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Animal Science Departmental Report 2004-2005 Return to Beef Cattle articles
Performance of Growing Beef Cattle Strip-Grazing Stockpiled Endophyte
Infected, Non-Toxic Endophyte Infected and Endophyte Free Tall Fescue M. E. Drewnoski, E. J.
Oliphant, M. H. Poore, J. T. Green, and M. E. Hockett Summary Data suggests
that non-toxic endophyte infected fescue has the agronomic persistence and
growth similar to that of endophyte infected fescue. Grazing endophyte infected
fescue in a stockpiling system during the winter in the piedmont of NC does not
lower animal gains. Introduction Consumption of tall fescue (Festuca arundinacea) infected with the fungus Netyphodium coenophialum has been associated with poor animal performance. Ergot alkaloids produced by this endophyte are thought to be the cause of fescue toxicosis. This endophyte is also responsible for the strong persistence and competitiveness of the endophyte infected tall fescue when compared with endophyte-free tall fescue Non-toxic endophyte infected fescue is does not produce the ergot alkaloids but does produce other alkaloids which increase the plants resistance to pests and disease. Recently published studies (Parish, 2003) have shown that the non-toxic endophyte infected fescue has the animal performance similar to that of the endophyte free while have the strong agronomic performance comparable to that of the endophyte infected. However, more long term data conducted using a variety of production systems is needed. The objective of this study was to evaluate animal performance and agronomic persistence of non-toxic endophyte-infected (EN) fescue, endophyte-infected (E+) and endophyte-free (E-) tall fescue in a system that includes a stockpiling phase and spring grazing phase. Materials and Methods A 5-yr winter grazing study was conducted in 2001, 2002, 2003, 2004 and 2005. Stands were established in fall 1999. In August of each year the stands were clipped and in September they were fertilized. Forage was allowed to accumulate from August until December. In December of each year 48 Angus-cross tester cattle, with average initial body condition score (BCS) of 5, were grazed on one of three treatments for 86 days (yr 1), 70 days (yr 2), 86 days (yr 3), 72 days (yr 4), and 56 days (yr 5). Steers were used the first year and heifers were used in subsequent years. Extra “grazer” heifers were used in yrs 3 (n=12) and 4 (n= 10) in an effort to more uniformly utilize the available forage. Cattle were given a daily allotment of forage, under strip-grazing management, with a target residual height of 2 inch. Total pre-graze forage mass was determined in mid November using a falling plate meter. Forage samples were taken every two weeks and hand separated for species composition. After the end of the winter grazing season heifers were maintained on trt hay in yrs 2, 3 and 4, until the beginning of April. After sufficient forage mass had accumulated on the plots heifers were rotationally grazed on their trt from April until the beginning of July. The spring trial lasted 56 days (yr 2), 58 days (yr 3) and 70 days (yr 4). Results and Discussion In the winter, average daily gain on pasture (Table 1) did not differ among treatments (P = 0.15) but did differ by year (P < 0.01). In the winter on a stockpiling system, cattle gained the same regardless of treatment. This may be due to the combination of alkaloid concentration decreasing in the winter (Kallenbach, 2003) and cool ambient temperature. In late spring the heifers on the non-toxic endophyte and the endophyte free had higher average daily gains (Table 2) than the heifers on the endophyte infected (P <0.01). Total pre-graze forage mass did not differ between E+ and EN (P = 0.16) but was lower (P < 0.01) for E- (3545 lbs/ac, 3126 lbs/ac, and 3411 lbs/ac for E+, EN, and E- respectively). Stand persistence (percent fescue in the paddock) was lower (P < 0.01) in the E- stands (82.5%) than for the E+ (90.7%) and EN (88.4%). The non-toxic endophyte-infected fescue appears to have the positive agronomic qualities of endophyte infected and the animal performance similar to the endophyte free. In a system that includes stockpiling, EN seems to be a viable alternative to E+ having persistence and yield similar to that of E+ even after intensive winter grazing. Implications Non-toxic endophyte-infected fescue could be a good option for late spring and fall grazing. While endophyte infected fescue may still have a place in production systems as a source of forage for winter grazing. References Kallenbach, R.L., G.J. Bishop-Hurley, M.D. Massie, G.E. Rottinghaus, and C.P. West. 2003. Herbage Mass, Nutritive Value, and Ergovaline Concentration of Stockpiled Tall Fescue. Crop Sci. 43:1001-1005. Parish, J. A., M. A. McCann, R. H. Watson, N. N. Paiva, C. S. Hoveland, A. H. Parks, B. L. Upchurch, N. S. Hill, and J. H. Bouton. 2003. Use of nonergot alkaloid-producing endophytes for alleviating tall fescue toxicosis in stocker cattle. J. Anim. Sci. 81:2856–2868. Table 1. Animal performance during winter as influenced by
treatment and year
Table 2. Animal performance during spring as influenced by treatment
and year
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