Exposure to calls before hatching affects the post-hatching behaviour of domestic chickens.

The soundscape experienced by animals early in life can affect their behaviour later in life. For birds, sounds experienced in the egg can influence how individuals learn to respond to specific calls post-hatching. However, how early acoustic experiences affect subsequent social behaviour remains unknown. Here, we investigate how exposure to maternal 'cluck' calls pre-hatching affects the behaviour of domestic chickens (Gallus gallus domesticus) at 3-5 days and 17-21 days old. We incubated eggs and played cluck calls to half of them. After hatching, we raised chicks in small groups occupying different enclosures. At 3-5 days old, we tested chicks' responses to three stimuli: (i) background sound, (ii) chick calls and (iii) cluck calls. We found that the pre-hatching experience of cluck calls reduced the likelihood of moving in response to all three stimuli. At 17-21 days old, some chicks explored beyond their own enclosure and 'visited' other groups. Chicks exposed to cluck calls before hatching were three times more likely to enter another group's enclosure than control chicks, and this was unaffected by the chicks' social connectedness. Our results indicate age- and context-dependent responses of chicks to pre-hatching cluck-call playbacks, with potential long-term effects on individual social behaviour.

Plasma and Tissue Amikacin Concentrations Following Regional Limb Perfusion of Chickens (Gallus gallus domesticus).

Intravenous regional limb perfusion (IVRLP) has been used in the treatment of pododermatitis and distal limb infections, which are significant causes of morbidity in avian species. This intravenous drug administration technique is designed to achieve high drug tissue concentrations while minimizing systemic toxic effects. Amikacin is commonly used for IVRLP in veterinary medicine, but dosing guidelines have not been established for its use in birds. The current study aimed to determine the tissue concentration of amikacin after a single IVRLP administration in healthy, euhydrated leghorn hen chickens (Gallus gallus domesticus). Chickens received a single IVRLP dose of 10 mg/kg amikacin and were euthanatized posttreatment at 1 hour (n = 6), 12 hours (n = 6), and 24 hours (n = 6) to assess tissue and synovial fluid concentrations of amikacin in the injected leg. Mean tissue concentrations were highest 1 hour post-IVRLP (synovial fluid = 153.0 µg/mL, metatarsal pad tissue = 26.05 µg/mL) before declining at the 12- and 24-hour time points. This indicates that administration of amikacin via IVRLP can reach minimum inhibitory concentrations of common bacterial isolates in tissues after a single treatment with 10 mg/kg amikacin. Regional limb perfusion every 24 hours is recommended, although the minimum days of treatment may be case dependent and vary based on response to therapy.

Isolation and characterization of enterococci from poultry reveals high incidence of Enterococcus thailandicus in Victoria, Australia.

AIMS: Antibiotic resistance is a global health crisis. Roughly two-thirds of all antibiotics used are in production animals, which have the potential to impact the development of antibiotic resistance in bacterial pathogens of humans. There is little visibility on the extent of antibiotic resistance in the Australian food chain. This study sought to establish the incidence of antibiotic resistance among enterococci from poultry in Victoria. METHODS AND RESULTS: In 2016, poultry from a Victorian processing facility were swabbed immediately post-slaughter and cultured for Enterococcus species. All isolates recovered were speciated and tested for antibiotic susceptibility to 12 antibiotics following the Clinical Laboratory Standards Institute guidelines. A total of 6 farms and 207 birds were sampled and from these 285 isolates of Enterococcus were recovered. Eight different enterococcal species were identified as follows: E. faecalis (n = 122; 43%), E. faecium (n = 92; 32%), E. durans (n = 35; 12%), E. thailandicus (n = 23; 8%), E. hirae (n = 10; 3%), and a single each of E. avium, E. gallinarum, and E. mundtii. Reduced susceptibility to older classes of antibiotics was common, in particular: erythromycin (73%), rifampin (49%), nitrofurantoin (40%), and ciprofloxacin (39%). Two vancomycin-intermediate isolates were recovered, but no resistance was detected to either linezolid or gentamicin. CONCLUSIONS: The relatively high numbers of a recently described species, E. thailandicus, suggest this species might be well adapted to colonize poultry. The incidence of antibiotic resistance is lower in isolates from poultry than in human medicine in Australia. These results suggest that poultry may serve as a reservoir for older antibiotic resistance genes but is not driving the emergence of antimicrobial resistance in human bacterial pathogens. This is supported by the absence of resistance to linezolid and gentamicin.

