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SUMMARY Emu (Dromaius novaehollandiae) are a large flightless bird and are members of the Ratite family. Emu originated from Australia and have long been raised for their meat and oil. The cost associated with raising emu is high, which makes emu meat and products expensive. Emu have very low hatchability rates when compared with other commercial poultry. To date, little research has been published on egg storage conditions of emu eggs, which may contribute to the decreased hatchability of the eggs. In this study, eggs were stored for times ranging from 1 to 8 wk and subsequent effects on moisture loss and hatchability was recorded. we found significant differences (P < 0.0104) in hatchability of emu eggs due to storage time. Significant differences (P < 0.0001) were also found in moisture loss due to egg storage. Based on these data, 2 wk of egg storage appears to be the optimal storage time. After 3 wk of storage, hatchability begins to decrease.

The major factor facing the commercial poultry industry today is the cost of feed. Breeding companies have put great emphasis on selecting their lines for rapid growth and low feed to gain to increase the efficiency of production. Even though genetics have made drastic differences in growth parameters, evident from the last 45 years of genetic selection, producers still employ other methods to help birds perform more efficiently including; feed additives, temperature control, incubation, ventilation, hatchery sanitation and egg disinfection. Bac-DTM is a novel disinfectant, which is currently being used as a wound wash for humans and animals. The product utilizes benzalkonium chloride, a well-studied quaternary ammonium compound, which has been generally regarded as safe (GRAS). Bac-DTM has been effectively used as a human first aid antiseptic for many years. The objectives of this trial were to determine the effects of Bac-DTM on egg conductance, hatchability, body weight and feed conversion (FC) in turkey eggs and poults. Turkey eggs were washed with Bac-DTM then incubated under standard conditions while recording egg conductance and hatchability. Body weights were measured at hatch, 21d and 42d. The results showed that egg conductance, hatchability, or body weights of chicks hatched from Bac-DTM washed eggs did not differ significantly from water washed controls. However, mean feed conversion was significantly lower (p

Very little research has been conducted on emu (Dromaius novaehollandiae) in comparison to other types of poultry. Much of the information that is available to producers is very conflicting. Feed restriction for the emu chick for the first 4 d of life is a common practice among the emu industry; however, scientific research has not supported this practice. To the best of our knowledge, the effects of hydration supplements have not been investigated in the emu. Therefore, weights were recorded on emus fed Hydrogel-95 and were compared with emus that were not fed any supplements to determine if the supplement had any effect on the growth parameters of emu chicks. From these 2 field trials, we conclude that feeding Hydrogel-95 significantly decreases weight loss in emu chicks during the first week of life.

SUMMARY A comparison of performance and P reduction in litter and manure from broilers fed rations with and without phytase enzyme was made with chickens reared on litter or in cages. Low-activity phytase supplemented as a dry powder to mash diets did not affect performance, but litter P accumulation was decreased 14 to 21% in the finisher phase. Manure P content of broilers in cages was reduced 14 to 19% during the starter and grower phases. Liquid phytase applied postpelleting to diets with 0.5% total P (0.3% available P) reduced litter P accumulation (14 to 19%) and reduced manure P content in starter, grower, and finisher phases of the study. Phosphorus content in raw manure was decreased by 55% during the finisher phase. Feed conversions of broilers in cages and on conventional litter-covered floors were improved significantly with postpellet application of liquid phytase. Feed conversion improvement was greater in birds in cages. Postpellet application of dry phytase was shown to be feasible based upon performance and reduction in litter P accumulation. Feed conversions were improved by 7 to 8 points (P < 0.05) when compared to those of birds given a normal P level (0.72% total P) diet without phytase. Litter P accumulation was reduced between 20.5 and 28.5% with dry phytase applied postpelleting. With liquid phytase applied postpelleting, litter P accumulation was reduced 26.6%. These reductions in litter P content represent about 4 lb of P per ton of litter.

