Efeito da endogamia nas características morfométricas e reprodutivas dos eqüinos da raça Mangalarga Marchador

Abstract

This work was carried out in order to evaluate the coefficient of inbreeding and its effect on the linear characteristics and reproductive indices of equines created at Catuni Farm in the North of Minas Gerais. The information of the zoothecnic archive from Catuni Farm was analyzed. The studied characteristics were the morphometric traits as withers and hip height, lengths of head, neck, back-loin, hip and body, widths of chest and buttocks and the reproductive traits as age to the first parturition, gestation lenght, parturition interval. The kinship matrix involved 2196 animals of the zoothecnic archive of the Catuni farm, and the inbreeding coefficient (f) was calculated in accordance with Wright (1922) and its effect was evaluated by the simple linear regression of the same on the linear measures and reproductive indices using statistical procedure PROC REG (SAS, 2004). From the total of animals, 27.59% had revealed themselves inbred, being the medium F of the equal population to 1.45%. Considering only the inbred animals, the medium consanguinity reached 5.28% (minimum of 0,1 and maximum of 28,13%). The sires, when their offspring were born, were 9,06 years old in average; while the mothers were 8,90 years old, providing a medium interval of 8,98 years. The effective size of the Mangalarga Marchador herd of the Catuni Farm was of 185,25 animals. Negative effect of the inbreeding on the productive and reproductive characteristics were not verified, except for the morphologic characteristic buttock width, in which it was determined that for each 1% of increase of F there was increase of 0,0576 cm. Possibly due to the low inbreeding coefficient, the current levels of inbreeding are not presenting significant effect on the others evaluated characteristic.