Growth of male WAD sheep fed cassava waste or dried sorghum brewer's grains as supplements to tropical grass/legume forage

Abstract

Eighteen 4–5-month-old individually penned West African Dwarf (WAD) rams (mean weight 14 kg) were offered one of three rations for 112 d to determine growth rate on a supplemented Panicum/Centrosema (6:1) forage ad libitum and forage/concentrate ratio of 56:44. Grass and legume contained 11.9 and 23.3% CP and 31.7 and 31.2% crude fibre, respectively. Supplements fed at 2%/BW contained 97% cassava wastes (CW), 97% dried sorghum brewer's grains (DSBG) or 48.5% each of CW and DSBG, and 5.4, 33.2 and 18.1% CP, respectively. Digestibility and nitrogen balance of the rations were determined with three other rams in a 3 × 3 Latin square experiment. Intake and digestibility of DM and energy of the rations were similar. Nitrogen intake, N absorbed and urinary N loss increased directly with dietary DSBG levels ( P < 0.01). High starch and fibre in CW, lowest N content and intake from 97% CW supplement were implicated in least N digestibility of the supplement. At low N intake, faecal N loss was greater than urinary N excretion, but with increased N, more N was lost in urine than faeces. All animals were in positive N balance. Average daily BWG ranged from 12 to 68 g. DSBG was a better supplement than CW but the mixed supplement was best for highest N retention, average BWG as well as feed, energy and protein conversion efficiencies. It is concluded that DSBG is an energy- and protein-rich feed for ruminants. Its inclusion at 48.5% level with 48.5% CW in a Panicum-Centrosema forage supplement promoted maximum daily gain among WAD rams, while 97% level of either feed in the supplement depressed growth.