Biomedical subjects

D M Denbow

Publications and source records attributed to D M Denbow.

At least 19 recordsLinked to original sources

PubMed1998

Soybeans transformed with a fungal phytase gene improve phosphorus availability for broilers.

Male broilers (n = 416) were used to compare the efficacy of providing dietary phytase either as a commercial supplement or as a recombinant protein in transformed soybean. From 7 to 21 d of age, broilers were fed a basal diet containing 0.20% nonphytate P (nP) with additional supplementation by fungal phytase as Natuphos or as raw transformed soybeans expressing recombinant phytase at 400, 800, or 1,200 U/kg. For comparison, broilers were also fed the basal diet containing 0.08, 0.16, or 0.24 added nP. The basal diet was fed as the negative control. Diets were consumed ad libitum as a mash. All excreta were collected from each pen from 18 through 20 d of age, and the birds were killed at 21 d of age. Supplementing the basal diet with nP linearly increased body weight gain, feed efficiency, feed intake, toe ash weight and percentage, and tibia shear force and energy. Phosphorus digestibility decreased linearly as nP level increased, but P excretion increased. Dietary phytase linearly increased growth rate, feed intake, toe ash weight and percentage, tibia shear force and energy, and P digestibility, whereas excretion was decreased. Except for P digestibility, there was no difference in efficacy of responses for performance, bone mineralization, and P excretion between the two sources of phytase. It appears from this study that phytase can improve growth performance of broilers fed low nP diets when provided either as a commercial supplement or in the form of transformed seeds.

6-Phytase↗

PubMed1997

Utilization of phytate phosphorus and calcium as influenced by microbial phytase, cholecalciferol, and the calcium: total phosphorus ratio in broiler diets.

The present study was performed to evaluate the potential of microbial phytase and cholecalciferol (D3) for improving the utilization of phytate P and Ca and the influence of the Car:total (t) P ratio in a corn-soybean meal diet fed to broilers from hatch to 21 d of age. A 4 x 4 x 2 factorial arrangement of treatments was used: 1.1, 1.4, 1.7, and 2.0:1 Ca:tP ratio; 0, 300, 600, and 900 U of phytase/kg of diet; and 66 and 660 micrograms of D3/kg of diet. Another four treatments were included: the four Ca:tP ratios with 6,600 micrograms of D3 addition, but without phytase. Added phytase linearly increased (P < 0.001) BW gain, feed intake, toe ash content, and P and Ca retention; these measurements were negatively influenced by widening the dietary Ca:tP ratio, and synergetically improved by addition of D3. Increasing the Ca:tP ratio decreased (P < 0.001) all measurements in the presence or absence of supplemental phytase and D3. Dietary Ca:tP ratios between 1.1:1 to 1.4:1 appears critical to the efficient use of supplemental phytase and D3 for improving the utilization of phytate P and Ca. The addition of D3 in corn-soybean meal diets indicated a potential for improving the utilization of phytate P and Ca by increasing Ca and P retention by about 5 to 12% in birds, which led to an increase in toe ash content (P < 0.03). The enhanced phytate P utilization (P < 0.001) was also observed during assay of the phytase activity in the mixed diets with an addition of D3 and without added phytase. In summary, the findings of this study suggested that phytase, D3, and Ca:tP are important factors in degrading phytate and improving phytate P and Ca utilization in broilers.

6-Phytase↗

PubMed1996

Response of broilers to graded levels of microbial phytase added to maize-soyabean-meal-based diets containing three levels of non-phytate phosphorus.

