title: A prospective study of calf factors affecting first-lactation and lifetime milk production and age of cows when removed from the herd.
abstract: This prospective study was designed to investigate possible carryover effects of calf management practices and how events occurring during the first 16 wk of life affect first-lactation and lifetime milk production as well as age when animals are removed from production. This is the final of 3 stages in a longitudinal study that encompassed 10 yr of data collection. First, management and nutritional data were collected in the first 16 wk of life. The second part of this study evaluated conditions of animals at the time of first calving as affected by calf management, nutrition, and health. Both of these studies have been previously reported. This third portion covers the same calf effects on lactation performance and age at culling. Observations for the current study were collected from on-farm and Dairy Herd Improvement records. The multiple imputation technique was used in this analysis to avoid bias due to missing data. This study concluded that delivery score, weaning dry matter intake, days of illness before 4 mo, days treated before 4 mo, and body weight at first calving all had significant effects on first-lactation production of Holsteins. Delivery score and grain intake at a young age affected lifetime production. Age at culling was only affected by early grain intake in this study.
authors.affiliation: Department of Dairy and Animal Science, The Pennsylvania State University, University Park, PA 16802, USA. ajh@psu.edu
authors.forename: A J
authors.initials: AJ
authors.lastname: Heinrichs
authors.forename: B S
authors.initials: BS
authors.lastname: Heinrichs
mesh_terms: D000367:Age Factors; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D001823:Body Composition; D002417:Cattle / Q000502:physiology*; D003612:Dairying / Q000379:methods; D004032:Diet / Q000662:veterinary; D002523:Edible Grain; D005260:Female; D007774:Lactation / Q000502:physiology*; D008892:Milk / Q000378:metabolism*; D011446:Prospective Studies; D013997:Time Factors