Lysine requirement of laying hens estimated by plasma lysine concentration at two days after changing dietary lysine levels repeatedly using the same hens
Yamamoto, A.; Yamashita, T.; Kokawa, K.; Watanabe, R.; Fujimura, S.; Ishibashi, T.
Animal Science and Technology 68(10): 934-939
The lysine requirements were estimated from data of plasma lysine concentration at two days after changing successively dietary lysine levels using repeatedly the same laying hens. At 46 weeks of age, 20 laying hens with average body weight and high egg production rate were accustomed gradually to the 0.65% lysine diet for five days. After then, the 0.65% lysine diet was switched successively to 0.75, 0.55, 0.85 and 0.45% lysine diets at two day interval. About 0.4 ml of blood was taken from the wing vein between 13:00 and 14:00. The plasma amino acid concentration of six laying hens which laid on the day and the next day of blood sampling throughout the experimental period was determined. No negative effects of frequent blood sampling and dietary deficient or excess lysine levels on egg production, egg size, feed intake and body weight were observed. The plasma lysine concentration was maintained at about 50 nmol/ ml, when the dietary lysine levels or lysine intake was less than the lysine requirement level, and then increased linearly with increasing dietary lysine levels. From the break point, the lysine requirements were estimated to be 0.61+-0.01% and 693+-3 mg/hen/d. These values were similar to those obtained by laying performance in the laboratory (0.63%) and the commercial farm (0.60%) indicating that it was possible to determine the lysine requirement using repeatedly the same laying hens in a short period.