Selection for mastitis resistance in dairy cattle: a review with focus on the situation in the Nordic countries

A genetic analysis of longitudinal binary clinical mastitis (CM) data recorded on about 90 000 first-lactation Swedish Holstein cows was carried out using linear random regression models (RRM). This method for genetic evaluation of CM has theoretical advantages compared to the method of linear cross-sectional models (CSM), which is currently being used. The aim of this study was to investigate the feasibility and suitability of estimating genetic parameters and predicting breeding values for CM with a linear sire RRM. For validation purposes, the estimates and predictions from the RRM were compared to those from linear sire longitudinal multivariate models (LMVM) and CSM. For each cow, the period from 10 days before to 241 days after calving was divided into four 1-week intervals followed by eight 4-week intervals. Within each interval, presence or absence of CM was scored as '1' or '0'. The linear RRM used to explain the trajectory of CM over time included a set of explanatory variables plus a third-order Legendre polynomial function of time for the sire effect. The time-dependent heritabilities and genetic correlations from the chosen RRM corresponded fairly well with estimates obtained from the linear LMVM for the separate intervals. Some discrepancy between the two methods was observed, with the more unstable results being obtained from the linear LMVM. Both methods indicated clearly that CM was not genetically the same trait throughout lactation. The correlations between predicted sire breeding values from the RRM, summarized over different time periods, and from linear CSM were rather high. They were, however, less than unity (0.74 to 0.96), which indicated some re-ranking of sires. Sire curves based on the time-specific breeding values from the RRM illustrated differences in intercept and slope among the best and the worst sires. To conclude, a linear sire RRM seemed to work well for genetic evaluation purposes, but was sensitive for estimation of genetic parameters.Keywords: dairy cattle, genetic evaluation, clinical mastitis, random regression model ImplicationsLinear random regression models (RRM) were used as a new longitudinal approach for genetic evaluation of clinical mastitis data in dairy cattle. This approach has theoretical advantages compared to the method of linear cross-sectional models (CSM) currently used. The estimated genetic parameters and predicted breeding values from the RRM were in good agreement with the results from linear longitudinal multivariate and linear CSM. However, the RRM approach was sensitive to parameter estimation in the current setting.

Section: Genetic Parameterscontrasting

confidence: 54%

Section: Random Regression Models For Clinical Mastitismentioning

confidence: 99%

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Random regression models for genetic evaluation of clinical mastitis in dairy cattle

Carlén

Grandinson

Emanuelson

et al. 2009

“…Carlé n et al (2005) obtained incidence levels of 10%, 12% and 15% in Swedish Holstein for numbers of cows affected in parities 1, 2 and 3, respectively. These were lower incidences than UK data, which would be understandable as udder health including mastitis has been a breeding goal in Sweden since 1984 (Heringstad et al, 2000), but also the observation period was shorter (for the period of 10 days before calving to 150 days from calving). Mastitis incidence of a herd is influenced by age structure, which has also been shown by many studies that have included later parities, and found mastitis incidence to increase with parity (Pö sö and Mä ntysaari, 1996;Carlé n et al, 2005;Appuhamy et al, 2009).…”

Section: Discussionmentioning

confidence: 65%

Genetic parameters for production, health, fertility and longevity traits in dairy cows

