Variability in feeding behavior between individual dairy cows fed under different levels of competition

Abstract Text:

The objective of this study was to investigate the effects of differing levels of competition for feed access on group-housed dairy cows and on the variation in feeding behavior between individuals within the group. We hypothesized that as competition increases: 1) cows will consume feed faster and in larger meals, and 2) individuals within the group will experience greater variability in feed consumption patterns. Eighteen lactating Holstein dairy cows with average DIM of 77±20 d and production of 46±7 kg/d at the start of the trial, were divided into groups of 3 and fed 3x/d. Groups were exposed to each of 3 competition levels: high (3 cows: 1 feed bin), moderate (3 cows: 2 feed bins), and low (3 cows: 3 feed bins). Treatments were assigned in random order according to a modified Latin Square design and applied for 10 d. DMI and feeding behavior (feeding time, feeding rate and meal patterns) for each cow were recorded using an automated feed intake system on d 6-10 of each period. Data were summarized by group and treatment period, and analyzed in a general linear mixed model. DMI (29.1 kg/d) was found to be similar (P=0.63) across treatments. Increased competition resulted in a reduction in feeding time (Low=202.6; Moderate=194.9; High=83.6 min/d; SED=4.49; P=0.015), especially following fresh feed delivery and milking. Rate of feed intake increased with greater competition (Low=0.16; Moderate=0.18; High=0.20 kg DM/min; SED=0.01; P=0.01). Meal frequency (8 meals/d) and size (4.0 kg DM/meal) were unaffected by treatment (P>0.40), while meal length increased under high competition (Low=37.0; Moderate=36.6; High=47.3 min/meal; SED=3.7; P=0.046). This was due to greater within-meal non-feeding time, which at the high competition level, was approximately double that of the other treatment levels (Low=10.0; Moderate=10.8; High=20.3 min/meal; SED=2.3; P=0.008). Analysis of individual within group variability, calculated as the daily SD of each group averaged across d 6-10, revealed treatment differences in variability of meal length (Low=12.0; Moderate=13.9; High=29.0 min/meal; SED=5.56; P=0.04) and within-meal non-feeding time (Low= 6.4; Moderate= 8.3; High= 21.5 min/meal; SED=4.57; P=0.03). These results suggest that at elevated competition levels, cows modify their feeding behavior to consume more feed in a shorter period of time and devote a large portion of their meal time towards waiting to gain feed access. Further, there is greater variability in meal patterns within groups at higher levels of competition for feed access.

Keywords: Dairy cow, feeding behavior, competition, meal patterns