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Peruse practical information for the dairy producer on essential topics including management, A.I. and breeding, new technology, and feed and nutrition.

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The following is the first of a two-part series discussing design specifications for feed and water spaces in freestall barns.

Two basic ingredients in the production of milk are feed and water. Therefore, careful attention must be given to the design and management of these areas in freestall shelters. The feeding area should allow convenient delivery of the ration, provide enough space for the cows to consume an adequate amount of feed, be clean and free of debris and be easy to clean. It should also provide a productive and safe work environment for the caretaker and be cost-effective.

Water stations should provide plenty of good-quality, clean water offered from units conveniently located within the animal area that are easy for cows to drink from. This [article] will discuss design considerations for fenceline feeding and watering stations in freestall dairy shelters.

The feeding area should:

•encourage and allow each cow to consume an adequate amount of feed dry matter during each feeding episode during the day

•provide a comfortable feeding experience for the cow

•facilitate 24-hour availability of high-quality feed

•be easy to clean and use

The design, construction and management of a modern feeding system should contain the following key principles:

•Cows are fed at a fenceline, not a walk-around feedbunk.

•Facing fencelines are far enough apart to negate the feeling of confrontation.

•The cows eat in normal head-down (grazing) position.

•The eating surface is 2 to 6 inches above the cow alley.

•There is a flat feed table to encourage easy mechanical clean-out and feed push-up.

•The smooth, nonporous, easy-to-clean eating surface is 32 to 36 inches wide.

•There is a hard surface area at the same elevation as the eating surface where the food is “stored” after delivery or where cows may “push” feed back during eating.

•Feed should be pushed or scraped back to the eating surface, towards the cow, without becoming contaminated with gravel or mud from an unpaved driveway or vehicle track.

•The driveway is wide enough to allow the delivery vehicle to pass without driving where feed is to be delivered or on previously delivered feed.

•A separation device, or feed barrier, allows cows convenient access to the feed table without undue twisting, turning or repositioning of the head and neck.

•Expected contact points between cow and the separation device are shaped and located to prevent abrasion, penetration or bruising.

The dimensions of the feed delivery vehicle, both present and future, must be considered when determining the minimum height and width clearances of the driveway and shelter access opening.

Feeding space per cow

The feeding space refers to the amount of fenceline available to the cows. Feeding space per cow is calculated by dividing the total length of feeding space provided by the number of cows that have access to it. The amount of space required for cows to stand and eat comfortably is an important consideration.

One suggestion for determining the amount of feeding space required per cow is to multiply the chest width of a cow by 1.15 for non-pregnant cows and 1.25 for pregnant cows. Non-pregnant and pregnant 1,400-pound dairy cows with a chest width of 32 inches will require 25 inches and 27 inches of feeding space, respectively. Well-designed two-row and four-row freestall shelters can provide enough fenceline length for all cows in a group to eat at once, if the group is not overpopulated.

Three-row and six-row freestall shelters do not provide enough fenceline length for all the cows in a group to eat at once. Overpopulating a group further reduces the available feeding space per cow. Whether it is important for all cows to eat at the same time is a management decision, not an engineering decision. One study of two six-row freestall shelters indicated that even with limited feed space (15 to 16 inches per cow), the feeding area was fully occupied infrequently. No loss in production could be attributed to limited feeding space. However, they also recognized the limited nature of the study.

A more recent study of feedbunk length requirements for Holstein dairy heifers found that limited feedbunk length did not affect group growth rates, but it significantly affected individual growth rates. Perhaps the same is true with respect to individual dry matter intake (DMI) and milk production of lactating dairy cows.

Cow standing area

The width of the feeding alley should allow the cow to pass behind cows eating without disturbing them. A 12-foot alley width allows two-way cow traffic behind cows eating at the fenceline. If the feeding alley also provides access to a row of freestalls, 14 feet is recommended to allow cows to enter and exit the stalls more easily, without disturbing cows at the feeding area.

The surface on which cows stand should provide confident footing to reduce the chance of injury. Grooves in a parallel or diamond pattern formed into the concrete are common. The surface should be of good quality and construction to provide traction but not injure cows’ feet.

In an attempt to create a more comfortable surface for cows to stand on when eating, some producers install rubber belting in the feeding alley where the cows stand to eat. The cushioned surface is typically 5 to 6 feet wide and runs the length of the alley. It stands to reason this surface is more comfortable for cows to stand on compared to concrete. Some suppliers offer belting with a grooved surface, but still it can become slippery when wet and covered with manure. However, cows often prefer to walk on the cushioned surface when they are not hurried and the surface is available.

Sanitary steps

Sometimes a curb, or step, approximately 4 to 8 inches high and 12 to 16 inches wide, is placed next to the feeding area. The purpose is to prevent cows from defecating into the feed manger. A sanitary step is not recommended along a fenceline feeding area since it may hinder the cow’s ability to assume a natural grazing posture.

The separation device (feed barrier)

A successful feed barrier must allow the cow convenient, injury-free access for eating while preventing her from walking onto the feeding area. She should be allowed to access the feed in a natural way with a minimum of annoyance or obstruction from the feed barrier or separation device. The separation device should also protect the feed from contamination by manure and minimize feed spillage into the standing area. Two feed barriers commonly found in modern freestall shelters are the post-and-rail design and self-locking stanchions.

The lower portion of the separation device consists of a curb, or low wall, to prevent manure and feed from mixing, discourage the cow from stepping onto the feed table and allow feed to be delivered to the feed table without spilling into the cow alley. The height of the curb should not exceed the recommended throat height since it can interfere with the cows’ access to feed.

