Insemination of Cows during Transition and Metabolic Stress

Project entitled:

Postponing insemination of cows in metabolic stress to Day 120: an idea to validate for the health and profitability of the herds

Highlights

• For some cows, the beginning of a new lactation is stressful, and oftentimes even more so in the case of high producers. Their energy metabolism is put under severe strain. Good producers are simply unable to integrate all of the energy necessary for production.
• Energy deficits in the cow, indicated by a high blood BHB level (> 0.8 mmol/L), have an impact on embryo development.
• A specific signature is noted in the embryo, including both transcriptomic, with an immediate effect, and epigenetic, with an effect over the longer term.
• This particular signature causes the embryo to switch to “energy-saving mode”, which can reduce its chances of implantation and lead to a different metabolic programming over the longer term.
• Postponing insemination from Day 60 to Day 120 postpartum for cows showing energy deficiency can help avoid this type of embryo programming.
• Prolonging the voluntary waiting period for cows with high BHB levels in their milk (> 0.15 mmol/L) results in a longer interval between calving in these animals.
• Partial budget analysis shows that the impact on net earnings of the herds is marginally positive. Given that there are no economic drawbacks, why not favour a practice that might prove beneficial for the herd in the long term?

Objectives

Thanks to economic and epigenomic analysis, the objective is to provide farmers with the tools needed to determine the energy state of lactating cows, as well as the economic and biological benefits and disadvantages of delaying the insemination of cows with a BHB blood level greater than 1.2mM/L.

Results and potential benefits

Genomic analysis demonstrates that on Day 60, the embryos are different in cows showing high BHB levels. Differences observed at the transcriptomic level indicate an adaptation that consists of switching to an “energy-saving mode”, which in the short term could compromise the chances of implanta- tion. In terms of epigenetic programming, i.e. over a longer timeframe, DNA modifications target genes that are particularly important for metabolism, which might suggest an adaptation to an energy-poor environment. Eight heifers from cows with high or low BHB levels were produced from these embryos and epigenetic analysis of their blood indicates approximately 2,000 differences. These indicators must now be sorted and validated before they can be used to monitor the herd and choose the heifers to be retained. These tools are essential for the development of factual management practices based on measurements taken at birth (biomarkers) and in milk (BHB) and quickly adopted by producers.

For the economic portion of the project, a partial budget was created to assess the impact of prolonging the voluntary waiting period for cows with a high BHB level in their milk at the time of the first control. Analyses conducted based on Lactanet’s database and scientific publications served as a basis for an assessment adapted to the Quebec reality for herds with average annual productions of < 9,000, between 9,000 and 11,000, and > 11,000 kg of milk. Results show that extending the voluntary waiting period for cows with high BHB levels in their milk only has a marginally positive impact on a dairy farm’s net earnings, regardless of its average production (< 9,000 kg of milk: $10.10/cow/year; 9,000 to 11,000 kg of milk: $17.30/cow/year; > 11,000 kg of milk: $8.60/cow/year). In this context, and in light of the potential benefit for the embryos, it would be advisable to adjust our practices.

Innovative aspects

• Discovery of a specific embryo signature, including both transcriptomic (short-term) and epigenetic (longer-term) components.
• Prolonging the voluntary waiting period between calving and subsequent insemination for cows experiencing metabolic stress could help avoid unfavourable embryo programming without having an impact on the company’s net earnings.

Professionals trained

This project resulted in the training of one Master’s student in genomics, Catherine Chaput, and one Master’s student in technical and economic management for the dairy industry, Catherine Couture. Both students are enrolled at Université Laval’s Department of Animal Sciences.

For further information

The results of the project have been transferred by an extension paper, posters session at the Quebec Dairy Cattle Symposium, the Novalait Forum Techno and at some local knowledge transfer day. Already published:

• Revue Le producteur de lait québécois, Janvier-février 2020, Repousser l’insémination chez les vaches en déficit énergétique; une idée validée. Pages 30-32.

Financial contributions

Partnership for innovation in dairy production and dairy processing (EPI 2015-2019):

• Fonds de recherche du Québec – Nature et technologies
• Consortium de recherche et innovation en bioprocédés industriels au Québec
• Novalait

Total budget: $282,866