Interactive effects of light-sources, photoperiod, and strains on growth performance, carcass characteristics, and health indices of broilers grown to heavy weights1

Effects of light sources, photoperiods, and strains on growth performance, carcass characteristics, and health indices of broilers grown to heavy weights (>3 kg) were evaluated. The experimental design was a 4 × 2 × 2 factorial treatments consisting of 4 light sources [incandescent (ICD, standard), compact fluorescent light, neutral light emitting diode (Neutral-LED), and cool poultry specific LED (Cool-poultry specific (PS)-LED)], 2 photoperiods (regular/intermittent [2L:2D], and short [8L:16D]), and 2 strains (A, B). In each trial, chicks of 2 different strains from different commercial hatcheries were equally and randomly distributed into 16 environmentally controlled rooms at 1 D of age. Each room was randomly assigned one of 16 treatments from day 1 to 56 D of age. Feed and water were provided ad libitum. Birds were provided a 4 phase-feeding program (starter, grower, finisher, withdrawal). Birds and feed were weighed on 1, 14, 28, 42, and 56 D of age for growth performance. On day 56, a total of 20 (10 males and 10 females) birds from each room were processed to determine weights and yields. The BW, BW gain, live weight, and carcass weight of birds reared under PS-LED were higher (P < 0.05) in comparison with birds reared under ICD, but feed intake, feed conversion ratio, mortality, and carcass characteristics were not affected by treatments. Also, broilers subjected to the short/non-intermittent photoperiod had the lowest (P < 0.05) growth performance and carcass characteristics compared with values obtained for regular/intermittent photoperiods. In addition, strain was significant (P < 0.05) for most of the examined variables. Feed conversion, fat, tender, and yield were not affected by treatments. There was no effect of photoperiod, light sources, or their interactions on mortality. This study shows positive impacts on alternative light sources when compared to ICD along with regular/intermittent photoperiod in commercial poultry facilities rearing the 2 strains used in this study, thereby reducing energy costs and optimizing production efficiency without compromising the welfare of broilers grown to heavy weights.

Effects of color temperatures (kelvin) of LED bulbs on growth performance, carcass characteristics, and ocular development indices of broilers grown to heavy weights

Limited data are available for comparing light-emitting diode (LED) bulbs that are currently available in commercial broiler production facilities. We evaluated the effects of color temperatures (kelvin) of LED bulbs on growth performance, carcass characteristics, and ocular development indices of broilers grown to heavy weights (>3.0 kg). The experiment had a randomized complete block design. Four treatments consisted of 3 LED light bulbs (2,700 [warm LED]; 5,000 [cool LED 1]; and 5,000 K [cool LED 2]) and incandescent light (2,010 K [ICD], standard) from day zero to 56 d of age. A total of 960 Ross×Ross 708 day-old chicks were equally and randomly distributed into 16 environmentally controlled rooms at 50% RH (30 males and 30 females/room). Thus, each of the 4 treatments was represented by 4 rooms (4 replicates) per trial. Feed and water were provided ad libitum. All birds were fed the same diet. Ocular specimens were collected on d 42 for development and histopathologic examination. Blood samples were collected on d 21, 28, 42, and 56 to determine plasma corticosterone. On d 56, twenty birds from each room (10 males and 10 females) were processed to determine weights and yields. The BW and BW gain (BWG), live weight, and carcass weights of birds reared under cool LED 1 were different in comparison to birds reared under ICD (P<0.05). However, feed intake (FI), feed conversion ratio (FCR), and mortality were not affected by treatments. The treatments did not affect fat, breast and tender weights, and yields. In addition, ocular development indices and plasma corticosterone concentrations were not affected by treatments, suggesting the LED light bulbs we evaluated did not compromise the welfare of the birds. It was concluded that cool LED 1 may be a better potential replacement light source in comparison to ICD on performance, but it may be equal when compared to other LED light sources examined in this study.

Ocular Responses to Ammonia in Broiler Chickens

In two trials, 60 male commercial broilers were placed in each of eight environmentally controlled chambers receiving 0, 25, 50, or 75 ppm aerial ammonia from 1 to 28 days. Birds exposed to 25 ppm (lower concentration) ammonia gas developed ocular abnormalities but at a slower rate when compared with birds exposed to 50 and 75 ppm (higher concentrations). Birds exposed to higher concentrations also developed more severe lesions. With little atmospheric ammonia present after 28 days of the grow-out stage, the corneas indicated signs of healing. Lymphocytes and heterophils were seen in the iris at 49 days in ammonia-exposed birds even when ammonia exposure was terminated at 28 days. The lower ammonia concentrations resulted in abnormalities that were slight when compared with those seen at the higher ammonia concentrations. As measured by the incidence of inflammatory infiltrates in the trachea, lung, and air sacs, respiratory tract tissues did not appear to be affected by any tested level of aerial ammonia. The findings in this investigation represent the first report indicating that ammonia-induced uveitis in chickens clears rapidly after exposure to ammonia ceases.

