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Eggs laid by hens experimentally infected with Salmonella enteritidis were assayed for the presence of Serogroup D-specific yolk antibodies. Yolk antibodies were detected with S. enteritidis and Salmonella pullorum antigens in the microantiglobulin test as early as 9 days after inoculation of hens with S. enteritidis. Yolk antibody titers reached peak levels at 3 to 5 wk postinoculation and remained at detectable levels for at least 7 wk postinoculation in eggs from both orally inoculated and horizontally contact-exposed hens. Eggs laid by hens from commercial flocks implicated in epidemiological investigations of human S. enteritidis outbreaks were also tested. Serogroup D-specific yolk antibodies were detected in 5 to 22% of eggs from hens in houses identified as infected by bacteriological culturing of internal organs of hens for S. enteritidis.

Due to the numerous proposed cardiovascular benefits associated with consumption of omega-3 fatty acids, marketing of an egg enriched by omega-3 fatty acid may benefit the egg producer. Effects on yolk composition of a standard laying hen diet enriched with 3% menhaden oil (test diet), versus an isocaloric (control) diet containing no added fat, were evaluated for 18 wk. Dietary menhaden oil did not alter egg production, egg weight, total yolk fat, or yolk cholesterol. However, yolk contents of omega-6 and omega-3 fatty acids were influenced by diet. Arachidonic acid decreased and eicosapentaenoic acid increased in eggs from hens fed the test diet following 1 wk of dietary treatment. Docosahexaenoic acid and linolenate increased in eggs from hens fed the test diet at 2 and 3 wk of the trial, respectively. These alterations in yolk composition resulted in a decrease in the ratio of omega-6 to omega-3 fatty acids from 18 for eggs from hens fed the control diet to 3 for eggs from hens fed the test diet. At Weeks 14 and 18, hens (n = 10 per diet) were killed and necropsied. No change in gross scoring of hepatic lipidosis was observed. Histologically, significantly greater scores for hepatocellular lipid infiltration were recorded for liver sections from hens fed menhaden oil than for control hens. Increased microscopic hepatic lipid infiltration observed with dietary omega-3 administration may have significance for flocks predisposed to fatty liver syndrome and may also provide a unique system in which to study the effects of dietary omega-3 fatty acids on liver lipid metabolism.

Doxycycline (DOTC) and oxytetracycline (OTC) were dissolved in drinking water (0.5 g/l) and supplied to laying hens for 7 consecutive days. Eggs laid were collected daily during and after medication, and the antibiotic concentrations in the yolk and albumin were determined by the cup-plate method with Bacillus cereus var. mycoides ATCC 11778. The concentrations of both antibiotics were increased in yolk day by day with the advance in medication, reached peaks 2 days after withdrawal and then declined gradually. Mean peak concentrations in the yolk were 6.70 micrograms/g for DOTC and 1.42 micrograms/g for OTC. Peak concentrations in the albumin occurred in the middle stage of medication, where the mean values were 12.24 micrograms/g for DOTC and 1.03 micrograms/g for OTC. DOTC was detected in albumin until 24 days after withdrawal and for 2 days more in yolk than in albumin. OTC was detected in yolk until 9 days after withdrawal. The depletion period of OTC was shorter for the albumin, where the residue disappeared in all eggs 6 days after withdrawal. In spite of similarities between DOTC and OTC in structure, DOTC was deposited in higher concentrations and lasted for a longer period in eggs. This characteristic was considered due to its greater lipophilicity, closely correlated with oral absorption and tissue penetration.

1. Exposure of laying hens to elevated ambient temperatures (30-40 degrees C) resulted in a significant increase in the biotin concentrations in plasma and egg yolk. 2. Exogenous oestrogen administration to immature pullets increased plasma biotin three-fold. The increase was six-fold when the birds were simultaneously exposed to an ambient temperature of 35 degrees C. 3. It is proposed that ambient temperature affects the balance between thyroid and ovarian hormones resulting in increased circulating levels of biotin and deposition of the vitamin in egg yolk.

Single Comb White Leghorn laying hens that were 60 wk of age were fed wheat and soybean meal diets containing either 0 or 1% cholesterol. Birds were artificially inseminated, and fertilized eggs were collected for incubation after a plateau of egg cholesterol content was reached. Posthatch chicks were raised with starter diets containing either 0 or .5% cholesterol. Samples of developing embryos and posthatch chicks at various stages were prepared for cholesterol analysis. As compared with controls, cholesterol content of eggs from hens fed 1.0% cholesterol diet was increased by approximately 70%. Embryos from the cholesterol-loaded eggs had significantly higher (P less than .05) cholesterol content. The plasma total cholesterol (TC) level in chicks from cholesterol-loaded eggs, when compared with TC in control eggs, was significantly higher at hatching but decreased to the same level by 2 wk after hatching. Cholesterol feeding to newly hatched chicks elevated plasma TC and high-density lipoprotein cholesterol levels. The TC contents of liver and heart, but not skeletal muscle, were significantly higher in chicks fed the .5% cholesterol starter diet than those fed the cholesterol-free diet. These results show that cholesterol metabolism in developing embryos and posthatch chicks is influenced by cholesterol in both maternal and chick diets.