SUMMARY A majority of the broilers produced around the world are sexed on the basis of rapid-feathering females or slow-feathering males, which is facilitated by the presence of the sex-linked, auto-sexing, slow-feathering K gene in males. Recent advances in materials have allowed development of a caging system that is a viable alternative to the traditional floor-rearing regimen. In this study, a comparison was made between the traditional floor- and cage-rearing environments and their influence on feathering of auto-sexing, sex-linked male and female broilers fed at 0.2 mg/kg of feed either NaSe or an organic selenium yeast (OR). Feed conversion ratios, BW, and mortality were not affected by Se source. Feather tracts on the back, breast, thigh, wing, neck, and wing were scored subjectively based on feather size and skin surface covered. Feather scores ranged from 0 (no feathering) to 5 (best feathering) for each tract. The OR induced more rapid whole body feathering in the slow-feathering males as well as in the normal-feathering females. The influence of OR was evident from 21 through 42 d of age. Females had a faster feathering rate than did males. Females approached full feathering at 35 d of age, but males lagged behind females even at 42 d. Feathering of broilers in the conventional house was slightly faster than the feathering of broilers in the cage house. The mechanism for improved feathering rate in normal-feathering females and slow-feathering males given OR has not been determined.

Inorganic sodium selenite (NaSe; 0.1 and 0.3 ppm) and organic selenium yeast (Sel Plex 50: OR; 0.1 and 0.3 ppm) were provided in the diets of broilers placed on four different litter types: 1) ACR paper (diced recycled low-density fiber paper treated with boric acid, 4.5%), 2) shavings (pine wood shavings), 3) diced/cross-cut news print, or 4) 50% mixture of ACR and shavings, in a 32-pen broiler house with curtain side walls. Subjective body feathering scores ranging from 0 (no feathers) to 5 (best) were determined at 3, 5, and 6 wk of age. In experiment 1, feather scores at 6 wk of age were improved significantly with OR supplementation at 0.3 ppm compare to all other selenium treatments, and in Experiment 2 both levels of OR supplementation were associated with improved feathering compared to NaSe supplementation. ACR paper caused reduced feathering in both experiments, and neither NaSe nor OR were sufficient to overcome the problem. In both experiments, OR was associated with better feathering for broilers on all litters at all ages. Performance parameters such as feed conversion ratios were not affected by selenium source even though feathering, an energetically expensive function, was improved in the OR-fed birds.

Poult enteritis and mortality syndrome (PEMS), a disease that affects turkeys between 7 and 28 d of age, causes a severe inflammation of the intestinal tract and is characterized in poults by severe diarrhea, high morbidity, mortality, and stunting. The PEMS-associated mortality and growth depression is related to malabsorption and decreased metabolic activity caused, in part, by a possible insulin deficiency or insensitivity. Insulin receptors are stimulated by the glucose tolerance factor (GTF) that incorporates Cr. Body Cr deficiency can be exacerbated by dietary deficiency and by increased excretion due to stress associated with a diarrheal disease such as PEMS. BioChrome (BC) contains natural, preformed GTF, the bioactive form of Cr. Experiments were conducted in which BC was blended into poult starter feed at 400 ppb during the first 21 d posthatch. Body weights were determined at 1, 7, 14, and 21 d of age, and weekly feed conversions were calculated for each treatment group (control, BC, PEMS, and BC+PEMS). At 6 d post-hatch, each PEMS-designated poult was given a 0.1-mL oral gavage of a 10% suspension of feces from PEMS-infected poults. Blood samples were taken via cardiac puncture from four birds per treatment group at 7, 10, 14, 17, and 21 d of age. Radioimmunoassays were conducted for plasma insulin, glucagon, thyroxine (T4), and triiodothyronine (T3). Plasma insulin levels were depressed in PEMS-infected poults from Days 10 through 17, but plasma glucagon levels in the PEMS-infected poults were significantly elevated at 14 and 17 d, after which they returned to control levels in both of the PEMS-infected groups. The T3 and T4 levels were depressed through Day 21 in PEMS-infected poults, but with BC treatment these blood hormone levels rebounded by Day 21. Body weights of PEMS-infected poults were increased significantly by the BC treatment but not to the level of noninfected controls.