Infestation prevalence, spatio-temporal distribution, phylogenetic positioning, and pathogen investigation of Argas persicus ticks in domestic hens (Gallus gallus domesticus) from Pakistan.

Soft ticks pose significant health risks as vectors of various pathogens. This study explored the spatio-temporal distribution and genetic relationships of the soft tick species Argas persicus infesting domestic hens (Gallus gallus domesticus) across different districts in Pakistan. An examination of 778 hens revealed a notable tick infestation prevalence of 70.82%, with a total of 1299 ticks collected from 551 hens. The overall mean intensity was 2.19 soft ticks per infested chicken, and the overall mean abundance was 1.61 soft ticks per examined hen. Morphological identification confirmed all collected ticks (n = 1210) as A. persicus, comprising 719 males, 333 females, 121 nymphs, and 38 larvae. The Haveli, Muzaffarabad, and Kotli districts had the highest infestation rates, while Bagh had the lowest. Molecular analyses of tick DNA, focusing on 16S rDNA and 12S rDNA sequences, revealed genetic similarities among A. persicus soft ticks from Pakistan and other regions, providing insights into their evolutionary history. Importantly, no Babesia, Rickettsia, or Anaplasma infections were detected in the examined samples. These findings enhance the understanding of soft tick infestation patterns and the genetic diversity of A. persicus in the studied region.

Saline, chlorhexidine, and povidone-iodine alone or in combination with iodine povacrylex are effective antiseptics in chickens (Gallus gallus domesticus).

OBJECTIVE: To evaluate the topical antiseptic activity of saline, chlorhexidine (CHX), and povidone-iodine (PI) scrubs on the skin of chickens with or without the addition of DuraPrep (DP). ANIMALS: 7 healthy adult Orpington hens (Gallus gallus domesticus). METHODS: The right apterium corporale laterale was swabbed for standard aerobic bacterial culture and colony-forming unit (CFU) determination. The apterium was divided into 3 areas and treated with sterile saline, CHX, or PI. Samples were collected by swabbing each area before and after additional treatment with DP. CFU's were counted after 48 hours of incubation. Statistical analysis was performed using a linear mixed model with a continuous outcome. RESULTS: Compared to saline, CHX and PI treatment without DP decreased CFU count by 119 (95% CI, 55 to 183; P < .001) and 123 (95% CI, 58 to 187; P < .001), respectively. The application of DP after CHX and PI further decreased CFU counts by 6 (P = .01) and 9 (P = .01), respectively. DP after saline treatment decreased counts by 128 CFU (95% CI, 63 to 192; P < .001). No significant difference was detected between saline, PI, or CHX after DP application (-1.0 CFU; 95% CI, 63.4 to -65.4; P = .98 for both PI and CHX). CLINICAL RELEVANCE: CHX or PI provided greater reductions in bacterial CFU than saline, and all combinations with DP provided similar results. No notable cutaneous reactions were detected at any point. This data suggests that a scrub protocol including CHX or PI with DP is acceptable in surgical site preparation of chickens.

Isolation and biochemical characterization of novel acid phosphatase and zinc-dependent acid phosphatase from the chicken's brain.

The AcPase exhibits a specific activity of 31.32 U/mg of protein with a 728-fold purification, and the yield of the enzyme is raised to 3.15 %. The Zn2+-dependent AcPase showed a purification factor of 1.34 specific activity of 14 U/mg of proteins and a total recovery of 5.14. The SDS-PAGE showed a single band corresponding to a molecular weight of 18 kDa of AcPase and 29 kDa of Zn2+-dependent AcPase. The AcPase enzyme has shown a wide range of substrate specificity for p-NPP, phenyl phosphate and FMN, while in the case of ZnAcPase α and ß-Naphthyl phosphate and p-NPP were proved to be superior substrates. The divalent metal ions like Mg2+, Mn2+, and Ca2+ increased the activity, while other substrates decreased the enzyme activity. The Km (0.14 mM) and Vmax (21 µmol/min/mg) values of AcPase were higher than those of Zn2+-AcPase (Km = 0.5 mM; Vmax = 9.7 µmol/min/mg). The Zn2+ ions activate the Zn2+-AcPase while Fe3+, Al3+, Pb2+, and Hg2+ showed inhibition on enzyme activity. Molybdate, vanadate and phosphate were found to be competitive inhibitors of AcPase with Ki values 316 µM, 185 µM, and 1.6 mM, while in Zn2+-AcPase tartrate and phosphate also showed competitive inhibition with Ki values 3 mM and 0.5 mM respectively.

