Control Flock Research Articles

Evaluating the dynamics and efficacy of a live, attenuated Mycoplasma anserisalpingitidis vaccine candidate under farm conditions

ABSTRACT The aim of the present study was to monitor the dynamics and to measure the safety and efficacy of a live, attenuated, thermosensitive Mycoplasma anserisalpingitidis vaccine candidate, namely MA271, in geese breeder flocks under field conditions. Two rearing flocks were vaccinated with MA271 at 4 weeks of age and boosted at 24 weeks of age by cloaca inoculation (1 ml) and eye-dropping (60 µl). The geese then were transported to multi-aged breeding farms. Two breeding flocks served as controls. Colonization of the cloaca by MA271 showed 75% maximum prevalence between 4 and 6 weeks after the first vaccination. Then the prevalence decreased to 25% until the cooler, humid fall months which coincided with the booster vaccination. Boosting raised cloacal colonization to 100%. No clinical signs were observed in the vaccinated birds. After transportation to five multi-aged breeding farms, the wild-type strain appeared as well as MA271 in three flocks. In one flock, the wild-type strain completely displaced MA271, while in one flock only MA271 was detected. Only wild-type strains were detected in the control flocks; however, due to an HPAI outbreak, both flocks were exterminated before the end of the study. Based on the available data, the median percentage of infertile eggs was 3.7-5.1% in the MA271 vaccinated flocks, and 7.7% in the non-vaccinated flock. In conclusion, MA271 can colonize the cloaca of geese under field conditions. MA271 proved to be safe and presumably protects against M. anserisalpingitidis-induced reproduction losses.

Holo-analysis of the effects of xylo-oligosaccharides on broiler chicken performance

ABSTRACT 1. Xylo-oligosaccharides (XOS) stimulate proliferation of beneficial bacteria in the gastrointestinal tract of broiler chickens. This results in enhanced utilisation of dietary non-starch polysaccharides and increased production of valuable short-chain fatty acids. However, these positive effects do not always translate into improved bird productive performance, with inconsistent performance responses observed between bird trials. 2. A holo-analysis was conducted to determine the effects of supplementing XOS into broiler diets on bird feed intake, body weight gain, feed conversion and mortality. This was done by comparing the XOS supplemented treatment to the control treatment. A total of 53 studies which met the criteria for inclusion were used in the analysis. 3. The results showed that XOS had a notable positive impact on bird mortality; XOS reduced mortality by 0.69% for every 1% increment in the control group. XOS supplementation induced a positive effect on the feed conversion ratio (FCR). However, the efficacy of XOS at improving FCR was dependent on the efficiency of the control group (performance of the flock), and the concentration of total arabinoxylan, protein and phytase in the diet. There were insufficient data points to predict the effect of XOS on body weight and feed intake. 4. In conclusion, the holo-analysis revealed that supplementing XOS to broiler chicken diets reduces bird mortality. XOS can also improve FCR, but the scale of response is dependent on the diet composition and control flock performance. Additional studies are required to confirm the effects of XOS on body weight and feed intake.

Effects of a novel, non-invasive pre-hatch application of probiotic for broilers on development of cecum microbiota and production performance

BackgroundProbiotics are used in the broiler industry to increase production performance. Most often a probiotic is applied by mixing it in the feed, but studies have shown that earlier application may be advantageous. Therefore, in ovo application where the probiotic is administrated into the egg before hatch has been investigated as an alternative application method. However, in ovo application may impact hatchability negatively and may not be feasible at all hatcheries. The purpose of this study was to investigate the effect of a novel non-invasive method for mass application before hatch. The probiotic (E. faecium 669) was applied as a single dose by spray on the unhatched eggs and production performance and development of the cecal microbiota until slaughter was compared with a control flock. Through 16S rRNA sequencing of cecal samples from 25 broilers at day 7, 21 and 37 we compared the microbiota composition and richness for each group. The study was repeated for additional recording of production performance and re-isolation of the probiotic E. faecium from the intestine.ResultsIn both trials the probiotic E. faecium could be re-isolated from the yolk sac and intestine at hatch and at day 7. Broilers in the probiotic treated groups had a higher performance in terms of bodyweight at day 34 and European production efficiency factor. Finally, a significant reduction of first-week and overall mortality was observed in the probiotic group in the first trial. Based on 16S rRNA profiling, significant differences in alpha diversity were found exclusively at day 37. Estimation of beta diversities, however, identified significant differences in microbiota composition between the control and probiotic group at day 7, 21 and 37.ConclusionThe probiotic E. faecium strain successfully colonized broilers before/during hatch after a single spray application at day 18 of incubation. Positive effects of the probiotic were observed in multiple production parameters, including reduced mortality in trial 1, and microbiota analyses indicate significantly different microbiota compositions throughout the experimental phase. Taken together, the novel low-tech mass administration of E. faecium (669) may be considered a feasible strategy for improvements of production parameters in broiler production.

