Smallholder pig production in Southern Africa is constrained by feed shortages and the demand for cereals for food. This makes it important to identify alternative feed for pigs.
A study in South Africa evaluated the nutritive value of acacia tortilis leaf meals, which has relatively high crude protein and favourable mineral concentration, to determine the response in growth performance of finishing pigs.
Makhathini Research Station in Jozini, South Africa, individually hand harvested 8 trees of each of 5 dominant leguminous trees:
A total of 30 finishing male F1 hybrid (Landrace × Large White) pigs with an initial weight of 60.6 (s.d. = 0.94) kg were randomly allotted to 6 dietary treatments containing 0, 50, 100, 150, 200, 250 g/kg dry matter inclusion levels of acacia tortilis leaf meal. Each treatment diet was offered ad libitum to 5 pigs in individual pens for 21 days.
Acacia tortilis and acacia xanthophloea leaf meals had the highest crude protein and fat content among all the acacia species. The neutral detergent fibre and acid detergent fibre concentrations in the leaves varied significantly across Acacia species. Average daily feed intake, average daily gain and gain:feed ratio was measured weekly. There was an increase in both average daily feed intake and average daily gain as A. tortilis leaf meal increased, before they started to decrease. Using piecewise regression (brokenstick analyses), it was observed that A. tortilis leaf meal can be included up to 150 g/kg DM in finisher pig diets. The gain:feed ratio was linearly reduced with incremental levels of A. tortilis leaf meal in the diets.
Inclusion of leaf meal above 150g/kg was associated with depressed average daily feed intake and average daily gain. Acacia tortilis leaf meal can be included up to 150 g/kg dry matter in finisher pig feeds, without negatively affecting animal performance. The ability with which pigs utilise leaf meal-based diets improves with duration of exposure (adaptation) to such diets.
This study was conducted by M. Khanyile and M. Chimonyo and was a collaboration between the Department of Agriculture and Environmental Affairs, Makhathini Research Station, and the Animal and Poultry Science department at the University of KwaZulu-Natal, South Africa.