Composition and specific gravity of milk of West African Dwarf sheep as affected by stage of lactation and parity
Twelve matured lactating ewes weighing between 16 and 24 kg live weight were used to evaluate the effects of stage of lactation and parity on milk composition and specific gravity of milk of West African Dwarf (WAD) sheep in a semi-intensive system of management. Stage of lactation was divided into 4: early, mid, late and very late respectively with 3 weeks interval. The animals were of parities 1 and 2 and were allowed to graze on an established paddock in the University Farm for 5 hours and supplemented with concentrate (17% CP, 5% BW) daily. Animals were hand milked once daily at 8.00 am for 12 weeks. Stage of lactation significantly (P < 0.05) affected specific gravity of milk while parity did not have any significant effect. Daily milk mass and daily milk volume decreased linearly from early to very late stage of lactation; 158.276 to 34.411 g and 156.054 to 34.410 cm3 respectively. Average composition of milk components were 3.78%, 4.49%, 0.76%, 4.99%, 9.02% and 14.00% for protein, lactose, ash, fat, solid non-fat and total solids respectively. Stage of lactation significantly (P<0.001) affected milk protein, lactose, fat, solid non-fat and total solid except ash. However, parity did not significantly affect any of these milk constituents. The contents of total solids, solid non-fat, fat and protein were positively correlated with. On the other hand, phenotypic correlations between lactose, protein and fat were negative. It was concluded that stage of lactation exerts significant influence on specific gravity and composition of milk of WAD sheep while parity did not.
Keywords: stage of lactation, parity, specific gravity, ewe milk, composition