Single Comb White Leghorn Cockerels Research Articles

Effect of Lactobacilli in the Diet on the Concentration of Nitrogenous Compounds and Minerals in Blood of Chickens

The concentrations of nitrogenous compounds and minerals in blood of 90-to-100-day-old Single Comb White Leghorn cockerels were investigated by feeding on a diet (31.3% crude protein) with Bacillus coagulans or Lactobacillus casei at 105, 107, 108 or 109 level, respectively, for 13 days. The results obtained are summarized as follows:1. Feeding of the diet added either of both bacteria at 107 or more levels resulted in the increase of total nitrogen and decrease of non-protein nitrogen at significant level. The concentrations of uric acid, ammonia and urea were tended to decrease after feeding of the diet added bacteria.2. The concentration of sodium was decreased by feeding of the diet added Lactobacillus casei, but not Bacillus coagulans. The concentration of potassium was decreased and that of calcium and magnesium was increased by feeding of the diet added either of both bacteria, but that of phosphorus was unchanged.

The Effect of Melatonin on LH-RH Induced Changes in Pituitary and Gonadal Function of Immature Domestic Fowl1

Single comb White Leghorn cockerels received daily subcutaneous injections of 100 �zg melatonin at 1700 h from age 2- through 13-days (LD 14:10; lights on at 0530). Groups of animals then received a single subcutaneous injection of 2.5 �og LH-RH (age = 14-days) at different times before autopsy. Testicular response was assayed by the testicular uptake of 3 2 P (administered carrier-free). Melatonin inhibited the LH-RH induced increase in 32 P uptake by the testes. Gonadotrophin bioassays of the anterior pituitary glands from treated animals showed that during the first 90 mm of LH-RH availability the pituitary gonadotrophin levels decrease, possibly indicating the release of gonadotrophic hormones. Then, during the following 30 mm and possibly longer, the pituitary gonadotrophin levels increase, possibly indicating the synthesis of new quantities of gonadotrophin. A mechanism to explain these results is proposed.

Release of gonadotropin from the anterior pituitary gland of fowl by LH-RH as measured by the 32P uptake of the testes

Single comb White Leghorn cockerels received LH-RH in varying dosages at different time periods. The uptake of 32P by the testes was the end-point of the assay. Dosages as low as 0.06 μg were effective but at least 30 minutes were required for a significant response. Differences in 32P uptakes were observed between 2-day and 8-day-old birds. The younger chicks had greater percentage increases over their controls than did the older chicks and the latter reached their peak response 40 minutes later. Assay of anterior pituitary glands demonstrated that 90 minutes after LH-RH treatment there was less gonadotropin present than in control glands but 150 minutes after injection anterior pituitary gland content was greater than that of the control glands.

Fractionation Studies on a Factor in Linseed Meal Protecting Against Selenosis in Chicks

Growth rate of Single Comb White Leghorn cockerels fed a casein-gelatin-glucose diet was significantly depressed at two weeks when 10 p.p.m. or more selenium was added to the diet. When 20% linseed meal was included in the diet, growth was not reduced with 10 p.p.m. selenium and only slightly reduced with 20 p.p.m. selenium. Including 20% soybean meal failed to modify the toxicity. Levels of 5 and 10% linseed meal were less effective in counteracting selenosis than was 20%.Fractionation studies showed that a protective factor in linseed meal was extracted by methanol and ethanol and was not destroyed by autoclaving. Ashing the ethanol extract destroyed its activity. The factor was readily extracted by chloroform:methanol (2:1) but less effectively by acetone and diethyl ether. Washed chloroform:methanol extract was inactive but the washings contained the factor. Concentrates of the factor were active at less than 1% of the dry matter of the diet. The results of these studies show that linseed meal contains a heat stable, organic, polar factor that modified selenium toxicity in the chick.

