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This study was conducted to determine the effect of in ovo feeding of dextrin (Dext) and iodinated casein (IC) on hatch and early growth in broilers. Three experiments were conducted at a commercial hatchery using a commercial Inovoject™ system with treatments occurring in conjunction with vaccination at transfer from incubator to hatcher units (18.5 to 19 d embryonic development). In all 3 experiments, approximately 15,000 eggs (2,500 eggs per group) were treated and transferred to a single hatcher unit. Treatments in Exp. 1 consisted of buffered saline solution alone (Control, Cont) or a dextrin solution (Dext, 18% maltodextrin, 10% potato starch dextrin) containing zero, 80, 240, 720, or 2,160 μg IC/mL. The results of this initial experiment indicated that broiler chicks at hatch that received 240 and 720 μg IC/mL in Dext were heavier (P 0.05) compared to the other treatment groups; there were no differences in hatchability between groups. Based on these findings, subsequent studies used treatments of zero, 240, and 480 μg/mL IC in Dext or Cont. In Exp. 2, hatch weights in all treatment groups were higher (P 0.05) compared to those receiving Cont. In Exp. 3, chicks given Dext alone or 240 and 480 μg/mL in saline weighed less at hatch compared to the other treatment groups. However, chicks provided Dext alone in Exp. 3 had less weight loss after a 24-hour holding period compared to the other groups. All treatment groups exhibited greater weight gain from one to 10 d compared to the Cont group. The results indicate that in ovo feeding of broiler embryos with Dext containing 240 and 480 μg IC/mL may have beneficial effects on broiler hatch weights and early growth rate.

Studies were conducted using a commercial InovojectTM system to determine effects of in ovo feeding of dextrin and iodinated casein (IC) on hatch and posthatch growth in broilers. At ∼18.5 d embryonic development, eggs were treated with 0, 240, or 480 μg IC/mL in saline (Cont, IC240, and IC480) or dextrin (Dext, DextIC240 and DextIC480). The Dext solution consisted of 18% maltodextrin and 10% potato starch dextrin; saline was the vehicle used by the company for in ovo vaccination. The volume for all in ovo treatments was 50 μL/injection. Eggs in Experiment 1 were transferred to a commercial hatcher unit whereas eggs in Experiments 2 and 3 were transferred to a research hatcher unit to assess effects of treatments on timing of hatch. At hatch, chicks were randomly selected and placed in floor pens and grown to 6 wk. In Experiment 1, there were no differences in hatch weights, but broilers provided Dext IC240 in ovo were heavier (P < 0.05) at 6 wk compared to other treatments with the exception of the Dext IC240 group. In Experiment 2, hatch weights were heavier (P < 0.05) in chicks receiving IC240 and DexIC480 treatments compared to Controls. At 6 wk, broilers in all treatments were heavier (P < 0.05) than Cont with the exception of IC480. In Experiment 3, hatch was stimulated by IC240 (in saline), but was delayed by Dext IC240. Serum analysis of β-hydroxybutyrate (μM/mL), as an indicator of ketone accumulation from fat metabolism of chicks held in chick boxes for 24 h posthatch (to simulate delay in placement after hatch), indicated that chicks in the IC240 group (that hatched earlier) had higher blood ketones compared to chicks that received Dext or DextIC240 in ovo (that hatched later). We conclude dextrin and iodinated casein (240 μg/mL) provided in ovo (∼18.5 d of embryonic development) has the potential to improve chick quality and posthatch body weight by delaying or narrowing hatch window.

This paper reviews and presents data suggesting that the use of thyroxine (T4) to induce moult in poultry may be a viable alternative to previous methods involving feed withdrawal or feed avoidance...

Graham reported that the feeding of thyroxine to dairy cows in the declining phases of lactation caused a distinct rise in the amount of milk produced and in the percentage of butter fat. Synthetic thyroprotein (iodinated casein or protamone) has been reported in a number of papers to produce the same effect.

