Effects of light sources and intensity on broilers grown to heavy weights. Part 1: Growth performance, carcass characteristics, and welfare indices.

This study investigated the effects of light sources and light intensity on growth performance, carcass characteristics, and welfare indices of heavy broilers (>3.0 kg) in 4 trials with 2 replications per trial. A total of 960 one-day-old Ross×Ross 708 chicks (30 males/30 females/room) were randomly distributed into 16 environmentally controlled rooms at 50% RH. A 4×2 factorial treatment structure evaluated 4 light sources (incandescent [ICD, standard], compact fluorescent [CFL], neutral light emitting diode [Neutral-LED], and cool poultry specific filtered LED [Cool-PSF-LED]) and 2 levels (5 lx, 20 lx) of light intensities. Each of the 4 light sources was paired with one of the 2 light intensities. Birds were fed the same diet with a 4-phase feeding program (starter, grower, finisher, and withdrawal). Feed and water were provided ad libitum. Birds and feed were weighed on one, 14, 21, 28, 42, and 56 d of age for growth performance. All mortality was recorded daily and feed conversion was adjusted for mortality. Immune response was determined on d 28 to d 35, whereas other welfare indices were performed on d 42 and 49, respectively. At d 56 of each trial, 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 weights of birds reared under Cool-PSF-LED were different (P≤0.05) in comparison to birds reared under ICD. However, FI, FCR, and mortality were not affected by treatments. There was no effect of treatments on fat or breast and tender weights and yields. In addition, there was no effect of treatments on ocular development, immune response, and other welfare indices, suggesting that the light sources evaluated did not compromise welfare of heavy broilers. It was concluded that the 3 light sources evaluated in this study may be suitable for replacement of ICD light source in poultry facilities to reduce energy cost and optimize production efficiency.

Effects of color temperatures (Kelvin) of LED bulbs on blood physiological variables of broilers grown to heavy weights.

Light-emitting diode (LED) lighting is being used in the poultry industry to reduce energy usage in broiler production facilities. However, limited data are available comparing efficacy of different spectral distribution of LED bulbs on blood physiological variables of broilers grown to heavy weights (>3 kg). The present study evaluated the effects of color temperature (Kelvin) of LED bulbs on blood physiological variables of heavy broilers in 2 trials with 4 replicates/trial. The study was a randomized complete block design. Four light treatments consisted of 3 LED light bulbs [2,700 K, (Warm-LED); 5,000 K, (Cool-LED-#1); 5,000 K, (Cool-LED-#2)] and incandescent light (ICD, standard) from 1 to 56 d age. A total of 960 1-day-old Ross × Ross 708 chicks (30 males/room 30 females/room) were equally and randomly distributed among 16 environmentally controlled rooms at 50% RH. Each of the 4 treatments was represented by 4 rooms. Feed and water were provided ad libitum. All treatment groups were provided the same diet. Venous blood samples were collected on d 21, 28, 42, and 56 for immediate analysis of selected physiological variables and plasma collection. In comparison with ICD, Cool-LED-#1 had greater (P < 0.05) effects on pH, partial pressure of CO2(pCO2), partial pressure of O2(pO2), saturated O2(sO2), and K⁺. However, all these acid-base changes remained within the normal venous acid-base homeostasis and physiological ranges. In addition, no effect of treatments was observed on HCO(3)(-), hematocrit (Hct), hemoglobin (Hb), Na⁺, Ca²âº, Cl⁻, mean corpuscular hemoglobin concentration (McHc), osmolality, and anion gap. Moreover, blood glucose concentrations were not affected by treatments. This study shows that the 3 LED light bulbs evaluated in this study may be suitable for replacement of ICD light sources in commercial poultry facilities to reduce energy cost and optimize production efficiency without inducing physiological stress on broilers grown to heavy weights.

Effects of different vaccine combinations against Mycoplasma gallisepticum on the digestive and reproductive organ characteristics of commercial egg-laying hens.

