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

Abstract

This 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.