1. The elimination kinetics of four macrolide antibiotics (tylosin, erythromycin, spiramycin and josamycin) in eggs were determined separately for albumen and yolk after oral administration through either drinking water or diet or after intramuscular injection. 2. Residues were assayed by a plate diffusion technique in cylinders with Micrococcus luteus as the test-organism. 3. Drug excretion was usually over a longer time in the yolk. Spiramycin was the most highly excreted in the egg whereas seven to eight times less tylosin and erythromycin was transferred. The conditions for the use of macrolide antibiotics in laying hens are discussed.

The fat content and the concentrations of glucose and triglyceride in day-old chicks hatched from 27 and 60 wk-old broiler-breeder hens were determined from pooled samples of residual yolk and blood serum, respectively. Serum glucose and triglyceride levels were unaffected (P greater than .05) by breeder age, although there was a linear (P less than .001; r = .67) relationship between these characteristics and chick weight. Yolk fat, adjusted for chick weight, was on the average 13% greater (P less than .05) in chicks from old breeders than chicks from young breeder hens. Yolk wet weight was not affected (P greater than .05) by breeder age. Results indicate that breeder age may affect chick performance through alterations in the fat content of residual yolk.

An experiment was conducted to determine if adding supplemental cholesterol to the feed or first adding it to the supplemental fat source of laying hen diets would result in differences in egg yolk and liver cholesterol levels. Five levels of cholesterol (0, .5, 1, 2, and 4%) and three levels of animal tallow (0, 4, and 8%) were used. The diets were randomly assigned and fed for 35 days to individually caged hens within each of six replicates. Eggs laid on or near Days 0, 7, 14, 21, 28, and 35 were used for cholesterol analysis. Liver cholesterol, egg production, and feed intake were also assessed. Mixing cholesterol with the fat source before feed incorporation did not promote higher yolk or liver cholesterol levels and were essentially the same as the method in which powdered cholesterol was added directly to the feed. A linear increase in yolk and liver cholesterol was observed with 0, .5, and 1% dietary cholesterol. Yolk cholesterol also increased linearly during the first 14 days of cholesterol administration. Further increases in yolk cholesterol, however, were not obtained with either the higher levels of dietary cholesterol or the extended feeding times.

The titers of hemagglutinins to human erythrocytes were investigated using sera and eggs from hens immunized by a single intraperitoneal injection of crude blood group substance from OSe saliva mixed with Freund's complete adjuvant. Elevation of the hemagglutinin titer in egg yolk followed the increase of serum hemagglutinin with 1- to 2-week time-lag. The maximum hemagglutinin titer of egg yolk was 1/2 to 1/8 of the serum hemagglutinin titer. The total hemagglutinin quantity in egg yolk exceeded the serum quantities of the antibody in sacrificed hens. Egg-white transiently contained a very low titer of hemagglutinin. The yolk hemagglutinin scarcely migrated at all to the white after storage of the egg for 3 months at 5 degrees C. These results indicate that egg yolk from hens immunized with blood group substances is an appropriate source of blood group hemagglutinins.

Hens were immunized intraperitoneally with OSe saliva mixed with Freund's complete adjuvant, and the properties of hemagglutinins in sera and egg yolk were compared. Both serum and egg yolk hemagglutinins agglutinated O, A1, B and A1B erythrocytes to a similar degree, and both showed somewhat stronger agglutinating potencies at 5 degrees C than at 25 degrees C or 37 degrees C. The degrees of agglutination were little improved by the addition of 20% BSA or PVP medium solution for potentiating incomplete agglutinin. The antiglobulin-augmentation reaction with specific anti-chicken-Igs revealed that the principal immunoglobulins of the serum hemagglutinins produced during the early and hyperimmune phases of immune response were IgM and IgG, respectively; whereas the presence in egg yolk of both IgM and IgG hemagglutinins was demonstrated throughout the antibody producing periods. The yolk probably contained IgM incomplete hemagglutinins, because addition of an antiserum to chicken-IgM strongly enhanced the yolk hemagglutinin. The secretor status of six saliva specimens, OSe, Ose, ASe, Ase, BSe and Bse, was tested by the agglutinin-inhibition reaction using one of the following reagents: Ulex lectin, chicken antiserum, and egg yolk hemagglutinin. High inhibition titers of OSe saliva were obtained with the serum hemagglutinin (of the early and hyperimmune phases) and the yolk hemagglutinin of the eggs laid in the hyperimmune phase. The test with Ulex lectin showed a moderate grade of inhibition, and the use of yolk hemagglutinin produced in the early stage of immune response resulted in very low inhibition titers. Yolk hemagglutinins produced in the early and hyperimmune stages were more strongly inhibited by ASe and BSe salivas than by other hemagglutinin reagents. These results indicate the availability of blood group agglutinins in the yolks of eggs laid during the hyperimmune stage.

