Biomedical subjects

D M Denbow

Publications and source records attributed to D M Denbow.

At least 73 records · Page 4Linked to original sources

PubMed1990

Central versus peripheral opioid regulation of ingestive behavior in the domestic fowl.

1. Three experiments were conducted to determine whether opioid regulation of ingestive behavior in the domestic fowl is mediated at sites within the central nervous system (CNS) or peripheral tissues. 2. Food and water intake were significantly decreased by the intramuscular (im) injection of naloxone hydrochloride (NHCl) and naloxone methobromide, which have a high and low ability, respectively, to cross the blood-brain barrier. 3. Water, but not food, intake was significantly decreased by the intracerebroventricular (ICV) injection of NHCl. However, water intake was not affected by the im injection of doses which were effective when given ICV. 4. These results suggest that in the domestic fowl there is a peripheral component to opioid regulation of food intake, while opioid regulation of water intake seems to be mediated at peripheral sites and within the CNS.

Animals↗

PubMed1990

Protein and energy self-selection by turkey hens: reproductive performance.

1. The influence of protein and energy self-selection on the reproductive performance of turkey hens was investigated. Large White turkey hens were fed on either a complete diet (185 g CP/kg, 11.30 MJ ME/kg) or were provided with a choice between a high protein-low energy diet (348 g CP/kg, 7.74 MJ ME/kg) and a high energy-low protein diet (81 g CP/kg, 13.39 MJ ME/kg). 2. Egg production, egg weight, and the fertility and hatchability of eggs produced were not significantly affected by the dietary treatments (P greater than 0.05). 3. While energy intake was not significantly different between groups, protein consumption decreased by approximately 40% (P less than or equal to 0.001) among self-selecting hens compared to hens fed on the complete diet. This resulted in a 10% (P less than or equal to 0.05) reduction in the food intake in the self-selecting birds.

Animal Feed↗

PubMed1990

Effect of light sources and light intensity on growth performance and behaviour of female turkeys.

1. The effect of different light sources (incandescent, sodium vapour, daylight fluorescent and warm fluorescent) and light intensities (10.8 and 86.1 lux) on growth performance and behaviour of female turkeys was investigated in two experiments conducted at different times of the year. 2. Although light source influenced body weight and efficiency of food utilisation, there was no consistent effect between experiments in favour of any particular source. 3. Light intensity had no effect on body weight, efficiency of food utilisation or behaviour.

Animals↗

PubMed1990

Genetic influences on seasonal decline in the fertility of female turkeys.

Daughter-dam pairs of white, large-bodied, turkey breeder hens (108) were reared under similar husbandry conditions, and their egg production and fertility were monitored from the onset of lay for 6 mo. On a monthly basis, percentage fertility was compared by daughter-dam regressions to estimate heritabilities. The heritability estimates were 18.36, and 38%, respectively, for the 2nd, 3rd, and 4th mo of lay; but no estimates could be made for Months 1, 5, or 6. The heritability of percentage fertility for Months 2, 3, and 4 combined was 42%. The proportion of hens that remained above 75% fertility declined each month for both dams and daughters, except in one case. Thus, the seasonal decline in fertility appears to have a genetic component.

Animals↗

PubMed1990

Influence of light sources on the growth and reproduction of large white turkeys.

The present study evaluated the effects of sodium vapor (SV), daylight fluorescent (FL) and incandescent (IN) light sources on the growth and reproduction of primary turkeys. Large White turkeys (90 sire line and 324 dam line) were reared by sex under one of the three light sources from 8 to 22 wk of age. At 22 wk of age, all males and females were preconditioned under their assigned light source, but the photophase was restricted to 6 h per day at an intensity of 21.6 lx. At 33 wk of age, the males were exposed to 16 h of light per day under the same light sources in which they were reared. At 35 wk of age, the females were reassigned to the various light sources in order to achieve all possible combinations of adolescent and breeder light-source treatments. Sixteen hours of light per day were provided at an intensity of 53.8 lx during a 20-wk cycle of egg production. The body weights of males and the feed efficiencies of males and females were unaffected by the adolescent light-source treatment. The females were significantly heavier under SV than those under FL and IN lights. Hen-housed egg production was significantly higher for females exposed to SV and FL lights versus IN during the first 10-wk production period. Hen-day egg production was significantly higher for females given FL than for those provided SV and IN lights. However, total hen-housed and hen-day production was unaffected by either adolescent or breeder light-source treatments. Fertility, hatchability, days to first egg, egg weight, and egg specific gravity were also unaffected by either the adolescent or breeder light-source treatment. (ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1989

Effects of oviductal trauma on humoral anti-sperm antibody production and fertility in turkey breeder hens.

