Puberty beginning in lambs from hairless ewe submitted to caloric or protein restriction

AbstractThis study was carried out to evaluate if caloric or protein restriction in lactation ewe affect puberty beginning of its lambs. Had been used 21 lambs, two females and five males per type of treatment. During 60 days the mothers received the treatment for which its lamb was sort out: Control Treatment (TC, maintenance), Energy Restriction Treatment (TRC, ½ of the energy of the TC) and Protein Restriction Treatment (TRP, 1/3 of the protein of the TC). The lambs were weaned and received a diet composed by corn silage and concentrate, weighed and evaluated fortnightly. In males, the ejaculate was collected, scrotal circumference and testicular size measured. In females, it was realized ultrasound to measure the ovaries and verify the corpus luteum presence. For males was considered in puberty if produced ejaculation with at least: motility of 50%, sperm concentration of 50 x 106espermatozoa/mL and maximum of 50% total sperm abnormalities, and females if exhibit corpus luteum. An interaction was found between evaluation period and treatment for scrotum circumference (p=0.0019), testicular volume (p=0.0025) sperm motility (p<0.0001) and concentration (p=0.027), TRP was later than TRC and TC in all variable. In female no treatment effect (p>0.05) were found about follicles characteristics, however that was difference in the presence of corpous luteum (p=0.0179). The TC females showed corpus luteum from the 10th week, TRC 11th and 13th for TRP. It was concluded that mother protein restriction during the lactation delays the beginning of the puberty of its lambs.

摘要
本研究旨在评估泌乳母羊的热量或蛋白质限制是否会影响其羔羊的初情期启动。本研究共纳入21只羔羊，每种处理组对应2只雌性羔羊与5只雄性羔羊。试验期60天，母羊根据其所对应羔羊的分组接受相应处理：对照组（TC，维持日粮）、能量限制组（TRC，日粮能量为TC组的1/2）以及蛋白质限制组（TRP，日粮蛋白质为TC组的1/3）。羔羊断奶后饲喂由玉米青贮与精补料组成的日粮，每两周进行一次称重与指标评估。对雄性羔羊采集精液，测量其阴囊周长与睾丸尺寸；对雌性羔羊实施超声检查以测量卵巢体积并确认黄体存在情况。雄性羔羊的初情期判定标准为：采集的精液需满足精子活力≥50%、精子浓度≥50×10^6个/mL，且总精子畸形率≤50%；雌性羔羊的初情期判定标准为检测到黄体。
分析结果显示，评估周期与处理方式对阴囊周长（p=0.0019）、睾丸体积（p=0.0025）、精子活力（p<0.0001）及精子浓度（p=0.027）存在显著交互作用；蛋白质限制组（TRP）的各项指标对应的初情期均晚于能量限制组（TRC）与对照组（TC）。对于雌性羔羊，不同处理方式对卵泡特性无显著影响（p>0.05），但黄体存在情况存在显著差异（p=0.0179）。对照组（TC）雌性羔羊于第10周检测到黄体，能量限制组（TRC）与蛋白质限制组（TRP）分别于第11周和第13周检测到黄体。本研究结论为：泌乳期母羊的蛋白质限制会延迟其羔羊的初情期启动。