Rick Grant
Department of Animal Science,
University of Nebraska, Lincoln, NE, 68583-0908,
U.S.A.E-mail: ansc801@unlvm.unl.edu
Take Home Messages
Introduction
The goal of every dairy producer should be to provide housing, feeding, and milking environments that promote cow comfort, milk production, and herd health. Cow comfort can make a difference of at least a thousand kilograms in rolling herd average milk production between herds with similar genetics and nutrition. As early as the 1960's, researchers realized the benefits of comfortable housing facilities for cow health and productivity. Albright (1) documented a lower incidence of mastitis, lameness, and injured hocks for cows housed in free stalls compared with those cows in confinement.
The successful producer will create a cow environment that minimizes stress, excessive competition for feed and water, and potential for injury and disease. Common herd health problems associated with poor cow environment and comfort include: mastitis, lameness, hock injuries, metabolic, and infectious disorders. A comfortable, low-stress environment is particularly critical during the transition period following parturition to promote rapid increases in feed intake and to minimize duration of negative energy balance (9).
The most important daily activities of a dairy cow, from a nutritionist's perspective, are:
For any dairy enterprise, the feeding management system must promote intense feeding behaviorby the milking herd. Researchers at Michigan State University (6, 7, 8) found that higher producing, older cows consumed more feed, ate larger meals more quickly, ruminated longer and more efficiently, and drank more water than lower producing, younger cows. To achieve this intensity of feeding behavior, the cow's environment must be such that it ensures cow comfort and health. This paper focuses on specific aspects of cow comfort and how it may affect health of the cow. As a nutritionist, I'm most concerned with any aspect of cow comfort that could compromise health and reduce intake and productivity of the cow. A truly profitable feeding program will encourage cow comfort, normal feeding activity, and normal social behavior by the milking herd. Intense feeding behavior results in maximum feed intake, optimum production and reproduction, and improved herd health (Figure 1).
Figure 1. Cow comfort and herd health from a nutritionist's perspective. The figure shows the relationships among the cow's environment, cow comfort, health, and feeding behavior. The nutritionist strives for maximum intake, but this cannot be achieved unless cow comfort and herd health are optimized by the components of the cow's environment such as free stalls, floors, feeding system, etc.
Floors
All walking surfaces should be skid resistant to reduce injuries, increase mobility to feed, water, and resting areas, and to encourage estrous activity. If you notice cows walking very slowly, or timidly, with rear feet spread wide, this could be a sign of poor traction. All concrete should be grooved to make it less slippery. Before placing cows on freshly poured and grooved concrete, be sure to smooth off rough or sharp edges to prevent hoof injury (10). On-farm observations of "new concrete disease", when cows are introduced to a new concrete surface, suggest that newly grooved concrete can wreak havoc on hooves. Instances of lameness, related to acidosis and poor feeding management, are often exacerbated when cows are moved from dirt to concrete, or from old concrete to newly poured and grooved concrete. Invariably, productivity of the herd suffers under these conditions. To prevent hoof problems related to new concrete, reduce the abrasiveness of new concrete. Beginning several weeks prior to introducing the cows into the facility, drag a 900-kg block of concrete with a tractor over the new and grooved alleys, lanes, and holding pens. Some farmers have used street cleaners to remove particles and dust sanded off during this process. This or similar approaches effectively sand off rough edges, without reducing the effectiveness of the grooving. An excellent point to consider is that if the floor is uncomfortable for people to walk on in bare feet, the same is probably true for the cow as well (11).
When allowed a choice, cows often prefer to stand on rubber belting rather than concrete. Consider installing rubber belting next to headlocks or post and rail feeding systems to promote dry matter intake (21).
Recently, on-farm experience has indicated the usefulness of using dry cows or heifers to "condition" a new facility prior to introducing the lactating herd. By having these animals in the facility a week or so before the milking herd, it gives the new barn a cow smell and puts some manure in the alleys. This technique recognizes the importance of accommodating normal cow behavior and facilitating cow comfort to reduce stress when designing the cow's environment.
Self-Locking Stanchions
Self-locking stanchions are used commonly in commercial dairies to restrain cattle for various management tasks such as: 1) artificial insemination, 2) pregnancy checking, 3) monitoring herd health, and 4) top dressing a supplement. The system can be abused, and thus compromise cow comfort and health, if cows are allowed to remain in the headlocks beyond the period of time actually necessary for the management routine. As part of a regional dairy management research project, Utah and Indiana researchers evaluated the effect of extended lock-up times on cow behavior, well-being, and productivity. In the Utah studies (3), cows were housed in an open free stall barn with self-locking stanchions at the feed manger. The effect of an extended lock-up period of 4 hours (7 to 11 am or 9 to1 pm) on stress response was measured during the spring (April-May, 12oC) or summer (July-August, 21.4oC). During periods when the cows were not locked-up, serum cortisol concentrations averaged 9.4 ng/ml during the spring and 13.8 ng/ml during the summer. When cows were locked-up for 4 hours, the corresponding cortisol values were: 14.7 (spring) and 22.9 (summer). Using cortisol as an index of stress, these researchers concluded that extended lock-up was more stressful during hot summer days vs. cooler spring days. These changes in serum cortisol were associated with an 8.5% reduction in milk production for cows that were locked-up for four hours daily during hot weather.
