Effect of grass species and time of cutting on in vivo digestibility in horses and sheep

Abstract

Two digestibility trials evaluating six different silages fed simultaneously to mares and rams were conducted to compare the digestibility by the two animal species. Timothy/ meadow fescue (TMF) and tall fescue (TF) silages made at three different cutting times in round-bales were fed according to an unbalanced 6 x 4 Latin square design with 3-week experimental periods. A 5-day faeces collection period was used for mares and a 7-day collection period for rams. During the collection periods the animals were fed at the maintenance level (60 and 41 g DM/kgW0.75/day for mares and rams, respectively). The mares and rams preferred TMF silage to TF silage. As growth stage proceeded, the digestibility decreased in both grass species. The digestibility of the TMF silage was markedly better than that of the TF silage cut at the same time. The digestibility values obtained by rams were higher than those obtained by mares. The organic matter digestibility (OMD) of TMF silages at the first, second and third cutting time was 67.3, 56.7 and 51.7%, respectively, in mares and 75.7, 68.0 and 63.4%, respectively, in rams. The respective OMD of TF silages in mares was 60.9, 52.7 and 45.7% and in rams 74.0, 66.9 and 59.2%.