1. Eighteen Warren SSL hens of 71 weeks of age were forced-moulted by ad libitum feeding of a high-zinc diet (10,000 ppm zinc for 2 days followed by 5,000 ppm zinc-supplement diet for 4 days). From the start of the treatment, eggs were collected and 3 hens were slaughtered on days 0, 2, 3, 4, 5 and 6 of the study. 2. Zinc analyses were carried out on the different components of the eggs and on liver, pancreas, kidney, different yolky follicles of the ovary and various segments of the oviduct. 3. Seven-, six- and threefold increases in zinc concentration were found in pancreas, liver and kidney, respectively. 4. The shell gland and isthmus, but not the magnum, also showed slight but significant increases in Zn content. 5. Zinc accumulation was also high and almost identical in ovarian follicles F1 to F4 but slightly less in F5 and F6 follicles. 6. In the egg, a significant increase in zinc concentration was only observed in the yolk.

Two studies were conducted to determine the effects of anticoccidial agents on the production and reproduction of White Leghorns. In Experiment 1, nicarbazin (NCZ) was fed at 0, 20, 50, and 100 ppm. Hen-day egg production, egg weight, the egg-yolk DNC (4-4'-dinitrocarbanilide) level, and egg-yolk mottling were affected by the treatments. When response was evidenced, the relationship between those variables and the level of NCZ was basically linear. Decreased egg production occurred from Days 5 and 6 of the treatment through Days 1 and 2 of withdrawal. On Days 9 and 10 of treatment, the control hens peaked at 92% hen-day production, while hens fed 20, 50, and 100 ppm of NCZ peaked late--at 90, 82, and 80%, respectively. Compared to the controls, egg weight was reduced linearly as the level of dietary NCZ increased. The egg-yolk DNC level increased from Days 3 and 4 of treatment through Days 9 and 10 of withdrawal. Egg yolk mottling generally increased along with the level and duration of feeding NCZ. If the NCZ was mistakenly fed to White Leghorn layers, ill effects would be alleviated within 10 days after drug withdrawal. In Experiment 2, halofuginone (3 ppm), maduramicin (5 ppm), monensin (100 ppm), narasin (70 ppm), nicarbazin (125 ppm), robenidine (33 ppm), and salinomycin (60 ppm) were fed to White Leghorn hens at the levels specified in parentheses. Nicarbazin reduced egg production, depressed egg weight, reduced shell thickness, and caused egg-yolk mottling; but internal egg quality, as measured by Haugh Units, was unaffected. Halofuginone, maduramicin, monensin, narasin, robenidine, and salinomycin did not have a meaningful effect on the variables measured when fed to White Leghorn layers.

Egg production type chickens were given the drug Probucol in their diets to determine its effect on egg production characteristics, liver lipid metabolism, egg yolk lipid synthesis, and egg yolk cholesterol concentration. In none of the three trials conducted did Probucol feeding affect egg production or body weight. The drug reduced total liver lipogenesis as measured by incorporation of 14C-acetate by surviving liver slices. Relative incorporation of 14C-acetate into cholesterol by liver was increased by the drug. However, in ovo incorporation of 14C-acetate in total yolk lipids remains unchanged and relative incorporation into yolk cholesterol is reduced. As a result, egg yolk cholesterol content is reduced by 5% with the .10% dietary level of drug administration.

Each of three colostomized laying hens received per os 0.2% L-Lysine with 48 atom-% 15N-excess (15N') labelled in alpha-position in addition to a pelleted laying hen ration of 120 g over a period of 4 days. On the following 4 days they received equal amounts of unlabelled lysine. The eggs laid during the 8 days of the experiment were separated into the white of egg, the yolk and the eggshell, and the to and heavy nitrogen in the individual fractions were determined. Above that, 17 amino acids and their atom-%15N' were determined in the 19 samples of the white and yolk of egg. Of the total 15N' from the lysine fed in the 4 days, 10.1% were found in the yolk, 10.5% in the white of egg and 1.1% in the eggshells of the eggs laid during the 8 days of the experiment. 85% of the total amino acid-15N' of the yolk and 86% of the white of egg detected to be lysine-15N'. The 15N'-amount of the other 16 amino acids was mainly concentrated in the two acid and basic amino acids. Approximately 50% of the non-lysine 15N' in the egg are contained in aspartic acid, glutamic acid, histidine and arginine. A very low incorporation of the labelled lysine only could be detected in the aromatic and sulphur-containing amino acids from both the yolk and the white of egg. 43% of the 15N' was detected in the 10 essential and semi-essential (except lysine) and 57% in the 6 non-essential amino acids of the yolk and 52% and 48% resp. of the white of egg. One can summarize that the incorporation of 15N' into the egg shows the same development as that of the labelled amino acids of the wheat protein and that 15% of the lysine-15N' could be detected in the 16 other amino acids.

