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The consequences of dietary excesses of 10 essential amino acids, His, Ile, Phe, Trp, Val, Arg, Leu, Lys, Met, Thr, on growth, feed intake and plasma levels of triiodothyronine (T3) and thyroxine (T4) in growing chicks were investigated. Each amino acid was added to a starter ration to bring it to a level 2.84x above the National Research Council (1984) requirement. Excesses of all amino acids except His and Leu caused significant reductions in weight gain. Of the amino acid excesses that reduced growth, only Trp and Val did not also reduce feed intake. Gain:feed decreased significantly only in chicks consuming excess Arg, Lys, Phe, and Trp. Chicks fed excesses of Ile and Val had plasma T3 levels that were statistically higher than control levels; none of the other amino acid excesses significantly altered blood concentrations of this hormone. Compared to the control, plasma T4 levels were not significantly altered by the amino acid excesses, but there was a significant difference between Trp and Val, the latter being lower. This study shows that high dietary levels of essential amino acids cause depressions in weight gain and feed intake, and, with Ile and Val, these depressions are accompanied by elevations in plasma T3 levels. Otherwise, the amino acid excesses had little effect on plasma levels of thyroid hormones.

The effectiveness of computer-assisted instruction (CAI) in nutrition education was evaluated by determining if a CAI program designed to reinforce class lectures and available on disks and the university network was associated with higher cognitive achievement test scores. Students’ opinions concerning the helpfulness, advantages, and disadvantages of such a program were also assessed. Our CAI program was available to 243 students in four sections of an introductory nutrition course. Students could use the CAI program for any amount of time. There were 160 users and 83 nonusers. A valid and reliable cognitive pretest–post-test, an attitude assessment, and a demographic and opinion questionnaire were used. Differences in pretest–post-test scores were analyzed by two-way analysis of variance. Internal consistency of the attitude assessment instrument was determined using Cronbach's alpha test. Users of the CAI program had higher pretest–post-test gain scores than nonusers. Eighty-seven percent of the students thought that the program was useful or very useful; 78% thought that it improved their grades. Students’ attitudes were positive toward use of computers and, generally, improved with use of the program. We concluded that class material in a computerized format available on disks and a network is useful for improving performance of students in a college-level, introductory nutrition course.

Consumption of low-protein diets consistently causes elevations in circulating levels of triiodothyronine (T3) in several species of animals. In chicks this is often accompanied by lower levels of circulating thyroxine (T4). Since low-protein diets are usually formulated by replacing the detected protein with carbohydrate, the question arises as to whether the changes in thyroid hormones are a result of the lower protein or higher amounts of carbohydrate in such diets. Male broiler chicks, 13-26 days of age, were fed experimental diets that contained either an adequate level of protein (24%) or levels that were slightly (17%) or moderately (10%) deficient in protein. The deleted protein was replaced, isocalorically, with either glucose, soybean oil, or hydrogenated coconut fat. Though the level of protein and source of energy differed among diets, all diets contained identical amounts of all nutrients and energy, and were of similar weight densities. Circulating levels of thyroid hormones were measured from blood samples taken at the end of the study. Plasma T3 was elevated to a similar degree in all protein-deficient animals compared with control. Plasma T4 decreased in all protein-deficient chicks and was lowest with 10% dietary protein. Changes in circulating levels of thyroid hormones occurred independently of the source of dietary energy. Therefore, it is concluded that alterations in circulating levels of thyroid hormones that occur in chicks fed low-protein diets are a specific effect of the protein deficit and are not a related to the amounts of carbohydrate or fat present in the diet.

