MilkMyths.org.uk

Most people see dairy cows grazing in the field and think that they have an easy, peaceful life, and die naturally at a ripe old age. In truth, the dairy cow is the hardest worked of all farmed animals, nurturing a growing calf inside her while simultaneously producing 30-50 litres of milk a day. No other farm animal carries this dual load of pregnancy and lactation. John Webster, Emeritus Professor of Animal Husbandry, Bristol University’s Clinical Veterinary Science department has likened the workload of the high-yielding dairy cow to that of:

“. . . a jogger who goes running for six to eight hours every day’ and believes that ‘the only humans who work harder than the dairy cow are cyclists in the Tour de France.” (29)

This enormous physical burden takes its toll on the cow’s body and after only two to four lactations she is culled, either due to infertility, mastitis, severe lameness or because her milk yield has dropped (7). Compare this to a healthy beef cow, who can produce 10 or more calves before reaching physical exhaustion, and you understand why Professor Webster believes:

“As far as the welfare issue is concerned, the problems with beef cattle are nothing compared to the problems in the dairy industry. So anyone who avoids beef and elects to eat cheese due to welfare concerns is missing the point.” (7, 44)

Fig. 20. Modern high-yield dairy cows cannot consume enough food at pasture to satisfy both their enormous milk output and their normal bodily functions, resulting in malnourished animals with protruding bones (Photo: Ed Shephard)
Click here for a video clip of malnourished cows

The misconception that dairy cows do not suffer often stems from the fact that they do not display the signs of distress that we expect to see, such as bellowing, immobility or loss of appetite (7). However, in the wild, cattle and other ruminants are prey animals who live in herds to reduce their risk of predation (7). In this situation, the animal that shows outward signs of illness becomes the target of attack (7). Cows have therefore evolved to soldier on regardless of how much they are suffering. According to Professor Webster, pain thresholds in cows are the same as in humans (7).

The high-yielding Holstein cow is a large animal who simply cannot consume enough food at pasture to sustain her enormous milk output as well as her other bodily functions, leaving her in a constant state of ‘metabolic hunger’ (6, 7). At pasture, her food intake is limited by the rate at which she can consume and digest grass. As grass is high in fibre, it fills up the rumen (stomach) quickly, causing the cow to feel ‘full up’ while at the same time still feeling hungry for nutrients (6, 7). Standing and eating for hours on end is also very tiring work and cows, who would naturally spend 12-14 hours a day lying down, face conflicting motivation to stop eating and rest (7, 37). Rye grass pastures, which are very high in nitrogen, can lead to increased urea in the cow’s blood, making her feel sick and impairing her appetite (7). Professor Webster summarises her feelings as ‘simultaneously hungry, tired, full up and feeling sick’ (7).

Due to their inability to meet the metabolic demands of lactation, it is normal for cows to ‘milk off their backs’ in early lactation (draw on body reserves), resulting in a ‘coat rack’ appearance with the bones of the hips and spine protruding, as illustrated in Fig 14 (7, 29). Dairy farmers consider this to be a normal metabolic situation in high-yielding dairy cows and have come to accept ‘bony’ dairy cows as typical, when in fact they are malnourished (46).

The abnormal demands on the cows’ energy reserves often lead to ketosis and fatty liver syndrome (7).

Ketosis occurs when the cow begins to break down body fat in an effort to bridge the ‘energy gap’ during early lactation (45). Body fat is transported to, and broken down in the liver to metabolites which are then utilized by the body tissues (45). Excess mobilisation of fat can lead to a toxic level of ketones accumulating in the blood, milk and urine, causing a loss of appetite and drop in milk yield (45). Affected cows may also exhibit nervous signs, which include excessive salivation, licking of walls or gates, malco-ordination and aggression (45).