The upper portion of the separation device should also be considered when determining the curb height. If self-locking stanchions, or a similar feed barrier, are installed or might be added in the future, the top curb should be approximately 3 inches lower than the maximum throat height to allow for the bottom rail and a space between the bottom rail and curb to prevent feed build-up. This will reduce the capacity of the feed table and may increase feed spillage in the cow standing area. Placing a 3-inch-high wood filler strip above the concrete can help reduce this concern, and it can be removed in the future if necessary.

The post-and-rail feed barrier provides excellent access to the feed table for cows, and it is relatively inexpensive to construct. Proper placement of the upper rail allows the cow good access to feed with a minimum of interference. The neck of the cow should only nudge the rail slightly when she is reaching for feed.

Self-locking stanchions, or head locks, allow the manager to restrain a group of cows, or a single cow, for observation, treatment or other herd management activity. This feed barrier type is often mounted to a slant so the cows can reach further into the feeding area more comfortably.

It is important to select a design that allows each cow to insert her head and neck easily and comfortably through the access opening without excessive twisting and turning. Some manufacturers have overlooked this important design consideration, perhaps intending to provide more opening in a given space, simplifying assembly or saving material. Downed cows are also a concern with this feed barrier type. Fortunately, designs are available that allow the lower section to open wide to aid in cow release.

The eating surface

The eating surface must be smooth, clean and free of leftover feed and debris in order to encourage good feed intake and aid in the control of disease. The low pH of silage can etch the manger surface, exposing the cow’s tongue and mouth to rough edges.

The feed table should be located 2 to 6 inches above the cow alley to allow the cows to eat in a more natural grazing posture. Cows eating with their heads in a downward position produce 17 percent more saliva – which directly affects rumen function – than cows eating with heads held horizontally.

The feed table should be 32 to 36 inches wide and should slope away from the fenceline approximately 1/8-inch per foot to help drain away moisture. High-strength concrete and admixtures are used to improve the durability of feeding surfaces. Properly installing tile along the length of the feed table provides a durable, smooth surface. Epoxy coatings are also used, but must be applied properly to allow for good adhesion.

Feeding area management

Without proper care and management, any feeding system design can fail. Feed should be readily available to the cows. This is especially important in feeding areas with limited feeding space or overpopulated groups. Cows tend to work feed away from the feed table and out of reach when eating. Feed should be pushed up regularly so it is available to other cows in the group. The feed table should be scraped clean of feed and debris daily so fresh feed can be put in its place. In addition, the feeding area should be well-ventilated and the cow alley cleaned frequently so cows do not have to stand in an accumulation of manure. PD

References omitted but are available upon request at

—Excerpts from “Dairy Housing and Equipment Systems: Managing and Planning for Profitability” Proceedings

“Hey, Doc, my cows are eating dirt. Waddya got for that?”

A few years ago, I posed this question at several dairy seminars in the Midwest: “Do your animals chew on wood or eat dirt if they have the chance?” A few said their cows would chew on wood. Almost all indicated their cows would eat dirt, if available. One fellow said he had to haul in dirt around the foundations of his buildings to replace the soil his cows had eaten over a period of years. Strangely enough, a few even told of their cows licking or drinking from urine puddles, if they could get to them. As bad as that sounds, it is even more alarming when conventional opinion regards this eating behavior as being almost normal because it is so common. It’s the “everybody’s doing it, so it must be OK” syndrome. And it may be “normal” in the sense that it is appropriate, compensatory behavior for animals forced to subsist on a mineral-deficient ration.

Eating dirt and other abnormal appetites are attempts to secure some vital element or attain some nutritive balance that is not otherwise present in their diet. It should be considered a warning signal that something is amiss in the ration.

To examine the problem from a holistic viewpoint, let’s go back in time and look at the effect of domestication on today’s dairy cattle. Most authorities agree that primitive cattle or Aurochs (Bos taurus primigenius) were first domesticated about 8,000 years ago. Before domestication, cattle lived a lifestyle similar to that of bison in the American west. They were free to roam over wide, naturally fertile areas. Specific imbalances of soil in one area would be offset by excesses or adequacy of the same element in other areas. A multitude of different plants were available. Many plants had the ability to absorb and concentrate different minerals and trace minerals, giving the grazers even greater nutrient options. Thus, over a period of time they could seek out and obtain balanced mineral and nutritional needs. Predators strengthened the genetic pool by culling the weak and unfit.

It’s a lot different today. Dairy cattle have been genetically modified to produce at levels never intended by nature, increasing their need for minerals.

Ever-more restrictive confinement limits their ability to seek out and consume adequate diets. In a natural grazing situation herbivores probably had hundreds of different plants from which to choose. Today they are limited to six or less: grass, alfalfa, corn, soybeans, cottonseed and maybe some oats or barley. Seeds and grains in the amount currently fed can be detrimental to dairy cow health. Cows are ruminants and need a high-forage diet!

Crop quality has declined. Every crop harvested or animal removed from a farm or ranch takes with it a finite amount of life-supporting nutrients. Major elements can be replaced, but it is difficult to restore a natural balance that includes high organic matter, adequate trace minerals and vibrant biological life. Intensive NPK fertilization results in higher yields at the expense of nutritive values and mineral content in the crops.

“Average” is a myth! A total mixed ration (TMR) is the industry standard feeding strategy that attempts to provide, in one total mix, all the nutrition required by the ‘average’ cow in the group. This concept fails to consider the individuality of each animal’s nutrient requirements. No two animals have the same needs. Variables such as breed, age, pregnancy, stage of lactation, weather, season of the year and others have a marked influence on the need for mineral supplementation. With a TMR, probably no one animal will get exactly what it needs. A few may get pretty close, but many will be lacking in some nutrients while others will have excesses. This limits their production, eventually depresses their immune response and ultimately may result in various herd health problems. Eating dirt, if available, is their way of responding to these imbalances.

