| | We know that swath grazing is better than feeding greenfeed because it is cheaper feed per cow/day. We also know that baling, feeding and transportation costs are eliminated with swath grazing. Carrying capacity also makes a difference.
Research at the Lacombe Research Centre showed that over four years carrying capacity ranged from 355 to 195 cow-days per acre (Table 1). It costs about the same per acre no matter what the carrying capacity. This means that during the low year daily feed costs were almost double (1.8) what they were in the high year. No wonder good producers want to get carrying capacity as high as possible!
Table 1. Range in Barley Yield, Utilization, Daily Consumption and Carrying Capacity for Swath Grazed Barley Over Four Years
| Yield | 2.9 - 3.7 | tons/ac |
| Utilization | 76 - 92 | % |
| Daily Consumption | 19 - 29 | lb/day |
| Carrying Capacity | 195 - 355 | cow-day/ac |
Carrying capacity is influenced most by yield, utilization and daily consumption.
The low end of the range for yield was due to late planting and that had the biggest impact on carrying capacity over the four years of research. So ... don’t plant too late!
Generally, the high forage quality of spring cereals and the relatively low energy requirements of beef cows in mid-gestation allows producers to limit graze with an electric wire.
The forage quality shown in Table 2 indicates that, while digestibility and NDF (affects intake) change from fall to winter, the nutritive value is more than cows require at mid-gestation. This justifies limit-grazing. A 1480 lb. cow requires about 20 lbs. of swath dry matter/day at mid-gestation and 23 lbs./day in late gestation to maintain her weight in winter.
Table 2. Change in Barley Swath Nutritive Value Over Winter
 | IVDOM | NDF | Crude Protein |
| ---------------------------- % -------------------------------- |
| Sept. | 61 | 58 | 14 |
| Nov. | 57 | 62 | 12 |
| Feb. | 54 | 62 | 12 |
IVDOM is in vitro digestible organic matter
NDF is neutral detergent fiber |
On average, our cows had a wide range in daily consumption - mostly above the limits (Table 1). The range is due mainly to management and, to a point, nutritive value. So, even under good management with an electric wire, daily consumption varied by almost 50%.
Many producers try to maximize carrying capacity by increasing utilization (reducing waste), with the understanding that their cows are consuming high quality forage, and if shorted for a day it’s no big deal. Despite what we hope for, cows won’t eat 100% of the swath. They will trample some into the ground.
In our low year (Table 1), the swath froze to the ground and the cows couldn’t apprehend the forage, so utilization dropped by about 20%.
How long we leave cows out on a swath allotment to clean up more of the swath is a dilemma. The cost to cow health and care may be larger than loss of feed. In the end that decision is up to the producer.
The loss in quality between fall and winter on the swath is relatively low (Table 2). However, there is a big change in quality from the time the cows move onto fresh swath until they are moved again (Table 3).
In fact, the nutritive value of the swath residue just before moving is between the value of straw sampled in September from the same field (Table 3) and cow minimum requirements.
Table 3. Nutritive Value of Barley Swath and Residue Before Swathing in September and Before and After Grazing in Winter
| Before Swathing
September | Winter
Nov. -- Feb. |
|
Grain & Straw | Straw | Before Grazing Swath | After Grazing Residue |
| IVDOM % | 61 | 50 | 57 | 46 |
| NDF % | 58 | 61 | 67 | 73 |
| Crude Protein % | 13 | 12 | 12 | 9 |
IVDOM is in vitro digestible organic matter
NDF is neutral detergent fibre |
Cows that are given a two to four day quantity of swath will consume a lot more on day 1 and 2 and may consume none on day 4. How much they consume will be due to ease of access, nutritive value, swath fouling and weather conditions.
If we let the cows in this study graze in September, potential intake requirements, based on quality, would be 19 lbs. for mid and 22 lbs. dry matter/day for late pregnancy cows. A small weight gain would be expected if limited grazing allowed 22 lbs./day consumption at mid-pregnancy.
Cows that grazed halfway through the grazing period (day 3 of a 4 day swath allocation), when feeding value might be close to that of straw, requirements went up to 31 to 34 lbs. dry matter/day for mid and late pregnancy cows, but potential intake was down to 23 lbs./day.
In this case weight loss would occur. Over a four day grazing period, dry matter intake would be near potential on day 1 and well below on day 4 due to the reduction in nutritive value (Table 3). Availability would also be reduced.
Leaving cows on swaths for extended periods, just to force cows to clean up swath, could be counter productive.
We’ve talked about four day swath rationing moves. Moving animals more often will help keep daily rations more stable and can help control swath losses. In fact, in harsh conditions or with cows approaching calving, daily moves would be desireable.
There are more effective ways of increasing carrying capacity than “shorting” cows to increase utilization. The most effective way is to maximize yield by planting early. Also choose species and varieties that aren’t susceptible to the late planting yield loss. This aspect of swath grazing management is now under study.
For more information contact Vern Baron, Agriculture & Agri-Food Canada, 403-782-8109; email: baronv@agr.gc.ca |
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