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Biomedical subjects

J W Merkley

Publications and source records attributed to J W Merkley.

16 recordsLinked to original sources
PubMed1989

Adipose tissue deposition and cellularity in cimaterol-treated female broilers.

The effect of feeding a beta agonist, cimaterol, on carcass yield and composition and adipose tissue development was studied in female broilers. Cimaterol was provided at .25 ppm in the feed starting at 4 wk of age. Birds were sacrificed at 4, 6, 8, 10, 12, and 16 wk for determination of eviscerated carcass yield, carcass composition, and growth and cellularity of the abdominal, neck, back, and sartorial adipose depots. Carcass yield was significantly (P less than .01) greater in treated birds than in controls (70.0 vs. 72.8%) at 10 wk of age. Moisture percentage and protein decreased (P less than .05) less rapidly in treated carcasses than in control carcasses with increasing age. Lipid percentage increased (P less than .05) in treated carcasses less rapidly than in control carcasses. The weight of the abdominal fat pad was significantly (P less than .05) lower in treated birds than controls at 16 wk. There were no significant treatment effects on live weights, skeletal growth, or liver weights at any age. The composition of the pectoralis minor was not affected by the treatment. Frequency distributions of adipocyte diameters from the neck and thigh differed from those of the abdominal and back depots at 16 wk. Adipocyte diameter appeared to be more sensitive to the dietary treatment than adipocyte numbers per depot. Both adipocyte size and numbers in each depot continued to increase with increasing age of the broilers. The abdominal fat pad showed the largest percentage increase in cell numbers from 4 to 16 wk of age.

Abdomen↗
PubMed1989

Growth response to chronic beta agonist feeding and mature carcass characteristics of quail (Coturnix coturnix japonica) selected for high and low body densities.

A study was conducted to determine the effect of long-term feeding of a beta agonist (cimaterol) on female Japanese quail. Quail used were from lines selected for high (HD) and low (LD) body density from a randombred population. Dietary treatments consisted of 1) the basal feed, 2) the basal feed containing .5 ppm, or 3) 1.0 ppm of the beta agonist. The treatment period for the six experimental groups extended from 14 to 94 days of age. Weight gains to 49 days and live weights at 94 days of age were greater (P less than .05) in the cimaterol-fed groups. Age and live weight at first egg in both lines were greater (P less than .01) when groups were fed treated diets. Eviscerated carcass yields were higher (P less than .01) and carcass moisture was lower (P less than .05) in treated groups. There were no differences in carcass fat or protein among the dietary treatments. Abdominal fat pad weights were larger (P less than .05) in the heavier (P less than .01) HD line but were not significantly affected by cimaterol. Abdominal adipocyte diameters were significantly larger in HD (P less than .05) and cimaterol-treated (P less than .05) quail.

Abdomen↗
PubMed1988

Association of rate-of-feathering genotypes in broilers with production and carcass composition traits. 2. Effect of genotypes and diet on processing traits and lipid deposition.

Five rate-of-feathering genotypes: K/K, K/k+, and k+/k+ in male and K/W and k+/W in female broilers were produced from matings of grandparent stocks of a common genetic background. Genotypes were compared for differences in processing characteristics and lipid deposition using isocaloric high and low protein diets from 28 to 52 days. The two female genotypes reared on the same diet did not differ on measures of plant weights, eviscerated carcass weights, breast weights, and abdominal fat pad weights. Significant differences were observed among the male genotypes reared on the same diet in plant weights, eviscerated carcass weights, and breast weights. All genotypes reared on the high protein diet had significantly increased plant weights, eviscerated carcass weights, and breast weights and significantly decreased abdominal fat pad weights and percentage carcass lipid.

Animals↗
PubMed1987

Hepatic fatty acid profiles in aflatoxin-exposed broiler chickens.

