A walk through the broiler breeder life: how do footpad dermatitis and gait scores develop from rearing to slaughter?

The two most common animal-based indicators used to evaluate leg health in broiler chickens are footpad dermatitis (FPD) and gait scoring, but these indicators are less explored in broiler breeders. This study is the first to investigate FPD and gait scoring in broiler breeders during their lifespan from rearing to end of life. In total, eight flocks were monitored (four Ross and four Hubbard) at five different timepoints, in rearing (5 and 15 weeks of age), during the production period (25 and 45 weeks of age) and at the end of the production period (approximately 60 weeks of age). At each visit, 50 hens and 25 roosters were gait scored (six-point scale) and footpads from another 50 hens and 25 roosters were evaluated (five-point scale) (total n = 3000 breeders, 2000 hens and 1000 roosters). Litter quality and air quality were measured at each visit. The results showed that the overall prevalence of FPD in rearing was low and that it increased towards the end of the production, with a mean FPD score of 2 out of a maximum 4 in the hens, indicating moderate lesions and 1.5 in the roosters. In all houses, the litter was dry and loose. FPD was not related to the litter quality, but to air quality, especially the ammonia concentration (P < 0.001). Overall, the gait score were good, and increased with age in both hens (P < 0.001) and roosters of both hybrids (P < 0.001).

Keel bone fractures in broiler breeders: is palpation a reliable diagnostic method?

The aim of this study was to estimate the sensitivity and specificity of palpation relative to necropsy for detection of keel bone fractures (KBF) in broiler breeders. In addition, the study investigated observer reliability of palpation. Four commercial breeder flocks (Ross 308 n = 2, Ranger Gold n = 1, Hubbard JA 757, n = 1) were included in the study. A total of 400 hens and 60 roosters were examined after culling or slaughter, at end of lay (63 weeks). Keel bones were first palpated independently by two raters with a varying degree of experience in palpation of keel bones in laying hens. After palpation, a necropsy with investigation of the keel bone was conducted. The prevalence of KBF at end of lay for hens, as diagnosed by necropsy, varied from 14-58%, while only one in 60 assessed roosters had KBF. Palpation had poor sensitivity, with differences between raters ranging from 56% to 36% when hybrid is not considered. The specificity of palpation for all hybrids together was 85% and 88%, for the two raters, respectively. The two raters had moderate agreement, Gwet's agreement coefficient (95% confidence interval): 0.60 (0.52-0.69). In conclusion, palpation has poor diagnostic accuracy for detection of KBF in broiler breeders, and other methods, like necropsy, must be applied for reliable assessments. KBF appears to be a prevalent condition in different hybrids of broiler breeder hens, but not in roosters.RESEARCH HIGHLIGHTS This is the first study to investigate palpation as a diagnostic method for detection of KBF in broiler breeders.Palpation has poor diagnostic accuracy for detection of KBF in broiler breeder hens with differences between raters.KBF can be a prevalent problem in broiler breeder hens of several hybrids, but not in roosters.

Effect of graded levels of soapnut (Sapindus mukorossi) shell powder on reproductive performance in broiler breeders.

OBJECTIVE: This study investigated the effects of soapnut (Sapindus mukorossi) shell powder (SSP) on serum hormone level, egg quality, semen characteristics and reproductive performance of broiler breeders fed with a maize-soybean meal based diet. METHODS: Ninety six female and twenty four male CARIBRO-VISHAL broiler breeders, 38-week old, were individually caged and randomly allocated to four treatment groups (24 female breeders/treatment and 6 male breeders/treatment): an un-supplemented control (T1) and three groups with 0.0176% SSP (group T2), 0.026% SSP (group T3) and 0.0528% SSP (group T4), to have supplementary saponin at 0, 50, 75, and 150 ppm, respectively, for 42 days. RESULTS: The results indicated that serum (p<0.001) and seminal plasma (p<0.05) testosterone level, semen volume (p<0.001), mass motility (p<0.001), and live spermatozoa count (p<0.001) was increased in groups T3 and T4 compared to T2 and control groups. Compared with control group, total sperm count was increased (p<0.001) and dead spermatozoa count was decreased (p<0.001) in SSP supplemented groups. Supplementation of SSP did not affected the quality of egg lay. Compared with control group, fertility (p<0.01) and hatchability (total eggs set and fertile eggs set) (p<0.001) were significantly improved in SSP supplemented groups with the highest improvement in T3 treatment group. Embryonic death was decreased (p< 0.001) in SSP supplemented groups compared to control; lowest embryonic death was recorded in T3 treatment group. CONCLUSION: Thus, it was concluded that dietary supplementation of 0.026% SSP (saponin equivalent 75 ppm) improved the reproductive performance of broiler breeders.

