Influence of hen age and molting treatments on shell egg exterior, interior, and contents microflora and Salmonella prevalence during a second production cycle.

The objective of this study was to determine if increasing hen age and 3 different molting treatments influenced the total microflora counts or the prevalence of Salmonella spp. on the exterior of the egg shell, within the interior shell, or in the contents. Eggs from Hy-Line W-98 and Bovans White layer strains were sampled approximately every 28 d from 70 to 114 wk of age, with the molting period from 66 to 70 wk of age. Layers were utilized from the 35th North Carolina Layer Performance and Management Test and managed under identical husbandry practices. This study consisted of nonfasted, nonmolted, and feed-restricted treatments with the use of 135 eggs per layer strain, for a total of 270 eggs sampled per period. The exterior, interior shell, and contents were spiral plated onto plate count agar to calculate the total aerobic counts. Additional preenrichment, enrichment, conformational, and biochemical procedures were performed to test for the presence of Salmonella spp. Hen age and molting treatment significantly (P < 0.05) affected the microbial loads on all 3 egg components. Exterior, interior, yolk, and albumen counts increased during the molt period to as much as 1 log unit higher than the highest countable plate, which was 10(5). Exterior, interior, and contents counts significantly increased (P < 0.05) during period 15, with a significant increase (P < 0.05) in the interior also in period 14, and in the contents in periods 14 and 17. There were a total of 360 egg pools, and of those, 4 were positive Salmonella samples. Both the interior and exterior shell components and 2 of the 3 molting treatments had positive samples. Of these positives, 4 were confirmed as Salmonella Braenderup. Three positives were associated with the interior component, whereas 1 positive was associated with the exterior shell component. Three of the 4 samples were related to the nonfasted treatment, whereas the remaining positive was found in the non-molted treatment.

Effects of injected gluconeogenic supplementation on the performance of broilers from young breeders.

Previous research has shown that administering carbohydrates to late-term embryos increases chick hatching weight and liver glycogen content and that supplementing broiler chicks from young hens at day of hatch with subcutaneously injected hydrolyzed casein and thiamine enhances their early performance. It was hypothesized that other practical and readily available gluconeogenic energy sources, including hydrolyzed casein, may similarly be given to hatchlings from immature breeder hens to increase the availability of liver glycogen reserves and augment growth. In addition to physiological saline (sham) and hydrolyzed casein treatments, 2 other treatments containing practical gluconeogenic energy sources (chicken egg crude albumin or albumin hydrolysate) were tested in the current study using hatchlings that were subsequently provided adequate brooding and nutrition. Added biotin was included in the crude albumin treatment. There were no treatment effects on mortality, BW gain, feed or water consumption, feed conversion, body temperature, hematocrit, plasma refractive index, relative liver weight, or liver glycogen content at any of the ages or age intervals examined through d 16 posthatch. These results suggest that under proper brooding conditions and timely feed provision, growth is not facilitated by injected casein hydrolysate, chicken egg crude albumin, or chicken egg albumin hydrolysate during the early transition from fat to carbohydrate-based nutrient uptake in posthatch chicks from young breeder hens.

The physiology of induced molting.

The initiation of seasonal feather molting in wild avian species frequently coincides with incubation of eggs and brooding of offspring. A period of natural inappetence or anorexia usually accompanies this molt. This is particularly true of the jungle fowl, the wild ancestor of the domestic chicken. Brooding of eggs by the jungle fowl is accompanied by spontaneous anorexia, with little food or water consumed throughout the period of egg incubation. During this time, the reproductive tract regresses, and feather molting is initiated. Selective breeding for a high rate of egg production has blunted the response of the commercial laying hen to exogenous environmental cues and reduced or eliminated the endogenous biological cues that coordinate initiation of seasonal molting. However, commercial layers retain in their physiological repertoire the ability to tolerate prolonged fasting and to undergo a spontaneous regression of the reproductive tract and feather molting. Induction of a coordinated molt, by manipulation of environmental and nutritional cues, or endocrine manipulation, can be used in domestic hens to regress and regenerate the reproductive tract. This improves subsequent egg production and eggshell quality. This process also induces temporary recrudescence of lymphoid tissues and may alter immune function in hens. The process of molting, and the subsequent recovery from the molt, may be viewed as a complex physiological constellation, induced by environmental and nutritional cues, involving endocrine systems, reproductive tissue structure and function, lymphoid structure, and immune function.

