Submitted to: Agronomy Journal
Publication Type: Peer reviewed journal
Publication Acceptance Date: 12/15/2006
Publication Date: 5/11/2007
Citation: Popp, M., Coffey, K., Coblentz, W.K., Johnson, Z., Scarbrough, D., Humphry, J.B., Smith, T., Hubbell, D.S., Turner, J. 2007. Empirical analysis of weaning and pasture rotation frequency with implications for retained ownership. Agronomy Journal. 99:747-754 Interpretive Summary: Most of the tall fescue found in the Ozark Highlands is infected with a fungal endophyte that produces ergot alkaloids that are toxic to livestock. These toxins cause various symptoms in cattle that are described collectively as fescue toxicosis. One possible approach for alleviating this condition in fall-born calves is to wean early (April), which is before toxin levels in tall fescue reach their maximum. However, this technique was not successful. Weaning weights were lighter in April relative to late-weaned (June) calves. More importantly, April-weaned calves remained lighter than June-weaned calves at the time they entered the feedlot, and slighter lighter even at slaughter. Furthermore, more intensive pasture management (twice weekly) did not improve steer or heifer calf performance relative to less intensive (twice monthly) rotation management. Regardless of the production system, returns were greatest for calves retained through the feedlot finishing stage, relative to sale at weaning, or when entering the feedlot.
Technical Abstract: The economic impact of rotation frequency (twice weekly vs. twice monthly until time of weaning) and time of weaning (early April vs. 56 d later) was examined for fall-calving cows using a modified put and take grazing strategy implemented to maintain equal grazing pressure across production systems. Cow and/or calf death losses resulted in replacements with either bred cows or cow–calf pairs. While the analysis on heifer calves was limited to sale at time of weaning, steer calves were tracked through the feedlot stage to determine if the time of sale would alter production system recommendations. For the conditions presented in this study, cow–calf producers may be advised that (i) relative to late weaning, early weaned calves did not regain their weight disadvantage observed at time of weaning; (ii) more intensive pasture management (rotating twice weekly rather than twice monthly) was not worth the effort because partial return results for late-weaned steer and heifer calves did not differ statistically by rotation frequency, regardless of sale time; (iii) partial returns were highest for steer calves retained through the finishing stage at the feedlot (regardless of production system) compared with sale at the time of weaning or at the time of placement in the feedlot;(iv) the range of returns or financial risk exposure increased with length of calf ownership. However, use of long-term average prices excluded input price risk from the analysis and output price risk was only partially addressed.