The nutritive value of macadamia oil cake meal and wood ash as alternative feed ingredients for chickens in rural areas

Abstract

The majority of South African household live in poverty with a limited variety of foods available in their home. In most rural villages domestic poultry plays an important role in improving household food security, but is limited by shortage of feed and high feed costs. Using non-conventional feed ingredients in poultry diets may ease the situation of malnutrition in rural populations, providing the family with high quality animal protein at more affordable prices. Macadamia oil cake meal (MOCM) is an inexpensive by-product from the macadamia oil industry of the Limpopo Province. Although it is relatively high in crude protein (20-25%), MOCM has never been considered as a feed ingredient for poultry feeds. The high and varying fibre content (up to 25%, depending on the extrusion method applied) of MOCM may render it unsuitable as an ingredient for high producing poultry such as broilers. The question, however, arouse whether the inclusion of MOCM in the growing diet of meat-producing chickens typically found in rural areas, would be cost-effective. Calcium (Ca) in poultry rations is usually supplied as calcium carbonate from limestone. Wood ash (WA) from fireplaces at homestead in rural villages was found to be rich in Ca (approximately 26%) and has the potential of being a free and readily available Ca supplement that could easily be added to the diet. The purpose of this study was to evaluate the effects of MOCM and WA as alternative feed ingredients in growth rations for chickens in rural areas. New Hampshire chickens were randomly divided into eight treatment groups with four replicates per treatment and twelve chicks in each replicates. The chicks were housed in an environmentally controlled broiler house from day-old to 15-weeks of age. Four diets were formulated, one without MOCM and the other three containing different levels of MOCM, viz. 10, 50 and 100% plus salt and a trace nutrient mixture. Each of these treatments was split in two with one receiving limestone (CaCO3) and the other WA, as Ca sources, giving eight treatments in total. All the treatments received diets with a Ca level close to 1 %. Parameters measured on weekly basis were body weight (BW), feed intake (FI), and body weight gain (BWG) and feed conversion efficiency (FCE) was determined. The analysis of the carcass composition and tibia bone strength was done at the end of the 15 week period. An analysis of variance with the ANOVA model (SAS) was used to determine the significance between different treatments for the balanced data. Significance of difference (5%) between means was determined by multiple comparisons using Tukey t-test. The treatment of 100% MOCM was terminated at eight weeks since the chickens had retarded growth and low body weight gains, demonstrating that the 100% MOCM diet both with and without Ca were not feasible. The BW and feed intake of the diet of 100% MOCM plus WA was, however,significantly higher than the diet of 100% MOCM plus lime. However, the inclusion level of up to 50% MOCM had no significant differences in (muscle and fat), except for FI, BWG and FCE between treatment diets. In conclusion, the results prove that MOCM can be added to the ration at a 10% concentration level without any adverse effect on growth. Higher inclusion levels of MOCM might also be beneficial,especially when included at an older age of the bird. Wood ash proved to be an efficient Ca source, as the substitution of limestone with WA showed no negative effect on the tibia bone parameters measured. Copyright