Biomedical subjects

L F Kubena

Publications and source records attributed to L F Kubena.

At least 19 recordsLinked to original sources

PubMed2006

Effects of alfalfa and fructooligosaccharide on molting parameters and bone qualities using dual energy X-ray absorptiometry and conventional bone assays.

The aim of this study was to evaluate effects of alfalfa and fructooligosaccharides (FOS) on molting performance and bone parameters compared with the conventional feed withdrawal molting procedure. A total of 36 Single Comb White Leghorn hens (84 wk of age) were used for this experiment. The hens were divided into 6 treatment groups with 6 birds per treatment: pre-trial control (PC), full fed (FF), feed withdrawal (FW), 100% alfalfa (A100), A100 + 0.375% FOS (A100L), and A100 + 0.75% FOS (A100H). At the end of the 9-d molt period, hens were euthanized, and tibia and femurs were collected to evaluate bone qualities using dual-energy x-ray absorptiometry (DXA), Instron (Model 1011 Instron Universal Testing Machine, Instron Corp., Canton. MA), and conventional bone assays. Egg production was recorded during the molting period to evaluate first day out of production, and ovary was also collected to measure ovary weight. Alfalfa molting diets had comparable molting parameters, such as percentage of BW loss, ovary weight, and first day out of egg production, to the conventional feed withdrawal molting procedure, and FOS supplementation did not have any detrimental effects on molting performance. Conventional bone assay and DXA results suggest that hens lose a considerable amount of bone minerals during a molting period. The tibia and femur bone strengths of the FF, FW, A100, and A100L hens were significantly lower than the PC hens, whereas hens fed A100H had similar tibia bone breaking strength to that of the PC hens. The bone parameters measured by conventional assays, bone breaking strength measured by Instron, and bone density and mineral content measured by DXA were highly correlated to each other.

Absorptiometry, Photon↗

PubMed2006

The effect of an experimental chlorate product on Salmonella recovery of turkeys when administered prior to feed and water withdrawal.

Previously, an experimental chlorate product (ECP) has been observed to reduce Escherichia coli and Salmonella infections in swine, cattle, and broilers. The following studies were performed to investigate the effects of different concentrations and durations of administering ECP on crop and ceca Salmonella typhimurium (ST) colonization of turkeys. In 2 separate trials, each conducted with 2 replicates, 15-wk-old turkey toms were challenged with 10(7) to 10(9) cfu of ST. In Experiment 1, toms were administered 0, 0.5, 1.0, 2.0, or 4.0x of ECP (a 1.0x concentration is equivalent to a 15 mM chlorate ion concentration) in the drinking water for 38 h. In Experiment 2, toms were administered a 2x concentration of ECP in the drinking water for 0, 14, 26, or 38 h prior to water withdrawal. All treatments were followed by a 10-h water withdrawal and an 8-h feed withdrawal prior to organ sampling. In Experiment 1, turkeys provided ECP had significantly (P < 0.05) lower populations and incidences of crop (>1.4 log reduction) and ceca (>0.6 log reduction) ST as compared with control birds (2.1 and 0.94 log ST average for all trials, respectively), with little or no additional benefit from administration of higher ECP concentrations. In Experiment 2, toms provided ECP had lower populations of crop (>2.2 log reduction) and ceca (>1.5 log reduction) ST when compared with controls (3.1 and 1.8 log ST, respectively). Again, there appeared to be little benefit in longer administration intervals on quantitative reduction of ST. These experiments suggest that the ECP significantly reduces Salmonella colonization in commercial turkeys when administered prior to feed and water withdrawal.

Animal Feed↗

PubMed2006

Effect of various combinations of alfalfa and standard layer diet on susceptibility of laying hens to Salmonella enteritidis during forced molt.

