Effect of environmental factors on the digestibility and voluntary feed intake of kikuyu
Digestion trials using sheep and voluntary feed intake (VFI) trials using long yearling heifers in Calan gates were conducted in the spring, summer and autumn. Five years of digestibility data, amounting to 82 digestion trials, was pooled for this study. Voluntary intake data was pooled for the three years of intake trials, amounting to 38 intake trials. These data and the daily maximum temperatures, rainfall and evaporation recorded at and prior to the digestion and intake trials at Cedara were pooled, analysed using multiple regression techniques, and regressed on dry matter digestibilty and VFI, to examine the influence of environment on the nutritive value of the herbage and to develop simple linear regression models for predicting kikuyu quality and intake. Rainfall and temperature in the period of cutting (plot preparation) and fertilization had a negative effect on digestibility, irrespective of the stage of re-growth at harvesting, 20, 30 or 40 days later, and a combination of the two proved significant, accounting for the most variance in DMD. Temperature depressed DMD by 28.1 g/kg DM per degree rise in temperature (oC). Temperatures recorded during the cutting and fertilization phase were highly negatively correlated to VFI, irrespective of stage of re-growth.
Keywords: Pennisetum clandetinum, DMD, VFI, environmental temperature, rainfall