Effects of dietary inclusion of leucaena leaf meal with and without ferrous sulphate on the digestibility of dietary components and growth of pigs over the weight range 20–60 kg

Two experiments were conducted to evaluate the effect of feeding diets containing leucaena leaf meal (LLM) and ferrous sulphate supplementation to pigs. Four diets, containing 0, 100, 200 g kg−1 LLM and 200 g kg−1 LLM treated with 4 g kg−1 ferrous sulphate, were compared. In the first experiment, four castrated male pigs (average weight 20 kg) were randomly allotted to the four diets in a 4 x 4 latin square design, in order to evaluate the digestible components of the diets. Mean crude protein digestibility was significantly (P < 0.05) lower in the diets containing a high level of LLM (200 g kg−1) compared with that of the control diet (0 g kg−1 LLM) and the diet containing a low level of LLM (100 g kg−1). The digestibility of crude fibre increased significantly (P < 0.05) with increased level of LLM in the diets, being 29.4, 42.9, 40.7 and 44.4% for dietary treatments 0, 100, 200 g kg−1 LLM and 200 g kg−1 LLM treated with ferrous sulphate, respectively. The calculated metabolisable energy (ME) was slightly lower for the control diet compared with the other treatments. The mean differences in the rate of nitrogen retention and the efficiency of nitrogen utilisation by the pigs were not significantly (P < 0.05) different between treatments. In the second experiment, 32 pigs, of equal number of females and castrated males, with average initial body weight of 21 kg were blocked by sex and randomly allocated to the four diets. Feed intake and liveweight gain of the animals were recorded up to 60 kg, when physical carcass measurements were taken. ed on the high level of LLM without ferrous treatment recorded significantly (P < 0.05) lower average feed intake, daily gain and feed conversion efficiency. These animals lost hair from their bodies and had significantly (P < 0.05) heavier kidneys compared with their counterparts on the dietary treatments 0, 100 g kg−1 LLM and 200 g kg−1 LLM with ferrous treatment. The higher mimosine content of this diet was the probable cause of the inferior performance of the pigs on this treatment. Ferrous sulphate inclusion improved the performance of pigs fed a high level of LLM. It was concluded that pigs may be raised on diets containing up to 200 g kg−1 LLM treated with 4 g kg−1 ferrous sulphate. The optimum combination of LLM and ferrous sulphate needs further investigation.