There is a limit to the amount of fat the liver can break down to ketone bodies and, when this is saturated, the surplus fat accumulates in the liver (46). This reduces the normal function of the liver and, because it is a vital organ, many normal body functions are upset. Milk production, mastitis

Milk fever is one of the most common metabolic disorders in dairy cattle, usually occurring just before, during or immediately after calving (47). It is caused by low blood calcium resulting from the high calcium demands of pregnancy and lactation. When the cow’s blood calcium becomes too low to support normal nerve and muscle function she collapses and is unable to stand until her blood calcium becomes normal again (48). Death can be rapid, with milk fever the most common cause of sudden death in dairy cows (47). According to the National Animal Disease Information Service (NADIS), it is also one of the most important causes of calving problems and subsequent calf deaths (48).

Grass staggers (or grass tetany) occurs when the cow’s intake of magnesium is lower than her output (49). It occurs most commonly in lactating cows at pasture as grass can be very low in magnesium, especially rye grass, while the output of magnesium in milk is high (49). Clinical signs can appear very rapidly as cows do not store magnesium and must rely on a daily intake (49). Initially, animals become nervous and excitable, and then begin to stagger and fall over (49). This can quickly progress to convulsions, coma and ultimately death. The short duration of clinical signs means that the mortality rate is high, as many animals are found dead before anyone notices they are ill (49).

Fig. 21. Sole ulcers such as this are common in the hind feet of dairy cows as the weight of their enormous udders causes the pedal bone of the foot to penetrate through the sole
Click here for a video clip of lame cows

While the obvious solution to the problem of hunger and mineral deficiency in high-yielding dairy cows would be to stop breeding animals with such a high milk output, dairy farmers are instead increasingly feeding their cows on high protein feed concentrates (7). These concentrates, which are usually made from GM soya and maize, are higher in calories than grass and thus provide more energy (7). However, they are also high in amino acids which further accelerate milk production (7). The result of this is increased milk production in the short term but loss of body condition, infertility and greater susceptibility to illness later on (7). The high starch and protein content of feed concentrates also cause digestive problems which lead to a reduction in appetite, bloat and lameness induced by laminitis (discussed further below) (3, 6, 7).

“The level of lameness in dairy cattle in the UK is unacceptably high. It is a major cause of pain and discomfort to the animals.” (50)

Professor Webster shares these concerns, citing an annual incidence of lameness of 50% and prevalence of 20% - meaning that half of the cows in Britain go lame each year and 20% are lame at any one time (7). As lameness is almost always a painful condition, he believes:

“. . . it is indisputably the most serious welfare problem faced by dairy cows.” (7)

And because many lame cows continue to milk satisfactorily, they are forced to struggle on despite their severe pain (7). In their Report on the Welfare of Dairy Cattle, FAWC found:

‘many farms where lameness is causing unnecessary pain and distress. Yet some stockmen appear not to perceive lameness as a problem and the severity and extent often go unnoticed and untreated’ (3).

Approximately 80% of cases of lameness are due to foot problems and the remainder to leg damage (50). Sole ulcers, white line disease, digital dermatitis and laminitis are the most common foot problems and are caused by a number of complex factors (3, 7, 50). The majority of leg lameness is due to physical damage from badly designed cubicles and to injury at calving (50).

Seventy-five per cent of sole ulcers and white line disease (cracks in outer rim of the sole which allow dirt and bacteria to enter, causing abscesses) occur in the outer claw of the hind feet (7). This is directly attributable to the presence of the huge udder which pushes the cow’s hind legs apart and forces her to adopt an abnormal gait, putting extra pressure on the outer claws, as illustrated in Fig 6 (29). Poor hoof quality, caused by nutritional deficiencies, can also predispose the sole to ulcers (30). Both sole ulcers and white line disease cause chronic pain which gets worse with time (7). They are further aggravated by the long distances many cows must walk between pasture and milking chamber twice a day, and also by winter cubicle housing where many cows are forced to stand on concrete for extended periods of time (discussed further below) (7). According to Professor Webster:

“Most farmers only elect to treat the most severe cases, for example where there has been complete penetration of the sole, inducing deep pain from standing on concrete and scalding pain through exposure of sensitive underlying tissue to acid slurry.” (7)

