Hemp field

Nutritional composition and concentration of cannabinoids in co-products of industrial hemp

Maria Villagrasa & Fernando Diaz

Hemp (Cannabis sativa) has been cultivated for hundreds of years around the world. Industrial hemp is grown in Europe on a limited basis to produce fiber, but also seeds and oil. Hemp varieties that can be grown for these purposes should be included in the common catalogue of varieties of agricultural plant species in the European Union (EU).

The maximum tetrahydrocannabinol (THC) content, which is the main psychoactive substance, is limited to 0.2% in the EU, while in the US it must be less than 0.3%.

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Effects of vitamin E supplementation on milk production and reproductive performance

Maria Villagrasa & Fernando Diaz

Vitamin E is an essential nutrient for cows, but the effects of its supplementation are often controversial in the scientific literature. The goal of a recent meta-analysis published in Journal of Dairy Science was to evaluate the effects of vitamin E supplementation and serum vitamin E levels on productive and reproductive variables of dairy cows in transition.

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Productive response of dairy cows supplemented with forage turnip

Maria Villagrasa & Fernando Diaz

The Brassicaceae family is composed of numerous species of great economic importance and varied uses, such as forage, human food, and medicinal and ornamental plants, with the genera Brassica and Raphanus as two of the most widespread.

Within Brassica forages there are different types such as cabbage (B. oleracea) or forage turnips (B. rapa). The interest in the latter is that its cultivation allows for high feed yields in short periods of time, higher than those of other similar crops. It also contributes to the diversification of the forage base for dairy production in temperate areas.

Forage turnip is a biannual plant that produces seed usually in its second year. Its vegetative cycle lasts two to four months, depending on weather conditions, shorter when temperatures are higher and longer when they are lower.

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Milk production systems: “Circularity, the new challenge”

Adolfo Alvarez Aranguiz

Since the green revolution, farmers have become more and more production-oriented and have been encouraged to maximize productivity through the increased use of farm inputs (i.e., fossil fuels, pesticides, mineral fertilizers, imported feed), improved plant and animal genetics, advanced machinery, and new technology. This has come at a cost of unintended harmful side effects on the landscape and the environment, which have become unacceptable to societies.

The current global food system has an enormous environmental impact. It is responsible for about a quarter of all greenhouse gases released by human activity, drives deforestation and loss of biodiversity, pollutes fresh and marine waters, and takes up 40% of the world’s ice and desert-free land (Poore and Nemecek, 2018).

We all know that the key challenge in the coming decades will be to produce enough safe and nutritious food for future populations without running out of resources or destroying Earth’s ecosystems –in other words, without exhausting the biological and physical resources of the planet.

Dairy production is not an exception within the global food system chain, and as all other components, needs to affront new challenges to assure “Food and Resource Security” for future generations.

New challenges for dairy production

The world dairy sector faces new challenges ahead that must be taken into account in the development and adjustment of the dairy production systems.

Challenges of the dairy sectorChallenges of the dairy farmers

Climate change:
-Greenhouse gas emissions: CH4, N2O, CO2
-Temperature increase
-Extreme and unexpected meteorological events

Food Security:
-World population: expected increase in 1.000 million people in the next 10 years

Resource Security:
-Soil, water and air quality and sustainability


-Availability, knowledge

Investment and upgrade:

-Soil, water, air

-Milk price volatility


This situation arises from the 4-5% annual increment in the world’s demand for dairy products, but also with unpredictable changes in consumers and market preferences, a situation that puts the dairy producer in an unclear situation for medium to long-time strategies, such as genetics or investments.


The current production systems developed in parallel with the so-called “Green Revolution” during the 60s and 70s have clearly demonstrated their inefficiency with respect to food security and resource security. After 50 years, hunger is still a big problem around the world while resources keep diminished rapidly.

