title: Genetic and crossbreeding parameters for incidence of recorded clinical lameness in New Zealand dairy cattle.
abstract: OBJECTIVE
  To estimate genetic and crossbreeding parameters for the incidence of recorded clinical lameness in New Zealand dairy cattle.
  
  
  METHODS
  Herd records from 76,357 cows, collected during the 2005/06 to 2008/09 milking seasons from 155 herds in the Livestock Improvement Corporation young sire progeny test scheme, were used to estimate genetic parameters and breed effects for incidence of recorded clinical lameness in HolsteinFriesian, Jersey and crossbred dairy cattle. Recorded clinical lameness was coded "1" for cows that presented at least one event of clinical lameness at any day during the season and "0" for unaffected cows. Genetic parameters were estimated using an animal model across breeds considering all and then only first lactation records. Heritability and repeatability of recorded clinical lameness were calculated from the variance component estimates both with and without logit transformation.
  
  
  RESULTS
  The mean incidence of recorded clinical lameness per herd was 6.3 (min 2, max 34)%. The incidence of recorded clinical lameness in Holstein Friesian cows (mean 6.8, SE 0.24%) was higher than the incidence of recorded clinical lameness in crossbred (mean 6.1, SE 0.19%) and Jersey cows (mean 6.0, SE 0.28%) (p=0.0002). There was no difference in incidence between crossbred and Jersey cows (p=0.96). Estimates of the heritability of recorded clinical lameness as an untransformed trait were 0.053 (SE 0.014) for first lactation records and 0.016 (SE 0.003) for all lactation records. As a transformed (logit) trait heritabilities were 0.067 (SE 0.024) and 0.044 (SE 0.016) for first and all lactation records, respectively. The repeatability estimates of recorded clinical lameness were 0.071 (SE 0.005) and 0.107 (SE 0.011) for untransformed and logit transformed lactation records, respectively. Sire estimated breeding values for recorded clinical lameness showed the lowest values in Jersey sires, and ranged between -5 and 8%.
  
  
  CONCLUSIONS
  Despite the low heritability of recorded clinical lameness, this study provided evidence that there is significant exploitable animal genetic variation. Selection of specific sires across and within breeds could be an option for increasing genetic resistance to lameness in New Zealand dairy cattle.
authors: Tanzania Livestock Research Institute, Mpwapwa, Tanzania.
authors: A R
authors: AR
authors: Chawala
authors: N
authors: N
authors: Lopez-Villalobos
authors: J K
authors: JK
authors: Margerison
authors: R J
authors: RJ
authors: Spelman
mesh_terms: D000818:Animals; D001947:Breeding; D002417:Cattle; D002418:Cattle Diseases / Q000235:genetics*; D003433:Crosses, Genetic; D003612:Dairying; D020022:Genetic Predisposition to Disease; D014644:Genetic Variation; D015994:Incidence; D007794:Lameness, Animal / Q000453:epidemiology / Q000235:genetics*; D009520:New Zealand