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PRODUCTION PAPER

Hybrid, Maturity, and Cutting Height Interactions on Corn Forage Yield and Quality

Dep. of Crop and Soil Sci., Cornell Univ., Ithaca, NY 14853

^* Corresponding author (wjc3{at}cornell.edu).

Received for publication February 26, 2003.

	ABSTRACT

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS AND DISCUSSION CONCLUSION REFERENCES

 
Corn (Zea mays L.) hybrids may show different silage quality responses to harvest date and cutting height because hybrids differ in neutral detergent fiber (NDF) digestibility. A brown midrib, leafy, and dual-purpose hybrid were harvested at early [280 g kg^–1 dry matter (DM) content], medium (350 g kg^–1), and late (420 g kg^–1) harvest dates at 15-, 30-, and 46-cm cutting heights in 2001 and 2002 to determine optimum harvest management for each hybrid type. Most forage quality characteristics had hybrid x harvest date interactions as indicated by the 73 g kg^–1 decrease in NDF digestibility of the brown midrib compared with 20 g kg^–1 decreases of the other hybrids between the early and late harvest date. Milk per megagram, a forage quality index, declined (1523, 1487, and 1417 kg Mg^–1), but DM yields increased (13.2, 13.6, and 14.1 Mg ha^–1), so calculated milk yields were similar (20333, 20200, and 20233 kg ha^–1) at early, medium, and late harvest dates, respectively, suggesting a broad optimum DM content for harvest. The sharp decline in NDF digestibility, however, raises concern about harvesting the brown midrib hybrid above 350 g kg^–1 DM content. Calculated milk yield had a hybrid x cutting height interaction, as indicated by no change in the leafy hybrid and a 13% decrease in the brown midrib hybrid as cutting height increased from 15 to 46 cm. This suggests that an increase in cutting height may be a good management practice for the leafy hybrid but not for the brown midrib hybrid.

Abbreviations: CP, crude protein • DM, dry matter • GDD, growing degree days • HI, harvest index • IVTD, in vitro true digestibility • NDF, neutral detergent fiber • RM, relative maturity

	INTRODUCTION

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS AND DISCUSSION CONCLUSION REFERENCES

 
THE NUTRITIVE VALUE of corn forage, a function of digestibility, intake potential, and protein, improves with an increase in grain and a decrease in stover content (Coors et al., 1997). Dual-purpose hybrids differ in grain and stover content or harvest index (HI) values (Cox and Cherney, 2001; Cox et al., 1994), which contribute to forage quality differences among hybrids (Allen et al., 1991; Coors et al., 1997; Cox et al., 1994; Hunt et al., 1992). Maturity at harvest (Darby and Lauer, 2002; Ganoe and Roth, 1992; Hunt et al., 1989; Wiersma et al., 1993) and cutting height at harvest (Cummins and Burns, 1969; Curran and Posch, 2001) also affect grain and stover content and subsequent corn forage quality of dual-purpose hybrids. Dairy producers, however, are increasingly planting forage-type hybrids, such as brown midrib and leafy hybrids, which have higher stover digestibility and lower grain content compared with dual-purpose hybrids (Cox and Cherney, 2001). Such hybrids may respond differently to harvest maturity stage and cutting height management. Dairy producers require more information on the effect of hybrid type, harvest maturity stage, and cutting height interactions on the yield and quality of corn forage.

Brown midrib hybrids averaged 52 g kg^–1 greater in vitro true digestibility (IVTD) and 135 g kg^–1 greater NDF digestibility compared with mean values of about 25 hybrids in a 3-yr test in New York (Cox and Cherney, 2001). Brown midrib hybrids also had 20% less DM yields when compared with hybrids of similar relative maturity (RM) in these trials. Oba and Allen (1999), however, reported that cows produced 2.6 kg d^–1 greater milk yield when fed silage from a brown midrib hybrid vs. its normal counterpart. Leafy hybrids had similar DM yields when compared with hybrids of similar RM, the same IVTD, 35 g kg^–1 more NDF, and 30 g kg^–1 more NDF digestibility compared with mean values in the New York hybrid test (Cox and Cherney, 2001). Furthermore, Bal et al. (1998) and Ballard et al. (2001) reported that cows produced similar milk yields when fed silage from leafy and dual-purpose hybrids. Thomas et al. (2001), however, reported that cows produced 1.5 kg d^–1 more milk when fed silage from a leafy vs. a dual-purpose hybrid.

