Abstract

SOSA-PEREZ, G et al. Recombinant bovine somatotropin (bST) in estrus synchronization and prolificacy in Pelibuey ewes. Arch. zootec. [online]. 2014, vol.63, n.241, pp.219-222. ISSN 1885-4494.  https://dx.doi.org/10.4321/S0004-05922014000100025.

In this study it was investigated whether the effect of administration of Recombinant Bovine Somatotropin (bST) (two days before the end of progestin treatment) on synchronizing estrus, estrus, fertility, prolificacy and mode of delivery in Pelibuey sheep. It was an inserted a intravaginal device impregnated with progesterone (P4 CIDR 0.3 g) for nine days on180 sheep with 4 ± 0.32 years of age, the sheep were randomly assigned to one of three treatments: T1= CIDR (n= 60), T2= +250 mg of bST CIDR (n= 60) and T3= CIDR+300 48 IU eCG hours before the end of progestin (n= 60). Results showed no difference (p>0.05) between treatments in estrus synchronization response, fertility and prolificacy. The time to onset of estrus was lower (p<0.05) when applying bST (31.95 ± 2.85 h), with respect to the application of progesterone (43.67 ± 3.55 h). The number of ewes with triplets was higher (p<0.05) when applying bST (32.73 %) and less where it was applied eCG (13.47 %). The administration of 250 mg of bST in Pelibuey sheep, two days before the end of progestin, reduces the time to onset of estrus and increases the proportion of triplets.

Keywords : Hair sheep; Fertility; Pregnancy rate; Multiple births.

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