Effects of environmental temperature and dietary zinc on egg production performance, egg quality and antioxidant status and expression of heat-shock proteins in tissues of broiler breeders.

To investigate the effects of environmental temperature and dietary Zn on egg production performance, egg quality and antioxidant status, as well as expression of heat-shock proteins (HSP) in tissues, of laying broiler breeders, we used a completely randomised design with a 2×3 factorial arrangement of treatments. The two environmental temperatures were normal (21±1°C, NT) and high (32±1°C, HT). The three dietary Zn sources were a Zn-unsupplemented basal diet (CON), and the basal diet supplemented with 110 mg Zn/kg as either the inorganic Zn sulphate (iZn) or the organic Zn proteinate with a moderate chelation strength (oZn). HT decreased (P<0·002) egg weight, laying rate, eggshell strength, thickness and weight, but increased (P≤0·05) rectal temperature, broken egg rate, misshapen egg rate, feed:egg ratio, Cu Zn superoxide dismutase activities in liver and pancreas, as well as metallothionein (MT) level in pancreas, and HSP70 mRNA levels in liver and pancreas of laying broiler breeders. Broiler breeders fed the oZn diet had higher (P<0·04) Zn content in the liver, as well as MT levels in the liver and pancreas, compared with those fed the CON diet. Under HT, broiler breeders fed the oZn diet had higher (P<0·05) Zn content in the pancreas compared with those fed the iZn and CON diets. The results from this study indicated that HT impaired egg production performance and eggshell quality possibly because of the disturbed redox balance and HSP homoeostasis, whereas the oZn is more available than the iZn for pancreatic Zn of heat-stressed laying broiler breeders.

On the composition of gastroliths from broiler breeders.

The purpose of this study was to ascertain the composition and origin of certain gastroliths or gizzard stones from broiler breeders (Gallus gallus domesticus). Fourier transform infrared spectroscopy (FTIR) and X-ray powder diffraction techniques were used as analysis tools. The main components resulted to be organic fibre and minerals referred to a pegmatite rock (quartz, feldspar albite and haematite) used as grit. Although the generally accepted purpose of gastroliths in chicken is the crushing and grinding of foodstuff in the ventriculus, the importance of mineral uptake from grit of iron and other essential elements such as Al, Ca, K, Cl, P, Ti, Mn, Mg, Cu, Zn and Zr (in ppm) as a secondary effect of the abrasion and dissolution of gastroliths should not be disregarded.

Effects of different selenium sources and levels on antioxidant status in broiler breeders.

OBJECTIVE: This study was conducted with the objectives to examine the impacts of inorganic selenium (Se) and different types and levels of organic selenium on the serum and tissues Se status and antioxidant capacity in broiler breeders. METHODS: Five hundred and forty 48-wk-old Lingnan Yellow broiler breeders were randomly assigned to 6 dietary treatments, provided same basal diet (0.04 mg/kg of Se) with 0.15 mg/kg, or 0.30 mg/kg of Se from sodium selenite (SS) or from selenium-enriched yeast (SY) or from selenomethionine (SM). The broiler breeders were slaughtered after an 8-wk experiment. RESULTS: The results showed that SM was better than SY and SS, 0.30 mg/kg level was better than 0.15 mg/kg level in Se deposition (p<0.05) in serum, liver, kidney, pancreas and muscle; in antioxidant status, organic selenium had better effects than SS in broiler breeders (p<0.05), but SM and SY had a similar result, and 0.15 mg/kg level was better than 0.30 mg/kg (p<0.05). CONCLUSION: The results demonstrated the evident advantage of supplementation of broiler breeders with 0.15 mg/kg SM, which improved tissue Se concentrations and antioxidant status, and can be considered as the best selenium source.

