[Show abstract][Hide abstract] ABSTRACT: Our laboratories are investigating the use of High Energy (10 MeV) Electron-Beam (E-beam) irradiation for is potential use in vaccine development. Ionizing radiation inactivates microorganisms by “direct and indirect” effects on nucleic acids and other cellular components. Though the cells are inactivated, the surface antigenic properties of the microorganisms remain unaltered. We hypothesized that electron-beam (E-beam) inactivated Salmonella enterica serovars could be used as a potential immune modulator to activate the innate immune response and thus reduce Salmonella intestinal colonization and shedding in neonatal chickens. Three replicate experiments were designed to evaluate the efficacy of a high energy E-beam irradiated Salmonella enterica serovar Typhimurium (ST) administered in ovo to: (a) induce a functional innate immune response and (b) reduce ST colonization in the ceca of chicks three-weeks post-hatch. We have previously shown that unmethylated CpG motifs of bacteria DNA oligodeoxynucleotides (CpG-ODN) given in ovo stimulates innate immune responsiveness of chicken heterophils and increases resistance of young chickens to SE colonization; thus were used as positive controls in these experiments Eighteen-day-old chicken embryos were equally divided into four independent treatment groups: (1) a negative control (sham injected, no challenge) group, (2) an infected control (sham injected, challenged) group, (3) a CpG-ODN injected, challenged positive control, and (4) an E-beam ST-injected, challenged group. All treatment groups contained 100 birds, half of the animals from each treatment group were euthanized on day 4 post-hatch so that peripheral blood granulocytes (heterophils) could be collected to evaluate the functional innate immune response. The remaining birds where reared under normal housing conditions for the remainder of the experiment. On day 18 post-hatch the birds were challenged with the homologous ST strain and five days later (day 23 post-hatch), the experiment was terminated to evaluate the colonization of ST in the ceca of the birds. Differences in the leukocyte function and in the log10 cfu of ST counts among treatment groups were determined by analysis of variance. Significant differences were further separated using Duncan's multiple range tests. Here, heterophil function was measured using in vitro assays for (1) oxidative burst and (2) degranulation. Heterophils from the CpG-ODN and E-beam ST-treated birds exhibited a significant increase (P < 0.05) in both the oxidative response and degranulation when compared to all other treatment groups with no differences in heterophil functions between the CpG-ODN and e-beam-treated groups. ST colonization of the ceca was significantly reduced (P < 0.05) in both the CpG-ODN and the E-beam ST-treated birds when compared to the non-vaccinated control birds. These results demonstrate that in ovo administration of E-beam irradiated Salmonella induced a primed heterophil-mediated innate immune response and provide a protective intestinal colonization-inhibition effect against a homologous Salmonella challenge.
[Show abstract][Hide abstract] ABSTRACT: Populations of Salmonella in animals may be substantially reduced by treatment with a vaccine composition which has been produced by exposing whole, intact cells of a Salmonella species to irradiation with an electron beam under conditions effective to kill the cells. The electron beam irradiated cells of Salmonella are effective for stimulating protective immune response in the animals against the Salmonella. Induction of these immune responses significantly reduces or eliminates the colonization of the animal by the Salmonella, and consequently reduces or eliminates the shedding of Salmonella in the feces of the animals.
