Biomedical subjects

W B Gross

Publications and source records attributed to W B Gross.

At least 37 records · Page 2Linked to original sources

PubMed1989

Effects of dietary corticosterone in young Leghorn and meat-type cockerels.

1. Cockerels from meat-type (MT) and Leghorn (LG) stocks were fed on diets containing 0, 20, or 30 mg corticosterone/kg from 1 to 22 d after hatching. 2. Within MT and within LG stocks, responses to dietary corticosterone inclusion rates were similar; however, patterns differed between these major classes resulting in stock X diet interactions. 3. Traits responding to different inclusion rates of corticosterone in a dissimilar manner for MT and LG chickens included: immunoresponsiveness, body weight, efficiency of food utilisation, feathering; relative weights of liver, spleen, bursa, testes, breast and abdominal fat pad, as well as the proportion of liver lipid. 4. No differential responses occurred for relative adrenal weight, plasma xanthophyll concentrations, proportion of breast lipid and abdominal fat, or surface and cloacal temperatures. 5. Results indicated genetic differences in thresholds for response to corticosterone and in degree of response once thresholds were reached. Within populations, sensitivities varied between target organs.

Animal Feed↗

PubMed1989

Factors affecting chicken thrombocyte morphology and the relationship with heterophil:lymphocyte ratios.

1. Thrombocytes were observed in a haemocytometer chamber and cells were classified into 5 morphological groups which were related to the extent of environmental stress. Thrombocyte morphology scores (TMS) were calculated for each blood sample. 2. Following exposure to social stress, chilling, or the injection of killed Escherichia coli, both TMS and heterophil:lymphocyte (H:L) ratios were increased. From maximum values 1 d after chilling H:L and TMS values returned to normal within 2 and 11 d respectively. 3. The addition of corticosterone (200 mg/kg) to the food resulted in increased H:L ratios whereas TMS were not affected. 4. The injection of an adrenal blocker, 1,1-dichloro-2,2 bis p-choro-phenyl ethane, resulted in decreased H:L values whereas TMS were not affected. 5. Resistance to E. coli challenge infection was not affected by TMS.

Animals↗

PubMed1989

Antibody responses to sheep erythrocytes for White Leghorn chickens differing in haplotypes of the major histocompatibility complex (B).

Lines of White Leghorn chickens were developed by selection for high (HA) or low (LA) antibody response to sheep red blood cells (SRBC) and then backcrossed to provide individuals segregating for haplotypes B13 and B21 of the major histocompatibility complex (MHC) within each selected line. Although antibody response to SRBC was consistently higher in background genome HA than LA, there was a significant interaction between background genome and MHC haplotypes. The interaction resulted from higher antibody response in B13/B21 individuals of line HA and in B21/B21 individuals of line LA. Thus, response to SRBC was dependent on particular haplotype combinations present at the MHC as well as the background genome in which they were expressed.

Animals↗

PubMed1989

Response of White Leghorn chicks fed ascorbic acid and challenged with Escherichia coli or with corticosterone.

This study was undertaken to assess the effects of dietary ascorbic acid on the growth and immunoresponsiveness of chickens when subjected to particular types of stress. White Leghorn chicks were fed diets containing no supplemental ascorbic acid, and ascorbic-acid diet (330 ppm) for 2 days or for 19 days before challenge. Then, half of the females were inoculated with Escherichia coli; half of the males were challenged with dietary corticosterone (30 ppm) for 12 days; and the remaining chicks were maintained as controls. These chicks, reared under "good" husbandry procedures, did not realize advantages in growth or feed efficiency due to the short- or long-term consumption of diets containing ascorbic acid. Incubation with E. coli resulted in considerably higher heterophil-to-lymphocyte ratios 24 h after inoculation, and E. coli-induced mortality was higher for pullets on short-term ascorbic acid than for those on long-term or no ascorbic acid. Dietary corticosterone caused differences in body weight and the relative weights of certain organs, regardless of dietary levels of ascorbic acid. The antibody response to red-blood-cell antigens from sheep was enhanced in unchallenged cockerels (no dietary corticosterone) fed ascorbic acid on a long-term basis, but dietary corticosterone overshadowed the advantageous effects of dietary ascorbic acid. These data showed that the effects of supplemental ascorbic acid on growth and on immunoresponsiveness were related to the quality of the husbandry, length of supplemental feeding, age of the chicks, endogenous-exogenous balance for ascorbic acid, and the relationship with corticosterone.

