By Jeff Lehmkuhler
My forage colleagues and I seem to get bombarded with questions on forage quality and interpreting forage test results this time of year. The timing coincides with folks starting to feed hay and looking at developing supplementation programs for the cattle receiving the forage. Getting the forage tested for nutrient content is the first step.
Proximate analysis allows for separating a forage/feed into various macronutrient categories and was initially developed by German researchers in 1860. The components measured in the Weende analysis included: moisture, ash, crude protein, crude lipid, crude fiber and calculated nitrogen-free extracts. Crude fiber was replaced by the neutral and acid detergent fiber analyses developed by Dr. Peter VanSoest in the 1960’s to improve energy estimates of feedstuffs for ruminants as some of the cell wall is degraded by the rumen microbes. I am always in awe of the progress researchers have made in the nutrition field beginning with feed composition analyses more than 150 years ago.
The laboratory process provides us with some insight on the feed quality, but the energy estimates don’t always mimic the biological performance of a feedstuff. However, the laboratory analyses are useful in developing feeding programs. As an example, knowledge on the crude protein content of a forage can help avoid rumen nitrogen deficiencies ensuring microbial fermentation is optimized. I encourage everyone to test stored forages that will be fed this winter to help in developing supplementation strategies.
Forage test results can tell us a lot about a feedstuff. However, when we think about hay quality, we must go beyond the laboratory analyses. I see many forage test results each year, but that is where it stops. I don’t get to physically see the forage, touch it, smell it. I know what you are thinking, here he goes again off on some Ivory Tower academia discussion. Actually, I want to share two different real-world situations from this fall with you to hopefully drive home the notion that managing the hay making process is as or more important than the chemical component of the hay.
The first farm situation involves alfalfa hay, the queen of forages. Not many beef operations produce alfalfa or alfalfa/grass mix hay for beef cattle. This may be due to the cost of production, fertility, soil type or other factors. Let me set the stage. The operation weaned calves and were providing grass hay and grain supplement. The calves received grass hay the first month after weaning. A spot check of their weight taken after a month post-weaning reveled calves averaged 569 pounds with an average daily gain of 3.2 pounds. Now, these calves were eating the hay aggressively and some of the weight gain was a result of gut fill. However, the calves were doing well, eating and gaining. Exactly one week later, weights were taken again. On average, the calves weighed 548 pounds. They had lost an average of 21 pounds in 7 days! Yes, this would be an average daily gain of -3 pounds per day. Calves were coughing excessively; one calf was showing symptoms of respiratory distress five weeks post-weaning. What happened?
I did what I do in situations where weight losses like this occur. First, I checked the waterers. They were not fouled by manure and had a bit of feed/hay in them but not bad. I then looked at the hay. Bingo! This was alfalfa hay, not grass hay, that was offered the first four weeks. In September, a last cutting of alfalfa was taken and baled. However, weather conditions changed and forced the alfalfa to be baled before it was dry enough to store as dry hay. The farm ran out of the grass hay that had been fed after 4 weeks and put in this alfalfa hay which now was about six weeks since being baled. Mold was found throughout the bales and some areas were black. A general forage test wouldn’t have provided this type of information. We would have seen the moisture percentage being high giving us suspicion that it may have been moldy, but in a lot of situations it would have been overlooked. By attempting to salvage a few bales of hay, the calves lost weight, got sick and cost the operation.
The second situation involves cover crop harvested for hay. When cut at boot stage cover crop forages, generally cereal rye in this area, can have decent quality. Rye can be tricky though as it matures early and fields that are poorly drained make it a challenge to get rye harvested in early spring. The farm manager thought the hay would be decent quality in the 10-12% protein range and mid 50’s for TDN. This hay was being fed to lightweight backgrounding calves and getting calves to eat was an issue. After getting the forage test results, the hay was notably lower in quality than expected being only 7% crude protein. This category of animal is stressed from weaning, shipping, commingling and will often have low intakes the first few days after arrival. These light-weight calves are also in a lean phase of growth needing additional protein for muscle accretion. The diet was formulated assuming the hay is 11% protein, but the hay only contained 7% protein. Since the requirement for protein in these light-weight calves is 14-16%, the diet for these calves was protein deficient. This deficiency can reduce immune response and lower performance. Further, the NDF and ADF levels would suggest the hay was cut a bit mature. Lastly, upon inspection of the hay, it was also baled too wet due to weather. Some bales heated and caramelized which would lower protein and energy. Other bales were moldy and had black areas within the bales. When you are managing stressed light weight calves, it is critical that the calves want to eat, not that they are forced to eat what is provided. Calves of this type need soft-leaved second/third cutting grass hay that is mold free. Was it just the hay? No there were other management factors that were involved as well, however, the forage test alone would not reveal the mold issues.
Forage testing for nutrient content is always recommended to help develop feeding programs. However, be certain to consider anti-quality issues such as mold that could impact animal performance. Weather is always going to be a challenge when making hay. It is important to realize the potential trade-off of wet forage at baling to get the hay up versus the risk of increased growth of fungi and molds. These molds and fungi can have detrimental impacts on intake and animal performance. As a backgrounder in Oklahoma told our group when we visited his operation, don’t force your cattle to be Hoover vacuums cleaning up everything in the bunk even if it is half rotten feed. Rather manage the feeding program to provide them something that is palatable which they want to eat to ensure optimal health and performance. Have a great holiday season and stay healthy this year.
Source : osu.edu