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Four layer genetic stocks consisting of 3 Ottawa control strains (5, 7, and 10) and a commercial laying stock (CCS) were utilized to evaluate potential changes in behavioral profiles due to the effects of genetic selection through 2 production cycles. The Ottawa strains were started as random bred strains from the crosses of several popular commercial layers in 1950, 1959, and 1972, and the commercial strain used herein was from calendar year 1993, and its ancestors were involved in the formation of all of the random bred strains. The behavior study utilized 2 replicates from each strain that contained 4 cages, 6 hens/cage, for a total of 192 hens. Behavioral observations were recorded on 2 consecutive days beginning at 22 wk of age and every 28 d thereafter during the first production cycle, the molt period, and the second production cycle through 90 wk of age and periodic feather and Hansen's test scores recorded. Behavior profiles were similar between the control strains and the CCS, indicating that long-term genetic selection by commercial egg-type breeding firms to enhance production parameters has had no impact on laying strain behavior patterns. Appetitive behaviors were not affected by strain. During the molt, hens had reduced (P < 0.05) feeding and drinking frequencies in comparison with those observed during the first and second cycles. The data indicated that hens pecked inedible objects at a greater (P < 0.0001) frequency during the first cycle and molt than during the second cycle. Fearfulness scores were only influenced by production phase with the molt having the highest (P < 0.01) score of 3.46. Strain or production phase did not influence the frequency of aggressive and submissive acts.

The hypothesis was proposed that the improved embryonic livability observed when higher incubation temperatures were imposed on eggs stored for 15 d prior to setting might have basis in energy metabolism. To test the hypothesis, fertilized turkey eggs were incubated either for the first 2 wk of development (experiment 1) or only the first week of development (experiment 2) at 37.8 degrees C compared with controls incubated at 37.5 degrees C. In both experiments, eggs were stored for either 15 or 3 d prior to setting. Viable embryos were selected randomly from each storage-by-incubation period treatment combination at 25 to 28 d of incubation and were sampled for blood, heart, and skeletal muscle tissues. Tissues were weighed and assayed subsequently for glucose or glycogen content. In experiment 2, the randomly selected embryos from each treatment combination were sampled at 7, 14, 21, and 28 d of incubation. Embryos at 7 and 14 d were assayed on a whole body basis, whereas at 21 and 28 d the bodies were dissected, and heart, liver, and skeletal muscle tissues were weighed and assayed for glycogen and lactate. Blood samples were collected between 25 and 28 d of incubation as in experiment 1 and assayed for glucose, creatine kinase, lactate dehydrogenase, and thyroid hormone concentrations. In both experiments, accelerated development was noted due to higher temperature and enhanced embryonic carbohydrate metabolism, and elevated thyroid hormone concentrations were observed compared with controls. It was concluded that a possible mechanism for the improved livability of faster growing embryos observed after prolonged egg storage might be due to better utilization of carbohydrate.

Two commercial strains of Single Comb White Leghorn hens, HyLine W-36 and DeKalb XL, were reared separately as pullet flocks in an enclosed, environmentally controlled brood-grow house with three banks of quad-deck cages (310 cm 2 per bird). There were 1,800 hens of each strain, which were divided into two groups, control feed and a direct-fed microbial (DFM) feed treatment. During the pullet-rearing phase to 18 wk of age, the DeKalb birds had greater parameters of growth and overall feed cost than the HyLine birds. The overall feed cost of the DFM treatment was $0.02 per bird greater than controls. However, the DFM-treated feed improved the livability of the DeKalb birds by 2.68%. At 18 wk of age, 3,528 hens were transferred to an enclosed, mechanically ventilated layer house. The two strains were placed in two differently sized quad-deck layer cages with seven birds per cage; the cage sizes were 35.56 cm x 60.96 cm (2,267.73 cm 2 or 310 cm 2 per bird) and 14 cm x 32 cm (2,890.32 cm 2 or 413 cm 2 per bird). There were a total of 144 replications with each strain and DFM treatment combination made up of 36 replications equally divided between the high and low density cages. At 70 wk of age, hens receiving the DFM treatment exhibited greater mean egg weights (61.72 g) and percentages of extra large eggs (XLE, 52.06%) compared to that of controls (61.12 g and 48.98%, respectively). The treatment of 310 cm 2 /hen DFM produced the least (P ≤ 0.05) large eggs; however, this treatment group produced the most (P ≤ 0.05) XLE. The use of DFM resulted in a shift from smaller to larger eggs. Regardless of density, the DFM hens had lower (P ≤ 0.05) feed cost (FC) compared to FC of the controls (a savings of $0.46/bird between the DFM and control in the 310 cm 2 /hen treatment and a $0.83 savings/bird between the DFM and control in the 413 cm 2 /hen treatment). It was concluded that PrimaLac can improve egg size and lower feed costs, regardless of the bird density used in the present study.

