Typescript (photocopy). / Digitized by Kansas Correctional Industries

Digitized by Kansas Correctional Industries

No description available.

No description available.

No description available.

No description available.

No description available.

No description available.

The objective of this work was to define the effects of dietary energy intake on broiler fat deposition and metabolism. Fatty broilers are one of the major problems in the broiler industry. The effects of changing calorie to protein (Cal/Pr) ratios, and the addition of cellulose or dried distiller's byproduct (DDBP) in the diet, on abdominal fat deposition, liver lipogenesis and glucose oxidation and broiler performance indicated that the mean body weight of broilers fed narrower Cal/Pr ratio diets (124 and 143 for starter and grower, respectively) were lower (P<.01) than broilers fed diets with mid-Cal/Pr ratios (138 and 160) and wide Cal/Pr ratios (147 and 171). Feed conversion was better (P<.01) for broilers fed the diet with wide Cal/Pr ratio than the broilers fed the diet with narrow Cal/Pr ratio. Abdominal fat deposition increased (P<.001) with wide Cal/Pr ratio than narrow Cal/Pr ratio. No significant differences were found in in vitro liver lipogenesis and glucose oxidation when Cal/Pr ratio was widened. Mean body weight, feed conversion and abdominal fat levels of broilers fed 5% cellulose or 10% DDBP diets were not different when compared to broilers fed diets with the same Cal/Pr ratio without these two feed ingredients. The time-course of the deposition of abdominal fat fitted a negative exponential growth curve. The data also indicated that the highest potential for abdominal fat deposition was during the first two weeks of age. When the feed intakes of broilers were restricted for a 6 day period beginning at 1, 2, 3 and 4 weeks of age, the feed efficiencies of all the restricted broilers were significantly improved compared with broilers fed ad libitum. No significant differences were observed in mean body weight between the different treatments. The percentage of abdominal fat in broilers restricted-fed starting either at 1 or 2 weeks old for a 6-day period were lower (P<.05) than broilers fed ad libitum. Feed restriction from days 7 to 12 reduced the adipocyte size but not the number. Feed restriction decreased (P<.05) lipogenesis at 2 and 8 weeks of age. No significant effects were found in lipolysis between the restricted and ad libitum-fed broilers. These studies demonstrate that early feed restriction (days 7 to 12) reduced abdominal fat deposition which is attributed to the reduction in the adipocyte size. Smaller size adipocyte resulted from decreased activity of lipogenesis. / Graduation date: 1991

Spexin (SPX), also called neuropeptide Q (NPQ), is a novel neuropeptide discovered recently using the bioinformatic approach. Except for mammals, SPX has not been reported in lower vertebrates including fish and amphibians. Following its discovery, the biological functions of this peptide in both higher and lower vertebrates are still largely unknown. To examine the structure and functions of SPX in fish model, molecular cloning of goldfish SPX has been performed and found to be highly comparable to its mammalian counterparts. In goldfish, broad expression of SPX transcripts has been found in various tissues. In vivo feeding studies have revealed that SPX mRNA levels in the telencephalon, optic tectum and hypothalamus of goldfish brain could be elevated by food intake. Brain injection of goldfish SPX, however, inhibited both basal and NPY- and orexin-induced feeding behaviour and food consumption. Similar treatment has also reduced transcript expression of NPY, AGRP and apelin with concurrent rises in CCK, CART, POMC, MCH and CRH mRNA levels in different brain areas examined. The differential effects of goldfish SPX on NPY, CCK and MCH transcript expression could also be noted in vitro in goldfish brain cell culture. In mice, SPX has been also found to be expressed within the brain-gut axis, including the stomach and specific neuronal subpopulations within the hypothalamus, including the ARC, PVN, DMN, and VMN. Similar to goldfish, feeding has shown to affect SPX mRNA and protein expression. Fasted animals have lower SPX mRNA in the stomach, and lower SPX protein levels in the serum and glandular stomach; the opposite effects have been noted in ad libitumfed animals. Both IP and ICV injection of SPX could produce a short-term feeding inhibitory effect. Furthermore, ICV administration of SPX could also downregulate hypothalamic expression of NPY, NPY5R, AGRP, and GHSR mRNA, and upregulate leptin receptor and MC4R gene expression concurrently. Taken together, these findings suggests that SPX may act as a satiety factor in vertebrate species. Apparently, SPX expression could be induced by feeding and the neuropeptide could act centrally to inhibit feeding by differentially regulating orexigenic and anorexigenic signals within the CNS. / published_or_final_version / Biological Sciences / Master / Master of Philosophy