Fig. 22. Modern dairy cows can weigh up to 750kg and are much too big for most of the cubicle houses in Britain which were installed in the 60s and 70s when cows were 150-200kg lighter
Click here for a video clip of a typical cubicle unit

Incidence of digital dermatitis, a painful bacterial infection of the foot, has increased in recent years due to a combination of factors (7). Many indoor cubicles were installed when the predominant dairy breed was the British Friesian, which commonly weighed around 550kg, but the increased popularity of the Holstein means that many cows now weigh in excess of 700kg (50). As a consequence, the length and width of cubicles are too small for modern dairy cows and they are often forced to stand with their hind feet in the slurry passage behind the cubicle (50). Slurry is highly acidic and softens the cow’s feet, allowing bacteria to penetrate (50). In addition, most dairy farmers have switched from hay to silage as winter cattle feed (7). Whereas hay is composed of dry grass and other herbaceous plants, silage is wet, fermented grass which causes wet manure, contributing to hygiene problems when cows are housed indoors (7).

Roads, tracks and gateways which have rough, uneven surfaces can cause puncture wounds in the foot which are susceptible to infection (50). When allowed to walk at their own speed, cows are able to place their feet carefully to avoid obstacles or rough objects. When forced to hurry (by the farmer or farm dog) they bunch together and cannot choose where to place their feet, so are more likely to sustain damage from sharp stones (50). In many dairy units the ageing concrete floors have become broken or cracked, causing abrasions and punctures of the sole which are also easily infected (30). Although digital dermatitis can be treated with antibiotics, once it has become endemic in a herd it is very difficult to eradicate (7).

Laminitis is the acute or chronic inflammation of the soft tissue (laminae) between the bone and the outer horny wall of the foot, which, according to DEFRA:

‘imagine crushing all your fingernails in the door then standing on your fingertips’ (6).

The soft tissue of the foot is well endowed with nerves and blood vessels which carry oxygen and nutrients to support hoof growth and is therefore very sensitive to toxins in the blood (30). Feed concentrates which are high in protein and starch cause toxins to be produced in the rumen which are absorbed into the blood stream and irritate the soft foot tissue, causing inflammation (30). According to DEFRA, research carried out in Scotland in the late 1980’s found a significant link between high protein diets and lameness (30). Wet silage, which is high in acid and ammonia, can also lead to toxins in the blood which cause laminitis (30).

When a foot is affected by laminitis the blood flow is restricted, affecting hoof growth and resulting in softer soles which are more prone to disease, such as ulcers and white line disease, as well as puncture, leading to digital dermatitis (30).

The inadequately sized cubicles in which most dairy cows spend six months of the year contribute to the high incidence of lameness in several ways. The problem of cows having to stand with their hind legs in the slurry passage has been outlined above. The small size of the cubicles also makes it difficult for modern cows to lie down comfortably, reducing the amount of time that they spend lying and increasing the pressure on their legs and feet (3, 7). Some cows avoid the cubicles altogether and instead lie in the aisles or slurry passages where they become very dirty and increase their risk of hock abrasions, lameness and mastitis (discussed further below) (3).

Cows may also be forced to spend long periods standing or lying in the passages because there are not enough cubicles for all of the cows in the herd (3, 7). Due to the social hierarchy of the herd, subordinate cows may also be reluctant to lie in cubicles next to dominant cows, opting to stand or lie in the passages instead (3, 7). To overcome this problem, the FAWC recommends that indoor housing units contain 5% more cubicles than the number of cows (3).

Many cubicle units have concrete bases because they are easier to clean, but they are also hard and uncomfortable and may lead to swelling of the knees and hocks as well as pressure sores (43, 51). Under The Welfare of Livestock Regulations 1994, dairy farmers must provide indoor cows ‘access at all times to a well-drained and bedded lying area’ (34). In practice, however, the bedding provided is often little more than a thin layer of sawdust or straw which does not provide adequate cushioning to keep the cow comfortable or prevent contact sores (3). The use of mats or cow mattresses in cubicles help provide cushioning but must still be covered in bedding such as sand, straw or shavings to prevent contact sores and keep the mat dry (43).

