title: Genetic parameters of several measures of milk flow rate and milking time.
abstract: Heritabilities and genetic correlations of milking rate, time, and yield were estimated by intrasire regression of daughter on dam for 252 Holstein pairs. Heritabilities were: lactation yield, .51 +/- .11; peak rate, .47 +/- .11; bucket milk yield, .38 +/- .10; average rate, .37 +/- .12; milk yield to .45 kg/min, .19 +/- .12; total time, .17 +/- .12; duration of peak rate, .10 +/- .10; strip time, .08 +/- .15; yield during peak rate, .07 +/- .11; and strip yield, .01 +/- .17. The genetic correlation of peak rate with lactation milk yield was .69 +/- .08, indicating substantial genetic improvement in milking rate by selecting for milk production. The genetic correlation between total milking time and lactation milk yield was .50 +/- .20, indicating an increase in total milking time due to selection for milk. Direct selection for peak rate would provide an opportunity to reduce total milking time.
mesh_terms: D000818:Animals; D002417:Cattle / Q000502:physiology*; D003612:Dairying; D005260:Female; D005823:Genetics; D007734:Kymography; D007774:Lactation; D008893:Milk Ejection; D010298:Parity; D010641:Phenotype; D011247:Pregnancy; D012212:Rheology; D012641:Selection, Genetic; D013997:Time Factors