Nível sanguíneo de testosterona, crescimento e características ao abate de cordeiros em diferentes condições sexuais

Abstract

This study evaluated the effects of sexual conditions in testosterone blood levels, in growing, characteristics and slaughter yields of lambs. Fourty nine (49) Texel x Corriedale cross male lambs were used, originating from sngle births, distributed in three groups: uncastrated (n=16); castrated (n=17) and induced to cryptorchidism (n=16). Animals were raised in the region of the Pampa Biome, in Rio Grande do Sul, under natural extensive pasture conditions, with food supplementation after weaning. Animals were identified and wegheid at birth. Castration and induction to cryptorchidism were made when lambs reached the average age of 35 days. Growing was monitored through weighings and mensuration of morphomedtric measures at 28-days intervals. Five collections of blood were made, between the 119° and 231° days of age, to determine concentration of total testosterone. Lambs were slaughtered with the minimum weight of 30 kg and body condition score between 3.0 and 3.5. Data were submitted to analysis of variance to evaluate the effects of sexual conditions. Uncastrated lambs and castrated showed higher values for body weight between the 35° and 203° days of age, as well as for toraxic perimeter and body compactness. Uncastrated lambs were superior to cryptorchids in average weight during the total period of the experiment. Cryptorchids presented average weight gain higher than hose castrated between 203° and 259° days. Castrated lambs showed superior body condition scores in the 147° day, in relation to cryptorchids, and in the 175° and 203° days compared to uncastrated and cryptorchid animals. Blood testosterone concentrations were superior in uncastrated and cryptorchid lambs, in the 203° and 231° days and in the overal average.Castrated lambs attained the stipulated conditions for slaughter more precociously. Uncastrated and induced to cryptorchidism showed higher values for body length (cm), toraxic perimeter (cm), body weight (kg), head (kg), skin (kg), penis (kg) and liver with gall bladder (kg). Uncastrated showed higher values for lungs with trachea (kg), body compactness (kg/cm), carcasss weight (kg) and cold carcass (kg) than castrated animals. It is concluded that, with the advancing of age, sexual conditions affects the hormomonal testosterone production but, no differences were observed in terms of growing at younger ages. Castrated lambs reach slaughter condition at younger ages than uncastrated and cryptorchids, producing lighter carcasses without, however, occurring differences in terms of body parts yield among castrated, uncastrated and criptorchid lambs.