Abstract #497

# 497
The use of single measurements to assess growth of dairy calves and the effect of management practices on calf BW variability.
Guilherme B. Bond*1, Daniel M. Weary2, Marina A. G. von Keyserlingk2, Lorraine Doepel1, Karin Orsel1, Herman W. Barkema1, Edmond A. Pajor1, 1University of Calgary, Calgary, AB, Canada, 2University of British Columbia, Vancouver, BC, Canada.

Bridging the gap between research methods and application on commercial farm settings is necessary to stimulate producers to use new management practices that promote better calf welfare. Our objectives were to evaluate the association between a single measurement of calf BW and management practices and identify practices related to higher BW residuals. Farms (n = 82) were selected through convenience sampling, had at least 80 Holstein lactating cows and used DHI recording systems. Visits occurred once from June 2010 to August 2012 in AB and BC, Canada. Producers were interviewed about their pre-weaning calf management practices and heart girth was measured for all available calves from 0 to 8 weeks of age. The final database contained data from 865 calves from 57 farms in AB (567 calves) and 25 farms from BC (298 calves). Calf BW was regressed against age and the resulting line equation was BW = 40.56 + 4.649 × Age (wk). Calf BW residuals were calculated by subtracting the actual BW from the expected BW at each age. Individual animal BW residuals were averaged by farm to represent calf growth on each farm. Average farm BW residuals ranged from −16.5 kg to +16.7 kg. The association between management practices and calf BW residuals was tested at calf-level using mixed models in SAS 9.4. Management variables significant in a univariable model (P < 0.20) were included in the final multivariable model (P < 0.05). Feeding more than 5 L of milk per day through a teat was associated with higher BW. Conversely, calves fed less than 5 L of milk by bottle had the lowest BW when compared with the other feeding strategies. Feeding milk by bucket, regardless of the amount, was associated with lower BW. Calves introduced to water at an earlier age had higher BW than calves introduced to water later than 2 mo of age. Calves housed in groups had lower BW when compared with calves housed in individual pens; mixed housing (using 2 or more different types of housing) resulted in the lowest BW compared with other systems. The growth measurement used in this study was successful in describing differences of calf growth among farms. These differences were related to practices such as feeding more milk by teat and early introduction to water.

Key Words: welfare, feeding, water