[Show abstract][Hide abstract] ABSTRACT: The etiological agent of necrotic enteritis is Clostridium perfringens. Traditionally, necrotic enteritis is controlled with in-feed antibiotics. However, increasing consumer demand for drug-free poultry has fostered the search for nonantibiotic alternatives. Yeast extract contain nucleotides that are immunomodulatory and also essential for cellular functions. An experiment was conducted to evaluate the efficacy of NuPro yeast extract (Alltech Inc., Nicholasville, KY) in reducing intestinal C. perfringens levels in broiler chickens. One hundred ninety-two 1-d-old male broiler chicks were obtained and randomly assigned to 6 treatments in a battery cage trial. Treatment 1 consisted of chicks fed a corn-soybean meal basal diet (BD) without added bacitracin methylene disalicylate or NuPro. Treatment 2 consisted of chicks fed BD into which bacitracin methylene disalicylate was added at 0.055 g/kg. Treatment 3 consisted of chicks fed BD supplemented with NuPro at a 2% level for the first 10 d of the experiment. Treatments 4 (PX), 5, and 6 (PN) consisted of chicks that were challenged with 3 mL of the C. perfringens inoculum (~10(7) cfu/mL) on d 14, 15, and 16 of the experiment and fed diets similar to treatments 1, 2, and 3, respectively. On d 1 and 7 postchallenge, intestinal C. perfringens levels, lesion scores, and alkaline phosphatase activity were assessed. On d 1 postchallenge, C. perfringens level in treatment 5 (2.09 log(10) cfu/g) was lower (P < 0.05) compared with the PX treatment (4.71 log(10) cfu/g) but similar to the PN treatment (2.98 log(10) cfu/g). A similar trend was observed on d 7 postchallenge. NuPro supplementation enhanced alkaline phosphatase activity (P < 0.05) in C. perfringens-challenged chicks and appeared to reduce intestinal lesion scores. Although dietary supplementation of NuPro in the PN treatment reduced C. perfringens levels by 1.73 and 0.68 log(10) cfu/g compared with the PX treatment on d 1 and 7 postchallenge, respectively, these reductions were not significant. Extending the period of NuPro supplementation beyond the first 10 d of life should be considered for achieving significant reduction in intestinal C. perfringensg levels.
[Show abstract][Hide abstract] ABSTRACT: Salmonella is one of the leading causes of human foodborne illness and is associated with swine production. Bacteriophages are naturally occurring viruses that prey on bacteria and have been suggested as a potential intervention strategy to reduce Salmonella levels in food animals on the farm and in the lairage period. If phages are to be used to improve food safety, then we must understand the incidence and natural ecology of both phages and their hosts in the intestinal environment. This study investigates the incidence of phages that are active against Salmonella spp. in the feces of commercial finishing swine. Fecal samples (n = 60) were collected from each of 10 commercial swine finishing operations. Samples were collected from 10 randomly selected pens throughout each operation; a total of 600 fecal samples were collected. Salmonella spp. were found in 7.3% (44/600) of the fecal samples. Bacteriophages were isolated from fecal samples through two parallel methods: (1) initial enrichment in Salmonella Typhimurium; (2) initial enrichment in Escherichia coli B (an indicator strain), followed by direct spot testing against Salmonella Typhimurium. Bacteriophages active against Salmonella Typhimurium were isolated from 1% (6/600) of the individual fecal samples when initially enriched in Salmonella Typhimurium, but E. coli B-killing phages were isolated from 48.3% (290/600) of the fecal samples and only two of these phages infected Salmonella Typhimurium on secondary plating. Collectively, our results indicate that bacteriophages are widespread in commercial swine, but those capable of killing Salmonella Typhimurium may be present at relatively low population levels. These results indicate that phages (predator) populations may vary along with Salmonella (prey) populations; and that phages could potentially be used as a food safety pathogen reduction strategy in swine.
