Growth performance, health and meat quality of broilers fed diets containing Kalahari melon (Citrullus lanatus)seed cake

Abstract

The poultry industry is facing challenges of inadequate supply of feed protein sources which subsequently leads to high costs. The study was conducted to determine the effects of dietary inclusion of Kalahari melon seed cake (KMSC) in diets on health and performance in broiler chicken. Five dietary treatments were assigned to four hundred (400) mixed-sex Cobb 500conventional broiler diet (optifeeds) control; conventional broiler diet + 5% KMSC; conventional broiler diet + 10% KMSC; conventional broiler diet + 15% KMSC and conventional broiler diet + 20% KMSC. Each treatments had eight replicate with a pen holding ten broilers as an experiment unit. The experimental diets were fed ad libitum along with freshwater for a period of 6 weeks. Broilers were fed starter (0-14 days), grower (14-28 days) and finisher (28-42 days). The results indicated significant effects of diet (P <0.05) on overall average daily feed intake (ADFI), average body weight gain (ABWG), average daily gain (ADG) and feed conversion ratio (FCR) in dietary inclusion of KMSC. Broilers fed a 15% KMSC diet had the highest overall ADFI (78.38 g ± 0.93). The highest overall ADG was obtained in the control-fed diet (43.63 g/d ± 0.51) whilst the lowest overall ADG was obtained in the 15% (39.83 g/d ± 0.51) fed broilers. Nevertheless, broilers fed control (1883.13 ± 22.17) and 5% (1860.50 ± 22.17) diets had the highest final weights. With regards to overall FCR, the birds fed the control and 5% KMSC diet had the lowest values while those fed the 15% KMSC had the highest value. The highest cumulative weight gain (CWG)obtained was observed from control and 5% KMSC whilst the lowest values were from broilers fed 15% KMSC. The results demonstrated that dietary inclusion influenced protein consumtion (PC), protein efficiency ratio (PER), specific growth rate (SGR) and growth efficiency (GE). Dietary treatments significantly affected the haematology parameters, however no significant effects were found on red blood cell (RBC). The dietary treatments showed effect on serum parameters. At 42 days, broilers were slaughtered in order to determine the carcass traits and meat quality parameters. Four broilers in each replication were choosen randomly to be used for evaluation. The findings from the study indicated that all carcass traits were influenced by diet (P<0.05), apart from dressing % and thigh ratio. Control and 5% KMSC fed broilers had the highest hot carcass weight (1431.62 g ±26.55), (1426.28g ± 26.55), cold carcass weight of (1373.56g ± 26.40), (1369.21 ± 26.40)respectively. The internal organ sizes of broiler were influenced by dietary inclusion apart from caeca and colon. The dietery treatments significantly influenced meat quality parameters. Broilers fed 15% KMSC had lighter meat color (L*) in both 0 h and 24 h post slaughter. Moreover, broilers fed 15% KMSC had higher cooking loss, whilst those fed 5% KMSC had higher shear force. Also measured, were the tibia parameters, bone breaking strength, bone ash and macro mineral content. Diet influence (P <0.05) tibia biomechanics parameters. Inclusion of KMSC in broiler diets increased the tibia linear parameters. Diet also influenced macro minerals content. The broilers fed 20% KMSC recorded the highest values of total ash, moisture and phosphorus content while broilers fed the control diet had the lowest. The broiler chickens fed 20% KMSC recorded the highest values on all the macromineral content. Deformation was observed in the proximal metaphyseal tibiotarsus region of broiler tibiae fed 5%, 10%, and 20% KMSC. This deformation is linked to the gross lesion analysis. Therefore, this led to the conclusion that since KMSC promoted comparable growth performance, nutrient utilization, blood parameters, carcass traits, meat quality, internal organs and bone development parameters, it might eventually replace soybean meal