Influence of Acacia tortilis leaf meal-based diet on serum biochemistry, carcass characteristics and internal organs of finishing pigs

Dietary inclusion of tannin-rich leguminous leaf meals beyond threshold levels can impose toxicity and compromise welfare of pigs. The objective of the study was to determine the response of metabolites, carcass characteristics and internal organs of finishing pigs to Acacia tortilis leaf meal inclusion levels. Thirty Large White × Landrace pigs (61.6 ± 1.23 kg bodyweight) were randomly allotted to six dietary treatments, to give five replicates per treatment. The treatments contained 0, 50, 100, 150, 200 and 250 g/kg of A. tortilis leaf meal and were rendered iso-energetic and iso-nitrogenous. An increase in A. tortilis inclusion was related to an initial increase and then a decrease in feed intake (P < 0.05), weight gain (P < 0.001) and feed conversion ratio (P < 0.05). Serum concentrations of iron and activities of aspartate aminotransferase and alkaline phosphatases increased quadratically (P < 0.001) as A. tortilis leaf meal increased. There was a significant linear increase in alanine aminotransferase activity with leaf meal incremental level. Hepatosomatic index, scaled kidney weight and scaled heart weight increased linearly (P < 0.001) as A. tortilis increased. There was a quadratic increase in the relative weight of lungs (P < 0.001) as leaf meal increased. Although quadratic decreases (P < 0.01) in cold-dressed mass and dressing percentage were observed with incremental levels of A. tortilis leaf meal, there was a linear decrease (P < 0.05) in backfat thickness. It was concluded that serum biochemistry, internal organs and carcass characteristics respond differently to increases in A. tortilis inclusion. The A. tortilis leaf meal can be supplemented in finishing pig diets at low levels before feed efficiency and carcass characteristics are negatively affected.