There's a Lot of Hay, But it's Only So Good
Livestock Update, October 2003
Mark L. Wahlberg, Extension Animal Scientist, VA Tech
This year we have had an abundance of rain, thus the grass has grown profusely. Unfortunately, when the grass achieved the proper stage of maturity for hay harvest, it kept right on raining. When hay-making weather finally arrived, it was pretty late in the season. The result was a huge amount of hay that is overly mature, and thus somewhat low in feed value.
The nutrition a cow gets out of hay is a function of how much she eats and the amount of energy, and protein contained in the hay. With hay that is overly mature, the fiber is less digestible. This results in hay moving more slowly through the digestive system. Since it takes longer to pass through the gut, the cow is not able to consume large amounts of hay at any one time. Conversely, with hay that has less fiber and higher digestibility, the rate of passage through the system is faster, and hay intake by the cow is higher. So the problem with over-mature hay is two-fold: the hay has a lower concentration of nutrients, and the intake of the hay is also less.
But exactly how much nutrition is needed by the cow? And just how low in nutrient content is this year's hay? Let's look at Table 1 for the nutrient requirements of a mature beef cow.
|Table 1. Nutrient Requirements of a Mature Beef Cow (Concentration of Nutrients in the Feed)|
|Dry, Middle of
|Dry, Late in
|Low Milk at Peak Lactation (10 Lb) Typical of many British breed cows|
|Crude Protein %||8.8||7.3||6||7|
|Dry Matter Intake||25||25||24||24|
|Medium Milk at Peak Lactation (20 Lb) High milk British or British Exotic Cross|
|Crude Protein %||10.6||8.5||6||7|
|Dry Matter Intake||28||26||24||24|
|High Milk at Peak Lactation (30 Lb) Simmental or Gelbvieh or Dairy Cross|
|Crude Protein %||12.2||9.6||6||7|
|Dry Matter Intake||30||28||24||24|
|From National Research Council (NRC, 1996).|
As can be seen in this table, nutrient requirements are higher during lactation, especially in early lactation, than when a cow is not producing milk. With higher levels of milk production, nutrient requirements of the cow are also higher. Finally, a cow's metabolism is programmed to have a higher level of feed intake during lactation, to help her consume the higher quantity of nutrition she requires at that time.
Although most hay is not sampled and tested for nutrient content, the Forage Testing Lab at Virginia Tech has processed several this year. As you might imagine, there is a range of results. Many samples are testing in the upper 40's on TDN, with others in the low 50's. However, protein level of tested grass hays is consistently at least 8%. Even less second-cutting hay is tested, but it is typically in the mid to upper 50's on TDN and at least low teens for Protein.
How should this hay be used to best advantage? Well, that depends on a number of factors. When the cows are calving is the most critical item. Fall-calving cows (September-October) with their calves should be on pasture now, and should be able to graze for some time to come. There is no rush to feed them any hay. Grazing provides much better quality nutrition than does hay, especially this year's hay. As can be seen in table 1, once the cow moves into late lactation her requirements for nutrition go down quite a bit. This time typically coincides with the end of the breeding season. Once a cow is bred the level of nutrition is not very critical. At this time I would recommend that supplementary feed be given to her nursing calf, either by early weaning or by creep feeding, than by feeding the cow. Dr. John Hall has discussed this topic more completely in his article in this same issue of Livestock Update.
If the cows are calving in the winter (December-February) they will definitely need supplemental feeding. This is particularly true if they have the genetic potential for high milk production (see Table 1). The poor quality first-cutting hay just doesn't fit in very well with calving at this time of year. Grain that provides both extra energy and protein must be fed to these cows if low quality hay is all that is available. Feeds such as corn gluten feed, a mixture of corn and soybean meal, wheat midds, or a blended commercial grain mix with at least 14 or 16% protein would be needed. This supplemental feed should be given through the breeding season, or until good spring grass is abundant for grazing.
