Impact of hard vs. soft wheat and monensin level on rumen acidosis in feedlot heifers

Effect of red osier dogwood extract on in vitro gas production, dry matter digestibility, and fermentation characteristics of forage-based diet or grain-based diet

This in vitro batch culture study investigated the effects of red osier dogwood (ROD) extract supplementation on gas production (GP), dry matter disappearance (DMD), and fermentation characteristics in high forage (HF) and high grain (HG) diets with varying media pH level. The experiment was a factorial arrangement of treatments in a completely randomized design with 2 media pH (5.8 and 6.5) × 4 dose rates of ROD extract (0, 1, 3, and 5% of DM substrate). An additional treatment of monensin was added as a positive control for each pH level. The HF substrate consisted of 400 and 600 g/kg DM barley-based concentrate and barley silage, respectively, while the HG substrate contained 100 and 900 g/kg DM barley silage and barley-based concentrate, respectively. Treatments were incubated for 24 h with GP, DMD and fermentation parameters determined. No interaction was detected between the media pH level and ROD extract dose rate on GP, DMD and most of the fermentation parameters. The GP, DMD, and total volatile fatty acid (VFA) concentration were greater (P = 0.01) with media pH of 6.5 in both HF and HG diets. The GP were not affected by increasing ROD dose rate, except that GP linearly decreased in the HF (P = 0.04) and HG (P = 0.01) diets at 24 h; the DMD tended to linearly decrease at pH 6.5 (P = 0.06) for both HF and HG diets and at pH 5.8 (P = 0.02) for the HG diet. Adding ROD extract to the HF and HG diets linearly (P = 0.01) increased the acetate molar proportion at high or low media pH and consequently, the acetate to propionate (A:P) ratio linearly (P ≤ 0.04) increased. Supplementation of ROD extract to the HF diet linearly (P = 0.04) decreased the molar proportion of propionate at pH 6.5 (interaction between pH and ROD extract; P = 0.05), but had no effect on propionate proportion when added to the HG diet. Moreover, the proportion of branched-chain fatty acids linearly (P = 0.03) decreased with ROD extract supplementation at low pH (interaction, P < 0.05) for HF diet and linearly decreased (P = 0.05) at pH 6.5 for HG diet (interaction, P < 0.05). The NH3-N concentration was not affected by ROD supplementation in the HF diet but it linearly (P = 0.01) decreased with increasing dose rate in the HG diet. Methane concentration tended to linearly (P = 0.06) increase with ROD extract supplementation at high pH for HF diet and linearly increased at pH 5.8 (P = 0.06) and pH 6.5 (P = 0.02) for HG diet. These results indicate that the decreased DMD and increased A:P ratio observed with addition of ROD extract may be beneficial to HG-fed cattle to reduce the risk of rumen acidosis without negatively impacting fiber digestion.

Increasing dietary proportion of wheat grain in finishing diets containing distillers' grains: impact on nitrogen utilization, ruminal pH, and digestive function

Because of its high crude protein (CP) content, dietary inclusion of corn dried distillers' grains with solubles (DDGS) in finishing cattle diets can increase the ruminal loss of ammonia-nitrogen (NH3-N), which ends up excreted as urine urea-N (UUN). Increasing dietary fermentable energy supply can enhance ruminal use of N; however, it could also lead to acidotic conditions that compromise digestive function and animal performance. We evaluated the effects of partially replacing dietary corn grain with 20% or 40% (dry matter [DM] basis) wheat grain in finishing diets containing 15% corn DDGS on N utilization, ruminal pH, and digestive function. Nutrient intake and digestion, ruminal fermentation characteristics, microbial protein synthesis, route of N excretion, and blood metabolites were measured. Six ruminally fistulated crossbred beef heifers (initial body weight ± SD; 797 ± 58.8 kg) were used in a replicated 3 × 3 Latin square design with 28-d periods. Dietary treatments were either corn (73% of diet DM; CON), 53:20 corn:wheat blend (20W), or 33:40 corn:wheat blend (40W) as the major fermentable energy source. Dry matter intake (DMI) tended to be lower for heifers fed the 40W than CON and 20W diets. Feeding diets containing wheat grain led to an increase (P = 0.04) in neutral detergent fiber (NDF) intake. However, there was no diet effect (P ≥ 0.60) on apparent total tract DM and NDF digestibility. Feeding wheat grain led to a decrease (P ≤ 0.03) in mean and minimum pH, an increase (P = 0.04) in pH < 5.8 duration, and a tendency for an increase in the area and acidosis index for pH < 5.8 and 5.5. Nitrogen intake, which was lower (P = 0.04) for 40W than 20W heifers did not differ between CON and 20W heifers. There was no diet effect (P = 0.80) on ruminal NH3-N concentration and estimated microbial N flow. However, feeding diets containing wheat grain led to a decrease (P = 0.045) in UUN excretion (% total urine N). Fecal and total N excretion (% of N intake) increased (P < 0.01) following the addition of wheat grain to the diet. Apparent N retention was lower (P = 0.03) for 40W than CON and 20W heifers. In summary, although it led to a desirable decrease in UUN excretion, feeding wheat grain in corn DDGS-containing diets increased acidotic conditions in the rumen, which possibly led to the tendency for a decrease in DMI. The negative apparent N retention at the 40% wheat grain inclusion also suggests a decrease in nutrient supply, which could compromise feedlot performance.

