Heat stress has serious negative consequences for the swine industry by reducing feed intake and growth performance in pigs. Based on commercial observations, we estimate that heat stress during the summer results in a reduction of hot carcass weights of approximately 6 to 10 lbs in fixed time production systems. By using dietary heat abatement strategies, we can improve the efficiency of pork production, thus minimizing the cost of feed per unit of pork produced.
In the present studies, we determined the impact of dietary betaine as a heat abatement strategy in swine. Betaine is an osmolyte and has an important role in maintaining water homeostasis and cell integrity. Beneficial effects of betaine during heat stress have been demonstrated in poultry and rabbits. To achieve this objective, 3 experiments were conducted. In Experiment 1, effects of dietary supplementation of natural betaine (0, 0.10, 0.15, or 0.20%) on pig performance and metabolic status during thermo-neutral and heat stressed conditions was evaluated using 64 pigs. Heat stress negatively impacted daily gain, feed intake, respiration rate and rectal temperature, as expected. Betaine appeared to reduce respiration rate and rectal temperature in heat stressed pigs, but did not have major impacts on serum chemistry or growth performance. In Experiment 2, the impact of betaine during heat stressed conditions on pig performance and carcass characteristics was evaluated in 1,477 pigs fed diets with or without Paylean in a commercial production facility. Betaine reduced feed intake, but did not impact any other measures of pig growth performance or carcass characteristics. Paylean improved growth performance and carcass characteristics, resulting in an increased final carcass weight of 8.9 lbs and a reduction in feed used per unit of carcass gain of 17%. In Experiment 3, a dose titration study was conducted to evaluate the impact of betaine in late finishing pigs housed under heat stressed conditions using a total of 2,193 crossbred pigs. Betaine supplementation at 1.25, 2.50, or 3.75 lbs per ton had no effects on growth performance or carcass characteristics. Paylean increased final carcass weight by 5.35 lbs and reduced the amount of feed used per unit of carcass gain by 13.6%. Collectively, these data indicate that under practical, commercial conditions, betaine did not improve pig performance or carcass characteristics when supplemented at 1.25, 2.50, and 3.75, and 4.00 lbs/ton. These studies were conducted during heat stress and betaine was supplemented during the last phase of production, with pigs weighing approximately 200 to 210 lbs until market weight. Results from these studies do not support the use of betaine in diets for late finishing pigs housed under heat stressed conditions. Supplementation with Paylean clearly improved pig performance and carcass characteristics, resulting in an immediate net economic benefit to pork producers.

Eric van Heugten
North Carolina State University
Box 7621
Raleigh, NC 27695-7621
Phone: (919) 513 1116""
E-mail: Eric_vanHeugten@ncsu.edu