Evaluation of the efficacy of an autogenous Escherichia coli vaccine in broiler breeders.

In poultry production Escherichia coli autogenous vaccines are often used. However, the efficacy of autogenous E. coli vaccinations has not been evaluated experimentally in chickens after start of lay. The aim of the present study was to evaluate the protective effect of an autogenous E. coli vaccine in broiler breeders. Three groups of 28-week-old broiler breeders (unvaccinated, vaccinated once and twice, respectively) were challenged with a homologous E. coli strain (same strain as included in the vaccine) or a heterologous challenge strain in an experimental ascending model. The clinical outcome was most pronounced in the unvaccinated group; however, the vast majority of chickens in the vaccinated groups had severe pathological manifestations similar to findings in the unvaccinated group after challenge with a homologous as well as a heterologous E. coli strain. Although significant titre rises in IgY antibodies were observed in the twice vaccinated group, antibodies did not confer significant protection in terms of pathological impact. Neither could transfer of maternal-derived antibodies to offspring be demonstrated. In conclusion, with the use of the present model for ascending infection, significant protection of an autogenous E. coli vaccine against neither a homologous nor a heterologous E. coli challenge could not be documented.

Effect of dietary manganese on antioxidant status and expressions of heat shock proteins and factors in tissues of laying broiler breeders under normal and high environmental temperatures.

To investigate the effect of Mn on antioxidant status and on the expressions of heat shock proteins/factors in tissues of laying broiler breeders subjected to heat challenge, we used a completely randomised design (n 6) with a factorial arrangement of 2 environmental temperatures (normal, 21±1°C, and high, 32±1°C)×3 dietary Mn treatments (a Mn-unsupplemented basal diet (CON), or a basal diet supplemented with 120 mg Mn/kg diet, either as inorganic Mn sulphate (iMn) or as organic Mn proteinate (oMn)). There were no interactions (P>0·10) between environmental temperature and dietary Mn in any of the measured indices. High temperature decreased (P<0·003) Mn content, and also tended (P=0·07) to decrease Cu Zn superoxide dismutase (CuZnSOD) activity in the liver and heart. However, an increased Mn superoxide dismutase (MnSOD) activity (P<0·05) and a slight increase in malondialdehyde level (P=0·06) were detected in breast muscle. Up-regulated (P<0·05) expressions of heat shock factor 1 (HSF1) and HSF3 mRNA and heat shock protein 70 (HSP70) mRNA and protein were found in all three tissues. Broiler breeders fed either iMn or oMn had higher tissue Mn content (P<0·0001), heart MnSOD and CuZnSOD activities (P<0·01) and breast muscle MnSOD protein levels (P<0·05), and lower (P<0·05) breast muscle HSP70 mRNA and protein levels compared with those fed CON. Broiler breeders fed oMn had higher (P<0·03) bone Mn content than those fed iMn. These results indicate that high temperature decreases Mn retention and increases HSP70, HSF1 and HSF3 expressions in the tissues of laying broiler breeders. Furthermore, dietary supplementation with Mn in either source may enhance the heart's antioxidant ability and inhibit the expression of HSP70 in breast muscle. Finally, the organic Mn appears to be more available than inorganic Mn for bone in laying broiler breeders regardless of environmental temperatures.

Comparative pathomorphological, bacteriological and serological examination of broiler breeders and pheasants experimentally infected with Ornithobacterium rhinotracheale.

The aim of the investigations was to determine the influence of Ornithobacterium rhinotracheale (ORT) on the development of pathomorphological lesions in the respiratory organs and on the health status of experimentally infected broiler breeders and pheasants from the rearing stage. There was no evidence of clinical signs in infected broiler breeder hens nor in the group of infected pheasants except for one bird in the latter group which exhibited slower movement and gasping. The frequency and intensity of pathomorphological lesions were higher in pheasants. The gross pathology findings were characterized mainly by redness of the mucosa of the upper respiratory tract and accumulation of mucous content in the nasal cavities, infraorbital sinuses, larynx and trachea. Histopathology confirmed the presence of inflammation of the upper respiratory tract. Lesions in the lungs included hyperaemia, granulomatous and fibrinous pneumonia. ORT was reisolated only from the group of infected pheasants. Reisolation was successful from the respiratory organs (trachea, larynx, infraorbital sinuses, and lungs) of eight out of 10 infected birds. The serological response in both species was characterized by rapid production of specific antibodies that reached a maximum level in the blood in the first week after experimental infection. The antibody titres decreased gradually and were maintained at a stable level until the 12th week after inoculation. Fourteen weeks post-inoculation specific antibodies could not be detected by enzyme-linked immunosorbent assay.

