Chemical preparation of NaOH—Keratin hydrolysate for improving the nutritive value of wheat straw

Abstract

Wool and chicken feathers were used as sources of keratin hydrolysates for enriching wheat straw in ruminant diets. The optimal conditions for the preparation of keratin hydrolysates from keratin concentrations of 2–12% were attained by hydrolysis of wool and feathers for 6–9 min at boil. The amino-acid profile of the white and black wool hydrolysates were similar, having 1.5–4 times greater amounts of glutamic acid, methionine, tyrosine, histidine and lysine than feather hydrolysates. Keratin hydrolysates of 8.5, 11.5 and 13.9% were sprayed on wheat straw at the rate of 100 ml 100 g −1. In-vitro dry-matter digestibilities were significantly ( P < 0.05) increased with 8.5% keratin-hydrolysate supplement, but no further improvement was noted with higher levels of supplement. The average in-vitro dry-matter digestibility of untreated wheat straw was 44.72%. However, this increased by 21.1–23.7% after treatment. Nitrogen loss from the hydrolysates during treatment ranged from 12 to 15%.