MANAGEMENT COMPONENTS

SECTION 4. LACTATING DAIRY COW CARE

The performance, health, and welfare of the lactating cow are reflections of the quality of care received at every stage its life. Performance depends on converting feed nutrients into milk. Over the last 20 years, milk production has increased markedly due to improvements in genetics, nutrition, milking systems, facility design, health programs, care, and management. The welfare and care of the lactating cows are critical for the success of the dairy and providing the consumer with a safe and wholesome dairy product.

Proper facility design reduces stress and provides for comfort, proper nutrition, and health of the lactating cow. Temperatures under 40^oF (4^oC) may adversely affect lactating cows. Cold stress symptoms in dairy cattle are difficult to observe. The cow adapts to the stress of cold weather by increasing appetite and diverting energy from milk production to producing body heat. A heavier winter coat also helps the animal adapt. Rain and fog do not directly harm the cow. However, mud in corrals increases the risk of mastitis, and frozen, crusty mud may injure the teats and udder. Cows housed in mud may have increased nutritional requirements for body maintenance of up to 20 to 50 percent.

Cow productivity can also be decreased by temperatures over 75^oF (24^oC) and is aggravated by high humidity. The heat-stressed cow eats less, and milk production is reduced. Signs of stress, such as panting or standing in water, are not obvious until prolonged exposure to extreme temperatures or humidity occurs. Heat stress is compounded when the temperature does not fall below 70^oF (21^oC) at night.

In the southwestern states, most enclosed dairy barns have open sides which provide for air flow. Barns that are not properly constructed and ventilated can accumulate heat, moisture, and gases. All of these factors can have detrimental effects on the cattle and dairy employees. A gap at the roof peak allows for the natural venting of warm air, moisture, and gases. Additional air movement can be provided by low-speed, high-volume fans.

Natural and electric lighting should be provided. Insufficient light in the barn makes it difficult for workers to observe and detect problems with the animals or the barn.

Freestalls

Freestalls are individual cow bedding areas where partitions orient the cow for comfort and sanitation. The typical dairy using a freestall barn does so to facilitate cow comfort and manure handling. Freestalls give the cow a dry and comfortable place to lie down for rest and rumination.

Freestall barns should have one stall for each lactating cow. Some operators may choose to provide more stalls to accommodate herd growth and to provide areas for subordinate animals to move away from more aggressive herd mates.

Freestalls should be designed and maintained for cows that are about 10% larger than the herd. Stalls that are too short or narrow make it difficult for the animal to rise. Some configurations may entrap the animal, resulting in injury or death. Stalls that are too long or wide allow the animal to move forward so that feces and urine are deposited within the stall and not in the alleyway. It is desirable to use excess bedding and devices which prevent the forward movement of the animal within the stall.

Animals will back into stalls unless the stalls are protected with so-called "back-out" devices. An arm or other device that contains a steel rod which moves upward as the cow rises is preferred. The rod or pipe must be heavy enough to encourage the cow to back out. Back-out control devices should be effective without creating a safety hazard. For example, the use of a heavy wire cable stretched tightly over the row of stalls is effective but can be dangerous.

The choice of bedding material is influenced by cow comfort, sanitation, waste system, disease risk, cost, availability, and farm maintenance. Bedding material should be dry, drain well, and not contain or support the growth of bacterial pathogens at a level that increases the risk of udder infection. Bedding material should be soft and resilient examples are: gravel, kiln-dried shavings, beach sand, and dried manure. The accumulation of feces and urine, along with the gradual reduction in bedding material, results in an uneven, wet, microbe-laden depression that increases the risk of udder infection and the potential for the animal to step on her udder as she attempts to rise. Bedding material must be maintained by removing wet or soiled material in a timely manner and replacing it with fresh material. Tractor mounted devices for smoothing bedding in freestalls are effective in helping to maintain a level surface for cows to lie on.

Cow mattresses consisting of coverings filled with ground rubber or other materials have been used with success on some dairies. They require less maintenance than traditional freestall bedding materials. If they are not designed correctly and comfortable for the cows, they may not be used as frequently. Cows should spend much of their non-eating, non-milking time lying down and ruminating.

Loose Housing

Barns, shades, and corrals form the loose housing unit for the dairy cow. Ideal loose housing provides thermal and physical comfort and minimizes disease. Facility design and size depend on cow numbers, climate, and waste handling techniques. Overcrowding often aggravates adverse conditions, such as excess moisture, accumulation of manure, or reduced ventilation. This can predispose the cow to health problems, such as mastitis and pneumonia, and increase the number of insect pests. Overcrowding also affects cow behavior and may reduce access to feed, water, or resting areas for some subordinate animals.

