Factors affecting milk production in improved Awassi dairy ewes

This study investigated the factors affecting milk production and lactation curve parameters from the complete lactations of Awassi dairy sheep. The animals were kept in a single flock under intensive management and milked twice daily starting at lambing. Lambs were removed from the ewes at birth into an artificial rearing unit. The results of the analyses of 3740 complete lactations showed a mean litter size of 1.28 lambs born per ewe lambing and average total milk yield of 506 l from lactations 214 days in length and with an average lambing interval of 330 days. Mean lactation number was 3.71 and ewes conceived on average in the 6th month of the lactation. The lactations peaked on day 45 at a yield of 3.44 l. The maximum milk secretion potential of the ewes was 3.9 l/day, with milk yield increasing at 62 g/day mid way between lambing and peak yield and declining at 16.5 g/day mid way between peak and the end of lactation. Age at first lambing, lactation number, lit ter size, month of lambing and month of conception during the lactation had significant effects (P < 0.05) on some or all of the lactation parameters investigated. Relatively high milk yield was obtained in lactations starting in the January to March period. The monthly effect an milk production was explained by significant (P < 0.05) heat load and photoperiod effects. High milk production was found to have a significant (P < 0.05) adverse effect on reproductive performance. Conception followed a significant (P < 0.05) shout term variation in milk production.