Remedios T. Mabayo

Cholinergic factors are not involved in the delayed diet passage from the crop of chicks given medium chain triacylglycerol.

The role of cholinergic mechanisms in the delayed food passage from the crop induced by medium chain triacylglycerol was investigated in the young chicken. Vagotomy altered the crop emptying of chicks given dietary long chain triacylglycerol, but did not alter it in chicks given dietary medium chain triacylglycerol. On the contrary, denervation in the cranial rete and lateral commissure of the gizzard further inhibited the food passage induced by medium chain triacylglycerol. Administration of cisapride, which induces acetylcholine release from the myenteric nerves, and atropine, a muscarinic cholinergic antagonist, both delayed crop emptying of chicks given medium chain triacylglycerol. These results demonstrate that cholinergic factors are not involved in the delayed forward movement of the food containing medium chain triacylglycerol from the crop of chicks.

Feeding behavior in rats fed diets containing medium chain triglyceride

The effect of dietary medium chain triglyceride (MCT) on short-term food intake was compared with the effect of long chain triglyceride (LCT) in rats. Corn oil and glyceryl tricaprylate were used as LCT and MCT sources, respectively. Rats were given diets containing 200 g MCT/kg diet (MCT diet), 100 g MCT + 100 g LCT/kg diet (ML diet), or 200 g LCT/kg diet (LCT diet) in Experiment 1. Cumulative food intake was determined every h for the first 12 h, then at 2-h intervals thereafter during the subsequent 12 h. As early as 1 h after feeding, cumulative food intake significantly decreased in MCT-fed animals in a dose-dependent fashion. In Experiment 2, rats were given a choice between MCT and LCT diets for 1 h to confirm whether or not the palatability of diets was influenced by dietary fat sources. There was no difference in food intake between the two diets. In Experiment 3, the responsibility of endogenous cholecystokinin (CCK) for the difference in food intake between the two diets was investigated for 6 h by using a CCK-A receptor antagonist, Devazepide (DVZ, 1 mg/kg b. wt.). Food intake in the MCT diet and also in the LCT diet was improved by DVZ. It is concluded that the satiety, but not the palatability, is affected by carbon chain length in dietary triglyceride sources, although the responsibility of endogenous CCK is very small.

The role of olfaction in oil preference in the chicken

The role of olfaction on the preference of diets containing 20% medium-chain (MCT) or long-chain triacylglycerol (LCT) was investigated in the chicken. Olfactory bulbectomized, sham-operated (Sham) or intact (Intact) birds were offered a choice between LCT or MCT diet and food intake was measured over a short time period. Intact and Sham groups showed a significant preference for LCT over MCT diet, but olfactory-bulbectomized chickens lost the preference for LCT over MCT. The bilateral cutting of the olfactory nerves confirmed the results taken in olfactory bulbectomy. It is concluded that olfaction plays a major role in the preference of diets containing MCT or LCT in chickens.

Effect of dietary medium chain triglyceride on protein and energy utilisation in growing chicks

1. Protein, fat and energy retentions of chicks fed on diets containing medium chain triglyceride (MCT) and long chain triglyceride (LCT), at 100 and 200 g fat/kg diet, were investigated. Maize oil was used as the LCT source. The MCT used was glyceryl tricaprylate. 2. Body weight gain and food intake were decreased with the diets containing MCT and these effects were greater at the higher fat concentration. Protein retention was also reduced by dietary MCT, although the efficiency of protein utilisation (protein retained/protein intake) was not altered. 3. The values for fat and energy retentions were significantly lower in the chicks fed on the MCT-supplemented diets than in those receiving the LCT-containing diets. Dietary ME values and efficiencies for energy utilisation (energy retained/ME intake) were also reduced by dietary MCT.

Feeding behaviour in chickens given diets containing medium chain triglyceride

1. The effect of dietary medium chain triglyceride (MCT) on short-term food intake was compared with the effect of long chain triglyceride (LCT) in chickens. Maize oil was used as the LCT while glyceryl tricaprylate (C 8) and glyceryl tricaprate (C 10) were used as MCT. Cumulative food intake was determined during the 6 h after the start of feeding. 2. Chicks were given diets containing 200 g C 8/kg diet, 200 g C 10/kg diet or 200 g LCT/kg diet in experiment 1. As early as 30 min after feeding, cumulative food intake in both MCT-supplemented diets decreased significantly compared with the diet containing LCT. 3. To determine if endogenous cholecystokinin (CCK) was responsible for the decrease in food intake caused by MCT, birds were injected with the CCK-A receptor antagonist devazepide (DVZ, 1 mg/kg BW) before diet presentation. DVZ had no effect on food intake with either LCT- or MCT-supplemented diets. 4. In experiment 3, chicks were given a choice between either diets containing LCT and C 8, LCT and C 10, or C 8 and C 10 to confirm whether or not the palatability of the diets was influenced by the dietary fat sources. There was no difference in food intake between C 8 and C 10-supplemented diets. However, chicks preferred the LCT-supplemented diet compared with either of the diets containing MCT.

