RESUMO
A dose of 0.3 mL of water solution containing 0.00 (control), 0.625, 1.250 or 1.875 µg of 25-hydroxy cholecalciferol (25(OH)D3) was administered to 312 fertile eggs derived from 49-w-old Cobb 500 broiler breeders on the 17th day of incubation (DE17) via allantoic cavity. After treatment, eggs were distributed and maintained until hatching in four incubators set at 37.8 ºC and 55% RH. Each incubator received eggs from all treatments, according to a block design with four treatments of 77-79 replicates each. Hatching was checked every two hours from 484h to 512h of incubation to evaluate productivity and chick qualities. Chicks were housed until 10 days of age in heated battery cages according to a block design with four treatments of 10 replicates of six chicks each for performance and mortality evaluation. Mean hatching time of the chicks treated with 25(OH)D3 during the embryonic phase occurred 4 to 5 h earlier than control group (502:31h), with no effects on hatching or neonate qualities. An inverse linear effect of 25(OH)D3 dose on chick body weight at hatching was observed, but 10-d-old broiler performance and mortality were not affected. The fast body weight recovery of the broilers obtained from the embryos supplemented with the highest 25(OH)D3 level was recorded until 10 days of rearing, equaling final mean body weights (p>0.05) among experimental groups. The results of this study indicate the potential use of 25(OH)D3 as exogenous vitamin supplementation to embryos a few days before hatching without affecting neonate qualities and 10-d-old broiler chicken performance.
RESUMO
Effects of yolk sac removal (deutectomy) upon performance of chicks from three divergent strains were tested to evaluate the importance of endogenous nutrition on the post-hatch phase. Chicks from three different strains (Hy-Line W98, Cobb 500, and JA57) were submitted to a surgery procedure after hatching. Half of them had the residual yolk removed, and the other constituted a sham-deutectomized group. After operation, chicks were designated to a 3 x 2 factorial design (3 strains x 2 presence/absence of yolk sac), in a total of six experimental groups and ten replications of two to four birds. During 14 experimental days all birds were fed ad libitum a 21% CP and 3050 kcal/kg EM mash diet. Data were analyzed by ANOVA, and Tukey's test (p 0.05). Relative yolk sac weights were similar among chicks from different breeders, averaging 11.7% to 13.5%. Comparing to sham-operated, deuctetomized chicks had lower weight gain at 7 and 14d, indicating that endogenous nutrition, via yolk sac, is very important to galliform birds whatever their strain. Hy-line deutectomized chicks gained 40% less body weight at the 7th day as compared to their sham counterparts. Analysis of the same criterion to Cobb and JA57 groups revealed a decrease of 16.1% and 10.8%, respectively, on weight gain efficiency. At the 14th rearing day, Hy-Line chicks had the lowest weight gain, followed by JA57s' and Cobbs'. The results suggested that chicks selected for fast growth are less dependent on endogenous nutrition, responding better when exogenous nutrition is associated to yolk assimilation.
RESUMO
Effects of yolk sac removal (deutectomy) upon performance of chicks from three divergent strains were tested to evaluate the importance of endogenous nutrition on the post-hatch phase. Chicks from three different strains (Hy-Line W98, Cobb 500, and JA57) were submitted to a surgery procedure after hatching. Half of them had the residual yolk removed, and the other constituted a sham-deutectomized group. After operation, chicks were designated to a 3 x 2 factorial design (3 strains x 2 presence/absence of yolk sac), in a total of six experimental groups and ten replications of two to four birds. During 14 experimental days all birds were fed ad libitum a 21% CP and 3050 kcal/kg EM mash diet. Data were analyzed by ANOVA, and Tukey's test (p 0.05). Relative yolk sac weights were similar among chicks from different breeders, averaging 11.7% to 13.5%. Comparing to sham-operated, deuctetomized chicks had lower weight gain at 7 and 14d, indicating that endogenous nutrition, via yolk sac, is very important to galliform birds whatever their strain. Hy-line deutectomized chicks gained 40% less body weight at the 7th day as compared to their sham counterparts. Analysis of the same criterion to Cobb and JA57 groups revealed a decrease of 16.1% and 10.8%, respectively, on weight gain efficiency. At the 14th rearing day, Hy-Line chicks had the lowest weight gain, followed by JA57s' and Cobbs'. The results suggested that chicks selected for fast growth are less dependent on endogenous nutrition, responding better when exogenous nutrition is associated to yolk assimilation.