Maintaining healthy herds is a priority in commercial dairies. Prevention, early diagnosis, and effective treatment of health disorders is required to improve cow performance and enhance longevity of the animals.

Most of the metabolic problems of the dairy cow happen during the first two weeks of the lactation. It has been reported that nearly 25 percent of the cows that leave the herds do so during the first 60 days in milk.

Dairy cows

Milk production and the incidence of purulent vaginal discharge in grazing dairy cows

Mercedes Gonzalez & Nuria Garcia

Pasture-based milk production systems are seasonal, requiring cows to become pregnant every 365 days to take advantage of fresh grass as an economic feed source. Grazing cows are more vulnerable to negative energy balance than cows in intensive systems since they are more likely to suffer nutritional imbalances, resulting in worse reproductive performance and lower farm profitability.

To strengthen economic sustainability, peaks of maximum grass growth during spring must be aligned with the highest animal requirements. The short time period (about 85 days) during which cows in seasonal grazing systems must conceive to maintain reproductive efficiency, leaves little room for delays, and therefore postpartum pathologies should be minimized.

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Dairy cows

Identification of clinical mastitis by using daily cow behavior and production data

Nuria Garcia

Mastitis remains one of the most important diseases in dairy cattle due to its negative consequences on animal welfare and productivity. Cases of clinical mastitis are generally treated without knowing the underlying cause of the disease, because current diagnostic tools are based on culture or PCR techniques, the results of which take at least one day.

More than 130 bacterial species have been associated with bovine mastitis, only 10 species or groups of species, however, are responsible for 95% of the infections. Most of these pathogens can be classified, into gram-positive (G+) or gram-negative (G-) bacteria depending on the characteristics of their cell wall. This differentiation is important to properly focus treatment, as infections caused by G- bacteria should not be treated with broad-spectrum antibiotics.

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Little calf

Relationship of serum calcium levels with health problems and milk production

Joaquin Ventura & Fernando Diaz

Calcium is a fundamental mineral for the proper functioning of the body. It has multiple functions, from structural in bones and teeth, to its participation in the transmission of nerve impulses, through its role in muscle contraction, blood clotting, the transport of various elements through cell membranes as well as many others.

This gives an idea of the number of disorders that can be triggered when calcium deviates from normal concentrations. A well-known example of the problems of below-optimal calcium concentrations in cows is post-calving hypocalcemia, it is however not the only potential health issue.

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Nostril

Risk factors for foot-and-mouth disease infection

Maria Villagrasa & Nuria Garcia

Foot and mouth disease (FMD), is a serious and highly contagious viral disease that affects livestock and has a significant economic impact; causes serious loss of production and, although most of the affected animals recover, they remain weak.

It is caused by a virus of the Picornaviridae family of which there are seven strains that are endemic in different countries of the world; each strain requires a specific vaccine. Infected animals exhale the virus that can infect other animals by air or oral route.

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Calf

Inactivation of bovine leukemia virus in bovine colostrum by spray-drying treatment

Alvaro Garcia

Enzootic bovine leukosis is caused by a retrovirus known as the bovine leukemia virus (BLV). There have been attempts in Europe to eradicate the disease by culling with Denmark and the United Kingdom having been successful.

According to the USDA, and due to its endemic nature, testing and culling seropositive animals may not be such a cost-effective control method compared with preventing its transmission. In the US this disease continues to be prevalent with more than 80% of dairy operations testing positive.

In South America it is also prevalent with around 10% of newborn calves infected, particularly during the first 24 months of life, and reaching almost 50% before first calving. Losses are also the result of up to 5% cow deaths related to a BLV-associated lymphosarcoma, with reported profit losses of more than $5,000 per animal.

Some experiments have demonstrated the presence of BLV in colostrum that helps prevent neonatal infection, others however, have also detected the virus and confirmed its infectivity by oral consumption. This has led to controversy as of the importance of colostrum as a source of protection against the disease.

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Cow

Lameness during the dry period increases transition diseases in dairy cows

Alvaro Garcia

During the transition period dairy cows are at higher risk of developing infectious and metabolic diseases that result from sudden changes in behavior and metabolism. Among these changes the reduction in intake in the weeks close to calving is likely to be the change with the most profound effect as predisposing cause for metabolic problems.

Relationship between dry matter intake, lameness, and the occurrence of metabolic diseases

Inadequate nutrient intake has been associated with common problems such as metritis, subclinical hypocalcemia and subclinical ketosis. To further complicate things a reduction in dry matter (DM) intake during the close-up period may prolong and aggravate the negative energy balance during the transition period through fat mobilization.

This increased metabolism in the adipose tissue and the liver causes a state of inflammation has been linked to higher occurrence of several of these per-parturient problems. Adequate nutrition is also fundamental to maintain hoof integrity and prolong productive life. Lameness continues to be the second highest reason of dairy cow culling in the U.S., right behind mastitis. Furthermore, lameness is considered among the best welfare indicators for dairy cattle.