Mycoplasma gallisepticum (MG) is a major and economically significant pathogen of avian species. When administered before lay, F-strain MG (FMG) can reduce egg production during lay, but the ts-11 strain of MG (ts11MG) does not exert this effect. Two trials were conducted to determine the effects of pre-lay vaccinations of ts11MG, MG-Bacterin (MGBac), or their combination, in conjunction with an FMG vaccination overlay after peak production on the digestive and reproductive organ characteristics of Hy-Line W-36 layers housed in biological isolation units (4 units per treatment, 10 birds per unit). The following vaccination treatments were administered at 10 wk of age (woa): 1) Control (no vaccinations); 2) MGBac; 3) ts11MG; and 4) ts11MG and MGBac combination (ts11MG+MGBac). At 45 woa, half of the birds were vaccinated with a laboratory stock of high passage FMG. In both trials, parameters determined in 4 birds per unit at 55 woa included: BW; fatty liver hemorrhagic syndrome incidence; mean number of mature ovarian follicles; ovarian, oviduct, and small intestine weights; and the weights and lengths of the various portions of the oviduct and small intestine. Treatment effects were observed for the weights of the entire small intestine and the duodenum, jejunum, and ileum, as percentages of BW; and for vagina weight as a percentage of total oviduct weight. In general, the weights of the small intestine and its 3 components were increased in response to the FMG vaccine that was administered at 45 woa. An FMG vaccination at 45 woa may increase relative intestine weight in layers; however, use of a prelay MGBac vaccine alone or in combination with ts11MG, with or without an FMG overlay, does not affect the gross characteristics of their digestive and reproductive organs, and may be used without having an adverse effect on their performance, as was observed in a previous companion study.

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.

Effects of different vaccine combinations against Mycoplasma gallisepticum on the internal egg and eggshell characteristics of commercial layer chickens 1,2,3.

Live F-strain Mycoplasma gallisepticum (FMG) vaccines are presently being used to help control field-strain MG outbreaks. However, they may exert some adverse effects on egg production. Live strains of MG of lesser virulence as well as killed vaccines have little or no effect on egg production, but afford lower levels of protection. This has led to research investigating their use in combination with a subsequent overlay vaccination of FMG given later in the production cycle. In the present study, 2 trials were conducted to investigate the effects of prelay vaccinations of live and killed MG vaccines or their combination, in conjunction with an FMG vaccine overlay after peak production, on the egg characteristics of commercial layers. The following vaccination treatments were administered at 10 wk of age (woa): 1) unvaccinated (Control), 2) MG-Bacterin (MGBac) vaccine, 3) ts-11 strain MG (ts11MG) vaccine, and 4) MGBac and ts11MG combination (MGBac + ts11MG). At 45 woa, half of the birds were overlaid with an FMG vaccine. In each trial, internal egg and eggshell parameters including egg weight (EW), Haugh unit score (HU), eggshell breaking strength (EBS), percentage yolk weight (PYW), percentage albumen weight (PAW), percentage eggshell weight (PSW), eggshell weight per unit surface area (SWUSA), percentage yolk moisture (PYM), and percent total lipids (PYL) were determined at various time periods between 21 and 52 woa. At 28 woa, SWUSA was lower in the ts11MG and MGBac + ts11MG groups compared to the Control group. Conversely, at 43 woa, SWUSA was higher in the ts11MG than in the MGBac group. Between 23 and 43 woa, PYL was higher in the MGBac and ts11MG groups in comparison to the Control group. In conclusion, vaccination with MGBac alone or in combination with ts11MG at 10 woa with or without an FMG vaccine overlay at 45 woa does not adversely affect the internal egg or eggshell quality of commercial layers throughout lay.

The impact of deposition site on vaccination efficiency of a live bacterial poultry vaccine.

Vaccines are utilized within the poultry industry to minimize disease-associated losses and spray vaccination is a commonly utilized means for the mass application of poultry vaccines. During this process, vaccine-laden particles are deposited upon target areas (e.g., eyes, nares, and oral cavity) resulting in the direct internalization of the vaccine. However, particles are also deposited on nontarget areas such as the exterior of the subject and its surrounding environment. To better determine the fate of particles deposited upon nontarget areas and the impact of deposition site on the efficiency of vaccine application, a live bacterial poultry vaccine (AviPro(®) MG F) was applied via spray using a spray cabinet with a slotted partition allowing for head-only, body-only, and whole-bird spray application. At 11 wk age, Hy-Line(®) W-36 pullets (n = 280) were allocated equally among 7 treatments including: nonvaccinated controls, pullets spray-vaccinated at the manufacturer's recommended dose (1X) in a site-specific manner (head-only, body-only, and whole-bird), pullets spray-vaccinated at 5X the recommended level (body-only), pullets vaccinated by manual eye-drop application (1X), and pullets eye-drop vaccinated at a level approximating that achieved during the spray vaccination process (1/700X). At 6 to 7 wk postvaccination, vaccination efficiency was assessed via serological-based assays [serum plate agglutination (SPA) and ELISA] and the detection of vaccine-derived in vivo populations. Results indicate an additive contribution of the vaccine deposited on the body to the overall vaccination efficiency of this live bacterial live poultry vaccine.

