A577
Nutrition for Lactating Cows -
Balancing a Ration, Dry Matter Intake, and Water

hand calculating a ration | the pearson square procedure | balancing lactating cow rations | balancing rations to reduce pollution | using a feed delivery system | maximizing dry matter intake to optimize milk production | tools to monitor feeding, production, and rumen health | water

Introduction: The use of computers has greatly changed and improved the way dairy cow rations are formulated. The process of hand-calculating rations is time-consuming, difficult, and cannot be used to calculate the complex nutritional formulas. Computers, combined with research and unique software, have allowed for a more complete evaluation of nutrients in a ration. Computers and advanced software have also enabled economics to become part of the ration balancing equation. There are 5 common ways that computers may evaluate and express ration information:

Introduction: Dairy cow rations are often formulated by first selecting a major feed source such as hay and silage. Then the nutrients these feed sources provide are compared to the requirements found in table #2. Finally, a supplement is added, when necessary, to meet the nutrient requirements that may not be met by the major feed sources. Energy can often be expressed as Total Digestible Nutrients (TDN) or as Net Energy (NE). Net energy is currently one of the most valuable ways of expressing energy. It can be used to express the energy requirements for maintenance (NEM), growth (NEG), or for lactation (NEL). Use the following tables and the equations found in the examples to help make adjustments to specific rations.

The information for this table has been taken from the Nutrient Requirements of Dairy Cattle, Seventh Revised Edition, 2001, National Research Council.

The information for this table has been taken from Hoard’s Dairyman Feeding Guide, pg. 79, Mike Hutjens, 1998.

¹  The 0.31 number comes from table #2 using the 3.5% fat content of the milk.

Step #2: Estimate the cow’s dry matter intake (DMI) by using the following equation:

DMI = (body weight in lbs X 1.8%) + (0.3 X lbs of 4% fat corrected milk produced)

For this example, the cow will be fed 6 pounds of dry matter alfalfa hay. This leaves 22 – 6 = 16 pounds of dry matter corn silage. The early bloom alfalfa hay being fed has tested as follows: Dry matter = 90%, Crude Protein = 18.0%, and NEL = 0.61 Mcal/lb. The corn silage being fed has tested as follows: Dry Matter = 35%, Crude Protein = 8.5%, and NEL = 0.70 Mcal/lb.

Step #4: Calculate the net energy provided by the alfalfa hay and corn silage to the cow. This is done by multiplying the Mcal/lb NEL of the alfalfa by the amount the cow is consuming. The same is done for the silage.

18.0% X 6 lbs = 0.18 X 6 = 1.08 lbs/day crude protein from alfalfa
8.5% X 16 lbs = 0.085 X 16 = 1.36 lbs/day crude protein from silage
1.08 + 1.36 = 2.44 lbs/day crude protein total from the alfalfa and silage

Conclusion: Based on the fact that the cow has a Mcal NE requirement of 25.88, she definitely requires additional energy. She has a protein requirement of 6.35 lbs per day. She is also in need of additional protein in her ration.

Step #6: Add additional energy and protein to balance the ration to meet her nutritional needs. In this example, shelled corn and soybean meal will be used to supply the additional needs. The shelled corn has components that test as follows: Dry matter = 88%, Crude Protein = 10%, and NEL = 0.94 Mcal/lb. The soybean meal tests as follows: Dry matter = 88%, Crude Protein = 58%, and NEL = 0.88 Mcal/lb.

0.52 X 11.1 = 5.75 lbs soybean meal on a dry matter (DM) basis
0.48 X 11.1 = 5.35 lbs shelled corn on a dry matter (DM) basis

Soybean meal: 5.75 lbs X 58% crude protein = 3.3 lbs crude protein
Shelled corn: 5.35 lbs X 10% crude protein = 0.54 lbs crude protein
Total protein from the supplements: 3.3 + 0.54 = 3.84 lbs crude protein

• Take the Mcal/lb NEL of the soybean meal and multiply it by the amount of soybean meal in the diet. Do the same for the shelled corn. Add both these amounts and the energy provided by the alfalfa hay and corn silage together. This gives the total energy in the ration.