Foodborne Pathogens and Disease 03/2010; 7(7):851-6. · 2.28 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Clostridium perfringens-associated necrotic enteritis causes significant economic losses. The objective of this study was to evaluate the effect of bismuth citrate, lactose, and organic acid on the development of necrotic enteritis in broilers. The first study was a dose response that evaluated bismuth citrate at 50, 100, or 200 ppm on bacterial intestinal colonization and lesion development associated with our C. perfringens challenge model. The second study evaluated bismuth citrate, lactose, and citric acid on intestinal pH and lesion development. For the third study, we determined if lactose would enhance the efficacy of bismuth citrate against intestinal colonization and lesion development associated with C. perfringens. In study 1, intestinal lesion scores at the 50, 100, and 200 ppm bismuth citrate treatment level were reduced (P < or = 0.05) when compared with the birds fed 0 ppm bismuth citrate. Intestinal C. perfringens colonization of the 100 and 200 ppm bismuth citrate treatment group was significantly reduced when compared with birds fed 0 ppm bismuth citrate. In study 2, we found no significant differences in lesion development, after C. perfringens challenge, between birds fed 100 ppm bismuth citrate or fed a combination of 100 ppm bismuth citrate with dietary lactose or citric acid relative to the controls. The intestinal pH of birds fed 100 ppm bismuth citrate or fed a combination of 100 ppm bismuth citrate with dietary lactose or citric acid was not significantly reduced when compared with the controls. However, a significant reduction in pH was observed in birds fed a combination of 100 ppm bismuth citrate and lactose relative to the negative controls. In study 3, a decrease (P < or = 0.05) in intestinal lesion scores occurred in birds fed lactose with 100 ppm bismuth citrate, compared with the positive controls. There were no significant differences in intestinal bacterial colonization. These preliminary data suggest that bismuth citrate may reduce intestinal lesion development and C. perfringens colonization in broilers infected with necrotic enteritis.
[Show abstract][Hide abstract] ABSTRACT: Our laboratory is evaluating the efficacy of direct-fed microbials (DFM) and phytogenic products to control Clostridium perfringens, a gram-positive organism associated with decreased performance and morbidity and mortality associated with necrotic enteritis, as well as some recent human food safety issues. Three experiments were conducted to evaluate a DFM (PoultryStar) and a phytogenic product (PEP125), which were administered to birds from day of hatch until termination (d 25) via the drinking water or through supplementation to a wheat-corn diet, respectively. Each experiment contained a nonchallenged negative control and a positive control wherein birds were immunocompromised with a 10x dosage of infectious bursal disease vaccine at 14 d of age and subsequently gavaged with C. perfringens (10(7) cfu/mL) daily for 3 consecutive days starting on d 17. Intestinal lesions, mortality, and log10 values of C. perfringens in the probiotic and phytogenic treatment groups were found to be lower (P<0.05) than those observed in the positive controls. These experiments suggest that the DFM and the phytogenic product could be used as potential alternatives to help control C. perfringens and necrotic enteritis.
[Show abstract][Hide abstract] ABSTRACT: The correct usage of disinfectants is an important component of a successful biosecurity program. The objective of this study was to determine the effect of time, temperature, and organic matter (OM) on disinfectant efficacy. Staphylococcus aureus and Salmonella Typhimurium were used to represent gram-negative and gram-positive bacteria commonly found in commercial poultry housing. The first study evaluated the effect of temperature (4, 20, 32, or 43 degrees C) and time (1, 2, 3, 4, 6, 8, 12, 16, 20, 24, and 30 wk) on the efficacy of disinfectants diluted to working concentrations. The second study determined the effect of OM on the efficacy of working concentrations of freshly prepared disinfectants against the bacteria. For the third study, we compared the bactericidal properties of freshly prepared disinfectants and 30-wk-old disinfectants in the presence of OM. Quaternary ammonium-, chlorhexidine-, phenolic-, and binary ammonium-based solutions represented disinfectants commonly used within the poultry industry. In the first study, all of the disinfectants were effective against S. aureus and Salmonella Typhimurium regardless of treatment. However, the phenolic compound had reduced (P <or= 0.05) efficacy against Salmonella Typhimurium after 6 wk of storage at the highest temperature of 43 degrees C and after 16 wk at the second highest temperature of 32 degrees C. All of the disinfectants were effective against S. aureus regardless of temperature treatment. In the second study, the addition of sterile chicken litter had deleterious effects on all 4 classes of disinfectants against Salmonella Typhimurium. Of the disinfectants tested, the phenolic compound retained efficacy against S. aureus. In the third study, the presence of OM significantly reduced (P <or= 0.05) the efficacy of the 30-wk-old quaternary ammonium and phenolic compound against Salmonella. The fresh quaternary ammonium and binary compound achieved a greater kill (P <or= 0.05) of Staphylococcus, relative to the 30-wk-old disinfectant. These results emphasize the need to use fresh disinfectants and that OM should be removed before disinfection.
