Cows that are comfortable make more milk and stay in your herd longer than those that struggle to survive the system. Take some time to score your herd's comfort level in the following five areas at different times of the year. If you can improve low-scoring areas, you could have higher milk production and healthier cows.
1. Time Budgets
How hectic is a day in the life of your typical cow? Hopefully, it's routine, slow-paced and boring. Rick Grant, president of the Miner Institute, Chazy, N.Y., and colleagues have done some great work evaluating cows' daily time budgets. (Table 1)
Cows' daily chores include eating, ruminating, drinking, standing around, socializing, getting milked and resting, known as vitamin R. Humans take cows away from their chores so we can accomplish ours - cleaning barns and stalls and locking cows up for routine procedures.
The problem is that we only have about 3.5 hours, including lock-up times, before we start to change a cow's schedule. Unfortunately, resting time is the part of a cow's day that humans usually disrupt. Overcrowding stalls and excessive parlor hold times are two of the main "impositions" that reduce cows' available resting time.
Vitamin R is important to cows for many reasons:
■ It's their version of REM sleep.
■ They get their weight off their feet.
■ They ruminate more.
■ Resting may enhance mammary blood flow.
Grant calculates that the average cow needs 12 hours of resting time. But cows in the upper echelon perform better with at least 14 hours. Indeed, many of these higher performers have figured out how to manipulate their schedules to allow for a greater amount of resting time. They are often the first ones in the parlor, or they spend less time eating or socializing.
The short-term cost of violating the vitamin R requirement is approximately 2 to 3 pounds of milk per day for every hour of rest time taken from a cow. Longer-term costs of increased laminitis and decreased body condition and reproductive performance could be even greater.
Action Steps. Use the information in Table 1 to evaluate your cows' time budget. Then look for ways to reduce "imposition time" by splitting groups at milking, enhancing parlor routines and cow flow, and judiciously using lockups.
2. Stall Usage Indexes
It would be a crime if all of the effort placed on time management allowed for sufficient resting time, then your facility's stalls were uncomfortable or had a design flaw that made cows slow to use them.
Stall usage indexes provide an indicator of stall acceptance.
■ The cow comfort index -- the proportion of cows lying down in stalls -- should exceed 85%. It's usually highest one to two hours after milking.
■ Stall standing index -- the proportion of cows touching a stall that are standing -- should be less than 20%. Anything greater has been associated with abnormally long herd-mean standing indexes and increased levels of lameness. The best time to measure the stall standing index is approximately two hours before milking.
Action Steps. If your herd isn't meeting stall usage indexes, evaluate your stall design and surface and bedding levels. Refer to stall design suggestions presented in other articles in this section or check websites mentioned elsewhere.
3. Rumination Time
Rumination enhances saliva flow, providing buffers that act to neutralize acids produced by the microbial fermentation of feedstuffs. This, in turn, raises rumen pH, reducing the risk of rumen acidosis and laminitis and enhancing ruminal digestion.
Rumination is a process closely related to relaxation. Your cows are much more likely to be ruminating when lying comfortably, being milked or calmly waiting in the holding area than when they're stressed. More stressful times include cows' perching in stalls; being grouped, whether by management or because of heat stress; or being locked up for an extended time.
A Cornell study overcrowded stalls by 30% in a group of cows and compared their performance to a control group without any overcrowding.
The groups were fed the exact same ration. Rumination time was reduced by 25% in the overcrowded group.
What percent of cows lying comfortably in their stalls should be ruminating? Consider that the average cow ruminates for eight hours (Table 1). Suppose that one to two hours of rumination occurs outside of the stalls and six to seven hours while lying in them. You would expect to see 50 to 60% of the cows ruminating while lying in the stalls. (That's six to seven hours of ruminating in stalls per 12 hours of lying in stalls.) There are times throughout the day when the percentage of cows ruminating will be slightly higher or lower than this, but the average throughout the day should be 50 to 60%.
Action Steps. If your herd doesn't meet this percentage, evaluate stall design, bedding, overcrowding and ration characteristics.
4. Lameness and Hocks
Lameness and hock scores both indicate a herd's comfort level. You can most easily score lameness when cows are moving, such as walking to the parlor.
The prevalence of lameness is influenced by a number of variables - the major ones being stall usage and standing time on concrete, the ration, the footbath and hoof trimming programs.
