Cattle Breeding: Between Profit and Welfare

• To make dairy herds profitable, it is necessary to maintain a continuous high level of milk production.
• Blood testing is one of the methods for monitoring the health of pregnant animals.
• Scientists examined 101 cows in early pregnancy.
• Significant differences concerned the levels of lymphocytes, granulocytes, and platelets.
• The project involved an interdisciplinary team from Poland and Portugal.
• A2 milk is an opportunity for Polish dairy farms.

– Cattle breeding is an attempt to find a compromise between profitability and animal welfare. We check their condition, among other things, through blood analysis – says Prof. Alicja Kowalczyk from the Department of Environmental Hygiene and Animal Welfare, co-author of the study "Examination of the hematological profile of pregnant cows of the Polish Holstein-Friesian black-and-white variety in early pregnancy." The article appeared in the quarterly "Journal of Veterinary Research," publishing original works in the field of basic research and clinical studies on innovative diagnostic tools, vaccines, and antimicrobial therapies. They most often include animal infectious diseases, bacteriology, virology, parasitology, immunology, molecular biology, pharmacology, biochemistry, food and feed safety, and public health.

– We focused on studies in cows up to the 50th day of pregnancy, as there is no literature on the analysis of the hematological profile in dairy cattle up to this stage of pregnancy. Determining this profile is of great importance for the effective selection of animals and assessment of their health status. Our results can be useful in effective herd management – adds Prof. Kowalczyk.

Colostrum for a Good Start

Pregnancy in cows lasts almost as long as in women, about nine months. In natural conditions, the calf stays with its mother for several months and drinks milk. However, for the breeder, milk is too valuable, so the calf is weaned within the first few days. Right after birth, it receives colostrum, rich in proteins, fats, minerals, hormones, enzymes, and vitamins. Above all, it contains antibodies that strengthen the immune system of the calf and allow it to survive in the new environment. Then it is fed milk replacers containing dried milk, whey, soy protein, fats, minerals, and vitamins. In the following weeks, the calf transitions to solid feed.

The cow is then in the interpregnancy period, between the end of delivery and the next conception. The level of progesterone, which helped maintain the pregnancy, decreases. The secretion of estrogens increases, leading to the next estrus and insemination.

– In dairy cattle breeding, the dominant biotechnology of assisted reproduction is insemination. Its advantage over natural mating is mainly due to the possibility of individual selection of males for breeding to achieve the set breeding goals. It avoids diseases associated with natural mating, allows for the transport of semen over long distances, enables the use of sexed semen, but above all, provides a more accurate assessment of the breeding value of the fathers – says the professor.

The first estrus after delivery can occur as early as 20-30 days, but the first insemination should not take place earlier than 60 days after delivery. To make dairy herds profitable, a high level of milk production must be maintained. Therefore, the breeder is concerned with shortening the time when the cow does not produce milk. This is possible with a high level of reproduction and shortening the interpregnancy and intercalving periods.

– Shortening these periods is a controversial practice, as it maximizes profits at the expense of animals. Farms have different rules. Some extend the interpregnancy period even up to 90 days. Such values in high-yielding cows indicate good fertility of the herd – adds the scientist.

Milk is produced in the milk-forming cells continuously throughout the lactation period. It lasts on average 10 months, from calving to drying off the cow, i.e., stopping milking. This is done between 45 and 60 days before the expected time of delivery, to relieve the body from milk production, allow for better fetal development, regeneration of the mammary gland, and the formation of appropriate antibodies.

Quick, Sure, Non-Invasive

Profitability should go hand in hand with caring for animal welfare, which requires providing an appropriate diet and living conditions. One of the methods for monitoring animal health, quick and non-invasive, is blood testing. It is a good indicator of the animal's condition and can also indicate reproductive disorders. It helps detect possible diseases so that preventive measures can be implemented early enough.

