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To evaluate the prebiotic potential and intestinal fermentation products of wheat bran-derived arabinoxylooligosaccharides (AXOS) in relation to their structure, 5 preparations with structurally different AXOS were included (~4% wt:wt) in rat diets that mimicked the average Western human diet composition. Xylooligosaccharides (XOS), fructooligosaccharides (FOS), and inulin were used as references. The observed effects mainly depended on the average degree of polymerization (avDP) of the AXOS preparations. The AXOS and XOS preparations with a low avDP ([less than or equal to] 3) resulted in increased colonic acetate and butyrate production and boosted bifidobacteria concentrations in the cecum, but did not significantly lower the concentrations of branched SCFA, which are considered to be markers of protein fermentation by intestinal microbiota. In contrast, an AXOS preparation with a higher avDP (61) effectively suppressed branched SCFA concentrations and thus tipped the balance away from protein fermentation. However, it neither increased colonic butyrate concentrations nor stimulated cecal bifidobacteria development. Two AXOS preparations with a similar avDP (12 and 15) but different average degrees of arabinose substitution (avDAS) (0.69 and 0.27) affected the measured intestinal characteristics similarly, suggesting that the influence of the avDAS was apparently limited and possibly overshadowed by that of the avDP. Among those tested, an AXOS preparation with an avDP of 5 and an avDAS of 0.27 exhibited the best combination of desirable effects on gut health characteristics. Compared with this optimal AXOS preparation, FOS and inulin resulted in similar bifidogenic effects with increased production of colonic acetate (inulin) but not of butyrate. These new insights into the structure-activity relation of AXOS open up new perspectives for the production and application of AXOS preparations with optimized prebiotic and fermentation properties.

Cerulenin, a natural fatty acid synthase (FAS) inhibitor, and its synthetic analog C75 are hypothesized to alter the metabolism of neurons in the hypothalamus that regulate ingestive behavior to cause a profound decrease of food intake and an increase in metabolic rate, leading to body weight loss. The bulk of data exclusively originates from mammals (rodents); however, such effects are currently lacking in nonmammalian species. We have, therefore, addressed this issue in broiler chickens because this species is selected for high growth rate and high food intake and is prone to obesity. First, we demonstrate that FAS messenger and protein are expressed in the hypothalamus of chickens. FAS immunoreactivity was detected in a number of brain regions, including the nucleus paraventricularis magnocellularis and the nucleus infundibuli hypothalami, the avian equivalent of the mammalian arcuate nucleus, suggesting that FAS may be involved in the regulation of food intake. Second, we show that hypothalamic FAS gene expression was significantly (P < 0.05) decreased by overnight fasting similar to that in liver, indicating that hypothalamic FAS gene is regulated by energy status in chickens. Finally, to investigate the physiological consequences of in vivo inhibition of fatty acid synthesis on food intake, we administered cerulenin by intravenous injections (15 mg/kg) to 2-wk-old broiler chickens. Cerulenin administration significantly reduced food intake by 23 to 34% (P < 0.05 to P < 0.0001) and downregulated FAS and melanocortin receptors 1,4, and 5 gene expression (P < 0.05). However, the known orexigenic (neuropeptide Y, agouti gene-related peptide, orexin, and orexin receptor) and anorexigenic (pro-opiomelanocortin and corticotropin-releasing hormone) neuropeptide mRNA levels remained unchanged after cerulenin treatment. These results suggest that the catabolic effect of cerulenin in chickens may be mediated through the melanocortin system rather than the other neuropeptides known to be involved in food intake regulation. genotype; fasting; hormones; metabolites

The aim of this study was to investigate the hormonal regulation of the avian homolog of mammalian uncoupling protein (avUCP) by studying the impact of thyroid hormones and insulin on avUCP mRNA expression in chickens (Gallus gallus). For 3 wk, chicks received either a standard diet (control group), or a standard diet supplemented with triiodothyronine ([T.sub.3]; T3 group) or with the thyroid gland inhibitor methimazole (MMI group). A fourth group received injections of the deiodinase inhibitor iopanoic acid (IOP group). During the 4th wk of age, all animals received two daily injections of either human insulin or saline solution. The results indicate a twofold overexpression of avUCP mRNA in gastrocnemius muscle of T3 birds and a clear downregulation (-74%) in MMI chickens compared with control chickens. Insulin injections had no significant effect on avUCP mRNA expression in chickens. This study describes for the first time induction of avUCP mRNA expression by the thermogenic hormone [T.sub.3] in chickens and supports a possible involvement of avUCP in avian thermogenesis. thyroid hormones; thermogenesis; muscle