Effects of an S6 Strain of Mycoplasma gallisepticum Inoculation Before Beginning of Lay on the Leukocytic Characteristics of Commercial Layers

A clinical study was conducted on commercial layers housed in biological isolation units, within which exogenous stress factors potentially affecting bird performance were minimized. This set-up was devised in order to assess how a pre-lay inoculation of S6 strain Mycoplasma gallisepticum affects the leukocytic properties of laying chickens. Previous studies have demonstrated relative decreases in lymphocyte and relative increases in heterophil percentages in birds infected with other strains of Mycoplasma gallisepticum. However, current results showed that the differential percentages of lymphocytes were decreased, whereas those of heterophils were increased, in both sham-inoculated control birds and birds inoculated with S6 Mycoplasma gallisepticum between 19 and 26 wk of age. This study clearly shows that a pre-lay inoculation of S6 Mycoplasma gallisepticum alone had no apparent effect on the leukocyte profile of commercial layers housed in biological isolation units.

Mycoplasma gallinarum infection in commercial layers and onset of fatty liver hemorrhagic syndrome

Fatty liver hemorrhagic syndrome (FLHS) was observed in each of three trials in which commercial layers were utilized to determine the effect of Mycoplasma gallinarum (MGn) on egg and eggshell quality parameters and egg production. In each of three trials, FLHS occurred 31-54 days later in MGn-inoculated hens as compared with the Mycoplasma-clean (control) hens. In trials 1 and 2, no therapeutic intervention was initiated to ameliorate FLHS. In trial 3, therapeutic intervention was instituted and consisted of the addition of 1 pound of choline chloride/ton of feed. Total mortality recorded throughout the duration of each trial and attributable to FLHS was not significantly different between the control and the MGn-inoculated treatment. However, FLHS-associated mortality in each of the three trials was numerically greater for the control treatment.

Effects of an S6 strain of Mycoplasma gallisepticum challenge at onset of lay on digestive and reproductive tract characteristics in commercial layers

Mycoplasma gallisepticum (MG), a reproductive/respiratory pathogen in poultry, has been implicated in suboptimum egg production and decreased hatchability. Commercial layer hens raised in a controlled environment were inoculated with the S6 strain of MG at 20 wk of age. The S6 inoculation had no effect on bird weight, egg production, digestive tract weight and length, or histopathologic lesion scores, although significant differences were noted in the lengths and weights of various portions of the reproductive tract. This study shows that S6MG inoculation does not detrimentally affect layer hen performance when in the absence of environmental stressors customary to a caged layer facility.

Effects of F-strain Mycoplasma gallisepticum inoculation at twelve weeks of age on digestive and reproductive organ characteristics of commercial egg laying hens

Experimental inoculation with the F-strain of Mycoplasma gallisepticum (FMG) between 8 and 18 wk of age is known to affect reproductive performance in commercial layers. Therefore, two trials were conducted to determine if changes in digestive and reproductive organ characteristics also occur in commercial laying hens infected with FMG at 12 wk of age. In Trial 1, liver weight, liver lipid and moisture contents, ovary weight, ovarian follicular hierarchy, and the weights, lengths, and histologies of the infundibulum, magnum, isthmus, uterus, and vagina were determined. In Trial 2, fatty liver hemorrhagic syndrome (FLHS) incidence and the weights, lengths, and histologies of the duodenum, jejunum, and ileum were determined in addition to the parameters examined in Trial 1. In both trials, the average number of mature (diameter > or = 12 mm) ovarian follicles was lower in FMG-inoculated hens in comparison to controls. Also, magnum/oviduct (cm/cm) length was reduced in treated birds. In Trial 2, isthmus/BW and isthmus/oviduct (g/ g) weight were decreased at 46 wk of age, and vagina/ BW and vagina/oviduct (g/g) weight were decreased at both 20 and 36 wk of age due to FMG treatment. In Trial 2, FMG treatment resulted in a 50% increase in the number of FLHS birds. Furthermore, treatment caused a decrease at 20 wk of age and an increase at 44 wk of age in liver moisture content. However, the intestinal characteristics examined were not affected by FMG inoculation. Altered liver, ovarian, and reproductive organ characteristics were associated with FMG infection in commercial layers. More specifically, FMG inoculation at 12 wk resulted in a higher incidence of FLHS, ovarian follicular regression, and decreased isthmal and vaginal proportions of the reproductive tract. These data clearly demonstrate that alterations in performance and egg characteristics of layers inoculated with FMG at 12 wk of age are related to mutual functional disturbances in the liver, ovary, and oviduct without concomitant intestinal changes.

