A study of the protein and amino acid requirements of the growing New Zealand White rabbit with emphasis on lysine and the sulphur-containing amino acids

Abstract

1. New Zealand White (NZW) rabbits were given, between 4 and 8 weeks of age, a range of diets, based on oats and fish meal, containing from 104 to 255 g crude protein (nitrogen x 6.25; CP)/kg to establish the level of CP below which growth was retarded. 2. In three experiments each diet was fed to four animals and food intake, growth and N balance were measured over 4 weeks. Body analysis was also carried out after two of the experiments. 3. The rates of food intake and growth of animals increased with dietary CP concentration until a CP concentration of approximately 150 g/kg diet had been reached. Beyond this there was little further improvement. N balance studies showed that once this dietary concentration of CP had been reached, there was a reduced rate of N retention. 4. Good agreement was found between N retention measured by balance methods and by body analysis: body composition showed a tendency towards an increase 5. Microbial protein produced in the caecum and eaten during coprophagy, was found to supplement the dietary protein by approximately 2 g CP/d, or by only 0.1 of a normal dietary intake of CP. 6. In the second part of the study NZW rabbits were offered, between 5 and 8 weeks of age, diets based on oats containing 150 g CP/kg. The protein supplied by oats was supplemented with maize gluten, gelatin, groundnut meal, casein, soya-bean meal or fish meal. 7. Rabbits offered diets containing casein, soya-bean meal and fish meal gained 40-50 g/d similar, to animals given a well-balanced control diet, while those given diets containing maize gluten, gelatin or groundnut meal gained approximately 30 g/d. This indicated that amino acid balance in dietary protein was important to the growing rabbit. 8. In later experiments, diets based on cereals and groundnut meal supplemented with varying amounts of lysine and methionine were offered during a 3-week-post-weaning period in order to assess requirements for those limiting amino acids. 9. The addition of both lysine and methionine improved growth rates. The minimum requirements for normal growth were found to be 6.2 g methionine+cystine and 9.4 g lysine/kg diet.

New concepts and objectives for protein-amino acid nutrition in rabbits: a review.

“…Studies performed at INRA (Lebas et al, 1973;Colin 1974, 1975 a and and those of Davison and Spreadbury (1975) and Spreadbury (1978) led to confirming the essentiality of these amino acids and the high requirements of arginine, in contrast to the ones observed in poultry. They also suggested that the optimal level of an amino acid depends on the balance with other amino acids and the level of energy in the diet, so the recommendation for lysine is given in grams per 1000 kcal of digestible energy.…”

Energy and nitrogen metabolism of rabbits during pregnancy, lactation, and concurrent pregnancy and lactation

“…All animals were housed in the metabolism cages described by Spreadbury (1978). The period of pregnancy and lactation was divided into three consecutive periods of 8 d after animals had been allowed to adapt to their designated feeding levels for 4 d. Urine and faeces were collected separately each day and stored at I".…”

Levels of lysine and methionine+cystine for growing New Zealand White rabbits

“…Studies to determine the required levels of amino acids for rabbits began in the 1960s (McWard et al, 1967;Gaman & Fisher, 1970;Cheeke, 1971;Adamson & Fisher, 1971, with those focusing on commercial animals starting in the 1970s (Lebas et al, 1973;Colin, 1975;Davison & Spreadbury 1975;Spreadbury, 1978) and forming the basis of the nutritional recommendations included in the NRC (NRC, 1977).…”