Search

1. This study compared the effect of bilateral electrolytic lesions of the basomedial hypothalamus (HL) in broiler and White Leghorn (WL) males. 2. Hypothalamic lesions were placed in WL at 10 weeks of age (body weight 1.1 kg) and in broilers, either at 6 weeks (body weight 1.5kg) or at 10 weeks of age (body weight 3.4kg). They were fed ad libitum until autopsy at 16 and 17 weeks of age for broilers and WL, respectively. 3. Hypothalamic lesions caused obesity (high percentage weight of abdominal adipose tissue) in both strains. Obese fowls with unimpaired reproductive systems were classified as OB and those with functional castration as FC (functionally castrated) or FCLC (functionally castrated with large comb). 4. All post-HL syndromes-OB, FC and FCLC-were present in WL, whereas all obese broilers (which are immature at this age) were classified as OB. 5. The percentage weight of abdominal adipose tissue in OB broilers was lower than in OB WL (3% vs 5%, respectively). 6. Daily food intake of OB broilers was higher than control at 12 to 15 weeks of age, regardless of time of placement of HL, whereas daily food intake of OB WL was significantly higher than that of control WL only during the first 2 weeks following HL. 7. Body weight of OB broilers at autopsy was 20% higher than control broilers, whereas body weight of OB WL was not significantly affected. 8. An additional group of broilers was reared to sexual maturity under food restriction until 28 weeks of age. HL were placed at 10 weeks of age (body weight 1.7 kg). Autopsy was performed after a 4-week period of ad libitum feeding. 9. There were OB as well as FC and FCLC among the HL, food-restricted broilers. Percentage weight of testes and spleen were reduced in OB fowls of both strains, but more so in OB WL. 10. Hyperphagia and weight gain were not observed during the ad libitum feeding period of those obese broilers after HL, indicating that hyperphagia and weight gain are secondary to obesity.

The Mediterranean tortoise (Testudo graeca) is listed as "Vulnerable" on the IUCN Red List. Reproductive characteristics and means to increase offspring production were studied in T. graeca terrestris in a semi-natural environment. Courtship and mating occurred during early spring for about 4 weeks, followed by a laying season of approximately 2 months, with a second, shorter mating period in the fall. During the first mating, calcified eggs were already present in the uterus; we inferred that sperm from both mating seasons were stored in the oviduct for fertilization of eggs of the second laying cycle and of the following year. Average egg production was 3.8+/-0.3 eggs/year. Most females laid all of their eggs in a single clutch, but 18% laid in a second clutch, 11-21 days later. X-ray radiography revealed calcified eggs in the uterus about 4 weeks before oviposition. All eggs in the uterus were calcified simultaneously and were laid in a single clutch; if a second clutch developed, those eggs were also calcified simultaneously. Based on endoscopic examinations, ovaries were active throughout the entire year. Plasma progesterone concentrations in females were very low and were detected only soon after oviposition ( 440 +/-141 pg/ml). Plasma estradiol concentrations in females varied from 4.1 +/-1.5 pg/ml to 70.2 +/-29.4 pg/ml, with no clear seasonal pattern. Maintaining tortoises at a low environmental temperature (9 +/-1 degrees C versus 28 +/- 1 degrees C) reduced plasma estradiol concentrations. Giving 2mg/kg tamoxifen (TAM) increased plasma estradiol to 220 +/-33 pg/ml when treatment was given in September but not in late October, winter or spring. Treatment with TAM increased the number of eggs laid during the following laying season to 7.3 +/- 1.0 eggs/year, laid in one to three clutches. In males, plasma testosterone concentrations had a seasonal pattern with the onset of a rise in July from 2 to >4ng/ml, a continued increase to a peak of 12.8+/-5.3 ng/ml during November and a decline thereafter. Artificial incubation in sand at 29 +/-1 degrees C shortened the natural incubation time of 103+/-3.1 days to 83.5 +/- 1.3 days, increased hatching rate from 28 to 53%, and increased survival rate from 51 to 71% at 40 weeks of age. In summary, this study provides options for increasing reproductive performance, hatchability and offspring survival in captive Mediterranean tortoises, and may offer new tools for conservation of animals that are on the verge of extinction.

The present studies employ multitudinous approaches in order to overcome the methodological obstacles in the understanding of the relationship between neurochemical alterations and behavioral deficits induced by heroin during prenatal development. Mice were exposed prenatally to heroin via daily subcutaneous injections of 10 mg/kg, on gestation days 9-18. At age 50 days, the heroin-exposed offspring displayed behavioral deficits as assessed in the eight-arm and Morris mazes, pointing to possible alteration in the septohippocampal cholinergic innervations. Biochemically there was increased presynaptic activity of these innervations as attested to by the increased [3H]hemicholinium-3 (HC-3) binding sites and by K+-stimulated inositol phosphate (IP) formation. Postsynaptically, there was global hyperactivation along the different components of the nerve conduction cascade, including an increase in M1 muscarinic receptor Bmax, a general increase in G-proteins (GP) including the most relevant, G subtype, and an increase in IP formation and in basal protein kinase C (PKC) activity. However, there was desensitization of PKC activity in response to cholinergic agonist in the heroin-exposed offspring. Transplantation of normal embryonic cholinergic cells to the impaired hippocampus reversed the behavioral deficits and both the pre- and postsynaptic hyperactivity and resensitized PKC activity. To support and further strengthen the findings of the neural grafting study, correlation of the heroin-induced behavioral deficits with the biochemical alterations, done within individuals, was applied. The results showed high r values for IP formation, basal PKC, and PKC desensitization. The r values for HC-3 binding were statistically significant but relatively low. Taken together, the findings of the neural grafting and correlation studies bring us closer to understanding the relationship between the prenatal heroin-induced biochemical and behavioral changes. However, mammalian models possess the inherent methodological hindrances, stemming from possible maternal effects. To provide a control for these confounding variables, a chick embryo model was applied in which filial imprinting, a behavior related to a specific hyperstriatal nucleus, served as an endpoint. Heroin was administered to developing chick embryos by injecting the eggs (20 mg/kg) on incubation days (ID) 0 or 5. Prehatch exposure to heroin markedly diminished the ability for filial imprinting in the hatched chicks.