The recommended loafing space for each cow in loose housing is 40 to 50 square feet of roofed area, in semi-arid conditions. The recommended space in unpaved earthen exercise corrals for groups of 100 cows is from 500 to 600 square feet per animal. Corral space may be reduced to 100 square feet on paved lots. Guidelines for housing in cooler climates are 20 to 30 square feet of roofed area per head for small breeds, and 30 to 40 square feet per head for large breeds. These considerations are equally important for waste removal and cow comfort.

In semi-arid conditions, loose housing roofs are often 10 to 12 feet wide, with similar height dimensions, and oriented north to south to allow the sun to dry the bedding. Wider-roofed structures should be oriented to allow for maximum natural air flow. Haystacks and other large objects should not be located where they impede air flow.

Bedding materials in dry weather can be dirt and dry manure, with weekly scraping to facilitate drying and reduce insect breeding areas. Straw or sand are preferred wet weather bedding materials. Wood shavings and sawdust can harbor high numbers of mastitis pathogens if not kiln dried. Cotton stalks and gin trash are not permitted by the California Department of Food and Agriculture for bedding because of herbicide and pesticide residues.

To reduce slippage, surfaces in loose housing should include scarified concrete areas, 15 to 20 feet wide around water troughs, feed bunks, and entrances. It is advisable to score the surface perpendicular to cow traffic. Crisscross scoring gives better footing. Finely crushed rock is an alternative flooring; however, large pebbles which can bruise hoof tissue should be avoided.

Loose housing and corrals that are hard-surfaced generally require a 4 percent slope for proper drainage. Dirt lots may need a 4 percent slope or more, depending on soil type and rainfall. Surface pumping to remove storm water from a corral area can help reduce mud problems. However, corral scraping and excess manure removal before and after the rainy season are necessary.

Feed manger configuration, placement, and width per cow are factors in reducing stress and increasing comfort for dairy cows. Length of feeder space per cow affects time available to eat and amount of feed the bunk can hold. Cows are normally allowed 2 to 2 ½ feet of manger per cow. Feed mangers must be cleaned regularly. This is particularly important with high moisture feeds during hot weather, since they can ferment and spoil if not consumed.

Each cow should be offered a balanced ration that meets the nutrient requirements outlined by the National Research Council's Nutrient Requirements for Dairy Cattle (1989). These nutrients include energy, protein, fiber, vitamins, and minerals. Many digestive disorders can be prevented by not feeding more than 60 to 65 percent of the diet as concentrate ingredients. Careful management of the body reserves of dairy cows is crucial to efficient production because body fat is a necessary and important energy source for lactation in the first few weeks after calving. However, excessive body fat before calving is associated with increased metabolic diseases, calving problems, and culling. Body condition of cows and heifers should be evaluated regularly so feeding and management practices can be appropriately altered.

Commodity by-product feeds can economically be included in a dairy ration. Several factors need to be considered before a by-product feedstuff is fed. Many by-product feedstuffs contain high moisture levels which makes them prone to spoilage and will reduce palatability and quality of the ration. By-product feeds often vary in nutritive content and should be regularly assayed for their moisture, nutritive content, and pesticide residues.

Toxins produced by molds are called mycotoxins. When mycotoxins are consumed in small amounts, symptoms may be absent or be evidenced by reduced milk production and appetite. Cows may abort and, occasionally, die. Feed quality should be maintained by suitable storage conditions. The feeding value of moldy or spoiled feed is related to the extent of spoilage and the age and type of animal to be fed.

To prevent the ingestion of small pieces of wire, baling wire should be carefully disposed. Magnets on the chutes of feed wagons will catch iron debris. Care should be taken to prevent nails and other metal from falling into feed mangers. Rumen magnets should be administered to cows. Magnets stay in the reticulum and collect metal fragments to prevent them from piercing the rumen wall.

Water

Animals need fresh, clean drinking water for normal growth and production. A dairy cow consumes about five gallons of water per gallon of milk produced daily. Cows are particularly sensitive to water problems because of the large volume they drink.

Excess nitrate, salt, bacteria, algae, or chemicals can decrease consumption of water and cause adverse health effects. The sources of these contaminants may include septic tanks and dairy wastes. Elevated nitrate levels may affect reproduction, number of abortions, growth rate, respiration, and mortality. Mature animals can tolerate fairly salty water, up to approximately 3000 milligrams per liter total dissolved salts. Animals in late gestation that consume excessive salt may experience severe udder edema at calving. Excess bacteria and algae generally do not cause health problems but may contribute to decreased water consumption. Water troughs should be cleaned regularly.