Effects of an S6 strain of Mycoplasma gallisepticum challenge before beginning of lay on various egg characteristics in commercial layers

Mycoplasma gallisepticum (MG) is a reproductive/respiratory disease in poultry implicated in suboptimum egg production and decreased hatchability. Commercial layer hens raised in a controlled environment were inoculated with the S6 strain of MG at 10 wk of age. Egg production and selected egg and egg quality parameters were quantitated over the entire lay cycle for inoculated and control birds. The S6 inoculation had no effect on bird weight, egg production, associated egg quality parameters, or histopathologic lesion scores. This study shows that in the absence of environmental stressors a prelay S6 MG inoculation does not produce detrimental effects on layer hen performance.

The effects of 6/85 live Mycoplasma gallisepticum vaccine in commercial layer hens over a 43-week laying cycle on egg production, selected egg quality parameters, and egg size distribution when challenged before beginning of lay

In each of two trials, 80 commercial leghorn-type pullets were separated into two treatments with four replicates of 10 chickens in each treatment. Forty pullets were designated as controls and received no inoculation, whereas the remaining 40 pullets received the 6/85 vaccine strain of Mycoplasma gallisepticum (MG) at 10 wk of age. Hen-day egg production, egg weight, eggshell strength, Haugh unit score, pimpling incidence, and blood/meat spot incidence were monitored and recorded weekly in each trial through an entire laying cycle of 43 wk. Further, eggs from all treatments were collected daily, Monday-Thursday, and individually weighed. No significant difference was observed between the treatments for 43-wk means for hen-day egg production, for any of the monitored egg or eggshell quality parameters, or for the number of extra large, large, medium, small, pee wee, or undergrade egg sizes. A significant (P < or = 0.05) difference was observed for the number of jumbo-sized eggs between the two treatments. Results of this study suggest that vaccination of commercial layer chickens at 10 wk of age with 6/85 strain MG does not detrimentally impact egg production, egg size distribution, or ovary/oviduct function as evidenced by selected egg parameters monitored in this study.

In ovo peptide YY and epidermal growth factor administration and their effects on growth and yolk utilization in neonatal meat-type chickens (Gallus domesticus)

The effects of in ovo peptide YY (PYY) or epidermal growth factor (EGF) administration on chick growth, yolk absorption and yolk stalk function in posthatch (0-5 days) meat-type or broiler chicks were determined. At Day 18 of incubation, treated eggs were injected into the air cell with 100 microl of either PYY (Trial 1) or EGF (Trial 2) at a dosage of 600 microg/kg egg weight. Saline-treated control eggs were injected similarly with 0.9% saline. At hatch, 200 microl of (51)Cr-labeled microspheres were injected into chick yolk sacs. Epidermal growth factor increased ileal wet weight adjusted for body weight as well as ileal serosal dry matter. Body weight, feed consumption and excreta weight per bird, and relative weights of the yolk sac, intestine and liver were significantly affected by age of the chick in both trials. Relative radioactivity of the yolk sac, yolk stalk, blood, liver, and kidneys were affected by bird age in Trial 2; however, there were no significant effects due to PYY or EGF treatments on relative radioactivity of the tissues and organs examined. These data suggest that PYY and EGF had no effect on yolk absorption or yolk stalk function through 5 days in the posthatch chick.

The effects of ts-11 strain Mycoplasma gallisepticum vaccination in commercial layers on egg production and selected egg quality parameters

Live Mycoplasma gallisepticum (MG) vaccines have been USDA approved and licensed for use in commercial layer chickens since 1988; however, egg production and egg quality data exist only for the F strain of MG. Information pertinent to the effects of ts-11 MG on egg and eggshell quality parameters, as well as egg size distribution, is lacking. In this study, pullets were inoculated at 10 wk of age with ts-11 strain MG and placed in biological isolation units at 10 birds/unit. Hen-day egg production, eggshell strength, Haugh unit score, pimpling incidence, and blood/meat spot incidence were monitored and recorded in each trial through a 45-wk production cycle. Further, eggs from all treatments were collected daily, Monday-Thursday, and individually weighed. Results of this study indicate that no significant difference was observed between the treatments for the parameters measured or for egg size distribution. Therefore, these data should lessen producers' concerns pertaining to the impact of ts-11 strain MG on egg production, egg and eggshell quality parameters, and egg size distribution.

The effects of F strain Mycoplasma gallisepticum, Mycoplasma synoviae, and the dual infection in commercial layer hens over a 44-week laying cycle when challenged before beginning of lay. II. Egg size distribution

In each of two trials, 160 commercial pullets were separated into four treatments with four replicates of 10 chickens in each treatment. Forty pullets were designated as controls and received no inoculation; 40 pullets received F strain Mycoplasma gallisepticum (FMG); an additional 40 pullets received Mycoplasma synoviae (MS); and the final 40 pullets were inoculated with both FMG and MS (dual). All inoculations occurred at 10 wk of age. Eggs from all treatments were collected daily, Monday-Thursday, and individually weighed. No significant difference was observed among the treatments for percentages of jumbo, extra-large, medium, small, peewee, or undergrade eggs. As a percentage of eggs laid for the 4 days of each week over the 44-wk laying cycle of each trial, the FMG hens laid significantly fewer large size eggs (43.2%) as compared with either controls (51.17%) or dual-infected hens (49.95%). No significant difference was found in percentage of large eggs laid by FMG hens when compared with MS hens.