Embryonic and posthatch long-term exposure to the odor of 2-methoxy-3-isobutyl-pyrazine (2M3IP) was examined for its potential physiological consequences as reflected in changes in BW and organ weights in domestic chicks (Gallus gallus domesticus). Experiments were run from Day 1 of incubation to the age of 3 wk with a total of 360 fertile chicken eggs. The experimental design consisted of four treatment groups: PP chicks were exposed to 2M3IP during both incubation and posthatch rearing; PC chicks were exposed to 2M3IP during incubation only; CP chicks were exposed to 2M3IP during rearing period only; CC control chicks were not exposed to 2M3IP. Chicks were weighed immediately after hatch and at 3 wk of age, when they were necropsied. Various organs (thyroid, adrenal, testes, comb, liver, spleen, abdominal fat, and the bursa of Fabricius) were removed and weighed. Body weights of both sexes in the PP group were reduced. This reduction was significant in males relative to both CP and CC groups and in females only relative to the CP group. Effects of 2M3IP exposure on the examined organs were as follows: in males, adrenal gland weight significantly increased in the PP group vs all other groups. No weight differences were found between the other inspected organs among the four treatments. In females, comb weight significantly decreased compared with the rest of the groups when 2M3IP exposure occurred during incubation (PC). Further investigation is needed to study the mechanisms that underlie the differential effects of pyrazine odor on male and female chicks.

The ontogeny of the tonic immobility (TI) response in domestic fowl chicks was studied during the first week of life. The TI response of naive White-Leghorn Gallus domesticus male chicks ( N =5–9), was tested at the age of 1, 2, 3, 5 and 7 days. TI was induced dorsally and its duration, the number of induction trials and the latency of peeping were recorded. The TI response was strongly affected by age. It was poorly developed during the first 3 days of life, when the median TI duration in control chicks was 10 s and the mean number of induction trials 2.3±0.3. After the third day of life, TI duration increased by up to 15× and susceptibility by about two. Peeping latencies were very short throughout the first week and in many cases, peeping started long before the termination of TI. Immediately following recovery from TI, chicks were put in an open field and the latencies of walking and jumping and the number of steps, jumps and peeps were observed. No changes in either locomotion or vocalization in an open field were found between the third and fifth day. Furthermore, there was no correlation between any of the parameters of the TI and OF tests. The effect of habituation, which is known to attenuate the TI response, was studied by repeatedly subjecting chicks to TI and OF tests, once on each day of the experiment. Habituation prevented the increase in TI duration and susceptibility after the third day of life, but did not affect the OF response. The effect of aversive treatment, which was expected to increase TI, was examined by placing chicks in 5-cm deep tap water for 5 min, prior to testing. Treatment significantly attenuated TI on Day 1 and increased overall locomotion and peeping in open field.

A study was conducted to examine the effect of contact lenses on egg production, egg weight, fear response, and mortality in White Leghorn hens. Two hundred laying hens in their second laying period (76 to 104 wk of age) were housed in 48.5 × 45.5 cm sized cages with five birds per cage. Red contact lenses were placed on the eyes of 100 chickens; the other 100 chickens served as controls. Some of the chickens with the lenses developed eye irritations within 2 wk after the beginning of the experiment. After 7 months, a large proportion of the experimental hens were severely affected. Six hens from each group were killed and necropsied. Heart weight was significantly heavier among the hens with lenses. Duration of tonic immobility (TI) was significantly longer among the control chickens than among those with contact lenses (158 vs. 66 sec). No differences were found in egg production, egg weight, and mortality between the control and the experimental hens. However, contact lenses appear to be associated with an increase in eye irritations and thus their application is discouraged.

Estradiol benzoate (E 2 ) increases plasma lipids in hypothalamic obese, functionally castrated (OFC), obese laying (OL), and control laying hens (CONT). However, E 2 reduces fattiness in OFC but not in OL or CONT hens. Antiestrogen, such as tamoxifen (TAM), reduces plasma lipids in OL and CONT, but not in OFC, hens and has no effect on fattiness in any of them. Apolipoprotein VLDL-II (apo-VLDL-II), lipoprotein lipase (LPL), and rate of lipolysis may mediate these estrogenic effects. In the present study, effects of E 2 and TAM on fattiness, plasma apo-VLDL-II, in vitro lipolysis, and LPL activity in postheparin plasma and abdominal adipose tissue (AAT) were determined in OFC, OL, and CONT hens. Basomedial hypothalamic lesions were performed in 3-month-old White Leghorn hens. At the static phase, 10 months later, OFC, OL, and CONT hens were divided into three subgroups and injected IM on alternate days, with either 2 mg E 2 /kg b.wt., 10 mg TAM/kg, or vehicle corn oil, for 5 weeks. In OL and OFC hens, body and AAT weights were higher than in CONT poullets. Food intake and ovarian weight were similar in OL and CONT, higher than in OFC hens. Plasma LPL activity was higher, whereas plasma apo-VLDL-II and stimulated lipolysis were lower in OFC than in OL and CONT hens. In OFC hens LPL activity per unit of AAT was half than in OL and CONT. Total LPL activity in AAT was similar in OFC and CONT and higher in OL hens. Levels of basal lipolysis were similar in all experimental hens. TAM did not affect any of the measured parameters in OFC hens. In OL and CONT hens, TAM depressed apo-VLDL-II, increased plasma LPL activity, but had no effects on AAT LPL activity, on stimulated lipolysis, or fattiness. E 2 increased apo-VLDL-II to similar levels in all groups and reduced LPL activity in plasma and AAT of obese hens. Only in OFC hens did E 2 enhance basal and stimulate lipolysis and reduce FI and fattiness. We conclude that in adult laying hens, unlike in cockerels and juvenile hens, estrogen reduces lipid incorporation in fat depots by enhancing apo-VLDL-II production that reduces plasma and ATT LPL activity. This may increase lipoprotein available for incorporation into developing yolks. The lack of estrogen in OFC hens reduces circulating apo-VLDL-II and thus increases LPL activity and amount of fat depots.

