FR 40. Preliminary results on factors affecting lambing intervals of ewes in tropical conditions

Resumen

The least squares technique was used to analyse 1 865 lambing intervals (IEP) from the Sheep Division - Universidad Central de Venezuela, from 1984 to 1994 in order to evaluate the effect of sex of lambs (S), ewe breed (RM), type of lambing (TP), month of lambing (MP), year of lambing (AP), birth condition (CN), number of lambings (NP), and breeding sistem (M); with birth weight of lambs (PN), weaning weight of lambs (PD), weaning age of lambs (ED) and weight at lambing of the ewe (PP) as covariables. Adjusted and unadjusted means for IEP were 285 ± 9.3988 and 289 ± 1.7517 days. IEP was significantly affected by RM, AP and NP. The best IEP was for West African (WA) ewes (272 days) and for high WA breed ewes (278 days). For AP the differences are possibly due to management. For NP the longest IEP was for first lambing ewes (304 days) and the shortest one for adult ewes with 7 and 8 lambings (267 and 265 days).