The expression of calbindin in chicks that are divergently selected for low or high incidence of tibial dyschondroplasia.

Three experiments were conducted with broiler chicks that were divergently selected for low or high incidence of tibial dyschondroplasia (LTD and HTD, respectively) to determine if the expression of intestinal calbindin-28 kD mRNA and protein differed between the 2 strains. In addition, levels of intestinal vitamin D receptor mRNA and plasma thyroid hormone concentrations were also examined. In experiment 1, LTD and HTD chicks were fed a corn-soybean meal diet that was adequate in all nutrients except cholecalciferol (D3), which was titrated to 5 or 40 microg/kg diet in a completely randomized 2 x 2 factorial arrangement. At 4 and 8 d of age, HTD chicks fed 5 microg of D3/kg of diet had a lower (P < 0.05) expression level of calbindin-28 kD mRNA than the LTD chicks fed the same diet. At 4 and 8 d of age, HTD chicks fed 5 microg of D3 had the lowest intestinal expression of calbindin-28 kD protein. Expression of vitamin D receptor mRNA did not differ for broiler strains at either level of D3 supplementation. In experiment 2, there was no significant difference in the expression of calbindin-28 kD mRNA or vitamin D receptor mRNA between day-of-hatch LTD, HTD, and commercial broiler chicks. Experiment 3 was similar in design to the first experiment except that the birds were fed for 18 d. Calbindin-28 kD and vitamin D receptor mRNA expression levels at 18 d were similar to those observed in experiment 1. Plasma triiodothyronine and free-triiodothyronine concentrations were greater for LTD chicks, regardless of dietary D3 supplementation levels. These results suggest that divergent selection of broilers for LTD or HTD alters the physiological response to nutritionally inadequate levels of dietary D3.

Body weight and semen production of broiler breeder males as influenced by crude protein levels and feeding regimens during rearing.

An appropriate dietary CP level and feeding regimen during rearing is considered important for controlling BW and improving semen production in broiler breeder males. A total of 640 day-old broiler breeder male chicks of two commercial strains (A and B) received treatments of a factorial arrangement of two CP levels (12 and 16%) of corn-soybean grower diets and two feeding regimens [changing feed to a grower diet from the standard broiler starter at 0.45 and 0.68 kg BW and then skip-a-day feeding]. Four- to 28-wk BW differed between CP levels during rearing, with heavier BW on the 16% CP diet than on the 12% CP diet in spite of isocaloric feed intake. Strains did not show a significant difference in BW prior to 40 wk of age. Feed restriction initiated at 0.45 or 0.68 kg BW had no effect in controlling BW after 4 wk of age. Uniformity of BW did not differ between CP levels. Semen volume was greater on the 12% than on the 16% CP diet from 28 to 36 wk of age. Semen concentration was not affected by CP levels, feeding regimens, or strains. Spermatozoa per ejaculate from 28 to 52 wk of age was correlated negatively with 8- to 20-wk BW. This negative relationship was attenuated with age, until at Week 46 or later spermatozoa per ejaculate was associated positively with BW after sexual maturity. No difference in percentage of males in semen production was noted between strains, CP levels, or feeding regimens. In brief, diet changes at 0.45 or 0.68 kg BW were not important in improving semen production, whereas the low CP diet (12%) had advantages in semen production over the high CP diet (16%). A negative relationship existed between semen production and BW during rearing; however, continued BW gain after sexual maturity was necessary to optimize semen production, especially during the late breeding period.

Effect of exposure to low level lead on growth and growth hormone release in rats.