In the Indiana studies (2, 4), milk yield, milk fat, somatic cell count, and dry matter intake were unaffected by 4-hour extended lock-up. Unlike the Utah data, plasma cortisol, as well as neutrophil:lymphocyte ratio, mastitis, and other health concerns were not affected by extended lock-up times. Behaviorally, locked cows had elevated lying frequency during the remainder of the day, and grooming activity was greater throughout the rest of the day. Acts of aggression were greater during the period immediately following lock-up, which could negatively impact the critically important intense feeding behavior. Locked cows ruminated less throughout the remainder of the day following lock-up, although total daily rumination activity was unaffected.
Free stalls
Design and Dimensions
Properly maintained free stalls or tiestalls are the key to cow comfort on most dairies. Stalls should provide a clean, dry, and comfortable location to lie down. Properly designed free stalls includes consideration of stall bed, stall partition, and bedding material (14). Dimensions and design of the stall should allow the cow to stand up and lie down naturally. Recommended free stall dimensions are provided in several excellent publications including the Dairy Housing and Equipment Handbook (15) and the Guideline for Planning Dairy Free Stall Barns (11). An important consideration is "lunge space". When standing up, a cow must lunge either forward or to the side of the stall. If adequate lunge space is not available, cows will have difficulty in rising and may eventually stop using the stall altogether.
To determine if stalls are designed properly for cow comfort, consider the following:
If the answer to any of these questions is "yes", then the stalls are not as comfortable as they should be. Also, check for patches of rubbed-off hair and injuries to hocks and knees. These are signs that cows rub excessively on stall partitions or neck rails when rising or lying down.
Bedding
Straw, sawdust, sand, and shredded newspaper can all work well as bedding material. Unfortunately, for too many dairies the choice is often determined more by the manure handling system, and less by considerations of cow comfort. Any bedding used must keep the cows clean and dry. Keeping stalls well-bedded maximizes moisture absorption, adds resilience, makes stalls more comfortable, increases usage, and reduces potential for injury.
Most cows prefer a 4% slope from front to rear of the stall (10). The stall surface, with bedding, should be free of "potholes". Look for dirty switches, udders, and hindquarters. Many veterinarians suggest a "wet knee" test in which you kneel in the stall for 10 seconds; if your knee is wet, then the stalls are not properly maintained. The "drop knee" test, in which you crouch and then drop to the knees in the stall, will quickly tell you how truly comfortable the stalls are for the cows!
Stalls should be inspected daily and wet bedding removed. Improperly maintained free stalls not only reduce cow comfort, but increase the risk of mastitis and injury. In a study of 18 commercial dairy herds in Ontario, the use of rubber-filled mattresses was found to be superior to plain rubber mats (22). These researchers observed fewer cows lying in the alleys, cleaner cows, fewer hock injuries (9.2 vs. 29%), and lower somatic cell counts for cows with the more comfortable bedding surface. A point to keep in mind is that if stalls become too uncomfortable, cows may stand for excessively long periods of time causing fatigue stress and reduced milk production (18). If poorly placed brisket boards, stall dividers, or bedding boards cause injury or discomfort, fear may discourage the cows from using the stalls, or they may stand for longer periods of time before attempting to lie down and rest (5). A cow when lying down pumps 50% more blood through the mammary gland than a cow that is standing. Remembering the biological principle that it requires approximately 500 units of blood flowing through the udder for every 1 unit of milk synthesized, it quickly becomes apparent why resting activity is so important to the lactating dairy cow.
Ventilation
A ventilation system for a dairy facility should prevent high humidity in winter and heat build-up in summer. Free stall fronts and partitions should be open enough to allow air movement across the cow. Excessive condensation and moisture damage, especially on the roof, and cobwebs are often a sign of inadequate airflow. Other signs of poor ventilation include: air that smells of ammonia, excessive coughing, nasal discharge, or open-mouthed breathing by the cows (10). The cow's haircoat will be free of moisture in a properly ventilated building.
Milking Parlor and Holding Area
Cows should spend no more than two hours in the holding area (one hour or less is preferable). Cows will ruminate in the parlor and holding pen if they are comfortable and at ease. Research at Purdue University and University of Nebraska indicates that up to 50% of the cows in the parlor can be ruminating at one time when they are at ease with the milking routine and milking environment (Grant, unpublished data). If more than 20% of the cows defecate in the parlor, this could be a sign of discomfort or uneasiness. The milking system needs to be properly designed, installed, and maintained. When cows seem ill at ease in the parlor, stray voltage should always be checked as a possible cause. Milkers should be calm and reassuring as they handle and milk the cows. Cow movement to and from the parlor should be gentle and considerate to reduce stress. Several publications detail proper milking system design and maintenance to assure cow comfort and minimal incidence of mastitis (15, 16, 17).
