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Forskningsartikel2009Vetenskapligt granskadÖppen tillgång

Scientific opinion on welfare of dairy cows in relation to metabolic and reproductive problems based on a risk assessment with special reference to the impact of housing, feeding, management and genetic selection

Algers, Bo; Blokhuis, Harry; Bötner, A; Broom, DM; Costa, P; Domingo, M; Greiner, M; Hartung, J; Koenen, F; Müller-Graf, C; Raj, M; Morton, DB; Osterhaus, A; Pfeiffer, DU; Roberts, R; Sanaa, M; Salman, M; Sharp, JM; Vannier, P; Wierup, Martin

Sammanfattning

Following a request from the European Commission, the AHAW Panel was asked to deliver a Scientific Opinion on the welfare of dairy cows, considering whether current farming and husbandry systems comply with the requirements of and welfare of dairy cows from the pathological, zootechnical, physiological and behavioural points of view. Due to the great diversity of topics and the huge amount of scientific data, it was proposed that separate scientific opinions on different welfare subjects would be more adequate and effective. Therefore, it was agreed to subdivide the risk assessment process into four different subjects: i) metabolic and reproductive disorders, ii) udder disorders, iii) leg and locomotion problems and iiii) behaviour, fear and pain. A fifth scientific opinion integrates conclusions and recommendations from the scientific report with the outcomes from the four separate risk assessments. The scientific opinion on welfare of dairy cows in relation to metabolic and reproductive problems, based on a risk assessment with special reference to the impact of housing, feeding, management and genetic selection, was adopted by the AHAW Panel on 05 June 2009. In the risk assessment four different farming scenarios were considered: 1) cubicle houses; 2) tie-stalls; 3) straw yards; 4) pasture. Identified hazards were classified under (a) housing, (b) nutrition and feeding, (c) management and (d) genetics. The risk assessment outcomes for each of these four classes of hazards were determined and the four different farming scenarios compared. When comparing the different farming systems it can be concluded that the risk of suffering metabolic and reproductive disorders is independent of the housing system; however, lower risk estimate values were observed for animals kept at pasture, which may indicate that they are less likely to have metabolic and reproductive problems and therefore poor welfare. According to the scoring system used in this analysis, the most important hazards in relation to the housing were poor cubicle design and lack of space in cubicle houses and tie-stalls, respectively, with high risk estimate values. Inadequate ventilation, temperature and humidity were the highest ranked hazard in straw yards. However, the risk estimate and magnitude values in straw yards were much lowers than in cubicles and tie-stalls. Nutrition and feeding related hazards have a major influence on metabolic and reproductive problems defined both in terms of magnitude of the adverse effect and risk estimate. An inadequate transition feeding was the hazard with the highest risk estimates in the three indoor farming systems. Cows are in negative energy balance during early lactation, when functional body tissues may be metabolised to excess, causing poor welfare. This risk is particularly severe in high-producing genetic strains. A transition period feeding that sustains dry matter intake while maintaining optimal body condition at calving reduces this risk. Also, the risk of cow over/under feeding was very high ranked, as well as the risk of an unbalanced diet. Cattle require a diet that is adequate in fibre otherwise the anatomy and physiology of the rumen are impaired and there is increased risk of ruminal acidosis and other related disorders. Unbalanced diet is the major cause of sub-acute ruminal acidosis. Ruminal acidosis (acute and subacute) and parturient paresis (milk fever) can cause very poor welfare in dairy cows. When concentrate dispensers are used, appropriate control is necessary to avoid over/underfeeding and reduce the risk of acute ruminal acidosis. Concentrate feeding facilities on dairy farms should be adequately maintained and diets carefully balanced so as to maintain optimal ruminal fermentation and to minimise negative energy balance. Reproductive disorders can reflect prolonged or short-term poor welfare, such as lack of oestrus, embryonic loss or early abortion due to stress during parturition and in early lactation, and can also cause poor welfare directly, particularly dystocia and genital infections associated with pain or inflammatory reactions. Among the hazards related to the management of dairy cows, inadequate biosecurity was the highest ranked hazard in all husbandry systems. The magnitude of the adverse effect was the same but in the case of pasture the risk estimate value was lower than on the other three systems. Good hygiene should be provided at calving to reduce risk of genital infections. Improper management was also highly ranked in all farming systems. Recent research shows that a reproductive management strategy with extended calving intervals of 15 months or more seems to offer significant advantages for the welfare of high yielding dairy cows, without reducing overall milk production. To reduce risk of dystocia particularly at first calving, heifers should be inseminated after they reach the mature weight for the breed and only sires known to have low incidence of dystocia should be used to breed heifers. Genetic selection for high milk yield with insufficient emphasis on other traits relating to fitness increases the risk of suffering from metabolic and reproductive problems. This risk is greater when housing, nutrition and management are unable to compensate for the adverse effects of genetic selection. The increased inbreeding of recent years may lead to, or be associated with, increased reproductive problems, reduced lifetime milk production and a reduction in breeding performance if it continues. Excessive or prolonged negative energy balance in dairy cows is more likely to occur in the highest producing animals and has been found to be associated with reduced fertility, digestive, metabolic and infectious disease, especially mastitis

Nyckelord

animal welfare; metabolism; reproduction; dairy cows; risk assessment; housing; nutrition and feeding; management; genetic selection; farming systems

Publicerad i

EFSA Journal
2009, nummer: 7, artikelnummer: 1140Utgivare: EFSA