Scratch area as an epidemiological risk factor for Spotty Liver Disease in cage-free layers in Australia

Spotty Liver Disease (SLD) is a serious problem in laying hens farmed in cage-free systems. The causative organism, Campylobacter hepaticus, is regarded as having a fecal-oral method of transmission and hence may build up and spread readily in housing systems which allow ease of direct contact of hens with the flock's fecal material. The epidemiology of SLD has not been thoroughly investigated. An initial cross-sectional analytical epidemiological survey of SLD in free range and barn layer systems was conducted in Australia over 2019 to 2021.The survey involved rearing flocks (n=32) which were then followed through into laying flocks (n=24) up to 40 wk of age. Cloacal swabs were collected during rearing and lay for C. hepaticus detection by PCR. Flocks were classified as "Cases" (n=18) where clinical SLD according to the case definition was observed or "Controls" (n=6) which were clinically unaffected. No C. hepaticus was detected in cloacal swabs from rearing houses whereas the organism was detected in 18 Case flocks in lay and from 2 Control flocks in lay. All layer houses that incorporated a scratch area (n=13) were categorized as Cases. Thus, having a scratch area is a key determinant for SLD and no analyses of further contributory factors from these flocks were able to be made. Of the remaining 11 flocks which had floors fully covered by slats, 5 were Cases (45%). Further risk factor analysis was compromised by this small sample size and identification of other significant associations was not possible. A larger survey investigating flocks laying in houses with fully slatted floors was undertaken to further the understanding of SLD epidemiology and is reported in a companion paper.

An Investigation of the Effect of Water Additives on Broiler Growth and the Caecal Microbiota at Harvest.

Campylobacter is the most common foodborne pathogen in developed countries and most cases are associated with poultry. This study investigated the effect of three anti-Campylobacter water additives on broiler growth and on the caecal microbiota at harvest using 16S rRNA amplicon sequencing. Mixtures of organic acids (OA) and essential oils (EO) were administered to broilers for the entirety of the production cycle (35 d) and medium-chain fatty acids (MCFA) for 5 d immediately before harvest, under commercial conditions. Bird weight gain was significantly (p < 0.001) reduced in broilers receiving the OA and EO treatments. While this was most likely due to reduced water intake and corresponding lower feed consumption, changes to the caecal microbiota may also have contributed. Firmicutes made up over 75% of the bacteria regardless of sample type, while the minor phyla included Bacteroidetes, Actinobacteria, Melainabacteria, and Proteobacteria. There were no significant (p > 0.05) differences in the alpha diversity as measured using ACE, Chao1, and Shannon indices, except for control (water) versus MCFA and OA versus MCFA, using the Wilcox test. In contrast, there was a significant (p < 0.05) difference in beta diversity when the treated were compared to the untreated control and main flock samples, while linear discriminant analysis effect size (LeFSe) identified three OTUs that were present in the control but absent in the treated birds. It was concluded that the water additives tested adversely affected broiler performance, which may, at least in part, be due to changes in the caecal microbiota, assuming that the altered microbiota at day 35 is indicative of a change throughout the production cycle.