Feed deprivation is commonly used by the poultry industry to induce molting and stimulate multiple egg-laying cycles. However, feed deprivation has been observed experimentally to increase susceptibility of poultry to Salmonella infections. Previous studies indicated that alfalfa was efficacious in reducing Salmonella; the present investigation was designed to evaluate the efficacy of combined alfalfa and layer diets on Salmonella colonization. Leghorn hens over 50 wk of age were divided into 12 groups of hens and placed in individual laying cages. One week prior to dietary changes, hens were put on an 8L:16D photoperiod that continued for the 9-d experiment. Hens were challenged orally with 104 cfu of Salmonella Enteritidis (SE) on d 4 of treatment and cultured for SE at the termination of the 9-d study. Two independent experiments were conducted consisting of the following treatment groups: nonfed hens, full-fed standard commercial layer diet, 100% alfalfa meal diet, a 90% alfalfa meal/10% standard commercial layer diet, and a 70% alfalfa meal/30% standard commercial layer diet. When evaluating SE colonization in the ceca (Exp. 1), a reduction (P < 0.05) was seen in the 100% alfalfa meal diet and the 70% alfalfa meal/30% standard commercial layer diet treatment groups when compared with the controls with Log10 values of 0.54, 0.44, and 2.82, respectively. Evaluation of physiological parameters showed the alfalfa treatment groups had reductions (P < 0.05) in weight loss, ovary weight, and feed consumption when compared with the full-fed standard commercial layer diet hens, and these results were comparable with the nonfed hens. In Exp. 2, all of the treatment groups had a reduction (P < 0.05) in SE colonization of the ceca when compared with the controls. There were also similar physiological reductions in weight loss, ovary weight, and feed consumption when birds were fed the alfalfa diets in Exp. 2. These data suggest that alfalfa can potentially be combined with layer ration to limit SE infection and still induce a molt comparable with feed withdrawal.

Animal Feed↗

PubMed2005

Ovarian laying hen follicular maturation and in vitro Salmonella internalization.

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.

Animals↗

PubMed2005

Alfalfa as a single dietary source for molt induction in laying hens.

Molting is a process by which a hen's reproductive tract is rejuvenated prior to the beginning of a laying cycle. This process is often artificially induced in commercial settings in order to extend the productive life of a flock of hens. The most common method for the induction of molt is feed withdrawal for a period of several days. It has been noted that feed withdrawal, while effective in inducing molt and allowing an adequate reproductive rest period for the hen, may cause deleterious effects on the animal. This has prompted the investigation of alternatives to feed deprivation for the induction of molt in commercial laying hens. This study involved feeding alfalfa to hens to assess its ability to induce molt. Results show that alfalfa meal and alfalfa pelleted diets were equally effective as feed withdrawal in causing ovary weight regression in birds. Molted hens induced by alfalfa diets exhibited postmolt levels of egg production over a twelve week period that were similar to that of hens molted by feed withdrawal. The postmolt eggs laid by hens molted by alfalfa were of comparable quality to eggs from feed deprived hens. Alfalfa, a fibrous feed with low metabolizable energy, may be provided to hens on an ad libitum basis for an effective molt induction that retains comparable egg quality and production.

Analysis of Variance↗

PubMed2005

Reduction of Salmonella enterica serovar enteritidis colonization and invasion by an alfalfa diet during molt in Leghorn hens.

The standard method for molting to stimulate multiple egg-laying cycles in laying hens is feed deprivation. However, the physiological changes within hens caused by feed deprivation increase susceptibility of the hens to Salmonella enterica serovar Enteritidis (SE) infection. In an effort to develop an alternative method to induce molting without increasing susceptibility to SE, an alfalfa diet was compared with the standard molting method for the level of ovary regression and SE colonization. Hens over 50 wk of age were divided into 3 treatment groups (12 hens/group): nonmolting by normal feeding (NM), molting by feed deprivation (M), and molting by alfalfa diet (A). Individual hens on all treatments were challenged orally with 10(5) cfu of SE on the fourth day after feed changes and were analyzed for ovary weight and SE colonization or invasion in crop contents, cecal contents, liver, spleen, and ovary on the ninth day. In 3 of the 4 trials, there was a significant decrease in SE colonization of the crop between the alfalfa diet (A) and the feed deprived molt (M). In most of the 4 trials, there was a significant reduction in SE infected organs in birds fed the alfalfa diet (A) compared with birds undergoing feed deprived molt (M). Most of the trials showed no significant difference in overall SE between A and NM. Therefore, the results of this study suggest that an alfalfa diet has the potential to be used as an alternative method for forced molting, without increasing the incidence of SE in eggs and internal organs.

Animal Feed↗

PubMed2005

Effects of drinking water treatment on susceptibility of laying hens to Salmonella enteritidis during forced molt.

