Effect of time of supplementary feeding on intake / apParent digestibility and rumen fermentation of grass hay by sheep

Eft'ects ot ' time ot ' supplementation on t'orage intake, nutrient apparent digestibility and rumen fermentation were studied with 72 mature castrated male sheep (wethers) offered grass luy t'rom 76.30 h to 09.30 h nnd supplemented with a cereal-based concentrate giuen at either 09.30 or 16.00 h. Voltnúary intake ot ' hay organic matter (OM) was decrensed by feeding the concentrate (P < 0.01). Offering concentrate at 09.30 h at'ter hay zons aaaíIable, increased intake ot ' hay and total OM compared zuith offering it at 76.00 h before hay was artailable (P < 0'05). Daily pattern of hay intake zuas not changed zuhen concentrate was offered at 09.30h compared with t'eeding hay nlone, but concentrste giuen at 16.00 h resulted in a lower hay intake between 16.30 and 78.00 h. Sheep ot't'ered concentrate at 0g.30 h hntl higher rumen aÍttlonia leoels than those offered concentrate at 76.00 h, but there were n0 differences in the apparent digestibility of the ntttrients, rumen pH and molar proportions of the main aolatile t'ntty acids ' There were also no dfferences between grlups in the blood plasmn concentratiotts of 3-hydroxybutyrnte (3OHB), non-esterified fatty acids NEFA) and glucose, It is concludetl that feeding stryplement at'ter rather than bet'ore a petiod ot ' intake ot ' t'orage or a bout of grnzing may offer a means ot ' minin'rizing reduction of t'orage intake as a consequence of feeding concentrate