For example, a lighter colour product is an indicator of higher


digestibility (Figure 1). Whilst rapid drying can help reduce production costs, it can also ‘burn’ the protein in the presence of residual sugars therefore reducing digestibility, which can be observed with a darker colour.


Figure 2: Quality overview of Optimin SeY


Figure 1: Physical appearance of Optimin SeY (left) versus a competitor selenium yeast (right)


A more granular product also indicates the presence of more


live yeast cells which have been shown to have minimal absorption. Selenium yeast should be inactivated with autolysis of the yeast proteins, helping to make them more accessible leading to improved selenium absorption. A high quality selenium yeast product should therefore have the appearance of a fine spray-dried powder. Additionally, to help identify a good selenium yeast, a Certificate


of Analysis should confirm that the total selenium and SeMet contents conform to the guaranteed specification. Trouw Nutrition’s Optimin SeY is a premium high quality selenium-


enriched yeast containing 100% organic selenium comprised of an optimal combination of natural organic selenium forms including SeMet as the main bioavailable form plus SeCys and other organic selenocompounds. The product also offers guaranteed and consistent quality, with Trouw Nutrition being the only supplier of selenium- enriched yeast that runs analysis on both total selenium and SeMet on a routine basis for each batch released and guarantees these values on a certificate of analysis. Furthermore, analysis of multiple batches of Optimin SeY has


shown an average selenium content of 2201ppm with 66% of this selenium as SeMet, both exceeding the minimum EU specification requirements for a selenium yeast (Figure 2). The stability of different organic selenium sources can also vary


depending on their origin and matrix, with differences in stability having been shown between selenium yeast sources and synthetic organic selenium sources. Furthermore, the presence of trace minerals in a premix can affect the stability of other premix components. Both the stability of selenium as well as SeMet present in Optimin SeY have been shown for three years for Optimin SeY itself in pure form, one year in premix and six months in complete feed, which is critical to ensure maximum benefi ts are achieved both in terms of cost effectiveness and animal performance.


PAGE 46 MAY/JUNE 2019 FEED COMPOUNDER


Selenium-enriched yeasts in ruminant diets – a cost effective supplement Due to its function within the immune system and antioxidant status, the selenium content of a diet is particularly important during times of stress such as the transition period in dairy herds, pre-calving in suckler cows and pre-lambing in sheep. The possible drawback of selenium yeast, however, is that it is


more expensive than inorganic selenium sources, leading to an increase in mineral supplementation costs and finished feed prices. With many ruminant farming systems facing a financial squeeze, it is important to be able to demonstrate a return on investment from the addition of organic selenium. The marginal cost of adding organic selenium to the legal limit is


actually very small. For example over a six week transition period, the cost of supplementing Optimin SeY would be less than £1 per head more than supplementing with just inorganic selenium. When this is compared to the known problems and cost


implications of diseases associated with selenium deficiency, the cost soon becomes less of an issue. For example, industry figures estimate that each retained cleansing case costs on average £290, while each case of metritis costs £189. Research also shows that 60% of clinical mastitis cases during


lactation can be traced back to bacterial infections that occurred during the dry period (Figure 3), and the risk of picking up new infections is 10 times greater during the dry period than during the lactation.


Figure 3: The origin of infection (dry period or lactation) in clinical mastitis cases (source: FAS)


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