Thyroid hormone responses in embryonic avian species are of two types, developmental and metabolic. Many studies have characterized the developmental function of the turkey embryonic thyroid, but few have characterized the metabolic function. Therefore, the purpose of this study was to describe the response of turkey embryonic thyroid hormones to three environmental factors. We proposed that embryonic thyroids from different genetic backgrounds would respond differently to changes in maternal diet and incubation temperature. Lines of turkeys known to have different embryonic growth and survival were examined in the current study. These eggs differ in egg weight, eggshell conductance, hatchling weight and organ maturity at the time of hatching. Eggs were produced throughout a 20 wk laying period and embryos were sampled at monthly intervals. Half of the hens producing the eggs were fed additional iodide in their diets, then, subsequently, half of each dietary treatment and line combination were incubated at either 36.8 C or 37.5 C to prolong the incubation period. Embryos were sampled during the final week of incubation when thyroid hormones become elevated to effect maturation and survival functions in turkey embryos. Embryonic thyroxine (T4) and triiodothyronine (T3) levels were assayed by RIA and compared among the treatments. Line, diet, and incubation period interacted to affect the levels of T4, T3 and T3 to T4 ratios in the turkey embryonic during late incubation. It was concluded that environmental factors can affect circulating thyroid hormone levels in turkey embryos, thus affecting metabolic functions, and the possibility exists to manipulate these circulating levels using environmental incubation conditions to improve hatchability.

An experiment was designed to examine a mechanism to improve embryonic survival following maternal thyroid hormone manipulation. Commercial turkey breeder hens were fed diets containing supplemental iodide to mimic changes in the maternal thyroid output during an egg production cycle (32 to 48 wk of age). Dietary iodide treatment depressed maternal blood thyroxine (T4) concentrations in a time-dependent manner. Dietary iodide depressed maternal blood 3, 5, 3’-triiodothyronine (T3) levels across all times examined. The maternal dietary treatment increased embryonic blood concentrations of T4 at 25 to 28 d of incubation but depressed blood concentrations of T3 only at 27 d of incubation. In a second trial, the same response was noted in maternal blood when the hens were fed additional iodide with no corresponding effects on T3 concentrations. The iodide treatment decreased embryonic T4 concentrations in the second trial as well but in a time-dependent manner. Iodide accelerated the increase in T4 concentrations coincidental with earlier pipping in eggs from iodide-fed dams compared with controls. The data indicate that the embryonic thyroid function during hatching is dependent upon the maternal thyroid in turkey dams, even though the embryo develops outside the maternal body.

Functional eggshell qualities, thyroid hormones, and carbohydrate metabolism of chick embryos at the end of incubation were compared between a modern (Arbor Acres line) and a randombred control population (Athens-Canadian Randombred). Embryos from the Arbor Acres genetic line developed in larger eggs with more albumen and less yolk than Athens Canadian Randombred lines. Percentage shell and functional eggshell properties measured as eggshell conductance constants did not differ between genetic lines. On a relative basis, hearts were generally smaller and livers heavier in Arbor Acres than in Athens-Canadian Randombred birds. Heart and liver glycogen concentrations were greater in Athens-Canadian Randombred than in Arbor Acres embryos. However, blood glucose was greater in Randombred than in Arbor Acres embryos only at internal pipping, a time of hypoxia and hypercapnia. Blood plasma concentrations of thyroxine did not differ significantly between the modern and Randombred embryos at any stage examined. Modern broiler chick embryos possessed greater concentrations of triiodothyronine as well as greater triiodothyronine to thyroxine ratios than Randombred embryos at external pipping and hatching. It can be inferred from the data that chick embryos differ in their use of carbohydrate during late development between modern and Randombred genetic lines.

