Immunological and Physiological Differences Between Layer- and Broiler Chickens after Concurrent Intratracheal Administration of Lipopolysaccharide and Human Serum Albumin

Layers and broilers were concurrently intratracheally challenged with 0.5 mg Lipopolysaccharide (LPS) and 0.1 mg Human Serum Albumin (HuSA) at 3 weeks of age. Specific total and isotype-specific (IgM, IgG, IgA) Antibody (Ab) responses to HuSA during 3 weeks following immunization, cellular in vitro mitogen responses to Concanavalin A (Con A) and specific cellular responses in vitro to different dosages of HuSA, blood serotonin (5-HT) levels, plasma Corticosterone (CORT) levels at 6 weeks of age and ex vivo nitric oxide (NO) production in the presence of LPS, respectively, were measured in all birds. Higher in vitro cellular responses to HuSA, but not Con A, were found in the broilers than in the layers. Also higher total, IgM and IgG antibody responses to HuSA were found in the broilers. Higher ex vivo NO production was found in the layers. A heavier spleen weight was found in the broilers, but relative spleen weight was higher in the layers. The broilers grew much heavier and also maintained a higher growth during the first 24 and 48 h after i.t. challenge with LPS and HuSA. No breed effect was found for body temperature responses after i.t. challenge. Blood 5-HT levels and plasma CORT levels were significantly higher in the layers. Number and type of significant correlations between 5-HT levels, cachectin response to LPS, antibody levels and cellular immunity differed between breeds. Our data suggest comparable immune responses to i.t. HuSA challenge in broilers and layers of similar age and confirm the earlier reported higher humoral immune response in broilers. On the other hand, the cachectin response to LPS differed between broilers and layers. Our results do not confirm the earlier reported higher cellular immune response of layers. Different significant relationships between physiological parameters in broilers and layers were found. Our results suggest that selection for enhanced growth does not necessarily affect specific immune competence of poultr

Relationship between hatchling length and weight on later productive performance in broilers

Hatchling length and weight are used as tools to measure hatchling quality. However, the relationship between these parameters and later performance are not well known. This review evaluates the relationship between hatchling length or weight and slaughter weight, breast meat yield and feed conversion ratio (FCR) in both male and female broilers. Datasets from two trials were compared. In the first, hatchling length and weight of 100 male and 100 female broilers were measured and body weight and breast meat yield were determined at 38 days of age. In experiment 2, hatchling length of 187 female and 230 male broilers was measured and body weight was determined at 21 and 42 days of age. Feed intake was determined between 21 and 42 days of age. In both experiments, male broilers showed a positive relationship between hatchling length and slaughter weight or breast meat yield, but no relationship was found with hatchling weight. The relationship between hatchling length and performance in female broilers differed between the two experiments. In female broilers, a negative relationship between hatchling weight and breast meat yield was found. No relationship between hatchling length and FCR in both male and female broilers was found. From this limited dataset, it can be concluded that hatchling length seems to be a better parameter to predict subsequent chick performance, excluding FCR, than hatchling weight, but gender needs to be taken into accoun

Efficacy of Probiotics for Reducing the Incidence of Lameness in Broilers Grown on Wire Flooring