Agricultural/livestock systems, including milk production systems, developed during those years have been following a linear production system (Figure 1), based purely on an economic analysis and short-term results, where biological factors have taken a secondary role. These systems have been characterized by a high use of external inputs (fertilizer, feed, energy…) in order to maximize production (milk, meat, grain,…). In the particulate case of dairy farms:

Inputs (e.g., feed, supplements, fertilizers, insecticides, herbicides, energy, medications, hormones,…) have been used with the objective of increasing milk production, while aspects such as the environment, manure management, nutrients leakage, animal fertility…, have been considered secondary.

Figure 1

Figure 1. Dairy farm linear production system

Today, these linear systems, adjusted to the production conditions of the different regions, face very varied situations, with very specific challenges to overcome, and with their own characteristics for each country or region. This is the case of Europe and the USA with environmental and animal welfare problems, together with low animal fertility.

South America where the agriculture displaces animal production to marginal areas with the subsequent soil degradation, deforestation and drop in the water table level. Asia facing problems related with feed production and supply, together with the environment, and land availability and productivity.

New Zealand with high stocking rates, and a milk ono-production system; or Africa with high degraded lands and low productivity. Greenhouse gas emissions and water quality are common problems in most regions.


The concept of circularity originates from industrial ecology (Jurgilevich et al., 2016), which aims to reduce resource consumption and emissions to the environment by closing the loop of materials and substances. Under this paradigm, losses of materials and substances should be prevented, and these should instead be recovered for reuse, remanufacturing and recycling.

In line with these principles, moving towards a circular food system implies searching for practices and technology that minimize the input of finite resources, encouraging the use of regenerative ones, prevent the leakage of natural resources (e.g. carbon (C), nitrogen (N), phosphorus (P), water) from the food system, and stimulating the reuse and recycling of inevitable resource losses in a way that adds the highest possible value to the food system (Jurgilevich et al., 2016).

The suggested solution, that is already underway in many regions of the world, is basically, the return to productive systems similar to those used by our grandparents, adding new technologies and knowledge and, of course, aiming at higher production, sustainability, profitability and simultaneously considered social aspects, economics and environment, what we call “circular production system” (figure 2).

What is sought with these new circular production systems is a balance between inputs and outputs, (i) where attempts are made to reduce external inputs to the farm with an increase in efficiency and control of final products, and (ii) where there are no longer single products (milk, grain …), but a set of them, which to some extent are revalued and recirculated within the system itself.

Animal production plays a key role in the circular system, especially in ruminants due their capacity to convert high fiber products (low nutritional value for the growing human population) in a high nutrient feed, like milk or meat, and manure that can contribute to the return of nutrients to the soil.

Rotation of annual crops with perennials, or animal production with agriculture, need to be considered as another important tool for resource maintenance.

Figure 2

Figure 2. Dairy farm CIRCULAR production system

These dairy circular systems are at the same time integrated and play an important role in the whole economic system due the high nutrition value of milk for humans, especially children.

During the process of adaptation to or development of a circular system, the particular circumstances, agro-ecological, social, and economics of the country, region or farm always need be considered. As extreme examples, we could mention Africa, where food security is a priority, and where the circular systems to be developed need to be based on a sustainable intensification over time.

Also, where the supply of a high nutritional value product, such as milk, can be ensured through the development of a production system focused in the conservation of natural resources, mainly soil and water, for future generations.

Dairy farms in Europe or in the USA are at the other extreme, where the priority is environment and resource security (air, soil and water), and where food security (hunger) is replaced by the so-called nutritional security (nutritional components of food, to avoid obesity and other “rich-countries” diseases).

These priorities lead to the European/USA milk production systems, which are based on smart control systems, with application of new technologies mainly in relation to energy, animal feeding, emissions control, water quality and recycling, and animal welfare.


The circular dairy production systems will play a key role in the future of the so-called circular economy, mainly in relation to food security and resource security (figure 3).

Figure 3

Figure 3. Circular economy

In order to attain a truly circular global dairy sector, further work is needed. Pathways should be broadened to cover (i) developing and emerging economy contexts, (ii) extensive grazing systems with large herds on large land areas, and (iii) highly intensive systems with up to thousands of cows per farm and water stressed areas, among other areas.

Research is also needed to deepen the analysis of different pathways, comparing their economic, social and environmental performance, identifying strategic levers that can be activated to make circular dairy farming competitive, and ensuring their feasibility and relevance at regional and local scales around the world.