Cow Comfort and Hoof Health
Lameness is the second or third most common reason for culling dairy cattle, and untreated lameness can lead to a 20% or greater loss in milk yield for the entire lactation (19). Several factors contribute to lameness including the cow environment, genetics, disease, and nutrition. Specifically, the following factors are associated with increased incidence of lameness: 1) poor feeding management, 2) metabolic and digestive disorders, 3) stress of parturition, 4) infectious disease (mastitis, metritis), 5) environmental stress including hard stall surfaces and lack of bedding, 6) excessive or insufficient exercise, 7) excessive body weight and body condition, and 8) cumulative stress during a lactation. The environmental factors which contribute to cow comfort and reduced incidence of lameness are often overlooked, and nutritionists instead focus mostly on nutritional factors. Raven (21), in an excellent text on cattle hoof care, wrote that lameness appears to be an "occupational hazard" of the dairy cow, especially with modern confinement housing systems.
Herd performance losses associated with lameness include: 1) reduced body weight and body condition score, 2) reduced dry matter intake primarily due to reduced mobility, 3) reduced milk fat secretion and fat:protein inversions related to ruminal acidosis, 4) decreased longevity in the herd, and 5) poor reproductive performance.
Laminitis can exacerbate natural stresses of lactation, especially during early lactation, and cause a reduction in dry matter intake that predisposes the cow to other metabolic problems such as ketosis and abomasal displacement (20). Ruminal acidosis sets in motion a cascade of physiological events that results in the release of histamine that then causes vasoconstriction, vasodilation, laminar destruction, hoof deterioration, and development of laminitis. A major point to keep in mind is that histamine is a chemical that is released naturally in response to stress. Consequently, any stressor, including an uncomfortable environment, can contribute to lameness, and more generally, immune system weakness. A weakened immune system can be associated with higher incidences of respiratory infections, high somatic cell counts, and mastitis, as well as lameness (19, 20).
While it is well known that carbohydrate nutrition plays a major role in the onset of laminitis (insufficient effective fiber, excessive nonfiber carbohydrate), environmental factors also play a substantial, if often overlooked, role. As previously discussed, the floor surface can impact hoof health. Dirt lots are more conducive to good hoof health than concrete, particularly rough concrete, and newly grooved concrete. Cows need to avoid wet environments, and high traffic areas should be kept clean, be properly grooved, and have proper drainage. Stalls should be kept clean, dry, comfortable, and be of proper dimensions. A Stall Comfort Index has been developed (21) in which the goal is to have 90 to 95% of the cows lying in the free stall during periods of idling. If less than 85% of the cows use the stalls, then there may be a problem in stall comfort or design. In general, clay bases are preferred by cows, although concrete bases may be made more comfortable by embedding of rubber tires. For stalls with concrete bases, bedding can double resting time in free stalls from 7 to 14 hours/day. When cows lie down for an adequate amount of time daily, not only is more milk potentially synthesized, but cows are placing less stress on the outer hoof (21) which reduces incidence of lameness as well. On-farm observations suggest that the most common causes of lameness in dairy cattle are: 1) too much time spent on concrete and the inability to lie down, 2) ruminal acidosis, and 3) the combination of cows on concrete being overfed (or misfed) starchy concentrates.
Other Management Considerations for Cow Comfort and
Herd Health
Stress of Parturition
Ten multiparous Holstein dairy cows were placed in individual calving pens at one week before expected calving date (13). After parturition, cows and calves were kept together for 24 hours to ensure maternal attachment. Separation of calves on day 3 evoked only a weak stress response by the cow as evidenced by small changes in heart rate, serum cortisol, and transitory vocalizations. After separation, cows went to a feed gate and began active feeding. Removal of the calf had a negligible effect on its mother's feeding behavior; presumably even less when the calf is removed within hours, as is commonly practiced.
Exercise
Results of exercise studies in dairy cattle have been equivocal (9). A recent study by Gustafson (12) found no difference between exercised or nonexercised dairy cows in feed intake or milk production. However, the need for veterinary care during the first two weeks of lactation was greater for the nonexercised cows. These same cows were also more afflicted by calving-related disorders and leg problems. Negative health effects became more pronounced with advancing age of the cow.
Summary: Relationships among Environment,
Cow Comfort, Health, and Feed Intake
As illustrated in Figure 1, the cow's environment plays a substantial role in determining cow comfort, and subsequently the cow's ability to express intense feeding behavior and achieve maximum feed intake. Cow comfort also impacts herd health, and therefore feed intake, and will substantially determine performance of the dairy herd.
References