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Methods to Increase Reproductive Efficiency in Cattle
W.J. Silvia
Department of Animal and Food Sciences
Project Description
There is now considerable evidence that lactating dairy cattle metabolize ovarian steroid hormones like progesterone at an accelerated rate. This is one factor contributing to poor fertility. This also affects the success of hormone based protocols for synchronization of estrus. In our first experiment, we showed that the concentrations of progesterone achieved in lactating cows using a CIDR device were much lower than in dairy cows or heifers. These concentrations are of questionable biological value. A second experiment is in progress to determine if the concentration of progesterone that results from the use of 2 CIDR devices will have more pronunced biological effect. This will be determined by measuring follicle growth by ultrasound and by measuring the concentration of LH blood samples collected during CIDR administration.
Impact
CIDRs are commonly used in the field to manipulate reproductive activity in dairy cattle. These data clearly show that CIDRs are able to maintain a significantly lower concentration of progesterone in lactating dairy cows than in the other groups. This implies that these cows metabolize progesterone more effectively than cows in other physiological states and may help explain why lactating dairy cows have such severe problems with fertility. From these data, new methods for the use of CIDRs may be developed.