Biomedical subjects

W B Gross

Publications and source records attributed to W B Gross.

At least 19 recordsLinked to original sources

PubMed1992

Restricted feeding and broiler performance: age at initiation and length of restriction.

Broiler cockerels were provided either ad libitum access or restricted to alternate-day access to feed initiated at different ages and lasting for different durations. Regimens consisted of ad libitum feeding; alternate-day feeding; alternate-day feeding from 0 to 6, 6 to 12, or 12 to 18 days of age (DOA); alternate-day feeding from 0 to 12, 0 to 6, and 12 to 18, or 6 to 18 DOA; and alternate-day feeding from 0 to 18 DOA. By 39 DOA, chicks restricted for only one 6-day period reached body weights equivalent to those of chicks eating ad libitum. Body weights of chicks restricted for more than 6 days during the first 18 days after hatch were lower than those of chicks eating ad libitum at 39 DOA. Restriction for more than 6 days improved feed efficiency. Chicks restricted for the whole experiment had superior feed efficiency but low body weights. Antibody responses to sheep erythrocyte antigen were similar among feeding regimens. Response to Escherichia coli inoculation was generally less severe in chicks provided restricted access to feed, and overall mortality was highest in chicks eating ad libitum. Feeding regimens had little effect on organ weights relative to body weight, amount of abdominal fat (either on an absolute basis or relative to body weight), or percentage lipid in the abdominal fat pad.

Abdomen↗

PubMed1992

Antibody responses to combinations of antigens in white Leghorn chickens of different background genomes and major histocompatibility complex genotypes.

Antibody responses in chickens to SRBC, Newcastle disease (NDV), and Brucella abortus (BA) were compared when given singly or in combination. Chickens used in the present experiment originated from a cross and then backcrossing of White Leghorn populations that had been selected for high (HA) or low (LA) antibody response to SRBC antigens. The populations used in the current study were segregating for MHC haplotypes B13 and B21. The experiment had a 2 x 3 x 6 factorial arrangement of treatments (two background genomes: HA and LA; three MHC haplotypes: B13B13, B13B21, and B21B21; and six antigen treatments: SRBC, NDV, or BA only, SRBC plus NDV, SRBC plus BA, and NDV plus BA). Antigens were administered either i.v. (SRBC) or i.m. (NDV and BA) when chicks were 42 days of age. Blood was obtained 27 days later (69 days of age) for antibody determinations. A significant background genome by MHC haplotype interaction for BA antibodies was due to relatively high titers in Line HA chickens of MHC genotypes B13B13 and B13B21. Background genome by MHC genotype interactions were not significant for SRBC or NDV antibodies. Antibody titers to SRBC were higher in background genome HA than LA, and similar among MHC genotypes. Antibodies to NDV were lower in chickens of MHC genotype B21B21, but there were no differences due to background genome. For each of the three antigens, antibody responses were highest when administered singly rather than in combination. Antibody titers were lower for SRBC when given with BA, and for BA titers when given with NDV.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1992

Role of socialization, stress and sex of chickens on response to anesthesia and on response to an organophosphate neurotoxicant.

The influence of socialization of chickens on response to exogenous substances in the presence and absence of stress was examined. Chickens of both sexes were habituated to human beings (socialized) by being talked to and offered food from the hand of the caretaker. After 19 w, half the socialized group and half the unsocialized group were subjected to stress (loud noises for 120 sec twice daily) for 2 w. At the end of this period, response to 37 mg pentobarbital/kg iv was evaluated by length of sleeping time. Males slept longer than females, and males that were socialized but not stressed slept significantly longer than other males. Stress and socialization did not significantly affect pentobarbital sleeping time in females. This indicated that response to pentobarbital was dependent on sex and on socialization, with the most notable effects occurring in socialized males. Socialized and nonsocialized, stressed and unstressed male and female chickens were also administered a single po dose of 360 mg tri-ortho-tolyl phosphate (TOTP)/kg. This organophosphorus ester induced a delayed neuropathy that caused ataxia in all the chickens. The ataxia was significantly more pronounced earlier in males than in females, although the sex difference became insignificant 18 d after dosing. Socialized chickens were ultimately more affected. Noise stress did not affect TOTP-induced ataxia. This indicated that response to an organophosphate neurotoxicant was also dependent on sex and socialization, with the most notable effects again seen in socialized males. Response to endogenous substances in chickens depends both on sex and on familiarity to humans.

Anesthesia↗

PubMed1992

Effect of short-term exposure of chickens to corticosterone on resistance to challenge exposure with Escherichia coli and antibody response to sheep erythrocytes.