– The examination of the hematological profile is crucial for maintaining the profitability of the herd and high reproduction, which depend on the quick diagnosis of disorders – says Alicja Kowalczyk. – The percentage of animals in the herd with postpartum retention, subclinical hypocalcemia, and ketosis, as well as cows with fatty liver or displacement of the abomasum largely determines the profitability of milk production.

The hematological profile changes during pregnancy and lactation, as the mother's body adapts to the new situation. The demand for nutrients and energy for the developing fetus increases, which translates into an increase in the number of erythrocytes transporting oxygen and the content of hemoglobin and hematocrit. Age, physiological state, feeding method (especially for hemoglobin levels), season, and climate also affect blood parameters. Heat stress significantly impacts the success of fertilization and maintenance of the fetus. The optimal ambient temperature for cows is up to 25 degrees; above this range, animals experience thermal stress.

Heifers and Multiparous Cows at the Peak of Lactation

– We tried to determine why so many cows lose their pregnancy at an early stage, up to the 50th day. It happens regardless of whether it is a pregnancy resulting from insemination or embryo transfer. We confirmed that the feeding in this herd was correct, so we first checked the biological material used for the insemination of the females. The embryos and insemination doses were of good quality, but still, many individuals did not develop pregnancy. Determining the hematological profile, i.e., basic blood parameters at an early stage of pregnancy, proved helpful – says the scientist. The team she led examined a herd of early-pregnant cows of the Polish Holstein-Friesian black-and-white variety.

– For years we have been cooperating with a large specialist dairy farm in Wielkopolska. We collect data there, conduct analyses, advise on how to manage the herd and increase reproduction efficiency – says the project leader.

Of the 101 cows, the youngest heifers were 9 months old, and the oldest multiparous cows were over six years old. They were divided into groups: a control group of non-pregnant heifers and non-pregnant cows and an experimental group of pregnant heifers and pregnant cows. The animals were in the peak period of lactation (after calving, milk yield begins to increase and reaches its maximum between the 10th and 90th day after delivery).

– This was an average group of animals. Those with clinical symptoms of diseases, such as increased body temperature, decreased milk yield, poor milk composition, lack of appetite, or lying down, did not qualify for the study. We also checked subclinical states, with symptoms invisible to the naked eye, but verified in laboratory tests – says the author of the article.

In March and April 2021, after morning milking and before feeding, 5 ml of blood was collected from each animal. The samples were transported in a refrigerator to the laboratory of the Faculty of Biology and Animal Breeding at UPWr. There, their analysis was carried out in terms of white and red blood cells, lymphocytes, monocytes, granulocytes, platelets, hemoglobin, and hematocrit.

– This was a health monitoring of the herd using morphological analysis, which reflects the state of the body's homeostasis. We checked how the blood composition changes with the development of pregnancy, and whether there are any worrying changes. We determined which elements of this hematological puzzle may be related to abnormal development of early pregnancy – says the professor. Additionally, the cows were subjected to ultrasound examination to detect and confirm pregnancy.

The most effective methods of pregnancy detection use clinical diagnostics. In cattle, pregnancy can be detected by palpation per rectum, ultrasonography, and hormonal tests. Each of these methods has its advantages and disadvantages, so the decision to use one of them should be made by a veterinarian in consultation with the breeder.

Granulocytes Digest Enemies, Lymphocytes Protect Against Infection

Among the 11 parameters examined, significant differences were observed in the levels of lymphocytes, granulocytes, and platelets, between animal groups up to the 45th day and between the 45th and 50th days of pregnancy.

Changes in the content of white blood cells may result from the migration of lymphocytes to the uterine membrane to protect against pathogenic microorganisms and the development of infection.

– Interestingly, the analyzed blood parameters also differed between heifers and cows. For example, we observed more lymphocytes, red blood cells, and hemoglobin in heifers than in cows. On the other hand, the level of granulocytes was higher in cows compared to heifers and exceeded the accepted reference values in all study groups – says the professor.

