In recent years farmers have become more specialized, with many focusing on only one or two crops (McRae et al., 1989). There is mounting evidence that this approach is neither sustainable for producers nor good for the environment (Hesterman and Thorburn, 1994). An ecological rather than a factory approach to agriculture is needed (Brown, 1989). In the future, new technologies will have to conform to the environment where they are used, not dominate it (Hildebrand, 1990). More complementary production systems need to be developed which include both crops and livestock, facilitate a more efficient nutrient cycling system, and include the option of marketing grain through livestock (Brummer, 1998). Well-planned, innovative production systems that optimize use of legumes in crop rotations, and the use of no-till seeding techniques should make procedures more profitable and sustainable (Keeney, 1989). Although many farm/ranch operations do include both crops and livestock, most research is directed at solving either a crop or livestock problem with little regard to a systems approach that evaluates crop/livestock interactions.

Wintering cows on native range grasses was widely practiced until the winters of 1867-1868 and 1889-1890 when cattlemen suffered horrendous animal losses, because of blizzards and inadequate reserve feed supplies (Young and Evans, 1984). In the Northern Great Plains, rangelands may be covered with snow for much of the winter making it difficult for cows to graze standing forage. However, the amount of harvested feeds used for wintering cows can be minimized by swath grazing (Klein, 1996). Since 1978, Canadian researchers and producers have investigated the use of various small grain crops such as oats, barley, fall rye, and winter triticale for winter swath grazing (Klein, 1994; Klein, 1996; McCartney, 1996). Barley chaff left in swaths after harvesting has also been successfully used to winter beef cows (Klein, 1994). For a variety of reasons, swath grazing has had limited use in the United States. Although there are Canadian reports that cattle can graze crop swaths through as much as 20 inches of snow (Klein, 1996), crusted snow and ice are potential problems in the Northern Great Plains.

The objectives of this research were to develop a three-year crop rotation that would minimize the use of purchased inputs such as nitrogen fertilizer and pesticides and to provide swathed forage for wintering dry gestating beef cows. Additional objectives were to use crops that could be marketed either directly and/or through cattle, and to determine the long-term effect of winter grazing on soils and subsequent crop production. This paper concentrates on forage and grain production and the winter performance of gestating beef cows rotationally grazed on triticale straw, oat/pea straw and swathed drilled corn.

A three-year integrated crop/livestock project was initiated in the spring of 1999. This research included two replicates of a three-year crop rotation consisting of oat/pea in year 1, triticale-sweet clover in year 2, and drilled corn in year 3. Drilled corn was seeded at the rate of 80,000 seeds per acre with a John Deere 750 no-till drill, to maximize the stand of forage, minimize stalk diameter, and to provide effective crop competition to reduce the need for post seeding herbicide treatment. All crop phases were present each year. The oat/pea and triticale-sweet clover crops were harvested for grain with the straw and chaff allowed to drop from the combine in a swath to facilitate winter grazing. Chaff placement in the swath was generally below the straw. The drilled corn was swathed around the first frost, in mid- to late-September. Each of the three crops were seeded in replicate 15-acre fields providing approximately 4.5 acres of each crop per field, with a 20-foot perennial grass border. All crops were seeded no-till, and 60 lb of nitrogen (N) and 10 lb of phosphorus (P) were applied per acre. On one end of each 4.5 acre crop plot, subplots were established where animal grazing was not allowed. Crop residue was removed from half of the subplot area and allowed to remain on the other half. These areas were used to determine the effect of crop residue and animal impact on soil quality and subsequent crop production. Forage dry matter yields (Figure 1) and initial crude protein (CP; Figure 2) values were determined on samples obtained at the time forages were cut (harvested).

The animal portion of the project involved wintering 4 to 6 year-old dry gestating Hereford cows, bred to calve in late March, on rotationally grazed triticale straw, oat/pea straw and swathed drilled corn. Cows were grazed on either oat/pea or triticale straw early in the winter and drilled corn late in the winter. Grazing was initiated in November and continued through mid-February each of the 3 years. The performance of cows rotationally grazed on swathed crops and crop residues were compared to cows fed swathed perennial forage (western wheatgrass), and cows fed hay in a drylot (control). Each of the 3 treatments included 2 replications of 10 cows, or 20 cows per treatment. Cows grazing the crop residue and drilled corn were also provided a daily supplement averaging 4 lbs/cow/day the first two years. In 2001-2002 cows only received 3 lb of supplement per cow per day for 45 days. The supplement consisted of a mixture of oat/pea and triticale grain that provided a 20% crude protein supplement. Grain was harvested from the fields used for winter grazing.