Male 1-d-old broilers (n 920) were given 0, 200, 400, 600, 800, 1000 and 1200 U microbial phytase/kg diet in combination with 2.0, 2.7 or 3.4 g non-phytate P (nP)/kg or 4.0, 5.1 or 5.8 g total P (tP)/kg in a 21 d trial to assess the effectiveness of phytase in a maize-soyabean-meal diet. In addition to the above twenty-one diets, a positive control P diet supplied 4.5 g nP/kg, 6.9 g tP/kg and 10 g Ca/kg. The basal diet contained 230 g crude protein/kg, 8.8 g Ca/kg, 4.4 g tP/kg and 2.0 g nP/kg. Defluorinated phosphate and limestone were used to supply P and Ca. A Ca:tP ratio of 2:1 was maintained except in the positive control diet which had a ratio of 1.45:1. Phytase additions linearly increased (P < 0.01) body-weight (BW) gain, feed intake, toe ash percentage, and apparent retention (% of intake) or total amount (g/bird) of retained Ca and P, and linearly decreased (P < 0.01) P excretion (g/kg of DM intake) at each level of nP with the magnitude of the response inversely related to the level of nP. Above-normal mortality was only observed in the group receiving 2.0 g nP/kg diet without phytase. Adding nP linearly increased (P < 0.01) BW gain, feed intake, toe ash percentage, Ca retention, total amount (g/bird) of P retained, and P excretion, and linearly decreased (P < 0.01) apparent retention (%) of P. Derived linear and non-linear equations for BW gain and toe ash percentage at the two lower nP levels, 2.0 and 2.7 g/kg, were used to calculate P equivalency values of microbial phytase. The results show that 939 U microbial phytase is equivalent to 1 g P from defluorinated phosphate in broilers fed on maize-soyabean-meal diets. The amount of P released per 100 U phytase decreased as the total amount of phytase increased.

6-Phytase↗

PubMed1996

Case report: neurochemical, physiological, and behavioral effects of bright light therapy on a cortically blind patient.

The present study evaluated the effects of bright light therapy on a patient with cortical blindness. Behavioral indices of functioning included the appraisal of mood, fatigue, appetite and orientation. Physiological measures assessed were blood pressure and temperature. Blood serum samples were analyzed for 5-HIAA and norepinephrine (NE). For the control and follow-up, the patient was exposed to 30 minutes of red light (300-lux), and thirty minutes of white light (10,000-lux) was used for treatment. High-pressure liquid chromatography analyses of blood serum samples revealed no change in serotonin (5-HT). However, an increase in blood NE was indicated following light treatment (red light: 12.7 ng/ml, white light: 43.5 ng/ml and, red light: 27.5 ng/ml). Analysis of data revealed significant differences in baseline and treatment scores for 4 of the outcome measures.

Adult↗

PubMed1996

Phosphorus equivalence of microbial phytase in turkey diets as influenced by calcium to phosphorus ratios and phosphorus levels.

Male day-old turkey poults (n = 768) were fed 0, 300, 600, or 900 U of phytase/kg of a corn-soybean diet in combination with four Ca:total P (tP) ratios of 1.1, 1.4, 1.7, and 2.0:1, and two levels of nonphytate P (nP) of 0.27 and 0.36% in a 21-d trial. Dietary Ca:tP ratios were obtained by varying defluorinated phosphate and limestone at the expense of cornstarch. The calculated dietary percentage of phytate P was 0.266 for all diets. Phytase additions linearly increased (P < 0.05) BW gain, feed intake, gain:feed, toe ash content, and apparent retentions of Ca and P at each Ca:tP ratio and nP level, but the response was influenced by dietary Ca:tP ratios and P levels. The detrimental effect (P < 0.02) of widening the Ca:tP ratio was observed for all measurements at each phytase and P level, and was greatest at lower phytase and P levels. Widening the Ca:tP ratio from 1.4 to 2.0 decreased the phytase efficacy by 7.4 and 4.9%, respectively, for 0.27 and 0.36% nP diets, which was close to the decrease in the phytase activity in vitro by 7.5 and 6.7%, respectively. The largest responses to supplemental phytase were achieved when poults were fed diets with 600 and 900 U of phytase/kg diet, respectively, for 0.36 and 0.27% nP, and for Ca:tP ratios ranging from 1.1 to 1.4:1. Second-order translog equations were generated for the phytase, Ca:tP ratio, and P effect, and nonlinear and linear equations for the phytase and Ca:tP ratio effect. Based on an assessment for the R2 and P values of equations, BW gain, feed intake, toe ash content, and P retention were sensitive measurements of the response to phytase addition. Equivalent equations were developed to determine the P equivalency of supplemental phytase. About 652 and 963 U of phytase were equivalent to 1 g nP, respectively, for 0.27 and 0.36% nP diets in turkey poults from hatch to 21 d of age.

