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.

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 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).

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.