Cows were weighed and condition scored following an overnight stand without feed or water at the beginning and end of the experiment. Intermediate weights were taken when possible after grazing the oat/pea and triticale residue. Fresh forage was provided daily to swath grazing cows by moving a portable electric fence. Weekly samples of hay bales as well as random samples of swathed forages were collected for lab analysis through out the feeding period. All forage samples were analyzed for CP, in vitro dry matter digestibility (IVDMD), neutral detergent fiber (NDF), acid detergent fiber (ADF) and P.

The total dry matter production from drilled corn in 2001 was 16,392 lbs/acre, which was approximately double the amount from oat/pea (7,476 lbs/acre), and triticale (8,418 lbs/acre), and almost eight times as much as the production from perennial grass (2,156 lbs/acre). Forage dry matter production, not including the triticale and oat/pea grain, is shown in Figure 1. Concentrations of CP at harvest for the oat/pea and triticale residue and the corn at the time it was swathed (Figure 2) were below CP requirements for dry cows (Table 1). However, these were essentially whole plant samples, minus the harvested grain, but when cows grazed these forages they selected a higher quality diet, which contained more of the higher quality chaff and corn leaves and less of the low quality straw and corn stalks. Oat/pea and triticale grain yields in 2001 were 2,848 and 3,032 lbs/acre, respectively (Figure 3). Oat/pea and triticale grain crude protein concentrations are shown in Figure 4. Crude protein for forage (Figure 2) and grain (Figure 4) are for the year 2000 because lab analyses have not been completed on comparable samples for 2001, but we do not expect CP values to differ greatly between years.

Beef cow nutrient requirements for non-lactating cows and for cows just after calving (Table 1) show that mid-gestation requirements are quite modest and could be met with rather low quality forages, but nutrient requirements escalate substantially after calving. One of our objectives was to reduce cow wintering costs by feeding swathed forages to take advantage of the relatively low dry cow nutrient requirements.

Cow weight gains during the third year (2001-2002) of our research show that for the first 43 days when cows on the swathed crops treatment were grazing swathed triticale and swathed oat/pea crop residue they lost weight despite some supplementation (Table 2). Cow nutrient requirements are usually lowest during this period (Table 1). However, during the last 61 days, when cows on the swathed crop treatment were grazing swathed drilled corn they gained more weight than control cows or cows grazing swathed grass. Cow nutrient requirements are usually higher during this period (Table 1). Over the full 104 days there was not a significant difference in weight gains among treatments even though cows on the control treatment had numerically higher weight gains. Cow condition scores are the best means of estimating body fat stores that could be used to moderate winter nutrient requirements. Condition scores for 2001-2002 were initially around 5.4-5.5 and did not differ significantly during the winter period (Table 3). However, condition scores did drop slightly for cows grazing swathed grass, with cows on this treatment also gaining the least weight.

Concentrations of CP, IVDMD, NDF, ADF and P for hay, swathed forages and grain used in 2001-2002 are shown in Table 4. By comparing IVDMD, ADF and NDF in the swathed triticale and oat/pea residue to the swathed corn it is easy to see why cows grazing the crop residue lost weight at the beginning of the winter and then gained weight during the last 61 days when they were grazing swathed corn. Cows were fed the best feed during the latter part of the winter to more nearly match their requirements as shown in Table 1.

Over the three years, the performance of cows grazing swathed crops or perennial grass has been comparable to control cows fed hay. This suggests that dry gestating cows can be successfully wintered on swathed forages, if they are properly managed and supplemented. Cows will graze swaths through several inches of snow (Figure 5), but crusting and icing can be a problem which may necessitate a mechanical treatment, such as ripping swaths open with a front end loader or snow blade, to increase forage accessability. Advantages of swath grazing include lower winter feed costs, and minimal manure disposal problems.

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McCartney, D. 1996. Research Summary of swath grazing. Western Forage/Beef Group, Agriculture and Agri-Food Canada, Lacombe, Alberta.

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We wish to thank Charles Flakker, Justin Hartel, Marvin Hatzenbuhler and Curtis Klein for technical assistance with crop production and animal care and Gary Brucker and Becky Wald for chemical analysis of forage samples.

North Dakota Extension Bulletin 74, February 2000. Adapted from Nutrient Requirements of Beef Cattle, National Research Council 1996.