The effect of triacylglycerol chain length on food intake in domestic fowl.

Triacylglycerols of varying chain lengths were tested for their effects on food intake in fasted Single-Comb White Leghorn cockerels 9-12 weeks of age. Tributyrin, tricaprylin, triolein, or saline were intubated intragastrically or infused intrahepatically. All triacylglycerol administrations were in 10 ml volumes with 10 kcal being infused intrahepatically and 10 or 20 kcal being infused intragastrically. When administered intragastrically, the short-chained triacylglycerol tributyrin decreased food intake at most times tested; the medium chain-length tricaprylin and the long chain-length triolein affected food intake sporadically. When infused into the liver, tributyrin and tricaprylin decreased food intake at most times tested, whereas triolein decreased food intake at 60 and 180 minutes only. Satiating effectiveness was related to triacylglycerol chain length when intubated, which may reflect rate of absorption from the gut; however, hepatic satiety receptors were also differentially sensitive to triacylglycerol chain length indicating that more than rate of assimilation from the gut must be considered.

Protein and energy self-selection of turkey hens. Serum prolactin and luteinizing hormone concentrations.

1. The incidence of broodiness was four times as high among turkey hens fed a complete control diet than among hens allowed to self-select their diet from two different feed sources, one being relatively high in protein and the other relatively high in energy (i.e. split-diet). 2. Among non-broody birds, hens fed the split-diet had a significantly lower serum prolactin concentration in the third month of production as compared to control hens. 3. Hens in their second season of egg production had significantly lower serum luteinizing hormone concentrations during the latter stages of egg production than did first season hens.

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.

Effects of various feeding regimens on reproduction in broiler-breeder males.

A study was conducted using commercial broiler-breeder males and females maintained in all-litter pens allowed to mate naturally. Using a separate feeding arrangement, males were given a diet containing either 12% or 14% protein. Body weights were maintained at either 90% or 100% of the recommended level. Females were provided feeders with grills which denied males access to the feed, while male feeders were elevated 46 cm above the floor to deny female access to that feed. In control pens, males and females ate from the same feeders and received a breeder diet with 14% protein. Eggs produced in pens where the males and females were fed separated showed significantly higher fertility (4.2%) than eggs from control pens. No differences in percentage fertility were noted between the two dietary-protein levels or body-weight groups of males fed separately. Furthermore, no differences were measured in percentage hatch of fertile eggs among any of the treatment groups. Males in control pens showed significantly heavier body weights and breast-angle measurements starting at 32 and 40 wk of age, respectively. No treatment effect was measured for male pododermatitis. The male control birds had heavier testes weights than the males in the groups with restricted body weights. However, semen concentration was not affected. This indicates that the improved fertility was related to the size and weight of the males, not to their ability to produce semen. The reduced fertility associated with excess male body weight may be both physical and physiological in nature.

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.

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.

Effects of feeder space on body weight uniformity of broiler breeder pullets during an alternate day feeding program.

The effect of feeder space on body weight uniformity of adolescent broiler breeder females during a feed restriction program was evaluated. From 2 to 20 wk of age, broiler breeder pullets were fed a starter/developer diet containing 16.0% protein and 2,944 kcal ME/kg feed. Feed allocations, predicated on mean pen body weight, were fed on an every other day basis. Feeder space was 45 or 90% of that recommended for use with a feed restriction program. The mortality, feed efficiency and body weight uniformity data all support the hypothesis that it is not necessary to provide enough feeder space to enable all birds to eat simultaneously. Broiler breeder pullets provided only 45% of the recommended feeder space responded as well as, or better than, those given 90% of the recommended feeder space.

Hyperplastic response of adipose tissue to caloric overconsumption in sexually mature chickens.

Two experiments were conducted to determine the hyperplastic response of adipose tissue from sexually mature chickens in response to caloric overconsumption. In the first experiment, birds were either force-fed or allowed to consume feed ad libitum, whereas in the second experiment, a feed-restriction regimen was also implemented. In both experiments feeding treatments were applied for 19 consecutive days, and a diet high in energy and low in protein was fed to all birds to promote lipogenesis. To monitor adipocyte dynamics, birds in Experiment 1 received an intramuscular injection of [methyl-3H]thymidine on Day 15, whereas in Experiment 2 birds were injected on Days 1 and 10. In both Experiments 1 and 2, body weight gain and percentage weight gain were greater in the force-fed birds. Furthermore the retroperitoneal (abdominal), and right sartorial fat depots increased in weight as a result of force-feeding, and there were concomitant increases in total adipocyte DNA content and total radiotracer uptake by these tissues. The results indicate that expansion of adipose tissue in sexually mature chickens is not restricted solely to cellular hypertrophy, but periodic hyperplastic activity also occurs in response to caloric overconsumption.

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.

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.

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.

Ovum formation and multiple ovulation in lines of white Plymouth Rocks and their crosses.

The production of double-yolked eggs and the duration of the rapid growth phase of yolks were measured in parental lines of White Plymouth Rock pullets and their crosses over 30 d, commencing with the day of first egg. Significant differences were found between mating combinations in the incidence of multiple-yolked eggs, but not in the period of rapid yolk growth. Heterosis and recombination effects for multiple ovulation were respectively -9% and -66% of the mean, while the corresponding values for the period required for rapid yolk growth were -1% and -5%. Three double-yolked eggs were observed containing yolks which differed by 3 d in their periods of rapid growth. Hypotheses are were presented for the origin of double-yolked eggs.

Avian cerebrospinal fluid: repeated collection and testing for a possible role in food intake regulation.