A flock of 520, 11-wk-old breeder Pekin ducklings was raised in 20 floor pens in a curtain-sided poultry house under decreasing day lengths. At 22 wk of age, the ducklings were photostimulated (16 h of light/day) with a combination of natural daylight and artificial light. After dusk, half of the ducklings were exposed to 10 lx of incandescent (IN) light and the other half were maintained under 172 lx of high-pressure sodium (HPS) light. In addition, each light treatment consisted of an equal number of pens with two different sex ratios, 22 hens:4 drakes (15% males) and 21 hens:5 drakes (19% males). Egg production, egg quality characteristics, and fertility were monitored from 22 to 52 wk of age. Ducklings housed under 172 lx of HPS light exhibited significantly (P ≤ .05) greater egg production between 23 and 34 wk of age. Egg weight, shell weight, and shell thickness were not consistently affected by the different light treatments or sex ratios. The sex ratios did not affect percentage egg fertility, but fertility was significantly (P ≤.05) higher in the HPS light treatment during the last 15 wk of the study. It was concluded that HPS light of 172 lx can enhance egg production in breeder Pekin ducklings prior to peak production (37 wk), and HPS light can improve fertility following the peak egg production period. Furthermore, this study indicated that a breeder duckling flock with 15% males was adequate to achieve optimum fertility.

DeKalb XL chicks were given a beak trim at 6 d of age (6DP) with a 2.8-mm gauge and a beak trim at 11 wk (11WB) with a block cut approximately 2 mm anterior to the nasal openings. Corticosterone (CS) levels of the 6DP treatment were (P < or = 0.01) elevated above nontrimmed CS levels at 2 h posttrim; and BW and feed consumption (FC) of the 6DP were depressed until 8 wk of age. At 11 wk of age, CS of the 11WB treatment was (P < or = 0.02) elevated above controls at 1, 2, 8, and 5 wk posttrim. The 11WB treatment resulted in a decrease in FC and a reduction in BW at 12, 14, and 16 wk of age, whereas there were no differences among treatments in livability during the pullet phase. At 72 wk of age, FC of the nontrimmed controls was greater than both beak trimmed treatments, and both beak trimmed treatments had greater hen housed eggs, percentage hen day egg production, and percentage livability. Both beak trimmed treatments resulted in better egg income, feed cost per hen, and net income (NI). The 6DP and 11WB beak trim treatments resulted in an improvement of NI per hen of 1.48 dollars and 1.86 dollars, respectively. In addition, both beak trimmed treatments exhibited better feather score and Hansen's test (fearfulness). It was concluded that pullets and hens could adapt to the physiological stress of beak trimming and out perform, during a lay phase, controls whose beaks were not trimmed.

Two commercial strains, Hy-Line W-36 and DeKalb XL, were moved to a laying house at 18 wk of age. They were housed 6 hens/layer cage at 2 densities (361 and 482 cm2/bird) with 2 replications each per strain/density combination. The high-density treatment contained 24 hens/replication and the low-density treatment contained 18 hens/replication for a total of 168 hens. Production parameters were measured during the first egg production cycle, the molt period, and the first 4 wk of the second lay cycle (20 to 68 wk of age). Behavioral observations were taken during 2 consecutive d at 26, 34, 43, 51, 62, 64, and 68 wk of age to examine behavioral patterns. Modified Hansen's tests were conducted concurrently to provide indication of the fearfulness levels of hens at the various stages of production. The production characteristics were similar for both strains. The hens kept at the higher density had lower (P < 0.01) hen-day production and (P < 0.05) daily egg mass. Appetitive behaviors were not affected by strain or density but were affected by the age of the hen and by molting. During the molt, feeding and drinking behavioral acts were fewer (P < 0.05) at 0.018 and 0.013 acts per bird/min, respectively, and standing behavior was highest. The results indicated that the frequencies of pecking inedible objects during the molt period were similar to the frequencies at 26 and 34 wk. Hens performed more acts of standing, and crouching and had lower frequency of movement during the molt. Those kept at a low density performed more movement acts. Feather pecking decreased as hens aged and increased when they molted but was not affected by strain or density. The frequency of aggression and submissive acts was significantly lower during the molt period. Behaviors were affected by strain, density, bird age, and molting; however, the patterns and number of aggressive acts did not increase to compromise the welfare status of the hens. Behaviors during the molt appeared consistent with mechanisms for conservation of body reserves.

