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Biomedical subjects

D L Fletcher

Publications and source records attributed to D L Fletcher.

At least 73 records · Page 4Linked to original sources
PubMed1992

Methodology for achieving pigment specifications.

The methodologies for poultry pigmentation are varied and often are not well coordinated. Differences in the ability to measure pigments, as opposed to appearance, have resulted in systems designed to deliver enough pigment to the bird based on experience in achieving and maintaining acceptable product appearance. Through the application of HPLC techniques, however, feed ingredients can be analyzed and diets can be formulated to extremely precise levels; but the effects on the final product can only be measured in gross and vague terms. New developments in computer-aided scanning and imaging systems may allow for an effective evaluation of the complex surface appearance presented by a broiler carcass and can relate subtle differences in feed formulation to the ultimate appearance of the poultry product.

Animal Feed↗
PubMed1992

Lactic acid fermentation of broiler processing waste: physical properties and chemical analyses.

Broiler processing waste (offal), consisting of broiler heads, viscera, and feet, was collected from a commercial processing plant, ground, mixed with a fermentable substrate, and inoculated with actively growing organisms from a commercial silage culture. The offal mixture was fermented at 11, 19, and 37 C for up to 48 h and evaluated for pH, odor, and aqueous, solid, and oil fractions produced by centrifugation. Freshly ground offal, fermented offal, and aqueous and solids fractions were analyzed for moisture, fat, and protein content. The oil fraction produced by centrifugation of the fermented offal was analyzed for fatty acid composition. The optimum fermentation conditions, as determined by final pH, were obtained by the addition of 6% sucrose, inoculation with 10(6) cfu of silage culture organisms/kg of offal, and incubation at 37 C. The pH decreased from 6.2 to 3.9 in 24 h. Freshly ground offal and 48-h fermented offal were found to contain 63.2% moisture, 15.9% fat, and 14.9% protein, and 57.3% moisture, 19.1% fat, and 12.9% protein, respectively. The aqueous and solid fractions were 73.3% moisture, 1.1% fat, and 12.1% protein, and 57.7% moisture, 6.8% fat, and 21.8% protein, respectively. Fermentation was effective in decreasing pH, altering the odor and viscosity, and, upon centrifugation, increasing fat recovery and producing fractions that were easily separated.

Animals↗
PubMed1992

A rapid method for the determination of temperature abuse of fresh broiler chicken.

Ready-to-cook broiler chicken carcasses were obtained immediately postchill from a commercial processing plant. A control group was held at 4 C for 10 days. Test groups were held at 4 C for 2 days, temperature abused at 10, 15, or 20 C for 0, 1, 2, 4, 6, 8, 12, or 24 h, and then held at 4 C for an additional 4 days. Both control and test birds were sampled using whole carcass rinse techniques and bacteria enumerated using impedance detection times (DT) and total plate count (TPC) techniques at incubation temperatures of 18 and 42 C. The DT and TPC showed a significant increase (P less than .05) in the number of organisms recovered at 18 C but did not show a significant increase (P less than .05) in organisms recovered at 42 C when carcasses were held at 4 C continuously for up to 10 days. Carcasses that were temperature abused at 10 C for up to 24 h were not significantly different (P less than .05) from the unabused controls, using either DT or TPC, following incubation at 18 and 42 C. At an incubation temperature of 18 C, carcasses abused at 15 or 20 C had significantly more growth of bacteria than controls at 1, 6, 12, and 24 h and 4, 8, and 12 h as determined by DT and at 6, 12, and 24 h and 1, 2, 4, 8, and 12 h, respectively, as determined by TPC.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Post-mortem biochemistry of Pekin duckling and broiler chicken Pectoralis muscle.

