Linda Benedict, Blouin, David C., Gillespie, Jeffrey M., Wyatt, Wayne E. | 3/6/2014 9:37:58 PM
Wayne E. Wyatt, Jeffrey M. Gillespie, David C. Blouin and Bradley C. Venuto
Most beef operations in Louisiana are based on a cow-calf production system. Efficient use of available pasture is critical to the sustainability and economic viability of these operations. Stocking rate and method are managerial factors affecting frequency and height of defoliation of pasture forages. A stocking system that increases production and economic efficiencies without making unreasonable time, labor and resource demands and that is sustainable year-round is desirable. Research was undertaken at the LSU AgCenter’s Iberia Research Station to address the issues of productivity and economics of stocking rate and rotational versus continuous stocking methods for cow-calf production.
Over a five-year period (Phase I 1999-2002; Phase II 2004-2005), mature Brangus cows with calves-at-side were allocated to six different stocking treatments (four stocking treatments per phase). During Phase I, the continuous stocking method was compared at low, medium and high stocking rates. Low was 0.5 cows per acre (2 acres per cow); medium was 0.8 cows per acre (1.3 acres per cow); and high was 1.1 cows per acre (0.9 acres per cow). A fourth rotational stocking treatment with eight paddocks using the high stocking rate was also included. Consequently, the comparison of continuous and rotational stocking methods was done at a high stocking rate in Phase I. During Phase II, the rotational stocking (eight-paddock) method was compared at low, medium and high stocking rates and a continuous- medium stocking treatment was also included. The comparison of continuous and rotational stocking methods was done at a medium stocking rate in Phase II. Both phases included the continuous-medium and the rotational- high stocking treatments.
Pastures in both phases contained warm-season grasses (common bermudagrass and dallisgrass) as a perennial sod. In the fall of each year, pastures were seeded with annual ryegrass. Pastures annually received 155 pounds per acre of nitrogen in three split applications.
Cows were maintained on pasture on a year-round basis. Cow body weights were recorded in January (pre-calving), April (pre-breeding), July (post-breeding), October (weaning) and again in January of the subsequent year. Calves were weighed at weaning of each year. An adjusted 205-day weight (adjusted for cow age, calf gender and weaning age) was calculated. Also, pasture weaning weight – pounds of calf per acre – was calculated.
In Phase I, increases in stocking rate resulted in numeric decreases in average cow weight, although there was no statistical difference between continuous-low and continuous-medium stocking rates (Figure 1). Nor was there a difference between continuous and rotational stocking when both were stocked at the high stocking rate. In Phase II, the rotational-low stocking treatment resulted in a greater average cow weight than the remaining stocking treatments. Average cow body weight was similar for the rotational- medium and rotational-high stocking treatments. Also, average cow body weight was similar between the rotational and continuous stocking treatments when compared at the medium stocking rate. Apparent cow weight differences in the Phase I and Phase II continuous-medium and rotational-high stocking treatments were likely because of greater rainfall accumulation in the spring and summer months of Phase II compared to Phase I. Also, greater amounts of supplemental feed were fed to cows during the winters of Phase II.
The effect of stocking rate within the continuous stocking treatments in Phase I on calf adjusted 205-day weights (adjusted for cow age, calf gender and calf age at weaning) was very pronounced (Figure 2). Calf adjusted 205-day weight was greater for low compared to medium stocking rates and for medium compared to high stocking rates. Such was not the case for the rotational stocking treatments in Phase II. In Phase II, calf adjusted 205-day weights were simi lar between the stocking treatments. The comparison of continuous versus rotational stocking was similar for calf adjusted 205-day weight for both the high (Phase I) and the medium (Phase II) stocking rates.
In both phases, there was a pronounced impact of stocking rate upon pasture weaning weight (Figure 3). Under continuous (Phase I) and rotational stocking (Phase II), increases in stocking rate significantly inflated the pounds of calf weaned per acre. However, whether continuous versus rotational comparisons were made at the high (Phase I) or medium (Phase II) stocking rates, pounds of calf weaned per acre were the same.
Detailed production data collected in the study allowed for the estimation of costs and returns associated with each of the stocking strategies. Input prices assumed in the study were those published in annual LSU AgCenter cost of production estimates. Calf prices were adjusted according to their weaning weights. In Phase I, the stocking strategies yielding the greatest net returns over total expenses per acre, excluding labor, were the continuous- medium and continuous-high strategies, with means of $109.07 and $111.95, respectively (Figure 4). These were greater than the net returns over total expenses for the continuouslow and rotational-high strategies, at $39.76 and $57.32, respectively. While the continuous-high and rotationalhigh strategies yielded the greatest returns since more beef was produced per acre, they also resulted in greater expense, particularly in the case of the rotational-high, where there was increased machinery expense associated with moving animals and pasture maintenance, and increased expenses associated with cross-fencing. In Phase II, the rotational-high strategy resulted in the greatest net return per acre, at $247.30, followed by the rotational- medium and continuous-medium, and finally the rotational-low. In this phase, the greater net returns of the high stocking rates resulted from more beef being produced per acre.
In Phase I, 10.6 hours of labor were required per acre in the rotationalhigh compared to 6.3 hours per acre used in the other strategies (Figure 5). In Phase II, the rotational stocking strategies similarly required much greater labor. In both cases, the increased labor was associated primarily with moving animals and shades, repairs and maintenance on fencing, and increased machinery time associated with forage management. In terms of animal and pasture performances, stocking rate appears to affect both more so than does stocking method. Producers will find a larger effect on production by manipulating the stocking rate to their particular environment and then consider stocking methods.
In terms of returns over total expenses (labor excluded) on a per acre basis, greater returns were realized for Phase II than in Phase I. The reversal of the comparison of continuous- medium to rotational-high between the two phases was surprising and can possibly be attributed to a more favorable weather environment of the latter phase. Also, hay was harvested from rotational treatments in the latter phase and contributed to income for those treatments. It is worth noting that at comparable stocking rates, there was either greater (Phase I) or equal (Phase II) returns for the continuous compared to their rotational counterpart. Returns over total expenses would suggest that producers again focus more attention on stocking rate than on stocking method. As anticipated, labor expended increased in response to increases in stocking rate and in response to rotational grazing.
Wayne E. Wyatt is a professor at the Iberia Research Station, Jeanerette,La. Jeffrey M. Gillespie is a professor in the Department of Agricultural Economics and Agribusiness. David C. Blouin is a professor in the Department of Experimental Statistics. Bradley C. Venuto, formerly with the LSU AgCenter, is deceased
(This article was published in the 2014 winter issue of Louisiana Agriculture magazine.)