Chicken tissues were intrinsically labeled with a stable isotope of selenium (76Se) and were evaluated for use in a human feeding study. Laying hens were fed a low Se (0.06 ppm) basal diet for 39 days and then fed the basal diet supplemented with 0.3 ppm enriched 76Se (as selenite) for 35 days. Incorporation of 76Se into samples was determined by use of a double isotope dilution technique and a combined gas chromatography/mass spectrometry analysis. The 76Se content of the basal diet was increased by a factor of 9.7 with the addition of the enriched stable isotope. This maximal level of enrichment was approached in egg yolk (9.5-fold) and liver (9.0-fold). Enrichment was lower in egg white (7.2-fold) and breast meat (5.0-fold). Level of enrichment in a given tissue reflected both the turnover rate of the tissue and its natural selenium content. Selenium-depleted laying hens continuously fed 76Se at the 0.3 ppm level produced egg yolks and livers that were enriched sufficiently with the stable isotope for use in a human metabolic study.

Clearance of sulfamethoxazole (SMX, or sulfisomezole) in eggs and tissues of chicken after withdrawal of the drug which was medicated feed additively (at 0.2 or 0.4%) or administered intramuscularly (100 mg./kg., twice daily) for 5 successive days was determined using a fluorescamine reagent. Clearance patterns of SMX were found to be different between albumen and yolk. SMX level in albumen diminished linearly to below 0.1 p.p.m. (sensitivity level) by 5 days after the cessation of medication. On the other hand, SMX level in yolk remained at a plateau until 4 days, and thereafter decreased linearly to below 0.1 p.p.m. by 10 days. SMX levels in most tissues diminished below 0.1 p.p.m. by 3 days and those in kidney and skin by 4 days. Clearance patterns in tissue were quite similar to those in egg albumen. Proportion of acetylated-SMX to total-one in both albumen and yolk tended to increase up to 10% with the lapse of time after drug withdrawal. Acetylation was high in liver (36.5-43.6%), spleen skin and fat, but low in breast muscle and kidney (3.7-11%) in the groups of feed addition; while acetylation was low in liver of the group of intramuscular injection.

White Leghorn hens, housed in cages were fed commercial-type corn-soy diets containing one of three levels of 3-Nitro-10 (0, .0025, and .005%) and either of two levels of xanthophyll (high and low) supplied by yellow corn. Egg yolks were collected and the yolks analyzed for color using reflectance colorimetry. The addition of 3-Nitro-10 at either level increased egg yolk dominant wavelength (DWL) and excitation purity (EP) values while decreasing luminosity (LUM) values (probability levels: .08, .10, and .003, respectively). It was concluded that the addition of 3-Nitro-10 to the diet of laying hens improved egg yolk color.

An unusual yolk material (waxy yolk) was identified in some hard boiled yolks of one strain of domestic hen. Its structure was consistent with it being formed from normal yolk through disruption of the yolk spheres. These are normally stable during even long periods of storage. Formation occurs mainly after ovulation, during passage of the egg down the oviduct; only rarely could it be found in the larger follicles of the ovarian hierarchy. In the flock of birds examined the incidence of eggs with waxy yolk was 75% of all eggs laid over a 7 d period. Of the 173 birds tested, the eggs of only 17 birds were totally unaffected; all eggs of 82 birds contained this material. The results of a hatchability trial indicated this material had no apparent influence on the embryo or hatchability.

Comparative data collected over two years are presented which refute the popular press claims that blue-shelled eggs of Araucana chickens have higher protein levels and lower cholesterol levels than market eggs. These comparisons were made between the eggs from the strains of Araucanas and those of White Leghorns and Sex-links. None of the differences found between test groups in % protein/g. albumen and % protein/g. yolk were shown to be consistently related to any one test group type. However, all Araucana test groups were significantly (P less than .01) lower in their total egg protein content than either control group by from 2.8--6.5%. This lower total protein content was the result of a consistent increase in the yolk/albumen ratio of the Araucana eggs over the market eggs. The Araucana eggs were consistently higher in their cholesterol levels on a mg./g. yolk basis than either of the market eggs. These increased concentrattions ranged from 2.0--6.9%.

Hatching eggs from 48 and 55-week-old Small White turkey breeders were used to examine the yolk sac of these poults. Influences due to flock age, egg weight, poult sex, and a two day postplacement regimen of feeding or fasting were evaluated in a factorially designed experiment. Each variable was found to act independent of the other. Older breeders gave eggs having a greater percentage yolk and with more ether extract than if they were from younger hens. For the most part, these fundamental differences remained with the poult's yolk sac at and after placement. Examining egg weight effects apart from hen age showed that heavier eggs had heavier yolks but their percentage of the total was to the converse and no compositional differences appeared. Poults from large eggs had a greater amount of yolk sac that contained proportionately less ether extract than if they were from small eggs. In total, yolk sac found ca. 12 h after poult removal from the hatcher corresponded to reserves that would remain ca. two days after formal hatching. The yolk sac free carcass failed to exhibit any compositional differences regardless of egg source or weight upon placement, but 48 hr later changes occurred that could largely be attributed to interim yolk resorption. Fasting delayed yolk sac uptake and favored removal of moisture and lipid to a greater extent than protein while the converse was true if access to feed and water was permitted. All parameters were unaltered because of poult sex.

