Inclusion of enzymes in Kalahari melon based broiler diets : effects on growth performance and meat quality

Abstract

The poultry industry is one of the fastest growing within the agricultural sector. Feed ingredient such as soybean meal have been used widely used in broiler diets but are becoming expensive mainly due to the competition between humans and animals for the same protein sources. It is therefore imperative to explore unconventional protein sources specifically indigenous legumes with potential to supply good quality protein in broiler diet. Therefore, this study was conducted to evaluate the inclusion of enzymes in Kalahari melon based diet on growth performance, protein utilization efficiency, serum biochemistry, meat quality and bone development of broiler chickens. Five isoenergetic and isonitrogenous diets were formulated with the inclusion of Kalahari melon (KM) cake at 10% in place of soybean meal and various enzymes combinations to the grower and finisher diets. The following diets were formulated: Control (commercial diet), KM (commercial diet + 10% KM), KMP (commercial diet + 10% KM + protease), KMXB (commercial diet + 10% KM + xylanase and β-glucanase) and KMXAP (commercial diet + 10% KM + xylanase. amylase and protease). Four hundred unsexed day-old broiler chicks were random distributed to the five dietary treatments, replicated 8 times. The chicks were offered commercial starter diet from 1 to 14 days. The experimental diets were offered during the grower and finisher phase. From the results, Broilers fed control diet had the highest average daily feed intake (ADFI) in the grower phases, whilst birds fed the KMP diet had the lowest. Similarly, the birds fed the KMP diet had the lowest average daily gain (ADG) compared with the other treatments. With regards to the feed conversion ratio (FCR), the birds fed the KMP diet had the highest value while those fed the KMXAP had the lowest value. In the finisher phase, the birds fed the control diet had the highest ADFI and ADG respectively compared with the other treatments. The birds fed the control diet also had the lowest FCR. Like the grower phase, the birds fed the KMP had the lowest values for ADFI and ADG respectively. In grower phase, protein consumed was higher in birds fed KM followed by control. Protein efficiency ratio (PER) and specific growth rate (SGR) was however, highest in iv birds fed the KMXAP diets. In all instances, the birds fed the KMP diets had the lowest values for PC, PER, SGR and growth efficiency (GE) in the grower phase. In the finisher phase, the birds fed the control diet had the highest PC although not significantly different from all other treatments apart from the KMP diet. Similarly, the birds fed the control diet had the highest value for PER followed by those fed KMXB diet. SGR was however highest in birds fed the KMXB diet followed by those fed the KMXAP diet. As with the grower phase the birds fed the KMP diet consistently had the lowest values for all parameters. Birds fed control had the highest (P < 0.05) symmetric dimethylarginine , whilst birds fed KMP had the lowest. Birds fed control had the highest amount of SDMA followed by the KMXAP diet, whilst KMP had the lowest. Birds fed KM had the highest amount of GLOB whilst KMXAP had the lowest. Birds the fed KMXB had the highest amount of ALB/GLOB followed by KM. However, birds fed KMP had highest amount of alkaline phosphate followed by the KMXAP. Broilers fed KMXB had the highest final weight, whilst KMP had lowest. Broilers fed control had the highest breast weight, whilst KMP had lowest. No significant effects were found between the dietary treatment and hot carcass weight (HCW), cold carcass weigh (CCW), carcass yield, breast index, thigh index and drum index. Broilers fed KMXAP had lighteR meat color (L), whilst control had darker meat color in both 0 h and 24 h P slaughter. Moreover, broilers fed KM had higher cooking loss, whilst those fed KMXAP had higher shear force. Additional, diet did not affect meat pH ,meat colors and water holding capacity . Broilers fed KMXB had highest tibia weight and tibia diameter proximal compared to other treatments. Broiler fed KM and KMP had highest tibia width diameter, whilst control had lowest. With regards to tibia length and tibia diameter distal end, diet did not affect the tibia parameters. In conclusion, enzymes inclusion in diets containing Kalahari melon improved growth performance, meat quality and health and welfare of broiler chickens. Inclusion of enzymes in Kalahari melon-based diets is therefore, recommended for improved broiler production and decreased raw material costs in feed production.