The 100-day contract with the dairy cow: 30 days prepartum to 70 days postpartum

The concept of setting goals and time constraints is not new in business management. But how does it apply to dairy farm management? In evaluating the production cycle of the dairy herd, a 100-day period of critical importance exists. The ‘100 day contract’ with the dairy cow begins 30 days before calving and runs through first breeding to 70 days postpartum.

The terms of the contract include birth of a live calf with the cow remaining healthy during the transition period; high peak milk production; controlled loss of body condition and high fertility at first breeding. The momentum toward successful achievement begins in the close-up dry cow group and builds through calving to first breeding. Getting the cow off the track at any point disrupts the momentum and can lead to ‘wrecks’.

Wrecks include metabolic disorders during the periparturient period that can have a long-term impact on production and reproduction. This paper will focus on a phase by phase look at the negotiations required to successfully fulfill the ‘contract’ as well as the long-term consequences of cows getting off track.


The dry cow

The contract begins with the care and preparation of the prepartum dry cow. The concept of preparing the dry cow is different from the traditional view of the dry period as a ‘rest’ phase (Gerloff, 1988). The cow must be prepared for calving and initiation of lactation. Goff and Horst (1997) concluded that the periparturient period should adapt the rumen while maintaining normal calcium metabolism and a strong immune system.

Although not producing milk, the pregnant, prepartum cow is undergoing metabolic changes involving reproduction and new mammary growth.

Bell et al. (1995) measured energy and protein deposition in the uterus and fetus. Their research clearly illustrated the increased nutrient requirements during the final 30 days of gestation (Table 1). In short, there is a significant increase in metabolism of the cow during the final 30 days of gestation and therefore a need to maintain intake and proper plane of nutrition.


Table 1. Rates of energy and protein deposition in uterus and fetus during pregnancy in Holsteins¹.


¹Adapted from Bell et al. (1995).



ENDOCRINE CHANGES AFFECT INTAKE

With the approach of parturition, the animal undergoes a significant shift in endocrine balance and profile. Goff and Horst (1997) reported that cows experienced an increase in circulating levels of estrogen and cortisol.

Dry matter intake is affected by endocrine shifts and feed intake decreases during the last two weeks of gestation. Dry matter intake has been shown to decline by as much as 30 to 40%, from 2% to less that 1.5% of the animal’s body weight. Lower feed intake results in a negative energy status and mobilization of fat and protein. Severe decreases in feed intake put the animal at risk for a number of metabolic disorders.


PARTURITION DISEASE COMPLEX

Severe losses of body stores or a more general lack of properly balanced nutrients increase the risk of the animal experiencing a number of metabolic diseases. Markusfeld (1993) describes these as a parturition disease complex.

It is important to understand that these disorders are not independent but are related. A cow suffering from milk fever is at increased risk for retained placenta, left displaced abomasum, and/or ketosis. A number of other interactions exist among periparturient diseases.

Grohn et al. (1995) recently reported the incidence of these diseases for Holstein cows in New York (Table 2). As the median day of occurrence indicates, these diseases are most likely to occur during the period immediately after calving.

However, these disorders have an impact on production and reproduction during the entire lactation. Cows experiencing any one of these disorders are at much greater risk of suffering from a number of the other periparturient dysfunctions. Furthermore, these periparturient disorders disrupt the cow’s metabolic momentum toward high peak milk yields and also have negative carryover effects on reproductive performance.


Table 2. Lactational incidence risks and median days postpartum of disorders in 8070 multiparous Holstein cows in New York state¹.


¹Grohn et al., 1995.



Calving and subsequent reproduction

The culmination of periparturient disorders is lost production and income.

Markusfeld (1993) reported significant decreases in milk production and reproductive performance of cows suffering from postparturient uterine (PPU) disease (Table 3). The decreases in milk production and reduced reproduction efficiency associated with the periparturient diseases mean that incidence of these diseases must be closely monitored.

Retained placenta and related reproductive tract infections are often assumed to be caused by nutritional deficiencies. More specifically, since researchers reported the relationship between vitamin E, selenium and retained placenta, many producers first react to cows calving with retained placenta by increasing vitamin and mineral supplementation of the dry cow diet.

Correct vitamin and mineral supplementation is certainly a goal of properly managing the transition cow. French researchers, however, more completely described retained placenta as an under-nutrition disease. Chassagne and Chacornac (1994) reported that cows that retained the placenta were on a lower plane of nutrition. Blood metabolite measurements showed higher fat mobilization and lower blood glucose, as well as lower blood calcium and amino acids (Table 4). In addition, cows with retained placenta had lower circulating monocytes.