PSXI-27 Comparison of live weight, backfat depth, and loin eye muscle measurements in ewe and ram lambs

Abstract Application of ultrasound carcass trait scanning in meat animals enhances the selection efficiency and accuracy. One hundred and sixty-two mixed age Katahdin ewes were selected based on ultrasound carcass traits and bred in a high lean muscle selection (n=81) and control (n=81) flocks, respectively in December 2019. Carcass traits including loin eye area (LEA), loin eye muscle width (LEW) and depth (LED), and back-fat depth (BFD) were measured for sires, dams, and their progeny lambs. Birth weight (BW), rearing rank, sex, and weaning weight (WW=90 d) and post weaning weight (PW=120 d) were recorded for progeny. Post-weaning live weight, LEA and BFD values were calculated for deriving an expected progeny difference lists and ewe replacements. Retaining ram lambs (25% male progeny) were recorded for live weight, carcass trait scanning, and breeding values estimate at six-month old as breeding sires. There was no difference between selection and control progeny for WW, PW, BFD and LEA measurements. Means for BW, WW, PW, LEA, LEW, LED, and FBD in progeny were 3.77 ±0.56, 22.13 ±2.98, 24.48 ±3.08 kg, 5.9 ±0.1cm², 4.4 ±0.5 cm, 1.9 ±0.2 cm and 2.9 ±2.6 mm. However, the WW, PW, LEA, and LEW were measured significantly (P &amp;lt; 0.05) greater for ram lambs (20.6 kg, 25.5 kg, 6.1 cm², 4.5 cm) over ewe lambs (19.5 kg, 23.8 kg, 5.7 cm², 4.3 cm). Single born lambs were significantly (P &amp;lt; 0.01) heavier at birth, weaning and post-weaning, and measured greater value for LEA and LED than twin birth or reared lambs. The statistical analysis showed WW was significantly (P &amp;lt; 0.01) correlated with PW (r=0.71) and both WW and PW correlated with LEA (r=0.5) but not with BFD. The result indicates that lean animal selection using ultrasound carcass trait scanning will improve early age selection efficiency and accuracy.

Flock Management Risk Factors Associated with Q Fever Infection in Sheep in Saudi Arabia.

Simple SummaryQ fever is a zoonotic disease with significant public health implications. Sheep are one of the main reservoirs for this disease, whereas abortion is the primary clinical outcome. Q fever is endemic in many countries, including Saudi Arabia. Flock management practices play a significant role in the spread of Q fever infection among flocks. However, information on flock management factors associated with Q fever seropositivity in Saudi Arabia is very scarce. The results obtained from 50 flocks identified three protective factors (lambing pen, change bedding after removing aborted materials, and isolation of aborted ewes) and two risk factors (infestation with ticks and history of Q fever) were associated with Q fever seropositivity.Q fever is a zoonotic disease caused by Coxiella burnetii (C. burnetii), an intracellular, Gram-negative bacterium that infects humans and domestic ruminants. Information on flock management factors associated with Q fever seropositivity in Saudi Arabia is very scarce. Therefore, the objective of this study was to identify the animal and flock management factors associated with Q fever seropositivity. For the assessment of risk factors, a case-control study was carried out. Cases (n = 25) were flocks that had recent abortions within the previous two weeks and were PCR positive for C. burnetii. Control flocks (n = 25) had no history of recent abortion and were PCR negative for C. burnetii. A questionnaire was developed to collect information about the flock management risk factors possibly associated with Q fever exposure in sheep. A total of 2437 sheep serum samples, collected from infected (n = 1610, 10–150 samples/flock) and non-infected (n = 827, 10–65 samples/flock) flocks, were tested for C. burnetii antibodies using a commercial ELISA kit between May 2018 and April 2019. In addition, 521 samples, including 50 aborted materials, 173 vaginal swabs, 134 faecal, and 164 milk samples, were collected for PCR testing. Infected flocks were 100% seropositive (within-flock seroprevalence ranging between 13.8% and 60%) and 100% PCR positive (with animal shedders of C. burnetii through aborted materials and/or vaginal fluids, feces, and milk). However, in non-infected control flocks, 28% were seropositive (within-flock seroprevalence ranging between 6.7% and 20%) and none had C. burnetii shedders. Epidemiological data were analyzed using mixed-effect logistic regression with a random effect for the flock. The results identified three protective factors: flocks with a lambing pen (odds ratio (OR): 0.46; 95% CI: 0.28–0.76), change bedding after removing aborted materials (OR: 0.42; 95% CI: 0.23–0.76), and flocks that isolated aborted ewes (OR: 0.41; 95% CI: 0.25–0.67), as well as two risk factors: flocks infested with ticks (OR: 2.78; 95% CI: 1.65–4.70) and flocks with a history of Q fever (OR: 3.03; 95% CI: 1.42–6.50). These results could be used to improve sheep flock biosecurity measures to prevent the introduction and reduce exposure of sheep and humans to Q fever infection.

