Effects of feeding pattern on ghrelin and insulin secretion in pigs.
ABSTRACT Ghrelin is a peptide hormone that has been implicated in the regulation of feed intake, but little is known about its secretion in pigs. Hence, the effect of feeding pattern on the regulation of ghrelin secretion was tested. In experiment 1, barrows were allotted randomly into 1 of 2 groups, (1) ad libitum fed (CONT) and (2) limited access to feed (once per day, MEAL). Blood samples were taken through jugular catheters every 15 min for 6 h after 7 d on the experimental feeding regimen. Plasma concentrations of ghrelin and insulin were determined by radioimmunoassay. Ghrelin concentrations in the MEAL pigs were elevated before feeding and declined after feeding (P < 0.01). No pattern in plasma ghrelin concentrations was observed in the CONT pigs, but ghrelin concentrations were lower than in the MEAL group. Insulin concentrations were greater in CONT pigs (P < 0.01) during most of the sampling and increased after feeding in the MEAL pigs (P < 0.01). In experiment 2, the treatments were the same as in experiment 1; however, the amount of feed was increased in the MEAL group so that their daily intake was similar to the CONT pigs. Ghrelin concentrations in the MEAL group were again elevated before the meal and declined afterward (P < 0.01). Insulin but not glucose concentrations were negatively correlated with ghrelin. Once-per-day feeding resulted in increased plasma concentrations of ghrelin, which decreased after feeding. Ghrelin may be involved in the regulation of feed intake in pigs.
- [Show abstract] [Hide abstract]
ABSTRACT: Radioimmunology was used to determine leptin and ghrelin levels in sow colostrum and milk in relation to those in sow and neonatal pig blood plasma and to the body weight of piglets during the first week of lactation. The highest concentration of leptin was found in colostrum on the second day of lactation (69.3 ± 6.3 ng/mL). Leptin concentrations in sow plasma were significantly lower than in colostrum/milk (2.19 ± 0.9 ng/mL, P = 0.7692) and were stable in the first 7 days of lactation. Total and active ghrelin concentrations in colostrum/milk were stable in the measured time points (6734 ± 261 pg/mL, P = 0.3397; 831 ± 242 pg/mL, P = 0.3988, respectively). Total ghrelin concentrations in sow plasma were lower than in colostrum/milk. These results indicate that pigs follow a unique species-specific pattern of leptin and ghrelin synthesis, release and existence, and that the mammary gland is an important source of leptin and ghrelin contained in colostrum/milk.Animal Science Journal 08/2013; · 1.04 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: Following domestication, livestock breeds have experienced intense selection pressures for the development of desirable traits. This has resulted in a large diversity of breeds that display variation in many phenotypic traits, such as coat colour, muscle composition, early maturity, growth rate, body size, reproduction, and behaviour. To better understand the relationship between genomic composition and phenotypic diversity arising from breed development, the genomes of 13 traditional and commercial European pig breeds were scanned for signatures of diversifying selection using the Porcine60K SNP chip, applying a between-population (differentiation) approach. Signatures of diversifying selection between breeds were found in genomic regions associated with traits related to breed standard criteria, such as coat colour and ear morphology. Amino acid differences in the EDNRB gene appear to be associated with one of these signatures, and variation in the KITLG gene may be associated with another. Other selection signals were found in genomic regions including QTLs and genes associated with production traits such as reproduction, growth, and fat deposition. Some selection signatures were associated with regions showing evidence of introgression from Asian breeds. When the European breeds were compared with wild boar, genomic regions with high levels of differentiation harboured genes related to bone formation, growth, and fat deposition.PLoS Genetics 04/2013; 9(4):e1003453. · 8.52 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: Objectives of this study were to measure both daily and periprandial plasma ghrelin concentrations of postpubertal Holstein heifers during prolonged undernutrition. Following an acclimation period, Holstein heifers [n = 10; 339.5 ± 8.6 kg of body weight (BW)] were fed ad libitum [well fed (WF); n = 5] or restricted to 50% of ad libitum intake [underfed (UF); n = 5) for 8 wk. Body condition scores (BCS) were recorded at the beginning and end of the treatment period, and weekly measurements of BW, plasma ghrelin, progesterone, and nonesterified fatty acids (NEFA) concentrations were obtained. Ovarian follicular and luteal structures were measured twice weekly via transrectal ultrasonography. Plasma ghrelin concentrations were also measured during a periprandial window bleed conducted at the end of the experiment. During the window bleed, samples were collected every 15 min between 0500 and 0900 h, with feed offered at 0700 h. Underfed heifers lost BW and BCS, whereas WF heifers gained weight and either increased or maintained BCS. Chronic underfeeding increased circulating ghrelin and NEFA concentrations. By wk 4 of the treatment period, circulating ghrelin concentrations of the UF heifers reached a plateau. Periprandial fluctuations in ghrelin concentrations were apparent as plasma ghrelin concentrations changed over time. Overall differences in periprandial plasma ghrelin concentrations were primarily due to prefeeding effects of plane of nutrition. Plasma ghrelin concentrations and change in BCS were negatively correlated such that heifers that lost the most BCS had the highest concentrations of circulating ghrelin. Two of the 5 UF heifers became anestrus by wk 3 of the treatment period. Despite being of similar age, the heifers that became anestrus had lower BW and plasma ghrelin concentrations than the UF heifers that continued to ovulate. In the current experiment, long-term undernutrition elicited ghrelin responses similar to those reported for shorter durations of nutrient restriction in cattle and other ruminants. These results demonstrate that plane of nutrition is a chronic regulator of plasma ghrelin concentrations, and that these concentrations can be experimentally manipulated in postpubertal heifers for up to 8 wk with no evidence of an adaptive response.Journal of Dairy Science 08/2013; · 2.57 Impact Factor