Fig. 23. The combined weight of blood, secretory tissue and stored milk can result in a total udder weight of 50-75kg. This puts enormous strain on the udder tissues and predisposes the cow to mastitis
Click here for a video clip of a cow’s distended udder

Mastitis is a painful bacterial infection of the udder which affects 30 percent of the dairy cows in Britain at any one time, with one million cases of clinical mastitis occurring in the UK every year (3, 5, 7). While clinical mastitis produces obvious symptoms such as swollen, hard udders and discoloured or clotted milk, mastitis can also occur in a subclinical form with no visible changes to the udder or milk, making the number of these cases impossible to calculate (3, 13, 29).

Mastitis pathogens, of which there are over 200, belong to one of two categories: contagious or environmental (43). Streptococcus uberis and E. coli are by far the most common causes of mastitis and are both environmental pathogens, thriving in dirty, wet bedding and poorly ventilated buildings (3, 43). Both contagious and environmental pathogens can be transmitted from cow to cow via the milking machine (43). While the incidence of contagious mastitis has declined over the past 30 years, the incidence of environmental mastitis has remained largely unchanged since 1960, accounting for over 58% of clinical cases (43). The failure in combating environmental mastitis is largely due to the increase in herd size and the very high milk yield of the modern dairy cow (3, 43).

Larger herds make it difficult to properly monitor each cow and her milk, allowing infected animals to enter the milking chamber and pass the infection on via the milking machine (43). Larger herds also produce more manure which accumulates in indoor housing units, creating an environment in which bacteria thrive (43). High-yielding dairy cows who are only milked twice a day may leak milk onto the cubicle bed when their udder becomes full, producing a bacterial haven of faeces, bedding and milk (43). The abnormal accumulation of milk in the udder also strains the udder tissues and predisposes high-yielding cows to mastitis (6, 29). The combined weight of blood, secretory tissue and stored milk can result in a total udder weight of 50-75kg (43). In beef cows, who have small udders, the incidence of mastitis is a fraction of that in dairy herds (29).

Fig. 24. Faulty milking machines can damage the cow’s teats, causing great pain and increasing her risk of mastitis

Poorly designed and maintained milking machines are also recognised as major contributors to udder infection (30, 43, 52). Despite the major role they play on a dairy farm, milk machine maintenance is often neglected (43). This can lead to physical damage of the teats, which are richly endowed with nerves and therefore highly sensitive, and allow infection to penetrate the udder (43). Faulty machines can also actively transport bacteria to, as well as propel them into, the udder (30, 43).

Teat damage can also occur because of high stocking densities in indoor housing units as well as inadequately sized cubicles (43). Large cows in narrow cubicles may push their legs through into the adjacent cubicle and crush their neighbour’s teats (43). Disruption to an established herd, either by the addition of new members or splitting it into smaller groups, can result in fighting which may also cause teat injuries (43). Severe teat injuries, such as total teat amputation, are surprisingly common in dairy herds (43).

Summer mastitis, an acute illness of dry (not lactating) dairy cows, is also common in temperate countries such as Britain (3, 43). It occurs in 35-60% of UK herds annually, affecting over 20,000 animals (3, 43). The main means of transmission is the sheep head fly (Hydrotoea irritans) which feeds on cattle blood (43). Damaged teats predispose cows to infection (3). Summer mastitis causes extensive, painful damage to the udder which becomes swollen, hot and hard and produces a thick, foul smelling secretion (3, 43). Severely affected cows become lame from the pain, with extreme cases leading to abortion and death (3, 43).

When a cow is suffering from mastitis her body produces large numbers of white blood cells which migrate to the udder to fight the infection (13). Many of these cells then pass out in her milk, and the greater the infection the higher the number of these ‘somatic’ cells in her milk (13). Dairy processors use this somatic cell count to determine what price they pay farmers for their milk, imposing financial penalties for milk with high somatic cell counts (43, 52). Under EU regulations, milk with a somatic cell count as high as 400 million per litre may still be sold for human consumption (13, 43). Some farmers feed milk which exceeds this threshold to the calves (43).