Effect of replacing barley silage with calcium oxide-treated barley straw on rumen fermentation, rumen microbiota, nutrient digestibility, and growth performance of finishing beef cattle

Effect of calcium oxide (CaO) treatment of barley straw and salt on rumen fermentation, microbiota, digestibility, growth, and carcass quality of cattle was assessed. A replicated 4 × 4 Latin square metabolism experiment was conducted using eight heifers fed a wheat finishing diet with barley silage (B-SIL), barley straw (B-S), or 5.0% CaO-treated barley straw (CaOS) with or without NaCl (CaOS-NS). Growth over 115 d was assessed using 75 individually housed steers fed the above diets and an additional diet (I-CaOS), where CaO was added to straw just before feeding. There was no effect (P ≥ 0.08) of diet on rumen fermentation, digestibility, or carcass quality, although CaO decreased (P < 0.001) maximum pH and retained Na was decreased (P < 0.05) by CaOS-NS. Rumen bacterial abundance was altered (P ≤ 0.05) by diet. The average daily gain (ADG) of B-SIL and CaOS-NS steers was 14.1% greater (P ≤ 0.05) than BS and CaOS steers, whereas the gain:feed of CaOS-NS steers was 14.2% greater (P ≤ 0.05) than B-S and CaOS steers. Steers fed I-CaO had similar ADG and gain:feed to other treatments. CaO-treated straw without NaCl could replace barley silage in wheat diets, without compromising digestibility or growth in steers.

Effect of mixed live yeast and lactic acid bacteria on in vitro fermentation with varying media pH using a high-grain or high-forage diet

Two experiments were conducted to assess the effects of media pH and mixtures (SCEF) of live yeast [Saccharomyces cerevisiae (SC)] and lactic acid bacteria [Enterococcus faecium (EF)] on gas production (GP), dry matter disappearance (DMD), and volatile fatty acid (VFA) concentrations in batch culture using either high-forage (HF) or high-grain (HG) diets. Diets were evaluated in separate experiments, each as a complete randomized design with 2 (media pH 5.8 and 6.5) × 5 (control, three SCEF, monensin) factorial arrangement of treatments. The SCEF had varying ratios of SC:EF: 0:0 (control), 1.18:1 (SCEF1), 1.25:1 (SCEF2), and 1.32:1 (SCEF3), added on a log10 basis. For the HF diet, supplementation of SCEF had greater GP (P = 0.03) at pH 6.5 and greater DMD (P = 0.03) and VFA concentration (P < 0.01) at pH 5.8 and 6.5 than control. For the HG diet, acetate:propionate (A:P) ratio at pH 6.5 was greater (P = 0.05) for SCEF than control. Increasing ratio of SC to EF in SCEF linearly (P < 0.01) decreased GP and DMD and linearly increased acetate percentage at pH 6.5. These results suggest that optimizing the SC:EF ratio in a mixture of SCEF can help improve rumen fermentation.

Evaluation of hybrid rye on growth performance, carcass traits, and efficiency of net energy utilization in finishing steers