Effect of dietary manganese on antioxidant status and expression levels of heat-shock proteins and factors in tissues of laying broiler breeders under normal and high environmental temperatures.

To investigate the effect of Mn on antioxidant status and expression levels of heat-shock proteins/factors in tissues of laying broiler breeders subjected to heat challenge, we used a completely randomised design (n 6) with a factorial arrangement of 2 environmental temperatures (normal, 21 (sem 1)°C and high, 32 (sem 1)°C)×3 dietary Mn treatments (an Mn-unsupplemented basal diet (CON), or a basal diet supplemented with 120 mg Mn/kg diet as inorganic Mn sulphate (iMn) or organic Mn proteinate (oMn)). There were no interactions (P>0·10) between environmental temperature and dietary Mn in all of the measured indices. High temperature decreased (P<0·003) Mn content, and also tended (P=0·07) to decrease copper zinc superoxide dismutase (CuZnSOD) activity in the liver and heart. However, an increased manganese superoxide dismutase (MnSOD) activity (P<0·05) and a slight increase of malondialdehyde level (P=0·06) were detected in breast muscle. Up-regulated (P<0·05) expression levels of heat-shock factor 1 (HSF1) and HSF3 mRNA and heat-shock protein 70 (HSP70) mRNA and protein were found in all three tissues. Broiler breeders fed either iMn or oMn had higher tissue Mn content (P<0·0001), heart MnSOD and CuZnSOD activities (P<0·01) and breast muscle MnSOD protein levels (P<0·05), and lower (P<0·05) breast muscle HSP70 mRNA and protein levels than those fed CON. Broiler breeders fed oMn had higher (P<0·03) bone Mn content than those fed iMn. These results indicate that high temperature decreases Mn retention and increases HSP70 and HSF1, HSF3 expression levels in tissues of laying broiler breeders. Furthermore, dietary supplementation with Mn in either source may enhance heart antioxidant ability and inhibit the expression of HSP70 in breast muscle. Finally, the organic Mn appears to be more available than inorganic Mn for bone in laying broiler breeders regardless of environmental temperatures.

Lysine, methionine, phenylalanine, arginine, valine, isoleucine, leucine, and threonine maintenance requirements of broiler breeders.

Five hundred and sixty Cobb-Vantress broiler breeders were used to determine the maintenance requirement of dietary Arg, His, Ile, Leu, Lys, Met, Phe, Thr, and Val in 10 21-d assays using the comparative slaughter technique. Fifty sexually immature broiler breeder pullets per assay were given crystalline amino acid diets containing graded levels of Arg, His, Ile, Leu, Lys, Met, Phe, Thr, or Val, respectively, representing 0, 10, 20, 30, 40% of their suggested requirement level (NRC, 1994) with all other amino acids maintained at 40% of their suggested requirement level. Sixty hens were slaughtered prior to the beginning of the study to assess initial body composition at 3 weight groups. Linear regression lines (protein accretion vs. amino acid intake) were determined and the maintenance requirements were calculated based on zero protein accretion. The maintenance requirements expressed on a metabolic weight basis were determined to be 174, 94, 52, 81, 60, 126, 133, and 155 mg/kg(0.75)/d for Arg, Ile, Leu, Lys, Met, Phe, Thr, and Val, respectively. Additionally, the maintenance requirements, expressed on metabolic protein weight basis, were determined to be 651, 329, 172, 295, 223, 523, 478, and 546 mg/kgCP/d for Arg, Ile, Leu, Lys, Met, Phe, Thr, and Val, respectively. The requirement for His could not be established as the results obtained were outside of assay range.