Unfortunately, mainstream nutritionists tend to downplay the ability of animals to balance their nutritional needs. Anyone who doubts that cattle can make valid nutritional choices needs to watch cows graze in a mixed pasture. They do not just mow grass like a lawnmower, but they pick and choose each mouthful. They avoid eating the bright green grass surrounding ‘cow pies’ in the pasture but will search the fence-rows for weeds that concentrate various essential trace minerals. Given the chance, they will balance their nutritional needs during each feeding period.

The following incident illustrates another aspect of this ability. Weather had made it a bad year for crop quality. In late winter, a good client called me about two problems. His cattle were eating excessive amounts of mineral and his heifers would abort a live calf about 10 days before they were due to calve. The calf would live, but the heifer would usually die. Focusing first on his mineral problem, he decided to try a “cafeteria” mineral program in which each mineral was fed separately. He had to carry each bag of mineral through his cow lot to get to the mineral feeder. His first few trips were uneventful. Then suddenly several of the normally docile cows surrounded him, tore a bag of mineral from his arms, chewed open the bag and greedily consumed the contents … a zinc supplement.

Within a week after the mineral change, consumption returned to normal and his remaining heifers calved normally. Apparently, the previous year’s stressful growing season had resulted in crops that were deficient in zinc or perhaps high in zinc antagonists. His mineral mix was high in calcium with only small amounts of zinc. Their quest for zinc impelled them to overeat the mixed mineral. Excess calcium interferes with zinc absorption. Every mouthful they took increased the imbalance and escalated their need for zinc. Inevitably, metabolic problems began in the most vulnerable group – young, growing heifers in the last stages of pregnancy. Finally, they just gave up and checked out ... all for want of a few grams of zinc.

If your cows are eating dirt or if you just want to experiment, give your cows a chance to participate in their own diet formulation. Do not change your current ration, but do provide separate free-choice sources of these six items: salt, bentonite, bicarb, a basic mixed mineral with a 2-to-1 Ca/P ratio, one with a 1-to-2 Ca/P ratio, and kelp. Cows with rumen acidosis will prefer bicarb or bentonite. The separate sources of Ca and P allow them to adjust that critical ratio. If they lack trace minerals they may also eat a lot of kelp. If kelp consumption remains high you may want to provide separate sources of some of the trace minerals. There are commercial companies that provide a broad range of separate free-choice minerals and trace minerals.

We should use our nutritional knowledge to formulate dairy rations, but we should also rely on the nutritional wisdom of animals to fine-tune their individual needs. It doesn’t hurt to have two opinions; one from your nutritionist’s computer and one from the real experts – your cows. PD

Nutritionist Terry Dvorachek is in expansion mode. That’s because his clients are, too. Within a few weeks, Mountain View Dairy in Luxemburg, Wisconsin, will open a new freestall barn and expand its herd from 600 to 1,100 cows. To prepare for the expansion, Dvorachek has been stretching out the dairy’s forages.

“What I’m trying to do is keep tabs on the inventory of their feeds and look for feeds that would fit their feeding program,” Dvorachek says.

That includes finding good nutrient profile matches for the dairy’s forages, such as soybean meal/canola meal to feed with its haylage and corn gluten feed for its silage. Pairing forage nutrient profiles with off-farm commodities amounts to what Dvorachek calls, “forage stretchers,” which help the dairy make the most of its available forages.

“Don’t be afraid of buying products,” Dvorachek says. “Don’t be afraid to look at different products to buy to help address forage and energy needs.”

Dvorachek currently feeds a ration that includes 38 percent corn silage and 18 percent haylage. To help make the dairy’s forages last longer and feed more cows this year, the ration has included ensiled peas and oats and Western baled hay. Both commodities have helped to “fill the gap” in meeting the growing dairy’s forage needs.

After the expansion is complete, Dvorachek plans to transition the dairy to a ration that includes 55 or 60 percent silage. He says this will be possible because this fall more of the 400 acres owned by the dairy, where most of the dairy’s forages are grown, will be harvested in corn silage, which has a higher yield per acre than alfalfa or other crops.

“In our area, we are becoming corn silage-driven,” Dvorachek says. “Our farms are getting larger, and producers just simply can’t produce enough haylage alone to feed their animals anymore.”

As the percentage of corn silage in his rations have increased, Dvorachek says he’s also monitored fungus toxins. Within the last year, Dvorachek has found mycotoxins and aflatoxins creeping into silages. In turn, he has added a mycotoxin binder in Mountain View’s ration and in other dairy rations he consults in the area.

“A lot of dairies are adding in a mycotoxin binder as a status quo ingredient,” Dvorachek says. “It’s an extra 12 cents per cow per day, but when you do the math, if you eliminate some abortions, how do you put a value on that?”

To prepare for expansion, dairy owners, Mark and Al Seidl, had to overcrowd a few of their pens. It’s an added stress that Dvorachek says both he and the dairy’s owners have been “limping through.” To help minimize stress and competition at the feedbunk, Dvorachek says he’s focused on keeping the ration digestible, and he’s added extra minerals. Heat in late August and early September compounded stress and limited milk production in overcrowded pens, but Dvorachek says that minus the heat the ration and its added minerals have performed well and the cows have transitioned through the expansion process well. PD

Feed cost is the biggest concern for today’s dairy producers. The price of commodities such as cottonseed and soybeans, continues to drive up the cost of dairy rations. Today, nutritionists have to be able to identify the real feeding cost and help dairymen to find the equilibrium between ration cost and animal performance. Any changes to a dairy’s ration should positively correlate with animal performance, animal health and business profitability.

