Effect of camelina oil or live yeasts (Saccharomyces cerevisiae) on ruminal methane production, rumen fermentation, and milk fatty acid composition in lactating cows fed grass silage diets.

The potential of dietary supplements of 2 live yeast strains (Saccharomyces cerevisiae) or camelina oil to lower ruminal methane (CH4) and carbon dioxide (CO2) production and the associated effects on animal performance, rumen fermentation, rumen microbial populations, nutrient metabolism, and milk fatty acid (FA) composition of cows fed grass silage-based diets were examined. Four Finnish Ayrshire cows (53±7 d in milk) fitted with rumen cannula were used in a 4×4 Latin square with four 42-d periods. Cows received a basal total mixed ration (control treatment) with a 50:50 forage-to-concentrate ratio [on a dry matter (DM) basis] containing grass silage, the same basal total mixed ration supplemented with 1 of 2 live yeasts, A or B, administered directly in the rumen at 10(10) cfu/d (treatments A and B), or supplements of 60g of camelina oil/kg of diet DM that replaced concentrate ingredients in the basal total mixed ration (treatment CO). Relative to the control, treatments A and B had no effects on DM intake, rumen fermentation, ruminal gas production, or apparent total-tract nutrient digestibility. In contrast, treatment CO lowered DM intake and ruminal CH4 and CO2 production, responses associated with numerical nonsignificant decreases in total-tract organic matter digestibility, but no alterations in rumen fermentation characteristics or changes in the total numbers of rumen bacteria, methanogens, protozoa, and fungi. Compared with the control, treatment CO decreased the yields of milk, milk fat, lactose, and protein. Relative to treatment B, treatment CO improved nitrogen utilization due to a lower crude protein intake. Treatment A had no influence on milk FA composition, whereas treatment B increased cis-9 10:1 and decreased 11-cyclohexyl 11:0 and 24:0 concentrations. Treatment CO decreased milk fat 8:0 to 16:0 and total saturated FA, and increased 18:0, 18:1, 18:2, conjugated linoleic acid, 18:3n-3, and trans FA concentrations. Decreases in ruminal CH4 production to treatment CO were related, at least in part to lowered DM intake, whereas treatments had no effect on ruminal CH4 emission intensity (g/kg of digestible organic matter intake or milk yield). Results indicated that live yeasts A and B had no influence on animal performance, ruminal gas production, rumen fermentation, or nutrient utilization in cows fed grass silage-based diets. Dietary supplements of camelina oil decreased ruminal CH4 and CO2 production, but also lowered the yields of milk and milk constituents due to an adverse effect on intake.

Bayat AR ，Kairenius P ，Stefański T ，Leskinen H ，Comtet-Marre S ，Forano E ，Chaucheyras-Durand F ，Shingfield KJ ... -  《-》

Plant oil supplements reduce methane emissions and improve milk fatty acid composition in dairy cows fed grass silage-based diets without affecting milk yield.

Four lipid supplements varying in chain length or degree of unsaturation were examined for their effects on milk yield and composition, ruminal CH4 emissions, rumen fermentation, nutrient utilization, and microbial ecology in lactating dairy cows. Five Nordic Red cows fitted with rumen cannulas were used in a 5 × 5 Latin square with five 28-d periods. Treatments comprised total mixed rations based on grass silage with a forage-to-concentrate ratio of 60:40 supplemented with no lipid (CO) or 50 g/kg of diet dry matter (DM) of myristic acid (MA), rapeseed oil (RO), safflower oil (SO), or linseed oil (LO). Feeding MA resulted in the lowest DM intake, and feeding RO reduced DM intake compared with CO. Feeding MA reduced the yields of milk, milk constituents, and energy-corrected milk. Plant oils did not influence yields of milk and milk constituents, but reduced milk protein content compared with CO. Treatments had no effect on rumen fermentation characteristics, other than an increase in ammonia-N concentration due to feeding MA, RO, and SO compared with CO. Lipid supplements reduced daily ruminal CH4 emission; however, the response was to some extent a result of lower feed intake. Lipids modified microbial community structure without affecting total counts of bacteria, archaea, and ciliate protozoa. Dietary treatments had no effect on the apparent total tract digestibility of organic matter, fiber, and gross energy. Treatments did not affect either energy secreted in milk as a proportion of energy intake or efficiency of dietary N utilization. All lipids lowered de novo fatty acid synthesis in the mammary gland. Plant oils increased proportions of milk fat 18:0, cis 18:1, trans and monounsaturated fatty acids, and decreased saturated fatty acids compared with CO and MA. Both SO and LO increased the proportion of total polyunsaturated fatty acids, total conjugated linolenic acid, and cis-9,trans-11 conjugated linoleic acid. Feeding MA clearly increased the Δ9 desaturation of fatty acids. Our results provide compelling evidence that plant oils supplemented to a grass silage-based diet reduce ruminal CH4 emission and milk saturated fatty acids, and increase the proportion of unsaturated fatty acids and total conjugated linoleic acid while not interfering with digestibility, rumen fermentation, rumen microbial quantities, or milk production.

Bayat AR ，Tapio I ，Vilkki J ，Shingfield KJ ，Leskinen H ... -  《-》

Linseed oil and DGAT1 K232A polymorphism: Effects on methane emission, energy and nitrogen metabolism, lactation performance, ruminal fermentation, and rumen microbial composition of Holstein-Friesian cows.

