Genetic covariance functioners for live weight, condition score, and dry-matter intake measured at different lactations stages of Holstein-Friesian heifers

Genetic parameters for live weight, body condition score and dry-matter intake of dairy heifers were estimated using covariance function methodology. Data were from 469 heifers of the Langhill Dairy Cattle Research Centre and included observations during the first 25 weeks in lactation. Genetic variance for live weight and condition score were estimated by a second order polynomial covariance function, whereas the genetic variance for DMI was described by a third order polynomial covariance function. Heritability estimates for observations measured at different stages of lactation ranged from 0.43 to 0.56 for live weight, from 0.21 to 0.45 for condition score and from 0.18 to 0.37 for dry-matter intake. Genetic correlations between repeated observations for live weight and condition score were large (0.84 to 1.00). For dry-matter intake, observations in early lactation had only a low to moderate genetic correlation to observations in mid-lactation