[Show abstract][Hide abstract] ABSTRACT: Laying hens are typically induced to molt to begin a new egg-laying cycle by withdrawing feed for up to 12 to 14 d. Fasted hens are more susceptible to colonization and tissue invasion by Salmonella enterica serovar Enteritidis. Much of this increased incidence in fasted hens is thought to be due to changes in the native intestinal microflora. An alternative to feed withdrawal involves feeding alfalfa meal crumble to hens, which is indigestible by poultry but provides fermentable substrate to the intestinal microbial population and reduces Salmonella colonization of hens compared with feed withdrawal. The present study was designed to quantify differences in the cecal microbial population of hens (n=12) fed a typical layer ration, undergoing feed withdrawal, or being fed alfalfa crumble by using a novel tag bacterial diversity amplification method. Bacteroides, Prevotella, and Clostridium were the most common genera isolated from all treatment groups. Only the ceca of hens undergoing feed withdrawal (n=4) contained Salmonella. The number of genera present was greatest in the alfalfa crumble-fed group and least in the feed withdrawal group (78 vs. 54 genera, respectively). Overall, the microbial diversity was least and Lactobacillius populations were not found in the hens undergoing feed withdrawal, which could explain much of these hens' sensitivity to colonization by Salmonella.
[Show abstract][Hide abstract] ABSTRACT: A multi-state outbreak investigation of Salmonella Typhimurim cases associated with pet snakes and the frozen vacuum-packed rodents used to feed them identified a Texas frozen feeder rodent facility (Supplier A) as the source of the Salmonella-infected frozen rodents. Texas authorities collected samples directly from Supplier A. Seven Salmonella-positive samples out of 49 environmental swabs were found and one adult mouse out of 88 frozen feeder rodents was Salmonella-positive by culture. No Salmonella strains were isolated from rodent feeds. The pulsed-field gel electrophoresis (PFGE) subtype patterns of S. Typhimurium isolates from feeder rodent and environment samples were indistinguishable from the outbreak strain isolated from humans. A follow-up investigation was performed on all additional feeder rodent facilities identified in Texas. Salmonella was isolated at one of four facilities; seven of 100 rodent samples were positive for Salmonella at this facility. The serotype S. I 4,,12:i:- was isolated from seven feeder rodent samples, and PFGE patterns of the seven isolates were indistinguishable. As observed in the initial outbreak investigation, no Salmonella were cultured from rodent feeds at any of the facilities. The feeder rodent industry is an insufficiently recognized industry in the United States. Outbreak investigation and testing of additional feeder rodent facilities in Texas indicate that further evaluation of feeder rodent facilities as a source of Salmonella for pet snakes and humans is warranted.
Zoonoses and Public Health 11/2008; 55(8-10):488-96. · 2.09 Impact Factor
[Show abstract][Hide abstract] 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.