This study was initiated to determine whether a specific fatty acid marker from hepatic lipids could be identified to confirm aflatoxin exposure in chickens. Male broiler chicks (240) were reared to 21 days of age on diets containing 0, 625, 1.25, 5.0, and 10.0 ppm aflatoxin. Live weights and organ weights differed significantly among the dietary groups. Total liver lipids increased significantly (P less than .001) with increasing aflatoxin levels. Separation of extracted lipids into neutral and polar fractions established that this increase in hepatic lipid was accounted for almost entirely by increases in neutral lipid fractions. A gain of 117% occurred in the weight of neutral lipids as aflatoxin increased from 0 to 10 ppm. In both neutral and polar lipid fractions subsequent chromatographic analysis of fatty acid methyl esters (FAME) showed linear increases in the monoenoic fatty acids with increasing aflatoxin. No single FAME from either lipid fraction was suitable for confirming aflatoxin exposure.

Aflatoxins↗
PubMed1984

The individual and combined effects of aflatoxin and ochratoxin A on various processing parameters of broiler chickens.

Male broilers (Hubbard X Hubbard) were placed at hatching into a completely randomized 2 X 2 X 2 factorial experimental design with the treatments consisting of 0 and 2.5 micrograms aflatoxin/g of feed (ppm) and 0 and 2.0 ppm ochratoxin A. In Trial 1, there were four replicate pens of 10 broilers per replicate at each treatment level. At 3 weeks of age two replicate pens were randomly selected and placed on control feed (0 to 3 weeks), the remaining two replicate pens were maintained on treatment (full-term). In Trial 2, there were three replicates of 38 broilers per replicate at each treatment level. At 3 weeks of age 13 broilers from each replicate pen were randomly selected and placed in separate housing and fed control diets (0 to 3 weeks). The remaining 25 broilers were kept on mycytoxin treatments until the conclusion of this trial (full-term). Data collected in these trials indicate that body weights of broilers were significantly (P less than .05) decreased by aflatoxin, ochratoxin A, and the combination treatments of the full term feeding regimen. Broilers partially recovered body weight in the 0 to 3-week feeding regimen; however, recovery was less rapid during ochratoxicosis compared to aflatoxicosis. Body weights of broilers in the combination treatment remained significantly (P less than .05) depressed throughout the trials. As body weight decreased, parts weights decreased accordingly. Carcass yield was significantly (P less than .05) decreased by all treatments, primarily by a decrease in breast yield.(ABSTRACT TRUNCATED AT 250 WORDS)

Aflatoxins↗
PubMed1983

The effect of sodium fluoride and sodium silicate on growth and bone strength of broilers.

Two experiments were conducted using 300 broilers each. Standard broiler diets were supplemented by adding to the drinking water either sodium fluoride or sodium meta-silicate. Sodium fluoride provided 120 ppm Na and 100 ppm F and 120 ppm Na and 74 ppm Si were provided by the sodium silicate. Control groups received tap water. All groups received a standard corn-soybean meal diet and drinking water ad libitum. All broilers were reared in floor pens, and hardwood shavings were used for bedding. Live weights and feed conversion were determined every 2 weeks. Growth rates, feed conversions, and mortality were not affected by the sodium salts in either experiment. Litter conditions in the pens were closely observed, and no differences were found resulting from the addition of either sodium salt to the drinking water. A significant decrease in humeri strength was observed when one wing of broilers in the control and sodium fluoride treated groups was immobilized with tape during the last 2 weeks of each experiment. This loss of strength was not significant in the sodium silicate group. In both experiments, breaking strength and ash content of humeri and tibiae were significantly increased in birds fed the sodium fluoride when compared to the control group. The sodium silicate group yielded intermediate results.

Animals↗
PubMed1983

Individual and combined effects of aflatoxin and ochratoxin A on bruising in broiler chickens.

A 2 x 2 factorial design with treatments of 0 and 2.5 microgram/g aflatoxin and 0 and 2.0 microgram/g ochratoxin A was used to evaluate the individual and combined effects of these mycotoxins on bruising and blood thigh syndrome in broiler chickens. Trial 1 consisted of four replicate pens of 10 broilers per replicate, which were maintained on these dietary treatments from 0 to 3 weeks of age. At 3 weeks of age two replicate pens per treatment were randomly selected and placed on toxin-free feed with two replicate pens remaining on toxin feed until they were 6 weeks of age when the trial was concluded. In Trial 2 three replicate pens of 38 broilers per treatment were maintained on toxin feed from 0 to 3 weeks of age. At 3 weeks of age 13 broilers per replicate were placed on toxin-free feed with 25 broilers per replicate remaining on toxin until they reached 7 weeks of age when Trial 2 was concluded. These data indicate that a synergistic toxicity exists between aflatoxin and ochratoxin A to significantly (P less than .05) decrease body weight. Body weights of broilers on aflatoxin or ochratoxin A diets for only 3 weeks partially recovered by 6 or 7 weeks of age; however, the body weights of broilers on the interaction treatments for only 3 weeks remained significantly (P less than .05) depressed at 6 and 7 weeks of age.(ABSTRACT TRUNCATED AT 250 WORDS)

