COMBINED ANALYSIS OF TALL FESCUE STEER GRAZING STUDIES IN THE EASTERNUNITED-STATES

The mixed-models procedure (MMP) was used to analyze pooled data sets from 12 independent studies conducted during the last 13 yr at nine lo cations in seven states to provide combined estimates of daily gains b y beef steers (Bos taurus) grazing tall fescue (Festuca arundinacea Sc hreb.) pastures free of (E-) or infested (E+) at different levels with the endophytic fungus Acremonium coenophialum. Treatments included lo w-infestation (less-than-or-equal-to 5% E+), moderate-infestation (gre ater-than-or-equal-to 20 to less-than-or-equal-to 35% E+), and high-in festation (greater-than-or-equal-to 50 to less-than-or-equal-to 97% E) tall fescue pastures, and, in tall fescue-clover (Trifolium spp.) mi xtures, pastures at the same E+ levels with approximately 25 and 10% c lover in spring and summer stands, respectively. Spring, summer, and c ombined spring + summer data were analyzed separately. The MMP permitt ed estimation of the fixed effects of treatments over a broad inferenc e space of future years and different tall fescue pastures over a wide geographic range; detected relationships that had not been apparent i n the individual studies, such as the interactions between clover pres ence and E+ infestation levels; and provided a more coherent body of i nformation than did the results obtained from each discrete study. Log istical and financial constraints that force undesirable compromises i n the conduct of future grazing and other expensive or time-consuming research may be avoided by using MMP within the context of cooperative projects.