The ratio of roughage to concentrate on milk secretion rate in goats fed Stylosanthes hamata hay

Abstract

An experiment was conducted to evaluate the effect of roughage to concentrate ratio (R:C) on milk secretion rate (g/h) in goats using a cross-over design in which each goat passed sequentially through all the treatments in random order. The treatments (R: C) were: A = 70 percent roughage : 30 percent concentrate; B = 50 percent roughage : 50 percent concentrate e and C = 30 percent roughage : 70 percent concentrate. In the experiment, seven goats were milked once a day, from the 2nd to 8th week of lactation, thrice per week for 2 weeks per treatment. The animals were fed at 4 percent body weight (DM basis). The feed consisted of Stylosanthes hamata hay (S. hamata hay) and a 17.2 percent CP concentrate ration. Data were analysed using the treatments as main effect with live weight and week of lactation as covariates. There was no significant treatment effects on milk secretion rate (P>0.05). Overall milk secretion rate was 5.23g/h. Week of lactation also had no significant effect (P>0.05). However, live weight of doe at time of milking had a highly significant effect (P>0.001) with milk secretion rate increasing by 0.41g/h per kilogram live weight. The R2 values for the predictive mathematical relationship for goats fed Stylosanthes hamata hay at 4 percent body weight in the dry season was R2 = 0.888. It can therefore be deduced that for a lactating doe in the 5th week of lactation at 20kg body weight fed at 4 percent with Stylosanthes hamata hay to concentrate ratio at 70 percent roughage : 30 percent concentrate would give a milk secretion rate of 6.717g/h while at 50 percent roughage : 50 percent concentrate it would give 6.662g/h and 30 percent roughage : 70 percent concentrate level would give 7.054g/h. 

Keywords: Stylosanthes hamata hay, concentrate, goats, milk secretion