Evaluation of Awassi genotypes for improved milk production in Syria

Abstract

A performance evaluation, conducted between 2003 and 2005, compared the milk production of three genotypes of Awassi ewes: Turkish (T), Syrian (S) and the F1-cross between the Turkish and Syrian ewes (TS), at the International Center for Agricultural Research in the Dry Areas (ICARDA) experimental farm in Tel Hadya (northern Syria). After weaning, which occurred at 56days, milk yield and milking length were measured weekly during the milking period ( n = 381). Milk yield of TS and T ewes were 12% and 30% higher, respectively, than S ewes. Milk yield and milking length of TS ewes reflected additive inheritance and did not differ from the parental genotypes' average ( p ≥ 0.199). Culling of low producing ewes in 2003 and 2004 also resulted in increased milk yield. Dams of all genotypes displayed similar weights at birth ( p = 0.898) and weaning ( p ≥ 0.677). The latter suggests dams of the different genotypes olerated equally the pre-weaning lactation load. Performance tended to improve as ewes aged, with milk yield and milking length peaking at 3years of age ( p > 0.05). Ewe lambing weight, birth–weaning ewe weight decline, litter size, and litter weight weaned peaked at 4–5years of age ( p ≤ 0.016). With the exception of birth–weaning ewe weight decline, year effects influenced the traits under study ( p ≤ 0.035). Excluding litter size, the best performance was in 2005, followed by 2003 and 2004. Milk yield increased with litter size at weaning ( b = 18.7; p = 0.024). The lambing–weaning ewe weight decline (3.6kg) and ewe productivity (0.46kg litter weaned weight per kg ewe weight) did not differ between genotypes ( p ≥ 0.178). Average litter size was 1.15, with the TS ewes displaying the largest litter size (1.23; p = 0.026). Single lambs were 25% heavier than twins at birth averaging 4.73kg and 3.8kg, respectively. Male lambs were 4% heavier than female lambs at birth ( p < 0.0001) and 9.3% heavier at weaning ( p < 0.0001). Lamb birth weights, weaning weights and daily weight gains were similar for all genotypes ( p ≥ 0.210). The average proportion of fat (5.95%), crude protein (5.19%) and solids non-fat (11.29%) in the milk varied across genotypes where S < TS < T ( p ≤ 0.0037). F1 crosses with T increased the productivity of S ewes by 12.2%. It is noteworthy that this occurred under improved feeding and may not be recommended for other conditions. Culling low producing ewes led to a 12.8% increase in milk yield, which could translate into a substantial boost in revenue for farmers rearing traditional sheep flocks in milk producing areas.