No abstract

This study was conducted to evaluate the effects of time of initiation of feeding after hatching and influence of diet composition on growth performance, carcass characteristics, digestive tract development and immune responses of broilers. A total of straight-run 420 Ross 308 broiler chicks were randomly allotted to six treatments with five replicates of 14 chicks each. The dietary treatments consisted of feeding a maize-soybean meal diet immediately posthatching until 14 days of age (Control), fasting for 24 or 48 h posthatching, feeding maize for 24–48 h posthatching, and feeding a maize gluten-dextrose pre-starter diet for 5 days posthatching. The study lasted from 0 to 42 days of age. For the entire 42-day period, chicks fasted or fed maize for 48 h posthatching or those fed the maize gluten-dextrose diet for 5 days posthatching had lower (P < 0.05) feed intake and lower (P < 0.05) weight gain compared with the Control. However, birds fasted or those fed maize for 24 or 48 h posthatching had similar (P > 0.05) feed intake and weight gain as the Control. The duodenal villus height and villus height:crypt depth ratio were lower (P < 0.05) and the duodenal crypt depth was higher (P < 0.05) in birds fasted for 48 h posthatching compared with the Control. Conversely, birds fasted for 48 h posthatching had higher (P < 0.05) jejunal villus height and villus height:crypt depth ratio and lower (P < 0.05) jejunal crypt depth compared with the Control. The antibody titres against Newcastle disease was lower (P < 0.05) for the groups other than the Control, whereas the antibody titres against Avian Influenza virus was lower (P < 0.05) in birds fasted for 48 h posthatching and in those fed maize for 48 h posthatching compared with the Control. Also, birds fed maize for 24 h posthatching had lower (P < 0.05) antibody titres against sheep red blood cells compared with the other treatments. These results indicated that feeding a maize-soybean meal starter diet immediately after hatch has a beneficial effect on growth performance and immune response of broilers and improves morphological development of the intestine.

In total, 378 Shaver White layers were allocated into 7 treatments with 6 replicates, from 30 to 42 wk of age, to assess the effects dietary organic (ethylenediamine dihydroiodide [EDDI]) versus inorganic (calcium iodate [CIOD]) iodine in laying hens. A basal diet served as control while the remaining six diets were supplemented with either CIOD (CIOD 2 , CIOD 4 , and CIOD 8) or EDDI (EDDI 2 , EDDI 4 , and EDDI 8) to provide 2.0, 4.0, and 8.0 mg of added iodine/kg of diet, respectively. Performance and egg quality were not affected by adding 2.0 or 4.0 mg/kg of iodine to the diets. However, a progressive decline in egg performance and feed intake occurred with EDDI 8 and CIOD 8 diets. The EDDI 8 diet also increased abnormal eggs in parallel with decreasing the eggshell strength and Haugh unit and disturbing the serum and egg yolk lipids. This trend was connected with increase in triiodothyronine (T3) and thyroxine (T4), which led to oxidative stress in serum and egg contents. The iodine levels of eggshell and egg contents were increased by dietary iodine in a dose and time-dependent manner, while the effect of EDDI was higher than CIOD at all levels. To summary, supplementation of diets with 2 or 4 mg/kg of iodine as CIOD and specifically EDDI increased the iodine content of eggs without adverse effect on hen performance and egg quality traits. However, considering the time-dependent nature of this increase, a 12-wk period of supplementation might be not sufficient to achieve a specified level of iodine in the eggs. HIGHLIGHTS Diet supplementation with 2, 4, and 8 mg/kg of iodine as CIOD and EDDI increased iodine content of eggs. The highest level of iodine, especially as EDDI, diminished egg performance and egg quality connected with an increase in serum T3 and T4, which led to oxidative stress. A 12-wk period of supplementation appears to be not sufficient to achieve a specified level of iodine in the egg.