A new research study, published in the April issue of the Journal of Dairy Science, looked at the effect of feed-delivery method on growth, feeding competition, feeding and sorting behavior of dairy heifers.

Thirty-two Holstein heifers were divided into eight groups of four and exposed to one of two feed-delivery treatments for 13 weeks. The treatment rations contained 65 percent grass/alfalfa haylage and 35 percent textured concentrate (on a dry matter basis) fed as either a total mixed ration (TMR) or as a top-dressed ration (TDR).

Group dry matter intakes were recorded daily throughout the experiment. Feeding behavior was recorded using time-lapse video, and sorting behavior was measured for seven days during week one, five, nine and 13. Sorting activity was determined through particle size analysis of the fresh feed and orts. The particle size separator separated feed into four fractions (long, medium, short and fine). Sorting of each fraction was calculated as actual intake expressed as a percentage of predicted intake. Heifers were fecal scored for consistency of stool twice weekly using a scale from one (liquid) to four (solid); heifers were weighed every two weeks.

Neither dry matter intake nor average daily gain differed between treatments. Heifers fed the TDR tended to consume less neutral detergent fiber than heifers fed the TMR. Heifers fed the TDR sorted against long particles and consumed short particles to a greater extent than did heifers fed the TMR. Daily feeding time did not differ between treatments, but heifers on the TDR did spend more time at the bunk in the two hours following feed delivery. Heifers fed the TDR were displaced from the feed bunk more frequently than heifers fed the TMR, particularly during the two hours following feed delivery. Fecal scores were lower for heifers on the TDR.

These results suggest that feeding a TMR to replacement dairy heifers may promote a more even daytime feeding pattern, minimize feed sorting and feed bunk competition, and promote more solid fecal consistency.

Source: Journal of Dairy Science