Z R Howard

Texas A&M University, College Station, TX, United States

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Publications (7)20.43 Total impact

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    ABSTRACT: Since one of the costs in the commercial egg industry is that of replacement pullets, commercial egg layer managers have opted to induce molt older hens in order to extend their productive life for additional egg laying cycles. Conventional molt induction involves the complete removal of feed for several days. However, this management practice can lead to deleterious physiological responses by the hen and subsequent susceptibility to infection by pathogens. Consequently less stressful molting regimens involving the feeding of low energy diets such as alfalfa have been developed. In this study, 80 week old laying hens that were deprived of feed or fed alfalfa meal during a nine day induced molt. Full fed hens were used as the control. On day 8 serum triglycerides were quantified and on day 9 hens were euthanized and the liver, spleen, heart, intestine, pancreas, ovary, and kidney were collected and weighed. Intestinal weight were highest in the non-molted hens, lower in the hens fed alfalfa, and lower still in the hens deprived of feed. Molted hens exhibited reduced weights of liver, heart, ovary, and pancreas compared to the non-molted hens. Serum triglycerides were highest in the non-molted hens, less in feed deprived hens, and the lowest in alfalfa fed hens. These results suggest that a comparable molt could be achieved with feeding alfalfa meal to 80 week hens compared to feed deprivation.
    Bioresource Technology 10/2008; 99(14):6692-6. · 5.04 Impact Factor
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    ABSTRACT: The practice of induced molting involves the restriction of light, feed removal and optionally water for 5-14 days. However, there is growing concern regarding feed removal and animal welfare issues. With this in mind, alternative diets have been developed to produce similar molting effects as that of feed deprivation. Alfalfa, which largely consists of insoluble fiber, can be used as a molting diet. In this study, heterophil and lymphocyte counts, serum chemistry, and organ weight parameters were evaluated in hens that were deprived of feed or fed alfalfa during a nine day induced molt. Full-fed hens were used as the control. Blood serum parameters assessed included calcium, magnesium, glucose, total protein, ketone bodies, uric acid, and cholesterol. White blood cells were counted and categorized by cell type. On the ninth day of the trial, the hens were euthanized and the liver, spleen, heart, intestine, pancreas, ovary, oviduct, and kidney were collected and weighed. On day 8 birds molted with alfalfa or by feed deprivation had significantly higher (P<0.05) levels of ketone bodies and cholesterol and lower levels of calcium, and magnesium compared to the full-fed hens while birds molted by feed deprivation exhibited significantly lower levels of uric acid. Birds molted by both methods exhibited significant reductions in ovary, oviduct, liver and pancreas weights and increased spleen weights when compared to the non-molted hens. On days 0, 2, and 6 there were no significant differences (P>0.05) in either heterophil or lymphocyte percentages. However, heterophil percentages were higher in feed withdrawal birds than full-fed birds on day 4 but lymphocyte percentages were higher in full-fed birds compared to feed withdrawal birds. On day 8 of the induced molt lymphocyte percentages were higher from full-fed birds when compared to feed withdrawal birds but no significant differences were detectable for heterophil percentages. Based on reproductive organ weight loss and changes in serum and immunological responses of birds during molt, it appears that alfalfa meal can be an effective molt induction alternative.
