PERFORMANCE OF FEEDER CATTLE OFFERED A DIET CONTAINING EARLY-BLOOM STAGE FLATPEA SILAGE

Flatpea (Lathyrus sylvestris L.) is a long-lived, stress-tolerant, per ennial legume that is generally used as a conservation cover crop. The abundant forage produced by this species is rich in protein, but it a lso contains 2,4-diaminobutyric acid (DABA), a neurotoxic nonprotein a mino acid. No signs of flatpea toxicity, however, have been reported f or cattle consuming flatpea herbage. A study was conducted to compare the performance of growing cattle (Bos taurus) fed a diet containing e arly-bloom stage flatpea silage with that of cattle fed a correspondin g diet containing alfalfa (Medicago sativa L.). In a randomized comple te block, unbalanced design with unequal replication, 52 crossbred cat tle (steers and heifers) that had not previously consumed flatpea were blocked by sex and assigned by weight to pens (four pens of steers an d three pens of heifers) of seven or eight animals each. Animals had a d libitum access to water and diets consisting of 30% (dry matter [DM] basis) legume ('Lathco' flatpea or 'Vernal' alfalfa) silage, 30% timo thy (Phleum pratense L. 'Climax') silage, and 40% grain (67% oats [Ave na sativa L.], 33% corn [Zea mays L.]) for 86 d. Alfalfa and flatpea s ilages were of similar chemical composition and in vitro organic matte r disappearance (IVOMD). Flatpea silage contained 1.1% DABA (DM basis) , which did not adversely affect intake of the diet. At the conclusion of the trial (d 86), average daily gain (ADG) was approximately 10% l ess (P < 0.05) for cattle offered the flatpea diet than for cattle off ered the alfalfa diet. Steers gained approximately 10% (P < 0.05) more than heifers, regardless of the diet. Animals offered the flatpea die t had a greater feed/gain (P > 0.10), requiring 7 to 10% more feed (on am as-fed basis) per pound of gain than animals offered the alfalfa d iet. The observed weight gains and the absence of signs of flatpea tox icity during the study suggest that flatpea could be a satisfactory su bstitute for alfalfa in diets for growing beef cattle in regions where edaphic constraints limit alfalfa production.