Biochemical post-mortem changes between red and white avian muscle were determined using duckling and chicken Pectoralis muscles, respectively. Six live Pekin ducklings and six live broiler chickens, in each of two trials, were obtained from commercial plants and processed at a pilot facility. After evisceration, carcasses were held at 4 C, then Pectoralis muscles were removed at .25, 1, 4, and 24 h post-mortem, and sampled for pH, lactate, adenosine triphosphate (ATP) content, and R-value (inosine to adenine ratio). Duckling Pectoralis pH significantly (P less than .05) decreased from 6.25 to 5.66 from .25 to 24 h post-mortem, respectively, as compared with that of the chicken, which decreased from 6.41 to 5.62 for the same times. Duckling lactate values, from .25 to 24 h, increased from 15.86 to 28.86 mumol/g, respectively, and chicken lactate values increased from 27.62 to 53.51 mumol/g. The ATP content of the duckling Pectoralis muscle decreased from 1.59 to .14 mumol/g and chicken Pectoralis decreased from 3.42 to .21 mumol/g from .25 to 24h, respectively. The R-values of duckling and chicken Pectoralis significantly increased from .25 to 24 h (.98 to 1.37 and .80 to 1.51, respectively). Duckling and chicken biochemical measurements were significantly different at all post-mortem sampling times, except for 24-h values of pH (5.66 versus 5.62, respectively) and 24-h contents of ATP (.14 versus .21 mumol/g, respectively). The different post-mortem biochemical measurements between duckling and chicken Pectoralis muscle is evidence that different rates of post-mortem metabolism and rigor development exist between these red and white avian breast muscles.

Adenine↗
PubMed1991

Effect of dietary manipulation on c-myc RNA expression in adipose tissue, muscle and liver of broiler chickens.

The effects of dietary restriction on the relative steady state levels of cellular myc (c-myc) mRNA in abdominal adipose tissue, breast muscle and liver of chickens were determined. Fasting was found to increase c-myc RNA expression in adipose tissue (p less than 0.01). This increase returned to normal levels after refeeding. Muscle and liver in fasted birds did not show changes in c-myc that differed from controls. Serum concentrations of glucose, triglyceride (TG), free fatty acids (FFA) and insulin-like growth factor (IGF-I) were compared to levels of c-myc found in control birds. In adipose tissue, c-myc levels were negatively correlated with serum glucose, TG and IGF-I, while in muscle a positive correlation with serum glucose and TG was found. Data suggest that c-myc is involved in the metabolic changes occurring in fat cells under fasting conditions.

Adipose Tissue↗
PubMed1990

Localization of chicken parathyroid glands through vital staining.

Five, fat-soluble dyes and one, metachromatic tissue dye were administered to White Leghorn hens and broilers to determine how these compounds would color parathyroid tissue for subsequent gland localization. Sudan black, sudan red, canthaxanthin, oil red O, beta-apo-8'-carotenal, and toluidine blue O were administered orally in gelatin capsules once a day for 1, 2, or 3 days before slaughter. The dyes were administered at approximately 100 mg/dose. The carotenoid pigments were given at 200 mg/dose. Two administrations were required to develop sufficient visible staining. All dyes except the toluidine blue O were visibly deposited in the parathyroid glands. Sudan black resulted in the greatest contrast with surrounding adipose tissue. Male broilers 3 wk of age that were given one dose of sudan black showed gland definition comparable to that seen in the hens after two doses. Male broilers 5 wk of age showed less gland definition when given sudan black or sudan red for 1 or 2 days. A histological examination indicated that the fat-soluble dyes were located extracellularly. These results indicate that sudan black can be used to visually identify the parathyroid glands of chickens.

Animals↗
PubMed1990

Listeria monocytogenes colonization of broiler chickens.