Feed costs represent 45 to 60 percent of the total cost of milk production. Therefore, the key to maximizing dairy farm profitability is still to maintain adequate nutrient levels while managing feed costs carefully. We all know that when optimal nutrition is achieved, cows will produce better quality and larger quantities of milk and overall health will improve, resulting in saved veterinary fees, breeding costs and drug treatments. A basic understanding of animal nutrition and how it applies to dairy cattle is essential to good herd management.

Proper feeding of the dairy cow is complicated and requires a combination of scientific knowledge, creativity and good management skills to balance the needs of the rumen microorganisms and the needs of the animal. Nutritionists have to be able to use this knowledge and apply it not only as an animal nutrition concept but also as a business concept.

Nutritionally, the objective of feeding dairy cattle is to provide a rumen environment that maximizes microbial population and growth. When designing rations for ruminants, one needs to consider both the animal and the rumen microorganisms.

In order to optimize animal performance, the process of feeding the microbes may be compromised. When ration changes are made based solely on changes in commodity prices, animal performance may be negatively compromised. Instead of saving money, the dairyman will be in a worse situation.

For example, because of the rising prices for soybean and cottonseed meal, some dairy producers have been considering the increased use of dried distillers grains (DDG) as a replacement for the aforementioned ingredients in order to save money. Many university and field trials have shown that the replacement of soybean meal (which is a rich source of rumen degradable protein), with sources of rumen undegradable protein (RUP) such as DDG, often results in an inconsistent improvement in lactational performance. Inclusion of high amounts of DDG (36 percent of the diet’s dry matter [DM]), however, generally decreases milk yields and milk fat. In addition, the limited amount of some amino acids such as lysine in DDG may cause a decrease in milk protein content.

Whole cottonseed is also used considerably in dairy rations, and it has also been a big concern of late when calculating a ration’s cost. Whole cottonseed is rich in energy, protein, fiber and phosphorus when compared to most of the many other ingredients available in the market. A comparison of the nutrient profile of whole cottonseeds with other commonly available protein supplements shows it to be the only ingredient rich in both energy and fiber.

This feature is especially attractive to high-producing cows in negative energy balance, which are usually starving for both energy and fiber. The inclusion of whole cottonseed in the diet of early- lactation cows usually increases the amount of energy eaten while still increasing milk yields. It frequently has a positive effect on milk fat tests, though a negative effect on milk protein is usually observed. Overall, the effect on milk price is usually positive. However, a reduction in pounds per head per day of whole cottonseed consumption might cause a reduction of total fat content in the ration (energy) which might result in negative results in animal performance.

For example, the number one nutritional reason for poor reproductive performance in ruminants is the lack of energy. As they start the lactation process, cows are in a negative energy balance. In order to compensate for this deficiency, cows rely on their stores of fat (e.g., body condition score or BCS). The more energy included in the ration, the sooner they will come out of this negative balance. Cows that lose BCS will take longer to have their first estrus and ovulation, and they consequently have poor reproductive performance.

Economically, in the short run the reduction of a ration’s price by replacing highly priced ingredients with lower priced ingredients might be the solution for the dairy business; however, animal performance might be compromised in the long run if the ration’s energy balance is not suitable to maintaining animal health. Alternative feedstuffs have to be considering for such potential negative changes. The dollar value of any feed ingredient should reflect the nutrients it contains relative to the cost of nutrients in other available feedstuffs.

Some tips to consider:

1) Look for alternative feed sources that might replace or complement the total ration by reducing feed cost while maintaining ration quality.

2) Be aware that a single feed ingredient in a ration is only part of the total ration. (Look at the whole picture, not only its parts).

3) The cost related to the reduction or the addition of a new feed ingredient in the ration has to pay off in its utilization by the cow. 6) Monitor feed cost and animal performance as ration changes are made.

4) Consult your nutritionist if considering the use of a new or substitute ingredient in the ration. Ask how it will be beneficial to animal performance and business profitability.

5) If your nutritionist provides you a commodity blend, ask him or her what is the exact proportion of each ingredient in the ration and the price you are paying for each ingredient.

6) Know your feed cost per animal per day. PD

References omitted but are available upon request at

In almost all biological systems, it is important that pH not deviate much from a fixed value. For example, for blood to carry oxygen from the lungs to tissue, pH must be maintained very close to 7.4. When rumen pH is either too high or too low, microbial fermentation and absorption of end products of that fermentation are less than optimal. Buffers, and other compounds, are added to rations for ruminant animals to aid in maintaining both blood and rumen pH in the desired ranges.

What is pH?

Maintenance of blood pH, in terms of animal survival, is extremely important. Supplying oxygen to tissues and temperature regulation are the only functions that take precedence over maintenance of proper acid-base balance. While it is extremely important to recognize this fact, the first part of this article will focus on the role of buffers in the digestive tract.

The term pH is commonly used to describe the acidity or alkalinity of solutions. In regards to this discussion, the item of interest, however, is not pH, but what it represents, which is the concentration of hydrogen ions. Use of the term pH to describe acidity may be slightly confusing as it is not a numeric scale but a logarithmic scale. A change in rumen pH from 6.0 to 6.5 may appear to be slight, only 8 percent, but represents a 316 percent reduction in hydrogen ion (acid) concentration.

What are buffers?

