Effect of supplemental yeast culture and dietary starch content on rumen fermentation and digestion in dairy cows

Abstract

The objectives of this experiment were to evaluate the effect of feeding a culture of Saccharomyces cerevisiae on rumen metabolism and digestibility when cows are fed diets varying in starch content. Four lactating Holstein cows were assigned to a 4 × 4 Latin square design with a 2 × 2 factorial arrangement of treatments. Treatments were low starch (LS; 23% of diet DM) and no yeast culture (YC; LS-control), LS and 15 g of YC/d (LS-YC), high starch (HS; 29% of diet DM) and no YC (HS-control), and HS and 15 g of YC/d (HS-YC). Periods lasted 28 d, with the last 9 d for data collection. Days 20 to 24 were used to determine production, nutrient flow, and digestibility. On d 25, 3 kg of corn grain DM was placed in the rumen 1 h before the morning feeding, and yields of milk and milk components were measured after the challenge. Blood was sampled -1, 3, 7, and 11 h relative to the morning feeding on d 24 and 25. Rumen pH was measured continuously on d 24 and 25. Rumen papillae were collected on d 24 and 28 to quantify mRNA expression of select genes. Supplementing YC increased yields of milk (26.3 vs. 29.6 kg/d), energy-corrected milk (ECM; 26.5 vs. 30.3 kg/d), fat (0.94 vs. 1.08 kg/d), true protein (0.84 vs. 0.96 kg/d), and ECM/dry matter intake (1.15 vs. 1.30) compared with the control but did not affect dry matter intake (22.6 vs. 22.9 kg/d). Cows fed HS had increased milk true protein percentage (3.18 vs. 3.31%) and yield (0.87 vs. 0.94 kg/d) compared with cows fed LS. Feeding HS-YC increased the proportion of dietary N incorporated into milk true protein from 24.9% in the other 3 treatments to 29.6%. Feeding HS increased the concentration of propionate (21.7 vs. 32.3 mM) and reduced that of NH-N (8.3 vs. 6.7 mg/dL) in rumen fluid compared with the control, and combining HS with YC in HS-YC tended to increase microbial N synthesis compared with LS-YC (275 vs. 322 g/d). Supplementing YC to cows fed HS reduced plasma haptoglobin and rumen lactate concentrations, increased mean rumen pH, reduced the time with pH <6.0, and prevented the decrease in rumen neutral detergent fiber digestion caused by HS. Cows fed HS had less total-tract digestion of organic matter (73.9 vs. 72.4%) because of reduced acid detergent fiber (57.6 vs. 51.7%) and neutral detergent fiber (60.9 vs. 56.7%) digestibility. Production performance after the challenge was similar to that before the challenge, and YC improved yield of ECM. After the challenge, supplementing YC tended to reduce rumen lactate concentration compared with the control and reduced haptoglobin in cows fed HS. Feeding HS but not YC increased expression in rumen papillae of genes for receptors (FFAR2 and FFAR3) and transporter (SLC16A3) of short-chain fatty acids but did not affect genes involved in transport of Na/H or water or in inflammatory response. Supplementing YC to dairy cows improved lactation performance in diets containing low or high starch, and mechanisms might be partially attributed to improvements in rumen pH, digestion of fiber, microbial N synthesis, and reduct...

Screening of live yeast and yeast derivatives for their impact of strain and dose on in vitro ruminal fermentation and microbial profiles with varying media pH levels in high‐forage beef cattle diet

“…In the present study, the linearly decreased A:P ratio with YD4 or YD5 at either pH 5.8 or pH 6.5, indicates that the addition of YD switched rumen fermentation to increased propionate production. The finding of the present study is consistent with the results of a study by Dias et al 3 reporting that the addition of yeast culture decreased the ratio of A:P with high or low starch diet in dairy cows. This is a very interesting finding because the increase of propionate production at the cost of acetate production suggests an improved fermentation efficiency.…”

“…YD are usually defined by their biochemical constituents, such as percentages of mannans, ß ‐glucans or nucleotides. The benefits associated with yeast products in ruminants have been extensively shown to increase dry matter (DM) intake and milk yield, stabilize rumen pH and increase feed digestion . Broadway et al .…”

“…Additionally, supplementation with yeast products could increase the proportion of propionate and decrease the ratio of acetate to propionate (A:P) in the rumen of cattle . There is the evidence for the improvement of milk production and feed efficiency as a result of including yeast products in dairy diets . However, although yeast products have been increasingly used in beef cattle nutrition as feed additives to improve rumen fermentation, animal health and production efficiency, the research on yeast products with respect to improving the performance of beef cattle is still limited.…”

“…The benefits associated with yeast products in ruminants have been extensively shown to increase dry matter (DM) intake and milk yield, stabilize rumen pH and increase feed digestion. [3][4][5] Broadway et al 6 reported on the likelihood of LY releasing polysaccharides such as -D-glucan and -D-glucan that could either interact with immune cells or bind bacteria to prevent the attachment and colonization of pathogens in the gastrointestinal tract, aiming to increase immunity of animals. Therefore, yeast products play a significant role and show great potential with respect to improving performance and productivity in ruminants.…”

“…7 There is the evidence for the improvement of milk production and feed efficiency as a result of including yeast products in dairy diets. 3 However, although yeast products have been increasingly used in beef cattle nutrition as feed additives to improve rumen fermentation, animal health and production efficiency, 5,8,9 the research on yeast products with respect to improving the performance of beef cattle is still limited. To date, the effects of yeast products are inconsistent in the different studies conducted on growing beef cattle, which may be a result of factors such as yeast strains, dosages and diet.…”