Stress during pregnancy: development of sexual behavior of male and female lambs

Abstract

The aim of this study is to evaluate the influence of stress generated by LPS during the final third of gestation in sheep on maternal behavior at birth and at weaning, testicular development and sexual behavior of male lambs. The experiment will be carried out in the Annex of Biometeorology and Ethology Laboratory located at the Sheep sector of Administrative Campus of the University of São Paulo in Pirassununga. 84 crossbred Santa Inês nulliparous sheep artificially inseminated with semen of White Dorper will be use. After the positive pregnancy diagnosis will be randomly divided into 2 treatments - TC: the control group will consist of sheep that not suffer application of LPS in any the time of pregnancy and TF: the final group will be challenged in the final third of gestation with the application of LPS. Cortisol levels and body temperature will be analyzed during pregnancy. At birth the lambs will be evaluate on affiliate maternal behavior and birth weight, then social and cognitive behavior will be evaluate during weaning. In 36 males from 4 to 12 months, testosterone analysis, LH and estradiol will be held, and morphology analysis and ultrasound of the testicles will be done. From 36th to 48th weeks the reproductive behavior will be assessed and at 48th 50% will be castrated for histopathological analysis. For behavior analysis is used the theory of generalized linear models proposed by Wenderburn and Nelder (1972), using the procedure of SAS GLIMMIX. The treatments will be compared by t-test and regression analysis will be made to list the answers at different stages of life of the lamb. (AU)