Subclinical acidosis and its clinical manifestation, laminitis, may result from nutritional or even management errors. Inadequate amounts of dietary effective fiber can result from excessive grain supplementation, the presence of highly fermentable carbohydrates or changes in the fiber/carbohydrate ratios.

One other important aspect to assess the health status of dairy cows is body condition scoring. While subjective, it is still a very useful and practical visual assessment tool of the nutritional status of cattle with high percentages of repeatability attained with practice, both between measurements and scorers.

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Cows

Risk factors for bovine viral diarrhea virus infection in dairy farms

Lucas Pantaleon

Bovine viral diarrhea virus (BVDV) is a common disease in cattle which causes significant economic losses around the globe. The severity of the negative financial impact of the virus varies based on the immunity status of a given population and the pathogenicity of the viral strain. In populations that are susceptible to BVDV or the introduction of a highly pathogenic strain, understandably will lead to high economic losses in that herd.

In breeding cattle, the virus causes reproduction disorders (abortion, prolonged gestation, reduced fertility) and has a negative impact on productivity because of culling, morbidity, and mortality. The disease could manifest as acute, subclinical, and persistent infection forms. All forms of BVDV cause health issues in affected herds and lead to the presence of persistently or temporarily infected animals. The circulation of the virus in the population is facilitated by the variety of forms that the disease can take, regardless of the presence of high viral antibodies.

The spread of the bovine viral diarrhea virus in dairy herds

The virus can cross the placenta and cause infection of the fetus early during pregnancy, resulting in the birth of persistently infected (PI) cattle. The most important sources of infection are the PI animals. On the other hand, healthy adult cattle or calves that become transiently infected (TI) are normally of a minor significance with regards to disease spreading.

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Calf

Oral electrolytes to treat diarrhea can lead to hypernatremia in water-restricted calves

Alvaro Garcia

Diarrhea is the first leading cause of calf losses in dairy production systems. Affected calves soon become dehydrated and lose weight, and if not treated accordingly may soon die. A specific drug therapy to treat the causative agent should thus be accompanied by fluid therapy to reestablish the losses of water and minerals.

As a result, oral electrolyte solutions are very important when dealing with severe diarrhea in baby calves, with several types available in the market. These solutions may differ depending on the main intended purpose (i.e. isotonic solutions, electrolytes plus energy sources, etc.), and knowing which one to choose is critical for a prompt recovery.

The wrong fluid therapy can result in unbalances in the body electrolytes or even further losses aggravating the calf’s condition. One thing to consider however is that most milk replacers are made with cheese whey. As a result, these milk replacers have higher concentrations of sodium (up to 2% or 17–80 mmol/L). In addition, they also contain high concentrations of lactose ranging from 140 to 230 mmol/L.

This results in higher overall solids per liter of solution and greater osmolality resulting in more body fluid passing into the intestinal lumen. If in addition sugar (dextrose) and minerals (electrolytes) are added to the solution, then its osmolality can easily exceed 600 mOsm/kg.

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Dairy cows

Fasciolosis in dairy cows

Lucas Pantaleon

Fasciolosis in a zoonotic disease. The infection is caused by Fasciola hepatica and Fasciola gigantica flukes and juvenile forms affecting the liver parenchyma, as well as adult forms that migrate to the bile ducts. The disease is responsible for significant economic losses to dairy cattle producers, such as liver condemnation during slaughter.

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Drenching gluconeogenic precursors during transition impacts profitability

Alvaro Garcia

Healthy, productive cows are the cornerstone of profitable dairy farms, and it is the adequate management during the transition period that defines the overall lactational response and health of dairy cows. Changes happening during this period are the result of body changes, shifting hormonal balances, and nutrient requirements.

Hormonal changes during this period reduce appetite, which is combined with the fetus partially occupying the room previously destined to the pre-stomachs. The sudden onset of lactation right after calving leads to drastic changes in nutritional demands particularly to supply nutrients for colostrum and milk synthesis. All these changes result in the need of the cow to mobilize body reserves to account for the reduced nutrient intake.

From a biological response perspective, it is the mobilization of body fat stores that is the most impactful physiological change in the dairy cow. The appearance in blood of non-esterified fatty acids and subsequently beta-hydroxybutyrate are consequences of this mobilization. Excessive ketone bodies in body fluids, reflect this degree of fat catabolism, and contribute to reduced appetite and decreased milk yield.

Negative effects of ketosis

When ketone bodies concentration in blood exceed certain limits both subclinical and the clinical ketosis can manifest in cattle. One approach to improve this condition has been to artificially supplement gluconeogenic precursors to provide energy, without the need by the animal to mobilize fat excessively. It has been demonstrated that these precursors stimulate gluconeogenesis, increase plasma glucose, and decrease lipolysis.

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