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).