EXAMINATION OF THE DIETARY METHIONINE REQUIREMENTS OF BREEDING NORTHERN BOBWHITE, COLINUS-VIRGINIANUS

Adult Northern bobwhite were used to test the hypothesis that dietary methionine levels recommended by the NRC for breeding quail are excess ive for wild bobwhite. We tested the hypothesis by comparing immunocom petence, reproductive performance, and chick viability of Northern bob white hens fed diets containing low (0.31%), moderate (0.39%), or high (0.47%) concentrations of methionine. Chick viability was determined by assessing immunocompetence, including evaluating the ability of hen s to passively transfer immunity to their chicks. Hens were fed the ex perimental diets for 6 wk on an ad libitum basis. After 6 wk, methioni ne treatment had no measurable effect (P greater than or equal to 0.20 ) on hen phytohemagglutinin wing web indices, organ weights, or serum anti-Pasteurella multocida titer indices. Mean egg weight, percentage egg production, total cumulative egg production, yolk weight, yolk vol ume, and percentage fertile and percentage hatch of fertile eggs did n ot differ (P greater than or equal to 0.12) among diet treatments. Amo unt of albumen in eggs produced by hens fed the high methionine diet a veraged 0.27 g more (P = 0.003) than eggs of hens fed the low methioni ne diet. Anti-P, multocida titer of yolks from eggs in Week 6 were not different (P = 0.36) between birds fed the high and the low methionin e diets. The mortality rate of chicks after challenge with 23 cfu of P . multocida was not different (P greater than or equal to 0.05) among diets. Chicks hatched from eggs laid by vaccinated hens during Weeks 2 and 3, however, had lower (P < 0.05) mortality than chicks of unvacci nated hens. It appears a dietary methionine concentration of 0.3% may be sufficient for wild Northern bobwhite to produce viable chicks.