In three trials, a total of 108 broiler chickens were unchallenged or challenged orally with either 10(2) or 10(6) cells of Listeria monocytogenes at 1, 14, or 35 days of age. The birds were kept in separate wire-floored brooders and growout batteries, fed unmedicated broiler-starter rations ad libitum, and killed 7 days postchallenge. The ceca, duodenum, spleen, liver (including gall bladder), and a cloacal swab were sampled from each bird and were analyzed for the presence of L. monocytogenes. In Trial 1, L. monocytogenes was recovered on all sampling days, but most frequently from birds challenged when 1 day old. In Trials 2 and 3, recovery was only from birds challenged at 1 day of age. The L. monocytogenes organism was not recovered from any uninoculated control birds. There was a dose-related colonization response (10(6) greater than 10(2]; and more recoveries were obtained from the ceca, spleen, and cloacal swabs than from the duodenum and liver.

Animals↗
PubMed1990

A comparison of seven microbiological sampling procedures for hard-cooked eggs.

Seven microbiological sampling methods for hard-cooked eggs were evaluated and compared. Fresh eggs within 24 h of oviposition were cooked at 98 C for 22 min in water and then cooled in 31 C water. Eggs were dipped for 10 min in a physiological saline solution (.85% saline) 10 C cooler than the eggs and containing known numbers of bacteria. Eggs were then stored for 4 days at 6 C and sampled using one of seven rinse or blend procedures on whole eggs, shell, shelled egg contents, or shelled egg contents plus shell. Highest recoveries were made from the peeled egg plus shell rinse, shell rinse, whole egg blend, and shell blend. Lowest recoveries were found with the whole egg rinse, the peeled egg rinse, and the peeled egg blend. These results indicate that significant numbers of organisms are associated with the inner and outer shell surfaces as well as the egg contents surface (albumen). Satisfactory recoveries can be made with the peeled egg plus shell rinse or the whole egg blend. Whole egg rinsing of hard-cooked eggs does not appear to be satisfactory.

Bacteriological Techniques↗
PubMed1989

Influence of sodium pentobarbital on pH, sarcomere length, and muscle tenderness of broiler Pectoralis major muscle.

Six trials were conducted to determine the effect of sodium pentobarbital (SP) anesthesia on broiler muscle pH, sarcomere length, and Allo-Kramer shear values. Birds were divided into six groups, three of which were anesthetized with SP prior to slaughter. Birds from both the anesthetized and nonanesthetized groups were subjected to one of three processing treatments: 1) muscles hot boned as soon as possible after death and immediately analyzed (HB/0); 2) muscles hot boned and aged 24 h in ice/water slush (HB/24); and 3) muscles left on carcass (conventional process) and aged 24 h in ice/water slush (CP/24) before deboning. The SP/HB/0 group was found to have significantly higher (P less than .05) pH values and longer sarcomere lengths than those of the other five treatment groups. No significant differences were observed for pH among the four 24-h aged groups. Sarcomere lengths were found to be shortest in the SP/HB/24 and HB/24 groups followed by SP/CP/24, HB/0, and CP/24 groups. The CP/24 and SP/CP/24 groups had the lowest shear values, with the HB/0, HB/24, and SP/HB/24 groups exhibiting three-fold higher shear values. These results indicate that SP can delay the effects of ante-mortem stress on early rigor processes; however, no such effects were apparent following 24-h aging.

Animals↗
PubMed1989

Early post-mortem metabolism and muscle shortening in the Pectoralis major muscle of broiler chickens.

Three experiments were conducted to examine the effects of sodium pentobarbital (SP), iodoacetate (IO), tubocurarine (TC), and surgical denervation (DN) on early rigor development in broiler breast muscle. In Experiment 1, birds were either anesthetized or not with SP before receiving an injection of IO or TC or maintained as noninjected controls. Experiment 2 was identical except that a treatment of denervation of the breast muscle was added. Experiment 3 was conducted to contrast birds at 1 day (DN1) and 3 days (DN3) denervation prior to slaughter to nonoperated controls. Measurements of muscle lactate, ATP, R value (ratio of inosine to adenine nucleotides), pH, sarcomere lengths, and shear were used to evaluate treatment effects. Results for Experiment 1 showed no significant differences among treatment and control groups for ATP and lactate contents, R values, or sarcomere lengths; however, significantly lower pH and higher shear values were observed for control birds. In Experiment 2, no significant differences were observed among the treatment groups for ATP, R values, or sarcomere lengths. However, lactate and shear values were significantly lower, and pH higher, for the DN and SP treated birds. Experiment 3 resulted in lower lactate and higher pH values for the DN3 treatment in comparison with both DN1 and control groups. Results of these studies indicate that the use of SP and DN can be used to alter the early profiles of rigor development.