This study was undertaken to examine the effect of exposure to low level lead on growth and growth hormone (GH) release. Female pups exposed to lead beginning in utero were smaller than controls on postnatal day 7 (P = 0.06). There was no corresponding effect in males. No overall differences in body weights were detected in either sex with respect to treatment effect. No differences in food or water intake were observed at any time. Pituitaries from 49-day-old lead-treated pups responded to in vitro incubation with growth hormone releasing factor (GRF) with a smaller increase in GH release than those from control pups (P = 0.08). In the case of the dams, lead did not affect body weight, body length, food consumption or pituitary responsiveness; however, water consumption was significantly increased in the lactating dam (P < 0.05). Interestingly, blood lead content in 5-day-old pups (43.3 +/- 2.7 micrograms/dl) exposed to lead in utero was more than twice that of their 49-day-old litter-mates (18.9 +/- 0.7 micrograms/dl). At 49 days blood lead levels in female pups (19.94 +/- 0.8 micrograms/dl) were significantly higher than those of male pups (17.00 +/- 1.1 micrograms/dl). Maternal blood lead levels on the same day averaged 22.7 +/- 2.5 micrograms/dl. This study suggests that exposure to a low level of lead can reduce pituitary responsiveness to a hypothalamic stimulus. In addition, the data reinforce the importance of considering age and sex when evaluating the toxic effects of lead.

Antiorthostatic suspension as a model for the effects of spaceflight on the immune system.

We describe the use and appropriateness of antiorthostatic suspension in immunological investigations. This manuscript describes the model and discusses how well data obtained by using the model correlate with spaceflight data. This review concludes with some suggestions for future experiments using antiorthostatic suspension.

Research note: maintenance of duodenum weight during a molt induced by dietary zinc in a low-calcium diet.

The duodenal loop was excised from hens that had been induced to molt by a low-calcium diet containing 2,800 ppm zinc in the form of zinc sulfate heptahydrate. This was compared to that of hens pair-fed a layer diet. In Experiment 1, hens exhibited an increased duodenum weight after receiving the zinc diet for 14 days but no differences remained 14 days later. In Experiment 2, increased duodenum weight was noted after 4 days on the zinc diet and this persisted through 10 days. This greater tissue weight was observed whether expressed on a wet or dry weight basis. Thus, there was a persistency of tissue mass. The duodenum does not regress during a zinc-induced molt as it does during a fast-induced molt.

Spaceflight alters immune cell function and distribution.

Experiments were carried out aboard COSMOS 2044 to determine the effects of spaceflight on immunologically important cell function and distribution. Control groups included vivarium, synchronous, and antiorthostatically suspended rats. In one experiment, rat bone marrow cells were examined in Moscow, for their response to recombinant murine granulocyte/monocyte colony-stimulating factor (GM-CSF). In another experiment, rat spleen and bone marrow cells were stained in Moscow with a variety of antibodies directed against cell surface antigenic markers. These cells were preserved and shipped to the United States for analysis on a flow cytometer. Bone marrow cells from flown and suspended rats showed a decreased response to granulocyte/monocyte colony-stimulating factor compared with bone marrow cells from control rats. Of the spleen cell subpopulations examined from flown rats, only those cells expressing markers for suppressor-cytotoxic T- and helper T-cells showed an increased percentage of stained cells. Bone marrow cells showed an increase in the percentage of cells expressing markers for helper T-cells in the myelogenous population and increased percentages of anti-asialo granulocyte/monocyte-1-bearing interleukin-2 receptor-bearing pan T- and helper T-cells in the lymphocytic population. Cell populations from rats suspended antiorthostatically did not follow the same pattern of distribution of leukocytes as cell populations for flown rats. The results from COSMOS 2044 are similar, but not identical, to earlier results from COSMOS 1887 and confirm that spaceflight can have profound effects on immune system components and activities.

Effect of spaceflight on natural killer cell activity.

The effects of spaceflight on immune cell function were determined in rats flown on COSMOS 2044. Control groups included vivarium, synchronous, and antiorthostatically suspended rats. The ability of natural killer cells to lyse two different target cell lines was determined. Spleen and bone marrow cells obtained from flight rats showed significantly inhibited cytotoxicity for YAC-1 target cells compared with cells from synchronous control rats. This could have been due to exposure of the rats to microgravity. Antiorthostatic suspension did not affect the level of cytotoxicity from spleen cells of suspended rats for YAC-1 cells. On the other hand, cells from rats flown in space showed no significant differences from vivarium and synchronous control rats in cytotoxicity for K-562 target cells. Binding of natural killer cells to K-562 target cells was unaffected by spaceflight. Antiorthostatic suspension resulted in higher levels of cytotoxicity from spleen cells for 51Cr-labeled K-562 cells. The results indicate differential effects of spaceflight on function of natural killer cells. This shows that spaceflight has selective effects on the immune response.

