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ARS Home » Midwest Area » Madison, Wisconsin » U.S. Dairy Forage Research Center » Research » Publications at this Location » Publication #198721
Title: EFFECT OF CORN SILAGE MATURITY AND MECHANICAL PROCESSING ON NUTRIENT DIGESTIBILITY BY LACTATING DAIRY COWS OF DIFFERENT LACTATION STAGES

Author
item FERREIRA, GONZALO - UNIV. OF WISCONSIN-MADISO
item Mertens, David

Submitted to: Journal of Dairy Science
Publication Type: Abstract Only
Publication Acceptance Date: 4/11/2006
Publication Date: 7/9/2006
Citation: Ferreira, G., Mertens, D.R. 2006. Effect of corn silage maturity and mechanical processing on nutrient digestibility by lactating dairy cows of different lactation stages [abstract]. Journal of Dairy Science 89 (Supplement 1):262.192

Interpretive Summary:

Technical Abstract: Starch digestibility (StarchD) can decrease when corn silage is harvested at advanced stages of maturity. Processing corn silage through rollers during chopping typically increases StarchD. We hypothesized that corn silage processing increases StarchD in lactating dairy cows to a greater extent when corn silage is harvested at a late (L) than at an early (E) maturity stage. Corn silages were harvested at 34 or 42% DM (E and L, respectively) and with (P) or without (U) kernel processors. Twenty-four cows in mid lactation and 24 cows in late lactation (73±23 and 455±113 DIM, respectively) were used in a replicated 4×4 Latin square design with 28-d periods to determine nutrient digestibility. Diets contained ~70% corn silage (DM basis). Total tract nutrient digestibilities were measured using LaCl3 as an external marker. Maturity and processing affected dry matter digestibility (69.6, 73.6, 68.7, 72.5% for EU, EP, LU and LP, respectively), but the interaction was not significant. Fiber digestibility (NDFD) was greater for cows in late lactation than for cows in mid lactation (48.7 vs. 44.6%, P < 0.01). Maturity and processing affected NDFD (49.6, 51.3, 41.0, 44.7% for EU, EP, LU and LP, respectively), but the interaction was not significant. Lactation stage did not affect StarchD. In agreement with our hypothesis, we observed a significant maturity by processing interaction (P < 0.04) for StarchD (92.7, 98.0, 91.4, 98.5% for EU, EP, LU and LP, respectively), although the difference in StarchD between EU and LU was less than expected. The corn silage fragmentation index (CSFI) for EU and LU corn silages was 41 and 58%, respectively, suggesting that a greater fragmentation of the kernels occurred during harvesting of the LU corn silage. This increased fragmentation may have attenuated the negative effect of maturity on StarchD. We concluded that the increase of StarchD due to processing is greatest when corn silages are harvested at advanced stages of maturity.