Absence of “selfish herd” dynamics in bird flocks under threat

The "selfish herd" hypothesis1 provides a potential mechanism to explain a ubiquitous phenomenon in nature: that of non-kin aggregations. Individuals in selfish herds are thought to benefit by reducing their own risk at the expense of conspecifics by attracting toward their neighbors' positions1,2 or central locations in the aggregation.3-5 Alternatively, increased alignment with their neighbors' orientation could reduce the chance of predation through information sharing6-8 or collective escape.6 Using both small and large flocks of homing pigeons (Columba livia; n= 8-10 or n= 27-34 individuals) tagged with 5-Hz GPS loggers and a GPS-tagged, remote-controlled model peregrine falcon (Falco peregrinus), we tested whether individuals increase their use of attraction over alignment when under perceived threat. We conducted n= 27 flights in treatment conditions, chased by the robotic "predator," and n= 16 flights in control conditions (not chased). Despite responding strongly to the RobotFalcon-by turning away from its flight direction-individuals in treatment flocks demonstrated no increased attraction compared with control flocks, and this result held across both flock sizes. We suggest that mutualistic alignment is more advantageous than selfish attraction in groups with a high coincidence of individual and collective interests (adaptive hypothesis). However, we also explore alternative explanations, such as high cognitive demand under threat and collision avoidance (mechanistic hypotheses). We conclude that selfish herd may not be an appropriate paradigm for understanding the function of highly synchronous collective motion, as observed in bird flocks and perhaps also fish shoals and highly aligned mammal aggregations, such as moving herds.

Association of Broiler Litter Microbiome Composition and Campylobacter Isolation.

Infection with Campylobacter species is one of the leading causes of bacterial diarrhea in humans in the US. Chickens, which become colonized on the farm, are important reservoirs of this bacterium. Campylobacter can establish itself in the broiler house via a variety of sources, can survive in the litter of the house, and possibly persist over successive flock cycles. However, the role of the broiler litter microbiome on Campylobacter persistence is not clear. A matched case-control study was conducted to determine whether the broiler litter microbiome composition was associated with Campylobacter isolation within the broiler house. Flocks were classified as cases when either Campylobacter jejuni or Campylobacter coli was isolated in boot sock samples, or as controls otherwise. Case and control flocks were matched at the broiler house level. Composite broiler litter samples were collected and used for DNA extraction and 16S rRNA gene V4 region sequencing. Reads were processed using the DADA2 pipeline to obtain a table of amplicon sequence variants. Alpha diversity and differential bacterial relative abundance were used as predictors of Campylobacter isolation status in conditional logistic regression models adjusting for flock age and sampling season. Beta diversity distances were used as regressors in stratified PERMANOVA with Campylobacter isolation status as predictor, and broiler house as stratum. When Campylobacter was isolated in boot socks, broiler litter microbiome richness and evenness were lower and higher, respectively, without reaching statistical significance. Campylobacter isolation status significantly explained a small proportion of the beta diversity (genus-level Aitchison dissimilarity distance). Clostridium and Anaerostipes were positively associated with Campylobacter isolation status, whereas Bifidobacterium, Anaerosporobacter, and Stenotrophomonas were negatively associated. Our results suggest the presence of bacterial interactions between Campylobacter and the broiler litter microbiome. The negative association of Campylobacter with Bifidobacterium, Anaerosporobacter, and Stenotrophomonas in litter could be potentially exploited as a pre-harvest control strategy.

Rearing experience with ramps improves specific learning and behaviour and welfare on a commercial laying farm

To access resources in commercial laying houses hens must move between levels with agility to avoid injury. This study considered whether providing ramps during rear improved the ability of birds to transition between levels. Twelve commercial flocks (2000 birds/flock) on a multi-age site were examined between 1 and 40 weeks of age. All birds had access to elevated perching structures from 4 days of age. Six treatment flocks were also provided with ramps during rear to facilitate access to these structures. Flocks were visited three times during rear and three times at lay to record transitioning behaviour and use of the elevated structures, together with scores for keel bone and feather damage. Ramp reared flocks used the elevated structures to a greater extent at rear (P = 0.001) and at lay, when all flocks had ramps, showed less hesitancy [i.e. pacing (P = 0.002), crouching (P = 0.001) and wing-flapping (P = 0.001)] in accessing levels. Mean levels of keel bone damage were reduced in ramp reared flocks (52%) compared with control flocks (64.8%) at 40 weeks of age (P = 0.028). The early life experience of the ramp reared flocks enabled specific learning that translated and persisted in later life and resulted in overall welfare benefits.