The use of India ink and 51Cr-labeled microspheres in examining the function of the yolk stalk as a passageway between the yolk sac and intestine in posthatch broiler chicks

India ink and radioactive 51Cr-labeled microspheres were used in separate trials to examine the role of the yolk stalk lumen as a distinct pathway between the yolk sac and gut through the first 5 d of posthatch growth in broiler chicks. Throughout this period, India ink was able to pass from the yolk sac through the yolk stalk and into the intestine, but was not able to pass from the intestine into the yolk stalk or yolk sac. Furthermore, labeled microspheres moved from the yolk sac via the yolk stalk into the gut; which caused the total counts per minute of the intestine, yolk stalk, and excreta to progressively increase. It was concluded that India ink and 51Cr-labeled microspheres were useful materials in establishing that the yolk stalk provides a direct one-way passage by which material in the yolk sac may move into the intestine of broiler chicks during the first 5 d after hatching.

Subacute to chronic fowl cholera in a flock of Pharaoh breeder quail

A total of 1300 birds in flock of breeder Pharaoh quail (Coturinix coturnix) experienced a moderate rate of mortality (13%) during a 7-day period. Clinical signs included depression, ruffled feathers, prostration, lameness, inapetence, diarrhea, and periorbital sinus swelling with mucoid discharge and lameness. Gross lesions observed in dead quail were emaciation, carcass congestion, mild hepatomegaly with green discoloration, congested intestinal mucosa, caseous purulent arthritis-osteomyelitis, and thickened crop mucosal epithelium. Histopathologic examination revealed mild hepatic amyloidosis, proliferative parabronchitis, splenic reticular cell hyperplasia, thymic cortical atrophy, subacute bacterial osteomyelitis, periarthritis, and crop mycosis. Pasteurella multocida was isolated from the joints of these birds and the isolates were serotype 3 x 4. These findings suggest that Pharaoh quail are susceptible to P. multocida and are likely to develop subacute to chronic fowl cholera.

The effects of F strain Mycoplasma gallisepticum, Mycoplasma synoviae, and the dual infection in commercial layer hens over a 44-week laying cycle when challenged before beginning of lay. I. Egg production and selected egg quality parameters

In each of two trials, 160 commercial pullets were separated into four treatments with four replicates of 10 chickens in each treatment. Forty pullets were designated as controls and received no inoculation; 40 other pullets received F strain Mycoplasma gallisepticum (FMG); an additional 40 pullets received Mycoplasma synoviae (MS); and the final 40 pullets were inoculated with both FMG and MS (dual). Hen-day egg production, egg weight, eggshell strength, Haugh unit score, pimpling incidence, and blood/meat spot incidence were monitored and recorded in each trial through an entire laying cycle. No significant difference was observed among the treatments for hen-day egg production, egg weight, eggshell strength, or Haugh unit scores. Significant differences were observed for pimpling incidence among controls (1.63%), Mycoplasma gallisepticum (MG)-infected (2.09%), and dual-infected hens (2.41%). A significant difference in blood/meat spot incidence was observed between MG-infected hens (0.27%) and dual-infected hens (0.45%). Histopathologic examination of the ovary and all segments of the oviduct revealed no significant differences among the treatments. These results suggest that the majority of the hen reproductive tract functions similarly in FMG-vaccinated, MS-infected, or dual-infected hens as compared with Mycoplasma-clean hens.

Various blood parameters in commercial hens acutely and chronically infected with Mycoplasma gallisepticum and Mycoplasma synoviae

Two trials were conducted to study the effects of acute (Trial 1) and chronic (Trial 2) mycoplasma infections on differential leukocyte counts in chickens. The trials initially included either 20 (Trial 1) or 40 (Trial 2) 6-wk-old commercial leghorn chickens negative for antibodies to Mycoplasma gallisepticum (MG) and Mycoplasma synoviae (MS). Chickens were inoculated with F strain MG (FMG), MS (WVU 1853), or both. One group of chickens remained uninoculated and served as a negative control for both trials. Chickens were housed in fiberglass isolation units from 6 to 10 wk (Trial 1) or 6 to 70 wk of age (Trial 2). Differential leukocyte counts were examined from 6 to 10 wk (Trial 1) or 66 to 70 wk of age (Trial 2) in all chickens. Also, in Trial 2, packed cell volumes (PCVs) and plasma protein values were examined from 66 to 70 wk of age. In the acute study (Trial 1), differential leukocyte counts revealed statistically significant differences (P < 0.05) in heterophil, lymphocyte, monocyte, eosinophil, and basophil values among treatments. In general, the differential counts of FMG- and MS-infected birds were characterized by heterophilia, lymphopenia, monocytosis, eosinopenia, and basopenia. Histopathologic examination of the spleen, liver, kidney, and bone marrow revealed a high degree of lymphoid foci within the spleen and bone marrow of all infected chickens. In the chronic study (Trial 2), no statistically significant differences (P < 0.05) were observed in differential leukocyte counts, PCV, and plasma protein values among treatments. Histopathologic examination of spleen, liver, kidney, and bone marrow did not reveal any difference among treatments.