Antiemetic activity of abietic acid possibly through the 5HT3 and muscarinic receptors interaction pathways.

The present study was designed to evaluate the antiemetic activity of abietic acid (AA) using in vivo and in silico studies. To assess the effect, doses of 50 mg/kg b.w. copper sulfate (CuSO4⋅5H2O) were given orally to 2-day-old chicks. The test compound (AA) was given orally at two doses of 20 and 40 mg/kg b.w. On the other hand, aprepitant (16 mg/kg), domperidone (6 mg/kg), diphenhydramine (10 mg/kg), hyoscine (21 mg/kg), and ondansetron (5 mg/kg) were administered orally as positive controls (PCs). The vehicle was used as a control group. Combination therapies with the referral drugs were also given to three separate groups of animals to see the synergistic and antagonizing activity of the test compound. Molecular docking and visualization of ligand-receptor interaction were performed using different computational tools against various emesis-inducing receptors (D2, D3, 5HT3, H1, and M1-M5). Furthermore, the pharmacokinetics and toxicity properties of the selected ligands were predicted by using the SwissADME and Protox-II online servers. Findings indicated that AA dose-dependently enhances the latency of emetic retching and reduces the number of retching compared to the vehicle group. Among the different treatments, animals treated with AA (40 mg/kg) exhibited the highest latency (98 ± 2.44 s) and reduced the number of retching (11.66 ± 2.52 times) compared to the control groups. Additionally, the molecular docking study indicated that AA exhibits the highest binding affinity (- 10.2 kcal/mol) toward the M4 receptors and an elevated binding affinity toward the receptors 5HT3 (- 8.1 kcal/mol), M1 (- 7.7 kcal/mol), M2 (- 8.7 kcal/mol), and H1 (- 8.5 kcal/mol) than the referral ligands. Taken together, our study suggests that AA has potent antiemetic effects by interacting with the 5TH3 and muscarinic receptor interaction pathways. However, additional extensive pre-clinical and clinical studies are required to evaluate the efficacy and toxicity of AA.

Investigating the impact of nutritional insufficiency on parahippocampal neurons in domestic chickens, Gallus gallus domesticus.

Over time, scientists have been fascinated by the complex connections among nutrition, brain development, and behavior. It's been well understood that the brain's peak performance relies on having the right nutrients available. Thus, nutritional insufficiency, where an organism lacks vital nutrients crucial for optimal growth and function, can upset the body's balance, potentially triggering stress responses. However, our grasp of how the brain reacts to insufficient nutrition, particularly in avian species like domestic chickens, has shown inconsistencies in our understanding. Domestic chickens have frequently served as subjects for studying memory and learning, primarily focusing on the hippocampus-a region highly responsive to environmental changes. Yet, another critical brain region, the parahippocampal region, integral to memory and spatial cognition, had received relatively little attention concerning the consequences of inadequate nutrition and hydration. To address this knowledge gap, our study sought to investigate the impact of stress induced by nutritional insufficiency on the neuronal cells within the region parahippocampalis in two distinct age groups of domestic chickens, Gallus gallus domesticus: fifteen and thirty days old. We employed the Golgi-Cox-Impregnation technique to explore whether the structural characteristics of neuronal cells, specifically the dendritic spines, underwent changes under transient stressful conditions during these crucial developmental stages. The results were intriguing. Stress evidently induced observable alterations in the dendritic spines of the parahippocampal neuronal cells, with the extent of these changes being age-dependent. In fifteen-day-old chickens, stress prompted substantial modifications in the dendritic spines of parahippocampal multipolar and pyramidal neurons. In contrast, among thirty-day-old chickens, the response to stress was less comprehensive, with only specific parahippocampal multipolar neurons displaying such alterations. These findings underscored the influential role of stress in reshaping the structure of parahippocampal neurons and emphasized the importance of considering age when studying the impact of stress on the brain. Through this research, we aim to enhance our understanding of the intricate interplay between stress, brain structure, and the critical role of adequate nutrition, especially during pivotal developmental stages. Our future research objectives include a deeper investigation into the intracellular events including cellular and molecular mechanisms precipitating these changes and determining whether these alterations have downstream effects on crucial brain functions like learning and memory.

