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

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 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.

Factors that affect heat production in lactating Jersey cows

“…Data from 9 research experiments conducted at the University of Nebraska-Lincoln's Dairy Metabolism Unit were used (Foth et al, 2015;Drehmel et al, 2018;Judy et al, 2018Judy et al, , 2019aKnoell et al, 2019;Reynolds et al, 2019;Morris et al, 2020a,b). Across these 9 experiments, data from 293 animal-periods were collected on 54 Jersey cows.…”

“…Cows were fed within the headboxes and allowed free access to water via a water bowl. Details for the specific methods used to quantify gas consumption and production can be found in individual publications (Foth et al, 2015;Drehmel et al, 2018;Judy et al, 2018Judy et al, , 2019aKnoell et al, 2019;Reynolds et al, 2019;Morris et al, 2020a,b). Heat production was estimated through calculation of observed O 2 consumption and CO 2 production with correction for CH 4 production and urinary N excretion according to Brouwer (1965) as follows:…”

“…for Foth et al (2015) and Reynolds et al (2019), where analyses were completed at the Ruminant Nutrition Laboratory of the University of Nebraska-Lincoln. Methods were similar across location and are described in individual publications (Foth et al, 2015;Drehmel et al, 2018;Judy et al, 2018Judy et al, , 2019aKnoell et al, 2019;Reynolds et al, 2019;Morris et al, 2020a,b). Crossover experimental designs were used in all 9 experiments.…”

Methane Emissions and Milk Fatty Acid Profiles in Dairy Cows Fed Linseed, Measured at the Group Level in a Naturally Ventilated Housing and Individually in Respiration Chambers

“…In this context, supplementing the diet with >50 g of linseed lipids per kg feed dry matter (DM) particularly decreased CH 4 emission, but diet digestibility was concomitantly impaired [5,6]. At supplementation levels of ≤20 g linseed lipids per kg feed DM, there was no reduction in the CH 4 emissions [7][8][9]. Thus, supplementing feed with moderate levels ranging from 26-36 g linseed lipids kg −1 feed DM appears to be the most promising approach to achieve a clear CH 4 reduction with marginal effects on digestion and intake [6,10,11].…”

Reduction of Enteric Methane Emissions in Heifers Fed Tropical Grass-Based Rations Supplemented with Palm Oil

“…Recent work has reported reductions from 7.2 to 21.4% [9,[12][13][14][15] when 20 to 60 g/kg of lipids were included in the rations of dairy cows and beef cattle. The mechanisms for the suppression of methanogenesis consist of replacing rumen fermentable organic matter in the diet, decreasing the numbers of ruminal methanogens and protozoa, and the biohydrogenation of unsaturated fatty acids [16].…”