Relay Intercropping Winter Cover Crop Effects on Spring Forage Potential of Sweet Maize Stover and Yearling Cattle Beef Performance.

Small landholders who grow sweet maize for the fresh produce market often also have cattle with little access to winter forage. Grazing cover crops with sweet maize stover can potentially increase the available nutritive value. A 3-year randomized complete block study with three replicates at New Mexico State University's Alcalde Sustainable Agriculture Science Center compared sweet maize (Zea mays var. rugosa) with sweet maize relay intercropped at the V7−9 stage with cereal rye (rye: Secale cereale L.) or hairy vetch (vetch: Vicia villosa Roth) for early spring grazing. Intercropping the rye or hairy vetch into sweet maize did not influence the sweet maize stover biomass yield or nutritive value after the winter. The dry matter (DM) yield and crude protein (CP) concentration of hairy vetch biomass was greater (p < 0.01) than rye biomass (1.46 vs. 2.94 Mg DM ha−1 for rye and hairy vetch, respectively, and 145 vs. 193 g CP kg−1 for rye and hairy vetch, respectively). Average daily gains by yearling cattle were not different when grazing maize−rye or maize−vetch. Producers should consider the spring planting timing of the primary crop and the initiation of grazing in the winter or the spring to maximize the utilization of the previous crop's residue (stover), as well as the cover crop itself.

Determination of methylglyoxal in ruminal fluid by high-performance liquid chromatography using fluorometric detection.

There is no reported method for the quantification of methylglyoxal in ruminal fluid. The method reported here is based on the conversion of methylglyoxal to 6-methylpterin, followed by quantification of the resulting pteridinic compound by fluormetric detection using liquid chromatography. Ruminal fluid was collected and preserved with 1 M HCl at -20 degrees C. Cation exchange prior to derivatization was used to eliminate possible interfering peaks. The detection limit of 0.125 microg/mL was calculated. The recoveries were >80%, and the coefficients of variation were <15%. This method has proven to be rugged and accurate for the detection of methylglyoxal concentration in ruminal fluid collected from cows fed diets deficient in degradable intake protein as a marker. Methylglyoxal is produced by ruminal bacteria in response to low nitrogen levels in the rumen. The ruminal methylglyoxal concentration has the potential to be a useful marker to assess ruminal nitrogen status to aid in more accurate diet formulation.