A higher level of granulocytes can be caused by an increase in progesterone levels, but it can also be a signal that the body is under attack by disease. The most important function of granulocytes is the absorption and destruction of pathogens and parasites. It is granulocytes that are responsible for initiating the inflammatory process and also for its resolution. Granulocytes are activated by bacteria, viruses, fungi, or damaged cells. Upon encountering a pathogen, they absorb it and release contained granules to digest and destroy the pathogen.

Platelets show the mother's adaptation process to the developing fetus. Too high a level may indicate an infection, chronic inflammation, iron deficiency, or anemia. It can also be associated with a dangerous condition, known as pregnancy poisoning. This metabolic disease occurs in the late stage of pregnancy, usually due to inadequate nutrition. It develops when the mother's glucose homeostasis is disrupted and the energy demand cannot meet the needs of the developing fetus. It can also occur at an early stage of pregnancy, for example, due to feeding with poorly balanced feed low in energy or protein, or rich in poorly digestible fiber.

Lymphocytes may be higher in the summer, as high temperatures stimulate the release of corticosteroids, which increase the number of white blood cells.

A higher level of erythrocytes results from the increased demand of the uterus for blood and oxygen for the fetus, in connection with the oxygen exchange through the placenta. Their proper level is especially important in the early stages of fetal development when the placenta is developing. A drop in their level means that the pregnancy is at risk or that anemia is developing.

Reproductive disorders are associated with, among other things, ovarian cysts, vaginal inflammations, and inflammation of the uterine mucous membranes. Some of the disorders have a bacterial, fungal, and viral basis, others – genetic and nutritional.

Passionate and Interdisciplinary

An interdisciplinary team is involved in the project: biotechnologists, animal scientists, veterinarians, and clinical dietitians. They work in various scientific centers in Poland and Portugal: MSc Marcjanna Wrzecińska and Prof. Ewa Czerniawska-Piątkowska (West Pomeranian University of Technology in Szczecin), Prof. Władysław Kordan (University of Warmia and Mazury in Olsztyn) and Jose Pedro Araujo (Instituto Politécnico de Viana do Castelo)

For years they have been researching reproductive problems in cattle and reproduction efficiency. They study factors affecting the quality of biological material used in assisted reproduction techniques, reducing the insemination index, reducing early pregnancy losses, increasing the efficiency of estrus detection methods, and synchronizing the estrous cycle and ovulation. They analyze the entire reproductive chain, from sperm to calf, through insemination or in vitro fertilization and embryo transfer.

–For us, this is primarily fun, we are all fixated on animal reproduction. The opportunity to work in the field, outside of daily laboratory work, sheds a different light on designing and implementing scientific activities, and combining science with practice gives us a lot of satisfaction – says Alicja Kowalczyk, who specializes in andrology. Primarily, she examines the biological quality of semen measured by the level of biochemical and structural changes in sperm during their conservation and storage. Recently, she applied for patent protection for her method of sperm selection by gender, non-invasive, compared to the commonly known method based on cytometry and free cell flow. Work on improving the newly discovered technology continues in the just-started project BoviSort FemCell, funded under action 16 "Cooperation" of the Rural Development Program 2014-2020.

It is possible to determine whether a sperm contains female or male material, depending on its DNA, various membrane receptors, and other differences in the structure of these cells. This allows them to be sorted: female, most desired for the dairy production sector, male for meat production, and both directions for the insemination industry, i.e., semen production stations. Such sexed, or gender-sorted semen and embryo transfer can allow doubling the herd of females in a year - says the scientist.

– This is what herd owners expect from us: tips on how to increase the efficiency of breeding through modern animal-assisted reproduction techniques. How to reduce costs while maximizing production – says the professor. He believes that one of the innovative ideas in animal production, which is an opportunity for greater profitability, is the transition of Polish dairy farms to the production of A2A2 variant milk.

