Fiber Digestibility's Impact on Components

Changes in forages result in pleasant component increases.
Fiber Digestibility's Impact on Components - Articles


Penn State Dairy Cows

January 2014 started off as well as 2013 ended. Except for one small research project, this month was fairly quiet and the entire herd could be maintained on a consistent ration. Two new corn silage structures were opened at the end of the month that presented some opportunities for ration adjustments.

A goal of the dairy management team is to provide a consistent forage source for the researchers. This year we have allocated the upright silo corn silages for the research diets. The bagged 2013 corn silage fed in December was close to being finished. To prepare for the start-up of research projects and transition the herd from the bag, the bunk corn silage was opened for the non-research cows as was one upright silo. The analyses on these silages were very different, Table 1.

Table 1. Corn silage analyses from the bag, upright and bunk.
Item (DM basis)BagUprightBunk
Dry matter, %31.536.136.6
Crude protein, %
NDF, %44.434.542.4
NDF-D, 30 hr., % NDF50.750.651.1
Starch, %
Starch 7-hr. dig, % starch70.477.274.6

The one common theme for the three corn silages analyzed was the low neutral detergent fiber (NDF) digestibilities. Typically our silages test in the high 50's or low 60's, so this year we are dealing with very low fiber digestibility. There is a lot of variability in the starch content and in its digestibility. This provided an opportunity to revise the rations and to monitor the herd response.

The bunk and upright structures were opened the third week of the month. Since the fresh cows were doing well on the bagged corn silage, the decision was made to keep them on the same ration for the rest of the month. The two high groups were started on the bunk corn silage except the forage was raised from 60 to 62.5 percent (total ration dry matter). The pen of 2 year olds and cows housed in the tie-stall barn were put back to a 65% forage ration using a 50/50 split of the upright and bunk corn silages. The grass hay and cottonseed hulls were NOT added back into the diets and the liquid sugar and candy meal were kept at the same inclusion level when the bagged corn silage was fed. Production remained the same but there was a milk fat percent response. Pre- and post- ration change were milk fat 3.74% and 3.87% and milk protein 3.15% and 3.16%, respectively. A total mixed ration sample was tested the last week of the month to compare to the formulated diet. The results are listed in Table 2. For the month of January the herd averaged 86 pounds with a 3.80% milk fat, 3.15% milk protein, 108,000 SCC and 7.5 mg/dl MUN.

Table 2. Total mixed ration results compared to the formulated diet for the last week in January.
Item (DM basis)ActualFormulated
Dry matter, %46.047.0
Crude protein, %14.615.0
NDF, %30.732.0
Starch, %26.224.3

IOFC Results

Month and YearGross Milk Price/cwtMilk income/cowFeed cost/cowIOFCAverage milk lbsLow BenchmarkHigh benchmark

IOFC Graph