Research and Reviews: Beef and Sheep

Special Circular 170-99

Forage and Animal Evaluation of Heifers at Indian Lake Hydrologic Unit CRP Stocker Grazing Demonstration

S. Boyles^{+ 1}, B. W. Stol⁺, and T. L. Dobbels^++
*The Ohio State University Department of Animal Sciences
⁺Natural Resources Conservation Service
⁺⁺Ohio State University Extension, Logan County

Abstract

The objectives of this project were to monitor the performance of cattle grazed on Conservation Reserve Program (CRP) land. One 40-acre parcel that had been previously grazed for three years and a 52-acre parcel that had been grazed for one year were allocated for the 1998 grazing project. A total of 50 heifers were used in the study with 25 animals being placed in each pasture site. Cattle placed on the 40-acre parcel received four pounds of whole shelled corn per head per day during the last 60 days of the grazing period in 1998. The average daily gain was 2.2 and 2.3 lb per day for unsupplemented and grain-supplemented heifers, respectively. This lack of difference in gain is perhaps not unexpected, since there were abundant amounts of high-quality forage available.

Introduction

There are 346,050 acres of Ohio farmland enrolled in the Conservation Reserve Program (CRP) (Loux et al., 1995). As contracts approach their expiration date, participants are faced with the decision of what to do with CRP acres. Anyone wishing to participate in other USDA programs must meet Conservation Compliance provisions. Agricultural commodities cannot be produced on highly erodible land (HEL) unless soil-erosion prevention measures are initiated or installed that maintain soil loss to USDA-acceptable standards. Maintaining CRP cover and using it for pasture or hay production should meet the Conservation Compliance demands. The objectives of this project were to monitor the performance of cattle grazed on CRP land.

Materials and Methods

An intensive grazing project was initiated at the Indian Lake Water Shed Project at the farm of Russ and Miriam Forsythe near Belle Center, Ohio. The two- to five-year project will evaluate intensive grazing of cattle instead of a cropping system.

Land Description

One 40-acre parcel that had been previously grazed for three years and a 52-acre parcel that had been grazed for one year were allocated for the 1998 grazing project. Permission was granted from the Consolidated Farm Service Agency (CFSA) to conduct the experiment. The land was seeded to orchardgrass, timothy, and clover eight years ago when it went into CRP. Red clover was frost seeded in March 1995 at a rate of 10 lb per acre and again seeded on February 1, 1996, at a rate of 8.75 lbs per acre on the 40-acre parcel. On March 15, 1997, 7.6 lb of red clover and 150 lb of limestone were applied to both grazing sites. The grazing site prior to the onset of the project was mowed once a year during the time the land was in CRP. The soil was a Napponee St. Clair silt/loam with 6 to 12% slopes, which is typical of Logan County, Ohio.

Cattle placed on the 40-acre parcel received four pounds of whole shelled corn per head per day during the last 60 days of the grazing period in 1998. The whole shelled corn was fed on the ground. A plastic pipe cut in half with wooden ends was used as a feed trough. Cattle placed on the 52-acre parcel received no supplemental grain.

Fence Design

The 40-acre pasture ground was divided into four sections. Perimeter fence was high-tensile fence (5 strands, 3 electrified). Internal fence, dividing the sections, was one strand of electric fence. However, paddock A was completely enclosed in high-tensile fence for an arrival area and to acquaint cattle with the electric fence. Three sections (A, B, and C) contained 11.3 acres per section, and the fourth section (D) comprised 6.1 acres. Each section was subdivided with movable electric tape so the paddocks were 1.4 acres in size (28 cells). The cattle were moved daily in the mornings within the grazing sites.

The 52-acre pasture area consisted of six sections of 2.6, 5.7, 6.4, 7.4, 13.6, and 16.1 acres, respectively. The 52-acre grazing site had fencing and daily cattle movements similar to the 40-acre grazing site.

Water and electric were provided from a nearby barn. Black plastic pipe (0.75 inch, 200-lb test) was laid along the fence, and a portable water trough was moved to the paddock that calves were currently grazing. Calves always had access to salt and mineral supplements.

