Biomedical subjects

H L Marks

Publications and source records attributed to H L Marks.

At least 55 records · Page 3Linked to original sources

PubMed1990

Abdominal fat and testes weights in diverse genetic lines of Japanese quail.

Six experiments were conducted to investigate abdominal fat levels in mature male and female Japanese quail following selection for 4-wk body weight and to investigate the relationship between testes development and abdominal fat accumulation. The present study utilized P-, T-, and S-line quail selected for more than 75 generations for high 4-wk body weight and also lines divergently selected (16 or more generations) for high (H-SD, H-CD) and low (L-SD, L-CD) 4-wk body weight. Adult males had from two to four times more abdominal fat than females, the reciprocal of abdominal fat patterns in chickens. These differences were observed regardless of the selection environment, direction of selection, or duration of selection. Percentage of abdominal fat was higher in high body weight lines than in low body weight lines, and correlation coefficients between body weight and abdominal fat were moderate to high (mean = .39). Correlations between abdominal fat and testes weights were positive and largest at 5 wk (r = .62).

Abdomen↗

PubMed1988

Divergent selection for growth in Japanese quail under split and complete nutritional environments. 1. Genetic and correlated responses to selection.

Japanese quail were divergently selected for 4-wk body weight under two different nutritional environments. In one environment quail were divergently selected for high and low body weight (H and L) under a split diet (SD) with quail having the opportunity to self-select feed from high protein and high energy diets. In the other environment, quail were similarly selected (H and L) under a normal (28% protein) complete diet (CD). After 11 generations of selection, H-SD and H-CD lines were 48.9 and 49.7% higher in 4-wk body weight than controls. Quail from L-SD and L-CD lines were 46.5 and 45.4% lower in 4-wk body weight than controls. Realized heritabilities for 4-wk body weight were .36 +/- .03, .30 +/- .03, .52 +/- .02, and .47 +/- .03 for H-SD, L-SD, H-CD, and L-CD lines, respectively. Selection differentials were significantly higher in the SD than in the CD environment. Changes in 2-wk, adult body, and egg weight across generations paralleled that of the trait under selection (4-wk body weight). Selection also resulted in decreased hatchability and egg production with increased age to sexual maturity in both environments. The SD environment was determined to be a stress environment because of birds' inferior growth there compared with growth in the CD environment. Rate of growth, however, to reach adult body size was superior for L-SD quail once the stress environment was removed. There was also evidence that eggs were larger for quail in the SD than the CD environment.

Animals↗

PubMed1988

Divergent selection for growth in Japanese quail under split and complete nutritional environments. 2. Water and feed intake patterns and abdominal fat and carcass lipid characteristics.

A study was conducted to investigate water and feed intake patterns, abdominal fat and carcass lipid levels, feed efficiency and growth in high (H) and low (L) body weight lines of Japanese quail divergently selected under complete diet (CD) or split diet (SD) environments. Birds under the SD environment could self-select from high-protein low-energy or low-protein high-energy diets. Progeny from both the selected and control (C) lines were evaluated under the SD environment in Generations 6 and 10, and under the CD environment in Generation 10. Under the SD environment, body weights of the H lines were similar as were body weights of the L lines; however, under the CD environment, there were significant differences between H lines and between L lines. Body weights were higher under the CD than under the SD environment. Differences between H and L lines in body weights and 1-wk relative growth rates within SD and CD environments were attributed to differences in water and feed consumption and feed efficiency. Water consumption was greater in the SD than CD environments. Feed consumption was greater in the SD than CD environment from 0 to 2 wk of age; thereafter, feed consumption was higher in the CD environment. Abdominal fat and carcass lipid levels were greater in H than L lines, with the magnitude of the difference greater in the SD environment, indicating that the SD may be a better environment than the CD environment for the study of abdominal fat and carcass lipids in Japanese quail.

Adipose Tissue↗

PubMed1988

Adipose cellularity in nonselected and selected broiler stocks: measurements at equal weights and ages.