1. Monitor Moisture Levels on Forages:
   1. When moisture in the total mix gets above 50%, the total dry matter intake begins to fall rapidly. Moisture can be measured with a Koster Moisture tester or microwave oven. It is important to adjust the amount of forage fed when the amount of moisture in the forage changes. This will keep the amount of dry matter in the ration consistent. A simple way to measure moisture content in a forage is to weigh 100 grams of forage onto a paper plate. Also record the weight of the paper plate. Place the plate with the forage spread evenly in a microwave oven and heat 4 minutes for wet forages and 3 minutes for dry forages. Remove, stir the forage on the plate, and record the weight of the plate and forage. Then heat the sample again, but this time for only one additional minute. Continue to stir, weigh, record and then reheat for 30-second intervals until the measures become constant. Be careful not to char the forage or start a fire. If the forage begins to char, decrease the heating time. To calculate the moisture percentage, subtract the last dry weight from the original wet weight. Then divide this number by the wet weight and multiply by 100. This is the moisture of the sample. If exactly 100 grams of sample was weighed onto the plate, the final dry weight (minus the paper plate) subtracted from 100 is the moisture content. Alternatively, the final dry weight is the dry matter percentage.
      
      
2. Specific Nutrient and Feed Ingredients Levels:
   1. Limit molasses to 2-5% of the dry grain mixture. Anything over 5% may cause clumping and bridging of grain mixes, and higher levels will reduce fiber digestibility.
   2. The maximum level of urea that can be safely fed to cattle is 0.4 lbs. per day if it is utilized well. Its utilization will depend on protein level, energy intake, ration ingredients, and the feed delivery system.
   3. Grain intake should not exceed 70% of the total ration dry matter. A safe guideline for total grain or concentrate would be 50-60% of the ration.
   4. Forage intake should be near 2% of the cow’s body weight. With excellent forage quality, up to 2.25% is possible.
   5. Energy requirements (NEL) during early-lactation are 0.78 to 0.81 Mcal/lb in early lactation. These requirements will change to 0.74 to 0.78 for mid-lactation and 0.65 to 0.74 for late-lactation.
   6. Limit total fat to no more than 7.5% of the total ration dry matter. When fat levels get too high they may interfere with fiber digestibility.
   7. When milk yield exceeds 5% of body weight, some form of undegradable (UIP) or bypass protein should be supplemented.
   8. At least 5 pounds of fiber over 1.5 inches long should be fed per day. Not having enough "effective" fiber may lead to acidosis, cows going off feed, and other health problems.
   9. Non-fiber carbohydrate in the ration should not exceed 45%. The optimum level would be 38-40%.
   10. Salt should be added to the grain mix at 1%, or fed at the rate of 1 ounce per cow per day plus 1 ounce for every 30 pounds of milk.
   11. A calcium-phosphorus mineral source should be included in the grain mix at 1-2% or fed at the approximate rate of 1 ounce per 10 pounds of milk.
   12. Supplement vitamins (A, D, E) and trace minerals in the ration to meet requirements of the National Research Council (NRC).
       
       
3. Body Condition Scores (BCS) should be carefully evaluated. Animals should have a score between 3 and 4 (on a 1-5 scale) just prior to calving. Animals that are too thin (BCS < 3) when they give birth will have weak offspring, not provide enough milk, and will take longer to heal reproductively. Animals that are too fat (BCS > 4) at parturition are at a higher risk of having dystocia (calving difficulty). Ideally, approximately six (6) weeks prior to calving, the pregnant cows should be sorted by body condition. This will permit additional feeding of supplements to those females with a low BCS. Those females with a BCS 4-5 should be placed on a diet with less energy. Depending upon the year, season, and cost of supplementary feeds, the females that are moderately heavy to heavy can be permitted to drop a BCS without compromising reproductive goals.

