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.

Potential of alfalfa as an alternative molt induction diet for laying hens: egg quality and consumer acceptability.

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.

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.

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.

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.

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.

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.

Effect of storage condition on bone breaking strength and bone ash in laying hens at different stages in production cycles.

This study was conducted to determine the effects of refrigeration and frozen storage on tibia breaking strength (kg/g) and tibia ash (%) in bones obtained from hens of different ages. A total of 75 Single Comb White Leghorn hens were divided into three equal groups according to age (72, 80, and 92 wk of age). Both tibias of each hen were harvested and immediately defleshed. The tibias from each hen were randomly assigned to either 1 d of refrigeration or 7 d of frozen storage. Tibia breaking strengths were determined using an Instron Universal Testing Machine with 50-kg-load cell at 50-kg-load range with a crosshead speed of 50 mm/min. Tibia ash weights were determined by ashing for 24 h at 615 degrees C. Bone breaking strength in 72 wk of age hens was significantly (P < 0.05) higher in refrigerated tibias (2.48 kg/g) than those in frozen storage (1.75 kg/g). However, there was no difference (P > 0.05) for bone ash (percentage of tibia ash) in all three groups between refrigerated storage (72 wk: 38.840%, 80 wk: 46.40%, 92 wk: 46.99%) and frozen storage (72 wk: 39.12%, 80 wk: 44.88%, 92 wk: 45.35%). This study indicated that frozen storage only influenced assessment of bone strength in 72-wk-old laying hens but could be used for sample storage of bones from older hens.

Consumer poultry meat handling and safety education in three Texas cities.

Shifting demographics, increased poultry consumption and a general ignorance concerning food safety measures provide the potential for increased foodborne illness. In order to determine where food safety educational efforts would be most effective and the needed content of the messages, a survey addressing poultry preparation, storage and thawing methods, and sources of food safety education was constructed and distributed in supermarkets in three Texas urban centers. Between 60 and 67% of consumers prepared poultry once or twice per week. A majority of Hispanics (57%), minors (79%) and uneducated (55%) respondents thaw poultry outside of the refrigerator, either on a counter, in a microwave, or in a sink of water. A majority of Caucasians receive food safety information from either magazines (52%) or television (60%), whereas minors receive education mainly from the educational system (57%) or family (71%). Through increased education in these areas, good food safety habits may be increased in those target groups, especially the next generation of consumers.

The effects of post-mortem electrical stimulation and muscle tensioning in two broiler muscles.

High voltage post-mortem electrical stimulation (ES) and muscle tensioning during chilling (MT) were applied to broiler carcasses to determine the effect of this combined treatment on absorbance ratio (R- value), sarcomere shortening, and myofibrillar fragmentation in muscles of differing fiber type composition. The ES + MT treatment resulted in a greater effect on these three parameters in the posterior Latissimus dorsi (predominantly twitch-glycolytic) than in the anterior L. dorsi (predominantly tonic-oxidative). The differing responses of these two muscles to the ES + MT treatment combination may be useful in explaining the effects of rigor-accelerating treatments such as ES + MT in avian and mammalian muscles.

Concurrent identification of calpains I and II from chicken skeletal muscle.

A single anion-exchange column resolved two peaks of calcium-activated neutral protease activity, corresponding to the two calpain forms chicken skeletal muscle. Multiple columns have previously been needed to resolve the two isoforms from avian tissue. Calcium requirement assays confirmed one form to require approximately 100 microM Ca2+ for half-maximal activity, while the other required approximately 500 microM Ca2+. Electrophoresis revealed that the enzymes were not purified to homogeneity.

Fragmentation, tenderness, and post-mortem metabolism of early-harvested broiler breast fillets from carcasses treated with electrical stimulation and muscle tensioning.

Two 72-bird trials were conducted to determine the effects of 15 s electrical stimulation (ES) (440 V, 2 s on and 1 s off) and prechill muscle tensioning (MT) on fragmentation, tenderness, and post-mortem metabolism of early-harvested (1 h post-mortem) broiler breast fillets. Compared with controls, all treatments increased sarcomere length and decreased shear value. Electrical stimulation reduced muscle pH values. Histological examination of samples from fillets harvested early and then aged 24 h revealed that all treatments increased fiber disruption compared with controls. Both fragmentation and excessive sarcomere shortening prevention were important to the improvement in fillet tenderness associated with the ES and MT treatments.