Physical-Chemical Composition of Milk and Fiber Quality in Hair Goats and the Phenotypic Correlations Between Milk Composition and Fiber Traits

Abstract

The objective of this study was to investigate physical-chemical composition of milk and fiber quality in Hair goats and to evaluate the phenotypic correlations between milk composition and fiber traits. The mean values of milk fat, protein, lactose, non-fat solid, total solids, lactic acid and pH in Hair goats' milk were 4.09, 3.53, 5.15, 9.36, 13.45, 0.22% and 6.61, respectively. The mean values of fiber length, fiber diameter, breaking strength, fiber elasticity and clean hair yield were 9.13cm, 80.93 mu m, 13.67g, 35.89% and 91.61%, respectively. The effect of lactation stage on physical-chemical parameters of milk was significant (P<0.05). Fat content of milk was highly and positively (P<0.01) correlated (0.71) with total solids. Protein was highly and positively (P<0.01) correlated with lactose (0.99), non-fat solid (0.98) and total solids (0.68) contents. There were not significant correlations between all fiber parameters. The phenotypic correlation between fiber diameter and protein content of milk was -0.54 and between fiber diameter and total solids was -0.36 and between fiber diameter and lactose was -0.51. In conclusion, fat content of milk was the lowest in the early lactation stage. Protein, lactose, non-fat solid and total solids contents were the highest in the mid lactation stage. pH was the highest in the late lactation stage. The diameter of the fibers of hair obtained from Hair goats was high. Also, results indicate that there was highly and positively correlation between fat and total solids, protein and lactose, protein and non-fat solid, protein and total solids contents. However, there was significant negatively correlation between fiber diameter and protein content of milk, fiber diameter and lactose, fiber diameter and total solids. (C) 2016 PVJ. All rights reserved