Introduction: The trend of the dairy industry has been to move to more consolidated, concentrated, and condensed systems and operations to increase productivity. As cattle are fed and housed in large groups on small areas of land, proper feeding, management, and waste-disposal programs become increasingly important to reduce environmental pollution. Feeding to reduce excreted nutrients, manure handling and storage, manure application to fields, and odor reduction are all areas that the federal government, through the agencies of the USDA and the EPA, are concerned about. Environmentally, the following nutrients are of primary concern:

1. Individual Component Feeding:
   1. Forage Based Systems:
      1. Hay: Traditionally, hay has been the way to deliver forage to dairy cattle. Advantages of hay is that it can be preserved well as a forage, if it is dried properly and stored in an area protected from weather elements. It is also easy to store and handle.
         
         Disadvantages are that weather may often cause field losses, harvest problems, and a reduction in product quality. Hay requires specialized harvesting equipment and there are significant costs of harvesting, storing, and delivery to the animal.
         
         
      2. Haylage: Putting up feeds as haylage has advantages over hay in that fewer days are needed to dry the feed before harvesting. This greatly reduces losses in the field during harvest. Haylage may be put up in bunkers, bags, baleage wraps, and upright silos.
         
         Disadvantages are that dry matter levels when ensiling are critical to ensure adequate fermentation. Abnormal fermentations, which may severely alter feed taste and palatability, are common when haylage is ensiled too wet. The harvesting and storing of haylage also requires specialized equipment and storage areas which may be of economical concern.
         
         
      3. Green Chop: This is the process of direct cutting and feeding of grass or legumes with no storage involved. Feeding in this manner has the advantages of no harvesting losses and the increased palatability of fresh feed. Disadvantages are that the forage quality changes daily, and strategic planning must be in place to maintain a steady and consistent supply of quality forage. In hot weather, green chop will heat and spoil rapidly, which will necessitate more frequent cuttings. This involves a significant amount of labor. Also, this type of feed is only available seasonally.
         
         
      4. Pasture: Having animals graze on pasture has the advantage of letting the animals do the harvesting of the forage. If grazing is managed properly, animals will have free choice access to quality, palatable forage. The disadvantages of grazing are that it requires close monitoring of pasture length and proper fencing (moving electric wires, etc.). It is also very seasonal in nature.
         
         
   2. Grain Systems:
      1. Individual Cow Grain System: This system is typically found in cows housed in stanchion or tie stall barns. The grain mix is fed individually to each cow, based on need and can be fed separately or as a top-dress on the forage of choice. The advantages are that it is a low cost and a simple way to feed to the needs of the individual cow. The disadvantages are that it is quite labor intensive and slug (eating too much, too fast) feeding of grain may occur.
         
         
      2. Feeding Grain in the Parlor: This method of feeding grain is common and has the advantage of encouraging cows to enter the parlor. It is a low-labor, moderate cost system to operate.
         The disadvantages are that it is difficult, if not impossible, to regulate the amount of grain fed to the individual cow. Some cows may milk out more quickly and be released before they have finished their grain. Other cows may choose not to eat all their grain and leave an extra portion for the next cow. Any grain feeding of over 5 pounds is slug feeding and may have serious consequences to rumen health. This type of feeding also produces more manure in the parlor.
         
         
      3. Electronic Grain Feeders: These feeders identify individual cows by an identification tag and then are programmed to deliver a predetermined amount of grain based on body size, body condition, and milk production. This system has the advantage of being able to provide the extra nutrients needed for high-producing cows. Grain intake can also be monitored, and cows off feed can be quickly identified. One disadvantage of this system is that it is an expensive system that must be maintained. It also requires a high level of management where the feeders must be adjusted constantly to the changing conditions and production levels of each cow.
         
         
2. Total Mixed Rations
   1. What is a total mixed ration? A total mixed ration (TMR) is a blend of forage, grain, and mineral into a single feed formulated to meet all nutrient requirements. It is fed as the only feed source for the cow. It is intended to be fed free-choice and formulated so that each bite a cow takes is perfectly balanced to provide the nutrients necessary for maintenance, to maximize milk production, and support pregnancy.
      
