The hidden cost of disease: Ⅱ. Impact of the first incidence of lameness on production and economic indicators of primiparous dairy cows

摘要

Lameness is a persistent and underreported healthand welfare problem in the dairy industry, resulting inreduced cow performance and profitability as well asearly culling. The study objectives were (1) to quantifythe impact of the first instance of lameness, at differentstages of lactation, on production and economic performance,and (2) to further quantify the impacts of thefirst instance of lameness when only cows that remainin the herd for at least 100 d in milk (DIM) and thosethat remain for 305 DIM are included in the analysis.A retrospective longitudinal study was conducted usingpre-existing data from animal health records and DairyHerd Improvement Association records. Data wereedited based on selected inclusion criteria, yielding adata set containing records from 15,159 first-lactationHolstein cows from 120 herds with year of first calvingbetween 2003 and 2014. Lame cows were assignedto 1 of 4 groups based on when in the lactation thefirst event of lameness occurred: transition (1–21 DIM),early lactation (22–100 DIM), mid-lactation (101–200DIM), or late lactation (201+ DIM). Mid- and latelactationlame cows were also stratified by cumulativemilk yield before the lameness event. Healthy cows (i.e.,no recorded lameness event) were randomly assignedfor each lactation stage, with mid-lactation healthy andlate-lactation healthy cows similarly stratified. Productionperformance (cumulative milk, fat, and proteinyield) and economic performance [milk value, marginover feed cost (MOFC), and gross profit] were analyzedusing a mixed model with herd as a random effect.Cumulative milk yields were 811 to 1,290 kg lower forlame cows than for healthy cows, with milk componentyields undergoing similar reductions. Reductions in milkyield contributed to losses in milk value (−Can$527to −Can$1,083; −US$419 to −US$862) and MOFC (−Can$510 to −Can$774; −US$406 to −US$616). Higherlosses were reported using gross profit (−Can$753 to−Can$1,052; −US$599 to −US$837), which includesall lameness-related costs. Production and performancelosses were smaller when 100 DIM and 305 DIM thresholdswere applied (i.e., exclusion of cows culled before100 and 305 DIM, respectively), however, mid- andlate-lactation lame cows maintained high levels of significantlosses for all 6 variables analyzed. Lamenessalso led to higher levels of culling, masking losses fortransition and early-lactation lame cows in the 305-DIM analysis. Increasing producer understanding ofthe costs associated with lameness not only serves toprovide insight to producers for more informed cullingdecisions, but may also help producers weigh the costsof adopting new methods and technologies targeted atreducing on-farm lameness.