| dc.description.abstract | The study was conducted to investigate the effect of feeding malted sorghum grains in place of maize grains on growth performance, blood parameters and meat quality of Ross 308 broiler chickens (R3O8BC). A pilot work (Study 1) was conducted to investigate the effects of malted sorghum grains on their chemical composition before the feeding trials commenced. Unscreened grains of Mr Buster (red sorghum) and Segaolane (white sorghum) were malted and analysed for crude protein (CP), crude fibre (CF), organic matter (OM), ash, energy, crude fat, and condensed tannin levels and their interaction effects. Condensed tannin content of malted and unmalted Mr Buster (0.08% verna 0.09%) was significantly higher than that of malted and unmalted Segaolane grains (0.05% versus 0.04%). Grain type had effects on dry matter (DM), OM, ash, CP and condensed tannin while the effects were not observed in energy and crude fat contents. Malting affected (P<0.05) OM, ash, CF and condensed tannins but did not affect DM, CP and energy. Interaction effects of grain type and malting were observed on CF and condensed tannin content of sorghum. It was concluded that although malting does not alter chemical composition of the grains, it however, reduces CF and condensed tannin levels. Based on these initial findings a feeding trial was conducted to determine growth performance of broiler chickens as reported below. In the second study (Study 2), 150 day old R308BC were randomly allotted to the following dietary starter treatment diets: Control diet - Broiler commercial diet containing 100% maize; Segaolane diet=Broiler commercial diet containing 100% malted Segaolane in place of maize; and Mr Buster diet = Broiler commercial diet containing 100% malted Mr Buster in place of maize. The results for growth performance, in weeks 3 and 4 showed rapid increase in average mean feed intake (AWFI) across all experimental diets. There was an increase in average weight gain (AWG) and mean weekly body weights of R308BC across the diets. No significant differences in AWG were observed at weeks 3 and 6 on R308BC fed malted Mr Buster and Segaolane based diets. In week 2, low feed conversion ratio (FCR) was recorded in R308BC fed Control diet followed by those fed malted Segaolane-based diet. Chickens fed malted Mr Buster diet had highest FCR in weeks 3, 4, 5 and 6. However, no significant difference was observed between the FCR from R308BC on Control or malted Segaolane-based diets at weeks 3, 4 and 5. This means that malted Segaolane and maize caused similar response suggesting that Segaolane can be a suitable replacement of maize grains. The R308BC fed malted Mr Buster diet had poor FCR at weeks 3, 4, 5 and 6 compared to other experimental diets. The protein intake (PI) of birds fed Control diet was lower than those fed other experimental diets. In week 5, birds fed on Control diet had the highest protein efficiency ratio (PER) compared to those on malted Mr Buster-based diet. Birds fed on Control diet had similar PER as those fed malted Segaolane-based diet.The results for blood parameters were within the normal range. Birds fed Control diet had significantly higher (P<0.05) white blood cells count (46.8 x lOe3/pL) compared to those fed malted sorghum-based diets. The highest (P<0.05) basophil count was observed on birds fed malted Segaolane-based diet (0.57%) and malted Mr Buster-based diet (0.56%). Glutamic oxaloacetic transaminase (GOT) and glutamic-pyruvic transaminase (GPT) enzymes were lowest (P<0.05) in birds fed malted Segaolane-based diets. No significant differences were observed in lymphocytes, neutrophils, monocytes, eosinophils, red blood cells, haemoglobin, haematocrit, and blood platelets of birds across experimental diets. Experimental diets did not have any significant effect on albumin, total protein, triglycerides, urea and bilta of Ross 308 chickens. Therefore, it can be postulated that malted sorghum grains did not have a negative impact on the blood biochemistry and physiological function of birds. This implies that malted sorghum grains can be used as substitute to maize in broiler diets without having any adverse effects on the health status of chickens. Positive growth response and good health due to manipulation of diets of food animals should also result in acceptable quality of the food product. Therefore, the third study was designed to test the quality of the meat derived from chickens fed malted sorghum-based diets.'In the carcass characteristics and meat quality study (Study 3), birds fed Control diet had the highest (P<0.05) slaughter, hot carcass and cold carcass weights. On the other hand, birds fed Control diet had the lowest (P<0.05) drumstick-thigh and vertebrae. The highest (P<0.05) vertebrae weight was recorded in birds fed malted Segaolane-based diet This implies that malted sorghum-based diets performed similar to Control in these portions regardless of lower carcass weights. The fact that malted sorghum-based diets improved drumstick-thigh weight portions, which are popular with consumers indicates that these diets can be considered as energy ingredients in formulating chicken diets. Regarding viscera macro morphometry, birds fed malted Mr Buster-based diet had the longest (P<0.05) large intestine, heavy gizzard, heart and liver implying that the diet affected the bird’s internal organs negatively. The initial pH (pHi) of the meat of birds fed malted Mr Buster were significantly higher (P<0.05) than that of the birds fed Control or malted Segaolane-based diets. Experimental diets did not significantly affect DM, ash, OM and energy content of breast muscle from R308BC. Regarding the mineral composition of the breast, birds fed malted sorghum-based diets had lower (P<0.005) phosphorus content compared to breast muscle of birds fed Control diet. Potassium and magnesium contents in the breast muscle from birds fed malted sorghum-based diets were the highest (P<0.05). The findings of this study suggest that malted Segaolane grains can be used as an energy alternative to maize in broiler diets. This caniv reduce the competition of maize grains between livestock feed processing and human consumption and possibly reduce costs of livestock feeds. | en_US |
