NUTRITION ▶▶▶


How to mitigate feed safety risks in ruminant diets


BY DANIELA VEGA SAMPEDRO, TECHNICAL CONSULTANT FEED ADDITIVES, AND EVELIEN VAN DONSELAAR, GLOBAL PROGRAMME MANAGER FEED SAFETY, TROUW NUTRITION


F


ood safety will always be the common denominator and universal driver when it comes to assuring sus- tainable food production across the supply chain. Ru- minant feed production is undergoing a shift that ad-


dresses the challenges of ruminants’ diverse diets and includes several preventive measures to avoid possible hazards and optimise food safety. Ruminant diets are made up of a variety of feedstuffs and by-products, as well as dried or ensiled forages (usually 50– 75% of the diet). Microbiology presents safety concerns as bacteria, yeasts and moulds of different origins can occur nat- urally in feed ingredients. As on-farm storage of feedstuffs presents additional concerns, applying phytosanitary practic- es helps minimise the risk of micro-organisms and mycotox- ins contaminating feed. Below, we look at primary safety con- cerns that can arise when feed is contaminated with micro-organisms during processing and storage and how an integrated approach can help farmers mitigate the risk.


Yeast Yeast problems can occur in co-products and silages used for ruminant feeding in total mixed ration (TMR). Ensilaging is done to preserve crops with high moisture content. The limit- ed air contact should stimulate lactic acid bacteria develop- ment, creating a natural preservation and preventing yeast de- velopment in the silage. However, many factors such as weather conditions, quality of raw materials and microbial pressure can disturb this process, impairing lactic acid produc- tion and allowing yeast fermentation. Neither aerobic nor an- aerobic yeast (facultative anaerobe) are favourable in silage, since they consume valuable nutrients. When silage is under


anaerobic conditions, fermentation of yeast from sugars to CO2 occurs, producing ethanol. The effects of ethanol production not only impair lactic acid fermentation but negatively affect milk flavour. When silage is under aerobic conditions, the activ- ity of different yeast strains will convert the lactic acid bacteria into CO2


and H2 O, reducing dry matter levels and being ex-


pressed through raised temperature of the silage. Further deg- radation will lead to increased pH in silage, which later will enhance the propagation of other undesirable organisms.


▶DAIRY GLOBAL | Volume 7, No. 3, 2020 45


Ruminants are highly efficient animals and can digest fibrous feed and by-products unusable for human food. A Future Market Insights report projects the upcycled food industry will grow at a 5% compounded rate. While ruminants are well designed to leverage the feed-to-food upcycling trend, production efficiency can never come at the expense of safety.


Yeast fermentation has a negative effect on palatability and odour of feed, which may result in low or irregular feed in- take, lower feeding efficiency, lower milk yield and possibly also more indirectly related health problems such as lameness and mastitis.


Bacteria Animal feed may become contaminated with harmful bacte- ria, such as E. coli, Salmonella or Listeria. Listeria monocy- togenes, for example, can compromise animal performance. These bacteria are more likely to survive when air leaks into the silo. Currently, there is no practical way to provide a lis- teria-free environment. The micro-organisms can cause lister- iosis (also known as silage sickness) in animals, which can lead to septicaemia and may affect the central nervous sys- tem, having a direct negative impact on animal performance. Apart from the impact on animal health and performance, E. coli and Salmonella are food-borne zoonoses that can make their way into food consumed by humans and may harm


Increased tem- perature is a clear indicator that yeast fer- mentation is af- fecting the nu- tritional value of the silage


(36.9°C with an environmental temperature of 18°C at the time of measuring).


PHOTO: TROUW NUTRITION


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