General

Dairy cow management can contribute to many of the common and economically significant diseases. Common diseases include mastitis, reproductive tract infection, foot disease, and gastrointestinal problems. Prevention of disease requires a multi-disciplinary approach to management, including facility design and operation, nutrition, waste management, animal selection, and veterinary medicine.

Mastitis

Mastitis is the most common disease of the dairy cow. It results from a microbial infection of the udder where bacteria gain entrance via the teat openings. Subclinical mastitis is the most prevalent, and does not result in gross changes in the milk or severe abnormalities in the animal. However, subclinical mastitis may progress to clinical mastitis. Clinical mastitis results in reduced milk yield and is a common reason the cow is culled prematurely.

With clinical mastitis, there are observable signs of dysfunction. These include swelling and/or redness of the udder, discomfort, and abnormal milk secretions. In some cases of clinical mastitis, systemic disease such as diarrhea, loss of appetite, dehydration, and even death occurs. Some severely affected animals may become non-ambulatory and will require special handling as described in Section 7, "Care and Handling of Animals Destined for Sale or Slaughter."

The emphasis on mastitis control should be prevention. The keys are proper sanitation and management of non-infected and subclinically infected animals. Wet, manure-laden areas in the lactating and dry cow pens and bedding areas, and poor sanitation during the milking process increase the risk of mastitis. Udders should be clean and dry when milked. Teats should be sprayed or dipped with disinfectant after milking.

Foot Care

Healthy feet are important to the productive cow. Lameness will interfere with movement to the milkingfacility, obtaining feed and water, exhibiting estrus, and general health. Foot rot, laminitis, hairy foot warts, etc. can cause severe discomfort for the dairy animal and be a source of economic loss to the dairy. The first sign of foot rot is lameness that may involve one or more feet. In acute cases, lameness is followed by swelling of the foot, spreading of the toes, and an abscess above the hoof. If not corrected, the infection will spread deeper and infect the joints, resulting in chronic arthritis.

Feet should be trimmed at regular intervals to maintain proper foot conformation and prevent losses due to lameness. Management practices that help reduce hoof damage and avoid bruising will help reduce the incidence of foot disease. Proper drainage of all locations to minimize standing water also helps. Early detection and treatment will help minimize the incidence of foot disorders. Various types of foot bath solutions may be used to decrease the incidence of some foot diseases.

Switch Trimming and Tail Docking

Tails of milking cows may be carriers of fecal matter, mud, and other contaminants which become a nuisance in the milking parlor. It has been hypothesized that disease may be transmitted from pathogens carried on the tail to the employees and equipment during routine milking procedures. Although not documented, it is thought

that udder health and milk quality may be improved by minimizing contact with contaminated tails. To lessen the physical contact between the cow's tail and the milker the trimming of the switch or docking of the tail is sometimes utilized. The more common practice is switch trimming which involves the periodic trimming of the long hairs growing at the distal end of the tail. Tail docking is performed by placing an Elastrator band (similar to a rubber band) on the tail for approximately seven days, then removing the distal portion of the tail with a sharp, sanitized instrument. The majority of the tail is usually removed; however, a portion remains to cover the length of the vulva. Tail docking is not a routine practice on most California dairies with the exception of a small percentage of dairies using a parallel milking parlor.

Dairy management should seriously address the possible advantages of tail docking versus the loss in the ability of the cows to switch away biting insects, especially flies, the risk of infection, and the loss of the tail as a communication signal to herd mates and caretakers of behaviors such as irritability and pain. No data have been published to support the claims of improved milker comfort and health or better udder hygiene and milk quality (e.g. lower somatic cell counts) in cows with docked tails. Tail docking is illegal in some countries due to welfare consideration and trade policies.

Machine Milking

Machines with a partial vacuum are used to remove milk from the udder. Vacuum levels between 12 to 14 inches of Mercury are normal. Cows should have clean, dry udders before the milking machine is attached. Pulsators, regulators, air hoses, and liners require regular maintenance to function properly.

Lactating cows are moved and handled several times daily. The manner in which cattle are handled affects the safety and welfare of both the animal and the personnel. Cows are gregarious and do not like to be isolated. They are also creatures of habit and do not easily adapt to new situations. From an early age, cattle should be handled quietly. Pain should not be used as a motivator.

Alarming sounds and force may be effective in the short term but can result in cow behavior that is erratic, explosive, and unpredictable. Hydraulic systems used for operating stalls and gates within the milking parlor should be fitted with over-pressure relief valves to assure that the forces generated do not injure the cattle.

Well-designed free stalls with soft, clean bedding facilitates cow comfort.