Health Care Requirements of Dairy Cattle. II. Nongenetic Effects

Health data were compiled for 293 Holstein cows by 80 sires over 9 yr. Supplemental labor and veterinary expense were recorded specific to a cow on a daily basis. Each entry was assigned to one of six health functions: mammary, locomotion, respiration, reproduction, digestion, and other. Prior to least squares analysis, daily information was summed to form 3-mo, seasonal observations. Nongenetic effects significantly contributing to variability for the sum of health functions for labor and expense were: season, stage of lactation (partitioned into 50-day intervals), year (labor only, expense not significant), parity, season and stage interaction, and a covariable for duration of seasonal observation. Sire and cow effects were not considered. Summer season imparted a deleterious effect on health. Stage of lactation was the greatest source of variation with early stages quadruple later stages. Increases from first to fifth and later lactations were threefold. Season and stage interaction indicated a late summer through early winter calving advantage in decreasing annual requirements for health care.