Influence of age, dietary cholic acid, and calcium levels on performance, utilization of free fatty acids, and bone mineralization in broilers

The effects of age on the utilization of dietary palmitic or a 50/50 mixture of palmitic and oleic acid at the 8% inclusion level in the absence or presence of .2% cholic acid and also in the presence of low (.8%) or high (1.2%) calcium were investigated using broiler chicks from 1 to 56 days of age. Significant interactions (P less than .01) were observed between the type of fatty acid supplemented and the presence or absence of cholic acid on weight gain and feed efficiency. Supplementing diets with a mixture of equal weights of palmitic and oleic acid, reduced feed intake relative to control diets and diets supplemented with palmitic acid alone. There was an interaction between the age of the bird and the type of fatty acid supplemented on fat retention and metabolizable energy (ME) of diets (P less than .01). There was also a significant interaction between the type of fatty acid supplemented and the addition of cholic acid on fat retention and ME of diets. While cholic acid reduced soap formation during the process of digestion (P less than .05), increasing dietary calcium level increased the proportion of the digesta fat that was present as soap (P less than .01). The proportion of digesta and excreta fat, present as soap, depended on the type of fatty acid supplemented. The addition of free fatty acids to broiler diets resulted in a decrease in bone ash and bone calcium content relative to those birds fed the control diet. It is concluded that the ability of broilers to utilize dietary free fatty acids depends on the age at which they are fed, although in all cases supplemental cholic acid enhances fatty acid utilization.