Hunt et al. (1989) reported that optimum forage yield and quality of six dual-purpose hybrids occurred at the two-thirds milk line stage of development, about 390 g kg^–1 DM content, in an irrigated study in California and Idaho. Wiersma et al. (1993) reported that four dual-purpose hybrids had maximum DM yields and IVTD concentrations and minimum NDF concentrations at the one-half milk line stage of development, about 330 g kg^–1 DM content, in a Wisconsin study. In another Wisconsin study, four dual-purpose hybrids had maximum DM yields at black layer formation, about 420 g kg^–1 DM content (Darby and Lauer, 2002). Maximum IVTD concentrations, however, occurred at about 300 g kg^–1, and minimum NDF concentrations occurred at about 350 g kg^–1 DM content. Consequently, maximum forage quality, as measured by the milk index, milk per megagram (Schwab and Shaver, 2001), and calculated milk yields occurred at about 330 and 370 g kg^–1 DM content, respectively. Darby and Lauer (2002) concluded that close-to-optimum DM yield, forage quality, and resultant milk performance indices can be obtained between 300 and 400 g kg^–1 DM content.

Cummins and Burns (1969) reported that corn forage yields decreased about 18% but that IVTD increased 60 g kg^–1 as cutting height increased from 15 to 90 cm. Harvestable digestible DM (IVTD x yield) was the same at 15-, 45-, and 90-cm cutting heights (6.0, 6.0, and 5.9 t ha^–1, respectively). Curran and Posch (2001) reported that yields of eight dual-purpose hybrids decreased 11% but that whole-plant IVTD increased 16 g kg^–1, NDF digestibility increased 8 g kg^–1, and starch concentrations increased 27 g kg^–1 as cutting height increased from 10 to 50 cm. Consequently, calculated milk yields decreased only 3.7%. Curran and Posch (2001) concluded that cutting height management can influence corn forage quality and potential animal performance.

Forage-type compared with dual-purpose hybrids may respond differently to harvest maturity stage and cutting height management because of differences in stover digestibility. The objective of this study was to examine the effect of the interactions of hybrid type, crop maturity stage at harvest, and cutting height management on the yield and quality of corn forage. The outcome of this study will help determine if a particular hybrid type has an optimum cutting height at a particular stage of crop maturity.

	MATERIALS AND METHODS

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS AND DISCUSSION CONCLUSION REFERENCES

 
Field experiments were conducted in 2001 and 2002 on a Honeoye silt loam soil (fine-loamy, mixed, mesic Glossoboric Hapludalf) at a Cornell University research farm near Aurora, NY (42°26' N, 76°26' W). The experimental site is tile-drained, and soil test values indicated a pH of 7.8 and high concentrations of P and K in each year. The experimental site, which was plowed and harrow-cultipacked in April of each year, has been in a corn–soybean [Glycine max (L.) Merr.] rotation since 1990, so corn followed soybean in each year. The experimental site received about 90 kg ha^–1 broadcast K (0–0–62) in April before plowing. Also, 90 kg ha^–1 liquid starter fertilizer, 40–61–0, was banded at planting. Cyanazine {2-[[4-chloro-6 (ethylamino)-S-triazin-2 yl] amino]-2-2 methylpropionitrile} and metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide] were applied immediately following planting for weed control. Escapes were controlled by hand weeding. At the fifth-leaf stage, 150 kg N ha^–1 was sidedressed (injected 0.1 m deep between every other row) as a 32% (wt./vol.) N solution of urea [(NH₂)₂CO] and ammonium nitrate (NH₄NO₃).

Three hybrids were planted in late April of both years with a four-row planter at 0.76-m row spacing and 86000 kernels ha^–1. Plots were thinned, if necessary, to a final plant density of 79000 plants ha^–1. The hybrids included Pioneer Brand ‘34B23’ (dual purpose), 108-d RM; Mycogen Brand ‘TMF108’ (leafy), 108-d RM; and Cargill Brand ‘F757’ (brown midrib), 114-d RM. The center two rows of each hybrid were harvested by hand at three harvest dates and three cutting heights to determine DM yield. Each hybrid was sampled for DM content (oven-drying) a couple of days before each harvest date to ensure that each hybrid approximated the intended DM content at the early (280 g kg^–1), medium (350 g kg^–1), and late (420 g kg^–1) harvest dates. 34B23 and TMF108 were harvested on the same dates in 2001 (22 August, 30 August, and 8 September) and 2002 (22 August, 29 August, and 6 September, respectively), and F757 was harvested about a week later for each respective harvest date. The DM content of 34B23 (286, 345, and 416 g kg^–1), TMF108 (300, 369, and 436 g kg^–1), and F757 (262, 328, and 389 g kg^–1) at the early, medium, and late harvest date, respectively, averaged close to the intended DM content. The DM content of individual hybrids, however, varied by ±20 g kg^–1 at each harvest date because of the difficulty in timing a harvest at a specific DM content. Wooden height gauges, 4.3 m in length, were set beside each row and used as a guide for harvesting at cutting heights of 15, 30, and 46 cm. The experimental design was a randomized complete block with four replications in a split-split plot arrangement with hybrids as main plots (12.8 by 9.1 m), harvest dates as subplots (12.8 by 3.1 m), and cutting heights as sub-subplots (4.5 by 3.1 m).

