- Milk quality has a large influence on the production and ripening of fine cheeses. The recent introduction of genomic techniques has contributed to our understanding of milk microbial ecosystems. A number of species of bacteria, yeasts and moulds have been identified in cheeses without describing their roles (positive or negative) and activities (production of aromatic compounds) in the cheese ripening process.
- Quebec’s cheeses often meet the highest standards and, at times, lack consistency in regards to quality. In addition, little is known about the indigenous microflora of fine cheeses from Quebec.
- The expected results, including the inventorying of natural species of Quebec cheeses, will allow us to determine the impact of the region on cheese microflora and to determine local cheese typicity….
Putting back to day 120 the insemination of cows in metabolic stress: an idea to validate for the health and profitability of the herds
- One of the recurring problems with dairy cattle diet is the marked increase in energy needs during lactation. High-producing cows are simply unable to ingest all of the energy necessary for production.
- Despite increases in food quality, dietary efficiency must also be examined as a function of physiology to minimize the consequences of this weight loss.
- Cows with a BHB blood level (ketones in the blood) of more than 1.2 mM/L are subject to acetonemia.
- Our cows’ productivity level is still on the rise with an average surpassing 9,000kg for Holstein cows and attaining more than 10,500 kg to reach the 90th percentile.
- These production levels are certainly a feat, but they also represent a risk. The biological barrier begins to makes its presence felt since, in high producers, dairy production is sometimes associated with reduced fertility….
- Dairy cattle productivity is influenced by the ways in which the animals are managed and their genetic potential.
- Through genetic improvement (traditional and genomic), we aim to improve performance by selecting the highestperforming versions of the genes. The traditional approach is to mate the highest-producing animals without taking DNA into account, while genomics
aims to select the DNA sequences that are associated with animals exhibiting the highest productivity levels.
- The general model involves having two copies of the best version of the gene, representing the best genetic combination. However, it has been found that certain traits react better to the cross-breeding of different species, most notably traits associated with health and fertility. This means that, for certain traits, the best combination is to have two different versions.
- Dairy production in Quebec and Canada is not based on the cross-breeding of species to promote genetic heterogeneity. Furthermore, it is contraindicated to aim for genome-wide diversification (all of the DNA that is found in each cell) because this would counter the genetic gains made in the last 40 years….
METABIOLAC Industrial Research Chair in metabolic activity and the functionnality of bioprotective lactic cultures
- In the coming decades, the agri-food sector will face a number of challenges, including meeting the food needs of a world population of more
than 9 billion individuals in terms of both quality and safety.
- The new market trends increasingly limit resorting to traditional microbiological barriers such as chemical additives and the use of antibiotics
as growth factors in animal production.
- The discovery of new generations of natural and safer antimicrobials that may be used throughout the food chain represent one of the most
- The scientific program for this chair includes 4 components focusing on the identification, characterization and exploitation of the antibacterial and antifungal activities of lactic acid bacteria in production and processing sectors….
This important research initiative aims to provide dairy farmers with concrete data and tools to optimize comfort, with a particular focus on stall housing, and to increase the longevity of dairy cattle. The chair also aims to improve recommendations concerning animal welfare to help farmers prepare for the implementation of the animal welfare component of the ProAction national program…
• Due to climate change, fodder production in the province of Quebec must be adapted.
• Timothy grass is a plant that grows well in cool climates, but the current climate is beginning to make it less advantageous.
• An alternative must be found to Timothy grass that is better suited to the growing conditions in Quebec…
Impact of Production Processes on the Microbiological Quality of Greek Yogurt and the Valorization of By-Products
- Greek yogurt has won the favour of consumers and now makes up the largest segment of the yogurt market.
- The dairy industry is in need of comparative data on the stability and safety of these types of high protein content (HPC) yogurts, produced by centrifugation or ultrafiltration, as well as valorization strategies for by-products.
- Cold HPC products contain more probiotics, but their subsequent stability is affected by the strain and the HPC process…
Improving EcoEfficiency in Milk Processing by Optimizing the Usage of Milk Components: the Case of Greek Yogurt
- Concentrated “Greek-type” yogurt has seen an exponential increase in consumption but has consequently generated acidic whey that is managed as residual matter.
- This environmental problem, the costs of development related to Greek yogurt production and its value to consumers raises questions about ecoefficiency (EE) in milk processing.
- This project allows for a more specific comparison between the environmental impact (using a life cycle assessment (LCA) approach) of ultrafiltration before filtration (UF-MILK) and post fermentation (UF-YOG).
- The ultimate goal of the research is to develop decision-making tools for industrial dairy processors, based on life cycle assessment data and the notion of industrial ecology, in order to optimize the use of milk’s natural components…
- One of the challenges in the milk processing industry is producing high quality cheeses on a consistent basis.
- Many factors influence quality, including the microbiological composition of milk and the effectiveness of starter cultures and bacteriophages.
- This project investigates these factors using a “systems biology” approach to better understand the impact of the microbiological network on cheddar production…
We have developed a farming practices assessment tool that targets ten key elements of calf and heifer management. The elements chosen were calving management, newborn care, painful procedure management, colostrum management, mother-calf separation, feeding and housing calves, weaning, feeding and housing heifers, and general follow-up. The targets and indicators for each of the key elements were validated by a panel of experts and weighted on the basis of the experts’ opinions and scientific literature. The tool was tested on 28 dairy farms in Quebec to determine its feasibility and the reproducibility of results between two observers. The farm assessment included an interview about farm management and measurements of the environment in the cow barn. The results and recommendations were discussed with the farmers. The usefulness of the tool was assessed by the farmers themselves. The five objectives initially set for the success of the tool were achieved: 1) keep visits to no more than 3 hours, 2) easily collect data and obtain high reproducibility rates in the qualitative variables measured, 3) help to detect problems and discuss these problems with farmers, 4) convince users of the usefulness of the tool to identify the elements of calf and heifer management that need to be improved, and 5) encourage the adoption of recommended farming practices. The results of this project show that voluntary improvements in animal welfare can be facilitated with the use of appropriate tools to help farmers adopt recommended practices.