1. The administration of the anti-oestrogen, tamoxifen (TAM) to juvenile chicks results in precocious puberty. In the present study the effects of TAM administration (1 mg/kg body weight on alternate days from 12 d of age) on testicular function, hypothalamic chicken gonadotropin-releasing hormone (cGn-RH-I), plasma luteinising hormone (LH), growth hormone (GH), prolactin (PRL) and testosterone were studied in juvenile White Leghorn cockerels. 2. The increase in hypothalamic GnRH-I content which occurs during sexual development was advanced in TAM-treated birds, in association with precocious testicular development, an early rise of plasma testosterone content and enhanced comb growth. 3. Plasma LH concentrations behaved similarly and were higher in the TAM-treated than in control birds, during most of the experimental period. Plasma PRL concentration, which is high at hatching, decreased more quickly in TAM-treated than in control birds; plasma GH values were not consistently affected by TAM treatment. 4. Both the growth and the involution of the bursa of Fabricius in the TAM-treated cockerels preceded that in the control chicks. 5. It is concluded that TAM treatment induces precocious puberty in the cockerel by blocking the negative feedback action of aromatised testicular androgens on the hypothalamus.

1. Embryonic injections of 0.3 mg/egg of tamoxifen (TAM), 0.2 mg/egg CI‐628 (both antioestrogens), 0.5 mg/egg (ATD (aromatisation inhibitor), or antibodies to oestradiol (E), all suppressed male copulatory activity (MCA) in young male chicks. 2. Embryonic injections with either flutamide (F, androgen antagonist) or high dose of antibodies to testosterone (T) only slightly suppressed MCA. 3. TAM had no effect on embryonic plasma LH levels, 24 and 48 h after injection. 4. It seems that at the embryonic stage oestradiol is required for the normal differentiation of MCA.

In order to study the role of sex steroids in the differentiation of chick behavior, two groups of experiments were carried out. The first part of the study documented sexual dimorphisms in three behavioral measures in chicks: open-field activity, flocking response, and masculine sexual behavior activated by testosterone (crowing, waltzing, and mating attempts). In the second part, possible organizing influences on these sexually dimorphic behaviors were examined. Male and female embryos were injected with estradiol benzoate (EB) or testosterone propionate (TP). Treatment of males with EB or TP demasculinized all three behaviors. None of the steroid treatments had any effect on the behavior of the females. Plasma testosterone levels of the chicks were not affected by any of these treatments, either before or after testosterone activation. Comb weight was reduced by treatment of male embryos with EB and increased by TP in female embryos, which suggests different mechanism for the development of somatic and behavioral characteristics. The results suggest that exogenous T or E given embryonically can exert similar effects on both sexual behavior and nonreproductive activity of chicks.

1. The effects of early exposure of heavy breed (HB) chicks to an anti‐oestrogen (tamoxifen—TAM) and to an androgen which cannot be aromatised (5α‐dihydrotestosterone—DHT) on subsequent adiposity and its response to testosterone were studied. 2. Embryonic TAM administration reduced adiposity in females but not in males at 8 weeks of age. Embryonic DHT produced similar responses but to a lesser extent. 3. Testosterone propionate (TP) administration during growth had no effect on adiposity in any of the treated groups but TP reduced adiposity in males which had been exposed to DHT at the embryonic stage.

1. Four methods of semen collecting that involved interruption of mating in two breeding ostrich pairs were tested: an artificial vagina was tested without promising results; the funnel method, in which a funnel was placed under the phallus of the tested male immediately after mating allowing semen drips to be collected; the vacuum method, using a turkey semen collector, inserted into the seminal canal; and the tube method, conducted by placing a test tube inside the seminal canal, allowing semen to enter by gravity. 2. For the funnel, vacuum and tube methods, respectively, average semen volume was 0.1 +/- 0.02, 1.12 +/- 0.22, and 0.58 +/- 0.13 ml, sperm concentration was 0.66 +/- 0.14, 2.35 +/- 0.26, and 2.13 +/- 0.27 x 10(9) cells/ml, and percentage of abnormal cells was 5.82 +/- 1.79%, 4.68 +/- 1.19%, and 7.09 +/- 1.72%. 3. Semen characteristics varied throughout the reproductive season reaching peak concentration in June-July. 4. The vacuum method proved to be the most efficient and was a low stress, restraint-free method for collecting ostrich semen.

The effects of glucocorticoids (GC) on embryonic mortality and posthatch BW were studied. Cortisol hemisuccinate or corticosterone in 0.1-mL vehicles were injected into the albumen of 7-d-old White Leghorn chicken embryos. Embryonic mortality rates and the age after injection at which death occurred were determined. When 0.02 to 20 microg cortisol per egg were injected in saline, total embryonic mortality rate increased in a doseresponse manner, with a median lethal dose (LD50) at 10 microg. Saline injection alone caused a similar mortality rate to that caused by injection of 2 microg cortisol (around 35%). However, whereas mortality among the cortisol-treated embryos was greatest on Days 16 to 18, most of the saline-treated embryos died around the time of injection. The lethal effect of corticosterone, which is endogenous GC in adult chickens, was compared to that of cortisol by injecting both in the same vehicle (a saline:ethanol mixture) and was found to be similar. However, when 2, 10, or 20 microg of corticosterone was injected in oil, mortality rates were lower than those caused by the matching doses of cortisol in saline, probably due to the lower diffusion rate of the steroid out of the oil carrier. Hatch weight was significantly lower in chicks treated with 10 and 20 microg cortisol, and BW of the latter was lower compared with control throughout the 3-mo observation. In conclusion, cortisol and corticosterone are equally active in causing embryonic mortality. Posthatch BW is affected only by GC doses that are equal to or greater than the LD50.

Prolonged stress inhibits the hypothalamus–pituitary–gonadal (HPG) axis and reduces plasma testosterone (T). However, enhanced secretion of luteinizing hormone (LH) and T has been documented during the initial stages of acute stress in mammals. This study assayed the effect of short-term stress on plasma T and corticosterone (B) in juvenile, pubertal, and adult White Leghorn cockerels. Stress was induced by brief physical restraint of caged juvenile (7 weeks), pubertal (17 weeks), and adult (40 weeks) cockerels, as well as 40-week-old adults reared together in a room lined with wood shavings (group reared). Blood was sampled immediately before restraint (0 time), at the end of a 10-min restraint period, and at 30, 60, and 180 min after 0 time. Restraint resulted in an initial increase in plasma T in all groups, along with a rise in B. Whereas B generally reached its peak level at the end of the restraining period, T peaked 20 min later. The maximum increase of T and B relative to prestress levels (T and B ratios) was similar in all groups, with median T ratio reaching 1.25–1.5—about half that of the B ratio. Thus, the extent of T and B response to short-term stress was not influenced by basal levels of T, which were highest in adults, and basal levels of B, which were higher in caged adults than in group-reared adults. Injection of ACTH did not induce a greater increase in plasma T than in sham-injected controls. Further, the elevation of T in response to stress was extinguished in castrated adults, indicating that T is secreted from the testes rather than the adrenals in response to stress. When the same regime of blood sampling was applied to adults not subjected to restraint, the T ratio rose by up to 11 times. It can therefore be stipulated that T response depends on the type of stress applied, a factor that should be considered when investigating androgen levels in plasma.