Growth and thyroid function were studied in Mg-deficient chicks. Dietary levels of 80 to 315 ppm Mg were compared with control levels of 578 to 787 ppm Mg. Signs of Mg deficiency appeared rapidly and acutely within 2 to 5 days at dietary levels of 250 to 260 ppm or lower. Growth and feed intake decreased progressively as the deficiency became more severe. Control chicks pair-fed with the deficient chicks gained significantly more weight. Serum Mg decreased at all levels of Mg below control, but at 260 and 315 ppm it returned to control values after 21 days on treatment. Serum Ca diminished only when dietary Mg was 250 ppm or less. Serum K increased in severely deficient chicks but decreased over time in milder deficiencies. Thyroid gland weights were unchanged. However, very young chicks fed a Mg-deficient diet had lower serum 3,5,3′-triiodothyronine (T3) whereas serum thyroxine (T4) was generally unaffected. Beyond 1 wk of age chicks that had prior access to a Mg-sufficient diet had low serum T4 levels whereas serum T3 was unchanged. Therefore, peripheral thyroid hormone metabolism is altered in a Mg deficiency, but this effect is dependent on the age at which the deficiency occurs.

We showed previously that Met deficiency at 0.25% of the diet causes elevations in plasma triiodothyronine (T3) in broilers. In the present study, plasma levels of thyroid hormones as well as insulin-like growth factors (IGF)-I and -II were measured in chicks fed 3 deficient levels of total Met. Control (0.5%) and Met-deficient diets (0.4, 0.3, and 0.2%) were fed to male broilers from 8 to 22 d of age. Additional groups of control chicks were pair-fed with the Met-deficient ones. Chicks receiving 0.4% Met increased feed intake by 10% with no significant change in body weight. The more severe Met deficiencies of 0.3 and 0.2% caused graded reductions in feed intake and weight gain. However, corresponding pair-fed control chicks were significantly heavier. These changes suggest more marked alterations in metabolic processes with 0.3 and 0.2% Met than with 0.4% Met. Liver weights were heavier in chicks fed 0.3 and 0.2% Met but not 0.4%. Plasma T3 was higher in all deficient chicks compared with the free-fed control, which was significant only with 0.3% Met. However, with 0.3 and 0.2% Met, plasma T3 was significantly elevated compared to pair-fed controls. Plasma thyroxine (T4) was lower in all deficient groups, which was significant only with 0.2% Met, whereas no significant differences occurred between deficient chicks and their pair-fed controls. Plasma IGF-I levels were not significantly different, but they were consistently lower in deficient chicks and deserve further study. Plasma IGF-II was significantly less in chicks fed 0.2% Met compared to pair-fed controls suggesting that Met deficiency interferes with IGF-II metabolism. We concluded that a deficit of dietary Met altered plasma T3 and IGF-II levels, but the effect was dependent on the degree of deficiency.

Consumption of low protein (10%) diets is known to produce elevations in plasma triiodothyronine (T3) in growing chickens. Therefore, we evaluated the effect of individual essential amino acid deficiencies on plasma thyroid hormone concentrations. For 13 to 15 d, chicks were fed either a control diet free-choice, one of six amino acid-deficient diets free-choice, or the control diet, pair-fed at the level consumed by chicks fed each of the deficient diets. The control diet was a 50/50 mixture of broiler starter and purified amino acid diets. The amino acids, fed at the indicated percentages of National Research Council recommendations, were: arginine, 60%; lysine, 60%; threonine, 60%; leucine, 75%; isoleucine, 75%; and methionine, 50%. Feed consumption and weight gain were significantly lower in all deficient groups than in the free-choice control group. In all cases except leucine, deficient chicks also gained less weight than their pair-fed controls. Plasma T3 levels in the groups deficient in arginine, lysine, isoleucine, or methionine were higher than in their respective pair-fed controls. However, only with the isoleucine deficiency did T3 levels exceed those of control chicks given free access to feed. Thyroxine levels were significantly lower than control levels only with the lysine deficiency. These results suggest that changes in circulating levels of thyroid hormones in a protein deficiency may be a consequence of selected amino acid deficits, because individual essential amino acids, when deficient in the diet, do not exert the same effect on circulating levels of thyroid hormones.