Paratuberculosis is an ailment that is difficult to diagnose prior to its terminal phase. The disease results in sizeable economic losses, even in the absence of clinical signs. A variety of risk factors have been identified on dairy farms. A risk factor questionnaire that is based on known factors is currently available in Quebec to help dairy farmers facing the disease. The goal of this study was to validate the relevance of such a practice and the correlation between a score obtained on the questionnaire and the clinical prevalence in dairy herds whose status—infected or not—is known. About thirty herds having had cases of the disease and an equivalent number of control herds were chosen. A maximum of 30 cows aged 3 years and over were randomly selected from among these herds, and a blood enzyme-linked immunosorbent assay (ELISA) as well as a Mycobacterium avium ssp. paratuberculosis culture of manure were performed. The risk factors questionnaire was then completed with the farmers. Afterwards, the score obtained on the questionnaire was compared to the intra-herd prevalence of the disease. The anticipated potential outcomes were to estimate, using the questionnaire, whether a herd with an unknown status was infected or not and whether the level of infection was serious or mild. This would enable dairy farmers to use a low-cost method to determine whether paratuberculosis was an underlying subclinical problem in their herd.
In Canada, several yogourts are produced containing commercial polysaccharides (PSs) as stabilizers. Bacteria that produce exopolysaccharides (EPSs) are also increasingly used in yogourt production due to their ability to improve its texture, viscosity and water retention. Until now, studies on the role of EPSs pertained to systems that didn’t contain commercial PSs. The proposed approach was to 1) determine the types of interactions that occur between EPSs and PSs in model dairy systems and in yogourt, 2) verify the biocompatibility of strains and compare yogourts with and without EPSs, and 3) evaluate the impact of the composition of the milk mixture and the production parameters on the rheological properties of yogourts. Our work confirmed that there is no direct correlation between the amount of EPSs and the resulting improvements. The structure of EPSs (charge, stringy nature) and their interactions with molecules in the environment influence their ability to modulate the sensory properties of yogourts. A model dairy system was developed and makes it possible to study the effect of proteins and EPSs on the structural organization of yogourt. Certain EPSs, although they significantly modify the structure of yogourt (marked phase separation), yield more firm yogourts without syneresis, proving the importance of the structural characteristics of each EPS. Strain pairs that produce biocompatible EPSs act in synergy to improve the properties of yogourts. This project therefore offers considerable opportunities for improving the quality of fermented dairy products and developing new products.
Approximately 10 kg of buttermilk powder are generated from the production of 100 kg of butter. Currently, buttermilk is used mainly in food formulation (e.g., bakeries and cookie factories), where it competes with powdered milk and whey. Although it has a similar composition as skim milk, certain characteristics of buttermilk limit its technological uses. Much work has demonstrated that the functional properties of buttermilk, other than its emulsifying power, are often inferior to those of skim milk. Furthermore, the incorporation of buttermilk in cheese milk reduces the firmness of the curd and the retention of species. Scientific literature suggests that phospholipids, protein-lipid complexes and other minor lipids are the reason behind these problems. We can therefore make the assumption that separating the lipids from the buttermilk would make it possible to restore the technological properties of the lean part while at the same time producing a value added extract. The purpose of the project was to develop an integrated approach that would make it possible to completely use buttermilk solids in dairy and food processing. The project also aimed to better understand the phenomena or interactions responsible for the distinctive technological characteristics of buttermilk. Lastly, it sought to propose a new technological approach that would make it possible to use buttermilk in cheese factories and provide preliminary data on the potential for using buttermilk and its parts as functional food ingredients.
The objective was to study the variability of milk constituents based on management and dietary factors on the farm. An analysis of more than 9 million observations as at the test date showed that cows fed total mixed ration produced more milk, fat, protein and lactose, and less urea than those who received forages and concentrates separately. An analysis of data from more than 400,000 cows and 2.4 million feed rations showed that the concentration of urea varied depending on breed and increased with parity. On the other hand, an analysis of 923 milk samples collected from cows and the reservoirs of 33 farms suggests that there is a correlation between the amount of omega-3 fatty acids and the feeding system, and the presence or lack of corn silage in the rations. Relationships were also observed between conjugated linoleic acids (CLAs) and C18:1 trans fatty acids, and the presence of grain corn in the ration. As for the amount of omega-6 fatty acid and the percentage of casein in the total protein, no significant correlation was observed with the presence of corn silage or grain corn. However, considering the large number of variables, additional statistical analyses are necessary to draw definitive conclusions.
Milk is a complete food that provides a good source of calcium and protein, but the milk fat (MF) it contains is often viewed negatively. Among the most studied compounds in MF, conjugated linoleic acids (CLAs) have received a lot of interest due to their potential health benefits. However, the mechanisms of action of CLAs have not yet been established, and scientific evidence remains necessary to accept the claims. As part of this research project, we used innovative in vitro models to study the metabolism of dairy-based CLAs. We also assessed the impact of these compounds on the balance of the digestive ecosystem. The results revealed that all fatty acids (FAs) in milk were 79.6% digestible and that CLAs seemed to be highly digestible compared to other long-chain FAs. On the other hand, our results showed that short-chain FAs inhibited lactobacillus growth and that this inhibition increased with the concentration of FAs and the length of the carbon chain. However, growth stimulation was observed with other probiotics, namely bifidobacteria, when FAs were used in low concentrations. On a scientific level, this project made it possible to acquire priceless fundamental knowledge about the digestive metabolism of dairy FAs and their positive effects on colonic microbiota. This new information can continue to improve the image of dairy MF among consumers and develop new high-value-added products likely to increase the competitiveness of Quebec’s dairy industry at the national and international level.