Effects of maternal dietary EPA and DHA supplementation and breeder age on embryonic and post-hatch performance of broiler offspring: age and n-3 pufa affect embryonic and post-hatch performance.

Breeder age and nutrition are amongst the most important factors affecting progeny growth and development. The present experiment was carried out to evaluate the effects of n-3 fatty acid (FA), with special emphasis on the ratio of eicosapentaenoic (EPA, 20:5 n-3) and docosahexaenoic (DHA, 22:6 n-3) acid, provided to the diet of ageing broiler breeder hens at different ratios, on the incubation parameters and the performance of the offspring. Four hundred and eighty Ross-308 broiler breeder hens were fed one of four different diets (120/treatment), with an equal fat content. The control diet was a basal diet, rich in n-6 FAs (CON). Blends of fish oil were used to enrich the three other diets in n-3 FA and to obtain different EPA/DHA ratios of 1/1 (EPA=DHA), 1/2 (DHA) or 2/1 (EPA). Every 5 weeks, incubation parameters were assessed. Every 15 weeks, offspring was reared until slaughter age on a standard diet. Breeder age affected almost all incubation and post-hatch parameters, whereas n-3 FA treatment only lowered egg weight (p < 0.0001) and consequently hatched chick weight (p < 0.0001). Supplementation of EPA resulted in a higher proportional liver weight (p = 0.0219) at hatch, a lower body weight up to 28 days post-hatch (p = 0.0418), a lower daily weight gain (p = 0.0498) and a higher feed conversion ratio (p = 0.0395) during the starter period (p = 0.0498), resulting in a higher overall offspring feed conversion ratio (p = 0.0317) compared to the control diet. DHA supplementation, on the other hand, resulted in a lower residual yolk weight (p = 0.0220) and a higher overall offspring mortality (p = 0.0125). In conclusion, supplementation of n-3 FA could not counter the adverse effect of breeder flock age, but did not harm incubation or improve post-hatch performance, either. EPA and DHA affected offspring development differently during early post-hatch life.

Recent strategies to mitigate reproductive aging in male broiler breeders: A review.

The continued improvement of genetics, nutrition, and management has resulted in rapid growth, better feed efficiency, and higher meat yield with competitive prices in the broiler industry. Nowadays, however, it is well-documented that productive traits and fertility are negatively correlated, and male broiler breeders are exposed to a fertility decline after 45 wk of age. Considering a low male-to-female ratio in breeder flocks, roosters have a prominent impact on flock fertility. Consequently, strategies to maintain the fertility of male broiler breeders could guarantee the reproductive performance of commercial herds. Understanding reproductive aging demands deep insights into its molecular and physiological mechanisms. Over-weighting, Sertoli and Leydig cell dysfunctions, compromised antioxidant capacity, imbalance in sexual hormones, and epididymal lithiasis are among candidate culprits associated with reproductive aging in roosters. Nutritional and managing strategies have been successfully applied to modulate body weight, improve sperm fatty acid profile and antioxidant status, and boost spermatogenic and steroidogenic pathways. The current review characterizes the physiology and biochemistry of reproductive aging in male broiler breeders and then highlights strategies and their underlying mechanisms to mitigate this failure. In summary, applying one or more of the abovementioned strategies might result in consistent post-peak reproduction and benefit producers in the poultry industry.

Myotendinopathy of Unknown Etiology in Broiler Breeder Males.

This case series describes an emerging and ongoing lameness condition observed in broiler breeder males in flocks owned by a broiler integrator in the United States between February 2021 and April 2023. The lameness is characterized by an upright, penguin-like posture and gait. Affected flocks are typically 12-22 wk of age at presentation, but birds with similar stance and gross lesions can be observed as early as 1 day of age. Male mortality associated with this condition ranges from 0.01% to 6% per flock. The condition is infrequently observed in pullets from the female line but has not been observed in males (sex slips) from the female line. On postmortem examination, affected birds have bilateral hemorrhage due to a tearing of the iliotibialis muscles and fascia. In one case, a higher proportion of affected birds had unilateral lesions concurrently with broken legs or severe inguinal vaccine reaction. In this case, the affected leg was the weight-bearing leg. Histopathology confirmed the presence of hemorrhage in fascial sheaths surrounding major muscles, in addition to muscle fiber necrosis, edema, fibroplasia, and dissociation of tendon collagen. Bacteriology, histopathology, and clinical presentation identified no factors that were suggestive of an infectious etiology for this condition. No etiology has been established, but a suggested pathogenesis involves excessive biomechanical force resulting in tendon structural stress, leading to separation of tendon collagen fibers and associated muscle fiber stretching, separation, necrosis, and hemorrhage. The condition has been reported in multiple genetic lines, but the role of inheritance in the condition has not been fully evaluated.

