Biomedical subjects

K W Washburn

Publications and source records attributed to K W Washburn.

At least 19 recordsLinked to original sources

PubMed1991

Plasma and yolk cholesterol levels in Japanese quail divergently selected for plasma cholesterol response to adrenocorticotropin.

Studies were conducted to determine the effect of divergent selection for plasma cholesterol response to adrenocorticotropin (ACTH) on the levels and relationships between plasma and yolk cholesterol in Japanese quail. Cholesterol data were obtained in Generation 25, following seven generations of relaxed selection, from birds maintained under a normal environment with no exposure to exogenous ACTH. Levels of plasma and yolk cholesterol were determined at 22 and 28 wk. Plasma cholesterol levels of quail in the low cholesterol line were significantly (P less than .01) lower than levels in the high line at both ages (224 versus 383 and 209 versus 326 mg/100 mL, respectively). In contrast, yolk cholesterol levels were significantly (P less than .01) higher in the low line than in the high line (24.1 versus 21.5 and 21.1 versus 16.9 mg cholesterol/g yolk at 22 and 28 wk, respectively). A significant line by sex interaction was present at both ages for plasma cholesterol with females having higher cholesterol values than males in the low line and males having higher values than females in the high line. A negative relationship was observed between changes in plasma and yolk cholesterol in the selected lines. Greater deposition of cholesterol in the yolk of the line with lower plasma cholesterol indicates that excretion rate may play a role in explaining genetic differences in plasma cholesterol.

Adrenocorticotropic Hormone↗

PubMed1991

Efficiency of feed utilization and rate of feed passage through the digestive system.

The relationship of efficiency of feed utilization determined by the feed conversion ratio (FCR) to the rate of feed passage through the digestive system of juvenile chickens was studied and three different methods of measuring feed passage rate (FPR) were evaluated. The FPR did not differ between sexes that had different FCR, nor did it differ between commercial broiler strains that differed in FCR. Feed restriction did not affect FPR. There was little correlation between FCR and FPR in any of the groups evaluated and the FPR was similar for high- and low-FCR groups. There was some evidence for increased FPR in birds grown at 32.2 C compared with those grown at 26.7 C. Similar results were obtained for FPR whether the tracer dye was given in the feed, or in a gelatin capsule, or no tracer dye was used. Repeatability of FPR obtained on the same individuals at different ages was very low.

Animal Feed↗

PubMed1991

Body, abdominal fat, and testes weights, and line by sex interactions in Japanese quail divergently selected for plasma cholesterol response to adrenocorticotropin.

Line by sex interactions of BW, abdominal fat, testes weight, and plasma cholesterol were investigated in two Japanese quail lines. High (H-PCHOL) and low (L-PCHOL) quail lines had been developed by 18 generations of divergent selection for plasma cholesterol response to adrenocorticotropin (ACTH). Quail were from Generation 28 breeders maintained under a normal environment with no exposure to exogenous ACTH after Generation 18. Quail from growth-selected lines were also used to examine relationships between BW and plasma cholesterol. Body weights of H-PCHOL quail were significantly (P less than or equal to .05) heavier than BW of L-PCHOL quail at 2 and 4 wk of age. However, at 8, 16, and 28 wk BW were similar. Quail from long-term, growth-selected lines were observed to have plasma cholesterol levels similar to those of control lines. Therefore, early BW changes in H-PCHOL and L-PCHOL lines may not be related to plasma cholesterol changes. At 2 and 4 wk, male and female plasma cholesterol values were similar in the H-PCHOL and L-PCHOL lines, however, at 8 and 16 wk males had higher values than females in the H-PCHOL line, and females had higher values than males in the L-PCHOL line. Because interactions were present only after sexual maturity was reached, sex hormones may be involved in the expression of these interactions. Quail in the L-PCHOL line were observed to have significantly (P less than or equal to .05) more abdominal fat and significantly (P less than or equal to .05) smaller testes than quail in the H-PCHOL line.

Abdomen↗

PubMed1990

Variation in the three-week body temperature of broilers and Athens-Canadian randombred chickens.