This project was developed in order to verify whether the current recommendation of drying cows for 60 days is still suitable for today’s herds or whether a 35-day dry period management approach would be more appropriate. To assess all possible impacts, four studies were conducted. The first two studies took place on 13 commercial farms and included a total of 850 cows. The objective of the study was to assess the impacts of a 35-day dry period management approach on milk production and composition, health and metabolic diseases as well as cow reproduction. The purpose of Study 2 was to determine the economic impact of this practice in a Quebec context. Study 3 verified the effects of a shorter dry period on cell renewal and cell activity in the mammary gland. Study 4 measured the effects of a diet specific to a short dry period management approach on feed efficiency and digestibility. The results of all of these studies suggest that, in first calf heifers, the additional milk obtained by continuing to milk the heifers for an additional month compensates for the slight decrease in production during second lactation. In cows in third or more lactation, there is no impact on milk production during the next lactation. There are no major impacts on metabolic diseases or reproduction following a short dry period. Cows that have undergone a short dry period management approach consume more dry matter at the beginning of lactation and mobilize less body stores. A 35-day dry period had no impact on cell renewal or cell activity in the mammary gland at the beginning or in the middle of the following lactation. From an economic point of view, a short dry period management approach seems to be advantageous for a farm with average production costs, especially if the farmer purchases the additional quota to cover the additional production. However, the results vary for each farm.
This national organization’s mission is to combat one of the most costly diseases of dairy herds. To do this, it crossed provincial borders to expand its operations into eight universities and two research centres. In just five years, the Network grew its team by nearly 65 researchers and collaborators throughout the country. It has carried out over 27 research projects covering a wide range of topics that include vaccination, virulence factors, resistance to antibiotics, farm practices, diagnostic methods, behaviour, welfare, genetics and more. These projects, some of which generated practical applications and patent-pending discoveries, were the subject of more than 50 scientific publications to date. They were carried out with the help of over 100 students, including 45 graduate students (17 candidates for master’s degrees, 15 doctoral students and 13 postdoctoral fellows). The organization is viewed as the leading expert on the future of udder health in Canada.
Industrial Research Chair NSERC-Novalait-DFC-PLQ-MAPAQ-Valacta on Nutritional Control of Milk Components
This research program was established to help dairy farmers better manage the marketing of their products. It aims to help farmers meet consumers’ needs and develop control mechanisms for milk production and composition that align with the objectives set by the dairy industry.
As a result of this chair’s research: it is now possible to…
Producing cheeses such as Cheddar, Camembert, mozzarella and Swiss of consistent quality on an industrial scale is a central concern for cheese makers. Understanding the factors that cause variability in technological and organoleptic properties would enable a better control of the product and limit economic losses. The biochemical and metabolic activity of lactic ferments and secondary flora have an impact on the organoleptic qualities of cheeses. To meet the challenge of improving cheese quality, the Industrial Research Chair focused on developing an innovative approach to studying cheese making and ripening—first by advancing technological knowledge on cheese and then by expanding knowledge on the expression of cheese-related microbial metabolism through implementing a research field based around “omic” methods. The Chair helped consolidate a centre of expertise and knowledge on cheese and bacterial and fungal cultures in addition to training highly skilled future professionals who will form the next generation in industry and research. The main results were obtaining the typological profile of four types of cheese during ripening to better understand the direct relationship between a cheese’s composition and its final properties, and an in-depth analysis of the evolution of various microbial species present in cheese during the aging process to fully understand their contribution to the aging of Cheddar and Camembert. This information will help guide the dairy industry in its efforts to control the effects of various microbial communities on the organoleptic characteristics of the finished product.
There is a marked enthusiasm for fine cheeses in Quebec—the province sees the highest average weekly spending for them in all of Canada. The project aimed to understand the microbiological and technological typicality of various Quebec milks and fine cheeses and use these results to regulate the quality of manufacturing and enhance Quebec products. The particular management of a dairy herd changes its milk’s microbial and chemical composition in addition to having a direct impact on its technological properties. Thus, milks used for the manufacture of fine artisan cheeses may contain a biodiversity of dairy yeasts and molds (Y&M) specific to Quebec, with unknown exploitation potential. The results clearly showed that some local milks have unique characteristics, whether because of the composition of the milk or the secondary microflora of Y&M, which turned out to be very important.
Developing products to maintain the viability and activity of probiotic bacteria is a genuine technological challenge for manufacturers who wish to market functional foods. Cheese has advantages such as higher pH, a denser matrix and a higher fat content that can increase the likelihood that probiotic bacteria will survive the production and ripening process as well as transit through a human stomach. The main goal of this project is to determine the conditions in which the functional properties of probiotics in cheese can be made and kept viable. A model curd reproducing an environment similar to that found in Cheddar cheese was used to assess the combined effects of pH, salt/moisture percentage and ripening temperature on the survival and growth of various commercial probiotics during the aging of Cheddar. The viability of the Bifidobacterium animalis ssp. lactis BB-12 and Lactobacillus rhamnosus GR–1 strains on their own as well as in co-culture was determined in the context of a Cheddar manufacturing process and during the 12-week ripening of the cheese at 4°C and 8°C. The viability of probiotic bacteria in cheese was also assessed using two quantification methods: the classic method of counting on a light box and the molecular method known as qPCR/PMA. The results provided a better understanding of the factors that affect the viability and activity of probiotic bacteria in cheese as well as the development of molecular tools dairy processors can use to determine the viability of probiotic strains and ferments and to perform strain typing.
