APPROXIMATION OF GROWTH INDICATORS AND ANALYSIS OF INDIVIDUAL GROWTH CURVES BY LINEAR DIMENSIONS OF TUBULAR BONES IN CHICKENS OF MEAT PRODUCTION DIRECTION DURING POSTNATAL PERIOD OF ONTOGENESIS

Medical and biological sciences, including morphology, now require the introduction of the latest information technologies and mathematical methods to process the obtained and accumulated research results. To study the growth dynamics of body weight in domestic birds, classical growth models, Gompertz, were used for the purpose of quantitative description of the growth processes in biological objects, in particular for the growth and development of birds – Von Bertalanffy, Richards, and hyperbolastic models. The research material was tubular bones of the thoracic (humerus, ulna, and radius) and pelvic (femur, tibia, and tarsometatarsus) limbs in birds of meat production (broiler chickens and laying hens from the parent broiler flock of Cobb-500 strain) of different age groups during the postnatal period of ontogenesis. An appropriate regression analysis of experimental data based on known growth models was performed to solve the goal of obtaining growth curves and identifying special points (extremes, inflections, etc.), to build a picture of the overall development of the body as a whole and individual bones of the extremities. The most biologically suitable growth models for describing the growth dynamics of the body as a whole and individual studied bones were determined. The absence of a unified growth model of linear parameters of different tubular bones in meat producing chickens during the postnatal period of ontogenesis was established. This implies the need for a clear selection of growth models taking into account age, species, breed, keeping and feeding conditions of domestic birds. The growth model that best describes the body weight dynamics of broiler chickens is the hyperbolastic growth model of the H3 type, and in laying hens from the parent broiler flock – the Brody growth model.

The link between broiler flock heterogeneity and cecal microbiome composition

Background Despite low genetic variation of broilers and deployment of considerate management practices, there still exists considerable body weight (BW) heterogeneity within broiler flocks which adversely affects the commercial value. The purpose of this study was to investigate the role of the cecal microbiome in weight differences between animals. Understanding how the gut microbiome may contribute to flock heterogeneity helps to pave the road for identifying methods to improve flock uniformity and performance. Results Two hundred eighteen male broiler chicks were housed in the same pen, reared for 37 days, and at study end the 25 birds with highest BW (Big) and the 25 birds with lowest BW (Small) were selected for microbiome analysis. Cecal contents were analyzed by a hybrid metagenomic sequencing approach combining long and short read sequencing. We found that Big birds displayed higher microbial alpha diversity, higher microbiome uniformity (i.e. lower beta diversity within the group of Big birds), higher levels of SCFA-producing and health-associated bacterial taxa such as Lachnospiraceae, Faecalibacterium, Butyricicoccus and Christensenellales, and lower levels of Akkermansia muciniphila and Escherichia coli as compared to Small birds. Conclusion Cecal microbiome characteristics could be linked to the size of broiler chickens. Differences in alpha diversity, beta diversity and taxa abundances all seem to be directly associated with growth differences observed in an otherwise similar broiler flock.

Evaluation of broiler chickens rearing parameters in relation to intensity of infection with Eimeria protozoa

The study was aimed to assess the rearing parameters in Ross 308 broiler chickens depending on the intensity of infection with Eimeria protozoa. Two flocks were included in the analysis. One was found to be free from coccidiosis (healthy flock HF) and the other was classified as infected flock (IF). The collected data included the age of the chickens, losses (including falls and culls), body weight, weight gains, and daily feed intake. Additionally, the mean feed intake per kg body weight was estimated and the European Production Efficiency Factor (EPEF) was calculated. The study demonstrated that the presence of Eimeria parasites in the rearing environment of broiler chickens had an impact on the rearing performance by increasing the demand for feed and the percentage of falls and culls during the rearing period, in comparison with chickens from the coccidiosis-free flock. Although they consumed higher amounts of feed, the coccidia-infected chickens were characterized by substantially lower weight gain values. The EPEF value on rearing day 42 in the Eimeria-infected broiler flock was by 103.66 lower than that calculated in the healthy flock.

