Effect of pre-slaughter feed withdrawal and dietary supplementation of vitamin E and ascorbic acid on microbiological and keeping quality of broiler chicken meat

Thirty, six week old broiler chickens were randomly divided into six groups (T₁-T₆) of five each. All the birds in T₁ to T₄ groups were fed on a standard broiler finisher diet for 10 days. The broilers in groups T₅ and T₆ were also fed on same diet but supplemented with vitamin E (as α-tocopherol acetate) and vitamin C @ 300 and 150 mg/kg of diet, respectively. The birds were sacrificed after 10 days of feeding. Pre-slaughter feed withdrawal was done on 10^th day of feeding as per the following schedule - 0 h (T₁), 8 h (T₂, T₅, T₆), 16 h (T₃) and 24 h (T₄) before processing. Total viable count (TVC) of intestinal contents decreased significantly (P<0.01) and progressively as the feed withdrawal was increased from 0 to 24 h in vitamin E and C unsupplemented groups (T₁-T₄). The number of coliforms differed significantly (P<0.01) in both meat samples and intestinal contents. Staphylococcus aureus counts in intestinal contents also differed significantly (P<0.05) due to feed withdrawal being highest in T₁ (unsupplemented, 0 h feed withdrawal), however, in meat, Staphylococcus aureus counts did not differ significantly. The count of yeast and mould also did not differ due to treatments. The thiobarbituric acid (TBA) value of breast and thigh muscles was significantly lower in meat samples of broilers received vitamin E (0.25 mg malondehyde/kg) followed by control (0.53 mg malondehyde/kg) and ascorbic acid (0.80 mg malondehyde/kg). It was concluded that 300 mg/kg vitamin E supplementation in broiler diet during last 10 days before marketing improved the keeping quality of meat. Moreover, based on microbiological quality it was inferred that eight hours pre-slaughter feed withdrawal time was sufficient.