Submitted to: Postharvest Biology and Technology
Publication Type: Other
Publication Acceptance Date: 7/5/1995
Publication Date: N/A
Interpretive Summary: The native grasses are known for high production efficiency with regards to both water and nutrient use. Because of this they provide summer forage in animal production systems that are based mainly on forage. This study compares the dry matter intake and dry matter digestion of two native grasses, eastern gamagrass and switchgrass, and an introduced grass, flaccidgrass. Switchgrass and flaccidgrass have been found to be high in quality. This study is the first in the southeast USA to formally evaluate the quality of gamagrass hay. The results from this study indicate that gamagrass has sufficient inherent quality and that it should be given additional consideration in dairy and beef cattle production systems.
Technical Abstract: Eastern gamagrass (Tripsacum dactyloides [L.]L.) hays were harvested May 23 when vegetative (GG-V), and 28 days later (June) when reproductive culms were developing (GG-R), and were compared. The GG-V hay was further compared with a vegetative switchgrass (Panicum virgatum L.) hay harvested May 29. The GG-R hay was also compared with a late-early-boot flaccidgrass (Pennisetum flaccidum Griseb.) hay harvested on the same day. Forages were direct-cut with a flail chopper, artificially dried (24 hours) in a forced air bulk dryer (82 degrees C), bailed after drying, stored, and without further processing fed to Suffolk wethers (Ovis aries) in a 4 x 4 latin square design. The GG-V and GG-R gamagrass hays had similar apparent dry matter digestion coefficients averaging 0.64 and were also similar to switchgrass and flaccidgrass averaging 0.64 and 0.61, respectively. All hays had similar concentrations of crude protein (100 g/kg), neutral detergent fiber (715 g/kg), acid detergent fiber (373 g/kg), hemicellulose (342 g/kg), cellulose (305 g/kg) and acid detergent lignin (58 g/kg). Dry matter intake (kg/100 kg body weight) was similar for GG-V (2.42) and GG-R (2.19) and for GG-V and switchgrass (2.27), but wethers fed GG-R had higher intake compared with flaccidgrass (1.27). Nitrogen (N) retention, as a percent of total N intake, was higher for wethers fed gamagrass (23% for GG-V and 33% for GG-R) than for either switchgrass (15%) or flaccidgrass (14%). Differences in N retention were reflected in N excreted in the urine. Eastern gamagrass shows potential as a useful perennial C4 grass for ruminant production systems.