Behavior of Beef Steers Grazing Five Different Tall Fescue Cultivar-Endophyte Combinations.

Consumption of wild-type toxic endophyte-infected tall fescue (‘Kentucky 31’) has previously been shown to have a negative impact on the behavior and performance of cattle.  A 56 d study was conducted over two years during the Fall to evaluate behavior of beef cattle grazing the following tall fescue pasture treatments:  ‘Kentucky 31’ toxic endophyte-infected (KY31), Jesup AR542 endophyted infected (J542), ‘GA-186’ AR584 endophyte infected (GA584), ‘PDF’ AR584 endophyte infected (PDF584), and ‘KYFA 9301’ AR584 endophyte infected (KY584). Three-2 ha paddocks of each treatment were grazed by British-Continental crossbred steers (n=75 per year, initial body weight = 322 kg), stocked at 2.5 steers per ha. One steer in each paddock wore a behavior monitoring device (IceTag v 2.004) that recorded animal activity. Daily time spent grazing, standing still, lying down, and walking were analyzed using the MIXED procedure of SAS (SAS Inst., Cary, NC) and a significance level of α ≤ 0.05 was used. Time spent grazing did not differ (P ≥ 0.3) between years (Yr 1 = 39.7, Yr 2 = 40.4%) or treatments. Time spent standing still did not differ (P = 0.2) between years (Yr 1 = 15.6, Yr 2 = 16.8%) however time spent lying differed between years (P ≤ 0.008; Yr 1 = 44.6, Yr 2 = 42.8%) and treatments with KY31 steers lying down less and standing more (P ≤ 0.03) than GA584 or PDF584. Steps taken per day did not differ (P ≥ 0.4) between years (Yr 1 = 3003, Yr 2 = 2960) or treatments.  All four novel endophtye tall fescue treatments experienced some level of contamination of ergot alkaloid producing endophyte (J542, 30.3%; GA584, 11.8%; PDF584, 5.5%; and KY584, 10.0%) presumably from buried seed, while KY31 had 78%. Cattle exposure to ergot alkaloids across treatments could explain some similarities in behavior between treatments.