Medidas morfométricas como critérios de seleção de machos ovinos para reprodução em rebanhos crioulos nos Pequenos Lençóis Maranhenses

Abstract

Sheep farming is one of the main activities developed in the Brazilian Northeast, where many breeders consider it a source of subsistence. However, it is developed empirically, with low levels of technology, inefficient food, health and reproductive management, but has undergone an adaptation process, which has led to the emergence of native breeds and extensive management methods, which, although sustainable, they still deal with limited obstacles and low productivity, requiring improvements, especially in reproductive management. Choosing good breeders results in progeny that present high production rates, as they will leave 50% heritability for their descendants, linked to this, females will present high conception rates, improving management. The objective of this study was to analyze the influence of the correlation between the morphometric measurements of thoracic perimeter (PT), scrotal circumference (CE), scrotal width (LE), scrotal length (CDE) with body weight (PC) in male sheep used in reproduction of creole herds in the municipality of Paulino Neves, Pequenos Lençóis Maranhenses. 29 mixed breed breeders (SPRD) were used from breeders from the ACORDEN association – Association of breeders and defenders of Nature, municipality of Paulino Neves, in the small Maranhão sheets. The animals are raised free range, feed on native forage, reproduce randomly and have very poor health control. The morphometric measurements of body weight were carried out using a scale with an analogue clock graduated in kg/PC and for the measurements of CE, LE, PT and CDO, a flexible measuring tape and metallic tape graduated in centimeters (cm) were used. The data were tabulated using the Microsoft Excel® program. Pearson's linear correlation was used at 95% reliability, using the Microsoft BioEstat 5.3 program. PC and CDE presented higher coefficients of variation (21%) and the others below 15%. The means and standard deviation were 23.97 ± 5.09 for PC, 25.62 ± 3.74 for CE, 69.48 ± 6.09 for PT, 10 ±1.39 for width and 15. 90 ± 3.30 for the CDE. A positive correlation was obtained for the variables body weight (PC) and scrotal circumference (CE) r= 0.6737 (p=<0.0001), PC and chest circumference (PT) r= 0.7682 (p= <0 .0001), PC and scrotal width (LE) r= 0.6217 (p=<0.0003), PC and scrotal length (CDE) r= 0.8104 (p=<0.0001). The average measurements evaluated were lower than the data found in the literature, possibly linked to the genetic conditions of the animals, resulting from inbreeding. However, the morphometric measurements of the studied sheep breeders can constitute a viable alternative as a control parameter and selection of males for reproduction as they present a strong correlation between them