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The effect of Aspergillus oryzae on ryegrass degradation rate and production parameters of Jersey cows grazing ryegrass pasture 

    Input costs of milk production systems continues to rise, resulting in pressure on the profitability of these systems. In many countries, the sub-therapeutic use of antibiotics or ionophores, are forbidden and there are certain health concerns associated with the use of these products. This created a need for non-antibiotic products that can be used in cattle to increase feed efficiency.

    A variety of feed additives are available to nutritionist and farmers to use as a supplement in dairy cattle diets. The majority of dairy production systems in South Africa are pasture-based. In the Southern Cape, Kikuyu (Pennisetum clandestinum) and ryegrass (Lolium multiflorum) are commonly available for use as pasture for dairy cattle. It is well known that energy intake is the first limiting factor for milk production in dairy cattle on pasture. Dairy cattle typically receive 6 kg/day of a maize-based concentrate and will consume approximately 8 - 10 kg DM/day of pasture.

    The neutral detergent fibre (NDF) content and the fiber degradability (NDFd) are two factors that determine pasture intake. The physical fill factor and the rate of digestion limits the dry matter intake of cattle. The NDF content of pasture relates to rumen fill, and it serves as a measure of energy availability to the animal. A low NDF value is generally indicative of a higher energy availability. Poor quality pasture usually has a higher NDF content, which results in lower degradability and thus lower energy availability to the animal. Fungi, such as Aspergillus oryzae, can break down lignin-hemicellulose bonds and thus improve fibre degradation. Increased degradation of the fibre may result in an increase in intake and energy supply in cattle. Further research is needed to determine whether the supplementation of Aspergillus oryzae fermentation product will affect the rumen environment and fibre degradation and how this will alter milk production and composition of dairy cattle grazing ryegrass/kikuyu pasture in spring.

    The project to be carried out at the Outeniqua Research farm of the Western Cape Department of Agriculture, aims to investigate if Aspergillus oryzae fermentation product supplementation to Jersey cows grazing ryegrass in spring affects milk production, milk composition, rumen environment, fibre degradation and dry matter intake. 

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