Cattle Description

An area cattle feeder supplied the cattle. The cattle were fed on a contract basis. The grazing charge was $0.25/lb of gain. Fifty heifers were used in the study with 25 animals being placed in each pasture site. Individual animal weights were recorded on June 2, 1998. The heifers averaged approximately 590 lb. Cattle were weighed approximately every 30 days during the 113-day grazing period. Cattle received a body condition score (Boyles et al., 1992) at the beginning and end of the trial. The body-condition score system used was based on a 1 through 9 scale with 1 representing very thin body condition and 9 representing very fat body condition. The cattle were individually graded (USDA, 1980) on June 2, 1998. Cattle had free-choice access to mineral supplements containing GainPro™ (Hoechst Roussel Vet) and water. All cattle were implanted with Revalor-G™ (Hoechst Roussel Vet).

Forage Nutrient Content

Forage samples were collected on weekly intervals when cattle were begun on the demonstration area. Samples were taken from a paddock just prior to the steers entering that particular grazing cell. The procedure was to walk diagonally across the field and take small samples and place the collected forage in a sealable plastic bag. The samples were frozen and then sent to the Ohio State University Research-Extension Analytical Laboratory at Wooster for analysis.

Internal Parasite Control

The deworming program involved a strategic-deworming program as prescribed by Dan Bloomberg of Hoechst Roussel Vet. Fecal samples were collected during the project and mailed to an independent parasitology laboratory for analysis.

Animal Performance

The heifers’ final individual weights were taken on September 25, 1997. The average daily gain for the heifers was 2.2 lb/day when no supplemental grain was fed (Table 1). The cattle that received four pounds of whole-shelled corn per head per day during the last 60 days of the grazing project had an average daily gain of 2.3 lb/day gain. Thus, supplemental grain did not appear to improve performance in 1998. This perhaps is not unexpected since there was an abundant amount of high-quality forage available (Tables 3 and 4).

Frame, Muscle Score, and Body Condition

Large-frame calves were 28 lb heavier than medium-frame calves at the beginning of the trial (Table 2). Large-frame calves were 40 lb heavier than medium-frame calves at the end of the grazing season. Average daily gain was 2.3 lb/day for large-frame cattle and 2.2 lb/day for medium-frame cattle. Calves with initial body condition scores of 3 and 4 had higher average daily gain than calves with body condition scores of 2 or 5. Although very thin cattle are capable of compensatory gain, they may have been limited for health reasons or a comparative lack of muscling potential. Calves with body condition scores of 5 or higher have very little opportunity to provide the cattle owner with compensatory gain.

Animal Requirements (Energy and Protein)

Protein levels ranged from 13.3 to 20.8 on a dry-matter basis (Tables 3 and 4). No differences existed between the 40-acre site that had been previously grazed and the 52-acre site that had not been grazed. Rotational grazing is keeping the forage in a vegetative state and maintaining high-protein levels. The crude-protein levels for 1998 were somewhat higher than those for 1995, 1996, and 1997. However, at no time were the cattle deficient in available protein. The high protein levels of the previous year, sometimes attaining 30% crude protein, may have been an indication of overgrazing.

Net-energy values did not change from 1995 to 1998. The net-energy values for gain are adequate for maintaining approximately 1.0 to 1.5 lb of body weight gain per day (NRC, 1984 and 1996). Average daily gain exceeded 2 lb per day in 1998. Average daily gain was 1.6 lb per day for 1997 and 1996 and 1.4 lb per day for 1995. The deworming program with Safe-Guard™, the feeding of GainPro™, and/or implanting with Revalor-G™ may have further enhanced daily gain. Another contributing factor could be that the excess protein was being converted to energy and resulting in greater body-weight gain than predicted. There was also a correlation with the decreased stocking rate every year as well.

Animal Requirements (Minerals)

In general, the forage appears to be adequate in most of the minerals required to meet the cattle requirements (Tables 3 and 4). However, supplementation of minerals could be recommended. Sodium requirements approach 600 parts per million (ppm), and the forage only supplied 39 to 197 ppm. Therefore, a source of salt (sodium chloride) should be available.

Improvements in performance may or may not occur by providing a mineral supplement; however, it is cheap insurance and well worth the cost. Next to sodium, phosphorus is the most important mineral for grazing cattle. The current phosphorus levels in the forage (0.26 to 0.38% of DM) were adequate to borderline in meeting NRC requirements (0.15 to 0.40% of dietary DM). Although phosphorus forage levels may appear to be numerically adequate, it should not be assumed that it is all actually available to the animal. Therefore, a mineral supplement fed free-choice should contain 5 to 8% phosphorus for stocker cattle (Bock et al., 1991).