6-Phytase↗

PubMed1996

Improving phytate phosphorus availability in corn and soybean meal for broilers using microbial phytase and calculation of phosphorus equivalency values for phytase.

Two experiments were conducted to determine the effectiveness of Natuphos phytase for improving P availability of soybean meal-based semipurified diets (SP, Experiments 1 and 2) and corn-soybean meal-based diets (CS, Experiment 2) fed to broilers (1 to 21 d). There were 360 and 288 birds fed the SP diets in Experiments 1 and 2, respectively, and 288 birds were fed the CS diets in Experiment 2. Phosphorus equivalency values for phytase were calculated. The basal diets were formulated to contain 0.27% nonphytate P (nP); the SP basal diet contained 0.45% total P (tP) that included 0.17% P as defluorinated phosphate; the CS basal diet contained 0.51% tP that contained 0.12% P as defluorinated phosphate. Both basal diets were supplemented with defluorinated phosphate to provide 0.36, 0.45, of 0.54% nP or with 350, 700, or 1,050 U of phytase/kg diets. Supplementing defluorinated phosphate and phytase linearly increased BW gain (P < 0.001), feed intake (P < 0.001), and percentage ash of dried toes (P < 0.01). Phytase addition increased apparent retention of P (P < 0.02), Ca (P < 0.005 in Experiment 2), and N (P <0.06 in Experiment 2 for CS), increased apparent digestibility of DM (P < 0.04), and linearly decreased (P <0.005) P excretion. In comparison to the 0.45% np diet, P excretion was reduced 42 to 51% by addition of phytase. The addition of defluorinated phosphate linearly decreased apparent retention of P (P < 0.02) and Ca (P < 0.005 in Experiment 2), and increased P excretion (P < 0.007). The average of released P by phytase calculated by solving nonlinear or linear response equations of P and phytase levels for SP diets in Experiments 1 and 2 gave a P equivalency value 1 g P = 1,146 U of phytase. The P equivalency value for CS diets fed only in Experiment 2 was 785 U of phytase = 1 g P as defluorinated phosphate. These studies show that microbial phytase is effective for improving P availability and for decreasing P excretion. Added phytase can also increase Ca and N retention.

6-Phytase↗

PubMed1996

Supplemental microbial phytase improves zinc utilization in broilers.

Day-old male broilers (n = 384) were used in a 21-d trial to investigate the effect of microbial phytase on the retention and utilization of Zn. A corn-soybean isolate basal diet containing 20 ppm Zn was fed alone and supplemented with 5, 10, or 20 ppm Zn as ZnSO4.7H2O or with 150, 300, 450, or 600 U of phytase/kg of diet. Total excreta were collected during Days 18 to 20. Toe, tibia, and liver samples were taken at the end of the experiment. Adding Zn and phytase to the low Zn basal diet linearly increased BW gain and feed intake of broilers (P < 0.01). The gain to feed ratio was not changed by adding Zn but was decreased by adding phytase (P < 0.01). The amount of DM retained was linearly increased by adding Zn and phytase (P < 0.10), but DM retained as a percentage of intake was only increased by adding Zn (P < 0.05). The amount of Zn retained per bird was linearly improved by adding Zn and phytase (P < 0.01). Zinc retained as a percentage of intake was linearly decreased by adding Zn but was linearly increased by adding phytase (P < 0.10). Ash percentage of toe and tibia were not affected by adding Zn but were linearly improved by adding phytase (P < 0.10); however, the amount of ash in toe or tibia was increased by Zn (P < 0.05) and phytase (P < 0.01 for toe; not significant for tibia). The concentration and amount of Zn in toe and tibia were linearly increased by adding Zn and phytase (P < 0.001). The concentration of Zn in liver increased by adding Zn (P < 0.10) but was not significantly improved by adding phytase. The amount of Zn retained in liver was linearly improved by adding Zn and phytase (P < 0.05). Nonlinear or linear response equations of the effects of Zn and phytase levels were generated and used to calculate the Zn equivalency values. The average function of Zn equivalency values (Y, milligrams per kilogram) of microbial phytase (X, units per kilogram of diet) was developed: Y = 0.20 + 0.0082X. The results indicate that approximately 0.9 mg of Zn was released per 100 U of phytase over the range of 150 to 600 U of phytase.