Effect of microgravity modeling on interferon and interleukin responses in the rat.

Rats were placed in whole-body harness suspension in three configurations: antiorthostatic hypokinetic/hypodynamic suspension (AAH) to induce headward body fluid redistribution and unload the limbs, orthostatic hypokinetic/hypodynamic suspension (OHH) to unload the limbs without fluid redistribution, and harness restraint (HR) to produce the restraint stress of the model without fluid redistribution or musculoskeletal disuse. AHH and OHH suspension transiently increased interferon-gamma (IFN-gamma) production in response to the mitogen concanavalin A. Harness restraint alone did not affect IFN-gamma response. However, both suspension modeling and harness restraint caused a transient reduction in interleukin-1 (IL-1) and IL-2 responses to mitogen. This suggests that factors associated with musculoskeletal unloading affected IFN-gamma responses, while IL-1 and IL-2 responses were affected by the physiological stress of restraint.

Effects of spaceflight on levels and activity of immune cells.

Experiments were carried out on cells from rats that had been flown on Soviet Biosputnik Cosmos 1887 to explore the effects of spaceflight on immune responses. Rat bone marrow cells were examined for their response to colony stimulating factor-M. Rat spleen and bone marrow cells were stained with antibodies directed against cell surface antigenic markers. The results of the studies indicate that bone marrow cells from flown rats showed a decreased response to colony stimulating factor. There was a higher percentage of spleen cells from flown rats staining positively for pan-T-cell, suppressor-T-cell and interleukin-2 receptor cell surface antigens. A small increase in the percentage of cells staining positively for helper-T-cell antigens was also noted. In addition, a higher percentage of cells that appeared to be part of the myelogenous population of bone marrow cells from flown rats stained positively for surface immunoglobulin.

Characterization of different hematological responses during molts induced by zinc or fasting.

Single Comb White Leghorn hens were induced to molt by complete fasting for 11 days (FAST) or feeding a layer ration that contained 20,000 ppm zinc as zinc oxide for 11 days (ZINC). In both cases hens lost approximately 30% of their initial body weight. A control (CON) group was maintained. At 4, 8, 12, 18, and 42 days after initiation of the treatments, total erythrocyte numbers (TRBC), percent packed cell volume (PCV), mean corpuscular volume, hemoglobin (Hb), mean corpuscular hemoglobin (MCHb), and mean corpuscular hemoglobin concentration (MCHC) were determined. Erythrocytes were characterized as reticulocytes, intermediate Stage VII erythrocytes, or mature Stage VIII erythrocytes. The FAST hens exhibited significantly increased PCV through 18 days, which was not exhibited by ZINC hens. The FAST treatment increased TRBC on Days 8 and 12 and decreased TRBC on Day 42 while ZINC decreased TRBC on Day 4 and increased TRBC on Day 12. The FAST hens exhibited decreased Hb on Day 42, as reproduction resumed. Both ZINC and FAST hens exhibited decreased MCHb and MCHC on Day 12. Percentages of reticulocytes were decreased at Day 4 by FAST and increased at Days 8 and 18 by ZINC. Stage VII erythrocytes were decreased on Days 4 and 12 in FAST hens whereas ZINC hens exhibited a decrease on Day 4 and an increase on Days 8 and 18. Concomitantly, FAST hens exhibited an increase in Stage VIII erythrocytes on Days 4 and 12, whereas an increase on Day 4 and decreases on Days 8 and 18 were observed in ZINC hens.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of lighting program and nutrition on feather replacement of molted single comb White Leghorn hens.

