The best place to begin your selection process for a corn silage hybrid is by talking to your trusted seed company agronomist and sales professional. They have observed their hybrids (and competitors' hybrids) in many more plots across multiple growing conditions than is possible with observations by individual growers. This local experience is more valuable in positioning the correct hybrid than catalog scores or descriptions pooled across growing environments that may not reflect local conditions.
That said, no discussion with local experts is complete without considering these eight points, whether you’re selecting a brown midrib (BMR) hybrid or a conventional silage hybrid.
Fiber digestibility. While small differences in
- Maturity. Hybrid maturity ratings help growers manage agronomic risk and spread harvest timing. Hybrids are typically given an overall grain comparative relative maturity (CRM), silage CRM (if the company promotes the hybrid for silage), a silking CRM and a physiological CRM (black-layer or zero milk line). What often is misunderstood by growers is that there is no industry standard for these ratings so comparing hybrids between companies is difficult. Grain and silage growing degree units (GDUs) are probably the best overall indicator to determine if a hybrid can mature for silage or grain harvest based on comparisons with long-term GDU accumulation records for the local area. Hybrids within the same genetic family but containing different technology traits often are assigned the same maturity. However, depending on the level of insect infestation, these hybrids may differ by 2-3 days in maturity. For example, a hybrid with corn borer and rootworm resistance traits is likely to be healthier and, therefore, mature faster under heavy insect infestation compared to the same base genetics lacking these technology traits.
- Silking CRM. It is prudent to reduce agronomic risk by spreading the pollination period between hybrids. Selecting hybrids with different grain or silage CRM ratings may not always provide the desired effect because they could both have similar GDUs to silking. It is best to consult GDU to silk ratings to see the relative difference in timing of pollen shed and silk emergence.
- Technology traits. Different growing regions have differing needs for technology traits, such as corn borer or rootworm resistance. Crop rotation also plays a role for technology needs. It is best to consult your local agronomist and sales professional to get their input on technology needs in your area.
- Agronomic traits. Consider such factors as stress emergence, adaptability to high populations and drought tolerance. Grain traits — such as stalk strength, test weight or grain drydown — need not be considered for silage hybrids.
- Disease package. Just like technology traits, be sure to discuss the need for specific disease tolerance, such as foliar diseases (e.g., northern corn leaf blight and Goss’s wilt) and ear rots (e.g., Fusarium, Gibberella and Diplodia).
For the next three silage-specific traits, be sure to ask your seed sales professional for absolute values for tonnage, starch content and fiber digestibility rather than catalog scores (e.g., 1=poor, 9=excellent). Local growing conditions greatly affect these values from individual fields. However, the relative comparison between hybrids is useful data for your nutritionist to review.
- Whole plant dry matter yield (tonnage). This trait is strongly influenced by plant population, plant height at the ear and starch (grain) content. Be sure to compare apples to apples and that yield values are presented at similar dry matter (DM) contents (typically either 35% DM or 30% DM).
- Starch content. Starch is the most important factor contributing to the energy density of corn silage. Research has clearly shown that there are no significant differences in kernel texture or starch digestibility among hybrids when harvested for silage when kernels are pre-black layer maturity.
- Fiber digestibility. While small differences in : fiber digestibility do exist among conventional silage hybrids, the biggest influencer is the plant’s growing environment during the vegetative stage. Research has shown that growing environment is three times more influential on fiber digestibility than seed genetics. This is why BMR hybrids have been commercialized. There is simply not the genetic variation in non-BMR hybrids to significantly increase fiber digestibility values. Also, when evaluating fiber digestibility between companies, be sure you note the incubation time (24, 30 or 48 hours) when comparing absolute values.
The foregoing is provided for informational purposes only. Please consult with your nutritionist or veterinarian for suggestions specific to your operation. Product performance is variable and subject to a variety of environmental, disease, and pest pressures. Individual results may vary.