Air temperature, carbon dioxide, and ammonia assessment inside a commercial cage layer barn with manure-drying tunnels.

Understanding the air temperature distribution, ammonia (NH3) and carbon dioxide (CO2) levels in poultry housing systems are crucial to poultry health, welfare, and productivity. In this study, 4 Intelligent Portable Monitoring Units and 7 temperature sensors were installed inside and between the cages and above 2 minimum ventilation fans of a commercial stacked-deck cage laying hen house in the Midwest United States (425,000 laying hens) to continuously monitor the interior environment over a 6-month period. During cold conditions (March 12th-May 22nd), there was a variation noted, with barn center temperatures consistently being highest in the longitudinal and lateral direction (P < 0.001) and the top floor deck warmer than the bottom floor (P < 0.05). During hotter conditions (May 23rd-July 26th), the interior thermal environment was more uniform than during the winter, resulting in a difference only in the longitudinal direction. The daily CO2 and NH3 concentrations were 400 to 4,981 ppm and 0 to 42.3 ppm among the 4 sampling locations, respectively. Both CO2 and NH3 decreased linearly with increasing outside temperatures. The mean NH3 and CO2 concentrations varied with sampling locations and with the outside temperatures (P < 0.001). For CO2, the minimum ventilation sidewall had lower values than those measured in the barn's center (P < 0.05) during cold weather, while the barn center and the manure room sidewall consistently measured the highest concentrations during warmer weather (P < 0.05). For NH3, the tunnel ventilation inlet end consistently had the lowest daily concentrations, whereas the in-cage and manure drying tunnel sidewall locations measured the highest concentrations (P < 0.001). Higher NH3 and CO2 concentrations were recorded within the cage than in the cage aisle (P < 0.05). The highest NH3 concentration of 42 ppm was recorded above the minimum exhaust fan adjacent to the manure drying tunnel, which indicated that higher pressure (back pressure) in the manure drying tunnel allowed air leakage back into the production area through nonoperating sidewall fan shutters.

Effects of heat stress on pullet cloacal and body temperature.

One measure of the thermal status of poultry is cloacal temperature measured with a cloacal thermometer; however, this method requires handling the bird, is invasive, and can be stressful. Infrared thermography is an alternative means for assessing bird thermal status. The objective of this study was to investigate the body temperature response of pullets subjected to different environmental air temperatures during the growing phase and to evaluate the relationship between the cloacal temperature and the body parts surface temperature. A total of 648 chicks (Lohmann LSL Lite) were used in 2 different phases, phase I (day 1 through 6 wk of age) and phase II (week 7 through 17). During phase I, chicks were reared at 1 of 3 different thermal environments: thermal comfort (35°C-19°C), mild heat stress (38°C-22°C), or mild cold stress (28°C-17°C). In phase II, pullets were randomly redistributed to 1 of 4 daytime temperature treatments: 20°C; 25°C; 30°C; and 35°C, all with night time temperature of 20°C. Cloacal temperature and body surface temperature for 8 parts (head, eye, comb, chest, back, wing, leg, head area, and body area) were obtained weekly from 4 to 2 birds per treatment, respectively, during phase II. There were no effects for the interactions between the 2 experimental phases for cloacal and body parts surface temperature. There was a strong correlation (P < 0.001) between cloacal temperature and each body part temperature; cloacal temperature followed a quadratic response to environmental air temperature treatments. Pullets subjected to 35°C/20°C and 30°C/20°C had the highest body parts temperatures compared with the other 2 treatments (P < 0.05). The leg surface temperature was greatest in all treatments, and the chest the lowest. Regression between cloacal and body parts temperature had a 95% predictive accuracy of better than 0.4°C, suggesting a useful alternative to direct cloacal temperature measurement.

Effect of cooled perches on the efficacy of an induced molt in White Leghorn laying hens previously exposed to heat stress.