Animals↗

PubMed1989

Effect of adrenal blocking chemicals on viral and respiratory infections of chickens.

In a series of experiments chickens were treated with chemicals which block the production of corticosterone by the adrenal cortex prior to being challenged with respiratory disease (and other) agents in order to determine if the course of the diseases could be altered. Some chickens received a single intramuscular injection (14 mg/kg) of 1,1-dichloro-2,2-bis/p-chlorophenyl/ethane (ABC) dissolved in corn oil (20 mg/mL) at least 12 h before challenge. Other chickens received feed containing 500 mg/kg of metyrapone for at least 12 h before and during the challenge infection. Treated chickens were more resistant than the untreated controls to Newcastle disease virus, Mycoplasma gallisepticum, combined M. gallisepticum-Newcastle disease virus infection, and avian adenovirus group II infection. The feeding of erythromycin (1 g/kg of feed), one day before and during the challenge, reduced the severity of M. gallisepticum infection. The effects of feeding both metyrapone and erythromycin resulted in a further increase in resistance. Chickens which had been treated with ABC had less severe lesions and greater postchallenge weight gain than the controls in response to a secondary Escherichia coli infection.

Adenoviridae Infections↗

PubMed1988

Types of adrenocorticoids and their effect on organophosphorus-induced delayed neuropathy in chickens.

The present study examined the effects of a glucocorticoid and a mineralocorticoid on organophosphorus-induced delayed neuropathy (OPIDN) as previous investigations have indicated that an endogenous steroid with both properties could alter this syndrome in chickens. The glucocorticoid triamcinolone and the mineralocorticoid deoxycorticosterone were provided in the diet beginning 1 day before and continuing 10 days after triortho-tolyl phosphate (TOTP, 360 mg/kg po), phenyl saligenin phosphate (PSP, 2.5 mg/kg im), and diisopropyl phosphorofluoridate (DFP, 1 mg/kg sc). In a manner similar to that seen with corticosterone, a low concentration (0.1 ppm) of triamcinolone reduced and a high concentration (10 ppm) exacerbated clinical signs. Concentrations of deoxycorticosterone under 80 ppm also partially delayed or ameliorated ataxia induced by TOTP, PSP, and DFP, but a combination of 0.1 ppm triamcinolone and 80 ppm deoxycorticosterone was not more effective than triamcinolone alone. Peripheral nerve damage was noted in all chickens given organophosphorus compounds, whether or not they had been given corticoids. Both steroids induced hydroxylase activity, but effects on most other enzyme systems examined were unremarkable. High concentrations of triamcinolone (10 ppm) could, however, also reduce liver cytochrome P450 levels and liver cholinesterase activity. Exacerbation of OPIDN was most notable in chickens under highest stress, as indicated by elevated heterophil-to-lymphocyte ratios. The clinical, pathological, biochemical, and hematological indices of exposure to adrenocorticoids and agents inducing OPIDN in chickens were, therefore, similar for both a synthetic glucocorticoid and the endogenous steroid corticosterone.

Animals↗

PubMed1988

Environment-genetic influences on immunocompetence.

The immunological responses of an animal are changing continually in response to perceived environmental changes. This is because the genetic background, the lifelong environment of animals and their interaction greatly influence immunological responsiveness. An animal's genetic background influences all factors related to immunocompetence. Among these are age of onset of immunocompetence, responsiveness to specific antigens, antibody titers, type of antibody and immune response, as well as the persistence of the responses. Defense by immunity must require considerable resources, because chickens with a high antibody response are smaller and have poorer feed efficiencies than those chickens whose antibody response is lower. An increase in the effectiveness of one defensive factor may result in reduced effectiveness of another factor. For example, chickens selected for a high antibody titer response to antigen have reduced effectiveness of macrophages. Environmental stresses influence the immune response. Stress at the time of the animal's contact with antigen results in a reduced antibody response. After the antibody response begins, stress has little effect. Stress promotes the sensitization of cell-mediated immunity but inhibits its effectiveness. A short-term stressor such as weaning is followed, in about 24 h, by a short period of reduced immunocompetence, even though lymphoid mass may be reduced. Reduced immunocompetence during stressful periods can be reduced by employing adrenal blocking chemicals, or by socializing animals to their handlers.