Crossbred beef steers with a high percentage of Angus ancestry [n = 240, initial shrunk body weight (BW), 404 ± 18.5 kg] were used in a 117-d feedlot experiment to evaluate the effect of hybrid rye (Rye; KWS Cereals USA, LLC, Champaign, IL) as a replacement for dry-rolled corn (DRC) on growth performance, carcass traits, and comparative net energy (NE) value in diets fed to finishing steers. Rye from a single hybrid (KWS Bono) with an ergot alkaloid concentration of 392 ppb was processed with a roller mill to a processing index (PI) of 78.8 ± 2.29. Four treatments were used in a completely randomized design (n = 6 pens/treatment; 10 steers/pen), where DRC (PI = 86.9 ± 4.19) was replaced by varying proportions of Rye [DRC:Rye, dry matter (DM) basis (60:0), (40:20), (20:40), and (0:60)]. Liver abscess scores and carcass characteristics were collected at the abattoir. Carcass-adjusted performance was calculated from hot carcass weight (HCW)/0.625. Performance-adjusted NE was calculated using carcass-adjusted average daily gain (ADG), DM intake (DMI), and mean equivalent shrunk BW with the comparative NE values for rye calculated using the replacement technique. Data were analyzed using the GLIMMIX procedure of SAS 9.4 (SAS Inst. Inc., Cary, NC) with pen as the experimental unit. Treatment effects were tested using linear and quadratic contrasts, as well as between diets with and without Rye. Replacing DRC with Rye linearly decreased (P ≤ 0.01) carcass-adjusted final BW, ADG, DMI, and gain:feed (G:F). Feeding rye linearly decreased HCW and longissimus muscle area (P ≤ 0.04). Distributions of liver scores and USDA grades for quality and yield were unaffected by treatment (P ≥ 0.09). Estimated replacement NE for maintenance (NEm) and gain (NEg) values for rye, when included at 60% of diet DM, were 1.90 and 1.25 Mcal/kg, respectively. Rye can be a suitable feed ingredient in finishing diets for feedlot steers. Estimated replacement values of Rye when fed at 60% of diet DM closely agreed with current tabular standards but, when included at 20% of diet DM, estimated NEm and NEg values of Rye were increased 9.5% and 12.8%, respectively. Net energy value of Rye for gain is approximately 84% compared to DRC; thus, the complete replacement of DRC with Rye depressed DMI, ADG, G:F, and carcass weight.

Influence of yeast culture and feed antibiotics on ruminal fermentation and site and extent of digestion in beef heifers fed high grain rations1

The study objective was to investigate the effects of site of delivering Saccharomyces cerevisiae fermentation product (SCFP) on ruminal pH and fermentation characteristics, and the site and extent of feed digestion in the digestive tract of beef heifers fed high-grain diets. Examining the ruminal and postruminal effects of SCFP is important for understanding the potential use of SCFP as an alternative for current industry-standard antibiotics used in beef cattle rations. Five beef heifers (initial BW = 561 ± 11.7 kg) equipped with ruminal and duodenal cannulas were used in a 5 × 5 Latin square design with 28-d periods, including 21 d for adaption and 7 d for data collection. Five treatments were as follows: 1) control diet that contained 10% barley silage and 90% barley concentrate mix (DM basis); 2) control diet supplemented with antibiotics (ANT; 330-mg monensin/d and 110-mg tylosin/d per head); 3) ruminal (top dress) delivery of SCFP (rSCFP; NaturSafe, Diamond V, 18-g SCFP/d); 4) duodenal delivery of SCFP (dSCFP; 18-g SCFP/d, via duodenal cannula); and 5) a combination of rSCFP and dSCFP (rdSCFP; 18-g rSCFP and 18-g dSCFP). Intake of DM tended (P < 0.10) to be greater by heifers fed rdSCFP than those fed control, ANT and rSCFP diets. Minimum ruminal pH was greater (P < 0.05) with rSCFP than control and rdSCFP treatments. The duration of ruminal pH < 5.6 tended (P < 0.10) to be less with rSCFP than control and ANT. Heifers fed the rSCFP diet had greater (P < 0.03) protozoa counts and proportion of acetate than the other treatments. Nutrient flows to the duodenum did not differ (P > 0.19), whereas the amount of truly fermented OM was greater (P < 0.03) with rdSCFP than the other treatments. Ruminal OM digestibility was highest with rSCFP and rdSCFP, intermediate with dSCFP and ANT, and lowest with control (P < 0.03). Intestinal digestibility was similar among treatments. As a result, total tract digestibility of OM (P < 0.07) and NDF (P < 0.01) was greater with rSCFP and rdSCFP than control and ANT. Fecal IgA concentration was highest with ANT, intermediate with dSCFP and rdSCFP, and lowest with control and rSCFP (P < 0.03). These results demonstrate that feeding SCFP improved stability of ruminal pH and digestibility of OM and NDF. Delivery of SCFP to the duodenum appeared to have little effect on nutrient digestibility but improved intestinal immune response. Feeding SCFP performed better or at least equal to antibiotics currently used in beef cattle rations and could be a natural alternative for beef cattle production.

