Genetic variation in dairy cattle claw health traits recorded by claw trimmers
Claw health has been recorded by claw trimmers at trimming in Sweden since 1996, but data was then captured at each AI association. From 2003 data was captured by central scanning and entered directly to the national cow data base at the Swedish Dairy Association (SDA). This reporting was introduced because SDA wanted to be able to use these records to improve dairy cow claw health by breeding. It is desirable with cows that have healthy claws, because poor claw health can contribute to impaired production and fertility.
The claw health report begins with some information about herd, claw trimmer, date et cetera and continues with the part where the claw health is recorded. Here the ID of each cow is filled in and on the same row the conditions for dermatitis, heel horn erosion, sole haemorrhage and sole ulcer are recorded as no lesion (blank), slight lesion (/) or severe lesion (X).
The aim of this study was to estimate genetic parameters and repeatabilities between lactations for dermatitis, heel horn erosion, sole haemorrhage and sole ulcer from the reported claw health records. Data collected between 2003 and June 2007 for Swedish Holstein (SH)and Swedish Red dairy cattle (SR) were used in the study. The edited data sets consisted of 65 816 records from first and 24 121 records from second lactation of SH, and of 58 457 records from first and 22 282 records from second lactation of SR. Results show that heritabilities for the claw diseases were relatively low. For SH, heritabilities in first lactation were between 0.035 (sole ulcer) and 0.079 (dermatitis) and in second lactation between 0.032 (sole ulcer) and 0.079 (sole haemorrhage). For SR they were between 0.038 (sole ulcer) and 0.059 (sole haemorrhage) in first lactation and between 0.028 (sole ulcer) and 0.085 (heel horn erosion)in second lactation. Correlations between the claw diseases were estimated and showed highest correlations between dermatitis and heel horn erosion (0.86 for SR and 0.64 for SH)and also between sole haemorrhage and sole ulcer (0.70 for SR and 0.72 for SH). The genetic correlation for the same disease between lactations was high (0.84 and higher). The conclusions of this study are that the claw health reports are very useful. Heritabilities was relatively low but were sufficient enough to be possible to improve claw health through breeding. Correlations were very high within disease between lactations and also high between dermatitis and heel horn erosion as well as between sole haemorrhage and sole ulcer.