Biomedical subjects

W B Gross

Publications and source records attributed to W B Gross.

At least 19 recordsLinked to original sources

PubMed2006

Poult performance as influenced by age of dam, genetic line, and dietary vitamin E.

An experiment was conducted to measure the effects of age of dam, genetic line, and dietary levels of vitamin E on growth and immunocompetence of poults. Age of dam was defined as younger (in early egg production) and older (past peak production); line consisted of a commercial sire and dam line; and dietary vitamin E was supplemented into the diet at 10 and 300 IU/kg of feed. Traits measured included body, liver, gizzard, and yolk sac weights at hatch; BW and feed conversion to 9, 28, and 42 d; response to SRBC, Phaseolus vulgaris agglutinin-P, and Escherichia coli administered at 28 d of age; and response to a cold stress on d 5 posthatch. Differences among genetic lines were evident with growth greater for poults from the sire than from the dam line. Performance of poults from older dams was generally superior to that of poults from younger dams. The higher level of vitamin E resulted in a greater than 7-fold increase in blood plasma vitamin E and reduced mortality. There were interactions among the main effects in which the fitness of poults from younger dams was enhanced by the higher level of vitamin E and the effect of breeder age differed among genetic lines.

Age Factors↗

PubMed2004

Effect of different cell fractions of Mycobacterium avium and vaccination regimens on Mycobacterium avium infection.

Because of the availability of uniform genetic stocks and the ability to modulate stress levels, chickens were investigated as a host for the development of an antimycobacterial vaccine. The imposition and the timing of stress significantly influenced the outcome of Mycobacterium avium infection in chickens. Simple, whole cell or lysate vaccines and combinations of vaccine preparations were identified that led to high levels of protection. In addition, short-term stress at the time of vaccination significantly increased the protective efficacy of M. avium vaccine preparations. Post-infection vaccination of M. avium-infected chickens was also shown to significantly reduce the number of lesions and colony counts.

Animals↗

PubMed1997

The effect of stress on the response of chickens to coccidiosis vaccination.

Six-week-old Leghorn chickens, which had been adapted to both their environment and cage mates, were orally inoculated with 400 Eimeria tenella oocysts as a means of low-dose vaccination. At 2, 3, 4, 5 or 6 days after vaccine administration, the birds were subject to 24 h of social stress through a prescribed method of random redistribution. Two weeks after vaccine administration, the birds were challenged by oral inoculation with 8000 oocysts. Caecal lesion scores were determined 6 days after challenge. Vaccinated chickens were more resistant to lesion formation than unvaccinated controls, and protection, as determined by lower lesion scores, was significantly enhanced when stress in the form of social disruption was applied on the fourth day following vaccine administration.

Animals↗

PubMed1997

Effect of dietary selenium on the response of stressed and unstressed chickens to Escherichia coli challenge and antigen.

Selenium was added to the feed of White Leghorn type chickens 1 day prior to challenge with either Escherichia coli or sheep erythrocyte antigen. The incidence of death or lesions was reduced from 86% to 21% at the optimal dose of selenium (0.4 mg/kg resulting in feed concentration of 0.45 mg/kg). After the chickens were stressed by chilling, selenium was ineffective against E. coli. Dietary additions of selenium between 0.1 and 0.8 mg/kg resulted in an antibody titer increase from 2.2 to 3.9 to the log2 against sheep erythrocytes (SRBC). Following chilling, antibody titer response was reduced from 4.9 to 2.4 to the log2. This titer reduction could be prevented with dietary additions of selenium between 0.1 and 1.2 mg/kg. The effects of a nitrofuran and selenium were additive against E. coli challenge infection.

Animals↗

PubMed1997

Dietary effects on immune response of fast-growing chicks to inoculation of sheep erythrocytes and Escherichia coli.

Responses to SRBC and Escherichia coli inoculations were measured during the early posthatch period in broiler cockerels fed diets differing in nutrient density. Diet A consisted of 20% protein and 2,685 kcal ME/kg and Diet B consisted of 24% protein and 3,146 kcal ME/kg. There was no effect of diet on antibody response of chicks inoculated at 10 d of age with 0.25, 2.50, 5.00, or 25.00% suspensions of SRBC. A significantly larger proportion of chicks, however, produced antibody at the 25.00% than at the 0.25% dosage of SRBC. When inoculated at 15 d of age with 10(-6), 10(-4), or 10(-2) dosage of E. coli, there were no significant diet by dosage interactions for lesion scores, or relative change in BW 24, 48, and 120 h after inoculation. There were differences among E. coli dosages for severity of lesions and mortality, with rankings being 10(-2) > 10(-4) > 10(-6). Lesion scores and mortality were higher for the chicks fed Diet B than those fed Diet A. Also, deleterious effects of E. coli on BW 24, 48, and 120 h after inoculation were greater for chicks fed Diet B than for chicks fed Diet A. Responses to inoculations of SRBC and E. coli of broilers fed a diet with a lower nutrient density were equal or superior to those of broilers fed a diet with a higher nutrient density.

Animal Feed↗

PubMed1996

Immunoresponsiveness of fast-growing chickens as influenced by feeding regimen.