We conducted two experiments with preruminant calves weighing 80 to 240 kg to study the long-term nutritional regulation of circulating IGF-I, thyroxine ([T.sub.4]), and triiodothyronine ([T.sub.3]). The two experiments were similar in design but were performed with calves of two live weight ranges: 80 to 160 kg (Exp. 1) and 160 to 240 kg (Exp. 2). In each experiment, 36 calves were allocated to one of 12 dietary treatments, which consisted of six protein intake levels at each of two energy intake levels. Digestible protein intakes ranged between .90 and 2.72 g N[center dot][BW.sup.-.75][center dot][d.sup.-1] in Exp. 1 and between .54 and 2.22 g N[center dot][BW.sup.-.75][center dot][d.sup.-1] in Exp. 2. The energy intake levels were kept constant on a protein-free basis; increased energy intakes were realized by increasing energy intake from fat and carbohydrates in a fixed ratio. The digestible protein-free energy intakes were 663 and 851 kJ[center dot][BW.sup.-.75][center dot][d.sup.-1] in Exp. 1 and 564 and 752 kJ[center dot][BW.sup.-.75][center dot][d.sup.-1] in Exp. 2. Blood samples were taken 5 to 6 h after feeding once every 14 d until the calves reached their target weight. In both experiments, plasma IGF-I and [T.sub.4] concentrations increased with increasing protein intake (P < .01), but they were unaffected by protein-free energy intake (P > .10). In both experiments, plasma [T.sub.3] levels were markedly higher at the high protein-free energy intake level (P < .01) and increased slightly with increasing protein intake in Exp. 1 (P = .19) and Exp. 2 (P < .01). Results of these experiments suggest the involvement of IGF-I in the response of protein deposition to increased protein intakes and the involvement of the active thyroid hormone [T.sub.3] in the response of protein deposition to increased protein-free energy intakes. Key Words: Veal Calves, Protein Intake, Energy Intake, Insulin-Like Growth Factor, Triiodothyronine, Thyroxine

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Abstract Background Muscle growth depends on the fusion of proliferate satellite cells to existing myofibers. We reported previously that 0–14 day intermittent feeding led to persistent retardation in myofiber hypertrophy. However, how satellite cells respond to such nutritional insult has not been adequately elucidated. Results One-day-old broiler chicks were allocated to control (Con, ad libitum feeding), intermittent feeding (IF, feed provided on alternate days) and re-feeding (RF, 2 days ad libitum feeding after 12 days of intermittent feeding) groups. Chickens were killed on Day 15 and satellite cells were isolated. When cultured, satellite cells from the IF group demonstrated significant retardation in proliferation and differentiation potential, while RF partly restored the proliferation rate and differentiation potential of the satellite cells. Significant up-regulation of insulin like growth factor I receptor (IGF-IR) (P<0.05) and thyroid hormone receptor α (TRα) (P<0.05), and down-regulation of growth hormone receptor (GHR) (P<0.01) and IGF-I (P<0.01) mRNA expression was observed in freshly isolated IF satellite cells when compared with Con cells. In RF cells, the mRNA expression of IGF-I was higher (P<0.05) and of TRα was lower (P<0.01) than in IF cells, suggesting that RF restored the mRNA expression of TRα and IGF-I, but not of GHR and IGF-IR. The Bax/Bcl-2 ratio tended to increase in the IF group, which was reversed in the RF group (P<0.05), indicating that RF reduced the pro-apoptotic influence of IF. Moreover, no significant effect of T3 was detected on cell survival in IF cells compared with Con (PP<0.05) cells. Conclusions These data suggest that early-age feed restriction inhibits the proliferation and differentiation of satellite cells, induces changes in mRNA expression of the GH/IGF-I and thyroid hormone receptors in satellite cells, as well as blunted sensitivity of satellite cells to T3, and that RF partially reverses these effects. Thus, a moderate nutritional strategy for feed restriction should be chosen in early chick rearing systems.