The objective of this study was to determine if a factor(s) involved in the regulation of food intake exists in the cerebrospinal fluid (CSF) of the domestic fowl. A technique was developed that allows blood-free CSF samples to be collected repeatedly from the cisterna magna for up to 6 weeks. Using this technique, CSF was collected from free-feeding and 24-hour fasted broiler cockerels and injected into the lateral cerebral ventricle of 8-week old Leghorn cockerels and 4-week old broiler cockerels. The free-feeding birds received 10 microliter intracerebroventricular injections of CSF either at normal concentration (1 X -CSF) (Experiments 1 and 3) or at four times normal concentration (4 X-CSF) (Experiments 2 and 4). Artificial CSF served as the control. Food and water consumption were monitored following injection. The 1 X- and 4 X-CSF collected from both the free-feeding and 24-hour fasted donors did not affect the food intake of either the Leghorn or the broiler recipients. Water intake, however, was significantly increased in the Leghorns and broilers receiving the 4 X-CSF collected from 24-hour fasted birds. Thus, there does not appear to be a factor(s) present in the CSF collected from the cisterna magna that alters food intake when injected into the lateral ventricle, but a factor may exist in the CSF collected from fasted donors that stimulates water intake.

Tryptophan's influence on feeding and body temperature in the fowl.

The neurotransmitter, serotonin, has been implicated in both food intake and body temperature regulation. In this experiment, the effect of tryptophan, the amino acid precursor of serotonin, on food consumption and rectal temperature in the fowl was determined. Single Comb White Leghorn cockerels were intubated with a tryptophan solution or distilled water. Tryptophan significantly (P less than or equal to .05) decreased both food intake and body temperature of the birds. These results suggest that tryptophan may inhibit food intake via peripheral rather than central mechanisms.

Intraperitoneal injections of tryptophan inhibit food intake in the fowl.

The effects of intraperitoneal injections of tryptophan on food intake in the chicken were examined. Four levels of tryptophan (12.5, 25, 50, 100 mg), and a saline control were tested in birds that were ad libitum fed or fasted 24 hr. The tryptophan treatments decreased food intake in the ad libitum-fed chickens in a dose-dependent manner. Food intake of the 24-hr fasted chickens was not influenced by the tryptophan injections. It is not known whether tryptophan is acting centrally or peripherally to decrease food intake of ad libitum-fed chickens.

Intraduodenal glucose infusions do not affect food intake in the fowl.

A series of experiments was performed to examine the role of the duodenum in food intake regulation in the fowl. In each of the experiments, birds were surgically fitted with intraduodenal cannulae. In Experiments 1 to 6, Single Comb White Leghorn (SCWL) or Rock Cornish cockerels were infused with isosmotic glucose, urea, or saline solutions. Glucose had no effect on food intake as compared with the saline and urea control treatments. In the final experiment, food intake of splanchnicectomized SCWL cockerels was contrasted to that of sham-operated controls, following intraduodenal glucose infusions. No difference between the denerved and intact birds was observed. The duodenum of the fowl, unlike the mammal, does not appear to play a significant role in food intake regulation.

Food intake in the domestic fowl: effect of intrahepatic lipid and amino acid infusions.

Five experiments were conducted to determine the effect of hepatic and jugular infusions of amino acid and lipid solutions on short-term food intake of cockerels. Neither jugular nor hepatic infusions of amino acids had any effect on food intake of Single-Comb White Leghorn (SCWL) cockerels. Lipid infusions had no effect on SCWL cockerels when administered intrajugularly but decreased food intake significantly when infused intrahepatically. In contrast, no effect on food intake was observed when Rock-Cornish (RC) cockerels were infused intrahepatically with lipid. Thus, it appears that the liver of the SCWL cockerel is not responsive to plasma amino acid concentrations but is sensitive to circulating lipid levels. This lipid sensitive mechanism may be important in the peripheral control of food intake in a chicken such as the SCWL which has been bred for egg production but may be desensitized in fowl such as the RC broiler which has been selected for large body size and feed consumption.

Reduced food intake following intracerebroventricular administration of a low molecular weight fraction of plasma from free-feeding fowl.

Plasma was collected from free-feeding Leghorn cockerels and partitioned by gel filtration into fractions of different molecular weight ranges. The individual fractions were then lyophilized and reconstituted to four times the original concentration. The plasma was administered to 10-week-old Leghorn cockerels via a stainless steel guide cannula, stereotaxically implanted into the lateral cerebral ventricle. Sated cockerels received 10 microliters intracerebroventricular (ICV) injections of one of the concentrated plasma fractions or of a control injection of artificial cerebrospinal fluid. Food and water intake were monitored following injection. Food intake was significantly decreased by the ICV injection of plasma fractions less than 1500 mol wt, whereas water consumption was not significantly different from that of the controls. The 1500 to 5000 mol wt fraction and the fraction above 5000 did not alter either food or water intake. These results suggest that the plasma of free-feeding domestic fowl contains a low molecular weight factor that is involved in the regulation of food intake.

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.

Selection for growth alters the feeding response to injections of biogenic amines.

Two experiments were conducted to determine if selection for growth altered the response to intracerebroventricular (ICV) injections of methoxamine and 5-hydroxytryptamine (5-HT). Lines of chickens divergently selected over 25 generations for 8-week body weight were used. The ICV injection of methoxamine into fully fed birds significantly increased food intake in the high-weight line but had no effect on food intake in the low-weight line. Conversely, the ICV injection of 5-HT had no effect in fully fed birds but significantly decreased food intake in 24-hr fasted birds in both weight-lines. Food intake was affected by 5-HT for a much longer period in the high-weight line than in the low-weight line. These results suggest that selection for growth alters the brain response to biogenic amines.