Milk Yield and Composition As Affected by Nutritional Manipulations

Abstract

The objective was to evaluate milk yield, milk composition and milk fatty acids contents of lactating Harri ewes (n=24) receiving different concentrate to roughage (A 80:20; B 60:40; C 40:60 and D 20:80 C:R) rations. The results revealed that no differences (P = 0.29) in body weights of ewes were detected after parturition but body weights declined steadily as ewes continued on lactation. Group D produced more (P < 0.01) milk (1.38±0.5 kg/day) than groups A (0.76±0.5 kg/day), B (0.88±0.5 kg/day) and C (0.66±0.5 kg/day). Yields of milk fat, SNF, protein, lactose and minerals yields (g/day) were greater (P = 0.01) in group D than groups B and C not group A. No differences were found in milk fat, SNF, protein, lactose and minerals percentages (%). Groups D and A had more (P = 0.06) C18:2c (3.15±0.21 and 2.99±0.08 g/100g fat) than group B (1.98±0.54 g/100g fat) not group C (2.72±0.05 g/100g fat). Poly unsaturated fatty acids (PUFA) were increased (P<0.01) in groups A and D (4.07±0.18 and 4.49±0.27 g/100g fat) than groups B and C (3.34±0.12 and 3.41±0.23 g/100g fat). Lactating ewes' diet should include adequate ratio of roughage to increase milk yield and improve milk fat composition of unsaturated fatty acids. Keyword: Sheep, concentrate: roughage ratio, nutrition, milk yield, fatty acids.