29791 Bird-delivered ivermectin as a novel urban West Nile virus prevention strategy

ABSTRACT IMPACT: Successful implementation of this control strategy will result in a commercially available ivermectin-treated birdfeed that the public can use to protect themselves from infection with West Nile virus (WNV) by reducing mosquito survival and thereby suppressing WNV transmission around their homes. OBJECTIVES/GOALS: We assessed the efficacy and feasibility of ivermectin (IVM)-treated birds as a mosquito control strategy for local reduction of West Nile virus (WNV) transmission. We conducted a randomized field trial in backyard chickens and developed a mathematical model informed by field data to predict the impact of treated wild birds on transmission. METHODS/STUDY POPULATION: We placed 48 chickens in four treated and four untreated control flocks in backyards coops across Davis, CA and administered IVM daily in feed to treated flocks (Jul-Sep 2019). We assessed entomological indices weekly (i.e. Culex mosquito abundance, WNV infection prevalence, and parity rate) around each coop, monitored serum IVM levels in treated chickens, and tested for WNV antibodies in all chickens. Shifting our focus to wild birds, we developed a spatially-implicit mathematical model of WNV transmission near IVM-treated birdfeeders. Model parameters for bird movement were based on our telemetry of 27 birds in Fort Collins, CO (Aug-Sep 2020). Using the model, we predicted optimal deployment of treated feeders to provide local WNV control. RESULTS/ANTICIPATED RESULTS: WNV seroconversions were reduced in treated vs. untreated flocks, indicating a reduction in WNV transmission intensity at treated coops (P = 0.03). A sustained, but insignificant reduction in number of infected mosquitoes was observed near treated coops (P = 0.59); small sample sizes and below normal WNV prevalence in the study area limited our power. We anticipate that optimal spacing and number of IVM-treated birdfeeders required for effective WNV control in neighborhoods will depend on feeder usage rates by common bird species irrespective of WNV competence; broad availability of IVM-treated bloodmeals to mosquitoes will be more effective in reducing transmission than targeting the few species responsible for viral amplification. DISCUSSION/SIGNIFICANCE OF FINDINGS: IVM is a novel method for controlling zoonotic pathogens in the US and has the potential for targeted mosquito control to reduce pesticide usage. Evaluating spatial deployment of IVM-treated bird feed for local reduction in WNV transmission is a stepping stone to commercial deployment of this WNV control strategy.

236 Comparison of ultrasound scanned loin eye muscle characteristics and back-fat depth measured in lean muscle selection and control Katahdin sheep flock

Abstract Sheep farming is an important enterprise for many farmers in US, and meat is a viable protein resource for human nutrition. However, increasing concern for health aspects of meat consumption has led consumers to demand a higher ratio of lean to fat tissues. Application of ultrasound carcass scanning in meat animal selection and marketing as a performance prediction will enhance the selection efficiency, accuracy and profitability. One hundred and sixty two mixed-age Katahdin ewes were evenly divided into a high lean muscle selection (n = 81) and control (n = 81) flock based on the prescreened ultrasound measures, including loin eye muscle area (LEA), loin eye muscle width (LEW), and depth (LED), and back-fat depth (BFD). The LEA is measured between the 12th and 13th ribs lateral and perpendicular to the vertical column and parallel to rib covering the longissimus dorsi muscle. Live animal measurements were conducted using ultrasound scanner fitted with a 3.5 MHz linear transducer (ExaGo, France) prior to fall breeding schedules. Live weight (LWT), body condition score (BCS) and FAMACHA score (FAM) were recorded. Data were analyzed using GLM procedures of SAS statistics. There was no difference between selection and control flocks for LWT, BCS and FAM; however, LEA, LEW, LED and BFD were significantly (P &amp;lt; 0.05) greater for the lean selection over control flock (Table 1). The correlation coefficients (P &amp;lt; 0.01) were found as moderate (r = 0.6) to high (r = 0.8) among LED, LEA, LEW and BFD, whereas these traits showed lower (r = 0.4) but significant (P &amp;lt; 0.01) correlations with LWT. The results indicate that lean muscle selection in sheep with ultrasound scanning of longissimus muscle characteristics will enhance the production efficiency and genetic gain and facilitate producing a high value meat product.

