The Relationship between Milk Constituents of Lactating Ewes and Linear Body Measurements of their Lambs
The objective of this study was to evaluate the relationship between milk constituents of ewes and linear body measurements of their lambs maintained under a semi-intensive management system. Twenty-eight ewes comprising 10 Yankasa (YA), 8 West African Dwarf (WAD) and 10 crossbred (YAxWAD) sheep with body weight range of 15-26 kg average age of 2½ years and lambs between 1 and 8 weeks were used for the study at the Teaching and Research Farm of the Federal University of Technology, Akure, Ondo State, igeria. Milk measurement commenced from a week post-partum to allow lambs have access to their dams’ colostrum. The lambs were separated between 7 pm and 7 am from ewes which were then milked dry. The milk constituents determined were protein (PA), fat (FT), ash (AS) and lactose (LA). The linear body measurements of the lambs such as height at withers (HT), body length (BL), heart girth (HG), shoulder width (SW), tail length (TL), neck length (L), neck circumference (C), face length (FA), hind leg length (HL), foreleg length (FL), ear length (EA), head width (HW) and rump height (RH). The data were subjected to One-way analysis of variance (AOVA), the means were separated using Duncan’s multiple range test and Pearson correlation and Multiple stepwise regression parameters were estimated using SPSS. Fat and ash were similar for all ewes, while the milk protein and lactose content were affected by genotype. The mean weight (kg) of lambs of West African Dwarf, Yankasa and the West African Dwarf x Yankasa lambs were 4.46 ± 0.21, 5.41± 0.21 and 5.02 ± 0.21, respectively. There was significant effect (P<0.05) of genotype on height at withers, body length, foreleg length, hindleg length, facelength, earlength, tail length and rump height with the Yankasa lambs showing a consistently higher values in these body measurements than either the West African Dwarf and crossbred ewes. Dam’s protein content was significantly correlated with lamb’s heart girth (0.24; P<0.01) and neck length (0.20; P<0.05). Other parameters that were significantly correlated include dam’s fat content and lamb’s neck length (0.26; P<0.01) and face length (0.18; P<0.05). Dam’s milk ash was significantly but negatively correlated with lamb’s tail length (-0.22; P<0.05). Lamb’s heart girth and neck length were superior to other linear body measurements in estimating protein and fat content of milk followed by foreleg length and heart girth, respectively while heart girth was superior in estimating lactose content. The best single measurement that can be used to predict ash content was tail length. Generally, accuracy of prediction of compositional traits was low (0.03-0.17), however, lamb’s heart girth could be used in the selection of lactating ewe with high quality milk.
Keywords: Milk constituents, lactating ewes, body measurements, lamb
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