This study examined the effect of water-chilled perches on hen production and physiological responses to induced molt during elevated temperatures. A total of 288White Leghorns at 82 wk of age were housed in 36 cages of 6 banks. Each bank was assigned to 1 of 3 treatments: cooled perches, air perches, and no perches. The hens were subjected to 2 heat episodes during their first laying cycle at week 21 to 35 and week 73 to 80, respectively. The hens were subjected to a 28 D nonfasted molting regimen starting at 85 wk of age. Cyclic heat of 32°C (6:00 am to 6:00 pm) was applied daily during the molting period. After molt, hens were returned to a layer diet and housed under thermoneutral condition. Two birds per cage were monitored for BW change during molt. Egg production was recorded daily. Feed utilization was measured during molt at 86 and 88 wk of age. Egg weight and eggshell traits were examined at 84 wk (pre-molt) and post-molt at 92, 96, and 104 wk of age. Rectal temperature and blood samples were collected from 2 birds per cage at the end of molt. Blood samples were used for determining heterophil/lymphocyte ratio, corticosterone, and thyroid hormones. Plumage condition was examined at 22 wk post-molt. Compared to control and air perch hens, cooled perch hens had higher feed usage and greater BW loss, lower heterophil/lymphocyte ratios (P < 0.05) with no difference in thyroid hormones and corticosterone at the end of molt. Cooled perch hens also had higher egg production beginning at 98 wk of age (Ptreatment*age < 0.0001) than control hens and sometimes the air-perch hens. Cooled perch hens had higher rectal temperature than control but not air perch hens at end of molt. Moreover, cooled perch hens had better breast feather scores than air perch hens but worse vent plumage (P ≤ 0.05) than both control and air perch hens. These results indicate that the provision of cooled perches assists hens with better adaptation to stressors, such as induced molt plus heat exposure, resulting in improved post-molt egg production.

Productive performance and surface temperatures of Japanese quail exposed to different environment conditions at start of lay.

The objective of this study was to evaluate the effects of different environment conditions on productive performance and surface temperatures of Japanese quail (Coturnix coturnix japonica) during the initial stage of laying. In environmental controlled chambers, the birds were subjected to different temperatures and air velocities at the feeder. A total of 216 Japanese quails were distributed randomly in 2 galvanized wire cages, with 3 partitions each and 27 birds/cage. The experimental design consisted of randomized blocks with 2 treatments (air velocity at the feeder: 0, 1, 2, and 3 m/s and air temperature: 17, 23, 29, and 35°C) and 6 replicates. The productive performance was analyzed statistically (Sigma Plot 12.0) by 2-way ANOVA, with treatment means separated by the Tukey test (P < 0.05). To evaluate the main effects and interactions of the factors, the Holm-Sidak multiple comparisons test was performed using a mild condition as the control group (0 m/s). Feed intake did not differ (P > 0.05) among birds reared at temperatures of 23, 29, and 35°C, but higher feed intake was noted at 17°C. The mean values of egg production increased significantly (P < 0.05) with increased air velocity levels. It was observed that there was an increase in egg production and feed intake with the intensification of air velocity at the feeder, regardless of ambient temperature. Egg weight and feed conversion were not affected by air velocity treatments (P > 0.05). There was a significant positive correlation between air temperature and mean surface temperature and head surface temperature. In contrast, a significant negative correlation was observed between air velocity and mean surface temperature and head surface temperature. Productive performance was affected by temperature and air velocity, except for egg weight and feed conversion, which was not influenced by air velocity. Air velocity is important in removing heat from the surface of birds.

Effect of cooled perches on performance, plumage condition, and foot health of caged White Leghorn hens exposed to cyclic heat.

We examined the effects of water-chilled perches as cooling devices on hen performance during 2 summers using daily cyclic heat. White Leghorns, 17 wk of age, were assigned to 36 cages arranged into 6 banks. The banks were assigned to cooled perches, air perches, and no perches resulting in 2 replicate banks and 12 cages per treatment. Chilled water (10°C) was circulated through the cooled perches during heat episodes. Daily cyclic heat of 35°C was applied from 0600 to1800 h with a lowering of temperature to 28°C from 1800 to 0600 h during the 2014 and 2015 summers when hens were 21 to 35 and 73 to 80 wk of age, respectively. Mortality and egg production were recorded daily. Feed utilization, egg weight, and shell quality traits were measured at 4-wk intervals during the heat episodes and at 8-wk intervals during thermoneutrality. Body weight was determined at 17, 35, 72, and 80 wk of age and physical condition at 80 wk of age. At several ages during the heat episodes, cooled perch hens had increased egg production (P < 0.0001) and feed usage (P < 0.04) as compared to both air perch and control hens. The cooled perch hens had higher BW at 35 and 72 wk of age (Ptreatment*age = 0.03) and lower cumulative mortality (P = 0.02) than control hens but not air perch hens. Eggs from cooled perch hens had overall heavier weights (P < 0.0001) and higher breaking force (P < 0.0001) than eggs from the other two group hens. Greater eggshell percentage (Ptreatment*age = 0.03) and eggshell thickness (Ptreatment*age = 0.01) occurred at some ages during the 2 heat episodes as compared to the other 2 treatments. Nail length, feet hyperkeratosis, and overall feather score were similar among treatments. These results indicate that cooled perch ameliorates the negative effects of heat stress on egg traits and performance without influencing the physical condition of hens.

