Animal Preference of Tall Fescue during Reproductive Growth in the Spring

Abstract

AbstractAnimal preference may create problems when diverse tall fescue (Festuca arundinacea Schreb.) germplasm is evaluated under grazing. The objective of this experiment was to relate differences in animal preference of tall fescue populations to maturity and genetic background. In 1988, 25 entries were established in small plots at the Black Belt Substation, Marion Junction, AL on a Eutaw clay (very‐fine, montmorillonitic, thermic, Entic Peluderts) within each of four 0.8‐ha pastures. Pastures were grazed during the spring 1990 and 1991 seasons at stocking rates of 2.5, 3.75, 5.0, and 6.25 crossbred yearling Angus steers ha±1 (Bos spp.). Animal preference was measured by visually rating the amount of forage removed at 3, 6, and 13 d after grazing was begun in 1990, and after 3 and 6 d in 1991. Population‐by‐stocking‐rate interaction was significant for all preference ratings, but accounted for only 2 to 5% of the total variation. Changes in magnitude were not important. Based on bivariate plots of preference during spring reproductive growth vs. maturity, three groups were distinguishable: (i) two very early maturing populations with a low preference score, (ii) a group of 17 medium‐maturing populations with a medium to low preference score, and (iii) six late maturing populations with a high preference score. Low preference during grazing of tall fescue during spring reproductive growth was an attribute of mediterranean germplasm and of populations selected in the southern USA. A comparison of ‘Georgia 5’ EI vs. EF tall fescue revealed that cattle preferred the endophyte free material at all rating times during reproductive growth in the spring in both years. This preference can be uniquely attributed to the absence of the endophytic fungus Acremonium coenophialum Morgan‐Jones and Gams.