The quantitative (percentage) rumen degradability of Panicum maximum at 48hrs post rumen incubation was studied in West African (Northern) long-legged sheep using the nylon bag technique, in a 4x4 Latin square experimental design of; four sheep, four time intervals, four experimental rounding of same sample and f our levels of iodinated casein. The animals had an average body weight of 9.6 +/- 1.46kg. The animals were fitted with rumen fistula through which Panicum maximum were incubated. Various dose ranges of 1.5g, 2.5g, 3.5g, and 4.5g of iodinated casein were infused into the rumen 8hrs prior to the incubation. Potential rumen degradability of Panicum maximum was determined at time intervals of 4,8,12 and 48hrs post incubation. The results of the experiment showed that infusing a maximum dose of 3.5g of iodinated casein produced marked improvement in the rumen degradability of dry matter, organic matter and crude protein fractions of Panicum maximum and beyond this limit the effect decreased. The increase in rumen potential degradability of all the fractions of Panicum maximum was significantly different (p Keywords : Rumen, degradability, iodinated casein, Panicum maximum , sheep. Nigerian Veterinary Journal Vol. 27 (2) 2006: pp. 7-13

The purpose of this study was to determine by use of light- and electron-microscope autoradiography whether or not iodination occurred in mammary tumors of female GR mice. Of the sixty tumors studied it was found that pregnancy-dependent and hormone-induced tumors possessed iodinating ability. Although mammary glands from nonpregnant GR mice lacked the ability to iodinate, by the 16th day of pregnancy in response to hormonal stimulation the glands readily iodinated casein, and some epithelial cells contained ultrastructural cytochemical evidence of mammary peroxidase. Preneoplastic mammary gland lesions known as hyperplastic alveolar nodules were also able to iodinate, as were plaques, the disc-shaped lesions which give rise to the hormone-responsive mammary tumors in this strain. Plaques also contained epithelial cells with mammary peroxidase activity. When hormone-induced mammary tumors were transplanted into syngeneic mice they retained the ability to iodinate for several generations. However, as the tumors progressed to hormone independence, the ability to iodinate was gradually lost. Hormone-independent mammary tumors from GR mice lacked both iodinating ability and cytochemical evidence of mammary peroxidase. These findings suggest that iodination depends upon hormone-responsive cells within the mammary tumors and that as these cells become hormone unresponsive, the ability to iodinate is lost.

White Leghorn cockerels were fed a broiler ration containing 0 (controls), 0.02 or 0.04% Protamone (iodinated casein) either continuously or for 10–14 days after which the 0.02% Protamone ration was switched to control or vice versa. Body growth rate was temporarily suppressed during the first 14 days of feeding 0.02% Protamone. Thyroid weight was promptly depressed during feeding of Protamone and increased more slowly when Protamone was removed from the feed. Only a fleeting increase in oxygen consumption rate was detectable in birds fed either 0.02 or 0.04% Protamone. Serum T4 and T3 promptly rose when Protamone was fed; continued feeding resulted in compensatory adjustments in secretion and perhaps peripheral metabolism of iodohormones within 2–3 days so that a level close to 200 ng. T3 or 2.5 μg. T4/100 ml. serum was subsequently maintained.

The effects of short- and long-term (from 3 days to 28 weeks) administration of excess thyroxine in the form of the iodinated casein "Protamone" (0.2%) to rats on the content of soluble thyroid iodoproteins and on biosynthesis and polymerization of thyroid proteins in vitro were investigated. The concentration of soluble iodoproteins significantly increased (40–80%) up to 2 weeks of treatment, and after that remained at the same level. 27S iodoprotein markedly increased during thyroxine treatment. The content of DNA in the gland and the thyroid weight were a little lower in the treated rats than in the control. The incorporation rate of [14C]leucine into soluble and microsome-bound proteins in vitro was markedly reduced in the treated animals (30–80 % of control). Thyroxine pre-treatment of rats induced retarded synthesis of thyroglobulin and its subunits in vitro. The inhibition of the synthesis of thyroid proteins in vitro and the incrrease in the soluble iodopritein content in the gland in vivo was not correlated with the duration of thyroxine treatment. The immobilization of pre-formed thyroglobulin in the follicle lumen for a long time period is probably an important factor in the enlarged conversion of thyroglobulin into 27S iodoprotein. In conclusion, the long-term suppression of endogenous TSH secretion by administration of thyroxine results in an accumulation of iodoproteins in the thyroid and a reduced rate of synthesis of iodoproteins; after 2 weeks a steady state is reached both with regard to iodoprotein accumulation and synthesis. Finally, the results obtained suggest that the thyroid-pituitary axis becomes adapted to chronic administration of excess thyroxine.

Egg production, liver lipid, and liver hemorrhagic score were not significantly altered by diets that contained inositol (at 1 or 2 g./kg. diet) and fed ad libitum, or force-fed to S.C. White Leghorn hens to produce fatty liver-hemorrhagic syndrome (FLHS). FLHS was not prevented by lecithin, iodinated casein alone or with inositol. The vitamins B12, choline and E appeared to reduce FLHS and liver lipid in the one group tested. The dose-response relationship between feed intake, liver hemorrhagic score and liver lipid content was again demonstrated.

