Authors: O.A.OSINOWO, M.N.BEMJI,
Nigerian Society for Animal Production 37(2): 279-284, 2010
Abstract
Udder circumference (Ue) and distance between teats (DBT) measured before and after milking were used to determine CUC (UC before milking minus UC after milking and CDT (DBT before milking minus DBT after milking). All four parameter were utilized as independent variables in two standard regression models (linear and multiple linear) to develop equations for prediction of daily milk yield from 202 weekly records of 17 lactating does, consisting of 8 West African Dwarf (WAD) and 9 Red Sakata (RS) goats. WAD and RS goats had similar mean values/or daily milk yield (270.34±12.47ml vs 265.26±14.51ml) and UC (28.49±0.33cm vs 28.81 ±0.39 cm), but differed very significantly (P<0.001) in DBT (7.33 ±0.11cm and 5.82 ±0. 13 cm). Both models had significant (P<0.001) RJ values ranging from 0.244 to 0.757. UC was the best index of milk yield W = 0.688) followed by CUC (R = 0.476) in the linear regression equation while DBT and CDT yielded lower R value (0.244 vs 0.258). Inclusion of all four parameters in the multiple linear regression equation yielded the highest R (0.757). The prediction equation was Y =- 441.443+25. 739X +23.349X -2I.265X+61.080X in which Y is milk yield, XI, X4 represent UC, CUC, DBT and CDT respectively. Positive and significant (P<0.001) phenotypic correlations were observed between UC and milk yield (0.759), CUC and milk yield (0.690), DBT and milk yield (0.498), CDT and milk yield (0.508) . In the current practice of collecting weekly records, early prediction of future milk production from udder circumference measured prior to milking will be accurate using linear regression predictive equation. Alternatively, if more traits related to udder size such as UC, CUC, DBT and CDT are incorporated as independent variables in multiple linear regression equation; milk production could be predicted with better accuracy