The effect of intracerebroventricular (i.c.v.) injection of corticotrophin releasing factor (CRF) on food and water intake and on body temperature in chickens was determined. Both broiler and Leghorn type chickens were utilized in this experiment. A stainless steel guide cannula was surgically implanted into the right lateral ventricle of each bird. The i.c.v. injection of CRF significantly decreased food intake in both fed and overnight-fasted broilers and Leghorns. Water intake was decreased by CRF in Leghorns but not broilers. When CRF was injected into Leghorns given access to water, but not food, water intake was not affected. Body temperature was not affected by the i.c.v. injection of CRF. These results suggest that CRF acts within the central nervous system of chickens to decrease food intake while having no affect on water intake or body temperature.

Tamoxifen (TAM) is an antiestrogen that advances sexual puberty in cockerels, turkey toms, and Muscovy drakes. The effect of TAM on semen-fertilization capacity in White Leghorn (WL) male chicks was assayed in the present study. Sixty, 2-wk-old, male chicks were divided into two equal groups. The chicks from one group were injected im with 1 mg of TAM per kg of BW every other day, those from the second group were vehicle-treated (with corn oil) and served as controls. Each chick was paired with a virgin, WL laying hen. When semen was produced, the paired female was inseminated twice a week. The results revealed that TAM administration caused the early production of fertile semen, which resulted in the first normal descendants as early as 8 wk of age arid brought about 100% of parenthood by the age of 88 days.

The effects of Tamoxifen (TAM) on reproductive traits in young turkey toms and Muscovy drakes were studied. At 6 wk of age, five toms were injected every other day with 1 mg TAM/kg BW, while six others were treated with corn oil (controls). In the toms, using TAM advanced semen production by 4 wk (13.5 versus 17.5 wk of age) and increased the size of the snood and testes. Similarly, in the Muscovy drake, using TAM enhanced penis growth and advanced semen production by 5 wk.

1. Mule ducks were produced by naturally mating Muscovy drakes and Khaki Campbell ducks. 2. Semen was collected from 6-month-old mule drakes via an artificial vagina. The fluid was clear without any spermatozoa or spermatids. 3. Testes from 27-week-old mule drakes were smaller in size than those of Khaki Campbell drakes but heavier than Muscovy males of the same age. Histological sections of these testes revealed that spermatogenesis was not complete. 4. Testosterone concentration in the mule drakes was higher than in Muscovy males but similar to Khaki Campbell drakes. 5. Mule drakes have strong sexual drives as a result of high concentrations of testosterone, but, because spermatogenesis is incomplete, their semen had no sperm.

The present study examines the effects of intermingling day-old broiler chicks with 2-wk-old light strain chicks, on body weight, general activity, feeding behavior, feather condition, and heart size of the broilers. Fifteen groups of chicks (five for each treatment) were raised until 6 wk of age in 1 x 2 m experimental pens. Each group consisted of 10 broiler chicks in Treatment 1 (control pens), 8 broiler, and 2 light strain chicks in Treatment 2 (8:2), and 5 broiler with 5 light strain chicks in Treatment 3 (5:5). The feeding program consisted of a commercial starter ration (21% protein, 3,000 kcal ME/kg) for the first 4 wk followed by a finishing ration (18% protein, 3,150 kcal ME/kg). Feed and water were provided for ad libitum consumption. Body weight did not differ between Treatment 1 (controls) and the "intermingled" broilers. Feather condition was significantly poorer among the 5: 5 groups than in the controls. Heart weight (a possible indicator of chronic stress) in broilers of the 5:5 groups was significantly heavier than in the controls. No differences in the general activity parameters were found between broilers of the various treatments. Pecking at feed among broilers was significantly greater (P < 0.05) in the 8:2 groups than in both control and 5:5 groups. During the first 6 wk after hatching, intermingling broiler chicks with equal numbers of light strain chicks that are 2 wk older may lead to long-term chronic stress for the broilers.

In White Leghorn hens, basomedial hypothalamic (BMH) lesions result in two syndromes: a) obese, functionally castrated (OFC) hens, in which both the ventromedial hypothalamic nucleus (VMH) and the mammillary nuclei are damaged and plasma estrogen is very low; and b) obese laying (OL) hens, which have normal levels of plasma estrogen and are less obese than the former, and whose lesion is limited to the VMH. In the present study, the involvement of estrogen in regulation of fattiness and energy metabolism was assayed in OFC, OL, and control (CONT) hens. BMH lesions were made at 13 weeks of age. When the typical syndromes reached the static phase, 20 weeks later, CONT, OFC, and OL hens were divided into three subgroups and were injected for 10 weeks on each alternate day, with either 10 mg tamoxifen (TAM)/kg, 2 mg estradiol benzoate (E2)/kg, or the vehicle, corn oil (0.5 ml). E2 raised plasma total lipids and reduced plasma glucose, insulin, and hematocrit in all treated hens, and increased liver weight in OL and OFC, but not in CONT hens. In OFC hens only, E2 reduced food intake (FI) and fattiness. In OL and CONT hens, E2 increased plasma T3, but raised the resting metabolic rate (RMR) only in CONT ones. In OFC hens, E2 reduce plasma T3 and T4 without affecting RMR. E2 reduced comb weight and egg production in CONT and more severely in OL hens. In the latter, E2 diminished ovarian and oviduct weights, whereas in OFC hens it increased the size of the atrophied oviduct. TAM had no visible effect on OFC hens. However, in CONT and OL pullets, TAM decreased plasma total lipids, FI, liver, and ovarian and oviduct weights, abolished egg production, increased plasma glucose, insulin, T3 and T4, RMR, hematocrit, and comb weight, but had no effect on fattiness and body weight. It is well established that estrogen increases fattiness in cockerels and juvenile pullets. However, in adult hens in the present study, estrogen and its antagonist had no effect on fattiness in the laying ones, and even reduced body fat in the OFC hens. These results suggest that in hens, E2 effects on fattiness alter with age. As E2 increased plasma lipids in all hens, it may be assumed that in adult hens E2 reduces fat deposition in depots to increase its availability for yolk production.

