Profile of Milk Proteins

Project entitled:

Variation in the Profile of Milk Proteins

Kevin M. Wade, Daniel Ouellet, René Lacroix, Daniel Lefebvre, Daniel St-Gelais, Sylvie Turgeon, Yvan Chouinard


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.