Energy and protein supplementation can improve liveweight gain of steers grazing good quality tropical pasture in the wet season

Abstract

This experiment aimed at maximising wet season liveweight gain (LWG) of cattle grazing good quality tropical pasture. Twenty-five Brahman crossbred steers (203 ± 4.2 kg) were allocated into 5 treatments, namely control (Con; grazing only), grazing + molasses/urea mixture (MU) at 0.5% liveweight (LW) (5MU) or 1% W (10MU), and grazing + mixture of molasses/urea (55%), fish meal (25%) and whole cottonseed (WCS; 20%) at 0.5% W (5MWF) or 1% W (10MWF). Steers grazed fertilized pangola grass pasture (Digitaria eriantha cv. Steudal) for 84 days. Pasture DM availability was maintained at > 1.5 t/ha. The Mean green leaf yield was 1.9 t DM/ha, in vitro DM digestibility was 64%, and crude protein content was 15%. The LWG of Con steers was 960 g/d. Providing MU did not increase LWG, but inclusion of fishmeal and whole cottonseed markedly improved LWG above control by 34% and 39% for 5MWF and 10MWF, respectively. Levels of supplement had no affected on LWG. It is concluded that supplementing rumen fermentable energy and protein alone did not increase LWG of steers grazing good quality tropical grass pasture, but the inclusion of rumen bypass protein and energy in supplement significantly increased LWG, as a result of the higher bypass protein and energy intake.