Total Tract Digestibility Of OM Research Articles

Supplementing flaxseed meal with sucrose, flaxseed oil, or both: Effect on milk enterolactone, ruminal microbiota profile, production performance, and nutrient utilization in dairy cows

Flaxseed is the richest source of secoisolariciresinol diglucoside, which is converted by ruminal microorganisms primarily to the mammalian lignan enterolactone. Our objective was to investigate the effect of diets containing soybean meal or flaxseed meal (FM) supplemented with sucrose, flaxseed oil, or both on milk enterolactone concentration and yield, diversity and relative abundance of ruminal bacterial taxa, ruminal fermentation profile, production performance, milk fatty acid (FA) yield, and nutrient utilization in dairy cows. Sixteen Holstein cows [8 multiparous (4 ruminally-cannulated) and 8 primiparous] averaging (mean ± SD) 134 ± 54.1 DIM and 679 ± 78.9 kg of BW in the beginning of the study were assigned to treatment sequences in a replicated 4 × 4 Latin square design. Each experimental period lasted 25 d with 18 d for diet adaptation and 7 d for data and sample collection. Diets were formulated to contain a 60:40 forage:concentrate ratio and included (DM basis): 1) 8% soybean meal and 23% ground corn (SBM), 2) 15% FM, 10.7% ground corn, and 5% sucrose (FLX+S), 3) 15% FM, 15.4% ground corn, and 3% flaxseed oil (FLX+O), and 4) 15% FM, 10.2% ground corn, 5% sucrose, and 3% flaxseed oil (FLX+SO). Compared with SBM, the concentration and yield of milk enterolactone increased in cows fed the FM diets, but did not differ among FLX+S, FLX+O, and FLX+SO. The relative abundances of the phyla Firmicutes, Verrucomicrobiota, and Actinobacteriota and those of the bacterial genera Lachnospiraceae NK3A20 group, Eubacterium coprostanoligenes group, Anaeromusa-Anaeroarcus, WCHB1-41, and p-251-o5 decreased, whereas Prevotella and NK4A214 group increased when comparing SBM against at least 1 diet containing FM. Furthermore, the relative abundances of Firmicutes and Actinobacteriota and those of Prevotella, Lachnospiraceae NK3A20 group, Eubacterium coprostanoligenes group, Acetitomaculum, Lachnospiraceae unclassified, NK4A214 group, and Anaeromusa-Anaeroarcus changed (increased or decreased) across the FLX+S, FLX+O, and FLX+SO diets. However, all these changes in the relative abundance of the ruminal bacterial taxa were not conclusively associated with the effect of diets on milk enterolactone. Diets did not affect ruminal pH and concentrations of NH3-N and total VFA. Dry matter intake and yields of milk, milk fat, and milk true protein all decreased in cows fed FLX+O or FLX+SO. Yields of milk total odd-chain FA, branched-chain FA, total < 16C FA, and total 16C FA all decreased with feeding FLX+O and FLX+SO. The apparent total-tract digestibilities of DM and OM were lowest in the FLX+S and FLX+O diets, with CP and ADF digestibilities lowest in cows receiving FLX+S or FLX+O, respectively. Urinary excretion of total N was lowest with feeding SBM. Contrarily, diets did not affect the urinary excretion of total purine derivatives. In brief, despite the effect of diets on the relative abundance of several ruminal microbiota phyla and genera, we were unable to conclusively associate these changes with increased milk enterolactone in FM-containing diets versus SBM.

145 The effect of a plant secondary metabolite blend on energy metabolism and nutrient balance of beef cattle consuming low-quality warm season grass hay

Abstract Plant secondary metabolites (PSM) such as condensed tannins, hydrolysable tannins, saponins and essential oils purportedly impact rumen fermentation at low inclusion rates in beef cattle diets. Twelve steers (347 ± 23 kg BW) of British and continental influence were allocated to 1 of 4 replicated 3 x 3 Latin squares. Latin squares each had 14 d periods (10 d adaptation and 4 d for sample collection). All cattle were fed ground warm-season hay (89.5% DM, 92.8% OM, 65.9% NDF, 43.6% ADF, 6.70% CP) at 1.5% of BW (DM-basis) and supplemented with soybean meal at 0.18% of BW (DM-basis) once daily. Treatments consisted of a blend of tannins, saponins and essential oils provided at 0% (Control), 0.1% (Low) and 0.3% (High) of hay offering. Treatments were mixed with daily soybean meal allotment and provided before feeding of hay. Urine and feces were completely collected from d 11 through 14 at 0730 h and daily amounts of urine and feces produced were measured gravimetrically. Measures of gaseous exchange were determined via indirect calorimetry on d 13 and 14. Open-circuit respiration calorimeters (91.4 × 91.4 × 191.2 cm) were used to collect respired gas and ruminal methane production. Total oxygen consumption and production of carbon dioxide and methane were calculated from the difference in concentration of oxygen, carbon dioxide, and methane from air exhausted from each calorimeter and concentration of oxygen, carbon dioxide, and methane in ambient air and multiplied by amounts of air flowing from each calorimeter standardized for temperature, pressure, and humidity. Data were analyzed for a Latin square using the MIXED procedure of SAS with fixed effect of treatment, period and square and random effect of steer. Linear and quadratic contrast coefficients were assigned using PROC IML for uneven spacing of treatments. Significance was declared when P ≤ 0.05. Per experimental design, forage N and OM intake did not differ (P ≥ 0.77). Apparent total tract digestion of OM, NDF and ADF did not differ (P ≥ 0.66) among treatments. Fecal nitrogen excretion, and the percentage of N excreted in feces increased linearly (P = 0.01). N balance tended (P = 0.08) to decrease linearly with increasing PSM supplemented. Methane (L/kg DMI) was not affected (P = 0.28) by treatments. Methane, GE, DE, and ME (mcal/kg DMI) was unaffected (P = 0.19) by treatment. Under the conditions of this experiment, a blend of PSM had little effect on rumen fermentation or energy metabolism in beef steers.

