Leptin profile relative to progesterone in serum of Shami goats during the early breeding season

The aim of the study was to determine the serum leptin profile relative to progesterone level in Shami goats during the early breeding season. Ten multiparous- non pregnant Shami does were offered diets based on barley and wheat straws with free access to natural grazing, with water and minerals available ad libitum. Daily prefeeding blood samples (10 mL) were collected for 46 days by jugular venipuncture. Serum was stored at -20 degrees C until assayed for leptin and progesterone analysis using radioimmunoassay technique. Data were analyzed as a repeated measure design using PROC GLIIMMIX Procedures in SAS 9.4. Differences in least square means for leptin were tested using Fisher's protected least significant differences (p <= 0.05). Results indicated that the level of P4 was largely undetectable at lower than 0.3 ng/mL in non- cycling does (n=8) while it increased significantly (p < 0.01) in cycling does (n=2) and the least square means of serum leptin levels were 3.5 +/- 0.94 and 3.7 +/- 0.47 ng/mL, in cycling and non- cycling Shami goats, respectively. No significant effect was found for the groups studied or their interaction with seasonal days on serum leptin, but a significant effect (p< 0.01) for the seasonal days was confirmed. No regular daily rhythm was found in serum leptin levels in non-ovarian active goats, and the overall levels of leptin regardless the groups studied were significantly lower in the early than the late seasonal days. Higher levels of leptin showing significant variations (p<0.01) were also observed during the luteal phase in ovarian active goats and there was a positive and significant correlation (r = 0.40, p<0.01) between leptin and progesterone concentrations. This suggests that leptin might affect luteal function in Shami goats and further study is recommended.