This experiment concerned the induced molt of 320 60-wk old Single Comb White Leghorn hens placed two per cage in two adjoining sections of a light-tight, fan-ventilated poultry building. Treatments compared were: 1) lighting program: Washington (WSU) vs. North Carolina (NCSU). The WSU program used 8 h light/day for 28 days beginning 7 days before fast. The NCSU program used continuous light for 7 days prior to fast, followed by 12 h light/day for 21 days. The light portion of the photoperiod was then increased in steps in both treatments to 16 h. 2) Molt diet: cracked corn (CC) vs. 16% protein molt ration (MR) for 14 days. 3) Laying diet. A 14% protein mash calculated to contain .60% or .65% total sulfur amino acids (TSAA) or ascorbic acid (AA) at 0 or 50 ppm added to the laying mash. Day 1 was designated as the first day of photoperiod modification. Primary and secondary feather loss and subsequent primary feather growth were all significantly increased by the WSU light program at 56, 84, and 112 days. Total and average growth of new primaries was significantly increased by MR at 56 days and total primary feather growth by .65% TSAA at 112 days. No effects due to AA were observed. Photoperiod had the greatest effect on molt per se, with MR and .65% TSAA increasing early and late growth, respectively.

Effect of lighting program and nutrition on reproductive performance of molted single comb White Leghorn hens.

Two adjoining rooms in a light-tight, fan-ventilated, insulated house were used for a study involving 320 Single Comb White Leghorn hens, 60 wk of age, placed two per cage. These hens were subjected to an induced molt which compared two lighting programs, two molt rations, two levels of total sulfur amino acids (TSAA), and two levels of ascorbic acid (AA) in a factorial arrangement. There were four treatments. Treatment 1 compared the Washington lighting program (WSU), consisting of an 8-h light photoperiod for 28 days beginning 7 days before fast with the North Carolina program (NCSU), consisting of a 24-h light photoperiod for 7 days prior to fast followed by 12 h light/day for 21 days. After 28 days, light duration was increased to 16 h/day in stages for both programs. Treatment 2 consisted of feeding cracked corn (CC) or 16% protein molt ration (MR) for 2 weeks: Treatment 3, feeding of 14% layer mash with either .60% or .65% TSAA; and Treatment 4, addition of either 0 or 50 ppm AA to the 14% layer mash. After molting, egg production was increased in the NCSU lighting program and .65% TSAA treatments. Feed conversion was improved by the NCSU lighting treatment. Deaths were fewer in diets with 50 ppm AA. Egg weight, specific gravity, and shell weight were not affected by any treatment. A significant light X molt diet interaction occurred due to better performance of MR birds compared with CC birds in the NCSU lighting program, whereas on the WSU lighting program, CC produced better performance. These data indicated that combining features of various molt programs may not produce optimum results.

Postmolt performance of laying hens molted by high dietary zinc, low dietary sodium, and fasting: egg production and eggshell quality.

Single Comb White Leghorn (SCWL) hens, 65 weeks of age, were assigned to one of four dietary treatments: fasting to a body weight loss of 34% (FAST), administration of a diet containing less than or equal to 500 ppm sodium for 42 days (Lo Na), administration of a diet containing 20,000 ppm zinc for 10 days (Hi Zn), and a control (CON) diet. The hens were subjected to two photoperiod treatments, those receiving 17 hr (17-hr) of light per day throughout the 32-week experiment and those restricted to 8 hr of light per day for the first 42 days followed by a .5 hr/day increase until 17 hr was reached. Egg production and mortality were recorded daily. Feed consumption, feed conversion, and livability were determined weekly. Beginning on Day 56, eggs were collected at 28-day intervals for determination of egg weight, egg specific gravity, and shell weight. During the molt phase (1 to 6 weeks), the 17-hr light day significantly increased egg production, feed consumption, and decreased feed conversion (kg/doz) across all groups when compared with the 8-hr light/day treatments, but FAST treatments consumed identical amounts under both light treatments. From 7 to 32 weeks during the postmolt phase, egg production was significantly increased and feed conversion decreased by the FAST and Hi Zn treatments relative to CON, Lo Na treatment was intermediate. Feed consumption was significantly higher for the FAST treatment. Overall, there were not significant effects on egg production, feed consumption, and feed conversion.(ABSTRACT TRUNCATED AT 250 WORDS)

Cellular changes in the spleen during an induced molt.

Agranulocytes proliferated in spleens of molted hens and both leucocytic and erythrocytic cells exhibited decreased numbers of pyknotic nuclei. These changes were confined to the period when the reproductive tract regressed. It was concluded that there is a relationship between the physiological status during an induced molt and the cellular population of the spleen.