    Bioresource Technology 02/2008; 99(3):604-8. · 5.04 Impact Factor
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    ABSTRACT: An in vitro study was designed to determine the extent of Salmonella enterica serovar enteritidis survival and growth permissiveness in egg components isolated from shell eggs held at refrigeration temperature over an 8 week time period. Eggs were collected from a commercial laying facility at one-week intervals for eight weeks and stored at refrigeration temperature. After storage, eggs were dipped in ethanol, cracked aseptically and separated into yolk and albumen samples. S. enteritidis resistant to novobiocin and nalidixic acid were inoculated on to the surface of the yolk membrane at a concentration of approximately 106 CFU mLˉ1. Yolks were then covered with albumen and incubated for 24 hrs at 25ºC. After incubation, eggs were separated into component parts. Samples were removed from yolk, albumen and yolk membrane and diluted 10-fold in sterile phosphate buffered saline. In albumen, S. enteritidis counts were increased in weeks 3 and 8 compared to week 1 (trial 2). The frequency of eggs exhibiting net growth of S. enteritidis in albumen occurred at week 7 versus weeks 0 and 1 in trial 1 and weeks 3 and 8 versus weeks 0 and 2 in trial 2. In the membrane fraction, the frequency of eggs exhibiting net growth of S. enteritidis occurred at weeks 5 and 8 versus week 0 in trial 2. In the yolk fractions, S. enteritidis counts recovered from week 6 eggs were significantly higher (P<0.05) than those of weeks 0, 2, 3 and 7 (trial 2) and the number of detectable S. enteritidis positive eggs were greater in week 8 than week 5 in trial 1. This suggests that egg components recovered from aged eggs stored at refrigeration temperatures infrequently supported S. enteritidis net growth but generally did not inhibit survivability.
    American Journal of Agricultural and Biological Science. 01/2007;
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    ABSTRACT: Because food and poultry industries are demanding an improvement in written communication skills among graduates, research paper writing should be an integral part of a senior undergraduate class. However, scientific writing assignments are often treated as secondary to developing the technical skills of the students. Scientific research paper writing has been emphasized in an undergraduate course on advanced food microbiology taught in the Poultry Science Department at Texas A& M University (College Station, TX). Students' opinions suggest that research paper writing as part of a senior course in Poultry Science provides students with scientific communication skills and useful training for their career, but more emphasis on reading and understanding scientific literature may be required.
    Poultry Science 03/2006; 85(2):352-8. · 1.52 Impact Factor
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    ABSTRACT: Salmonella enterica serovar Typhimurium has been isolated from commercial egg production facilities in the United States. Given its importance as a causative organism for food-borne salmonellosis, identifying approximate timelines for bacterial invasion of the egg is needed. The objective of this study was to examine net growth of S. Typhimurium in egg components over time. In trial 1 eggs were collected over a 24 hour period from a flock of single comb white leghorn hens while in trial 2 eggs were picked up from a commercial laying source once a week over the course of eight weeks and stored. Eggs were held at refrigeration temperature and each week, subsets of eggs were cracked, separated into yolk and albumen components, and inoculated with 108 CFU/ml of novobiocin and nalidixic acid (NO/NA) resistant S. Typhimurium onto the vitelline membrane of the egg. Yolks were then covered with albumen. Eggs were incubated for twenty-four hours at 25°C. After incubation eggs were again separated into albumen, yolk, and vitelline membrane samples. In trial 1, S. Typhimurium net growth occurred in albumen by the second week and continued from 4 to 8 weeks while in trial 2 net growth only occurred at week 5 and 7. S. Typhimurium net growth on vitelline membranes occurred by 2 weeks and continued from 4 to 8 weeks in trial 1 while no net growth occurred in trial 2 over the 8 week period. Yolk samples showed no net increases in S. Typhimurium populations over the 8 week period. Salmonella enterica serovar Typhimurium ist aus Hühnereiern isoliert worden, die in den USA für den Verkauf vorgesehen waren. In Kenntnis, dass dieses Bakterium lebensmittelabhängig humanpathogen sein kann, ist es von Interesse, den zeitlichen Verlauf der bakteriellen Besiedlung von Eiern zu untersuchen. Ziel der vorliegenden Studie war es daher, das Wachstum von S. Typhimurium in den Ei-Komponenten in Abhängigkeit von der Zeit zu untersuchen. Im 1. Versuchsansatz wurden die Eier einer Schar Leghorn-Hennen im Zeitraum von 24 Stunden gesammelt, während im 2. Versuchsansatz einmal wöchentlich im Handel angebotene Eier in einem Zeitraum von 8Wochen erworben wurden. Die Eier wurden im Kühlschrank aufbewahrt. Einmal wöchentlich wurden Eier entnommen und geöffnet; das Eiweiß wurde vom Dotter getrennt; die den Dotter umhüllende Haut wurde mit 108 CFU/ml einer Novobiocin- und Nalidixinsäure-resistenten S. Typhimurium-Kultur beimpft. Die beimpften Dotter wurden mit dem Eiweiß bedeckt und bei 25°C 24 Stunden lang inkubiert. Anschließend wurden Proben genommen vom Eiweiß, Dotter und der ihn umhüllenden Haut. Beim Versuchsansatz 1 begann das Wachstum von S. Typhimurium im Eiweiß in der 2. Woche und setzte sich in der 4. bis 8. Woche fort; beim Versuchsansatz 2 dagegen war das Wachstum von S. Typhimurium im Eiweiß nur in der 5. und der 7. Woche zu verzeichnen. Auf der Dotter-umhüllenden Haut war beim Versuchsansatz 1 Wachstum nach 2Wochen und danach im Zeitraum der 4. bis 8. Woche nachzuweisen, beim Versuchsansatz 2 nur in der 5. und 7. Woche. Der Eidotter wies während der 8Wochen kein Wachstum von S. Typhimurium auf.
