Preference by sheep for endophyte-infected tall fescue grown adjacent to or at a distance from alfalfa

Abstract

Two experiments were conducted to assess preference by sheep for endophyte-infected tall fescue growing in monoculture at least 5 m away from alfalfa (fescue-middle (FM)) over endophyte-infected tall fescue growing adjacent (0.2 to 1 m; fescue-alfalfa (FA)) to alfalfa (FA), and the effect of legume scent on preference for endophyte-infected tall fescue. In Experiment 1, 10 six-month-old lambs were offered for 12 days a choice of freshly harvested FA and FM. On days 13 and 14, lambs were offered the same choice, except cages (to allow access only to scent) containing freshly harvested alfalfa were put in the feeders containing FA, whereas cages containing freshly harvested FM were included with the feeders containing FM. Forage intake was measured 1 h after feeding and at three consecutive 2-h intervals thereafter. FA contained greater ( P < 0.002) concentrations of the alkaloid ergovaline (360 ± 27 ppm) and CP (8 ± 0.4%) than FM (219 ± 27 ppm and 6 ± 0.4%, respectively). Lambs preferred ( P < 0.05) FA to FM during the 1 st hour of feeding, but the differences became smaller and disappeared in later feeding periods ( P < 0.005). Lambs offered FA with alfalfa scent or FM with FM scent preferred ( P < 0.05) FA but only on the 2 nd day. In Experiment 2, 10 six-month-old lambs were offered a choice of FM with cages (to allow access only to scent) containing freshly harvested alfalfa or FM for 8 days. During the following 4 days, FM in the cages was replaced with freshly harvested sainfoin. Preference was greater ( P < 0.05) for FM offered with alfalfa scent than for FM offered with FM scent only on days 4 and 8. When lambs were offered FM with alfalfa or sainfoin in cages, they preferred ( P < 0.05) tall fescue with sainfoin scent over fescue with alfalfa scent, but intake was variable across hours and days ( P < 0.001). It is concluded that (1) lambs adjusted their intake of and preference for FA and FM over successive feeding bouts within each day, likely owing to an attempt to balance intakes of nutrients and alkaloids and (2) olfactory cues influenced preference, but to a lesser extent than nutrients and alkaloids in endophyte-infected tall fescue.

How planting configuration influences plant secondary metabolites and total N in tall fescue (Festuca arundinacea Schreb.), alfalfa (Medicago sativa L.) and birdsfoot trefoil (Lotus corniculatus L.): Implications for grazing management

“…Consistent with this hypothesis, EV concentration in E+TF was greater when the plant grew adjacent to Alf or BFT than when it grew in a monoculture. These results are consistent with findings from a previous study where E+TF had greater EV concentrations when growing adjacent to Alf than when growing in monoculture (Friend, Provenza, & Villalba, ). Interestingly, Friend et al.…”

“…Interestingly, Friend et al. () also found that when sheep were given a choice between E+TF growing adjacent to Alf or in monoculture (with less EV), sheep preferred E+TF with greater EV which also had more crude protein, but only during the first hour of the feeding period. The correlation coefficient between EV and N in E+TF indicated a significant positive relationship which may imply that increased N renders greater EV in E+TF.…”

Comparison and Diet Preference of Novel Endophyte‐Infected Tall Fescue Cultivars

“…Additionally, this short grazing scheme enabled us to detect which cultivar cattle grazed first, indicating the favorite cultivar. During the first hour of grazing, sheep preferred to graze a tall fescue and alfalfa mixture with higher CP, even though alkaloid content was higher, vs. tall fescue with alfalfa grown 5 m away with a lower CP and alkaloid content; preference for the high-alkaloid mixture decreased after the first hour (Friend et al, 2015). In grazing studies, cattle (Lyman et al, 2012) and sheep (Friend et al, 2015) were observed to adjust their intake of CTE+ tall fescue over successive grazing bouts within each day in an attempt to balance intake of alkaloids.…”

“…These studies used 21- (Jackson et al, 1984) and 53-d feeding trials. In grazing studies, cattle (Lyman et al, 2012) and sheep (Friend et al, 2015) were observed to adjust their intake of CTE+ tall fescue over successive grazing bouts within each day in an attempt to balance intake of alkaloids. Additionally, this short grazing scheme enabled us to detect which cultivar cattle grazed first, indicating the favorite cultivar.…”

“…In this study, a shorter grazing period was used to prevent overgrazing of any one plot, allowing the animals to make preference selection based on the characteristics of the cultivar. Friend et al (2015) reported differences in feeding preference within the first hour of grazing and attributed these differences to CP and alkaloid content of the tall fescue and alfalfa (Medicago sativa L.) grazing scheme. Postingestive feedback (Provenza, 1995) may play a role in cattle grazing CTE+ KY31 as often as nontoxic cultivars.…”