363 Effect of Protein and Starch Supplementation Level on Intake and Digestibility By Steers Consuming Low-Quality Forage: I. Bos Taurus Taurus

Abstract A deficiency of ruminally available N (RAN) caused by a basal diet of low-quality forage depresses forage utilization. Supplemental protein improves forage utilization by increasing RAN, resulting in increased intake and potentially improving digestion. Addition of starch to a supplement can increase total digestible OM intake (TDOMI); however, too much starch decreases RAN creating competition between fiber and starch fermenting bacteria potentially decreasing forage utilization. Our objective was to determine the effect of starch supplementation on intake and digestion in Bos taurus taurus steers. Accordingly, five ruminally cannulated Angus steers (BW 375 ± 45 kg) were used in a 4 × 4 Latin square to evaluate the effect of decreasing supplemental starch when consuming King Ranch Bluestem hay (3.5% CP, 73% NDF). Steers received four isonitrogenous (130 mg N/ kg BW) supplements providing increasing levels of starch (2% starch = 100% soybean meal; 20% starch = 26.3% corn, 73% soybean meal, 0.7% urea; 38% starch = 51.6% corn, 47% soybean meal, 1.4% urea; 56% starch = 78.6% corn, 19% soybean meal, 2.4% urea). Five 14-d periods were conducted, consisting of 9 d adaptation and 4 d to measure intake and digestion, and 1 d for ruminal fermentation. As designed, supplement OM intake (SOMI) increased linearly (P &amp;lt; 0.01) as starch level increased. Forage OM intake (FOMI) decreased linearly with increasing starch (P &amp;lt; 0.01). Increases in SOMI and decreases in FOMI combined to result in no significant (P ≥ 0.14) differences in total OMI (TOMI) between starch levels. Total digestible OMI (TDOMI) responded quadratically (P = 0.05) to increasing starch and was 45.8, 49.4, 48.4 and 41.9 g TDOMI/kg BW0.75 for 2, 20, 38, and 56% starch, respectfully. Total DOMI was 18% greater when steers were provided 20% starch supplement compared with 56% starch. Similarly, total digestible NDF intake responded quadratically (P = 0.05) and was maximized with 20% starch. Total tract OM digestion and NDF digestion were not significantly affected (P ≥ 0.15) by starch level in the supplement. In conclusion, providing supplemental starch over 20% decrease forage utilization. Decreases in FOMI with starch inclusion may be attributed to competition for RAN between fiber fermenting and starch fermenting bacteria.

Evaluation of condensed algal residue solubles as an ingredient in cattle finishing diets and the effects on digestibility and fatty acid flow

Our objective was to evaluate the effects of inclusion of condensed algae residue solubles (CARS) in corn-based cattle finishing diets on performance, carcass characteristics, and duodenal concentrations of fatty acids. In Exp. 1, 480 British (pre- dominately Angus) crossbred steers (initial BW = 432 kg; SD = 40 kg) were finished using a 2 × 3 factorial treat- ment arrangement. Treatments were CARS (0, 2.5, 5% of diet DM) displacing dry-rolled corn:high-moisture corn (DRC:HMC) or steam-flaked corn (SFC). In Exp. 2, feed- ing 0, 2.5, or 5% CARS in SFC diets was evaluated for digestibility and fatty acid flow using 6 ruminally can- nulated steers in a 3 × 3 replicated Latin Square design. The main effects of CARS included quadratic responses (P ≤ 0.01) for carcass-ad-justed final BW, ADG, G:F, hot carcass weight, 12th-rib fat, and YG. The main effects of diet indicated SFC di- ets had greater (P ≤ 0.02) G:F, hot carcass weight, and 12th-rib fat compared with DRC:HMC diets. In Exp. 2, inclusion of CARS in the diet did not affect total-tract DM, OM, or NDF digestibility (P ≥ 0.52). Total fatty acid flow at the duodenum was unaffected (P = 0.18) by treat- ment. However, there was a linear increase (P < 0.01) in C16:0, C18:0, C18:1 trans, C18:1 vaccenic acid, and C22:6 omega-3 docosahexaenoic fatty acid flow as CARS inclu- sion increased. Including 2.5% CARS in finishing diets improved G:F and increased n-3 fatty acids at the duodenum.