Day-old White Leghorn cockerels were fed a purified essential fatty acid (EFA)-deficient basal diet (0.03% linoleic acid) ad libitum for 1 week. They were then fed one of the following treatments for 7 weeks: 1) basal diet ad libitum, 2) basal +4% corn oil pair-fed to 1, 3) basal +4% corn oil ad libitum, or 4) corn-soybean diet. Chicks fed the deficient diet exhibited marked reductions in weight gain, energy efficiency, and comb and testes weights, increases in liver size, and characteristic changes in tissue fatty acids at 8 weeks of age. Depressions in weight gain, tibial length, epiphyseal plate width, pituitary growth hormone (GH) activity, elevated plasma GH, and a tendency for reduced nitrogen reten tion, point to an impairment in GH metabolism in EFA-deficient chicks. Results with pair-fed control chicks suggest that smaller tibial length and width, smaller epiphyseal plate width, reduced nitrogen retention, elevated plasma GH and, to a partial extent, reduced body weights, smaller combs and testes, and larger pituitary glands are a result of reduced appetite and food intake rather than a direct biochemical effect of EFA per se. Changes due directly to the EFA deficiency, independent of reduced food intake, were decreased energy efficiency, increased liver weight, elevated triene- tetraene fatty acid ratio, and reduced hypophyseal GH. These results demonstrate the importance of equalizing food intake in studies of this nature. Hypophyseal GH content was not affected by treatments in the same fashion as was plasma GH concentration. This indicates that different hypothalamic-hypophyseal mechanisms operate to increase plasma GH in EFA-deficient and pair-fed control chicks. J. Nutr. 109; 330-338, 1979.

Protein-deficientdiets (17, 10, 6.5 or 3% protein) and a 24% control diet were fed to growing chicks. A control group was pair-fed dailywith each deficient group. Energy intake was lower in the 6.5 and 3% protein groups than in the other groups. However,weight gain, bone growth and feed conversion efficiencywere lower with 10% protein or less. Relative thyroid weights were unaffected by dietary protein. Plasma T3 (3,5,3'-triiodothyronine) levels were significantly higher in all deficient groups, whereas plasma T4 (thyroxine) was lower. Plasma rT3 (reverse T3) was un affected by the protein deficiencies, suggesting that en hanced conversion of T4 to T3 rather than to rT3 had oc curred. Hepatic a-grycerol-3-phosphate dehydrogenase (

Two studies were conducted to observe the effects of an essential fatty acid (EFA) deficiency, added dietary corn oil and pair-feeding on growth, reproduction and other physiological parameters in the mature cockerel. A purified, linoleic acid (LA)-deficient diet (0.01% LA), or additions of 5% (3.01% LA) or 15% (9.04% LA) corn oil, were fed ad libitum from hatching through 24 weeks of age. Reductions in growth, feed consumption, and comb, and testes size, incomplete spermatogenesis, increased tissue eicosatrienoic acid (20: 3 omega 9) and changes in weights of selected internal organs were observed in deficient cockerels. Total pituitary gonadotropic activity was measured by two bioassay procedures and blood luteinizing hormone was measured by radioimmunoassay. By maturity both of these parameters were significantly reduced in deficient chickens. When these chickens were fed diets with 5% or 15% corn oil under pair-feeding or ad libitum conditions from 20 to 24 weeks, the reduced growth, comb and testes size and gonadotropin metabolism appeared to be caused by depressions in appetite and energy intake rather than EFA per se. The degenerate testicular histology of the 20-week old deficient cockerels, while responding fully to the ad libitum intake of the diets containing corn oil, showed only partial rehabilitation of spermatogenesis when diets with either 5% or 15% corn oil were pair-fed. In general, increasing the level of dietary fat from 5% to 15% did not cause many physiological changes.

A diet with 20% herring oil (0.55% linoleate) gave comparable growth responses to a diet containing 20% corn oil (12.07% linoleate) in 4-week-old male and female White Leghorn chicks. No additive or synergistic growth responses were noted in female chicks fed a mixture of herring oil and corn oil. Decreased testes size and changes in testicular histology occurred in young cockerels fed herring oil. Comb responses were dissimilar in male and female chicks fed fish oil.

