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Hy-Line Brown, W36, and W98 hens were housed for 2 wk at 22°C, exposed to 35°C heat stress (HS) for 2 wk, and had 2 wk of recovery at 22°C. Production parameters (egg production, feed intake, egg quality measures, and mortality), acid-base status (pH, pCO2, HCO3−, pO2), intestinal calcium uptake, and expression of hepatic heat shock protein-70 were measured. All production parameters except mortality were reduced by HS in all 3 strains. There were strain × temperature interactions for egg production, feed intake, shell thickness, specific gravity, and yolk weight, with the least severe reduction in W98 hens. The W36 hens were intermediate for egg production and feed intake, and the Brown and W36 hens were equivalent for shell thickness, specific gravity, and yolk weight. There were no interactions for egg, albumen, and shell weights, Haugh units, and intestinal calcium uptake, and all were reduced by HS. Blood pH and pCO2 were reduced by HS, and hepatic heat shock protein-70 was increased, with no differences among strains. Mortality rates during HS were 16, 8, and 4% for the Brown, W98, and W36 hens, respectively, but were not subjected to statistical analysis. The results suggest a mechanism in the W98 bird that appears to confer an advantage during HS with regard to egg production.

Hy-Line W-36, W-98, and Brown hens lay approximately the same number of eggs/hen housed to 80 wk; however, little is known about differences in performance during heat stress (HS). Two experiments were performed. The first experiment evaluated intestinal calcium uptake (CaT), heat shock protein-70 (HSP70) liver expression, and endocrine status in the 3 strains under heat stress in response to 1 h of transient exposure to high temperature before onset of 18 h of HS. The second experiment evaluated the differences between W-36 and W-98 in acid-base status observed at 2 different ambient temperatures. The HSP70 and CaT data were analyzed as a completely randomized design (CRD) using a 3 x 2 factorial with strain as a 1 factor and preexposed and control treatments as the other. Estrogen and progesterone data were analyzed as a CRD using repeated measures in a 3 x 2 x 2 factorial with strain as a the first factor, preexposure and control treatments as the second factor, and phase of blood collection as the third factor. The data of the second experiment were analyzed as a CRD using repeated measures in a 2 x 2 x 2 factorial with strain, temperature, and phase of blood collection as the factors. The method applied in both experiments was based on the mixed model (SAS). The results show a strain effect, with the higher CaT in the W-36. The results indicated that transient exposure to HS did not induce changes in HSP70 liver expression. In the second experiment, the blood gas values did not differ between strains, except for the partial pressure of CO(2), in which the values at 22 degrees C are higher for the W-36. At 38 degrees C, there was an increase in blood pH and a reduction in HCO(3)(-) in both strains. The results indicate that endocrine, acid-base status, and Ca homeostasis represent important factors to be considered in assessing genetic differences for thermotolerance.

The Poultry Science Association (PSA) leadership has created its first comprehensive 5-year strategic plan (2006 to 2010) as a guide to the organization's growth and development. As societal concerns about animal agriculture increase and as changes in the poultry industry and in universities reduce the numbers of poultry scientists and thus membership in PSA, it became apparent that, to maintain relevance, the PSA needed to undertake a more rigorous and comprehensive review of its assets, areas of weakness, and reasons for being. The strategic planning process provided the lens for organizational analysis and planning. Our new mission for the PSA is to be a global scientific society dedicated to discovery and dissemination of knowledge, generated by poultry research that enhances human and animal health and well-being and provides for the ethical, sustainable production of food. The Association's vision is to be a preeminent global organization of poultry scientists and industry leaders, firmly grounded in scientific endeavors related to the biology and production of poultry. Increased membership diversity will be pursued by recruiting people of varied geographic, gender, cultural, and scientific backgrounds—including health and medicine—leading to a diverse leadership. The PSA will serve as the clearinghouse for poultry science information and provide through its Foundation significant financial support to students and young scientists engaged in poultry science research, teaching, and outreach education. The PSA, in partnership with the Federation of Animal Science Societies (FASS), will be a highly credible, well-respected, powerful force that is able to influence policy makers at governmental levels for the benefit of animal agriculture by delivering sound scientific information. The strategic plan highlights strategic directions to be implemented as well as assessment of progress. It will take the vision, energy, and dedication of PSA leaders and members to ensure that the strategic plan is well implemented, monitored, and altered appropriately, keeping it a living plan of action.

SUMMARY Two corn-soy rations formulated to provide normal ME (2,890 kcal/kg) or reduced ME (2,805 kcal/kg) were combined in a factorial arrangement with or without enzyme (Avizyme 1500) supplementation (ES). These rations were fed for a 15-wk period to 2 strains of Single Comb White Leghorn hens (SCWL) [Babcock B-300 (B) and Hy-Line W-36 (H)] beginning at 25 wk of age. Overall feed intake was significantly affected only by strain not by dietary ME level or ES. Energy level of ration and strain of hen had a significant effect on feed efficiency: a 9-point difference in feed conversion favoring Hy-Line W-36 and a 5-point difference favoring the normal dietary ME (2,890 kcal/kg). Enzyme supplementation significantly affected egg production (EP) differently in each strain. We observed increased EP by Hy-Line W-36 hens on the reduced ME diet with ES, but in the Babcock B-300 hens only those on the normal ME diets with ES had increased EP. Egg weight showed a significant interaction effect of dietary ME supplementation and strain such that the Babcock B-300 hens laid eggs of greater weight when fed normal ME diets compared with eggs from the Hy-Line W-36, which were heavier from hens on the reduced ME diet. Percentage of yolk increased among hens fed the reduced ME diets; yolk percentage of Babcock B-300 eggs was greater than that of eggs from Hy-Line W-36. Roche Color fan score decreased in eggs from hens on the reduced ME diet. Enzyme supplementation had a significant positive effect on protein and calcium retention but no effect on AME or gut content viscosity. Enzyme supplementation also negatively affected phosphorus retention.

Avian shell gland tissue was subjected to Western blot analysis using anti-human estrogen receptor-α antibody H222. Initial attempts to obtain consistent, high-quality blots were unsuccessful because, as it turned out, excessive lipid in tissue preparations interfered with protein separation. Incremental additions of acetone eventually proved to be the critical step in solubilizing lipids and allowing consistent separation of bands on gels. A detailed description of the methodology is presented.