Effects of genetic strain and light intensity on blood physiological variables of broilers grown to heavy weights.

The effects of genetic strain, light intensity, and their interaction were examined on blood physiological variables of broilers maintained in environmentally controlled rooms in each of 5 trials. The study consisted of a 2 × 5 factorial arranged in a randomized complete block design with 10 treatments of 2 strains (Ross × Ross 308 and 708) and exposure to 5 light intensities (25, 10, 5, 2.5, and 0.2 lx) with chicks equally and randomly distributed at 1 d of age. The 5 light intensities were randomly assigned from 22 to 56 d of age. Feed and water were provided ad libitum. Venous blood samples were collected on d 21 (base line), 28, 42, and 56 of age. Main effects indicate that Ross × Ross 308 significantly (P ≤ 0.05) increased BW, partial pressure of CO2, Ca(2+), Na(+), Cl(-), and thyroxine, along with significantly (P ≤ 0.05) reduced pH level, partial pressure of O2, HCO3(-), and triiodothyronine in comparison with Ross × Ross 708. No main effect of light intensity was observed on all examined variables. In addition, no significant main effects were observed for strain, light intensity, or their interaction on saturated O2, hematocrit, hemoglobin, K(+), mean corpuscular hemoglobin concentration, glucose, osmolality, and anion gap. Physiologically, although Ross × Ross 308 had a significantly increased BW in comparison with Ross × Ross 708, Ross × Ross 708 showed a significant (P ≤ 0.05) increase in partial pressure of O2 and triiodothyronine along with lower blood partial pressure of CO2 and thyroxine. The results of this study supplement current knowledge of physiological response to differing lighting levels and may be used to establish the normal blood values for commercial broilers grown to heavy weights. Plasma corticosterone was not affected by either treatments or strain, indicating that the treatments did not induce physiological stress in broilers.

Effects of Mycoplasma gallisepticum vaccination on serum α1-acid glycoprotein concentrations in commercial layer chickens.

Increases in circulating acute phase protein (APP) levels occur in reaction to systemic infections in animals. However, no previous research has been conducted to monitor possible changes in APP levels of birds in response to prelay vaccinations of various live attenuated Mycoplasma gallisepticum vaccines in conjunction with their subsequent use as an overlay vaccine during the production period. Serum concentrations of the APP, α1-acid glycoprotein (AGP), were determined on d 0, 1, 3, 7, 14, and 28 after subjecting commercial laying hens to one of the following treatments at 10 wk of age (woa): 1) control (no vaccination); 2) ts-11 strain M. gallisepticum (ts11MG) vaccination; 3) M. gallisepticum-bacterin (MGBac) vaccination; and 4) ts11MG and MGBac combination (ts11MG & MGBac) vaccination. Furthermore, at 45 woa, the birds in half of the units assigned to each treatment group were vaccinated with high-passage F-strain M. gallisepticum (HpFMG). Birds in treatment 1 that were (single control) and were not (double control) vaccinated with HpFMG, and birds in treatments 2, 3, and 4 that were vaccinated with HpFMG were further tested during lay on d 0, 1, 3, 7, 14, and 28 after vaccination. On d 7, 14, and 28 postvaccination at 10 woa, the ts11MG & MGBac, ts11MG, and MGBac group AGP concentrations were not different from one another, but all were higher than those in the control group. Similarly, on d 3, 7, and 14 postvaccination, the single control, and the MGBac ts11MG, and ts11MG & MGBac treatment groups that were later vaccinated with HpFMG at 45 woa, were not different, but all were higher than that in the double control group. In conclusion, elevated circulation AGP concentrations may be used to detect and confirm subclinical infections in pullets up to 28 d after having been vaccinated with ts11MG, MGBac, or their combination. Furthermore, in association with depressed performance, elevated serum AGP concentrations in layers may be used to confirm HpFMG infections up to 28 d after its use as a vaccine.

