Studies were conducted in which levels of essential amino acids in excess of the minimum requirements were minimized in broiler diets composed of commercially available feed stuffs and synthetic amino acid supplements. Growth rate and efficiency of feed utilization of chicks fed such diets were equal to that attained by chicks fed diets formulated by conventional means when grown under conditions where heat stress was not a factor and significantly improved when fed under conditions of heat stress. Improvements were obtained in efficiency of protein and calorie utilization using this technique of formulation.

Hair follicle activity and fibre growth were studied using histological sections from the skin of five adult feral does sampled every four weeks for 18 months. The main period of guard hair growth in primary follicles was from November to April. Secondary follicles grew fine, long, nonmedullated fibres (cashmere) from December to June. Shedding of these fibres from secondary follicles had commenced by July and cashmere was absent from the fleece by November. From September to December a subsidiary hair cycle occurred in many secondary follicles which produced minute (vellus) fibres, less than 2.4 mm in length. Some secondary follicles probably shed their cashmere fibres and remain quiescent over spring. Annual pelage changes were therefore achieved with one main growth period, although many secondary follicles underwent another brief hair cycle in spring.

Studies have been conducted to examine the response of broilers to diets varying in nutrient density. Constant energy:nutrient ratios were maintained in diets for growing broilers fed 2970 to 3740 M.E. kcal./kg. and measurements made of weight gain, feed consumption, efficiency of feed utilization, calorie:gain ratios, and various carcass characteristics.Growth rate and efficiency of feed utilization were almost direct functions of the dietary nutrient density level. Broilers offered higher energy diets consumed a greater number of calories but converted these to gain with little impairment in caloric efficiency. Regression analyses were used to derive equations for predicting changes in feed consumption and growth rate associated with changes in dietary nutrient density level.

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