The body temperatures of commercial broilers and an Athens-Canadian randombred population (ACRB), correlations of body temperature with BW, and a sire family heritability (h2) estimate in the ACRB population were obtained. The body temperature of the broilers was significantly lower than that of the ACRB chicks (41.44 versus 41.77 C). Correlations between BW and body temperature were very low for both the broiler and ACRB chicks (.04 and .06). A sire-component h2 estimate of .19 was calculated for 3-wk body temperature in the ACRB population.

Analysis of Variance↗

PubMed1988

Genetic variation of plasma growth hormone and its genetic association with growth traits in young chickens.

A pedigreed, randomly mated population of 25 sire families was assessed for genetic variation in body weight, gain, and plasma growth hormone (GH) under conditions of reduced temperature brooding (26.7 C) from day of hatch to 7 days of age. Heritability estimates (h2) for 7-day body weight and gain were moderate to high. The calculated h2 for GH was moderate. Plasma levels of GH were not phenotypically or genotypically correlated with body weight or gain.

Animals↗

PubMed1987

Use of a fat probe to assess variation in abdominal fat in broilers.

Four trials were conducted to compare the fat probe measure of abdominal fat with that of actual abdominal fat weights and percentage abdominal fat. Various ages, diets, and genetic groups were used to provide experimental chickens with a wide range in body weights and abdominal fat percentages. Mean values obtained by two operators using the probe on the same bird were similar (correlations of .70 to .79). Considering all comparisons, the arithmetic mean of the correlations between fat probe values and percentage abdominal fat was .24; values ranged from .01 to .44. In five comparisons of groups differing significantly in percentage abdominal fat, there were no significant differences in probe values, and correlations between fat and probe values were low. In three other comparisons of groups differing significantly in percentage abdominal fat, differences between probe values were significant and correlations between fat and probe values were moderate. In the comparison groups in which there was an association between probe and fat values, the magnitude of the differences in fat values was about four times as great as that of differences in probe values and the correlations were moderate (.28 to .44). In the comparisons in which higher abdominal fat. In comparisons where higher probe values were not associated with higher abdominal fat, higher body weights were not associated with higher percentage fat.

Adipose Tissue↗

PubMed1986

Genetic variation of neonatal stress response to reduced temperature brooding in a randombred population of chickens.

Chicks from a randombred population were assessed for genetic variation in 1-day body weight and serum corticosterone under two brooding temperatures (26.7 and 32.2 C). Brooding at 26.7 C resulted in lower 1-day body weights and higher corticosterone levels. Heritability estimates (h2) for 1-day body weight were moderately high in both temperature groups but were low for gain in both temperatures. The h2 for corticosterone level from chicks brooded at 26.7 C was moderate, whereas estimates for those brooded at 32.2 were very low. Statistically significant (but low) negative phenotypic correlations were obtained for corticosterone with body weight and gain in both temperature groups. A significant negative genotypic correlation was observed between corticosterone and body weight for chicks brooded at 26.7 C but not for those brooded at 32.2 C. Corticosterone data from the highest and lowest responding sire families revealed a significant response group by temperature interaction. Chicks from the first of two additional hatches showed significant response group differences in serum corticosterone to the reduced brooding temperature. The neonatal serum corticosterone response to cold stress has a genetic basis; however, because there was a negative genotypic correlation between serum corticosterone and body weight, selection for increased corticosterone levels under reduced temperature brooding would likely result in decreased body size.

Animals↗

PubMed1985

Thyroid and adrenal response to heat stress in chickens and quail differing in heat tolerance.

Three experiments were conducted to evaluate the thyroid and adrenal response in groups of birds with altered heat tolerance. Groups of chickens that had been handled on each of 4 days and a nonhandled control group were bled on the 5th day with or without heating for 1 hr at 50 C. Handling did not affect the thyroid response as indicated by thyroxine (T4) or triiodothyronine (T3) levels. Corticosterone levels were lower in handled birds than nonhandled birds after heating. In a second experiment, groups of broilers were fed a diet containing .2% thiouracil or a control diet. After 2 weeks they were bled either with or without 1 hr of heating at 50 C. The T3 and T4 levels were reduced by thiouracil feeding both with and without heating, but adrenal function was not affected. In Experiment 3, T3 and T4 levels were compared for four lines of Japanese quail. The nongrowth-selected line had higher T3 and T4 levels than growth-selected lines but did not have elevated levels of T3 or T4 in response to heat stress. The growth-selected lines (T, S, and P) responded to heating with increased T3 and T4 levels. Levels of T4 in Line T (selected on a thiouracil diet) after heating were significantly higher than all other lines.