A two-step chromatographic procedure was developed for the isolation and purification of hen IgY antibodies from egg yolk. The antibodies were completely separated from vitellin and lipids by hydrophobic interaction chromatography followed by gel filtration. Almost no residual yolk proteins, no immunoglobulin aggregates, and no antibody fragments could be detected in the final extract. Moreover, the method described, guarantees the recovery of antibodies of undiminished activity. Although the final yield is somewhat lower than that obtained by an isolation method consisting of two precipitation steps with polyethylene glycol and alcohol respectively, the procedure described is particularly recommended when highly purified antibody preparations are needed.

Crossbred pullets reared on a low plane of nutrition had a lower mortality rate due to Marek's disease and lymphoid leucosis in the laying phase and had smaller livers with less fat than those reared on a high plane of nutrition. On the other hand, the addition of 0.06% methionine to the laying diet increased the incidence of deaths due to Marek's disease and lymphoid leucosis. The spleen weight of birds fed the diet supplemented with methionine was greater than that of those fed the unsupplemented diet. The source of cereals in the laying diet had no effect on mortality, but birds fed diets with barley had larger livers and spleens. The gizzards and intestinal tracts of the birds fed the diet with oats were larger than that of birds fed diets based on barley. The inclusion of 2.5% rapeseed oil in the laying diet resulted in haemorrhage of ovarian follicles and reduced the proportion of yolk in the egg.

1. The transfer of aminoglycoside antibiotics into eggs was determined separately from albumen, yolk or whole egg after oral administration of dihydrostreptomycin (DHS), neomycin and spectinomycin and after an intramuscular injection of DHS. Residues were assayed by an agar plate diffusion method in cylinders with a specific test organism for each antibiotic. 2. Only DHS, administered by the intramuscular route, led to detectable residues in eggs. The total amount of DHS excreted via the eggs represented 1% of the dose administered. 3. Residues in the whole egg were detected for 8 d.

The cholinesterase (acylcholine acylkhydrolase, EC 3.1.1.8) of chicken egg yolk was partly purified and characterized. It was compared to homologous enzymes of liver and blood plasma of laying hens. During gel filtration, yolk and liver cholinesterase were resolved into two fractions. Blood plasma cholinesterase showed one form only, identical with yolk and liver cholinesterase 1 *** (EC 3.1.1.8). This form has an Mr of 440 000 and may be a tetramer of a cholinesterase form present in yolk and liver (Mr 104 000). Substrate specificity, pH optima, Km values, the influence of effectors (ammonium derivatives, choline, eserine, fluoride), gel filtration, gel electrophoresis, isoelectric focusing and affinity chromatography, all point to a very close similarity, if not identity, of the corresponding forms.

Practical diets containing various selenium levels, with and without selenite supplementation, were fed to hens. Eggs were then collected over a 14-day period to determine how quickly changes in dietary selenium affected egg white and yolk selenium. Changes in egg white selenium content were rapid and essentially completed seven days after changing the selenium content of a practical diet. Changes in egg yolk were not yet completed by 14 days. When selenium from practical feedstuffs was fed, the selenium content of dried egg white was about equal to or greater than the selenium content of dried egg yolk. When selenite was fed, the selenium content of dried yolk was higher. Feeding selenomethionine resulted in more selenium in egg white than in egg yolk. Feeding selenocystine resulted in more selenium in egg yolk than egg white, a pattern similar to that from feeding selenite. The data suggest that selenocystine is not incorporated into protein but is metabolized to an inorganic selenium compound.

The concentrations of 59Fe and of radioiodinated transferrin and albumin were measured in the blood, liver, spleen, bone marrow and ova at different times after the injection of transferrin-bound 59Fe and the labelled proteins into non-laying, laying and oestrogen treated chickens. In the egg-laying and oestrogen-treated birds the 59Fe of the plasma was rapidly transferred from transferrin to another component with the properties of th phosphoprotein, phosvitin. Radioactive iron, and labelled transferrin and albumin to a lesser extent, entered the ova only while they were in the ovary. Relatively more labelled transferrin than albumin was found in all the tissues studied except in the ova, in which the two labelled proteins were present in the same relative concentration as in the plasma. It is concluded that, during egg laying and after oestrogen treatment, plasma iron bound to transferrin is taken up by the liver, incorporated into phosvitin and is then secreted into the plasma leading to elevation of the plasma iron concentration and transfer of iron to the ova.