      
   2. What are the benefits of a total mixed ration?
      1. Cows consume forages and grains in correct proportions.
      2. Cows are less likely to sort or slug feed, which decreases the risk of digestive upsets.
      3. Dry matter intake and feed efficiency is improved.
      4. Less palatable feeds can be utilized because of blending and diluting in the TMR.
      5. There is potential to reduce labor required for feeding.
      6. Feeding TMRs allows for greater accuracy in formulating and feeding a ration.
         
         
   3. What are the disadvantages of feeding a total mixed ration?
      1. The investment of equipment for mixing and delivery is significant.
      2. TMRs do not take into account individual needs of cows, so cows may need to be grouped and moved during lactation.
      3. Feeding hays can be difficult because some mixers may not be able to mix it properly. Overmixing may also be a problem.

1. Feedbunk Management
   1. Assess Feed Refusals: The best time to assess refusal is 1 hour before the next scheduled feeding. The feed refused should be weighed and an appropriate action taken. It should also be compared to the consistency and nature of the regular TMR. Feed refusal that has more long stem forage and less grain and concentrate than the TMR indicates a ration that is being sorted. The refused feed may be disposed of, fed to other animals, or blended back into the next TMR. The feedbunk should be scored according to the amount of refusal present. A sample feedbunk scoring system is outlined below.
      
      

      Feedbunk Scoring System
      Score	Description
      0	No feed remaining in the bunk
      1	Most of the feedbunk floor devoid of feed
      2	Feed looks similar to delivered TMR
      3	Two to three inches of feed across the bottom of the bunk
      4	More than 50% of the feed remaining from last delivery
      5	Feed virtually undisturbed and >90% remaining
      0 = A score of 0 one hour before the next feeding means increase TMR by 5% 1 = A score of 1 one hour before the next feeding means increase TMR by 2-3% 2 = A score of 2 one hour before the next feeding means no change is needed 3+ = Investigate the problem and adjust accordingly Source: Batchelder, 1998

      
      

   2. Feeding Frequency: By increasing or maximizing the frequency of feeding and the number of times the feed is pushed up, dry matter intake can be greatly increased.
   3. Adequate Feedbunk Space: There should be adequate feedbunk space for all cows to eat at the same time.
   4. Accurate Measurements and Delivery of Feed: Scales should be used to provide an accurate mix and proportion of feed to each cow. The scales should be tested and calibrated regularly as required.
   5. Moisture Adjustments: A moisture tester should be used to monitor the changing dry matter content when ensiled feeds or green chop is fed. The dry matter should be tested regularly and the amount fed in the ration adjusted accordingly.
   6. Clean Feedbunks: Buildup of old feed, cobs from corn silage, and fines can lead to spoilage, sorting, and a decrease in dry matter intake. Feedbunks should be cleaned regularly to prevent this buildup, especially after feed has been rained on.
   7. Competition: Cows definitely have a hierarchy of social interaction. First calf heifers most often are at the bottom of the social totem pole and may get pushed away from feeding situations. They often have to wait for feeding opportunities, and this often leads to slug feeding or eating unbalanced, sorted feed. Ideally, first calf heifers should be housed and fed separately from older cows.
      
      
2. Forage Quality and Nutrient Density:
   1. Feed High Quality Forage: As a forage decreases in quality, it also loses energy density. When forages reach low enough energy densities, cows cannot physically eat enough of that feed to meet their maintenance and production requirements. It is always best to feed forages of high quality. A good rule of thumb is to feed forages with a net energy of lactation (NEL) of greater than 0.60 Mcal/lb.
   2. Low Quality Feed Reduces Dry Matter Intake: Cows typically will only eat 0.9% of their body weight as forage neutral detergent fiber. When forage quality decreases, forage NDF increases. When those NDF levels approach and exceed 0.9%, dry matter intake will decrease.
      
