Estimation of ergovaline intake of cows from grazed perennial ryegrass containing NEA2 or standard endophyte

Abstract

Abstract Ergovaline concentration was measured monthly from December 2015 to April 2016 in herbage of perennial ryegrass pastures containing NEA2 or standard endophyte (SE) in the Waikato, Manawatu and Canterbury. Ergovaline concentrations were then combined with estimated pasture intake, pasture botanical composition and cow liveweight data from experimental dairy farm systems in the Waikato and Canterbury to estimate dairy cow ergovaline intake (mg/kg LW0.75/day). For the diploid ryegrass 'Trojan' with NEA2 estimated ergovaline intake ranged from 0.01 to 0.029 mg/kg LW0.75/day, levels at which no significant animal production effects have been reported. Ergovaline intake of tetraploid ryegrass 'Bealey NEA2' was at least an order of magnitude lower than this. For the diploid ryegrass, 'Bronsyn' with SE, ergovaline intake was 0.016 to 0.056 mg/kg LW0.75/day, which at the highest level carried a ~20% risk of causing animal production effects for 15% of the samples. AR1 and AR37 pastures, used as controls, contained nil or trace amounts of ergovaline. Keywords: alkaloid, Epichloë festucae var. lolii, Lolium