Quantitative review of optimum amino acid intakes for young laying pullets

Abstract

Data relating egg output to daily intakes of lysine, methionine, tryptophan, isoleucine and valine have been analysed using both published and unpublished sources. Amino acid requirements in mg/d for individual pullets were estimated by the following equations: (Table: see text) where E = egg output in g/d and W = body weight in kg. Response curves for flocks of pullets were calculated using the Reading model and optimum intakes were derived for various body weights, egg outputs and ratios of input costs to output values. Estimates of amino acid maintenance requirements were related to reported values for the adult cockerel and the amino acid requirement for egg output was related to the digestibility of amino acids and the composition of egg protein. Procedures are suggested for deriving response coefficients for other essential amino acids.

Utilisation of synthetic amino acids by broiler breeder hens

“…To ensure that this was not the case here, all essential amino acids were considered when formulating feed B100, making use of the requirements specified by , thus taking care that the amino acid balance in the two basal feeds was relatively constant. Of the non-test amino acids only tryptophan was not Morris & Blackburn, 1982;McDonald & Morris, 1985) the as at a maximum rate o iency of between 0.75 and 0.85 has been suggested by M in excess of requirement. However, the small difference in tryptophan content between the two basal feeds suggests that it is unlikely that the large differences in response measured here could have been a response to tryptophan or indeed to any of the other non-test amino acids, especially as the same ingredients were used to supply these amino acids in both basal feeds.…”

“…When laying in closed cycles, broiler breeders should be as efficient as laying hens in converting dietary amino acids to egg output (Fisher, 1980): an effic cDonald & Morris (1985) and by Emmans & Fisher (1986). Broiler breeders fed intact protein here utilised lysine and methionine for egg production with mean efficiencies of 0.55 and 0.62, respectively, these being lower than the equivalent values estimated for laying hens, but similar to those reported by Bowmaker & Gous (1991) (0.47 for lysine and 0.50 for methionine) and Goddard (1997) (between 0.58 and 0.68 for lysine) in their studies with broiler breeders.…”

Lysine requirements of laying hens

“…Under practical market conditions, it is unlikely that the most economical diet supplies all of the essential amino acids in the optimal amounts (McDonald and Morris, 1985). An alternative is to know the response pattern of the hen to the amino acids and analyze whether the responses are more profitable at rates below the maximum production.…”

“…An alternative is to know the response pattern of the hen to the amino acids and analyze whether the responses are more profitable at rates below the maximum production. Therefore, McDonald and Morris (1985) recommended that the amino acid supply should be calculated using the production rate determined by the first limiting amino acid.…”

“…The economic optimum level of Lys intake calculated by McDonald and Morris (1985) for the cost-benefit ratio k ¼0.004 was 700, 750 and 800 mg of Lys according to 40, 45 and 50 g/day of E max , respectively, and 1.5 kg of body weight. As stated, the differences are related to the variability in the population.…”