AFA Research Report - Lysine Requirement of Cockatiel Chicks

Abstract

INTRODUCTION

Lysine may be the single most important amino acid that affects the protein nutrition of captive birds fed practical diets. It is the essential amino acid most often limiting in cereals and other seeds which comprise the main sources of nutrition for many caged birds. A deficiency of lysine in the diet of young domestic birds such as chickens, quail and turkeys results in poor growth and in failure to deposit the normal dark melanin pigments of feathers. Because body size and feather color are important considerations when assessing the value of caged birds, lysine nutrition had a high priority among problems that needed study.

This project was designed to determine the quantitative lysine requirement of young cockatiel chicks, based primarily on growth. Feather pigmentation was also studied. The basic approach was to feed newly hatched chicks diets in which the amino acids were provided by mixtures of pure amino acids in place of protein. The lysine content of the diet could thus be varied from low to high levels and the effects on growth and feathering determined.

 MATERIALS AND METHODS

The management techniques used here were virtually identical with those we developed and presented in our final report of June 1983 to the AFA Research Committee: "Solid Food Requirements and Water Tolerance of Cockatiel Chicks from Hatching to Five Weeks." The basal diet, presented in Tables 1, 2, and 3, did not include lysine, which became the single variable in two feeding trials with groups of cockatiel chicks.

The levels of L-lysine added to the dry basal diet varied from O .1 % to 2.0%. Each group of 12-17 chicks was fed its diet from hatching to 14 days of age or longer. One of these experiments was concluded at 14 days, but then the chicks were fed either the same diets or were shifted to alternatives in order to observe recovery or, in the case of one group, the effects of imposing a deficiency half way through the growth period. Each bird was weighed each day before the first feeding at 6 a.m. Mortalities were recorded. Observations of feather pigmentation of all chicks were made from the time juvenile feathers could first be seen through the skin at 10 days until the experiments were concluded at fledging.

 RESULTS

In the first experiment, the groups were fed the four levels of lysine to 14 days, at which time the results of feeding the diets were clear. The lowest level of lysine (0.1 %) permitted only poor growth and survival, but 0.4% permitted much better growth and good survival, as shown in the growth data of figure 1 and table 4. The groups fed 1.0% or 2.0% lysine survived and grew well but not as rapidly as similar chicks fed 20% protein from isolated soybean protein supplemented with methionine, as presented in the report of our first study.

After 14 days, when the group fed 2. 0 % lysine was shifted to the diet containing 0.4 % lysine, growth continued at approximately the same rate for 8 days, essentially in the same pattern as the group fed 1.0% lysine for the whole period. Meanwhile the group that was shifted from 0.4% lysine to the 20% protein diet grew rapidly and continued to gain up to the weight expected by fledging (80-90 grams).

The levels of lysine that had been chosen for the second experiment were based on the results of the first study. The lowest level (0.2 %) permitted only slow growth (table 5 and figure 2), but was better than 0.1% lysine in experiment 1. Survival was also better with 0.2% lysine (table 5). Groups fed higher levels grew faster until the level of0.8% lysine was reached and when maximum growth was obtained. As in the first experiment, body weight at 14 days of age was used as the criterion for determining the lysine requirement, as shown in Figure 3.

None of the groups fed the amino acid-containing diets grew as well as those fed the protein-based diet. No observable differences accounted for this effect.

With regard to feather pigmentation, no white or light feathers or parts of feathers were observed in areas that are normally dark. These observations were made...