Effect of cooled perches on physiological parameters of caged White Leghorn hens exposed to cyclic heat.

We assessed the effects of water-chilled perches as a cooling device on the physiological parameters of caged laying hens exposed to 2 cyclic heating episodes. White Leghorns, 17 wk of age, were randomly assigned to 36 cages of 6 banks placed in the same room. Each bank was randomly assigned to 1 of 3 treatments: cooled perch (CP), air perch (AP), and no perch (CTRL) resulting in 2 replicate banks and 12 cages per treatment. Chilled water (10°C) circulated through the CP during heat periods when hens were 21 wk to 35 wk and 73 wk to 80 wk of age, respectively. During the heating episodes, hens were submitted to a daily cyclic temperature regimen of 35°C (0600 h to 1800 h) and 28°C (1800 h to 0600 h). Rectal temperature, packed cell volume, heterophil to lymphocyte (H/L) ratio, and plasma levels of triiodothyronine (T3), thyroxine (T4), interleukin (IL)-6, IL-10, immunoglobulin (Ig) Y, interferon (IFN)-γ, and heat shock protein (HSP) 70 were measured on the last day of the 2 heating episodes. At the end of the first heating episode, CP hens had lower rectal temperature (P = 0.02) than both AP and CTRL hens. The CP hens also had lower HSP 70 (P = 0.04) than CTRL hens but not AP hens. At the end of the second heating episode, the CP hens had lower rectal temperature (P = 0.02) and circulating H/L ratio (P = 0.01) than both AP and CTRL hens. The CP hens also had higher levels of T3 (P = 0.002) and T3/T4 ratio (P = 0.0006) than CTRL hens but not AP hens, with a greater packed cell volume than AP hens (P = 0.02) but not CTRL hens. Cytokines and IgY levels were similar among treatments. These results indicate that CP hens were better able to cope with cyclic heat stress than CTRL and sometimes AP hens as noted by the beneficial effects on rectal temperature, thyroid activity, HSP, and H/L ratio.

Effects of carbon dioxide on turkey poult performance and behavior.

Appropriate ventilation of poultry facilities is critical for achieving optimum performance. Ventilation promotes good air exchange to remove harmful gases, excessive heat, moisture, and particulate matter. In a turkey brooder barn, carbon dioxide (CO2) may be present at higher levels during the winter due to reduced ventilation rates to maintain high temperatures. This higher CO2 may negatively affect turkey poult performance. Therefore, the objective of this study was to evaluate the effects of subjecting tom turkey poults (commercial Large White Hybrid Converters) to different constant levels of atmospheric CO2 on their growth performance and behavior. In three consecutive replicate trials, a total of 552 poults were weighed post-hatch and randomly placed in 3 environmental control chambers, with 60 (Trial 1) and 62 (Trials 2 and 3) poults housed per chamber. They were reared with standard temperature and humidity levels for 3 wks. The poults were exposed to 3 different fixed CO2 concentrations of 2,000, 4,000, and 6,000 ppm throughout each trial. Following each trial (replicate), the CO2 treatments were switched and assigned to a different chamber in order to expose each treatment to each chamber. At the end of each trial, all poults were sent to a local turkey producer to finish growout. For each trial, individual body weight and group feed intake were measured, and mortality and behavioral movement were recorded. Wk 3 and cumulative body weight gain of poults housed at 2,000 ppm CO2 was greater (P < 0.05) than those exposed to 4,000 and 6,000 ppm CO2. Feed intake and feed conversion were unaffected by the different CO2 concentrations. No significant difference in poult mortality was found between treatments. In addition, no effect of CO2 treatments was evident in the incidence of spontaneous turkey cardiomyopathy for turkeys processed at 19 wk of age. Poults housed at the lower CO2 level (2,000 ppm) demonstrated reduced movement compared with those exposed to the 2 higher CO2 concentrations.

