Meza-Herrera, C.A., Bocanegra V.J.A., Bafiuelos, R., Arechiga, C.F., Rincon, R.M., Ochoa-Cordero, M.A., Juarez-Reyes, A.S., Cerrillo-Soto, M.A. and Salinas, H. 2007. Circannual fluctuations in serum cortisol and glucose concentrations and hair coat growth in goats. J . Appl. Anim. Res., 31: 79-82.
This study characterized serum cortisol (CORT) and glucose (GLUC) levels and the hair cover length i n six goat genotypes, Granadina (G), Nubian (N), Saanen (S), Toggenburg (T),
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 13.4Á 10.6 light-hours per day. Mexican-native (Criollo) goats (n 010) were randomly assigned into 2 groups: (1) goats exposed to a male buck (n 05); (2) goats not exposed to a male buck (n 05). 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 (4499.05 vs. 32.3920.6); a reduced number of days in anestrous (4.094.8 vs. 51.9928) and a greater number of luteal phases (15.794.4 vs. 11.398.7) without compromising serum progesterone levels (6.890.8 vs. 7.390.5). In conclusion, presence of a sexually active male induced a greater ovarian activity in Criollo goats, shortening seasonal anestrous irrespective of the controlled photoperiodic regime.
(2011) The male effect stimulus positively influences luteinising hormone secretion in ovariectomised Criollo goats irrespective of a controlled photoperiodic regime, Journal of Applied Animal Research, 39:3,[196][197][198][199][200][201][202][203][204] 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 13.4Á10.6 lighthours per day. Mexican-native (Criollo) goats (n 020) were randomly assigned into 2 groups: (1) goats exposed to a sexually active male buck (n 010); (2) goats not exposed to a male buck (n 010). Each experimental group of goats included ovariectomised goats (OVX, n 05), and ovariectomised and estradiol-implanted goats (OVX ' E2, n 05). 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 (2.090.5 vs. 0.790.1), 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: 3.290.4 vs. 0.790.1 pulses/6 h; amplitude: 1.690.1 vs. 0.890.3 ng/mL; concentration: 5.390.6 vs. 2.090.9 ng/mL) (P B0.001). In conclusion, the presence of a sexually active male increase LH pulse frequency, amplitude and concentration in OVX-goats (Criollo), irrespective of a controlled photoperiodic regime.
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