Browsing by Author "Mdoda, Bayanda"

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    Effects of Supplemental Zingerone on Cobb 500 Broiler Chicken (Gallus gallus domesticus) Growth Performance, Health and Meat Quality
    (University of the Witwatersrand, Johannesburg, 2023-07) Mdoda, Bayanda; Chivandi, Eliton; Lembede, Busisani Wiseman
    Commercial broiler and pullet chicken producers supplement chicken diets with sub-therapeutic doses of antibiotics such as zinc bacitracin that act as growth promoters to enhance production performance, meat and egg quality. Use of these antibiotics as growth promoters, in addition to causing environmental pollution, causes the public health challenge of antibiotic resistance which compromises poultry and consumer, hence the need to search for environmentally friendly and health-friendly alternatives to antibiotics. Phytochemicals, zingerone included, display biological activities similar to those of antibiotics. This study evaluated zingerone`s potential to replace bacitracin (ZnBcn) as a growth-promoting diet supplement in broiler feed specifically determining its effects on growth performance, meat quality and bird health. One hundred and twenty unsexed 1-day-old Cobb 500 broiler chicks (10 chicks per replicate with 3 replicates per diet) were randomly assigned to four dietary treatments where zingerone replaced ZnBcn at: diet 1 – 0 mg kg-1 (control: 500 mg akg-1 of zinc bacitracin); diet 2 – 40 mg kg-1; diet 3 – 80 mg kg-1 and diet 4 – 120 mg kg-1 in the starter, grower and finisher diets. The broiler chicks were fed ad libitum for 6 weeks: starter (week 1-2), grower (week 3-4), and finisher (week 5-6). Initial and weekly body mass, daily feed intake (FI), and terminal body mass (TBM) were measured. Body mass gain (BMG), average daily gain (ADG), and feed conversion ratio (FCR) were computed. On day 42, the chickens were humanely slaughtered, blood collected and carcasses dressed. The gastrointestinal tract (GIT) and accessory GIT viscera organs were weighed and small and large intestine lengths were measured. Empty carcass masses were measured and the dressing percentages were computed. Viscera macromorphometry, long bone indices and carcass traits, the meat’s physical quality [initial and ultimate pH (pHi and pHu), colour, thawing loss (TL), cooking loss (CL), and tenderness] traits, proximate and amino acid content and fatty acid profiles were measured. Plasma malonaldehyde (MDA) concentration, glutathione peroxidase (GSH-Px), glutathione-S-transferase (GST), superoxide dismutase (SOD) and catalase (CAT) activities, surrogate markers of liver and kidney function, liver fat content and histology were determined. Across growth phases and overall, dietary zingerone had similar effects (p > 0.05) as ZnBcn on the chicken’s TBM, BMG, ADG, FI, and FCR. It also had similar effects (p > 0.05) as ZnBcn on the chicken’s empty carcass mass, dressing percentage, long bone indices and viscera macromorphometry. Dietary zingerone had similar (p > 0.05) effects as ZnBcn on the broiler chicken meat’s pHi, pHu, CL, TL and tenderness. However, at 40 mg kg-1 of feed (diet 2) it increased the meat’s redness (a*) compared to that of counterparts fed the ZnBcn-fortified control diet. Furthermore, supplemental zingerone had a similar effect to that of ZnBcn on the meat’s crude protein content but it significantly increased the meat’s ash and fat contents (p < 0.01; p < 0.0001). Meat from chickens fed diet 2 (40 mg kg-1 of feed zingerone) had the highest concentration of essential amino acids (p < 0.05) and that from chickens fed diets 3 (80 mg kg-1 of feed zingerone) had the lowest (p > 0.001) total amino acid content. Dietary zingerone had a similar (p > 0.05) effect as ZnBcn on the chicken meat’s total saturated fatty acids, but breast meat from chickens fed diets 3 (80 mg kg-1 of feed zingerone) had significantly increased (p < 0.0001) total monounsaturated fatty acid and oleic acid content. Meat from chicken-fed diet 4 (120 mg kg-1 of feed zingerone) had the highest total polyunsaturated fatty acid and linoleic acid content and a higher PUFA:SFA ratio compared to that from counterparts fed diets 1, 2 and 3. Supplemental zingerone had similar effects (p > 0.05) as ZnBcn on the chickens’ liver masses and fat contents, plasma MDA concentration, GSH-Px, GST, SOD, CAT, alkaline phosphatase, alanine transaminase activities, albumin, total bilirubin, creatinine and urea concentrations. Chickens’ hepatic inflammation and steatosis scores were similar across diets (p > 0.05). At 120 mg kg-1 of feed zingerone, though similar to the control, supplemental zingerone decreased the chickens’ plasma globulin and total protein concentration (p < 0.01; p < 0.05) compared to counterparts supplemented at low and medium dose of zingerone. Zingerone can be used as a growth promoter in place of zinc bacitracin in broiler chicken diets without compromising growth, feed use efficiency, carcass yield, long bone and GIT viscera growth and development, the meat’s pH, CL, TL and tenderness. Furthermore, it can be used without eliciting oxidative stress in the birds and with no risk to kidneys, liver and general health of the birds. Importantly, zingerone, as a dietary supplement, can be used to enhance broiler chicken meat’s redness, positively impacting its acceptability and meat’s total monounsaturated, oleic acid, total polyunsaturated and linoleic acid fatty acid profile; thus improving its nutritional value.