      
3. Avoiding Ration Ingredients or Levels of Ration Ingredients that Decrease Dry Matter Intake
   1. Fat: High levels of fat (over 7.5% total fat) can inhibit dry matter intake. The cow’s system monitors the fat intake in the blood, and when fat levels reach certain levels, it will cause the cow to reduce her fat intake. This will decrease her dry matter intake in general.
   2. Fuzzy Cottonseed: Fuzzy cottonseed should be limited to a maximum of 7 pounds in a ration. Dairy producers should also know the source and type of cottonseed they are using. Some cottonseeds accumulate more of the toxic substance gossypol. Some states require that all cottonseed be tested for gossypol. If the source or type of cottonseed being fed is not known, it should be tested for gossypol levels.
   3. Moldy, Heat Damaged, or Spoiled Feed: Many changes that affect palatability and quality may occur to feed between the time it is harvested and fed. Mold growth, heat damage, and an increase in ammonia or soluble protein from inadequate or slow fermentation may all contribute to loss of intake.
      
      
4. BST Response
   1. Dry Matter Intake Increase: After being injected with BST, cows will increase in milk production and also increase in dry matter intake. This increase in feed intake lags behind the milk response by 3-5 weeks. The reason some dairies fail to see expected BST responses is that feeding management practices fail to allow for this needed increase in dry matter intake.
      1. Feed Bunk Management: Cows on BST must have fresh feed available constantly. Feeding to an empty bunk or requiring cows to clean up all their feed before feeding again is a mistake. Maximum returns come when cows are fed consistently and when there is a 3-5% refusal left in the bunk. The refused feed should be monitored closely for signs of sorting and mixing, and feeding regimens adjusted accordingly.
      2. Ration Balancing: Rations should be balanced to support the increase in milk production associated with BST. High quality, palatable feed should be used in rations to promote intake and efficiency.
         
         
5. Cows Held Away From Feed
   1. The Milking Parlor: Cows that stand for more than 4 hours per day in holding areas and during the milking process may be limited in the amount of dry matter intake they can consume. They just do not have enough time in the rest of the day to consume the needed feed. High producing cows will be hurt the most by this limitation.
   2. Using Feeding Areas as Alleys: Some dairies use the feeding areas of milking pens as walk alleys for adjacent pens to get to the milk barn. The cows in the pen used for an alley are locked away from feed while the cows from the adjacent pen are taken to the barn, milked, and return. Adding this time to the time those cows are away from feed during milking may exceed the 4 hour limit, and they may be unable to meet their intake needs.
   3. Poor Feeding Management: Anytime feedbunks are empty for any extended period of time, cows desiring to eat are being limited on their intakes.
      
      
6. Cows in Hot Weather
   1. Feedbunk Management in Hot Weather: Cows seeking shade in hot weather will avoid the feedbunk until cooler periods in the day. Feeding only small portions during the hot periods of the day and larger portions in cooler periods will help. Cooling systems such as fans and misters over the feedbunks will also help.
   2. Balancing Rations in Hot Weather: In hot weather, a cow’s dry matter intake decreases by 20-40% and yet her maintenance requirement for energy increases. Eating patterns change to promote slug feeding (eating too much, too fast). Feed stability in the bunk decreases. Ration balancing becomes challenging for cows in these conditions. More energy dense, palatable, rations with high quality feeds are needed during this time. Care must be taken not to just juice up rations at the expense of a safe rumen balance.
      
      
7. Excessive Moisture or Nutrients in the Ration
   1. Moisture: When the total moisture in the ration exceeds 50%, dry matter intake can decline by 3-5%.
   2. Nutrients: When some nutrients are in excess, they produce high levels of metabolites in the blood, which may send signals to the brain that tell the cow to stop eating.
      1. Fat: High levels of fat in the diet are metabolized to Non-esterified Fatty Acids (NEFA) which, at high levels, will suppress appetite.
      2. Ammonia or Soluble Protein: Feeds high in protein, particularly fermented feeds, may have much of the protein in the form of soluble protein, degradable protein, or ammonia. When this enters the cow’s rumen it can be rapidly broken down into small proteins and ammonia. Excessive ammonia or other nitrogen compounds may enter the bloodstream and suppress appetite.
      3. Rapidly Fermentable Grain and Starch: When starch is present in high levels in the rumen, it is rapidly fermented into volatile fatty acids (VFA’s). These acids in excess may cause a drop in rumen pH, damage to the lining of the stomachs, enter the bloodstream, and cause suppression of appetite.
         
