The effects of several supplementation frequencies on forage use and the performance of beef cattle consuming dormant tallgrass prairie forage

Two experiments were conducted to quantify the impact on forage use and per formance of varying supplementation frequency of cattle consuming forage di ets across a range of frequencies. In both experiments, a common supplement was used that contained a relatively high concentration of CP (43%) and wa s fed at the following frequencies: 1) 2 d/wk; 2) 3 d/wk; 3) 5 d/wk; and 4) 7 d/wk. In Exp. 1, 120 Hereford x Angus cows (BW = 537 kg) grazing winter tallgrass-prairie range were supplemented at the various frequencies from D ecember 7 until calving (average calving date = 3/7/99). All treatments pro vided the same quantity of supplement on a weekly basis (12.74 kg, as-fed) but divided the amount delivered on a given day equally among the number of supplementation events for that treatment. Less BW was lost from December 7 through calving (linear effect, P = 0.02) as frequency of supplementation increased, but the magnitude of difference in weight change was relatively small. Body condition responded similarly through early February (linear e ffect, P = 0.02), although treatment effects were not as distinct at calvin g (cubic effect, P = 0.11). In Exp. 2, 16 ruminally fistulated Hereford x A ngus steers (BW = 257 kg) were blocked by weight and assigned to one of the four frequencies of supplementation. Steers were offered tallgrass prairie hay (73.5% NDF, 4.8% CP) ad libitum and were supplemented at a rate (relat ive to BW) similar to that of the cows in Exp. 1. Increasing frequency of s upplementation increased (linear effect, P = 0.02) forage OM intake, OM and NDF digestion, and digestible OM intake. However, the most prominent diffe rences in forage OM intake tended (cubic effect, P = 0.07) to occur with th e two extreme frequencies of supplementation. In conclusion, forage use was improved with an increased frequency of supplementation, but the impact on performance is not likely to be large unless extreme differences in freque ncy occur.