Production characteristics of Hy-Line W36 laying hens hatched from white and tinted eggs.

Eggshell color can greatly influence visual appeal of table eggs, and within the United States, table eggs are normally sorted and marked according to eggshell color to maximize consumer appeal. Recently, table egg producers have noted increased incidence of "off-color" or tinted (TT) eggs derived from white egg laying breeder hens. Therefore, the objectives of this study were to determine the production characteristics and resultant eggshell color of laying hens hatched from different colored eggs. Hy-Line W36 eggs were obtained from a commercial breeder operation and eggshell color was assessed with a colorimeter to separate eggs into groups of tinted (TT) and nontinted (NT) eggs before incubation. Treatment groups were placed into separate hatching trays. At hatching, chicks from each treatment group were individually wing-banded. Pullets were randomly allocated into cages according to treatment groups at 18 wk. Birds were placed into individual cages, with 5 consecutive cages representing a treatment replicate. Each treatment was replicated 24 times for a total of 120 birds per treatment and fed a nutritionally complete layer diet. Production performance was evaluated from 18 to 34 wk of age. Average weekly egg production was calculated. Feed intake, egg weights, egg mass, feed conversion ratio, and egg color were analyzed every 2 wk. Birds were weighed every 4 wk until completion of the study. Birds hatched from TT eggs had significantly increased BW throughout the experimental period. Hen-day egg production was significantly different when compared with the NT treatment at 19 and 20 wk of age. Eggshell color was also found to be significantly different for the NT and TT groups with TT eggs being significantly further from true white. Selection of progeny based on eggshell color may be a criterion for selecting white egg layers as layers hatched from TT eggs resulted in more off-color eggs, which may affect consumer acceptance for buying white table eggs.

Effects of live and killed vaccines against Mycoplasma gallisepticum on the performance characteristics of commercial layer chickens.

Different vaccine strains of Mycoplasma gallisepticum have been used on multiple-age commercial layer farms in an effort to protect birds against virulent field-strain infections. Use of the F-strain of M. gallisepticum (FMG), as an overlay vaccine during lay, may be necessary because of the lower level of protection afforded by M. gallisepticum vaccines of low virulence given before lay. Two replicate trials were conducted to investigate effects of live and killed M. gallisepticum vaccines administered individually and in combination before lay, in conjunction with an FMG vaccine overlay after peak egg production (EP), on the performance characteristics of commercial layers. The following treatments were utilized at 10 wk of age (woa): 1) control (no vaccinations); 2) ts11 strain M. gallisepticum (ts11MG) vaccine; 3) M. gallisepticum-Bacterin vaccine (MG-Bacterin); and 4) ts11MG and MG-Bacterin vaccines combination. At 45 woa, half of the birds were overlaid with an FMG vaccine. Hen mortality, BW, egg weight, percentage hen-day EP, egg blood spots, and egg meat spots were determined at various time periods between 18 and 52 woa. The data from each trial were pooled. Treatment did not affect performance in interval I (23 to 45 woa). However, during interval II (46 to 52 woa), the EP of control and MG-Bacterin-vaccinated birds that later received an FMG vaccine overlay was lower than that in the other treatment groups. Furthermore, treatment application reduced bird BW during interval II. Despite the effects on BW and EP, no differences were observed for egg blood or meat spots among the various treatments. It is suggested that the vaccination of commercial layers before lay with ts11MG, but not MG-Bacterin, may reduce the negative impacts of an FMG overlay vaccination given during lay. These results establish that the vaccination of pullets with ts11MG in combination with the vaccination of hens with an FMG overlay, for continual protection against field-strain M. gallisepticum infections, may be used without suppressing performance.

Effects of strain and light intensity on growth performance and carcass characteristics of broilers grown to heavy weights.