Effects of Newcastle disease vaccines and Newcastle disease/infectious bronchitis combination vaccines on the head-associated lymphoid tissues of the chicken

Ten Newcastle disease virus (NDV) and 10 NDV and infectious bronchitis virus (IBV) combination vaccines (NDV/IBV) were evaluated for their effect on the head-associated lymphoid tissue (HALT) of 2-wk-old chicks. After vaccination, the chicks were subjected to an in vivo assay that measures the ability of the gland of Harder (GH) to respond to killed Brucella abortus antigen given in the eye by titering B. abortus antibodies in the tears. Following this, several sites in the HALT and trachea were examined histologically and scored for microscopic changes. The results indicated that three of the NDV/IBV combination vaccines (one BI/Mass&Conn and two LaSota/Mass&Conn) interfered with the GH response to killed B. abortus, whereas none of the NDV vaccines did Histologically, several changes were noted in the vaccinated chicks; however, no changes in the GH were observed that could explain microscopically the GH depression. With the IBV-only vaccines reported earlier (16), and the NDV-only and NDV/IBV combination vaccines reported here, a total of 36 vaccines have been evaluated using the same testing protocol. The conclusions of these combined studies suggest that several of the modified live virus vaccines containing IBV, either alone or in combination with NDV, interfere with the ability of the GH/HALT to respond to antigenic stimulation.

Attempts to reproduce a runting/stunting-type syndrome using infectious agents isolated from affected Mississippi broilers

Various organisms, including 12 aerobic and 2 anaerobic bacteria, an infectious bronchitis virus (IBV), a reovirus, and 2 bacteriophages, were isolated from intestinal tracts of commercial broiler chicks undergoing a runting/stunting-type condition. In a series of trials, these agents were given alone and in combination to 1-day-old chicks in an attempt to reproduce the field condition. Because the agents were isolated and evaluated over time, an augmented designs variation of the analysis of variance proved particularly useful in analyzing the data collected and minimizing bird usage. Chicks inoculated with tryptose phosphate broth served as negative controls, and those inoculated with the original intestinal tract material were positive controls. Relative to the negative control chicks, body weights of the positive control chicks and of chicks inoculated with several of the agent combinations were depressed at 7, 14, and 21 days postinoculation. Common to combinations that most consistently caused weight depression were reovirus + IBV + others of the agents isolated. However, because none of the agent combinations reproduced the lethargy or dry feces seen in the positive controls, none was considered to be the ultimate cause of this particular runting/stunting-type condition. Further characterization of the disease syndrome was based on the positive control chicks. These chicks consistently had lowered body weights and transient lethargy and dry fecal pellets. Microscopic lesions consisted of lymphocytic renal and pancreatic interstitial infiltrates, dilated or cystic duodenal and jejunal crypts of Lieberkühn, increased crypt depth, and increased cellularity in the intestinal lamina propria. Electron microscopy revealed regular arrays of 26-nm viral particles, usually in association with membrane debris, in intestinal epithelial cells and crypt lumens and in intestinal and renal mesenchymal cells. These viral particles were theorized to be essential to reproduction of the complete malady seen.

The effect of added complex carbohydrates or added dietary fiber on necrotic enteritis lesions in broiler chickens

Two trials utilizing two corn diets and four wheat diets were conducted. In Trial 2, all chicks were crop-infused at 9 d of age with Eimeria acervulina. In both trials, a broth culture of Clostridium perfringens was mixed with the diets for 3 consecutive d. Necrotic enteritis lesion scores were lowest in chickens consuming the corn diet with no C. perfringens and highest in chickens fed the wheat diets with C. perfringens. Chickens consuming a wheat diet with no added complex carbohydrates or added fiber exhibited the highest lesion score. Chickens on wheat diets with 4% new, ground, pine shavings had intestinal lesion scores intermediate to those of chickens that consumed the wheat or corn diets. Chickens consuming corn diets yielded the lowest lesion scores. Chickens provided diets containing either guar gum or pectin were not fully consumed and thus probably reduced the number of challenge organisms ingested.

Fatty liver-hemorrhagic syndrome observed in commercial layers fed diets containing chelated minerals

This study was originally conducted to determine the effect of various chloride levels and consumption of chelated versus non-chelated minerals on egg production and eggshell breaking strength. However, the focus of this report changed after fatty liver-hemorrhagic syndrome (FLHS) was observed in hens that consumed diets containing chelated minerals. No FLHS was observed in hens that consumed a diet that contained non-chelated minerals. Four hundred thirty-two 35-week-old commercial laying hens were housed in individual cages in groups of nine hens each. The treatments were factorially arranged (3 x 2) such that six experimental diets differing in chloride levels and in source of minerals were fed for six 28-day laying periods. A significantly higher mortality attributed to FLHS was observed in hens that consumed the diets having chelated minerals as compared with hens that consumed the diets with non-chelated minerals. No difference in mortality was observed among the hens fed the various chloride diets.

