Plant and Animal Performance In Mixed Tall Fescue/Legume Pastures.

Tall fescue is the one of most used grasses in irrigated pastures throughout the Intermountain West. Two limitations of tall fescue are decrease in productivity during hot summer months and the need for supplemental nitrogen (N). The objective of this research is to examine the efficacy of tall fescue+alfalfa (TF+ALF), tall fescue+birdsfoot trefoil (TF+BFT), tall fescue+nitrogen fertilizer (TF+N), and tall fescue without nitrogen fertilizer (TF-N) on forage quality, forage quantity and livestock performance.  Research plots were planted at the Utah State University Pasture Research Facility in Lewiston, UT in 2010 and grazed in 2012. Treatments were arranged in a randomized complete block design with four replications and divided into four paddocks per replication. Three Angus crossbred steers with an average starting weight of 380 kg were placed on each treatment and rotated to a new paddock every 7 days. A put-and-take method was used throughoutthe growing season such that each paddock received 80% utilization. Four forage samples were collected from each paddock just prior to grazing using a .5-m² quadrat for determination of dry matter (DM) and nutrient content. ADF, NDF, IVTD, and TDN were used to calculate nutrient content. Steers were weighed every 28 days. DM was similar among the TF+N (5668 kg ha^-1),TF+BFT (5534 kg ha^-1), and TF+ALF (5249 kg ha^-1) treatments. Whereas, DM in TF-N treatment was lower (4075kg ha^-1).  Steer average daily gains (ADG) were also similar among the TF+BFT (0.76 kg d^-1), TF+N (0.66 kg d^-1), and TF+ALF (0.62 kg d^-1). However, ADG on TF-N treatment was much lower (0.31 kg d^-1).  Pasture performance appears to be equal or higher on TF+BFT and TF+ALF than TF+N in both DM yields and steer ADG. A comparison of nutrient content will also be presented.