Results the conformation traits varied from 20.28 TL to

124 R .A. Mrode et al. Livestock Production Science 65 2000 119 –130

3. Results the conformation traits varied from 20.28 TL to

0.47 FA. Apart from FA, FUA, ANG, UDS, UDD, 3.1. Genetic relationship between LS and BD and TL, the genetic correlations between LS and conformation traits in the AYR breed the conformation traits were all below 0.17, with almost zero genetic correlations observed between Table 5 shows the conformation traits analysed LS and CW, RA, RW, TPR and TPS. Significantly, with abbreviations which will be used in the paper the four conformation traits with the largest genetic together with estimates of heritabilities and the correlations with LS were FA 0.47, UD 0.46, genetic and phenotypic correlations with LS. The FUA 0.28 and TL 20.28. heritability of LS averaged over all the multivariate analyses was low at 0.0660.01. Generally the 3.2. Genetic correlation between LS and SCC phenotypic correlations between LS and the con- formation traits were very low, with a maximum The estimates of genetic correlations between LS correlation of 0.09 with udder depth. and SCC from the bivariate analyses were 20.32 The range of genetic correlations between LS and 0.05 for the HF, 20.28 0.20 for the AYR and Table 5 Phenotypic r and genetic r correlations between Conformation traits and Lifespan, along with heritabilities for all traits in the Ayrshire p g breed 2 a Trait Linear assessment scheme h r r p g Stature STA Very small Very tall 0.55 0.02 0.16 ,125 cm .149 cm 0.10 Chest width CW Very narrow Very wide 0.25 0.01 20.08 and strong 0.11 Body depth BD Very shallow Very deep 0.27 0.02 20.19 0.10 Angularity ANG Very thick Very sharp 0.51 0.06 0.23 and course and angular 0.09 Rump angle RA Pins higher Very low pins 0.27 20.03 20.04 than hips 0.05 Rump width RW Very narrow Very wide 0.38 0.04 0.08 0.08 Rear legs side RLS Very straight Very sickled 0.27 20.04 20.10 and posty 0.07 Foot angle FA Very low Very steep 0.31 0.05 0.47 0.10 Fore udder attachment FUA Very weak loose Very strong 0.26 0.10 0.28 and tight 0.09 Rear udder height RUH Very low Very high 0.40 0.06 0.16 0.08 Udder support UDS Negative cleft, Extreme cleft, 0.09 0.04 0.26 broken support strong support 0.10 Udder depth UDD Level with or Well above 0.22 0.09 0.46 below hock hock 0.08 Teat placement rear TPR Teats on outside Base of teats 0.25 0.05 0.02 of udder almost touching 0.12 Teat placement side TPS Very close Far apart 0.25 0.00 20.04 0.03 Teat length TL Very short Very long 0.37 20.01 20.28 0.10 Lifespan LS 0.06 a Standard errors S.E of r in brackets. The S.E. for the heritability of conformation traits is about 0.02 and that of Lifespan50.01. g R .A. Mrode et al. Livestock Production Science 65 2000 119 –130 125 20.11 0.20 for the JER. These results indicate that generally similar considering all bulls and cows higher SCC resulted in a lower herd life. evaluated. However, higher standard deviations 0.22 were obtained for bull PTAs when bulls with 3.3. Genetic evaluation for LS at least 50 reliabilities were considered. Figs. 1 and 2 show the mean PTA plotted by year of birth for The number of observations together with the bulls with at least 50 daughters and cows, respective- average number of lactations and standard deviations ly. For all breeds, there was a slight positive genetic are given for each breed in Table 4. Across breeds trend for LS. the average LS ranged from 3.8 to 4.0 lactations. The INDEX for the AYR calculated from the This rather high average number of lactations is due genetic correlations between FA, UD, FUA, TL and to the fact cows were required to complete a first LS estimated for this breed in Section 2.1 had a lactation before being included in the evaluation. The heritability of 0.31 compared with 0.36 for HF; and a highest averages were obtained for HF and JER r of 0.62 with LS compared with 0.69 for HF. The g breeds. rank correlation between LS breeding values from Table 6 gives means, standard deviations and the analysis using these AYR breed parameters and ranges of LS PTAs and reliabilities for all bulls for the official breeding values based on HF parameters the different breeds. Similar statistics for cows with was 0.97 for all bulls. The corresponding simple at least one observation either for LS or INDEX in correlation for cows was 0.99. the bivariate analysis are presented in Table 7. The The increase in the reliability of bull PTAs with means for bull PTAs are around zero for all the the inclusion of conformation traits in LS evaluations breeds and ranged from 20.8 lactations to 1.4 is demonstrated in Figs. 3 and 4 for two categories of lactations. However, most bull PTAs are in the range bulls. For bulls with LS observations for 1–20 of 60.5 lactations. The means for cow PTAs varied daughters, the reliability of bull PTAs increased between 0.13 and 0.18 lactations with individual cow linearly with an increase in the number of daughters PTAs ranging from 20.5 to 1.1 lactations. Within with conformation records. There was an increase of each breed, the standard deviations of PTAs were about 110 in reliability when there were 201–500 Table 6 Means and standard deviations S.D. of bull PTAs and reliabilities for Lifespan Breed Numbers of Predicted Transmitting Ability PTA Reliability bulls evaluated Average S.D. Min Max Average S.D. Holstein Friesian 56 360 0.05 0.14 20.7 1.4 0.27 0.19 Ayrshire 5656 0.05 0.18 20.6 0.9 0.27 0.18 Jersey 3556 20.03 0.20 20.6 0.8 0.26 0.19 Guernsey 1584 0.05 0.15 20.4 0.7 0.28 0.21 Shorthorn 1172 20.05 0.19 20.8 0.6 0.21 0.17 Table 7 Means and standard deviations S.D. of cow PTAs for Lifespan Breed Number of Predicted Transmitting Ability PTA cows evaluated Average