Table 3. Losses due to postparturient uterine diseases¹.


¹Adapted from Markusfeld, 1993.



Table 4. Measurements of blood metabolites and nutrients between normal cows and cows with retained placenta¹.


¹Adapted from Chassagne and Chacornac (1994). **P<0.05.



NUTRITION AND PERIPARTURIENT DISEASES

These results emphasize the importance of the overall plane of nutrition. A common limitation is the forage quality selected for feeding the dry cow herd. In addition, the feeding management system fails to promote feed intake in dry cows. Lower plane of nutrition results in excessive body weight losses and can disrupt energy metabolism.

Grohn and others determined ketosis was an important metabolic disorder compared to other diseases. Ketosis is related to disrupted energy metabolism. Simensen et al. (1990) reported peak levels of ketones in milk at 17 to 31 days after calving. There was a significant relationship between milk yields and increasing acetoacetate (a ketone) in the milk. As acetoacetate increased to levels >0.1 nmol per liter of milk, there was a significant decrease in milk production. Therefore, it has been established that early lactation cows suffering from ketosis have lower milk production.

Although not reported as often as other calving disorders, milk fever is a significant risk factor for several other disorders including retained placenta and displaced abomasum. Subclinical milk fever, ketosis, or a combination of the two can directly affect the chances of successfully accomplishing the ‘100 day contract’. Cornell researchers reported increased incidence of milk fever as lactation number and genetic potential increased.

These same researchers cited studies that showed decreased productive life by 3.4 years. Given that older, higher producing cows are most susceptible to these disorders, the economic impact of parturient paresis can be significant in lost production but also loss due to premature culling.

The concern of disrupted metabolism caused by ketosis and milk fever is the increased risk of other periparturient diseases. Curtis et al. (1983) reported that milk fever resulted in significant increases in the incidence of other transition cow problems. As illustrated in Table 5, milk fever led to increased risk of dystocia, retained placenta, left displaced abomasum, ketosis and mastitis.

Based on review of the literature, Coppock (1974) concluded that factors causing loss of muscle tone (atony) increased risk of displaced abomasum. These results were supported by a more current report by Massey et al. (1993) who found that milk fever increased the risk of a displaced abomasum 4.8 times.


Table 5. Influence of hypocalcemia on risk of other periparturient disorders¹.


¹Adapted from Curtis et al., 1983.



The often-overlooked aspect of displaced abomasum was the increased risk with the heightened stress of parturition. Other factors that Coppock identified as risk factors included toxemia due to metritis and mastitis.

Although the displaced abomasum can be repaired surgically, milk production is reduced by 8 to 10% compared to normal cows in the same herd.


NUTRITION AND IMMUNE FUNCTION

One key variable associated with transition cow health is the immune function.

Cai et al. (1994) reported that cows suffering from metritis or mastitis during early lactation had reduced immune cell function before calving.

Cows with retained fetal membranes had lower immune cell function for the first week postpartum. Immune cell function was also lower during the summer months of June, July, andAugust. These researchers concluded that neutrophil function could predispose the animals to periparturient disorders. Kehrli et al. (1989) found normal primiparous Holsteins suffered immunosuppression associated with impaired immune cell function. More recently, Kimura et al. (1999) reported that lower immune function could be associated with a shift in the phenotype of circulating immune cells.

Nutrients that influence immune function range from energy and protein balance to the micronutrients including vitamins and trace minerals.

Considerable effort has been invested in an effort to describe antioxidant balance in cattle during the periparturient period. Pryor (1976) reported that plasma zinc decreased more than 30% on the day of calving and first day of lactation. As lactation progressed, cows reached prepartum levels by seven days postpartum.

More recently, Goff and Stabel (1990) reported a much more severe decline in plasma zinc during the periparturient transition phase. Plasma zinc declined 67% with the nadir occurring at one day postpartum. Plasma retinol and a-tocopherol declined 38% and 47%, respectively. After calving, zinc, vitamin E, and retinol returned to near normal levels by 3, 10, and 14 days postpartum, respectively. The change in circulating antioxidants might be associated with secretion of these nutrients in colostrum. Kincaid and Cronrath (1992) reported that zinc concentrations in mammary gland secretions increased more than two times in colostrum compared to milk.

This transfer of nutrients into colostrum could be partially responsible for the reduction in circulating antioxidant nutrients.