Rewarding memories? Behaviour of broiler chickens towards peat in flocks with and without previous exposure to peat

Under commercial conditions, environmental provisions assumed to have an enriching effect on broiler chicken welfare may be offered infrequently and at limited locations, raising questions about their enrichment value. We hypothesized that, if broilers given limited access to peat remembered peat as rewarding, they would subsequently be quicker to exploit fresh peat compared to broilers never previously exposed to peat. We observed 9 control flocks without previous peat exposure and 18 flocks given peat from 1 week of age with variable regularity and in limited locations. During flock visits at approximately 4 weeks of age, we placed 10 L of fresh peat in one location (peat patch) and pretended to do so in another location (control patch, wood shavings litter only). From 20-min video recordings of the peat and control patches, we determined the mean latency for the first five birds to perform standing, lying, ground pecking, ground scratching and vertical wing shaking in each patch. We also recorded the total number of birds present, and proportion lying, per patch based on instantaneous scan sampling at 1-min intervals. We used linear mixed models to assess effects of previous flock exposure to peat, patch type and their interaction, with farm as a random factor. Birds were quicker to ground peck, and slower to stand and lie, in peat than control patches, and the proportion lying was lower (i.e. birds were more active) in peat patches. Birds in peat-exposed flocks were quicker to ground peck than birds without prior peat experience. They also had shorter latencies to stand on peat, and to commence ground scratching and vertical wing shaking in peat, compared to birds in peat-unexposed flocks whereas previous peat exposure did not affect these behaviours in the control patch. In peat-unexposed flocks, birds were slower to stand, in the peat patch than the control patch, and fewer birds were present in the peat patch than the control patch throughout the 20-min observation period. Thus, birds in the peat-exposed flocks were quicker to exploit fresh peat by performing behavioural elements of foraging and dustbathing whereas birds in peat-unexposed flocks showed more caution towards the peat. We conclude that, even though provisioning of peat was relatively sparse and ephemeral, it was sufficient to generate long-term positive memories of the resource and to activate the performance of natural behaviours, supporting its value as an enrichment for broilers under commercial conditions.

Detection and Quantification of Clostridium perfringens and Eimeria spp. in Poultry Dust Using Real-Time PCR Under Experimental and Field Conditions.

Infection of poultry with Eimeria spp., the causative agent of coccidiosis, can predispose birds to necrotic enteritis (NE) caused by netB gene-positive strains of Clostridium perfringens. The detection of Eimeria spp., C. perfringens, and netB were examined in settled dust from broiler flocks under experimental and field conditions. Dust samples were collected from settle plates twice weekly from two experimental flocks inoculated with three species of pathogenic Eimeria in 9-day-old chicks, followed by netB gene-positive C. perfringens 5 days later to produce subclinical and clinical NE. A noninoculated flock was sampled weekly from day 0 and served as a control flock. An additional 227 dust samples from commercial broiler flocks were collected at the end-of-batch (6-7 wk of age; one scraped dust sample per flock). In the NE-subclinical and NE-clinical flocks, high levels of Eimeria spp. and C. perfringens were detected after inoculation followed by a gradual decline over time. In the control flock, C. perfringens and netB were detected at low levels. No significant effect of sampling location was evident on Eimeria spp., C. perfringens, and netB load within poultry houses. These results provide evidence that Eimeria spp., C. perfringens, and netB gene copies can be readily measured in poultry dust samples collected in settle plates and may provide an alternative sampling method for monitoring flock coccidiosis and NE status. Further studies are required to assess the utility for such a test in commercial flocks.

