Effects of the FecXR allele of BMP15 gene on the birth weight, growth rate and carcass quality of Rasa Aragonesa light lambs

A new allele of the BMP15 gene (FecXR) that increases prolificacy has been recently described in the Rasa Aragonesa sheep breed. The present study was conducted to evaluate the effects of lamb and maternal genotypes on birth weight, growth and meat quality traits. Two experiments were carried out. In experiment 1, the progeny of heterozygous (R+) and wild-type (++) dams mated to wild-type hemizygous (+) rams from four flocks were tested to estimate the effects of the FecXR allele on birth weight and average daily gains (ADGs) until weaning and slaughter (at approximately 50 and 100 days of age, respectively). Three maternal/lamb genotype groups were studied: wild-type progeny from ++ ewes (females: ++/++, n = 62; males: ++/+, n = 60), wild-type progeny from R+ ewes (females: R+/++, n = 31; males: n = 28 R+/+) and progeny carrying the FecXR mutation born to R+ ewes (females: R+/R+, n = 35; males: R+/R, n = 28). No significant differences were observed in the birth weights or ADGs between the FecXR genotype groups in either female or male lambs. In experiment 2, 37 male lambs (13 ++/+, 12 R+/+ and 12 R+/R) were used to evaluate the effect of the FecXR genotype groups on carcass characteristics and meat quality traits. All lambs were classified within the normal ranges for the “Ternasco de Aragón” commercial category, and no significant differences were observed between the genotype groups. We conclude that birth weight, growth traits, light lamb carcass characteristics and meat quality traits were not affected by the maternal and lamb FecXR genotype combinations that were studied.