Mastitis is your enemy when trying to improve Fertility Rates’

Источник: The DairyNews
One can observe many positive trends in the Russian dairy industry. Some of our better farms are producing almost three times the national average in milk production per cow per annum, while the European agricultural products import embargo, attractive subsidies on cow purchases and partial interest reimbursements have brought enthusiasm to the sector. Elsewhere, one can observe nationally dramatic improvements in milk parlour protocols, herd management practices and fodder quality and apportionment during growth and lactation.
Mastitis is your enemy when trying to improve Fertility Rates’
Unfortunately, our best milk producers still lag significantly behind, for example, Danish producers in terms of annual milk production. In many European countries, regular monitoring of cow health and milk quality as part of Dairy Herd Improvement (DHI) has worked successfully for nigh on three decades. The latter is built upon the establishment of long-term partnerships between producers and processors. On-going improvements in Milk Quality and Milk Quantity are the underlying focus of DHI and economic justification for the measures implemented. Today, one average Danish cow produces more milk in one year than three Russian cows! Why ?

As in all industries, improved efficiencies in cost and time of production result from regular monitoring a variety of parameters, which are then optimised for overall performance. DHI over time on individual farms is based upon this very same principle. Here, the importance of access to Centralised Milk Testing on a monthly basis for each cow in the milking herd cannot be trivialised.

Alarmingly, two features continue to characterise many Russian dairy herds:

1)    Unusually high rates of clinical and subclinical mastitis; and
2)    Unusually low conception rates.

The question arises:

Are these two phenomena linked as cause and effect or entirely independent of one another? 

Internationally, one cow suffering from clinical mastitis usually equates to approximately 30-40 cows within the same herd suffering from undetected sub-clinical mastitis.  When this equation is used in a Russian context, it quickly becomes evident that the numbers of animals suffering from sub-clinical mastitis is a major problem, is indeed endemic in most of the herd animals and is not given sufficient attention. Treatment of both clinical and sub-clinical mastitis by traditional antibiotics is a long-term process focused on treatment during Drying-Off and exclusion of animals with clinical mastitis from the milking herd. This problem is further exacerbated by the high incidence of Antibiotic Resistance among the bacteria responsible for causing mastitis in the Russian milking herd. This is not the result of antibiotic over-use inside Russia, but rather the importation of antibiotic-resistant bacterial strains that accompanied the importation of high-quality milking livestock into Russia in recent decades.

Increasingly much of Russia’s milking herd is based upon Holstein-Friesian ‘Super Cows’. These animals represent highly-tuned milk-producing machines that have been selected over many generations and are now common within the dairy industry internationally. Like thoroughbred race horses, these ‘Super Cows’ are far removed from their wild ancestors and are thus more vulnerable to adverse husbandry conditions, damp, cold, poor bedding, infection, variations in feed quality, etc. Thus, the modern dairy farm endeavours to monitor and optimise most of these conditions for each cow and thereby maximise the Quality and Quantity of Dairy herd milk production.

Returning the above central question.....

If the reader is asked to run 400 meters while suffering from an infectious disease, such as the common cold or influenza for example, one can expect poorer performance than when healthy. If this analogy is transposed to a dairy cow, the question should be asked: While unnaturally infected with large populations of mastitis-causing and mastitis-related bacterial species, is my cow more or less likely to conceive or not? In principal, a healthy ‘Super Cow’ has been bred over generations to resist mastitis, produce high quantities of quality milk and spend most of its life pregnant. These animals are remarkably good at delivering these attributes as preferentially selected by their genetic heritage, even when subjected to sub-optimal conditions. However, Russian dairy herds in general see far too much mastitis each month of the year. If one takes, the number of animals that suffer from one or more bouts of mastitis during a lactation cycles during a given year and multiple by just 3-4 (not 30-40), the number obtained is often greater than the total herd size. Mastitis is far too often endemic in Russian Dairy herds. Measures need to be taken to reduce the incidence of a disease that should normally be seen only on older cows and rarely, if ever, in First Lactation animals.

First Lactation cows suffering from clinical mastitis is unfortunately encountered too frequently inside Russia and represents huge lost earnings. Mastitis events severely compromises the ‘Return On Invest’, inclusive of the cost of producing the grain and pasture employed to feed these animals throughout their lives and labour on farm and in dairy.  ‘Super Cows’ have been imported at great cost or reared over 18 months at great expense before entering the dairy herd.

First lactation mastitis results in:

1)    Significant milk production losses during current and all subsequent lactation cycles throughout the life of the animal;
2)    An increased likelihood of re-infection;
3)    A source of mastitis contamination within the herd;
4)    A cause of some animals being withdrawn from the dairy herd permanently; and finally
5)    Lower conceptions rates.

