RANGELAND RESEARCH ROUNDUPBy Justin Derner & Justin Reeves

Lessons From Long-TermCattle Weight Gain Data

Havingjust read The Worst Hard Timeby Timothy Egan, I am awestruck bythe determination, resilience, persever-

ance and fortitude of those who remained on thewestern Great Plains during the Dust Bowl yearsof the 1930s.While we struggle with the severe toexceptional drought conditions remaining fromthe 2012 growing season, envision the conversa-tions livestockproducers, natu-ral resource pro-fessionals andbankers will behaving if thesecurrent droughtconditions per-sist through2013.

The Range-land ResourcesResearch Unithas a wealth oflong-term graz-ing studies inboth the north-ern mixed-grassprairie and shortgrass prame, which we areindebted to the foresight of the early scientiststo establish and subsequent scientists and staffto maintain through the years. Justin Reeves, apost-doc, joined our unit in June and has beenpouring through these long-term data to findthe lessons learned with regards to influencesof precipitation (and temperature) on beef pro-duction. Here, we will highlight key findingsfrom northern mixed-grass prairie with respectto both yearling steers and cow-calf pairs. Sub-sequent columns will address findings from theshortgrass prairie.

Yearling steer weight gain data has been col-lected at the USDA-ARS High Plains GrasslandsResearch Station in Cheyenne at light, moderateand heavy stocking rates from 1982-2012. Weexamined the effects of spring and summer tem-perature and precipitation, as well as prior yearprecipitation, on beef production.

At heavier stocking rates, steer weightgains weremore sensi-tive to weath-er variations.A novel find-ing was tem-perature (rel-atively coolsprings andwarm sum-mers) had alarge predic-tive role insteer weightgains. Steerweight gainswere highestduring years

with cool, wet springs and warm, wet sum-mers, corresponding with .optimum growthconditions for this mixed cool-season/warm-season plant community. Using three-monthseasonal clusters of precipitation and temper-ature that are forecasted and freely availablefrom the Climate Prediction Center of the U.S.National Oceanic and Atmospheric Adminis-tration up to a year in advance, these fore-casts can provide ranchers with an increasedpredictive capacity to adjust stocking rates toweather variability, thereby reducing enter-prise risk in advance of the grazing. season.

lS-CowCountry Winter 2013

Cow-calf weight gain data were also collect-ed at the USDA-ARSHigh Plains Grasslands Re-search Station from 1975-2012,with Herefordsused from 1975-2001and a Red Angus x Cha-rolais x Salers cross from 2003-2012(cattle werenot grazed in 2002).We were interested in theeffects of the same weather variables as for thesteer weight gain data on cow, calf and total pairbeef production.

Overall, Hereford cow-calf pair beef produc-tion was more sensitive to the seasonal weathervariables than cows or calves individually. ForHereford cow, calf, and cow-calf weight gains,spring temperature and precipitation were im-portant determinants of beef production. Priorwinter precipitation was also influential in sub-..

sequent weight gains of calves and cow-calfpairs during the summer grazing season. Her-efords were more sensitive to seasonal weatherpatterns than the crossbreds, indicating that sea-sonal temperature and precipitation effects arelessened on these larger crossbred animals.

These findings are being incorporated intodecision support tools to help ranchers optimizestocking rates and minimize enterprise risk inadvance of the upcoming grazing season. Addi-tionally, these findings will be used in a recentlyfunded proposal through the Wyoming Agri-cultural Experiment Station Competitive GrantsProgram (lead scientist is John Ritten) to criti-cally evaluate the economic impacts of climate

..change and drought on Wyoming ranchers. •