Five plants were randomly selected at harvest from each sub-subplot to estimate DM content, grain concentration, and forage quality characteristics. The five-plant sample was divided into stover and ear fractions and dried at 60°C in a forced-air dryer to constant moisture. The ears were shelled after drying to determine grain concentration, which allowed for an estimate of HI, expressed as kg grain kg total DM^–1. The five-plant stover sample was run through a hammer mill, and a 20-g sample of stover was removed for quality analysis. The 20-g stover/total stover ratio, shelling percentage, and HI values were calculated for each sample. We then removed and discarded the appropriate amount of grain and cob to approximate the original stover/cob/grain ratio in the remaining plant parts. The remaining stover, cob, and grain were then reassembled into a whole-plant sample and ground in a hammer mill. Stover and whole-plant samples were then ground separately in a Wiley mill (Thomas Scientific, Swedesboro, NJ). Whole-plant samples were then passed through a splitter and reduced to 50 g in weight. Stover and whole-plant samples were further ground separately through a cyclone mill (Udy Corp., Ft. Collins, CO) fitted with a 1-mm screen.

Whole-plant and stover samples (0.5 g each) were analyzed by wet chemistry for NDF, according to procedures by Van Soest et al. (1991), and for total N using a LECO N analyzer (LECO Corp., St. Joseph, MI) with Dumas combustion (Tate, 1994; Wiles et al., 1998). Crude protein (CP) was calculated by multiplying N by 6.25. Whole-plant and stover samples (0.25 g each) were also analyzed for IVTD according to Stage 1 of the procedure described by Marten and Barnes (1980). Samples were incubated for 48 h at 39°C in 5 mL of buffered rumen fluid containing 20 mL of the Kansas State buffer supplemented with 0.5 g L ^–1 urea. Following fermentation, residues were analyzed for NDF to determine NDF digestibility. Whole-plant samples (1.0 g) were analyzed for ash content by combustion at 510°C for 4 h. Whole-plant samples (0.1-g samples) were also analyzed for starch using the peroxidase/glucose oxidase method, based on the Trinder (1969) reaction. Starch is hydrolyzed to glucose, which reacts with oxygen, and is catalyzed by glucose-oxidase. Hydrogen peroxide is formed and reacts to create a dye that is bright pink in color. The color reaction is quantified with a spectrophotometer (Cambridge Technology, Watertown, MA), and glucose is predicted using calibration curves according to procedures developed by Setter (personal communication, 2002).

Potential milk yield indices were then estimated from the spreadsheet Milk 2000 (Schwab and Shaver, 2001). Milk per megagram (kg milk Mg^–1 corn forage), a forage quality index, was calculated from NDF, NDF digestibility, CP, ash, and starch concentrations. Milk yield (kg milk ha^–1 corn forage) was calculated as the product of milk per megagram and DM yields.

Hybrid, harvest date, and cutting height were considered fixed, and replications and years were considered random effects in the analysis of variance. Combined analyses across years and separate analyses within a year were conducted for DM yield, HI, stover and whole-plant quality characteristics, milk per megagram, and milk yield using General Linear Model (GLM) procedures of the SAS statistical software package (SAS Inst., 1993). The Bartlett test for homogeneity of variances was conducted on all variables as outlined by procedures in Anderson and McLean (1974). All stover and whole-plant quality characteristics had homogenous variances, but milk and DM yields had non-homogenous variances when tested at = 0.05 (P = 0.03). Because of the robustness of the Bartlett test (Anderson and McLean, 1974), however, we tested for nonhomogenous variances at = 0.01. Consequently, we will present the combined analyses for stover and whole-plant characteristics as well as DM and milk yields, which tested normal using the Shapiro–Wilk statistic in the PROC CAPABILITY: NORMALTEST option of SAS. We will not present the combined HI data, however, because HI tested highly significant (P = <0.001) for nonhomogenous variances. The HI values within an individual year tested normal using the Shapiro–Wilk statistic.

