University of Nebraska Cooperative Extension MP 76-A

Summary

Two-year forage trials showed higher dry matter yields for winter triticale than for winter wheat while forage qualities were similar. Likewise, a spring triticale cultivar had higher dry matter yields than spring barley or oat cultivars when harvested for forage after heading, and forage qualities were similar. In summer trials, dryland forage sorghum and sorghum x sudangrass hybrids had higher crude protein, digestibility and energy values than irrigated forages because they were not as mature. Lower lignin content and higher digestibility resulted when the brown midrib trait was present in forage sorghum or sorghum x sudangrass hybrids.

Introduction

Data are limited on the forage production and quality potential for currently available annual forages. Changes in production potential and feed quality have occurred, such as lower lignin content and higher digestibility associated with the brown midrib (BMR) trait that has been crossed into some forage sorghum, sudangrass, sorghum x sudangrass and corn hybrids. Forage trials were conducted over two years to compare some of the newer forage cultivars with some that have been around long enough to be considered standards. Forage production and quality were evaluated for cereal forages grown under dryland management and for sorghum, sorghum x sudangrass, and pearl millet forages grown under dryland or irrigated management systems.

Procedure

Dryland winter wheat and triticale cultivars were harvested for forage at Mead, McCook, and Sidney in 1997 and 1998 after producing a seed head. Ten wheat cultivars were planted, including Arapahoe, Lamar, Longhorn, Pronghorn and six experimental cultivars. Five triticale cultivars were planted, including Trical, Newcale, and three experimental cultivars. There were four replications of each cultivar at each location.

Dryland spring seeded cereal crops were harvested as forage at Sidney in 1998 and 1999 after most of the cultivars had produced a seed head. There were two triticale, two barley, and three oat cultivars with four replications of each cultivar. All annual forages were planted in six row plots with a double disc grain drill with 12 in between rows. All forage plots were harvested with a plot swather that cut the center four rows. Mechanical chopping of the forages allowed subsampling for dry matter and forage quality analyses. Quality results were available from 1998 trials only at the time this paper was prepared.

Summer dryland forages were planted at Sidney and included one sudangrass, six sorghum x sudangrass, and eight forage sorghum cultivars. Forages were harvested after the majority of cultivars had headed in growing seasons of 78 and 75 days in 1998 and 1999, respectively. The plots were fertilized with 60 lb of N and 40 lb of P₂O₅ in 1998 and 45 lb of N in 1999.

Summer irrigated forages planted at Scottsbluff included one sudangrass, five sorghum x sudangrass, nine forage sorghum, and three pearl millet cultivars. The plots were harvested after the majority of cultivars had produced a seed head in growing seasons of 82 and 88 days in 1998 and 1999, respectively. They were fertilized with 120 of N and 80 lb of P₂O₅ as a side dress in both years.

Forage quality tests included percentages of dry matter for total and nitrate nitrogen, neutral detergent fiber, acid detergent fiber, acid detergent lignin and in vitro dry matter digestibility (IVDMD). The acid detergent fiber (ADF) values were used to calculate energy values as TDN, net energy and metabolizable energy by using equations listed by the National Forage Testing Association. Least significant differences at the 5% probability level of incorrectly stating a difference were determined for each trait by using the general linear model in the Statistical Analysis Services computer program.

Results

Fall and spring seeded cereal forage results are shown in Table 1. Averages are shown for the 10 winter wheat and 5 triticale cultivars harvested at each location in 1997 and 1998. Although differences in dry matter forage yields were not large, the top yielding winter wheat cultivar at all three locations was Pronghorn, and the top yielding winter triticale cultivar at McCook and Sidney was Newcale. Both of these cultivars were developed by plant breeders in the University of Nebraska system. Forage crude protein (CP) and ADF levels were similar among the wheat and triticale cultivars at each location, making energy levels calculated from ADF similar also.

The top yielding spring cereal forage was triticale cultivar 2700. The barley cultivars ranked second and third in dry matter yields. Forage CP levels were similar with an average of 8.7% of dry matter. Energy levels were also similar with an average of 65% TDN, which was the same as in the winter forages.

Dry matter yields for dryland summer forages in Table 2 are an average of trials in 1998 and 1999. Dry matter percentages, plant heights and maturity scores are not shown, but were similar between years. Crude protein levels for 1998 ranged from 13 to 9.4% of dry matter, which was consistent with the maturity stages that ranged from boot to headed. Producers who want summer forage high in crude protein and digestibility should harvest crops more than once a season when the crops have regrowth capability. Other producers may want more dry matter yield with a single cut system when the crude protein and TDN contents are adequate for the animals that will consume the forage.

Dry matter yields for irrigated summer forages are shown in Table 3 as an average of 1998 and 1999 trials. In Tables 2 and 3, cultivars with an X before or after numbers or a name were experimental cultivars in the years of these trials. High yielding cultivars included both forage sorghum and sorghum x sudangrass hybrids. Some brown midrib hybrids had good yields but showed some lodging in the single harvest system that allowed them to grow 6 to 7 ft tall, but this was also true for some non-BMR hybrids.

Forage quality results shown for 1998 indicate variation in CP and IVDMD, which often is due to maturity differences when harvested. However, the emergence of summer forages with increased digestibility, such as the brown midrib cultivars in forage sorghum, sorghum x sudangrass, pearl millet and corn hybrids, brings new opportunities for improved animal performance through grazing or feeding of these forages. Reduced lignin fiber content of these forages allows for greater digestibility, but multiple harvest or grazing systems may be needed to minimize lodging problems that can occur if they get too tall. In both the irrigated and dryland trials in 1998, the highest IVDMD values were associated with the lowest acid detergent lignin percentages which are typical for many BMR hybrids.

Nitrate nitrogen levels in Tables 2 and 3 were generally below the 2000 ppm level often listed for initial toxicity concern for ruminants. However, previous research with similar forages in western Nebraska showed some potentially toxic nitrate levels in irrigated forage in the first of two harvests during the summer, especially with high nitrogen fertility in the soil. Thus, nitrogen application rates will need to be managed carefully along with maturity stage at harvest to achieve satisfactory levels of CP without increasing nitrates to toxic levels.

The choice of an annual forage crop and cultivar may depend more on the time forage is needed in the grazing or harvested forage system rather than on differences in yield potential. Fitting a forage crop into a cropping system would be an important consideration. Also, equipment requirements for the shorter annuals, like small grain or foxtail millet forages, may already be in an operation for other hay crops, whereas equipment needed to easily harvest and feed the taller forages may be unique. Getting the thicker stemmed forages to dry down in a reasonable time period for making hay will usually require a crimping action of the forage during cutting. The emergence of hybrids with higher digestibility may enhance grazing of standing or windrowed summer annual forages during the winter.

Issued in furtherance of Cooperative Extension work, Acts of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture. Elbert C. Dickey, Director of Cooperative Extension, University of Nebraska, Institute of Agriculture and Natural Resources.

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