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.
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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
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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; · 2.55 Impact Factor
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ABSTRACT: The present study investigated the effects of dietary fat sources and feeding level on performance, adipose tissue fatty acid profile and lipid metabolism related genes expression in finisher pigs. A total of 128 finisher pigs [average initial body weight (BW), 81.2 ± 0.322 kg] were allotted to 4 treatments on the basis of BW. There were 4 replicates in each treatment with 8 pigs per replicate. Pigs were fed diets containing 50.0 g/kg linseed oil or animal fat, either ad libitum or restricted (15.0% less) in 2 × 2 factorial arrangement for 28 d. Dietary fat source did not affect (P > 0.05) average daily gain (ADG), average daily feed intake (ADFI) and gain to feed ratio (G:F). The ADG and ADFI of pigs fed ad libitum were greater (P < 0.05) than that of restricted fed pigs. The G:F of restricted fed pigs was greater (P < 0.05) than that of ad libitum fed pigs. Pigs fed 50.0 g/kg linseed oil diet had greater (P < 0.05) concentrations of adipose tissue polyunsaturated fatty acids (PUFA) like linoleic acid and α-linolenic acid than that of pigs fed 50.0 g/kg animal fat diet. Saturated fatty acids (SFA) like palmitic acid (P < 0.05), palmetoleic acid and steric acid (P < 0.10) concentrations of adipose tissue were greater in pigs fed animal fat than pigs fed linseed oil. However, adipose tissue fatty acids concentrations were not affected (P > 0.05) by feeding level. Adipose tissue expression of acetyl CoA carboxylase (ACC) and fatty acid synthase (FAS) were down-regulated, whereas expression of lipoprotein lipase (LPL) and hormone sensitive lipase (HSL) were up-regulated in finishing pigs fed restricted diets. However, fat sources of diet had no effects (P > 0.05) on expression of ACC, FAS, LPL and HSL genes. Results obtained in the present study indicates that dietary inclusion of 50.0 g/kg linseed oil have potential to improve the adipose tissue PUFA contents, and 15.0% feed restriction resulted into down-regulation of ACC and FAS and up-regulation of LPS and HSL expression in adipose tissue.Animal Feed Science and Technology 10/2014; · 2.09 Impact Factor