The Morrill Act establishing the land grant university system created public higher education institutions and paved the way for women and racial minorities to access them. Today women are ∼50% of the undergraduate population in animal science (AS) departments at the original land grant state universities, but racial minorities lag far behind, in part because the schools created under the 1890 legislation provided a diversion away from the state universities. Demographic trends from the U.S. Census and the Bureau of Labor Statistics indicate increasing positive growth in nonwhite workforce participation, with concurrent decreases in non-Hispanic male participation; men and women will be nearly equally represented by early in the 21st Century. In the faculties of AS departments, both women and minorities are seriously underrepresented; causative factors underlying this phenomenon are similar. Although, historically, adherence to role stereotypes and divisions of labor explain some of the under-representation, these assumptions do not hold across all economic classes. Other factors contributing to the scarcity of women and faculty of color in AS include assumptions and mechanisms of scientific research itself; the very neutrality and disinterestedness of researchers, inherent in the scientific method, prevent recognition that values and personal biases affect decisions of hiring selections and mentoring effectiveness. We explore the cultural factors that underlie these values and biases that are common not only to agriculture but also to science more broadly.

Older hens in production lay larger but fewer eggs than younger birds, and the incidence of soft and broken shells is greater in older hens than younger. These changes are attributable at least in part to changing hormone profiles and diminished ability of the hen to transport calcium at the duodenum. In further exploration of this relationship, a study was conducted with three ages of Hy-Line W-36 birds: prelay pullets (PL; 19 wk, 0% production), peak-production hens (PP; 29 wk, approximately 93% production), and late-stage hens (LS; 71 wk, approximately 80% production). Hens from the PP and LS groups were palpated for presence of an egg in the shell gland; hens were then euthanized and tissues (kidney, shell gland, hypothalamus) were removed for quantification of estrogen receptor-alpha (ERalpha) populations via immunocytochemical and Western blot analyses. Localization of ERalpha by immunostaining in the shell gland showed differences among age groups; however, no differences were noted in localization of ERalpha between age groups in the kidney and hypothalamus. In both the kidney and the shell gland there was a decrease in the amount of ERalpha, as detected by immunoblotting, in the LS hens compared to PL and PP birds (P < 0.05). The results suggest that failure of calcium regulating mechanisms with age may be mediated at least in part through the reduced populations of estrogen receptors in certain critical tissues.

Reproduction in Japanese quail is primarily regulated by photoperiod. Vasoactive intestinal peptide (VIP) has been suggested as a transducer of environmental information, especially photoperiodic cues, to the hypothalamo-pituitary-gonadal axis. To investigate the possible interaction of VIP and the reproductive (gonadotropin-releasing hormone, GnRH) system, double-immunocytochemical staining for VIP and cGnRH-I was conducted in sexually mature male quail held under a long-day photoperiod (16L:8D; LD) and in sexually quiescent males held under a short-day photoperiod (8L:16D; SD). VIP-immunoreactive (ir) cells were found primarily in three locations: lateral septal organ (LSO) in nucleus accumbens (Ac), ventral hypothalamus, and infundibular area. VIP-ir cells in LSO displayed characteristics typical of cerebrospinal fluid (CSF)-contacting cells, and co-existed with cGnRH-I-ir cells and beaded fibers. In contrast, VIP-ir cells in the infundibular area did not co-exist with cGnRH-I-ir structures. The number of visible VIP-ir cells in the infundibular area of SD males was significantly lower than that of LD males, while the number of visible VIP-ir cells in Ac/LSO was not altered by photoperiod. A cluster of cGnRH-I-ir cells in the caudalmost septal area was heavily innervated by VIP-ir fibers, which appeared to contact cGnRH-I-ir cells directly at this location. Both VIP- and cGnRH-I-ir fibers heavily innervated the external layer of the median eminence (ME). These data suggest that Ac/LSO, the caudalmost septal area, and ME are possible sites of interaction between the VIP and the GnRH systems.

An experiment was conducted with two strains of Leghorn hens, DeKalb Delta (D) and Hisex White (H), to investigate the effect of a commercial poultry enzyme preparation (EZ; xylanase plus protease) on the digestibility of protein, fat, Ca, and P and to determine any changes in the relative size of the digestive tract, gut morphology, and gut viscosity (GV) of birds fed wheat middlings (WM) over an 18-wk period. Three hundred birds (150 birds per strain) were randomly assigned to six diets: Diet 1, control (corn-soybean); Diets 2 and 3, 8% and 16% WM, respectively; Diet 4, 8% WM and 0.1% enzyme (EZ); and Diets 5 and 6, 16% WM and 0.1% and 0.2% EZ, respectively. There were five replicates per diet per strain. At 50 wk, protein digestibility increased significantly with supplementation of EZ, but, at 60 wk, all responses were similar. Protein digestibility was greater in DeKalb Deltas for WM with EZ compared with Hisex on the same treatment. Fat digestibility was greater for Diet 1 than the other diets at 50 wk but showed a similar response at 60 wk. The H strain showed a reduction in fat digestibility with WM diets with EZ. The control diet showed greater Ca digestibility than the other diets at 50 wk but did not differ at 60 wk. Phosphorus digestibility increased significantly for WM diets with or without EZ at 60 wk. Intestinal weight was significantly higher for WM with or without EZ at 50 wk, but was equal to the control diet at 60 wk. At 60 wk, gizzard weights (GW) were also lower in birds fed WM and WM with EZ compared with birds fed the control, but GV was not affected by dietary treatments. Histological observations on jejunum of birds fed WM without EZ showed shortening, thickening, and atrophy of the villi, all of which improved when EZ was included in the diet. Availability of some nutrients in WM diets was improved with supplementation of enzyme. Gastrointestinal (GI) tract and organ size were increased, and gut morphology appeared to be improved.

The paper reviews hypotheses explaining the regulation of food intake in mammals that have addressed specific anatomical structures in the brain. An hypothesis, poikilostasis, is introduced to describe multiple, homeostatic states whereby the regulation of metabolism and feeding occur in birds. Examples are given for both wild and domestic avian species, illustrating dynamic shifts in homeostasis responsible for the changes in body weights that are seen during the course of an annual cycle or by a particular strain of bird. The following neural structures are reviewed as each has been shown to affect food intake in birds or in mammals: ventromedial hypothalamic nucleus (n.), lateral hypothalamic area, paraventricular hypothalamic n., n. tractus solitarius and area postrema, amygdala, parabrachial n., arcuate n. and bed n. of the stria terminalis. Two neural pathways are described which have been proposed to regulate feeding. The trigeminal sensorimotor pathway is the most complete neural pathway characterized for this behavior and encompasses the mechanics of pecking, grasping and mandibulating food particles from the tip of the bill to the back of the buccal cavity. A second pathway, the visceral forebrain system (VFS), affects feeding by regulating metabolism and the balance of the autonomic nervous system. Wild, migratory birds are shown to exhibit marked changes in body weight which are hypothesized to occur due to shifts in balance between the sympathetic and parasympathetic nervous systems. Domestic avian species, selected for a rapid growth rate, are shown to display a dominance of the parasympathetic nervous system. The VFS is the neural system proposed to effect poikilostasis by altering the steady state of the autonomic nervous system in aves and perhaps is applicable to other classes of vertebrates as well.