You can best score hocks when cows are standing or lying down. Generally only one hock per cow is scored.
Inadequately bedded stalls often create hock problems. Cows kept in stalls deeply bedded with sand or separated manure solids, or on waterbeds with adequate bedding material typically have good hock scores. Stalls with mattresses and a minimal amount of bedding will produce elevated hock scores.
Many dairies have more hock problems during the summer if they can't keep some forms of bedding on mattresses when curtains are open and fans are running.
Action Steps. Evaluate lameness and hock scores in your herd at different times of the year. (Table 2) What are the most likely reasons for elevated scores? How can problems be corrected?
Floor designs should provide a surface that is readily cleanable, yet with confident traction for cows. Injuries can easily occur when housing floors are too slippery, and hooves can wear thin when floors are too rough.
Action Steps. Evaluate the walking surface in your facilities. Grooves in concrete should be 0.5 inches deep, 0.5 inches wide and 2 to3 inches apart on center. Typical grooving runs parallel to the length of the building and, ideally, it would be perpendicular to the direction of cow flow. The concrete surface should be smooth, while the grooves themselves should be cut at right angles and not have rough edges.
A diamond pattern, where grooves run parallel to each other at 4 to 6 inches on center, helps to provide traction when cows travel a variety of directions.
Softer rubber or well-grooved rubber belting can also be used to improve the floor surface.
6. Heat Stress and Bunching
Cows will group or bunch together when stable flies are biting and when they're heat stressed. It takes only a few stable flies to make cows bunch. Determine if flies are causing the bunching by walking through the cows, looking for swishing tails or tail stubs and the occasional fly on the lower part of legs.
The air movement in tunnel-ventilated barns will keep stable flies out, while frequent application of insecticides may be needed to prevent bunching in other types of barns.
Heat stress, a huge problem last summer, has multiple ramifications:
■ Milk production drops due to lower feed intake and cows' expending additional energy to cool themselves through panting.
■ Laminitis can result when uncomfortable cows spend more time standing on concrete, less time ruminating and altering meal patterns.
■ Reproduction suffers from altered follicular growth and development, impaired luteal function and heat-induced early embryonic death.
A cow's normal respiratory rate is about 50 breaths per minute (bpm), and her normal rectal temperature is 100 to 102 degrees. Respiratory rates are an earlier indicator of heat stress than rectal temperatures for the following reason: At first, a cow will increase her respiratory rate to maintain her temperature through greater evaporative cooling from her respiratory track. When heat starts to overwhelm a cow's ability to maintain her temperature by simply increasing respiratory rates, rectal temperature begins to rise.
In barns with inadequate cow cooling, respiratory rates increase about 1.5 bpm per degree as temperatures move above the upper limit of a cow's thermoneutral zone, which is approximately 68 degrees, depending on humidity levels.
Cows will exhibit increased standing as their rectal temperature moves past 102 degrees. Cows with rectal temperatures of 104 degrees will usually have respiratory rates of 100 to 115 bpm.
Action Steps. Keep all vital signs as close to normal as possible: shoot for maximum respiratory rates of 70 bpm and rectal temperatures of less than 102 degrees. These are your target goals to evaluate the effectiveness of your heat stress prevention program.
As a guideline, fans should be started when air temperature exceeds 65 degrees and run long enough into the evening to cool all cows completely.
7. Ventilation Management
Adequate air exchanges reduce airborne bacterial numbers, humidity levels, noxious ammonia and excess heat. Potential airborne pathogens survive for a much shorter time at lower humidity levels, between 55 and 75%.
Action Steps. Use the following guidelines to monitor air quality in naturally ventilated cold barns, those with minimal or no insulation:
■ In the winter, barn air temperature should not be more than 5 to 10 degrees above ambient temperature.
■ In the spring, summer and fall, barn air temperature should be equal to the ambient temperature if no evaporative cooling is used.
■ You need more ventilation if ammonia or other odors are evident.
Score your cows at different times of the year. What aspects of cow comfort are hurting your milk production? What can you do to improve cow comfort?
By Bill Stone
The Manager newsletter / Northeast DairyBusiness
Cornell University PRO-DAIRY
Bill Stone, a veterinarian, is a dairy herd management specialist with Cornell's PRO-DAIRY program.