A population of nonselected broilers (AC) and a stock of commercial broilers (C) differ in growth characteristics. The two stocks of broilers were examined for differences in adipose tissue at equal ages at 28 and 54 days of age and at equal body weights. Body composition and abdominal adipose tissue were measured. Total adipocyte number, adipocyte size distributions, and DNA content of the abdominal fat pad were determined. Partial correlations of abdominal fat, expressed as a percentage of body weight, with mean adipocyte volume and abdominal adipocyte number were calculated. Body weights of C birds were greater than body weights of AC birds at 28 days of age (903 +/- 21 and 355 +/- 12 g; X +/- SE) and at 54 days of age (2,410 +/- 45 and 892 +/- 31 g). Abdominal fat pads were heavier in C birds than in AC birds on an absolute basis (P less than .01) and as a proportion of body weight (P less than .01). The C birds had more and larger adipocytes than AC birds at equal weights (P less than .05) and equal ages (P less than .01). Age did not significantly affect adipocyte size in AC birds, but adipocytes were larger in C birds at 28 days of age (117.3 vs. 78.8 pL, P less than .01) and further increased in size at 54 days (177.3 vs. 79.1 pL, P less than .01) when compared with those in AC birds at the same age.(ABSTRACT TRUNCATED AT 250 WORDS)

Adipose Tissue↗

PubMed1988

Effects of recombinant chicken growth hormone in randombred meat-type chickens.

Recombinant chicken growth hormone (rcGH) was administered subcutaneously twice daily to male and female Athens-Canadian randombred meat-type chickens between 2 and 14 days posthatch. Treatment groups consisted of non-injected controls, saline-injected controls, and those injected with either 50 or 250 micrograms/kg rcGH per injection. Body weight, body weight gain, feed consumption, and feed efficiency were determined. Body weight or body weight gain was not significantly affected by rcGH through 28 d. Feed consumption and efficiency were not significantly affected by treatment through 21 d. It was concluded that rcGH failed to demonstrate any significant growth-promoting effects in young, slow-growing randombred chickens.

Animals↗

PubMed1987

Sexual dimorphism in broilers following periods of equal water and feed intake.

A study involving three experiments was conducted to investigate patterns of feed and water intake following an initial period in which both sexes received the same water or feed allowance. Restriction of water to an equal intake level in males and females from 0 to 10 days resulted in similar feed intake patterns and similar body weights for both sexes. Following exposure to ad libitum water, males immediately consumed 7 to 11% more water than females, while the accompanying change in feed intake was smaller in magnitude (1 to 6%). Restriction of feed to equal intake levels in both sexes from 0 to 12 days resulted in males and females consuming similar amounts of water. Body weights of males were slightly greater than female weights due to differences in feed efficiency. Following placement under ad libitum feed, males consumed more feed than females (8 to 9%). However, the divergence in feed intake following feed restriction between sexes was more gradual than the divergence in water intake following water restriction. These data indicate that feed and water intake patterns of males and females are controlled by inherent mechanisms independent of differences in body weight or maintenance requirements.

Animals↗

PubMed1987

Selection for 8-week body weight in normal and dwarf chickens under different water/feed environments.

Normal and dwarf chickens fed either regular (.4%) or high (1.6%) salt diets were selected for four generations for high 8-wk body weight. Selection gains in body weight were greater in dwarf than in normal genotypes. Selections differentials, gains, and heritabilities were greater in lines selected under the .4% salt environment. When tested females were fed .4% salt diets, normal females from lines selected after being fed 1.6% salt diets had less fat than those from lines selected after being fed .4% salt diets. However, no differences were observed in dwarf females from the two selection environments.

Adipose Tissue↗

PubMed1987

Water and feed intake, feed efficiency, and abdominal fat levels of dwarf and normal chickens selected under different water:feed ratio environments.

