Effect of parity on changes in udder traits, milk yield and composition of West African dwarf sheep during lactation

Abstract

Twelve West African Dwarf sheep, comprising four ewes in each of the Parities 1, 2 and 3, were used to determine the effect of parity on udder traits during lactation, milk yield and composition. Udder length, udder width, udder circumference, udder volume, teat length, teat width, teat circumference, distance between the teats and teat height from the ground of sheep were measured in centimetres (cm) weekly for 12 weeks of lactation, commencing from Day 4 postpartum. Parity highly influenced (P < 0.05) udder traits, except udder volume (P > 0.05). The udder length, width and circumference were higher (P < 0.05) in Parity-3 ewes than Parity-1 and -2 ewes. A similar trend was shown for teat length, width and circumference. Parity had no effect (P > 0.05) on udder volume, but significantly (P > 0.05) affected distance between the teats and teat height from the ground. With the exception of udder volume, all traits peaked by the 3rd week of lactation, and gradually declined thereafter. Milk yield and milk weight peaked by the 3rd week postpartum and these were higher for ewes in Parity 3. Milk yield and milk weight declined faster in ewes in Parities 1 and 2 than they did in Parity-3 ewes (P < 0.05) as lactation length increased. In regard to milk composition, moisture, protein and fat, but not total solid, solid-not-fat and lactose, were greater (P < 0.05) in Parity-3 ewes both at peak milk yield (3rd week of lactation) and end of lactation. From these findings, we conclude that parity type plays a significant role in influencing udder traits, milk yield and milk quality in ewes.