Antibiotics are routinely used to treat mastitis and may be injected up the teat canal, as illustrated in Fig 19, or administered orally (43). Intermammary injections, if performed carelessly, can cause teat canal damage which is extremely painful and increases susceptibility to infection (35). To reduce the amount of drug residue which enters the food chain, all antibiotics have a specified post-treatment milk withholding period stated on the product (43). Due to public health concerns, the EU imposes limits on the maximum permissible level of antibiotics in milk, which is currently set at 0.007 mg/litre (13). Dairy processors use random sampling to test milk for residues, penalising those farmers whose milk fails to meet these restrictions (43).

To help reduce the amount of mastitis in dairy herds, most farmers practice 100% dry cow therapy – as recommended by DEFRA (43, 52). This involves injecting a long-acting antibiotic into all four teats of all cows, whether infected or not, as soon as they enter their two month dry period (43, 52). Cows that suffer from repeated cases of mastitis or have persistently high somatic cell counts are routinely culled (52).

Fig. 25. Mastitis, a painful infection of the udder which is widespread in British dairy herds, is treated by injecting antibiotics up the teat canal – a procedure which can damage the udder if performed improperly

The arduous life that dairy cows endure causes such rapid physical degradation that an alarmingly high number of young animals are culled due to infertility (3, 7). A culling rate of 25% is normal for most dairy herds and poor fertility is the single biggest factor (3). As one dairy farmer put it:

Although infertility in itself is not a welfare problem, it is an indicator of poor welfare resulting from physical exhaustion (3, 7). Even the Milk Development Council (MDC) acknowledges that ‘the drive towards increased milk yield has resulted, in part, to decreased fertility’ (54). They also cite postpartum (after calving) uterine infections as a major cause ofreduced fertility, with retained placenta and calving difficulties being the most frequent causes of uterine infection (54). The risk of retained placenta and calving difficulties both increase when cows are impregnated with large dairy or beef breeds which they have difficulty giving birth to (3, 29, 33).

To help combat the problem of infertility, the use of fertility drugs is now widespread on dairy farms in Britain (55). Cows are given hormones to help increase conception rates, but also as a herd management tool to ensure that groups of calves are conceived and born around the same time (54, 55).

When a farmer decides to abandon dairy farming, the herd of milking cows will be sold off, usually at a livestock market. Surplus dairy cows are also routinely sold at markets. But farmers do not necessarily take their animals to the nearest livestock market; they take them where dairy cows are most in demand. Currently the demand for dairy cows is highest in the South West of England and some cows and calves travel from as far away as Essex and Norfolk, enduring journeys of six hours or more (56).

On top of these long journeys, many cows sent to market must also endure the uncomfortable pressure of overfull udders. According to FAWC: “It is common practice to send dairy cattle to market or to agricultural shows with overstocked udders.” (3) This means that the cow is not milked on the morning of the sale or show so that her udder looks full, making the cow ‘more attractive to prospective buyers or judges’ (3). In their 1997 report on the Welfare of Dairy Cattle, the FAWC condemned this practice, stating:

“Cows with overstocked udders suffer unnecessary pain and unnecessary distress which is against the law.” (3)

Fig. 26. This dairy cow at Colchester market is leaking milk from her overstocked udder, a common sight at UK livestock markets (Photo: Animal Aid)
Click here for a video clip of a cow at market with an overstocked udder

Despite their advice, cows continue to be sent to markets with overstocked udders, as witnessed by a Viva! investigator who attended three dairy cow auctions at Taunton livestock market in 2005. FAWC have also reiterated their concerns over this practice in their 2005 Report on the Welfare of Farmed Animals at Gatherings (57).

The Dark Side of Dairy - A report on the UK Dairy Industry
A Viva! Report by Toni Vernelli, BSc (Hons) Animal Biology and Conservation
Published by Viva! © Viva! 2005

Contents

A report on the UK Dairy Industry

Suffering in Silence