High-producing dairy cows are most susceptible to metabolic diseases during the periparturient period. During the first few days of lactation, milk production increases more rapidly than dry matter intake (DMI). Maintaining high DMI is essential to attain optimal milk production. The prepartum diet, body condition score, and environmental and managerial conditions affect DMI. Postpartum disease events have an even greater impact on DMI. Objectives of this study were to determine the effect of adverse health events on DMI, milk production, bodyweight, reproductive indices and mature equivalent (ME) production of dairy cows.
Reduced performance from periparturient disease
Forty-eight multiparous Holstein cows from the University of Illinois dairy herd were monitored for the first 20 days of lactation. Cows calved between September 2, 1994 and February 9, 1995. Dry matter intake and milk production were measured daily, and each adverse health event was recorded. Disease events included milk fever (MF), retained placenta (RP), metritis (MET), ketosis (KET), displaced abomasum (DA) and mastitis (MAST). Bodyweight at calving and at approximately 20 days postpartum, average days open and services per conception were recorded.
Projected 305 day ME milk production and composition were determined at 60 days postpartum. Data from 46 of 48 cows were available for analysis. The mean daily DMI per cow was 20.9 pounds at the beginning of the trial, increased approximately one pound per day over the 20 days and averaged 42.7 pounds at the end of the 20-day period. Milk production averaged 65.5 pounds per day during the trial.
Bodyweight averaged 1,412 pounds before calving and 1,324 pounds at 20 days postpartum. The projected 305 day ME yields of milk, fat and protein at day 60 post-calving were 20,235, 677 and 623 pounds per cow, respectively. Thirty-one cows conceived, averaging 1.7 services per conception and 111 days open. Twenty-four cows (52 percent) had at least one adverse health event and 22 cows (48 percent) did not experience a postpartum disease event.
The prevalence of MF, RP, MET, KET, DA and MAST was 6.5, 21.7, 4.3, 23.9, 19.6 and 13.0 percent, respectively. Two cows had twins; one of which developed KET and DA. Of the three cows that had MF, one had RP and one developed MAST. Of the six cows that had MAST, two had RP, one had MF and one had KET. Cows were categorized as having no disease event (NONE), one or more disease events (EVENT), retained placenta and/or metritis (RP/MET), or displaced abomasum and/or ketosis (DA/KET). There were 22, 24, 10 and 13 cows, respectively, in each category. Mean daily DMI and yields of milk were determined for each cow and group. Group means were tabulated for bodyweight and reproductive indices.
Postpartum mastitis control
The primary environmental pathogens responsible for bovine mastitis include two types of bacteria: coliforms and streptococci other than Streptococcus agalactiae. While the contagious mastitis bacteria Staphylococcus aureus and Strep. agalactiae are transmitted by infected cows during the milking process, environmental pathogens are found in the cow’s surroundings and new infections primarily occur outside the milking parlor.
The duration of infection by environmental pathogens is shorter than for contagious pathogens. More than 50 percent of coliform infections have been shown to last less than 10 days and nearly 70 percent less than 30 days. Few coliform infections become chronic, with less than 13 percent lasting for more than 100 days.
Approximately 60 percent of streptococcal infections last less than 30 days, while up to 18 percent may become chronic and persist more than 100 days.The percentage of quarters within a herd infected with environmental streptococci at any one point in time tends to be low and seldom exceeds 10 percent, while typically less than one percent of quarters are shown to be infected with coliforms.
The rate of new intramammary infections by environmental bacteria is typically higher during the dry period than during lactation. New intramammary infection rates are highest in the early stages of lactation and decreases dramatically after the first 60 days in milk. Infections tend to be more prominent with each successive lactation.
The key principles for environmental mastitis control are keeping the environment clean and dry. Several opportunities exist to improve the environment of dairy cows and thereby reduce teat-end exposure to bacterial pathogens. Moisture is essential for bacteria to grow and may be easiest for dairy producers to control. Well-ventilated barns will remove excess moisture from the air and help keep the environment dry.