6-Phytase↗

PubMed1996

Effects of supplemental phytase and phosphorus on histological and other tibial bone characteristics and performances of broilers fed semi-purified diets.

Two trials with day-old chicks were conducted to investigate the effects of supplemental phytase (Natuphos) on histological, mechanical, and chemical properties of tibia, and performances of broilers fed semi-purified diets containing soybean meal as the only organic P source [0.11% nonphytate P (nP)]. Dietary treatments in Trial 1 were: 1) 0.20% nP, 2) Diet 1 + 800 U of phytase/kg of diet, 3) 0.27% nP, 4) Diet 3 + 600 U of phytase, 5) 0.34% nP, 6) Diet 5 + 400 U of phytase. Supplemental phytase and inorganic P increased tibial length (P < 0.01), shear force (P < 0.001), shear stress (P < 0.05), ash content (P < 0.001), and BW gain and feed intake (P < 0.001) during Trial 1. The hypertrophic zone width at the proximal end of the tibia was decreased (P < 0.05), and the tibial width (P < 0.05) of the long axis of the tibia was increased by the phytase and P supplementation. Supplemental phytase enlarged the cartilaginous and proliferative zones of the tibial proximal end (P < 0.05), and an increase in nP levels produced similar effects. Supplementation of phytase and P also tended to improve the orderliness of development and arrangement of cartilage and bone cells. Dietary treatments in Trial 2 were: 1) 0.27% nP, 2) Diet 1 + 350 U of phytase, 3) Diet 1 + 1,050 U of phytase, 4) 0.45% nP, 5) 0.54% nP, 6) Diet 5 + 1,050 U of phytase. Broilers fed diets containing relatively high levels of nP and phytase supplementation in Trial 2 gave results similar to those observed in Trial 1. Marked improvements (P < 0.05) in the ash content, shear force, shear stress, length of tibia, BW gain, and feed intake, and reduced hypertrophic zone width were achieved for broilers fed the P-deficient diet supplemented with phytase. Also, supplemental phytase tended to increase the width of cartilaginous and proliferative zones, to increase trabecular bone density, and to improve the orderliness of development and mineralization of cartilage and bone cells. In summary, supplementing a low-nP diet with inorganic P or phytase resulted in similar beneficial effects on bone development.

6-Phytase↗

PubMed1996

Effect of microbial phytase on nitrogen and amino acid digestibility and nitrogen retention of turkey poults fed corn-soybean meal diets.

The effect of microbial phytase on N and amino acid (AA) digestibility and N retention was investigated in a 29-d trial using 480 Nicholas Large White Turkey female poults fed corn-soybean meal diets. A 2 x 2 x 2 factorial arrangement of treatments was used with 0.45 and 0.60% nonphytate P (nP), 22.5 and 28.0% CP, and 0 and 750 U of microbial phytase/kg of diet. At 0.45% nP, adding phytase to either 22.5 or 28.0% CP diets increased BW gain (P < 0.01), and percentage (P < 0.01) and weight (P < 0.10) of toe ash; at 0.60% nP, the magnitude of the effect of phytase was less (P > 0.10) than observed for 0.45% nP and inconsistent. Apparent and true ileal digestibility of N and AA was estimated by using chromic oxide as an indicator at Day 24. At 0.45% nP, adding phytase to 22.5% CP diets tended to improve the apparent and true ileal digestibility of N and AA, except cysteine or methionine; adding phytase to 28.0% CP diets increased the digestibility of N and most of the AA (P < 0.001 to 0.10). At 0.60% nP, adding phytase to 22.5% CP diets increased the apparent and true ileal digestibility of N and all the AA (P < 0.001 to 0.10), but did not change digestibilities at 28.0% CP diets. Adding phytase also increased (P < 0.001 to 0.10) apparent ileal digestibility of DM and P at 0.45% nP for both CP diets, but only for 22.5% CP diets at 0.60% nP. The total excreta were collected at Day 27 to 29. Adding phytase to 0.45% nP diets increased apparent utilization of DM (P < 0.01 to 0.10) and retention of N (P < 0.05 to 0.10) at both CP levels; retention of P was only increased (P < 0.10) at 22.5% CP. At 0.60% nP, adding phytase increased utilization of DM (P < 0.05) and retention of N (P < 0.10) only at 22.5% CP; P retention was not affected. In summary, microbial phytase enhanced growth performance, toe ash, ileal N and AA digestibility, and apparent N and P retention.