An existing environmental chamber for short-term indirect calorimetric studies was re-configured for use as a within-chamber recirculation unit with a computerized control and data acquisition system, and modified with an in-chamber humidity control unit to provide 30 to 80% RH. Intake air was pre-conditioned to a specific temperature-humidity state point and delivered at 20 to 50 standard L/min. Data can be collected from the chamber to a computer via an 8 channel amplifying/filtering unit and an analog-digital converter. The computer also controlled the environmental conditions in the chamber. Over a series of “dry” runs (without animals), system error for dry bulb temperature varied from ± 0.2°C to ± 1.1°C, with an average error of 0.4°C. Average moisture production and CO2 errors were 6.5% and 1.4%, respectively, from a series of animal tests. All were within acceptable limits for reliable data generation.

1. 1. Using a 3-factor uniform-precision rotatable central composite design, male turkeys at 5 ages (5–20 weeks) subjected to 5 temperatures (T, 25–40°C) and 5 relative humidities (RH, 40–80%) during 2 h exposure periods were assessed for body temperature (BT), moisture production (MPM), CO 2 production, respiration rate (RR) and heart rate (HR). Prediction equations based on thermal conditions were developed for each physiological response. 2. 2. For the temperature range selected, RH had a stronger effect than T. Maximum RR occurred at lower T and RR was more variable in older, heavier birds. 3. 3. Twenty-week-old birds used compound ventilation in addition to panting, which may have reduced the severity of heat stress and the consequent lack of a significant change in body temperature.

Although no mechanical maintenance and little cost are associated with the trough waterers on chick brooder units, they have many disadvantages. A pressure-regulated nipple unit was designed to replace the trough system on a chick starting battery, and construction and operating costs (maintenance time) of the nipple system were compared with the original trough system. Assessments of water quality and chick performance were also made. A modification of the nipple system was designed to allow water line manipulation and water consumption data collection, although these were not tested. Advantages of the system include reduced labor for cleaning and maintenance, no self-contamination, and easy modification of the lines for water treatments and water consumption data collection. The only disadvantage is cost of the pressure regulators; however, this would be offset within four to seven 3-wk chick trials. For the 3-wk trial conducted in this study with the pressure-regulated nipple-equipped unit and a conventional unit, there were no differences in weight gain, mortality, or feed conversion.

Degradation of the biosphere with the associated loss of biological integrity is the most critical issue facing humankind today. Wildlife damage management expertise is critically needed in addressing this issue head-on from both traditional and non-traditional approaches. The profession offers a unique combination of both wildlife management training and damage management experience, which helps in understanding a variety of conservation perspectives, especially on private land. Because relationships between damage management and sustainability are often not clearly recognized, and because many traditional wildlife damage management activities are criticized as inappropriate or not needed, we suggest a reassessment of our vision for the future of the profession to include biosphere sustainability as a basic guiding principle. Implications could include greater emphasis in some areas and reassessment in others such as prairie dog management. Greater emphasis might be placed on native ecosystems, impacts of invasive exotic species or overabundant native species, fragmented habitats, nest pests, and, particularly, sustainable agricultural issues. A shift toward greater service to biosphere sustainability will bring both rewards and responsibilities. It will also strengthen the relevance of wildlife damage management and enhance the credibility of the profession for the future.

Two experiments with a factorial arrangement of treatments were conducted to determine the effect of inorganic sulfate and sulfur amino acids (SAA) levels on bone mineralization and Ca excretion in broilers from 1 to 21 days of age. Experiment 1 included two levels of Ca (.6 and 1.0%), two sulfate sources [copper sulfate (CuSO4·5H2 O), and potassium sulfate (K2 S4 O)], and three sulfate levels (.024, .034, and .044%). Experiment 2 included two Ca levels (.6 and 1.0%), two CP levels (18 and 22%), and three SAA levels (.93, 1.23, and 1.53%). Body weight gain, feed:gain, feed consumption, and tibia variables were measured in both experiments. In Experiment 2, Ca retention was also assessed. In Experiment 1, birds fed potassium sulfate and .6% Ca gained significantly more weight than birds fed copper sulfate and 1.0% Ca, respectively. As sulfate level increased, tibia ash percentage increased and decreased linearly in birds fed copper sulfate and potassium sulfate, respectively (P

Three experiments were conducted to determine the effect of protein and dietary sorghum tannin levels on weight gain (WG), feed conversion (FC), and pancreas weight (PW) of female turkeys from Day 1 to 12 wk of age. Two protein levels (100 and 85% of NRC, 1984) and five tannin levels (0, .49, .98, 1.47, and 1.96%, expressed as percentage catechin equivalents) in a factorial arrangement of treatments were used in all experiments. Turkeys were fed the dietary treatments from Day 1 to 4 wk, 4 to 8 wk, and 8 to 12 wk in Experiments 1, 2, and 3, respectively. No significant (P > .05) interaction between protein and tannin level was observed for WG, FC, or PW in all experiments. Neither protein nor tannin level had an effect on PW expressed as a percentage of body weight. In all experiments, feeding the suboptimal protein level significantly (P

Heat stress (HS) effects on reproductive and thyroid hormones have been well documented; however, mechanisms of action are not well understood. Two studies were conducted to determine whether HS-induced and hypothyroid-induced effects are similar in the laying hen, with regard to reproductive hormones and vasoactive intestinal polypeptide (VIP)-immunoreactive cells in the hypothalamus. In study 1, thirty 32-wk-old Hy-Line W-36 laying hens, housed at 22 degrees C, were cannulated. On d 0 and then on d 1 to 5 of HS (35 degrees C, 50% RH), a daily blood sample was obtained and assayed for triiodothyronine (T(3)), thyroxine (T(4)), 17beta-estradiol (E(2)), progesterone (P(4)), prolactin (PRL), and VIP, and T(3):T(4)was calculated. On d 0, 1, 3, and 5, livers were obtained for hepatic type I deiodinase mRNA (cDI-1) determination. In study 2, eighty 32-wk-old hens were randomly assigned to 4 treatments of 20 birds each: 1) HS (36.5 degrees C, 50% RH), 2) thiouracil-induced hypothyroidism (HY), 3) HY + T(4) administration, and 4) control (22 degrees C). Beginning on d 1 of the 5-d study, daily blood samples (3.0 mL) were removed and assayed as in study 1. On d 5, brains were removed from 3 hens/treatment and immunoreactivity of VIP cells was determined. In study 1, HS reduced E(2), P(4), T(3) (P = 0.0001), T(3):T(4) ratio (P = 0.0078), and hepatic type I deiodinase mRNA (P = 0.0204) and increased T(4) (P = 0.0013); there was no effect on VIP or PRL. In study 2, HS and HY reduced T(3), T(3):T(4) ratio, and E(2) (P = 0.0001) and increased PRL (P = 0.0045); HS alone decreased P(4) (P = 0.0001). In HY + T(4), plasma E(2) and PRL were similar to control. Vasoactive intestinal polypeptide increased in plasma of HY birds, but there was no effect of HS or HY + T(4). Immunoreactive VIP cells increased (P = 0.0036) in nucleus inferior hypothalami of HS and HY brains. In HY + T(4), VIP immunoreactive cell numbers were similar to control. It appears that HY induced chemically or by HS exerts similar effects on reproductive hormones in the hen; the results suggest involvement of the VIP-PRL pathway even though peripheral blood concentrations were not consistent between studies.