Copper levels ranged from 7 to 10 parts per million (ppm). This may be borderline if suggested minimum copper levels are 10-ppm (NRC, 1996). However, the forage copper levels are actually deficient. Copper absorption can be hindered by other minerals such as the presence of high levels of molybdenum (Peterson, 1987). NRC (1996) suggests that the 10-ppm level is adequate if the diet does not exceed 0.25% sulfur and 2 ppm molybdenum. The current forage molybdenum levels were, at times, five to six times the 2 ppm level (11 ppm). It can therefore be assumed that opportunities for copper deficiency could occur if not provided in a mineral supplement. Thornton et al. (1972) observed that forage copper levels of 7 to 14 ppm were inadequate if forage molybdenum levels were 3 to 20 ppm.

Grass Tetany Potential (High Potassium)

No symptoms of grass tetany were observed in the cattle. The average magnesium content of the forage in this trial was more than 0.2% (Tables 3 and 4). Minimum needs of sheep and cattle for growth can generally be met by pastures or diets containing 0.10% magnesium, and 0.18 to 0.20% magnesium is considered necessary for lactating cows (McDowell et al., 1993). A value of K/(Ca+Mg) in excess of 2.2 has been correlated with an increase in the frequency of grass tetany (Kemp and t’Hart, 1957). It is interesting to note that over the four-year period, forage potassium levels appeared to decrease. The mineral supplement for the heifers contained 10% magnesium.

Internal Parasite Control

Low worm egg counts throughout the 1998 grazing season document the fact that the strategic deworming program provided full-season worm control. As a result, worm infection did not interfere with animal performance. Cattle with such low worm egg counts (0 to 6 eggs) do not need to be treated with a dewormer when they enter the feedlot. The animal owner could save this expense.

CRP land can initially be considered parasite-safe pasture. Because CRP land has not been grazed for years, worms are not present to infect cattle. Cattle owners will benefit from improved weight gains if they maintain control each grazing season. Pastures used during the 1998 project will have low worm contamination at the start of the 1999 grazing season.

References

Bliss, D. H. 1989. The prevalence of parasite contamination of spring pastures from cow/calf herds in Texas as determined by fecal worm egg counts. Texas Vet. Med. J. 51:18-20.

Bock, B. J., Hannah, S. M., Brazle, F. K., Corah, L. R., and Kuhl, G. L. 1991. Stocker cattle management and nutrition. Kansas State University Cooperative Extension Service. C-723.

Bosworth, S. C. 1988. Methods of measuring pasture yields. In: Pasture in the Northeast Region of the United States. Northeast Regional Agricultural Engineering Service. pp. 105-113.

Boyles, S., Flakoll, T., and Ringwall, K. 1992. Cow nutrition and body condition. North Dakota State University, NDSU Extension Service. AS-1026.

Grunes, D. L., Stout, P. R., and Bronell, J. R. 1970. Grass tetany of ruminants. Advan. Agron. 22:331-374.

Kemp, A. and t’Hart, M. L. 1957. Grass tetany in grazing milking cows. Neth. J. Agric. Sci. 5:4.

Loux, M. M., Sulc, R. M., Thomison, P., Beuerlein, J. E., and Johnson, J. 1995. Converting CRP land to cropland or pasture/hayland: Agronomic and weed control considerations. Ohio State University Extension. Extension Factsheet. AGF-024.

McDowell, L. R., Conrad, J. H., and Hembry, F. G. 1993. Minerals for grazing ruminants in tropical regions. 2nd Ed. Animal Science Dept., University of Florida.

Milner, C. and Hughes, R. E. 1968. Methods of the measurement of primary production of grassland. Blackwell Sci. Publ., Oxford, England.

NRC. 1984. Nutrient requirements of beef cattle. 6th Ed. National Academy Press. Washington, D.C.

NRC. 1996. Nutrient requirements of beef cattle. 7th Ed. National Academy Press. Washington, D.C.

Peterson, M. K. 1987. Considerations in trace mineral supplementation. Proceedings, The Range Beef Cow Symposium X. p. 121.

Thornton, I., Kershaw, G. F., and Davies, M. K. 1972. An investigation into copper deficiency in cattle in the Southern Pennines. II. Response to copper supplementation. J. Agric. Sci. Camb. 78:165.

U.S. Department of Agriculture. 1980. U.S. standards for feeder cattle. Agriculture Marketing Service. AMS-586.

Vitosh, M. L., Johnson, J. W., and Mengel, D. B. 1995. Tri-state fertilizer recommendations for corn, soybeans, wheat and alfalfa. Michigan State University Extension. E-2567.