Anti-diarrheal effect of piperine possibly through the interaction with inflammation inducing enzymes: In vivo and in silico studies.

Piperine is a natural alkaloid that possesses a variety of therapeutic properties, including anti-inflammatory, antioxidant, antibacterial, and anticarcinogenic activities. The present study aims to assess the medicinal benefits of piperine as an anti-diarrheal agent in a chick model by utilizing in vivo and in silico techniques. For this, castor oil was administered orally to 2-day-old chicks to cause diarrhea. Bismuth subsalicylate (10 mg/kg), loperamide (3 mg/kg), and nifedipine (2.5 mg/kg) were used as positive controls, while the vehicle was utilized as a negative control. Two different doses (25 and 50 mg/kg b.w.) of the test sample (piperine) were administered orally, and the highest dose was tested with standards to investigate the synergistic activity of the test sample. In our findings, piperine prolonged the latent period while reducing the number of diarrheal feces in the experimental chicks during the monitoring period (4 h). At higher doses, piperine appears to reduce diarrheal secretion while increasing latency in chicks. Throughout the combined pharmacotherapy, piperine outperformed bismuth subsalicylate and nifedipine in terms of anti-diarrheal effects with loperamide. In molecular docking, piperine exhibited higher binding affinities towards different inflammatory enzymes such as cyclooxygenase 1 (-7.9 kcal/mol), cyclooxygenase 2 (-8.4 kcal/mol), nitric oxide synthases (-8.9 kcal/mol), and L-type calcium channel (-8.8 kcal/mol), indicating better interaction of PP with these proteins. In conclusion, piperine showed a potent anti-diarrheal effect in castor oil-induced diarrheal chicks by suppressing the inflammation and calcium ion influx induced by castor oil.

Effect of Puncture Vine on Growth Performance, Carcass and Meat Traits, Metabolic and Immunological Blood Indicators, and Selected Cecal Microbiota in Broiler Chickens.

This study investigated the effects of puncture vine (Tribulus Terrestris) addition on the performance, carcass and meat characteristics, selected metabolic and immunological blood indicators, some microbiota, and short-chain fatty acids. A total of 252 1-day-old broilers were distributed to three treatments with 12 cages as replicates per treatment (T1 = 0.0%, T2 = 0.08%, and T3 = 0.16% puncture vine). Performance parameters and metabolic and immunological serum indicators were measured in each feeding phase, while carcass characteristics, meat quality, cecal microflora, and short-chain fatty acids were measured at 35 days. Results showed that live weight, weight gain, production efficiency, and meat component color were lower in initial and ultimate at T3, while the percentages of the legs and gizzard were higher at T2 than T1. The relative weight of cooking loss was higher in T2 and T3, but the myofibril fragmentation index was lower than T1. Total protein and globulin were higher in T2 and T3 (14 days old), and the glucose level was lower in T2 (35 days old) than at T1. Interleukins (IL-4, IL-6, and IL-10) and tumor necrosis factor-α (TNF-α) were higher in T2 than T1 and T3 (35 days old). Puncture vine has antimicrobial activity against Escherichia coli and Salmonella spp., while Lactobacillus spp. was higher in T2. The total short-chain fatty acid content was higher in chickens fed puncture vine. These results indicate that the use of puncture vine powder as a natural alternative at a dosage of 0.08% has a safe effect on the performance, carcass and meat characteristics, and health of broilers.

Sensitivity to the role of an animated agent from observed interactions in newborn chicks (Gallus gallus).

Few month old human infants are able to detect the social roles of artificial agents and consistently choose the object behaving as 'approacher' rather than 'repulser'. This preference has been considered evidence of a pre-linguistic and pre-cultural origin of the social mind. Similar preferences have not been described in other species, though comparative data could help clarify the nature of this phenomenon and its evolutionary origin. In this study, we investigated sensitivity to the social role of an artificial agent in domestic chicks. Birds offer an excellent model to study the evolutionary roots of cognitive abilities, since they separated from mammals over 300 Ma. Moreover, the investigation of newly hatched chicks allows control for previous experience. After being exposed to computer-presented animations depicting an interaction among two agents, chicks underwent a free choice test among those same objects. While no initial evidence of a clear preference emerged from the planned analysis, chicks in the experimental condition showed a preference for the 'approacher' when controlling for side bias, mirroring human infants behaviour. This suggests the existence of an early ability to discriminate agents from their interactions, independent from any social experience.

