The response of broiler breeder hens to dietary lysine and methionine

Abstract

1. Broiler breeder hens were used in an experiment lasting 10 weeks (29 to 38 weeks of age) to measure the responses to dietary lysine and methionine, the main objective being to determine whether the coefficients of response to these amino acids were the same for broiler breeders and for laying pullets. 2. The hens were offered 150 g/d of one of 20 dietary treatments, 10 being lysine-limiting and 10 being methionine-limiting. The diets were mixed by diluting one of two concentrate (summit) mixes with a protein-free dilution mixture. The lysine-limiting summit diet was designed to supply approximately 1300 mg lysine/bird d, while the other supplied 520 mg methionine/bird d, when fed at 150 g/bird d. 3. Birds on the 5 lowest concentrations of both lysine and methionine did not consume the allotted amount of food, the amount decreasing, in a curvilinear fashion, to approximately 105 g/bird d. 4. The minimum egg weight recorded was 0.8 of the maximum, whereas the rate of lay of birds fed on the diets with the lowest amino acid concentrations was 0.2 of the maximum. 5. Using the Reading Model, the coefficients of response were calculated to be (for lysine) 16.88 E and 11.2 W, and for methionine, 7.03 E and 1.52 W, where E = egg output, g/bird d, and W = body mass, kg/bird. An average, individual, broiler breeder of 3 kg, producing 45 g of egg output per day, would need 793 mg of lysine and 321 mg of methionine daily. This intake of methionine is similar to that estimated by means of coefficients used for laying pullets, but the lysine requirement would be underestimated by 0.18 if the coefficients for laying pullets were used. 6. The coefficients for maintenance for both lysine and methionine, determined in this experiment, are considerably lower than values published previously, whilst the coefficients for egg output are, in both cases, higher. The resultant flock response curves therefore differed significantly from those in which the coefficients of response for for laying pullets were used.(ABSTRACT TRUNCATED AT 400 WORDS)

Reevaluation of Methionine Requirement Based on Performance and Immune Responses in Broiler Breeder Hens

“…In accordance with the results of the present study and those reported by Bowmaker and Gous (1991) methionine requirement for EP was 342 and 355 mg/d, respectively. These amounts were near to the methionine level in the basal diet (322 mg/d), which could provide the minimum methionine requirement for reproductive performance.…”

Utilisation of synthetic amino acids by broiler breeder hens

“…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. It is likely that lysine was not first-limiting in the present trial, given its lower efficiency compared with that for methionine.…”

Response of laying hens to methionine + cystine intake by dilution technique

“…The increase in feed intake is an attempt by the birds to consume the required amount of the limiting amino acid to maintain egg production; however, when the deficiency becomes more severe, an increasing feed intake is not possible because the bird would increase heat production (Bowmaker and Gous, 1991). The latter finding is due to the change in the relationship between energy and protein in the diets, which provided more energy intake than necessary to maintain egg production with the lowest met+cys levels.…”