Effects of the Booroola (FecB) genotypes on growth performance, eweʹs productivity efficiency and litter size in Garole × Malpura sheep

The present study was conducted to evaluate the effects of FecB genotypes on body weight, average daily gain (ADG), eweʹs productivity efficiency (EPE) and litter size in FecB introgressed Garole × Malpura (GM) crossbred sheep. A total of 235 GM lambs were selected randomly and screened for FecB mutation using forced RFLP-PCR. The majority (69.8%) of GM individuals were carriers (BB and B+) for the FecB mutation and frequency of the FecB allele was about 0.40. The FecB genotypes were significantly (P < 0.01) associated with the lambʹs body weights from birth to 12 months of age. The generation wise (F1, F2 and F3), lambʹs body weight did not differ significantly at birth, 6 and 12 months of the age, while it differed significantly (P < 0.05) at 3 and 9 months of age. The ADG1 (0–3 months) was significantly associated (P < 0.05), but not the ADG2 (3–6 months) and ADG3 (6–12 months) between genotypes. Type of birth and sex significantly (P < 0.01) affected the body weight from birth to 12 months of age; and body weight of single born lambs was significantly higher (P < 0.01) than that of twins and triplets from birth to 12 months of age. Type of birth significantly (P < 0.01) affected the ADG1, but had no significant effect on ADG2 and ADG3. Year of birth did not affect the birth and weaning weights, but it significantly affected (P < 0.01) the body weight and ADGʹs after weaning ages. The EPE was affected significantly (P < 0.01) by the FecB genotypes at birth, 3 and 12 months of age. The EPE of B+ and BB ewes were 7.86 kg (36.9%) and 2.32 kg (10.9%) higher as compared to ++ ewes at 12 months of age, respectively. The mean litter size of BB ewes (2.17 ± 0.24) was significantly higher (P < 0.01) than that of B+ ewes (1.73 ± 0.04) and ++ ewes (1.03 ± 0.23). The present study indicated that the body weight and ADG of carrier lambs (BB and B+) was comparatively lower than that of non-carriers (++), while EPE of B+ ewes was comparatively higher than that of BB and ++ ewes. Further, it is interesting to note that heterozygous and homozygous state of individuals increased 0.70 and 1.14 extra lambs as compared to non-carriers (++), respectively.