The hypothesis was proposed that shorter incubation periods and faster growth rates for long-stored eggs would improve embryonic survival and poult hatchling quality. Increased incubation temperatures were tested for their efficacy in improving embryonic livability in fertilized eggs stored for 15 d prior to setting in the incubator compared to controls stored for only 3 d. Two temperature treatments were applied. In experiment 1, a 37.8 degrees C set point for dry bulb temperature was used to accelerate development for the initial 2 wk compared to the controls at 37.5 degrees C. Following treatment, the accelerated embryos were returned to the same machine as the controls. In experiment 2, higher temperature exposure was only for the initial week of incubation. The temperature and storage treatments were in a completely random 2 × 2 factorial arrangement of treatments. At the completion of 28 d of incubation, survival rates of all treatments were determined by opening all nonhatching eggs to differentiate truly fertilized eggs from unfertilized. Hatchability was determined by dividing the total number of poults on a hatching tray by the number of fertilized eggs on a tray. Incubator trays were the experimental unit. Tissues were sampled in both experiments to verify treatment effects on growth and metabolism. Hatching times were observed at 4-h intervals during the actual hatching process beginning at 25 d of incubation. It was concluded that delayed growth and depressed metabolism of fertilized turkey eggs stored for 15 d can be compensated for by exposure to higher incubation temperatures for the initial 1 or 2 wk of incubation.

Four commercial table egg genetic stocks consisting of the Ottawa Control Strains 5, 7, and 10 (CS5, CS7, and CS10) and the 1993 H&N "Nick Chick" (CCS) were housed in the same environment and compared for production characteristics. These birds were housed in an environmentally controlled laying facility with trideck cages. Feed consumption, egg production, and mortality were monitored daily and compiled every 28 d. The study was conducted for two egg production cycles, including the molt period. Body weight was progressively lower for the more modern strains with CS5 being the heaviest and CCS maintaining the smallest body weight throughout the production periods. The CCS had the highest (P < 0.0001) hen-day production rate, which resulted in the greatest daily egg mass among the strains. The CCS consumed the greatest amount of feed and exhibited the highest gross egg income among the strains. We concluded that genetic selection has improved production parameters in commercial layers as determined by measurements in this study.

Two commercial strains of 18-wk-old Single Comb White Leghorn (SCWL) hens, HyLine W-36 and DeKalb XL, were housed six hens per cage in layer cages at two densities (361 and 482 cm2 per bird) with two replications each per strain and density combination. The high density treatment contained 24 hens per replication, and the low density treatment contained 18 hens per replication. Egg production was measured during the first egg production cycle, a molt (fast) period, and the first 4 wk of the second lay cycle (20 to 68 wk of age). Blood samples were obtained from six hens from each replicate in each strain and density combination (total of 48) at 20, 26, 34, 43, 51, 62, 64, and 68 wk of age. In addition, blood samples were obtained in a random order from hens in each cage, and the sequence of sampling was recorded (1 to 6). Blood smears were made, from which heterophil to lymphocyte ratios (H:L) were determined. Radioimmunoassays were conducted to determine levels of plasma corticosterone (CS), 3,5,3'-triiodothyronine (T3), and thyroxine (T4). The results indicated that strain did not affect percentage hen-day egg production (%HDP). Strain and cage density did not affect H:L, T3, T4, or CS. However, these parameters were affected by bird age, which was related to the egg production cycle. Plasma CS significantly (P < or = 0.001) increased during peak %HDP at 26 wk and 64 wk during the molt (fast), and H:L significantly (P < or = 0.001) increased during the molt (fast) at 64 wk. The sequence in which blood samples were obtained, from hens within a cage in sampling order, also increased plasma CS. The CS was significantly (P < or = 0.001) elevated in the third, fifth, and sixth hens from which blood samples were drawn. Plasma T3 and T4 changed during the production cycle. The T3 was significantly (P < or = 0.0001) depressed during peak egg production at 26 wk and during the molt (fast) at 64 wk when compared with the other time periods. Plasma T4 was depressed (P < or = 0.0001) at 51 wk and was elevated (P < or = 0.0001) at 64 wk during the molt (fast). The physiological and metabolic parameters of the different hen strains and cage densities were similar during egg production. However, CS, T3, T4, and H:L changed with age in relation to the egg production cycle. In addition, the physiological demands of peak egg production and molt (fast) appeared to be similar.

