The Effects of Nutrition on the Onset of Puberty

Abstract

The nutrition of mammals is a factor in their ecology which is more difficult to quantify and thus evaluate under natural conditions than the more easily measured and thus experimentally varied physical factors, such as light and temperature. Because of the large number of separate units, such as proteins, fats, carbohydrates, minerals, and vitamins, which constitute an adequate nutritional regime, the study of the effects of alterations in nutrition becomes complex, as many of the individual elements have separate effects on the reproductive processes. Not only do the separate parts of the diet have individual effects but some of the elements involved also do not act entirely independently of each other. Change in the level of intake of a single factor (i.e. calcium) may therefore result in changes in the animals’ physiological mechanisms which are really the result of alteration of a proportional relationship (i.e. the calcium: phosphorus ratio). Thus it becomes difficult to interpret and even more difficult to compare much of the published experimental work on dietary effects on reproduction because of the numerous combinations of the factors involved. As well as alteration of the quality of the diet, the amount of total food intake (the plane of nutrition) is of considerable importance in the normal physiological well-being of the animal, which is in turn reflected in its reproductive performance. Qualitative alteration of the diet often involves altering the plane of nutrition as well, so that there are really two variables affected. The plane of nutrition is also important with regard to the energy value measured in terms of calorific intake that is supplied to the animal.