Feed deprivation is used in the layer industry to induce molting and stimulate multiple egg-laying cycles in laying hens. Unfortunately, the stress involved increases susceptibility to Salmonella enteritidis (SE), the risk of SE-positive eggs, and incidence of SE in internal organs. Leghorn hens over 50 wk of age were divided into 4 treatment groups of 12 hens each in experiment 1 and 3 treatment groups of 12 hens in experiments 2 and 3; hens were placed in individual laying hen cages. Treatment groups were 1) nonmolted (NM) and received feed and distilled water for 9 d, 2) force molted by feed removal for 9 d and received distilled water, 3) force molted by feed removal for 9 d and received 0.5% lactic acid (LA) in distilled water. An additional group (4) in experiment 1 only was force molted by feed removal for 9 d and received 0.5% acetic acid in distilled water. Seven days before feed removal hens were exposed to an 8L:16D photoperiod, which was continued throughout the experiment. Individual hens among all treatments were challenged orally with 10(4) SE on d 4 of feed removal. When compared with the NM treatments, weight losses were significantly higher in the M treatments, regardless of water treatments. When compared with NM treatments, crop pH was significantly higher in the M treatment receiving distilled water. Crop pH was reduced to that of the NM controls by 0.5% acetic acid in the drinking water. No consistent significant changes were observed for volatile fatty acids. The number of hens positive for SE in crop and ceca after culture and the number of SE per crop and per gram of cecal contents were higher in the M treatments, when compared with the NM treatments, but there was no effect of addition of either of the acids to the drinking water. Additional research using different acid treatment regimens may provide a tool for reducing the incidence of SE in eggs and internal organs during and following molting of laying hens.

Acetic Acid↗

PubMed2005

Utilizing different ratios of alfalfa and layer ration for molt induction and performance in commercial laying hens.

Molting is a common practice used by the commercial egg industry to rejuvenate flocks for a second or third laying cycle. During this time the hens rest from production, and the reproductive organs are rejuvenated to increase production and quality during the next laying cycle. Although feed withdrawal (FW) is the most popular and effective method of molt induction, it has come under scrutiny due to food safety issues and animal welfare issues. This study involved feeding alfalfa mixed with layer ration at different ratios to hens to determine their ability to induce molt. The treatment ratios were 100% alfalfa (A100), 90% alfalfa and 10% layer ration (A90), and 70% alfalfa and 30% layer ration (A70). In addition, a fully fed (FF) nonmolted control and a FW negative control were used. Alfalfa is an insoluble, high fiber feedstuff with low metabolizable energy. Egg production for A90 and FW treatments ceased completely by d 6, whereas birds fed A100 and A70 ceased egg production by d 8. Ovary and oviduct weight of hens fed all molting diets decreased (P < 0.05) by an average of 1.5 to 2.5% (BW basis) compared with FF control during the 9-d molt induction period. As the percentage of layer ration increased, feed intake also increased and percentage of BW loss decreased during the 9-d molt induction period. Hens molted by FW lost an average of 25.8% BW, whereas A70 hens lost 18.9% BW. Nonmolted hens (FF) and A70 treatment hens had significantly lower (P < 0.05) egg production when compared with all other treatments over the 39-wk postmolt period. FF treatment hens also had lower (P < 0.05) albumen heights when compared with all other treatments. From these results, alfalfa or alfalfa mixed with layer ration appears to be viable alternatives to conventional FW methods for the successful induction of molt and retention of postmolt performance.

Agriculture↗

PubMed2005

Comparisons of molting diets on skeletal quality and eggshell parameters in hens at the end of the second egg-laying cycle.

A study was conducted to evaluate skeletal quality and eggshell parameters of molted hens at the end of the second laying cycle. Sixty Single Comb White Leghorn hens were used for this study. There were 2 controls and 4 molting treatments: full-fed control 1 (82 wk old; FF1), full-fed control 2 (122 wk old; FF2), feed withdrawal (FW), 100% alfalfa (A100), 90% alfalfa/10% layer ration (A90), and 70% alfalfa/30% layer ration (A70). At the end of the second laying cycle (approximately 122 wk of age), hens were euthanized by CO2. Tibia and femur were collected. There were no differences in bone parameters between FF1 and FF2 (P > 0.05) hens. There were no differences in bone parameters among the different molting dietary treatments (P > 0.05). In the eggshell parameters, the FF2 hens exhibited heavier egg weights than the FF1 (P < 0.05), whereas the percentage shell and egg production of the FF1 birds were significantly higher than those of the FF2 birds. Shell weights of the FW and A90 birds were significantly heavier than that of the A100. The correlation analysis showed that overall bone parameters were negatively correlated with eggshell parameters. Bone parameters were highly correlated with each other. Shell weight, percentage shell, and shell thickness were positively correlated with each other, whereas egg weight was negatively correlated with percentage shell. These results suggest that age of hens and molting dietary treatments influence egg parameters, and eggshell formation is closely related to bone metabolism in laying hens.

