SUMMARY The transition period pre- and post-calving is a stressful time for the dairy cow. Natural plant extracts may help maintain antioxidant status and support immune function. In this study (Vizzotto et al., 2021) cows fed Orego-Stim had lower somatic cell counts and reduced levels of some oxidative stress biomarkers, leading to greater milk production.
BACKGROUND Transition cows are more susceptible to impaired immunity and increased disease prevalence, enhancing the chance of early culling or lower productivity. A high somatic cell count (SCC) in milk is an indicator of infection and can also alter mineral flow in the udder, causing a higher pH and a lower acidity. This can reduce levels of ionic calcium, which is vital for the calf, and reduce milk production. Antioxidants can help to reduce incidence of oxidative stress, supporting performance and immune function. This study was undertaken to assess the effect of plant extracts on the antioxidant status of transition cows and milk quality. Orego-Stim Powder is a high quality eubiotic composed of 100% natural oregano oil. TRIAL DESIGN A trial was carried out at Federal University of Rio Grande do Sul, Brazil, in the hot season, from October 2015 to January 2016. 24 Jersey cows (approx. 400kg bodyweight, 2.7 lactations) were split into one of three treatments. Control (standard diet with no additives), OS (10g per day of Orego-Stim Powder) or GT (5g per day Green Tea extract), from 21 days pre-calving to 21 days post-calving. Bodyweight and body condition were measured weekly. Blood samples were taken on days -28, 0, 2 and 28 relative to calving date in order to determine levels of the oxidative stress biomarker dichlorofluorescein diacetate (DCF) and the levels of antioxidant Glutathione (GSH) present. From days 5-21 of lactation, milk was analysed daily for markers of quality, such as SCC, as well as measuring total milk yield.
Feed intake, bodyweight and milk production data are presented in Trial Summary 22252201. Cows offered Orego-Stim had a lower milk SCC (Figure 1), as well as higher ionic calcium levels and more acidic milk with a lower pH. GSH levels were higher in cows receiving plant extracts, indicating increased antioxidant activity (Figure 2). Pre- and post-calving, DCF in red blood cells was lower in cows fed Orego-Stim, indicating a reduced level of oxidative stress and therefore an improved antioxidant status (Figure 3).