Chickens in a low-stress environment (heterophil/lymphocyte ratio 0.31) were given feed containing 30, 40, or 60 mg of corticosterone/kg of feed for 0.5 hour. Between 0.5 to 12 hours later, chickens were exposed to Escherichia coli via the air sac route. For each dose of corticosterone, there was an untreated control group that was exposed to E coli via the air sac route. The prevalence of pericarditis was reduced from 78 to 7% between 2 and 4 hours after exposure. Resistance was associated with heterophil/lymphocyte (H/L) ratios greater than 1.04. Peak H/L ratios correlated positively with amount of corticosterone in the feed. In one experiment, chickens were inoculated IV with sheep erythrocytes at various times after consumption of feed containing corticosterone. Suppression of antibody responsiveness was most pronounced 4 hours later. Antibody responsiveness correlated positively with lymphocyte numbers. Histologic examination of air sacs was made following euthanasia at various times after E coli exposure. Lesions observed in control chickens included: edema at 0.5 hour, beginning of heterophil infiltration at 1 hour, increased edema and heterophil infiltration at 2 hours, and severe edema and heterophil infiltration at 4 hours. Lesions were not observed in chickens that had been given feed containing 40 mg of corticosterone/kg of feed.

Administration, Oral↗

PubMed1991

Performance of early and late feathering broiler breeder females with different feeding regimens.

1. Growth, reproductive characteristics and immunocompetence were evaluated in a line of broiler breeder females segregating at the sex-linked feathering locus when maintained on three feeding regimens with two forms of food in a factorial design. 2. Long-term obesity but not short-term weight gain had deleterious consequences for reproductive characteristics, response to sheep red blood cell antigen, resistance to Escherichia coli and livability. 3. Reproductive performance of early feathering females was superior to that of late feathering ones. Differences were attributed to an association between the allele for late feathering and an endogenous viral locus ev21, which encodes for avian leucosis virus. 4. Reproductive performance of breeders fed crumbles was superior to that of breeders fed a combination of crumbles and fines.

Animal Feed↗

PubMed1991

Genotype, feeding regimen, and diet interactions in meat chickens. 3. General fitness.

Several fitness traits were measured in males from two meat lines fed diets differing in nutrient density ad libitum daily or on alternate days. Criteria of evaluation were antibody response to SRBC, blood heterophil:lymphocyte ratios, incidence of leg deformities, and resistance to Escherichia coli inoculation. Males from the heavier line had lower antibody titers to SRBC inoculation than those of the lighter line. Diets, feeding regimens, and interactions among them did not influence response to SRBC. Lines, diets, feeding regimens, and interactions among them were not significant for heterophil:lymphocyte ratios. Chicks fed daily had a higher incidence of leg deformities than those fed on alternate days. There were no differences between lines or diets, nor were interactions significant. Interactions were present between main variables for response to E. coli inoculation whether the measure was initial weight loss, recovery, or lesion scores, demonstrating the complexity of genotype-environmental relationships in resistance to this infectious agent.

Animals↗

PubMed1991

Use of corticosterone and ampicillin for treatment of Streptococcus faecalis infection in chickens.

Chickens were selectively bred for either high-antibody (HA) or low-antibody (LA) response to sheep erythrocytes. From 6 to 31 days after Streptococcus faecalis challenge exposure, LA-line chickens maintained a greater percentage of the prechallenge-exposure body weight and had lower heterophil-to-lymphocyte ratio than did HA-line chickens. The optimal dose of corticosterone (30 mg/kg of feed) was effective in maintaining postchallenge-exposure body weight greater than that of controls. Ampicillin (20 mg/d) alone was ineffective in almost all experiments. Treatment with 30 mg of corticosterone/kg of feed plus ampicillin resulted in increased body weight response to S faecalis infection when treatment was initiated 1 day before or 2 days after challenge exposure. Treatment with corticosterone was more effective in HA- than in LA-line chickens. Treatment before challenge exposure was more effective than treatment 2 days after challenge exposure.

Ampicillin↗

PubMed1990

Production traits and alloantigen systems in lines of chickens selected for high or low antibody responses to sheep erythrocytes.

The selection of chickens for high (HA) and for low (LA) antibody titers to sheep erythrocytes has produced differences in the selected trait and in the correlated responses in body weight, egg production, and erythrocyte antigens. The response to selection continued through 14 generations. There was considerable divergence between lines for erythrocyte alloantigen systems, including the major histocompatibility complex. Females from Line LA were heavier as juveniles and lighter as adults, matured at a younger age, and had higher egg production than those from Line HA. There were no differences between lines for the incidence of defective eggs laid-except for the percentage of eggs with double-yolks, which was greater for Line LA than HA. The phenotypic correlations of antibody response with growth and with reproductive traits were very low; the genetic correlations were moderate to high for most of these traits.

Alleles↗

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↗