6-Phytase↗

PubMed1995

The interaction of clonidine and nitric oxide on feeding behavior in the chicken.

Central administration of alpha 2-receptor agonists stimulate food intake in mammalian and avian species. Recently we reported that inhibition of nitric oxide (NO) synthase (NOS) decreased food intake in chickens. In the present study, we investigated whether the increased eating induced by clonidine (Clon), an alpha 2-receptor agonist, is attenuated by NOS inhibition. In the first experiment, four levels (0, 9.4, 18.8 or 37.5 nmol/10 microliters) of Clon were administered into the right lateral ventricle of chickens, and food intake was monitored. Clon increased 30 min-food intake in a dose-dependent manner. In a co-administration study of L-NG-nitro-arginine methyl ester HCl (LNNA), a NOS inhibitor, and Clon, LNNA (0, 1.5, 3.0 or 5.9 mumol) attenuated food intake induced by Clon (37.5 nmol) in a dose-dependent manner. Our results suggest the possibility that NO interacts with adrenergic neurons in the central nervous system to modulate feeding behavior in the chicken.

Animals↗

PubMed1995

Endogenous amylase levels and response to supplemental feed enzymes in male turkeys from hatch to eight weeks of age.

Amylase and xylanase enzyme concentrations in the pancreas, small intestine, and crop were measured in Nicholas male poults fed diets with and without supplemental amylase and xylanase from 0 to 8 wk of age. Eight birds from each of three diets (control, amylase-supplemented, xylanase-supplemented) were killed every 3 d to determine the amylase and xylanase activity within the pancreas, small intestine, and crop. Pancreatic organ weight was not affected by diet, indicating an absence of dietary amylase effect upon pancreatic tissue growth. Pancreatic amylase activity was not consistently affected by diet. Amylase activity within the intestinal chyme increased sporadically with dietary amylase supplementation over the control and xylanase-supplemented diets. Increasing supplemental amylase activity levels may provide more conclusive evidence of an additive effect of dietary amylase and endogenous amylase activity. Xylanase supplementation within the feed did not affect endogenous amylase activity.

Amylases↗

PubMed1995

Effects of protein level and enzyme supplementation upon growth and rate of digesta passage of male turkeys.

An experiment was conducted to determine the effect of feeding enzyme supplements (Avizyme and protease) at two levels of dietary crude protein (24 and 28%) to male turkeys from 0 to 5 wk of age. The Avizyme-protease enzyme mixture was fed at five concentrations within each protein level in an effort to determine an optimal level of supplementation. Enzymes were added to the 24% protein diet to determine whether the supplements would enhance the growth performance of birds fed the lower protein diet to the level of those fed the 28% protein diet. Rate of passage was evaluated to determine whether an ANF effect corresponded to enzyme concentration or protein level. Dietary protein level significantly influenced growth. Birds fed the 28% protein diet had improved body weight gain, feed consumption, and feed efficiency of 11.5, 6.5, and 4.4%, respectively, when compared with birds fed the 24% protein diet. Enzyme addition to the 24% protein corn-soybean meal diet produced a graded response but did not improve growth over the control. Although enzyme supplementation improved poult utilization of the 24% protein diet, growth and feed utilization were not equal to the performance of the poults fed the 28% protein diet. When the enzyme mixture was added to the 28% diet, performance was not consistently altered. Rate of digesta passage was not different between the levels of dietary protein or among levels of enzyme supplementation, indicating that the applied protein levels did not deleteriously affect nutrient utilization.

