Effect of synchronization of follicle-wave emergence with estradiol and progesterone and superstimulation with follicle-stimulating hormone on milk estrogen concentrations in dairy cattle

摘要

Very little is known about the effects of hormonal synchronization of follicle waves and superovulation on the estrogen content of a cow's milk. The objective of this study was to determine the effect in dairy cows of synchronization with estradiol-17 beta (E2) and progesterone (P4) on milk E2 concentrations and to compare these levels with those achieved during superstimulation for 4 d with porcine follicle-stimulating hormone (FSH). The milk E2 concentrations were raised significantly above pretreatment levels (P 0.05) for 2 d after synchronization, the mean peak being 40.2 +/- 6 18.5 (standard error) pg/mL and the pretreatment mean 1.5 +/- 0.5 pg/mL. The mean peak E2 concentration during ovarian stimulation was 4.4 +/- 0.7 pg/mL. The mean E2 concentration was significantly higher (P 0.05) after synchronization than during superstimulation for the 1st milking after synchronization but not subsequent milkings. The milk estrone concentrations were above pretreatment levels for 1 d after synchronization and were not different from those observed during superstimulation.