The ins and outs of forage quality

Forages make up 45 to 95 percent of the feed that dairy animals receive on a farm. We usually think in terms of just the lactating cows. It is more difficult to think in terms of the whole herd in terms of the forage needs for the farm on an annual basis.

Forages are the single-most important feed that we feed on the farm and the most variable in quality. It is critical to the profitable success of a farm that this part of the farm operation be carefully planned and optimized.

We need to start out with the forage requirements for the animals on the farm. Replacements and dry cows for sure need grasses in their rations for optimal performance. Corn silage and alfalfa fit well with lactating cow rations. It should be added though, high-quality grasses fit as well.

This then brings us to the soil resources on the farm. Many farms do not have the soil resources to grow alfalfa. Either the soils are marginal in drainage, fertility or both. Combine this with climatic conditions that are not always conducive to optimal production of alfalfa – it then makes little sense to grow an expensive forage crop such as alfalfa. Corn silage requires cropland that has reasonable drainage and fertility.

Climate requirements are also important to provide adequate moisture and growing degree days that will allow the growth of even the short-season corns every year. It is essential to sit down with the agronomist and nutritionist together to plan a crop program that will ensure a balance of the forages needed for the herd for every year, providing enough of a margin of safety to meet the annual needs with good quality forage. This implies that in good years, there will be excess forages on hand.

Storage facilities can become a critical part of the equation. It is essential to have access to the right forages for each of the groups being fed year-round. It can be devastating to have to feed poor-quality forage right when there is a period of heavy calving. This translates into the loss of a significant amount of milk for all of the cows calving during that period. Having appropriate storage is a capital investment that needs to be done to ensure quality forage at all times for each group of animals on the farm.

The recommendation for grasses being a part of a dairy’s program is based on good research with both annual grasses such as triticale and improved varieties of perennial grasses such as endophyte-free fescues, which provide not only high yields but also top nutritional value. Grass provides first the effective fiber needed to enhance mat development in the rumen that is difficult to achieve with legumes and corn silage. Grasses actually enhance the utilization of these forages. Grasses also improve our nutrient management and equally importantly, soil organic matter and soil health and ecology. It is critical, however, that for high-producing cows, grasses with high digestibility be used.

The analysis of the forages to be fed to each of the groups on the farm is critical. It is recommended that samples be taken going into storage so that there are records of what will be available come time to feed the forage. It is also recommended that weights be taken going into storage so that it will be possible to plan for allocation of the forages to the different groups in a manner that will optimize growth and lactation.

It is also equally important to analyze the forages as they come out of storage. The critical analyses are DM, protein, NDF, lignin, 24-hour NDF digestion and in the case of corn silage, starch and 7-hour starch degradability, especially if the corn is going to be fed soon after it is placed into storage. Mineral analyses of the forages to be fed to dry cows are also critical.

We cannot afford to use book values in today’s economy. Too much money can be left on the table if we are not balancing the rations correctly. Our newest concern is starch degradability. This concern comes because of the high cost that we now pay for corn.

The highlighted areas are based on a 30 percent DM for corn silage, which is suggested as the near-optimum area for corn silage harvest. It was observed that as the DM at harvest exceeded 40 percent DM, starch digestibility decreases dramatically. It was also observed that if the corn silage was kept in storage for five to six months, starch degradability went way up. The question was asked by an economist and a farmer, given the value of the stored corn in the silo, did it make sense to delay that long before beginning to make a return on the investment. These data also demonstrate that there is a significant range in digestibility. This is not only a DM effect but also a hybrid effect. Starch Kd, percent per hour is the number that we put into our nutrition programs. We have been assuming 30 percent per hour which translates into about 80 percent of the starch being degraded in the rumen. With only a 20 percent per hour, about 65 to 70 percent of the starch is degraded in the rumen. This results in the need to increase the bypass protein in the ration, resulting in increased ration costs.

We have recently been looking at not only the overall digestibility of the NDF in the forage but also the fact that part of the fiber that is digested, digests very quickly. BMR corn silage is a good case in point. We have found that many kinds of grass, if harvested early, have a large part of the digested grass fiber that breaks down quickly in the rumen. This means that the high-producing cow can eat another meal and move to a higher level of productivity.

The new technologies, coupled with new varieties of forages and hybrids of corn silages, are allowing us to feed higher percentages of forages in our rations. This can translate into rations that are more profitable, resulting in better nutrient management and healthier cows that live longer. The importance of good forage management on the farm has moved to a new level.