Response in carcass yield, organ weights and the gut morphology to Vachellia tortilis inclusion in broilers.
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Date
2018
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Abstract
The broad objective of this study was to determine the response to incremental levels of Vachellia tortilis leaf meal on carcass yield, organ weights and gut morphology of broilers. Five-hundred unsexed cobb 500-day-old broiler chicks were fed on conventional starter mash for 14 days. The chicks were randomly allocated to six dietary treatments. These treatments contained 0, 30, 60, 90, 120 and 150 g/kg DM inclusion levels of Vachellia tortilis leaf meal. Each diet was offered ad libitum to 10 birds per pen for 17 days before they were slaughtered. Six pens received the same experimental diet.
There was a linear decrease in both slaughter weight (SW) and dressed carcass weight (DCW) (P<0.05) as V. tortilis leaf meal increased. The SW and DCW decreased by 0.77 and 0.94 g for each g/kg increase in V. tortilis inclusion. The scaled weights of thighs (TW) and drumstick (DW) showed no relationship with levels of leaf meal. The weight of gizzard, intestines and stomach, however, increased linearly (P<0.05) as levels of leaf meal increased. Relative gizzard, intestine and stomach weights increased by 0.0028, 0.0059 and 0.0008 g for each g/kg increase in Vachellia tortilis (P<0.05) inclusion. There was a linear increase in relative heart weight and kidney weight with increasing levels of V. tortilis leaf meal in the diet. The relative heart and kidney weight increased by 0.0009, 0.0006 g as V. tortilis increased (P<0.05). The relative weight of the liver was, however, not related to V. tortilis inclusion. It was concluded carcass yield and organ weights responded differently to increase in Vachellia tortilis inclusion.
There was a linear increase in villus height (VH), apparent villus surface area (AVSA) and villus height: depth ratio (P<0.05) as V. tortilis leaf meal increased. The VH, AVSA and CD/VH ratio increased by 0.12, 1.08, and 1.96 g for each g/kg increase in V. tortilis inclusion. The crypt depth (CD) showed no relationship (P>0.05) with levels of leaf meal. The thickness of submucosa, muscularis and epithelial, however, increased linearly (P<0.05) as levels of leaf meal increased. Submucosa, muscularis and epithelial thickness increased by 8.73, 1.15, and 0.38 g for each g/kg increased in Vachellia tortilis inclusion. Elevated inclusion levels of V. tortilis leaf meal was associated with increased villus height, apparent villus surface area, villus height and depth ratio, thickness of submucosa, muscularis and epithelial. In conclusion, increasing V. tortilis in the diet increase gut morphology parameters of broiers thus improve the digestibility and absorption with a negative effect on growth performance, carcass yield and internal organ weights.
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Masters Degree. University of KwaZulu-Natal, Pietermaritzburg.