Date of Graduation


Document Type


Degree Name

Doctor of Philosophy in Poultry Science (PhD)

Degree Level



Poultry Science


Susan E. Watkins

Committee Member

Randolph J. Chick

Second Committee Member

Nicholas B. Anthony

Third Committee Member

Charles V. Maxwell


Betaine, Broiler, Methionine, Methyl Donor, Sparing


4,096 broiler chicks were randomly allocated to 128 floor pens (32 birds/pen). 2,048 day-old male broilers were placed in the east end of a barn, and the following week 2,048 day-old male broilers were placed in the west end. At each placement day, half of the chicks were Cobb 500 and half were Ross 708, and each pen contained only one breed source. East end birds received coccidiostat in the feed, west end received coccidial vaccine, and each end was under separate environmental control. Eight diets contained two levels of coccidiostat (0, 1 lb./ton), methionine (deficient, adequate), and betaine (0, 2 lb./ton). Live weights were measured at days 0, 15, 31, 42 and 56. Cocci scoring was performed on day 22, ammonia flux was measured on day 36, and paw scoring was performed on days 42 and 56. Processing occurred on days 43 (5 birds/pen) and 57 (5 birds/pen). There were no significant differences between treatments in live weights for days 15, 31, 42, or 56. Day 42 paw scores for birds fed betaine + deficient methionine were significantly lower than other treatments, for Cobb Treatments 3 and 7, and for Ross Treatment 3. Birds in the west end had no cocci lesions, while the east did. Ross birds receiving coccidiosis-vaccine, fed betaine + reduced methionine had lower ammonia flux than Ross birds receiving either coccidiostat, fed no betaine + reduced methionine or Ross birds receiving coccidiosis-vaccine, fed betaine + adequate methionine. At day 57, Cobb birds fed betaine + reduced methionine had significantly higher breast and tender weights than all other Cobb birds, while Ross birds fed reduced methionine + no betaine had higher wing weights than any Ross birds receiving betaine. These findings indicate betaine supplementation can act to partially spare methionine. Betaine supplementation was also shown to decrease single-day heat-related mortality and also affect processing performance in broilers reared to heavy weights.