Although most of the poultry science departmental losses occurred during the 1960s, attrition through mergers with animal science units has continued. In the 1980s and 1990s, four departments were merged, leaving only the southeast (from Delmarva to Texas) and a few scattered states elsewhere with intact poultry departments. The loss of departments coincides with areas where the poultry industry is relatively smaller, but even in states with significant industries, departments are threatened. It is suggested that a divergence of program needs between industry and university, precipitated by vertical integration and loss of job opportunities and exacerbated by lack of cooperative planning, has been a contributing factor. The contrast between departmental and industry trends is striking, with university personnel decreasing ~15% since 1984 but with per capita consumption increasing ~20% since 1986 and surpassing been consumption in 1991. Heavily integrated poultry operations have been relying more and more on in-house research and on-the-job training, but long-term efforts in such areas as animal welfare, behavior, and basic or mechanistic research require university participation. Universities and industry must work more closely together in the future to address long-range efforts to the maximum benefit of both.

Plasma progesterone and luteinizing hormone (LH) profiles were obtained during the first ovulatory cycle of heat-stressed (HS, 35 C; n = 24) and unstressed (US, 17 to 27 C; n = 24) hens using 30-min sampling intervals beginning approximately 6 h prior to ovulation. Progesterone levels from HS hens were lower from 6 h [.07 +/- .01 (SE) versus 1.66 +/- .25 ng/mL; P = .008] to predicted ovulation (.06 +/- .006 versus .70 +/- .18 ng/mL; P = .07). Likewise, LH levels from HS hens were lower from 6 h (1.55 +/- .16 versus 3.86 +/- .34 ng/mL; P = .007) to predicted ovulation (1.63 +/- .18 versus 2.50 +/- .27 ng/mL; P = .01). Eggs from HS hens were more often laid early (less than 24 h) than eggs from US hens (71.42 versus 13.33%, respectively; P = .01), but US hens more often laid eggs of a normal oviposition interval length (24 to 26 h) compared with HS hens (73.34 versus 14.29%; P = .0005). The percentage of delayed eggs (greater than 26 h) was not different (US, 14.29 versus HS, 13.37%; P = .75) between the two treatment groups. Basal production of progesterone by dispersed granulosa cells from US hens was 97.62 +/- 16.01 ng/mL. Challenge by LH increased this to 417.50 +/- 53.38 ng/mL (P = .0001). In contrast, basal progesterone secretion by cells from HS hens was 40.25 +/- 6.60 ng/mL (P = .0001) and LH challenge failed to increase progesterone production.(ABSTRACT TRUNCATED AT 250 WORDS)

The objective of the present research was to determine the effects of CO2 as an immobilization agent on turkey meat quality. In the study, two concentrations of CO2 were used, 40 and 60%; electrical stunning served as the control. As compared with electrical stunning, there was a significant (P

Three-beta-hydroxysteroid dehydrogenase (3beta-HSD) is a key enzyme in the pathway that produces progesterone. Hy-Line hens (W36, W98, and Brown) were subjected to mild heat stress [36 degrees C for 24 h (acute heat stress, AHS) or 2 wk (chronic heat stress, CHS)] or maintained at 22 degrees C (thermoneutral, TN). Granulosa cells (GC) from the 3 largest follicles were isolated, dispersed, and incubated with luteinizing hormone (LH), follicle-stimulating hormone (FSH), prolactin (PRL), a combination, or no hormone (control), and then with pregnenolone nitro blue tetrazolium to determine 3beta-HSD activity. Treatment by LH (TN, P = 0.04; AHS, CHS, P0.0001) and by LH+FSH (TN, AHS, CHS, P0.0001) resulted in increased enzyme activity compared with the respective controls. In TN and CHS, LH+FSH increased the activity to a greater extent than LH alone (TN, P = 0.02; CHS, P = 0.0004); in AHS the increase was not significant (P = 0.29). Treatment with FSH, PRL, or LH+PRL decreased (TN, AHS) or had no effect (CHS) on 3beta-HSD activity. In TN and AHS cells, FSH and PRL reduced enzyme activity (P = 0.006 and 0.0580, respectively). When LH was added to PRL, suppression by PRL was mitigated somewhat. When LH and FSH were added to PRL, 3beta-HSD activity in AHS and CHS cells actually increased compared with the respective controls (P = 0.052 and 0.003) but remained below the activity of cells incubated with LH+FSH or LH alone. This suggests that gonadotropic actions of LH and LH+FSH are countered by the antigonadotropic action of PRL and, conversely, that PRL reduces the stimulatory action of LH and FSH. Strain differences in GC response to hormones were observed primarily in the CHS-treated birds; generally, W98 was highest; Browns showed the weakest response, and W36 was intermediate. In earlier studies, HS reduced circulating LH and GC progesterone and 3beta-HSD activity in vitro and increased circulating PRL. The results suggest a mechanism by which reduced activity of 3beta-HSD and progesterone by GC during HS might be explained, particularly with the differences in strains observed.

In the hen, heat stress (HS) disrupts shell calcification and reproductive processes, including hormone synthesis and egg production. Two studies were conducted to investigate palliative effects of exogenous estrogen or dietary vitamin D 3 on Ca homeostasis and reproductive physiology during HS. Study 1: Hy-Line W36 hens were randomly assigned to thermoneutral (TN) or HS treatments and to 1 of 7 estrogen treatments: zero (control) or one Compudose 200 implant given 1, 2, 3, 8, 9, or 10 d before onset of HS. With no implant, HS reduced plasma estradiol (E 2 ) and total Ca absorbed (CaT) by duodenal cells (P < 0.05). In TN hens with implants, plasma E 2 tripled within 24 h (P < 0.05) and remained elevated (P < 0.05) through d 9. In HS hens with implants, plasma E 2 rose 6-fold (P < 0.05) to equal TN+E 2 concentrations and remained elevated through d 10. In TN and HS hens with implants, the rate of Ca absorption (CaTR) and CaT increased dramatically; the responses were quadratic and essentially identical. Study 2: Hy-Line W36 hens were provided diets formulated either according to NRC requirements (NRC, 1994), or with the addition of 22,000 IU/kg vitamin D 3 (+VD hens). A 24-h HS episode was imposed 2 wk after initiation of the dietary regimen. Duodenal samples were collected for Ca absorption assays after the 24-h HS episode. Both CaTR and CaT in +VD hens were approximately 3-fold higher than in hens in the NVD group (P = 0.102). The results lead to the conclusion that exogenous estrogen, high levels of dietary vitamin D, or both, before a HS episode, are efficacious in alleviating at least some of the effects of HS and should be further investigated.