There exists a bulk of scientific evidence that suggests lower conceptions rates can be caused by mastitis infections. Why? Mastitis is caused principally by Staphylococcus aureus (the same species that causes significant loss of life in hospitals internationally), Streptrococcus agalactiae and Streptococcus uberis. Once these causative infections have established themselves in one or more quarters of the udder, infection results in the destruction of milk-producing tissue. Tissue destruction (dead and decaying cells) then allows a plethora of other less invasive bacterial species to colonise the infected quarter and in turn produce symptoms that allow increased transmission of the disease within the milking herd. For example, ‘pus’ dripping from the infected teat can be transmitted by insects, the milking parlour, bedding and easily to other quarters of the same udder. This is a catastrophe for the milk producer. Furthermore, although clinical mastitis produces visibly discoloured ‘milk’ and a positive reaction to the California Milk Test, sub-clinical mastitis is being transmitted continually within the herd, unnoticed by the dairy farmer.

Mastitis infection is characterised by large populations of bacteria in the infected udder quarter. In Austria, for example, bacterial counts are less than 25,000 per millilitre and regularly less than 10,000. Such bacterial counts in herd milk are rare in Russia. Some European cheese producers, notably French and Italian, refer to this as ‘sweet milk’ and allows the production of high-value cheese varieties rarely produced in Russia. The bacterial populations giving rise to mastitis produce toxins and / or stimulate cytokine production in the lactating cow that are known to depress ovulation. These toxins are produced by bacteria when they are alive and also as they die and degrade. The same toxins can also produce fevers which in turn suppress ovulation.

The exact nature of the immune system response induced by bacteria involved in mastitis has been well studied, as have the effects exerted at the level of the hypothalamic-pitutary axis, ovary, reproductive tract and embryo. For example, Interferon-alpha is known to reduce pregnancy rates in cattle, increase body temperature, inhibit secretion of luteinising hormone and reduce the levels of circulating progesterone. Other mediators that are affected include Interferon-gamma, Tumour Necrosis Factor-alpha, prostaglandin F-2 alpha, Interleukin-1 beta, Interferon gamma and Nitric Oxide - all of which are known to directly affect the reproductive biology of dairy cattle. Their exact effects will not be detailed further here. Numerous other immune modulators also influence the normal physiology of the dairy cow. None is ideal if one is wishing to optimise fertility and justify the additional cost of sexed semen, for example.

Some of the more convincing data in this area comes from a ten-year study conducted on 758 cows in Tennessee, USA of which 326 Developed Mastitis at one time or another. The study was concluded in 1998, but evidence based on such a long time frame adds to its validity.


With good reason, mastitis has been named the “Enemy of reproductive success”. Mastitis is known to interfere with postpartum ovarian function including ovulation, fertilisation, implantation, and pregnancy maintenance. Economic losses vary between herds, but generally include milk production losses, increased treatment costs and culling / removal from the herd. The keratin plug characteristic of cows during drying-off  is slower to form and more likely to leak milk. Infection of dams has also been linked to increased concentrations of circulating anti-Müllerian hormone 12-month-old heifer progeny, which equates to reduced fertility in next generation cows.   

More recent data are equally compelling:


An Ontario study based on some 4,555 breedings showed conception rate reduced from 48% to 38% if mastitis event was noted within 30 days of breeding. Similarly, in Israel, mastitis has been shown to provoke a significant reduction in first insemination conceptions post partum following observation on 4,500 cows over 18 months. The above trends are repeated in innumerable scientific studies internationally and can today be taken as irrefutable evidence of mastitis being linked to a reduction in reproductive success.


Figure: Clinical and sub-clinical mastitis severely compromises the overall health and fitness of the dairy cow and can result in 500 to 1,000 litres of lost production per animal per year.

Improved mastitis control must commence with improved individual cow health and milk quality monitoring on a monthly basis in conjunction with Centralised Milk Testing. Part and parcel of this process is the need to link these enhanced testing procedures with appropriate intervention strategies for mastitis control. Without recourse to such measures, the Russian dairy industry will continue to suffer from alarmingly high levels of mastitis infection and most probably poor conception rates in most of the herd. Some evidence exists to suggest that up to 20% young heifers are already infected with mastitis causing bacteria before actually entering the milking herd, but this alone is far from the principal cause of endemic mastitis infection. It is noteworthy that in many Russian milking herds, the bulk of first lactation animals are succumbing to clinical or sub-clinical infection within twelve months. The negative impact of this level of infection on profitability across the industry is horrendous.

Doctor Ian Humphery-Smith,

Lecturer for medical and veterinary students for infectious diseases and molecular biology for 7 years

Founded of the Human Proteome Organisation to take-up the gauntlet of the next phase of the Human Genome Project

Director of International Business Development at the Skolkovo Foundation

Consultant for multinational corporations across Space, IT, Biomedicine and Energy sectors

Presently the Head of private sector investment in Skolkovo RusInnovations

30.01.2024
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