Livestock Response

Table 3 shows the average daily gains and gains/acre of cattle on the trial each year from 1989 to 1999. The average body condition scores for each treatment from 1994 to 1999 are also shown on table 3. This is a visual ranking of the amount of fat on an animal's body with 10 being extremely fat and 1 being extremely thin. This ranking was made because of concern that the animals on the extreme grazing treatment were coming off in poor condition. Figure 2 shows the relationship between stocking rate and average daily gain, figure 3 shows the relationship between stocking rate and gain per acre and figure 4 shows the relationship between stocking rate and economic return for 1991 to 1999. Reference lines indicate the average stocking rate of each of the four grazing treatments in the study. The figures for economic return do not include the costs for land, labor or management which vary widely from one operation to another. The years 1989 and 1990 are not included in these graphs because none of the pastures were stocked heavily enough to significantly reduce average daily gains. As the grazing intensity increased, average daily gain decreased. Gains per acre increase until they reach a certain level and then begin to decline, and profit per acre shows the same pattern. As is apparent from figure 2, the relationship between stocking rate and average daily gain differs significantly between years (p<0.0005). These differences may be due to variations in forage quality, the effect of weather on the animals, class of animal, their initial weight, or their potential to gain. Table 4 A shows the stocking rate which would have resulted in the maximum gain per acre in each year. We can't predict what stocking will result in the maximum gain in the future so its impossible to stock each year for the maximum gain in that year. In retrospect if we were to pick one constant stocking rate for the past nine years which would have provided the greatest gain per acre for this period it would have been 2.449 AUMs/acre. This is the point labeled as "optimum" in figure 3.

 Table 3. Average daily gains and gains per acre from different stocking intensities 1989-1999. Average Daily Gains (lbs/head/day) Desired Grazing Intensity 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 Light Moderate Heavy Extreme LSD(0.05) 2.18 2.35 2.03 2.00 NS2 1.01 1.23 1.17 1.05 NS 1.42a1 1.13ab 0.91b 0.69b 0.48 2.04a 1.89a 1.70a 1.20b 0.44 1.56a 1.56a 1.68a 1.06b 0.40 1.10a 0.90ab 0.74b 0.20c 0.26 1.05a 0.94a 0.86a 0.55b 0.29 1.07a 0.93a 0.81ab 0.44b 0.39 1.63a 1.46a 1.20ab 0.83b 0.45 1.53a 1.31ab 1.03b 0.60c 0.38 1.40a 1.30a 1.19ab 0.96b 0.25 Average Gain (lbs/acre) 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 Light Moderate Heavy Extreme LSD(0.05) 16.84c 33.27bc 41.28ab 61.00a 22.35 13.69c 27.63b 36.47b 52.87a 9.95 16.86b 43.10a 58.83a 61.90a 20.35 18.60d 54.33c 105.58b 129.22a 22.49 13.82c 45.34c 119.31b 166.77a 44.42 20.10b 38.70ab 57.23a 26.64ab 30.75 12.78c 42.37b 70.45a 77.04a 24.30 14.14c 30.10bc 53.25a 45.38ab 22.79 30.27c 66.05b 110.13a 71.10b 27.85 28.29c 62.25b 97.86a 67.98b 29.59 36.50b 59.73b 93.93a 108.49a 24.31 Condition Score 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 Light Moderate Heavy Extreme LSD(0.05) 5.19a 4.84ab 4.80ab 4.21b 0.64 5.08 5.13 5.16 4.74 NS 5.19a 5.11a 4.91ab 4.37b 0.58 5.35 5.24 4.93 -- 3 NS 5.81a 5.71ab 5.21b 4.65c 0.53 5.72a 5.65ab 5.54bc 5.41c 0.18 1Means in the same column followed by the same letter are not significantly different at p=0.05. 2Means not significantly different. 3Not available

Table 4 B shows what the gain/acre would have been in each year if we had stocked at this rate. Table 4 C shows what the gain per acre would have been if we had stocked at a moderate stocking rate. It is important to note that the pastures which are stocked at the heavy and extreme rates were in good condition at the beginning of the study and that their condition has slowly deteriorated over the course of the study. As these pastures have deteriorated we have seen the "optimum" stocking rate gradually decline and we expect that we will see it decline further as the study continues.

If cattle prices were constant, return per acre would peak at a stocking rate somewhere below maximum gain per acre with the exact point depending on carrying costs (interest, death loss, salt and mineral, vet cost, transportation, labor and land). However, fluctuating cattle prices make determining an optimum stocking rate difficult. For example, in May 1991 we stocked our pastures with bred heifers weighing an average of 800 lbs. An 800 lb heifer was valued at \$702.26. Our carrying cost for the season for this animal was \$35.29, so if we had sold her in September when the cattle were removed from the trial we would have had to get \$737.55 to break even. To get this price, assuming a 5% shrink, she would have had to come off the pasture weighing 941 lbs which would be an average daily gain of 1.18 lbs/day. Average daily gains were not very good in 1991 therefore reducing economic returns. In May 1992, we stocked our pastures with bred heifers averaging 750 lbs. Heifers of this weight were valued at \$560.33 in May and at \$620.33 in August at the end of the grazing season. Carrying costs for this animal in 1992 were approximately \$19.77 which would have returned \$40.13 even without a gain in weight. This difference in beginning and ending value of the animals made it possible for the stocking rate with maximum return/acre to exceed the stocking rate with maximum gain/acre in 1992.