Early feed and water intake, feed efficiency, and abdominal fat weights were investigated in normal and dwarf genotypes previously selected for high 8-wk body weight under .4 and 1.6% dietary salt environments. Progeny from the selected lines were evaluated on a normal .4% salt diet in two experiments following Generations 3 and 4. Progeny of lines selected on the .4% salt environment tended to have higher body weights and feed intake than progeny of lines selected on the 1.6% salt environment. There was evidence that progeny from normal birds previously selected on the 1.6% salt environment had higher initial (0 to 6 days) water:feed ratios than progeny of normal birds previously selected on the .4% salt environment, with ratios approximately 20% greater from 0 to 2 days in Generation 4 progeny. Feed efficiencies were similar within genotype across selection environments. However, feed efficiency of dwarfs appeared to be superior to feed efficiency of normals from 0 to 8 days, whereas at later ages, normals were more efficient. Normal females of lines selected in the 1.6% salt environment had from 13 to 29% less abdominal fat percentages than contemporaries from lines selected on the .4% salt environment at 63 to 66 days of age. Abdominal fat weights of dwarfs, however, were not influenced by the selection environment.

Adipose Tissue↗

PubMed1987

Selection for resistance to aflatoxin in chickens.

Two populations of broiler chickens [Athens-Canadian (AC) and a commercial stock] were selected for resistance to aflatoxicosis by dosing chickens in each population with a single oral dose of aflatoxin, which resulted in 40 to 70% mortality. Chickens that did not receive aflatoxin served as the nonselected control groups. Birds surviving the aflatoxin challenge were used as breeders for subsequent generations. Rapid progress was made in the AC population for resistance to aflatoxin, but only moderate progress for this trait was attained in the commercial broiler stock. After five generations of selection in the AC population, LD50 values of 9.42 and 17.05 milligrams aflatoxin per kilogram body weight (BW) were determined for the nonselected and selected lines, respectively. After four generations of selection in the commercial broiler population, LD50 values of 6.05 and 8.02 mg aflatoxin/kg BW were determined for the nonselected and selected lines, respectively. These data demonstrate that genetic progress can be made in chickens, but the amount of progress for resistance to aflatoxin may be influenced by the population.

Animals↗

PubMed1987

Comparison of three nonlinear regression models for describing broiler growth curves.

Three general growth models (Logistics, Gompertz and Saturation Kinetics) were compared for describing growth of broilers. Accuracy of fit, case of use and interpretation of data were used to compare the models. Data from a broiler feed restriction study was used to illustrate the parameter differences between the models. All three models accurately described the growth of the birds from the different experimental treatments based on coefficients of determination greater than or equal to .966. The Saturation Kinetics model proved to be the least accurate based on examination of residual values but still had a high association to the actual data. Linear regression applied to short intervals of the growth curve also proved to be an accurate means of interpreting growth rates.

Animals↗

PubMed1986

The role of water intake on sexual dimorphism for early growth of broilers.

Two experiments were conducted to investigate feed intake and body weight of males restricted to the water intake of ad libitum females immediately after hatch. Ad libitum males were heavier and consumed more feed than ad libitum females, with differences becoming significant after Day 10. Body weight and feed intake of water-restricted males and females were essentially identical, suggesting that when males and females receive the same amount of water, they also consume similar amounts of feed. Ad libitum males tended to have higher feed efficiencies than females, whereas water-restricted males and females had similar feed efficiencies. These data indicate that unless males are able to consume more water than females, there is an absence of development of sexual dimorphism in body weight during early life.

Animals↗

PubMed1986

Adipose tissue cellularity and growth characteristics of unselected and selected broilers: implications for the development of body fat.

Chicks from large and small eggs were used to increase body weight range within samples of unselected Athens-Canadian (AC) and commercial Cobb (C) broilers. At 54 days of age, representatives of each sex and broiler stock obtained from the large and small eggs were killed. Indices of whole body, muscle, fat, and bone growth were taken. Samples of abdominal fat were fixed with osmium tetroxide for electronic quantification of adipocyte number and size distribution. Broiler stock, egg size, and sex affected all indices of muscle and bone growth on an absolute basis, but only broiler stock significantly affected abdominal fat pad development. Muscle and fat weight, expressed as a proportion of body weight, were larger in C broilers. Abdominal adipocyte number was greater in C than AC (126.0 +/- 10.0 vs. 90.9 +/- 7.7 million, P less than .01), but the greater adiposity of C was associated with an increase in adipocyte size. If the mean adipocyte volume of C (120.4 +/- 8.5 pl) was reduced to the mean adipocyte volume of AC (53.8 +/- 6.5 pl), proportional weight of the abdominal pad of C would have been smaller than proportional pad weight of AC. The problem of excessive abdominal fat deposition in the selected broiler stock appears related to factors that affect control of adipocyte size and body composition.