Broiler chicks from 2 to 4 weeks of age were fed control (0.23%) and deficient (0.115, 0.058%) levels of L-tryptophan. Separate groups of control chicks were pair-fed daily with the deficient chicks. Deficient chicks grew less efficiently than did pair-fed controls. Plasma triiodothyronine (T3) was elevated in deficient chicks, especially compared to pair-fed controls, and this was accompanied by lower reverse T3. Plasma thyroxine (T4) was also reduced with 0.059% tryptophan. However, thyroid weights and follicle diameters were unchanged. Reductions in weight gain and bone growth, increases in pituitary and pineal weights, and elevations in plasma GH occurred in the tryptophan-deficient chicks apart from any effect due to reductions in feed intake. Comb and testis size, and plasma testosterone were little affected by the deficiency. Based on changes in plasma T3 levels and feed conversion efficiencies, we conclude that tryptophan-deficient chicks show signs of relative hyperthyroidism and energy wastage compared to pair-fed controls. The elevations in plasma growth hormone and T3 support the concept that serotonin is a negative modulator of the synthesis or release of these hormones in chickens.

The effect of early and prolonged exposure of growing cockerels to selected photoperiods and wavelengths of light on pineal gland weight and lipid composition was investigated. The six treatments included 14L:10D white (control), 24L:0D white , 0L:24D dark, and 14L:10D narrow-band blue, green, or red light. Pineal gland fresh and dry weights were greatest under the white light treatment and least under the dark and red treatments. Examination of histological preparations and biochemical analysis both indicated that the absence of light depleted pineal lipid. When expressed as a percent of dry tissue weight, lipid from the colored light treatments was significantly greater than from the control. We conclude that both the photoperiod and the wavelength of light are capable of influencing pineal gland lipid metabolism in the cockerel.

Four replicate experiments were conducted to determine the effects of pinealectomy and environmental lighting on growth and thyroid function in broiler cockerels. Birds were housed in battery brooders under a 14L:10D white light regime for 2 weeks and then allotted to light-controlled chambers. The light environments were 14L:10D white, 14L:10D green (narrow band, 545 nm peak), and constant dark. Surgery was performed when the chicks were 3 to 5 days old. At the end of the 32-day experimental period, weight gain and thyroid weights were measured and plasma triiodothyronine (T3 ) and thyroxine (T4) levels were determined by radioimmunoassay. Pinealectomy significantly (P Birds grown under white light were significantly (P

The effects of a dietary P deficiency on thyroid function, serum growth hormone, and growth parameters in 10 to 29-day-old broiler cockerels was determined. Chicks fed severely P-deficient diets (.05% or .10% available P) grew more slowly and ate less feed than controls fed .65% P. The deficiency was also accompanied by hypercalcemia, hypophosphatemia, and decreases in percent bone ash, fat-free tibial weight, and tibial length and width. Increases in the relative weights of kidneys, hearts, and pituitary glands (.05% P only) occurred as well. Most of these changes occurred to a lesser extent or not at all in pair-fed controls, showing that they resulted specifically from the P deficiency and were not simply a result of reductions in feed intake. Phosphorus deficiency also was accompanied by peripheral edema and hydropericardium. Relative thyroid weight was unaffected. Serum triiodothyronine was consistently lower in the P-deficient chicks, although effects were significant only in one experiment. Thyroxine levels tended to be low also, but not consistently so. Serum growth hormone in P-deficient chicks in both studies was consistently lower than that in pair-fed controls, but this was significant only when .10% but not .05% available P was fed. The findings suggest that serum levels of both thyroid hormone and growth hormone are altered by P deficiency, but the results were not clearly definitive.

Caged Sex-Sal (DeKalb Warren) replacement pullets were fed diets containing .30%, .35%, or .41% available phosphorus from 0 to 20 weeks of age; in a second study pullets were fed the above levels plus a level of .25% available phosphorus from 2 to 20 weeks of age. Some of the pullets were fed diets restricted by 11 to 16% from 8 weeks of age. Reducing the dietary phosphorus did not harm weight gain, feed intake, feed conversion efficiency, bone ash or total calcium and inorganic phosphorus levels in plasma. There was a very small but significant reduction in weight gain and feed intake when .30% or .35% available phosphorus was fed from 0 to 4 weeks of age, but this difference disappeared at the later ages. With the nonstimulatory lighting schedule used, plasma phosphorus decreased markedly in the latter phase of the studies at all levels of dietary phosphorus and thus represented a nondietary age effect. These results show that dietary available phosphorus for caged, brown egg type pullets on full or restricted feeding programs can be decreased to a level as low as .25% from 2 to 20 weeks, and .30% from hatching to 20 weeks without adverse effect.