Miotendinopatía de etiología desconocida en machos reproductores pesados. Esta serie de casos describe una condición de cojera emergente y recurrente observada en parvadas de machos reproductores pesados propiedad de un integrador de pollo de engorde en los Estados Unidos entre febrero del 2021 y abril del 2023. La cojera se caracteriza por una postura y desplazamientos corporales en forma erguida, parecidos a los de los pingüinos. Las parvadas afectadas suelen tener entre 12 y 22 semanas de edad en el momento de la presentación, pero se han podido observar aves con similar postura corporal y lesiones macroscópicas tan temprano como al primer día de edad. La mortalidad de los machos asociada con esta condición oscila entre el 0.01% y el 6% por parvada. La condición se observa con poca frecuencia en pollitas de la línea hembra, pero no se ha observado en machos provenientes de la misma línea hembra (errores de sexado). En el examen post mortem, las aves afectadas presentan hemorragia bilateral debido a un desgarramiento de los músculos iliotibiales y la fascia. En un caso, una mayor proporción de aves afectadas tuvieron lesiones unilaterales simultáneamente con patas rotas o una reacción postvacunal severa en la región inguinal. En este caso, la pierna afectada era la misma que soportaba peso. La histopatología confirmó la presencia de hemorragia en las vainas fasciales que rodean los músculos principales, además de necrosis de fibras musculares, edema, fibroplasia y disociación del colágeno del tendón. Mediante la bacteriología, la histopatología y la presentación clínica no se identificaron factores que sugirieran una etiología infecciosa para esta afección. No se ha establecido una etiología, pero una patogénesis sugerida implica una fuerza biomecánica excesiva que produce estrés estructural del tendón, lo que lleva a la separación de las fibras de colágeno del tendón y al estiramiento, separación, necrosis y hemorragia de las fibras musculares asociadas. La afección se ha informado en múltiples líneas genéticas, pero no se ha evaluado completamente el papel de la genética en esta condición.

The effect of hydroxy-selenomethionine on the productive and reproductive performance of old broiler breeders.

BACKGROUND: Selenium (Se) is a rare essential element that plays a vital role in the health and performance of animals. By interfering in the production of antioxidant enzymes such as glutathione peroxidase, thioredoxin reductase and methionine sulfoxide, Se plays a role in reducing the effects of oxidative stress and animal performance. OBJECTIVES: This study aimed to investigate the effect of hydroxy-selenomethionine (OH-SeMet) in the diet of broiler breeder and old broiler breeder roosters on productive performance, reproduction and sperm quality parameters. METHODS: For this purpose, 260 broiler breeders of the Ross 308 strain were used in a completely randomized design with four treatments and five replications (13 hens and one rooster in each replication). Experimental treatments included: (1) a basal diet without OH-SeMet (T1:control), (2) a broiler breeder diet without OH-SeMet and a rooster diet containing 0.1 mg/kg OH-SeMet (T2), (3) broiler breeder diet containing 0.1 mg/kg OH-SeMet and rooster diet without OH-SeMet (T3) and (4) broiler breeder and rooster diet contained 0.1 mg/kg OH-SeMet (T4). RESULTS: The results showed that T3 and T4 treatments improved egg production, egg weight, egg mass and feed conversion ratio (FCR) compared to the control treatment (p < 0.05). The fertility and hatchability percentages of T4 and T2 treatments increased compared to T1 and T3 treatments (p < 0.05). The rate of embryonic losses in T1 was higher than in other treatments. However, grade one chickens were higher in T4 than in other treatments (p < 0.05). Total motility and viability of sperms were significantly higher in T2 and T4 treatments than in T1 and T3 treatments. The sperm abnormality percentage and sperm MDA concentration decreased in T2 and T4 treatments. CONCLUSIONS: Therefore, using OH-SeMet may be a practical approach to help old broiler breeders' production and reproduction performance.