Buffers are defined as compounds that resist change in the pH of a system. While rumen pH can vary dramatically, the normal range may be considered to be from 5.7 to 6.7. In this range, bicarbonate is the primary buffering system in the rumen, although there are other minor buffers as well.

Bicarbonate, as a buffer, is most effective at a pH of 6.37 and is effective at a range of from 4.67 to 8.07. Commonly used compounds (such as sodium sesquicarbonate, potassium carbonate, sodium carbonate, magnesium oxide, calcium and magnesium carbonates) are more properly termed alkalizing agents based on their mode of action. Practically speaking however, this distinction only applies to magnesium oxide as all other compounds mentioned add to the rumen bicarbonate pool.

A byproduct: Volatile fatty acids

Volatile fatty acids formed during rumen fermentation are waste products produced by bacteria. Rumen fermentation is an anaerobic process and, as a result, conversion of carbohydrates in feed to microbial cells is greatly exceeded by the amount of these various waste products. When these waste products are absorbed and utilized by the host animal, the amount of energy to provide for cell maintenance and growth greatly exceeds that available to rumen bacteria. Most common among the volatile fatty acids produced during fermentation are acetic acid, propionic acid and butyric acid. It has been estimated that if the rumen were not buffered, the pH may drop to approximately 3.0.

Dissociation constants vary for common volatile fatty acids. This means that not all acids produced during rumen fermentation produce the same level of acidity. If propionic acid has a relative rank of 1.0, then butyric acid and acetic acid are 1.09 and 1.30, respectively. Lactic acid, found in silage and produced in relatively large quantities when animals are not well adapted to high-grain rations, is much more acidic than the volatile fatty acids. Lactic acid is 10.3 times more acidic than propionic acid, which can lead to problems when animals consume large amounts of silage. None of these organic acids can compare to hydrochloric acid, which is more than 70,000 times as strong an acid as propionate.

Neutralizing acid

Buffers also vary in their ability to neutralize or completely consume acid. Based solely on chemistry, one can rank buffers on a scale of from one to 10, 10 being the best. Table 1 shows a comparison of theoretical acid-consuming capacity and measured acid-consuming capacity. It should be noted that while magnesium and calcium compounds rank higher than sodium and potassium compounds, there is much more variability in quality for the former. Some calcium and magnesium buffers and alkalizing agents are relatively poor acid consumers, while others are quite good. Generally speaking, these are unrefined products and can vary based on the particular deposit from which they are mined. Potassium and sodium buffers and alkalizing agents are usually refined products and, as such, are more consistent in performance. Unrefined trona ore, predominantly sodium sesquicarbonate, tends to be less variable in performance than mined calcium or magnesium products. In general, products should be chosen based on consistency of measured results.

Quantities of buffers added to rations depends on a number of factors: rate and extent of rumen carbohydrate fermentation, quality and quantity of fermented feeds (such as corn silage) and passage rate are some of the most important. It is possible to calculate the amount of buffering required if ration composition and kinetics of rumen degradation are known.

Plant cell walls and starch are carbohydrates varying dramatically in rate and extent of rumen degradation. If one assumes rumen losses of plant cell walls are 40 percent, then for a cow consuming 50 pounds of dry matter (DM) with 28 percent plant cell walls, theoretical production of acetic acid, propionic acid and butyric acid from cell wall fermentation are 2.0, .90 and .80 pounds, respectively. Bacterial waste, as volatile fatty acids, are 3.7 pounds and .65 pounds of microbial cells are produced from 14 pounds of cell walls. If the same ration contained 35 percent starch and that starch was 90 percent fermented in the rumen, theoretical production from that portion of the feed yields 10.5 pounds of volatile fatty acid and about 2.0 pounds of microbial cells.

Rations higher in fiber require less acid neutralization partly because of higher salivary secretions and lower rates of acid production. Feed fiber, especially that found in legumes, can remove acid much in the same way a water softener removes calcium from water (ion exchange). Total ion exchange capacity of most rations is limited; the equivalent of a fraction of an ounce of sodium bicarbonate. Amounts of buffers added to the ration can be calculated based on ruminal acid production, salivary bicarbonate production and feed pH. Excessive acid neutralization can be as deleterious as insufficient buffering, as dissociated volatile fatty acids are not absorbed as well as undissociated volatile fatty acids. When rumen pH rises too high, absorption of volatile fatty acids across the rumen wall ceases, as will rumen fermentation. At a pH of 6.0, approximately 95 percent of acetic acid is dissociated, as are 93 percent of both propionic and butyric acids. It is interesting to note that volatile fatty acid absorption across the rumen wall is more rapid shortly after a meal, before salivary secretion increases.

Since estimates regarding production of volatile fatty acids and microbial cells have been made, a brief (unrelated to buffers) yet important discussion follows. Plant cell walls are important in overall rumen function; however, the role of rumen fermentable starch cannot be overemphasized. As can be seen from the previous example, the contribution of starch fermentation to microbial cell growth is much greater than plant cell wall fermentation. At amounts that might be found in a typical dairy ration, starch has the potential to grow three times the amount of microbes and nearly five times the amount of propionic acid as plant cell walls. The implications of this, as regards milk production, are clear.

Regulating blood pH

While rumen pH can vary over a broad range, blood pH does not. Under conditions commonly found in the rumen, acid content, as measured by pH, can vary 10 fold. Blood acid content is highly regulated and varies by no more than 10 percent from the average. Normal blood pH is 7.4; animals are alkalotic when pH is greater than 7.45 and acidotic when pH is less than 7.35. Metabolism must be altered to correct either condition as blood pH outside the range of from 6.8 to 7.8 results in death.