Hogan et al. (1992) reported that supplemental vitamin E administered via parenteral injection increased circulating tocopherol. Cows injected with vitamin E had immune cells with a greater intracellular cytocide compared to cows receiving the placebo (80.1 vs 70.8, respectively). These results revealed that as circulating tocopherol increased, the intracellular kill of pathogenic bacteria also increased. The use of dietary supplements or injectable nutrient precursors may allow for the enhancement of immune function during the transition phase.


ANIMAL HOUSING, ANIMAL STRESS, AND THE PERIPARTURIENT COW

A growing list of research publications can now be summarized in stating that nutrition management is a key to successful completion of the 100-day contract. One factor critical to a successful transition cow contract that affects the success of the nutrition management program is the housing environment of the transition cow. The dry cow experiences a significant stress associated with the aforementioned transition.

The housing system is key to minimizing exposure to environmental stress. The following description can and should be applied to all animal housing systems, but is especially important for the transition cow. The housing system should protect the animal from injury and disease. This is especially important for the dry cow during late gestation. Harmon and Crist (1994) reported that the incidence of environmental mastitis is highest the first two weeks and the last two weeks of the dry period. Voermans (1997) recommended evaluating the housing system in terms of ability to reduce exposure of the animals to pathogens.

Furthermore, Voermans concluded that the important benefits of good housing in minimizing animal stress were manifested in improved immune function and increased resistance to challenge by pathogenic microorganisms. Clean, dry bedding is essential to improved animal health, especially in the periparturient transition phase.

The environment in which cows are fed is also important when evaluating the transition program and ability to successfully achieve the 100-day contract. Much has been written pertaining to the feeding environment of lactating cows; but comparatively little information is available relative to the periparurient cow. Adequate bunk space to allow all cows equal access at feeding time is important, as is the availability of water relative to distance from feed (<50 feet) and the number of animal spaces, In managing the transition cow group, there can be large fluctuations in the number of cows on a day to day basis.

The amount of feed delivered must be carefully monitored as group size changes when fresh cows are moved out after calving and late gestation cows are added. Age and body weight of the cows entering and leaving the production group will also affect the amount fed. These details of where and how feed is offered to the transition cow group can determine the success or failure of the early lactation cow.


Early postpartum cows

Prevention of metabolic disorders and diseases is critical to successfully reaching the 100-day contract. The second phase is to achieve peak milk and good fertility at first service. Miettinen (1990) reported that cows with higher levels of ketone bodies (acetoacetate and ß-hydroxybutyrate) had increased days to first service and decreased pregnancy rate and, as a result, longer days open with higher services per conception (Table 6). The results of this study from Finland illustrate the importance of minimizing metabolic disorders on reproductive efficiency.


Table 6. The effects of early postpartum energy status on reproductive performance¹.


¹Adapted from Miettinen, 1990.



NUTRITION IN THE POSTPARTUM COW: IMPACT ON REPRODUCTION

A common denominator among periparturient diseases is a reduced plane of nutrition. This poor level of nutrition is directly related to intake and energy balance. Energy balance during the periparturient period has a large impact on reproduction. Butler et al. (1981) reported that energy balance during the first 20 days was inversely related to days required to reach normal ovulation. These researchers also noted that normal ovarian function was observed 10 days after energy balance reached its lowest point and began to return to a positive balance. Lucy et al. (1991) reported similar results with an increased number of larger follicles present as estimated energy balance increased.

Another concern is the carryover effect of negative energy balance on fertility. Britt, from North Carolina State, has proposed that a period of negative energy balance influences the development and quality of pre-ovulatory follicles. In this case, cows experiencing severe body condition loss in the last weeks of gestation and/or early lactation will have reduced conception rates. Poor fertility would be due to an ‘imprinting’ of ovulatory follicles during development and recruitment of these oocytes.


Protein nutrition and reproduction

While the relationship between energy balance and reproduction has become better understood, the effect of protein nutrition on reproductive efficiency is less clear. During the last several years, the Degradable Protein System has been adopted for diet formulation for growing and lactating dairy cattle. The objective of this system is to provide sufficient soluble/degradable protein to maximize rumen microbial fermentation and growth, with undegraded intake protein supplying amino acids to the small intestine above microbial supply. This balance of protein types would prevent excess ammonia production in the rumen leading to elevated blood urea nitrogen (BUN) levels.

Several reports suggest that increased BUN levels cause increased levels of urea/ammonia in reproductive tract secretions. These nitrogen compounds could result in decreased viability of the sperm cells, ovulated egg cells and the embryo itself. Decreased fertility would result, with increased services per conception and days open. Serum urea levels in excess of 20 mg/dl have been reported as a means of evaluating the balance between degradable and undegradable in lactating cows. This figure must be used with caution as undegradable intake protein supplied in excess of the animal’s requirements will ultimately be converted to urea.