Animals↗

PubMed1987

Response of early and late feathering broilers to various stressors.

Growth and responses to potential stressors were measured in early (k+) and late (K) feathering chicks from a common commercial broiler parent stock. Body weights were not different at 3, 10, or 49 days of age with ad libitum feeding, but K/K cockerels were heavier than k+/k+ ones at 24, 38, and 52 days of age with alternate day feeding. No differences in heterophil:lymphocyte ratios were found between K/K and k+/k+ individuals whether they were moved to a new environment or remained in familiar surroundings. Antibody response to sheep erythrocyte antigens was not different in K/w and k+/w pullets. Typical husbandry procedures that might be considered as mild stressors did not elicit physiological stress responses in these meat-type chickens.

Alleles↗

PubMed1987

Effects of fasting, water deprivation, and adrenal-blocking chemicals on resistance to Escherichia coli challenge.

Fasting for 2 days plus 1 day of feeding resulted in increased resistance to Escherichia coli challenge. If feed during the postfasting period contained metyrapone (a blocker of adrenal synthesis of corticosterone), resistance to E. coli challenge was reduced. Fasting for 1.75 days or water deprivation for 2 days resulted in decreased resistance to E. coli challenge. Deprivation of water for two days of chickens with blocked adrenals resulted in an E. coli challenge response similar to that of controls.

Adrenal Glands↗

PubMed1987

Prior experience and response of chickens to a streptococcal infection.

Streptococcus fecalis infection was diagnosed in a population of individually caged meat-type pullets. A retrospective analysis showed that the infection occurred in pullets fed ad libitum and not in those whose feed intake was restricted. Among the former, resistance as measured by changes in body weight and blood heterophils and lymphocytes was greater for those from which blood samples had been obtained than from those which had not been bled. These data are consistent with the hypothesis that handling and feeding programs can modify an individual's resistance to infectious agents. Moreover, these experiences do not have to be extreme; rather they may be consistent with routine production practices such as restricted feed intake and removal of blood for serological testing.

Animals↗

PubMed1986

Dose-related beneficial and adverse effects of dietary corticosterone on organophosphorus-induced delayed neuropathy in chickens.

Tri-ortho-tolyl phosphate (TOTP), 360 mg/kg, po, and 0,0'-diisopropyl phosphorofluoridate (DFP), 1 mg/kg sc, were administered to adult White Leghorn chickens 24 hr after they were placed on diets containing 0 to 300 ppm corticosterone. Supplemented diets were continued until clinical signs and lesions of delayed neuropathy appeared. Although low concentrations (less than or equal to 50 ppm) of corticosterone had beneficial effects on TOTP-induced neuropathy, greater than or equal to 200 ppm exacerbated clinical signs in chickens given either TOTP or DFP. Neurotoxic esterase activities 24 hr after TOTP or DFP were less than 20% of values measured in chickens not given organophosphorous compounds. Chickens given 200 ppm corticosterone without TOTP or DFP had significantly elevated activity of plasma cholinesterase and significantly inhibited activity of liver carboxylesterase. Degenerating myelinated fibers were also evident in distal levels of the peripheral nerves of chickens given TOTP or DFP.

Administration, Oral↗

PubMed1986

Effect of supplemental corticosterone and social stress on organophosphorus-induced delayed neuropathy in chickens.

Adult White Leghorn roosters maintained for 3 months in an environment of low social stress (LSS) were given triorthotolyl phosphate (TOTP), 180 mg/kg po, 24 h after initial exposure to either an environment of high social stress (HSS) or exogenously administered corticosterone (200 ppm in diet). The environment of HSS or the administration of corticosterone were continued for 10 days after TOTP administration. It was noted that the heterophil/lymphocyte ratio, a hematological indicator of stress, was similar in both groups and both had similar scores for clinical signs of delayed neuropathy. Both heterophil/lymphocyte ratios and clinical scores were significantly lower in chickens kept in the LSS environment and not fed corticosterone than in chickens kept in the HSS environment or fed corticosterone.

