Abstract

Data on birth weight of 2377 lambs obtained from 581 dams and 56 sires of Mengali sheep
born during 2005 and 2009 were recorded and analyzed to identify the factors affecting birth
weight of Mengali lambs. Mengali flocks were kept under semi-intensive condition in four
stations at three different locations (Experimental Station Center for Advanced studies in
Vaccinology and Biotechnology (CASVAB), University of Balochistan, (ESC), Quetta, Killi
Hassni, Quetta; Khadkucha, Mastung and Peer Wala (Mal), Nushki). The lambing occurred
spring and autumn, however majority of the Mengali sheep (85 %) lambed during spring
between (February and March months). Among the total lambs born, the male to female sex
ratio was 49.43: 50.57 respectively and shown no significant difference between two sexes.
The overall least-squares means for birth weight of males and females pooled over parity and
type of birth were 3.61±0.36 and 3.48±0.39 kg respectively. The estimate of heritability for
birth weight was observed as 0.39±0.06. Study on non-genetic factors revealed that the birth
weight was significantly (P<0.05) affected by period of birth, season of birth, sex of the lamb,
parity and location of flock. Hence, efforts should be made for better management of
pregnant ewes when the climatic conditions are not conducive to them.