Effects of genetic strain and light intensity on growth performance and carcass characteristics of broilers grown to heavy weights were investigated. The experimental design was a randomized complete block design. Treatment structure was a 2 × 5 factorial arrangement with the main factors being strain (Ross × Ross 308, Ross × Ross 708) and light intensity (25, 10, 5, 2.5, and 0.2 lx) with trial as replicates. In each of the 5 trials, chicks of 2 different strains of the same commercial hatchery were equally and randomly distributed into 10 environmentally controlled rooms (5 rooms/strain) at 1 d of age at 50% RH. Each room was randomly assigned 1 of 5 light intensities from 22 to 56 d of age. Feed and water were provided ad libitum. Birds and feed were weighed on 0, 14, 28, 42, and 56 d of age for growth performance. Humoral immune response was determined on d 28, whereas ocular and blood samples were performed on d 42 and 55, respectively. On d 56, 20 (10 males and 10 females) birds/strain from each room were processed to determine weights and yields. Genetic strain was significant (P ≤ 0.05) for most of the examined variables, where Ross × Ross 308 had better growth performance and meat yield in comparison with Ross × Ross 708. Although, there was no main effect of light intensity on growth performance and meat yield, results indicated that birds under 10 and 5 lx intensities showed slightly better growth performance and meat yield compared with birds under 25, 2.5, and 0.2 lx in both strains. There was no effect of strain and light intensity on ocular indices, immune response, plasma corticosterone levels, and mortality. This study shows the positive influence on profits to commercial poultry facilities that are using a low lighting environment to reduce energy cost, optimize feed conversion, and maximize production without compromising the welfare of the broilers.

Interactive effects of photoperiod and light intensity on blood physiological and biochemical reactions of broilers grown to heavy weights.

The effects of photoperiod, light intensity, and their interaction on blood acid-base balance, metabolites, and electrolytes in broiler chickens under environmentally controlled conditions were examined in 2 trials. A 3 × 3 factorial experiment in a randomized complete block design was used in this study. In each trial, all treatment groups were provided 23L:1D with 20 lx of intensity from placement to 7 d, and then subjected to the treatments. The 9 treatments consisted of 3 photoperiods [long/continuous (23L:1D) from d 8 to 56, regular/intermittent (2L:2D), and short/nonintermittent (8L:16D) from d 8 to 48 and 23L:1D from d 49 to 56, respectively] and exposure to 3 light intensities (10, 5.0, and 0.5 lx) from d 8 through d 56 at 50% RH. Feed and water were provided ad libitum. Venous blood samples were collected on d 7, 14, 28, 42, and 56. Main effects indicated that short/nonintermittent photoperiod significantly (P < 0.05) reduced BW, pH, partial pressure of O2, saturated O2, Na(+), K(+), Ca(2+), Cl(-), osmolality, triiodothyronine (T3), and total protein along with significantly (P < 0.05) elevated partial pressure of CO2, hematocrit, hemoglobin, and lactate concentrations. In addition, there were no effects of photoperiod on HCO3(-), glucose, anion gap, and thyroxine (T4). Plasma corticosterone was not affected by photoperiod, light intensity, or their interaction. There was no effect of light intensity on most of the blood variables examined. Acid-base regulation during photoperiod and light intensity exposure did not deteriorate despite a lower pH and higher partial pressure of CO2 with normal HCO3(-). These results indicate that continuous exposure of broiler chickens to varying light intensities had a minor effect on blood physiological variables, whereas the short photoperiod markedly affected most blood physiological variables without inducing physiological stress in broilers.

Impact of fowlpox-vectored Mycoplasma gallisepticum vaccine Vectormune FP MG on layer hen egg production and egg quality parameters.

This study was conducted to determine the impact of vaccination with Vectormune FP MG on egg production and egg quality characteristics of Single Comb White Leghorn hens. Due to questions of the efficacy of this vaccine in preventing Mycoplasma gallisepticum-mediated pathology, the ability of this vaccine to protect against postproduction-peak egg losses associated with F-strain M. gallisepticum (FMG) vaccination was also investigated. Vaccination with Vectormune FP MG did not result in any significant change in egg production or egg quality parameters compared with control (unvaccinated) hens. Subsequent revaccination with FMG at 45 wk of age (woa) yielded no impact on egg production or egg quality parameters of Vectormune FP MG vaccinated hens, unlike prior results for postproduction-peak vaccination of M. gallisepticum-clean hens with FMG, which exhibited a drop in egg production of approximately 6%. No difference in egg size distribution was observed for any of the treatment groups before or after FMG revaccination. These results suggest that hens can be safely vaccinated with Vectormune FP MG as pullets and can be revaccinated with a live M. gallisepticum vaccine such as FMG at a later date with no deleterious effects on egg production or egg or eggshell quality parameters.