Animal Feed↗

PubMed2004

The combination of zinc compounds and acidic pH limits aerobic growth of a Salmonella typhimurium poultry marker strain in rich and minimal media.

The objective of the present study was to examine the combined effects of zinc compounds with different acidic pH levels on the aerobic growth of a S. typhimurium poultry isolate in either rich or minimal media. When overall main effects of pH levels of medium or concentrations of Zn compounds were compared, growth rates of the S. typhimurium poultry isolate were significantly (p < 0.05) decreased by stepwise increase of pH levels of medium (pH 4, 5, 6, and 7) or concentrations (0.67, 3.35, and 6.03%) of Zn compounds (Zn acetate and Zn sulfate). In general growth rates of S. typhimurium poultry isolate appeared to be more reduced by Zn acetate than by Zn sulfate and more reduced in minimal media compared to rich media.

Animals↗

PubMed2004

Effects of high zinc diets using zinc propionate on molt induction, organs, and postmolt egg production and quality in laying hens.

This study was conducted to determine the ability of an alternative salt form of 1% Zn, Zn propionate, to induce molt in 66-wk-old hens. The hens were randomly assigned to 4 treatment groups of 27 or 28 birds each: a) molted conventionally by feed withdrawal, b) 1% Zn as Zn acetate, c) 1% Zn as Zn propionate, or d) nonmolted control for 9 d. Feed intake was (P < 0.05) depressed in Zn acetate and Zn propionate hens when compared with nonmolted control hens during the 9 d. Ovary weights of hens undergoing feed withdrawal, Zn acetate, or Zn propionate were not (P > 0.05) different from each other, but all were (P < 0.05) lighter than the ovary weights of nonmolted control hens. Zinc concentrations in the kidney and liver were (P < 0.05) increased in Zn acetate and Zn propionate molted hens when compared with nonmolted hens on the control diet or hens molted by feed withdrawal. Bone ash values were (P < 0.05) increased for Zn acetate and Zn propionate molted hens or nonmolted control hens as compared with molted hens on feed withdrawal. Over the entire 3-mo postmolt period, there were no significant differences in interior egg qualities, but egg weights from hens fed Zn propionate were (P < 0.05) heavier than those from hens on feed withdrawal. The data of the current study demonstrated that feeding a Zn propionate (1% zinc)-supplemented diet can induce molt.

Animal Feed↗

PubMed2004

Research note: Effects of different bone preparation methods (fresh, dry, and fat-free dry) on bone parameters and the correlations between bone breaking strength and the other bone parameters.

A study was conducted to evaluate effects of different bone preparation methods on bone parameters and the correlations between bone breaking strength and the other bone parameters. Bone breaking strength is dramatically changed depending on bone preparation methods, whereas other bone parameters such as ash content and ash concentration are not significantly influenced by bone preparation methods. Thus, the objective of this study was to evaluate the effects of 3 bone preparations (fresh, dry, and fat-free dry) on bone parameters and the relationship between bone breaking strength and bone parameters. Sixty Single Comb White Leghorn hens were used for this study. Hens were euthanized by CO2 gas, and the right tibia and femur were collected. The bones were divided into 3 treatment groups: fresh, dry, and fat-free dry. There were no significant differences in fresh weight, bone volume, dried weight, ash weight, and ash concentration of tibia and femur among the treatments. However, fresh tibia (24.13 kg) exhibited more bone breaking strength compared with the dried (9.90 kg) and fat-free dried bones (7.41 kg) (P < 0.05). The bone breaking strength (20.97 kg) of fresh femur was also significantly higher than the dried (9.22 kg) and fat-free dried femurs (6.94 kg). The bone breaking strength of the fresh bone was highly correlated with dried weight, ash weight, and ash concentration, whereas that of the fat-free dried bone was poorly correlated with the other bone parameters. The results indicate that fresh bone gives better bone breaking strength correlated to the other bone parameters than dry or fat-free dry preparation.