Iodinated casein at 220 mg. kg. of feed was fed to Muscovy ducklings to determine its effect on sexually differentiated growth. Nine male and eight female treated ducklings averaged 2,135 and 1,520 g. at eight weeks as compared to 2,315 and 1,588 g. for the untreated nine males and eight females. Feed conversion was 2.99 for treated and 3.60 for untreated ducklings.

Limnanthes alba or meadowfoam is a potential new oilseed crop, containing glucosinolates. Three experiments were conducted to evaluate meadowfoam meal (MFM) as a feedstuff for broiler chicks and weanling rabbits. In experiment 1, chicks were fed, for 6 wk, diets in which 30% of the dietary protein in the control diet was supplied by raw MFM, steam-cooked MFM (SC), SC plus 3% sodium carbonate (SC +), or aqueous-extracted MFM (EXT). Average daily gain (ADG) was lower (P

THE earlier attempts to stimulate the growth-rate of pigs by administration of thyroid-active substances1and of synthetic cestrogens2 have been followed by tests in which both treatments were given simultaneously.

OLNEY et al. (1962) showed that chlorinated hydrocarbon pesticides tend to accumulate in the fatty deposits of chickens. Wesley et al. (1966) presented evidence which suggested that starvation increased the depletion rate of DDT from the tissues of chickens. Repeated cycles of 48 hours of starvation followed by 24 hours of feeding non-contaminated feed reduced body fat content and body burden of DDT when starved chicks were grown to the same body weight as full-fed controls (Donaldson et al., 1968). The results with starvation suggest that any treatments which tend to decrease body fat may also tend to increase the rate of elimination of DDT residues from the body. Turner et al. (1946) showed that feeding iodinated casein to laying hens resulted in decreased deposition of subcutaneous and carcass fat. Stamler et al. (1950) found that the feeding of dessicated thyroid to chicks reduced the lipemia and fatty liver produced…

Disappearance of aqueous suspensions of beta carotene, during 3-hour incubations in the ligated intestine, was studied in three trials involving 120 rats. When 800 p.p.m. of iodinated casein was added to the diet, disappearance was significantly increased. Blood data indicate that this can be attributed to more rapid conversion of carotene to vitamin A. Adding 400 p.p.m. of iodinated casein or either 55 or 110 p.p.m. of methimazole to the diet did not affect carotene disappearance.

Sixty-three cycling gilts were assigned randomly to be started on treatment on Day 13 of the oestrous cycle. Treatments consisted of the following\p=m-\0,50 and 150 mg of a dithiocarbamoylhydrazine (ICI 33828) and 0, 1000 and 2000 mg of iodinated casein (Protamone) in all combinations administered in 1 \m=.\82kg of feed per day for 10 days. Iodinated casein significantly reduced gain in body weight while ICI 33828 had no significant effect. Only ICI 33828 significantly reduced feed consumption. Both iodinated casein and ICI 33828 at the higher doses significantly lengthened the interval from withdrawal to oestrus. Iodinated casein, a hyperthyroid compound, failed to overcome the apparent hypothyroid effect of ICI 33828 on reproduction in the gilt under the conditions of this experiment.

SEVERAL reports have appeared which suggest that thyroprotein, (iodinated casein) may have beneficial effects when fed to young chicks and, during the summer months, to laying hens (Parker, 1943, Irwin, Reineke and Turner, 1943, Turner et al., 1945, Turner, Irwin and Reineke, 1945, Gutteridge and Pratt, 1946, Gutteridge and Novikoff, 1947, Wheeler, Hoffmann and Graham, 1948). No experimental data are available, however, on the effect of feeding thyroprotein during the “growing period,” but Turner (1947) has recommended in a popular article that, “For growing pullets, the . . . (thyroprotein) feeding can continue at the rate of 15–20 grams per hundred pounds of their total feed until the approach of sexual maturity. Then the . . . (thyroprotein) can be cut to 10 grams per hundred pounds of their total feed.” The present paper reports on the effects of feeding thyroprotein during the 12 weeks period (12 to 24 . . .

