Effect of physical restriction and supplementation with Leucaena leucocephala on goat growth

Young Landim wethers were either free-range or tethered on 3-m ropes on native pasture in semi-arid Southern Mozambique. A leucaena leaf supplement at 2% BW (DM basis) was given to half of the animals. The experiment took place over the dry season of 2 years with very different rainfall (327 mm and 723 mm). There was no interaction (P > 0.05) between physical restriction and supplementation for average daily gain (ADG) or carcass characteristics in either year. In the drier year restriction lowered ADGs to 18.6% of the unrestricted animals' ADG (P = 0.0018). In the wetter year this same effect resulted in ADGs in the tethered animals of 36.9% of the free-range animals' ADG (P = 0.001). Goats supplemented with leucaena gained 184% of the BW gained by the unsupplemented animals in the low-rainfall year (P = 0.0038) and 168% in the high-rainfall year (P = 0.001). Carcass % of BW as well as kidney, heart, carcass and liver masses were higher and digestive tract % of BW were lower in free-range animals (P < 0.05) only in the high-rainfall year. Carcass and kidney weights were higher (P < 0.05) in the drier year and liver higher (P < 0.05) during both years for the supplemented animals. Tethering appeared to affect goat development negatively, especially in the dry year, whereas supplementation with leucaena was equally beneficial in dry and wet years.