Cooled perch effects on performance and well-being traits in caged White Leghorn hens.

We assessed the effects of chilled water cooling perches on hen performance and physiological and behavioral parameters under "natural" high temperatures during the 2013 summer with a 4-hour acute heating episode. White Leghorns at 16 wk of age (N = 162) were randomly assigned to 18 cages (n = 9) arranged into 3 units. Each unit was assigned to one of the 3 treatments through 32 wk of age: 1) cooled perches, 2) air perches, and 3) no perches. Chilled water (10°C) was circulated through the cooled perches when cage ambient temperature exceeded 25°C. At the age of 27.6 wk, hens were subjected to a 4-hour acute heating episode of 33.3°C and plasma corticosterone was determined within 2 hours. Egg production was recorded daily. Feed intake and egg and shell quality were measured at 5-week intervals. Feather condition, foot health, adrenal and liver weights, plasma corticosterone, and heat shock protein 70 mRNA were determined at the end of the study at 32 wk of age. The proportion of hens per cage perching, feeding, drinking, panting, and wing spreading was evaluated over one d every 5 wks and on the d of acute heat stress. There were no treatment effects on the measured physiological and production traits except for nail length. Nails were shorter for cooled perch hens than control (P = 0.002) but not air perch hens. Panting and wing spread were observed only on the day of acute heat stress. The onset of both behaviors was delayed for cooled perch hens, and they perched more than air perch hens following acute heat stress (P = 0.001) and at the age 21.4 wk (P = 0.023). Cooled perch hens drank less than control (P = 0.019) but not air perch hens at the age 21.4 wk. These results indicate that thermally cooled perches reduced thermoregulatory behaviors during acute heat stress, but did not affect their performance and physiological parameters under the ambient temperature imposed during this study.

Environmental impacts and sustainability of egg production systems.

As part of a systemic assessment toward social sustainability of egg production, we have reviewed current knowledge about the environmental impacts of egg production systems and identified topics requiring further research. Currently, we know that 1) high-rise cage houses generally have poorer air quality and emit more ammonia than manure belt (MB) cage houses; 2) manure removal frequency in MB houses greatly affects ammonia emissions; 3) emissions from manure storage are largely affected by storage conditions, including ventilation rate, manure moisture content, air temperature, and stacking profile; 4) more baseline data on air emissions from high-rise and MB houses are being collected in the United States to complement earlier measurements; 5) noncage houses generally have poorer air quality (ammonia and dust levels) than cage houses; 6) noncage houses tend to be colder during cold weather due to a lower stocking density than caged houses, leading to greater feed and fuel energy use; 7) hens in noncage houses are less efficient in resource (feed, energy, and land) utilization, leading to a greater carbon footprint; 8) excessive application of hen manure to cropland can lead to nutrient runoff to water bodies; 9) hen manure on open (free) range may be subject to runoff during rainfall, although quantitative data are lacking; 10) mitigation technologies exist to reduce generation and emission of noxious gases and dust; however, work is needed to evaluate their economic feasibility and optimize design; and 11) dietary modification shows promise for mitigating emissions. Further research is needed on 1) indoor air quality, barn emissions, thermal conditions, and energy use in alternative hen housing systems (1-story floor, aviary, and enriched cage systems), along with conventional housing systems under different production conditions; 2) environmental footprint for different US egg production systems through life cycle assessment; 3) practical means to mitigate air emissions from different production systems; 4) process-based models for predicting air emissions and their fate; and 5) the interactions between air quality, housing system, worker health, and animal health and welfare.

Pyrilamine in the horse: detection and pharmacokinetics of pyrilamine and its major urinary metabolite O-desmethylpyrilamine.