Genotyp A2A2 bardzo pożądany A2A2 Genotype Highly Desired

in global animal production, the largest share is milk production: over 30 percent. In Poland, more than 6 million 300 thousand heads of cattle are bred, of which as much as one-third is precisely dairy cattle.

– The dairy industry is experiencing a crisis caused by, among other things, fluctuations in milk market prices, rising production feed costs, but also changing consumer preferences. Some of them give up animal products due to ethical convictions or because of food allergies and intolerances to animal products – says the professor.

– Lifestyle means that we have more and more health problems and are looking for culprits, including in milk. Of course, some of us have various food intolerances, but it's not always lactose to blame – adds the scientist. – Once butter, mushrooms, and eggs were under scrutiny, now there is an anti-lactose trend, similar to the anti-gluten trend.

Poor assimilation of milk is due not only to lactose but also to casein, the dominant protein in milk. One of its fractions is beta-casein, which occurs in several genetic variants. The cow always produces milk with one genetic variant.

A2 is considered the oldest variant, from which subsequent ones arose through mutation. 10,000 years ago, when cattle domestication began, they had beta-casein A2 in their milk. The process of domestication and then crossbreeding of breeds to improve dairy females, the A1 variant was created. Today the most popular, but by no means the healthiest.

It turns out that casein A1 during digestion breaks down into beta-casomorphin-7, which can affect the risk of developing civilization diseases: diabetes, atherosclerosis, and cardiovascular diseases. It can also cause inflammatory conditions in the digestive system, i.e., food intolerance. – It may be beta-casomorphin-7, not lactose, that is often the cause of this intolerance – says the professor.

This problem does not exist in the case of milk containing beta-casein A2, similar to that in human milk. A2 milk, which does not differ in taste, smell, or consistency from "ordinary" milk. It is easily digestible and hypoallergenic, and further research indicates its beneficial effect on the functioning of the human digestive system.

In the milk of cattle bred in Poland and Europe, the dominant variants are A1 and A2. Therefore, we buy store milk that contains both these forms of beta-casein. However, such a mixture does not reduce the risk of allergies. The only solution is a genetic selection of animals. For a cow to give A2 milk, it must have two copies of the A2 gene, one from each parent.

Genetic research conducted last year by the Polish Federation of Cattle Breeders and Milk Producers showed that out of more than 14,000 tested females, as many as 48 percent have the desired A2A2 genotype. Females of seven breeds were tested. The vast majority of them are heifers of the Holstein-Friesian breed, both black-and-white and red-and-white variants.

These were pilot studies, aimed at assessing the potential for A2 milk production in Poland and creating a production subpopulation consisting solely of cows with the A2A2 genotype - says Prof. Kowalczyk.

According to a survey conducted as part of the "A2A2 – a new way of dairy products – application of genomic selection in the production of food with reduced allergenicity" project, nearly 60 percent of Poles surveyed would buy milk or products that do not cause stomach and digestive problems if they were available on the market. Every second person, who does not have an intolerance or allergy to milk, would choose products with reduced allergenicity. One in three people are willing to pay more for such products.

So far, A2 milk is not available in Poland, but it is conquering Australia, where it already accounts for 10 percent of the dairy market. It is becoming increasingly popular in New Zealand, the United States, and South America. There you can buy not only milk but also butter, cheeses, and yogurts based on it.

– There is great interest in Asia because Asians do not digest "ordinary" milk. This is a very developmental trend. In the current crisis in the dairy industry, we need to look for alternative products. Hypoallergenic A2 milk is a good alternative to a dairy-free diet. It could be an opportunity for the Polish dairy market, for example, if it interested customers from Asia – believes the professor. – It is worth switching to breeding cows with the A2 milk genetic variant, and here again, science comes to the rescue because thanks to genotyping, the breeder can check the genetic potential of his herd.

Aneta Augustyn

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