Effect of infection route and concurrent infectious bronchitis virus vaccination on Mycoplasma gallisepticum disease pathology in an experimental model.

The study of Mycoplasma gallisepticum (MG) infection is needed, not only to understand the disease process but also to understand the mechanisms by which MG vaccines protect the host. Many model systems have been used to study the MG disease process. This work compared two different routes of infection (intratracheal versus eye drop) in commercial pullets, looking for differences in the pathology (air sac and tracheal lesion scores, and tracheal mucosal thickness) and the humoral immune response (measured by serum plate agglutination) of the host. The impact of concurrent infectious bronchitis virus vaccination on disease outcomes was also determined. Results showed that the intratracheal route of MG infection caused increased air sac and tracheal lesion scores and tracheal mucosal thickness at one week post infection, whereas the eye drop route produced no noticeable pathology. However, tracheal mucosal thicknesses of intratracheally challenged pullets were not statistically different from those of the eye drop challenged or control pullets at two and three weeks post infection. Concurrent infectious bronchitis virus vaccination had a negligible outcome on disease pathology. Vaccination of specific-pathogen-free chickens with the F-strain MG vaccine completely protected them against the effects of MG intratracheal infectious challenge, as evidenced by a lack of significant difference in air sac and tracheal lesion scores and tracheal mucosal thickness with those of unchallenged media control chickens.

A comparative study of live attenuated F strain-derived Mycoplasma gallisepticum vaccines.

Commercially available attenuated strains of Mycoplasma gallisepticum (MG) are commonly used within the layer industry to control MG-induced mycoplasmosis. Among these are two live MG vaccines derived from the moderately pathogenic MG "chick F" strain. In the present study, the commercially available F strain derivatives were compared for their ability to elicit seroconversion, persist in vivo, and protect against virulent MG-induced airsacculitis. In addition, a noncommercial laboratory-derived high-passage F strain isolate was included in the study. Commercial (Hy-Line W-36) layers were placed in biological isolation units at 9 wk of age (woa). At 10 woa, birds within each biological isolation unit were treated via eye-drop application with one of the three F strain-derived vaccines at one of four levels (1x, 10(-1)x, 10(-2)x, or 10(-3)x). For the commercially available F strain derivatives, 1x equaled the manufacturer's recommended dose. The 1x dose of the noncommercial laboratory-maintained F strain derivative equaled 20 microl of a 48 hr culture. For wk 1-6 postvaccination (p.v.), sera were collected weekly from each bird, and seroconversion was assessed via serum plate agglutination (SPA). Virulent MG (strain R(low)) challenge occurred via intratracheal inoculation at 7 wk p.v. Necropsies were subsequently performed to assess challenge-associated airsacculitus. For each F strain derivative applied at 1x and 10(-1)x, 100% seroconversion, as measured by SPA, was demonstrated by 6 wk p.v., and rates at the 10(-2)x dosage were 10% and 90% for the commercial vaccines and 60% for the laboratory-derived strain in this period. Following challenge, airsacculitis was observed in 66.67% of the nontreated controls but not in any 1x- or 10(-1)x-treated bird independent of applied F strain derivative.

Mycoplasma gallisepticum transmission: comparison of commercial F-strain vaccine versus layer complex-derived field strains in a tunnel ventilated house.