[Show abstract][Hide abstract] ABSTRACT: A study was conducted to evaluate the effect of experimental chlorate product (ECP) feed supplementation on Salmonella Typhimurium (ST) in the crop and ceca of market-age broilers. In trial 1, 160 market-age broilers were randomly assigned to 8 treatment groups and replicated twice, with 20 broilers per pen for 1 wk. Trial 2 used the same design, but used 80 market-age broilers with 10 broilers per pen. Treatments were as follows: 1) control feed + double-distilled drinking water (dd H(2)O); 2) control + 18.5% experimental zeolite carrier with dd H(2)O; 3 to 7) control feed supplemented with 0.5, 1.0, 5.0, 10.0, or 18.5% of a feed grade ECP + dd H(2)O; 8) control feed + 1x ECP (0.16% w/v; containing 15 mM chlorate ion equivalent) added to dd H(2)O. Seven-week-old broilers were provided experimental treatments for 7 d, killed, and then ceca and crops were removed and evaluated for ST. Broilers fed 5 to 18.5% ECP or water ECP had a significantly lower (P < 0.05) incidence of ST in the crop (36 to 38% and 14%, respectively) when compared with the control (60%). Broilers fed 10% ECP or water ECP had significantly lower ST crop concentrations (1.03 log(10) and 0.38 log(10) ST/g, respectively) when compared with broilers fed a control diet (1.54 log(10) ST/g). Crop and ceca ST incidence (32 to 48%) and concentration (1.00 to 1.82 log(10) ST/g) were significantly lower in broilers fed 5 to 18.5% ECP as compared with the control (78%; 2.84 log(10) ST/g). Broilers fed 5% or greater ECP had significantly higher water consumption (380 to 580 mL water/d) and litter moisture (31 to 56%) when compared with the control (370 mL water/d; 23% moisture). Only broilers fed 18.5% ECP had significantly lower 7-wk BW (2.77 kg of BW) when compared with the controls (3.09 kg of BW). Average daily gains were significantly depressed in broilers fed 10 or 18.5% ECP compared with the controls. These results indicate broilers supplemented with feed </= 5% ECP or water ECP 7 d before slaughter reduced ST without affecting growth parameters.
[Show abstract][Hide abstract] ABSTRACT: Induction of the innate immune response in newly hatched chickens is important for limiting infections with bacteria, such as Salmonella enterica serovar Enteriditis (SE). CpG oligodeoxynucleotides (CpG-ODN) can stimulate the innate immune response of young chickens. Therefore, we examined the effectiveness of CpG-ODN administered in ovo on intestinal colonization by SE and the ability to modulate the function of heterophils in young chickens. Heterophils were isolated from 2-day-old chickens and were stimulated with heat-killed SE (HK-SE) or PMA for oxidative burst and HK-SE or live SE for degranulation assays. CpG-ODN treatment had no effect on heterophil oxidative burst when stimulated with HK-SE or PMA. However, HK-SE and live SE increased degranulation (P<0.01) in heterophils from CpG-ODN-treated birds compared to PBS-treated controls. In a second experiment, chickens were orally infected with SE on day 10 post-hatch and cecal contents were collected 6 days later for assessment of SE intestinal colonization. CpG-ODN treatment reduced SE colonization by greater than 10-fold (P<0.001) compared to PBS-injected control birds. Overall, we show for the first time that CpG-ODN given in ovo stimulates innate immune responsiveness of chicken heterophils and increases resistance of young chickens to SE colonization.
Veterinary Immunology and Immunopathology 10/2008; 127(3-4):371-5. · 1.88 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The objective of this in vitro study was to evaluate the effects of combining a prebiotic with alfalfa on fermentation by laying hen cecal bacteria. Cecal contents from laying hens were diluted to a 1:3,000 concentration with an anaerobic dilution solution and added to serum tubes filled with ground alfalfa or a layer ration with or without fructooligosaccharide (FOS) prebiotic. Samples were processed in an anaerobic hood, pressurized by using a pressure manifold, and incubated at 37 degrees C. Volatile fatty acid (VFA) and lactic acid concentrations were quantified at 6 and 24 h of substrate fermentation. In this study, fermentation of alfalfa resulted in greater production of acetate, VFA, and lactic acid compared with the layer ration. Although with a relative inconsistency in data between trials, the amendment of FOS to both alfalfa and the layer ration appeared to further increase fermentation as demonstrated by overall higher propionate, butyrate, VFA, and lactic acid concentrations. The effect was more pronounced after 24 h of fermentation, implying time constraints for the optimal production of fermentation products in the chicken gastrointestinal tract. These data indicate that in vitro cecal fermentation can be enhanced by the addition of FOS.
