Genetic Analysis of Clinical Mastitis Data from On-Farm Management Software Using Threshold Models

Abstract

Producer-recorded clinical mastitis data from 77,791 cows in 418 herds were used to determine the potential for genetic improvement of mastitis resistance using data from on-farm management software programs. The following threshold sire models were applied: 1) a single-trait lactation model, where mastitis was recorded as 0 or 1 in first lactation only; 2) a 3-trait lactation model, where mastitis was recorded as 0 or 1 in each of the first 3 lactations, and 3) a 12-trait, lactation-segment model, where mastitis was recorded as 0 or 1 in each of 4 segments (0 to 50, 51 to 155, 156 to 260, and 261 to 365 d postpartum) in each of the first 3 lactations. Lactation incidence rates were 0.16, 0.20, and 0.24 in first, second, and third lactation, respectively, and incidence rates within various segments of these lactations ranged from 0.036 in late first lactation to 0.093 in early third lactation. Estimated heritability of liability to clinical mastitis ranged from 0.07 to 0.15, depending on the model and stage of lactation. Heritability estimates were higher in first lactation than in subsequent lactations, but estimates were generally similar for different segments of the same lactation. Genetic correlations between lactations from the 3-trait model ranged from 0.42 to 0.49, while correlations between segments within lactation from the 12-trait model ranged from 0.26 to 0.64. Based on the results presented herein, it appears that at least 2 segments are needed per lactation, because mastitis in early lactation is lowly correlated with mastitis in mid or late lactation. Predicted transmitting abilities of sires ranged from 0.77 to 0.89 for probability of no mastitis during the first lactation and from 0.36 to 0.59 for probability of no mastitis during the first 3 lactations. Overall, this study shows that farmer-recorded clinical mastitis data can make a valuable contribution to genetic selection programs, but additional systems for gathering and storing this information must be developed, and more extensive data recording in progeny test herds should be encouraged.

Genetic parameters for serial, automatically recorded milkability and its relationship to udder health in dairy cattle

“…The same bulls should be used for artificial insemination across the data-recording farms to ensure a genetic connection between the farms. In line with this, Zwald et al (2006) demonstrated the potential usefulness of farmer-recorded clinical mastitis data in selection programmes. In the near future, an individual breeding company may be able to collect mastitis data from a subset of large herds that have the appropriate software and tend to record clinical mastitis cases diligently.…”

“…Figure 6 Mean relative breeding value (RBV) for the three udder-health traits somatic cell score (SCS), mastitis until day 50 of lactation (mastitis 50d) and mastitis until day 305 of lactation (mastitis 305d) by the category of RBVs for average milk flow in all sires (n 5 419). and 0.73 and Zwald et al (2006) estimated genetic correlations between mastitis resistance in the first three lactations ranging from 0.42 to 0.49, indicating that mastitis resistance may be a genetically different trait in the first lactation vs. later lactations or at different intervals.…”

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

“…Binary CM data have been analyzed with the theoretically more appropriate threshold CSM (e.g. Kadarmideen et al, 2000;Hinrichs et al, 2005;Zwald et al, 2006). However, this approach is not in routine use and does not use more of the available information than a linear CSM.…”

Melhoramento genético visando à resistência a mastite em bovinos leiteiros

“…Além disso, a correlação genética entre CCS e incidência de MC tem sido demonstrada relativamente elevada (0, 6-0, 8) e indica que o progresso pode ser feito na redução da MC, selecionando para a redução da CCS. (Heringstad et al, 2003(Heringstad et al, , 2006Nash et al, 2003;Zwald et al, 2006). Os casos clínicos de mastite também são tratados como uma característica de seleção no programa de melhoramento genético para a melhoria da saúde do úbere.…”

“…A inclusão destes registros na avaliação e seleção de touros levou a uma tendência genética reduzida para MC nesses países. Infelizmente, herdabilidade desta característica é relativamente baixa (0, 01-0, 15), com maior contribuição genética observada na primeira lactação (Heringstad et al, 2003;Nash et al, 2003;Zwald et al, 2006). No entanto, estes métodos de seleção de vacas e touros com filhas que mostram capacidade fenotípica de resistir à mastite tiveram um sucesso limitado.…”