It is also evident that practical steps must be taken to ensure farmers are the drivers, given that any successful transition will rely on actionable, collaborative approaches taken on the ground, while subsequent steps will require the contribution of best practitioners and collaboration with the broader value chain.

About the author

Adolfo Alvarez Aranguiz is Researcher at Wageningen University & Research, Netherland. His fields of expertise are ruminant nutrition, dairy farming, fodder production, feed formulation, grassing management, and tropical livestock.


Poore, J. and Nemecek,T., 2018. Reducing food’s environmental impacts through producers and consumers. Science 360: 987-992.

Jurgilevich, A., Birge, T., Kentala-Lehtonen, J., Korhonen-Kurki, K., Pietikäinen, J., Saikku, L. and Schösler, H., 2016. Transition towards circular economy in the food system. Sustainability 8(1): 69.

© 2020 Dairy Knowledge Center. All Rights Reserved.


Effects of steam-flaking on the digestibility of barley grain

Maria Villagrasa

Cereal grains are rich in starch and their content depends on plant variety, weather conditions, and agricultural practices. Adult cows have limited ability to chew cereal grains; it is essential then to break down the seed pericarp by means of chemical or physical treatments to improve its digestibility in the digestive tract.

Grain processing can be divided in two: non-thermal processes such as roller and hammer mills, and thermal processes including dry processing (roasting, etc.) and wet processing (autoclave, steam laminate etc.).

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Omega-3 fatty acids supplementation improves performance and immunity of dairy calves

Alvaro Garcia

Growing healthy dairy calves is critical for the profitability and sustainability of dairy operations. Their first weeks of life will define if they are going to turn into highly productive future dairy replacements. Supplementing calf with energy-supplying ingredients such as oils rich in poly-unsaturated fatty acids (PUFA) affect weight gains, immunity, antioxidant status, and metabolism.

Research has shown that the inclusion of PUFAs helps in the treatment of diarrhea and other inflammatory conditions early in life. This occurs by changing the ratio of PUFAs in the phospholipid fraction of the immune cells which alters the immune function. Of these PUFAs, linoleic and α-linoleic acid seem to have the greatest impact against the challenge posed by microbiological antigens.

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Tomato pomace increases vitamin concentrations in milk

Maria Villagrasa & Fernando Diaz

Tomato (Solanum lycopersicum) is the second largest vegetable crop in the world. The amount of waste it generates worldwide is estimated at 50,000 tons/year, and its disposal causes a negative impact on the environment. Tomato pomace is an industry co-product that, depending on the type of processing and the source of the raw tomatoes, includes variable proportions of skins, seeds and a small amount of pulp, representing about 4% of the original whole tomato weight.

Pomace contain valuable nutritional compounds, which include on a DM basis 59.0% fiber, 19.3% protein, 25.7% sugars, 7.6% pectin, 5.9% fat, 3.9% minerals and antioxidants (mainly lycopene).

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Mycotoxins in dairy cattle diets II: Prevention and treatment

Alvaro Garcia

Once the presence and concentration of mycotoxins have been determined, different practical approaches can be used to reduce their toxicity. The most common ones include: mold inhibitors (precautionary and before mold develops), fermentation enhancers (for high moisture, fermented feeds), physical separation (discard grain fines), adsorbent agents (at feeding time), blending down with clean feedstuffs to get below problem level, and strategically feeding to certain production phases.

Mold inhibitors and fermentation enhancers

Mold inhibitors (e.g., propionic acid) and fermentation enhancers (e.g., bacterial inoculants) are effective and recommended at storage time. However, there is no point in adding these agents once grain or corn silage has been stored for some time and molds and mycotoxins have already developed.

Hoffman and Combs (2009) suggest adding 5- 10 kg of actual propionic acid per ton of high-moisture corn (25% moisture or higher). Producers must keep in mind, though, that organic acid-treated grains can only be fed to livestock, and that treated grains cannot be marketed at the local elevator.