[Show abstract][Hide abstract] ABSTRACT: Induced molting by feed withdrawal has been a common practice in the commercial layer industry and usually involves the removal of feed for a period of up to 14 d. However, this is a practice that is believed to adversely influence the welfare of the hens and there is a need to examine behavioral responses to alternative molt regimens. The behavioral patterns of hens on 90% alfalfa:10% layer ration, 80% alfalfa:20% layer ration, and 70% alfalfa:30% layer ration molt diets were compared with feed withdrawal (FW) hens, and fully fed (FF) hens. The White Leghorn laying hens were approximately 54 wk old and were placed in 3 identical climate-controlled rooms. The hens were individually housed in 2-tier wire battery cages and provided treatment rations and water ad libitum. Nonnutritive pecking, walking, drinking, feeder activity, preening, aggression, and head movement were quantified during two 10-min periods each day for 6 hens from each treatment. Over the 9-d treatment period, hens in the FW, 70% alfalfa:30% layer ration, and 80% alfalfa:20% layer ration groups spent significantly more time walking than hens in the 90% alfalfa:10% layer ration group. The FF and 70% alfalfa:30% layer ration hens spent half as much time preening, whereas the FW hens displayed nearly twice as much nonnutritive pecking when compared with other treatments. Most differences in head movements occurred at the beginning of the molt period, whereas during the last half of molt, alfalfa-fed hens exhibited feeder activity similar to FF hens, and all were significantly higher than that of FW hens. After some initial adjustment by the hens, consumption of alfalfa molt diets appeared to reduce nonnutritive pecking behavior, which is characteristically associated with FW hens.
[Show abstract][Hide abstract] ABSTRACT: Foodborne Salmonella continues to be a major cause of salmonellosis with Salmonella Enteritidis and S. Typhimurium considered to be responsible for most of the infections. Investigation of outbreaks and sporadic cases has indicated that food vehicles such as poultry and poultry by-products including raw and uncooked eggs are among the most common sources of Salmonella infections. The dissemination and infection of the avian intestinal tract remain somewhat unclear. In vitro incubation of Salmonella with mammalian tissue culture cells has shown that invasion into epithelial cells is complex and involves several genetic loci and host factors. Several genes are required for the intestinal phase of Salmonella invasion and are located on Salmonella pathogenicity island 1 (SPI 1). Salmonella pathogenesis in the gastrointestinal (GI) tract and the effects of environmental stimuli on gene expression influence bacterial colonization and invasion. Furthermore, significant parameters of Salmonella including growth physiology, nutrient availability, pH, and energy status are considered contributing factors in the GI tract ecology. Approaches for limiting Salmonella colonization have been primarily based on the microbial ecology of the intestinal tract. In vitro studies have shown that the toxic effects of short chain fatty acids (SCFA) to some Enterobacteriaceae, including Salmonella, have resulted in a reduction in population. In addition, it has been established that native intestinal microorganisms such as Lactobacilli provide protective mechanisms against Salmonella in the ceca. A clear understanding of the key factors involved in Salmonella colonization in the avian GI tract has the potential to lead to better approach for more effective control of this foodborne pathogen.
[Show abstract][Hide abstract] ABSTRACT: Molting is a natural process, which birds undergo to rejuvenate their reproductive organs. The US poultry egg production industry has used feed withdrawal to effectively induce molt; however, susceptibility of Salmonella Enteritidis has encouraged the development of alternative methods. Previous research conducted in our laboratory showed that alfalfa is effective at molt induction and provides equivalent postmolt production numbers and quality when compared with feed withdrawal. In the attempt to further increase the efficacy of alfalfa molt diet and decrease the chicken susceptibility to Salmonella Enteritidis during molt, fructooligosaccharide (FOS) was added to a combination of 90% alfalfa and 10% layer ration in 2 levels (0.750 and 0.375%). Ovary and liver colonization by Salmonella Enteritidis in 3 and 2 of the 4 trials, respectively, were reduced (P <or= 0.05) in hens fed FOS-containing diets compared with hens subjected to feed withdrawal. Significant decreases in ce-cal Salmonella Enteritidis counts were also observed in 2 of the 4 trials. In 3 of the 4 trials, the same diets did not affect (P > 0.05) the production of cecal total volatile fatty acids when compared with hens undergoing feed withdrawal. However, in all 3 alfalfa molt diets, the concentrations of lactic acid were greater (P <or= 0.05) than hens with feed withdrawal, but no differences (P > 0.05) were observed among hens fed alfalfa combined with FOS and hens fed alfalfa/layer ration without FOS. Overall, given the similarities between hens fed 0.750% FOS (H) and 0.375% FOS (L), molt diets combined with the lower level of FOS should be sufficient.