In 5 experiments with 1,296 laying hybrids at the age of 22-73 weeks producing eggs for consumption a varied supplementation of between 0 and 20 mg vitamin E per kg of a semisynthetic ration was tested. The vitamin E content of the basal ration was less than 1 mg per kg feed. The quotas of selenium and unsaturated fatty acids in the feed were taken into consideration. Vitamin E and Se supplements did not influence, feed intake, laying, performance, feed efficiency/100 g egg development of body weight and mortality. The supplementation of 14% vitamin-E-free sunflower oil caused a significant decrease of the laying performance by 15%. There was no relation between the humoral immune reaction and vitamin E supply. The peroxide value of the abdominal fat and the activities of the creatine phosphokinase, the aspartate and alanine amino transferase in the blood serum were not directionally changed by the vitamin E, Se and oil supplements. There were no significant relations between the vitamin E content of the feed and that of the yolk and the yolk sac of the chicken. A vitamin E requirement of less than 1 mg and a requirement norm, including a safety margin, of 5 mg per kg feed was derived from the results for laying hens for egg production. A supplement of synthetic vitamin E to laying hen feed is thus not necessary.

Egg yolk was evaluated in the enzyme-linked immunosorbent assay (ELISA) as an alternative source of antibodies for detection of Mycoplasma gallisepticum (MG) and M. synoviae (MS) infections in chickens. There was no statistically significant difference (P greater than 0.05) between the ELISA geometric mean titers (GMTs) of saline-diluted egg yolk and chloroform-extracted egg yolk, and both preparations had a high correlation coefficient (0.87 for MG; 0.97 for MS). The saline-diluted and chloroform-extracted yolk had a relative sensitivity of 90% and specificity of 98% in the MG ELISA; in MS ELISA they were 100% and 96%, respectively. Hemagglutination-inhibition (HI) results with chloroform-extracted samples were satisfactory, but those with saline-diluted samples were not. Neither preparation was satisfactory for use in the rapid plate agglutination (RPA) test. A 1-ml sample of yolk was compared with the whole-yolk method. The chloroform-extracted whole yolk yielded a significantly higher (P less than 0.05) GMT in the MG ELISA; however, there was no statistically significant difference (P greater than 0.05) between GMTs yielded by the two procedures in the MS ELISA. The correlation coefficients for the two sampling methods were 0.73 for MG ELISA and 0.63 for MS ELISA. ELISA detected no statistically significant difference (P greater than 0.05) between GMTs of serum and chloroform-extracted yolk from individual birds. Results with the HI test were comparable to those with ELISA on the same samples. The RPA test yielded comparable results on the serum samples. No statistically significant differences (P greater than 0.05) were observed in HI or ELISA antibody levels between egg-yolk samples and sera on random samples collected from nine flocks that were MG- and MS-free or were infected with MG, MS, or both; however, egg-yolk samples tended to have slightly higher titers than sera in both tests. The optimum screening dilution of chloroform-extracted yolk for detecting MG and MS antibodies by ELISA was 1:800.

A study has been made of the changes in the weights, lipid and fatty acid compositions of the liver and residual yolk complex of the chick during the immediate period following hatching. By the 5th day after hatching about 85% of the gross weight and 90% of the lipid associated with the yolk complex had been absorbed. During this period, the composition of the yolk lipid displayed a marked increase in its proportion of cholesteryl esters and decreases in the triacylglycerides and phosphoglycerides. Whereas, in the triacylglycerides of the residual yolk after hatching there were changes in the proportions of the saturated fatty acids, in the phosphoglycerides there were distinctive changes in the proportions of the polyunsaturated fatty acids. Growth of the liver after hatching was associated with a substantial accumulation of fat. The very high level of cholesteryl esters associated with the embryonic liver was rapidly replaced by triacylglycerides in particular, and phosphoglycerides. The accumulation of the triacylglycerides was accompanied by a rapid change in their fatty acid composition away from that associated with embryonic development and differing markedly from that of the triacylglycerides being absorbed from the yolk. The changes in the lipid and fatty acid composition of the liver were indicative of the rapid alteration for the role of the liver in the lipid metabolism of the newly hatched chick.

A linear relationship (r greater than .98) was found between the level of dietary biotin and plasma and egg-yolk biotin in White Leghorn hens after feeding the experimental diets for 2 weeks. This shows high reliability of these parameters as indicators of biotin availability. When plasma and egg yolk biotin were used to assess biotin availability in feedstuffs, they indicated low values for wheat (0%) and sorghum (10 to 20%) and high values for corn (75 to 100%), soybean meal (100%), and meat and bone meal (85%). When these parameters were used to assess commercial poultry diets, they indicated values for a "layer" diet of 75 to 100% and for a "broiler" diet of 81 to 92%. Pelleting gave an increase in biotin availability of 10% over the mash diet. This method for assessing biotin availability promises to be simple, economic, rapid, and reliable.