Eggshell conductance was measured and eggshell conductance constants were calculated for eggs from ostriches. In addition, egg water, yolk, albumen, shell, and total solids were measured in an effort to determine the maternal investment of ostrich eggs. The results of the study suggest that the optimal incubator humidity for ostrich eggs is less than 25% to allow a 15% loss of initial egg mass during the 45-d incubation period. This low humidity does not preclude increasing humidity during the actual hatching process. In addition, incubation temperatures need to be adjusted to allow a longer development time for the embryo to attain an adequate level of maturity to survive the plateau stage in oxygen consumption or to prevent the use of limited energy of the yolk to survive the anoxia of tucking and internal pipping. The optimal incubation temperature of ostrich eggs appears to be between 36.1 and 36.9 C.

A study was undertaken to assess the role of sex and age on the adrenal cortical response of turkey poults during the time period associated with idiopathic poult mortality. Three and 14-day-old tom and hen turkey poults were subjected to the following treatments: saline injection (control), cool water immersion (20 C) for 1 min, cold water immersion (5 C) for 1 min, and 1 IU/kg adrenocorticotrophic hormone (ACTH) injection. Blood was collected 1 and 4 h posttreatment for plasma corticosterone (CS) assay. Temperature treatments did not affect plasma CS in either age or sex. Plasma CS was increased by ACTH after 4 h postinjection in both sexes and at both ages. The hypothalamic-pituitary-adrenal cortical axis of the turkey poult was functional but appeared to be insensitive to temperature stress.

Three trials were conducted to investigate plasma corticosterone (B) levels in Large White turkey hens in response to adrenocorticotropic hormone (ACTH) injections at different ages, doses, and routes of administration. In Trial 1, hens were subjected to one of the following treatments at 10, 15, and 20 wk of age: cold water immersion (5 C for 1 min), ACTH injection (10 IU/kg), or saline injection. The plasma B responses to ACTH and cold water immersion followed the same general pattern in all three age groups. Plasma B levels of hens in the ACTH treatment were depressed below control B levels until 6 h postinjection, when they became elevated. Plasma B levels of hens in the cold water treatment were either similar to or increased above those of controls by 2 h posttreatment and were depressed below control levels at .5 h posttreatment at 10 and 15 wk of age. In Trial 2, three dose levels of ACTH (1, 5, and 10 IU/kg) were injected either intramuscularly (IM) or intravenously (IV) in 10-wk-old hens. There was both a dose and route of administration effect. Of the IM-injected hens, only those in the 1-IU ACTH treatment group had significantly (P less than .05) increased plasma B levels and this occurred 4 h postinjection. However, plasma B levels of the 1 and 5-IU IV-ACTH treatment hens were significantly (P less than .05) elevated at .5 h postinjection. Plasma B of the 10-IU IM and IV-ACTH treatments were consistently, but not significantly, lower than controls through 4 h postinjection.(ABSTRACT TRUNCATED AT 250 WORDS)

In each of two trials, plasma corticosterone (B) was measured in Large White turkey torn poults after the following treatments were applied: 1) .9% saline injected; 2) cold water immersion, and 3) adrenocorticotropic hormone (ACTH) injected (10 IU/kg body weight). Poults were treated at 3- to 4-day intervals from the day of hatching to 21 days of age. Plasma samples were obtained at 1, 2, 3, 4, and 6 hr posttreatment. In both trials, there was a depression in B levels within the first 3 hr following ACTH or cold water immersion treatment. Significant increases in plasma B levels of the cold water treatment occurred at 4 hr posttreatment in Trial 1 in 7-day-old poults and in Trial 2 in 21-day-old poults. A significant adrenal cortical response to ACTH injection was observed in 3- and 7-day-old poults at 6 hrs posttreatment in Trial 2. Plasma B concentrations were also measured in three groups of nontreated Large White torn poults on the day of hatching at a commercial hatchery. Plasma samples were obtained from poults in incubators at 1000 hr, immediately following commercial processing procedures at 1030 hr, and at poult placement at 1330 hr. Plasma B levels of poults sampled in the incubator and after processing were similar. However, B levels of poults sampled at placement were increased significantly above the other two groups.

