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Present study evaluated the presence of a sexually active male buck upon the influence of an estradiol implant in ovariectomised (OVX) goats exposed to a 6-month-long controlled photoperiod in a range of 13.4–10.6 light-hours per day. Mexican-native (Criollo) goats (n=20) were randomly assigned into 2 groups: (1) goats exposed to a sexually active male buck (n=10); (2) goats not exposed to a male buck (n=10). Each experimental group of goats included ovariectomised goats (OVX, n=5), and ovariectomised and estradiol-implanted goats (OVX + E2, n=5). Blood samples were taken from OVX and OVX + E2 goats, every four weeks, during 6 h at 15 min intervals (i.e., 24 samples/day). Frequency, amplitude, and concentration of luteinising hormone (LH) were determined. While the OVX + E2 goats depicted an increased LH pulse frequency (2.0±0.5 vs. 0.7±0.1), the presence of a sexually active male increased frequency, amplitude and concentration of LH in OVX goats compared to goats not exposed to males (frequency: 3.2±0.4...

Present study evaluated the presence of a sexually active male buck upon the onset of reproductive activity and estrous cycle progression in Criollo goats exposed to a 6-month long controlled photoperiod in a range of 13.4–10.6 light-hours per day. Mexican-native (Criollo) goats (n=10) were randomly assigned into 2 groups: (1) goats exposed to a male buck (n=5); (2) goats not exposed to a male buck (n=5). Blood samples were taken weekly to quantify serum-progesterone levels through radioimmunoanalysis. Male exposure increased luteal activity and estrous cycle progression reflected as a higher number of days in luteal activity (44±9.05 vs. 32.3±20.6); a reduced number of days in anestrous (4.0±4.8 vs. 51.9±28) and a greater number of luteal phases (15.7±4.4 vs. 11.3±8.7) without compromising serum progesterone levels (6.8±0.8 vs. 7.3±0.5). In conclusion, presence of a sexually active male induced a greater ovarian activity in Criollo goats, shortening seasonal anestrous irrespective of the controlled photo...

Aguilera-Soto, J.I., Ramirez, R.G., Arechiga, C.F., Mendez-Llorente, F., Lopez-Carlos, M.A., Silva-Ramos, J.M., Rincon-Delgado, R.M. and Duran-Roldan, F.M. 2008. Zilpaterol hydrochloride on performance and sperm quality of lambs fed wet brewers grain. J. Appl. Anim. Res., 34: 17–21. Forty Rambouillet × elibuey male lambs were grouped as light-weight (LW; n =20; 28±1.2 kg BW) and heavy-weight (HW; n = 20; 40.5±1.6 kg BW) to be fed a finishing diet containing 60% wet brewers grain with or without 6 mg kg1 DM ofβ-adrenergic agonist zilpaterol hydrochloride (ZH). On d 60 of the feeding trial, ZH was removed and semen collection was measured by electroejaculation. Further, on d 63 animals were slaughtered for carcass and meat quality evaluation. On d 15 of the feeding trial, lambs fed ZH gained significantly (about 25%) more weight. However, at the end of feeding trial (60 d period), ADG, DMI and feed efficiency were unaffected by ZH consumption. Sperm motility was significantly reduced by ZH only in ...