Synergism between 4-Hydroxyquinoline and Pyridone Coccidiostats

Drug combinations containing a 4-hydroxyquinoline coccidiostat plus meticlorpindol exhibited anticoccidial activity against Eimeria acervulina and Eimeria tenella which was greater than equivalent levels of either coccidiostat alone. Combinations containing decoquinate, buquinolate, or amquinolate were shown to have nonadditive effects when combined with meticlorpindol. It was concluded that such drug combinations are synergistic in their action and that the two classes of anticoccidials probably act upon closely related, but nonidentical, metabolic pathways. During the study of a series of drug-tolerant strains of poultry coccidia we made the unexpected finding that a population of Eimeria acervulina which had developed resistance to meticlorpindol (3,5-dichloro-2,6-dimethyl-4pyridinol) showed a greater than expected sensitivity to decoquinate (ethyl-6-(decyloxy) 7-ethoxy-4-hydroxy-3-quinoline carboxylate). Further investigation revealed a situation of collateral sensitivity between decoquinate and meticlorpindol (Jeffers and Challey, 1973). The preexisting resistance of a strain of E. acervulina to decoquinate was reversed through the acquisition of resistance to meticlorpindol. Furthermore, it was shown that the induction of resistance to meticlorpindol served to enhance the sensitivity to decoquinate of an already sensitive strain of E. acervulina. It was hypothesized that populations resistant to meticlorpindol contain individuals capable of employing an alternative metabolic pathway not affected by meticlorpindol but which is readily blocked by decoquinate and related 4-hydroxyquinoline coccidiostats. Based on this hypothesis, it was thought that mixtures containing meticlorpindol and one of the 4-hydroxyquinoline coccidiostats might act synergistically. Experiments were designed to determine the anticoccidial activity of decoquinate and related 4-hydroxyquinoline coccidiostats in combination with meticlorpindol. We observed that all of the 4-hydroxyquinoline-meticlorpindol combinations which were examined showed anticoccidial activity which was markedly greater than equivalent levels of either compound administered alone. Because of the nonadditivity of this response, we conclude Received for publication 26 January 1973. that combinations of 4-hydroxyquinoline coccidiostats and meticlorpindol are synergistic in their effect upon coccidian endogenous development. MATERIALS AND METHODS A standard all-mash ration was used for all trials. The experimental drugs were thoroughly incorporated into the ration with the aid of a Hobart mixer. Trials were conducted with coccidiafree 16to 18-day-old Single Comb White Leghorn cockerels. The chicks were weighed and assigned in weight-balanced groups of 10 to clean finisher batteries. The chicks were given free access to the medicated rations at least 24 hr prior to oral inoculation with oocyst suspensions. Pure species cultures of coccidia which had never been exposed to anticoccidial drugs were employed. These cultures were all known to be fully sensitive to the anticoccidials used in this investigation. After preliminary studies, which showed oocyst output to be a highly sensitive indicator of drug action, we adopted this measurement as the major criterion of activity. The procedures employed for collection and enumeration of oocysts were as described by Jeffers and Challey (1973).

The Biological Effects of the Spore Bearing Lactic Acid Bacteria, <i>Lactobacillus sporogenes</i>, in Chickens

Lactobacillus sporogenes was isolated by NAKAYAMA et al. (1949) and kindly supplied by them to Sankyo Company.Experiments were conducted to determine the promotion of L. sporogenes and its biological responses for chickens were observed.Day-old single comb White Leghorn cockerels obtained from a commercial hatchery were reared in electrically-heated, metal wire floored battery brooders. The ten birds each were used in experimental and control groups, and trials were repeated seven times.The preparations containing 1×109 spores of L. sporogenes per gram was fed to chickens at the dietary level of 100ppm for 4 weeks.The results were as follows; L. sporogenes caused an increase of weight gain and an improvement of feed efficiency in chickens fed for 4 weeks.The vegetative cells and spores of L. sporogenes were recovered from and the amount of lactic acid increased in the small intestine and caecum when chicken were fed the organisms. However, the pH of intestinal contents, and the amount of serum cholesterol and serum lactic acid were not significantly different from control values.

Effect of Fasting, Refeeding and Dietary Protein Level on Uric Acid and Ammonia Content of Blood, Liver and Kidney in Chickens

The effect of graded levels of dietary protein on ammonia and uric acid concentration in blood, kidney and liver of single comb White Leghorn cockerels was investigated. The concentration of uric acid in the blood plasma was increased pro-portionally to the increased protein level of the diet, and the highest value was obtained 2 hours after feeding. The blood ammonia concentration was also increased, but to a lesser degree than for uric acid, by feeding 15 to 40% casein diets, whereas zero to 10% casein diets did not affect the blood ammonia concentration. Fasting for an extended period caused a marked increase in plasma uric acid concentration; 72 and 240 hours after beginning the fast the plasma uric acid concentration reached approximately 10 and 40 times the initial concentration, respectively; the rise in uric acid concentration was reduced to normal within 6 hours after refeeding. Ammonia an uric acid contents of both liver and kidney increased gradually with the increase of dietary protein level. Kidney ammonia content per unit weight was twice the liver ammonia content, whereas total ammonia content was equal in liver and kidney. On the other hand, uric acid contents of liver and kidney per unit weight were not significantly different, whereas total uric acid content of liver was twice that of kidney.