    Journal für Verbraucherschutz und Lebensmittelsicherheit 01/2006; 1(1):28-32. · 0.67 Impact Factor
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    ABSTRACT: Transovarian transmission of paratyphoid Salmonella is well documented and occurs at a low incidence in chickens. However, the exact mechanism of follicular invasion is not well understood. The following study investigates the ability of Salmonella to invade ovarian follicles at different stages of follicular maturity in vitro. Ovarian follicles were collected from Leghorn hens and separated into three stages of maturity: (1) large yellow follicles or F follicles (LYF), (2) small yellow follicles (SYF), and (3) small white follicles (SWF). All follicles were incubated at 37 degrees C in RPMI 1640 medium. Follicles were incubated with 1 x 10(6) CFU/mL of Salmonella typhimurium and Salmonella enteritidis sensitive to gentamicin for 2 h. Samples were then removed from the bacterial culture, and placed in medium containing gentamicin sulfate for 5 h to kill any S. typhimurium or S. enteritidis, which had not invaded the follicular membrane. After the 5 h incubation, follicles were stomached in phosphate buffered saline. Serial dilutions were made of each follicle and viable S. typhimurium and S. enteritidis cells were enumerated on brilliant green agar. Two identical trials were conducted. Data suggest that Salmonella may differentially invade ovarian follicles depending on maturity of the follicle, and that SWF may be more susceptible to S. typhimurium and S. enteritidis invasion than either the SYF or the LYF.
    Veterinary Microbiology 07/2005; 108(1-2):95-100. · 3.13 Impact Factor
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    ABSTRACT: Dietary molt induction to initiate additional egg laying cycles in commercial laying hen flocks is a wide spread practice in the United States. Feed deprivation is the most commonly used method but this practice has generated several concerns which has lead to research for viable alternative approaches. From a management standpoint a single ingredient molting diet consisting of high fiber-low energy represents an easily adaptable diet for large laying hen production units. Alfalfa meal is readily available in most commercial locations and possesses many of the desirable properties of an ideal laying hen molt diet. In the current study hens at a commercial laying facility were molted by both alfalfa and feed deprivation. After the hens had reentered post-molt commercial egg production, eggs were examined for egg quality performance. Egg shell strength, albumen height, yolk height, weight, length, and yolk color were all tested using various mechanical techniques. The eggs were also sampled for testing by consumer sensory panels that assessed the desirability of the eggs' color and flavor/texture. Eggs laid by hens molted by alfalfa had a significantly lower (p<0.05) "a*" level of colorimetry. Eggs laid by hens molted with alfalfa also exhibited significantly higher (p<0.05) egg weights and length. In the consumer sensory test, there was no significant difference (p>0.05) in color or flavor/texture scores in eggs from either feed deprived or alfalfa molted hens. The consumer sensory and mechanical quality attributes indicates that alfalfa shows promise as an alternative molt induction diet by providing a single diet option for extending egg production into a second egg laying cycle.
    Bioresource Technology 06/2005; 96(8):907-11. · 5.04 Impact Factor