Influence of Date and Method of Harvesting Hay on Lamb Performance

Animal response was measured in the evaluation of hays over a 3-year period using 516 fattening lambs of native and western origin. Mixed grass hays were cut the first of June and about a month later and were field-cured or barn-dried. Paired and comparison type feeding trials and conventional type digestion trials were utilized. Further, an attempt was made to equalize the protein and/or energy between the early- and late-cut hays by adding appropriate concentrate feeds to the late-cut hay ration. The measurement criteria were total weight gain, live weight grade, feed consumption, and feed efficiency. Variations appeared between years in the differences of TDN content of forages with approximately the same time intervals in harvest dates. The TDN values for early-cut barn-cured hay varied from 66 in 1958 to 57 in 1959 to 61 in 1960 while late-cut barn-cured hay was fairly constant at 53 or 54. Early-cut hay showed significant increases in dry matter, crude fiber and protein digestibility over late-cut hay. Hay harvested early was significantly more favorable than late-cut hay in influencing total gain, live weight grade, feed efficiency and hay consumption in 1958. Live weight grade only was influenced by date of cutting in 1959 while both live weight gain and grade were increased by early-cut hay in 1960. In 1958, heat drying of hay significantly increased live weight grades. During the same trial, increasing the percent protein of the concentrate (by substituting soybean meal for 25% of the corn) failed to influence the performance criteria measured. Lambs receiving late-cut hay in 1959 and 1960 supplemented with either energy or protein and energy grew as well and graded as high as lambs receiving the early-cut hay treatments. Therefore, it would appear that comparable animal performance could be obtained with lower quality hays, in the ranges herein tested, when adequately supplemented.