Feeding management plays an important role in the particle length needs of the cow. Guidelines for TMR for high producing dairy cows are 2 to 8 percent of the particles in the upper sieve, 30 to 50 percent in the middle sieve, 10 to 20 percent on the 4-mm sieve, and no more than 30 to 40 percent in the bottom pan. Sixty to 70 percent of the TMR should be classified as physically effective, to be multiplied by the NDF content of the diet or forage. Only forage and high fiber byproducts should be classified as effective fiber sources. Further evaluations of this new method to estimate peNDF are continuing.
Guidelines for Particle Size
Achieving adequate ration particle size requires using recommended guidelines for forages and TMR.
Table 1. Corn silage, haylage, and TMR particle size recommendations for lactating cows.
|Screen||Pore Size (inches)||Particle Size (inches)||Corn Silage||Haylage||TMR
|Upper Sieve||0.75||> 0.75||3 to 8||10 to 20||2 to 8|
|Middle Sieve||0.31||0.31 to 0.75||45 to 65||45 to 75||30 to 50|
|Lower Sieve||0.16||0.16 to 0.31||20 to 30||30 to 40||10 to 20|
|Bottom Pan||< 0.16||< 10||< 10||30 to 40|