Interactions between medium-chain and long-chain triacylglycerols in lipid and energy metabolism in growing chicks

The combined effects of dietary medium-chain triacylglycerols (MCT) and long-chain triacylglycerols (LCT) on lipid and energy utilization in chicks were investigated. Corn oil was used as the LCT source, and trioctanoin (8∶0) was used as the MCT source. The efficiency of dietary energy utilization (such as metabolizable energy values and fat and energy retention) decreased linearly as the level of MCT increased, but the efficiency of dietary protein utilization (protein retained per protein consumed) was not affected in a consistent manner. Fecal saturated and monounsaturated fatty acid composition was dependent on the dietary fatty acid composition, whereas fecal linoleic acid content was not. It is concluded that dietary MCT and LCT influence each other to some degree, with respect to protein and lipid metabolism in chicks. Moreover, in most cases, the nutritional characteristics of each triacylglycerol, including food efficiency and fat and energy retention, are independent of each other in growing chicks.

EFFECTS OF PARTIALLY HYDROLYSED GUAR GUM ON FEEDING BEHAVIOUR AND CROP EMPTYING RATE IN CHICKS

1. The effects of partially hydrolysed guar gum (PHGG) or intact guar gum (GG) on feeding behaviour and crop emptying rate in growing chicks were investigated. 2. Several combinations of dietary PHGG and GG at 50 g per kg diets were prepared for a feed intake experiment. Birds (1 7-d-old) were given diets for 3 h after 16 h fasting, and food consumption was measured at 1 h intervals. The food intake rapidly decreased as the dietary GG content increased even at 1 h after feeding. 3. The rate of food passage from the crop was also investigated with birds (20-d-old after 16 h fasting. Birds were tube-fed diets having several ratios of dietary PHGG and GG. After 1 h of feeding, the diet remaining in the crop was measured after drying. The crop emptying rate decreased linearly as dietary PHGG concentration decreased. 4. The present study suggests that partial hydrolysis of dietary GG improve both feeding behaviour and food passage from the crop in growing chicks.

Inhibition of food passage by omeprazole in the chicken.

The effect of omeprazole, a proton pump inhibitor, on the forward passage of the crop contents of chicks receiving 20% medium chain or long chain triacylglycerol was studied. Medium chain triacylglycerol significantly delayed the crop emptying of chicks compared with long chain triacylglycerol. Omeprazole also significantly inhibited passage from the crop of the long chain triacylglycerol meal. Application of omeprazole induces achlorhydria and consequently hypergastrinemia but chicken gastrin lower than 100 nmol/kg did not delay crop emptying. The addition of hydrochloric acid (HCl) to the diet reversed the action of omeprazole on the crop emptying of chicks. We conclude, then, that omeprazole delayed the crop emptying in chicks as a consequence of inhibition of acid secretion, although the mediator is not gastrin.

Improvement of dietary protein utilisation in chicks by medium chain triglyceride.

1. To improve the influence of variation of ME intake, an experiment was carried out using equalized feeding to investigate the comparative effects on protein and energy utilisation in chicks of diets containing medium chain triglyceride (MCT) and long chain triglyceride (LCT). Experimental diets were given at 3 different food intakes, namely, 100, 120 or 147 g/bird/10 d. The diets contained MCT or LCT on an isoenergetic basis. Maize oil and caprylic acid triglyceride respectively, were used as LCT and MCT sources. 2. Body weight gain and food efficiency of chicks significantly increased with the supplement of dietary MCT compared with dietary LCT at all food intakes. Protein retention and the efficiency of protein utilisation (protein retained/protein intake) at all food intakes also significantly increased with dietary MCT, while body fat and fat retention were significantly reduced. Chicks fed the LCT-supplemented diet, on the other hand, had a lower protein retention, but significantly higher fat retention. The value for energy retention and the efficiency of energy utilisation (energy retained/ME intake) were not significantly different between MCT- and LCT-supplemented diets. 3. It was concluded that supplementing MCT to the chick diet would improve body weight gain and protein utilisation while regulating fat deposition compared to the LCT supplemented diet, under equalized feeding conditions.

Cholestyramine Alters the Lipid and Energy Metabolism of Chicks Fed Dietary Medium- or Long-Chain Triacylglycerol

The effects of cholestyramine, a bile acid binding polymer, on the lipid and energy metabolism of chicks given dietary medium-chain triacylglycerol (MCT) or long-chain triacylglycerol (LCT) were investigated. Chicks (from 8 to 17 days of age) were fed diets containing MCT or LCT at 200 g oil/kg diet with or without 2% cholestyramine under equalized feeding conditions. An adjusted LCT diet was formulated in order to supply another group with daily nutrients and dietary metabolizable energy (ME) equal to MCT groups, except for corn starch. ME intakes of chicks given MCT or LCT diets were reduced by cholestyramine; consequently, fat and energy retention was reduced, though the reduction was more drastic in chicks fed LCT. This was caused by a change in amounts of the fecal excretion of fat and bile acids. Cholestyramine enhanced the excretion of octanoic acid (8∶0) in the feces, which suggests that bile acids are needed for 8∶0 absorption. Cholestyramine affects the utilization of dietary MCT and LCT by lowering fat and energy retention in chicks. However, the effect of cholestyramine on MCT utilization was smaller than its effect on utilization of LCT.