Regulation of blood pH is not as simple as the situation in the rumen. Hydrogen ions (acid) in blood are positively charged and in order to maintain a zero charge, one of two events must occur. Introduction of acid (positively charged) must be accompanied by the addition of a negatively charged ion (anion) such as chloride or bicarbonate, or the loss of positively charged ions (cations), such as sodium or potassium. Potassium, sodium and chloride are classified as dietary fixed ions; they are quantitatively absorbed from the gut, are not metabolized and excesses are excreted in urine.

Combustion of feed indicates effects on acid-base balance; ash from cereal grains is acid, while that from forages is alkaline. Cattle are much more tolerant of alkalosis than acidosis and, as such, require a slight dietary excess of positively charged fixed ions. The magnitude of this excess is determined by a number of factors including metabolic state.

Growth is a state when animals are in a negative acid balance; while catabolic states, such as starvation, represent a positive acid state. Acid-base imbalance affects multiple metabolic processes; among these are impaired glucose metabolism and transport of compounds across cell membranes. Ultimately, under prolonged conditions of acid-base imbalance, animal health and efficiency are reduced.

Modern management practices increase energy density to improve production, primarily with increased intake of cereal grains. Until recently, no attention was paid to acid-base balance in cattle. It has been suggested that benefits resulting from the addition of buffers, such as sodium bicarbonate, relate as much to fixed ion addition (sodium) as to acid neutralization.

Sodium, potassium, chloride, phosphorus, sulfur, calcium and magnesium are commonly included in equations describing dietary acid-base status. Phosphorus, sulfur, calcium and magnesium may warrant inclusion occasionally, but these are typically added to rations to satisfy requirements. Unlike sodium, potassium and chloride, absorption of phosphorus, sulfur, calcium and magnesium is variable and often low. Sulfur is a constituent of several amino acids, and as such, metabolic state influences the contribution of sulfur to acid-base balance. Equations describing dietary fixed ion differences must be predictive of acid-base balance across all metabolic states. In addition, the simplest equation describing a system is to be used in preference to a more complex one that does not increase accuracy of prediction.

Summary

Regulation of acid-base balance in ruminants is a more complex system than that in non-ruminants. To meet the demands of high production, feeds are included in rations that can disrupt ruminal and metabolic processes. Buffers are added to rations to mitigate negative effects of acids produced during fermentation on rumen health and function. Additionally, buffers allow blood pH to remain in a range that maximizes performance and animal health. PD

References omitted but are available upon request at

After several years of relatively cheap grain prices, corn and soybean prices have increased significantly. The increase is primarily due to greater demand for corn and soybeans to produce ethanol and biodiesel. Most economists suggest that these higher prices will be with us for the foreseeable future. Since other feedstuffs are typically priced to reflect the corn and soybean market, the cost of almost all feed ingredients has increased.

Since feed is the largest single cost in producing milk, most producers review their feeding program to see if there are ways to reduce these costs. Any changes made to rations should only occur after a thorough review of the feeding program and must take into account the impact a change could have on other aspects of the overall operation. This [article] will review factors that affect feed cost, methods for determining the value of byproduct feeds, review issues related to using byproduct feeds and provide some suggestions for dealing with feed cost over the long haul.

Factors that affect feed cost

Rations are formulated based on animal requirements and the quality of feeds available. In regards to animal requirements, higher-producing cows have lower feed cost per cwt. This is because maintenance requirements, the amount of feed required to maintain basic body functions, are diluted by higher levels of milk production. Because of this, it is still more profitable to feed for high levels of milk production even when feed costs are high. The key is to use a realistic level of production for formulating rations.

Forage quality is one of the biggest factors affecting total feed cost. As forage quality increases, less concentrate is required to provide the additional nutrients needed to support maintenance, milk production, reproduction and health. Considerable advances have been made by seed companies as they work to identify hybrids that not only yield well but are more digestible, so that the cow can obtain more metabolizable energy in support of milk production.

We also have a better understanding of the importance of timely harvest and forage processing to get the most out of our forage. Research has also demonstrated the importance of managing the forage during storage and feeding to prevent secondary fermentation of silage or deterioration of hay once it has been baled.

The factor most producers watch and talk about most is the cost of supplements, especially corn and soybean meal, as they are used to establish the price for most ingredients. Fortunately, there are a variety of feedstuffs available that can supply energy and protein in rations for dairy cows besides corn grain and soybean meal. The list of possibilities includes traditional grains and protein supplements as well as numerous byproducts from the production of food, fiber or fuel. There are also other unusual byproducts available in some areas that can be fed if the producer is set up to handle those ingredients. The initial attraction of byproduct feeds is their lower cost, but there are other factors to consider in addition to cost.

Most producers feed one or more additives which increase feed cost. Several additives have research data to validate their usefulness and document their potential to improve production or health. These additives when used according to directions provide a good return on investment and should be continued. However, there are additives on the market that do not have unbiased information to support their potential usefulness. Often these products are included in the ration because they may help solve a problem. The use of these additives should be critically reviewed as to their need and usefulness since they add to the cost of production and may not provide any return. No product, with or without research documentation, should be used as a Band-aid for poor management.

The same is true for certain ingredients as well. Remember:

•There are no magic bullets.

•If it sounds too good to be true, it probably is.

•No product can change the laws of science.

Determining the cost of feed ingredients

There are several methods for comparing the prices of byproduct feeds. Many ration formulation programs calculate the value of each feed ingredient based on the nutrient requirements of the diet and the nutrients available from ingredients offered. This method provides specific information for that particular situation, but most producers do not have the software to perform these calculations.