Effect of pecking stones and age on feather cover, hen mortality, and performance in free-range laying hens

Severe feather pecking is frequently associated with impaired egg production, poor hen welfare, and increased mortality. The aim of this study was to investigate the potential of pecking stones to ameliorate the incidence of feather pecking. A total of 18 flocks of Hy-Line Brown laying hens were randomly assigned to control (n = 9 no pecking stone access) or treatment (n = 9 pecking stone access) flocks and housed in commercial fixed sheds (farm A, n = 10) or commercial mobile sheds (farm B, n = 8) differing in various housing conditions. Beak length, feather score, egg production, and mortality were evaluated at 16 wk of age and every 10 wk until at least 46 wk of age. On farm A, hens with access to pecking stones had significantly lower mortality than hens without pecking stone access (P = 0.001). A significant interaction between pecking stone and age was observed on feather scores of wings of hens housed in farm A. Hens of the pecking stone group in farm A had higher wing feather score (indicating better feather condition) at the age of 56 and 66 wk than hens with no access to pecking stones (pecking stone × age, P = 0.002). The age of the hens was significantly associated with lower overall feather scores (poorer feather condition), reduced egg production, and higher mortality (P < 0.05). Although pecking stones reduced some feather loss and mortality, this effect was only present on one farm and therefore may be related to farm management. Especially the impact of pecking stones on mortality was inconclusive as the cumulative mortality in farm B was nearly twice as high compared with that in control flocks. Further investigations are warranted including the effects of pecking stone provision at an early age such as during rearing (0–17 wk of age).

Experimental forest fragmentation alters Amazonian mixed-species flocks

Habitat fragmentation has been associated with myriad negative effects for forest-dependent birds in the Neotropics. However, the vast majority of negative effects have been inferred from comparisons of pre-existing fragments with separate control sites. Such comparisons confound area loss with isolation and ignore effects of patchy distributions and local habitat heterogeneity. To directly test the effects of fragmentation on Amazonian mixed-species flocks—a complex and diverse species interaction network—we observed birds before and after re-isolation of three 10-ha fragments at the Biological Dynamics of Forest Fragments Project in central Amazonia. Following initial isolation in the 1980s, these fragments have been surrounded by a matrix of developing second growth that was cut again in 2013–2014 (re-isolation). Simultaneously, we also followed three control flocks in primary forest that bordered tall secondary forest. We quantified species richness and attendance, home range size, proportional use of edge and second growth, and space use for fragment and control flocks before and after re-isolation. Following re-isolation, one flock disappeared entirely and half of the obligate flock-followers either vanished or decreased attendance rates. Home ranges of fragment flocks shrunk, and movements were confined by newly created hard edges. These results provide direct experimental evidence that isolation leads to the deterioration and collapse of flocks in forest fragments, affecting both direct metrics and emergent properties of a complex social network. This study also provides retrospective insight into the value of adjacent second growth habitat as immigration corridors for birds in mixed-species flocks.

Optimization Algorithm Applied to Environmental Control in Broiler Houses

ABSTRACT The present study aimed to apply the Simulated Annealing (SA) optimization algorithm to find the ideal control of broiler housing rearing environment at 21, 28, 35, and 42 days of growth. Data from four types of houses using environmental control and similar flock density were recorded weekly in the morning and afternoon, during two seasons (summer and winter). The variables related to environmental and air quality data (temperature, relative humidity, air velocity, ammonia, and carbon dioxide concentrations) were registered and organized into the database to provide a descriptive analysis. The ideal rearing conditions were established as a goal, and we used the Simulated Annealing optimization algorithm to process the data. Such an approach may be applied in the cases that the ideal condition of optimization has multiple objectives, and when each variable is the result of a process. The model was implemented considering the optimal controlled environmental condition that depends on the age of broilers. Results indicated that there was a large dispersion of the data collected from the environmental variables. The process suggested that the optimized functions lead to absolute values obtained by the algorithm for each of the environmental factors of the controlled environmental system, representing the optimal condition of the environment found for each broiler age, considering the interactions of the variables. The maximum optimization was prominent to 21 and 35-d old birds, representing 40-48% of the improvement of the process. 28 and 42-d old birds might benefit from the controlled environmental optimization process by up to 30%.

