Gestational Heat Stress can Have Long-Term Pork Quality Impacts

Lora Berg 1, Editor

August 11, 2014

3 Min Read
Gestational Heat Stress can Have Long-Term Pork Quality Impacts

Heat stress costs the U.S. swine industry more than $300 million annually in reduced growth and efficiency, decreased reproductive performance, altered carcass composition and slowed swine metabolism, according to Jason Ross, Iowa State University (ISU) reproductive physiologist. Ross and his ISU colleagues recently joined a multi-state National Institute of Food and Agriculture-funded research project, led by Lance Baumgard, ISU nutritionist, to investigate the long-term impacts that in utero heat stress can have on the body composition of pigs all the way through the finishing phase.

“The detrimental effects of heat stress on animal productivity have been well-documented,” Ross explains. “However, whether gestational heat stress interacts with a future environmental insult to alter tissue deposition during the early finishing phase in pigs is unknown. The objectives of our recent studies were to compare the subsequent rate and quantity of tissue accretion in finisher pigs exposed to differing in utero and postnatal thermal environments, to determine whether prenatal heat stress has biological implications for postnatal piglet growth and development.”

As part of the research, nine pregnant gilts were exposed to thermal neutral (TN) conditions with cyclical nighttime temperatures of 59º F and a 71º F daytime temperature, while 11 gilts were exposed to heat-stress (HS) conditions consisting of cyclical temperatures of 80º F at night and 98º F during the day throughout the entire gestation period. Offspring from gestational TN (GTN) conditions included six gilts and six barrows weighing approximately 137 lb. The gestational HS (GHS) group of offspring was made up of six gilts and six barrows weighing approximately 136 lb.

Some gilts were euthanized as part of an initial slaughter group. Following the sacrifice of the initial slaughter group, pigs from the GTN and GHS groups were exposed to HS (93° F) or TN (72° F) conditions until they reached approximately 177 lb., at which point they were sacrificed.

Researchers found that rectal temperature and respiration rates were increased during postnatal HS compared to TN (103 ˚F vs. 102˚ F, and 92 vs. 58 breaths per minute, respectively). Postnatal HS decreased feed intake (19.4%) and average daily gain by 1 lb., 8 oz. vs. 2 lb., 1 oz. compared to TN conditions, but neither variable was influenced by gestational environment.

The research team notes that protein and adipose tissue accretion rates were reduced in HS pigs compared to TN controls by 126 g/day vs. 164 g/day and 218 g/day vs. 294 g/day, respectively. In utero HS independently reduced protein accretion by 16%, and increased adipose accretion rates by 292 g/day vs. 220 g/day compared to GTN in the finisher phase. The ratio of adipose to protein accretion rates increased by 95% in pigs experiencing GHS compared to GTN.

In summary, experiencing heat stress in utero impacted the future hierarchy of tissue accretion in the pig, with the altered nutrient partitioning favoring adipose tissue deposition at the expense of skeletal muscle during this phase of growth, according to the researchers.

Researchers include: Jay S. Johnson, M. Victoria Sanz Fernandez, John F. Patience, Jason W. Ross, Nicholas K. Gabler and Lance H. Baumgard, all of Iowa State University, Ames, IA; Mathew C. Lucy and Timothy J. Safranski, University of Missouri, Columbia, MO; and Robert P. Rhoads, Virginia Tech, Blacksburg, VA. For more information, contact Patience at (515) 294-5132.     

About the Author(s)

Lora Berg 1

Editor, National Hog Farmer

Lora is the editor of National Hog Farmer. She joined the National Hog Farmer editorial team in 1993, served as associate editor, managing editor, contributing editor, and digital editor before being named to the editor position in 2013. She has written and produced electronic newsletters for Farm Industry News, Hay & Forage Grower and BEEF magazines. She was also the founding editor of the Nutrient Management e-newsletter.

Lora grew up on a purebred Berkshire operation in southeastern South Dakota and promoted pork both as the state’s Pork Industry Queen and as an intern with the South Dakota Pork Producers Council. Lora earned her bachelor’s and master’s degrees from South Dakota State University in agricultural journalism and mass communications. She has served as communications specialist for the National Live Stock and Meat Board and as director of communications for the University of Minnesota College of Agricultural, Food and Environmental Sciences. During her career, Lora earned the Story of the Year award from the American Agricultural Editors’ Association and bronze award at the national level in the American Society of Business Publication Editors’ competition. She is passionate about providing information to support National Hog Farmer's pork producer readers through 29 electronic newsletter issues per month, the monthly magazine and website.

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