Performance and bone characteristics of broilers fed diets supplemented with vitamin A at different concentrations.

This work evaluated the influence of vitamin A on performance, organ weight, and bone and skin characteristics in broilers (Cobb 500) at 21 and 42 days of age. A total of 1920 chickens were distributed in a randomised design, considering six vitamin A supplementation levels (0, 6000, 16,000, 26,000, 36,000, and 46,000 IU kg-1 ), with 16 replicates and 20 chickens per experimental unit, established due to rising the range of vitamin levels observed in the literature to evaluate the effect of vitamin A on broilers. At 22 days, half of the replicates from each treatment continued receiving the initial diet, and the other eight repetitions received diets without vitamin A (0 IU kg-1 ) until 42 days. The level of vitamin A influenced feed intake (FI) and body weight gain (BWG) until 21 days for all treatments. Broilers at 21 days of age had a more significant BWG at a vitamin A supplementation level of 28,209 IU kg-1 . At 42 days, vitamin A influenced the BWG and FI of broilers at treatments that were not supplemented after 21 days. Treatments supplemented up to 42 days showed quadratic responses to vitamin A for BWG, FI, and feed conversion. The vitamin A levels influenced the relative weights of the small intestine, pancreas, gizzard, abdominal fat, Seedor index, and breaking strength at 42 days, where the adequate supplementation of vitamin A improved these characteristics in broilers. Vitamin A supplementation from 22 to 42 days old did not affect broiler performance. An increased BWG was obtained when vitamin A supplementation occurred until 42 days, with supplementation of 29,375 IU kg-1 and a lower response of feed conversion with the addition of 27,775 IU kg-1 .

Zeolite and corn with different compositions in broiler chickens feeding.

The objective of this work was to evaluate the behavior of zeolite against different types of corn in broiler chickens' diets. 1,200 male broiler chickens were assigned to 6 diets in a completely randomized design and a 2 × 3 factorial arrangement, consisting of 2 types of corn (higher or lower mycotoxin contamination) and the inclusion of zeolite (0; 5,000 and 10,000 g ton-1). In the period from d 1 to 21, there was an interaction (P = 0.0040) between types of corn and the inclusion of zeolite for feed conversion ratio (FCR). In the phase from 1 to 42 d, there was an interaction (P = 0.0322) on the serum levels of creatinine (CREA) and digestible gross energy (dGE); corn with lower mycotoxin level contamination (LMLC), caused a reduction in body weight gain (BWG) (P = 0.0046) and increase in the relative weight of abdominal fat (P = 0.0256). Inclusion rates of zeolite promoted an increase in the digestible CP (P = 0.0477) and digestible ash (P < 0.0001), as well as an increase (P < 0.0001) in hot carcass yield (P = 0.0433). The results indicate that the inclusion of zeolite, in the amounts used, did not alter the performance, serum levels, intestinal development and litter quality of the birds at 42 d of age. However, it was responsible for the improvement in the percentage of digestible nutrients (CP, GE, and MM).

Performance, metabolism, and meat quality of broilers fed dry brewery residue.

A study was conducted to assess the chemical composition and apparent metabolizable energy (AME), nitrogen-corrected AME (AMEn), and their respective coefficients of dry brewery residue (DBR) for broilers. A second study was conducted to evaluate the increasing inclusions of DBR in broiler diets and its effects on growth performance, carcass traits, blood metabolites, and meat quality. In the first trial (metabolism assay), a total of 250 male broilers were assigned to 5 diets (0, 100, 200, 300, and 400 g DBR/kg) composed by 5 replications with 10 animals per cage in a completely randomized design in the period from days 11 to 21. There was an increasing linear effect for AME, AMEn, metabolizable coefficient of gross energy (MCGE), and MCGE corrected for N (MCGEn). In the second experiment, a total of 840 one-day-old male broiler chickens were assigned to 6 treatments (0, 20, 40, 60, 80, and 100 g DBR/kg) with 7 replications and 20 animals per pen, from days 0 to 42. Growth performance was determined at days 21 and 42. There was an increasing linear effect for weight gain in the period from days 0 to 21 and for feed intake from days 0 to 42. A linear decreasing effect was observed at day 21 for cholesterol and quadratic effect for uric acid (UA), aspartate aminotransferase, and albumin. At day 42, there was a quadratic effect for UA and creatinine. At day 21, an increasing linear effect was observed for protein deposition rate. In conclusion, the inclusion of DBR up to 100 g/kg improved WG in the starter phase and did not negatively affect the productive parameters of broilers from days 0 to 42.

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.