By Jimmy Hughes
As we enter what is hopefully the final days of cold weather and look forward to warm temperatures and green grass, it is a good time to evaluate the body condition scores of your cattle to determine if extra supplementation will be needed to prepare your brood cow herd for calving and breed back time. University studies all agree there is a direct correlation between body condition scores and reproductive performance of your cow herd.
With this in mind, I have always encouraged producers to take a feed and forage sample to determine the approximate nutritional value of the feeds being provided to their cattle. With higher feed prices and less than normal hay crops, I would again encourage doing an analysis on the feed being provided to your cow herd. Armed with this information, you can better determine the feeding needs of your cows to get them in adequate body condition coming out of winter.
Another reason to have this information is to allow the producer to make better decisions when purchasing ingredients and feed by-products. With increased feed prices, a number of lower priced by-products are being made available to producers. The only way to determine if any of the products are of any value to you is to have an analysis completed on your current feed and incorporate the information into your feeding program.
Questions I am often asked are: What information should be asked for in an analysis and what does this information mean when I receive it? Most all laboratories performing forage analysis usually have a standard package that will provide most of the information beef cattle producers need. The standard analysis will provide protein levels, energy measurements, mineral levels, vitamin levels, fiber levels and moisture.
While most of these results are straight forward, the different measurements of energy are a little more complicated and harder to understand. The need to understand energy levels is even more important because energy is the most limited nutrient in beef cattle diets and exceeding energy requirements is what will increase body condition scores in your brood cow herd.
Most laboratories will report the following information as ways to determine the overall energy value of a feed: total digestible nutrients (TDN), fat, net energy of gain, maintenance and lactation, nitrogen free extract (NFE) and carbohydrates. Let’s look at each of these values and what this information means to you, the producer.
TDN is the value most often used by producers when determining the energy value of a feed. It is determined by the summation of the digestible protein, digestible nitrogen free extract, digestible crude fiber and digestible fat times 2.25. (Fat has 2.25 times more energy than carbohydrates; therefore, the reason for multiplying fat times 2.25% in the formula.) While TDN is a very crude measurement for energy, it is a good way to make an initial determination on the overall quality of feed. A good feed will be at least 65% TDN while a good forage should be close to 50% TDN.
The biggest area of concern in some analysis is it does not take into consideration the digestibility of the fiber and will underestimate TDN on highly digestible fiber by-products like gin trash and peanut pellets.
Fat will be reported as either fat percent or ether extract. This is very reliable and can be used when deterring the overall quality of feed. Again, it is important to remember the higher the fat level of the feed, the more concentrated the energy in the feed. While fat is good at providing high levels of energy, it is possible to get to much in the diet of cattle. Fat levels in the total diet above 8% can lead to palatability problems as well as some incidence of bloat.
Also, high fat feeds provided in the last trimester of gestation can lead to larger calves, obese cows, reduced milk production and calving problems. I suggest most producers provide a complete diet around 5% fat to reduce any problems associated with the feeding of high fat products.
Another measurement of energy sometimes reported is NFE which is determined by the percentages of water, ash, protein, fiber and fat being added together and subtracted from 100. NFE is made up primarily of readily available carbohydrates, like sugars and starches. Sugars and starches are very important in the diets of cattle because they provide rapid energy to cows during extreme conditions, such as cold, wet weather, and provide carbon chains to microbes in the rumen of cattle that help the microbes to continue to reproduce themselves for proper rumen function. Again, depending on the method of determination, the NFE percent may be reported at a level lower than actual because of digestible fiber levels.
Net energy of gain (NEg), net energy of lactation (NEl) and net energy of maintenance (NEm) are also based upon the calories required for cattle to either maintain body condition, increase body condition or energy required for lactating. These are very specific measurements to determine the amount of this feed required to meet the energy needed for maintaining, gaining and lactating. There will be around a 10% increase for lactating and growth over maintenance of a cow. Carbohydrates (CHO) are very important in cattle diets because they will provide the majority of energy the cow requires on a daily basis. A carbohydrate level of 24-32% will be adequate in providing needed carbohydrates to the diet of cattle. Cattle will use these carbohydrates for glucose production and microbial reproduction. Most by-products like soyhulls, peanut pellets and corn gluten do not contain the needed carbohydrates for cattle to perform at peek levels.
While there may be other labatories who report digestible energy (DE) or metabolizable energy (ME), most reports now contain one or more of the energy levels previously discussed. It remains important, as a producer, you take this information and talk with an animal nutritionist about what this means to your operation. A nutritionist will be trained to make recommendations that will not only meet the overall requirements of your cattle, but will also save you money by recommending products that will meet the total nutrient requirement of your herd including each of the different measurements of energy.
. I hope each of you are planning to attend the 2008 Alabama Cattleman’s Convention and Trade Show in Birmingham on February 1-2. This is an excellent way to gain valuable insight into your business and talk with fellow cattle producers. I look forward to seeing you there or talking with you in the coming months.
Jimmy Hughes is AFC’s animal nutritionist.