The increase in cheese production and the repeated use of the same lactic ferments increases the risk of fermentation failure due to the presence of phages in milk. Several strategies are now available to mitigate phage-related problems. Nonetheless, phages are still the main cause of delays in dairy fermentation and fluctuation in the quality of certain cheeses. Over the years, the phage problem has often been passed on to lactic ferment providers. Indeed, a manufacturer must distribute ferments that are insensitive to most phages and monitor phage populations. However, it is also important for processing plants to use proper control strategies in parallel, including an effective cleaning procedure. Ideally, the sources of contamination should also be known so they can be controlled optimally. This project aimed to identify phage sources in plants and in farms, study airborne phage behaviour and assess the effectiveness of physical and chemical methods to control phages.
Dairy products are known for their high nutrient density and considered to be privileged vehicles for transporting bioactive molecules. The development of functional dairy products will allow the dairy industry to produce food adapted to the nutritional requirements of consumers. However, adding bioactive compounds to cheese poses a significant technological challenge because of anticipated losses to whey (up to 95%) and the potential impact on sensory qualities. This research project aims to develop effective technology for integrating physiologically active compounds into the matrix of cheese. The results will provide tools to farmers to accelerate the development of new products. Work focused on adding probiotic cultures and phenolic compounds to cheese as well as developing single and double emulsions for encapsulating fat-soluble and water-soluble compounds. Despite high retention in the curd, probiotic cultures added to milk are salt sensitive and show a significant loss of viability during the first days of storage. The phenolic compounds show a high affinity for the casein fraction of milk, and retention in the cheese curd is excellent. Phenolic compounds affect the kinetics of formation and the characteristics of curds, but the performance indicators are the same. The formation of single and double emulsions was optimized to facilitate integration and retention of active compounds in cheese.
The development of new natural antimicrobials that may reduce the incidence of pathogens in food and prolong its shelf life remains an urgent issue in the food industry, including the dairy sector. The goal of this project is to identify, characterize and exploit new food antimicrobials for long-term dairy product conservation, replacing conventional additives. Various peptide fractions were obtained either by enzymatic hydrolysis of whey protein or by aqueous extraction from various cheese matrices. Analyzing the biological activity of these fractions showed significant inhibitory bactericidal or bacteriostatic activity against Listeria and Escherichia coli. Bacterial reductions of up to 5 logs were achieved, particularly with mozzarella and Gouda cheese extracts. The most active fractions were subjected to physicochemical and molecular characterization. In addition, a pilot process of fractionation and concentration through nanofiltration was developed for the large-scale preparation of a peptide fraction with strong inhibitory activity. The antimicrobial activity of the product obtained was validated in a model curd against L. monocytogenes. New high added-value products were thus developed and can be used as bioconservation agents in the dairy industry. This approach is not only an insurance policy for consumers, but also a proof of quality that would enhance the reputation of Canadian dairy products and therefore their profitability.
The reproductive performance of cows is an important part of dairy farm monitoring and agricultural business profitability. Breeders have been noticing a decrease in the fertility of dairy cows for years now. Uterine infections contribute significantly to the declining fertility of dairy cattle because they are linked with the interruption of the normal function of the uterus and ovaries. Although an endometritis diagnosis is only based on the presence of visible flow from the vulva, a large percentage of cases are not detected and remain untreated. The main objective of this study was to validate the use and interpretation of the leukocyte esterase test for diagnosing clinical and subclinical endometritis in dairy cows on the farm. For this study, a quick on-farm esterase test was used on all cows from 18 herds over a one-year period (about 1,200 cows). The quick esterase tests were compared to the reference test, endometrial cytology. Preliminary results show that cows with a positive esterase test had a significantly (p=0.05) lower success rate at first breeding than those who tested negative. These results will enable quick diagnosis and treatment of subclinical endometritis on the farm and, in turn, will increase the chances of conception following calving.
Most antibiotics used on dairy herds are for treating and preventing bovine mastitis. In North America, antibiotic treatment at drying-off is universally recommended for all of a herd’s cows after the last milking. New non-antibiotic products are now available to combat mastitis, including internal sealant or selective bacterial culture media usable on a farm (Petrifilm®). Some dairy herds are able to maintain a somatic cell count under 250,000 cells/ml. These properly controlled herds could receive selective intramammary treatment during the dry period without a negative impact on their overall health or milk production. The benefits of selective treatment during the dry period include reduced costs, a lower amount of antibiotic used and, consequently, a lower risk that there will be a presence of antibiotic residues and that bacterial resistance will develop. A total of 720 cows from 16 herds met our inclusion criteria—358 in the culture group, and 362 in the control group. A total of 47% of culture group cows did not receive antibiotics during the dry period. The proportion of infected cows at calving, the incidence of clinical mastitis during early lactation and milk production were not significantly different between groups. A comparison of economic margins between the control group and the culture group concluded that the savings associated with the use of selective antibiotic treatment during the dry period was $8.70 per cow. The Petrifilm tests were adequately reliable. A questionnaire administered to participating dairy farmers showed that all farmers found interpreting the Petrifilm plates to be easy or very easy.