Effects of modified-live infectious bronchitis virus vaccines on the head-associated lymphoid tissue (HALT)

Specific-pathogen-free (SPF) leghorn chicks were inoculated with different modified-live infectious bronchitis virus (IBV) vaccines to determine if the vaccines interfered with immune competence of the head region. A total of 16 vaccines were evaluated comprising nine Massachusetts, three Arkansas, two Holland, one Florida, and one combination vaccine (containing both Connecticut and Massachusetts). Chicks were vaccinated when they were 4 weeks, 2 weeks, or 1 day of age. When all chickens were 4 weeks 3 days of age, their glands of Harder (GH) were assayed for the ability to respond to antigenic stimulation. Tissues from chicks given GH-depressing and non-GH-depressing vaccines were also collected and scored for histological changes in the head-associated lymphoid tissue (HALT) sites and the trachea. All 16 vaccines depressed the GH response to antigenic stimulation when given to 4-week-old chicks. Six of these vaccines (two Massachusetts, two Arkansas, and two Holland) also depressed the GH response when given to 2-week-old chicks, and one, an Arkansas vaccine, depressed the GH response when given to 1-day-old chicks. The main histological changes associated with the vaccines were increases in lymphocyte populations in the nasal mucosa, eyelid, and, for some, the lacrimal gland and the GH. In addition, lymphoid follicles were increased in the eyelid, to a lesser degree in the GH, and occasionally in the trachea. No relationship was found between histologic changes and vaccine-induced suppression of the GH response.

Reovirus associated with excessive mortality in young bobwhite quail

Multiple submissions of bobwhite quail (Colinus virginianus) were received for diagnosis from a commercial-size quail operation. The history and clinical signs included respiratory distress, lethargy, and substantial mortality. Reovirus was recovered from quail in the first submission, and both reovirus and adenovirus were isolated from later submissions. To determine the pathogenicity of the isolated reovirus, the initial isolate was inoculated into young quail from a different source. Those inoculated by the subcutaneous route became lethargic, and more than half died during the 2 weeks of the trial. Reovirus was recovered from a high percentage of those inoculated by this route. To the authors' knowledge, the isolation of reovirus from quail has rarely been reported, and reovirus has never before been suggested as a pathogen in this species.

A comparison of the gland of Harder response and head-associated lymphoid tissue (HALT) morphology in chickens and turkeys

The immunofunctional response of the gland of Harder (GH) was compared in chickens and turkeys using an in vivo assay previously developed for use in chickens. The GH were surgically removed (GHx) from leghorn chicks at 1 day of age and from poults at 2 days of age. Intact birds of each species served as controls. During the fourth week of age, both GH-intact and GHx chicks were exposed to killed Brucella abortus antigen by the ocular or intraperitoneal route. One week later, serum and tears were collected and assayed for antibodies to B. abortus. In addition, all birds were killed at the end of the trial period, and the heads were fixed and processed for histologic examination. Various components of the head-associated lymphoid tissue (HALT) including the GH, nasal glands, lacrimal glands, lacrimal ducts, eyelid conjunctiva, and nasal cavity mucosa/submucosa, were evaluated microscopically using a scoring system to estimate quantity and degree of development of immune tissue in those sites. Results of all analyses indicate that functional response and morphology of the HALT are comparable in turkeys and chickens.

Investigation of renal protein loss in dogs with acute experimentally induced Ehrlichia canis infection

Urinary protein-to-creatinine ratios and serum albumin concentrations were measured in 8 adult male dogs experimentally inoculated with Ehrlichia canis. Urinary protein concentration increased significantly, but transiently, during the acute phase of infection. Urinary protein-to-creatinine ratios were highest (mean, 8.6) during the third and fourth weeks after infection, and decreased to less than 0.5 by 6 weeks after infection. Correspondingly, albumin concentration decreased significantly during the acute phase. Serum albumin concentrations were lowest (mean, 2.1 g/dl) the fourth week after infection and increased to greater than 3.0 g/dl by 11 weeks after infection. There was an inverse linear correlation between urinary protein-to-creatinine ratio and serum albumin concentration. The magnitude of proteinuria and its inverse relationship with serum albumin concentration suggested that hypoalbuminemia associated with acute E canis infection may be attributable primarily to increased renal loss of protein, rather than decreased hepatic synthesis as previously suggested. Another dog was subsequently inoculated with E canis from 1 of the experimentally infected dogs and a renal biopsy was performed during peak proteinuria (urinary protein-to-creatinine ratio = 22 and serum albumin = 1.1 g/dl). Immunofluorescent staining revealed mild to moderate deposits of anti-canine IgM, and to a lesser extent, anti-canine IgG and complement factor C3 in the glomerular tufts and mesangium. Ultrastructural evaluation revealed distortion and fusion of podocyte foot processes and increased microvilli on podocytes. These morphologic changes were consistent with transient glomerular leakage of protein of a magnitude that would significantly contribute to hypoalbuminemia during acute E canis infection. An underlying immunologic mechanism was suggested by positive glomerular immunofluorescence and previously described histologic findings.