Pyrilamine is an antihistamine used in human and veterinary medicine. As antihistamines produce central nervous system effects in horses, pyrilamine has the potential to affect the performance of racehorses. In the present study, O-desmethylpyrilamine (O-DMP) was observed to be the predominant equine urinary metabolite of pyrilamine. After intravenous (i.v.) administration of pyrilamine (300 mg/horse), serum pyrilamine concentrations declined from about 280 ng/mL at 5 min postdose to about 2.5 ng/mL at 8 h postdose. After oral administration of pyrilamine (300 mg/horse), serum concentrations peaked at about 33 ng/mL at 30 min, falling to <2 ng/mL at 8 h postdose. Pyrilamine was not detected in serum samples at 24 h postdosing by either route. After i.v. injection of pyrilamine (300 mg/horse) O-DMP was recovered at a level of about 20 microg/mL at 2 h postdose thereafter declining to about 2 ng/mL at 168 h postdose. After oral administration, the O-DMP recovery peaked at about 12 microg/mL at 8 h postdose and declined to <2 ng/mL at 168 h postdose. These results show that pyrilamine is poorly bioavailable orally (18%), and can be detected by sensitive enzyme-linked immunosorbent assay tests in urine for up to 1 week after a single administration. Care should be taken as the data suggest that the withdrawal time for pyrilamine after repeated oral administrations is likely to be at least 1 week or longer.

Drinking water temperature effects on laying hens subjected to warm cyclic environments.

Two experiments were conducted to evaluate the effects of drinking water temperature (Tw) on laying hens subjected to warm cyclic air temperature (Ta) conditions. Each experiment consisted of a 1-wk acclimation under thermoneutrality (TN) (Ta = Tw = 21 C), a 4-wk heat exposure or treatment period, and a 2-wk recovery under TN. Each experiment involved 24 individually caged hens at the initial age of 29 wk (Experiment 1) or 30 wk (Experiment 2). In Experiment 1, Tw of 18 or 27 C was provided to 12 birds per Tw regimen under a diurnal Ta of 27 to 35 C (daily mean of 31 C). In Experiment 2, Tw of 15, 19, 23, or 27 C was provided to six birds per Tw regimen under a diurnal Ta of 27 to 38 C (daily mean of 32.5 C). Experiment 1 showed that Tw of 18 C enhanced hourly and daily feed and water intake during the first 2 wk of heat exposure, as compared with Tw of 27 C. Experiment 2 showed that daily feed and water intake were greatest for hens in the 23 C Tw regimen and least for hens in the coolest or warmest Tw regimens. Reduction in daily feed intake with increase in daily mean Ta ranged from 2.0 to approximately 3.2 g/C-day (first week of heat exposure) to 1.1 to approximately 1.9 g/C-day (fourth week of heat exposure). Water to feed intake ratio was 1.8 to approximately 2.0 during acclimation and recovery, but increased to 3.0 to approximately 3.4 during heat exposure. Internal egg quality parameters were in general unaffected by Tw. The two warmer Tw regimens in Experiment 2 had less reduction in egg size than did the two cooler Tw. In both experiments, hens displayed anticipatory increase in feed and water intake 2 to 3 h prior to lights-off. However, the stimulus of lights-on did not elicit a strong return to feed and water consumption as typically seen in broilers. The results revealed the potential existence of an optimal Tw range (near 23 C) for heat-chal lenged laying hens. Larger-scale tests are warranted to further verify the findings.

Modified atmosphere treatments as a potential disinfestation technique for arthropod pests in greenhouses.