Animals↗

PubMed2004

Utilization of the nitrate reductase enzymatic pathway to reduce enteric pathogens in chickens.

Previous reports have shown that some bacteria, including Salmonella, use a dissimilatory nitrate reductase enzyme pathway (NREP) in anaerobic environments. This enzyme reduces nitrate to nitrite and has been shown to cometabolize chlorate to cytotoxic chlorite. The present investigations were performed to evaluate the susceptibility of a competitive exclusion culture (CE) to the experimental chlorate product (ECP). A commercially available CE product was evaluated for its nitrate reductase activity and therefore its chlorate sensitivity. Individual isolates (in triplicate) were cultured in 10 mL of Viande Levure broth containing 5 mM sodium nitrate or 10 mM sodium chlorate. Bacterial growth (optical density at 625 nm) was measured and 1-mL aliquots were removed concurrently for colorimetric determination of nitrate content at 0, 3, 6, and 24 h. Of the 15 different facultative strains, 11 had slight NREP utilization, 3 had moderate NREP utilization, and the remainder were NREP negative (with slight and moderate NREP utilization: >0.1 to <1.0 mM and >1.0 mM nitrate used within 6 h, respectively). Of the obligate anaerobes evaluated, 3 had slight NREP utilization and the remainder were NREP negative. In vivo studies utilizing both products (CE and ECP) in a horizontal transmission challenge model (seeders + contacts) showed significant reductions in Salmonella from 5.37 to 1.76 log10 cfu/g and 3.94 to 0.07 log10 cfu/g, respectively. The combined effect of the CE culture and an ECP are effective in killing these food-borne pathogens.

Animal Husbandry↗

PubMed2004

Evaluation of immunosuppressants and dietary mechanisms in an experimental disease model for necrotic enteritis.

Clostridium perfringens (CP) is the etiologic agent of necrotic enteritis (NE). Clinical signs of this disease include depression, decreased appetite, diarrhea, and severe necrosis of the intestinal tract. Understanding the disease progression of NE has been difficult due to its complexity and the involvement of multiple factors (dietary components, immunosuppression, and mechanical irritation of the gut) that appear to contribute to this syndrome. In the present investigation, day-of-hatch broilers were fed a 55% wheat diet and randomly assigned to 1 of 8 groups. Treatments included positive control (CP challenge only), commercial coccidia vaccine (CCV), commercial bursal disease vaccine (CBDV), or the combination of CCV and CBDV, and an appropriate negative control for each (vaccinated and not challenged). Challenged treatment groups received 10(7) cfu of CP twice daily. When compared with controls, broilers in each treatment group had increased (P < or = 0.05) lesion scores, with mean scores of 1.05 and 2.05 in the CP and CBDV + CP treatments, respectively. When compared with controls, the incidence of CP increased (P < or = 0.05) in all treatment groups (73 and 100% in the CCV + CP and CBDV + CP treatment groups, respectively). Compared with controls, percentage mortality increased (P < or = 0.05) from 2% to 26 and 34% in the CP and CBDV + CP treatment groups, respectively. Results of this study indicate that the methodology used provides a good model for studying NE.

Animal Feed↗

PubMed2004

Aflatoxin-induced toxicity and depletion of hepatic vitamin A in young broiler chicks: protection of chicks in the presence of low levels of NovaSil PLUS in the diet.

Aflatoxin contamination of foods and livestock feeds is an ongoing problem. In this research, NovaSil PLUS (NSP), a calcium montmorillonite clay that is commonly used as an anticaking agent in feeds, was evaluated for its ability to bind aflatoxin B1 (AfB1) in vitro and to prevent the onset of aflatoxicosis and vitamin A depletion in broiler chicks in vivo. Isothermal analyses were conducted with NSP and AfB1 to quantitate and characterize critical sorption parameters at equilibrium, i.e., ligand saturation capacities, affinity constants, and thermodynamics of the sorption process. In vitro results indicated that AfB1 was tightly sorbed onto the surface of NSP, which provided a high capacity and high affinity for the ligand. Thermodynamics favored sorption of AfB1 to NSP. The process was exothermic and spontaneous with a mean heat of sorption equal to approximately -50 kJ/mol, suggesting chemisorption (or tight binding). In addition to the in vitro studies, the effectiveness of NSP as an aflatoxin enterosorbent to attenuate the onset of aflatoxicosis in broiler chicks was determined at 3 different inclusion levels in the diet (0.5, 0.25, and 0.125%). NSP alone was not toxic to chicks at a level as high as 0.5% in the total diets (based on body and organ weights, feed intake, and hepatic vitamin A levels). NSP in the diet significantly protected chicks from the effects of highlevel exposure to aflatoxins (i.e., 5 mg/kg) and preserved hepatic vitamin A levels, even at lower dietary intake of clay.

