Efeito da restrição de vitaminas e minerais na alimentação de frangos de corte sobre o valor nutricional da carne.

Abstract

The purpose of this study was to assess the effect of the withdrawal of vitamin and mineral supplements from the diet of chicken in their final period of growing on carcass and abdominal yield and on the following meat components: moisture, fat, protein, ash, macro minerals (Ca, P, Mg, Na and K), microminerals (Zn, Fe, Mn and Cu) and vitamins (riboflavin, niacin and pyridoxine). 112 birds of a commercial brand were fed experimental diets, from the 21st to the 45th day of age, consisting of 4 different treatments: T1: diet containing mineral and vitamin supplements; T2: diet without supplements from the 21st to the 42nd day of age; T3: diet without supplements from the 28th to the 42nd day of age; T4: diet without supplements from the 35th to the 42nd day of age. Eight birds from each treatment (halt from each sex) were slaughtered at the end of the experimental period and the carcass yield and abdominal fat measured. Dark and light meat from each carcass was then collected and analyzed for proximal composition, minerals and vitamins. Average carcass yield was 67.54% and was not significantly (P > 0.05) affected by the treatments. Average abdominal fat was 3.49%. Supplements withdrawal (T2, T3 and T4), however, produced a significantly (P < 0.05) increase in the fat pad. Feed treatments as well as bird sex and type of meat did not affect the content of moisture (73.0%) and ashes (1.1%) in the meat. Protein (19.0%) and lipid (4.2%) contents were affected by feed treatment and type of meat. Macromineral levels in chicken meat were 5.2 mg/100g for Ca; 208 mg/100g for P; 24.6 mg/100g for Mg, 56.5 mg/100g for Na and 303.9 mg/100g for K and did not varied accordingly with feed treatments. Dark meat, however, showed higher levels of Ca and Na and lower levels of P, Mg and K than light meat. Average micromineral content in the meat was 1.6 mg/100g for Zn; 0.6 mg/100g for Fe; 1.5 mg/100g for Mn and less than 0.2 mg/100g for Cu, with no significant (P > 0.05) effect of treatments. Dark meat was higher in Fe and Zn contents than light meat. Bird sex showed no influence on meat macro or micromineral contents. Meat riboflavin and niacin contents were 0.12 and 16.28 mg/100g, respectively. Riboflavin content in T4 was lower than in the other treatments and higher in light meat than in dark meat. The leveI of pyridoxine in the chicken meat was below the analytical detection limit for that vitamin.