IMPROVING THE POTENCY AND RELIABILITY OF FIBROLYTIC ENZYMES FOR ENHANCING TROPICAL FORAGE UTILIZATION BY LIVESTOCK

Although tropical/subtropical C4 grasses are the mainstay of tropical ruminant production systems in the Caribbean basin, the nutritive quality of such grasses is inherently. In addition, such grasses are seasonally available; therefore, inadequate quantities exist to meet livestock needs in the dry season. Collectively, these problems have limited the level and efficiency of animal production in the Caribbean Basin. Several producers have reduced the dry season forage deficiency by harvesting and conserving forages during their peak growth periods for feeding in the dry season. Because of the low nutritive value of the native forages, ideal methods of conservation should also aim to improve forage quality. Several chemicals such as sodium hydroxide, ammonia, and calcium hydroxide can be used to improve the nutritive value of forages but such treatments are usually hazardous, corrosive to machinery, and occasionally toxic to cattle. In contrast, many reports in the last decade have shown that enzyme treatment of livestock feeds is a safe, benign method of improving forage quality and animal performance. However, results of enzyme application to feeds and forages have been inconsistent. Furthermore, very little attention has been paid to enzyme treatment of tropical forages and feeds. In fact, we do not know of any other laboratory in the US that aims to improve tropical forage quality with fibrolytic enzymes. Our initial work in this area screened several commercial fibrolytic enzymes, identified promising candidates for improvement of tropical hays and silages, and tested them in diets of beef and dairy cattle. The enzymes improved ruminal utilization and digestibility of tropical forages but did not result in improved average daily gain or milk production in cattle. This proposal employs a logical approach and sequential experiments to develop more potent, reliable enzymes for enhancing the quality of tropical grasses and hence improving the productivity of tropical animals fed such forages. The study will identify enzymes with the greatest activity under ruminal conditions, evaluate strategies for improving their potency such as adding co-factors, varying the substrate to enzyme ratio, and strategically combining different activities, and finally test the most promising enzymes in vitro, and in dairy cows and sheep in Florida and Puerto Rico, respectively. Therefore, this study will identify optimal fibrolytic enzymes for enhancing forage quality and animal performance in the Caribbean Basin with a strategy that has been used successfully for corn silage. The study meets Goal 1 of the T-STAR Caribbean Strategic plan, which is "to provide research that maintains and enhances production of established tropical and subtropical agricultural products". Because improving tropical forage quality will reduce reliance on imported supplements that increase the net nutrient load of farms, this study also meets Goal 2 of the Strategic plan, which is "to develop agricultural practices in the tropics and subtropics that are environmentally acceptable through an agro-ecosystems approach".