Animal Feed↗

PubMed1995

Growth and intestinal morphology of male turkeys as influenced by dietary supplementation of amylase and xylanase.

Three diets, a control and two diets supplemented with an enzyme cocktail premix containing either amylase or xylanase, were each fed to 100 male poults (10 replicates of 10 poults per pen) from 0 to 5 wk of age to observe the effects upon body weight gain, feed intake, and feed efficiency. The amylase-supplemented diet significantly increased feed efficiency through the first 2 wk and significantly increased body weight gain and feed intake through the first 3 wk. Xylanase supplementation did not improve growth or feed efficiency over the control. Mean villus length within the jejunum and ileum was significantly increased at 2 and 3 wk of age by dietary supplementation of amylase when compared with the control and xylanase diets. These findings suggest that the increased growth associated with the amylase diet during 0 to 3 wk can, in part, be explained by the increase in absorptive surface area, allowing for increased digestion of available nutrients coupled with increased enzyme activity for carbohydrate degradation from the supplemental enzymes.

Amylases↗

PubMed1995

Improving phosphorus availability in soybean meal for broilers by supplemental phytase.

A 21-d experiment was conducted with day-old male broilers (n=840) to evaluate the effectiveness of supplemental phytase for improving the availability of phytate P in soybean meal when varying levels of P were fed. The semi-purified basal diet (.18% phytate P) contained soybean meal as the only protein source. Seven levels of phytase (0, 200, 400, 600, 800, 1,000, and 1,200 U/kg diet) were added to diets formulated to contain .20, .27, or .34% nonphytate P (nP; or .38, .45, and .52% total P, respectively). The desired levels of nP in the three basal P diets were achieved by adding varying amounts of defluorinated phosphate. A 2:1 Ca:total P ratio was maintained in all diets. Body weight gains and feed intake were improved (P < .001) by phytase at all nP levels, but the magnitude of response was greatest at low nP levels, resulting in an nP by phytase interaction (P < .01). Gain:feed was unaffected by phytase addition. A high mortality (35 to 45%) was observed for the .20 and .27% nP diets without added phytase, but this declined to normal levels with the addition of 200 to 400 U phytase/kg diet. Ash percentage of toes and tibia and shear force and stress of tibia increased with added phytase. These responses clearly show that the phytate-bound P in soybean meal was made more available to broilers by microbial phytase, and the total response was related to the phytase and nP/total P levels. Based on the high R2 values for the second order translog equations, BW gain, feed intake, and toe ash percentage were the most sensitive indicators to assess P availability, followed by tibia force and ash percentage. Derived nonlinear and linear equations for BW gain and toe ash percentage at the two lower nP levels were used to calculate P equivalency values of phytase for inorganic P. Using the average function of P released ( gamma ) by microbial phytase ( chi ) derived with nP levels of .20 and .27% for BW gain and toe ash percentage, gamma = 1.120 - 1.102e-.0027chi, 1 g of P could be released with 821 U of phytase. The amount of P released increased with increasing levels of phytase, but the amount of P released per 100 U of phytase decreased. Released P ranged from 31 to 58% of phytate P for 250 to 1,000 U of phytase/kg of diet.

6-Phytase↗

PubMed1995

Response of turkey poults to tiered levels of Natuphos phytase added to soybean meal-based semi-purified diets containing three levels of nonphytate phosphorus.