 Table 4. Comparison of gain per acre from selected stocking rates. A B C Stocking rate that would result in the maximum gain/acre in each year. Stocking rate that if held constant would result in the maximum gain/acre over the nine-year period. Gain/acre over the nine-year period if stocking rate were held constant at 0.97 aums/acre, the average of the moderate treatment over this period. Year aums/acre gain/acre aums/acre gain/acre aums/acre gain/acre 1991 1992 1993 1994 1995 1996 1997 1998 1999 2.258 2.681 3.406 2.268 3.076 2.036 1.919 2.082 3,179 62.526 134.753 175.776 58.117 84.690 56.957 92.431 91.219 111.371 2.449 2.449 2.449 2.449 2.449 2.449 2.449 2.449 2.449 62.070 133.718 160.343 57.740 80.989 54.311 84.289 87.905 104.992 0.974 0.974 0.974 0.974 0.974 0.974 0.974 0.974 0.974 41.842 78.665 76.214 38.704 43.149 39.403 66.486 61.021 52.609 9yr. ave. 2.545 96.427 2.449 91.810 0.974 55.344

Table 5 A gives the stocking rates with the maximum predicted return per acre for each year from 1991 to 1999. These values correspond to the peaks of the curves in figure 4. Just as we can't predict what stocking will result in maximum gain per acre we can't predict what stocking rate will provide the greatest economic return in any future year. With cattle prices of the last nine years, and the gains that we achieved on these pastures, the one constant stocking rate which would have given us the greatest economic return over the last nine years was 1.844 AUMs/acre. This is the point labeled optimum in figure 4. Table 5 B shows what the return/acre would have been if we had stocked at this rate. Table 5 C shows what the return would have been if we had stocked at a moderate rate. Although the average return per acre is higher under the optimum rate there were three years with negative returns while all years had positive returns under the moderate stocking rate. (Cost for land, labor and management have not been subtracted).

 Table 5. Comparison of return to land, labor and management from selected stocking rates. A B C Stocking rate that would result in the maximum return/acre to land, labor and management in each year. Stocking rate that if held constant would result in the maximum return to land, labor and management over the nine-year period. Returns/acre to land, labor and management over the nine-year period if stocking rate were held constant at 0.97 aums/acre, the average of the moderate treatment over this period. Year aums /acre returns /acre gain /acre aums /acre returns /acre gain /acre aums /acre returns /acre gain /acre 1991 1992 1993 1994 1995 1996 1997 1998 1999 9 yr. ave. 0.882 3.125 2.387 0.669 1.439 2.060 1.113 1.012 3.240 1.769 \$4.10 \$97.11 \$105.10 \$1.99 \$2.05 \$31.83 \$13.35 \$2.11 \$56.58 \$34.91 38.764 130.956 158.275 28.489 59.491 56.948 73.542 63.066 111.327 80.095 1.844 1.844 1.844 1.844 1.844 1.844 1.844 1.844 1.844 1.844 -\$2.76 \$80.20 \$99.53 -\$5.86 \$0.94 \$31.44 \$ 6.91 -\$ 4.81 \$44.92 \$27.83 60.379 121.290 134.723 56.036 70.429 56.384 92.269 89.834 89.843 85.687 0.974 0.974 0.974 0.974 0.974 0.974 0.974 0.974 0.974 0.974 \$ 4.04 \$49.40 \$67.25 \$ 1.46 \$ 0.60 \$21.90 \$13.12 \$ 2.09 \$25.84 \$20.63 41.842 78.665 76.214 38.704 43.149 39.403 66.486 61.021 52.609 55.344

Comparing tables 4 and 5 it can be seen that in all but three years, 1992, 1996, and 1999 the stocking rate with the greatest economic return was less than the rate with the greatest gain per acre. Again it must be stressed that the pastures stocked at the heavy and extreme rates were in good condition at the beginning of the study. As these pastures have deteriorated in condition the "optimum" stocking rate has gradually declined. As the study continues we expect that we will see further reductions in livestock gains on these heavily grazed pastures as they continue to deteriorate, which should have the effect of lowering stocking rate with the "optimum" return.

This trial is continuing and these relationships need more study before we can recommend the stocking rate which will give the greatest return in the long run. Stocking at the rate which produced the greatest economic return in 1999 would damage the pasture and, if prices are low, it could result in substantial financial losses. The returns from a moderate stocking rate are "moderate," higher than the "optimum" stocking rate when prices are poor, and lower when prices are good. We cannot yet recommend the 1.844 AUMs/acre in table 5 because it is only based on nine years of data and changes in forage production, particularly as a result of range deterioration, or cattle prices could make it inappropriate. Also producers should keep in mind that an optimum stocking rate for a stocker operation may not be optimum for a cow-calf operation. In the future we hope to provide more information to help the livestock producer make a sound decision.