Processing, mixing, and particle size reduction of forages for dairy cattle.

Abstract

Adequate forage amounts in both physical and chemical forms are necessary for proper ruminal function in dairy cows. Under conditions in which total amounts of forage or particle size of the forage are reduced, cows spend less time ruminating and have a decreased amount of buoyant digesta in the rumen. These factors reduce saliva production and allow ruminal pH to fall, depressing activity of cellulolytic bacteria and causing a prolonged period of low ruminal pH. Insufficient particle size of the diet decreases the ruminal acetate-to-propionate ratio and reduces ruminal pH. The mean particle size of the diet, the variation in particle size, and the amount of chemical fiber (i.e., NDF or ADF) are all nutritionally important for dairy cows. Defining amounts and physical characteristics of fiber is important in balancing dairy cattle diets. Because particle size plays such an important role in digestion and animal performance, it must be an important consideration from harvest through feeding. Forages should not be reduced in particle size beyond what is necessary to achieve minimal storage losses and what can be accommodated by existing equipment. Forage and total mixed ration (TMR) particle sizes are potentially reduced in size by all phases of harvesting, storing, taking out of storage, mixing, and delivery of feed to the dairy cow. Mixing feed causes a reduction in size of all feed particles and is directly related to TMR mixing time; field studies show that the longest particles (>27 mm) may be reduced in size by 50%. Forage and TMR particle size as fed to the cows should be periodically monitored to maintain adequate nutrition for the dairy cow.

The Effect of Corn Silage Particle Size on Eating Behavior, Chewing Activities, and Rumen Fermentation in Lactating Dairy Cows

“…Effects of feeding corn silage of reduced particle size to lactating dairy cows on consumption of different size particles as described by the Penn State Particle Separator. of over 5000 samples, Heinrichs et al (1999) reported that on average corn silage samples fed on commercial dairy farms contain 8.1 ± 6.4% of the DM greater than 19.0 mm, but variation across herds is large. In the same survey, a minimum of 1% and a maximum of 81% of DM was >19.0 mm.…”

The Effect of Reducing Alfalfa Haylage Particle Size on Cows in Early Lactation

“…Based on a survey composed of over 800 samples, Heinrichs et al (1999) reported that although TMR samples fed on commercial dairy farms typically contain 7% of the particles greater than 19.0 mm variation across herds is large. In the same study, a minimum Figure 1.…”

The Effect of Corn Silage Particle Size and Cottonseed Hulls on Cows in Early Lactation

“…Across treatments peNDF values were not different and averaged 31.6 (Table 4). In a survey evaluating TMR physical form (n = 831 samples), Heinrichs et al (1999) reported that TMR samples fed on commercial dairy farms typically contain 7, 35, and 58% of the material retained on the 19-and 8-mm sieves, respectively. In the same study a minimum of 1.1 and a maximum of 43.1% was observed on the 19-mm sieve, while a minimum of 2.4 and a maximum of 69.1% was retained on the 8-mm sieve.…”