• Bacterial Chondronecrosis and Osteomyelitis (BCO) is a major cause of lameness in broilers globally.
  • Lameness is associated with pain, decreased mobility and reduced feed and water intake.
  • Broilers fed Orego-Stim had reduced incidence of lameness with known agnetis infection.


  • In fast-growing broilers, micro-trauma occurs in the long bones, rupturing blood vessels and allowing any bacteria present in the blood to enter the bone. This can lead to BCO (also known as femoral head necrosis). BCO is most prevalent after 35 days of age.
  • Staphylococcus agnetis is one of the bacteria associated with clinical BCO.
  • Orego-Stim is a high quality eubiotic containing 100% natural oregano essential oil.

An independent trial was conducted by the University of Arkansas (USA) using 560 male Cobb 500 chicks from day-old to 56 days old. The aim of the trial was to determine whether Orego-Stim can reduce lameness through improved gut health and antibacterial action. Birds were randomly allocated to either Control diet, or Orego-Stim (500g/t) supplementation, with 4 replicates per treatment. Birds were housed in pens with wire flooring to aid a pre-disposition to BCO. On day 20 and 21, birds were exposed to S. agnetis (105 cfu/ml) in drinking water. Lameness was recorded daily from day 22 to 56. Body weights of 20 healthy birds per treatment were recorded on day 56. Healthy birds were identified by walking behaviour and absence of any behavioural signs of lameness.



Cumulative Lameness Following Challenge Day 22-56

Figure 1. Cumulative lameness following challenge (day 22-56). a,b Superscripts which differ between treatment indicate significant difference at p<0.0001.

Average Final Body Weight Day56
Figure 2. Average final body weight (day 56). a,b Superscripts which differ between treatment indicate significant difference at p<0.05.


  • At day 56, the cumulative lameness was 20% lower in birds fed Orego-Stim versus birds from the control group (Figure 1).
  • Relative risk analysis suggests that birds without Orego-Stim are 1.35 times more likely to be lame.
  • In healthy birds, the body weights of Orego-Stim supplemented birds were heavier than those from the control group (Figure 2).