K. A. Beauchemin

Crushed sunflower, flax, or canola seeds in lactating dairy cow diets: effects on methane production, rumen fermentation, and milk production.

The objective of this study was to investigate the potential of reducing enteric methane production from dairy cows by incorporating into the diet various sources of long-chain FA varying in their degree of saturation and ruminal availability. The experiment was conducted as a crossover design with 16 lactating dairy cows maintained in 2 groups and fed 4 dietary treatments in four 28-d periods. Eight ruminally cannulated primiparous cows (96 +/- 18 d in milk) were assigned to group 1 and 8 multiparous cows (130 +/- 31 d in milk) were assigned to group 2. The dietary treatments were: 1) a commercial source of calcium salts of long-chain fatty acids (CTL), 2) crushed sunflower seeds (SS), 3) crushed flaxseed (FS), and 4) crushed canola seed (CS). The oilseeds added 3.1 to 4.2% fat to the diet (DM basis). All 3 oilseed treatments decreased methane production (g/d) by an average of 13%. When corrected for differences in dry matter intake (DMI), compared with CTL, methane production (g/kg of DM intake) was decreased by feeding FS (-18%) or CS (-16%) and was only numerically decreased (-10%) by feeding SS. However, compared with the CTL, feeding SS or FS lowered digestible DMI by 16 and 9%, respectively, because of lowered digestibility. Thus, only CS lowered methane per unit of digestible DM intake. Feeding SS and CS decreased rumen protozoal counts, but there were no treatment effects on mean ruminal pH or total volatile fatty acid concentration. Milk efficiency (3.5% fat corrected milk/DMI), milk yield, and component yield and concentrations were not affected by oilseed treatments. The study shows that adding sources of long-chain fatty acids to the diet in the form of processed oilseeds can be an effective means of reducing methane emissions. However, for some oilseeds such as SS or FS, the reduction in methane can be at the expense of diet digestibility. The use of crushed CS offers a means of mitigating methane without negatively affecting diet digestibility, and hence, milk production.

Potential use of Acacia mearnsii condensed tannins to reduce methane emissions and nitrogen excretion from grazing dairy cows

We measured the effect of condensed tannins (CT) extracted from the bark of the Black Wattle tree (Acacia mearnsii) on the milk production, methane emissions, nitrogen (N) balance and energy partitioning of lactating dairy cattle. Sixty lactating cows, approximately 32 d in milk grazing ryegrass pasture supplemented with 5 kg d-1 cracked triticale grain, were allocated to three treatments: Control, Tannin 1 (163 g CT d-1) or Tannin 2 (326 g CT d-1 initially, reduced to 244 g d-1 CT by day 17). Cows were dosed twice daily after milking for 5 wk with the powdered CT extract (mixed 1:1 with water). Low and high CT supplementation reduced (P < 0.05) methane emissions by 14 and 29%, respectively (about 10 and 22% on an estimated dry matter intake basis). However, milk production was also reduced by the CT (P < 0.05), especially at the high dose rate. Milk yields were 33.0, 31.8 and 29.8 kg cow-1 d-1. Tannin 2 also caused a 19% decline in fat yield and a 7% decline in protein yield, but protein and lactose cont...

Repeated Ruminal Acidosis Challenges in Lactating Dairy Cows at High and Low Risk for Developing Acidosis: Feed Sorting

