Influence of Plant Stage at Initial Harvest and Height of Regrowth at Cutting on Forage Yield and Quality of Timothy and Orchardgrass1

Abstract The need to obtain the best compromise between yield and quality has been recognized for years. The object of this study was to evaluate the influence of initial harvest at various growth stages and height of regrowth (all cuttings after initial harvest) at cutting on forage yield and quality of ‘Climax’ timothy ( Phleum pratense L.) and ‘Pennlate’ orchardgrass ( Dactylis glomerata L.). First growth of these grasses was harvested at each of the following stages: (a) transition (changing of apical meristem from vegetative to reproductive growth), (b) boot, and (c) anthesis. Following each initial harvest stage, regrowth was removed throughout the growing season at each of the following plant heights: 10 to 15 cm, 20 to 25 cm, 30 to 36 cm, 41 to 46 cm, and 51 to 56 cm. This field investigation was conducted during 1970 and 1971 on a fine, loamy, mixed, mesic Typic Hapludults (Murrill series) at the Agronomy Research Farm near Rock Springs, Penn. Delaying the first harvest of timothy and orchardgrass from the transition to anthesis stage resulted in increased yield and estimated total digestible nutrients (TDN). However, total seasonal regrowth, total TDN of regrowth, total digestible protein, and total digestible protein of regrowth decreased significantly (P≤0.05). Allowing plants of both species to attain heights of 20 to 36 cm, with few exceptions, produced highest total and regrowth forage yield, TDN, and digestible protein. However, frequent removal of regrowth, at a plant height of 10 to 15 cm, resulted in significantly (P≤0.05) lower yields and encouraged weed encroachment. These data indicate first harvest forage removal at the transition stage, followed by regrowth removal each time plants attain a height of 20 to 36 cm results in highest production of quality forage as measured by total seasonal regrowth, total TDN of regrowth and total digestible protein.