Research evaluating protein nutrition and reproductive performance is confounded with energy status of the animal. Higher protein diets will generally elicit a milk production response resulting in a more negative energy balance. Conversion of ammonia to urea by liver tissue also requires energy. In a number of research trials diets were reformulated by removing cereal grains and increasing degradable protein. This change in itself could influence energy balance of the cow.


Managing protein balance

Guidelines for the proper balance of protein types are determined by the types of feedstuffs and forages used. In general, 60-65% of the dietary crude protein should be in the form of degradable crude protein. Of the degradable protein, 40-60% should be soluble crude protein. Undegradable intake protein should make up 35-40% of diet protein. Although it is unclear if imbalances will adversely affect reproductive efficiency of dairy cows, properly balanced protein components of the diet will enhance production, improve efficiency and minimize incidence of increased blood urea nitrogen levels.


Minerals, vitamins and reproduction

Balancing energy and protein are critical in achieving maximum production.

Micronutrients, i.e., minerals and vitamins, are also important in achieving efficient and profitable levels of production. Several minerals and the fat-soluble vitamins have been associated with reproductive performance. Of the macrominerals, calcium:phosphorus ratios and total intake of the minerals are extremely important in preventing milk fever at calving.

Cows suffering from milk fever are more prone to retained fetal membranes, a prolapsed uterus and metritis. Therefore, dry cow nutrition management is important in prevention of these disorders and problems. Should a herd develop milk fever problems, calcium intake should be evaluated. Calcium intake should be limited to less than 75 g per cow per day. Phosphorus intake should be kept at a ratio of 1.5:1 relative to calcium. In the event milk fever problems continue, anionic salts can be used as an additional aid for its prevention. Anionic salt packs should only be used if correcting calcium intake fails to control milk fever.

Two microminerals associated with enhancing reproductive performance are zinc and selenium. The specific role of zinc in reproduction is not well defined but may indirectly result from the many functions of zinc in metabolism and immunity. Zinc supports tissue healing and restructuring that may be important in postpartum uterine healing. Zinc is also a component of enzyme systems that could influence hormonal profiles during pregnancy.

Selenium’s role in reproduction has been more closely evaluated. A number of published reports indicate that supplementation of selenium and vitamin E decrease the incidence of retained placenta, metritis and increase the rate of uterine involution. Vitamin E and selenium reduce tissue damage and function to maintain tissue integrity. This role of the micronutrients could enhance the uterine environment and support increased fertility.


Managing minerals and vitamins

Minerals and vitamins are added in small quantities, but it is essential that they be provided in adequate amounts to meet the animals needs.

Calcium and phosphorus intake should be closely controlled in the prepartum transition diet to supply less than 75 g of calcium, with phosphorus maintained at 1.5:1 ratio to calcium. Zinc, selenium, vitamin E and all other micronutrients should be balanced to meet but not exceed recommended levels. In some cases, additional vitamin E and selenium have been used in problem herds. However, extreme care must be exercised relative to intake.


Feeding system considerations

In addition, nutritional management is critical to achieving peak milk production to genetic potential. In doing this, many nutrition programs are designed to ‘lead feed’ or ‘challenge feed’ the fresh cow immediately after calving. In fact, many producers begin to accelerate grain feeding during the prepartum period. While the concept of this approach is correct, the implementation must be accomplished carefully. Excessive grain feeding can lead to ruminal acidosis, which can result in decreased dry matter intake and can predispose cows to other periparturient diseases. Acidosis can also result in laminitis in cattle (Vermunt and Greenough, 1994). These scientists report that systemic infections can contribute to laminitis.

For example, cows with severe metritis can develop laminitis in response to the systemic disease. Poor locomotion due to sore feet can result in significantly lower milk production. The largest incidence of lameness reportedly occurs during the first 50 to 70 days after calving, the period of peak milk production (Collick et al., 1989). Lameness also resulted in a significant increase in days to first service, days open and services per conception. The result of over-compensating with grain can actually be higher cull rates due to lowered milk yield and poor reproductive performance due to sore feet.


Summary

The ‘100 day contract’ is a series of delicate negotiations for the dairy farm manager. Unsuccessful negotiations at any point increases the risk of overall failure. The stress of calving must be intensively managed to reduce the odds of periparturient disease and increase the odds of success. Getting the details right and ensuring adequate intake of all nutrients are the key elements of the ‘100 day contract’.


References

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