Development of a multivalent adjuvanted inactivated vaccine against variant arthrotropic avian reoviruses.

Variant avian reoviruses (ARVs) are economically important emerging pathogens of poultry, which mainly affect young broiler chickens and cause significant production losses. Currently, there are no effective commercial vaccines available for control and prevention of emerging variant ARVs. In this study, monovalent inactivated adjuvated (20% Emulsigen D) broiler breeder vaccines containing antigens from ARV genotype cluster (C) group -2, -4, -5, or -6, and a multivalent vaccine containing antigens from all the four indicated genotypic cluster groups were developed and evaluated for their efficacy in protecting broiler progenies against homologous or heterologous ARV challenge. The use of monovalent or multivalent inactivated vaccines in a prime-boost immunization strategy induced the production of ARV specific antibodies in broiler breeders. The maternal antibodies were effectively transferred to broiler progenies. Broiler progenies obtained from immunized breeders demonstrated milder clinical symptoms and reduced gross and histopathological lesions after homologous ARV challenge. More severe gross and histological lesions were observed in challenged progenies from unvaccinated broiler breeders. However, cross protection was not observed when either of the monovalent-vaccine groups were challenged with a heterologous virus. In addition, the progenies from the unvaccinated ARV challenged control or heterologous ARV challenged vaccinated groups had significantly reduced body weight gain (p < 0.01) than the unchallenged-control, challenged-multivalent, or homologous ARV-challenged monovalent vaccine groups. However, homologous ARV challenged progenies in the multivalent or monovalent vaccine groups had similar body weight gain as the control unchallenged group with significantly reduced viral load (p < 0.01) in the gastrocnemius tendon tissue. This study indicates that broad-spectrum protection of broiler progenies from variant ARV infections is feasible through the development of multivalent vaccines after proper characterization, selection and incorporation of multiple antigens based on circulating ARV genotypes in targeted regions.

Erysipelothrix rhusiopathiae Infection Associated with Swollen Head Syndrome in a Broiler Breeder Flock in North Georgia.

An unusual case of swollen head syndrome in a 55-wk-old broiler breeder flock was identified in north Georgia in the summer of 2019. The presenting complaint was elevated mortality and visibly swollen heads. Necropsy of affected birds on the farm primarily revealed signs of bacterial septicemia, with few large scab lesions near the vent area. Bacterial culture analysis identified multiple organisms, but the primary organism of interest was identified as Erysipelothrix rhusiopathiae, cultured from affected liver, lung, sinuses, and one swollen wattle of birds in the affected house. Histopathologic analysis identified gram-positive rod-shaped bacteria in the spleen and liver (consistent with bacterial septicemia) confirmed with special staining (Brown & Hopps Gram stain). These organisms were noted to be consistent with E. rhusiopathiae; E. rhusiopathiae infection in broiler breeder chickens is a rare occurrence and is primarily associated with turkeys and/or swine production systems.

Reporte de caso- Infección por Erysipelothrix rhusiopathiae asociada con el síndrome de cabeza hinchada en un pollo de engorde. En el verano del 2019, se identificó un caso inusual de síndrome de cabeza hinchada en una parvada de reproductoras de pollos de engorde de 55 semanas de edad en el norte de Georgia. Las observaciones iniciales incluyeron mortalidad elevada y cabezas visiblemente inflamadas. La necropsia de las aves afectadas en la granja reveló principalmente signos de septicemia bacteriana, con pocas lesiones costrosas grandes cerca del área de extractores de la ventilación. El análisis de cultivos bacterianos identificó múltiples organismos, pero el principal organismo de interés fue identificado como Erysipelothrix rhusiopathiae, cultivado a partir de hígado, pulmón, senos paranasales y de una barbilla inflamada de aves en la caseta afectada. El análisis histopatológico identificó bacterias grampositivas en forma de bastón en el bazo y el hígado (compatibles con septicemia bacteriana) confirmadas con tinción especial (tinción de Gram de Brown y Hopps). Se observó que estos organismos eran compatibles con E. rhusiopathiae; La infección por E. rhusiopathiae en pollos de engorde se presenta de forma esporádica y se asocia principalmente con sistemas de producción de pavos y/o cerdos.