All effects in the combined ANOVA were considered significant at = 0.05. Fisher's protected LSD (P = 0.05) was used to separate means when main effects tested significant. Also, Fisher's protected LSD (P = 0.05) was used to separate means of harvest dates within or across hybrids and means of cutting heights within or across hybrids, when significant two-way interactions were observed, with procedures outlined by Little and Hills (1978).

	RESULTS AND DISCUSSION

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS AND DISCUSSION CONCLUSION REFERENCES

 
Weather Conditions
Although total precipitation and growing degree days (GDD) were similar, precipitation and GDD patterns differed between the 2001 and 2002 growing seasons. Monthly precipitation from May through August in 2001 consistently totaled 15 to 25 mm below normal. Monthly GDD were normal in June and 37 GDD (30–10°C system, McMaster and Wilhelm, 1997) below normal in July, so visible drought stress was not observed until mid-August, an exceptionally warm month in 2001. May and June were wet months in 2002, but monthly precipitation totaled 58 mm below normal in July and 52 mm below normal in August. Visible drought stress was observed in early August, shortly after pollination, which resulted in reduced kernel set and lower HI values in 2002 compared with 2001 (Table 1). The late-season drought stress in both years contributed to premature stover senescence. The early, medium, and late harvest dates corresponded to soft dough, late dent, and one-half milk line stages (Hunt et al., 1989) of growth, respectively, so HI values increased across harvest dates in both years.

Stover NDF of 34B23 and TMF108 increased about 30 g kg^–1 between the early and late harvest date (Table 2), which is consistent with previous studies on dual-purpose hybrids (Darby and Lauer, 2002; Hunt et al., 1989; Wiersma et al., 1993). Stover NDF of F757, however, increased 65 g kg^–1 between the medium and late harvest date. Stover NDF typically shows a linear increase with an increase in DM content (Darby and Lauer, 2002), so it is not clear why stover NDF of F757, which had the lowest DM content among hybrids at the late harvest date, increased the most.

Stover NDF digestibility of 34B23 and TMF108 decreased 20 to 30 g kg^–1 compared with 60 g kg^–1 for F757 between the medium and late harvest date (Table 3). Whole-plant NDF digestibility of 34B23 and TMF108 decreased 35 to 45 g kg^–1 compared with 87 g kg^–1 for F757 between the early and late harvest date (Table 3). Darby and Lauer (2002) reported a linear decline in cell wall digestibility from 250 to 420 g kg^–1 DM content, which they attributed to increased lignification of cell walls. Although brown midrib hybrids have low lignin concentrations, a delay in harvest to above 330 g kg^–1 DM content may result in greater relative increases in lignin concentration and NDF digestibility compared with dual-purpose and leafy hybrids. Nevertheless, stover NDF digestibility of F757 at the late harvest date averaged about 70 to 90 g kg^–1 greater than that of 34B23 and TMF108 at the early harvest date.

Stover IVTD of 34B23 and TMF108 decreased about 20 g kg^–1 compared with 53 g kg^–1 for F757 between the medium and late harvest date (Table 4). Whole-plant IVTD of 34B23 and TMF108 did not differ across harvest dates compared with a 20 g kg^–1 decrease for F757 between the medium and late harvest date. Darby and Lauer (2002) reported about a 55 g kg^–1 decline in stover and whole-plant IVTD concentrations as DM content increased from about 300 to 420 g kg^–1. Whole-plant IVTD concentrations and HI values have positive correlations in some years (Cox and Cherney, 2001; Cox et al., 1994), so the increase in HI values may have contributed to the mostly similar whole-plant IVTD across the three harvest dates, despite the decrease in stover IVTD.

