Inventory of Errors in Feed Composition and Nutrient Intake of Dairy Cows - Influence on Milk Yield and Health on Two Dairies in California

Abstract

Computer models used in ration formulation assume that nutrients supplied by a ration formulation are the same as the nutrients presented in front of the cow in the final ration. Deviations in nutrients due to feed management errors effects such as dry matter changes (i.e. rain), loading, mixing and delivery errors are assumed to not impact delivery of nutrients to the cow and her resulting milk production. To estimate how errors in feed management impact nutrients supplied to the cow, weekly total mixed ration (TMR) samples were collected and analyzed (Analab, Fulton, IL) for 4 and 5 pens (close up cows, fresh cows and 2 high milk producing cows pens) for 7 weeks on two California dairies. Differences among nutrient analyses from these samples and nutrients from the formulated rations were analyzed using Microsoft Excel. Differences among all formulated and supplied nutrients were significantly different among pens and P values were 0.5 for DM %, 0.2 for crude protein %, 0.3 for ADF %, 0.1 for NDF %, 0.04 for starch %, 0.4 for fat %, 0.08 for lignin % and 0.4 for ash %. Therefore feed management practices on all three dairies impacted nutrients supplied to the cow. However, differences among nutrients supplied due to diet changes for a pen were not significant. Therefore feed management impacts nutrient delivery to the cow but most diet adjustments are small relative to differences among pen rations. The largest source of errors in the loading, mixing and delivery process is the human work force due to its presence in every step of the feeding process and its vulnerability to errors.