Laying hens received single-dose intravenous injections of one of six U-14C labeled metabolites (bicarbonate, acetate, D-glucose, glycine, L-leucine, and palmitate) at times coinciding with maximum shell formation. Eggs were collected and 14C activities in shell, yolk, and albumen were measured. Typical patterns of 14C incorporation were observed with each of the three egg fractions; in shells highest 14C activities were obtained on the first postinjection day (D+1 day), albumen on the D+2 day, while yolks increased gradually their activities from zero levels on the D+1 day, reaching a plateau at around the D+4 day. In the second experiment, the 14C entry into albumen was slower than in the first one, with bicarbonate effecting higher albumen activities in D+3 than in D+2 eggs. Levels of 14C entry into shells of eggs laid on the D+1 day by hens injected with bicarbonate, glucose, or acetate were similar; significantly lower levels were obtained with (listed in descending order) glycine, leucine, and palmitate. Highest activities in albumen were induced by the two amino acids, with leucine causing higher activities than glycine; progressively lower entries were obtained with glucose, acetate, bicarbonate, and palmitate. In yolks, highest activities were obtained with glucose, followed by leucine, acetate, glycine, palmitate, and bicarbonate. Unexpectedly high activities obtained in the albumen of the D+1 eggs, particularly with 14C supplied from glucose, indicate that 14C was transported during the shell formation stage into the egg. The physiological implications are discussed and a suggestion is made that the possibility of carbonate for shell formation being delivered to the site of this formation from the inside of the egg should not be overlooked.

The authors studied the biochemical composition of the meat of broilers, eggs, liver and muscles of laying hens of 3 generations on a 5, 10, 25, 50 and 100% (broilers), 10 and 20% (laying hens) replacement of the animal protein quota in the diet by protein obtained from the hydrogen bacteria Alcaligenes eutrophus L-1. No deterioration of the quality of the produce was found from the standpoint of the main biochemical parameters.

Normal and cecectomized laying hens were used to study the influence of intestinal (ceca) flora and the implantation of Lactobacillus acidophylus on the levels of serum and egg yolk cholesterol. The ceca had been surgically removed when the experimental birds were 16 months of age. Serum cholesterol levels of cecectomized laying hens were higher than that of normal birds; the Lactobacillus acidophylus implantation resulted in a significant decrease in serum cholesterol levels in both normal and cecectomized birds. The normal intestinal (ceca) flora and Lactobacillus acidophylus implantation did not influence fat digestibility. Egg yolk cholesterol levels were higher for cecectomized birds. A constant relationship between serum and egg yolk cholesterol was not observed.

Lipovitellin, very low density lipoproteins (VLDL), low density lipoproteins (LDL), high density lipoproteins (HDL), and proteins of d greater than 1.20 were isolated from blood plasma and egg yolks obtained from hens fed a normal diet or one containing 2.5% of crude cottonseed oil. The amounts and compositions of each fraction were determined. Hen blood plasma and egg yolk VLDL and LDL obtained from hens fed a normal diet contained similar levels of lipid, and the fatty acid compositions of those lipids were, for the most part, similar. The percentages of VLDL and LDL in total lipoproteins were similar for plasma and egg yolk obtained from hens fed the normal diet. Separation of VLDL from LDL was not clear-cut in eggs from hens fed the diet which contained crude cottonseed oil. Lipovitellin, as it is isolated from egg yolk, did not appear to be present in any appreciable amount in hen blood plasma. Hen plasma appeared to contain about 10% of a liproprotein d greater than 1.20, the lipid of which was similar in fatty acid composition to that of lipovitellin except for palmitic and oleic acids. Lipids of all the different lipoproteins isolated from plasma and egg yolks of hens fed diets which contained 2.5% of crude cottonseed oil contained more stearic acid and less palmitoleic and oleic acids than did those from normal hens. The increased content of stearic acid increased the density of the lipoproteins so that a larger proportion of the lipoproteins were in the LDL and a smaller proportion were in the VLDL than in lipoproteins from normal plasma and eggs.

Addition of the hypocholesteremic agent Probucol ((4,4'-isopropylidine dithio)-bis(2,6-di-t-butyl-phenol)) to the diet of laying hens at up to 1% significantly reduced egg yolk cholesterol content (mg/g yolk) without impairment of rate of egg production, egg weight, shell strength, albumen quality, or other production related parameters. Dietary concentration of .1% Probucol significantly reduced yolk cholesterol within 2 weeks after feeding. Higher concentrations did not further reduce yolk cholesterol. Probucol at .025% reduced egg yolk cholesterol within 4 weeks after feeding, but after 8 weeks of feeding, eggs from hens fed .025% Probucol did not differ significantly in yolk cholesterol from those fed the basal unsupplemented diet. This suggests possible adaptation in cholesterol synthesis by the laying hen.

