Details

Autor(en) / Beteiligte

• Meller, R.A.
• Wenner, B.A.
• Ashworth, J.
• Gehman, A.M.
• Lakritz, J.
• Firkins, J.L.

Titel

Potential roles of nitrate and live yeast culture in suppressing methane emission and influencing ruminal fermentation, digestibility, and milk production in lactating Jersey cows

Ist Teil von

• Journal of dairy science, 2019-07, Vol.102 (7), p.6144-6156

Ort / Verlag

United States: Elsevier Inc

Erscheinungsjahr

2019

Quelle

Elsevier ScienceDirect Journals Complete

Beschreibungen/Notizen

• Concern over the carbon footprint of the dairy industry has led to various dietary approaches to mitigate enteric CH4 production. One approach is feeding the electron acceptor NO3−, thus outcompeting methanogens for aqueous H2. We hypothesized that a live yeast culture (LYC; Saccharomyces cerevisiae from Yea-Sacc 1026, Alltech Inc., Nicholasville, KY) would stimulate the complete reduction of NO3− to NH3 by selenomonads, thus decreasing the quantity of CH4 emissions per unit of energy-corrected milk production while decreasing blood methemoglobin concentration resulting from the absorbed intermediate, NO2−. Twelve lactating Jersey cows (8 multiparous and noncannulated; 4 primiparous and ruminally cannulated) were used in a replicated 4 × 4 Latin square design with a 2 × 2 factorial arrangement of treatments. Cattle were fed diets containing 1.5% NO3− (from calcium ammonium nitrate) or an isonitrogenous control diet (containing additional urea) and given a top-dress of ground corn without or with LYC, with the fourth week used for data collection. Noncannulated cows were spot measured for CH4 emission by mouth using GreenFeed (C-Lock Inc., Rapid City, SD). The main effect of NO3− decreased CH4 by 17% but decreased dry matter intake by 10% (from 19.8 to 17.8 kg/d) such that CH4:dry matter intake numerically decreased by 8% and CH4:milk net energy for lactation production was unaffected by treatment. Milk and milk fat production were not affected, but NO3− decreased milk protein from 758 to 689 g/d. Ruminal pH decreased more sharply after feeding for cows fed diets without NO3−. Acetate:propionate was greater for cows fed NO3−, particularly when combined with LYC (interaction effect). Blood methemoglobin was higher for cattle fed NO3− than for those fed the control diet but was low for both treatments (1.5 vs. 0.5%, respectively; only one measurement exceeded 5%), indicating minimal risk for NO2− accumulation at our feeding level of NO3−. Although neither apparent organic matter nor neutral detergent fiber digestibilities were affected, apparent N digestibility had an interaction for NO3− × LYC such that apparent N digestibility was numerically lowest for diets containing both NO3− and LYC compared with the other 3 diets. Under the conditions of this study, NO3− mitigated ruminal methanogenesis but also depressed dry matter intake and milk protein yield. Based on the fact that few interactions were detected, LYC had a minimal role in attenuating negative cow responses to NO3− supplementation.