Serum LH concentrations during seasonal reproductive transitions in criollo x Nubian goats with different nutritional status

The effect of body energy reserves (BMI) and daily feed intake (FI), on serum LH during transitions into the anovulatory (AT) or breeding season (BT) was determined. Twelve ovariectomized Criollo/Nubian goats, bearing s.c. 17-beta estradiol implants, were assigned to two groups of BMI (n=6): high (HBMI) and low BMI (LBMI). Within each BMI group, two subgroups (n=3) were established: with (WFIR) and without (WOFIR) temporal restriction in FI. LH pulse frequency (LHF) and mean (LHM) and basal (LHB) serum LH concentrations were determined. LHF, LHM and LHB gradually diminished during AT (2.08, 1.41, 0.41 pulses/6 h; 2.1, 1.21, 0.51 ng/ml; 1.3, 0.8, 0.4 ng/ml; P<0.01), whereas LHM and LHB gradually increased during BT (1.01, 1.58, 1.87 ng/ml; 0.57, 0.98, 1.04 ng/ml; P<0.01). HBMI goats had greater LHF than LBMI goats during AT (2.05 vs 0.55 pulses/6 h; P<0.05) and BT (3.2 vs 0.9 pulses/6 h; P<0.05), and also greater LHM during BT (2.1 vs 0.87 ng/ml; P<0.01). During AT, temporal feed restriction caused an earlier decrease on LHM and LHB in HBMI goats making their profile similar with LBMI goat's profile. During BT, temporal feed restriction diminished LHF and LHB independently of BMI (2.8 vs 1.3 pulses/6 h and 1.18 vs 0.55 ng/ml for WOFIR vs WFIR; P<0.05). Body energy reserves and daily feed intake modulate LH secretion during reproductive transitions in Criollo/Nubian goats. Moreover, temporal restriction in feed intake might diminish LH secretion during transition into the anovulatory season, even in goats with high BMI.