Influence of age and sex on carcass and meat quality traits of scavenging guinea fowls.

Doctor of Philosophy in Animal Science. University of KwaZulu-Natal, Pietermaritzburg 2016.

The purpose of the study was to determine the effect of age and sex on carcass and meat quality characteristics of scavenging guinea fowls in communal production systems. A total of 151 smallholder farmers in Wedza district of Zimbabwe participated in a survey to identify management practices and possible opportunities and constraints in guinea fowl production. Guinea fowls are a tool of alleviating poverty as a potential source of food and income for women who dominated ownership (53.4 %). The majority of the household heads were aged below 55 years. Crops were the main source of income to 46.8 % households whilst 9.8 % households depended on livestock as a source of income. The average guinea fowl flock size per household was 11.36 (SD = 15.44). Guinea fowls were kept mainly for households consumption (ri = 0.44) and income generation (ri = 0.35). Eggs were considered as the main food source followed by meat. About 66.4 % of households did not practice breeding, with the traits selected for included body frame (ri = 0.39), body weight (ri = 0.12) and mothering ability (r = 0.11). The majority of farmers (97.3 %) supplemented feed using locally available feed resources and provided water for their flocks. Keets struggled most from water shortages (ri = 0.45). Predation by birds of prey (ri = 0.31), diseases (ri = 0.22) and wild animal attacks (ri = 0.19) were the main causes of mortality. Ethnoveterinary medicines such as Aloe species and Capsicum frutescens were mostly used to treat diseases. The main constraints which reduced production were lack of capital and feed, and predation. Carcass characteristics, internal organ weights and physicochemical properties of breast meat from 48 scavenging guinea fowls were determined. Guinea fowls comprised of 25 females and 23 males made up of 21 growers (4 – 8 months old) and 27 adults (one year old). In addition, the carcass characteristics, internal organ weights and physicochemical properties of 48 scavenging chickens were used as a benchmark with no statistical comparison with guinea fowls. Chickens comprised of 18 females and 30 males with 19 growers (4 – 8 months old) and 29 adults (one year old). Adult guinea fowls had higher (P< 0.05) cold dressed weight than growers (673.1 ± 11.40 and 630.5 ± 12.34 g/kg BW, respectively). Dressing percentage was higher (P < 0.05) in adult (69.3 ± 0.92 %) than grower (64.7 ± 1.00 g) birds. There was no influence (P > 0.05) of sex on carcass weight. Growing guinea fowls had significantly heavier (P < 0.05) relative weights of leg, thigh and drumstick as compared to adults. Breast weight in males was heavier (P < 0.05) than in females (198.7 ± 5.37 g and 178.8 ± 6.25 g, respectively). Relative abdominal fat weight was higher (P < 0.05) in adults than in growers (24.5 ± 0.57 versus 20.7 ± 0.62 g/kg BW, respectively). Females had significantly higher abdominal fat weight than males. The back weight in adults of 148.7 ± 6.02 g was higher (P < 0.05) than 120.6 ± 6.52 g in growers. Sex had no significant effect (P < 0.05) on carcass remainders. Growers had heavier (P < 0.05) kidney, heart, lung and gizzard weights than adults. Total intestine length in growers (113.2 ± 4.15 cm/kg BW) was longer (P < 0.05) than in adults (74.3 ± 3.90 cm/kg BW). Similarly, growing birds had longer (P < 0.05) large intestines than mature birds. No sex differences (P > 0.05) were observed for intestinal lengths. Dry matter content decreased (P < 0.05) with age from 28.7 ± 0.81 % in growing birds to 24.7 ± 0.75 % in adult birds. Ether extract and ash were higher (P < 0.05) in adult than grower birds. Females had more (P < 0.05) fat content than males. Age and sex had no effect (P > 0.05) on crude protein. Meat from adult birds was darker, redder and yellower (P < 0.05) than from growing birds. Breast muscles from females (b* = 9.0 ± 0.32) were yellower (P < 0.05) than from males (b* = 7.9 ± 0.28). Shear force was higher (P < 0.05) in adults than growers. Cooking loss of 21.2 ± 0.42 % in growers was higher (P < 0.05) than 16.4 ± 0.39 % in adults. It was concluded that meat yield, carcass traits and meat quality vary with age and sex of guinea fowls.