The study examined the relationship between plasma corticosterone (CS) levels and early mortality in Large White tom turkey poults. Trial 1 was conducted to compare the plasma CS levels of 3-day-old poults that subsequently lived or died during the first 2 wk posthatch. Blood samples were obtained from 100 poults at 3 days of age. By 2 wk of age 9% mortality had occurred. Plasma CS of poults that lived (7.1 ng/mL) was significantly greater (P less than .05) than in poults that died (3.2 ng/mL) between 3 and 14 days of age. A second trial was conducted to test the effects of feed-induced elevation of plasma CS on poult performance under stressful conditions. This trial consisted of three treatment groups: 1) control (C), poults placed immediately after removal from the hatcher with feed and water; 2) control-held (CH), poults held without feed and water at 28.9 C for 3 days posthatch; and 3) 40 mg CS/kg feed-held (40H), poults held without feed and water at 28.9 C for 3 days posthatch then fed 40 mg CS/kg feed. Mortality was monitored daily and body weights, feed consumption, and plasma CS levels were measured at 1 and 2 wk of age. The only performance parameter that was significantly affected was body weight; a significant reduction occurred at 2 wk of age in poults given the 40H treatment. It was concluded that poult death is associated with low plasma CS levels, but diet-induced increases in plasma CS did not significantly improve livability following a stressful condition.

Two trials were conducted with turkey poults to examine the ontogeny of daily rhythmicity of plasma corticosterone (CS), and to determine the plasma CS response to adrenocorticotropic hormone (ACTH) injections and temperature stress at different times during a light-dark cycle. In Trial 1, CS levels were determined at 3-h intervals over a 24-h period in 3, 10, and 14-day-old tom and hen poults maintained on a 12 h light:12 h dark (12L:12D) light-dark cycle. Plasma CS levels of tom and hen poults were similar. A robust daily rhythm in plasma CS occurred by 10 days of age, with maximal levels of CS occurring during the scotophase. In Trial 2, daily variation in plasma CS sensitivity to cold treatment or ACTH in 2-wk-old toms was examined. Tom poults were exposed to cold water immersion (5 C for 1 min), porcine ACTH injection (1 IU/kg), or saline injection at 1100 h in midphotophase and at 2300 h in midscotophase. Treatments significantly increased plasma CS in both the photophase and scotophase, with the levels being significantly higher in the scotophase. At midphotophase cold or ACTH treatment induced, respectively, a 489 and 546% increase in plasma CS above that of controls. During midscotophase, 746 and 695% increases in CS above levels for controls were induced by cold stress or ACTH, respectively. Differences between percent changes for times of day were not significantly different. It was concluded that a daily rhythm in plasma CS in turkey poults grown under a 12L:12D light-dark cycle occurs between 3 and 10 days of age, with maximum levels occurring during the scotophase. A daily variation in the adrenal cortical response to exogenous ACTH or cold water treatment in excess of the normal plasma CS rhythm was not apparent.

Day-old tom poults were exposed to one of the following light treatments: 1) continuous incandescent light (24LL), 2) 23L:1D incandescent light, 3) 12L:12D incandescent light, or 4) natural day lengths only. Mortality was recorded daily. At Weeks 1, 2, 4, 6, and 8, after poult placement, body weights and feed consumption were measured. At each of these times, 10 poults were sacrificed from each treatment group for evaluation of plasma corticosterone. Day lengths utilized in this study had no consistent effect on poult-performance parameters except from 0 to 2 weeks of age. During this time, poults in the 24LL and 23L:1D treatments consumed less feed but were similar in body weight to poults in the other treatments. Adrenal function was also not consistently affected by day length. However, in all treatment groups plasm a corticosterone was lowest during the first 2 weeks posthatching, when compared to hormone levels at 4, 6, and 8 weeks. The lower corticosterone that occurred during the first 2 weeks posthatching may be involved in early poult mortality.