One of the difficulties associated with commercial layer production is the development of osteoporosis in hens late in the production cycle. In light of this fact and because of hens' unique requirements for Ca, many studies have focused on the regulation of Ca and the role of estrogen in this process. The time course of estrogen synthesis over the productive life of hens has been well documented; increased circulating estrogen accompanies the onset of sexual maturity while decreases signal a decline in egg production prior to a molt. Numbers of estrogen receptors decrease with age in numerous tissues. The parallel changes in calcium-regulating proteins, primarily Calbindin D28K, and in the ability of duodenal cells to transport Ca, are thought to occur as a result of the changes in estrogen, and are also reversible by the molt process. In addition to the traditional model of estrogen action, evidence now exists for a possible nongenomic action of estrogen via membrane-bound receptors, demonstrated by extremely rapid surges of ionized Ca in chicken granulosa cells in response to 17beta-estradiol. Estrogen receptors have also been discovered in duodenal tissue, and tamoxifen, which binds to the estrogen receptor, has been shown to cause a rapid increase in Ca transport in the duodenum. In addition, recent evidence also suggests that mineralization of bone per se may not explain entirely the etiology of osteoporosis in the hen but that changes in the collagen matrix may contribute through decreases in bone elasticity. Taken together, these studies suggest that changes in estrogen synthesis and estrogen receptor populations may underlie the age-related changes in avian bone. As with postmenopausal women, dietary Ca and vitamin D are of limited benefit as remedies for osteoporosis in the hen.

The paper reviews hypotheses explaining the regulation of food intake in mammals that have addressed specific anatomical structures in the brain. An hypothesis, poikilostasis, is introduced to describe multiple, homeostatic states whereby the regulation of metabolism and feeding occur in birds. Examples are given for both wild and domestic avian species, illustrating dynamic shifts in homeostasis responsible for the changes in body weights that are seen during the course of an annual cycle or by a particular strain of bird. The following neural structures are reviewed as each has been shown to affect food intake in birds or in mammals: ventromedial hypothalamic nucleus (n.), lateral hypothalamic area, paraventricular hypothalamic n., n. tractus solitarius and area postrema, amygdala, parabrachial n., arcuate n. and bed n. of the stria terminalis. Two neural pathways are described which have been proposed to regulate feeding. The trigeminal sensorimotor pathway is the most complete neural pathway characterized for this behavior and encompasses the mechanics of pecking, grasping and mandibulating food particles from the tip of the bill to the back of the buccal cavity. A second pathway, the visceral forebrain system (VFS), affects feeding by regulating metabolism and the balance of the autonomic nervous system. Wild, migratory birds are shown to exhibit marked changes in body weight which are hypothesized to occur due to shifts in balance between the sympathetic and parasympathetic nervous systems. Domestic avian species, selected for a rapid growth rate, are shown to display a dominance of the parasympathetic nervous system. The VFS is the neural system proposed to effect poikilostasis by altering the steady state of the autonomic nervous system in aves and perhaps is applicable to other classes of vertebrates as well.

Vitamin E (dl-alpha-tocopheryl acetate) was evaluated for its effects on performance, lymphocyte proliferation, and antioxidation in layers during heat stress. In Trial 1, 25, 45, or 65 IU of vitamin E/kg were fed to four replicated pens (five hens/cage) of DeKalb Delta or Hy-Line W-36 per treatment starting at 20 wk of age. At 34 wk of age, hens were heat-stressed at diurnal temperature ranging from 21 C to 35 C for 3 wk. The performances of hens not exposed to heat stress were not influenced by supplemental vitamin E. Supplemental vitamin E did not affect egg production; however, egg mass was greater (P0.05) with supplementation of 65 IU of vitamin E/ kg during heat stress. Egg yolk was significantly increased (P0.04) when hens were fed 45 and 65 lU/kg compared with the control vitamin E level (25 lU/kg). Haugh units were higher (P0.01) for hens fed 65 IU of vitamin E/kg compared to 25 and 45 lU/kg. Lymphocyte proliferative responses to concanavalin A (Con A) and Salmonella typhimurium lipopolysaccharide (LPS) were greater (P0.0001) in hens fed 45 and 65 IU of vitamin E/kg during heat stress. Strain had no effect on any of the parameters measured. In Trial 2, a 2 x 2 factorial was designed to test effects of vitamin C in drinking water (0 and 1,000 ppm) and dietary vitamin E (25 and 65 IU/kg). Eight replications per treatment with four hens per replication cage were heat-stressed at constant temperature of 35 C for 3 wk. Egg production and egg mass were higher when hens were fed 65 IU of vitamin E/kg than when hens were fed 25 lU/kg (81.5 vs. 75.9%, P0.03 and 48.2 vs. 44.6 g, P0.03, respectively). Yolk solids weight for the 65 IU vitamin E/kg group was higher (P0.01) compared to the 25 IU/kg group. ConA and LPS mitogenic responses were greater in hens fed 65 IU of vitamin E (P0.001 or P0.003, respectively) or 1,000 ppm of vitamin C (P0.001 or P0.002, respectively). The combination of 65 IU vitamin E/kg and 1,000 ppm vitamin C showed the highest ConA and LPS mitogenic responses among the treatments. No interaction effects of the two vitamins on production measurements or lymphocyte proliferative responses were observed. TBA values in egg yolk and plasma of hens fed 65 IU of vitamin E/kg were lower (P0.0001) than those of hens that received 25 IU of vitamin E/kg. These results suggest that vitamin E supplementation at 65 IU/kg diet may enhance production, induction of in vitro lymphocyte proliferation by ConA and LPS, and antioxidant properties of egg yolks and plasma of White Leghorn hens during heat stress and that supplementation of 1,000 ppm vitamin C may further enhance in vitro lymphocyte proliferative responses of hens during heat stress.