More commonly, producers use programs specifically designed to compare the value of several feeds compared to a reference feed such as corn and soybean meal. One program commonly used is the FEEDVAL program available from the University of Wisconsin (http://www.wisc.edu/dysci/uwex/nutritn/spreadsheets/FEEDVAL-Comparative.xls). This program calculates the value (price/ton) based on the dry matter (DM), crude protein (CP), total digestible nutrients (TDN), calcium (Ca), and phosphorus (P) contents of each feed compared with the test feeds (shelled corn, 48 percent CP, soybean meal, limestone and dicalcium phosphate).

The nutrient composition of the feeds can be changed to match the products available in your area as well as the percentage feed loss. The values for forages are expressed on a dry-matter basis whereas all other ingredient values are expressed on an as-fed basis. A second version of this program (FEEDVAL4) is available that calculates the value of feeds based on undegradable and degradable protein, TDN, fat, Ca and P content using blood meal, urea, tallow, shelled corn, limestone and dicalcium phosphate as reference feeds.

Both programs allow the user to compare a wide variety of feedstuffs based on their primary nutrient content. The program can also be used to determine the feeding value of home-grown feedstuffs. There are other similar programs available as well as similar functions in many of the ration formulation programs available today.

Producers should compare similar types of ingredients when selecting those they will ultimately use. If you are not sure how a particular ingredient would fit into your ration, be sure and consult your nutritionist before you purchase any new ingredient. Most nutritionists keep up with ingredient cost and can provide a considerable amount of help when looking at any new ingredient.

There are several listings of ingredient prices that can be accessed by the internet including the University of Missouri site (http://agebb.missouri.edu/dairy/byprod/). These sites are good for information, but you will need to contact a broker to get a delivered price to your farm.

The true cost of a feed ingredient may be different from what we initially paid. There are additional delivery costs for byproduct feeds that may not be included in the initial quote. If you must receive a semitrailer load of feed that will be fed over an extended time, you should include an interest cost on the money tied up in inventory. Shrinkage varies from 3 to 7 percent for dry ingredients and 15 to 35 percent for wet ingredients. Sometimes special storage or handling is required, compared to using a complete feed, and these costs should be taken into account. The major cost in this analysis is typically shrinkage and delivery cost when the feed is used in a normal time frame.

Nutrient form and balance

Most feedstuffs provide a combination of nutrients but are classified according to the primary nutrient provided. In most situations, it is desirable to include a mix of feedstuffs in the ration to help provide a more desirable balance of nutrients to optimize ruminal fermentation and health. For example, high-fiber energy supplements are useful for reducing the starch concentration of rations based on corn silage and supplemented ground corn.

For diets containing high-quality legume silage or high protein grass silage, protein supplements that contain rapidly degraded protein would not be desirable. However, there are other situations in which the use of urea or another source of degradable protein should be fed even though it may not be the least expensive protein source compared with soybean meal.

When byproducts are included in rations, we must be aware of the amount of phosphorus these ingredients add to the ration. With greater attention on nutrient runoff and its negative effect on the environment, we must consider the impact of overfeeding phosphorus and other nutrients on the long-term aspects of whole farm nutrient balance. Several byproducts have relative high levels of phosphorus, which is one of the primary concerns. If multiple feeds with higher-than- average concentrations of phosphorus are fed, the phosphorus content of the ration will be well above National Research Council (NRC 2001) recommendations. The long-term impact may be a limitation in the amount of manure that can be applied to your land – which could reduce any future expansion plans with the purchase of additional land.

Nutrient variation

When producers make the decision to use a byproduct, they also assume responsibility for quality control of that ingredient. Variations in the nutrient contents of byproduct feeds occurs because of differences in the variety of grain used for processing, fertility of soil the crop was grown on, processing method used by the plant to extract the primary products, blending of multiple byproducts together by the manufacturing plant and storage conditions.

The expected variation for some byproducts is greater because of the different types of processing in the industry. The variation in nutrient content in a byproduct is typically much higher for the industry compared with that from a single source. Processing methods used by manufacturers have changed greatly during the last decade. These changes allow the processor to more effectively remove the primary product (starch, oil, etc.) producing byproducts that have a different nutrient profile than that listed in many references.

For example, the processing methods used to produce ethanol have changed greatly which produce distillers – dried grains with solubles (DDGS) – with a different nutrient content than previously available. Part of this variation is due to a new generation of plants that have come on-line in the past few years that produce DDGS that are reported to have higher nutrient value than DDGS produced by older, more traditional ethanol plants.

Processing technology is constantly being refined to improve the extraction of primary ingredients. Researchers are also looking at ways to decrease the amount of nutrients such as phosphorus in byproducts, so that their use in animal feeds will improve whole farm nutrient balance and maintain water quality. Some processing technology being developed will allow the production of custom byproducts for feeding in the near future, which will be advantageous for dairy producers. For these reasons, producers should sample feedstuffs on a regular schedule to keep track of the variation and any change in nutrient content that may impact the nutrient content of the diet.

Quality issues

Another aspect of quality control is safeguarding against potential contaminants in the byproduct feeds. Normally, the raw materials used for manufacturing food are screened for mycotoxins and other potentially harmful contaminants before use, and the byproducts are safe for animal consumption as long as they are handled properly after they leave the plant. There have been a limited number of cases in the past where byproducts from non-food industry sources were contaminated, resulting in either the death of numerous animals or condemnation of the animals. Producers should ask about the quality control measures used by the manufacturer to safeguard against contamination of the byproduct with mycotoxins or other harmful compounds. As the production of biofuels increases, there may be situations where treated seed or fermentation products from other industries are used to make ethanol or biodiesel. The byproducts from these products could potentially be fatal to the animals consuming them.

