Intra-wet season variation in rangeland fodder quality influences feed conversion, growth and methane emissions in West African zebu cattle

Livestock in sub-Saharan Africa is a major contributor to greenhouse gas emissions, particularly enteric methane (eCH 4 ), with emissions intensities and yield often elevated. In this region, wet-season rangeland fodder is the primary feed source for livestock. This study evaluated the effects of fodder growth stage and feed allowance on feed intake, digestibility, average daily gain (ADG), feed conversion ratio (FCR), and eCH 4 emissions in cattle. Over a 112-day period, including a 14-day adaptation and a 98-day data collection phase, ten Sudanese Fulani zebu bulls (52 ± 1.2 months of age, 195 ± 14.6 kg body weight) were fed green rangeland fodder. They were divided into two groups of five animals each: one received fodder at a high allowance level of 4.5% of body weight (BW) dry matter (DM) basis (4.5ING), while the other received 2.5% of BW (2.5ING). Voluntary intake, digestibility, and eCH 4 (GreenFeed®) were measured daily across three fodder growth stages: vegetative stage (VeS), reproductive stage (ReS), and mature stage (MaS). ADG and FCR were assessed fortnightly. DM intake decreased progressively from VeS to MaS with the highest values recorded for 4.5ING (P