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Factors affecting 7 hour starch digestibility on conventional corn silage, BMR corn silage, and high moisture corn grain
Previous research has shown that there appears to be a relationship between time after ensiling and starch digestibility in lactating dairy cows. The objective of this study was to measure how time after ensiling and other factors affect 7 hour starch digestibility in conventional corn silage, BMR corn silage, and high moisture corn grain. Samples were taken monthly on 16 farms in New York and Vermont from November of 2010 to October 2011. All samples were sent to Cumberland Valley Analytical Services to have 7 hour starch digestibility and dry matter analysis determined on all samples. Linear analysis was performed on samples grouped by physical characteristics (Conventional vs. BMR vs. High Moisture Corn) comparing impact of time after ensiling and other factors on the 7 hour starch digestibility of the starch in the feedstuffs. The analysis of the conventional corn silage demonstrated that time after ensiling has the largest impact on 7 hour starch digestibility (P = 0.0007) however dry matter and farm that sample was taken from also has an impact. When time after ensiling, dry matter, and farm name was accounted for analysis showed a linear realtionship (R2 = 0.17; P = 0.11). For the bmr corn silage there appeared to be a strong relationship for time after ensiling on 7 hour starch digestibility (P > 0.99) however when dry matter and farm were applied to the data there was a linear relationship (R2 = 0.54; P = 0.01). It appears that the farm the sample came from had the biggest impact on the 7 hour starch digestibility of the BMR corn silage (P = 0.04). On the high moisture corn grain again there was a time after ensiling effect with a good relationship with 7 hour starch digestibility (P < 0.01). Dry matter and farm also have a linear relationship (R2 = 0.47; P = 0.01). In conclusion time after ensiling has a significant impact on 7 hour starch digestibility of both the conventional corn silage and high moisture corn grain; it does not have a significant impact on BMR corn silage. The variation that was accounted for by the farm that the samples came from indicates that other factors such as soil type, corn hybrid, amount of processing, and other farm factors can have an impact on 7 hour starch digestibility.
Keywords:
Starch Digestibility
Time After Ensiling
Corn Silage