Varying degrees of oviductal trauma were induced in turkey breeder hens during artificial insemination to determine the effects on humoral anti-sperm antibody production and fertility. Two experiments were completed. Mode of artificial insemination had no effect on fertility or the production of serum anti-sperm antibodies in either experiment. It was concluded that no relationship exists between serum anti-sperm antibody titers and fertility.

Journal Article↗

PubMed1989

The relationship of infertility to antibody production in the uterovaginal sperm storage tubules of turkey breeder hens.

Oviductal tissue from fertile and infertile turkey breeder hens was stained immuno-histochemically to test for the presence of antibody positive cells. Relatively infertile turkey hens (< 50% fertility) were found to have antibody positive cells within the uterovaginal sperm storage tubule epithelium, while fertile turkey hens (> 90% fertility) had no antibody positive cells. Data suggest a local immune response to spermatozoa exists in the uterovaginal sperm storage tubules of the turkey hen which may have a detrimental effect on fertility.

Journal Article↗

PubMed1989

Ingestive responses to mu and delta opioid receptor agonists in the domestic fowl.

1. Four experiments were conducted using the highly specific mu and delta opioid receptor agonists morphiceptin (B-casomorphin 1-4, amide) or [Met5]-enkephalin, respectively, to evaluate the effect of mu and delta opioid receptor agonists on ingestive behaviour in the domestic fowl. 2. Intracerebroventricular (ICV) administration of 0.625, 1.25, 2.5 and 5.0 micrograms of morphiceptin significantly stimulated drinking, while having no effect on feeding. Intramuscular injection of 0.5, 1.5 and 3.0 mg morphiceptin/kg body weight induced a significant increase in feeding, whereas drinking was not altered. 3. ICV administration of 0.625, 1.25, 2.5 and 5.0 micrograms [Met5]-enkephalin, as well as intramuscular injection of 0.5, 1.5 and 3.0 mg [Met5]-enkephalin significantly stimulated feeding while having no effect on drinking. 4. These results suggest that, in the central nervous system, mu opioid receptor agonists stimulate drinking and delta receptor agonists stimulate feeding. At sites outside the blood-brain barrier, both mu and delta opioid receptor agonists stimulate feeding.

Animals↗

PubMed1989

Effect of light sources and light intensity on growth performance and behavior of male turkeys.

This study consisted of two experiments: the first was conducted with Large White turkey males during the spring and summer (experiment 1) and the second during the autumn and winter (experiment 2). When 56 d of age, the birds were assigned to light-controlled pens and exposed to continuous illumination. Light sources used were incandescent, daylight fluorescent, warm fluorescent or high pressure sodium vapour lamps at light intensities of 10.8 or 86.1 lux. Results obtained showed that the light sources used had no significant effects on growth performance, efficiency of food utilization, feather scores or live bird quality of Large White turkeys. Social encounters were higher in birds reared under fluorescent and sodium vapour lights and mortality was higher in birds under fluorescent lights in experiment 1. Behaviour, feather scores, live bird grade and mortality were unaffected by light source treatments in experiment 2. Light intensity had no significant effect on growth, efficiency of food utilization, feather scores or bird market quality. Social encounters and mortality were higher in males exposed to 86.1 lux of light intensity.

Animals↗

PubMed1989

Peripheral and central control of food intake.

To either increase or decrease body weight of poultry, an understanding of food intake regulation is essential. Although it is advantageous to increase food intake in market birds, it is desirable to decrease intake in breeders. Recent studies have shown that the digestive tract, liver, and brain are all involved in food intake regulation. In this review, the role of various neurotransmitters and metabolic substrates in food intake regulation, both within the central nervous system as well as in the periphery, is discussed. In addition, how the strain of the bird or the physiological state of the animal influences the response to various compounds is discussed.

