Satisfying an animals\u27 nutritional needs can help optimize performance and keep an animal healthy. Meeting these nutritional requirements is often complicated by the low quality characteristics of hay, requiring supplementation with concentrate feedstuffs to offset this low nutrient density. The objectives of this study were to determine the impact of supplementation with soybean hulls (SH), distiller\u27s dried grains with solubles (DDGS), or a 50:50 mixture of the two (MIX) on ruminal fermentation characteristics and in situ forage disappearance in lactating and non-lactating ruminally-cannulated cows offered tall fescue hay. For this experiment, a basal diet of tall fescue hay was offered for ad libitum consumption from large round bales along with supplements of either SH, DDGS, or MIX fed at 0.5% of each cow\u27s body weight. The study consisted of six, 21-d periods using six ruminally-cannulated cows (679 ± 18.7 kg body weight), three lactating and three non-lactating, and the three supplements. Following a 14-d adaptation period to the diets, Dacron bags containing 5 g of ground fescue hay were placed individually into the rumen of each cow at specified intervals over a period of 7 d. On d 21, the bags were removed and washed in a top-loading washing machine ten times. Rumen fluid samples were collected on d 21 of each period at 2 h intervals from 1600 h to 2400 h for analyses of ruminal ammonia and volatile fatty acids. Ruminal forage disappearance was not affected (P ≥ 0.44) by diets. Total VFA were greater (P \u3c 0.05) from SH but the proportion of propionate was greater (P \u3c 0.05) from DDGS. Therefore, supplementation with DDGS should improve the energy status of cows being fed poor-quality hay as compared to being offered SH or MIX