Complex interactions between rumen microbiota, cow genetics, and diet composition may exist. Therefore, the effect of linseed oil, DGAT1 K232A polymorphism (DGAT1), and the interaction between linseed oil and DGAT1 on CH4 and H2 emission, energy and N metabolism, lactation performance, ruminal fermentation, and rumen bacterial and archaeal composition was investigated. Twenty-four lactating Holstein-Friesian cows (i.e., 12 with DGAT1 KK genotype and 12 with DGAT1 AA genotype) were fed 2 diets in a crossover design: a control diet and a linseed oil diet (LSO) with a difference of 22 g/kg of dry matter (DM) in fat content between the 2 diets. Both diets consisted of 40% corn silage, 30% grass silage, and 30% concentrates (DM basis). Apparent digestibility, lactation performance, N and energy balance, and CH4 emission were measured in climate respiration chambers, and rumen fluid samples were collected using the oral stomach tube technique. No linseed oil by DGAT1 interactions were observed for digestibility, milk production and composition, energy and N balance, CH4 and H2 emissions, and rumen volatile fatty acid concentrations. The DGAT1 KK genotype was associated with a lower proportion of polyunsaturated fatty acids in milk fat, and with a higher milk fat and protein content, and proportion of saturated fatty acids in milk fat compared with the DGAT1 AA genotype, whereas the fat- and protein-corrected milk yield was unaffected by DGAT1. Also, DGAT1 did not affect nutrient digestibility, CH4 or H2 emission, ruminal fermentation or ruminal archaeal and bacterial concentrations. Rumen bacterial and archaeal composition was also unaffected in terms of the whole community, whereas at the genus level the relative abundances of some bacterial genera were found to be affected by DGAT1. The DGAT1 KK genotype was associated with a lower metabolizability (i.e., ratio of metabolizable to gross energy intake), and with a tendency for a lower milk N efficiency compared with the DGAT1 AA genotype. The LSO diet tended to decrease CH4 production (g/d) by 8%, and significantly decreased CH4 yield (g/kg of DM intake) by 6% and CH4 intensity (g/kg of fat- and protein-corrected milk) by 11%, but did not affect H2 emission. The LSO diet also decreased ruminal acetate molar proportion, the acetate to propionate ratio, and the archaea to bacteria ratio, whereas ruminal propionate molar proportion and milk N efficiency increased. Ruminal bacterial and archaeal composition tended to be affected by diet in terms of the whole community, with several bacterial genera found to be significantly affected by diet. These results indicate that DGAT1 does not affect enteric CH4 emission and production pathways, but that it does affect traits other than lactation characteristics, including metabolizability, N efficiency, and the relative abundance of Bifidobacterium. Additionally, linseed oil reduces CH4 emission independent of DGAT1 and affects the rumen microbiota and its fermentative activity.

van Gastelen S ，Visker MHPW ，Edwards JE ，Antunes-Fernandes EC ，Hettinga KA ，Alferink SJJ ，Hendriks WH ，Bovenhuis H ，Smidt H ，Dijkstra J ... -  《-》

Effects of carbohydrate type or bicarbonate addition to grass silage-based diets on enteric methane emissions and milk fatty acid composition in dairy cows.

The aim of the study was to compare the effect of fiber- or starch-rich diets based on grass silage, supplemented or not with bicarbonate, on CH4 emissions and milk fatty acid (FA) profile in dairy cows. The experiment was conducted as a 4 × 4 Latin square design with a 2 × 2 factorial arrangement: carbohydrate type [starch- or fiber-rich diets with dietary starch level of 23.1 and 5.9% on a dry matter basis, respectively], without or with bicarbonate addition [0 and 1% of the dry matter intake, respectively]. Four multiparous lactating Holstein cows were fed 4 diets with 42% grass silage, 8% hay, and 50% concentrate in 4 consecutive 4-wk periods: (1) starch-rich diet, (2) starch-rich diet with bicarbonate, (3) fiber-rich diet, and (4) fiber-rich diet with bicarbonate. Intake and milk production were measured daily and milk composition was measured weekly; CH4 emission and total-tract digestibility were measured simultaneously (5 d, wk 4) when animals were in open-circuit respiration chambers. Sensors continuously monitored rumen pH (3 d, wk 4), and fermentation parameters were analyzed from rumen fluid samples taken before feeding (1 d, wk 3). Cows fed starch-rich diets had less CH4 emissions (on average, -18% in g/d; -15% in g/kg of dry matter intake; -19% in g/kg of milk) compared with fiber-rich diets. Carbohydrate type did not affect digestion of nutrients, except starch, which increased with starch-rich diets. The decrease in rumen protozoa number (-36%) and the shift in rumen fermentation toward propionate at the expense of butyrate for cows fed the starch-rich diets may be the main factor in reducing CH4 emissions. Milk of cows fed starch-rich diets had lower concentrations in trans-11 C18:1, sum of cis-C18, cis-9,trans-11 conjugated linoleic acid (CLA), and sum of CLA, along with greater concentration of some minor isomers of CLA and saturated FA in comparison to the fiber-rich diet. Bicarbonate addition did not influence CH4 emissions or nutrient digestibility regardless of the carbohydrate type in the diet. Rumen pH increased with bicarbonate addition, whereas other rumen parameters and milk FA composition were almost comparable between diets. Feeding dairy cows a starch-rich diet based on grass silage helps to limit the negative environmental effect of ruminants, but does not lead to greater milk nutritional value because milk saturated FA content is increased.

Bougouin A ，Ferlay A ，Doreau M ，Martin C ... -  《-》

Effects of essential oils on digestion, ruminal fermentation, rumen microbial populations, milk production, and milk composition in dairy cows fed alfalfa silage or corn silage.

Benchaar C ，Petit HV ，Berthiaume R ，Ouellet DR ，Chiquette J ，Chouinard PY ... -  《-》