Aflatoxins↗
PubMed1983

Effects of low level chronic aflatoxicosis in broiler chickens.

A completely random design consisting of three replicates of 25 broiler chickens (Hubbard x Hubbard) at each of four treatments was used to evaluate the effects of low level, chronic aflatoxicosis on performance and various processing parameters. The treatments in Trial 1 were control, .075, .225, and .675 and in Trial 2 control, .3, .9, and 2.7 micrograms/g toxin in feed (ppm). The chickens were maintained on these treatments from day-old to 7 weeks of age with feed and water available ad libitum. All aflatoxin dose levels in Trial 1 significantly (P less than .05) decreased live, dressed, and chilled eviscerated weight, whereas only 2.7 ppm significantly (P less than .05) decreased live and dressed weight in Trial 2, with chilled eviscerated weight being significantly (P less than .05) decreased at .3 and 2.7 ppm in Trial 2. Parts weights and dimension measurements reflected the aflatoxin-induced decrease in dressed weight. Breast yield (%) was significantly (P less than .05) decreased by aflatoxin while back, wing, drum, and thigh yields were significantly increased by aflatoxin. No effect of aflatoxin was seen on the incidence of crooked keel, feather follicle infection, breast blisters, or conformation. A hypocarotenoidemia and hepatic hyperlipemia were clearly a result of chronic aflatoxicosis in these broiler chickens. These data demonstrate that the toxicity of aflatoxin is dependent on the environment in which broiler chickens are exposed.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1982

Reproductive performance of White Leghorns provided fluoride.

Two trials were conducted to determine if added sodium fluoride in the drinking water of chickens would result in any deleterious effects on reproduction. In both trials 120 individually caged Single Comb White Leghorn hens (SCWL) were used. Experimental groups consisted of a control group which received no fluoride and three treated groups which received 100 parts per million (ppm) fluoride during either the growing period (0 to 20 weeks), production period (from 20 weeks on), or continuously from day 1. In Trial 1 broiler-breeder males that had not been treated with supplemental fluoride were used as the source of semen for artificial insemination. In Trial 2 half the SCWL cockerels used had been treated with 100 ppm F in the drinking water from day 1. The reproductive characteristics measured were egg production, fertility, duration of fertility, and hatchability of fertile eggs. No deleterious effects due to fluoride exposure at the 100 ppm level in the drinking water were observed in the reproductive performance of either pullets or cockerels. Egg production in both trials decreased slightly during the insemination periods in all raised to 4 weeks of age, and no effects of fluoride on progeny growth were noted.

Animals↗
PubMed1982

The effect of floor type on the development of breast blisters and feather follicle infections in broilers.

The effect of floor types on the incidence of feather follicle infection and breast blisters in caged broilers was investigated in two trials. Broilers were reared on corn-soybean meal diets with warm-room brooding. Floor types included litter (control), wire, wire covered with various types of plastic mats, and wire woven with surgical tubing. In trial 1, the effect of a coccidiostat (Monensin, 120 mg/kg of feed) was investigated for broilers not on litter, and in trial 2, the effect of supplemental zinc was investigated. Broilers were processed in the laboratory processing plant when they were 51 (trial 1) and 53 days old (trial 2). Carcasses were evaluated for the occurrence of fleshing downgrades, crooked keels, feather follicle infection, and breast blisters. Incidence of feather follicle infection was low for broilers on litter or wire floor and high for broiler reared on plastic mats. Breast blisters incidence was low for broilers on litter and plastic mats and was high for broilers on the wire floor. Overall carcass quality for litter (control) was superior to any of the cage treatments. Neither the coccidiostat nor supplemental zinc affected the incidence of breast blisters or feather follicle infection.