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    The potential of Mimusops zeyheri seed meal as a dietary energy source in broiler quail diets
    (2019) Mdoda, Bayanda
    The shortage of dietary energy sources for poultry feeds contributes to increased feed costs hence the need to search and develop alternative sources. Mimusops zeyheri seed meal (MZSM) has high energy content. This study evaluated the potential of MZSM to replace maize meal (MM) as an energy source in broiler quail finisher diets. The effects of dietary MZSM on the growth performance, feed utilisation efficiency, viscera morphometry, general health and meat quality of broiler quail were determined. Thirty-two 5-week old male broiler quails were randomly allocated to 4 diets wherein MZSM replaced MM on gross energy basis at 0%, 12.5%, 25% and 37.5% (diet 1 to 4) and fed for 4 weeks. Body mass and feed intake (FI) was measured. Body mass gain (BMG), average daily gain (ADG) and feed conversion ratio (FCR) were computed. On slaughter, the carcasses were eviscerated and viscera macro-morphometry determined. pH and colour of the breast muscle were measured. Tissues were collected for physico-biochemical and histological assays. At 37.5% inclusion MZSM reduced (p<0.05) FI. Dietary MZSM did not affect (p>0.05) BMG, ADG and FCR but increased (p<0.0001) the mass of proventriculi, ventriculi and small intestine mass and the small intestine length of the quail. Visceral fat decreased (p<0.0001) with an increase in dietary MZSM. At 25% and 37.5% inclusion, MZSM increased (p <0.05) villus height and width, crypt depth and villus height:crypt depth ratio. MZSM had no effect (p>0.05) on fasting blood glucose concentration but at 25% inclusion level it increased (p<0.05) fasting blood triglyceride concentration. Dietary MZSM decreased (p<0.05) hepatic lipid content. At 25% inclusion MZSM increased (p<0.05) plasma urea concentration. Dietary MZSM did not affect (p>0.05) plasma uric acid concentration. At 25% inclusion, MZSM increased (p<0.05) plasma ALT activity and at 12.5% and 37.5% it increased (p<0.05) plasma ALP activity while at 25% and 37.5% inclusion it significantly increased (p<0.05) TBARs concentration. Dietary MZSM (25% and 37.5% inclusion) increased (p<0.05) plasma total bilirubin concentration. It had no effect on pHi and colour of the quail breast muscle (meat). MZSM had no effect (p>0.05) on pHu but at 37.5% inclusion it decreased (p<0.05) redness of the meat 24-hours post-slaughter. Dietary MZSM increased (p<0.05) water holding capacity of the meat. At 12.5% inclusion it reduced (p<0.05) cooking loss. MZSM (25% and 37.5% inclusion) decreased (p<0.05) shear force required to cut through fillets. Dietary MZSM had no effect (p>0.05) on the meat’s moisture, dry matter and ash content. The meat’s crude protein content increased (p<0.05) with an increase in the meal and its fat decreased (p<0.05) with an increase in the meal. MZSM had no effect (p>0.05) on the meat’s total saturated, monounsaturated and polyunsaturated fatty acid content. At 25% and 37.5% inclusion, MZSM decreased (p<0.05) the meat’s trans and Cis fatty acid content but increased (p<0.05) the omega-3, -6 and -9 content. Mimusops zeyheri seed meal can partially replace MM in quail finisher diets without compromising growth performance and feed utilisation efficiency, as well as viscera morphometry and meat quality. Caution has to be exercised in the use of M. zeyheri as a dietary energy source as it may compromise liver function and increase lipid peroxidation in the birds.