Managing Reproduction in Dairy Cattle. II. Response of Cows to Progestogen Treated Herdmates during the Postpartum Period

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Abstract
Lactating Holstein cows (68) were handled as 1 unit but were either fed melengestrol acetate for 14 days or were contemporary controls. Cows that calved in a 21 day period were assigned to a treatment group. Those that calved during the subsequent 21 days served as controls and received no treatment. The alternating assignment was continued for 6 mo. Treated cows were between 14-35 days postpartum at the beginning of the feeding period. A decrease in days open (120-92) and services per conception (2.7-1.5) as compared with their previous year''s record occurred. The 34 control cows exhibited estrus over a period which coincided with that of 91% of the treated animals, with a slight delay in occurrence of 1st estrus. Control cows probably responded in some way to the treated cows in the early stages of the postpartum period.