Increasing the concentration of linolenic acid in diets fed to Jersey cows in late lactation does not affect methane production

Authors: JUDY, J - University Of Nebraska; BACHMAN, G - University Of Nebraska; Brown-Brandl, Tami; FERNANDO, S - University Of Nebraska; Hales Paxton, Kristin; HARVATINE, K - Pennsylvania State University; MILLER, P - University Of Nebraska; KONONOFF, P - University Of Nebraska

Submitted to: Journal of Dairy Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/20/2018
Publication Date: 3/1/2019
Citation: Judy, J.V., Bachman, G.C., Brown-Brandl, T.M., Fernando, S.C., Hales, K.E., Harvatine, K.J., Miller, P.S., Kononoff, P.J. 2019. Increasing the concentration of linolenic acid in diets fed to Jersey cows in late lactation does not affect methane production. Journal of Dairy Science. 102(3):2085-2093. https://doi.org/10.3168/jds.2018-14608.
DOI: https://doi.org/10.3168/jds.2018-14608

Interpretive Summary: Although the inclusion of fat has reduced methane production in ruminants, relatively little research has been conducted on comparing the source and profile of fatty acids on methane production in lactating dairy cows. A study using 8 lactating Jersey cows was conducted to determine effects of feeding a canola/tallow combination vs. extruded byproduct containing flaxseed as a fat source on methane production and diet digestibility in late lactation dairy cows. Diets contained approximately 50 % forage mixture of corn silage, alfalfa hay, and brome hay with only the concentrate mixture changing between diets to include either 1) a canola/tallow combination (CON), or 2) a corn/soybean meal diet with an extruded byproduct containing flaxseed as the fat source. Diets were balanced to decrease corn and canola meal and replace them with flaxseed to increase linolenic acid supply to the rumen. Milk production and dry matter intake were not different across treatments. Milk fat and protein were not affected by treatment. For methane production, no difference was observed for total methane production Heat production was not different across treatment. Furthermore, digestibility of fiber, protein, dry matter, organic matter, and starch were not affected by diet treatment. Results indicate that increasing linoleic acid supply may not affect methane production or digestibility of the diet in lactating dairy cows.

Technical Abstract: Although the inclusion of fat has reduced methane production in ruminants, relatively little research has been conducted comparing the effects of source and profile of fatty acids on methane production in lactating dairy cows. A study using 8 multiparous (325 ± 17 DIM; mean ± SD) lactating Jersey cows was conducted to determine effects of feeding canola meal and lard versus extruded byproduct containing flaxseed as a high-C18:3 fat source on methane production and diet digestibility in late-lactation dairy cows. A crossover design with 32-d periods (28-d adaptation and 4-d collections) was used to compare 2 different fat sources. Diets contained approximately 50% forage mixture of corn silage, alfalfa hay, and brome hay; the concentrate mixture changed between diets to include either (1) a conventional diet of corn, soybean meal, and canola meal with lard (control) or (2) a conventional diet of corn and soybean meal with an extruded byproduct containing flaxseed (EXF) as the fat source. Diets were balanced to decrease corn, lard, and canola meal and replace them with soybean mean and EXF to increase the concentration of C18:3 (0.14 vs. 1.20% of DM). Methane production was measured using headbox-style indirect calorimeters. Cattle were restricted to 95% ad libitum feed intake during collections. Milk production (17.4 ± 1.04 kg/d) and dry matter intake (15.4 ± 0.71 kg/d) were similar among treatments. Milk fat (5.88 ± 0.25%) and protein (4.08 ± 0.14%) were not affected by treatment. For methane production, no difference was observed for total production (352.0 vs. 349.8 ± 16.43 L/d for control vs. EXF, respectively). Methane production per unit of dry matter intake was not affected and averaged 23.1 ± 0.57 L/kg. Similarly, methane methane production per unit of energy-corrected milk was not affected by fat source and averaged 15.5 ± 0.68 L/kg. Heat production was similar, averaging 21.1 ± 1.02 Mcal/d. Digestibility of organic matter, neutral detergent fiber, and crude protein was not affected by diet and averaged 69.9, 53.6, and 73.3%, respectively. Results indicated that increasing C18:3 may not affect methane production or digestibility of the diet in lactating dairy cows.