Di-(2-ethylhexyl) phthalate (DEHP) and three structurally related side-chain analogs were fed to laying hens to determine relationships of structure to effects on lipid metabolism. Hubbard broiler breeder hens were fed either a standard laying mash control diet or the control diet containing DEHP, 2-ethylhexanol (2-EH), 2-ethylhexanal (2-EHALD), or 2-ethylhexanoic acid (2-EHA). Experimental treatments lowered feed consumption, body weight, and egg production. The DEHP and side-chain analog diets lowered plasma total lipids. DEHP, 2% 2-EH, and 1% 2-EHA diets lowered plasma free cholesterol. Liver weights were not significantly changed, but liver fat was reduced. Lipid classes were measured by quantitative thin layer chromatography densitometry. The decreases observed in plasma lipids occurred primarily in the triglyceride fraction. Liver lipid decreases occurred mainly in triglyceride and free fatty acid classes. Hen egg yolk percent fat, lipid classes, and free and total cholesterol were unaffected by any DEHP or side-chain analog diets. Plasma and liver hypolipidemic effects were observed with all of the oxidation state structural analogs of DEHP's side chain, but 2% 2-EH was the most effective treatment. These results suggest that the active portion of DEHP may be the metabolite, 2-EH, formed in vivo by hydrolysis of DEHP's ester bond.

Studies were undertaken to determine the dietary beta-sitosterol absorption in laying hens and its incorporation into the egg. Hens were divided into four groups and fed a commercial low-fat laying diet. Group 1 served as controls; the diet of group 2 was supplemented with 10% corn oil; group 3 with 4% plant sterols (emulsion in carboxymethylcellulose); group 4 with 10% corn oil and 4% plant sterols. The daily beta-sitosterol intake of hens in groups 1, 2, 3 and 4 was 0.036 g 0.095 g, 2 g and 2.56 g, respectively. After consuming the diets for 30 to 40 days, cholesterol and beta-sitosterol contents of the eggs were estimated by gas liquid chromatographic and mass spectrometric methods. Feeding corn oil with and without plant sterols increased cholesterol content of the eggs, while feeding plant sterols alone had no effect on egg cholesterol levels. The beta-sitosterol content of eggs from groups 1 and 2 was similar (60-66 mug/g yolk) and feeding plant sterols increased the beta-sitosterol content to a very small extent (82-90 mug/g yolk). Studies on the dietary beta-sitosterol and cholesterol absorption indicated that there was very little absorption of beta-sitosterol. In control hens, beta-sitosterol absorption was about 7% compared to 81% cholesterol absorption. Plant sterols feeding did not affect the beta-sitosterol absorption but reduced cholesterol absorption by 40%. Feeding corn oil alone did not affect cholesterol absorption. Failure to detect any significant amount of beta-sitosterol in these hens. At the peak radioactivity deposition in the eggs, only 2% of the absorbed beta-sitosterol radioactivity was found in the eggs of group 4 compared to 5% found in group 1, while cholesterol radiioactivity was nearly 4 to 5 times in both groups. These data suggested that laying hens synthesized specific lipoproteins for deposition in yolk.

The blood levels and tissue dispersion of sulfamoxole in poultry has been investigated. The clinical importance and public health hazards on the basis of the results obtained has been discussed.

The depletion of colistin in eggs was determined separately for the albumen, the yolk and the whole egg after oral and intramuscular administrations of colistin sulphate. Residues were assayed by an agar plate diffusion method with Bordetella bronchoseptica ATCC 4617 as test organism. Colistin residues were not detected after drug administration by the oral route, but could be detected in the yolk until eight days after intramuscular injection. The total amount excreted represented 0.9% of the dose applied.

In a study of chronic lead intoxication in mature chickens, blood lead levels were significantly lower in hens than in roosters receiving the same oral dose of lead. It was then shown that eggshells from lead-treated hens contained 6-12 times the lead concentration of eggshells from control hens. Similarly, the lead content of egg yolks from treated hens was significantly higher than yolks from controls. Lead-treated hens laid significantly more eggs during the period of observation of nearly 3 years because of the increased frequency of laying cycles, which was almost three times that of control hens. A further observation was histologic damage to the mature testes of the rooster.

The depletion of sulphadimidine (SDM) and its N4-acetyl and hydroxy metabolites was studied in eggs laid by hens after administration of either a single or multiple oral dosages of 100 mg SDM/kg. During medication and until 1 day after the last dose, the SDM and its metabolite concentrations in the egg white exceeded those in the egg yolk and reflected the plasma levels. In the period starting 2 days after the (last) dosage, the SDM concentration in the yolk became higher than in the egg white, and the drug depletion curves ran parallel. The mean maximum amount of SDM found in the whole egg was 1500 micrograms after a single and 1280 micrograms after multiple dosage. In eggs, traces of the N4-acetyl and 6-methylhydroxy metabolites could be detected (mainly in the egg white), and their concentrations were approximately 40 times lower than those of the parent drug. A highly significant correlation (P less than 0.005) was found between the development stage of the oocyte at the time of (last) medication and the amount of SDM found in the egg that developed from it. A period of 7 or 8 days after the (last) dosage of 100 mg SDM/kg/day is required to obtain SDM levels below 0.1 micrograms/g egg.