Keeping cows clean may require more effort on the part of the producer. Sand bedding is ideal for maintaining a clean environment. Sand does not support the growth of bacteria unless it is laden with manure. Properly designed and well-bedded stalls can go a long way in reducing teat-end exposure to bacteria. Daily maintenance is required in any housing system.
Fencing off pasture locations where cows tend to congregate will prevent muddy areas from becoming a source for environmental mastitis. Milking-time procedures, particularly udder preparation, can impact the amount of environmental mastitis. Teats should be clean and dry before machines are attached, and equipment must be in good working order. Milking wet udders may increase bacterial counts in raw milk and clinical mastitis cases.
Routine clipping of udder and flank hair will reduce the amount of bedding and fecal matter that may adhere to cows. Predipping with a germicidal dip before milking has been shown to reduce environmental mastitis by 50 percent. However, complete removal of the dip prior to unit attachment is critical to prevent adulteration of the milk supply. A timely, consistent udder preparation procedure, that all milking personnel follow, will assure thorough milk-out and may reduce mastitis problems.
Post-milking teat dipping and complete dry cow therapy have been the mainstay of mastitis control programs. Both are of limited value in controlling coliform infections, while some measure of control can be obtained for environmental streptococci. The notion that a teat dip has “residual” effects once the cow leaves the parlor must be weighed against the amount of bacterial exposure the cows will encounter in the stalls. Teat dips that provide a physical barrier have been reported to reduce new coliform infections and should contain a germicide to assure some degree of control over streptococci and contagious pathogens.
The majority of control efforts should be placed into reducing or eliminating teat-end exposure to environmental bacteria. Even so, there are some measures that can be implemented to raise a cow’s level of resistance to infection. Provision of a stress-free atmosphere for cows, particularly around calving, is essential for mastitis control, as well as high production. Stress has adverse effects on the cow’s immune system. Cows that are immunosuppressed are much more likely to contract mastitis and it may take longer for them to clear infections.
Many infectious diseases, such as bovine viral diarrhea, bovine respiratory disease complex and salmonellosis can cause severe immunosuppression. Reducing stress (including weather-related stress) and controlling infectious diseases will not only reduce the impact of environmental mastitis but may also lead to higher production levels.
Recent advances in vaccine technology have led to the development of a bacterin against the coliform bacteria, E. coli. Several field studies have demonstrated the incidence of clinical coliform mastitis was approximately 70 percent less in vaccinated cows compared with unvaccinated controls. The major benefit is the reduction in severity of the clinical manifestations of coliform mastitis (toxic shock and death).
The economic loss due to clinical mastitis has been estimated to be $107 per clinical episode. Losses due to decreased milk production and non-salable milk account for 84 percent or almost $90 per case. Use of the bacterin can be a cost-effective “insurance policy” for many producers. Dosing schedules should be planned according to label directions or under the supervision of a veterinarian. Staphylococcal and streptococcal “mastitis” bacterins have not consistently demonstrated beneficial effects.
Managing postpartum uterine infections
The postpartum uterine environment is in constant contact with fluid and tissue debris that can support bacterial growth. Bacterial contamination occurs in up to 90 percent of dairy cows during the first week postpartum. The outcome of uterine contamination depends on the number and virulence of the organisms present as well as the condition of the uterus and its inherent defense mechanisms.
Many different bacteria can be isolated from the early postpartum uterus. Most of these are environmental contaminants that are gradually eliminated during the first six weeks post-calving. Normal postpartum cows will resolve uterine infections by rapid involution of the uterus and cervix, discharge of uterine contents and mobilization of natural defense mechanisms (mucus, antibodies and white blood cells).