Avian Pathogenic Escherichia coli (APEC) in Broiler Breeders: An Overview.

Poultry meat is one of the major animal protein sources necessary to meet the global protein demand. Sustainability in broiler production is the key to achieving its continuous supply, and broiler breeders play a critical role in maintaining this sustainability by providing good quality chicks. Colibacillosis, the disease caused by avian pathogenic Escherichia coli (APEC), causes severe economic losses to the poultry industry globally. Moreover, APEC causes an additional burden among broiler breeders, such as a decrease in egg production and mortality among these birds. There is vertical transmission of APEC to the broiler chicks through eggs, resulting in increased first-week mortality and subsequent horizontal transmission at the hatchery. In this regard, the vertical transmission of antibiotic resistance genes is another concern that needs attention. Controlling several diseases in broiler breeders would possibly reduce the first-week mortality in chicks, thereby maintaining the production level. For that, constant monitoring of the bacterial populations is critical. Moreover, amidst the increased antibiotic resistance pattern, more focus on alternative treatment strategies like vaccines, probiotics, and bacteriophages is necessary. Future research focusing on strategies to mitigate APEC in broiler breeders would be one of the finest solutions for sustainable broiler production.

Prevalence of Potential Pathogenic and Antimicrobial Resistant Escherichia coli in Danish Broilers.

Avian pathogenic Escherichia coli (APEC) are important bacteria in broiler production in terms of economy, welfare, and use of antibiotics. During a previous outbreak of APEC in the Nordic countries, it was suggested that the pathogenic clones of E. coli causing the outbreak originated from grandparent stock and were transmitted to the offspring, causing increased first week mortality. This study investigated whether the pathogenic potential of E. coli at the parent and broiler level differs in relation to pathogenic potential described by the level of virulence-associated genes and pattern of antimicrobial resistance. The hypothesis was that, due to higher biosecurity at the parent level, the E. coli population will show a lower level of antimicrobial resistance and carry fewer virulence-associated genes, as a result of fewer E. coli infections observed. From four parent flocks and eight broiler flocks, 715 E. coli were isolated from cloacal swabs of newly hatched chickens (Ross 308). The isolated E. coli were characterized by eight virulence-associated genes and phenotypic resistance against six antimicrobials. It was found that the prevalence of virulence-associated genes and phenotypic antimicrobial resistance varied significantly between flocks, and the virulence-associated genes papC and irp2 and resistance against ampicillin were significantly more prevalent in breeder flocks compared to broiler flocks.

Differences in gut bacterial community composition between modern and slower-growing broiler breeder lines: Implications of growth selection on microbiome composition.

In the last century broiler chicken lines have undergone an extensive breeding regime aimed primarily at growth and high meat yield. It is not known if breeding has also resulted in a change to the broiler breeder's associated gut microbiota. Here we compared the gut microbiota of 37-week-old commercial Cobb breeding dams with dams from a broiler Legacy line which has not undergone selection since 1986. The dams from both lines were kept together in the same shed under the same management protocol from day of hatch to avoid additional confounders. We chose this age to allow significant bacterial exchange, thus avoiding exposure dependent artifacts and so that we could compare dams at the same developmental state of adulthood and peak laying performance. Significant differences in the composition of the cecum bacterial communities were found. Bacteria of the genus Akkermansia, implicated in mucin degradation and associated with host metabolic health, accounted for 4.98% ± 5.04% of the Cobb cecum community, but were mostly absent from the ceca of the Legacy line dams. Inversely, Legacy dams had higher levels of Clostridiales, Lactobacillales and Aeromonadales. These results show that breeding has resulted in a change in the gut microbiota composition, likely by changing the physiological conditions in the mucosa. It remains unclear if changes in gut microbiota composition are a part of the mechanism affecting growth or are a secondary result of other physiological changes accelerating growth. Therefore, the identification of these changes opens the door to further targeted research.