S.D. Min Max Holstein Friesian 1 839 878 0.16 0.14 20.5 1.1 Ayrshire 156 639 0.18 0.17 20.7 1.0 Jersey 87 939 0.16 0.21 20.5 1.4 Guernsey 56 886 0.13 0.13 20.5 0.8 Shorthorn 22 905 0.13 0.21 20.4 1.1 126 R .A. Mrode et al. Livestock Production Science 65 2000 119 –130 Fig. 1. Trend in Lifespan predicted transmitting abilities for bulls. Fig. 2. Trend in Lifespan predicted transmitting abilities for cows. daughters with conformation records. However, for 4. Discussion bulls with LS records for 201–500 daughters the increase in reliability with an increase in conforma- The low heritability of 0.06 for LS is in general tion records was only marginal. consistent with estimates for various measures of R .A. Mrode et al. Livestock Production Science 65 2000 119 –130 127 Fig. 3. Increase in reliability of predicted transmitting abilities of bulls with Lifespan records for 1–20 daughters with varying numbers of daughters with conformation records. functional herd life observed in several breeds and and Short and Lawlor 1992 reported r of 0.47 and g from different methods of estimation. Boldman et al. 0.44, respectively, between udder depth and func- 1992 reported a lower estimate of 0.03 for func- tional herd life in Holsteins compared with 0.46 in tional herd life for Holstein grade cows and the this study. The genetic correlations reported by estimates reported for the Guernsey breed ranged various udder traits and herd life for the Jersey from 0.02 to 0.05 Harris et al. 1992. Using a Rogers et al. 1991a varied from 0.35 to 1.00, with restricted maximum-likelihood procedure with an most being higher than obtained in this study. On the animal model, Vollema and Groen 1998 reported a other hand body traits, in agreement with the results similar estimate of 0.04 for functional herd life in of Van Doormaal et al. 1985, are poorly correlated Holstein cows born from 1985 and Brotherstone et with herd life. al. 1997 the same estimate of 0.06 as obtained in Vollema 1998 indicated no major differences this study for the Holstein breed in the UK. The between breeds in terms of the relationship between estimate reported for functional length of productive conformation traits and herd life. However, the life by Ducrocq et al. 1988 was slightly higher at results from the AYR data indicated a reasonable 0.09 from a survival analysis with a sire model. correlation of 0.23 between angularity and LS in In common with the results of Brotherstone et al. contrast to a correlation of 20.02 for the HF 1998, the largest genetic associations were ob- Brotherstone et al. 1998. Similar to the results for served between FA, UD, FUA, TL and LS. In the AYR, Klassen et al. 1992 also reported a general, moderate to high r have been observed in correlation of 0.44 between angularity and longevity g several studies between udder and teat traits and measured in terms of number of lactations in the various measures of herd life. Boldman et al. 1992 Holstein breed. 128 R .A. Mrode et al. Livestock Production Science 65 2000 119 –130 Fig. 4. Increase in reliability of predicted transmitting abilities of bulls with Lifespan records for 201–500 daughters with varying numbers of daughters with conformation records. One of the main benefits of conformation traits is proofs. Theoretically, Brotherstone et al. 1998, that they are measured during the first lactation and showed the gain in accuracy in bull progeny tests can therefore be used as early predictors of LS. For from combining information on conformation and linear scored conformation traits such as used in this LS. Figs. 3 and 4 demonstrate this gain in a practical study the direct functional relationship between these sense and indicate much of the gain in accuracy is traits and LS can be demonstrated; for instance, very for young bulls with no or little direct survival weak or loose attached fore udders would result in information. However, Brotherstone et al. 1998 the animal being culled early in life. However, the indicated that Type Merit which was moderately results of Rogers et al. 1991b and Mrode et al. correlated with LS and some of the conformation 1999 seem to indicate an indirect functional rela- traits used to indirectly predict LS, could be used as tionship between conformation traits and LS through a culling criterion in its own right. If that is the case, SCC. Both studies obtained negative r between the r between herd life and type traits could be g g udder traits and SCC, implying selection for higher, biased upwards and hence reliability of indirect sire more tightly attached udders should lower levels of evaluations based on conformation traits Essl, SCC resulting from infections and reduce the rate of 1998. involuntary culling. Other workers have demonstra- The negative r observed between LS and SCC is g ted the usefulness of udder traits in addition to SCC consistent with expectation as animals with higher in reducing incidence of mastitis De Jong and SCC as a result of infection would be subject to Lansbergen, 1996. involuntary culling. Presently in the UK, PTAs for Another benefit of the use of conformation traits in SCC are published but not incorporated into any herd life evaluations is the increased accuracy of index. As discussed subsequently LS is included in R .A. Mrode et al. Livestock Production Science 65 2000 119 –130 129 an index with production traits in the UK to improve Van Raden and Klaas-Kate, 1993. The trend was profitability. However, on the basis of these results, positive for herd life unadjusted for production as inclusion of SCC in such an index should result in might be expected. greater accuracy of prediction and hence increase profitability. The use of bivariate BLUP for the prediction of

5. Conclusions