Duration of Acquired Immunity of the Chicken to Eimeria tenella Infection

Acquired immunity to reinfection with Eimeria tenella was reexamined. The study suggests that chickens, immunized by multiple doses of E. tenella, develop only a condition of relative immunity. Immunity, as assessed by clinical signs of the disease, lasted somewhere between 42 and 63 days after the last immunizing dose. Immunity, whereby the host is protected against fatal E. tenella infection, was found to be effective for at least 105 days. Complete immunity, where there is no invasion of host tissue, as assessed by the presence of unsporulated oocysts in the fecal material of challenged immune birds, was not encountered in this study. Although chickens were producing serum lysins 21, 42, 63, 84, and 105 days after the last immunizing dose, they still remained susceptible to challenge inoculations given at that time. Acquired immunity to reinfection with Eimeria tenella (Railliet and Lucet, 1891) Fantham, 1909 is well known. Johnson (1927) first demonstrated that a specific immunity was acquired following a coccidial infection. His observations have since been corroborated by many investigators (Tyzzer, 1929; Horton-Smith, 1949; Waletzky and Hughes, 1949; and others). Little information, however, has been published concerning the duration of the immunity acquired. Horton-Smith, Beattie, and Long (1961) inoculated chickens with a single dose of 60,000 E. tenella oocysts. The birds were challenged with 120,000 oocysts 14, 21, or 28 days later. Six days after challenge the ceca of each bird were examined microscopically for parasites. No detectable infection or only light infections were observed in the birds challenged at 14 days, whereas heavier infections were observed in birds challenged at 21 or 28 days. Long (1961) reported that chickens immunized by multiple doses of E. tenella oocysts remain resistant for at least 3 months following the last immunizing dose. In the present study acquired immunity to reinfection with E. tenella was reexamined. The degree of immunity obtained was assessed by oocyst production and histological examinaReceived for publication 6 October 1967. * This investigation was supported in part by a Public Health Service Fellowship (GM-16,562) from the National Institute of General Medical Sciences, Public Health Service, and in part by a Public Health Service Research Grant (AI04101). t Present address: University of Wisconsin, Waukesha Center, Waukesha, Wisconsin. 227 a ion of the cecal tissue following a challenge inoculation. MATERIALS AND METHODS Single-Comb White Leghorn cockerels obtained from a local hatchery as day-old chicks were delivered to coccidia-free rooms and fed an all-mash ration containing vitamin and mineral additives, but no coccidiostats. Periodic fecal examinations for oocysts were made to assure freedom from infection prior to experimental use. Oocysts were from a pure line culture, developed from a single oocyst, and maintained in this laboratory. Fresh oocyst suspensions were prepared routinely from the ceca of donor birds 7 days after an oral inoculation of 4,000 sporulated oocysts. In Experiment I the duration of acquired immunity to E. tenella in the absence of an experimentally induced reinfection was investigated. One hundred and forty chickens were divided into two groups. Group I consisted of 60 birds and constituted the experimental group. Each member, at 1 week of age, was given 500 sporulated oocysts. The initial infection was followed by three immunizing inoculations of 5,000, 50,000, and 100,000 sporulated oocysts administered when the birds were 4, 7, and 10 weeks of age, respectively. Group II contained 80 birds and constituted the control group. Members of this group received no prior infection and were maintained in a coccidiafree room until needed for experimental purposes. At each immunizing inoculation, 10 birds from Group I were selected randomly and housed, 5 to a cage, over galvanized trays containing tap w ter to a depth of 1/2 inch. Ten uninfected chickens from Group II were given the same oocyst dosage as those of Group I and housed in the same manner. The intestinal droppings were collected every 24 hr, beginning on the 7th and terminating on the 15th day after each inoculation. The material from both trays of each group was pooled and the volume made up to 1 liter with tap water. The mixture was homogenized in a Waring blendor and a 100-ml sample extracted. This was filtered through an 80-mesh copper sieve, This content downloaded from 157.55.39.192 on Wed, 24 Aug 2016 06:03:58 UTC All use subject to http://about.jstor.org/terms 228 THE JOURNAL OF PARASITOLOGY, VOL. 54, NO. 2, APRIL 1968 Oocysts produced by experimental and control chickens in a nine day period (day 6-14) following immunizing and challange inoculations with Eimeria tenella oocysts.

