Genetic Evaluation of Rams for Total Milk Yield in Iraqi Awassi Sheep

Abstract

This study was conducted at the Improvement station of Sheep and Goats, Ministry of Agriculture, Iraq. A total of 344 milk records of the Awassi ewes collected during 2006-2007 were used to investigate the effect of non-genetic factors (year of calving, parity, lamb sex and litter size) on total milk yield (TMY), average daily milk yield (ADMY)and lactation period (LP). Data were analyzed by using GLM in SAS program. Components of variance for the random effects in the employed mixed model were estimated by MIVQUE method. Harvey program was used to estimate Best Linear Unbiased Prediction (BLUP) values of sires for all studied traits. Results showed that the total milk yield (TMY), average daily milk yield (ADMY) and lactation period (LP) was significantly affected by parity and production year. Litter size affected only LP, whereas the effect of lamb sex was not significant on all traits. The averages of total milk yield, average daily milk yield and lactation period were 73.16 kg, 0.81 kg and 85.78 day, respectively. Heritability estimates (h²) of TMY, ADMY and LP were 0.47, 0.44 and 0.33 respectively. BLUP values of sires for total milk yield were between 48.49 and-39.17 kg. These results provide evidence that Awassi sheep will response to genetic improvement process.