Also, mold inhibitors will do nothing against mycotoxins already present at the time of application. It is crucial to avoid unnecessary exposure of grain and silage to air during storage and feed-out and best not to feed grains that show mold growth or have a musty smell. If there is no choice other than to feed the affected grain, it is important to dilute the affected grain with safer grain sources.

Obviously, the easiest way to avoid mycotoxin problems is first not to have moldy feeds.  If despite best management efforts, one still ends up with mold and toxins there are some approaches to reduce the risk of exposure.

Physical processes

Physical processes such as cleaning, sorting, and dehulling are useful in separating the most dangerous material before thinking of any inactivating agents. Since most molds thrive in dead parts and fines, cleaning and sorting is the first defense against these contaminants.

Cleaning machines such as air separators, sieving machines, and sorting by density are obvious alternatives. The concern of feed mills are losses of feeding material that can represent around 8% or more. Granted, the negative impact of the mycotoxins on animal performance can far outweigh these losses.

Dehulling has a significant impact in reducing mycotoxin contamination. This however adds a degree of complexity and may slow-down the throughput of the feed mill. Again, this is a “balancing act” between the efficiency of the plant and the negative impact on the livestock it is charged with feeding.

Blending down with clean feedstuffs

If the mycotoxin-contaminated feedstuff is diluted with a “clean” batch, it reduces the toxin concentration. The US Food and Drug Administration (FDA) and the European Union however consider unlawful the deliberate mixing of adulterated food with good food for commercial purposes regardless of the contamination level.

The Centers for Veterinary Medicine may permit blending under special provisions (requested by the states), such as when facing feed shortages resulting from a drought. Permission is granted to the petition state, and the state’s regulatory agents oversee these activities.

Discarding the fines in dry grain stored in bins is a very important practice to reduce mycotoxins concentration. Research performed at the Virginia Polytechnic Institute suggests that mechanical screening of corn can reduce aflatoxin concentration in contaminated corn.

In this trial samples from a bin were collected with a probe at depths of 1, 3, and 5 meters. The samples were mechanically shaken to separate fines from intact kernels. The aflatoxin concentration in the whole kernel fractions was 86–89% lower than that present in the fines.

Total aflatoxin concentration and concentration in the fines was higher in samples collected at 1 meter than the samples taken at the other two depths. The difference in aflatoxin concentration at different locations within a bin underscores the importance of getting representative samples when assessing mycotoxin concentrations.

Using anticaking agents (“binders”)

The FDA does not recognize the use of mycotoxin binding agents as safe. Furthermore, these products must be subjected to an approved food additive petition if they are intended (sold) to be used for this purpose. Clay-type products are generally recognized as safe (GRAS) when used in animal feeds at levels not to exceed 2%.

The concern of the FDA is that binding may not be uniform across different products, rendering them unsafe for consumption. An additional concern is that there is no certainty about what may happen to this binding once exposed to the acid environment in the stomach. If under these circumstances un-binding were to happen, the animal may excrete unsafe levels of mycotoxins in meat or milk products.

In 2009 however, the European Commission extended their definition of feed additives to include: “materials that suppress or reduce the absorption of mycotoxins, promote the excretion of mycotoxins or modify their mode of action and thereby mitigate possible adverse effects of mycotoxins on animal health”. The position of the EU is thus difference from the FDA when it comes to the use of “binders”.

Mycotoxin adsorbents are included in livestock feeds to reduce mycotoxin toxicosis in livestock. The most frequent fungi belong to three groups: Aspergillus, Fusarium, and Penicillium.

Similarly, the most common resulting aflatoxins arising from these fungi are aflatoxin B1 (AFLB1), ochratoxin (OT) zearalenone (ZEA), deoxynivalenol (DON or “vomitoxin”), T-2 (trichothecene) and HT-2 toxins, and fumonisins (FUM).

These toxins have different chemical structures and as such different biological effects in the animal. The non-specificity and cross-symptomatology and interaction with management stress factors make their diagnosis oftentimes complicated.

