Effects of Chop Length of Alfalfa and Corn Silage on Milk Production and Rumen Fermentation of Dairy Cows

Abstract

Effects of chop length (shorter = 10 mm or longer = 19 mm) of alfalfa silage and corn silage were determined in 16 midlactation Holstein cows using a 4 x 4 Latin square design with a 2 x 2 arrangement of treatments. Experimental periods were 21 d long and consisted of 14 d of adaptation and 7 d of sampling. Cows received total mixed ration containing (dry matter basis) 44.0% barley grain-based energy supplement, 12.6% protein supplement, and 21.7% longer chop or shorter chop alfalfa silage and 21.7% longer chop or shorter chop corn silage. Reducing the chop length of alfalfa silage and corn silage reduced the average geometric particle length from 14.4 to 11.0 mm and from 14.2 to 10.4 mm, respectively. Reducing the chop length of both silages reduced the proportion of the diets retained by the 8- and 19-mm screen of the Penn State Particle Separator from 55.0 to 46.0% of dry matter. Reducing the alfalfa chop length increased total rumen volatile fatty acids at 4 to 5 h after feeding but did not affect rumen pH at 4 to 5 h after feeding, feed intake, and milk production. Reducing the corn silage chop length increased dry matter intake from 22.3 to 23.2 kg/d, increased rumen pH at 4 to 5 h after feeding from 6.12 to 6.20, but did not alter rumen volatile fatty acids at 4 to 5 h after feeding or milk production. Daily milk yield, milk fat percentage, and milk protein percentage averaged 38.2 kg/d, 2.62%, and 3.29%, respectively, across all diets. The low milk fat percentages suggest that all diets induced subacute ruminal acidosis (SARA), whereas the rumen pH did not indicate SARA. This discrepancy could be due to a difference in the time of rumen pH measurement and the time of the lowest rumen pH. Hence, the pH data need to be interpreted with caution. Diets could have induced SARA, because for all experimental diets the content of forage neutral detergent fiber was lower than recommended for barley grain-based diets.

Correlation between Composition of the Bacterial Community and Concentration of Volatile Fatty Acids in the Rumen during the Transition Period and Ketosis in Dairy Cows

“…Rumen contents were filtered through four layers of sterile cheesecloth, transferred to 50-ml sterile tubes, frozen immediately in liquid nitrogen, and stored at Ϫ20°C until analysis. Concentrations of VFAs (acetate, propionate, and butyrate) were determined by gas chromatography as described by Bhandari et al (5). Blood samples were collected by coccygeal venipuncture.…”

Effects of hydrolyzed and live yeasts on rumen microbial fermentation in a semicontinuous culture system (Rusitec)

“…VFAs were quantified by the method of Oeztuerk et al (7) using HPLC (Shimadzu LC-20AT, Japan) with a Rezex ROA-organic acid column (7.8 × 300 mm) at 60 °C, isocratic elution with 0.005 M H 2 SO 4 , and UV detection at 210 nm. NH 3 -N concentration was determined using a colorimetric technique as described by Bhandari et al (8). Digestibility of dry matter was detected by drying at 65 °C for 48 h. It was calculated as original dry matter sample weight minus dry matter residue weight divided by the original sample weight.…”

Effects of dry period management and parity on rumen fermentation, blood metabolites, and liver triacylglyceride in dairy cows

“…Subsequently, rumen fluid was transferred into two 15-mL tubes and stored at Á208C for analysis of volatile fatty acids (VFA), lactate and ammonia nitrogen. The analysis of VFA was conducted by gas chromatography (model 3900 Star, Varian, Walnut Creek, CA) as described by Bhandari et al (2007). Briefly, after the samples were thawed at room temperature, 3 mL of subsample was transferred into test tubes and mixed thoroughly with 0.6 mL of 25% metaphosphoric acid.…”