Effects of Methionine and Valine on Antibody Production in Chicks Infected with Newcastle Disease Virus

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Abstract
Day-old chicks were fed amino acid diets and then infected with B1 strain of Newcastle disease virus at 4 days of age. Deficiencies of methionine or valine were studied in an otherwise complete diet. The average weight and the feed efficiency improved with an increase in the level of methionine in the diet. The L- form induced a better response with respect to chick growth, feed utilization, and antibody production than D-methionine. Significant differences (P < 0.05) were observed in the average weight and HI titers (the reciprocal of the highest dilution of the serum that inhibits the agglutination of chicken red blood cells by the Newcastle disease virus) of chicks. The antibody titer was higher for chicks receiving 0.3% to 0.6% L-methionine levels than for chicks receiving 0.7% to 1.1% L-methionine. The optimum requirement of methionine for growth was 0.7% while for antibody production it was considerably lower. As valine was increased in the diet, there was an improvement in the average weight, feed efficiency, and antibody titer. At low levels of valine in the diet (0.5 to 0.7%) the antibody titer was low, but at high levels (0.9 to 1.5%) it increased. The requirement of valine for maximum growth response was 0.9%, but for optimum antibody production it was somewhat higher. A nearly linear relationship was observed between the HI titer and neutralization index of serum samples.