The effects of cottonseed cake with or without molasses on feed utilization, purine excretion, and milk production of Boran (Bos indicus) cows fed a mixture of wheat and oat straw

Abstract

The effects of 1.35, 1.80, or 2.25 kg dry matter (DM) of cottonseed cake, with (1.85 kg DM) or without molasses, on straw intake, diet digestibility, live-weight change, excretion of purine derivatives (PD), and milk production of Boran (Bos indicus) cows were studied. There were no significant (P > 0.05) interactions. Straw intake was 0.47 kg DM lower (P < 0.001) showing a substitution effect of 254 g kg-1 with molasses. Straw intake tended also to decrease from 5.18 to 4.94 kg DM (P < 0.15) with a daily substitution of 107 g kg-1 with increasing levels of cottonseed cake. Molasses increased DM and organic matter (OM; P < 0.01) but decreased crude protein (CP; P < 0.001) and neutral-detergent fibre (NDF; P < 0.01) digestibilities. Molasses (P < 0.05) and increasing levels of cottonseed cake (P < 0.01) increased daily milk yield from 3.06 to 3.26 and from 2.96 to 3.32 kg, respectively. Molasses increased live-weight by 300 g day-1 (P < 0.05). Increasing levels of cottonseed cake caused a live-weight change of 69 g to 467 g day-1 (P < 0.05). A supply of microbial-N increased (P < 0.001) in molasses diets but microbial-N production kg-1 digestible OM was not affected by treatments (P > 0.05).