ABSTRACT This study evaluated the behavior of broiler chickens subjected to thermal stress during different periods of the day and age of birds. A total of 180 one-day-old male broiler chicks were allocated to three chambers. Each chamber contained five boxes, with 12 chicks/box. Birds were assigned to a completely randomized design. The birds were filmed, and the images recorded every minute during the two periods: morning (from 08:00 to 09:00 h) and afternoon (from 17:00 to 18:00 h), at 7, 14, and 35 d of age. The frequency of the behavioral category (water intake, feed intake, resting, exploration, and comfort) was determined. Data were subjected to variance analysis for mixed models with rearing temperatures (cold, usual, and hot) and age of birds (7, 14, and 35 d) as subdivided plot, and periods of the day (morning and afternoon) as sub-subdivided plot. Birds at cold and usual temperatures showed higher feed intake than those at hot temperature in the morning. Birds exposed to cold and usual temperatures explored the environment less frequently at 35 d when compared with 14 d. However, chickens at hot temperature showed decreased exploration according to the increase of age. Birds spent more time feeding during the morning, regardless of age and rearing temperature. Also, during this period of the day, chickens spent most of the time exploring the environment. The frequency of feed intake and exploration decreases with the increase of age. The similarity of behavior between chickens reared at cold and usual temperatures may be due to a change in the thermal comfort zone of the birds. It suggests that the real thermal comfort temperature is between the two temperature ranges studied (cold and usual).

ABSTRACT The purpose of this study was to determine if in ovo feeding with 25(OH)D3 could influence the incubation parameters of bone mineral composition, mineral density, and bone breaking strength in post-hatch broilers. Fertile eggs from Cobb® broiler breeders were either non-injected or injected with 0, 1.2, 2.4, or 3.6 μg of 25(OH)D3/100 μL olive oil at eight days of incubation. The data were subjected to variance analysis using the General Linear Model procedure (GLM) of SAS®. There was a contrast-1 effect (non-injected eggs vs. injected eggs) for tibial bone mineral density and egg mass loss, with higher bone mineral density in non-injected eggs (0.836 mmAl) compared with injected eggs (0.790 mmAl) and lower egg mass loss in non-injected eggs (11.25%) compared with injected eggs (12.10%). Tibial and femur bone mineral density responded quadratically, and injections of 0.47 and 0.68 μg of 25(OH)D3 increased tibia and femur bone mineral density, respectively. Egg mass loss responded quadratically, and 25(OH)D3 injections of 2.21 μg reduced egg mass loss (11.60%). In ovo feeding of 25(OH)D3 can compromise bone mineral density of post-hatch chicken.

ABSTRACT Different levels of glycosaminoglycans (chondroitin sulfate and glucosamine sulfate) and vitamin C were injected in ovo to determine whether additive use influences the incubation parameters and bone characteristics of posthatch chicks. Hatchability was not affected by addition of glycosaminoglycans and vitamin C in ovo. However, chicks that received 4 μg additive showed 2.86% reduction in total mortality when compared with chicks from non-injected eggs. Moreover, tibia area and femur bone mineral density increased in chicks from eggs injected with 2.16 and 6.00 μg of additive, respectively. In ovo feeding with glycosaminoglycans and vitamin C can benefit bone development in embryos and reduce total mortality during the incubation period.