Several studies have demonstrated the economic benefits of having ideal fodder on dairy farms. However, the methods to efficiently produce and use fodder are slow at being implemented optimally within Quebec businesses. Several factors may be involved, including the dearth of tools available to adequately identify areas for improvement in fodder management and thus select the appropriate corrective action. An evaluation grid to diagnose the valuation of fodder in dairy farms was therefore developed.
The grid was designed by a group of six experts and validated with seven agricultural stakeholders. In 2010, 20 Quebec dairy farms put it to the test. Using four main indicators and nine secondary indicators, four aspects of fodder valuation were assessed: fodder production, fodder production cost, the efficiency of harvesting sites and the use of fodder by the herd. The grid proved functional under every fodder, stabling and feeding management modes encountered on the farms that participated in the test. It met the expectations of advisors and farmers. It identifies the strengths and weaknesses of businesses and allows a diagnosis. By contributing to the improvement of technical and economic performance in fodder management, the grid will be a valuable tool to increase the profitability of Quebec dairy farms.
In this project, exploratory research on the motivations for and obstacles to the adoption of four fodder management practices also showed that the mere presence of the evaluation grid encouraged the use of the practices proposed to participants. The study also highlighted the role of advisors in the adoption of agricultural innovations.
Fodder that is rich in rapidly fermentable energy helps increase the efficiency of nitrogen utilization by ruminants and reduces the amount of nitrogen excreted into the atmosphere. This research project showed that it is possible to increase the rapidly fermentable energy content of fodder by increasing its nonstructural carbohydrate content, which improves the milk production of cows through increased food intake and more efficient use of nitrogen. This strategy can reduce nitrogen emissions by 10 to 15% and result in net gains of more than $15 million annually for Quebec milk farmers. The project demonstrated the economic and environmental benefits of using nonstructural carbohydrate-rich fodder on Quebec dairy farms. The results: 1) enabled the development of agronomic recommendations for producing nonstructural carbohydrate-rich fodder within Quebec dairy businesses; 2) showed an improvement in the nitrogen use efficiency in more carbohydrate-rich fodder, with a corresponding reduction of nitrogen losses in the environment; and 3) showed that near-infrared spectroscopy can be used to predict the various nonstructural carbohydrates of fodder produced in Quebec.
Impact of Process Dynamics and Composition of Fermented Dairy Products on their Stability and Rheological Properties
Industrial production of yogourt increased by 184% in Canada from 1998 to 2011. Several factors dictate the properties of the acidic gels obtained, including the type of bacteria (diverse acidifying capabilities, producing or non-producing and type of exopolysaccharides), milk composition (total solids, fat content, serum protein / serum casein ratio) and manufacturing process conditions (homogenization, heat treatment). So far, most of the work has been done on set yogourts, but the most widely consumed type of yogourt in Canada is stirred yogurt. Unlike set yogourt, which is formed without stirring in the container it will be sold in, stirred yogourt is obtained by breaking up the gel after fermentation in a tank. During the process of stirring and travelling through piping, pumps and filling nozzles, the product is subjected to shear stress that breaks down the protein matrix, which adversely affects the rheological properties. Once potted, the stirred gel is put into cold storage, and the gel particles can interact again to partially restore the gel’s properties. The crucial question is whether, at the end of the packaging process, the yogourt will have acceptable texture properties, and how much of these properties will be recovered inside the pots. The project, which is based on complementary expertise in physical chemistry and fermented dairy product manufacturing combined with a process engineering approach, will raise the level of understanding of the role of each action (milk standardization, heating, cooling, stirring, pumping, etc.) performed during the manufacture of yogourt on its quality. For the first time, a pilot test system that can mimic the steps of the process that determine the quality of the finished product will be developed and validated. It will be possible to correlate the effect of composition and manufacturing steps with the final product’s quality.
Factors affecting the composition of the microbiota of raw milk are not yet well understood, but farm management practices such as feeding, milking, and sanitation have a definite influence on the microorganisms of interest for cheese making and alteration. The specific composition of raw milk microbiota will have a major influence on the subsequent conversion of milk into dairy products such as cheese, since these microorganisms have an impact on milk quality and shelf life. According to some Canadian dairy industry stakeholders, the microbiota of silage used for cow feed could be a source of contamination during the processing of milk. However, the rate of bacterial transfer from silage to milk is not well understood, since this step is strongly influenced by the quality of the silage (silage management during storage and opening), cow behaviour in terms of contact with bedding (udder contamination rates) as well as the level of hygiene during milking. The presence of undesirable microorganisms in silage can be avoided by using lactic inoculants to provide homolactic bacteria or heterofermentative lactobacilli. Inoculants are also chosen for their heat tolerance, and can survive in the rumen and potentially withstand the heat treatment of milk. The impact of heterofermentative lactic inoculants on the transformation of milk into cheese is not yet well known. However, these lactobacilli species were found in Cheddar cheese. An increased presence of thermoresistant acidifying bacteria (lactic and acetic acid) in milk can change the speed of acidification during the cheese making process and the organoleptic qualities of the cheese. This suggests that the use of homofermentative inoculants in silage and their transfer to cows leads to accelerated acidification of milk, and thus to difficulty controlling the process. The use of heterofermentative inoculants is thought to lead to the production of undesirable metabolites in milk and cheese or the production of gas causing slit-type defects.