Adrenal Cortex↗

PubMed1985

Parabiosis between avian embryos resistant and susceptible to Rous sarcoma virus.

Parabiosis of chicken embryos was used to determine if resistance or susceptibility to Rous sarcoma virus (RSV) tumors could be transferred between RSV-resistant (R) and RSV-susceptible (S) embryos. Eggs from RSV-R and RSV-S lines were parabiosed at 12 days of incubation. One week after hatching the chicks were inoculated in the wing web with RSV. Birds were examined for tumor lesions through 9 weeks of age. Lesion scores of the nonparabiosed RSV-S line were significantly higher than nonparabiosed RSV-R lines. Lesion scores of RSV-R chicks that had been parabiosed to RSV-S chicks were higher than nonparabiosed RSV-R chicks. Lesion scores of RSV-S chicks parabiosed to RSV-R chicks were not different from nonparabiosed RSV-S chicks. These results suggest that the resistance to RSV was not transferred between parabionts but that there was significant transfer of susceptibility from the RSV-S embryos to the RSV-R embryos.

Animals↗

PubMed1985

Evaluation of growth, hormonal, and hematological responses of neonatal chickens to reduced temperature brooding.

A series of experiments was conducted to examine the response of neonatal, male broiler chicks to brooding at a reduced temperature. In Trials 1 and 2, chicks brooded at 26.7 C generally had lower body weights and higher serum corticosterone levels during the first week after hatch than those brooded at 32.2 C. However, significant differences in body weight were observed only on Day 6 in Trial 1 and on Days 1 and 5 in Trial 2. Serum corticosterone levels, likewise, were not significantly different on all days in Trials 1 and 2. These hormone levels were statistically different on Days 1 and 5 in Trial 1 and on Days 1 and 3 in Trial 2. Brooding neonates at 26.7 C for 3 days in Trials 3 and 4 resulted in consistently lower body weights and gain and higher serum corticosterone, thyroxine, total protein, albumin, and globulin. Serum growth hormone levels in chicks brooded at 26.7 C were initially depressed the first day but were elevated on the 2 subsequent days, compared with chicks brooded at 32.2 C. Considering the physiological importance of corticosterone and thyroxine in the adaptation of chickens to cold environmental temperatures, it would be useful to evaluate the genetic variation associated with the responsiveness of these hormones in a randombred population and to improve tolerance of neonatal chickens to reduced temperature brooding through selection.

Animals↗

PubMed1985

Genetic variability in growth response of chicks to cold brooding temperature.

Genetic variability in adaptation to brooding at a reduced temperature was examined by comparing 1 to 14-day body weight gains of progeny from 28 sire families of the Athens-Canadian randombred population brooded at 32.2 C and at 26.7 C. The 1 to 7-day gain of the chicks brooded at 26.7 C was significantly depressed, but 7 to 14-day gain was not significantly depressed by brooding at the reduced temperature. Heritability estimates averaged over the two trials were .31, .23, and .35 for the 1 to 7-, 7 to 14-, and 1 to 14-day weight gains of groups brooded at 32.2 C and .55, .59, and .67 for the gain of groups brooded at 26.7 C. The heritability estimates for the difference in weight gain of families brooded at the two temperatures was .78.

Animals↗

PubMed1984

Hormone and lipogenic enzyme response of the heterozygous dw chick to dietary protein level.

