Prepartum shearing of Criollo sheep and its effect on lamb performance indicators

Abstract

Criollo breeds are of great social and economic importance and should be conserved. Prepartum shearing improves sheep metabolism and nutrient availability for the fetus. The study was conducted from November to February, which corresponds to the cold season in the Valley of Mexico. Twenty pregnant Criollo wool ewes with an average weight of 36 kg were used. The ewes were randomly assigned to two experimental groups: T1 (shorn, n=10) and T2 (unshorn, n=10). Shearing of T1 was performed one month before parturition. Subsequently, parturitions were monitored, and lamb weights at birth (NB), at one month (PM), and at weaning (WY; at two months of age), as well as survival, were recorded. Ewe weights were recorded one month postpartum. Results were analyzed using analysis of variance and chi-square tests. All ewes gave birth to a single lamb. Pre-lambing shearing did not improve lamb weight during lactation (LB: T1= 3.69±0.19 vs T2= 3.50±0.36; LB: T1= 9.52±0.64 vs T2= 8.36±0.97; LB: T1= 12.51±0.86 vs T2= 12.34±1.17 kg; p>0.05). Lamb survival was 100% for T1 and 90% for T2, however, no significant differences were found between treatments (p>0.05). The weight of ewes at one month postpartum was higher in shorn than in unshorn ewes (T1 = 37.96 ± 1.63 vs. T2 = 35.85 ± 1.82 kg, p < 0.05), but no differences were found at weaning. The lack of significant differences in some variables is possibly due to the limited number of observations; therefore, an increase in sample size is suggested in future studies. In conclusion, shearing did not improve lamb performance indicators at weaning, but it did increase ewes' weight at one month postpartum.