A 3-wk feeding trial using 920 day-old turkey poults was conducted to evaluate the addition of seven levels of phytase (Natuphos; 0, 200, 400, 600, 800, 1,000, and 1,200 U/kg of diet) to diets containing three levels of nonphytate P (nP) (.27, .36, and .45%). A positive control diet contained .60% nP. Semi-purified basal diets contained soybean meal as the only protein source. The increase in BW gain from added phytase was greatest for the lowest nP diet (nP by phytase interaction, P < .001). At .27% nP, gains improved (P < .001) to 800 U of phytase/kg of diet and then reached a plateau. At .36 and .45% nP, increases in gains were observed only for 200 U of phytase/kg of diet. The highest phytase addition to.36 and .45% nP diets produced gains equal to those of the positive control diet. Feed intake increases paralleled those of BW gains. Gain:feed was lowest for the .27% nP diets without phytase, but improved (P < .001) to 800 U of phytase/kg of diet and then reached a plateau. The high incidence of leg disorders and high mortality (40%) observed for the poults fed the .27% nP diet without added phytase declined with the addition of 200 to 400 U of phytase/kg of diet. Ash percentage of toes and tibias increased as the levels of nP (P < .001) and phytase (P < .01) increased; the magnitude of the response to phytase decreased as nP in the diet increased, resulting in an nP by phytase interaction (P < .001). Tibial shear force and stress responded in a similar manner to increasing levels of nP and added phytase. Results show that 652 U of microbial phytase is equivalent to 1 g of P from defluorinated phosphate in turkey starter diets using soybean meal as the only source of phytate P. The response per 100 U of phytase decreased as the total amount of phytase added was increased.

6-Phytase↗

PubMed1994

Nitric oxide controls feeding behavior in the chicken.

To investigate the effect of nitric oxide (NO) on food intake in the chicken, L-NG-nitro-arginine methyl ester HCl (L-NNA), an inhibitor of NO synthase, was applied. When i.p. administered, L-NNA significantly inhibited the food intake of broiler chickens in a dose response manner. Food ingestion was also depressed by the i.c.v. injection of L-NNA in a dose response fashion. The effect of L-NNA was attenuated by i.c.v. administration of L-arginine. These results suggest that central NO may control feeding behavior in the chicken.

Animals↗

PubMed1994

Peripheral regulation of food intake in poultry.

This review focuses on food intake regulation in avian species with the emphasis on sites of action outside of the central nervous system using data obtained mainly with studies involving poultry. Avian species do appear to regulate food intake, and there is good evidence that both the gastrointestinal tract and the liver are primary sites for regulation. Although young meat-type chickens may be eating near gut capacity, this does not appear to be the case in older birds. Furthermore, although the crop probably has a role in food intake control when meal feeding, its role during free access feeding is marginal. Food intake can be altered in chickens by infusion of glucose, lipids, epinephrine and possibly amino acids into the liver. The response to such infusions is altered by genotype and feeding state (fed or unfed). In addition, injection of peptides including cholecystokinin, bombesin, and gastrin outside the central nervous system decrease food intake. It is uncertain whether the anorexigenic effect of these peptides is a specific response, or if it is a general response caused by abdominal discomfort. Opioids appear to stimulate food intake with at least part of their effect being from outside of the central nervous system. Therefore, although the central nervous system is involved in food intake control in avian species, there are other sites involved. Furthermore, genetic selection for growth in meat-type chickens has altered the responsiveness of these control mechanisms suggesting that there is genetic variation for these physiological systems.

Amino Acids↗

PubMed1993

Food and water intake responses of the domestic fowl to norepinephrine infusion at circumscribed neural sites.

The effect on food and water intake of injection of norepinephrine into circumscribed brain sites of the domestic fowl was investigated. Injection of norepinephrine into sites throughout the preoptic area caused reliable increases in food intake. Food intake was also increased by injection of norepinephrine in the ventromedial nucleus, paraventricular nucleus, and medial septal sites. Food intake was decreased by injections near the lateral septal organ and the anterior portion of both the nucleus reticularis superior, pars dorsalis, and the tractus occipitomesencephalicus. Within the preoptic area, water intake was increased at basolateral sites but was inconsistently affected at more medial sites. No consistent trends were noted at sites examined outside the preoptic-hypothalamic area.

Animals↗