Incidental transport of arthropods on plant material can be a significant mode of pest entry into greenhouses. We evaluated the use of controlled atmosphere treatments as a potential way to eliminate arthropod pests on plant propagules (i.e., cuttings or small rooted plants). Lethal exposures to CO2 or N2 were determined for common greenhouse pests including fungus gnat larvae, Bradysia sp.; green peach aphid, Myzus persicae (Sulzer); sweetpotato whitefly, Bemisia sp.; twospotted spider mite, Tetranychus urticae Koch; and western flower thrips, Frankliniella occidentalis (Pergande). We also studied the effect of pest species, life stage, and presence or absence of plants on efficacy of modified atmosphere treatments. Finally, effects of modified atmospheres on plant quality were evaluated for several bedding plant species including begonia, Begonia semperflorens-cultorum Hort. 'Cocktail Series', chrysanthemum, Dendranthema grandiflora Tzvelev., geranium, Pelargonium X hortorum L.H. Bailey, and impatiens, Impatiens wallerana Hook f., and among cultivars of geranium and chrysanthemum. Exposure for 12-18 h to >99% N2 or CO2 caused complete mortality of aphids, mites, thrips, and whiteflies. Fungus gnat larvae were more tolerant of hypoxic conditions. Adult mites and eggs were equally susceptible. For most pests, there was no difference in response to atmospheres modified by CO2 or N2. However, there was variation in response among plant species and cultivars, with effects ranging from delayed flowering to mortality. Despite the possibility of adverse effects on some plants, this work indicates that use of modified atmospheres has potential to eliminate arthropod pests on plant propagules before they are introduced into greenhouses.

Intratracheal clenbuterol in the horse: its pharmacological efficacy and analytical detection.

Clenbuterol, a beta2 agonist/antagonist, is the only bronchodilator approved by the US Food and Drug Administration for use in horses. The Association of Racing Commissioners International classifies clenbuterol as a class 3 agent, and, as such, its identification in post-race samples may lead to sanctions. Anecdotal reports suggest that clenbuterol may have been administered by intratracheal (IT) injection to obtain beneficial effects and avoid post-race detection. The objectives of this study were (1) to measure the pharmacological efficacy of IT dose of clenbuterol and (2) to determine the analytical findings in urine in the presence and absence of furosemide. When administered intratracheally (90 microg/horse) to horses suffering from chronic obstructive pulmonary disease (COPD), clenbuterol had effects that were not significantly different from those of saline. In parallel experiments using a behavior chamber, no significant effects of IT clenbuterol on heart rate or spontaneous locomotor activity were observed. Clenbuterol concentrations in the urine were also measured after IT dose in the presence and absence of furosemide. Four horses were administered i.v. furosemide (5 mg/kg), and four horses were administered saline (5 mL). Two hours later, all horses were administrated clenbuterol (IT, 90 microg), and the furosemide-treated horses received a second dose of furosemide (2.5 mg/kg, i.v.). Three hours after clenbuterol dose (1 h after hypothetical 'post-time'), the mean specific gravity of urine samples from furosemide-treated horses was 1.024, well above the 1.010 concentration at which furosemide is considered to interfere with drug detection. There was no interference by furosemide with 'enhanced' ELISA screening of clenbuterol equivalents in extracted and concentrated samples. Similarly, furosemide had no effect on mass spectral identification or quantification of clenbuterol in these samples. These results suggest that the IT dose of clenbuterol (90 microg) is, in pharmacological terms, indistinguishable from the dose of saline, and that, using extracted samples, clenbuterol dose is readily detectable at 3 h after dosing. Furthermore, concomitant dose of furosemide does not interfere with detection or confirmation of clenbuterol.

The effect of dietary crude protein on growth, ammonia concentration, and litter composition in broilers.

An experiment was conducted to determine the effect of diets with reduced CP and supplemental amino acids on broiler performance, N excretion, litter characteristics, and equilibrium NH3 gas concentration. Results suggest that reducing CP (and lysine) below 241 g/kg (13.7 g/kg lysine) in the diets fed during the first 3 wk may slightly increase feed:gain and therefore may not be advisable. During the period 22 to 43 d of age there were no significant differences in weight gain and BW at 6 wk of age when reducing CP from 215 g/kg (11.5 g/kg lysine) to 196 g/kg (11.3 g/kg lysine), but feed intake and feed:gain ratio increased. However, reducing CP did cause equilibrium NH3 gas concentration and litter N to decline by 31 and 16.5%, respectively. Both of these advantages will improve air quality within the housing facility and possibly reduce heating costs during winter associated with higher ventilation rates required to reduce elevated NH3 gas concentrations.

The effect of dietary protein and phosphorus on ammonia concentration and litter composition in broilers.

