The effects of liveweight loss and milk production on the risk of lameness in a seasonally calving, pasture fed dairy herd in New Zealand.

Dairy herd managers have attempted to increase and maintain profits by selectively breeding dairy cattle for high production. Selection for milk production may have resulted in a tendency for greater liveweight (LW) loss postpartum. This study aimed to: (1) determine if excessive LW loss and milk yield in the first 50 days in milk (DIM) was associated with the development of lameness after 50 DIM, and (2) estimate the incidence risk of lameness in this herd attributable to excessive liveweight loss. The dataset comprised details from 564 mixed age cows from a single, seasonally calving, pasture fed dairy herd in New Zealand. After adjusting for the confounding effects of parity, LW at calving, breed, the presence of specified disease events in the first 50 DIM and milk yield, LW loss in the first 50 DIM increased the risk of lameness after 50 DIM by a factor of 1.80 (95% CI 1.00-3.17). The risk of lameness was greatest for high yielding cows that lost excessive LW (risk ratio 4.36, 95% CI 4.21-8.19), but the effect LW loss on lameness risk at the herd level was relatively small. Based on data accumulated during the study we estimate that for this herd, there would be a 3% (95% CI 1-6%) reduction in the incidence risk of lameness if excessive LW loss was prevented. Twenty three percent of the incidence of lameness in this herd was attributable to excessive LW loss. We conclude that policies and interventions to reduce the rate and amount of LW loss in the first 50 DIM will have a non-negligible impact on the incidence risk of lameness in this herd.

The effect of clinical lameness on liveweight in a seasonally calving, pasture-fed dairy herd.

This study investigated the effect of lameness on liveweight (LW) in pasture-fed dairy cattle. The data comprised 222,446 averaged daily LW measurements from 828 lactations of 542 mixed-age cows in a seasonally calving, pasture-fed New Zealand dairy herd. The LW measurements for individual cows were aggregated into weekly averages and analyses conducted to evaluate the effect of a diagnosis of lameness on LW change after controlling for the effect of week in milk, parity, LW at calving, breed, calendar month, and season. In lame cows, LW decreased for up to 3 wk before lameness was diagnosed and for up to 4 wk after treatment. Total LW loss arising from a single lameness episode was, on average, 61 kg (95% confidence interval: 47 to 74 kg). The results from this study demonstrate how LW records for individual animals can be used to enhance a herd manager's ability to detect lame cows and present them for treatment. The methods presented here show how daily LW monitoring might be used as a tool for early detection of lameness in dairy cattle.

Automatic recording of daily walkover liveweight of dairy cattle at pasture in the first 100 days in milk.

Daily walkover liveweight (WoLW) records (n=79,697) from 463 pasture-fed dairy cows from a single dairy herd in the lower North Island of New Zealand were recorded over the first 100 d of lactation. The aims of this study were to (1) describe LW records retrieved by a standalone automatic Wo daily weighing system; (2) describe the frequency and nature of outlier LW records measured by the system and develop an approach for excluding identified outlier LW records; (3) quantify the agreement between cow LW measured using the Wo system and those measured statically; and (4) describe the autocorrelation between daily LW measurements to provide an indication of how frequently management decisions need to be reviewed to effectively monitor cow LW change in the early-lactation period. The standard deviation of daily LW measurements across parities was 17 kg, on average. A near perfect association between LW measured statically and WoLW (concordance correlation coefficient 0.99, 95% CI 0.99-1.0) was observed. After controlling for the effect of LW at calving and long-term LW change using a mixed-effects linear regression model, the autocorrelation between WoLW recorded on successive days was 0.21, decaying to zero by 8 d. This study shows that by using a standalone automatic Wo weighing system positioned in the exit race of a rotary milking parlor, it was possible to record LW of individual cows on a daily basis and, with controlled cow flow over the weighing platform (allowing for sufficient succession distance to prevent congestion), results were similar to those recorded using conventional, static weighing techniques using the same scales. Based on the autocorrelation analyses, we recommend that LW are recorded on a daily basis to allow changes in physiological status such as the onset of acute illness or estrus to be detected. For managerial purposes, such as using LW change as a guide for adjusting the herd feeding program, we recommend a 7-d decision interval to effectively monitor significant changes in cows' recorded daily LW measurements.