Cows with certain periparturient problems have reduced ability to control uterine infections. Excessive stretching of the uterus (such as twins or calving difficulties) or metabolic disorders can decrease uterine contractility. This leads to retention of fluid and membranes beyond the normal period, providing excellent media for bacterial growth.
Calving problems, retained placenta and metritis reduces the ability of uterine white blood cells to remove bacteria. The duration of infertility associated with uterine infection depends on the severity and duration of inflammation. Resolution of the inflammation occurs with time. In the normal cow, fertility is restored by 40 to 50 days in milk.
Retained placenta has been defined as a condition where cows hold on to their fetal membranes longer than 24 hours after calving. If the retained placenta progresses to metritis and is responsible for systemic signs including elevated temperature, lack of appetite and reduced milk production, then intervention may be required. Retained placenta/metritis complex is a multi-factorial disease. Factors that can contribute to uterine disease include shortened gestational length (abortions), twinning, infectious diseases, improper assistance during delivery, stress and nutritional imbalances from energy or protein deficiencies, phosphorus or vitamin A deficiencies and vitamin E or selenium deficiencies.
Overconditioned dry cows are at higher risk for retained placenta. Unbalanced dietary anion/cation difference leading to subclinical hypocalcemia has been associated with inefficient uterine contractility. Cows may be able to expel their placenta but uterine involution may be delayed leading to infection and inflammation. Reducing or eliminating these conditions will allow cows to start their lactation profitably.
Monitor, mark and record
The University of Illinois study previously described demonstrates that preventing or minimizing the effects of periparturient disease, thereby maximizing DMI in early lactation, has a significant impact on postpartum milk production and subsequent lactation performance. In order to minimize the adverse effects of postpartum disease, dairy operations must monitor recently fresh cows closely. Dr. Lynn Upham of Tulare, California and others have recommend that recently fresh cows be monitored for temperature, appetite and attitude during the initial 10 days post-calving. This postpartum monitoring program works well in conjunction with a 30-day fresh cow feeding program recommended by many nutritionists.
A modification of Dr. Upham’s program is presented below. This program has been modified to reduce the number of marker colors from 5 to 3 and involves a slightly different marking system. The advantages of a fresh-cow marking program are that farm personnel can efficiently monitor and mark fresh cows, and with minimal orientation, any farm employee can determine a cow’s health status at a glance.
Once a day, all cows in the fresh-cow pen should be caught in lock-up headgates after fresh feed is placed in the bunk. Farm personnel observe appetite, attitude and measure rectal temperature on all cows for the first 10 days after calving. All data needs to be entered into an efficient recording system. Signs are recorded and cows are marked accordingly. Green is used for “okay” status. Red is used for “treated or sick” status. Yellow is used for “monitored” status.
The flowchart (Figure 1) can be used for determining the color marking and treatment protocol. Marking begins forward on the left rump (nearer the hook bone) as viewed from behind the cow. Each mark denotes one day postpartum. The day-five mark crosses the previous four days (from hook toward the pin). Day-six mark begins on the right side in a similar fashion. On day eleven, if the cow has received green marks on the previous three days, her tailhead is chalked orange to denote that she is ready to leave the fresh pen at the next cow move.
Only cows with orange tail heads are moved from the fresh pen. Cows that have difficult calvings, milk fever or twins should receive a yellow mark on the first day, even if there is no fever or depression. Cows with normal temperature but depressed appetite or attitude may be candidates for ketosis or displaced abomasum.
On-farm treatment protocols need to be established for the various postpartum diseases. Treatment protocols need to be developed with the herd health veterinarian. Many of these treatments will undoubtably require extra-label uses, which necessitates a valid veterinary-client-patient relationship. Maintaining these records will help improve reproductive programs because cows with postpartum uterine problems can be identified and managed appropriately. PD
References omitted but are available upon request at email@example.com
—Excerpts from 2007 Midwest Dairy Expo Proceedings
Richard L. Wallace, Dairy Extension Veterinarian, University of Illinois