The spring-calving cows (March - May) have a short time of critical needs. Up to within a month or two of calving these cows can get along fine with the low quality hay. As depicted in table 1, late gestation needs can be met with hay that is in the upper 40's on TDN and 7 or 8 % protein with no supplementation used. However, once she calves that hay is no longer good enough and supplementation like that described for the winter calving cow is needed until good spring pasture becomes available. You just don't have to feed the supplement for as long with the spring-calving cow.
Pasture is considerably higher in nutrient content than is hay. Stockpiled fescue typically contains energy in the upper 50's and protein in the teens, which is similar to many samples of alfalfa hay. Full utilization of fall pasture will provide a high quality diet to cows. Full utilization also provides more days of grazing, thus reducing the days in which hay must be fed. By using practices such as strip grazing to force cattle to fully graze a portion of the area before being allowed access to additional forage, less waste due to trampling and soiling will result. Fall pasture is a valuable resource, and needs to be wisely utilized in a grazing system.
Questions are already coming in concerning the use of liquid protein supplements (LPS) with this mature hay. These feeds are typically based on molasses or some other by-product liquid feed to which has been added urea (a nonprotein nitrogen source), minerals and vitamins, and sometimes fat to enhance the energy level. Claims of benefits for this type of feed include that there will be an increased intake and improved digestibility of hay when LPS is used. Yes, there is properly conducted research data to demonstrate this benefit. BUT, that research was done on western range type forage which typically contains a protein level of around 4%. Our forages rarely get below 8% protein. And that makes a difference.
When protein in the forage is less than 7%, the bacteria living in the rumen are not functioning very well because they are starved for protein. These are the same bacteria that digest the fiber in hay. When a source of nitrogen is added to the diet of the cow, the rumen bacteria use this nitrogen for their own growth and metabolism, allowing them to function more efficiently. Thus, the cow is able to digest her hay more fully, and as described early in this article, she is able to consume a higher quantity of hay each day. However, when the hay is at or above 7 % protein the rumen bacteria already have enough nitrogen to function efficiently, and any further addition of nitrogen or protein fails to increase digestibility or intake. Since our forages are almost always in excess of 7 or 8% protein, we fail to see the improvement in hay intake or digestibility that the western ranchers see with their forage that is only 4% protein.
This is not to say that LPS is not beneficial. It is a supplemental feed that provides both energy and protein. When extra energy or protein are needed, LPS can be considered as a feed to use, just as can be corn, soybean meal, corn gluten feed, or other supplements. But for us in the east it is a supplemental feed, not a treatment for low quality forage.
Let's take a quick look at creep feeding, especially for those fall-born calves as they move through the winter season. Many trials have demonstrated that creep feeding with grain mixes that are self fed generates a feed:gain ratio of about 10:1. This means that a calf must consume 10 pounds of creep feed to generate an additional 1 pound of gain. With calf prices quite high (frequently exceeding $1.00 per pound), and grain prices relatively modest, creep feeding looks like a paying proposition.
When calves get to be at least 4 months old, a producer must consider whether to supplement the hay with a grain mix to increase energy and protein of the diet, or to feed the grain to the calf directly. Producers in this situation should consider either early weaning of the calf to reduce the cow's nutrient requirements or to at least creep feed the calf while he is still nursing the cow during the latter half of lactation. For more information on creep feeding see the VCE publication on that topic, which is available on line at http://www.ext.vt.edu/pubs/beef/400-003/400-003.html
In summary, the 2003 hay season was full of frustration. But at least there was hay to cut. Now that it is made, and we know it is somewhat low in nutrient content, we need to use it wisely. This involves decisions about matching the time of hay feeding with the nutrient requirements of the cow. It also involves decisions about supplemental feeding. This may involve supplementing the calf instead of the cow, under certain circumstances. Extending the use of fall pasture through good grazing management will delay the need for hay feeding, and keep a better diet going into the cows.