44 Relative preferences for cool season grass hay cultivars in adult horses

Abstract

Tall fescue (TF) is productive in the Midwest and nutritionally similar to other cool season grasses. The potential for adverse effects has been documented in late gestation mares and growing horses, however effects on non-breeding mature horses are negligible. There are now more varieties of TF with novel endophytes designed to produce less ergovaline, the alkaloid to which toxicosis is attributed. The objective of this study was to evaluate relative preference for different monocultured hay by horses. In the fall of 2017, a field trial examining the performance of cool season grasses was established in Wooster OH. For the present study 7 were harvested: TF (v. KY 31; toxic endophyte), TF (v. Bronson; endophoyte free), TF (v. Texoma MaxQ; novel/non-toxic endophyte), Meadow Fescue (v. Preval), Festulolium (v. Spring Green), Perennial Ryegrass (v. Elgon), and Orchardgrass (v. Crown Royal) and a control was made by mixing all 7 cultivars together. First cutting chopped hay was created in 2019 and analyzed for nutrients and ergovaline concentrations. Ergovaline was below detectable limits in all samples, so 2020 hay was analyzed for nutrients and the presence of endophyte (via tiller staining) with only Bronson (3.3%) and Texoma Max Q (16.7%) having a low level of infection. Taste preferences were evaluated during summer 2019 and winter 2020 using a randomized complete block design with cultivar and bucket location as variables. Stalls had 8 buckets along a wall visible to pre-installed foaling cameras for recording. The same 4 mature horses at maintenance were used for the preference testing both years. Horses were fasted 30 min before entering the testing stalls and had access to the cultivars for 30 min. Weight consumed was recorded. Equine preference data for cultivar and bucket location were analyzed in JMP Pro 15. There was a significant difference (P < 0.001) in average consumption based on cultivar, however, standard deviations were high for all cultivars. In 2019 the cultivars in order of most to least preferred by the horses based on amount consumed (mean consumption ± standard deviation) were: 1) Perennial Ryegrass (2042 ± 243 g), 2) Orchardgrass (1258 ± 853), 3) Festulolium (1007 ± 900 g), 4) Control (771 ± 295 g), 5) TF Texoma MaxQ; non-toxic endophyte (451 ± 266 g), 6) TF Bronson; endophyte free (163 ± 86 g), 7) Meadow Fescue (118 ± 75 g), 8) TF KY31 (35 ± 98 g). Results were similar in 2020 with only the last 2 cultivars transposed in rank. Horses demonstrated a consistent preference for some species of cool season grasses in both 2019 and 2020, however the preference does not appear to be due to endophyte presence.