1. Immunoresponsiveness and disease resistance were measured in broiler males maintained on ad libitum feeding throughout or on alternate-day feeding. Alternate-day restrictions were started 1 and 2 d after hatch so that on any one day there were chicks fed and fasted. 2. Severity of response to E. coli challenge as measured by lesion scores, and mortality was greater for chicks fed ad libitum than those fed on alternate days. For chicks fed on alternate days, lesion scores were lower for those without access to feed for the 24-h period immediately after challenge. 3. Spleen weights, the indicator of response to marble spleen disease virus challenge, were higher for chicks fed ad libitum than those fed on alternate days. 4. Antibody response to sheep red blood cell antigen was not affected by feeding regimen. 5. Ratios of heterophils to lymphocytes were higher for chicks given access to feed for the previous 24-h period than for those fasted during the previous 24-h or those that had been fed ad libitum. 6. Results of this experiment suggest that for alternate-day feeding programs, vaccination be administered on the day that chicks are not fed.

Animals↗

PubMed1996

Feeding regimen by sire family interactions on growth, immunocompetence, and disease resistance in chickens.

Progeny from matings of 12 sires from a White Plymouth Rock line selected for high juvenile BW and 96 dams from a White Leghorn line selected for low antibody production to SRBC were reared under alternate-day (AD) or ad libitum (AL) feeding regimens. Within a feeding regimen males were heavier than females, and within a sex, chicks fed AL were heavier than those fed AD. Feeding regimen by sire family interactions were significant for BW at 21 d of age for both male and female progeny. The interaction was due to differences among sires in the magnitude of the AD: AL relationship. Product moment correlation coefficients between feeding regimens for male and female progeny of sire families for 21-d BW were essentially zero, which was consistent with the sire family by feeding regimen interactions observed at this age. At 41 d of age, relative to BW, weights of empty esophagus plus crop and of crop contents were greater for AD than AL chicks. There were differences among sire families for crop content and breast weights relative to BW. Lesion scores to Escherichia coli challenge were lower and antibody titers to SRBC antigen were higher in AD than in AL chicks. Sire families differed in antibody titers to SRBC antigen. Feeding regimen by sire family interactions were significant for percentage change in BW 144 h after E. coli challenge and lesion scores were greater for AL than AD chicks.

Aging↗

PubMed1994

Food restriction early or later in life and its effect on adaptability, disease resistance, and immunocompetence of heat-stressed dwarf and nondwarf chickens.

1. Dwarf and nondwarf chickens placed under 60% food restriction from either 4 to 6 (early) or 24 to 26 (late) days of age were exposed to high ambient temperatures (35 +/- 2 degrees C) from 36 to 43 d of age. 2. As measured by heterophil/lymphocyte (H/L) ratios, stress response to food restriction was similar at both ages for dwarfs while less at the younger than the older age for nondwarfs, resulting in a significant food restriction interaction of genotype by age. 3. Nondwarf chickens food restricted at the younger age had smaller increases in H/L ratios, improved resistance to marble spleen disease infection and greater growth than those restricted at the older age or fed ad libitum in response to the high ambient temperatures. 4. For dwarf chickens feeding regimen had no influence on response to the environmental insults. 5. Antibody response to sheep erythrocyte antigen was not affected by genotype or feeding regimen.

Animals↗

PubMed1994

Inhibition of adrenal steroidogenesis, food restriction and acclimation to high ambient temperatures in chickens.

1. White Plymouth Rock chickens placed under 60% food restriction or ad libitum feeding, with or without metyrapone treatment, from either 4 to 6 (early) or 24 to 26 (late) d of age were exposed to high ambient temperatures (35 +/- 2 degrees C) from 36 to 43 d of age. 2. Stress attributable to fasting was not manifested through leucocytic alteration when food-restricted chicks were supplemented with an adrenal blocking chemical, metyrapone. 3. Provision of metyrapone during the fasting period resulted in inferior compensatory growth during refeeding. 4. Exposure to high temperatures from 36 to 43 d of age did not cause an elevation in the heterophil:lymphocyte (H/L) ratios of chicks that had eaten metyrapone-treated food ad libitum during the neonatal stage. 5. During heat exposure, chicks that had been subjected to early 60% restriction with non-metyrapone-treated food had lower H/L ratios and improved resistance to marble spleen disease infection.

Acclimatization↗

PubMed1993

Responses of dwarf and normal chickens to feed restriction, Eimeria tenella infection, and sheep red blood cell antigen.

Relationships among stress responses, habituation to feed restriction, resistance to Eimeria tenella, and antibody response to SRBC were studied in dwarf and normal White Plymouth Rocks. Transfer of chicks at 22 days of age from starter to developer batteries resulted in an increase within 24 h of heterophil:lymphocyte (H:L) ratios of chicks of both genotypes. Restriction of feed intake from ad libitum (AL) to 60% of ad libitum reduced body weight and increased size of the crop-esophagus. As measured by H:L ratios, the effect of adapting to the 60% feed restriction dissipated between 12 and 16 days after initiation. Release of 60% restricted chicks to 80% of ad libitum also elicited a stress response as measured by H:L. These effects were noted in both dwarf and normal chicks. Time required for chicks on restriction to consume their daily allotment was curvilinear with a plateau occurring at a smaller value for dwarf than for normal chicks. Neither feeding regimen nor genotype had an effect on antibody response to SRBC. Resistance to E. tenella was greater in normal than dwarf chicks and greater for restricted than ad libitum chicks.

Age Factors↗

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↗