Nurtitional evaluation of meat meals for poultry. III. Association of chick growth with the bone, calcium, and protein contributed by meat meals to diets, and the effect of mineral and vitamin plus antibiotic supplementation

Abstract

Experiments were conducted to study the effect on chick growth of equalizing the bone, bone ash, or calcium contents of diets based on wheat plus skim milk and containing high or low quality meat meals with and without soybean meal, and of supplementing these diets with minerals and with vitamins plus antibiotic. Bone or ash content was the major cause of variation in the growth of chicks on diets in which meat meal provided about 35% and soybean meal about 22% of the total dietary protein, but not on diets in which meat meals provided about 57% of the protein. The first type of diet gave significantly faster growth than the second type, but this was not due to the lower bone or calcium content of the first type. The results are interpreted as indicating that when meat meals provided a major proportion of the protein, protein quality rather than the bone or ash content of the diets was the major cause of variation in growth. As supplementation with bone ash, or bone with the same ash content, or with calcium carbonate with the same calcium content, depressed growth equally, it was concluded that the main cause of depressed growth on diets containing high levels of added bone was the high calcium content of the diets. Though supplementation of some low quality meat meal diets with minerals, with or without vitamins plus antibiotic, slightly increased growth rates, the variation in growth-promoting ability between diets containing high and low quality meat meals was not appreciably reduced. The experiments confirmed previous indications that the growth-promoting ability of a meat meal included in chicken diets is mainly the resultant of any growth depression due to excess calcium and growth promotion due to the contribution of essential amino acids.