Effects of Harvest Intervals on the Yield and Composition of 10 Forage Grasses

Abstract

The effect of three harvest intervals (30, 45 and 60 days) on the yield, crude protein (CP), digestible protein (DP), and mineral (calcium, Ca; phosphorus, P; potassium, K; and magnesium, Mg) composition of 10 forage grasses was determined during a 1-year period at the Isabela Substation. The species studied included three Brachiarias, five Digitarias and two Cynodons. As the 30-day harvest interval, the dry matter yield (DMY) ranged from 25,859 to 19,041 pounds per acre per year. The highest DMY was obtained by Transvala digitgrass (Digitaria decumbens, PRPI. 6439) Stargrass (Cynodon nlemfuensis PRPI. 2341) had the highest CP and DP contents. The highest DMY at the 45-day interval was obtained by Transvala digitgrass, being significantly different (P < .05) from other grasses. The DMY ranged from 29,532 to 20,962 pounds per acre per year. Digitaria eriantha had the highest CP and DP contents. Stargrass had the highest DMY and CP at the 60-day harvest interval. The DMY ranged from 37,504 to 30,269 pounds per acre per year. Mean Ca and Mg contents in the grasses increased at the 45-day interval, with no Ca increase but a Mg decrease at 60 days. Mean P and K contents decreased as the harvest intervals increased. The yielding ability of the grasses was encouraging, especially in the Transvala digitgrass and Stargrass species. The CP and DP contents tended to vary as plants matured, suggesting that studies of mineral absorption and/or utilization of forage grasses by niminants should be undertaken.