Development of Innovative Green Biotechnology for the Valorization of Cheese Co-product : the Biobac Process
Our project, which started in January 2014, will provide the milk processing industry with a new solution for recovering liquid residues from cheese-making facilities. The main goal of our research is to transform the lactose in whey into 2,3-butanediol (BD) through a fermentation process known as Biobac which uses genetically enhanced bacteria. Usually, two steps are necessary to extract BD from lactose. The substrate is first hydrolyzed into glucose and galactose, and the resulting monosaccharides are fermented into BD. Our process will use an improved non-pathogenic bacterial strain that can transform lactose into BD directly. BD is a substance with many industrial applications, including the manufacture of polymers, explosives and pharmaceuticals. To validate the economic and environmental feasibility of recovering whey, a life-cycle assessment coupled with an eco-efficiency index will be conducted. This interdisciplinary project initiated by the Université de Sherbrooke involves the engineering and science departments.
Adjusted Milking during Transition Periods to Better Control the Negative Energy Balance and its Consequences
Energy imbalances in early lactation are the cause of many health, production and reproduction problems, which represent the main reasons for culling in dairy herds. The conventional approach to controlling energy balance is increasing the energy density of the feed served during the peripartum period. However, this increase in ration density is costly and increases the incidence of certain diseases (e.g., displaced abomasum). Another option to reduce the imbalance between energy intake and energy needs would be to temporarily reduce the latter. Recent research suggests that reducing the amount of milk collected in the first five days in milk would suffice to limit metabolic imbalances and improve cows’ immune status. The goal of this study is to measure the impact on the energy balance of incomplete milking of multiparous cows during the first week of lactation in a commercial context and its consequences. The proposed study is a randomized clinical trial on 800 multiparous cows from around 10 commercial dairy farms. Data collection has already begun and will extend over one year. The results of this project will confirm the usefulness and applicability of an innovative energy balance management method during the transition period.
This project aims to better understand the factors influencing the technological quality of milk destined for cheese production. It is based on the hypothesis that mechanical treatments promote the release of compounds from the milk fat globule membrane in milk’s soluble phase. The overall objective of the project is to highlight the effect of mechanical treatments applied to milk (skimming, pumping, churning, homogenizing) on the properties of casein micelles, including their coagulation ability. The project has five specific objectives: 1) identify and characterize the soluble components of milk that can be adsorbed to the surface of casein micelles during renetting and interfere with gel formation; 2) demonstrate the occurrence of interactions between curdled casein micelles and soluble milk components; 3) characterize the effect of the soluble components freed during the mechanical treatments on milk’s coagulation potential and on the characteristics of curds; 4) determine the impact of the intensity of mechanical treatments on milk’s coagulation potential and develop predictive models; and 5) develop new approaches to reduce the intensity of mechanical treatments applied to milk (prevention) and new processes to remove soluble components that have a negative effect on milk’s coagulative properties (correction). This project will develop new knowledge on the factors that optimize the coagulation properties of milk used to make cheese. Prediction tools will be developed to better anticipate the behaviour of milk at a dairy plant, and new technological approaches and processes to prevent or correct the negative impact of mechanical treatments will be proposed.
The connection to local Quebec products is taking on increasing importance for consumers. However, although Quebec fine cheeses often meet the highest standards of quality, they are sometimes inconsistent in doing so. These fluctuations come from the milk used to make them; its microbiological composition and technological properties. A previous study by our team showed that the diversity and quantity of yeast and molds found in Quebec raw milk are greater than first anticipated. The dominant species vary between farms, but the profile observed in a given farm shows good consistency over a five-month period. Furthermore, our study of 19 local cow milks has shown that milks from different origins and of different compositions affect the colour and appearance of the fungal microflora growing on the surface. Also, some Quebec herds were previously identified as unique for the chemical composition of their milk, the composition of the fungal microflora, their geographic location and/or the breeding method used.
Subclinical ruminal acidosis is often identified as an important risk factor for low milk fat syndrome. This metabolic disorder is a major problem in dairy production because it is associated with significant economic losses resulting from inhibition of mammary lipogenesis, decreased milk production volumes, a reduction of feed efficiency and premature culling. These problems are magnified by the difficulty of diagnosing this metabolic disease. Recent studies have highlighted the possibility that increasing the dietary cation-anion difference (DCAD) and/or adding a K2CO3 supplement to feed could prevent changes in ruminal biohydrogenation pathways which are usually associated with concentrate-rich feed, are often the cause of acidosis problems and have significant inhibitor effects on the synthesis of milk fat. However, it is unknown whether the observed results are due to an increase in the feed’s DCAD or to a direct effect of potassium or carbonate ions on ruminal fermentation. Consequently, this project aims to identify nutritional strategies to reduce the potential negative impacts of concentrate-rich diets which may cause subclinical ruminal acidosis problems affecting cows’ production performance in early lactation. Moreover, it has been shown that certain fatty acids of milk have potential for identifying the animals most at risk of being in or developing a state of subclinical ruminal acidosis. Current work therefore aims to study these relations under various conditions to assess and/or enhance their robustness and enable the development of a diagnostic tool applicable to the farm. Work began in September 2012 and will continue until 2016.
Since 1928, we have known that bacteria found in the rumen of cows produce vitamin B. Since real vitamin B deficiencies that can lead to death are extremely rare in adult animals with a functional rumen, it became generally agreed that these vitamins did not need to be taken into account when formulating feed for dairy cows. Over the last two decades, however, several studies have demonstrated that high-producing dairy cows could benefit from vitamin B supplements—but the response to these supplements varies. One of the great unknowns modulating this response is definitely the amount of vitamins available to the cow. Vitamin B is synthesized by rumen bacteria, but we know almost nothing about the factors that regulate this synthesis, especially in dairy cows. The goal of this project is to determine dietary intake, ruminal synthesis and duodenal flow of vitamin B under various nutritional management conditions to identify the nutritional factors that have the greatest influence on the amount of vitamin B available to the animal. The project’s expected results are 1) the identification of the critical factors affecting the synthesis and availability of vitamin B to the cow and 2) a database on the vitamin B content of food, the apparent synthesis in the rumen and the duodenal flow of these vitamin under various feeding conditions in order to develop a model to predict the amount of vitamin B available to the cow depending on nutritional management. Vitamin analyses in samples from several projects are underway, and the database is under development.