Growing broilers on wire flooring provides an excellent experimental model for reproducibly triggering significant levels of lameness. In Pilot Study #1 using broilers from Line C grown on wire flooring, adding the Biomin probiotic PoultryStar® to the feed reduced the percentage of lameness by half when compared with broilers that received the control diet alone. In Pilot Study # 2 using broilers from Line B grown on wire flooring, adding the PoultryStar® probiotic reduced the percentage of lameness to 8% when compared with 28% lameness in broilers that received the control diet alone. The objective of this study was to conduct a replicated experiment to determine if probiotics consistently reduced the incidence of lameness in broilers reared on wire flooring. Male broiler chicks from Cobb-Vantress Line B were placed at 1 day of age in pens having flat wire flooring within environmental chambers 1 through 10 inside the Poultry Environmental Research Lab at the University of Arkansas Poultry Research Farm. On day 14, birds were culled to 50 per pen, yielding a density of 1ft²/chick. A corn and soybean meal-based diet formulated to meet minimum National Research Council standards (1994) for all ingredients was provided ad libitum as the control feed. Broilers in chambers 1, 3, 5, 7 and 9 were provided the control feed while chambers 2, 4, 6, 8 and 10 were provided the same feed mixed with the probiotic throughout the experiment (50 lbs of control feed blended with 12.5 g PoultryStar® probiotic). The birds in all pens were walked and observed for lameness every two days starting on day 15 and continuing until the end of the experiment on day 56. Birds unable or unwilling to walk were diagnosed as clinically lame and humanely euthanized with CO2 gas. They were then necropsied to assess sub-clinical lesion incidences including femoral head separation, femoral head transitional degeneration, femoral head necrosis, tibial head necrosis, and tibial dyschondroplasia. Findings from the study indicate that for broilers grown on wire flooring, diets containing the probiotic PoultryStar® consistently reduced the incidence of lameness when compared with birds fed the control diet alone

Research note : lyophilization of hyperimmune egg yolk : effect on antibody titer and protection of broilers against Campylobacter colonization

Oral administration of antibodies is a promising strategy against various infectious diseases. Previously, it was demonstrated that passive immunization by providing hyperimmune egg yolk through the feed reduces Campylobacter jejuni colonization in broilers. Campylobacteriosis is the most commonly reported bacterial foodborne zoonosis worldwide, and poultry products are the number one origin of these bacteria for human infection. To date, no effective control measures exist to limit Campylobacter colonization in the chicken's intestinal tract. Here, the effect of lyophilization of hyperimmune egg yolk on protection of broilers against C. jejuni was investigated. During an in vivo trial, broiler chickens were prophylactically given feed with lyophilized hyperimmune or non-immunized egg yolk powder starting from day 1 after hatch. At day 11, broilers were inoculated with C. jejuni according to a seeder model. Five days later, all broilers were euthanized and cecal content was examined for C. jejuni colonization. No decrease in C. jejuni colonization was found. The freeze-drying resulted in a 16-fold decrease of the antibody titer in the yolk powder compared to the fresh yolks, presumably caused by structural changes in the antibodies. In conclusion, applying freeze-dried hyperimmune egg yolk failed to protect broilers against C. jejuni colonization, possibly because lyophilization affected the antibodies' functionality

Organic broilers in floorless pens on pasture

This thesis investigates different aspects of rearing broilers organically in floorless pens on pasture. The birds and pens were moved daily to fresh pasture. The interdisciplinary studies comprise the birds' growth performance and carcass quality, health, behaviour, leg condition and the birds’ effect on pasture. In the final study, on-farm diets were tested in a feeding experiment indoors. The data are based on four experiments carried out during 2000 to 2003. In 2000 and 2002, restricted-fed conventional broilers (ROSS 208) were reared in floorless pens on pasture and in control groups outdoors on straw. In 2001, two genotypes, ROSS 208 and the slow-growing ISA 657 were reared on three ground types, pasture, outdoors on straw and indoors on wood shavings with either an ad libitum or restricted feeding level. In 2003, a feeding experiment with slow-growing broilers fed on-farm diets in a choice feeding system was conducted indoors. Most birds were reared to 12 weeks of age, but ad libitum-fed ROSS birds were reared to 6 weeks. The experimental phase was from ca. 3 weeks to slaughter. The experiments indicate that under the given conditions - access to pasture does not offer sufficient protein and metabolizable energy to allow considerable feed savings in the farm enterprise (Paper I) - moving the floorless pens daily provides favourable conditions to prevent infections with Campylobacter and Eimeria in outdoor broilers (Paper II) - access to pasture as such appears to play no major role for the broilers' physical activity (Paper III) or leg condition (Paper IV) - broiler chickens on pasture can sustain white clover in a mixed grass/white clover pasture (Paper V) - with access to high-quality protein during the first three weeks there is a good potential to produce organic broiler meat with feed produced on-farm in northwestern Europe (Paper VI)