Two simultaneous trials were conducted using a commercially available, live, F strain Mycoplasma gallisepticum (FMG) vaccine (trial 1) or 2 inocula of layer complex-derived MG strains (LCD-MG; trial 2). In each of the 2 trials, 4 commercial turkeys were housed in each of 2 adjoining pens immediately adjacent to air inlets. The turkeys (8/trial) were inoculated in the right eye with either a 1× dose of FMG (trial 1) or with 0.02 mL of 1 of 2 actively growing LCD-MG inocula (4 turkeys/inoculum; trial 2). In each of the 2 trials, one pen housing 4 inoculated turkeys was maintained without the addition of other poultry, whereas 16 MG-free broilers and 4 MG-free layers were added to the other pen of 4 inoculated turkeys. Within each of the trials and at increasing intervals, either 4 layers (3 pens) or 4 turkeys (3 pens) were placed down-airstream from the inoculated pens. The distance of the first pen from the inoculated turkeys was separated by the width of one pen that was empty. Succeeding down-airstream pens were situated such that the empty distance (absence of any poultry) between pens that contained poultry doubled from one pen to the next such that the final pen that contained poultry had 4 empty pens between it and the next up-airstream pen that also contained poultry. At 106 d postinoculation, all poultry were bled, swabbed for MG from the choanal cleft, and then euthanized and necropsied. No commingled poultry in trial 1 (FMG), whether inoculated (turkeys) or commingled (layers and broilers), died during the course of the trial, and 5 of the 8 FMG-vaccinated turkeys exhibited serological but not cultural evidence of mycoplasmosis. In trial 2 (LCD-MG), 2 commingled broilers died and no inoculated turkeys exhibited either serological or cultural evidence of mycoplasmosis. In both trials, no poultry housed down-airstream from the inoculated poultry showed evidence of clinical signs of mycocplasmosis and none showed either serological or cultural evidence of mycoplasmosis.

Research Note: Age-related effects of feeder space availability on welfare of broilers reared to 56 days of age Part 2: Blood physiological variables.

Consumption of poultry meat has increased dramatically due to the relative price-competitiveness as compared to other meat products. The rapid growth and increased production efficiency of modern genetic strains is perceived to negatively impact the welfare of the animal. Hematological analyses such as acid-base balance provide a thorough evaluation of the welfare in both animals and humans. This study investigated the effects of feeder space availability on welfare of broilers grown to heavy weights using blood physiological variables. The study was a randomized complete block design. In each of the 2 trials, a total of 1,440 one-d-old Ross × Ross 708 chicks (straight-run) were obtained from a commercial hatchery. Chicks were equally and randomly allocated to 32 pens based on feeder space treatment. Treatments were 4 different feeder space allocations: 2.3 (Single feeder), 2.30, 4.60, and 6.90 cm/bird. To maintain uniform bird:feeder floor space, 3 feeders were installed in each pen, except for the single feeder pen. Blood samples (3 mL) were collected from the brachial wing vein of 3 birds per pen on d 27 and 55, which were then analyzed immediately for whole blood physiological variables. The remaining blood samples were centrifuged to collect plasma that was used for corticosterone and thyroid hormones analysis. Results show there was no effect of feeder space on most of the selected physiological variables, but age had significant effects on most of the examined variables. However, all observed changes were within physiological ranges. Plasma corticosterone and blood glucose were not affected by feeder space and age, indicating absence of physiological stress. The results are in broad agreement with those reported in the literature and on homeostatic variation of broilers grown to heavy weights. In conclusion, expanding feeder allowance does not enhance the welfare of broilers grown to heavy weights.

Onset of the humoral immune response of layer chicks vaccinated in ovo with strain F Mycoplasma gallisepticum vaccine and evidence of male-biased mortality.

Previous trials in which layers were in ovo-vaccinated against strain F Mycoplasma gallisepticum (FMG) showed that nearly 50% of the birds produced IgM antibody against FMG at 6 wk of age (WOA). Standard FMG vaccination application at 9 or 10 woa, result in this percentage at approximately 15 woa. This study investigated when FMG in ovo-vaccinated birds initiate a humoral immune response prior to 6 wk, and if sex influences this response. Hy-Line W-36 embryonated eggs were either not vaccinated (controls) or in-ovo vaccinated with a 50 µL volume of a 10-6 dilution of Poulvac MycoF vaccine (Zoetis). For each treatment group, 384 straight-run chicks were reared. At hatch and at 2, 3, 5, 7, 14, 21, and 28 d post-hatch, 54 birds per treatment were individually weighed and a blood sample was collected for Mycoplasma gallisepticum (MG) IgM antibody detection. ELISA was run on blood samples at 14, 21, and 28 d to distinguish IgG antibody production. At each age, BW was not different between vaccinated and control chicks (all P > 0.19). Males, however, outweighed females starting at d 5 (P = 0.02). Mortality was 1.0% for the control birds and 12.2% for the FMG birds during the first 2 wk. The majority (72.3%) of the mortalities in the FMG group were male. The percentage of control and FMG in ovo-vaccinated birds with IgM antibody production was 0% and 1.9% on d 7, 0% and 31.5% on d 14, 1.9% and 55.9% on d 21, and 0% and 60.6% on d 28, respectively. IgG antibody production in the FMG in ovo-vaccinated birds was 0.0% at 14 d, 2.9% at 21 d, and 21.2% at 28 d of age. All control birds tested negative for FMG-IgG production. In conclusion, the earliest detection of MG antibodies after in ovo vaccination with live FMG occurred at 7 d. Male layer chickens were more susceptible to the effects of an in ovo FMG vaccine than females.