         
8. Transition Nutrition
   1. Feeding a lead feed, transition or close-up dry cow ration can do much to enhance dry matter intake in the early fresh period. Feeding energy in a stepwise fashion between the far-off dry period and the fresh period will help the cow acclimate to new feed and prepare for the increase in volatile fatty acid (VFA) production in the rumen. Small papillae line the surface of the rumen wall and aid in the absorption of VFAs. The transition ration is balanced and fed in a way that promotes the lengthening of these papillae. Thus, when the cow freshens, her rumen is prepared to take on the increase in VFAs she will encounter in the milking herd rations.

1. Particle Size Evaluation: The Penn State Particle Separator Box is used to evaluate the amount of effective (rumen stimulating) fiber in the ration. It consists of a box with 3 layers. The top part of the box is like a sieve with numerous holes ¾" in diameter. The second or middle part of the box is also sieve-like and has holes ½" in diameter. The bottom section of the box is an enclosed pan that traps whatever falls through the top two screens. A feed sample is collected, weighed, and placed on the top screen. The box is then shaken back and forth horizontally and then rotated ¼ turn and shaken again. This is repeated until the box has rotated 2 complete revolutions. The feed that has separated into the different levels of the box is then weighed and a percentage of the total mix is determined.
   
   Recommended amounts of forage and TMR left in each level of the Penn State Particle Separator after the separation process:
   

   Part of Separator	Corn Silage	Haylage	TMR
   Upper Sieve	2-4% if not sole forage	10-15% in sealed silo	6-10% or more
   	10-15% if chopped & rolled	15-20% bunker silo, wetter	3-6% focus on total NDF
   Middle Sieve	40-50%	30-40%	30-50%
   Bottom Pan	40-50%	40-50%	40-60%

   This table is taken from Heinrichs, Jud. "Evaluating particle size of forages and TMRs using the Penn State Particle Size Separator."
   
   

2. Feed Inventory: Maintaining an accurate feed inventory of forage and by-products helps plan feeding strategies and monitor feed costs and usage.
3. Computerized Feed Management Systems: Computer systems can be linked to feed trucks that will monitor errors in mixing, feeder errors, amounts to be fed per pen, and provide many other useful functions. This can be a valuable tool in making sure the ration balanced on paper is actually the one delivered to the cow.
4. Milk Urea Nitrogen (MUN): Milk urea nitrogen is a simple test that can be done on milk that measures nitrogen content. Levels can be used to evaluate protein feeding and how consistently rations are mixed. High MUNs may suggest that protein is being overfed or that an inconsistent mix has been delivered to one group of animals. Low MUNs may suggest that insufficient protein is being fed or that inconsistent mixing has occurred.
5. Butterfat and Protein: Milk butterfat and milk protein should be constantly monitored. Low butterfat tests may indicate acidosis, selective feeding, or excessive grain or starch in the ration. High butterfat tests may indicate inadequate ration balance, excessive fiber, or inadequate energy in the ration. High or low protein tests may reflect the protein supplementation.
6. Manure Consistency: Evaluating manure can be a helpful tool in spotting possible nutritional problems and identifying sick animals. Manure can be scored according to consistency, color, smell, and presence of feed particles. Thin, fluid, green manure that arcs on defecation may indicate a sick cow, a cow off feed, or a cow on pasture or green chop. Loose manure that splatters and has little form may indicate a fresh cow or cows on pasture or green chop. Manure that stacks up 1-1 ½ inches, dimples, forms 2-4 concentric rings and sticks to a boot is considered ideal and normal. Manure that stacks up 2-3 inches and is dry may suggest a dry cow or a low protein, high fiber diet. Manure that stacks over 3 inches and contains all forage indicates a very sick cow.
7. Cud Chewing: Cud chewing is an excellent way to evaluate rumen health and the adequacy of effective fiber in the diet. Cud chewing is variable and depends on many factors, but a good rule of thumb is that when cows are resting (not eating, drinking or being milked), 60% of the cows should be chewing. A cow should chew at least 30 times before swallowing. This suggests that there is enough long fiber.