Bacteriological and epidemiological studies of campylobacter spp. in Swedish broilers

Campylobacter jejuni is the most frequently reported cause of bacterial gastrointestinal illness in humans in Sweden. Chicken products are considered an important risk factor for human infection. This thesis analyses and identifies sources and risk factors for colonisation of Campylobacter spp. in broilers at both farm level and slaughter. Slaughter groups with a low within-group prevalence were identified, split slaughter was confirmed as a risk factor and contamination of carcasses was shown to occur both during transport and during the slaughter process. Environmental campylobacter load was comparable on high and low incidence farms, indicating that hygiene regime is of greater importance than environmental load. Slaughter groups with a high within-flock prevalence had significantly higher campylobacter load in carcasses at slaughter than slaughter groups with a low degree of colonisation Campylobacter jejuni is the Campylobacter sp. predominantly found in broilers. Strain characterisation below species level, so-called subtyping, is a helpful tool in epidemiological studies, e.g. in determination of transmission routes. Certain subtypes were shown to be common in Sweden and may have a higher ability to survive in the environment around broiler houses. The results from phylogenetic analysis indicated that typing based on 16S rRNA sequencing is not always sufficient for differentiating between C. jejuni and C. coli. However, nine different 16S rRNA types were identified among 47 Swedish campylobacter isolates from broilers. About one-third of Swedish broiler producers seldom deliver any campylobacter-positive broilers to slaughter, demonstrating that it is possible to produce campylobacter-free chickens in Sweden. The factors identified as carrying the highest risk of producing campylobacter-positive broilers in Sweden were (i) insufficient general tidiness on the farm, (ii) split slaughter, (iii) an in-line position of the doors between the outside and access into broiler houses instead of an angled position. Furthermore, (iv) high risk farms often had other livestock such as cattle and pigs, and (v) high risk farms were more frequently situated in groves than in forest. Reducing the proportion of campylobacter-infected broiler flocks and the numbers of campylobacter on broiler carcasses would considerably lower the risk for consumers

Foot-pad dermatitis in broilers and turkeys

Foot-pad dermatitis is a condition characterised by lesions on the ventral foot-pads of poultry. It is a type of contact dermatitis, which in an early stage results in hyperkeratosis, erosions and discoloration of the skin. The erosions can develop into ulcers. In severe cases, the foot-pad lesions may cause pain which together with a deteriorated state of health constitutes a welfare issue. It has also been indicated that broilers with severe foot-pad dermatitis show slower weight gain. The aim of the present work was to improve the knowledge concerning the epidemiology of foot-pad dermatitis in meat-type poultry in Sweden. The studies were focused on surveying the occurrence of foot-pad dermatitis on Swedish commercial broiler and turkey farms, identifying endogenous and exogenous risk factors for foot-pad dermatitis in meat-type poultry and to evaluate the function of foot health as an indicator of management, hygiene and housing standards. The prevalence of foot-pad dermatitis in Swedish broilers at time of slaughter was estimated at 5-10 % for severe lesions and 10-35 % for mild lesions. The corresponding prevalence of foot-pad dermatitis in turkeys was estimated at approximately 20 % for severe lesions and 78 % for mild lesions. A significantly higher prevalence of foot-pad dermatitis was found in flocks reared on wet litter than on dry litter. In broilers, a significantly higher prevalence of lesions was found in flocks reared on thick layers of litter material than on thinner layers. There was an association between litter material and turkey foot-pad dermatitis. Type of drinker system, which is related to both water spillage and water consumption, was significantly associated with the prevalence of foot-pad dermatitis in both broilers and turkeys. There was a significant seasonal effect on the prevalence of broiler foot-pad dermatitis, with the highest prevalence found during October to January. The prevalence and severity of foot-pad dermatitis in broilers decreased over time when a surveillance programme was initiated and executed. In summary, foot-pad dermatitis in both broilers and turkeys was shown to be linked to a number of management, hygiene and housing factors, and can thus be used as an indicator of the standard of these factors. Surveillance and advisory programmes can be used successfully to decrease the incidence of foot-pad lesions in broiler and turkey populations and thus improve the health and welfare of the birds