The growth and lipogenic responses of broiler progeny from normal (DwDw male, Dw-female) and dwarf (Dwdw male, Dw-* female) dams to high and low dietary protein were studied. Body weight gains for the DwDw compared to Dwdw male progeny were greater from week 1 to 3, but less from week 7 to 8 and were similar for Dw-* and Dw- females. No significant effects of progeny genotype and no diet X genotype interactions were observed for feed conversion, carcass nitrogen or fat, abdominal fat, growth hormone, triiodothyronine (T3) or thyroxine (T4). Hepatic malic enzyme was elevated in DwDw male progeny compared to Dwdw males, regardless of diet, and was greater in Dw- females than in Dw-* only in response to low dietary protein. Citrate cleavage enzyme was greater in Dw-* than in Dw- females. Low protein resulted in elevated lipogenic enzyme activities, which were more pronounced in progeny of normal dams. A positive relationship observed between malic enzyme activity and T3 levels for all progeny not carrying the dw gene suggests that although circulating levels of thyroid hormones did not differ between genotypes, the cellular response to these hormones was affected by the presence of the dw gene.

ATP Citrate (pro-S)-Lyase↗

PubMed1984

Involvement of the thyroid gland in the response of young chickens to heat stress.

The involvement of the thyroid gland in the response of young chickens to heat stress was studied. Mean survival times when exposed to 50 C were significantly shorter for 3-week-old broiler male chickens injected with 40 micrograms L-thyroxine (T4)/100 g body weight compared to chickens injected with 30, 20, or 0 microgram of T4/100 g body weight. A significant reduction in heat stress survival time was obtained when T4 was injected 12, 18, or 24 hr before heat stress but not 6 hr before. Triiodothyronine (T3) reduced heat stress survival time when administered 12 to 24 hr before the stress but not when given 6 hr before. Chickens made hypothyroid by radiothyroidectomy had significantly longer heat stress survival times than controls. Likewise, chickens fed a diet containing .2% thiouracil 10 days before heat stress at 28 days had significantly longer survival times than control birds.

Animals↗

PubMed1984

Genetics of heat tolerance in Japanese quail.

Two experiments were conducted to assess the genetics of heat stress survival time (HSST) and its relationship to body weight (BW) in Japanese quail. In Experiment 1, Japanese quail from the Athens Randombred population were used and estimations of heritability (h2) and genotypic correlation (rg) were based on half-sib relationships. Three lines of Japanese quail selected under different environments and the Athens Randombred line were studied in Experiment 2. Estimations of h2 and rg were based on full-sib relationships. Heritability for HSST was moderate (.28 to .53) in Experiment 1 and low in Experiment 2 (.13 to .24). Phenotypic correlations between HSST and BW ranged from -.33 to -.05, and a negative genotypic correlations between HSST and BW suggested that selection for longer HSST would result in reduced BW.

Animals↗

PubMed1984

Characterization of plasma hormone levels and lipogenic enzyme activity in chickens divergently selected for oxygen consumption.

The bases for differences in growth and metabolism of lines previously selected for divergence in O2 consumption in comparison to a randombred control population were studied. Body weights, carcass fat, plasma growth hormone (GH), triiodothyronine (T3), thyroxine (T4), malic enzyme, and citrate cleavage enzyme activities were determined. The early growth of the low O2 birds was greater than the high O2 birds, whereas the growth rate of the control population was intermediate to, but not statistically different from, the two O2 lines. Six-week body weights did not differ between the lines. Percent fat of the high O2 birds was less than the other two lines at 1 and 2 weeks of age but greater than the low O2 birds at 3 weeks of age. Percent fat did not differ between the lines at 6 weeks. Plasma T4 levels differed between the lines only at Day 1, when the control population exhibited greater T4 levels than the O2 lines. Plasma T3 levels were lower in the high O2 chicks in comparison to only the control chicks at 0, 1, and 2 weeks of age. No line differences in T3 levels were detected at 3 or 6 weeks. From 1 to 3 weeks, GH levels were greater in the low O2 birds than the high O2, while the control birds had GH levels intermediate to the O2 lines. By 6 weeks, the O2 lines had similar GH levels, but these levels were lower than those of the controls. No consistent line differences in malic enzyme or citrate cleavage enzyme activities were observed.

