One of the most important aspects of animal production is the reproductive behavior, where a widely used strategy in small ruminants is the “male effect”. However, the response to this effect can vary depending on several factors, including the social rank (SR) of both sexes. The objective of this study was to evaluate how SR influences morphometric and socio-sexual variables in Dorper sheep in Northern Mexico. Through behavioral tests, 33 rams and 59 ewes were divided into two groups taking into account their SR. Rams included high SR (HSR; n = 14) and low SR (LSR; n = 19), while ewes included HSR (n = 23) and LSR (n = 36). Morphometric response variables included age, live weight, body condition, thoracic circumference, wither height, presence of horns, and testicular circumference, whereas reproductive variables included estrus rate, ovulation rate, corpus luteum, left ovary, right ovary, pregnancy rate, and embryos’ number. The results showed no differences (p > 0.05) for the morphometric variables considered, whilst, regarding the reproductive variables, the LSR rams × HSR ewes group showed the highest number of embryos (p < 0.05), and the corpus luteum number was higher in the HSR rams × HSR ewes group (p < 0.05). However, no significant differences were found for the remaining variables (p > 0.05). Improving productive and reproductive performance can contribute to increased income for sheep farmers.

Background: Hormonal treatments can influence hematological profiles through direct and indirect mechanisms in sheep’s. The aim was to evaluate the effect of administering equine or human chorionic gonadotropin (eCG, hCG, respectively) at 7 or 14 days post-mating on blood count values in early pregnancy of nulliparous ewes. Methods: A total of 63 ewes were used, which were randomly assigned to five experimental groups (EG): EG-eCG7 (300 IU of eCG, 7 days post-mating (DPM)), EG-hCG7 (300 IU of hCG 7 DPM), EG-eCG14 (300 IU of eCG 14 DPM), EG-hCG14 (300 IU of hCG 14 DPM) and; EG-Control (without hormonal treatment). Hematologic variables were determined on days 7, 14 and 28 DPM and included white blood cell count (WBCC), red blood cell count (RBCC), hematocrits (Ht), hemoglobin concentration (HbC), mean corpuscular hemoglobin (MCHb), mean corpuscular hemoglobin concentration (MCHbC) and medium corpuscular volume (MCV). An ANOVA and Pearson correlation were performed on the response variables. Result: The results showed differences in WBCC on day 7 between the EGs and between days for the EG-Control. The RBCC variable only showed differences between the days of the EG-eCG14. The Ht variable reported differences between the days of the EG-eCG14. Regarding HbC, differences were determined between the EGs for days 14 and 28, as well as between the days of the EG-hCG7. Additionally, positive and negative correlations were evidenced between the variables considered. Based on the above, it is concluded that in the first month of gestation, the variables WBCC, RBCC, Ht, HbC and MCV increase in pregnant ewes. The aforementioned contributes to determining ewes’ reproductive performance and improving their productive and reproductive parameters.