ISSUE FOCUS 38 FEED & ADDITIVE MAGAZINE July 2022 In conditions of HS, cows show increased respiration rates and higher losses of CO2 through the lungs and higher bicarbonate loss in the urine. As a result, less bicarbonate is available to help buffer acids in the rumen and pH is reduced, leading to SARA. Systematic measurement of ruminal pH for 24-h period indicated that daily live yeast supplementation contributed to a higher pH versus non-supplemented animals (Krizova et al., 2011) (Figure 1). In SARA challenged cows Alzahal et al. (2014) (Figure 2) found a positive influence of live yeast on rumen pH and in particular the time spent below pH 5.6. Levels of fibrolytic fungi and the main fibre degrading bacteria were increased, indicating better fibre digestion and also the number of lactate producing microorganisms was reduced. CONCLUSIONS/IMPLICATIONS There is no single approach to alleviate heat stress for dairy cows. It is necessary to introduce effective management and nutritional strategies to balance the homeostasis of the animal to help support feed efficiency, productivity and reproduction. Supplementation with live yeast (Saccharomyces cerevisiae) can be a successful part of those strategies to help alleviate the negatives effects of heat stress. For further information or references please contact emea@abvista.com About Diego Parra Diego Parra, Technical Manager EMEA at AB Vista, is responsible for some of the Mediterranean countries in Europe such as Spain, Portugal, Italy, Turkey and Switzerland. Diego was born and raised in Spain where he studied veterinary science at Complutense University in Madrid. Besides, he holds a master of science and a master of business administration. Also, he has already started a PhD in agricultural engineering with a focus on animal nutrition. He has 6 years of practical experience in the feed and poultry field, mainly, managing feed mills and farms, before joining AB Vista 3 years ago. About Dr. Dimcho Djouvinov Dr. Dimcho Djouvinov, PhD, Technical Manager CEE, AB Vista, provides technical service and nutritional solutions to customers in Bulgaria, Czech Republic, Romania and Ukraine. Dr. Djouvinov has more than 20 years’ experience in animal nutrition at university level and feed industry and brings scientific knowledge into practice. Figure 2. The effect of live yeast (Saccharomyces cerevisiae) supplementation on time ruminal pH spent below 5.6 (Alzahal et al., 2014). Figure 1. Effect of live yeast on the diurnal pattern of ruminal pH (feeding time is marked with arrows)
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