ATP Citrate (pro-S)-Lyase↗

PubMed1984

Preconditioning to heat stress by a nontemperature stressor.

Three experiments were conducted in which 3-week-old chickens were subjected to a handling procedure for 4 days (21 to 24 days of age) and subjected to heat stress on either the 5th or 7th day (25 or 27 days of age). The heat stress episode consisted of exposure to 50 C for up to 240 min in a forced-draft chamber. In two experiments in which broiler chickens were studied, the heat stress survival time, determined at 25 days of age, was increased by the handling procedure. The same phenomenon did not occur in Leghorn chicks or broiler chickens heat stressed after a 3-day adjustment period.

Animals↗

PubMed1984

Effect of the dw gene on growth, plasma hormone concentrations and hepatic enzyme activity in a randombred population of chickens.

The effect of the dw gene on growth, lipid deposition, plasma hormone concentration, and enzyme activity in a randombred population of chickens was studied. The reciprocal crosses were examined as well as purebred dwarf and normal populations. Body weight, carcass fat, plasma growth hormone (GH), triiodothyronine (T3), thyroxine (T4), hepatic malic enzyme (ME) and citrate cleavage enzyme (CCE) activities were determined at 0, 2, 4 and 6 weeks. Body weights of dwarf birds were less than normal birds and, unexpectedly, Dwdw males had greater body weights than DwDw males. Percent carcass fat was greater in dwarf birds in comparison to phenotypically normal birds. All males carrying the dw gene had greater fat pad weights than homozygous normal males. The dw- females from cross 3 had less abdominal fat than cross 4 Dw- females, while dw- females from the dwarf parental mating had fat pad weights similar to Dw- females. Plasma T4 levels were elevated in all birds carrying the dw gene in comparison to normal birds. Plasma T3 levels were depressed in all birds carrying the dw gene versus normals, although the T3 levels of Dwdw males were intermediate to dwdw and DwDw males. The homozygous dwarf progeny exhibited elevated GH levels versus normals and Dwdw males exhibited GH concentrations intermediate to dwdw and DwDw males. Malic enzyme activity was lower in all birds carrying the dw gene, while CCE activity was not effected by genotype.

ATP Citrate (pro-S)-Lyase↗

PubMed1983

Effect of dietary aflatoxin concentration on the assessment of genetic variability of response in a randombred population of chickens.

The effect of graded levels of dietary aflatoxin on the assessment of genetic variability of body weight and gain and plasma protein response was tested utilizing the Athens-Canadian randombred population of chickens. Dietary aflatoxin was administered at levels of either 0, 1.25, 2.50 or 5.0 microg/g of diet ad libitum from 7 to 21 days of age to progeny from 58 sire families. Twenty-one-day body weights, gain and plasma protein concentration were used to assess the variation in response.-The administration of increasing levels of aflatoxin resulted in a dose-related decrease of gains and plasma protein concentrations. Plasma protein concentrations were significantly higher among males than females within the control group; however, this difference was reversed as the severity of the aflatoxin challenge increased. Heritability estimates for all responses increased as the level of aflatoxin administered increased. This change was most notable for total plasma protein concentration. Phenotypic correlations for plasma protein concentration and growth measurements tended to diminish with increasing levels of aflatoxin. A similar trend was noted for the genetic correlations; however, a moderate correlation between growth responses and plasma protein response was detected in the 5.0-microg/g aflatoxin treatment group. Genetic correlations were calculated for the same characters between the different levels of aflatoxin. Regardless of which aflatoxin challenges were compared, a very high genetic correlation for 21-day body weight and 7- to 21-day gain was estimated. This variation in growth potential in the toxic environment paralleled that observed in the control environment but at a lower plane. Genetic correlations for plasma protein response across aflatoxin levels diminished as the difference between the levels of aflatoxin administered increased. Plasma protein concentration in the control environment was positively correlated with plasma protein response in groups fed a low level of aflatoxin, but negatively correlated when an aflatoxin challenge of 2.5 microg/g or more was given, suggesting that selection for aflatoxin resistance using plasma protein response as a selection criterion should be made under an aflatoxin stress environment.

Aflatoxins↗