Heat Stress and feeding strategies in meat-type chickens

Heat stress can induce hyperthermia in poultry. A reduction in heat load can be achieved by increasing the possibilities for dissipation, decreasing the level of heat production or by changing the thermal production pattern within a day. Strategies to reduce the negative effects of heat stress can be based on a specific feeding strategy, such as restricted feeding. Feed that is offered long enough before a hot period can ameliorate the harmful effects of high temperature. Another strategy may be to use choice feeding from different feed ingredients, rich in protein or in energy. With such self-selection, the chicken may adjust its intake of individual components, allowing the bird to optimise the heat load associated with the metabolism of the ingested nutrients. Additional promising strategies involve offering a choice between feeds with a different feed particle size or structure. A large particle size contributes to the development of the gastro-intestinal tract (GIT), especially the gizzard and the caeca. A large gizzard will maximize the grinding process and potentially ease digestion down the GIT, thereby reducing heat production associated with digestive processing. Also wet feeding may be profitable under heat stress conditions as well. Feeding wet diets may facilitate an increased water intake and larger particle sizes can limit water excretion in droppings, resulting in more water being available for evaporation during panting, hence cooling the bird. In conclusion, these feeding strategies may help to reduce heat production peaks, facilitate evaporative activity and/or decreases the heat load, resulting in beneficial effects on performance and health of the bird kept in more tropical areas worldwide

Enzymes as Feed Additive to Aid in Responses Against Eimeria Species in Coccidia-Vaccinated Broilers Fed Corn-Soybean Meal Diets with Different Protein Levels

This research aimed to evaluate the effects of adding a combination of exogenous enzymes to starter diets varying in protein content and fed to broilers vaccinated at day of hatch with live oocysts and then challenged with mixed Eimeria spp. Five hundred four 1-d-old male Cobb-500 chickens were distributed in 72 cages. The design consisted of 12 treatments. Three anticoccidial control programs [ionophore (IO), coccidian vaccine (COV), and coccidia-vaccine + enzymes (COV + EC)] were evaluated under 3 CP levels (19, 21, and 23%), and 3 unmedicated-uninfected (UU) negative controls were included for each one of the protein levels. All chickens except those in unmedicated-uninfected negative controls were infected at 17 d of age with a mixed oral inoculum of Eimeria acervulina, Eimeria maxima, and Eimeria tenella. Live performance, lesion scores, oocyst counts, and samples for gut microflora profiles were evaluated 7 d postinfection. Ileal digestibility of amino acids (IDAA) was determined 8 d postinfection. Microbial communities (MC) were analyzed by G + C%, microbial numbers were counted by flow cytometry, and IgA concentrations were measured by ELISA. The lowest CP diets had poorer (P ≤ 0.001) BW gain and feed conversion ratio in the preinfection period. Coccidia-vaccinated broilers had lower performance than the ones fed ionophore diets during pre- and postchallenge periods. Intestinal lesion scores were affected (P ≤ 0.05) by anticoccidial control programs, but responses changed according to gut section. Feed additives or vaccination had no effect (P ≥ 0.05) on IDAA, and diets with 23% CP had the lowest (P ≤ 0.001) IDAA. Coccidial infection had no effect on MC numbers in the ileum but reduced MC numbers in ceca and suppressed ileal IgA production. The COV + EC treatment modulated MC during mixed coccidiosis infection but did not significantly improve chicken performance. Results indicated that feed enzymes may be used to modulate the gut microflora of cocci-vaccinated broiler chickens