Animals↗
PubMed1988

Pectoralis muscle shortening and rigor development at different locations within the broiler breast.

Two experiments were conducted to evaluate differences in rigor development that occur as a function of location within the broiler breast muscles, pectoralis major (p. major) and pectoralis minor (p. minor). Three locations were evaluated, corresponding to anterior, middle, and posterior samples taken between the cranial and caudal ends of each muscle. Results of the first experiment indicated that the 1.55-mu sarcomere lengths of hot-boned p. major muscle at the anterior location were significantly shorter than those at the posterior location, which were 1.69 mu. Sarcomere lengths of p. minor were shorter than those of p. major in hot-boned muscles, but longer in those aged intact, indicating a significant muscle x treatment interaction. In the second experiment, the anterior location of hot-boned p. major reached the onset phase of rigor in about 1 h, whereas those at the posterior location required between 2 and 4 h postmortem. Between 1 and 8 h postmortem, sarcomere lengths for the anterior location of p. major were also significantly shorter than lengths in the posterior location, but the differences after 24 h were not significant. Samples at all locations of p. minor reached onset of rigor by 15 to 30 min postmortem, with no locational differences throughout the 24 h period of aging. The results of both experiments generally indicated differences between profiles of rigor development of the two muscles and between samples at different locations of the much larger and more complex p. major.

Animals↗
PubMed1988

Chicken breast muscle fiber type and diameter as influenced by age and intramuscular location.

Six trials were conducted to determine the influence of muscle (pectoralis major and pectoralis minor) and location within the muscle on fiber type and diameter in four different age groups of chicken. Broilers obtained from a commercial processing plant, Athens Canadian Randombred chickens, roasters, and broiler breeder hens were killed via cervical dislocation. Muscle samples were removed from the anterior, middle, and posterior areas of the pectoralis major (p. major), and from the anterior and posterior areas of the pectoralis minor (p. minor). Frozen transverse muscle sections, 10 mm thick, were prepared at -20 C, stained for adenosine phosphatase activity, and photomicrographed for fiber typing and fiber diameter measurement. No differences were found in fiber types by age group, sex, or location within the muscle. The p. minor muscle had more intermediate fibers than the p. major muscle. Fiber diameters were significantly larger in the posterior portion of the p. major muscle than in the anterior or middle portions in two of the broiler trials, the female roasters, and the breeder hens. No significant differences in fiber diameter were noted for the p. minor muscle.

Age Factors↗
PubMed1988

Research note: effects of caponization on broiler growth.

The effect of caponization on growth of male broiler chicks was investigated in two experiments. Broiler chicks were caponized, sham-operated, or left as intact controls at 3 wk of age (Experiment 1) or 1 wk of age (Experiment 2). When processed at 7 wk of age, intact control broilers in both experiments were significantly heavier than sham-operated or caponized broilers, with no significant weight differences between sham-operated and caponized birds. However, the slope of growth rate in capons was significantly greater than that of sham-operated controls in Experiment 2. Capons also had significantly larger abdominal fat pads than did sham-operated controls.

Animals↗
PubMed1987

Influence of caponization on skin pigmentation of male broilers.

