Total 160 and 20 offspring of White Leghorn hens fed a breeder diet containing 15% of yeast grown on n-paraffin and a control breeder diet, respectively, were fed experimental starter diets containing graded levels of vitamin B₁₂ to study the effect of the breeder diet and of supplemental vitamin B₁₂ in the starter diet on the growth of the chicks.
The eggs for the offspring were collected at the second and the fourth week after feeding the breeder diets and incubated, respectively. Two lots of either 5 males or 5 females each on the yeast breeder diet were fed one of 8 starter diets and 2 lots of either 5 males on 5 females each on the control breeder diet ware fed the basal starter diet for 3 weeks in each of the two hatches. To the basal starter diet, containing 37.2% of the yeast, 0, 1.16, 2.31, 3.47, 4.62, 5.78, 6.94 and 8.09μg of vitamin B₁₂ per kg of diet was supplemented. Vitamin B₁₂ content in the supplement and in the basal starter diet was determined microbiologically.
Following Equation 2 was found fit to describe the linear relationship between supplemental vitamin B₁₂ and growth of the offspring on the yeast breeder diet,
y=44.60+0.518x (2)
where, x is supplemented vitamin B₁₂ (μg/kg diet) and y is body weight gain for 3 weeks per 100g of diet (g/100g).
Substituting the body weight gain of the offspring on the control breeder diet per 100g of the basal starter diet, i.e., 47.9g/loog, to y, the differnce between amounts of vitamin B₁₂ carried over from the hens on either the control or yeast breeder diet was estimated to be 6.37μg/kg of starter diet, which corresponded 1.7μg of vitamin B₁₂ per chick.
Requirement of vitamin B₁₂ for the chicks on the yeast breeder diet and fed the yeast starter diet was estimated to be 11.4μg/kg of starter diet with 95% confidence interval of 18.6-9.4μg/kg.