Lysine requirements of laying hens in a practical farm
1997
Yamamoto, A. (Niigata Univ. (Japan)) | Ishibashi, T.
In order to confirm that the lysine (Lys) requirement increased with dietary amino acid (AA) levels and that the Lys requirement determined from plasma Lys concentration agreed well with that determined from data of laying performance, the Lys requirement was determined in a practical farm using a large number of laying hens. Laying hens at 78 weeks of age were divided into 13 groups, housed individually and given free access to the experimental diets with 110 and 125% AA of NRC requirements (1994) and water for 47 days. The two basal diets contained graded six Lys levels. Egg weight was recorded every three days, feed intake was recorded every six days and body weight was recorded at the beginning and end of the experiment. Blood samples were taken at the last day of the experiment for the determination of plasma Lys concentration. The maximum egg production rate and ratio of egg mass: feed intake on the 110% diets were inferior to those on the 125% diets. The Lys requirements were estimated to be 0.56, 0.56 and 0.57% for the 110% diet, and 0.61, 9.59 and 0.61% for the 125% diet, respectively, from the data of egg production rate, ratio of egg mass: feed intake and plasma Lys concentration. These results indicated that 110% AA of NRC (1994) was deficient for the maximum laying performance and that the Lys requirement increased with increasing dietary CP or AA levels
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