[Show abstract][Hide abstract] ABSTRACT: Two studies were conducted to evaluate the effects of melatonin on Salmonella Enteritidis infection in experimentally challenged laying hens subjected to a forced molt. Leghorn hens (>50 wk of age) were randomly assigned to rooms, acclimated to a 16L:8D regimen, and provided ad libitum access to a nonmedicated mash layer diet and water. Birds in one room were molted (8L:16D; complete feed withdrawal), whereas birds in the second room served as nonmolted controls (CONT). Within each room, birds were randomly assigned to melatonin treatment (MEL; 12 birds/treatment), dosed orally commencing the same day as feed withdrawal for 10 d: (experiment I: 0 or 5 mg of melatonin; experiment II: 0, 10, or 20 mg of melatonin). Three days following feed withdrawal, all birds were experimentally infected with Salmonella Enteritidis, and after 10 d of feed withdrawal, all birds were killed and necropsied. In experiment I, concentrations of Salmonella Enteritidis in the cecal contents and the number of Salmonella Enteritidis-positive tissues from the crop, ceca, liver, spleen, and ovary were higher (P < 0.0001) in the MOLT compared with the CONT treatments. No differences (P > 0.10) were observed in any of the parameters examined due to MEL treatment. For experiment II, cecal concentrations of Salmonella Enteritidis were generally higher in the MOLT compared with the CONT treatment and within molted birds, cecal concentrations were higher in the MEL treatment (P < 0.05). Melatonin treatment in molted birds increased (P < 0.05) the percentage of positive crops in the MOLT+20 MEL treatment (P < 0.05). Salmonella-positive cecal tissue was increased (P < 0.001) in MOLT compared with CONT birds and was also higher in MOLT+10 MEL and MOLT+20 MEL birds compared with the MOLT-only treatment. Results from the current research suggest that dosage with high levels of melatonin may exacerbate Salmonella Enteritidis infection in layers subjected to forced molt.
[Show abstract][Hide abstract] ABSTRACT: Several dietary alternatives to feed withdrawal have been proposed to induce a molt in laying hens. This study compared the behavior of laying hens on an alfalfa crumble diet (ALC) to hens that were either on a conventional layer diet (FF) or hens that had feed withdrawn (FW) during a 9-d trial. Each treatment consisted of 24 hens (3 hens per battery cage), and treatment began after a 2-week acclimation period. Video cameras connected to a digital multiplexer recorded the behavior of the hens. The percentages of observations performing nonnutritive pecking, feeder activity, drinking, walking, preening, head movement, and aggression were quantified for two 10-min periods at daily intervals. The FF hens spent significantly more (P < or = 0.05) time drinking than the other treatments, whereas FW hens displayed the most head movements. From d 1 through 7, FW hens walked less than ALC hens except on d 8 when FW hens walked more than ALC and FF hens. On d 4 and 6, the FW hens spent an increased amount of time preening compared with FF hens until the last few days of the molt period. For the most part, FW hens generally displayed more nonnutritive pecking than ALC and FF hens throughout the molt period. However, FW hen visits to the feeders declined as the trial proceeded, whereas ALC and FF hens generally spent more time at the feeder. In summary, the ALC diet showed potential as an alternative to FW for inducing a molt in laying hens based on reduced nonnutritive pecking behavior, head movements, and greater feeding activity.
[Show abstract][Hide abstract] 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.