K-State Research and Extension

“Forage Analysis: What Numbers Do I Need?”

by Justin W. Waggoner, beef systems specialist

One of the more common questions I receive with regard to analytical testing of forages and other feedstuffs is, “I have the sample, now what do I test for or what analysis package should I select?”

The basic components that nutritionists need to evaluate a feedstuff or develop a ration are dry matter or moisture, crude protein, an estimate of the energy content of the feedstuff [Total Digestible Nutrients (TDN), Net Energy for Maintenance (NEm), Net Energy for gain (NEg)], and the macro minerals, Calcium and Phosphorous. These are the most basic numbers that are required but including some additional analyses in the report can give us additional insight into the quality of the feedstuff or improve our ability to predict animal performance, which is the primary reason we analyze feedstuffs. I recommend that the report include acid detergent fiber (ADF) and neutral detergent fiber (NDF). The amount of NDF in forage reflects the amount of cell wall contents (hemicellulose, cellulose, and lignin) within the sample. The NDF fraction is often associated with the respective bulkiness of forage and is correlated with dry matter intake of the forage or feedstuff. Therefore, the amount of NDF may be used to estimate the expected dry matter intake associated with the forage. The ADF number represents the amount of cellulose and lignin within the forage and is correlated with the respective digestibility of the forage. In general, a higher ADF value is associated with forage that has a greater proportion of cellulose and lignin and would likely be more mature. Additionally, the ADF fraction is used to calculate the energy estimates TDN, NEm, and NEg that appear on the report. There are a number of different mathematical equations that the testing laboratory may use to calculate these numbers, based on the type of sample (corn silage, alfalfa, grass hay, etc.). If the ADF is included in the report, the nutritionist can adjust or recalculate the energy estimates if necessary.

If the forage will be fed in combination with a byproduct feed such as wet distiller’s grain, including an analysis for sulfur can be beneficial if the forage will be used in a growing or feedlot ration. Additionally, if the forage is a known nitrate accumulator (forage sorghums, sudangrass) or may have been stressed due to drought, including a nitrate analysis should always be considered, especially if the forage will be fed to pregnant cows.

Most analytical laboratories have a number of different analysis packages which encompass the most common procedures or numbers that a nutritionist or producer needs to know about their feeds. These packages will typically include the basic procedures (DM, CP, TDN) and then add on specific analyses such NDF, or the Macrominerals (Ca ,P, Mg, K, Na, Cl, S). Some laboratories may group analysis packages by the type of sample (Forage vs. mixed ration) or production purposes (dairy vs. beef).

The objective of analytical testing of forages and feedstuffs is to improve our ability to meet the animal’s nutrient requirements and ultimately predict animal performance. The unequivocal best method of evaluating the quality of a feedstuff is feeding the feedstuff to an animal and evaluating performance over a set period of time, under a specific set of conditions. Since that would not be cost effective or timely, analytically evaluating feedstuffs in a laboratory is the next best thing and although it is not perfect, it is unequivocally better than the “this looks like really good stuff” method of evaluating feedstuffs.

“Weaning: Help Your Calves Make the Transition”

by Justin W. Waggoner, beef systems specialist

Weaning is our opportunity as cattle producers to prepare calves for the next phase of the beef production cycle. Weaning represents a transition and how well we prepare calves for the transition is essential to the outcome.

The goal of weaning is to produce a healthy calf that is comfortable without its dam, readily consumes feed and has successfully acclimated to a new environment. One of the essential transitions a calf has to make during weaning is the transition from mother’s milk and grazed forage to grazed forage and supplement, hay and supplement, or a ration containing novel feeds delivered in a bunk.

Feeding both cows and calves a small amount of the supplement or weaning ration prior to weaning, in the weaning pen or pasture can be used to help acclimate calves to both the feeds and the environment. Additionally, feed intake of weaned calves is often low (1 to 1.5% of bodyweight, dry basis) immediately following weaning.

Calves also have relatively high nutrient requirements. Thus, the weaning diet must be nutrient dense to meet the nutrient requirements of the calves at the expected intakes previously mentioned. Unfortunately, the dry feeds calves are often most familiar with (typically grass hays) are not necessarily nutrient dense. At the K-State Agriculture Research Center, Hays, KS, a feeding management protocol for weaning calves has been developed that works well for transitioning weaned calves to a total mixed ration.

The protocol is summarized in the table below. Essentially, high-quality grass hay and the weaning ration are offered each at 0.5% of the calves’ current bodyweight, dry basis, on the day of weaning. The weaning ration is placed in the bottom of the bunk and the hay is placed on top. The amount of the weaning ration is steadily increased, while the amount of hay offered remains constant. In addition, on day 4 the hay is placed on the bottom of the bunk. Over a period of 7-10 days the dry intake of the calves is steadily increased and should reach approximately 2.2-2.5% of the calves bodyweight by 10-14 days following weaning.

*Remove any uneaten feedstuffs before feeding current days ration For more information, contact Justin Waggoner at jwaggon@ksu.edu.

“Feeding Corn to Cows this Winter”

 by Chris Reinhardt, feedlot specialist

Although some areas received abundant rain this summer and have ample hay supplies, other regions received only marginal rains, resulting in a marginal hay crop. On the other hand, most of the corn-growing regions of the Midwest and High Plains had excellent growing and harvest conditions which have contributed to abundant grain supplies, resulting in relatively low corn prices this fall.

This combination of coinciding circumstances have raised the question, “Can I feed corn to cows instead of hay?” Well, the answer is an emphatic, “Maybe…”

Nutritionists look at a cow as essentially a rumen with legs, a mouth, and an udder. The cow has a mouth to feed the rumen—more specifically, to feed the rumen microbes, and the job of the rumen microbes is to feed the cow. For most of a cow’s life she has fed these microbes a diet primarily of cellulose in the form of grass, hay, corn stalks, wheat straw, etc. What little concentrate (grain, by-product feeds, protein supplements) she’s received has been in the form of a small amounts of supplement in addition to the forages which have been her main diet.