The fact that several mycotoxin-producing molds can grow together under similar conditions makes its diagnosis even more difficult. As a result, one mold that seldom produce health problems acting alone, when the animal is immuno-suppressed and in the presence of another mycotoxin, can now show different symptomatology.

In fact, the effects of several mycotoxins can be present simultaneously, and can be classified as additive, antagonistic or synergistic. In addition, other factors interact that further complicate the diagnosis such as animal species, age group, type of diet, and how long they have been subjected to the mycotoxin challenge.

The main goal for farmers and the animal feed industry should be to prevent mycotoxin contamination in the field by adhering to best management practices. There are always unavoidable circumstances that cause stress in the several growth stages of crops and can result in unavoidable mold and mycotoxin contamination.

There are non-specific nutritional interventions that are suggested in order to boost the immune system such as the fortification with enzymes and minerals such as vitamin E and selenium. Then there is also the area of adding products with the specific intent of neutralizing the toxins themselves, namely binders, adsorbents or anticaking agents.

Adsorbent compounds tie-up the mycotoxin in a way that the new particle cannot be absorbed by the intestine. The ideal properties of an adsorbent have been summarized by various authors as four:

  1. they do not affect to animal health or production
  2. produce stable mycotoxin-adsorbent complex impeding absorption
  3. effective under the various environments of the entire gastrointestinal tract,
  4. environment-friendly after excreted out of the body

Three modes of action of adsorbents are currently accepted:

  1. binding mycotoxins to decrease their gastrointestinal absorption
  2. inactivating them
  3. modifying animals’ enzymes to transform mycotoxins into less toxic metabolites

Adsorbent compounds can be divided into two groups: organic and inorganic.

Organic adsorbents. The most popular organic adsorbent is yeast cell wall. Saccharomyces cerevisiae effectively suppresses the adverse effects of some mycotoxins (e.g. aflatoxins. Glucomannan of dry yeast cell wall is considered to have an immuno-modulating effect. When added to the diet it has decreased the severity of liver damage and protected immune reactions.

Among the mechanisms proposed are the proliferation of immune enzymes and immunoglobulin G. It has recently been demonstrated that d-glucan fraction of yeast cell walls is directly involved in the binding process of  mycotoxins,  and that the structural organization of glucans modulates the strength of this binding. Hydrogen bonds have been evidenced in the glucan-mycotoxin complexes and are stable at the pH condition of the digesta all along the digestive tract.

Recommended dosage for active yeast products is 1–2 kg/ton of feed, which corresponds or 20 g/day per cow. Organic adsorbent compounds are more efficient than inorganic binders against a broader range of mycotoxins and are the choice when multiple-toxins other than aflatoxins are present.

Inorganic adsorbents. Clays are natural adsorbents chemically made of silicates or aluminosilicates. They include a wide variety of products such as hydrated sodium calcium aluminosilicates, phyllosilicates with montmorillonite (magnesium hydrated sodium calcium aluminosilicates) as a major representative, and bentonite and zeolite.

They have rings of silicate tetrahedrons, with a silica molecule (positive) surrounded by four oxygens (negative) in a sheet-like structure. Mycotoxins are adsorbed into this structure trapped by the electric charges rendering it unavailable to intestinal absorption.

Most have been recognized as efficient binders of aflatoxins when added at 1% of the diet dry matter. Their efficacy against fusarium toxins such as zearalenone, fumonisins and trichothecenes is near nil. The rate of adsorption has been proposed to range somewhere between 40 and 60%. The strength of this bond depends on the chemical structure of the adsorbent material (i.e. electrical charge, porosity) and the mycotoxin itself (i.e. charge, solubility, shape).

The problem at the present time is that according to extensive research, it appears that the most effective binding happens in just a group of toxins, namely aflatoxins. There have been ample research testing clay-derived adsorbents such as bentonite, silicates, zeolites, and aluminosilicates. These compounds bind some mycotoxins with the resulting complex not being absorbed in the intestine.

Current recommendations are for their inclusion at 1% of the diet dry matter. The recommended level for aluminosilicates on the other hand is 2% of the total diet dry matter; their effect has been demonstrated also mostly against aflatoxins, but not against other mycotoxins. It is also advisable to fortify the diets with extra levels of vitamins and minerals since some of these adsorbents can reduce their availability.

