Plant Persistence and Animal Performance for Continuously Stocked Alfalfa Pastures at Three Forage Allowances

Alfalfa (Medicago sativa L.) has not been well suited for pasture because of its intolerance to grazing. ‘Alfagraze’, a cultivar bred for grazing tolerance, offers potential to use alfalfa as pasture. A 3‐yr grazing study was initiated in central Georgia to investigate persistence and animal performance of ‘Apollo’ and Alfagraze alfalfa at low, medium, and high forage allowance (FA). The FA for this study were targeted at 1000, 2000, and 3000 lb dry matter (DM)/1100 lb animal unit for low, medium, and high FA, respectively. Low FA reduced stand of both cultivars (P < 0.05) after only 1 yr (low = 6.8, medium = 8.2, high = 8.8 plants/sq ft). After 2 yr, high FA paddocks averaged 8.6 plants/sq ft, while medium and low FA had decreased to 5.4 and 4.4 plants/sq ft, respectively. The difference in grazing tolerance between cultivars became evident after 2 yr of grazing, when, averaged across FA, Alfagraze had 7.3 plants/sq ft and Apollo had 5.0 plants/sq ft. After an additional year of continuous stocking, Alfagraze had approximately 150% more plants than Apollo. Persistence differences between cultivars were most evident at low FA. After 2 yr of low FA, Alfagraze had 5.5 and Apollo had 3.3 plants/sq ft. After 3 yr, Alfagraze maintained stands of 5.5 plants/sq ft, while Apollo stands decreased to 1.5 plants/sq ft. Lower FA resulted in greater bermudagrass [Cynodon dactylon (L.) Pers.] encroachment. Lower FA decreased average daily gain (ADG) in yr 1. At low FA, improved persistence of Alfagraze resulted in 0.45 lb/d higher ADG than Apollo in yr 2. The better grazing‐tolerance of Alfagraze alfalfa resulted in longer stand persistence and better animal performance. Research Question Alfalfa is a high quality forage that can produce good animal gains. Little acreage of alfalfa in the USA is grazed because of poor persistence of hay‐type cultivars. ‘Alfagraze’, a grazing‐tolerant cultivar, offers livestock producers extended productivity of alfalfa used for pastures. This study investigated persistence differences between Alfagraze and ‘Apollo’ alfalfa, as well as the effect of forage allowance (FA) on stand persistence and animal performance of steers continuously stocked on alfalfa pasture. Literature Summary High quality forage is important for profitable stockering of weaned calves. Various forages can provide this during fall, winter, and spring in the southeastern USA, but a forage is needed that will produce high animal gains in summer. Alfalfa is a high quality forage for the late spring and summer, but its use as a grazing crop has been limited because of poor persistence when grazed. Rotational stocking has been recommended for alfalfa, but even then stand life is limited because of periodic overgrazing. ‘Alfagraze’, a grazing‐tolerant cultivar with high yield potential, should provide excellent animal gains during summer and good stand persistence. Study Description A 3‐yr grazing study was conducted at the Central Georgia Branch Experiment Station near Eatonton. Alfagraze and Apollo alfalfa were planted in fall 1988, and were continuously stocked during the summers from 1989 to 1991 at either low, medium, or high FA, which averaged 1110, 2170, and 4030 lb dry matter (DM)/animal unit, respectively. The paddocks were evaluated weekly during the grazing season, and put‐and‐take stocking was used to maintain the appropriate FA. Plant counts, species composition, and animal performance were measured during each grazing season. Applied Questions Was Alfagraze more persistent than Apollo, a standard hay‐type cultivar? Under continuous stocking, the difference in grazing tolerance between cultivars was evident after 2 yr of grazing, with Alfagraze having higher plant counts than Apollo. After 3 yr, Alfagraze had 150% higher plant populations than Apollo. At low FA, Alfagraze maintained significantly higher plant populations than Apollo throughout the 3 yr of the study. Did forage allowance influence stand loss? As FA decreased, greater stand losses occurred. After 1 yr of continuous stocking, low FA resulted in lower plant populations than medium and high FA. At the end of 2 and 3 yr grazing, both low and medium FA resulted in greater stand losses than high FA. Bermudagrass opportunistically encroached as the alfalfa stands decreased. Did forage allowance influence animal performance? In yr 1, reduced FA resulted in reduced average daily gain. At high FA, average daily gain was higher than at either low or medium FA. In yr 2, reduced FA resulted in increased gain per acre. Recommendation Alfagraze stands were more persistent than Apollo under continuous stocking. Differences between cultivars were evident early in the study. When alfalfa is grazed, the grazing‐tolerant cultivar Alfagraze should result in longer stand life than hay‐type cultivars. To determine the best FA for continuous stocking, stand persistence should be considered. High FA (approximately 2500 lb DM/animal unit) will provide the longest stand life and least weed encroachment, while still producing acceptable animal performance. Rotational stocking of alfalfa should allow better forage use and reduce the potential for weed encroachment while permitting higher stocking rates.