Knowledge and control of direct and indirect costs are among the most important management factors that a farmer can use to improve their business’s profitability. As dairy income is almost fixed because of the supply management system, increasing profits requires good management of short-and medium-term production costs.
Health, reproduction and management are key factors to maintain an optimal profit level. However, farmers do not have a clear picture of the impact of problems related to health (e.g., mastitis), housing (e.g., foot, leg and locomotion problems) or reproduction and their effects on a cow’s lifetime profitability. This is evidenced by the fact that these problems are linked to the main causes of involuntary culling in the past decade, and that they have remained roughly as frequent.
In Quebec, Valacta collects information on the production and diet of approximately 4,500 and 1,500 herds, respectively. DSA records data on the health of cows from around 1,500 herds. Agriculture and Agri-Food Canada, Valacta, Université de Montréal and McGill University collaborated to integrate the two databases and facilitate a lifetime analysis of production and food, raising, breeding and health events costs. This created a structure to visualize and interpret the factors contributing to profitability. A better understanding of these factors enables the use of visualization methods using large amounts of data to help farmers and their advisors make informed decisions.
Recent studies have shown that structural characteristics contribute significantly to the physiological impact and health effects of dairy products. Interaction with the matrix of products provides protection for components during digestive transit. This project is part of a process to identify nutritional synergies and the protective effects of dairy products on the nutrients of other food groups. It will help better understand and document the impact of these interactions on the bioavailability of calcium and polyphenols as well as the synergistic effects of milk’s various components on the physiological responses of polyphenols. The new knowledge generated by this project will be used by all stakeholders in the dairy industry. The first benefit of this project will be to increase the consumption of milk and dairy products after their synergy with the bioactive molecules of food is demonstrated.
The lactation cycle of dairy cows must include a period without production, called the dry period, so that optimal milk production can be achieved during the following lactation. Although this period is very important for the renewal of udder cells, the cow is very vulnerable to new infections during the active involution that follows the end of milking. It was established that the risk of intramammary infection at calving increases by 77% for every 5 kg of milk produced over 12.5 kg during the last day of milking. Since nowadays it is not uncommon to dry off cows that produce over 30 kg, it is clearly advantageous to reduce milk production before the dry period. The most commonly used method, dietary restriction, creates a metabolic stress. The goal of this project was to develop new approaches to reduce milk production come drying-off time and accelerate the involution of the mammary gland without disturbing cows’ metabolism. Two types of approaches were explored: the first was to reduce milk production at the time milking was to stop by decreasing the strength of the lactogenic signal, and the other was to accelerate the expression of mammary gland regression mechanisms. Decreasing the strength of the lactogenic signal using a prolactin inhibitor, quinagolide, rapidly reduced milk production and accelerated involution without disturbing the cows’ metabolism and immune resistance. A drastic food restriction also reduced milk production and accelerated involution, but caused metabolic stress and induced immunosuppression. A short-day photoperiod also helped weaken the lactogenic signal and caused a moderate decrease in milk production. Lastly, intramammary infusion of casein hydrolysates on drying-off day accelerated the involution of the mammary gland.
The Chair is part of a sustainable development approach that aims to increase the efficiency of dairy processing methods to optimize the economic, environmental and social benefits of the dairy sector in Canada. Membrane separation processes, which are ubiquitous in milk processing, have been targeted as a study model for our work for their significant impact on the dairy industry’s use of resources (water, energy and waste). The scientific program therefore targets the development of new knowledge on improving process efficiency by making better use of the natural constituents of milk (Axis I) and by optimizing the performance of membrane processes (Axis II).
The Chair’s work aims to:
− Identify new approaches to improve the use of natural milk constituents while minimizing the environmental impact of the processes
− Develop appropriate measurement tools and inventory methods for quantifying the effect of processes on dairy processing’s eco-efficiency parameters
− Apply the new tools to milk, whey, cream and buttermilk processing
The study models and scientific approach developed as part of this chair were defined to allow the development of cutting-edge expertise in milk processing efficiency as well as to provide a unique multidisciplinary environment for training highly qualified personnel for Canada’s milk processing industry. The Chair’s work will allow dairy processors to directly apply the results of research, thereby helping to improve the efficiency of their operations and quantify the effects.
In Quebec, less than 40% of cows reach their third lactation. While more than 90% of dairy herds live in stall housing, little is yet known about culling-related risk factors in this type of stall, especially those related to comfort. This project allowed us, for the specific case of stall housing, to 1) provide valid tools to evaluate comfort levels in the farm, 2) establish the impact of comfort on the prevalence of lameness, 3) learn about the risk factors associated with cow comfort, 4) learn about the farming characteristics and practices that promote longer useful life and 5) diagnose the factors related to adopting practices that promote comfort. The measure design stage confirmed, among other things, the usability of accelerometers to assess the level of comfort in stall housing. Providing training and using the developed comfort measurement tools resulted in a very good repeatability rate between observers. A method for evaluating lameness in the stall was also validated. Results obtained in 100 farms suggest that simple modifications to stalls (moving the tie rail forward and lengthening the chains) decreased the incidence of neck, knee and hock injuries as well as lameness. In addition, these results show that the main factors associated with involuntary culling of first- and second-lactation cows are the genetic index for CCS, divider height, stall width, flesh condition (<=2), the time spent lying down (between 9 and 15 hours a day), and the number of times they get up. Lastly, the project showed the importance of some factors at various stages of the comfort-oriented practices implementation process—for example, the advisors or “peers” at the education/awareness-raising stage.