국내 산란계의 주요 전염성 질병에 대한 혈청학적 모니터링

Serological monitoring has been conducted worldwide for early diagnosis of disease and monitoring of immune status in poultry. This study was conducted to evaluate the immune status of layers with sera submitted to the Avian Disease Laboratory, Chungbuk National University from 2015 to 2017. The test results were analyzed by the time submitted and by the age of the chicks. Low pathogenic avian influenza (LPAI) showed a low positive rate of antibody compared with those of Newcastle disease, indicating that domestic vaccination against LPAI was not sufficient. The antibody profile of infectious bronchitis (IB) depicted high level of titer and a low tendency of CV as compared to the uninfected control flocks, which indicated that most layer farms have been exposed to the field IB virus. In case of avian metapneumovirus infection (aMPV) and <italic>Mycoplasma synoviae</italic> (MS), since the introduction of the vaccine in 2011 and 2017, respectively, the positive rate and the titer level were higher than those in pevious times. No significant difference in the changes of seasonal result was observed, indicating proper vaccination and improvement in biosecurity and management.

Differences between feather pecking and non-feather pecking laying hen flocks regarding their compliance with recommendations for the prevention of feather pecking – A matched concurrent case-control design

Feather pecking (FP) is a multifactorial problem in all housing systems. Using a case-control design we wanted to determine a set of variables which may be decisive for a flock to become case or control. At the same time, we expected that the prevention of feather pecking not only depends on certain factors, but also quantitatively on the extent of compliance with recommendations. Data from three cross-sectional studies were pooled, from which 165 flocks were allocated to cases (FP problem flocks) or controls (no FP problem). Control flocks had at least 98% of hens with a very good or nearly complete feather cover whereas in case flocks 10% or more of the hens had highly damaged feathers or featherless areas ≥ 5 cm² in at least one body region. From 32 potential preventive factors that had been recorded in all data sets, 18 factors passed univariable pre-selection and were presented to forward logistic regression analysis. The resulting model for 137 flocks (due to missing values) explained 41% of the variance, correctly classified 77% of cases and comprised four variables with an effect size of f = 0.8. A higher stocking density increased the likelihood of a ‘FP-problem’ whereas the presence of wooden perches and a littered veranda lowered it. Unexpectedly, a higher drinking place/hen ratio also predicted a FP problem. The results concerning wooden perches and drinking place/hen ratio might be due to indirect effects and should be further investigated. Non-FP flocks complied on average with 46.5% of recommendations (from a list of 13 factors), which was greater than FP-flocks (42.5%, P = .036, U = 2537.500, n = 165, Mann-Whitney-U test, dCohen = 0.327). We conclude that the number of fulfilled recommendations as well as the combination of specific measures such as provision of a covered veranda with dry litter or reduced stocking density are important to prevent FP.

Comparison of performance, health and welfare aspects between commercially housed hatchery-hatched and on-farm hatched broiler flocks

On-farm hatching systems for broiler chicks are increasingly used in practice. We studied whether or not performance, health and welfare aspects differed between commercial flocks hatched on-farm or in a hatchery (control). In two successive production cycles on seven farms, a total of 16 on-farm hatched flocks were paired to 16 control flocks, housed at the same farm. Paired flocks originated from the same batch of eggs and were subjected to similar on-farm management. On-farm hatched and control flocks only differed with respect to hatching conditions, with on-farm hatched flocks not being exposed to, for example, chick handling, post-hatch feed and water deprivation and transport, in contrast to control flocks that were subjected to standard hatchery procedures, subsequently transported and placed in the poultry house. Day-old chick quality (navel and hock scores), 1st week mortality, total mortality, BW at day (d) 0, d7 and at depopulation, and (total) feed conversion ratio were determined. Prevalence of footpad dermatitis, hock burn, breast discoloration/blisters and cleanliness, litter quality and gait score were determined at d21 of age and around depopulation (d39 on average). Gross pathology and gut morphology were examined at depopulation age in a sample of birds of five flocks per treatment. On-farm hatching resulted in a higher BW at d0 (Δ=5.4 g) and d7 (Δ=11.5 g) (P<0.001), but day-old chick quality as measured by navel (P=0.003) and hock (P=0.01) quality was worse for on-farm hatched compared to control birds. Body weight, 1st week and total mortality, and feed conversion ratio at slaughter age were similar for both on-farm hatched and control flocks. On-farm hatched flocks had less footpad dermatitis (P=0.05), which indicated a better welfare. This was likely related to a tendency for better litter quality in on-farm hatched flocks at 21 days of age in comparison to control flocks (P=0.08). No major differences in gross pathology or in intestinal morphology at depopulation age were found between treatments. In conclusion, on-farm hatching resulted in better 1st week broiler performance and better welfare compared to conventional hatching in a hatchery.