New steps for a better leg health of broiler chickens

Broiler chickens’ leg health challenges

Broiler chickens have an astonishing ability to produce high-quality meat with an excellent feed efficiency. Over the past few decades, the ever-increasing growth rate of the high-performance broiler breeds has challenged their leg health. Examples of the emerging problems include bacterial chondronecrosis with osteomyelitis, tibial dyschondroplasia, angular bone deformities, and crooked toes. Lameness can be seen in all age groups, but it is especially prevalent in heavy-weight birds close to the slaughter age. Leg problems are among the most significant reasons for culling and mortality, and very costly for the broiler industry. 

Bacterial translocation from the intestinal lumen to internal organs and skeleton happens during the first few weeks of the broiler chicken’s life. This process has been suspected to affect the development of leg problems, but detailed information has been missing.

Hankkija FFI’s research collaboration: Bacterial translocation’s role in broiler leg health

Recently, Hankkija FFI took part in a research program led by professors Filip Van Immerseel and Richard Ducatelle at the Veterinary Faculty of the University of Ghent, Belgium, focusing on bacterial translocation and broiler leg health. The principal investigator of the study was doctor Evy Goossens.

In December 2023, the study entitled “Enterobacteriaceae and Enterococcaceae are the dominant bacterial families translocating to femur heads in broiler chicks” was published in the valued peer-reviewed journal Avian Pathology, with the young scientist Valerie Adriaensen as the first author.

Experimental Setup:

For the study, one hundred and twelve male Ross 302 hatchlings was divided into eight pens, 14 chicks per pen. The birds were sampled for blood, liver tissue and femoral head tissue at days 2, 3, 4, 5, 6, 7, 8, 10, 12, 14, 16, 19, and 22.

Study analyzed bacterial presence in femoral heads, blood, and liver tissues of broiler chicks at different ages

Bacterial counts were analysed from blood and liver on days 5, 8, 12, 16 and 22, and from the femur heads on all of the days. For the determination of bacterial groups, 16S rDNA sequencing was used.

Results and Key findings

Age-related presence of bacteria in broiler chick tissues

According to the hypothesis, the femoral heads showed an age-related presence of bacteria, with highest numbers in two-days old chicks. No bacteria were isolated from femoral heads of broilers older than 14 days. Live bacteria were detected only in femoral heads with normal histological structure. Cartilage retention and signs of separation between the articular cartilage and the growth cartilage in one or both legs were observed in all chicks sampled at days 19 and 22, but no bacteria were detected at these lesions.

Live bacteria were evident in normal femoral heads but not in damaged cartilage despite their presence in the bloodstream

In the blood and liver tissue, live bacteria were observed at all time points, with highest numbers at or before day 12. Thus, the lack of bacteria at the damaged cartilage in 19- and 22-days old chicks is even more surprising, as bacteria were present in the bloodstream at that time.  

Distinct bacterial populations in femoral heads and systemic tissues

Different bacteria occupied femoral heads than blood and liver. The dominant groups in blood and liver were Enterobacteriaceae, Enterococcaceae, and Staphylococcaceae, while bacteria in the femoral heads mainly belonged to Escherichia/Shigella and Enterococcus spp. It is apparent that some yet unknown mechanisms direct specific bacterial groups from the bloodstream to cartilage in the young broiler chicken.

Study identified different dominant bacterial groups in the femoral heads compared to blood and liver, suggesting specific mechanisms guiding bacteria from the bloodstream to the cartilage

Conclusions and Future research avenues

According to the conclusions of the paper: “This study shows that young clinically healthy broilers have a higher prevalence of bacteria in the femoral head compared to older broilers and that presence of bacteria in blood and liver is common during ageing of broilers.”

Young healthy broilers harbor more bacteria in femoral heads than older broilers

As usual, this study both gave answers and opened new research questions. It would be intriguing to further study the role of bacterial translocation in leg problems, knowing that bacteria are no longer present when the cartilage damage becomes visible. It would also be of interest to study if bacterial translocation can be affected through diet, considering that the gut permeability is highest right after hatching, and chicks eat very little at the first couple of days.

Hankkija FFI’s commitment to research and development

Hankkija FFI remains dedicated to staying updated on poultry leg health research and actively engaging in selected research projects. This proactive involvement aims to swiftly integrate new information into product development initiatives.

Reference:

Valerie Adriaensen, Filip Van Immerseel, Richard Ducatelle, Hannele Kettunen, Juhani Vuorenmaa & Evy Goossens (14 Dec 2023): Enterobacteriaceae and Enterococcaceae are the dominant bacterial families translocating to femur heads in broiler chicks, Avian Pathology, DOI: 10.1080/03079457.2023.2288872