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2. Yolk and albumen riboflavin concentrations were depressed by the deficient diets and cases of curled toes were seen in the chicks.
3. The few instances of defective down did not resemble cases seen in field outbreaks of a condition involving depressed hatchability and a defective down syndrome.
4. It is concluded from observations in this experiment and in the field outbreaks that there is a condition in breeding chickens causing depressed hatchability and defective down that is not attributable to riboflavin deficiency. 相似文献
2. Plasma VLDL plus LDL triglyceride concentrations were similar in males and females and only slightly higher in birds fed on the high‐fat diet. Concentrations at 3 weeks were similar to those at 7 weeks.
3. Body fat content was correlated more closely with plasma VLDL plus LDL triglyceride measured at 7 weeks than at 3 weeks.
4. Phenotypic correlations between body fat content and plasma VLDL plus LDL triglyceride concentrations at 7 weeks were 0.47 and 0.43 for males and females respectively fed on the high‐fat diet and 0.70 and 0.60 for males and females fed on the low‐fat diet.
5. Phenotypic correlations between body fat content and measurements with an abdominal caliper were 0.35 and 0.49 in birds fed on the high‐ and low‐fat diets respectively.
6. A possible procedure for selecting for leanness in broiler breeding programmes on the basis of measurements of plasma VLDL plus LDL triglycerides is discussed. 相似文献
2. In a larger‐scale experiment, isoenergetic and isonitrogenous diets containing 10, 20, 40 or 60 g/kg supplemental maize oil, tallow, coconut oil or fish oil were fed for 5 weeks.
3. Egg weights showed very different responses to the different fats. The responses could be described by quadratic functions that all gave optimum responses with supplemental dietary fat concentrations of about 40 g/kg. Egg weight increased the most with maize oil and was decreased with fish oil at the highest inclusion rate.
4. Measurements of egg components showed a relatively larger increase in albumen weights with maize oil than with other fats.
5. Across treatments, mean plasma oestradiol concentrations were very highly correlated (r = 0.96) with the changes in egg weights over the experimental period.
6. It is concluded that oestrogen is important in controlling egg weight and that the effect of dietary fats in influencing egg weight is mediated by an effect of the fats on oestrogen metabolism. 相似文献