Three dietary energy levels (2,737, 3,003, 3,322 kcal./kg.) were fed to heavy egg-type hens housed in cages at densities of 1,320, 660, and 440 cm.2 of floor area per hen. Increasing the number of hens per cage reduced egg production. This was most pronounced with three hens per cage during the latter part of the experiment. Final body weight was reduced only with three hens per cage, and occurred to a greater degree at the end of the experiment. Mortality increased at the higher hen densities due to Marek’s disease and lymphoid leucosis. Hen density did not significantly affect egg weight, shell strength, Haugh units or meat and blood spots. Dietary energy level did not significantly alter overall hen-day egg production. However, egg production on the highest dietary energy level declined more rapidly in the latter months. Therefore, a high dietary energy content was not conducive to sustained egg production. There were no significant interactions between hen density and dietary energy level. But, with two or three hens per cage, egg production was consistently lower for hens fed the highest dietary energy level. As dietary energy level increased, feed intake decreased and feed efficiency increased. But energy intake increased resulting in heavier hens on the highest energy ration. The highest dietary energy caused an increase in egg size during the mid-part of the experiment. Otherwise, energy level did not affect egg weight, shell strength, Haugh units or blood and meat spots. It is concluded that although increases in dietary energy levels result in increased energy intakes and body weights of hens, high energy rations will not reverse the downward trend in egg production as density of caged hens increases. To the contrary, feeding of high energy rations to hens housed at high densities in cages may not be advisable, since egg production was consistently lowest under these conditions.

Intestinal absorption of corn oil and beef tallow was studied in White Leghorn male chicks during the periods of 2 to 7 and 8 to 15 days of age. Absorption of both fats was less at the earlier age. The corrected absorbability of corn oil increased from 84 to 95%; that of beef tallow from 40 to 79%. With both dietary fats, the greatest amount of fat appeared in the excreta at 5 and 7 days of age and then decreased rapidly within a 2-day period. Absorbability values for corn oil and tallow during the 8 to 15 day period agreed with generally accepted values found in the literature, while those for the 2 to 7 day period were lower. These results show that the newly hatched chick does not have full physiological capacity for fat absorption. However, this appears to develop rapidly after the first few days of life.

THE development of nutritional muscular dystrophy in the growing chick is known to be modified by a number of nutritional factors. Dam et al. (1952) showed that concomitant dietary deficiencies of both vitamin E and sulfur amino acids are necessary for the appearance of this disorder. In addition, inclusion of selenium in the diet has been reported to reduce although never completely prevent the incidence of muscular dystrophy (Dam and Sondergaard, 1957; Nesheim and Scott, 1958). The use of unusually high dietary levels of antioxidants other than vitamin E may also prevent the development of muscular dystrophy (Machlin and Shalkop, 1956). Recently Calvert et al. (1964) have shown that dietary linoleic acid is necessary for the appearance of muscular dystrophy, and that chicks fed linoleic acid-free diets do not show symptoms of the disease regardless of the deficiency of vitamin E and sulfur amino acids. Unpublished results from our laboratory…

THE poor availability of soybean oil in ground soybean s limits their usefulness as a source of energy as well as protein for the chick. In a previous study (Carew et al., 1961) ground soybeans had a metabolizable energy value that was only 86% of that which would be anticipated on the basis of the composition of ground soybeans. However, in this same study it was found that the availability of soybean oil in soybeans for chicks could be markedly improved by compressing cracked dehulled soybeans into very thin flakes prior to including them in diets for chicks. Flaked, heat-treated dehulled soybeans were found to be equal to equivalent amounts of soybean oil meal and soybean oil in their ability to promote growth in chicks and improve efficiency of feed utilization. Apparently, the maximum value from heat-treated soybeans as a poultry feed ingredient can be obtained only if a processing …

