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Grazing Bites

It has been a very unusual spring to say the least. I don’t remember too many late Aprils, especially those ending with frosts or freezes.

Forage growth is certainly behind normal. An uncle of mine used to talk about grass being in head by the 5th of May and he usually was right. He also talked about the first of May being a good time to put the cows to pasture for the first time. It will be pushing it in most of Indiana to get there this year. Forages have have been nipped by cold weather again, and again. Cooler than normal temperatures, especially at night and cloudy days have really dampened growth. I figure that my fields are about 40 percent behind normal. I do find bluegrass heading out now. That is traditionally a good sign. What I’m not seeing is normal growth with most tall cool-season grasses or legumes.

Hay supplies are either limited or gone by now and in many cases, there is no more waiting. You may just have to graze. If you do have hay left, it won’t hurt to feed it a little longer. But if grazing must start, there are a few rules of thumb for these conditions:

First, start or continue grazing the fields or paddocks with the most growth present, ideally with a fair amount left over from last year if that is possible. The heavier amount of material will help to protect the soil and provide some “cushion” to slow down pugging where soils are wet. Keep the animals moving to avoid more damage, especially if they are in any one area for an extended period under saturated conditions. If paddocks are fairly good sized then leave them long enough to just top the growth and then move them to the next area. If you are having to graze short immature grass, also keep them moving. Multiple bites on the same plant will reduce the solar panel, and slow regrowth. Hopefully, with warmer weather predicted, we’ll get past this quickly.

It might be a good idea to make sure the cows have a belly full of hay prior to letting them out on pasture for the first time and wait until the afternoon after the grass has dried off.

Since we are still dealing with cool conditions and lush spring forage growth; this raises the possibility of grass tetany. New growth is very high in water and nitrogen. It is what we call “washy” grass. It can also be fairly high in potassium. Fields that have been fertilized with nitrogen may actually be even more imbalanced. The big problem is, these forages can easily be low in magnesium. Dr. Ron Lemenager, beef specialist at Purdue, points out that the ratio of minerals to each other is outside the acceptable range in this “washy” forage.

Pastures with a good grass-legume mix, generally at least 30 percent, are normally a little better than monocultures of grass because legumes carry more magnesium than grasses.

Having some hay available for grazing livestock to eat as dry matter along with the lush spring forage can help keep the grazing animal’s rumen in balance, but as Dr. Lemenager points out, they have to eat it. I’ve watched cows after two or three days in a lush spring field start going to fence rows looking for some dry matter. If they really are needing some dry matter and it is available, most will seek it out and consume it eventually. This dry matter early on may be from left over forage from last year, leaves off trees, and even some twigs. Grass tetany is generally more of a problem on fields that were grazed short last fall leaving very little or no dry matter behind to mix with the washy spring grass, and also in fields that have had early spring applications of nitrogen. Once the forages start catching up to where they should be for this time of the year, and start maturing more, dry matter will increase in the forage, and nutrients will be more in balance.

I asked Dr. Lemenager about supplemental feeds, specifically corn gluten and its effect on grass tetany, because I had been asked the same question several times and he said, “Adding a protein source like corn gluten might seem odd when N is already high, but it is actually adding rumen undegradable protein (RUP) and a fiber-based energy supply which can be positive from a cow’s nutrition perspective, especially lactating cows and even more so for replacement heifers that have been gaining 1.5 pounds per day all winter and now they crash on energy. Without energy (carbon chains) the soluble nitrogen cannot be efficiently incorporated into microbial protein. A problem with “washy” grass is that the rate of passage is very fast (hence manure can go through a screen door). This rapid rate of passage and lack of carbon chains is not conducive to good rumen fermentation of structural carbohydrates further aggravating the problem of energy balance. Bottom line is that feeding a dry feed like corn gluten helps slow rate of passage, provides an energy source to use the rumen degradable protein (RDP) fraction, and provides RUP and an amino acid supply to the small intestine. By itself, adding corn gluten doesn’t necessarily prevent grass tetany, but it should improve overall animal nutrition and help reduce the incidence of grass tetany.”

Feeding a high-magnesium mineral under these cool, wet, lush forage conditions is always a good practice. Lemenager recommends supplementing this mineral during times like these to make sure they are taking in enough. Magnesium is bitter and cows don’t like it, so additives are used to help improve intake. If salt is feed free choice at the same time as the high-mag mineral, they may not get enough magnesium to help prevent grass tetany.

Dr. Lemenager also commented that soybean hulls, either fed alone or as a mixture with corn gluten, would be a better choice than corn gluten alone. The hulls are less protein, but a readily fermentable fiber (no starch) providing the carbon chains to use the rumen degradable protein. He likes a 50:50 mix which runs about 17.5 percent crude protein and on a forage diet has almost the same energy value as corn without the starch that reduces rumen pH lowering fiber digestibility.

I look forward to some warm sunny days in the near future. I’ve had enough winter-like weather and I believe the animals and the plants have too. If you are lucky enough to have enough hay to get you by for a while longer until the pastures are truly ready to be grazed please consider using it. And, if you have extra, consider advertising to let neighbors know you have some to spare. There are producers all across the state that are in dire need of hay, especially in the northern half of Indiana.

Keep on grazing!

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