The rumen microbes digest the cellulose in forages best when the rumen pH remains in the range of 6.0 to 6.5; this is one (although not the only) reason cows chew their cud: the saliva produced and injected into the cud during rumination contains buffers to keep the pH above 6.0. The more grain or other concentrate feeds we provide, the more likely the rumen pH is to decline below 6.0. The other extreme would be finishing feedlot cattle consuming a high-grain diet which results in a rumen pH in the low 5’s or perhaps even the high 4’s—very acidic. This acidic pH makes for an environment unfavorable for forage digestion.

So when we begin to consider feeding more than a small amount of concentrate to cows, we need to consider that the rumen pH will likely fall below the pH which is optimum for forage digestion. For this reason it is advised that we consider feeding a diet which is either less than 25% concentrate (on a dry matter basis), or greater than 75% concentrate, and avoid feeding in between these two levels. Why? Because as we exceed 25% of the diet as concentrate, the rumen pH will decline and the nutritional value of the forages in the diet decline, resulting in wasted expense. (NOTE: this effect becomes more pronounced with increasingly low-quality forages than with high-quality forages.)

A schematic of the results of feeding concentrates in addition to a basal diet of forage looks something like this:

With that out of the way, one way to capture the value of low-cost grains and concentrate feeds this fall and winter, without placing cows on a “finishing” diet, is to consider limit-feeding a high-grain diet. By “high-grain”, we typically mean 70-75% concentrate with sufficient forage to prevent acidosis in aggressive eaters. By “limit-feeding”, we typically mean providing a level of intake of the high-energy diet which supplies a similar total daily amount of energy, protein, minerals, and vitamins, in a smaller intake amount, than we would normally expect when full-feeding a forage-based diet.

For example, you may feed a “conventional”, forage-based winter cow diet of 25 lbs of prairie hay (0.45 Mcal NE_M/lb, dry matter basis) with 6 lbs of dried distiller’s grains (0.99 Mcal NE_M/lb, dry matter basis), providing a total of 17.3 Mcal NE_M per day. This same 17.3 Mcal NE_M per animal per day could be supplied from 8 lb cracked corn (1.02 Mcal/lb), 7 lb dried distiller’s grains, and 5 lb of prairie hay. If you’ve done the math, that’s a “conventional”, forage-based diet fed at 31 lbs (dry matter basis) vs. the “limit-fed high-energy” diet fed at 20 lbs. If the cows weigh an average of 1,320 lbs, that’s 2.4% of body weight vs. 1.5% of body weight. FULL DISCLOSURE: the limit-fed cows are going to be hungry and fairly aggressive every morning. Even though they’re receiving the exact same amount of daily energy supply, because they’re not physically full, they will be more than ready come breakfast time. You’ll need stout fences and at 30-36 inches of bunk space per animal in the pen.

There are certainly challenges to limit-feeding cows, most of them pertain to logistics, facilities, and equipment. But two reasons to consider the limit-fed program are: (1) potential per-head feed cost savings; and (2) the chance to reduce the drain on your winter hay stores. In addition, depending on local spot market prices in your area, you may consider inserting other by-product feeds into the high-energy, limit-fed diet, such as: soy hulls, wheat midds, and corn gluten feed, since these all have energy values close to (although not equal to) that of corn.

“Trying to Add Value Through Backgrounding”

by Chris Reinhardt, feedlot specialist

The strong dollar is good for a lot of things, or so I’m told. However, the strong dollar also hurts our export markets because our product is automatically more expensive to buyers around the world simply because their currency loses its purchasing power vs. U.S. products. The U.S. beef industry saw beef exports climb out of the doldrums post-2001 and a dip after the recession in 2009 to record levels in 2011, 2012, 2013, and 2014. This led to record prices for boxed beef, fed cattle, and subsequently, feeder calves. Heady times indeed… Conversely, the U.S. dollar began a steady climb in value vs. other global currencies in mid-2014 and has increased in value by 20-25% over the past 18 months, resulting in a significant drop in beef exports; this has placed and will continue to place downward pressure on boxed beef value, fed cattle prices, and feeder calf prices.   As expected, we are experiencing low calf prices this fall compared to recent years; we’ve already seen feeder cattle futures decline by 40% since the mid-2014 highs.

In the face of this challenge, producers can capture more value through backgrounding calves to heavier weights. While a rising tide floats all boats, the current receding tide is pulling all boats downward, and a falling yearling market next spring puts our hopes of making money backgrounding our calves in jeopardy. For example, if 575 lb steer calves are currently valued at $139/cwt (total value = $799), and 875 lb steers are valued at $109/cwt next February (total value = $953), then the price slide (or the “value of gain”) is $51/cwt ($953 – $799 ¸ 300 lbs). This $51/cwt is the value of weight put on each calf above their initial weight of 575 lbs.

Producers can only increase profit if they can feed calves for less than 51¢/lb of gain. With the current low cost of grain and abundance of forage, the feed-only cost of gain for developing calves is likely in the range of 40-50¢/lb. But once we add the costs for vaccines, implants, anti-parasiticides, morbidity treatment costs, and a risk of mortality, total cost of gain could be in the range of 60-65¢/lb of added gain. If the sale price is expected at $109/cwt, we’re looking at backgrounding as a losing proposition.

Obviously, none of these numbers are set in stone. You will need to work closely with your local extension professional and feed supplier to formulate diets and provide cost estimates and breakeven calculations. Also, work closely with your veterinarian when building your processing and treatment protocols.