Severe wasting of body tissues, diarrhea, high morbidity and mortality, and stunting are all characteristics of poult enteritis and mortality syndrome (PEMS). The wasting of musculature and loss of nearly all adipose tissue suggested that even though the PEMS-infected poults were eating some feed, nutrient intake was not sufficient to meet body requirements for maintenance and growth. Because epithelial cells in the gastrointestinal tract appeared to be a target of the undefined etiological agent (or agents) that causes PEMS, a study was conducted in which PEMS-infected poults were evaluated for malabsorption through 3 wk of age. D-Xylose, a poorly metabolized pentose, was given per os as a bolus, and blood samples were obtained from the ulnar vein in the wing of control and PEMS-infected poults over a 3-h period to estimate intestinal absorption. D-Xylose absorption in control poults peaked 30 to 60 min after the oral treatment, similar to results reported earlier. The PEMS-infected poults did not show a peak in absorption. The PEMS-infected poults showed significant delays in D-xylose absorption at 4, 7, and 11 d after PEMS challenge. The severe malabsorption and metabolic deficiency problem associated with PEMS was postulated to be a direct effect of the undefined infectious agent or agents that cause the disease.

A metabolic dysfunction contributes to the poor performance and mortality associated with Poult Enteritis and Mortality Syndrome (PEMS). Within 2 d after contact-exposed poults were removed from the presence of PEMS-infected poults and returned to their respective treatment rooms to infect experimental poults, the experimental poults began to huddle together and show signs of the disease. When separated from the huddle, body temperatures of exposure poults were depressed significantly. Body temperatures decreased progressively through 8 d after exposure with a maximum depression of 2 C and returned to a normal level at 18 d after PEMS exposure. Similar decreasing patterns in serum glucose, inorganic phosphorus, triiodothyronine, and thyroxine were observed, with maximum decreases in these serum constituents being found between 8 and 13 d after PEMS exposure. There were significant correlations among decreasing body temperatures, decreasing serum constituents, and mortality in the PEMS-exposed poults. Daily mortality rates associated with PEMS began at 6 d and peaked at 9 d after PEMS exposure. Mortality rates decreased from 9 to 15 d after experimental PEMS exposure. Depressions in serum constituents, body temperature, and increased mortality rates did not coincide with decreased feed intake associated with PEMS. Therefore, it was concluded that the agent(s) causing PEMS may have a direct effect on energy metabolism in afflicted poults.

Studies were conducted to determine the influence of the interactions among litter moisture (high [HiM]> or =40% vs low [LoM]< or =20%), brooding temperature (high [HiB] = 38 C vs normal [NrB] = 34 C), and development of poult enteritis and mortality syndrome (PEMS) as indicated by body weights, relative weights of lymphoid organs, and mortality in Control [C] vs Infected [I] groups. There was a significant interaction between litter moisture and brooding temperature that had a significant influence on BW. The brooding temperature main effect was not significant, but there was a significant litter moisture effect on BW. Body weights were suppressed by PEMS infection, but infected poults brooded at HiB on LoM had significantly greater BW than those brooded at NrB and HiB on HiM. Main effects showed that there were significant litter moisture- and brooding temperature-mediated responses for BW. Relative weights of lymphoid organs revealed significant disease main effects but no effect due to brooding temperature and litter moisture. There was a significant effect of disease and brooding temperature with regard to mortality. The results from this study suggest that litter moisture influences productivity and mortality associated with PEMS, but brooding temperature has the greatest influence on PEMS-associated mortality. Therefore, higher brooding temperature for turkey poults being placed into a facility where they may be at risk for PEMS exposure is recommended.