Paratuberculosis is an insidious, contagious enteric disease caused by the intracellular bacterium Mycobacterium avium ssp. paratuberculosis (MAP). It is difficult to control, and can cause major economic losses when it infects a herd. This study aims to 1) facilitate the identification of herds affected by bovine paratuberculosis by validating a standardized method and 2) study the inflammatory and genetic markers associated with bovine paratuberculosis to better understand the evolution of this incurable disease.
For the first part, environmental samples from 24 farms as well as individual samples (serum [ELISA] and faeces [CFI]) from all adult cows were collected in summer and fall. The two sites most frequently identified as positive were boots (summer 15% and fall 12.5%) and the pit (summer 9.5% and fall 10.4%). The combination of samples from the pit and scourer and comparing the group of sick cows and the group of lean cows correctly identified all (8/8) positive farms upon ENV testing. When compared with the CFI, the ENV correctly identified 72% (95% CI: 43.4–90.3%) of positive herds. Our results suggest that the performance of the ENV was similar to that of the CFI and ELISA in identifying Quebec dairy herds in stall housing infected with MAP.
For the second part, the inflammatory profile of infected cows was studied. Although the so-called Th1 cellular immune response is effective in infancy during the silent infection period, this type of defense against intracellular pathogens wanes during the subclinical stage as the disease progresses. MAP thwarts its host’s immunological vigilance in some cows, which explains why antibodies against it are developed in such a delayed way (ELISA serum is still negative). The profiles are varied and do not always fit with the theorem that says that cows first have a Th1 response which, as the disease evolves, is replaced by a humoral response (Th2) manifested through a positive result in the ELISA test. Our analysis allowed us to characterize the inflammatory state in cows suffering from paratuberculosis and identify a genetic pattern associated with variations in the gene for osteopontin, a cytokine under study which is linked with chronic diseases.
The peripartum period is critical for dairy cows as they fail to meet their nutritional needs through their diet, which causes various metabolic and reproductive problems. The study aimed to assess whether a vitamin B12 and folic acid supplement injected during the peripartum period would improve the efficiency of energy metabolism, reducing production and reproductive problems related to a negative energy balance while improving the nutritional quality of milk. In farming conditions, the supplement increases the number of cows with a protein-to-milk-fat ratio above 0.75 by 8.2%, thereby reducing the risk of subclinical ketosis. It also shortens the first service interval by 3.8 days in multiparous cows but not in primiparous cows. The supplement increases vitamin B12 concentration in milk by 73% on average. Economic analysis shows that the supplement can be profitable in the Quebec context but should be evaluated on a case-by-case basis. The supplement had no significant effect on conception, but the results suggest a beneficial effect on follicular development: there were more pre-ovulatory follicles in treated cows, and the dominant follicle was larger.
MAPAQ has determined that Staphylococcus aureus is the main cause of raw milk cheese lots being rejected in recent years. Bacteriophages (or phages) are viruses that specifically target bacteria and destroy them. They are the most abundant biological entities on earth and help regulate bacterial populations. They are found in raw milk, including phages specific to S. aureus. Since the 1920s, phages have been used to prevent and treat bacterial infections, and this practice is still common in some countries. Phages are also used in various food and agricultural applications. Total elimination of undesirable bacteria is not required for the protective action to be successful. In addition, when used in the small amounts required, phages do not change the organoleptic properties of food. Thus, we propose using phages to control S. aureus in dairy products.
Food is a source of nutrients that are essential to human health. Currently, health foods or functional foods are developed by adding bioactive molecules to traditional foods, but very few studies examine how the molecular and structural organization of foods’ nutrients affects their health properties. Nutrients from food matrices must be bioaccessible and then bioavailable in order to reach vital organs and be metabolized. Dairy proteins have significant nutritional value due to being made from essential amino acids and branched-chain amino acids that have an impact on several postprandial metabolic responses. These proteins also play a key technological role in the yogourt manufacturing process. Polysaccharides can be added into yogourt to stabilize it. Previous studies have shown that starches, pectins (stabilizers used by the dairy industry) and beta-glucans (stabilizers of interest for being a source of fibre) can modulate protein digestion (in vitro and in vivo) and certain postprandial metabolic responses. Lipids are incorporated differently depending on the structure of foods (milk, cheese, etc.), and little information is available on how lipids behave in a gastric environment and what impact they have on digestive processes. The wide variety of existing cheeses (composition, texture, etc.) suggests a potential heterogeneity in the digestion and absorption processes.
Sylvie Turgeon, Michel Britten, Sylvie Gauthier and André Marette
This project is part of a series of studies to increase the value of buttermilk solids. It is known that incorporating buttermilk into rennet-type curds reduces their firmness and slows their rate of formation. Our previous work has shown that these effects are modulated by heat treatments applied during buttermilk production. We hypothesized that thermal co-denaturation of buttermilk and whey proteins may lead to the formation of complexes of which it may be possible to control the humidity. These complexes could improve not only the sensory properties of dairy products, but also, through their bioactive molecule contents, their potential as a health food.
The goal of this project is to develop new functional protein complexes by optimizing the interactions between whey proteins and buttermilk constituents. The project’s objectives are to: 1) characterize heat-induced interactions between whey proteins and buttermilk constituents; 2) assess the performance of protein complexes in cheese creation and in a yogourt-type acidic gel model; and 3) assess the health potential of the protein complexes following their gastrointestinal digestion.