By Augusto Madureira
New research shows a missed heat alert early postpartum isn't just an inconvenience; it is one of the earliest signals of a cow's overall fertility, and a closer look at why so many “quiet” cows are being misread.
Why does early heat predict good fertility?
Across thousands of lactating Holstein cattle, cows that showed at least one estrus alert within the voluntary waiting period (VWP) were 3.4 times more likely to be bred off a spontaneously detected heat, had 59% greater odds of conceiving at first service, and were 75% more likely to be pregnant by 150 days in milk. This effect is independent of the herd, country, or monitoring brand, which tells us this isn't a coincidence of one farm's management.
A cow that shows a strong, detectable heat early in lactation has almost certainly already resumed normal ovarian cyclicity, and cycling early is tied to how well she recovered from the stress of calving: no uterine infection, acceptable body condition loss and no major metabolic disorders like ketosis. In other words, an early heat is the cow telling us her whole transition period went reasonably well. Cows that don't show heats early in lactation tend to carry that disadvantage through the entire lactation: lower conception rates, more days open, a greater chance of pregnancy loss later and greater chances of being removed from the herd.
A recent study evaluated 2,198 lactating Holstein cows across seven commercial monitoring brands from multiple countries and evaluated the accuracy of the monitor based on serial collection of blood progesterone, which was used as a gold standard to confirm ovulation and therefore determine if the cow is cycling.
Source : msu.edu