Influence of antigen concentration, inoculation interval, number of exposures, type of housing, and placement concentration on the tear antibody response to Brucella abortus in chickens

A series of trials was run in leghorn chicks to examine select conditions affecting the tear antibody response to killed Brucella abortus antigen given by eyedrop administration. Specific conditions examined were concentration of antigen, number of antigen exposures, and interval between antigen exposures. Trials were also run to determine the earliest age at which the assay was functional in both broilers and leghorns. Two types of housing (isolators and battery cages) were examined, as were two levels of placement concentration, or bird density (0.32 and 0.64 ft. [0.03 and 0.06 m2]/chicken). All trials included intraperitoneally inoculated chicks as a comparison; tears as well as serum were assayed for antibodies. Of the various antigen regimens evaluated, two exposures of 20% B. abortus given 3 days apart was found to give a satisfactory antibody response in the tears 1 week later. Furthermore, response to B. abortus was found to be somewhat proportional to age, with the minimum age for a satisfactory response being 3 weeks in leghorns or 4 weeks in broilers. Statistically, there were no differences in antibody responses due to the types of housing or levels of placement used.

Effects of an Arkansas strain of infectious bronchitis vaccine on the head-associated lymphoid tissue (HALT)

Chicks were vaccinated with an Arkansas strain of infectious bronchitis virus (IBV) vaccine when they were 1 day (Trial 1) or 4 weeks old (Trial 2). Starting at 4 weeks 3 days of age, chicks in both trials were subjected to an assay that measures the immunofunctional response of the gland of Harder (GH), one of the components of the head-associated lymphoid tissue (HALT). The assay involved multiple ocular exposures to killed Brucella abortus antigen, after which tears were collected and titered for antibodies to B. abortus. Following this, select tissues from vaccinated and unvaccinated chicks were collected and examined microscopically for specific lesions. Both functional and structural alterations were detected in the HALT of IBV-vaccinated chicks. Antibody titers to B. abortus in vaccinated chicks were significantly lower (P less than 0.05) than in unvaccinated controls. Structurally, there were elevations (P less than 0.01) in the number of lymphoid cells and follicles found in the mucosal lining of the nasal cavity. This occurred in the vaccinated chicks of both trials. Otherwise, histologic changes were confined to the chicks vaccinated at 4 weeks of age (Trial 2). In that trial, there were elevations in lymphoid-cell and follicle numbers in the eyelid (P less than 0.01) and lacrimal gland (P less than 0.05).

Effect of infectious bursal disease virus vaccines on persistence and pathogenicity of modified live reovirus vaccines in chickens

Two commercially available live reovirus vaccines, alone or in combination with two infectious bursal disease virus (IBDV) vaccines, were evaluated for safety and efficacy in specific-pathogen-free leghorn chicks. Four trials were conducted to evaluate the vaccine combinations. At periodic intervals during the trials, tissues were collected and assayed for residual reovirus and examined for histological changes. Six weeks following reovirus vaccination, all treatment groups were challenged with a virulent field isolate of reovirus and sampled 1 week later for the final time. The two reovirus vaccines were safe and effective if given at 1 week of age, regardless of whether the vaccinates had been exposed to IBDV at 1 day. However, both reovirus vaccines persisted in the tendons of 1-day-old vaccinates. The effects of IBDV vaccines were generally minor and reflected by increases in the number of pre-challenge or post-challenge virus recoveries from some of the treatment groups receiving both type vaccines.

Decreased egg production in commercial laying hens fed zearalenone- and deoxynivalenol-contaminated grain sorghum

In an experiment to determine the effect of corn vs. grain sorghum on performance of laying hens, egg production decreased significantly in the grain sorghum-fed hens in each of two trials starting 24 weeks after the trials began. Necropsy of chickens fed both diets revealed buccal ulceration at the ventral aspect of the oral cavity and squamous metaplasia of the esophageal glands and submaxillary salivary glands. Lesions were much more severe in the sorghum-fed birds than in the corn-fed birds. Analysis of the grain sorghum and corn revealed the presence of mycotoxins. Zearalenone and deoxynivalenol were present in the grain sorghum, and a lower amount of deoxynivalenol and a trace of aflatoxin B1 were found in the corn. Although mycotoxin levels were low, interaction between these mycotoxins and others may have decreased egg production.

