The nitrogen requirement of the weanling kitten

Abstract

1. The nitrogen requirement of the weanling kitten was determined in a series of three experiments. In each experiment, diets were formulated to provide the growing kitten with the essential amino acids at or above the level of requirement. Expt 1 utilized a 4 x 4 balanced Latin square design with two groups of kittens (four male and four female). The crystalline L-amino acid diets were presented at four levels of dietary crude protein (N x 6.25) of 140, 160, 180 and 200 g/kg diet. The design for Expts 2 and 3 was a 6 x 6 balanced Latin square. For each of these experiments, groups of six male and six female kittens were assigned to diets. The six levels of dietary crude protein were 120, 140, 160, 180,200 and 220 g/kg diet; dietary N was supplied by crystalline L-amino acids for Expt 2 and casein plus a supplementary amino acid mix for Expt 3. Food intake, weight gain and N retention were determined in each experiment.2. A sigmoidal model y = P1+ P2/[1 +e(p3+p4. z)] was fitted to the response of weight gain and N retention to dietary N. The calculated requirement (95% of the upper asymptote, P1 +P2) for these experiments varied from 170 to 230 g protein/kg diet with the majority of these values falling between 180 and 200 g protein/kg.3. On the basis of these three experiments, the kitten's requirement for dietary crude protein is between 180 and 200 g/kg diet (28.8-32.0 gN/kg) for purified diets which provide a calculated 21 MJ metabolizable energy/kg diet.The dietary requirement for protein is based on two metabolic demands: (1) the necessity for sufficient quantities of essential amino acids in the proper proportions, (2) the necessity for adequate amounts of nitrogen to provide for the synthesis of non-essential amino acids and other nitrogenous compounds.Within the last 5 years the essential amino acid requirements for maximal kitten growth have been determined with crystalline L-amino acid diets. Protein requirements of the kitten determined before this information was available may have been inflated due to insufficient amounts of a particular amino acid. In addition, protein requirements determined using animal protein sources may be confounded by the association of the level of protein and palatability of the diet. Based on studies in which either casein or a mixture of fish and liver were used as the protein source (Dickinson & Scott, 1956; Miller & Allison, 1958;Jansen et al. 1975), the (US) National Research Council (1978) recommended that 'a protein of a quality equivalent to that derived from unprocessed mammalian, avian or fish muscle should be presented at a level of 28 % of metabolizable energy (ME) in the diet of a growing kitten. This is equivalent to 35 % protein in a diet (dry basis) providing 21 kJ (5 kcal) MEjg dry matter'. To define the N requirement more precisely we have completed three experiments in which all essential amino acids were supplied in adequate amounts and N was supplied as individual amino acids or casein. Food intake, weight gain and N retention have been determined in...

Effect of oral administration of L-lysine on conjunctivitis caused by feline herpesvirus in cats

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Increasing dispensable amino acids in diets of kittens fed essential amino acids at or below their requirement increases the requirement for arginine

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Maximal growth occurs at a broad range of essential amino acids to total nitrogen ratios in kittens

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