Meet “Verl” and “Chet,” two new forage-grass varieties engineered to provide year-round grazing developed by Agricultural Research Service scientists at the Southern Plains Range Research Station in Woodward, OK. Both varieties were released in cooperation with the Oklahoma Agricultural Experiment Station and USDA's Natural Resource Conservation Service.
Researchers set out to develop both warm- and cool-season grasses for livestock to graze year-round by increasing seed and forage production, persistence, and quality within grazing systems. Grasses also needed to have longevity on highly erodible lands and complement native rangeland.
The area's extended dry periods, insects and diseases provided a formidable challenge for development. Researchers began by working with their existing foundation: two warm-season grass species, eastern gamagrass (Tripsacum dactyloides) and sand bluestem (Andropogon hallii), and a cool-season variety, Texas bluegrass (Poa arachnifera). All are native to the Southern Plains, but each has its own drawbacks.
In 2005, researchers released a new eastern gamagrass called “Verl,” the first gamagrass released from a hybrid breeding program. In field trials, Verl equaled or surpassed standards set by a highly productive gamagrass called “Pete,” (released in 1988). Verl's forage dry matter yield was on an average 11% greater than Pete's when tested in Kansas, Oklahoma, Texas, Mississippi, Florida and New York. In an experiment conducted at Woodward, the Verl variety produced 45% more seed than Pete.
Sand bluestem, lauded for its forage palatability, high yield and positive ecological impact, also has a new variety called “Chet.” Dry matter yield was almost 9% greater for Chet than that of a key sand bluestem variety called “Woodward” (developed during the 1950s). In addition, the Chet variety produced growth of about 2.5 lbs./day on stocker cattle over a 62-day grazing period.
Researchers are continuing their work with bluegrass to develop a perennial, cool-season forage grass that's economical, environmentally friendly and a sustainable alternative to wheat as a cool-season forage.
— ARS Research Report, February 2008
Heifers developed to 50 or 55% of mature body weight had similar reproductive performance compared to heifers developed to traditional recommendations (60-65% of mature body weight), researchers at the University of Nebraska West Central Research and Extension Center in North Platte say.
Two experiments evaluated prebreeding target body weight and progestin exposure for heifers developed lighter than traditional recommendations.
Experiment 1 evaluated the effects of the system on heifer performance through subsequent calving and rebreeding over three years. A total of 119 heifers (505 lbs.) were randomly assigned to be developed to 55% of mature body weight (660 lbs.) before a 45-day breeding season (intensive, INT). Another 142 heifers were assigned and developed to 50% of mature bodyweight (600 lbs.) before a 60-day breeding season (relaxed, RLX).
Prebreeding and pregnancy diagnosis body weight were greater for INT than RLX heifers. Overall pregnancy rate did not differ (88.4%), but RLX heifers had later calving dates (7 days) and lighter calf-weaning weights (428 lbs. ± 9 lbs. vs. 439 lbs. ± 9 lbs.) compared with INT heifers.
Calf birth weight, calving difficulty, second-calf conception rates and two-year-old retention rate did not differ between systems. Cost per pregnant two-year-old cow was less for the RLX than the INT heifer-development system. Of the heifers that failed to become pregnant, a greater proportion of heifers in the RLX than in the INT system were prepubertal when breeding season began.
A second two-year experiment evaluated melengestrol acetate (MGA, 0.5 mg/day) as a means of hastening puberty in heifers developed to 50% of mature body weight. Heifers were randomly assigned to the control (n = 103) or MGA (n = 81) treatment for 14 days and were placed with bulls 13 days later for 45 days. Prebreeding and pregnancy diagnosis for body weight were similar (617 lbs. and 838 lbs., respectively) for heifers in the control and MGA treatments. The proportion of heifers pubertal before breeding (74%), pregnancy rate (90%), calving date, calf weaning weight and second breeding season pregnancy rate (92%) were similar between treatments.
Researchers conclude that developing heifers to 50 or 55% of mature body weight resulted in similar overall pregnancy rates, and supplementing the diets of heifers to 50% of mature body weight with MGA before breeding did not improve reproductive performance.
— Martin, et al, 2008, Journal of Animal Science, 86:451.