Experiments were conducted to evaluate heated unextracted soybean fractions as sources of soybean oil and protein for the growing chick. Heated dehulled unextracted soybean flakes produced growth rate and feed efficiency equal to that obtained with the combination of soybean oil meal and degummed soybean oil while heated ground unextracted soybeans were less satisfactory in this respect. The poorer results obtained with ground unextracted soybeans were shown to be related to a poorer absorbability of the oil in them. Flaking the soybeans markedly improved the absorbability of the oil by the chick, probably by causing a greater disruption of cellular structure than was obtained by the grinding of the soybeans. The metabolizable energy of ground unextracted soybeans was substantially less than that of unextracted soybean flakes. Most of the differences in metabolizable energy were accounted for by differences in absorbability of the oil. Soybean hulls at a level equivalent to that contained in soybeans were found to have no effect on growth rate and only a slight effect on feed efficiency. Autoclaving soybean oil did not lower its value for the chick. The relationship between the poorer growth obtained with ground unextracted soybeans and the low absorbability of the oil in them was discussed. To obtain maximum efficiency in the use of unextracted soybean products in chick rations, some such means as flaking must first be employed to increase the availability of the oil.

SOYBEAN oil is an excellent source of energy for chicks and also will stimulate growth rate when included in certain types of chick diets (Dam et al., 1959; Carew, 1961). Therefore it is desirable to study various means by which soybean oils may be easily incorporated into diets for chicks. Since soybean protein is the most widely used source of amino acids for poultry rations, unextracted soybeans, which contain approximately 20% soybean oil, offer a simple means of supplying most of the amino acids as well as the beneficial properties of soybean oil to chick diets in the form of a single feed ingredient. Previous reports from this laboratory have shown that finely ground, heat-treated soybeans do not serve as an efficient source of soybean oil for the chick because the soybean oil present in the soybean is poorly digested (Renner and Hill, 1960; Carew et al., 1961). Whereas extracted …

FATS from several sources have been reported to stimulate growth rate when added to diets for chicks. Included in this group are the oils derived from corn, peanuts, cottonseed and soybeans, egg oil, and lard. The reports on this subject have been reviewed by Rand et al. (1958), Hill et al. (1958), Dam et al. (1959), Denton and Menge (1959), Carew et al. (1959) and Menge and Denton (1961). This effect of certain fats on growth rate may reflect the presence of a required nutrient or may be related to the higher caloric density of diets containing added fat. Results which would support the latter possibility have been presented for fats of both animal and vegetable origin. Work by Baldini and Rosenberg (1957) showed that growth responses to beef tallow did not occur when energy levels of diets containing added fat were maintained isocaloric to that of the low-fat basal…

PREVIOUS work reported from this laboratory compared metabolizable and productive (net) energy determinations with chicks and showed that metabolizable energy is the better measure (Hill and Anderson, 1958). The purpose of this paper is to report determinations of metabolizable energy values for a variety of grains and grain products for chickens based on the use of glucose as the reference substance. Only limited data on directly determined metabolizable energy values are available for poultry, and are contained in reports by Mitchell and Haines (1927), Fraps et al. (1940), Olsson (1950), Hainan (1951) and Carpenter and Clegg (1956). Metabolizable energy values have been computed from digestibility data for many feeding materials by Axelsson and Eriksson (1951) and Titus (1955). Digestibility determinations with avian species are subject to limitations of the methods used for chemical or physical preparation of fecal and urinary constituents during analysis, or the difficulties of using surgically altered …

Four replicate experiments were conducted to determine the effects of pinealectomy and environmental lighting on testes and comb weights in the broiler cockerel. Birds were housed in brooder batteries under a 14L:10D fluorescent white light regime for 2 weeks and then allotted to light-controlled chambers. Surgery was performed when the chicks were 3 to 5 days old. The fluorescent light treatments were 14L:10D green (narrow-band, 545 nm peak), 14L:10D cool white, and constant darkness. At the end of the 46-day experimental period, testes weights were determined and comb weight recorded. Pinealectomy did not affect testes weights or comb development. Darkness significantly (P less than .05) depressed testes and comb weight. This suggests that lack of light, but not pinealectomy, affects circulating hormone levels and/or tissue responsiveness in the young cockerel.