Serologic response of roosters to gradient dosage levels of a commercially available live F strain-derived Mycoplasma gallisepticum vaccine over time.

Spray application is a commonly used, time- and labor-efficient means to deliver live Mycoplasma gallisepticum (MG) vaccine to laying hens in commercial production facilities. The dosage of vaccine received by spray-vaccinated birds can vary due to variation in the spray plume and the vaccine suspension droplet trajectory. In this study, a total of 48 Hy-Line W-36 males were placed individually in isolation units following eye-drop application of gradient levels (1 x, 10(-1) x, 10(-2) x, 10(-3) x, 10(-4) x, 10(-5) x, 10(-6) x, and unvaccinated control) of the MG vaccine. The determined titer associated with a 1 x dose was 2 x 10(6) colony-forming units/dose. Serologic response was assessed weekly following vaccination via serum plate agglutination (SPA) for weeks one through seven postvaccination (p.v.). In addition, immunologic response was assessed at 5, 6, and 7 wk p.v. via MG enzyme-linked immunosorbent assay (ELISA). As indicated by SPA analyses, a 1 x dose of vaccine resulted in 100% seroconversion, and dose levels of 10(-1) x and 10(-2) x resulted in 75% and 37.5% seroconversion, respectively, at 6 wk p.v. The MG ELISA results at 6 wk p.v. demonstrated immunologic responses in 100%, 57.1%, and 28.6% of the 1 x, 10(-1) x, and 10(-2) x dosed birds, respectively. The lower dosage levels of 10(-3) x, 10(-4) x, 10(-5) x, and 10(-6) x did not elicit a response from any bird at 6 wk p.v. Utilizing the SPA data, a logistic regression model was used to determine the relationship between dosage level and seroconversion rate (R2 = 0.999 with a standard error of prediction of 1.6%). The model predicted a required effective dosage of 0.26 x for 90% seroconversion at 6 wk p.v. under test conditions.

Effects of single and combined Mycoplasma gallisepticum vaccinations on blood electrolytes and acid-base balance in commercial egg-laying hens.

A previous study from our laboratory on F-strain Mycoplasma gallisepticum-inoculated layers showed a significant increase in arterial partial pressure of oxygen (pO(2)), which is generally associated with an oxygen-dependent improvement in tissue oxygenation. The aim of this study was to determine whether a killed (bacterin) and live TS-11-strain M. gallisepticum (TS-11-MG) vaccine treatment combination could further enhance the arterial pO(2) levels in layer chickens. The experiment was conducted in 2 trials and arranged in a completely randomized experimental design with 4 treatments. The treatments consisted of a control M. gallisepticum, bacterin, TS-11-MG, and bacterin + TS-11-MG combined, with all treatments receiving the R low strain of MG at 30 wk of age (WOA). In each of the 2 trials, 160 one-day-old MG-free pullets were raised to 10 WOA and were transported to a poultry disease isolation facility. Sixteen isolation units were divided into 4 treatment groups, and each of the 4 treatment groups had 4 replication units, with 10 birds/unit (40 birds/treatment). Venous blood samples were collected at the termination of the study at 56 WOA. The TS-11-MG-vaccinated chickens had a higher (P ≤ 0.05) blood pO(2) and a lower (P ≤ 0.05) partial pressure of CO(2) when compared with the control and combined MG-vaccinated groups. However, no significant blood pO(2) differences were observed between the bacterin and TS-11-MG treatment groups. Hematocrit and blood concentrations of hemoglobin were not statistically different among treatments, but were numerically higher in the TS-11-MG treatment group. There was a significant (P ≤ 0.05) treatment effect on blood concentrations of Na(+), Ca(2+), and anion, but no significant effect on glucose, cholesterol, triglyceride, or osmolality. These data suggest that the inoculation of layers with TS-11-MG was more effective in elevating pO(2) than was inoculation with TS-11-MG + bacterin combined.