QUALITY-RELATED CHARACTERISTICS OF FORAGES AS INFLUENCED BY PLANT ENVIRONMENT AND AGRONOMIC FACTORS

The most important factor influencing forage quality is herbage maturi ty. For example, a 1-week delay in harvesting of alfalfa (Medicago sat iva L.) will decrease digestibility and crude protein concentration by about 20 g kg(-1) and increase cell-wall concentration by approximate ly 30 g kg(-1). Forage quality also is influenced by the environment i n which forages are grown and by soil fertility and these cause year-t o-year, seasonal, and geographical variation in forage quality even wh en herbage is harvested at the same stage of maturity. High temperatur es normally increase rate of plant development and reduce leaf/stem ra tios and digestibility. Moderate water stress usually delays plant mat uration and causes forage quality to be maintained at higher levels. E xcessive amounts of forage protein nitrogen may be excreted as urea in animal urine, which can limit animal production. Protein in forages w ith high ruminal escape is used more efficiently. The amount of escape protein is higher for red clover (Trifolium pratense L,) than for alf alfa or white clover (Trifolium repens L.). As animal production conti nues to improve through genetic gain, the need for high quality forage s will become more important. There is good potential for producing ne w cultivars with improved forage quality and several are now on the ma rket. Additional cultivars with improved forage quality will be availa ble in the near future.