EFFECT OF TIME OF SUPPLEMENTARY FEEDING ON INTAKE, APPARENT DIGESTIBILITY AND RUMEN FERMENTATION OF GRASS HAY BY SHEEP

Effects of time of supplementation on forage intake, nutrient apparent digestibility and rumen fermentation were studied with 12 mature cast rated male sheep (wethers) offered grass hay from 16.30 h to 09.30 h a nd supplemented with a cereal-based concentrate given at either 09.30 or 16.00 h. Voluntary intake of hay organic matter (OM) was decreased by feeding the concentrate (P < 0.01). Offering concentrate at 09.30 h after hay was available, increased intake of hay and total OM compare d with offering it at 16.00 h before hay was available (P < 0.05). Dai ly pattern of hay intake was not changed when concentrate was offered at 09.30 h compared with feeding hay alone, but concentrate given at 1 6.00 h resulted in a lower hay intake between 16.30 and 18.00 h. Sheep offered concentrate at 09.30 h had higher rumen ammonia levels than t hose offered concentrate at 16.00 h, but there were no differences in the apparent digestibility of the nutrients, rumen pH and molar propor tions of the main volatile fatty acids. There were also no differences between groups in the blood plasma concentrations of 3-hydroxybutyrat e (3OHB), nonesterified fatty acids (NEFA) and glucose. It is conclude d that feeding supplement after rather than before a period of intake of forage or a bout of grazing may offer a means of minimizing reducti on of forage intake as a consequence of feeding concentrate.