Resumen de GM 22. Preliminary results on the effect of ram and ewe breed on lamb birth weight in tropical conditions
Josefina Combellas, Zoraida Rondon, Leyla Rios de Álvarez, Omar Verde
Least squares techniques were used to analyse 3464 records of lamb birth weights (PN) of the Sheep Section, Universidad Central de Venezuela, from 1984 to 1994 in order to evaluate the effect of sex of lambs (S), ram breed (RP), ewe breed (RM), type of lambing (TP), month of lambing (W), year of lambing (AP), birth condition (CN) and number of lambings (NP); with weight at lambing of the ewe (PP) as covariable. PN mean was 2.78 = Bl 0.653 kg, and was significantly affected by: S, RM, RP, TP, AP, NP. The lambs of rams of temperate breeds (Bergamasca and Dorset Horn) had higher PN than those of tropical breeds (West African (WA) and Persian Black Head (PCN)). The lambs of Bergamasca ewes had similar PN to those of WA and PCN x WA. The lambs of Dorset Horn ewes had lower PN, probabily as a consequence of adaptability problems. The use of rams of temperate breeds is justified to improve the lamb birth weight in tropical conditions.
