Department of Animal Science, Faculty of Agriculture, Razi University, Kermanshah, 6715685414, Iran.
Department of Theriogenology, Faculty of Veterinary Medicine, Razi University, Kermanshah, 6715685414, Iran.
Trop Anim Health Prod. 2024 Nov 16;56(8):385. doi: 10.1007/s11250-024-04218-1.
This study aimed to investigate whether providing additional ad libitum feeding could improve reproductive characteristics in prepubertal ewe lambs. Twelve Sanjabi ewe lambs, approximately one-month-old and with an average initial weight of 11.6 ± 1.3 kg, were monitored over a 3-month period, which was divided into three distinct periods of 30 days each. The first period spanned from the lambs' age of one to two months, the second period covered their age range of two to three months, and the third period encompassed their age range of three to four months. The lambs were randomly assigned to either a control group (C) or a treatment group (T). The control group received a basal diet consisting of hay and milk, whereas the treatment group received an enhanced diet comprising hay, milk, and concentrate. Live weight (LW) and average daily gain (ADG) were measured weekly, and blood samples were collected from the jugular vein at days 30, 60, and 90 of the experiment to determine the concentrations of progesterone (P4) and estrogen (E2). Following the 90-day experiment, the lambs were humanely euthanized in accordance with established protocols. Subsequently, both ovaries from each animal were removed, weighed and subjected to a comprehensive histological analysis. The ovaries underwent fixation, embedding, and sectioning procedures, followed by staining with hematoxylin and eosin (H&E) to facilitate microscopic examination. Ovary microscopic sections from both C and T groups were examined to assess follicles at various developmental stages, including primordial follicle number (PreFN) and diameter (PriFD), primary follicle number (PriFN) and diameter (PriFD), secondary follicle number (SFN) and diameter (SFD), antral follicle number (AFN) and diameter (AFD), and granulosa layer thickness of secondary (GLTSF) and antral follicles (GLTAF). The impact of diet and three experimental periods on ADG and LW exhibited significant variations. There was a significant increase (P < 0.05) in LW in the T group compared to the T group, with noticeable differences in LW fluctuations observed during distinct periods. However, ADG was more prominent in the initial and second observation periods than in the third. The impact of diet and experimental periods on P4 and E2 concentrations was found to be negligible. The T group showed significant improvements (P < 0.05) in PreFD, PriFN, and GLTAF compared to the C group. This study suggests that ad libitum concentrate feeding may promote reproductive characteristics in prepubertal ewe lambs. Further research is needed to explore its potential impact on the age of puberty.
本研究旨在探讨在小母羊的初情期前阶段，提供额外的自由采食是否可以改善其繁殖特性。选取 12 只大约 1 月龄、初始体重为 11.6±1.3kg 的三羊杂交小母羊，在 3 个月的试验期内，分为 3 个阶段，每个阶段持续 30 天。第 1 阶段为 1 至 2 月龄，第 2 阶段为 2 至 3 月龄，第 3 阶段为 3 至 4 月龄。将小母羊随机分为对照组（C）和处理组（T）。对照组饲喂基础日粮（干草和牛奶），处理组饲喂强化日粮（干草、牛奶和浓缩料）。每周测量活重（LW）和平均日增重（ADG），在试验的第 30、60 和 90 天从颈静脉采集血样，测定孕酮（P4）和雌激素（E2）浓度。90 天试验结束后，按照既定程序对小母羊实施安乐死。然后取出每个动物的两个卵巢，称重并进行全面的组织学分析。卵巢经过固定、包埋和切片处理，然后用苏木精和伊红（H&E）染色进行显微镜检查。检查 C 组和 T 组的卵巢显微镜切片，以评估不同发育阶段的卵泡，包括原始卵泡数（PreFN）和直径（PriFD）、初级卵泡数（PriFN）和直径（PriFD）、次级卵泡数（SFN）和直径（SFD）、腔前卵泡数（AFN）和直径（AFD）以及次级卵泡（GLTSF）和腔前卵泡（GLTAF）的颗粒细胞层厚度。日粮和三个试验期对 ADG 和 LW 的影响表现出显著的差异。T 组的 LW 显著增加（P<0.05），与不同时期 LW 波动的明显差异。然而，ADG 在初始和第二观察期更为显著，而在第三期则不那么显著。日粮和试验期对 P4 和 E2 浓度的影响可以忽略不计。T 组的 PreFD、PriFN 和 GLTAF 显著高于 C 组（P<0.05）。本研究表明，自由采食浓缩料可能会促进小母羊的繁殖特性。需要进一步的研究来探索其对初情期年龄的潜在影响。
