POSTPARTUM REPRODUCTIVE MANAGEMENT OF DAIRY-COWS IN A LARGE FLORIDA DAIRY-HERD

Dairy cows (n=199) were assigned randomly at Day 14 post partum to a c ontrol group or a programmed reproductive treatment group (PRT). Cows in the PRT group received 8 ug of GnRH on Days 14 and 50 post partum a nd 25 mg of PGF(2 alpha) injected on Days 21, 34 and 57 post partum. C ows in the PRT group had a greater frequency of progesterone (P-4) con centrations > 1 ng/ml (50% vs 30%; P<0.01). Frequency of cows having P -4 > 1 ng/ml at both Days 21 and 34 post 4 partum was greater in the P RT group than in the control group (39% vs 20%; P<0.01). Accumulation of days with a palpable cystic ovary was lower in the PRT than the con trol group (11.4% vs 6.5%; P<0.05). The frequency of anestrous cows th rough Day 57 post partum was not different between the 2 groups. Cows that were anestrous had a lower body condition score throughout the po stpartum period than the cyclic cows (2.7 vs <3.0; P<0.01). Conception rate to first service, conception rate to all services, services per conception and days open were not different between the groups. Intens ity of estrus detection was low for the study based on a low estrus de tection rate (42%) and a low palpation pregnancy rate index (below 68% ) throughout the study period. Accuracy of estrus detection was low ba sed on the distribution of normal interestrus intervals for the study (19 to 23 d; 13.5%). It is concluded that programmed reproductive trea tments during the postpartum period are functionally effective relativ e to altered ovarian activity; however, potential advantages to such a system are not evident without good estrus detection practices in a l arge commercial herd.