Particle Size Influences Preferential Consumption of Hay and Baleage in Total Mixed Dairy Rations

Lactating cows require complete balanced rations to meet their high nutritional requirements and to maximize milk and milk fat production. Total mixed rations (TMR) were developed to meet these nutritional needs by thoroughly mixing necessary feedstuffs into a single ration; hence providing a balanced diet in each bite. However, the actual nutrient and fiber concentration consumed by cows can dramatically differ from that of the ration due to selective feeding. The objectives of this study were to 1) evaluate the palatability of alfalfa hay TMR and alfalfa baleage TMR and 2) determine the effect of TMR fiber sources on the preferential sorting of rations. Sixty-four lactating dairy cows at the R.T. Wright University Farm at Northwest Missouri State University, Maryville, Missouri, were fed TMR containing either 35 percent alfalfa baleage or 35 percent alfalfa hay. Fresh TMR was weighed and distributed evenly within the feed bunk every 24 hours and orts (unconsumed feedstuffs) were collected and weighed to determine the amount of feed consumed. Feed samples from the bulk ration and arts mixture were collected for analysis of particle size distribution via a Penn State Particle Separator. Results indicate the cows clearly preferred shorter (< 0.79 cm) feed particles in both the baleage TMR and hay TMR. In addition, the cows preferred and consumed more alfalfa baleage TMR than alfalfa hay TMR. No relationships between moisture content and TMR preference were identified.