Date of Award


Document Type


Degree Name

Doctor of Philosophy (PhD)


Animal Science (Animal, Dairy, and Poultry Sciences)

First Advisor

L. Lee Southern


The purpose of this research was to determine the effects of dietary betaine in swine and poultry under conditions that may benefit the swine and poultry industries. In finishing pigs, one experiment was conducted to determine the effect of dietary betaine level on growth, carcass traits, and pork quality. Another experiment evaluated the interactive effects of betaine, pen spacing, and slaughter handling method. In weanling pigs, five experiments were conducted to determine the interactive effects of betaine and Zn, or to determine if betaine can replace a portion of the methionine requirement. In poultry, two experiments were conducted to determine if betaine affects energy utilization. Betaine did not have a consistent effect on growth or carcass traits in finishing pigs, but 0.25% betaine improved carcass leanness in one of two experiments. Betaine did not improve growth or carcass traits of pigs subjected to inadequate pen space. The pH of pork was increased and drip loss was decreased in pigs fed betaine. In weanling pigs, betaine improved growth performance in the presence of excess Zn, but it decreased performance in the absence of excess Zn. This effect was most pronounced during the first 2 wk post-weaning. However, in weanling pigs, betaine did not replace a portion of the methionine requirement. Betaine did increase average daily gain (ADG) of pigs fed methionine-deficient diets, but the increase in ADG was due to betaine stimulating average daily feed intake (ADFI). Thus, pigs fed betaine in methionine-deficient diets consumed similar amounts of total sulfur amino acids compared with pigs fed methionine-supplemented diets. In chickens, the effects of betaine on energy utilization were inconsistent. In one experiment, betaine decreased ADG and ADFI in chicks from 0 to 21 d post-hatching. However, in a similar experiment, betaine decreased energy intake and increased the amount of weight gain per unit of energy consumed. Thus, in chickens, the effect of betaine in improving energy utilization was minimal and inconsistent.