The cell walls of alfalfa (Medicago sativa L.) are a major source of energy for both dairy and beef cattle. Despite this, little is known about composition of the cell walls. Our objective was to characterize changes in the proportion of, and cell‐wall carbohydrate and lignin composition in, stems and leaves of maturing alfalfa. Field‐grown ‘Tempo’ and ‘Spredor 2’ alfalfa (upright and semiprostrate cultivars, respectively) were sampled at weekly intervals seven times in 1981 and eight times in 1982. Sampling both years commenced approximately 1 week before early‐bud stage and was terminated when seed pods formed. Plants were divided into stem and leaf fractions before cell‐wall and in vitro digestible dry matter (IVDDM) analyses were conducted. Concentrations of IVDDM in leaves were approximately 800 g kg‐1 and changed little with maturity. Stem IVDDM declined from approximately 750 g kg‐1 before bud development to 480 g kg‐1 in 1981 and 520 g kg‐1 in 1982. The concentration of cell‐wall material (CWM) increased by nearly 60% in stems in both seasons, whereas leaf CWM increased by only 10%. The proportion of lignin in the stem CWM increased by 30% with a corresponding decrease in the neutral‐sugar fraction as the plants matured. Xylose and glucose (low digestibility) increased with maturity as a proportion of total cell wall neutral sugars while arabinose and galactose (high digestibility) decreased. Soil‐moisture deficits in 1981 seemed to increase the amount of stem cell‐wall arabinose and xylose and decrease glucose concentrations compared with 1982. This work confirms that digestibility of alfalfa decreases with maturity as a result of increased concentration of CWM in stems, decreased stem digestibility, and increased proportions of stems. Significant compositional changes in CWM in stems and little change in leaves occurred as plants matured.

Extensive protein hydrolysis after harvest and during fermentation is characteristic of forage legumes preserved as silage. Differences in proteolysis among species have been observed, but plant characteristics associated with these differences have not been well defined. This study was conducted to determine if tannins play a role in modifying N transformations associated with the preservation of forage legumes as silage. In 1987, 12 legume genotypes (representing six species) were field grown and analyzed for tannin concentrations pre‐ and post‐ensiling dry matter (DM), pH, and N forms. In 1988, 18 genotypes (representing seven species) were evaluated in a similar manner. Tannin concentrations range from 0 to 27 g tannic acid equivalents kg−1 DM in 1987 and 0 to 31 g in 1988. Dry matter concentration pH, and concentration of total N, soluble nonprotein N (SNPN), free amino acid N, and ammonia N of fresh and ensiled herbage were within the range of previous literature reports for forage legumes. The proportion of total N in the form of SNPN after 35 d ensiling ranged from 32 to 73% in 1987 and 26 to 69% in 1988 and was negatively related to tannin concentration (r2 = 0.75). Within sericea lespedeza [Lespedeza cuneata (Dum‐Cours) G. Don], the only species with substantial variation for both tannin and silage SNPN concentrations r2 values were 0.81 in 1987 and 0.88 in 1988. Red clover(Trifolium pratense L.) and cicer milkvetch( Astragalus cicer L.) did not contain measurable levels of tannins, but exhibited lower proteolysis than alfalfa (Medicago sativa L.). These results suggest that tannins play a major role in limiting proteolysis some legumes during ensiling, but other factors also are involved.