An experiment was conducted to determine whether the susceptibility of cows to ruminal acidosis influences feed sorting and whether feed sorting changes during a bout of ruminal acidosis. Eight ruminally cannulated cows were assigned to 1 of 2 acidosis risk levels: low risk (LR, mid-lactation cows fed a 60% forage diet) or high risk (HR, early lactation cows fed a 45% forage diet). As a result, diets were intentionally confounded with milk production to represent 2 different acidosis risk scenarios. Cows were exposed to an acidosis challenge in each of two 14-d periods. Each period consisted of 3 baseline days, a feed restriction day (restricting TMR to 50% of ad libitum intake), an acidosis challenge day (1-h meal of 4 kg of ground barley/wheat before allocating the TMR), and a recovery phase. Ruminal pH was measured continuously for the first 9 d of each period using an indwelling system. Feed and orts were sampled for 2 baseline days, on the challenge day, and 1 and 3 d after the challenge day for each cow and subjected to particle size analysis. The separator contained 3 screens (18, 9, and 1.18 mm) and a bottom pan to determine the proportion of long, medium, short, and fine particles, respectively. Sorting was calculated as the actual intake of each particle size fraction expressed as a percentage of the predicted intake of that fraction. All cows sorted against the longest and finest TMR particles and sorted for medium-length particles. Sorting was performed to a greater extent by the HR cows, and this sorting was related to low ruminal pH. Both HR and LR cows altered their sorting behavior in response to acidosis challenges. For the HR cows, severe acidosis was associated with increased sorting for the longer particles in the diet and against the shorter particles, likely to lessen the effects of the very.

Feeding saponin-containing Yucca schidigera and Quillaja saponaria to decrease enteric methane production in dairy cows.

An experiment was conducted in vitro to determine whether the addition of saponin-containing Yucca schidigera or Quillaja saponaria reduces methane production without impairing ruminal fermentation or fiber digestion. A slightly lower dose of saponin was then fed to lactating dairy cows to evaluate effects on ruminal fermentation, methane production, total-tract nutrient digestibility, and milk production and composition. A 24-h batch culture in vitro incubation was conducted in a completely randomized design with a control (no additive, CON) and 3 doses of either saponin source [15, 30, and 45 g/kg of substrate dry matter (DM)] using buffered ruminal fluid from 3 dairy cows. The in vivo study was conducted as a crossover design with 2 groups of cows, 3 treatments, and three 28-d periods. Six ruminally cannulated cows were used in group 1 and 6 intact cows in group 2 (627 +/- 55 kg of body weight and 155 +/- 28 d in milk). The treatments were 1) early lactation total mixed ration, no additive (control; CON); 2) CON diet supplemented with whole-plant Y. schidigera powder at 10 g/kg of DM (YS); and 3) CON diet supplemented with whole-plant Q. saponaria powder at 10 g/kg of DM (QS). Methane production was measured in environmental chambers and with the sulfur hexafluoride (SF(6)) tracer technique. In vitro, increasing levels of both saponin sources decreased methane concentration in the headspace and increased the proportion of propionate in the buffered rumen fluid. Concentration of ammonia-N, acetate proportion, and the acetate:propionate ratio in the buffered rumen fluid as well as 24-h digestible neutral detergent fiber were reduced compared with the CON treatment. Medium and high saponin levels decreased DM digestibility compared with the CON treatment. A lower feeding rate of both saponin sources (10 g/kg of DM) was used in vivo in an attempt to avoid potentially negative effects of higher saponin levels on feed digestibility. Feeding saponin did not affect milk production, total-tract nutrient digestibility, rumen fermentation, or methane production. However, DM intake was greater for cows fed YS and QS than for CON cows, with a tendency for greater DM intake for cows fed YS compared with those fed QS. Consequently, efficiency of milk production (kg of milk/kg of DM intake) was lower for cows fed saponin compared with controls. The results show that although saponin from Y. schidigera and Q. saponaria lowered methane production in vitro, the reduction was largely due to reduced ruminal fermentation and feed digestion. Feeding a lower dose of saponin to lactating dairy cows avoided potentially negative effects on ruminal fermentation and feed digestion, but methane production was not reduced. Lower efficiency of milk production of cows fed saponin, and potential reductions in feed digestion at high supplementation rates may make saponin supplements an unattractive option for lowering methane production in vivo.

Effect of dietary forage to concentrate ratio on volatile fatty acid absorption and the expression of genes related to volatile fatty acid absorption and metabolism in ruminal tissue.

