Prostaglandin F 2α usage in a dairy reproduction program for treatment of unobserved estrus, pyometra and ovarian luteal cysts

Abstract

A retrospective study was conducted to evaluate the outcome of 223 prostaglandin F 2α (PGF) treatments given to lactating Holstein and Jersey cows over a 44-mo period. The cows were part of a commercial dairy herd. Treated cows were given PGF (25 mg i.m.) because they had not been observed in estrus or because they had been diagnosed as having a luteal cyst or pyometra. Outcome of treatments was assessed for frequency of response to treatment (the detection of estrus), time interval to detection and pregnancy outcome of breedings at PGF induced estrus. Of the 223 administrations of PGF, 70% ( 156 223 ) were given for unobserved estrus, 12.1% ( 27 223 ) were given for cystic ovarian disease and 15.2% ( 34 223 ) were given for pyometra. Estrus was detected in 55.3% ( 120 217 ) of cows over a period of 36 to 130 hours after PGF administration. Interval to estrus and response rates were not influenced by the reason for treatment. Mean time interval to response was 79.1 h. Time interval for response was affected by season (P < 0.01) housing location (P < 0.01) and lactation number (P < 0.05). Insemination was performed following 157 of the treatments. For cows treated for unobserved estrus, insemination was performed in response to estrus or at 80 h if no estrus had been previously seen. Of this group, 39.7% ( 58 146 ) failed to show estrus and were inseminated at 80 h. Reinsemination was required for 22.7% ( 20 88 ) of the cows that manifested estrus following insemination at 80 h. Overall conception rate was 41.4% ( 65 157 ). Cows inseminated in response to estrus had a 53.4% ( 47 88 ) conception rate, and appointment bred (80 h) cows had a 20.7% ( 12 58 ) conception rate. Factors significantly influencing conception were response to PGF administration (P < 0.05), season (P < 0.01) and lactation number (P < 0.01). It was concluded that estrus detection efficiency affects the outcome of PGF administration and that conception rates resulting from 80 h breeding when no estrus is observed may be unacceptably low.