The study objective was to assess the effects of limit feeding dairy heifers on behavior patterns and feeding motivation. Ten Holstein heifers were exposed to each of 2 dietary treatments, over 2 successive 26-d treatment periods (14-d adaptation period and a 12-d data collection period) using a crossover design:

(1) a high-forage total mixed ration (TMR), provided ad libitum

(2) a low-forage TMR, limit-fed at 2.05% body weight 

Heifers were fed once daily and motivation to access a low-nutritive feedstuff (straw) was assessed using a push-door apparatus at 2 time points: 3 h after feed delivery and 21 h after feed delivery. The amount of weight pushed, weight pushed as percentage of body weight, and latency to access the push door were recorded on 3 different days for each heifer at each time point on each treatment.

When fed ad lib heifers had greater dry matter intake (12.9 vs. 7.2 kg/d), greater feeding time (209.3 vs. 82.4 min/d), greater ruminating time (452.2 vs. 318.3 min/d), and slower rates of intake (0.06 vs. 0.09 kg of dry matter/min) than when limit fed.

Limit fed heifers pushed more weight as a percentage of body weight at 3 h (4.5 vs. 1.9%) and 21 h (9.3 vs. 2.8%) after feed delivery. At both 3 and 21 h after feed delivery, time until they accessed the door to the straw was shorter for the limit fed heifers compared with the ad lib heifers (65 vs. 145 s).

These results indicate that, in addition to decreasing feeding time, limit feeding increases motivation of heifers to access a low-nutritive feedstuff, possibly due to lack of satiety resulting from lack of physical fill or insufficient time spent foraging.

Link to JDS Abstract

Author: T.J. DeVries, Department of Animal and Poultry Science, University of Guelph,  tdevries@uoguelph.ca