Intake and nutritive value of florigraze rhizoma peanut silage for lactating dairy cows.

Florigraze rhizoma peanut (Arachis glabrata Benth.) is a very persistent, high quality legume that is well adapted to subtropical and tropical environments. This legume was ensiled and compared with corn silage (Zea mays) as a feedstuff for lactating dairy cows. Twelve Holstein cows, including 4 ruminally fistulated cows (mean, 70 days in milk), were used in an experiment with a 4 x 4 Latin square design replicated three times. Diets were formulated to contain 50% concentrate on a dry matter (DM) basis. Dietary treatments were rhizoma peanut silage and corn silage fed at DM ratios of 0:50, 20:30, 35:15, and 50:0. The dry matter intake, digestibilities of DM and crude protein, and production of milk and fat-corrected milk decreased quadratically as the percentage of legume in the diet increased. Nearly all of the decrease occurred when rhizoma peanut silage was the sole forage in the diet. The organic matter digestibility of the two forage types was similar; however, digestion of crude protein in rhizoma peanut silage was only 45% (calculated using simultaneous equations). Ruminal pH increased, and ammonia and total volatile fatty acid concentrations decreased, as the percentage of rhizoma peanut silage in the diet increased. In situ digestion rate constants for DM of rhizoma peanut silage were twice that of corn silage, but extent of DM digestion was greater for corn silage. Passage rates of concentrates and forage were unaffected by dietary treatments. Rhizoma peanut silage can replace 70% of corn silage in diets containing 50% concentrate without affecting dairy cow performance.

Prevention of leucaena toxicosis of cattle in Florida by ruminal inoculation with 3-hydroxy-4-(1H)-pyridone-degrading bacteria.

Ruminal microorganisms in cattle at a Florida agriculture research station did not have the ability to detoxify leucaena by degradation of 3-hydroxy-4(1H)-pyridone (3,4,-DHP), but a DHP isomer (2,3-DHP) was degraded in some cattle. Cattle with microorganisms that degraded 2,3-DHP were mostly Senepol cattle imported from St. Croix, US Virgin Islands, where leucaena is an indigenous species. Hereford cattle at the research station in Florida generally did not degrade 3,4-DHP or 2,3-DHP. An experiment was conducted in which a pure culture of 3,4-DHP-degrading bacteria was inoculated into Hereford cattle (with ruminal fistula) grazing leucaena. The bacteria successfully colonized the rumen of recipient cattle and persisted through the following winter when there was no leucaena in the diet.

Screening Subterranean Clover (Trifolium spp.) Germplasm for Resistance to Meloidogyne species.

This study was conducted to identify lines of subterranean clover (Trifolium spp.) with resistance to Meloidogyne arenaria (Neal, 1989) Chitwood, 1949, race 1; M. incognita (Kofoid and White, 1919) Chitwood, 1949, race 3; and M. javanica (Treub, 1885) Chitwood, 1949. A collection of 134 subterranean clover lines was evaluated and all had intermediate to high susceptibility. Root galling was negatively correlated with both seed and dry matter yields. Soil fumigation significantly reduced the nematode population in the field. Results indicate there is limited genetic resistance to root-knot nematodes among subterranean clover lines. Alternative sources of variation for this trait should be investigated.