Tungiasis: Participation of Cats and Chickens in the Dispersion and Maintenance of the Disease in an Endemic Tourist Area in Brazil.

Tunga spp. are fleas commonly found in impoverished tropical regions. In Vila Juerana, a tourist community in Ilheus, Bahia, Brazil, where tungiasis is endemic, dogs are the main host of fleas during their life cycle. However, there is no information about the role of cats and chickens in tungiasis in the village. Of the 272 households investigated, 112 had domestic animals, 48 had only dogs, 28 had only cats, and nine had only chickens. Of the 27 households with cohabitation among species, 16 had cats and dogs, eight had chickens and dogs, and three had dogs, cats, and chickens. The injuries due to tungiasis were ranked according to the Fortaleza classification, considering stages I, II, and III as viable lesions. The paws/feet of 71/111 (63.9%) cats and 173/439 (39.4%) chickens were inspected. Dogs that lived with positive cats and chickens also were inspected. Among the 38% (27/7; 95% IC 26.74-49.32) positive cats, 16 cohabited houses with infected dogs but none lived with positive chickens. Of the chickens, 2.3% (4/173; 95% IC 0.07-4.5) had lesions caused by tungiasis. In each household where a cat was infected, the dog was also positive. Two chickens cohabited with an infected dog and the other two did not coexist with other species. Cohabitation with infected dogs and the absence of house confinement restrictions in Vila Juerana make cats important carriers that spread tungiasis in this community. Chickens had a low frequency of tungiasis lesions despite living in proximity to infected dogs and cats.

Antiemetic effects of sclareol, possibly through 5-HT3 and D2 receptor interaction pathways: In-vivo and in-silico studies.

BACKGROUND: Emesis is a complex physiological phenomenon that serves as a defense against numerous toxins, stressful situations, adverse medication responses, chemotherapy, and movement. Nevertheless, preventing emesis during chemotherapy or other situations is a significant issue for researchers. Hence, the majority view contends that successfully combining therapy is the best course of action. In-vivo analysis offers a more comprehensive grasp of how compounds behave within a complex biological environment, whereas in-silico evaluation refers to the use of computational models to forecast biological interactions. OBJECTIVES: The objectives of the present study were to evaluate the effects of Sclareol (SCL) on copper sulphate-induced emetic chicks and to investigate the combined effects of these compounds using a conventional co-treatment approach and in-silico study. METHODS: SCL (5, 10, and 15 mg/kg) administered orally with or without pre-treatment with anti-emetic drugs (Ondansetron (ODN): 24 mg/kg, Domperidone (DOM): 80 mg/kg, Hyoscine butylbromide (HYS): 100 mg/kg, and Promethazine hydrochloride (PRO): 100 mg/kg) to illustrate the effects and the potential involvement with 5HT3, D2, M3/AChM, H1, or NK1 receptors by SCL. Furthermore, an in-silico analysis was conducted to forecast the role of these receptors in the emetic process. RESULTS: The results suggest that SCL exerted a dose-dependent anti-emetic effect on the chicks. Pretreatment with SCL-10 significantly minimized the number of retches and lengthened the emesis tendency of the experimental animals. SCL-10 significantly increased the anti-emetic effects of ODN and DOM. However, compared to the ODN-treated group, (SCL-10 + ODN) group considerably (p < 0.0001) extended the latency duration (109.40 ± 1.03 s) and significantly (p < 0.01) decreased the number of retches (20.00 ± 0.70), indicating an anti-emetic effect on the test animals. In in-silico analysis, SCL exhibited promising binding affinities with suggesting receptors. CONCLUSION: SCL-10 exerted an inhibitory-like effect on emetic chicks, probably through the interaction of the 5HT3 and D2 receptors. Further studies are highly appreciated to validate this study and determine the precise mechanism(s) behind the anti-emetic effects of SCL. We expect that SCL-10 may be utilized as an antiemetic treatment in a single dosage form or that it may function as a synergist with other traditional medicines.