The objective of the study was to investigate the fractional rate of volatile fatty acid (VFA) absorption and the expression of genes encoding for transporters and enzymes involved in the absorption and metabolism of VFA in ruminal tissue when cattle were fed high or low concentrate diets. Twelve ruminally cannulated Holstein cows were used in a randomized complete block design. The low concentrate (LC) and high concentrate (HC) diets contained 8 and 64% dietary concentrate (dry matter basis), respectively. Cows were fed their respective diet for at least 28 d, following which data and samples were collected over 6 d. Ruminal pH was measured continuously for 72 h, and the in vivo VFA absorption and passage rates were measured using Co-EDTA and n-valeric acid as markers. Ruminal tissue was collected postslaughter from the ventral sac of the rumen, and gene expression was evaluated using quantitative real-time PCR. Dry matter intake was not affected by treatment, averaging 14.9 kg/d, but cows fed HC had lower mean ruminal pH (6.03 vs. 6.48), and a greater duration (376 vs. 10 min/d) that ruminal pH was <5.8. Ruminal VFA concentration was 24 mM higher for cows fed HC compared with LC; however, the fractional rate of VFA absorption and passage from the rumen was not affected by dietary treatment, averaging 23.4 and 9.6%/h, respectively. The expression of genes encoding for enzymes involved in VFA activation and ketogenesis were not affected by treatment. Cows fed HC tended to have a relative abundance of pyruvate dehydrogenase lipoamide alpha 1 mRNA transcripts that was 1.4 times lower than that of cows fed LC, but other enzymes involved in pyruvate metabolism or regulation of the citric acid cycle were not affected. Collectively, these results suggest that the dietary forage to concentrate ratio does not affect the fractional rate of VFA absorption in vivo, but potentially alters energy metabolism in ruminal tissue.

Repeated ruminal acidosis challenges in lactating dairy cows at high and low risk for developing acidosis: ruminal pH.

The primary objective of this experiment was to determine whether lactating dairy cows that are at high (HR) or low (LR) risk for experiencing ruminal acidosis, because of their diet and stage of lactation, differ in their response to an acidosis challenge. A secondary objective was to determine whether the severity of acidosis changes with repeated challenges. The experiment was a completely randomized design with 2 groups (risk scenarios, HR vs. LR) and 3 periods corresponding to 3 repeated acidosis challenges. Eight lactating ruminally cannulated cows were assigned to 1 of 2 groups: HR, early lactation cows fed a 45% forage diet, or LR, midlactation cows fed a 60% forage diet. Cows were exposed to 3 acidosis challenges, each separated by 14 d. The challenge consisted of restricting total mixed rations to 50% of ad libitum intake for 24 h, followed by a 1-h meal of 4 kg of ground barley-wheat before allocating the total mixed rations. Ruminal pH was measured continuously for 9 of the 14 d each period using an indwelling system. Subacute acidosis (SARA) was described at 2 thresholds: pH <5.8 and pH <5.5. As expected, HR cows had lower ruminal pH profiles (curves) compared with LR cows: mean pH (5.81 vs. 6.21) and nadir pH (5.13 vs. 5.53). The HR cows also experienced SARA to a greater extent than LR cows during the experiment (pH <5.8, 10.6 vs. 3.5 h/d; pH <5.5, 5.9 vs. 1.6 h/d). The pH profiles of cows in both risk categories decreased with each challenge period; mean pH was 6.13, 6.03, 5.77, and nadir pH was 5.52, 5.34, and 5.14 in periods 1, 2, and 3, respectively. The challenges caused a similar decrease in pH for cows in both risk categories, but because the HR cows had a lower baseline pH, they experienced more severe SARA with each subsequent challenge. Feed restriction the day before administering the acidosis challenge caused ruminal pH to gradually increase. On the challenge day, the entire grain allotment was consumed by all cows in period 1, six cows in period 2, and only 3 cows in period 3. The pH plummeted immediately after each grain challenge. Ruminal pH remained very low during the first day after the challenge for all cows, but LR cows began their recovery more quickly than HR cows. Regardless of risk category, with each successive challenge, the pH decrease on the challenge day was more severe: nadir pH on the challenge day was 5.19, 5.07, and 4.90 and duration of SARA (pH <5.8) was 12.2, 13.4, and 15.8 h/d in periods 1, 2, and 3. This study indicates that cows become more prone to acidosis over time even though they decrease intake of the challenge grain to avoid acidosis. The severity of each subsequent bout of acidosis increases, especially for cows fed diets low in physically effective fiber and at high acidosis risk. Therefore, a bout of acidosis that occurs due to improper feed delivery or poor diet formulation can have long-term consequences on cow health and productivity.