The use of mycotoxin adsorbents in ruminants

Because of the particularity of their digestive systems, ruminants are more tolerant to some of the mycotoxins compared to single-stomached species. Aflatoxins deserve special reference since their metabolites (aflatoxin M1) can be excreted through milk. Other mycotoxins do not cause problems either because they are not excreted in milk (Fusarium toxins) or they are metabolized and excreted as less toxic compound.

The concentration of the aflatoxin M1 in milk usually is around 1- 2% the B1 ingested. In certain instances, and particularly in high producing cows it can reach 6%. Once Aflatoxin B1 is ingested, 42% can be degraded or transformed in the rumen to aflatoxicol (also toxic) or absorbed and transformed in the liver to aflatoxin M1, which can show up in milk.

Aflatoxin B1 and Aflatoxin M1 are both of concern to humans as they are potent carcinogens. Aflatoxin M1 is classified by the International Agency of Research on Cancer as class 2B, of possible human carcinogens; is currently regulated and its maximum allowed concentration in milk in the EU is 0.05 g/kg.

Inorganic adsorbing agents were able to reduce AFM1 in milk without affecting milk yield. For example, the hydrated sodium calcium aluminum silicate (HSCAS) at 0.56% inclusion in lactating dairy cow diets resulted in similar reduction of AFM1 of 46% on average when compared to controls.

Another study showed increased efficacy of HSCAS with increased level of inclusion; a reduction of 51.9% was obtained with 1% inclusion and increased to 82.2% and 86.9% with 2% and 4% inclusions, respectively. Sodium-bentonites also showed similar responses with 58% for one commercial product and 65% for the other one added at 1.2% to dairy cow diet.

Organic adsorbing agents such as a yeast-derived glucomannan added at 0.05% one study reported a reduction of AFM1 concentration of 58.5% while little response (4% in another) was observed in another. Caution must be expressed when interpreting negative results with the addition of extremely low concentrations of product (such as 0.05%), since the use of adequate premixes becomes extremely critical.

Final recommendations

  1. Most effective method is to reduce fines by screening.
  2. Blend with clean grain (just livestock producers), proportions to use depend on qualitative and quantitative analytical results (not feed manufacturers*).
  3. Reduce animal stress:
    • management and comfort
    • fortify trace minerals and particularly vitamins A, E and Se.
  4. Rations: use adsorbents/anticaking agents, which to use will depend on the analysis results on 2. Type of adsorbent: aflatoxins inorganic or some organic. For toxins other than aflatoxins, organic adsorbents are preferred.

*The FDA (and the EU) considers the deliberate mixing of adulterated food with good food for commercial purposes to be unlawful regardless of the contamination level. Permission is granted to the petition state, and the state’s regulatory agents oversee these activities under special circumstances such as extreme feed shortages.

© 2020 Dairy Knowledge Center. All Rights Reserved.


Making fescue baleage at different particle sizes

Alvaro Garcia

Festuca grasses are perennial and bisexual plants that mostly spread through rhizomes and are popular for pasture and hay. These grasses are of easy establishment outcompeting other plants and persisting over several years. Fescues can be conserved as baled silage particularly in small to middle-size livestock operations.

Similar best management practices used for baled hay and chopped silages can also be utilized for fescue with some minor adjustments. Some livestock producers choose higher moisture by harvesting and wilting earlier in the plant growth cycle, which increases nutrient content and digestibility, while reducing the risk of rain losses in the field.

One of the concerns at higher moisture levels though is the risk of butyric fermentation, result of the proliferation of clostridia in the ensiled material. When allowing fescue plants to mature there is also an increase in long, harder stems which have a negative effect on lactic acid production, since lactobacillus cannot easily access the plant sugars inside the stems.

Modern balers reduce this problem by incorporating cutting devices that chop the forage into smaller particles allowing for a greater cut surface area for lactobacilli colonization. This is also important since smaller particles allow not only for increased release of plant sugars but also an easier and even mixing into the TMR.

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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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