Average stover CP concentrations of TMF108 (69 g kg^–1) were less than those of 34B23 (73 g kg^–1) and F757 (77 g kg^–1, Table 5). Cox and Cherney (2001) previously reported that leafy hybrids had below-average CP concentrations and brown midrib hybrids had above-average CP concentrations. Stover CP concentrations consistently decreased at each successive harvest date, which agrees with previous studies (Darby and Lauer, 2002; Wiersma et al., 1993). Whole-plant CP concentrations of TMF108 decreased 4 to 5 g kg^–1 at each successive harvest date but did not differ for F757 across harvest dates (Table 5). Whole-plant CP concentrations generally show a linear decline as DM content increases from about 250 to 420 g kg^–1 (Darby and Lauer, 2002; Wiersma et al., 1993), but Ganoe and Roth (1992) also reported a hybrid x harvest date interaction. Although stover CP concentrations increased 4 g kg^–1 as cutting height increased from 15 to 30 cm, cutting height did not affect whole-plant CP concentrations. Neylon et al. (2002) also reported only a small change in whole-plant CP of leafy hybrids as cutting height increased from 13 to 46 cm.

Harvest date did not affect calculated milk yields (Table 7). The much lower milk per megagram or forage quality offset the greater DM yield at the late harvest date, which resulted in similar milk yields across the three harvest dates. Consequently, milk yields were optimized between DM contents of about 280 and 420 g kg ^–1, which is broader than the 300 to 400 g kg ^–1 range reported by Darby and Lauer (2002). The premature senescence of the stover before completion of grain fill contributed to the broader range in DM content for optimum milk yields in this study.

Calculated milk yields had a hybrid x cutting height interaction (P = 0.054), despite the lack of interactions for milk per megagram and DM yields. Milk yields of F757 declined 13% as cutting height increased from 15 to 46 cm because DM yields declined 15% and milk per megagram increased only slightly. In contrast, milk yields of TMF108 did not differ as cutting height increased from 15 to 46 cm because DM yields decreased 7% and milk per megagram increased 9%. Milk yields of 34B23 decreased 6% as cutting height increased from 15 to 46 cm, which exceeds the 3.7% decrease in milk yields of dual-purpose hybrids reported in a previous study (Curran and Posch, 2001). The low HI values in this experiment probably contributed to the greater decline in milk yield of 34B23 because less grain results in greater DM yield reductions and less increase in milk per megagram as cutting height increases.

	CONCLUSION

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS AND DISCUSSION CONCLUSION REFERENCES

 
Forage quality characteristics of corn hybrids responded differently to timing of harvest, and calculated milk yields responded differently to cutting heights. Whole-plant NDF digestibility of 34B23 and TMF108 declined gradually, and whole-plant IVTD did not differ across harvest dates. Whole-plant NDF digestibility and IVTD of F757 did not differ between the early and medium harvest date but declined sharply at the late harvest date. Brown midrib hybrids are fed almost exclusively to early lactating (high-producing) dairy cows because their enhanced NDF digestibility allows for increased DM and energy intake, which results in increased milk yields (Oba and Allen, 1999). The sharp decline in NDF digestibility of F757 between the medium and late harvest date raises concern about the timing of harvest of brown midrib hybrids.

Calculated milk yields of TMF108, a leafy hybrid, did not differ as cutting height increased from 15 to 46 cm because the increase in milk per megagram or forage quality offset the decline in DM yields. Calculated milk yields of F757, however, decreased with an increase in cutting height because the additional removal of highly digestible stover did little to improve forage quality and further reduced the inherently low DM yields. The results from this study indicate that an increase in cutting height may be a good management practice for leafy hybrids but not for brown midrib hybrids.

	REFERENCES

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS AND DISCUSSION CONCLUSION REFERENCES

 