Adipose Tissue↗

PubMed1986

Acute aflatoxicosis in genetically resistant and nonselected Japanese quail.

Aflatoxin B1 (AFB1) was administered by either oral intubation or intravenous (IV) injection to two lines of Japanese quail selected for aflatoxin resistance (AR2.5 and AR3) and a nonselected control line (NS). Pretreatment feed consumption did not vary significantly between lines; however, normal water intake of AR quail was 25% greater than that of NS quail. Oral AFB1 dosing (1.0 mg/kg body wt) elicited 53 and 25% decreases in feed and water consumption of NS quail within 24 hr. The only postdose change detected in the selected lines was a 10% increase in AR2.5 water intake. Oral AFB1 dosing also caused a significant reduction in excreta dry matter of NS quail. Twenty-four hr after IV AFB1 injection (.75 mg/kg body wt), feed and water consumption of the NS line were depressed by 93 and 75%, respectively, but only feed intake was decreased (13%) in the AR2.5 line. Intravenously injected AFB1 did not affect 24-hr parameters in the AR3 line. Body weight loss was noted in NS quail after both oral and IV dosing, while the AR lines maintained pretreatment body weights. Both AR lines also exhibited resistance to AFB1-induced hepatic lesions observed in NS birds. Biliary output was also studied during a 12-hr period following IV administration of AFB1. Cholecystic bile measurements taken at 1.5- and 3-hr after dosing averaged 34 and 50% higher in the AR lines than in the NS line. These results demonstrate the resistance of the selected quail to AFB1 whether administered orally or intravenously and therefore, indicate the AR line resistance is unrelated to intestinal absorption of the toxin.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗

PubMed1986

The relationship of certain blood parameters to aflatoxin resistance in Japanese quail.

Blood chemistry profiles were obtained for two lines of Japanese quail selected for resistance to aflatoxin, and for a nonselected control line. Nine of the 18 plasma components measured in samples taken at 4 weeks of age changed as a result of selection. Plasma concentrations of total protein, albumin, cholesterol, and potassium, and the activities of lactic dehydrogenase, glutamic-oxalacetic transaminase, and cholinesterase were significantly elevated in aflatoxin-resistant quail compared with the nonselected line. The activities of beta-glucuronidase and alpha-amylase changed most dramatically; both activities were much lower in the resistant lines than in the control line. In another experiment, serum total protein, albumin, alpha-amylase, and beta-glucuronidase were tested as identifiers of aflatoxin-resistant individuals within a nonselected population of quail. Serum samples obtained from 150 nonselected quail immediately before and 24 hr after administration of an oral dose of aflatoxin were analyzed for each of the four components. The acute toxicosis decreased body weight, serum alpha-amylase activity, total protein, and albumin; whereas, serum beta-glucuronidase activity and the coefficients of variation for each parameter were increased. Correlations between measurements made prior to dosing and parameters reflecting aflatoxin susceptibility were not significant. However, postdose determinations of albumin, protein, and beta-glucuronidase were significantly related to susceptibility parameters. These data indicate that the four blood components tested cannot be utilized to identify resistant birds within a nonselected population of quail without an aflatoxin challenge; but albumin, protein, and beta-glucuronidase are correlated with resistance when measured during an aflatoxin stress.

Aflatoxins↗

PubMed1985

Comparative responses of genetically resistant and nonselected Japanese quail to dietary aflatoxin.

