Strategic fat supplementation can improve herd fertility
These were just two of the take-home messages from Adam Lock, from the University of Vermont in the US, during his presentation at the British Society of Animal Science’s international conference entitled: Fertility in dairy cows – bridging the gaps.
His paper asked the question: Can dietary fatty acid supplementation aid reproduction?
“Extensive metabolisation, by the rumen bacteria, has made the study of dietary FA effects on reproduction challenging,” he said. “And the specific mechanisms by which lipids/FAs impact on overall pregnancy rates have not yet been fully explored and understood,” he explained.
“More research needs to be done to better identify the most effective fat sources, whether from seeds, oils or ‘inert/protected’ sources.”
Feeding fats to aid dairy cow reproduction is of considerable interest at this time and this interest is based on several factors. These include the reduction in reproductive performance of dairy cows, which has driven the development of nutritional strategies to reverse this trend, and the fact that the use of dietary fat supplements will intensify as nutritionists strive to increase the energy density of diets to meet the requirements of the high yielding dairy cow.
“A variety of fat supplements have a beneficial effect on conception rates in lactation dairy cows and fats often improve pregnancy rates, although there is large variability in the responses observed. But the results are rarely negative,” said Dr Lock.
Improvements are thought to be as a result of the FAs meeting the animals’ essential FA requirement in early lactation and through the development of healthier ovarian follicles. Feeding FAs is also thought to improve the quality of the embryos produced and to reduce embryonic mortality through suppression of uterine PGF2α.
“Most data indicate that improved calving rate of fat-supplemented cows have been associated with an improved progesterone status of the cow. This increases the performance of the dominant follicle and corpus luteum and also helps the corpus luteum to survive and continue to produce progesterone during early pregnancy,” said Dr Lock.
“The size of the dominant follicle is often larger in lactation dairy cows fed supplemental fat.” FA supplements have also been shown to improve fertilisation rates and embryo development.
“In a trials with ET cows and heifers, the diet of the donor animal was more important that the diet of the recipient, suggesting that the dietary fat helps the cow to develop a robust embryo.” So, when should producers begin FA supplementation? “Ideally at least 28 days, preferably 40 days, before breeding. And feeding FAs pre-partum may also benefit reproductive tissues and health.”