Animals↗

PubMed1988

Effect of heat stress early in life on mortality of broilers exposed to high environmental temperatures just prior to marketing.

A study was conducted to investigate the effects of heat stress during the 1st wk of life on subsequent mortality resulting from exposure to high environmental temperature and feed restriction just prior to marketing of broiler cockerels. Birds were raised under standard husbandry procedures except that at 5 days of age, half the broilers were heat stressed by exposure to an environmental temperature ranging from 35.0 to 37.8 C for 24 h while the remaining birds were held at 29.4 C. At 44 and 45 days of age, half the unstressed controls and half the birds stressed at 5 days of age were exposed to temperatures ranging from 35.0 to 37.8 C for 8 h/day. In a factorial arrangement of treatments, the effect of restricting feed for 8 h/day on Days 43, 44, and 45 was also examined. Exposing birds to high environmental temperatures at 5 days of age resulted in a significant decrease in mortality when birds were exposed to a high environmental temperature later in life. In addition, feed efficiency was improved significantly in early heat-stressed birds whereas body weight and body weight gain were not affected. Feed restriction had no significant effect on mortality, body weight, or feed efficiency. It appears, therefore, that exposing broiler cockerels to mild heat stress for 24 h at 5 days of age can significantly decrease mortality resulting from high environmental temperature later in life.

Animals↗

PubMed1987

The effects of opioid antagonists on ingestive behavior in the domestic fowl.

The effects of opioid antagonists on food and water intake in commercial stocks of chickens were investigated. Four experiments were conducted to examine the effects of naloxone (N-allylnoroxymorphone) and naltrexone (N-cyclopropylnoroxymorphone) in broiler and Single-Comb White Leghorn cockerels. Birds were injected intramuscularly with either naloxone HCl or naltrexone HCl at doses from 2.5 to 10 mg/kg. Food and water were offered ad lib 15 min post-injection. In broilers, naloxone dose-dependently attenuated food and water consumption for 300 min, while in Leghorns naloxone attenuated food and water intake for 240 and 300 min, respectively. Naltrexone dose-dependently reduced food and water consumption for 300 min in both broilers and Leghorns. Neither naloxone nor naltrexone significantly altered food or water intake at 24 hr. A fifth experiment was conducted to verify the specificity of opioid antagonism for water intake. Broiler cockerels received an intraperitoneal injection of either isotonic saline (0.15 M NaCl) or hypertonic saline (2.5 M NaCl) followed by an intramuscular injection of either isotonic saline or naloxone HCl (5 mg/kg). Food was withheld for the entire experiment while water was offered ad lib 15 min following the second injection. Naloxone significantly attenuated drinking in normally hydrated and osmotically challenged birds for 150 min. The results suggest a role for endogenous opioid peptides in the regulation of food and water intake in meat and egg-laying stocks of chickens.

Animals↗

PubMed1987

The effect of ambient temperature on turkey embryonic development at oviposition.

Stage of embryonic development at oviposition was measured in turkey breeder hens maintained in relatively warm and cool environments. The premise was that variations in embryonic development at oviposition might account for the decreased hatchability associated with warm summer temperatures. No treatment effect was found, as judged by somite counts after 52 h of incubation. Variation in embryonic development was as great within a hen as between hens, indicating that causative factor(s) other than stage of development at oviposition is the reason for reduced hatch of fertile eggs during periods of relatively high environmental temperature.

Journal Article↗

PubMed1987

Food intake response of genetically selected high and low-weight line cockerels to plasma infusions from fasted fowl.

Two experiments were conducted to determine if food intake of free-feeding chickens could be affected by infusions of plasma from fasted fowl. In the first experiment, chickens from two lines genetically selected for high or low body weight were infused intrahepatically with plasma collected from free-fed and fasted individuals from each line. Food intake of low-weight line birds was increased significantly by infusions of plasma from fasted high-weight line chickens when compared to food intake of low-weight line birds receiving plasma from free-fed low-weight line chickens. Food consumption in high-weight line birds was unaffected by any of the plasma treatments. In the second experiment, plasma from free-fed and fasted high-weight line chickens was infused intrahepatically into Single Comb White Leghorn cockerels. Again the birds receiving the plasma from the fasted fowl consumed significantly more food than those infused with plasma from free-fed fowl. The results of these experiments suggest that some property of plasma from fasted birds stimulates appetite. Selection for increased body weight may have intensified this hunger factor in high weight fowl.

