Effects of feeding a yeast-derived microbial protein source on production, reproduction and behavioural parameters in transition dairy cows
Transition cows (3 wk before calving until 3 wk after calving) often suffer from negative energy and protein balances due to reduced feed intake, but increased nutrient demands for milk production. In Canada, up to 50% of transition cows may be affected by a metabolic (ketosis, hypocalcemia, and milk fever) or infectious (retained placenta, displaced abomasum, and uterine infection) disease. These diseases lead to production losses, infertility, animal welfare problems, and high culling rates of transition cows. The consequences of negative protein balance in transition cows have received little scientific investigations. Therefore, in this study, we propose to evaluate the effects of a yeast-derived microbial protein (YMP) on production (feed intake and milk production), reproduction (ovarian dynamic, gene expressions in ovarian granulosa cells and fertility), nutrient metabolism (energy, nutrients and minerals in plasma and gene expressions in the liver), and behavioural responses in transition cows. We hypothesize that YMP supplementations may alleviate the production, reproduction and welfare problems faced by transition cows. Data generated from this study may enable our industrial partner to market YMP as a new product for transition cows.