– Rory Lewandowski, OSU Extension Educator, Agriculture and Natural Resources
Although much has been said and written about the high cost of producing hay, it doesn’t appear that beef cattle farmers are going to give up the practice of making and using hay on the farm anytime soon. Therefore, I want to propose that hay be looked at as a tool. Think of it as a tool that is used to manage important resources on the cattle farm. Those important resources are cows and pasture. In hay’s role as a tool, it should be used to provide nutrients to the cow and to protect the pasture base. Let’s take a closer look at each of these uses and how they can work together within a production system.
Cows require that nutrients be provided at specified levels to insure that they are productive. In the case of a cow/calf farmer, productive means that the cow is able to conceive, carry a calf to birth, and then raise that calf until it is weaned. In order for hay to be an effective tool it must provide a sufficient quantity of nutrients as determined by the cow’s production stage. In the beef cattle business crude protein (CP) and total digestible nutrients (TDN) are often used to describe cattle nutrient needs and to describe forage quality.
The National Research Council (NRC) has tables that list the nutrient requirements of cattle at various mature body weights and production stages. Although it is common to talk about these requirements in terms of the percent CP and percent TDN of the ration, livestock actually need to consume a specified amount or weight of nutrients. In other words, the animal has to eat a certain amount of a feedstuff that contains the given percentage in order to get the needed pounds of a nutrient. When hay is fed, it is generally assumed that the cow will eat a certain percent of her body weight and if the nutrient percentage is adequate, then she will get an adequate quantity of nutrients. Usually this works out, but not always, as we shall see.
At this point in the fall of the year, most of our spring calving herds have cows that are in a mid-gestation stage of production. There are probably some mid-gestation replacement heifers in the herd. If we use, as an example, cows with a mature body weight of 1300 lbs, then the nutrient requirements of these livestock classes, taken from the 1996 NRC for beef cattle are shown in the following table:
|Production stage||CP %||CP lbs||TDN %||TDN lbs|
|Dry, mid-gestation 1300 lb cow||6.7||1.62-1.65||47||11.4|
heifer (915-920 lbs)
How will the cattle farmer know if his/her hay is meeting these nutrient requirements? A properly done forage analysis will provide the best source of information. The value of the information provided by a forage analysis is directly related to how the forage sample is gathered. Hay should be grouped into lots according to species composition and date. Each lot of hay should be sampled separately. For example, grass hay made in early June is a separate lot compared to grass/clover hay made in early June or grass hay made in late June. Within a lot of hay, sample at least 12-15 bales (more is better) using a hay probe core sampler. There is a hay probe that can be borrowed from many Ohio County Extension offices.
Here are examples of two hay quality tests: a first cut grass hay with a CP level of 7.0% and a TDN value of 50% and a second cutting grass hay with a CP value of 12% and a TDN of 62%. How does this hay match up with the nutrient needs of mid-gestation cattle? How is this hay most effectively used? Dry Matter Intake (DMI) as a percentage of the animal’s body weight is influenced by forage quality. Low quality forages have a slower rate of digestion and passage through the digestive system so intake is decreased. According to a Kansas State University publication entitled “Beef Cow Nutrition Guide“, a dry cow will eat 1.5 to 1.8% of her body weight on a dry matter (DM) basis with a low quality forage, 2.0 to 2.2% with a average quality forage and 2.5% with a high quality forage. Of course, using general terms such as low, average and high quality is not very definitive and one person’s definition of those terms could differ from another person’s definition. Using these figures, our example 1300 lb cow would consume about 23 lbs DM of what I will call the low quality first cutting hay sample and around 27 lbs of DM of the average quality second cutting hay sample.
The next step is to use the forage quality analysis, and the expected dry matter intake (DMI) to determine how nutrient needs are being met. If we look at our first cutting hay nutrient analysis and then at the NRC chart for CP and TDN percentages it appears we are exceeding our mid-gestation cow requirements. However, when the 23 lb DMI figure is multiplied by our first cutting CP and TDN percentages, we find that the cow will be consuming 1.61 lbs of CP/day and 11.5 lbs of TDN/day. This just meets the requirement. The point here is that actual intake plays a big role in how animal nutrient needs are met. If the cow consumes this forage at 2.0% of body weight DMI, then requirements are exceeded. While nutrient percentages provide a convenient guideline, the bottom line is intake.
If we take this a step further and use the second cutting average quality hay analysis and a DMI of 27 lbs, the mid-gestation cow will consume 3.24 lbs of CP/day and 16.74 lbs of TDN/day. This greatly exceeds her nutrient requirements. The point here is that we could not expect the dry cow to voluntarily limit her consumption of better quality forage once her needs are met. Once again, it is about intake. It is the job of the cattle manager to limit feed hay, especially if hay is in scarce supply, in this situation.
Now consider the mid-gestation heifer and our hay supply. The total daily pounds of CP and TDN required in the diet are very similar to the dry, mature mid-gestation cow. The difference is that the heifer has not attained her full mature weight. She has a growth requirement. She will consume forage at a similar percentage of her body weight as compared to the mature animal but given her lower body weight, total pounds of DMI will be less. It is clear that the low quality first cutting hay in our example will fall short of meeting the nutrient requirements. The only way to make up the difference is with a more nutrient dense (higher quality) feedstuff. For example, if our pregnant heifer weighs 915 pounds and is provided with our average quality second cutting hay, we can expect a DMI at about 2.0% of her body weight or 18.3 lbs. Multiply that figure by the hay analysis (12% CP, 62% TDN) to calculate a daily intake of 2.2 lbs of CP and 11.3 lbs of TDN. This exceeds the CP requirement and is just slightly below the TDN requirement.
Based on the NRC percentage requirements for CP and TDN, it looked like this hay should have easily exceeded requirements. It depends upon the level of intake. Of course, it’s very possible this heifer might consume more than 2.0% DMI. In that case both CP and TDN requirements could be exceeded. Managers should expect to monitor body condition to determine if intake and nutrient requirements are being met.
The lesson here is that if hay is to be an effective tool at providing nutrients to cows, it must be matched to their nutrient needs. This means the cattle farmer has to match hay quality to stage of production. In our example, first cutting hay fed in late gestation will not be effective because it will fall short of meeting nutrient requirements. Fed at this time, it means the farmer must spend additional dollars and provide a supplement to meet the shortfall in nutrients.
I now want to consider how hay can be used as a tool to protect the pasture base. Pasture is an important resource in the cow/calf operation. It provides the lowest cost, lowest labor system of feeding and growing cattle. It is a resource that should be well managed and protected. Unfortunately, if cattle are allowed to continue to graze pastures under drought or very wet conditions, this resource can be damaged. The most dramatic example is soggy winter pastures with our 1300 lb cows churning the sod base in to mud.
There is a cost to restore these damaged pastures whether they are allowed to recover on their own or if the farmer steps in to renovate the pasture. The cost can be measured in terms of lost grazing days, less forage tonnage produced and lower forage quality if weeds invade. Re-seeding the area with improved pasture seed can speed up the recovery process but there is the added cost of seed and equipment. Overgrazing damage to pastures during times of severe drought and tearing up the sod base during soggy periods can be minimized by use of hay.
During either times of severe drought or soggy pastures, hay can be used as a tool to protect this resource base. Hay is not just for winter use. Cows should either be moved to a sacrifice area and fed hay or moved into an area with a heavy use pad and fed hay. Once weather conditions have improved, cows can go back to the pasture paddocks.
Most beef cattle farmers are going to make and feed hay. Thinking about the use of hay as a tool might help farmers make better management decisions regarding cattle nutrition and pasture management.