The Alltech Feeding Times Issue 36 - Winter 2021 Winter 2021 - Page 9

Fig 1 : % Change in useful energy correlated with Yea-Sacc ®
To quantify the efficacy of Yea-Sacc for improving rumen fermentation and nutrient utilization for specific dairy TMRs , allowing for greater precision when feeding Yea- Sacc , Alltech created the Alltech IFM™ : Yea-Sacc ® Value Test ( YSVT ® ).
The response of dairy TMRs to Yea-Sacc supplementation may vary depending on the feedstuffs . Formulation models are limited in predicting the effects of nonnutritive feed additives on rumen fermentation , which limits the precision of ration formulation and the prediction of the efficacy of a given additive . A quick labbased test that evaluates the potential of Yea-Sacc in a particular situation can help improve the nutritive value of a given TMR .
Building on Alltech IFM , an in vitro rumen fermentation model used to characterize feed digestion kinetics , YSVT is a unique approach to rumen fermentation analysis . Standard in vitro rumen simulation techniques are usually conducted over a shorter period spanning 48 to 72 hours of fermentation . As a result , these techniques do not allow for an accurate evaluation of the efficacy of yeast supplements , as the effects of yeast on rumen populations are not readily evident until supplements like Yea-Sacc have been included in the diet for at least 4 to 7 days .
As the animal adapts to the presence of Yea-Sacc in its diet , the rumen microbial population changes to comprise higher concentrations of fiber-digesting and lactate-utilizing bacteria . YSVT utilizes rumen fluid both from animals that have been adapted to Yea-Sacc and their counterparts that are fed the same basal ration without Yea-Sacc . This allows for the adequate adaptation of the rumen microbial populations to Yea- Sacc without the need for long-term incubation in the lab .
The YSVT test measures key fermentation indicators , including :
• Digestibility
• Lactic acid concentration
• Useful energy ( i . e ., energy produced from the fermentation of carbohydrates )
• Rumen energy efficiency ( i . e ., useful energy per pound of feed digested )
To date , more than 200 dairy TMRs have been analyzed using YSVT . More than 93 % of the samples showed a positive response to Yea-Sacc supplementation in terms of useful energy and rumen energy efficiency , with an average response of + 13 %.
In approximately 50 % of all samples , the increase in the useful energy released was not correlated with improvements in digestibility . This indicates that Yea- Sacc increases the efficiency by which feed nutrients are converted into useful energy for the animal , most likely through a more efficient and healthier microbiome . The lactic acid response was more variable , with more than 60 % of the samples showing a decreased concentration , indicating a reduced risk for a lower rumen pH and acidosis . In conclusion , the YSVT helps nutritionists and producers understand the value of yeast in improving rumen fermentation . As a result , feed additive supplementation strategies can be tailored to maximize the energy produced from rumen fermentation and improve digestive efficiency in dairy cows . Future developments of this tool will focus on better understanding the interaction of ingredients , the nutrient composition of the TMR and the response to Yea-Sacc — and on developing predictive models to quantify the expected animal performance based on the outcome of a given fermentation profile .