2 November 2009

5 minute read

Longevity
In 1997, dairy cows were kept on average for about 3.3 lactations, giving an average lifespan of about 5½ years for a cow entering a herd as a heifer at 2 years of age. The report believes that this lifespan is relatively short in terms of the potential lifespan of cows, which can live to 12 years or older.

Since 1997, the average number of lactations have increased to 3.6 per cow. This longer lifespan has occurred despite greater culling rates due to foot and mouth disease, bovine tuberculosis and bovine spongiform encephalopathy.

The report says that under UK conditions, the theoretical economic optimum for the cow’s life-span in the absence of disease is between 4.3 and 4.9 lactations. It recommends that the industry strive for an average lifespan of eight years.

The report identified that the main influences on a cow’s lifespan are voluntary and involuntary culling strategies. In the past more cows were voluntary culled, whereas today, more cows are culled involuntarily. Involuntary culling is mainly due to endemic and metabolic diseases and infertility and accounts for about 57 per cent of dairy herd culls.

The report recommends reducing the number of cows that are culled involuntarily with the aim of extending the overall productive life without compromising welfare, to achieve a longer lifespan. A lifespan of eight years – or about five to six lactations - gives a replacement rate of around 20 per cent, which is currently achieved in the best performing herds within the UK.

Breeding
Breeding cows has changed to incorporate a wider set of goals other than high milk yields. Of significant importance is bull selection for health and welfare traits. Other non production traits such as lifespan, health including lameness and mastitis and fertility (calving interval and non-return date) all play an important part in breeding values.

Despite this, component traits of breeding indices are still weighted by their relative financial contribution to overall profitability, rather than their contribution to welfare and other non-production traits.

Lameness
The report suggests that lameness is a major reason for the premature culling of dairy cows, accounting for 10 per cent of culls. Not only does lameness cause the cow great discomfort, it increases veterinary costs, takes up staff time, reduces milk yield and can impair fertility. A recent UK study showed that the average prevalence of lameness was 17 per cent in UK herds. This has not improved much since 1990. Despite control of traditional lameness such as sole ulcers, new infections such as digital dermatitis are challenging the industry.

One reason for the slow progress in dealing with lameness is the farmer's perception of the problem, suggests the report. The dairy cow industry is encouraging farmers to score their cows' mobility. In Holland, farmers are penalised financially for cow lameness, with milk from severely lame cows kept out of the milk tank. The penalty is based on an interpretation of an EC regulation (EC 853/2004) that requires milk to come from cows in a “good state of health”. Either way, issues of lameness need to be addressed urgently.

Mastitis
Mastitis is the most common disease in the UK herd and is responsible for nine per cent of premature cullings. A study carried out by the University of Edinburgh said that farmers reported 20 - 40 per cent of their cows had had mastitis in the past year.

The report says that the cost of a mild case of mastitis is about £169 per cow, and a severe case is £469. A fatality due to mastitis costs about £1709 per cow. FAWC recommend the introduction of a scheme which regularly collects records of the incidence of clinical and sub-clinical mastitis for individual cows

The FAWC consultation showed there is a wide variation in somatic cell counts with an average of between 100,000 and 250,000 cells/ml. Somatic cell counts have risen by 30 per cent since 1998, worsening the cases of sub-clinical mastitis.

Other diseases
Endemic diseases such as bovine viral diarrhoea. infectious bovine rhinotracheitis, leptospirosis and Johne's disease are a few examples which can lead to the premature culling of animals. One of particular concern is bovine tuberculosis (bTB), FAWC are looking forward to a successful, equitable outcome that protects the welfare of dairy cattel nd also the interests of the farmers and the public purse.

The report identifies that the risk of bluetongue and foot and mouth disease becoming endemic is increasing with changes in climate and importation of livestock and meat products from infected areas.FAWC believe that measures to prevent these outbreaks should be at the forefront of the industry and Government's plans.

Metabolic diseases such as displaced abdomasum (LDA), ketosis and milk fever are low, typically about one per cent. Despite this they should cause concern due to the loss of welfare and production.

Although many diseases can be controlled by vaccination, many cannot. The report identifies the need for bio-security in herd health plans and stresses that when problems do arise they must be treated promptly to ensure rapid recovery or prevent spread of disease. FAWC encourage on-farm recording of dieseases, perhaps as part of farm assurance schemes.

Infertility
Infertility is the main reason for premature, involuntary culling of dairy cattle. In the UK, the conception rate has declined by about one per cent every three years and is now around 40 per cent. Recent research has suggested that body condition affects both health and fertility.

The report also highlights that infertility is influenced by diseases such as lameness and mastitis and says that management of the dry cow is critical for fertlity. Failure to conceive as a first lactation heifer is a major fertility problem in UK herds. Therefore, management of the heifer during rearing and admission to the herd is vital.

It is evident that infertility in UK herds can be addressed through both breeding and management.

Further Reading

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You can view the full report by clicking here.