THE EFFECT OF A LYSINE DEFICIENCY ON BODY WEIGHT AND AGE AT SEXUAL MATURITY OF MEAT-TYPE PULLETS1

Nutritional manipulations and man-agement techniques for reducing growth rate and delaying sexual maturity in replacement pullets have been studied ex-tensively without uncovering any com-pletely satisfactory solution. Recently Gordon (1963) reported that the growth of chicks could be arrested, without appar-ent ill effects, by reducing the tryptophan level of the diet. Similar results have been observed in 4-week old chicks in this laboratory using a lysine-deficient diet. These observations suggested that amino acid deficiencies might provide a means by which growth rate and possibly age at sexual maturity could be modified in re-placement pullets, provided there were no subsequent detrimental effects. One experiment has been conducted to explore these possibilities. The experimental design involved the use of a "normal " and a lysine-deficient ration and a periodic ration reversal tech-nique. The lysine-deficient ration was composed of ground yellow corn 14.7%, wheat middlings 10.0%, ground barley 27.0%, corn gluten meal 25.0%, dried whey 3.0%, fat 5.0%, alfalfa meal 3.0%, distillers dried solubles 2.0%, soybean meal (50 % protein) 5.0%, and adequate vitamin and mineral supplements. Using the values of Almquist (1957), lysine cal-culated to be the first limiting amino acid