Animals↗

PubMed1987

Ionostatic control of food intake in the domestic fowl.

It has been suggested that there is ionostatic control of food intake in which calcium, acting in the hypothalamus, alters food intake. This study was conducted to determine the effects of intracerebroventricular (ICV) injections of calcium on food and water intake in both broiler and Leghorn cockerels. The ICV injection of 50, 100, or 150 mM CaCl2 had no significant affect on food or water intake in Leghorn cockerels. In broilers, the ICV injection of 50 mM CaCl2 significantly increased food intake. This effect appeared to be due to Ca++ as equivalent amounts of Cl- given as NaCl had no effect on food intake nor did isosmotic solutions of NaCl. The effect of Ca++ on water intake in broilers is equivocal as it increased water intake in one experiment while decreasing it in another. Whereas these results support the hypothesis of a role for calcium in food intake regulation in broilers, they do not support the existence of a specific ionostatic control mechanism.

Animals↗

PubMed1987

Ingestive behavior of meat and egg-type chickens: equal sensitivity to naloxone.

The efficacy of the opioid antagonist naloxone in attenuating ingestive behavior in stocks of chickens genetically selected for either meat (Rock-Cornish, RC) or egg production (Single-Comb White Leghorn, SCWL) was investigated. Because the stocks differ markedly in growth rate, two experiments were conducted to compare RC and SCWL cockerels at similar body weights and at the same age. Birds were injected intramuscularly with either isotonic saline or naloxone HCl at a dose of 5 mg/kg body weight. Food and water were offered ad libitum 15 min postinjection. In RC and SCWL stocks of similar body weight, naloxone significantly attenuated cumulative food and water intake through 210 min following the return of food and water. When administered to RC and SCWL stocks of the same age, naloxone significantly attenuated cumulative food intake for 300 min and cumulative water intake at 60 and 120 min. The relatively long-term depressions in cumulative food and water intake were attributable to significant decreases in incremental consumption within early time periods. There was no significant difference in the efficacy of naloxone in attenuating ingestive behavior when the stocks were compared at either similar body weights or at the same age. The results demonstrate that genetic selection for meat or egg production has not significantly altered opioid mechanisms regulating food and water intake in the domestic fowl.

Animals↗

PubMed1987

Naloxone attenuates food but not water intake in Japanese quail.

The effect of the opioid antagonist naloxone on food and water intake in male Japanese quail (Coturnix coturnix japonica) was investigated. Birds were injected intramuscularly with 0, 3, 10, and 30 mg/kg body weight of naloxone hydrochloride. Food and water were offered ad libitum 15 min postinjection. Food intake was attenuated in a dose-dependent fashion through 300 min following the return of food and water. The dose-response relationship was quadratic, with the greatest reduction in food intake occurring at the 10 mg/kg body weight dose. Water intake was not affected by naloxone. The results demonstrate that endogenous opioid peptides are involved in the regulation of food, but not water, intake in Japanese quail.

Animals↗

PubMed1986

Alteration of food intake following intracerebroventricular administration of plasma from free-feeding domestic fowl.

Four experiments were conducted to investigate the presence of a factor in the plasma of the domestic fowl that alters food intake when injected into the lateral cerebral ventricle. Plasma collected from free-feeding and 24-hour fasted birds was lyophilized and reconstituted to 2, 4, or 5 times normal concentration. Stainless steel guide cannulae were stereotaxically implanted into the lateral cerebral ventricle of 8-week-old Single Comb White Leghorn cockerels. Free-feeding birds received 10 microliter intracerebroventricular (ICV) injections of normal (Experiment 1) and concentrated (Experiments 2, 3, and 4) plasma collected from free-feeding and 24-hour fasted birds. Artificial cerebrospinal fluid (aCSF) served as the control. Food intake was significantly decreased by ICV injections of 2, 4, and 5 times normal concentration of plasma from fed birds. Plasma from fasted birds did not alter food intake regardless of concentration, but did significantly reduce water intake when concentrated to five times normal. It appears that a satiety factor, which can be detected by the central nervous system, is present in the plasma of free-feeding domestic fowl.

Animals↗