Dry residue of cassava on slow-growing broiler diets, with or without the addition of carbohydrases.

Dry residue of cassava was studied on the digestibility, performance, intestinal measurements, with or without inclusion of carbohydrases, of slow-growing broilers. 160 Label Rouge broiler chickens, 21-d-old, were distributed in a randomized, 2x5 factorial arrangement (male and female x 0, 10, 20, 30 and 40% residue) (metabolism trial). 1,100 male chicks were distributed in a 2x5 factorial arrangement (with/without carbohydrases x 0; 2.5; 5.0; 7.5; and 10.0% residue), with five replicates (performance trial). Increasing residue levels led to increases in energetic values. Feed intake from 1-21-d-old and 1-63-d-old decreased linearly. At 42 d-old, feed intake and weight gain levels exhibited a quadratic response, which predicted a highest value at 3.32% and 4.77%, respectively, for diets without carbohydrases. For 21- and 42-d-old chickens, the inclusion of carbohydrases reduced the weight and length of the small intestine. The energetic values of the diets were positively influenced by the residue and had similar digestibility values for both sexes. Inclusion of up to 10% of residue in slow-growing broiler diets does not impaired performance and intestinal morphology. The addition of carbohydrases reduced the viscosity of the digesta but it was not enough to improve the performance of the birds.

Effects of vitamin A on carcass and meat quality of broilers.

This study evaluated the level and length of time of vitamin A supplementation and its effects on carcass and cuts yield, meat quality, and myopathies in 42-day-old broilers. A total of 1,920 birds were divided into 6 groups, and each group received a different level of vitamin A: 0; 6,000; 16,000; 26,000; 36,000 and 46,000 IU/ kg. From d 1 to 21, the treatments were distributed among 16 replicates with 20 birds. From the 22nd d on, 8 repetitions remained with the initial treatment and the others received diets with no vitamin A supplementation. Twelve birds were slaughtered per treatment to evaluate carcass and cuts yield, shear force, cooking loss, water holding capacity, and the presence of substances reactive to thiobarbituric acid. The remaining birds were slaughtered and evaluated in loco for Wooden Breast (WB) and White Striping (WS). Wings weight was affected by vitamin A levels. The duration of the vitamin A supplementation process had effects on the weight of breast, legs with a dorsal portion, and meat color in the yellow intensity (b*). Incidence of WB had higher scores in birds supplemented until 42 d of age. WS showed a quadratic response and a lower response with supplementation of 29,700 IU/ kg. Even for WS, a higher occurrence of the normal score was found in birds supplemented until 21 d of age. Minimal quadratic responses were obtained for normal, moderate, and severe scores, in supplementations of 29,301; 29,959, and 29,827 IU/ kg, respectively. WB had lower occurrence rates in birds supplemented until 21 d of age. Consequently, the severe score was more frequent when supplementation was provided until 42 d of age. The level of vitamin A and the length of time during which this supplementation was provided had influence on cuts yield, meat color and the incidence of WB and WS of the 42-day-old birds.

Carcass characteristics and meat quality of slow-growing broilers fed diets containing dry residue of cassava, with or without the addition of carbohydrases.

This study evaluated the carcass and portion yield and meat quality of slow-growing broilers fed diets with increasing levels of dry residue of cassava (DRC), with or without the addition of carbohydrases. A total of 1100 Label Rouge male broilers were distributed in a completely randomized 2 × 5 factorial design (with or without the addition of carbohydrases and five levels of DRC [0, 2.5, 5.0, 7.5, and 10.0%]), with five replicates and 22 birds per experimental unit. No interaction (P > 0.05) was observed between enzyme addition and DRC levels for the carcass yield, portion yield (back, legs, wings, breast), or abdominal fat variables. There was an interaction (P < 0.05) between the addition of enzyme and DRC on breast pH 15 min post-mortem and the a* intensity of the breast in a colorimetry test. There was a quadratic effect on b* intensity independent of adding enzymes, with the lowest intensity predicted at 8.89% DRC. Regarding feet color, increasing DRC supplementation (independent of enzyme supplementation) led to an increase and decrease in L* and b* intensity, respectively (P < 0.05). Moreover, there was a quadratic effect on a* intensity, with a lower level of intensity predicted at 6.93% DRC (P < 0.05), regardless of the inclusion of enzymes. The inclusion of up to 10% dry residue of cassava in slow-growing broiler diets does not affect carcass and portion yield or the qualitative characteristics of the meat but does reduce the color of the breast meat and feet.