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ARS Home » Midwest Area » Madison, Wisconsin » U.S. Dairy Forage Research Center » Research » Publications at this Location » Publication #219315

Title: Post-Weaning Performance of Fall-Born Beef Steers Weaned from Endophyte-Infected Tall Fescue Pastures on Different Dates in the Spring

item Caldwell, James
item Coffey, Ken
item Coblentz, Wayne
item Jennings, John
item Hubbell Iii, Donald
item Kreider, David
item Rosenkrans, Charles

Submitted to: Journal of Animal Science
Publication Type: Abstract Only
Publication Acceptance Date: 11/19/2007
Publication Date: 3/17/2008
Citation: Caldwell, J.D., Coffey, K.P., Coblentz, W.K., Jennings, J.A., Hubbell Iii, D.S., Kreider, D.L., Rosenkrans, C.D. 2008. Post-Weaning Performance of Fall-Born Beef Steers Weaned from Endophyte-Infected Tall Fescue Pastures on Different Dates in the Spring. Journal of Animal Science. 86 (e-Supplement 3): 91.

Interpretive Summary:

Technical Abstract: Earlier weaning of fall-born calves grazing Neotyphodium coenophialum-infected tall fescue (E+) in the spring should reduced exposure of those calves to E+ toxins, resulting in improved long-term animal performance. However, a previous study did not support this hypothesis. A total of 118 Gelbvieh × Angus crossbred steer calves were used in a 3-yr study to determine the optimal time to wean fall-born calves grazing E+ fescue. Fall-calving cow-calf pairs were allocated randomly by weight and age immediately prior to the onset of calving to one of four weaning dates: 1) March 16 (177 d of age; MarW), 2) April 13 (204 d of age; AprW), 3) May 11 (236 d of age; MayW), and 4) June 8 (264 d of age; JuneW). The MarW and AprW calves were moved to wheat pasture whereas MayW and JuneW where moved to bermudagrass pastures following a 14-d fence-line weaning program. Steer BW at weaning increased (P<0.001) linearly across weaning dates and tended to increase (P=0.06) linearly at the time they were shipped to a feedlot, but steer BW at the end of the feedlot period and average daily gain during the feedlot period did not differ (P>0.19) across weaning dates (MarW 592, 1.8; AprW 577, 1.8; MayW 597, 1.8; and JuneW 609, 1.9 kg, respectively). Hot carcass weight tended to increase (P=0.10) in a linear manner across weaning dates. Quality grade did not differ (P=0.84) across weaning dates, with 47% of the steers grading choice and 53% grading select. Yield grade, and during the first 2 yr of the study, ribeye area, and marbling score did not differ (P>0.12) across weaning dates, but backfat thickness tended to increase (P=0.09) linearly across weaning dates. Therefore, weaning of fall-born steer calves from E+ pastures later may have short-term benefits, but those benefits may not persist throughout a feedlot period.