1. Lactating Dairy Cows Need Water for Maintenance and Milk: Milk is 85 to 88% water. Any problem with water intake will have a greater and more rapid effect on milk production than problems with any other nutrient. Lactating cows need to consume approximately 1 gallon of water for every pound of dry matter they consume. Heavy milking Holsteins will consume up to 50 to 55 lbs. of dry matter per day. This means that their water consumption (which comes from both moisture in the feed and drinking) should be 50 to 55 gallons per day.
   
   
2. Many Things Can Affect Water Intake: A wide variety of factors can influence water intake. Some of these include the following:
   1. Water temperature
   2. Rate of feed intake
   3. Moisture content of the ration
   4. Size, volume, and placement of the water trough
   5. Social and behavioral interactions between cows
   6. Water flow rates
   7. Level of milk production
   8. Stray voltage
   9. Environmental temperature, humidity, wind velocity, and precipitation
   10. Water quality
       
       
3. Water Quality
   1. Freshness: Having unlimited quantities of high quality fresh water will maximize water intake.
   2. Temperature: Some studies have shown benefits to dry matter intake and milk production by chilling water, especially in summer months. Other studies found that some cows will consume only warmer water if given a choice. When chilling water for milking cows, it should be done on all troughs to prevent competition for one or the other.
   3. Salinity, hardness, odor, taste, and pH should all be monitored.
   4. Bacterial contamination: This can be a serious problem that may lead to an increased incidence of mastitis and systemic illness.
   5. Algae growth: Algae growth decreases the palatability of water and should be controlled in drinking water. Certain algae may also produce toxins that can be harmful to cattle and other animal species.
      
      
4. Testing, Monitoring and Ensuring Water Quality
   1. Water should be tested annually for levels of the following: Total dissolved solids, hardness, pH, nitrates, iron, sodium, sulfates, fluoride, and bacterial growth. Other potentially toxic substances that may be tested for, if suspected, are arsenic, barium, cadmium, chromium, cobalt, copper, and cyanide.
   2. Water Trough Design and Placement Should be Evaluated
      1. Near Feedbunks: Cattle like to drink right after eating. Watering troughs should be placed within easy access of the feed bunks.
      2. Size: To avoid competition, troughs should be large enough to handle the number of cows in the pen. A good rule is one water outlet per 20 cows in loose housing or one foot of linear trough space per 10 cows.
      3. Fill: When cattle are released after having been locked in head-locking stanchions for heat detection, breeding, or vet-checking, troughs are sometimes immediately drained. Other cattle must then stand and wait for the water to fill. Troughs should be long, shallow and have a rapid fill: long to accommodate many cattle, shallow to prevent stagnation of water, and rapid fill to allow many cattle to drink at the same time. The rate of fill is directly proportional to the size of the inlet valve. It is a better idea to increase the rate of fill than to just increase the size of the trough.
   3. Check for Stray Voltage: If the water intake appears to be adversely affected, all water troughs should be checked for stray voltage by a qualified technician.
   4. Watering Troughs Should be Regularly Cleaned and Checked for Function:
      1. Water troughs should be checked daily to ensure adequate function.
      2. Water troughs should be drained and cleaned regularly to prevent growth of algae, for removal of feed and fecal waste, and to ensure freshness of the water supply.

Some of the previous information can be referenced from the following sources:

• Hutjens, Mike, Hoard’s Dairyman Feeding Guide, 1998.
• Hutjens et. al, Applied Dairy Nutrition and Problem Solving Seminar #6, AABP Annual Meeting, Nashville, Tennessee, 1999.
• McCullough, Hoard’s Dairyman Total Mixed Rations and Supercows, 1994.
• Linn et. al., Feeding the Dairy Herd, Minnesota Extension Service, University of Minnesota, 1996.
• Young, Allen, Fate of Nitrogen and Phosphorus on Dairy Farms, Intermountain Nutrition Conference, 2002.
• Norell, Richard, Quality Control in Feeding Management, Intermountain Nutrition Conference, 2002.