Wednesday, November 14, 2012
We often hear that cows fed AA balanced diets have better health and reproduction. A recent large dairy survey confirmed these reports. What is the scientific evidence to support these field observations? In the early lactation study reported in my previous SmartMail the authors also evaluated the impact of feeding an AA balanced, methionine enriched diet on embryo quality. Cows were superovulated with a modified 5d+intravaginal P4 and decreasing doses of Folltropin®.
The protocol used in this trial prevented us from evaluating the potential positive effect of amino acid balancing on the traditional reproductive indices (such as reducing the days to first service or differences in conception rates) documented in previous work. It is well documented, however, that a term pregnancy starts with a healthy embryo.
The cows fed the methionine enriched diets in this trial produced significantly more ova/embryos per corpus luteum. This resulted in 15% more transferable embryos per flush.
It is also noteworthy that cows with lower NEFA's at three weeks post-partum had a lower % of degenerated embryos, and a larger % of freezable and transferable embryos. These results partially support the idea that feeding AA balanced rations not only results in higher yields of milk components, but facilitates a more rapid return to positive energy balance with positive consequences on reproductive parameters.
In other words, healthier cows during the transition phase will have better reproduction. These results confirm what we hear from the field reports.