Effects of maternal and service sire breed on circulating progesterone and estrogen concentrations before calving and 13,14-dihydro- 15-keto-prostaglandin F2alpha after calving

Abstract

Effects of breed of service sire and dam upon prepartum and postpartum reproductive performance were studied in 20 Brahman (B) and 20 Angus (A) cows whose pregnancies were initiated by B or A bulls. Before calving cows were bled via tail venipuncture on d 28-34, 21-27, 14-20 and 7-13 prepartum and daily from parturition to d 7 postpartum. Serum concentrations of progesterone (P4; ng/MI), estrogens (E; pg/ml) and plasma 13-14dihydro-15-keto-prostaglandin F2(x (PGFM; pg/ml) were measured using radioimmunoassay procedures. Hormone data were analyzed using SAS GLM procedures for ANOVA specific for repeated measures. The models included breed of dam and service sire as main effects and their interactions. On d 14-20 prepartum P4 was higher (.01) in dams bred to B sires. Dams carrying males had higher (P=.003) P4 on d 14-20 prepartum than dams carrying female. On d 28-34 prepartum B had higher (P=.01) E than A female. On d 28-34 prepartum B had higher (P=.01) E than A dams. Dams bred to A had higher E on d 7-13 (P=.03) and on 28- 34 prepartum (P=.07) than did dams bred to B bulls. Dams carrying males had higher E than dams carrying female calves on d 14-20 (P=.01) and 21-27 prepartum (P=.02). Dams bred to B had higher ratios (P4:E) of P4 to E on d 7-13 (P=.03) and 14-20 prepartum (P=.007) than did dams bred to A bulls. B dams had higher PGFM on d .5 (P=.06), I (P=.05) and 2 postpartum (p=.07). Dams bred to A had higher PGFM on d 1 (P=.02) and 2 postpartum (P=.01) than dams bred to B bulls. Dams producing female calves had higher (P=.02) PGFM at parturition than dams producing males. Hormonal profiles pre and postpartum were influenced by breed of service sire and dam, which may influence postpartum reproductive performance in cattle.