Influence of Vitamin A Deficiency on Testes, Bursa Fabricius, Adrenal and Hematocrit in Cockerels

Additional physiological measurements were studied to aid in understanding the unique observation that marginally vitamin A-deficient cockerels had increased testes size. One-day-old Single Comb White Leghorn cockerels were fed either a vitamin A-deficient or -adequate (6600 USP units/kg) ration. Hematocrits were greater from vitamin A-deficient birds at 6, 9, 10 and 11 weeks of age. Combs, testes, bursae and adrenals were removed and weighed, and the latter 3 organs corrected for body weight. Bursae weights from vitamin A-supplemented birds were larger from 6 through 11 weeks of age. Vitamin A-deficient birds had heavier testes and heavier combs at 8 and 10 weeks of age. Histological examination of the testes from 11-week-old vitamin A-deficient birds showed mature sperm. No sperm were observed in the testes of control birds at this age. Corrected adrenal weights were heavier in the deficient birds at 9, 10 and 11 weeks of age. No differences in oxygen consumption were found between treatments measured at 3, 5 and 11 weeks of age. Increased testis weight, adrenal weight, comb size, red blood cell volume and decreased bursa weight suggested higher androgen secretion by vitamin A-deficient birds.

Protein Levels in Growing Diets and Reproductive Performance of Cockerels

Two experiments were conducted with Single Comb White Leghorn cockerels to determine the effect of dietary protein during the growing period on sexual maturity and various reproductive characteristics. Dietary protein levels of 16.0, 9.0, 6.75 and 4.5% were fed beginning when the cockerels were 9 weeks of age and 7 weeks of age in experiments 1 and 2, respectively. A 17% protein breeder diet was fed from 23 weeks until 37 weeks of age. Body growth was depressed with each decrease in dietary protein. The 4.5% protein level approximated a maintenance diet. Sexual maturity was delayed in the low protein groups, without apparent permanent damage to the reproductive system. After the recovery diet had been fed for 7 weeks, there was little difference between dietary groups in the number of birds producing sperm or in semen scores. By the end of the recovery period the low protein groups had higher sperm concentrations and greater testes weights. Fertility was higher in the 9.0 and 6.75% protein groups than in the 16.0 and 4.5% protein groups at the end of the recovery period. Hatchability of fertile eggs was not affected by protein levels during the growing period.

A Chick Assay Procedure for the Edema-Producing Factor in Toxic Fat

HYDROPERICARDIUM and other disorders in chickens attributed to feeds containing toxic fat have been described by several investigators (Schmittle et al., 1958a, b; Sanger et al., 1958; Edgar et al., 1958; Naber et al., 1958; Machlin et al., 1959; and Dunahoo et al., 1959). None of the known compounds tested has been concluded to be the causative agent of the syndrome.The isolation in pure crystalline form of the edema-producing factor from toxic fat was recently reported by Harman et al. (1960). In order to guide the purification of the factor, a quantitative assay procedure based upon the measurement of pericardial fluid volume in young chicks was employed. This paper is a report of our studies with this assay. EXPERIMENTALDay-old Single Comb White Leghorn cockerels from a commercial hatchery were reared in electrically-heated, metal, wire-floored battery brooders in temperature controlled rooms provided with 14 hours daily of artificial illumination.…

The effect of dietary antibiotics upon hepatic and renal xanthine dehydrogenase activity in chicks

Single-comb White Leghorn cockerels were fed a nutritionally adequate, practical-type chick starter diet supplemented with either 15 g. oxytetracycline or 6 g. procaine penicillin per ton in two feeding trials. Fresh liver and kidney homogenates from 4- and 9-week-old chicks were assayed in vitro for xanthine dehydrogenase activity. Oxytetracycline, but not penicillin, significantly inhibited xanthine de-hydrogenase activity per gram of kidney dry matter of 4-week- but not of 9-week-old chicks. Neither antibiotic affected liver xanthine dehydrogenase activity at either age. It is suggested that the growth stimulation observed during the period of rapid growth may be due in part to enhanced nitrogen utilization, resulting from the decrease in renal xanthine dehydrogenase activity.