Nociception in Chicken Embryos, Part II: Embryonal Development of Electroencephalic Neuronal Activity In Ovo as a Prerequisite for Nociception.

Chicken culling has been forbidden in Germany since 2022; male/female selection and male elimination must be brought to an embryonic status prior to the onset of nociception. The present study evaluated the ontogenetic point at which noxious stimuli could potentially be perceived/processed in the brain in ovo. EEG recordings from randomized hyperpallial brain sites were recorded in ovo and noxious stimuli were applied. Temporal and spectral analyses of the EEG were performed. The onset of physiological neuronal signals could be determined at developmental day 13. ERP/ERSP/ITC analysis did not reveal phase-locked nociceptive responses. Although no central nociceptive responses were documented, adequate EEG responses to noxious stimuli from other brain areas cannot be excluded. The extreme stress impact on the embryo during the recording may overwrite the perception of noniceptive stimuli. The results suggest developmental day 13 as the earliest embryonal stage being able to receive and process nociceptive stimuli.

Nociception in Chicken Embryos, Part III: Analysis of Movements before and after Application of a Noxious Stimulus.

Many potentially noxious interventions are performed on chicken embryos in research and in the poultry industry. It is therefore essential and in the interest of animal welfare to be able to precisely define the point at which a chicken embryo is capable of nociception in ovo. The present part III of a comprehensive study examined the movements of developing chicken embryos with the aim of identifying behavioral responses to a noxious stimulus. For this purpose, a noxious mechanical stimulus and a control stimulus were applied in a randomized order. The recorded movements of the embryos were evaluated using the markerless pose estimation software DeepLabCut and manual observations. After the application of the mechanical stimulus, a significant increase in beak movement was identified in 15- to 18-day-old embryos. In younger embryos, no behavioral changes related to the noxious stimulus were observed. The presented results indicate that noxious mechanical stimuli at the beak base evoke a nocifensive reaction in chicken embryos starting at embryonic day 15.

Nociception in Chicken Embryos, Part I: Analysis of Cardiovascular Responses to a Mechanical Noxious Stimulus.

Although it is assumed that chicken embryos acquire the capacity for nociception while developing in the egg, an exact time point has not yet been specified. The present research was an exploratory study aiming to determine when the capacity of nociception emerges during embryonic development in chickens. Changes in blood pressure and heart rate (HR) in response to a noxious mechanical stimulus at the base of the beak versus a light touch on the beak were examined in chicken embryos between embryonic days (EDs) 7 and 18. Mean arterial pressure (MAP) was the most sensitive parameter for assessing cardiovascular responses. Significant changes in MAP in response to a noxious stimulus were detected in embryos at ED16 to ED18, whereas significant changes in HR were observed at ED17 and ED18. Infiltration anesthesia with the local anesthetic lidocaine significantly reduced the response of MAP on ED18, so the measured cardiovascular changes may be interpreted as nociceptive responses.

Manganese-enhanced magnetic resonance imaging reveals light-induced brain asymmetry in embryo.

The idea that sensory stimulation to the embryo (in utero or in ovo) may be crucial for brain development is widespread. Unfortunately, up to now evidence was only indirect because mapping of embryonic brain activity in vivo is challenging. Here, we applied for the first time manganese enhanced magnetic resonance imaging (MEMRI), a functional imaging method, to the eggs of domestic chicks. We revealed light-induced brain asymmetry by comparing embryonic brain activity in vivo of eggs that were stimulated by light or maintained in the darkness. Our protocol paves the way to investigation of the effects of a variety of sensory stimulations on brain activity in embryo.

Radiographic Measurements of Internal Organs in Rhode Island Red Hybrid Hens (Gallus gallus domesticus) and Their Evolution During Egg Formation.