Biologically defective U.S.P. thyroid tablets which have appeared recently on the American market have been prepared from triple strength U.S.P. desiccated thyroid powder supplied by a European distributor. This material, with an unnaturally high iodotyrosine and low iodothyronine content, also has a phosphorus-nitrogen ratio greater than that found in genuine U.S.P. thyroid. Chemical evidence suggests that suboptimally iodinated casein was added to thyroid powder to increase the organic iodine content of the blend. Artificial mixtures have been prepared which closely resemble the physical, chemical, and biological characteristics of known defective U.S.P. thyroid.

DURING the past few years several reports have appeared on the use of chemical compounds to influence thyroidal activity. One of these, thiouracil, has been shown to produce a hypothyroid condition as measured by decreased metabolism (Reineke, Mixner, and Turner, 1945; Mixner, Tower, and Upp, 1946; and Shaffner and Andrews, 1948). The use of this drug is of interest because the induced hypothryoidism results in an increased deposition of fat and improved market grade in growing chickens (Andrews and Schnetzler, 1946; Andrews and Bohren, 1947). However, Kempster and Turner (1945) and Glazener and Jull (1946) have also shown that thiouracil depresses rate of growth when fed over extended periods (4–5 weeks). Since thiouracil, at the levels fed, was presumably effective in shutting off the elaboration of endogenous thyroxine, it seemed possible that a milder degree of hypothyroidism might induce fattening while permitting normal growth. Thyroprotein (iodinated casein) has been . . .

YACOWITZ et al. (1954) and Waibel (1958) reported that protein levels in excess of 20 percent promoted rapid growth of young goslings. Roberson and Francis (1961 Roberson and Francis (1963) found that a protein level of 24 percent increased the growth rate of young goslings, but the advantage was lost if the geese were carried beyond the stage of rapid growth. Various workers (Snyder and Orr, 1953; Swanson and Canfield, 1955; Bean and Hanson, 1962; and Roberson and Francis, 1963) have concluded that the major problem of processing geese during rapid growth is poor feathering, which makes feather removal at slaughter extremely difficult. Iodinated casein has increased the growth and improved the feathering of Long Island White Peking ducklings especially during periods of warm weather (Baker et al., 1959). The experiments reported here were initiated to determine the effect of changes in protein level, supplemental iodinated casein, and of supplemental methionine on body…

The authors found that intramuscular in-jections of the thyroxine-free B fraction of iodinated casein [see D.S.A. 13 (3) 301 (1951), POULSEN] into lactating goats, whilst causing marked increases in the milk and butterfat yields, resulted in an average decrease in live weight of 10 per cent and in a rise in both heart rate and body temperature. The effects showed little difference from those obtained with the oral administration of whole iodinated casein. Their findings thus disagree with those of Poulsen who found that the B fraction of iodinated casein had little or no effect on live weight. E.J.M. (Abstract retrieved from CAB Abstracts by CABI’s permission)

THE quantitative magnesium requirement of young turkeys has not been established. In 1960 the National Research Council listed the starting chicken’s magnesium requirement as 220 milligrams (mg.) per pound of diet, or 484 parts per million (p.p.m.). Three reports subsequent to 1960 suggest a lower magnesium requirement for the chick. Gardiner et al. (1960), McWard and Scott (1961), and Keene and Combs (1962) used purified glucose-isolated soybean protein diets in magnesium requirement studies. Gardiner et al. (1960) found the chick’s requirement to be approximately 250 p.p.m. McWard and Scott (1961) reported that in terms of growth and survival the requirement was about 200 p.p.m. Keene and Combs (1962) found the chick’s magnesium requirement to be 265 p.p.m. when the diet contained the antibiotic, oleandomycin. Without the antibiotic, the requirement was approximately 300 p.p.m. In the latter study iodinated casein (0.03%) did not alter the magnesium requirement, but reserpine (4 p.p.m.)…

A previous report (Arscott and Combs, 1953) revealed that condensed fish solubles contain a factor necessary for normal hatchability in New Hampshire pullets fed a corn-wheat-soybean meal type ration containing adequate levels of known required nutrients. In an attempt to increase the severity of the dietary deficiency, an experimental diet, containing 93.5% oat groats, was used in this investigation. This diet (Table 1), fortified with added vitamins, minerals and dl -methionine, was expected to be quite deficient in the unidentified factor(s) normally found in animal products. Approximately 200 New Hampshire pullets were housed in pens equipped with raised wire floors. These pullets were fed a corn-wheat-soybean meal ration for the first half of a 12-week preliminary period, after which time the basal diet shown in Table 1 was used. On the basis of individual hatchability, fertility and egg production records obtained during the first half of this preliminary period, four comparable …

Seven experiments are reported in which iodinated casein was fed to pigs. The daily doses varied from 0·25 to 1·5 g. of iodinated casein per pig daily for periods of several weeks. While the higher doses adversely affected the rate of growth of the pigs, the smaller doses were not sufficiently effective to have any practical importance.The thyroid glands of the pigs receiving the iodinated casein appeared to be slightly smaller in size, but their histological picture was not affected.