Canine pythiosis--isolation and identification of Pythium insidiosum

Pythium insidiosum was isolated from the subcutaneous tissue of a 1-year-old tan crossbreed dog and from the intestinal tract of an 18-month-old Samoyed male. Gomori's methenamine silver stain was superior to hematoxylin and eosin in demonstrating the organism in tissue sections. The agent was identified as P. insidiosum by zoospore formation in an aqueous yeast extract solution containing grass blades. Exoantigens produced in culture were shown to be identical to known P. insidiosum antigens by microimmunodiffusion.

The effect of Harderian adenectomy on the antibody response in chickens

Intact chicks and those that had their glands of Harder (GH) removed (GHx) at 1 day of age were studied for their response to optically or intraperitoneally (IP) applied antigens. Following exposure of the chicks to sheep red blood cells (SRBCs), killed Brucella abortus, or bovine serum albumin (BSA), serum and tear samples were collected and assayed for antibodies. Of the two sources of antibodies, the serum generally had higher levels than did the tears. The only exception to this occurred in the intact chicks inoculated by the eye, in which serum and tear levels were equivalent. With SRBCs, no difference could be detected between the two routes of inoculation. However, IP inoculation produced higher levels of antibody in the serum of intact and GHx chicks inoculated with B. abortus or BSA and in the tears of the GHx chicks exposed to B. abortus. Removal of the GH resulted in a consistent decrease in antibody levels in the tears, regardless of the route of exposure. Although this effect was noted with all three antigens, it was more pronounced in the trials using B. abortus and BSA. This finding is discussed in terms of describing the importance of the GH as a source of antibodies to optically applied antigens, and its importance as a route of circulating antibody egress. Furthermore, the feasibility of using the antibody response in tears to a test antigen is discussed as a means of measuring the immune status of a functioning GH.

Granulomatous uveitis in an owl

Granulomatous lens-induced uveitis was diagnosed in a mature male barred owl. Initial ocular examination revealed a large white mass in the left eye. Differential diagnoses for the mass included intraocular granuloma, neoplasia, foreign body, bacterial or fungal enophthalmitis, and fibrotic hematoma. After enucleation of the left globe, histologic examination revealed the mass to be a granulomatous inflammatory reaction to a posteriorly luxated, traumatized lens. Lens-induced uveitis should be considered whenever a bird has suffered lenticular trauma.

Persistence of commercial modified live reovirus vaccines in chicks

Four modified live reovirus vaccines were compared with a field isolate (81-176) of reovirus for safety in 1-day-old and 1-wk-old specific-pathogen-free chicks. At 1, 3, 5, and 7 wks after vaccination, blood, cloacal swabs, and hock tendon samples were collected and assayed for residual virus. Tendon samples were also examined microscopically and scored for histological changes. Vaccine efficacy was monitored by challenging chicks 7 wks postvaccination via the footpad with the 81-176 isolate. Serum samples were collected throughout the trials and assayed for reovirus antibodies using an enzyme-linked immunosorbent assay. In chicks vaccinated at 1 day of age, three of the four vaccine viruses were consistently recovered from the hock tendon tissues. Post-challenge virus recoveries were similarly positive for the same vaccine viruses. Histological lesion scores of the tendons paralleled the degree of virus recovery. In the chicks vaccinated at 1 wk old, none of the vaccine viruses were recovered, nor were tendon lesion scores substantially elevated. Following challenge, however, virus was recovered from all vaccinated groups.

Gossypol toxicosis in a herd of beef calves

A 6-month-old crossbred calf was examined as representative of a herd of calves experiencing dyspnea and death, with few other clinical signs of illness. Physical examination of the calf identified pleural and peritoneal effusion and poor body condition. The calf did not respond to supportive treatment, and necropsy of it and another calf from the herd identified congestive heart failure as the cause of death. Gossypol toxicosis was the cause of congestive heart failure in this herd; the source of the toxin was a cottonseed meal and cottonseed hull ration fed by the owner.

F strain Mycoplasma gallisepticum vaccination of post-production-peak commercial Leghorns and its effect on egg and eggshell quality

Forty-five-week-old commercial leghorns negative for antibodies to Mycoplasma gallisepticum (MG) and M. synoviae were vaccinated with high-passage F strain MG (FMG). Hens were confined in modified Horsfall-Bauer isolation units through 60 weeks of age. Egg production (% hen day) and parameters of egg and eggshell quality were monitored, including egg weight, eggshell strength, Haugh unit score, pimpling, and blood/meat spot incidence. Egg production was significantly lower (P less than 0.05) for FMG vaccinates than controls (down 5.76% and 5.80% in Trials 1 and 2, respectively). However, vaccinates and controls did not differ significantly in eggshell strength, shell thickness, pimpling, or blood/meat spot incidence. Haugh unit scores were significantly (P less than 0.05) greater for FMG vaccinates. At necropsy, all reproductive tracts appeared grossly normal. These studies suggest that high-passage FMG vaccination of post-production-peak hens does not adversely affect oviduct function.