During the last three decades, syndromes caused by bilateral destruction of the basomedial hypothalamus (BMH) were extensively studied in cockerels but not in hens. In the present study bilateral electrolytic lesions in the BMH of White Leghorn (WL) hens produced two main sets of symptoms: (a) Obese, functionally castrated hen (OFC); and (b) Obese, laying hen (OL). Following the placement of the hypothalamic lesion, the OFC hens developed transient hyperphagia, that was followed by hypophagia. Weight gain was accelerated in both periods, and marked obesity developed. These hens had high hematocrit values, and atrophied ovary, oviduct, comb, and adenohypophysis. Plasma estrogen, androgen, and total lipids and liver weight were reduced in the OFC hens. In these hens, the lesioned area included the ventromedial hypothalamic nucleus (VMH), the mammillary nuclei, and in some birds also the arcuate nuclei, and the tuberal nucleus. The OL hens manifested transient hyperphagia that subsided into normophagia with the development of obesity. These hens were less obese than the OFC ones and showed normal reproductive traits. The lesioned area in the OL hens was limited to the VMH. Unlike functionally castrated cockerels, where the induced fattiness is accompanied with higher rate of lipogenesis, the OFC hen manifested a unique syndrome: increased fattiness with arrest in estrogen-dependent lipogenesis.

The effect on aggressive pecking activity and mortality by an environmental enrichment device was examined. In this study, 2955 White Leghorn chickens from three different lines were used in six separate experiments. Experiments were conducted with chickens during their first or second laying period. Half the cages in each experiment were equipped with colored key rings or an enrichment object manufactured by Gallus Ltd. (Israel). Experimental and control groups of cages were distributed in an alternate serial order for each experiment which lasted for 3, 4, 5, 8, 9, and 10 months. The enrichment devices significantly reduced aggressive head-pecking behavior and significantly decreased the mortality rate from 1.06% per month among the controls to 0.57% among the experimental groups.

1. Tamoxifen (TAM) administration advances puberty in cockerels. In the present study the effect of TAM administration on the sexual development of White Leghorn hens was studied. 2. Two-week-old White Leghorn females were injected intramuscularly with TAM on alternate days at doses of 0.1 mg (0.1 TM), 1 mg (1TM), 5 mg (5TM) and 10 mg/kg body weight (10TM) respectively, while the controls were injected with maize oil (vehicle). The experiment was terminated at 23 weeks of age, when all the control hens laid eggs. Sample autopsies were made on chicks of 6, 14 and 23 weeks of age. 3. Body growth was not affected by any of the treatments. 4. Comb growth was accelerated by all doses of TAM, while hematocrit increased in the 1TM, 5TM and 10TM hens. 5. Egg laying advanced in the 0.1TM and 1TM birds, was delayed in 5TM hens and did not occur at all in the 10TM females. 6. TAM caused a precocious increase in plasma oestrogen and androgen, suppressed adiposity in a dose-related manner and, at low doses, advanced the development of the gonadal system. 7. At 23 weeks of age, when the gonadal system of the controls was fully active, TAM caused a dose-related depression in abdominal fat, liver, ovary, and oviduct weights, plasma total lipids and calcium concentrations and a dose-related increase in plasma oestrogen and androgen titres, and comb weight. 8. It seems that TAM increased gonadotropic activity and its androgen stimulating action, but suppressed peripheral signs of the elevated plasma oestrogen titres. Low doses of TAM enhanced gonadotropic activity and egg laying but the antioestrogenic effect depressed development of the gonadal system, suppressing egg production when high doses were administered. It therefore seems that oestrogens are necessary for normal ovarian development in hens.

Studies were conducted to determine if sex differences in embryo weights existed in a light-weight breed of chickens (the Single Comb White Leghorn, SCWL) and in a heavy broiler strain of chickens. Plasma thyroid hormone concentration was measured to determine its relationship to embryo weight. Male SCWL embryos were heavier than females at 15 and 17 days of incubation, but not at 13 days. Male broiler embryos were heavier than females at 13 and 15 days of incubation, but not at 17 days. There was no sex difference in the levels of plasma triiodothyronine (T3) or of tetraiodothyronine (T4) of SCWL embryos at those respective ages. The plasma T4 in male broiler embryos was significantly lower man that in the females at 15 and 17 days of incubation, but not at 13 days. There was no relationship between plasma T3, and the weight of SCWL embryos. There were significant linear regressions of embryo weight on the plasma T4 levels for SCWL males at 13 and 15 days of incubation and for SCWL females at 13 and 17 days of incubation, respectively. A significant regression of embryo weight on plasma T4 was found in female broiler embryos at 13 days of age, but not in females at other ages or in males at any of the ages studied.

Tamoxifen (TAM) is an antiestrogen that advances sexual puberty in cockerels, turkey toms, and Muscovy drakes. The effect of TAM on semen-fertilization capacity in White Leghorn (WL) male chicks was assayed in the present study. Sixty, 2-wk-old, male chicks were divided into two equal groups. The chicks from one group were injected im with 1 mg of TAM per kg of BW every other day; those from the second group were vehicle-treated (with corn oil) and served as controls. Each chick was paired with a virgin, WL laying hen. When semen was produced, the paired female was inseminated twice a week. The results revealed that TAM administration caused the early production of fertile semen, which resulted in the first normal descendants as early as 8 wk of age and brought about 100% of parenthood by the age of 88 days.

The effects of Tamoxifen (TAM) on reproductive traits in young turkey toms and Muscovy drakes were studied. At 6 wk of age, five toms were injected every other day with 1 mg TAM/kg BW, while six others were treated with corn oil (controls). In the toms, using TAM advanced semen production by 4 wk (13.5 versus 17.5 wk of age) and increased the size of the snood and testes. Similarly, in the Muscovy drake, using TAM enhanced penis growth and advanced semen production by 5 wk.