Aflatoxins↗

PubMed2004

Comparison of zinc acetate and propionate addition on gastrointestinal tract fermentation and susceptibility of laying hens to Salmonella enteritidis during forced molt.

Feed deprivation is the most common method used to induce molting and stimulate multiple egg-laying cycles in laying hens for commercial egg production. Unfortunately, an increased risk of Salmonella enteritidis (SE) colonization may result from the use of this method. Methods to stimulate multiple egg-laying cycles without increasing the risk of SE are needed. In each of 3 experiments, hens over 50 wk of age were divided into groups of 12 and placed in individual laying cages. One week before dietary changes, hens were put on an 8L:16D photoperiod that continued for the 9-d experimental period. Hens in all treatments were challenged orally with 10(4) cfu of SE on the fourth day. Treatments were full fed hens (nonmolted, NM), nonfed hens (molted, M), a zinc acetate diet (ZAC), and a zinc propionate diet (ZPR). The zinc diets contained 10,000 mg of zinc per kilogram of diet. Body weight losses were significantly higher in the M, ZPR, and ZAC treatments than in the NM treatment. Crop lactic acid decreased more in M, ZPR, and ZAC treatments than in NM hens in trial 2. Crop pH was significantly (P < 0.05) lower in NM hens than in M, ZAC, and ZPR hens in trial 2. Although cecal individual or total volatile fatty acids (VFA), and lactic acid were not significantly (P > 0.05) different between NM hens and M, ZAC and ZPR hens in trial 1, lactic acid was significantly (P < 0.05) higher in NM hens than in M, ZAC and ZPR hens (trial 2), and cecal total VFA were lower in M hens than in NM, ZAC and ZPR hens (trial 3). Colonization of SE in the crop and ceca was higher in the M and ZPR hens (trials 1 and 2). Liver, spleen, or ovary invasion by SE was higher in the M and ZPR hens (trials 1 and 2) than in NM hens. At the zinc concentration used in these studies, the zinc dietary regimens may be effective for reducing the risk of SE during induced molt.

Animals↗

PubMed2004

Review on the role of dietary zinc in poultry nutrition, immunity, and reproduction.

Zinc is an important nutrient in animal metabolism. In poultry, zinc serves not only as a nutrient but can also be used as a dietary supplement to manipulate the reproductive system of the bird. This article summarizes the general biochemistry, physiology, and nutritional aspects of zinc metabolism to provide a brief overview on what is known regarding zinc. The potential role of zinc in poultry immune response, Salmonella infection, and molting are emphasized.

Animal Nutritional Physiological Phenomena↗

PubMed2004

Using a feed-grade zinc propionate to achieve molt induction in laying hens and retain postmolt egg production and quality.

A commercial-feed-grade form of zinc propionate was examined as a potential feed amendment at a concentration of 1% zinc to induce molt in 90-wk-old hens. Dietary treatments consisted of 4 treatment groups of 28 birds each randomly assigned to either (1) molted conventionally by feed withdrawal, (2) 1% zinc as Zn acetate, (3) 1% zinc as Zn propionate, or (4) nonmolted control for 9 d. Ovary weights of hens fed Zn acetate or Zn propionate were not significantly different from each other, but hens fed Zn acetate or Zn propionate were significantly (p<0.05) lighter than the ovary weight of nonmolted control hens. Zinc concentrations in the kidney and liver were significantly (p<0.05) increased in both Zn acetate- and Zn propionate-molted hens when compared to either nonmolted control-fed hens or feed-withdrawal molted hens. Over the entire 3-mo postmolt period, there were no significant differences in interior or exterior egg qualities among the four treatments. Egg production of hens fed Zn acetate was significantly lower than feed-withdrawal hens, Zn propionate-fed hens, or nonmolted control hens (p<0.05). The data of the current study demonstrated that feeding a feed grade of Zn propionate (1% Zn)-supplemented diet can induce molt and retain postmolt egg quality and production comparable to hens molted by feed withdrawal.

Animal Feed↗