Studies were conducted to determine hen preference for and stress response to cage type. By using a plywood (1.25 cm) test apparatus with open- and solid-sided compartments and a plexiglass divider at the entrance for controlling passage, birds (n = 20) were evaluated as to their choice of compartment after training and acclimation. For each test, after training, an individual bird was placed in the start box and given 1 min to acclimate before making a choice. The experiment was repeated after rotating the apparatus 180 degrees. In Experiment 1, the open-sided compartment was chosen by 45% of the hens, and the solid-sided compartment by 25% (P = 0.02); 30% chose neither. In Experiment 2, the compartment with open sides was chosen by 70% of the hens, and that with solid sides was chosen by 15% (P = 0.004); 15% chose neither. The length of time required to choose one compartment over the other did not differ in either experiment (P = 0.29; P = 0.76). In Experiment 3, tests were videotaped from 0830 h to 1330 h, and tapes were scored for time spent in each compartment. Birds were observed to spend more time in open- compared with solid-sided compartments (P = 0.02). To assess stress level of birds exposed to each type of enclosure, blood was collected from 24 commercial Hy-Line W36 hens housed long-term in either open (n = 12) or solid (n = 12) cages, and heterophil:lymphocyte (H:L) ratios were determined. Birds in solid cages had higher H:L ratios than did birds in open cages (P = 0.02), indicating a greater stress response. These data would suggest that hens may prefer greater visual access to their surroundings afforded by open cages.

The well-being of commercial laying hens plays an important role in egg production. Behaviors such as pacing, displaced preening, increased aggression, and redirected activities have been associated with stress in poultry. This study was conducted to determine whether two strains of commercial layers, reported to differ in level of excitability, behave differently in two types of commercial cages. DeKalb Delta and Hy-Line W36 hens, 40 to 45 wk of age, were housed six to eight per cage in open or solid-sided cages, at an equal density between cages. For each strain, there were six cages per cage type for a total of 24 cages. In the first five experiments, behavioral data were obtained at a distance of 1 m by instantaneous or scan sampling. These experiments included hen behavior in both types of cages with and without the presence of frustrating or startle conditions. Some significant differences in behavior existed within experiments but not consistently among all experiments. Sampling method did not affect reliability of data collection. Two trials were then conducted to determine whether the length of time to return to normal activity after a startle stimulus is influenced by the cage type or strain. In the first startle experiment, DeKalb hens returned to normal activity more quickly than did Hy-Line hens (P = 0.07); this strain difference was not found when the experiment was repeated. Cage type did not appear to affect the behavior of birds adversely, although neither cage type appeared to confer an advantage. No clear differences were found in behavior by strain or by strain within cage.

A study was conducted to test the effects of wheat middlings (WM) with and without enzyme (xylanase and protease) supplementation on late egg production (EP), egg yields, and egg composition in two strains of Leghorn hens (DeKalb Delta and Hisex White). Six diets were randomly assigned to 300 birds (150 birds per strain) from 42 to 60 wk of age. Diet 1 was a corn-soybean meal control, Diets 2 and 3 had 8 and 16% WM, respectively, Diet 4 had 8% WM with 0.1% enzyme, and Diets 5 and 6 had 16% WM with 0.1 and 0.2% enzyme, respectively. Each dietary treatment was replicated five times per strain. Egg production, feed consumption (FC), feed efficiency (FE), percentage dirty eggs, specific gravity (SP), egg weight (EW), and egg mass (EM) were measured on a weekly basis. Egg components (EC) were measured biweekly and birds were weighed every 4 wk. Egg production was not significantly affected by diet, with averages of 83.7, 85.7, 84.1, 84.2, 82.3, and 84.0% for Diets, 1, 2, 3, 4, 5, and 6, respectively. Strain had a marked effect on FC, with Hisex having higher FC than DeKalb hens. Feed consumption also showed a significant diet by strain effect, being lower for Hisex hens fed diets with enzyme compared to diets without enzyme. DeKalb hens had better FE than Hisex hens, and addition of enzyme to 16% WM improved it further. Strain and diet had a significant effect on EC with higher percentages of albumen and yolk for diets with enzyme and for DeKalb hens. Percentage shell was lower for DeKalb hens than for Hisex hens but was not affected by diet. There was also a significant increase in EW for Diets 4 (63.1 g), 5 (63.8 g), and 6 (63.2 g) compared to Diets 1 (62.1 g), 2 (62.4 g), and 3 (63.0 g), with DeKalb hens showing an increase with Diet 5 compared to Hisex hens. Egg mass improved with the higher rate of enzyme in 16% WM diet compared to the lower enzyme level. Specific gravity declined with enzyme supplementation in WM diets. Eggs from DeKalb hens had lower SP than those from Hisex hens for all diets. Percentage dirty eggs did not differ significantly among treatments but was higher for the Hisex strain than for the DeKalb strain. There were no differences in BW between the two strains of hens or among diets. Adding protease and xylanase to diets rich in fiber can improve the egg output without affecting production parameters.

1Department of Animal Sciences, Purdue University, West Lafayette, Indiana 47907; 2Department of Animal and Food Sciences, Texas Tech University, Lubbock, Texas 79409; 3Department of Poultry Science, Auburn University, Auburn, Alabama 36849; 4Department of Poultry Science, University of Arkansas, Fayetteville, Arkansas 72701; 5Poultry Production and Product Safety Research Unit, USDA, Agricultural Research Service, Poultry Science Center, University of Arkansas, Fayetteville, Arkansas 72701; 6Novus International, Inc., St. Louis, Missouri 63141; 7Poultry Science Association, Savoy, Illinois 61874; 8Department of Animal and Food Sciences, University of Delaware, Georgetown, Delaware 19947; 9Institute for Conservation Leadership, Bozeman, Montana 59715; 10Department of Animal Science, University of Minnesota, St. Paul, Minnesota 55108; 11Department of Animal Sciences, University of Kentucky, Lexington, Kentucky 40546; 12Embrex, Inc., Research Triangle Park, North Carolina 27709; 13Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, Alberta, Canada T6G 2P5; 14Department of Surgery, Section of Urology, Medical College of Georgia, Augusta, Georgia 30912; 15Animal Health/Nutrition, Archer-Daniels-Midland Co., Quincy, Illinois 62301; 16Department of Animal Science, University of Tennessee, Knoxville, Tennessee 37996; 17Akey, Inc., Marysville, Ohio 43040; 18Department of Poultry Science, University of Georgia, Athens, Georgia 30605; 19Department of Poultry Science, North Carolina State University, Raleigh , North Carolina 27695; 20Department of Animal Science, University of Nebraska, Lincoln, Nebraska 68583; and 21Department of Animal and Food Sciences, University of Delaware, Newark, Delaware 19716