An experiment was conducted to determine whether broiler litter concentration of N and P and equilibrium NH3 gas concentration can be reduced by reducing dietary CP and P levels and supplementing with amino acids and phytase, respectively, without adversely affecting bird performance. Equilibrium NH3 gas concentration above the litter was measured. The experiment was divided into a starter period (1 to 21 d) and grower period (22 to 42 d), each having two different CP and P levels in a 2 x 2 factorial arrangement. The CP treatments consisted of a control with a mean CP of 204 and 202 g/kg for starter and grower periods, respectively, and a low CP diet with means of 188 and 183 g/kg, respectively, but with similar amino acid levels as the control. The P treatments comprised starter and grower control diets containing means of 6.7 and 6.3 g/kg P, respectively, and low P treatment means of 5.8 and 5.4 g/kg P supplemented with 1.0 g/kg phytase. Reducing starter diet CP by 16 g/kg reduced weight gain by 3.5% and, hence, body weight at 21 d of age, but did not affect feed intake or feed efficiency. Reducing P did not affect feed intake and weight gain, but improved feed efficiency by 2.0%. Responses in feed intake and efficiency to CP depended on the level of dietary P. For the grower period there were no significant differences in feed intake, weight gain, and feed efficiency, nor in body weight at 42 d of age, after correcting for 21-d body weight, between CP and P treatments. There were significant (P < 0.001) reductions in litter N and P concentrations, but not equilibrium NH3 gas concentration, moisture content, or pH, for low CP and P diets. Mean equilibrium NH3 gas concentration was 63 ppm. Litter N concentration was reduced 16.3% with the low CP diets, and litter P by 23.2% in low P treatments. The results suggest that dietary manipulation shows merit for reducing litter N and P concentrations while maintaining acceptable production performance from broilers.

Physical change, time of day, and child characteristics as factors in poison injury.

In a study of 85 children under 6 y whose mothers called the poison center, information regarding the physical surroundings of the substance ingested at the time of the incident was obtained along with ratings of maternal stress and child behavior problems. In 51% of the incidents, the substance had recently been moved from a usual storage site or was in use at the time of the ingestion. Environmental changes occurred in 1/3 of those poisoned between 4 and 6 pm which was the 2-h period of the greatest incidence. Poisoning in children 1 and 2 y were more likely to have followed physical environmental change. Children with higher child behavior problem score were more likely to be poisoned in the morning.

Cell wall elastic constitutive laws and stress-strain behavior of plant vegetative tissue.

The appropriateness of several elastic constitutive laws for apple and potato cell walls is tested using uniform cell inflation data. Whole-tissue stress-strain behavior under uniaxial loading is predicted from an analysis of the compression of a conglomerate of cells in a simple arrangement.

Elastic constitutive laws for cow teat tissue undergoing finite deformations.

Five constitutive laws are investigated to model the effect of machine milking. A nonlinear least squares procedure is employed to estimate material constants from in vivo teat inflation data. An exponential form is found to be statistically adequate as a constitutive law, and is used to determine the mechanical stresses in teat tissue during finite deformations.

Bacterial transport within and among various teatcup and cluster assemblies during milking.

For evaluation of bacterial transport, two experiments were conducted. In Experiment 1, two nonconventional cluster designs were compared with a conventional assembly. These two units were: 1) conventional unit without a claw and 2) linerless unit without a claw. In Experiment 2, two nonconventional teatcup designs were compared with a conventional teatcup, all attached to a conventional claw. These two were: 1) partial linear teatcup assembly and 2) conventional teatcup with restricted linear wall movement. The three teatcups in Experiment 2 differed only in the lower part of the liner barrel; mouthpiece and short milk tube were identical. A culture of Serratia marcescens bacteria was infused throughout milking into the short milk tube at the right front teatcup assembly. Swabs of liners and teats were used to culture for Serratia marcescens. For Experiment 1, the number of contaminated teats (and liners) was 32 of 144 and 88 of 144 for the conventional cluster, 20 of 144 and 37 of 144 for the clawless cluster, and 10 of 144 and 16 of 144 for the linerless cluster. For Experiment 2, the total number of bacterial transfers was 14 of 25 for the conventional teatcup, 7 of 25 for the restricted liner, and 3 of 25 for the partial liner. These occurrences of transfer correlate well with previously measured reverse pressure gradients across the short milk tube.