Two lines of Japanese quail (AR2.5 and AR3) selected for resistance to aflatoxin and a nonselected control line (NS) were fed diets containing 0, 10, and 20 micrograms of aflatoxin/g of feed. Line-related reductions in mortality and growth inhibition clearly demonstrated the resistance of the AR lines to dietary aflatoxin. Two-week cumulative mortality percentages for the NS, AR2.5, and AR3 lines fed the 10 micrograms/g diet were 13.9, 7.7, and 2.6%, respectively, and 44.4, 17.9, and 12.8% at 20 micrograms/g. Average growth reduction percentages resulting from feeding the 10 and 20 micrograms/g diets to the NS, AR2.5, and AR3 lines were: 17.3 and 27.5%, 10.7 and 20.1%, and 4.3 and 10.5%, respectively. In addition, AR quail were resistant in varying degrees to the following aflatoxin-induced effects: liver lipid accumulation and enlargement, hepatic protein depletion, elevated hepatic beta-glucuronidase activity, bursal regression, and hypoproteinemia. Comparisons of the AR and NS lines fed the control diet revealed no detrimental physiological or biochemical response to selection for aflatoxin resistance. Genetic resistance to aflatoxin was associated with increased relative liver weight, higher liver protein content, and elevated plasma concentrations of protein and lipid compared with NS quail. One or more of these differences may be related to the mechanism of genetic resistance to aflatoxin in AR quail.

Aflatoxins↗

PubMed1985

Sexual dimorphism in early feed and water intake of broilers.

Four trials were conducted utilizing two nonselected (randombred) and two selected (commercial broiler) stocks to investigate sex divergence in feed and water intake, and feed efficiency immediately posthatch. Although differences between sexes in body weight were not significant until 4 days of age, male:female ratios indicated that divergence in body weight started immediately posthatch and increased in a more or less linear fashion with age. At 14 days of age males were 7% larger than females (ratio 1.07) in both selected and nonselected stocks. The male:female ratios for feed intake followed the same general pattern as body weight ratios, starting at low levels immediately posthatch and increasing to the same approximate levels (ratio 1.07). Conversely, the male:female water intake ratios indicated that males consumed more water (4 to 9%) than females immediately following hatch and maintained constant rather than increasing ratios through 12 days. Feed efficiency and water:feed ratios were higher for males than females with the magnitude of the difference greater immediately posthatch. Data from these experiments indicated that both feed intake and feed efficiency are involved in the early body weight divergence between males and females.

Age Factors↗

PubMed1985

The influence of dietary salt on water consumption and carcass lipids in Japanese quail.

Studies were conducted to investigate the influence of dietary salt on water consumption and subsequent carcass lipids in Japanese quail at various ages. In Experiment 1, randombred nongrowth-selected (C) quail were fed 28% protein diets containing .0, .4, .8, 1.6, and 3.2% added salt. In Experiment 2, growth-selected P- and C-line quail were fed 20%-protein diets containing .4% and 3.2% added salt. The different dietary salt levels did not exert a consistent effect on body weight in Experiment 1. There was no adverse effect of salt level on feed consumption and efficiency and no direct effect on abdominal fat or carcass lipid levels. High salt (1.6 and 3.2%) stimulated water consumption and increased water:feed ratios. Water:feed ratios were higher for quail than for broilers, suggesting a species difference. In Experiment 2, C-line quail demonstrated similar effects to the high-salt (3.2%) diet in Experiment 1. High salt (3.2%) adversely affected body weight, feed consumption, abdominal fat, and carcass lipid in P-line quail. There was no affect on feed efficiency, and a substantial stimulation of water consumption with concomitantly increased water:feed ratios. The relatively low abdominal fat observed at 4 weeks of age indicate that nongrowth-selected quail may not be a good model for the study of abdominal fat in broilers.

Abdomen↗

PubMed1985

Postnatal growth and organ development in Japanese quail selected for high growth rate.

As a result of selection for high growth rate in the quail the organ growth pattern has changed considerably. The main change, which characterizes the early part of the postnatal growth, consists of an increased relative size of the digestive organs and a lowered early growth rate of pectoral muscles and feathers. Since the increase in growth rate is linked to an increase in the relative size of the digestive organs, the growth rate is most likely restricted by the capacity to ingest and digest food. It also appears that at least part of the increase in growth rate is made possible by the change in organ growth pattern.

Animals↗