Two colonial types (1 and 2) of Escherichia coli are represented predominantly in cultures isolated from turkey poults with poult enteritis and mortality syndrome (PEMS). Biotype codes determined using two systems (BBL: 36570 and 34560 for colony types 1 and 2, respectively; API-20E: 5144572 and 5144512 for colony types 1 and 2, respectively) clearly establish these organisms as E. coli. These isolates were not clearly divergent from the general profile for E. coli, but colony type 2 differs from colony type 1 with regard to its negative reactions for ornithine decarboxylase and the fermentation of dulcitol, rhamnose, sucrose, and melibiose, suggesting that it is atypical. Colony type 1 is nonserotypable and nonmotile, whereas colony type 2 is serotyped as O136: motile because it has H antigens associated with flagella. Capsular antigens were not found, but thin capsules were seen on cells from both colony types in stained preparations. Cultural morphology was different with colony type 1 having a circular, mucoid, raised morphology and colony type 2 having an irregular, flat, rough morphology. Colony type 1 has a doubling time at 37 C of about 20 min, whereas colony type 2 doubles in 30 min. Furthermore, colony type 1 is a potent colicin producer, but colony type 2 is not a colicin producer. Both E. coli isolates have resistance profiles for multiple antibiotics. Each strain responds to third generation fluoroquinolone antibiotics by changing their biotypes and become resistant after culturing once in their presence. These E. coli are proposed as possible etiological links in the complex series of events that take place in poults susceptible to PEMS.

1. The influence of photoperiod and time of year on the growth of hen turkeys was investigated. 2. Photoperiod treatments consisted of computer simulations of day lengths which occur naturally in the spring and autumn of the year. Both photoperiod treatments were given to hens in the autumn and spring. 3. Data were collected for growth evaluations at 2‐ to 4‐week intervals to 16 weeks of age. No significant season × photoperiod interactions occurred. 4. The spring trial resulted in greater body weights and better food conversions (food/gain) than the autumn trial. 5. Simulated autumn daylengths resulted in greater body weights and improved food efficiency at 16 weeks of age compared with simulated spring daylengths. 6. The pattern of growth (period changes) was influenced by season, but not photoperiod. 7. Season and photoperiod both have important and independent influences on the growth of the turkey hen.

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.

Graded levels of the Fusarium mycotoxins, scirpentriol (STO), 15-monoacetoxyscirpenol (15-MAS), 4,15-diacetoxyscirpenol (4,15-DAS), and 3,4,15-triacetoxyscirpenol (TAS), were fed to chicks until 3 wk of age. The primary wing feathers, which were scored visually on a scale of 1 to 5 using a newly created scoring scheme, were altered in a dose-related fashion by 15-MAS [minimum effective dose (MED) = .5 microgram/g diet], 4,15-DAS (MED = 2 micrograms/g), and STO (MED = 4 micrograms/g) but not by TAS (MED greater than 8 micrograms/g). The minimum growth inhibitory doses were 2 micrograms/g for STO, 15-MAS, and 4,15-DAS and 8 micrograms/g for TAS. The main alteration of the feathers was a frayed and missing web on the medial side of the distal half of the feather. The shafts of the feathers tended to have an accentuated medial curve. These results imply that the feather alterations associated with corn and feed infested with Fusarium spp. might be caused by trichothecene mycotoxins such as the scirpenols.

The effect of added dietary fat on the pigmentation of egg yolks was investigated by substituting cottonseed oil (0, 2, 4, and 6%) isocalorically for corn starch in a basal diet of white corn, soybean meal, and starch amended with a stabilized, saponified extract of marigold (Tagetes erecta) to provide 70 μg of trans- lutein per g of 0% added fat diet. Two groups of 30 hens per treatment were depleted of carotenoid stores prior to the experiment by feeding the unamended basal diet for 3 wk. After the hens had been fed the experimental diets for 21 days, five replicates of 4 eggs per pen were collected and were analyzed by HPLC for oxycarotenoid content. The diets with 0, 2, 4, and 6% fat yielded egg yolks with 45.42, 68.56, 75.57, and 80.89 μg of total oxycarotenoids per g yolk of which trans-lutein was 75, 76, 76, and 77% of the total, respectively. The minor oxycarotenoids detected were trans-lutein monoesters, trans-3′-oxolutein, trans-zeaxanthin, and cis-luteins. The yolks from hens fed the diets with 0, 2, 4, and 6% fat had scores of 10.3, 12.8, 13.2, and 13.3, respectively, according to the Roche Yolk Colour fan. Most earlier reports of positive, negative, and no effects for added dietary fat on yolk pigmentation can now be reconciled.