Much is known about the effects of high environmental temperature (HT) on egg production, but very little is understood about the mechanisms that underlie them. Two experiments were conducted to examine the effects of acute heat stress on circulating estradiol, on calcium uptake by gut tissue, on bone resorption, and on the dynamic relationships between estradiol and calcium in the hen during one ovulatory cycle. In one study, hens were moved individually and randomly into a hot [HT: temperature (T) = 35 C, relative humidity (RH) = 50%; n = 18] or a control, thermoneutral (TN: T = 23 C, RH = 50%; n = 18) environment immediately after a mid-sequence oviposition and brachial vein cannulation. Blood samples (2 mL) were collected every 3 h for 21 h for ionized calcium (Ca2+) and pH determinations and from which aliquots were frozen for 17β-estradiol (E2), total calcium (TCa), and inorganic P analysis. Excreta and urine were assayed for TCa and hydroxyproline (OHPr), respectively. A second study was conducted to determine the effects of HT (T = 35 C, H = 50%, 12 h) vs TN (T = 23 C, RH = 50%, 12 h) on the ability of duodenal cells to take up calcium (CaT). Blood pH and calcium responded to HT as expected (pH increased, Ca2+ decreased, and TCa decreased) and the cyclic pattern of Ca2+ in blood was abolished. The ratio of Ca2+:TCa decreased sharply at approximately the onset of shell calcification in control hens, but in HT hens there was no clear change in the ratio at any point in the cycle. The pattern of E2 typical of hens under normal conditions was significantly depressed in plasma of HT hens. Calcium uptake by duodenal epithelial cells of HT hens was lower than in TN hens. There was a clear inverse correlation between blood Ca2+ and urine OHPr in TN hens (r2 = –73, P = 0.0021) but not in HT hens (r2 = –27, P = 0.32). In addition to alterations in acid-base balance and the status of Ca2+, diminished ability of duodenal cells to transport calcium may be a critical factor in the detrimental effects of heat stress on egg production (numbers), eggshell characteristics, and skeletal integrity often documented in the laying hen.

Urinary N-acetyl-β-D-glucosaminidase (NAG) is an early physiological indicator of renal damage in several mammalian species. A study was conducted to confirm occurrence of NAG in hen urine, to establish baseline urinary NAG in laying hens, and to assess the feasibility of using the enzyme as a marker of renal damage in hens. Hy-Line® hens were used in a completely randomized block design in the first part of the study. Urine was collected at 4 to 6, 6 to 10, 10 to 14, and 14 to 18 h, and serum at 4, 6, 10, and 14 h postoviposition, and assayed by spectrophotometry for NAG. Kidney tissue from additional hens was assayed histochemically for NAG. Serum NAG (range: 0.11 to 0.14 mU/mg protein) was found to be several orders of magnitude lower than urine NAG (6.44 to 12.27 mU/mg protein). Urine NAG increased from 4 to 6 h through 14 to 18 h, indicating that time of collection is critical in order to utilize the enzyme as a valid marker for laying hens. A preliminary study with five hens indicated that 10 d of treatment with liquid cholecalciferol (D3) supplement (three times the recommended level) were not enough to detect renal damage on the basis of significant changes in urine NAG, but elevated urine NAG was detected at 40 d of D3-supplementation. Overall the results indicate that NAG in urine of laying hens is a potentially useful diagnostic marker of renal damage.

Altered brain GABA, phosphocreatine and adenosine triphosphate have been documented in paroxysmal (px) chicks in earlier studies, suggesting perturbations in energy metabolism as a causative factor in this syndrome that is characterized by spontaneous neural degeneration of several central sensory systems, grand mal seizures, and progressive anorexia. In this study, brain sections from 5-, 7-, and 10-day-old px and normal White Leghorn-cross chicks were stained by immunocytochemistry to localize and quantify GABA. Serum glucose was measured to assess adequacy of circulating energy substrate. Differences between px and normal brains were found in GABA staining intensity in nuclei and tracts associated with auditory, vestibular and oculomotor function, and in several septal areas. Staining appeared to be confined primarily to terminals, and increasingly larger numbers of stained terminals were found in older px brains. This progressive increase appears to parallel the degenerative changes that occur over time in px brain and progressive manifestation of clinical signs. Px chicks appear to have adequate circulating glucose, suggesting that alterations in brain energy substrates are not a function of inadequate supply.

1. At thermoneutrality (28 degrees C), CSF Na+:Ca2+ in hens was 61.66; under thermal stress (39 degrees C), it changed to 59.38 (30 min), 62.58 (3 hr), and 52.44 (10 hr); no change in ratio occurred at 15 degrees C. 2. ICV Ouabain and/or EGTA increased body temperature (TR) but not respiration rate (RR) at 39 degrees C. 3. At 28 degrees C, Ouabain decreased, and EGTA increased, TR and RR. 4. Ca2+ may be more critical than Na+ in thermoregulation. 5. Heat stress appears to stimulate Na+-transport mechanisms other than Na+-ATPase. 6. RR appears to be a function of TR, not of ion balance.

WHITE Leghorn layers were monitored for heat loss, feed intake, egg production and respiratory rate at various environmental temperatures (TJ after first being exposed to aerial ammonia (NH3). The initial exposure was to 10 or 60 ppm NH3 at a T, of 25 °C for 30 days to simulate a winter environmental condition in a poultry facility. Hens were then allowed to recover in an environment of 5 ppm of NH3 at a T^ of 22 °C for seven days to simulate a spring environmental condition. Birds were then placed individually in a partitional calorimeter free of NH3 at 25, 29, 33, or 37 °C for 24 h to simulate initial summer environmental conditions. There were no statistical differences (P>0.05) between the two groups of NH3-treated hens for sensible or latent heat losses, apparent respiratory efficiency of latent heat loss, egg production, or feed intake. From these resutls, it is hypothesized that interplay between cutaneous evaporative heat loss and respiratory evaporative heat loss may play a more important physiological role than previously thought in maintaining homeothermy of the bird at high environmental temperatures. This physiological reponse could thus provide an energetics compensation for lung damage caused by aerial ammonia.

The surface ultrastructure of the lung and trachea of 7-week-old broiler chicks were examined with scanning electron microscopy (SEM) to obtain a more accurate understanding of structural changes due to atmospheric ammonia (NH3). In the first experiment, four broilers were randomly assigned to each of four chambers, and exposed to 0, 25, 50, 75, or 100 ppm NH3 for 7 days. Chickens exposed to 100 ppm NH3 exhibited a large number of mucus-secreting cells that were not seen in the other treatments. Ciliary loss from the tracheal epithelium was not a consistent finding in either the exposed or the control groups. There was no evidence of goblet cell disappearance due to ammonia treatment. In the second experiment, four broilers were randomly allocated to each of four chambers and exposed to 0, 50, 75, or 100 ppm NH3 for 4 days. There was an increase in the thickness of the atrial walls and a shrinking of air capillaries with increasing NH3 concentration; in birds exposed to 75 and 100 ppm NH3, wall thickness was one to two times greater than in the control birds. There were no observable differences in gross appearance of lungs and tracheas between control and exposed groups except for hemorrhagic spots on one of the lungs exposed to 100 ppm NH3.