• Allen, M.S., K.A. O'Neil, D.G. Main, and J. Beck. 1991. Relationships among yield and quality traits of corn hybrids for silage. J. Dairy Sci. 74(Suppl.1):221(abstr.
• Anderson, V.L., and R.A. McLean. 1974. Design of experiments: A realistic approach. Dekker, New York.
• Bal, M.A., J.G. Coors, and R.D. Shaver. 1998. Influence of corn hybrid type and planting density on the nutritive value of whole plant corn silage in lactating dairy cows. J. Dairy Sci. 81(Suppl. 1):220(abstr.
• Ballard, C.S., E.D. Thomas, D.S Tsang, P. Mandebvu, C.J. Sniffen, M.I. Endres, and M.P. Carter. 2001. Effect of corn silage hybrid on dry matter yield, nutrient composition, and in vitro digestion intake by heifers and milk production by dairy cows. J. Dairy Sci. 84:442–452.[Abstract]
• Coors, J.G., K.A. Albrecht, and E.J. Burnes. 1997. Ear-fill effects on yield and quality of silage corn. Crop Sci. 37:243–247.
• Cox, W.J., and D.J. Cherney. 2001. Influence of brown midrib, leafy and transgenic hybrids on corn forage production. Agron. J. 93:790–796.[Abstract/Free Full Text]
• Cox, W.J., J.H. Cherney, D.J.R. Cherney, and W.D. Pardee. 1994. Forage quality and harvest index of corn hybrids under different growing conditions. Agron. J. 86:277–282.[Abstract/Free Full Text]
• Cummins, D.G., and R.E. Burns. 1969. Yield and quality of corn silage as influenced by harvest height. Agron. J. 61:468–470.[Abstract/Free Full Text]
• Curran, B., and J. Posch. 2001. Agronomic management of silage for yield and quality—silage cutting height. Crop Insights 10(2):1–4.
• Darby, H.M., and J.G. Lauer. 2002. Harvest date and hybrid influence on corn forage yield, quality, and preservation. Agron. J. 95:559–566.
• Ganoe, K.H., and G.W. Roth. 1992. Kernel milk line as a harvest indicator of corn silage in Pennsylvania. J. Prod. Agric. 5:519–523.
• Hunt, C.W., W. Kezar, and R. Vinande. 1989. Yield, chemical composition and ruminal fermentability of corn whole plant, ear, and stover as affected by maturity. J. Prod. Agric. 2:357–361.
• Hunt, C.W., W. Kezar, and R. Vinande. 1992. Yield, chemical composition and ruminal fermentability of corn whole plant, ear, and stover as affected by hybrid. J. Prod. Agric. 5:286–290.
• Little, T.M., and F.J. Hills. 1978. Agricultural experimentation: Design and analysis. John Wiley & Sons, New York.
• Marten, G.C., and R.F Barnes. 1980. Prediction of energy digestibility of forages with in vitro rumen fermentation and fungal enzyme systems. p. 61–128. In W.J. Pidgen et al. (ed.) Standardization of analytical methodology for feeds. Int. Dev. Res. Cent., Ottawa, ON, Canada.
• McMaster, G.S., and W.W. Wilhelm. 1997. Growing degree days: One equation, two interpretations. Agric. For. Meteorol. 87:291–300.
• Neylon, J.M., T.L. Ebling, C.C. Taylor, M.P. Lynch, M.A. Reddish, M.I. Endres, and L. Kung, Jr. 2002. The effects of height of cutting, hybrid, and stage of maturity at harvest on the nutritive value of corn silage for lactating dairy cows. J. Dairy Sci. 85(Suppl. 1):383(abstr.
• Oba, M., and M.S. Allen. 1999. Effects of brown midrib-3 mutation in corn silage on dry matter intake and productivity of high yielding dairy cows. J. Dairy Sci. 82:135–142.[Abstract]
• SAS Institute. 1993. SAS user's guide. Statistics. Version 6. 4th ed. SAS Inst., Cary, NC.
• Schwab, E.C., and R.D. Shaver. 2001. Evaluation of corn silage nutritive value using MILK 2000. p. 21–24. In Proc. Forage Prod. and Use Symp., 25th, Wisconsin Forage Counc. Annu. Meet., Eau Claire, WI. 21–22 Jan. 2001. Univ. of Wisconsin, Madison.
• Tate, D.F. 1994. Determination of nitrogen in fertilizer by combustion. Collaborative study. J. AOAC Int. 77:829–839.
• Thomas, E.D., P. Mandebvu, C.S. Ballard, C.J. Sniffen, M.P. Carter, and J. Beck. 2001. Comparison of corn silage hybrids for yield nutrient composition, in vitro digestibility and milk yield by dairy cows. J. Dairy Sci. 84:2217–2226.[Abstract]
• Trinder, P. 1969. Determination of glucose in blood using glucose oxidase with an alternative oxygen acceptor. Ann. Clin. Biochem. 6:24–27.
• Van Soest, P.J., J.B. Robertson, and B.A Lewis. 1991. Methods for dietary fiber, neutral detergent fiber, and nonstarch polysaccharides in relation to animal nutrition. J. Dairy Sci. 74:3583–3597.[Abstract]
• Wiersma, D.W., P.R. Carter, K.A. Albrecht, and J.G. Coors. 1993. Kernel milkline stage and corn forage yield, quality, and dry matter content. J. Prod. Agric. 6:94–99.
• Wiles, P.G., I.K. Gray, and R.C. Kissling. 1998. Routine analysis of proteins by Kjeldahl and Dumas methods: Review and interlaboratory study using dairy products. J. AOAC Int. 81:620–632.[Web of Science][Medline]

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