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Measuring forage quality of corn silage and understanding the impacts on rumen fermentation in lactating dairy cattle
Last year the USDA estimated that 113 million tons of corn silage was produced. This was up 4 percent from the previous year and was also the highest production in the United States since 1982. Given that corn silage is commonly included in diets for dairy cattle at 30-50% of the DM, this crop represents an important feedstuff to the dairy industry. Additionally given that the chemical composition and nutrient availability of this feed may vary, quality of this feedstuff is central to dairy production and profitability. The term forage quality is often defined by the extent to which the forage elicits a productive response. Fundamentally speaking the nature of this response is dependent upon the availability of forage nutrients to rumen microorganism. Plant factors which affect this availability include maturity, hybrid, and growing conditions. Additionally, harvesting and ensiling practices may also affect nutrient availability and these include the method of chopping, length of cut, extent of kernel processing and time of ensiling. Lastly, a number of animal factors may also influence nutrient availability including level of intake, nutrient demands, behavioral patterns, and animal health. Attributes of good quality forage usually include a high intake potential, high nutrient concentration and high digestibility or nutrient availability. Forage quality is commonly assessed through chemical and physical analysis, near-infrared spectroscopy, as well as using a number of in vivo and in vitro methods. The purpose of this presentation is to review how forage quality affects rumen fermentation, microbial digestion, and how factors that affect forage quality may be manipulated to ultimately contribute to greater milk production.
Keywords:
Corn silage, forage quality, rumen fermentation dairy production