Studies on Zinc in Poultry Nutrition: 2. Zinc Requirement and Deficiency Symptoms of Chicks

ABSTRACT STUDIES on zinc in the nutrition of the chick by Edwards, Young and Gillis (1958) have shown that the chick can obtain small quantities of zinc from feed and water and zinc-galvanized materials. Zinc may be obtained from the latter either by direct contact or by contamination of the feed and water from these materials. This paper is a report on the study of the chicks’ requirement for zinc under carefully controlled experimental conditions where special precautions were taken to isolate the chicks from any environmental zinc. Although O’Dell and Savage (1957) and Edwards et al. (1958) have described the general symptoms of a zinc deficiency in chicks, the severe zinc deficiency symptoms encountered in this study are described in detail and illustrated. EXPERIMENTAL Single Comb White Leghorn cockerels were used in all experiments. In five experiments, the chicks were housed in plastic cages with stainless steel tops. Five chicks . . .

The Effects of Progesterone and Diethylstilbestrol Injected Singly or in Combination on Sexual Libido and the Weight of the Testes of Single Comb White Leghorn Cockerels

SINCE the apparent demonstration of progesterone in the blood of the domestic fowl (Fraps, Hooker and Forbes, 1948Fraps, Hooker and Forbes, 1949), attention has been centered upon its effects and mode of action in the chicken. Much of the work thus far undertaken has dealt with the molt response induced in chickens by the use of exogenous progesterone (Adams, 1955; Juhn and Harris, 1955; and Shaffner, 1954, 1955). Adams (1955) also reported that progesterone modified sex response in treated hens. No male behavioral data were presented in any of the above papers.In 1943 Davis and Domm observed that two normal roosters receiving stilbestrol stopped crowing, but continued to copulate. Although a great deal has been published on the effects of estrogen as demonstrated by behavioral responses in the hen and capon, little information is available regarding its effects in the mature intact male.Due to the lack of information concerning how the …

The Effect of Sulfamethazine Feeding on the Thyroids, Combs and Testes of Single Comb White Leghorn Cockerels

ASPLIN and Boyland (1947) and Turner and Kumaran (1949) have reported that certain pyrimidine sulfa compounds could induce testicular hyperplasia and enlarged combs in cockerels. Turner and Kumaran (1949) explained these facts by assuming an increased gonadotrophin secretion by the anterior pituitary gland. An alternative explanation for the observed phenomena is increased sensitivity of the gonads to endogenous gonadotrophins.Experiments reported in the present paper were designed to elucidate the mode of action of sulfamethazine, one of the sulfa pyrimidine compounds found by Turner and Kumaran (1949) to be effective in inducing precocious sexual maturity. During our experiments a marked effect was observed on the thyroid size and activity.MATERIALS AND METHODSSingle Comb White Leghorn cockerels of an unselected population were used. The sulfamethazine was mixed with a 20% broiler mash at levels of 0.1 and 0.2%. Birds received feed and water ad libitum.At autopsy the combs, thyroids, …

Hematological and histological changes induced by adrenocorticotropic hormone and formaldehyde stressor in the domestic fowl.

In the present experiment, changes of percentage of leucocytes in the adult chicken blood induced by ACTIH injection and histological changes of lymphoid tissues and adrenals in the young chick induced by formaldehyde stressor, were examined.Hematological changes: Relative heterophilia and lymphopenia were observed in the treated chicks which were injected with 10mg of ACTH intravenously or intraperitoneally, and were not observed in the chickens injected with the same dose of ACTH intramuscularly or subcutaneously. It was found that pricking of comb has some stressor agentical effect upon blood in the fowl, and also it was suggested that Selye's stress concept should be applicable to the chicken.Histological changes: Single comb white leghorn cockerels 3-4 weeks old were used. They were injected with 1 cc of 4% formaldehyde intramuscularly 3times during 36hours. They were sacri ficed at the end of the period of 12hours after the last injection. The decrease in weights of thymus, spleen and bursa Fabricii and hypertrophy of adrenal gland were observed. Histologically, in the thymus of the treated chicks, the thymocytes of the thymus cortex drained into medulla, so that the demarcation between cortex and medulla became unvisible, and naked reticular cells appeared in the thymus cortex. The number of Hassal-body increased relatively, and the PAS positive degenerating intercellular granules also seemed to increase in their number. In the speen, severe involution of the lymph follicle in the white pulp, and heteropoiede in the red pulp were observed.Hyperplasia, hypertrophy, mitotic figures of the interrenal cells and loss of chromaffin substances in the chromaffiiin cells were observed in the adrenal gland. In the bursa Fabricii, though involutic change of the follicles was observed, other striking changes could not be confirmed histologically or cytologically. From these facts, it could not be decided whether the bursa Fabricii is a true lymphoid organ or not.These changes were comparable to those in mammals, and function of bursa Fabricii were discussed in the present parper.