The effect of heat stress on capillary blood flow (CBF) distribution was examined in laying hens, using 15 micron microspheres, by determining CBF before and after elevating body temperature by 1-2 degrees C. No changes was evident in unfeathered metatarsal skin, although its temperature increased by 7 degrees C. Breast skin CBF change was 3.5 times larger than that of back skin. Comb CBF increase was larger than in wattles. CBF in upper respiratory tract increased proportionally to increment in respiratory frequency. Digestive system CBF was reduced by hyperthermia: the effect was pronounced in its upper organs (46% of normal) and decreased along the tract. CBF increased 4-fold in an expiratory abdominal muscle, a smaller rise occurred in a pectoral muscle and no change in a leg muscle. CBF in the tibia fell to 64% of normal. In the reproductive system, CBF fell to 58% of control level in the uterus, to 70-80% in the larger ovarian follicles and infundibulum with no significant changes in magnum and isthmus. Cerebral CBF increased during hyperthermia. Heat stress significantly reduced CBF to inner body organs, with marked differences between systems as well as within systems. Changes were more pronounced on 2 degrees C hyperthermia than on 1 degree C hyperthermia.

The effect of light color on egg-laying and on egg quality during the first 50 wk of egg production and during a second cycle of 19 wk following molting was examined. Hens were exposed to one of the following six sources of light: blue (B), green (G), red (R), tungsten (T), cool-white (C) fluorescent or simulated-sunlight (V) fluorescent tubes. Light intensity was equalized at photon output. Total egg production per hen was significantly influenced by the color of light with the most eggs being procuced in R light and the fewest in B light. Hens were more sensitive to light color in response to egg production during the second cycle than during the first cycle. Hens in C light produced significantly fewer eggs than those under V light in both laying cycles. Eggs laid under B or G light were consistently larger than those under R light. Egg weights of hens in V light were heavier than those for the C or T light groups. In the first cycle, shell quality was significantly better in G light than in B or R light. Percent of yolk increased and percent of albumen decreased with age during the first cycle in all treatments and the rate of change was directly related to light color (wavelength). In the second cycle, shell quality, percent of shell, yolk and albumen did not change significantly with age in any of the light treatments. It can be concluded that the wavelength of light may influence egg production, egg components and shell quality of the domestic laying hen.

Bilateral basomedial hypothalamic (BMH) electrolytic lesions in White Leghorn cockerels produced six main physiological categories characterized by typical sets of symptoms: 1) functional castration (FC); hyperphagia, obesity, occasional diabetes insipidus, involuted adenohypophysis, dwarfism, atrophied comb and testes, reduced hematocrit, reduced plasma testosterone and thyroid activity, involuted thymus and adrenal cortex and elevated liver fat and plasma triglycerides and free fatty acids. The FC birds demonstrated defective immune response for the first 12 to 16 wk post-surgery. 2) functional castration with large comb (FCLC); hyperphagia, obesity, transient diabetes insipidus, slight diminution of adenohypophy-seal weight with marked reduction in basophilic cell population, fully atrophied testes but only slight reduction in comb size and hematocrit, plasma testosterone levels between those found in the first category and the control. 3) obese with normal testes (ONT); hyperphagia, obesity, high level of plasma lipids, normal histological organization of the adenohypophysis, normal testes, semen production and comb size. The next three categories exhibited physiological syndromes identical to the former three categories except for food intake, which operationally could be defined as normal. A marked difference among the BMH-lesioned birds was found in sexual behavior when the FC birds completely lost their libido. None of the replacement therapy regimens caused complete rehabilitation from adiposity or restoration of reproductive traits. Lipoprotein lipase activity increased at an early stage postlesioning and preceeded the development of hyperphagia. Placement of BMH lesions in newly hatched chicks resulted in marked dwarfism and obesity without hyperphagia. The BMH-lesioned heavy breed White Rock cockerels exhibited a lesser degree of adiposity than the light White Leghorn birds. Removal of the olfactory bulbs and destruction of the septal area resulted in increased thyroid activity, with secondary hyperphagia without obesity. In a short-term study, administration of sodium pentobarbital to the BMH area resulted in increased feeding. Conversely, glucose administration to the same area suppressed feeding in satiated but not in food-deprived chickens.

Synopsis Two types of modified cockerels were produced by lesioning the hypothalamus: (1) functionally castrated, obese, with atrophied testes and combs, bearing lesions in the mammillary nuclei and posterior part of the ventromedial nuclei (FC) and (2) functionally castrated, obese, with atrophied testes, but with large combs, bearing lesions in the posterior part of the mammillary nuclei and part of the arcuate nuclei (FCLC). Semen could not be obtained from either type of bird. Plasma testosterone concentrations, determined by radio‐immunoassay, were 25.5 ± 5, 125 ± 20 and 508 ± 272 ng/100 ml plasma, for the FC, FCLC and control birds respectively. Correlations were not found between comb weight and testosterone concentration within each of the different groups. Neuroendocrine aspects and some physiological effects of androgenic activity are discussed in the light of previous studies with similarly lesioned cockerels.

The detachment process of the domestic chick from its mother, or any other imprinting object occurs between the sixth and tenth week after hatching. The present study (Experiment I), examines whether the detachment process parallels endocrine events that precede prepuberty. Immediately upon hatching, groups of heavy strain chicks were imprinted to a colored foam rubber ball for 72 hours. The bond between these chicks and the imprinting object was then tested, and plasma LH and testosterone were assayed once a week until the chicks were 10 weeks of age; the sexual development of chicks of the same strain was studied at the same time. At the outset of the detachment period (5–7 weeks) an increase in plasma testosterone and a decrease in plasma LH was found. In addition, the comb and testes showed a definite weight increase while the bursa of Fabricius showed a significant decline in weight. In Experiment II, the beginning of the detachment process was induced by injecting 3 to 4 week old chicks with testosterone-propionate, estradiol-benzoate and 5α-dihydrotestosterone. Our evidence therefore appears to demonstrate that testosterone and its metabolites induce the detachment process by the same mechanism used to stimulate sexual behavior in juvenile chicks.