The cranial cervical sympathetic ganglion (CCG) provides the primary innervation of the pineal gland in several gallinaceous species. The CCG is located at the base of the skull near the exoccipital bone, dorsal to the level of the vagus and glossopharyngeal nerves. It occupies a much larger volume and appears pinkish-gray, instead of white, when compared to the petrosal ganglion. To surgically remove the CCG, chicks were anesthetized with halothane vapor. Following a small skin incision, blunt dissection was used to expose the CCG lying adjacent to the internal carotid. The ganglion was grasped with small forceps and pinched free of its fine neural connections to adjacent nerves. The success of the surgery was confirmed visually and by complete adrenergic dennervation of the pineal gland. The entire surgical procedure required approximately 20 min per bird. Mortality was less than 20% overall.

Leghorn males, 66 to 96 days of age, were fed a diet marginally deficient in phosphorus (.14% nonphytate). Growth and feed intake were significantly reduced, but plasma calcium and phosphorus were unchanged. Bone ash was significantly reduced compared to pair-fed controls but not ad libitum-fed controls. Thyroid size increased and plasma growth hormone (GH) levels decreased with the deficiency, apart from any effect attributable to the lower food intake and weight gain. Plasma 3,5,3′triiodothyronine (T3) and thyroxine (T4) were not significantly changed, although there was a tendency for T4 to be lower in the deficient chickens. As both thyroid size and plasma GH are regulated partly by pituitary function, dietary phosphorus may alter endocrine function through changes in pituitary metabolism.

The linoleic acid requirement for maximum growth of male broiler chicks to four weeks of age was 1.9% of the diet or 5.3% of dietary calories. No effect of depletion by feeding a linoleic acid deficient diet from one to nine days of age was evident in the chick’s requirement for linoleic acid.

SummaryA quick, reliable procedure for the surgical removal of the pineal gland from 3 to 5-day-old chicks is presented. This procedure for pinealectomy was satisfactory as judged by low mortality and high success of the operation as verified at autopsy. The entire procedure requires approximately 5 min/chick. Nembutal, Equi-Thesin, and ether were evaluated as anesthetic agents for use in pinealectomy. Ether was the most suitable drug because of its ease of administration, rapid induction, short recovery period, and low mortality experienced with its use.

The composition of pineal gland lipid was characterized in young cockerels. The total pineal lipid was 159.7 μg, which was equivalent to 3.0 and 14.1% of fresh and dry tissue weight, respectively. The major phospholipids were phosphatidyl choline (63.1%), phosphatidyl ethanolamine (16.1%), and sphingomyelin (14.7%). Palmitic, stearic, oleic, and arachidonic acids composed 27.9%, 19.4%, 15.8%, and 13.7% of the phospholipid fatty acid fraction, respectively. Free fatty acids (38.4%), cholesterol (17.6%), and cholesterol ester (17.2%) comprised the major fraction of neutral lipids, while the predominant neutral lipid fatty acids were palmitic (26.0%) and oleic (23.8%). The percentage of wet tissue weight that is lipid in the pineal is considerably less when compared to brain cortex or retina. When chickens are compared to several mammalian species, there is little difference in percent lipid per milligram pineal tissue, but definite differences exist in the percentage of various lipid classes.