An experiment was conducted to study calcium appetite and dietary calcium level related to laying hen performance. The experiment consisted of three periods: pre-experimental, training, and experimental. A total of 80 commercial strain laying hens (58 weeks old) were divided into two groups. One group (20 birds) served as a control throughout the experiment and was fed 3.5% dietary calcium without a free-choice calcium supplement. The other 60 birds were randomly divided into 3 sets of 20 and were all fed 3.5% dietary calcium for a pre-experimental period (13 days) as an adaptation period to a new environment prior to a training period (5 weeks). Dietary calcium level was decreased by .5% each week through the 5th week (to 1% Ca) for all 60 hens during the training period. The birds were given access to a free-choice calcium supplement (calcium carbonate granules) during both the pre-experimental and training periods. This dietary regimen was used in an effort to allow all hens to adapt to a supplemental feeding program and be prepared or conditioned for sudden changes in dietary calcium level. At the end of the training period, the 3 sets of 20 hens were fed either 1, 3, or 5% dietary calcium and a free-choice calcium supplement for 6 weeks. As dietary calcium level was increased, there was a decrease in free-choice supplemental calcium intake; however, all birds (except controls) consumed very large amounts of calcium. The training procedure was successful: no hens rejected the supplement. Neither dietary calcium level nor total calcium intake affected feed intake.(ABSTRACT TRUNCATED AT 250 WORDS)

Far-field recordings of short latency auditory responses were characterized in the White Leghorn chick (Gallus domesticus, 2-3 weeks post hatch). Six to twelve positive peaks were normally present within the first 8 ms following the onset of a click stimulus (stimulus intensity = 99.0 +/- 6.3 dB pe SPL, 44.3 +/- 1.2 dB SL). Both cochlear microphonic (CM) and neural response components were distinguished based on functional criteria. Neural responses (P1a-P6b) were readily masked by white noise. CM responses were resistant to masking and inverted when click polarity was reversed. Systemic cooling produced shifts in neural response latencies such that later peaks (e.g. latencies greater than or equal to P3) were delayed to a greater extent than early peaks (P1a and P2a). The latencies of CM components were relatively unaffected by cooling. The mean latencies and amplitudes were described quantitatively for dominant positive peaks. The mean auditory response threshold for 18 animals was 54.5 +/- 7 dB pe SPL. Dominant later components (P3a and the P3b/P4a complex) were the first to disappear after lethal injection of anesthetic. These were followed immediately by earlier neural peaks. CM components were the last to disappear. A working hypothesis is advanced regarding the distinction between central (P3a, P3b and P4a) and peripheral (P1a, P2a) neural components.

The effects of inverting click phase on far-field peripheral and brainstem auditory-evoked responses (PBARs) were examined in 8 White Leghorn chicks of age 3 wks. Significant latency differences occurred in all major positive peaks (Pla, P2a peripheral; P3a central) in response to rarefaction vs condensation clicks of equal intensity, with condensation clicks producing the shortest latencies (latency differences: Pla = 0.374, P2a = 0.372 and P3a = 0.352 msec, p less than .001). The mean latency shift corresponds to an equivalent sine wave frequency of approximately 1360 c/s, a value close to the spectral peak energy of the click. No differences in interpeak latency values were found nor any significant amplitude effects.

1. 1. Peripheral and central auditory projections were sectioned and far-field recordings measured to determine neural generators of the waveform in the White Leghorn chick. 2. 2. The mesencephalicus lateralis p. dorsalis and more rostral structures do not contribute to the waveform. 3. 3. Activity of N.VIII is reflected in peaks P1A and P2A; N2A appears to be central in origin but may be in part from the central stump of N.VIII. 4. 4. The crossed dorsal cochlear tract but not the trapezoid body is necessary for P3A and P4A; it is therefore functionally homologous to mammalian trapezoid fibres. 5. 5. P1A, P2A, N2A, P2B are not dependent on crossing fibres.

Female chicks carrying the lethal, sex-linked recessive paroxysmal (px) gene are susceptible to spontaneous and audiogenic seizures. Because seizure activity does not begin until 1 to 2 weeks posthatching - coincidental with disappearance of the yolk-sac - it is postulated that a contributing factor to seizure activity may be a developmental failure of the chick's ability to switch from lipid to carbohydrate as a primary energy source. In testing this hypothesis, three experiments were performed: 1) to evaluate cerebral energy reserves - adenosine triphosphate (ATP), phosphocreatine - of px and normal chicks; 2) to determine effects of energy source (ethanol, glucose, insulin, and glucose-insulin combined) on audiogenically-induced seizure activity and electrical seizure threshold; 3) to evaluate energy source utilization as estimated by the respiratory quotient (RQ). Brain ATP and phosphocreatine levels in px chicks were both decreased (P less than .05) as early as 10 days posthatching. Ethanol increased electrical seizure threshold in 50% of px chicks and provided protection from audiogenic stimulation. No consistent effect was found with any of the other substances. The RQ of px chicks were lower (P less than .05) than those of controls by 18 days posthatching.

1. Hens received ICV injections of Ca2+ (1.98 g/100 ml) or Na+ (7.25 g/100 ml) at 28 degrees C and, following acclimation, at 37 or 20 degrees C, respectively. 2. At 28 degrees C (thermoneutrality), rectal temperature rose (P less than 0.05) following Na+ and fell (P less than 0.05) following Ca2+, similar to mammals and broiler chickens. 3. At 37 degrees C, Ca2+-induced hypothermia did not occur; nor did the Na+-associated hyperthermia at 20 degrees C. 4. Acclimation to a high or low temperature may produce an endogenous shift in CSF ion levels that make additional ion administration ineffective in affecting body temperature.

Temperature-humidity effects on physiological responses of tom turkeys were investigated using a twodimensional rotatable central composite design. Eight temperature-humidity combinations were evaluated from 23 to 40°C and 40 to 90% RH. Response surfaces for mean, variation, and slope of core body temperature, CO2 production, and moisture production were used to assess level of stress at each of four ages. Temperature and humidity were approximately equal in their effects on physiological responses of 6-wk-old turkeys. Above 10 weeks of age, temperature decreased in relative significance as a stressor, and humidity appeared to be a more important factor in the birds’ ability to maintain homeothermy.

STUDIES on the hydrolysis of parathion (O-O-di-ethyl-O-p-nitrophenylphosphorothionate) and E.P.N. (thiono-benzene phosphoric acid O-ethyl-O-p-nitro-phenylester) at pH 7 showed unexpectedly that traces of some metal ions, for example, cupric ions, have a marked catalytic effect.