Occasionally, there are unusual byproducts that may become available for use. Some examples include: candy, cocoa byproduct, fruit pomace, fresh vegetables or fruits, vegetable residues or other products that are not typically fed. In some cases, there isn’t any information available on the nutrient content of these feeds and the producer must run analyses before they can be included in a ration. Many of these products have handling issues (ex, individually wrapped pieces of candy), but other products may have some compounds (either natural or added during processing) that would limit their use. In these cases, the producer should seek the assistance of a nutritionist with experience in this area.

Energy supplements other than corn grain

Either you have already looked at replacing some or all of the corn in the diet or you will in the near future. Corn is fed primarily as a source of fermentable energy. The energy is primarily in the form of starch which is digested at varying rates depending on how finely it has been ground or how it has been processed. There are several byproducts that can be used to partially replace corn grain in the diet. Some of the primary byproducts to consider include: hominy feed, soybean hulls, bakery byproduct, citrus pulp, molasses, wheat middlings, brewers grain, corn gluten feed or distillers grain. The energy in many of these byproducts is primarily in the form of digestible fiber, but some byproducts contain processed carbohydrates or sugar in the case of bakery byproduct and molasses, which should be handled differently in the ration.

Another source of energy is to feed more fat from sources such as whole cottonseed, whole soybeans, tallow, animal-vegetable blends or inert fat supplements. When multiple products that contain higher concentrations of fat are fed, the total amount of fat in the diet must be limited to avoid any negative effects on fiber digestion, animal health and milk fat depression. Considerable research has been conducted on each of these and each has advantages and disadvantages. The amount of corn that can be replaced by one or more of these byproducts depends on the quality and type of forage fed, production level and feeding system constraints.

Distillers grains have received a lot of press recently because this is the primary byproduct from the production of ethanol. As pointed out previously, there is a good deal of variation in the nutrient content of distillers grains. Some plants have taken extra steps to produce a more consistent product and typically collect a premium for their distillers grains. Research has demonstrated that distillers grains can provide up to 40 percent of the total ration DM, but this is not practical for most dairies.

Besides containing relatively high concentrations of fat, distillers grains also contain high levels of phosphorus. Like other byproduct feeds that contain higher concentrations of phosphorus, high feed rates increase the amount of phosphorus in the manure which builds up in the soil. The long- term implications include lower application rates of manure to land and limitations on herd expansion without purchasing additional land.

Suggestions for dealing with higher feed cost

It is important to review all aspects of your feeding program from time to time, independent of feed prices. This review should address several questions including: what are the primary weaknesses of the current feeding program? Often the primary weakness is related to forage quality, feed bunk management or some other aspect that is preventing your cows from being as productive as possible rather than the ration formulation.

If cow comfort is not as good as it should be, the cows will not respond completely to any change in the feeding program. The same is true for all of the little things that should be done to make sure each cow has feed when she is ready to eat, cows have plenty of bunk space, unrestricted access to water, water is cleaned each week and there is a good preventative health program in place.

The DM content of any wet feeds (silage or wet byproducts) should be measured routinely and rations adjusted as needed. This will reduce some of the variation in the nutrient content of the final ration and keep cows on a more consistent diet. Sample forages and other home-grown feed and have them analyzed. Use the analysis to fine-tune your rations. Home-grown forages commonly have greater variation than purchased feeds, so it is very important to sample and analyze frequently. Fine-tuning the ration can make a difference not only in milk production but also the amount of purchased feed needed and total feed cost.

Review mixing procedures and information used for mixing rations with the feeder to make sure that the rations mixed are the same as those formulated. A misplaced decimal or transposed number can be very costly in both feed cost and lost production. Too often the feeder doesn’t understand (or forgets) the importance of adding the correct amount of each ingredient and the impact of a mistake on cow health and production on the bottom line.

Manage feedbunks to optimize intake. Old feed should be removed each day to prevent spoilage of new feed and encourage consumption. Feed should be pushed up several times a day so cows have access at all times. Provide adequate bunk space for each cow. Normal recommendations are for a minimum of 2 linear feet per cow and more for fresh cows. Adjust feeding amounts to minimize refusals. Normal recommendations are for 3 to 5 percent depending on how well you can time feed delivery. If feed refusals are primarily the fractions that are sorted out by the cow, the amount of feed offered probably should be increased, and there are opportunities for improving feed mixing and processing.

Dairy efficiency, the pounds of milk produced for each pound of DM consumed, is a good tool to help evaluate the effectiveness of a ration and economics. High-producing cows should have a dairy efficiency greater than 1.6, whereas the majority of the herd should average 1.5. Dairy efficiency is lower for late-lactation cows and during heat stress. Supplemental cooling should be optimized to maintain production and dairy efficiency.

Establishing production groups, when possible, allows different rations to be formulated according to need, reducing total feed cost. It may be enlightening to determine the value of the milk produced by each cow, either current daily milk or lactation average, and compare that with the current feed cost to see which cows are profitable.

Summary

As we look for ways of controlling feed cost in light of increasing corn and feed prices, it is important to remember the basic factors that contribute to total feed cost. A careful analysis of the total feeding program that includes forage quality, availability and cost of byproduct feeds, feeding management and cow comfort should be conducted routinely to determine where cost can be trimmed and feed utilization can be improved. Given the current push for developing alternative fuels from corn and soybeans, producers must fine-tune their feeding management to maintain profitability. PD

References omitted but are available upon request at

—Excerpts from 2007 Kentucky Dairy Conference Proceedings