Administration, Oral↗

PubMed1986

Neurotoxicity of triorthotolyl phosphate in chickens of different genotypes in the presence and absence of deoxycorticosterone.

Indices of acute and delayed toxicity following administration of triorthotolyl phosphate (TOTP) were measured in roosters from lines of chickens originating from the Cornell randombred population. Matings were designed to produce individuals that had presence or absence of allele 21 of the B blood system. Non-B21 individuals had allele 13 or 31. Acute inhibition of esterases (neurotoxic esterase, liver cholinesterase, plasma cholinesterases, and plasma carboxylesterases) occurred in all birds within 24 hr of a single oral dose of 360 mg/kg TOTP. Clinical signs of delayed neuropathy were evident within 12 days of TOTP administration, with no significant difference between genotypes. Dietary deoxycorticosterone (40 to 200 ppm) appeared incapable of statistically significant modification of the strong effects of TOTP. Activities of blood esterases were different between roosters having B21/B21 and those with B13 and/or B31.

Acetylcholinesterase↗

PubMed1986

Effects of dose of antigen and social environment on antibody response of high and low antibody response chickens.

Chickens selected for high (HA) and low (LA) antibody response were exposed to 10-fold doses of red blood cell and killed bacterial antigens while in three different social environments. Antibody responses of the HA and LA line chickens differed most in the socialized environment and at lower doses of antigen. Dose effects were most pronounced in LA-line chickens whereas relationship of humans to chickens was most important to HA-line chickens. Socialized chickens were more consistent than ignored chickens in their response to successive antigens. Correlation between antibody response to red blood cell antigen and Mycoplasma gallisepticum lesions was stronger among socialized chickens than among ignored chickens.

Animals↗

PubMed1986

Resistance to natural and controlled exposures to Eimeria tenella: genetic variation and alloantigen systems.

Chickens from lines selected for high (HA) and low (LA) antibody response to sheep erythrocyte antigens were used to study relationships between blood group systems and resistance to Eimeria tenella. Results of natural and controlled exposures to E. tenella showed Line HA chickens to be more resistant than those from Line LA. Differences in resistance to E. tenella were found among alleles for the I blood group system with degree of resistance depending on the background genome.

Animals↗

PubMed1985

Aflatoxin effects in white Leghorn chickens selected for response to sheep erythrocyte antigen. 2. Serological and organ characteristics.

Aflatoxin was fed to chickens from lines selected for high and low antibody response to sheep erythrocyte (SRBC) antigen and reciprocal crosses between the two lines. Differences were found among populations for liver, bursa, and thymus weight and antibody production to SRBC but not for spleen weight or heterophil: lymphocyte ratios. Dietary aflatoxin depressed absolute and relative weights of bursae and thymi and absolute weights of livers and spleens. Relative to body weight, however, liver and spleen weights increased. There was a large decrease in liver metabolism and a dramatic increase in heterophil: lymphocyte ratios when 5700 ppb of aflatoxin was fed, but no alteration in antibody production to SRBC antigen was detected. Population by response to aflatoxin interactions were not significant for any of the traits measured except bursa and spleen weights, suggesting a general response to this mycotoxin among lines of chickens known to be immunologically different.

Aflatoxins↗

PubMed1985

Selective breeding of chickens for corticosterone response to social stress.

Selection for either a high or low corticosterone response to social stress produced lines that differ for this trait. Comparisons between the selected lines and various crosses showed additive and nonadditive genetic variation but no maternal effects for response to social stressors as measured by heterophil/lymphocyte ratios. When the lines selected for divergent responses to social stressors were exposed to nonsocial stressors, they responded similarly.

Animals↗

PubMed1985

Aflatoxin-antioxidant effects on growth of young chicks.

Butylated hydroxytoluene (BHT), an antioxidant, was provided to chicks at 8 X, 30 X and 80 X the normal concentrations in their feed beginning at 1 day of age and continuing for the next 6 weeks. The ability of these birds to resist the adverse effects of dietary aflatoxin (3000 ppb, beginning Day 8) was measured by weight gain and feed efficiency over the 6-week period of study. Birds on aflatoxin-contaminated feed did not gain weight as rapidly or as efficiently as birds on uncontaminated feed. Depression of growth caused by aflatoxin was significantly less in birds given BHT than in those fed the diet not containing antioxidant.

Aflatoxins↗