Trial Summary - Enhanced Growth of Calves Fed Orego-Stim®


  • Orego-Stim® Liquid, when provided at a dose of 2 ml/calf/day, improved growth performance of dairy calves by 2 kg at day 56 (weaning) and 2.9 kg by 70 days of age
  • This could result in an additional 21 - 31 kg of milk in the first lactation, giving a ROI of 4.5 : 1.


  • Orego-Stim® is a high quality phytogenic eubiotic containing 100% natural and unique oregano essential oil.
  • Heavier calves at weaning, and those with a higher average daily gain (ADG) from birth to weaning, have demonstrated a higher milk production during their first lactations (Chester-Jones et al., 2017).
  • Greater ADG and bodyweight are associated with better fertility in heifers (Brickell et al., 2009).

Trial Design

An independent trial was carried out at the AgriFood and Biosciences Institute (AFBI) in Northern Ireland, to assess the efficacy of Orego-Stim® Liquid on calf growth and health.

70 Holstein-Friesian dairy calves were assigned to one of two treatments from birth until 70 days of age. Treatments were:

  •  Control: no additives; 
  • Orego-Stim®: 2 ml/calf/day of Orego-Stim® Liquid. 

Groups were balanced for gender and birth weight. All calves were provided sufficient colostrum to ensure adequate transfer of immunity (IgG) from dam to calf.

From 5 days of age, calves were housed in straw pens and offered reconstituted milk replacer at 150 g/litre and fed up to 6 litres per day via automatic milk feeders until day 35. Allocation was then stepped down until weaning at 56 days of age. Calf starter feed was available ad libitum throughout, with automatic weigh scales at these feeders, allowing multiple daily weights for each calf to be measured. Any incidence of scour or pneumonia was recorded daily.



  • Calves offered Orego-Stim® Liquid were 2 kg heavier at weaning (56 days of age; p<0.05) and 2.9 kg heavier at 70 days of age (p=0.05) (Fig 1).
  • Calves offered Orego-Stim® Liquid had a 6.8% greater ADG than control calves (p=0.06) (Fig 2).  
  • There was no scour in any calf and 4 calves exhibiting signs of pneumonia (in the Control group only). 
  • Orego-Stim® Liquid is an effective phytogenic eubiotic to help support growth rates in dairy calves both pre and post-weaning.
  • This may lead to increased milk yields in the first lactation, offering a potential ROI of 4.5:1.

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