A Comparison of Triiodothyronine and Thyroxine in the Chick Goiter-Prevention Test

INTRODUCTIONTHE discovery of an unknown iodinated compound as a regular constituent of plasma and thyroid tissue (Gross et al., 1950) led to the discovery of triiodothyronine by Gross and Pitt-Rivers (1952). It has been established that triiodothyronine possesses all of the thyroid hormone qualities of thyroxine when tested in a variety of species (Gross and Pitt-Rivers, 1954). Moreover, triiodothyronine has proven to be from 3 to 7 times more potent than thyroxine in preventing thiouracil-induced thyroid goiter in rats (Gross and Pitt-Rivers, 1953; Tomich and Wollett, 1954). Since the above studies have been largely restricted to mammals, it seemed of some interest to determine the potency of triiodothyronine in terms of thyroxine in the fowl by means of the goiter prevention test.MATERIALS AND METHODSExperiments were performed on Single Comb White Leghorn cockerels maintained on commercial laboratory chow (containing 5 ppm. iodide) and caged under 24-hour infra-red illumination… .

Lipemia and Fat Deposition in Response to Oral Administration of Synthetic Estrogens

ORAL administration of estrogens for fattening poultry has produced good responses, but optimum conditions have not yet been described. Extensive feeding trials for this purpose have been reported with only two of the available synthetic compounds with estrogenic activity—diethylstilbestrol and its derivative dianisylhexene. From a practical standpoint these compounds both present disadvantages.Diethylstilbestrol has a relatively low oral estrogenic potency for chickens (Jaap, 1945; Munro and Kosin, 1946) and large doses are required to produce fattening. Thayer, Jaap and Penquite (1944, 1945) observed a slight improvement in finish of 8-week-old Barred Plymouth Rock cockerels fed diethylstilbestrol for 3 and 4 weeks. During these periods each bird consumed about 75 and 100 mg. of the estrogen respectively; birds that were fed for 2 weeks only and consumed about 50 mg. showed no improvement in grade. Feeding 6- and 11-week-old Single Comb White Leghorn cockerels for 4 weeks produced only a .

High Protein Mashes for Broilers

THE commonly accepted level of protein in starter mashes for chicks is 19–21 percent. If lower levels of protein are fed, rates of growth are at first comparatively slow. When higher levels of protein are fed it is usually concluded that there is no advantage in efficiency of feed utilization gained by this practice (Heuser, 1941).PROCEDUREThis paper presents the results of three series of tests made with Single Comb White Leghorn cockerels.1 Twenty-five or 26 chicks were used in each group in all tests. In the first and third tests all of the birds received proved to be cockerels. In the second test the number of females varied from 0 to 4 in each group of chicks.The all-mash rations used are shown in Table 1. The estimated protein was 20 and 29 percent in mash A and B, respectively. Actual analysis showed the protein content of these .

A Preliminary Study of the Effect of Sunlight, Dubbing, and Fractionated Anterior Pituitary Extract upon Growth, Endocrine Glands, and Sexual Capacity of Single Comb White Leghorn Cockerels

SINCE the female is much more directly productive than the male, the intensiveness of the study devoted to the environmental and physiological factors bearing upon her fecundity has greatly exceeded that relative to sexual development of the male. In the latter sex the effects of sunlight exposure, the functional activity of the comb, and the endocrine responses thereto have not been fully explored. It is felt, therefore, that a broad experiment interrelating as variables the effect of direct sunlight, dubbing, and the administration of fractionated anterior pituitary extract upon growth, endocrine glands, and ultimate sexual capacity may yield some data of a useful nature in the improvement of rearing practice of males to promote greater breeding efficiency at a mature age.EXPERIMENTALA group of March-hatched Single Comb White Leghorn cockerels were reared in batteries to eight weeks of age on a starter ration believed to be nutritonally adequate. One-half .