Metagenomic Analysis of the Respiratory Microbiome of a Broiler Flock from Hatching to Processing

Elucidating the complex microbial interactions in biological environments requires the identification and characterization of not only the bacterial component but also the eukaryotic viruses, bacteriophage, and fungi. In a proof of concept experiment, next generation sequencing approaches, accompanied by the development of novel computational and bioinformatics tools, were utilized to examine the evolution of the microbial ecology of the avian trachea during the growth of a healthy commercial broiler flock. The flock was sampled weekly, beginning at placement and concluding at 49 days, the day before processing. Metagenomic sequencing of DNA and RNA was utilized to examine the bacteria, virus, bacteriophage, and fungal components during flock growth. The utility of using a metagenomic approach to study the avian respiratory virome was confirmed by detecting the dysbiosis in the avian respiratory virome of broiler chickens diagnosed with infection with infectious laryngotracheitis virus. This study provides the first comprehensive analysis of the ecology of the avian respiratory microbiome and demonstrates the feasibility for the use of this approach in future investigations of avian respiratory diseases.

Can good broiler flock welfare prevent colonization by Campylobacter?

Using data on rearing and welfare metrics of multiple commercial broiler flocks from the last ten years, we investigate how welfare measures such as hock burn, mortality, weight, and pododermatitis, among others, impact the likelihood of a flock becoming colonized by Campylobacter. Using both logistic regression and Bayesian networks, we show that, while some welfare metrics were weakly related to Campylobacter colonization, evidence could not be found to suggest that these metrics actively exacerbated Campylobacter colonization, rather that they were both symptoms of the same underlying cause. Instead, observed dependency on the management of the flock suggested that yet-undiscovered differences in rearing practise were the principal cause of both poor bird welfare and increased risk of Campylobacter, suggesting that action can be taken to improve both these factors simultaneously.

Using stochastic dynamic modelling to estimate the sensitivity of current and alternative surveillance program of Salmonella in conventional broiler production

Since 2018, the EU commission has declared the Danish broiler industry to be Salmonella free. However, there is continuous Salmonella pressure from the environment, and a number of parent flocks and broiler flocks become infected annually. When a parent flock becomes infected, the infection can be transmitted vertically to the broiler flocks, before the parent flock is detected and destroyed, including the eggs at the hatchery. To address this issue, we developed stochastic dynamic modelling of transmission of Salmonella in parent flocks and combined that with the relation between flock prevalence and test sensitivity for environmental samples in the flock. Results suggested that after 10 and 100 infected hens were seeded, the likelihood of detecting an infected parent flock within the three first weeks after the infection was strongly influenced by the taking of five boot swabs (95% CI 70–100) instead of two (95% CI 40–100) or the supplementing of the two boot swabs by a dust sample (95% CI 43–100). Results suggest that the likelihood of detecting the broiler flock as infected in the program was estimated to at least 99% in broiler flock even if only one chicken was initially infected. These findings are of relevance for managing parent flocks and eggs at the hatchery in case of Salmonella infection in parent flocks in the Danish poultry.

Risk Assessment of The Use of Colistin Sulfate In Broiler Due To Escherichia coli Resistance In Broiler Flocks

The risk assessment of antimicrobial resistance is very important to determine the risk of decreasing antimicrobial efficacy can be used as a basis for policymakers in allowing or prohibiting the use of an antimicrobial. This study aims to assess the risk of using colistin against E. coli resistance in the broiler flock. Risk assessment is carried out qualitatively using primary data, interviews, and secondary data. To obtain primary data various studies were carried out including monitoring the prevalence of colistin-resistant E. coli and mcr-1 also mcr-2 genes in broiler flocks, mcr-1 gene transfer from E. coli to Salmonella Enteritidis, mcr-1 gene sequencing, mutant selection windows of colistin against E. coli, and also multiresistant of E. coli colistin-resistant. Assessment of the risk of E. coli colistin-resistant in the broiler flocks through direct contact with live broiler flock environment with the resulting assessment is a medium risk with low uncertainty. Since colistin sulfate is very critically important for humans, the reduced use of colistin sulfate in animal production is necessary to reduce the risk of resistance. Reducing the use of colistin sulfate requires the collaboration of various sectors such as the government, veterinary drugs industries, farmers, and consumers.