Effects of essential oils and their components on in vitro rumen microbial fermentation

The objective of this study was to investigate the effects of essential oils (EO) and essential oil compounds (EOC) on in vitro rumen microbial fermentation. Treatments were: control (no additive), cinnamon leaf oil (400 mg L-1), clove leaf oil (200 mg L-1), sweet orange oil (200 mg L-1), oregano oil (200 mg L-1), thyme oil (200 mg L-1), carvacrol (400 mg L-1), cinnamaldehyde (400 mg L-1), eugenol (800 mg L-1), and thymol (400 mg L-1). Treatments were evaluated using in vitro 24-h batch culture of rumen fluid with a 51:49 forage:concentrate dairy ration [16.7% crude protein (CP), 34.4% neutral detergent fibre (NDF)]. Incubations were conducted in triplicate with gas production (GP) measured at 0, 2, 6, 8, 12, and 24 h, while pH, ammonia (NH3), volatile fatty acid (VFA), in vitro dry matter (IVDMD) and neutral detergent fibre (IVNDFD) digestibilities were determined after 24 h of incubation. Among the EO and EOC evaluated, only the phenolic compounds, carvacrol, thymol, and eugenol affected ruminal ferment...

Cinnamaldehyde in feedlot cattle diets: Intake, growth performance, carcass characteristics, and blood metabolites

Cinnamaldehyde (CIN), a natural chemical compound found in the bark of cinnamon trees, can alter rumen fermentation by inhibiting selected ruminal microbes, and consequently, may improve growth performance and feed efficiency of animals. The objective of this study was to evaluate the effects of supplementing the diet of feedlot cattle with CIN on intake, growth performance, carcass characteristics, and blood metabolites. Seventy yearling steers (BW = 390 +/- 25.2 kg) were assigned to a randomized complete block design with 5 treatments: control (no additive), monensin (MO; 330 mg*steer(-1)*d(-1)), and 400, 800, or 1,600 mg of CIN*steer(-1)*d(-1). At the start of the experiment, steers were blocked according to BW and assigned to 14 blocks of 5 cattle, with cattle within block assigned to treatments. The diets consisted of 9% barley silage, 86% dry-rolled barley grain, and 5% supplement (DM basis). Dry matter intake responded quadratically (P = 0.03) to CIN supplementation with 13% more feed consumed for steers fed CIN (mean of 3 CIN levels) compared with those fed control during the first 28 d of the experiment, and with a tendency of 4% increase over the entire experiment. The ADG (kg/d) tended to respond quadratically (P = 0.08) to CIN supplementation during the first 28 d, but was not affected over the entire experiment (112 d). Feed efficiency (G:F) linearly declined (P = 0.03) during the first 28 d with CIN supplementation and was quadratically affected between d 29 to 56 and d 85 to 112 by CIN dose. Supplementation of MO did not affect (P > 0.15) DMI or growth performance at any time during the experiment. Serum NEFA concentrations were reduced (P = 0.05) by 35, 29, 30, and 22%, respectively, on d 56, 84, 112, and overall with CIN supplementation. Concentrations of serum amyloid A were reduced on d 28 by 56, 60, or 56% for 800 mg of CIN, 1,600 mg of CIN, and MO, respectively, compared with control. Plasma concentrations of lipopolysaccharide binding protein were linearly decreased (P = 0.05) with increasing CIN supplementation on d 28. Results indicate that supplementing a feedlot finishing diet with a small dose of CIN ameliorated feed intake during the initial month but had minimal effects on ADG, feed efficiency, and carcass traits over the entire experiment. Including CIN in the diet of feedlot cattle, particularly early in the feeding period, may help promote intake and reduce the effects of stress.