In an effort to deplete laboratory animals of as yet unidentified nutritional factors and so obtain a suitable animal for assay Betheil (1947) and Ershoff (1947, 1948) have included desiccated thyroid gland or iodinated casein in their experimental diets. This device serves to increase the basal metabolic rate of the animals so treated (Ershoff [1947], Robblee [1948]) and so results in a greater demand for nutritional factors not available in adequate amounts either in the diet or by intestinal synthesis. Elvehjem et al. (1947a, 1947b) observed that the feeding of a natural ration was more satisfactory than a synthetic diet for the assay of unknown factors in commercial liver preparations. They combined this ration with the feeding of desiccated thyroid to chicks and were able to obtain significant growth responses to the administration of liver. Folley (1947) as well as other workers (Zucker [1948]) have observed the decreased growth rates obtained on the litters from animals bred on synthetic

Summary Thyroprotein in the form of iodinated casein fed at levels of 0.625, 1.25 and 5.0g. daily to dairy cows with a T.D.N. intake of 125 per cent of Morrison's standards for good cows under usual conditions (10) produced no significant stimulation of milk production, milk fat production, heart rates, respiration rates or body temperatures. Gains in body weight and breeding efficiencies were not affected significantly. These same levels of thyroprotein feeding accompanied by a T.D.N. intake of 110 per cent of Morrison's standards for good cows under usual conditions (10)produced increases in milk production which approached statistical significance. Milk production appeared to decline when thyroprotein was withdrawn from the ration. Mean milk fat percentage, body weights, heart rates, respiration rates, body temperatures and breeding efficiencies were not affected significantly by these levels of thyroprotein administration.

Summary Two experiments were conducted to test the effect of iodinated-casein feeding on the production and health of Jersey and Holstein milking cows under Louisiana conditions. In a reversal trial 6 cows were used and 15 grams of iodinated casein per cow were fed daily. Twelve cows were used in a continuous trial and iodinated casein was fed at the approximate rate of 1.5 grams for each 100 pounds of live weight. The milk and fat production and the health of the cows fed iodinated casein were affected as follows: 1.Significant increases in milk yields and percentage of fat were obtained during the reversal trial. However, during the continuous experiment higher fat tests were shown for the first 6 weeks and increased milk yields for the first 5 weeks, but following this the control cows averaged higher in production. 2.The average increases of pulse rates were 10 and 13 beats more per minute, respectively, during the reversal and continuous experiments. 3.Three Holstein cows showed excessive body-weight losses of 98, 106, and 154 pounds during the reversal experiment. Body-weight losses aver aged 32 pounds for the first 8 weeks on iodinated casein; whereas, the control cows gained an average of 36 pounds during the same period of the continuous experiment. After the 8th week the average weights held quite constant. 4.Body temperatures appeared to be closely correlated with atmospheric temperatures. Those cows receiving iodinated casein showed higher body temperatures and were more sensitive to atmospheric temperature changes than were the control cows.

Summary An electrophoretic study of commercial casein, iodinated casein, and Prota-mone was made in a new model no. 38 electrophoresis apparatus (Perkin-Elmer Corp.). It was observed that casein consists of an α and β component. The observations of other investigators of the electrophoretic pattern of casein were confirmed. It was observed that Protamone, unlike its mother substance casein, was homogeneous electrophoretically. The electrophoretic mobility of Protamone was −6.0 to −9.2 10−5 at pH 6.0, 8.3 and 7.5 in acetate and barbiturate buffers with an ionic strength of 0.1. Furthermore, the electrophoretic mobility of Protamone was significantly higher than either α or β-casein under all the conditions studied. It also was observed that incubation with stirring of casein at 39° C. did not change the electrophoretic pattern in barbiturate buffer pH 7.5 with an ionic strength of 0.1. However, when iodine was added the electrophoretic pattern was changed and only a small peak of β-casein was observed. Casein incubated at 70° C. with or without iodination when studied electrophoretically in barbiturate buffer pH 7.5 with an ionic strength of 0.1 showed a single peak.

