Linda Benedict | 5/3/2005 1:07:36 AM
As Louisiana cattle producers continue to improve their beef stocker programs, it is important that they choose the right ryegrass for their pastures. Three varieties were looked at in a research project at the LSU AgCenter Iberia Research Station – Gulf, Jackson and Marshall. Researchers in other states, particularly Alabama, have found dramatic differences among these three varieties.
Four 20-acre pastures were each subdivided into six 3.3-acre treatment paddocks. Each pasture received an annual broadcast application of glyphosate (Roundup Ultra, 1 quart per acre) in mid-August to early September. Dormant warm-season forage was removed by burning in mid-September of each year. Pastures were lightly disked and seeded with a grain drill in mid- to late-September. Within a pasture, two paddocks each were planted with Gulf, Jackson and Marshall. The seeding rate was 30 pounds per acre for each variety. Pastures were broadcast with 2,4-D plus dicamba (Weedmaster, 1 quart per acre) in December to control buttercup and other cool-season broadleaf weeds. Nitrogen fertilizer was applied in late fall (75 pounds per acre), winter (75 pounds per acre) and in mid-spring (60 pounds per acre) each year.
October-weaned Angus and Brangus steer calves were allowed to graze Alicia bermudagrass hay meadows (approximately 28 to 42 day regrowth) after weaning. In two of the three years of the study, steers were able to graze hay meadow regrowth into late fall, just before being placed on ryegrass pastures. Because of inadequate forage growth of ryegrass during the early part of the 1998-1999 grazing season, steer calves were given access to good quality hay and hand fed a daily supplement (3 pounds per steer). The supplemental ration contained ground corn (77 percent), cottonseed meal (17 percent), salt (2.5 percent), oyster shell flour (2.5 percent) and trace minerals (1 percent). Monensin (Rumensin) was added to the supplemental ration to control coccidiosis (intestinal protozoa infection). Steers had access to fresh water and mineral supplements throughout the grazing season.
Three Angus and three Brangus steers were assigned to each paddock. To extend the grazing season as long as possible, large round bales of good quality hay were placed in each treatment paddock and replenished as needed throughout the grazing season. Ryegrass pastures were grazed 131 days in 1997-1998 (Dec. 20, 1997, to April 30, 1998), 85 days in 1998-1999 (Feb. 3, 1998, to April 30, 1999) and 129 days in 1999-2000 (Dec. 21, 1999, and April 19, 2000). Paddocks were continuously stocked throughout the grazing season.
Beginning in February of each year, measurements of the amount of forage available were made three to four times (roughly monthly intervals) using a rising plate meter. The average measurement reading indicated more forage was available for grazing with Jackson and Marshall than for Gulf ryegrass paddocks.
Although initial live weights of grazing steers were not different, the mean final weights for steers grazing Jackson and Marshall ryegrass paddocks were heavier than those of steers grazing Gulf ryegrass. This difference was consistent across years. Final weights were similar for both Jackson and Marshall ryegrass paddocks.
Overall live weight gains (three-season average) were 261, 276 and 281 pounds for Gulf, Jackson and Marshall ryegrass paddocks, respectively. Live weight gain, averaged over the three seasons, was 6.5 percent higher (about 18 pounds heavier) for steers grazing either Jackson or Marshall than for steers grazing Gulf ryegrass paddocks. Live weight gains were consistently higher in each year of the study for Jackson and Marshall than for Gulf ryegrass paddocks. There was no difference in the three-season average of live weight gains between steers grazing Jackson and Marshall ryegrass paddocks.
Average daily gains, averaged over the three seasons, of steers grazing Jackson and Marshall ryegrass paddocks were 6 percent higher (.15 pounds per day difference) than those of steers grazing Gulf ryegrass paddocks. Average daily gains of steers grazing Jackson and Marshall ryegrass paddocks were similar (2.50 and 2.54 pounds, respectively). Ryegrass variety effects on average daily gains were not consistent across grazing seasons, and those differences were highest in 1997-1998 and lowest in the droughty 1999-2000 season.
Live weight gains per acre, averaged across three grazing seasons, were 6.5 percent higher (a 31-pound per acre difference) for steers grazing Jackson and Marshall ryegrass paddocks (502 and 510 pounds per acre, respectively) than for steers grazing Gulf ryegrass paddocks (475 pounds per acre). Live weight gains per acre, averaged across three grazing seasons, were similar for steers grazing Jackson and Marshall ryegrass paddocks. Live weight gain per acre differences among the ryegrass varieties were not consistent across grazing seasons. Similar to that of average daily gain, the greatest range in varietal difference (565 to 486 pounds per acre for Marshall and Gulf, respectively) was in 1997-1998 season. Varietal difference in live weight gains per acre was lowest in the droughty 1999-2000 season.
Jackson, Marshall Outperform Gulf
Alabama researchers have reported more dramatic differences of ryegrass variety effects on animal performance. While certainly not achieved in the 1998-1999 grazing season, an objective of the winter-spring beef stocker program at the Iberia Research Station was to extend the grazing period that steers are maintained on ryegrass pastures. Also, 1999 and 2000 have been particularly dry years and may have affected steer performance on the different ryegrass varieties; however, steers gained relatively well (approximately 260 to 280 pounds total gain) when averaged across all three grazing seasons. The weight gain (25 to 35 pounds) per acre by steers grazing Jackson and Marshall ryegrass paddocks compared with the steers grazing Gulf ryegrass paddocks was significant.
Assuming seed prices are about 25 cents per pound for Gulf ryegrass and 38 cents per pound for Jackson and Marshall ryegrass, the difference in seed cost, at a seeding rate of 30 pounds per acre, is $3.90. Assuming a conservative sale price of 80 cents per pound for 700-800 weight cattle, the net profit per acre with Jackson and Marshall ryegrass was $20 to $28 compared with Gulf ryegrass. On an individual steer basis, gross sale price for steers grazing Gulf, Jackson and Marshall ryegrass paddocks during the late fall, winter and spring season would be about $629, $638 and $641, respectively. Choice of ryegrass variety in a stocker program can have an economic impact for beef producers.
The Wax Company, Inc., generously supplied all ryegrass seed for each planting season. Jackson and Marshall ryegrasses are commercially available varieties marketed by the Wax Company, Inc., Amory, Miss.