Backyard poultry hens are becoming very popular as pets, and thus the demand for treating the individual chicken is increasing. Few basic diagnostic techniques commonly used in small animal practice have been evaluated in this species. At the moment, there is no study in backyard hens describing radiographic measurements of internal organs contrary to psittacine birds or birds of prey. Moreover, the effect of egg laying on these measurements has not been studied in avian species even though it could affect radiographic measurements depending on the stage of egg formation. This is of particular concern in laying hens since they are able to lay on a daily basis. Thirteen adult hens and 3 juvenile Rhode Island red hybrid hens (Gallus gallus domesticus) were used to evaluate which organs can be reliably measured and to provide preliminary reference values for clinically healthy chickens. Additionally, whole body radiographs were collected every 2 hours over 24 hours in 5 adult hens to study the evolution of these measurements throughout egg formation. Organs that could be clearly delimitated on radiographs were measured, and the only organs that could be reliably measured were the heart and liver silhouettes. These measurements were significantly higher in adult compared to juvenile hens (P = 0.024). Among the different organ ratios, heart width: total liver width ratio was the only significantly different measurement and was higher in juvenile hens (P = 0.024). Hepatic silhouette measurements and ratios were found to increase over time (P < 0.02) but did not follow the progress of egg mineralization. Eggshell thickness was found to be a promising parameter to evaluate the stage of egg formation, and thus should be taken into account when trying to establish reference intervals for radiographic measurements of internal organs in laying hens.

Effect of Hooding on Physiological Parameters During Manual Restraint in Rhode Island Red Hybrid Hens (Gallus gallus domesticus).

Manual handling of chickens is required for many veterinary, research, and breeding procedures. This study aimed to assess the changes in physiological parameters over time during manual restraint of chickens, as well as the effect of hooding on these parameters. Heart rate, heart rate variability, respiratory rate, and body temperature were measured every 3 minutes for 15 minutes during manual restraint in 13 adult laying hens (Gallus gallus domesticus). Heart rate variability was significantly higher in hooded hens than in nonhooded hens (P= 0.003) but was not significant over time. Hooded hens were also found to have significantly lower heart rate (P = 0.043) and respiratory rate (P = 0.042) compared to nonhooded hens. Heart rate and respiratory rate significantly decreased over time, independent of the use of the hood (P = 0.008; P = 0.01, respectively). Temperature was found to increase significantly (P = 0.001) over time for both groups. Overall, hooding increased heart rate variability, a factor associated with a lower stress level, and decreased heart rate and respiratory rate. In conclusion, these data suggest that the use of the hood reduces stress levels in birds during manual restraint. Therefore, the use of the hood is encouraged for short (less than 15 minutes) painless procedures, such as physical examination or radiographic acquisition.

Pharmacokinetics and Safety of Sulfamethoxazole-Trimethoprim After Oral Administration of Single and Multiple Doses to Rhode Island Red Chickens (Gallus gallus domesticus).

Sulfamethoxazole-trimethoprim (SMZ-TMP), a commonly prescribed antibiotic for backyard hens, is neither Food and Drug Administration approved nor prohibited in laying hens in the United States. The aim of this study was to determine whether plasma concentrations above targeted minimum inhibitory concentration breakpoint values for Enterobacteriaceae could be achieved with oral dosing. Five Rhode Island red hens (Gallus gallus domesticus) were administered a single dose of 96 mg/kg SMZ-TMP (80 mg/kg SMZ and 16 mg/kg TMP) IV followed by the same dose orally after a washout period. Following oral dosing, mean SMZ concentrations exceeded the target breakpoint for approximately 12 hours; however, TMP only briefly exceeded the target breakpoint. Bioavailability was 60.5% for SMZ and 82.0% for TMP. Ten naïve birds were allocated into control (n = 4) and treatment (n = 6) groups for a 7-day multi-dose study. Treatment birds received an oral suspension dosed at 16 mg/kg TMP and 80 mg/kg SMZ every 48 hours (on days 1, 3, 5, and 7); TMP tablets were additionally dosed at 25 mg/bird on days 1, 3, 5, and 7, and 50 mg/bird on days 2, 4, and 6. Plasma SMZ-TMP concentrations were measured on a multiple time interval by ultraperformance liquid chromatography-mass spectrometry, and pharmacokinetic analyses were performed using a noncompartmental model. No accumulation for either drug was noted following repeated dosing, and no statistical differences in biochemical values, packed cell volumes, or weight were found between pre- and posttreatment in either the treatment or control groups. Sulfamethoxazole (80 mg/kg q48h PO) and TMP (24.1-28.0 mg/kg q24h PO) maintained therapeutic plasma concentrations at or exceeding the minimum inhibitory concentration breakpoint of Enterobacteriaceae for 72 and 24 hours for TMP and SMZ, respectively, without evidence of adverse effects or drug accumulation. Further studies are needed to refine this dosage regimen and evaluate adverse effects in ill birds.