Impact of strain and dose of live yeast and yeast derivatives on in vitro ruminal fermentation of a high-grain diet at two pH levels

The objective of this study was to determine the effects of live yeast (LY) or yeast derivatives (YD) on gas production (GP), dry matter (DM) disappearance (DMD), fermentation characteristics, and microbial profiles in batch culture. The study was a completely randomized design with a factorial arrangement: 2 media pH × 5 yeasts × 4 dosages. An additional treatment of monensin (Mon) was added as a positive control for each pH level. Media pH was low (5.8) and high (6.5); the yeasts were three LY (LY1-3) and two YD (YD4-5); and doses were 0, 4 × 106, 8 × 106, and 1.6 × 107 cfu mL−1 for LY and 0, 15, 30, and 60 mg bottle−1 for YD. Substrate consisted of 10% silage and 90% concentrate (DM basis) and samples were incubated for 24 h. Media pH of 6.5 vs. 5.8, increased (P < 0.01) GP, DMD, and volatile fatty acid (VFA) concentrations but decreased (P < 0.01) NH3-N concentration and copy numbers of Ruminococcus albus, Ruminococcus flavefaciens, and Selenomonas ruminantium. Increasing dose of LY2 linearly (P < 0.05) increased DMD. Total VFA concentration was greater with LY2 (P < 0.01) than LY3 and YD5 at pH 6.5. Overall, adding yeast products improved (P < 0.05) DMD at pH 5.8, and increased VFA concentration compared with Mon. These results indicate that in vitro GP and DMD of a high-grain diet varied with source and dose of yeast supplementation. Some yeast products have the potential to improve fermentation of feedlot diets when supplemented at appropriate doses.

Does intra-ruminal nitrogen recycling waste valuable resources? A review of major players and their manipulation

Nitrogenous emissions from ruminant livestock production are of increasing public concern and, together with methane, contribute to environmental pollution. The main cause of nitrogen-(N)-containing emissions is the inadequate provision of N to ruminants, leading to an excess of ammonia in the rumen, which is subsequently excreted. Depending on the size and molecular structure, various bacterial, protozoal and fungal species are involved in the ruminal breakdown of nitrogenous compounds (NC). Decelerating ruminal NC degradation by controlling the abundance and activity of proteolytic and deaminating microorganisms, but without reducing cellulolytic processes, is a promising strategy to decrease N emissions along with increasing N utilization by ruminants. Different dietary options, including among others the treatment of feedstuffs with heat or the application of diverse feed additives, as well as vaccination against rumen microorganisms or their enzymes have been evaluated. Thereby, reduced productions of microbial metabolites, e.g. ammonia, and increased microbial N flows give evidence for an improved N retention. However, linkage between these findings and alterations in the rumen microbiota composition, particularly NC-degrading microbes, remains sparse and contradictory findings confound the exact evaluation of these manipulating strategies, thus emphasizing the need for comprehensive research. The demand for increased sustainability in ruminant livestock production requests to apply attention to microbial N utilization efficiency and this will require a better understanding of underlying metabolic processes as well as composition and interactions of ruminal NC-degrading microorganisms.

Diets of differentially processed wheat alter ruminal fermentation parameters and microbial populations in beef cattle

The influences of differently processed wheat products on rumen fermentation, microbial populations, and serum biochemistry profiles in beef cattle were studied. Four ruminally cannulated Limousin × Luxi beef cattle (400 ± 10 kg) were used in the experiment with a 4 × 4 Latin square design. The experimental diets contained (on a DM basis) 60% corn silage as a forage source and 40% concentrate with 4 differently processed wheat products (extruded, pulverized, crushed, and rolled wheat). Concentrations of ruminal NH-N and microbial protein (MCP) in cattle fed crushed and rolled wheat were greater ( < 0.05) than the corresponding values in cattle fed pulverized and extruded wheat. Ruminal concentrations of total VFA and acetate and the ratio of acetate to propionate decreased ( < 0.05) with increased geometric mean particle size (geometric mean diameter) of processed wheat, except for extruded wheat; cattle fed extruded wheat had the lowest concentrations of total VFA and acetate among all treatments. The relative abundance of , , ciliated protozoa, and was lower in cattle fed the pulverized wheat diet than in the other 3 diets ( < 0.05), whereas the relative abundance of was decreased in cattle fed extruded wheat compared with cattle fed crushed and rolled wheat ( < 0.05). No treatment effect was obtained for serum enzyme activity and protein concentration ( > 0.05). Our findings suggest that the method of wheat processing could have a significant effect on ruminal fermentation parameters and microbial populations in beef cattle and that crushed and rolled processing is better in terms of ruminal NH-N and MCP content, acetate-to-propionate ratio, and relative abundance of rumen microorganisms.