Abstract #231

# 231
Effect of plane of nutrition in pre- and post-weaning phases on feed sorting behavior of dairy calves.
Lauren E. Engelking*1, Justin P. Rosadiuk1, Tony C. Bruinje1, Trevor J. DeVries2, Michael A. Steele1, 1University of Alberta, Edmonton, AB, Canada, 2University of Guelph, Guelph, ON, Canada.

Nutrition has an impact on the behavior of dairy calves in the pre- and post-weaning phases; however, an interaction between these 2 phases is poorly understood. Thus, the objective of this study was to investigate how plane of nutrition in the pre- and post-weaning phases affects feed sorting behavior post-weaning. Twenty Holstein heifer calves were randomly assigned to treatments according to a 2 × 2 factorial design. Treatments were (1) low pre- and low post-weaning, (2) low pre- and high post-weaning, (3) high pre- and low post-weaning, and (4) high pre- and high post-weaning. Calves were fed 5 L/d (2.5 L, 2 × /d; low) and 10 L (2.5 L, 4 × /d; high) of milk on an automated calf feeder from 1 to 8 wks. Water, concentrate, and chopped straw were provided free choice during the pre-weaning phase. During the post-weaning phase calves were fed a dry TMR containing (as-fed) 30% chopped straw and 70% concentrate (low) or 15% chopped straw and 85% concentrate (high) from wk 9–16. Feed refusal samples were collected once weekly from wk 10 - 16 to assess feed sorting using the Penn State Particle Separator (3 screens: 19, 8, and 1.18 mm) separating into long, medium, short, and fine components. Sorting was calculated as the percentage of actual intake relative to predicted intake. Values > 100% indicated sorting for, and values < 100% indicated sorting against. Statistical analyses were performed using the MIXED procedure of SAS 9.4. Plane of nutrition fed pre-weaning did not have affect feed sorting behavior post-weaning. However, calves fed a low plane of nutrition post-weaning tended to sort for more short particles than calves fed high plane of nutrition post-weaning (102.8 vs. 100.8%; P = 0.10). Post-weaned low plane calves sorted against medium particles, whereas post-weaned high plane calves sorted for medium particles (95.6 vs. 101.3%; P < 0.001). Our results suggest that plane of nutrition fed before weaning does not influence post-weaning sorting behavior, whereas providing a higher plane of nutrition post-weaning through an increased concentrate proportion decreases the incidence of feed sorting.

Key Words: feed sorting, plane of nutrition, pre- and post-weaning