Isoenergetic diets containing casein:carbohydrate:fat, 22:59:10% (control protein, CP), or 8:73:10% (low protein, LP), were fed to female rats during gestation and lactation and to offspring postweaning. Control fed rats were pair-fed to the LP-fed group. In the LP-fed group, body and liver weights were similar at birth but decreased at 10, 21, and 42 days, while intercapsular brown adipose tissue (IBAT) weight decreased from birth to 10 and 21 days but increased at 42 days compared to controls. Hepatic mitochondrial oxygen consumption (OC) with pyruvate + malate as substrate was similar at 21 and 42 days, whereas OC in state 3 and 4 with succinate was decreased at 42 days, only in the LP-fed group. In IBAT, OC was similar in each group at each age. In the LP-fed group, hepatic glycerolphosphate (GP) shuttle activity was the same as in controls at birth but increased progressively from 10 to 21 and 42 days, whereas malate-aspartate (M-A) shuttle activity was not substantially changed during development. In IBAT, shuttle activities were similar in both groups during development with M-A shuttle activity increased in the LP-fed group at 21 days. Serum triiodothyronine (T3) levels in the LP-fed group were increased at 10 and 42 days but decreased at 21 days after birth. These results suggest a role for both pre- and postweaning diet composition as a regulator of hepatic metabolism during development. The deficit in IBAT weight in the LP-fed group during early postnatal development indicates a decreased capacity for heat production in the neonate caused by maternal protein undernutrition.

The effects of narrow-band light at equal energy levels on the development of cockerels were investigated. A total of 216 chicks were raised in conventional electrically heated starting batteries until 6 weeks of age. They were then allotted to environmental chambers and exposed to one of the following light treatments for 35 days: blue (450 nm.), green (545 nm.), red (650 nm.), far-red (750 nm.), dark or white. Feed and water were supplied ad libitum. Chick growth was significantly (P The wavelength of light environment affected the reproductive development of the chick. Larger pituitary glands, containing significantly (P

Studies were conducted to determine levels of dimethyl sulfoxide (DMSO) that could be administered to chicks without toxic effect. The LD50 of a single dose of DMSO in day-old chicks was between 10.0 and 12.5 ml. per kg. body weight (b.w.) by oral administration and between 7.5 and 10.0 ml. per kg. b.w. by subcutaneous injection. The maximum nonlethal single dose of DMSO was 7.5 ml. per kg. b.w. by oral administration and 5.0 ml. per kg. b.w. by subcutaneous injection. Injected for 14 consecutive days, subcutaneously, 1.25 ml. DMSO per kg. b.w. was the maximum level tolerated with no toxic effects. In male chicks, a level of DMSO greater than 1.25 ml. per kg. b.w. reduced growth rate and produced an apparent fibrosis at the injection site. In female chicks the fibrosis, but not the growth depression, was observed. Intramuscular injection of DMSO at levels as low as 0.625 ml. per kg. b.w. produced a severe local inflammation that prohibited the use of DMSO in this age chick. The advantages and limitations of DMSO as an injection solvent for chicks are discussed.

Recently there has been much interest on the biological consequences of monosodium glutamate (MSG), particularly after parenteral administration. Olney (1969) reported that subcutaneous injections of MSG into neonatal mice produced an obesity that apparently did not depend on marked changes in food intake. These results suggest increased efficiency in the use of dietary energy for tissue synthesis. Since such effects might be economically important if they occur in domestic species, we performed the following experiments with broiler chicks. PROCEDURE Four experiments were conducted. In experiment 1, the subcutaneous toxicity of a single dose of MSG was studied in day-old chicks. The role of the sodium fraction in this toxicity was also considered. In experiment 2, graded doses of MSG were injected subcutaneously daily from 1 to 11 days of age. The chickens were observed for 112 days for differences in weight gain, feed intake, or outward appearance. The effects of…

A marked growth stimulating effect of certain fats in purified chick diets has been reported by Rand et al. (1958), and Dam et al. (1959). The latter workers have also shown that soybean oil, effective in purified diets, produces a significant improvement of growth rate when added to a ration composed of practical feedstuffs and typical of those used in commercial broiler production. Further studies in this laboratory have been conducted to investigate the use of heat-treated ground soybeans as a source of soybean oil for improving growth on practical rations, but without success (Norris et al., 1958). A possible explanation of these findings has been found in other work (Renner and Hill, 1959) in which the metabolizable energy of heated ground soybeans was substantially less than that expected from prior knowledge of the values of soybean oil meal and soybean oil, due to poor digestibility of the oil in …