Female chicks of an egg-laying strain were irradiated (.6 μE photons/m2/sec) from day-old to termination of the experiment at 672 days of age with narrow-band blue (B), green (G), or red (R) fluorescent light, or with white light from cool white (C) or sunlight-simulating (V) fluorescent tubes or from tungsten (T) incandescent lamps. The effect on initiation of egg laying by juvenile hens and on renewal of laying after molting was studied. There was no significant effect of light source on average days to first egg for initiating egg production. After molting, it took an average of 45, 28, and 16 days for hens in the B, G, and R groups, respectively, to begin to lay after light stimulation. The C group started to lay again after 32 days as compared to 19 and 21 days for the T and V groups. The relative weights of the abdominal fat of maturing hens under the monochromatic treatments were in inverse ratio to wavelength. There was no difference between the wide-spectrum sources. At a given level of photon irradiation, light quality was not a factor in the initiation of egg production but influenced renewal of egg laying following molting in the domestic hen. Light quality may also be involved in fat metabolism prior to maturity.

Effects of the thyroidal state on certain immunological parameters were studied in four groups of male White Leghorn chicks. One group was fed with commercial chick mash and served as control, the second was supplemented with 0.1 % Propylthiouracil (PTU) in food, the third was supplemented with 0.025 % thyroxine in food, and the fourth was supplemented with 0.1 % PTU and 0.025 % thyroxine. Treatment with PTU (29 days) resulted in hypothyroidism evidenced by low T4 level, decreased oxygen consumption rate and decreased weight gain. Thyroxine treated group reached hyperthyroidism shown by high T4 level and increased oxygen consumption rate. When all chicks were immunized with SRBC, hemagglutinating antibody titer of PTU treated group was significantly lower than that of the other group while thyroxine treatment resulted in increased, but statistically not significant titers. At 36 days of age the chicks were killed. PTU treated group exhibited decreased thymus, spleen and bursa weights and low 3H thymidine incorporation after Con A stimulation of both spleen and thymus cells. Thyroxine treatment resulted as well in low 3H thymidine incorporation. These findings indicated that hypothyroidism depressed the immunological system, while hyperthyroidism had no effect on antibody formation but depressed reactivity to Con A stimulation.

This study examines different types of attachment measurements and pecking behavior in group-reared domestic chicks imprinted to a silent imprinting object. Immediately upon arriving from the hatchery, groups of heavy strain chicks were imprinted to a colored foam rubber ball for 72 h. The bond between these chicks and the imprinting object was then tested from 8 days until 5 weeks of age. Three days of imprinting sessions demonstrated that a strong attachment could be formed between the imprinted chicks and the imprinting object. In both experimental and control groups, the number of pecks was found to be significantly correlated with the latency measurements. It is, therefore, reasonable to consider the number of pecks of the imprinting object as another measurement for filial attachment.

An improved method for obtaining semen from the Muscovy drake using an "artificial vagina" was developed and employed on a commercial scale. With such a procedure, the ejaculate volume was 1.12 +/- .85 ml, semen concentration was 1.35 +/- .43 X 10(9) cells/ml with 8.6 +/- 6.3% abnormal sperm cells. Average spermatozoal motility was graded as 3.59 +/- .93 on a scale of 0 to 5 and the initial pH was found to be 7.30 +/- .23 within 5 min of ejaculation.

Surgical removal of the olfactory bulbs (O.B.) in the chicken caused a marked increase in food intake, which was not accompanied by development of obesity. Oxygen consumption of the O.B. removed birds was significantly higher than that of the controls. Alcianophylic-thyrotropic cell population of the adenohypophysis and the percentage of active follicles in the thyroid gland were higher for the O.B. removed birds than for those of the controls. Feed supplementation of 0.1% propylthiouracil to the O.B. removed birds abolished the previously exhibited hyperphagia and caused a significant decline in oxygen consumption. The possibility that the O.B. removal caused a primary increase in thyrotropic axis activity followed by a secondary compensatory hyperphagia, is discussed.

The leaning role, previously suggested for testosterone in chickens, was tested in males and females of fatty and lean breeds. The breeds used were the White Leghorn (WL), of which the male is very lean, and the White Giant (WG) and the White Cornish X White Rock (WCWR), in which both sexes accumulate fat. Castration of WL males induced adiposity and replacement therapy with testosterone propionate (TP) reduced the fat to normal. However, in males of the fatty breeds, neither castration nor TP administration had any effect on adiposity. Similarly, long-term supplementation of a high dose of TP had no effect on the level of adiposity in females of both the heavy and the light breeds. Thus, the leaning effect found for testosterone in the WL male is not a general phenomenon in chickens but rather a specific response of the WL male.

Placement of electrolytic lesions in the septal area (S.A.) in chickens caused a marked increase in food intake which was not accompanied by development of obesity. Oxygen consumption of the S.A. lesioned birds was significantly higher than that of the controls. Alcianophylic-thyrotropic cell population of the adenohypophysis and percentage of active follicles in the thyroid gland were higher for the S.A. lesioned birds than for those of the control birds. The S.A. lesions caused also an increase in the somatotropic activity. The possibility that the previously found suppression effect of the olfactory bulbs on the thyrotropic and somatotropic activities in the intact chicken is mediated via the S.A., is discussed.

1. 1. Blood flow distribution was examined in 12 normothermic laying hens by microspheres injected via the brachial artery into the root of the aortic arch above the aortic valves. 2. 2. Double reference sampling (brachial and sciatic) accounted for uneven microsphere distribution between upper and lower body arterial flows. 3. 3. This easily accessible injection site yielded results comparable to those attained by left atrial injections. 4. 4. Blood flow (ml/min g tissue) was highest in the spleen (8.2); intermediate in the brain, kidneys. adrenals, liver, follicles (1.1–3.1); below 0.5 in the skin. muscle, respiratory tract and post ovulatory follicle. Hyperthermia markedly changed this order.

Electrolytic lesions of the baso-medial-hypothalamus (BMH) cause numerous dysfunctions of the endocrine system, many of which have been implicated in regulating immune responses. The objective of this report was to evaluate the direct effects of electrolytic lesions in the BMH on the immune response of the chicken. Our results indicate that temporary immune response impairment, as evaluated by both T and B lymphocyte related responses, occurred only in birds that expressed both brain damage and endocrine dysfunction, whereas birds expressing brain damage alone had normal immune responses. The possible regulation of immune responses by the BMH via the endocrine system is discussed.