Two experiments were conducted to investigate the influence of caponization on skin pigmentation. Male broiler chicks were divided into caponized, sham-operated, and intact treatment groups with surgery performed at 3 weeks of age (Experiment 1) or 1 week of age (Experiment 2). All chicks were provided with corn-soy broiler diets ad libitum. In Experiment 2, an additional 37.4 mg of total xanthophyll was added per kilogram of finisher diet. At 7 weeks of age, birds were processed, comb size was scored, and the gonadal area was examined to identify partially caponized or improperly sexed birds. Caponized, sham-operated, and intact carcasses for analysis totaled, respectively, 28, 25, and 18 in Experiment 1 and 59, 33, and 30 in Experiment 2. Skin pigmentation was measured by reflectance colorimetry on the anterior portion of the lateral feather tract, on the same area of breast skin after removal from the carcass, and on shank skin removed from the leg. No differences were found in skin lightness (L), redness (a), or yellowness (b) between the treatment groups. These results indicate that pigmentation differences between male and female broilers are not likely to be due to differences in testicular activity.

Animals↗
PubMed1983

The response of male broiler chickens to diets with various protein and energy contents during the growing phase.

1. In two trials each using 2 400 male broilers, the regression of body weight on the linear effects of dietary protein, energy and age, the quadratic effect of age, and their interactions, accounted for approximately 99% of the observed variation during the growing and finishing period (3 to 8 weeks of age). Increasing either dietary protein or energy content significantly increased body weight. 2. The regression of food consumption on the linear effects of age, protein, energy and protein X energy interaction, and the quadratic effect of age accounted for 94% of the observed variation. The regression of food utilisation on the linear effects of protein, energy, and age and the quadratic effects of dietary protein and age accounted for 97% of the observed variation. Food consumption and efficiency were dependent on both dietary protein and energy, increasing with increases in either dietary protein or energy content. 3. The regression of fat in the dressed carcass on the linear effects of protein, energy and age accounted for 19% of the observed variation. Carcass fat increased with increasing age and dietary energy, and decreased with increasing dietary protein. 4. Although body weight, food consumption and utilisation were significantly different between trials, the proportion of carcass fat was not.

Aging↗
PubMed1980

The influence of the light transmission properties of plastic window coverings on broiler pigmentation.

An experiment was conducted to determine the effect of different window coverings on broiler pigmentation. Equal numbers of male and female broilers were grown in open-type houses. The control house had open sides, while each treatment house had window coverings with either 42% or 89% light transmission properties. Birds from houses with window coverings deposited the same amount of pigment in the skin as did birds from the open house as indicated by blood xanthophyll level and excitation purity. Skin color scores, however, as well as dominant wavelengths and luminosities of shanks from these birds, indicated that pigmentation of birds grown in the house with 42% light transmission window coverings was significantly inferior to that observed for birds grown in either the open house or the house with 89% light transmission window covering. It was concluded that in situations where pigmentation is of concern, care should be taken in selecting window coverings which will not adversely affect pigmentation.

Animals↗
PubMed1980

Reproduction of the Oily Bird Syndrome in broilers.

The Oily Bird Syndrome (OBS) was successfully reproduced in broilers under laboratory conditions which included elevated temperatures simulating summer conditions and feeding high energy diets with a relatively wide calorie to protein ratio. No significant difference in incidence of the syndrome was detected in broilers fed a corn-soy diet, or one with 13% animal protein concentrates and 7.5% bakery product, or with a diet containing 10% distillers dried gains with solubles. Substituting animal tallow for poultry oil significantly (P less than .05) increased the incidence of the syndrome. Feeding diets with a more narrow calorie to protein ratio significantly reduced incidence in one experiment, and feeding an unpelleted diet from 3 to 7 weeks of age also significantly reduced the incidence below that of birds fed the same diet in pelleted form. Incidence of OBS was significantly less for birds housed in a separate building with lower temperature conditions than those maintained in a house with a higher environmental temperature. The OBS could best be observed under commercial processing conditions. Results of these experiments show that growing broilers at a high environmental temperature and feeding diets with wide calorie to protein ratios provide conditions conducive to the development of OBS. Further studies will be necessary to determine the specific etiology of the syndrome.

Animals↗