legumes, supply N (Scott et al., 1987). Many studies in the North Central USA on legume interseeding in Cropping systems that improve soil conservation are needed for established corn stands report grain yield losses that mixed grain and forage enterprises in the upper Midwest. Our objective was to determine whether established kura clover (Trifolium are attributed to moisture stress (Kurtz et al., 1952; ambiguum M. Bieb.) stands could serve as a living mulch for no-till Pendleton et al., 1957), N deficiency (Scott et al., 1987 corn (Zea mays L.) production, followed by a return to clover without Triplett, 1962), and reduced corn populations associated replanting. Treatments included corn sown into established kura clowith wider row spacing (Schaller and Larson, 1955; ver that was: (1) killed and sidedressed with N, (2) killed, (3) band- Stringfield and Thatcher, 1951). Living mulch systems killed, leaving 15 cm of untreated kura clover between rows, (4) have also been evaluated where existing forage is mansuppressed and sidedressed with N, and (5) suppressed and (6) unaged with herbicides to allow corn production. Corn treated kura clover without corn. Corn whole-plant yield in 1996 yields in such systems were equal to or greater than ranged from 14.0 to 15.7 Mg ha Ϫ1 and was greatest in Treatments 2 those in conventional corn production, but these systems and 4 and least in Treatment 5. Corn whole-plant yield in 1997 ranged were evaluated in the northeastern states, where seafrom 9.5 to16.9 Mg ha Ϫ1 and was greatest in Treatments 1 and 2 and least in Treatment 5. Grain yields in 1996 were not different among sonal precipitation is higher than in the Midwest (Entreatments, while in 1997 yields ranged from 7.2 to 11.1 Mg ha Ϫ1 and ache and Ilnicki, 1990; Mayer and Hartwig, 1986). Simiwere greatest in Treatments 1 and 2 and least in Treatment 5. Clover lar results in the North Central states have not been yield in 1997 following 1996 corn production was greatest in the achieved consistently, primarily because of the continuntreated control, but there was no clover yield difference in 1998 ued problem of competition for water, and to a lesser following either 1996 or 1997 corn production. Kura clover can be extent, light and nutrients (Eberlein et al., 1992; Echtenmanaged as a living mulch in corn with little or no corn whole-plant kamp and Moomaw, 1989).or grain yield reduction and clover will recover to full production Kura clover is a long-lived, perennial, rhizomatous within 12 mo without replanting.

Extensive degradation of protein during fermentation of high‐protein crops reduces efficiency of dietary N utilization in ruminants. Evidence suggests that enhanced levels of fermentable carbohydrates can reduce proteolysis. Our objective was to evaluate whether delaying daily cutting time, to allow total nonstructural carbohydrates (TNC) to accumulate, would inhibit protein degradation by way of greater acid production in the silo. Red clover (Trifolium pratense L.) and alfalfa (Medicago sativa L.) were harvested at 0600, 1000, 1400, and 1800 h in 1993, 1994, and 1995 and wilted to a dry matter (DM) content of 350 g kg−1 before ensiling. The level of TNC in fresh forage of both species increased throughout the day. Starch accounted for most of the daily change in TNC in fresh alfalfa, whereas in red clover, quantitative increases in sugar and starch impacted TNC similarly. Level of TNC at initiation of ensiling did not consistently affect protein degradation during fermentation as confirmed by generally insignificant correlation coefficients. The extent of proteolysis in the silo was consistently greater in alfalfa than red clover. Silage pH typically decreased and starch increased as cutting time was delayed from 0600 to 1800 h. While the extent of proteolysis was largely unaffected by inherent increases in TNC, lower silage pH and higher starch concentrations indicate that silage from the afternoon cuttings may be better preserved and higher in quality.

Soybean [Glycine max (L.) Merr.] has potential for use as an alternative forage crop, however, little is known about the effects of cultural practices on forage yield and quality. A study was conducted to evaluate the effects of cultivar, row spacing, plant density, and harvest maturity on the yield and quality of soybean forage. The study was conducted at the Univ. of Wisconsin Arlington Agricultural Research Station, Arlington, WI on a Plano silt‐loam soil (fine‐silty, mixed, mesic, Typic Argiudoll) in 1987 and 1989. The cultivars Corsoy 79, Pella, and Williams 82 were grown at 20‐ and 76‐cm row spacings at planting rates of 280 000 and 890 000 seeds ha−1 and were harvested at the R1, R3, R5, and R7 stages of development. Harvest maturity had the greatest effect on soybean forage yield and quality of the management practices evaluated. The yield of soybean forage increased from 2.4 Mg ha−1 when harvested at R1 to 7.4 Mg ha−1 when harvested at R7, but quality declined between stages R1 and R5 then increased from R5 to R7 as pods developed and seeds filled. Late maturing cultivars (Maturity Group III vs. Maturity Group II) produced greater forage yields but lower quality forage when harvested at the same stage of development. The 20‐cm row spacing produced 1.2 Mg ha−1 more forage than the 76‐cm row spacing, but crude protein concentration was 8 g kg−1 less. The results of this experiment indicate that soybean can produce forage similar in quality to alfalfa and that management practices typically used for grain production are suitable for forage production.