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United States Department of Agriculture

Agricultural Research Service

Research Project: Forage Characteristics that Alter Feed Utilization, Manure Characteristics and Environmental Impacts of Dairy Production

Location: Dairy Forage Research

Project Number: 5090-31000-023-00-D
Project Type: In-House Appropriated

Start Date: Nov 1, 2012
End Date: Oct 31, 2017

Objective 1: Determine the effects of dietary crude protein and forage type on feed utilization by dairy cows and heifers, in-barn methane and ammonia emissions, the production and chemistry of manure, and the impacts of these outcomes on manure nutrient availability in soils. • Sub-objective 1.A. Determine the primary dietary sources of ammonia (NH3), nitrate (NO3) and nitrous oxide (N2O) losses from urine and feces produced by lactating cows fed a typical ration of alfalfa silage, corn silage, corn grain and roasted soybeans. • Sub-objective 1.B. Evaluate the effects of forage types and supplementation on lactating cow urine and feces composition and subsequent losses of N in-barn and after application to soil. • Sub-objective 1.C. Determine impacts of limit feeding and monensin on NH3, NO2, CO2, methane (CH4) emissions from replacement dairy heifers. • Sub-objective 1.D. Evaluate diet options for gravid dairy replacement heifers raised in confinement. • Sub-objective 1.E. Evaluate grazing systems for raising replacement heifers. Objective 2: Characterize polyphenol-containing plant extracts and determine how they can be used to alter dairy cattle nitrogen efficiency, reduce in-barn emissions of ammonia and greenhouse gases and modify manure nitrogen availability in the soil. • Sub-objective 2.A. Identify tannin fractions that are most effective for shifting the digestion of plant protein from the rumen to the gastrointestinal tract and for ammonia abatement in manure. • Sub-objective 2.B. Determine dietary tannin impacts on NH3 and CH4 emissions from dairy barns. • Sub-objective 2.C. Evaluate the effects of adding tannin extracts directly to free-stall barn floors on NH3 and CH4 emissions. • Sub-objective 2.D. Determine the impacts of dietary tannins on manure chemistry and soil C sequestration, soil N mineralization, crop N uptake and crop yield after application of manure to soil. Objective 3: Determine how silage feed additives alter rumen fermentation and feed utilization in dairy cattle. Objective 4: Develop techniques and technologies to better estimate the digestion and physical function of forages and other feedstuffs in the rumen and overall utilization by the cow. • Sub-objective 4.A. Evaluate the effects of forage quality on energy intake, partitioning and feed conversion efficiency. • Sub-objective 4.B. Develop a functional characterization of forage fiber, accounting for physical form, fragility and digestion characteristics. • Sub-objective 4.C. Evaluate the physiological effects of metabolic fuels on energy intake and partitioning.

Objective 1. Alfalfa silage, corn silage, corn grain and roasted soybeans will be 15N (Nitrogen) enriched in the field and fed separately as part of a standard ration. Urine and feces will be collected from lactating cows on these rations and used in laboratory studies to estimate ammonia emissions from barn floors and soil N transformations after manure application as influenced by each feed. Urine and feces will be collected from various lactating cow trials having treatments of different forage types and supplementation strategies to understand their effects on ammonia emission from the manure and subsequent soil N transformations after manure application. The effects of limit feeding and monensin on ammonia and greenhouse gas emissions from replacement dairy heifers will be studied in emission chambers. Feeding options for raising dairy replacement heifers in confinement and grazing settings will also be evaluated. Objective 2. The ruminal-gastrointestinal digestibility of alfalfa proteins treated with chemically defined condensed and hydrolysable tannin fractions will be determined by in vitro incubation followed by enzymatic hydrolysis. Fractions from a commercial quebracho-chestnut tannin extract responsible for urease inhibition in dairy feces will be identified. Tannin extracts will be fed to lactating dairy cows at 0 to 3% of dietary dry matter, and effects on in-barn emissions of ammonia and methane will be measured. Feces collected from this experiment will be applied to soil to measure effects on soil C (carbon) and N cycles. Adding tannin extracts to free-stall barn floors will be studied as a means of reducing in-barn ammonia and methane emissions. Objective 3. In vitro analyses of untreated, inoculated and formic acid-treated silages will be performed to understand how a Lactobacillus plantarum silage inoculant can affect rumen microbial growth. Various silage extracts will be made and added to in vitro ruminal fermentations. Inoculated silage extracts that appear to contain the factors affecting ruminal microbial growth will be compared to extracts from untreated silages using a metabolomics approach to identify chemical differences. Objective 4. A series of lactating cow trials will be performed to examine the effects of forage quality on energy intake, partitioning and feed conversion efficiency. Functional relationships between physical form, fragility and digestion characteristics of forage fiber will be developed and tested in ruminally fistulated cows. Differences in the mix of energy sources in lactating cow rations on intake and partitioning at different stages of lactation will also be measured.

Last Modified: 8/25/2016
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