Submitted to: Domestic Animal Endocrinology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/27/2015
Publication Date: 4/1/2016
Publication URL: http://handle.nal.usda.gov/10113/61818
Citation: Lents, C.A., Brown-Brandl, T.M., Rohrer, G.A., Oliver, W.T., Freking, B.A. 2016. Plasma concentrations of acyl-ghrelin are associated with average daily gain and feeding behavior in grow-finish pigs. Domestic Animal Endocrinology. 55:107-113.
Interpretive Summary: Feeding behavior is an important component of growth and feed efficiency in swine. Identifying the physiological mechanisms that regulate feeding behavior in pigs is an important area of research. ARS scientists at Clay Center, Nebraska, studied ghrelin, a hormone produced by the stomach, which is thought to stimulate hunger and feed intake. They measured two forms of the hormone; total ghrelin and acyl-ghrelin. Using computerized feeding stations that record when individual pigs eat, scientists discovered that concentrations of acyl-ghrelin were correlated with the number of meals, meal length, and average daily gain in finishing pigs. Scientists also discovered that concentrations of acyl-ghrelin differed between males and females and with breed of the sire. This is the first report that has evaluated the relationship of ghrelin with feeding behavior in grow-finish pigs under commercial conditions. Further understanding of how ghrelin contributes to variation in feeding behavior and growth will be critical to improve feed efficiency of pigs. Improving feed efficiency of pigs is necessary to maintain the competitiveness of the U.S. pork industry while minimizing the use of natural resources in swine production.
Technical Abstract: Feeding behavior is an important component of growth and feed efficiency in swine. Acyl-ghrelin is a peptide produced in the stomach that is orexigenic. The role of ghrelin in regulating feeding behavior in swine under commercial conditions is unknown. The objectives of this study were to determine the effect of sex, sire line, and litter size on concentrations of ghrelin in plasma of grow-finish pigs, and to understand the relationship of plasma concentrations of ghrelin with feeding behavior, ADG, and back fat (BF) in grow-finish swine. Yorkshire-Landrace crossbred dams were inseminated with semen from Yorkshire, Landrace, or Duroc sires. Within 24 h of birth, pigs were cross-fostered into litter sizes of normal (N; > 12 pigs/litter) or small (S; = 9 pigs/litter). At 8 wk of age, pigs (n = 240) were blocked by sire breed, sex, and litter size and assigned to pens (n = 6) containing commercial feeders modified with a system to monitor feeding behavior. Total time eating, number of daily meals, and duration of meals were recorded for each individual pig. Body weight was recorded every 4 wk. Back fat and loin eye area (LEA) were recorded at the conclusion of the 12-wk feeding study. A blood sample was collected at week 7 of the study to quantify concentrations of acyl- and total ghrelin in plasma. Pigs from S litters weighed more (P < 0.05) and tended (P = 0.07) to be fatter than pigs from N litters. Postnatal litter size did not affect ADG, feeding behavior, or concentrations of ghrelin in plasma during the grow-finish phase. Barrows spent more time eating (P < 0.001) than gilts but the number of meals and concentrations of ghrelin did not differ with sex of the pig. Pigs from Duroc and Yorkshire sires had lesser (P < 0.0001) concentrations of acyl-ghrelin than pigs from Landrace sires, but plasma concentrations of total ghrelin were not affected by sire breed. Concentrations of acyl-ghrelin were positively correlated with the number of meals and negatively correlated with meal length and ADG (P < 0.05). A larger number of short-duration meals may indicate that pigs with greater concentrations of acyl-ghrelin consumed less total feed, which likely explains why they were leaner and grew more slowly. Acyl-ghrelin is involved in regulating feeding behavior in pigs, and measuring acyl-ghrelin is important when trying to understand the role of this hormone in swine physiology.