Small grain forages: How do they fit in the ration?
Our traditional forage plans are frequently disrupted by alfalfa winterkill, uncooperative weather or the need for flexibility in manure applications. Thus, we are seeing more small grain forages planted and used in our dairy rations. A few subtle nuances to feeding small grain forages should be kept in mind during ration formulation.
Starting with the soil
Soil fertility can have a minor influence on alfalfa or corn silage quality, but it can have a rather dramatic effect on the crude protein, potassium, and magnesium content of small grain forages. Sending samples to the laboratory for complete wet chemistry analysis is always a good practice.
- Crude protein: Small grain forages grown without adequate nitrogen fertility will often be 3 to 5 percentage units lower in crude protein as compared to small grain forages grown with adequate nitrogen.
- Potassium: Small grain forages can be widely variable in potassium content, ranging from 1.5% to 3.5%. This becomes important if the small grain forage will be used in the prefresh diet because the potassium content affects the dietary cation-anion difference (DCAD). If you feed anionic salts to limit hypocalcemia, a small grain forage could be a good or poor fit in the prefresh diet, depending on the potassium content.
- Magnesium: Magnesium levels in small grain forages can range from 0.10% to 0.30%, depending on soil magnesium status. Cows fed transition diets low in magnesium are more susceptible to transition tetany, which has signs similar to milk fever, but is not the same.
The energy and fiber content of small grain forages are highly variable and primarily dependent on the stage of maturity at harvest.
When small grain forages are harvested in the vegetative stages, it is not uncommon to observe forages with less than 45% neutral detergent fiber (NDF). Similarly, winter triticale and rye harvested the follow spring can have low NDF content. These can be ideal candidates for lactating cow diets.
Small grain forages harvested after seed head emergence will have NDF content similar to straw. Mature small grain forages will have NDFs greater than 60% and make desirable dry cow and heifer feed.
The “odd duck” of all small grain forages is oats planted mid- to late summer and harvested in the fall. They do not lignify to the same extent nor do they fully develop seed. As a result, we have observed fall oats with greater than 15% sugars; the lack of lignification results in extremely high NDF digestibility potential.
Control quality at harvest
We often refer to the “little rules” when putting up small grain silages – a little wetter, a little shorter, a little more packing, and with a little L. buchneri forage inoculant to help promote stability and limit spoilage at feedout.
Preferably, ensile small grain forages at 60% to 65% moisture and, because they are grasses, chop finer than alfalfa silage. Recent data suggest chopping grass forages finer may help improve dry matter intake. Because these grasses have hollow stems, they are more difficult to pack and eliminate oxygen from the silo. You may need to allow for extra packing time. Inoculants such as Crop-N-Rich Buchneri produce acetic acid in the silage, which limits the growth of spoilage bacteria and reduces subsequent spoilage and heating.
As this article shows, there’s no silver bullet when it comes to selecting, planting, harvesting and feeding a small grain forage. Quality and ideal use of these forages varies greatly based on many factors. Work closely with your nutritionist to evaluate the quality of your forages, manage your inventories, and feed the forages that work in your cropping system and are a best-fit for your different groups of animals.
This article was originally written for the September 25, 2019 issue of Hoard’s Dairyman.
Vita Plus Dairy Summit 2019 will take place December 11 & 12 in Green Bay, Wisconsin. Talk to your Vita Plus consultant for full event details and registration information. Breakout presentations include:
- Hypocalcemia: A new solution for an age-old problem | Dr. Zach Sawall, Vita Plus
- How seasonal and daily rhythms impact milk production | Dr. Kevin Harvatine, Penn State University
- True forage quality: Looking through a different lens | Pat Hoffman, Vita Plus
- Un-shrinking feed efficiency to increase dairy margins | Dr. Mike Brouk, Kansas State University
Feed quality and nutrition