CONFLICTING data are recorded in the literature as to the effect of iodinated casein on the performance of laying birds. Turner and co-workers (1945a, 1945b, 1946b, 1948) have presented evidence indicating that iodinated casein will help to sustain egg production of hens during the later months of the first laying year. Certain of these data also indicate that the drug will tend to increase the rate of lay of birds in subsequent years beyond the first laying year. In contrast, Hutt and Gowe (1948), Hoffman and Wheeler (1948), and Godfrey (1949), failed to obtain any response in egg production by feeding iodinated casein. Wilson (1949) found that the feeding of iodinated casein did not prevent a decline in egg production due to high ambient temperatures. Gutteridge and Pratt (1946), Gutteridge and Novikoff (1947), Hoffman and Wheeler (1948), and Godfrey (1949) have recorded data showing that the inclusion of iodinated casein . . .

Two experiments, each of ten months duration, were conducted to determine the effects of iodinated casein supplementation upon the performance of egg-type hens receiving various levels of sulfur amino acids. Eight replicate groups of five individually caged hens were assigned to each dietary treatment. Dietary treatments consisted of sulfur amino acid levels of 0.355 and 0.412 percent in experiments 1 and 2, and an additional level of 0.592 percent in experiment 2. All of these diets were fed with and without the addition of 220 mg. of iodinated casein per kilogram of diet. Iodinated casein supplementation resulted in significant reductions of hen-day egg production for diets containing 0.412 and 0.355 percent sulfur amino acids in experiments 1 and 2, respectively. In experiment 1 iodinated casein significantly decreased the feed efficiency and significantly increased the daily feed intake of birds receiving 0.355 percent sulfur amino acids. Diets of experiment 2 containing 0.355 and 0.412 percent sulfur amino acids and iodinated casein were associated with significant feed efficiency decreases as compared to comparable control diets, and the lower amino acid level resulted in a significant reduction of feed intake when iodinated casein was included. Although the performance of birds receiving the 0.592 percent sulfur amino acid diet of experiment 2 was not significantly reduced by the addition of iodinated casein, numerical depressions due to supplementation were evident. Egg weights were not significantly affected in either experiment. Body weights were significantly reduced only in experiment 2 with the diet containing 0.355 percent sulfur amino acids.

Five experiments were reported, involving a total of over 350 mice, in feeding trials concerned mainly with growth rates and feed utilization. One experiment involved gestation-lactation performance of mice fed rapeseed oilmeal as a ration component.Proportions of rapeseed oilmeal ranged from 17 to 50 per cent of the diet. The feeding of iodinated casein or of potassium iodide failed to counteract the growth-depressant factor in rapeseed oilmeal. Aureomycin as a feed supplement was ineffective against the factor.Growth, tissue composition and lactation data confirmed the deleterious nature of high levels of rapeseed oilmeal in the ration and provided evidence that species and sex differences in response to the rapeseed oilmeal factor exist. Males appeared to be more severely affected than females. Mice did not respond to iodine and to iodinated casein as has been reported for chickens and turkeys.

SummaryAddition of an iodinated casein with thyroid activity to a purified diet adequate in all known essential nutrients produced a growth retardation in mice. Growth inhibition was reversed by fractions of whey and by whey ash. The active inorganic component was found to be bromine.

THE effect of various thyroproteins on laying hens has been studied fairly extensively since 1923 when Crew and Huxley first attempted to demonstrate that thyroid feeding had an effect on egg production. Turner et al. (1945a, b) found that protamone, an iodinated casein with high thyroidal activity, increased egg production when added to the diet. These workers concluded that an optimum level of protamone in the feed ranged between five and ten grams per hundred pounds of feed. Additional work by Turner et al. (1946) demonstrated that protamone fed continuously at ten grams per 100 pounds of feed prevented a decrease in egg production during the summer months. Work by Singh and Shaffner (1950) indicated that thyroprotein elevated the basal metabolic rate. However, Lillie et al. (1952) questioned whether it improved egg production although the hen’s basal metabolism was increased. The use of estrogens to prevent further degeneration and relieve…

Feeding of iodinated casein to rats produces marked variations in the adrenaline and noradrenaline content of heart, spleen, liver, adrenals, and blood. An impairment in the destruction of the injected adrenaline is noticed in similarly treated animals. The significance of these results with reference to the thyrotoxic process is discussed.