Pritchard

Coffey

Mrode

et al. 2013

139

108

Milk production, fertility, longevity and health records, were extracted from databases of two milk recording organisations in the United Kingdom for the first three lactations of the Holstein-Friesian breed. These included data related to health events (mastitis and lameness), voluntarily recorded on a proportion of farms. The data were analysed to calculate disease incidence levels and to estimate genetic parameters for health traits and their relationships with production and other functional traits. The resulting dataset consisted of 124 793 lactations from 75 137 animals of 1586 sires, recorded in 2434 herds. Incidence of health events increased with parity. The overall incidence of mastitis (MAS) and lameness (LAM), defined as binary traits, were 17% and 16%, respectively. Heritability estimates for MAS and LAM were 0.04 and 0.02, respectively, obtained from repeatability linear sire models. Heritability estimates of mastitis and lameness as count traits were slightly higher, 0.05 and 0.03, respectively. Genetic correlations were obtained by bivariate analyses of all pair-wise combinations between milk 305-day yield (MY), protein 305-day yield (PY), fat 305-day yield (FY), lactation average log e transformed lactation average somatic cell count (SCS), calving interval (CI), days to first service (DFS), non-return at 56 days (NR56), number of inseminations (NINS), mastitis (MAS), number of mastitis episodes (NMAS), lameness (LAM), number of lameness episodes (NLAM) and lifespan score (LS). As expected, MAS was correlated most strongly with SCS (0.69), which supports the use of SCS as an indicator trait for mastitis. Genetic correlations between MAS and yield and fertility traits were of similar magnitude ranging from 0.27 to 0.33. Genetic correlations between MAS with LAM and LS were 0.38 and 20.59, respectively. Not all genetic correlations between LAM and other traits were significant because of fewer numbers of lameness records. LAM had significant genetic correlations with MY (0.38), PY (0.28), CI (0.35), NINS (0.38) and LS (20.53). The heritability estimates of mastitis and lameness were low; therefore, genetic gain through direct selection alone would be slow, yet still positive and cumulative. Direct selection against mastitis and lameness as additional traits should reduce incidence of both diseases, and simultaneously improve fertility and longevity. However, both health traits had antagonistic relationships with production traits, thus genetic gain in production would be slower.

“…Sub-clinical mastitis is generally diagnosed by an increase in somatic cell counts (SCC) in the milk. Although heritability for mastitis (,0.04) and SCC (0.11) in dairy cattle is low, the genetic correlation between the two is high (,0.70), so that SCC can be conveniently used in selection index to reduce the incidence of mastitis in cows (Mrode et al, 1998;Heringstad et al, 2000;Colleau and Regaldo, 2001;Willam et al, 2002) and ewes (Barillet et al, 2001;Rupp et al, 2003). These examples show the potential of genetic selection and significant progress may be made by the exploration of the molecular polymorphism responsible for these genetic effects on susceptibility to disease.…”

Section: Introductionmentioning

confidence: 99%

Minimising pain in farm animals: the 3S approach – ‘Suppress, Substitute, Soothe’

Guatteo

Levionnois

Fournier

et al. 2012

Recently, the French National Institute for Agricultural Research appointed an expert committee to review the issue of pain in food-producing farm animals. To minimise pain, the authors developed a ‘3S’ approach accounting for ‘Suppress, Substitute and Soothe’ by analogy with the ‘3Rs’ approach of ‘Reduction, Refinement and Replacement’ applied in the context of animal experimentation. Thus, when addressing the matter of pain, the following steps and solutions could be assessed, in the light of their feasibility (technical constraints, logistics and regulations), acceptability (societal and financial aspects) and availability. The first solution is tosuppressany source of pain that brings no obvious advantage to the animals or the producers, as well as sources of pain for which potential benefits are largely exceeded by the negative effects. For instance, tail docking of cattle has recently been eliminated. Genetic selection on the basis of resistance criteria (as e.g. for lameness in cattle and poultry) or reduction of undesirable traits (e.g. boar taint in pigs) may also reduce painful conditions or procedures. The second solution is tosubstitutea technique causing pain by another less-painful method. For example, if dehorning cattle is unavoidable, it is preferable to perform it at a very young age, cauterising the horn bud. Animal management and constraint systems should be designed to reduce the risk for injury and bruising. Lastly, in situations where pain is known to be present, because of animal management procedures such as dehorning or castration, or because of pathology, for example lameness, systemic or local pharmacological treatments should be used tosoothepain. These treatments should take into account the duration of pain, which, in the case of some management procedures or diseases, may persist for longer periods. The administration of pain medication may require the intervention of veterinarians, but exemptions exist where breeders are allowed to use local anaesthesia (e.g. castration and dehorning in Switzerland). Extension of such exemptions, national or European legislation on pain management, or the introduction of animal welfare codes by retailers into their meat products may help further developments. In addition, veterinarians and farmers should be given the necessary tools and information to take into account animal pain in their management decisions.