High mortality occurred in two flocks of ducklings: 20% and 50% by 4 and 7 days of age, respectively. The feeds were found to contain 300 to 1176 ppb of deoxynivalenol (DON), 4.5 ppm of fumonisin, and 10 ppb of aflatoxin B1. No other mycotoxins were detected. Pathological analysis indicated that the ducklings were dehydrated with no feed in the gastrointestinal tract. Histopathology revealed no significant lesions. A necropsy diagnosis indicated a condition similar to starve-outs and feed refusal. An infectious cause of mortality was not suspected.

Poult enteritis and mortality syndrome (PEMS) has multiple etiological agents associated with its occurrence, including two viruses and at least three Escherichia coli isolates. Myco Curb (MC) contains organic acids and is used as a feed additive to inhibit growth of many bacteria and toxin-producing molds but not viruses. Studies evaluating the influence of MC on BW, feed conversion, and mortality indicate that turkey poults tolerate MC at 1.25% but not 2.50%, but higher MC content in feed provides greater suppression of growth of bacterial isolates commonly associated with PEMS. In two PEMS experiments, 1.25% MC was blended into poult starter feed and was maintained in the feed for the duration of the 3-wk experiments. In these experiments, 1-d-old commercial poults were placed into battery brooders and were given turkey starter feed and water ad libitum. At 6 d posthatch, PEMS-designated poults were given a 1-mL oral gavage of a 10% suspension of feces from PEMS-infected poults. BW depression due to PEMS was not alleviated by MC, although there was less variation in mean BW of the MC-fed poults, and there was a highly significant reduction in mortality (68% in PEMS-exposed with MC vs. 32.5% in PEMS-exposed without MC). The reduction in mortality in the MC-fed poults was attributed to decreased bacterial content of the gut and to maintenance of packed cell volume and hemoglobin content. It was concluded that MC might be a potential nutritional intervention during PEMS.

To date, no definitive etiology has been described for Poult Enteritis and Mortality Syndrome (PEMS). However, two atypical Escherichia coli colony types are isolated consistently from moribund and dead poults afflicted with PEMS. To test the infectivity of these E. coli strains, poults were placed into floor pens in three isolation treatment rooms: 1) Control: no bacterial challenge, 2) E. coli colony Types 1 or 2 posthatch oral challenge: 10(8) cfu/per poult at 1 d, and 3) E. coli colony Types 1 or 2 posthatch oral challenge: 10(8) cfu/per poult at 6 d. Daily intramuscular injections of cyclophosphamide (100 micrograms per poult) from 1 to 5 d posthatch were given to half of the poults in each treatment. Atypical E. coli challenge caused BW depression, and cyclophosphamide treatment exacerbated the response. All E. coli-challenged poults developed diarrhea similar to PEMS. Mortality was increased by both atypical E. coli colony types, but at 21 d E. coli colony Type 2 caused greater mortality than colony Type 1. With cyclophosphamide treatment, mortality was exacerbated with both colony types, but colony Type 2 at 1 d caused the greatest mortality. Ultrastructural damage to ileum epithelium cell microvilli and subcellular organelles indicated that part of the BW depression could be attributed to malabsorption of nutrients. It was concluded that the atypical E. coli colony Types 1 and 2 play a significant role in the PEMS disease.