Reproductive traits and histology of the adenohypophysis were studied in adult White Leghorn cockerels after surgical thyroidectomy or .1% propylthiouracil (PTU) food supplementation. Both treatments caused hypothyroidism as judged by a marked reduction in plasma thyroxine levels, a decrease in resting metabolic rate values, an increase in liver and adipose tissue weights, and a marked elevation in the alcianophilic cell population in the adenohypophysis. Both the PTU-treated and thyroidectomized birds demonstrated reducted testes and comb weights. However, although thyroidectomy was found to increase the number of PAS-positive cells in the adenohypophysis, the PTU treatment reduced them. This phenomena is discussed.

An x-ray atlas of the sagittal plane of the chicken diencephalon, which enables a more precise placement of electrolytic lesions, or the implantation of cannulas and electrodes, was constructed. The localization of brain sites is accomplished on the horizontal and vertical planes only; for the lateral plane coordinates, a previously published complementary atlas is required. A high correlation was found between stereotaxic coordinates and the anticipated locations of electrolytic lesions. A procedure is described, which utilizes radiography with two reference points to determine and facilitate the use of specific brain coordinates.

Intravenous injection of Ang II (val5 angiotensin II amide) elicited an immediate drinking response in the domestic fowl which lasted at least 20 minutes. The minimal dosage needed was 300 μg. Intracranial injection of 10 μg Ang II through cannulas implanted in the anterior diencephalon caused a significant increase in water intake. The minimal intracranial dosage of Ang II which evoked drinking was 2.5 μg. Intracranial injection of isotonic KCl inhibited the drinking response induced by intravenously injected Ang II when administered simultaneously. This suggests that drinking caused by both intravenous or intracranial injection of Ang II is activated through identical brain regions. The positive drinking response of the chicken to repeated consecutive intracranial injections of Ang II declined from the first injection through the following ones.

1. Mature laying hens were subjected to ambient temperatures sufficient to maintain body temperature of 43 degrees C for periods of 6 to 7 h during the day (eight periods) or the night (five periods). This did not reduce total daily food consumption. 2. The effect of heat stress during the day was mostly on egg-shell quality, being adverse and significant. During the night heat stress caused a significant decrease in egg production, its effect during the day was less marked in this respect. 3. Heat stress thus seems mostly to affect the early stages of shell formation, while its effect on egg production seems to depend on the time at which it occurs in relation to ovulation. 4. These results suggest that egg production is directly affected by heat stress; prolonged heat stress probably also acts indirectly, by suppression of food intake.

Synopsis 1. Resting metabolic rate (RMR) and fasting metabolic rate (FMR) were periodically determined, using an open air circuit master system, from January to September in 10 White Leghorn, 10 Plymouth Rock and 20 New Hampshire × White Leghorn mature laying birds fed ad libitum. 2. The relationship of metabolic rate (l.O2/hr.) to body weight (kg.) in the pooled data followed the 0.795 W0.61 equation for the fasting level, and 0.916 W0.59 for the resting level. The expression of metabolic rates as litres oxygen per kg. body weight can lead to serious errors if birds of differing body weights are compared. 3. Heat increments of feeding (estimated by RMR‐FMR) gradually increased with rising environmental temperature, with only slight initial change in the FMR, followed by marked reductions in both the FMR and the RMR at the higher temperatures. It is suggested that a decrease in the FMR may allow for a reduction in the RMR in the hotter season, without this necessarily being linked with a depression in the...

Lesions in the anterior hypothalamic area of chickens impaired temperature regulation in hot environments by abolishing the panting reflexes and by annulling the behavioristic response which consists of the movement of the wings away from the poorly insulated undersurfaces of their bodies to facilitate the loss of heat by radiation, convection and conduction. In the cold, the lesions impaired heat production by abolishing the shivering reflex; however, many chickens retained their ability to fluff their feathers to conserve body heat. Disturbances in temperature regulation differed among the chickens: five did not regulate body temperature at 70°F; ten regulated at 70°F but not in the hot or cold; two regulated in the cold but not in the hot; and two regulated in the hot but not in the cold. At normal body temperatures seven ate and drank normally; four were adipsic; and three were both aphagic and adipsic. One chicken, though hyperthermic, kept on eating instead of reducing its food intake as do intact chickens in hot environments. Chickens that ate normally when their body temperatures were normal reduced their food intake when they became hypothermic (98–100°F); some ate moderately and some ate little or no food. Restoration of normal body temperature restored normal food intake. When body temperature dropped to 94°F or lower, chickens, although interested in food, ate little or none; cessation of eating was accompanied by failure of food to leave the crops, due, in all probability, to failure of intestinal peristalsis. The thermoregulatory function of the hypothalamus seemed to influence the use to which the food was put, whether for the production of heat or for the production of tissue substance (fat) leading to gain in weight or for activity. Hypothermic chickens stood quietly and usually fluffed their feathers to conserve heat. At body temperatures of 87°F or lower, chickens could no longer stand and became torpid.

In vitro 131 I l -triiodothyronine ( l -T 3 ) erythrocyte-uptake test was compared with oxygen-consumption determinations, thyroid 131 I uptake, and thyroidal weights in cockerels of two different breeds in order to evaluate the significance of the first test as a reliable method for estimating thyroid activity. Hyperthyroidism and hypothyroid states were produced by feeding of 0.05% thyroprotein and 0.1% propylthiouracil, respectively. While the oxygen consumption, thyroid weights, and thyroid 131 I uptake showed a clear response in accordance with the treated birds, no such effect was obtained with regard to the in vitro 131 I l -T 3 erythrocyte-uptake test. No differences in this respect could be noted between the two breeds studied. It is suggested that the lack of a specific thyroidal compound binding protein, which is known to be one of the principal differences between mammalian and avian sera, may be the cause of this phenomenon.

In both young and old laying hens the protein-bound calcium fraction in blood plasma decreased following feed supplementation of 0.05% thyroprotein, whereas the plasma alkaline phosphatase activity significantly increased. The enzyme response was found to be delayed in old as compared to young hens, significantly higher absolute levels being found in the latter. Propylthiouracil treatment caused a marked decrease in protein-bound calcium levels and alkaline phosphatase activity in both young and old hens. The uterine calcium levels and alkaline phosphatase activity in the thyroprotein treated birds did not show any significant differences as compared to the controls, except in the group of old hens receiving the highest dose, in which the calcium level was significantly decreased and the enzyme activity significantly increased. Both propylthiouracil treated groups showed a significant decrease in uterine calcium and alkaline phosphatase activity.