Quality-related characteristics of forages as influenced by plant environment and agronomic factors

Abstract

The most important factor influencing forage quality is herbage maturity. For example, a 1-week delay in harvesting of alfalfa ( Medicago sativa L.) will decrease digestibility and crude protein concentration by about 20 g kg −1 and increase cell-wall concentration by approximately 30 g kg −1. Forage quality also is influenced by the environment in which forages are grown and by soil fertility and these cause year-to-year, seasonal, and geographical variation in forage quality even when herbage is harvested at the same stage of maturity. High temperatures normally increase rate of plant development and reduce leaf/stem ratios and digestibility. Moderate water stress usually delays plant maturation and causes forage quality to be maintained at higher levels. Excessive amounts of forage protein nitrogen may be excreted as urea in animal urine, which can limit animal production. Protein in forages with high ruminal escape is used more efficiently. The amount of escape protein is higher for red clover ( Trifolium pratense L.) than for alfalfa or white clover ( Trifolium repens L.). As animal production continues to improve through genetic gain, the need for high quality forages will become more important. There is good potential for producing new cultivars with improved forage quality and several are now on the market. Additional cultivars with improved forage quality will be available in the near future.