Animals↗
PubMed1981

A comparison of bone strengths from broilers reared under various conditions in coops and floor pens.

A series of four trials was conducted to compare the influence of several design variables on the strength of bones from coop and floor-reared broilers. So that the activity of coop-reared broilers would increase, a fan system intermittently forced air up through the bottom of the coops. Because the broilers became accustomed to the intermittent force of air, the induced extra activity decreased after the first 7 days of fan use. No differences in bone strength were observed in broilers reared in the control and fan-treated coops. Broilers reared in floor pens with a screen covering placed at a height equal to the height of the coops (29 cm) had significantly (P less than .01) weaker wing bones than floor-reared controls. When the height of the screen was increased to 46 cm, no significant difference was observed in the strength of wing bones of broilers in the screened and control pens.

Animals↗
PubMed1981

Relationship of pen height to bone strength of broilers.

Broilers reared in cages have a high incidence of wing breakage during processing. Three trials were conducted to determine the effects of cage dimensions and floor types on bone breaking strength and wing breakage during processing. Broilers were fed commercial-type diets and processed through the pickers at a commercial processing plant or a research facility. Broken bones were detected by palpation, and humeri and tibia were removed. Breaking strength was determined for the humeri and tibia with a testing instrument. Incidence of breast blisters, crooked keels, follicle infection, fleshing downgrades, and slabsidedness were determined in one trial. Cage height was the major factor affecting wing breakage and humerus strength. Incidence of wing breakage for broilers on wire floors with cages .64 m high was not significantly different from that of control broilers reared on litter with ceiling 2.54 m high. Humerus breaking strength was significantly reduced in two of three trials by the .64-m-high ceiling. Cage rearing increased the incidence of crooked keels and feather follicle infections.

Animals↗
PubMed1981

The effect of sodium fluoride on egg production, egg quality, and bone strength of caged layers.

The development of bone fragility in caged layers is a major problem in the poultry industry. The incidence of bone breakage during the processing of spent hens substantially reduces the economic return from these birds. In two trials, a commercial strain of White Leghorn pullets was used. In each trial, one-day-old chicks were divided into two groups, wing banded, and placed in floor pens. The treated group received fluoridated water at levels up to 300 ppm. The control group of birds received only well water. At 20 weeks of age, birds from each group were transferred to one of two laying batteries. One battery of birds received fluoridated water (100 ppm F). The other served as a control and those birds received only well water. Production rate, egg weight, shell strength, shell thickness, and Haugh units were determined for each bird. At 45 weeks of age, the humeri and tibiae were removed, and bone strength, percentage of bone ash, and fluoride content were determined. Combined data from both trials showed that the fluoride treatment increased the breaking strength of humeri from 6.86 to 13.35 kg and that of tibiae from 6.61 to 13.10 kg. The fluoride treatment also significantly (P less than .01) increased the percentage of bone ash. Egg quality and rate of production were not reduced by the fluoride treatment.

Animal Feed↗
PubMed1976

Increased bone strength in coop-reared broilers provided flouridated water.

Four experiments were conducted to determine the feasibility of using fluoride to mitigate bone fragility (osteoporosis) that develops in cage-reared broilers. The treatments consisted of adding sodium fluoride to the drinking water at the levels of 100, 150, 200, and 200 p.p.m. of fluoride in the four experiments, respectively. Birds were transferred from starting batteries at four weeks of age into six coops. Birds in three coops served as controls; birds in the other three coops were provided the fluoridated water ad libitum from four to eight weeks of age. No significant differences were observed in the final body weights between treated and control birds in the four experiments. The percentage of bone ash was usually greater from the treated birds than from the controls. These differences were significant (P less than or equal to 0.01) in the 150 and 200 p.p.m. treatments. At all levels of fluoridation, the strengths of humeri were significantly (P less than or equal to 0.01) increased. However, at the lowest level of fluoridation, 100 p.p.m., the increase was significant only in the females. Tibia strength was significantly (P less than 0.01) increased only at the 200 p.p.m. level. The increase in bone strength from fluoridation may be sufficiently great enough to result in a decrease in the incidence of bone breakage during the processing of coop-reared boilers.

Animals↗