The data that have been presented indicate that the in ovo use of competitive exclusion (CE) agents is feasible for both chickens and turkeys. However, there are many pitfalls that await the use of in ovo application of CE agents, including the use of nonspecies-specific intestinal microbes and the use of harmful proteolytic, gas-producing and toxin-producing intestinal microbes. Of the potential CE agents that have posthatch application, only Lactobacillus reuteri has been shown to be safe and effective in terms of not affecting hatchability and in having a prolonged effect in the hatched chick or poult. Lactobacillus reuteri administration in ovo increases its rate of intestinal colonization and decreases the colonization of Salmonella and Escherichia coli in both chicks and poults. Additionally, mortality due to in-hatcher exposure to E. coli or Salmonella is reduced with in ovo L. reuteri. Use of antibiotics in ovo may preclude the use of co-administered CE agents, but Gentamicin and L. reuteri are a compatible mixture when administered in ovo in separate compartments. Nevertheless, the intestinal morphology can be affected by both the CE agent and by antibiotics. Lactobacillus reuteri both in ovo and ex ovo will increase villus height and crypt depth, and Gentamicin in ovo causes a shortening and blunting of the villus. Both Gentamicin and L. reuteri in ovo suppress potentially pathogenic enteric microbes, but with diminished antibiotic effects shortening and blunting of the intestinal villi does not correct itself. Goblet cell numbers increase significantly on the ileum villus of chicks treated with Gentamicin in ovo, and this is presumably due to the increase in potentially pathogenic bacteria in the intestinal tract. Diminishing antibiotic effects posthatch would then negatively affect the absorption of nutrients and reduce growth at least in a transitory manner. Thus, L reuteri administration in ovo singly or in combination with Gentamicin followed by L reuteri via drinking water or feed appears to have potential to control many enteric pathogens in poultry. Additional work in the use of in ovo CE cultures is mandated because there is a world-wide movement to reduce antibiotic use in poultry due to increased microbial resistance to antibiotics. Use of naturally occurring intestinal bacterial cultures, either in mixed culture or as single well-defined cultures, has potential for immediate use in the poultry industry.

A synthetic opioid agonist, FK 33-824 ([D-Ala2, N-Me-Phe4, Met-(O)5-ol]-enkephalin), was administered intramuscularly at levels of 0, 1, 25, or 625 μ g/kg of body weight to 4-wk-old Arbor Acres × Arbor Acres broiler cockerels. All levels of FK 33-824 caused the birds to be sedated, with the highest dose causing deep sedation over the 240-min test period. A significant time by treatment interaction was seen for plasma growth hormone (GH). At 30 min after treatment, a significant increase in GH occurred, but this transitory increase returned to control levels at 60 min. A secondary GH peak was observed in the 240-min samples from cockerels given the 625 μ g/kg dose. Significant treatment and time effects and a time by treatment interaction were seen in the plasma prolactin (PRL) response to FK 33-824. Prolactin was increased at 30 and 60 min after treatment with 1 μ g/kg, whereas higher doses seemed to suppress PRL concentrations. Over the 240-min experimental period, PRL concentrations tended to increase in all treatments except in the treatment with the lowest FK 33-824 dose, but the largest transitory increase was observed at 240 min in the birds given the 625 μ g/kg dose. These results suggest that FK 33-824 affected GH and PRL secretion in chickens in a manner different from other opioid agonists. This difference was probably due to the ability of FK 33-824 to bind to multiple opiate receptors, with the highest affinity for μ receptors and lesser affinity for δ receptors, whereas other opioids have high affinity for δ receptors. Effects mediated by μ receptors may be stimulatory for GH and PRL secretion in chickens, whereas δ receptors may cause inhibitory responses.

An evaluation of supplementary natural ventilation in curtain-sided housing using ridge ventilation was conducted. A well-insulated broiler house was constructed and divided into two halves, one with a continuous 1.2-m wide open ridge. Four broiler trials were conducted over three summers. Neither the thermal environment nor the bird performance was affected significantly by the supplemental ventilation provided by the open ridge. Modern poultry houses with well-insulated roofs result in minimal temperature differentials, thus potentially providing a lower stack ventilation rate.

Eggs from one flock were sampled monthly for a five month period. From a total of 2440 eggs, 345 were selected and classified as having shells which were either normal, rough, or translucent streaked. There were 115 eggs in each classification. There were no differences between these classes in egg weight or surface area. Relative to normal shelled eggs both rough and translucent shells had significantly lower shell weights, mg. shell/cm.2 of surface area, percent shell, and breaking strength as determined by quasi-static loading (P

Blood was collected from random-bred male Coturnix coturnix japonica and from quail selected genetically for high or low serum corticosterone responses to complex stressors after chronic exposure to short daily photoperiods and after exposure to long photoperiods. When compared to the low response quail, high response quail exhibited increased mean cellular hemoglobin values, reticulocyte numbers and heterophil percentages, and decreased monocyte and eosinophil numbers after exposure to long photoperiods. The data indicate that these corticosterone response lines can be partitioned by their hematological responses to photoperiodic manipulation.