Management and Assessment of Ensiled Forages and High-Moisture Grain

William J. Seglar, DVM, PASa*bill.seglar@pioneer.com and Randy D. Shaver, PhD, PASb,     aGlobal Nutritional Sciences, Global Forages division, DuPont-Pioneer, Northwest 62nd Avenue, Johnston, IA 50131, USA; bDepartment of Dairy Science, University of Wisconsin, 1675 Observatory Drive, Madison, WI 53706, USA

*Corresponding author.

Various forage and grain crops are grown, harvested, and fed to dairy cattle as ensiled forages or high-moisture grains. Although the nutritional value of hybrids and varieties is influenced by genetic inheritability, the crop growing environment dictates the outcome of forage quality, affecting nutrient digestibility. How the crop is managed based on its stage of harvest maturity and dry matter, along with key ensiling management factors, also determine the nutritional quality of fermented forages and grains. Veterinary practitioners can implement silage quality evaluations as part of a nutritional consultation service to help dairy clients maximize dairy performance and efficiencies.

Keywords

Silage quality

Forage quality

Ensiled forage

Forage and grain crops

Nutritional value

Fermentation

Digestibility

Evaluation

Key points

 Forage crop options affect dairy cow performance and health.

 Environmental growing conditions, more than seed genetic selection, determines the final forage quality fed to dairy cattle.

 Forage digestibility is influenced by growing conditions and length of time in silo storage.

 Harvest and ensiling management determines success of forage fermentation process and silage feeding value.

 On-farm tests and forage laboratory samples are available for determining forage quality of ensiled forages and grains.

Forage and grain crops ensiled for dairy production

The diversity of geographies and growing environments dictate the types of ensiled forages that are used for dairy production. Feed cost represents the largest single expenditure on most livestock operations. The production of high-quality silages can help reduce the cost associated with feeding concentrates and supplements. For dairy producers, whole-plant corn, high-moisture corn, alfalfa, cereal, and a variety of grass species are the silages of most economic significance.

Specific forage crop hybrids and varieties and impact of the growing environment

Forage Production Considerations

 Decisions on forage product options based on genetic nutritional traits are important; however, environmental and management factors have the greatest influence on forage quality.

 Corn silage quality at time of harvest is primarily influenced by harvest maturity, kernel processing (PROC), theoretical length of chop, and length of storage time in silos.

 Corn offers a diversity of feeding options, which include corn silage, high-moisture shelled corn, high-moisture ear corn (HMEC), snaplage (SNAP), dry corn (DC), and stalklage.

 Legume, grass, and cereal forage quality is contingent on stage of maturity at time of harvest and wilting time to achieve proper dry matter (DM) content at time of ensiling the crop.

 Temperature and moisture are 2 environmental variables during plant growth that highly influence forage quality of corn, legumes, grass, and cereal forage crops.

Forage categories

Plants are classified as C3 and C4 carbohydrate producers, and the primary difference is within plant cells in which photosynthesis for carbon fixation events occur. C3 plants are cooler season crops that have a longer growing season and higher water demands (Table 1). In contrast, C4 plants are warm season crops that are water efficient and drought tolerant. Table 2 compares water usage requirements for several C3 with C4 crops; alfalfa is a C3 crop that has the highest water demand, whereas C4 sorghum crops use about one-third of the water required by alfalfa.1

Table 1

Characteristics of cool and warm season grasses

Cool Season Grasses (C3) Warm Season Grasses (C4) Optimal growth at cooler temperature (70°F) Optimal growth at higher temperature (95°F) More digestible and higher in crude protein Less digestible and lower in crude protein Longer growing season More drought tolerant Higher water demands More efficient at using water

Data from Teutsch C. Using mixtures of summer forages for improved forage yields in dry conditions. J Anim Sci 2013;91(E-Suppl 2)/J Dairy Sci 96(E-Suppl 1):406. [abstract 358].

Table 2

Water use in forage crops

Alfalfa (C3) 844 100 Bennett & Doss, 196363 Bromegrass (C3) 828 98 Martin et al, 197664 Wheat (C3) 505 60 Martin et al, 197664 Orchardgrass (C3) 418 50 Bennett & Doss, 196363 Sudangrass (C4) 380 45 Martin et al, 197664 Corn (C4) 372 44 Martin et al, 197664 Sorghum (C4) 271 32 Martin et al, 197664

Data from Teutsch C. Using mixtures of summer forages for improved forage yields in dry conditions. J Anim Sci 2013;91(E-Suppl 2)/J Dairy Sci 96(E-Suppl 1):406. [abstract 358].

Crop scientists monitor growth rates with calculators based on ambient temperature where using corn for example, growth starts at 7.2°C, maximizes at 22-30° C range, and ceases at 46°C. A Growing Degree Unit (GDU) calculation is used in the United States that is based on a linear relationship of growth to temperatures in the 10-30°C range. The GDU formula along with an example for corn is shown in Table 3. Using alfalfa in contrast, this crop starts growing at 5°C compared to corn at 10°C. Using the calculation for alfalfa and same daytime and night time temperature inputs as showing in the table, there would be 15.0 GDU accumulated for that day.2

Table 3

GDU calculations for corn and alfalfa

Corn [(Daily maximum temperature + daily minimum temperature)/2] - 10 [(30°C+10°C)/2] - 10 10.0 Alfalfa [(Daily maximum temperature + daily minimum temperature)/2] - 5 [(30°C+10°C)/2] - 5 15.0

Corn utilization as ensiled forage or grain

Corn is the predominant cereal crop grown throughout the world, because compared with all cereal crops, corn is unique in its ability to outyield the other crops on a ton/acre and nutrients/acre basis.2 Corn growth and development are typically categorized by a staging system that divides plant development into vegetative (before flowering) and reproductive grain development (after flowering) stages. The reproductive stages are key growth periods for capturing crop harvest opportunities intended for (1) whole-plant corn silage (WPCS), (2) high moisture ear corn (HMEC) or snaplage (SNAP), high-moisture shelled corn (HMSC), and (4) dry corn (DC). The reproductive maturity of corn is assessed by plant moisture, as shown in Table 4. WPCS is based on whole-plant moisture content, whereas high-moisture and dry grains are based on kernel moisture content.

Table 4

Corn harvest opportunities for corn silage and grain

Corn Use % Moisturea,b Plant Part Moisture Corn silage 63-68 Whole plant HMEC/SNAP 26-33
32-39 Kernel
HMEC/SNAP product High-moisture corn (HMC) 25-32 Kernel DC grain (shelled corn) <15 Kernel

a% Moisture is used by crop producers, whereas cattle producers use % DM...