Reducing GHG emissions through genetic improvement for feed efficiency: effects on economically important traits and enteric methane production

Genetic selection for residual feed intake (RFI) is an indirect approach for reducing enteric methane (CH4) emissions in beef and dairy cattle. RFI is moderately heritable (0.26 to 0.43), moderately repeatable across diets (0.33 to 0.67) and independent of body size and production, and when adjusted for off-test ultrasound backfat thickness (RFIfat) is also independent of body fatness in growing animals. It is highly dependent on accurate measurement of individual animal feed intake. Within-animal repeatability of feed intake is moderate (0.29 to 0.49) with distinctive diurnal patterns associated with cattle type, diet and genotype, necessitating the recording of feed intake for at least 35 days. In addition, direct measurement of enteric CH4 production will likely be more variable and expensive than measuring feed intake and if conducted should be expressed as CH4 production (g/animal per day) adjusted for body size, growth, body composition and dry matter intake (DMI) or as residual CH4 production. A further disadvantage of a direct CH4 phenotype is that the relationships of enteric CH4 production on other economically important traits are largely unknown. Selection for low RFIfat (efficient, −RFIfat) will result in cattle that consume less dry matter (DMI) and have an improved feed conversion ratio (FCR) compared with high RFIfat cattle (inefficient; +RFIfat). Few antagonistic effects have been reported for the relationships of RFIfat on carcass and meat quality, fertility, cow lifetime productivity and adaptability to stress or extensive grazing conditions. Low RFIfat cattle also produce 15% to 25% less enteric CH4 than +RFIfat cattle, since DMI is positively related to enteric methane (CH4) production. In addition, lower DMI and feeding duration and frequency, and a different rumen bacterial profile that improves rumen fermentation in −RFIfat cattle may favor a 1% to 2% improvement in dry matter and CP digestibility compared with +RFIfat cattle. Rate of genetic change using this approach is expected to improve feed efficiency and reduce enteric CH4 emissions from cattle by 0.75% to 1.0% per year at equal levels of body size, growth and body fatness compared with cattle not selected for RFIfat.

Short Communication: Salivary Secretion During Meals in Lactating Dairy Cattle

Four multiparous Holstein cows in midlactation were used in a 4 x 4 Latin square to evaluate whether source of forage influenced salivary secretion during eating in lactating dairy cows. The forages were allocated separately from the pelleted concentrates. Cows were offered 1 of 4 forages each period: barley silage, alfalfa silage, long-stemmed alfalfa hay, or chopped barley straw. Saliva secretion was measured during the morning meal by collecting masticates through the rumen cannula at the cardia of each cow. Rate of salivation (213 g/min) was not affected by forage source. However, the forage sources differed in eating rate (g of DM/min), which led to differences in ensalivation of forages (g of saliva/g of DM and g of saliva/g of NDF). On the basis of DM, ensalivation (g of saliva/g of DM) was greatest for straw (7.23) and similar for barley silage, alfalfa silage, and alfalfa hay (4.15, 3.40, and 4.34 g/g of DM, respectively). Higher ensalivation of straw could be accounted for by its higher neutral detergent fiber (NDF) content; ensalivation of NDF (g of saliva/g of NDF) was actually greatest for long-stemmed alfalfa hay (12.4) and similar for the other chopped forages (8.9). Cows consumed concentrate about 3 to 12 times faster than the various forages (DM basis), and ensalivation of concentrate was much lower (1.12 g of saliva/g of DM) than for forages. Feed characteristics such as particle size, DM, and NDF content affect salivary output during eating by affecting the eating rate. Slower eating rate and greater time spent eating may help prevent ruminal acidosis by increasing the total daily salivary secretion in dairy cows.