Abstract
Three experiments were carried out at 3 local experiment stations with one of 3 broiler-type cross-breds for each station and one experiment at Hyogo Animal Breeding Station with cross-breds of White Cornish male x White Plymouth Rock female.
In 3 local stations, 5 groups of 4-week-old chicks were fed one of 5 experimental broiler finisher diets containing various levels of riboflavin and nicotinic acid for 6 weeks. Growth rate, feed conversion (feed/gain) and ratios of ready-to-cook and chicken meat of chicks on the finisher containing the lowest levels of riboflavin and nicotinic acid, i.e. 2.6 and 42mg/kg, respectively, were almost identical to those of chicks fed the other 4 experimental diets.
In Hyogo Animal Breeding Station, duplicated lots of 40 4-week-old chicks each were fed 3 experimental broiler finisher for 6 weeks. One finisher containined no additional riboflavin and nicotinic acid, the second had the same levels of the vitamins to the diet of the lowest levels of the vitamins in the previous experiments. The last finisher was the control diet containing excess amount of the vitamins. Performance of the chicks on the second diet was almost identical to that on the diet of excess vitamins, confirming the results cbtained in the previous experiments at 3 stations. Growth rate and ratios of ready-to-cook and chicken meat of chicks on the finisher without the additional vitamins were almost equal to those of the other chicks, but feed conversion was slightly but significantly inferior to those of the other 2 groups.
With these experimental results, it was suggested that the minimum requirement of riboflavin and nicotinic acid for broiler-type chicks after 4-week-old will be not more than 2.6 and 42mg/kg diet, respectively.