Dried distiller´s grains plus solubles supplementation improves low-quality tropical grass utilization on beef steers

ABSTRACT: This study was designed to evaluate the effect of corn dried distiller´s grains (DDGS) supplementation on feed intake, total tract digestibility, and ruminal fermentation of beef steers fed low-quality Guinea grass (Megathyrsus maximus, cv. Gatton panic). Twelve Braford crossbred steers were housed in individual pens (n = 4 steers/treatment), provided with three levels of DDGS supplement: 0%, 0.6%, or 1.2% BW. Steers were blocked by live weight and randomly assigned to treatments within the block. Corn DDGS supplementation increased total OM intake (21.55, 40.23, and 56.69 g/kg BW0.75) and tract OM digestibility (46.33, 49.03, and 72.39 % DM). Total tract digestible OM, CP, NDF and EE intake also increase in response to DDGS supplementation. Forage OM intake decreased when supplementation level reached 1.2 % BW. Also, ruminal pH decreased with DDGS supplementation level (6.88, 6.47, and 6.27). No differences were observed in total volatile fatty acids (VFA) concentration; however, the molar proportion of acetate decreased (77.98, 73.90, and 67.29 % Total VFA) as well as acetate: propionate ratio (4.38, 3.48, and 2.74). On the contrary, propionate proportions increased (18.32, 21.86, and 24.81 % Total VFA). Levels of ammonia and lactate were within suggested values for optimal fermentation and bacterial growth. Low-quality grass supplementation with corn DDGS increased total OM intake and digestibility. Also, DDGS inclusion favorably altered volatile fatty acids profile by reducing the acetate to propionate ratio regarding forage-only diets.

309 Nutrient Digestibility of Beef Steers Consuming Finishing Diets with an Added Nutritional Packet

Abstract The effects of a nutritional packet fed to beef steers during the final 64 d of the feedlot finishing phase on apparent total tract nutrient digestibility were evaluated. Angus-crossbred steers (n =120; initial BW = 544 ± 52 kg) were assigned to 30 pens (4 steers/pen; 15 pens/treatment; pen = experimental unit) in a randomized complete block design. A steam-flaked corn-based finishing diet was fed ad libitum and treatments applied as follows: 1) control and 2) 30 g/steer-daily (DM-basis) of the nutritional packet [containing live yeast (Saccharomyces cerevisiae; 8.7 Log CFU/g), vitamin C (5.4 g/kg), vitamin B1 (13.33 g/kg), NaCl (80 g/kg) and KCl (80 g/kg)]. The nutritional packet used ground corn as a carrier and was included at 1% of diet DM. Orts were quantified daily (if any) and subtracted from the total dietary DM offered to calculate DM intake. Fecal samples were collected twice daily (0700 and 1700 h) for 5 consecutive days (d 47 to 51) from at least 3 steers within pen. Feed samples were collected daily at time of feeding (0630 h). Fecal and feed samples were composited to represent the collection period, dried (55oC), ground (1 mm), and analyzed to assess DM, OM, NDF, ADF, and hemicellulose. In situ (288 h) iNDF was used as an internal marker to measure apparent total tract nutrient digestibility. Data were analyzed using the GLIMMIX procedure of SAS. Intake of DM, OM, and fiber components during the digestibility period was not affected (P ≥ 0.44) by treatment. Steers fed the nutritional packet had increased apparent total tract digestibility of OM (P = 0.02), DM (P = 0.01), NDF (P = 0.02), ADF (P = 0.01), and hemicellulose (P = 0.08; tendency). Improved nutrient digestibility without affecting nutrient intake may warrant an enhanced energy deposition in the carcass.

PSX-B-3 Effect of infrequent nitrogen supplementation on forage utilization

Abstract Our objective was to determine the effects of differing levels of supplemental nitrogen offered daily, or every 3 d on nitrogen balance, forage intake, and digestibility in cattle consuming low-quality forage. Five ruminally cannulated Angus × Hereford steers (BW = 350 ± 71 kg) were used in a 5 × 5 Latin square design. Steers consumed low-quality bluestem hay (67.7% NDF, 4.7% CP; DM basis) ad libitum. Treatments were no supplement (CON), or cottonseed meal offered at levels providing 120 mg N/kg BW each day (L/1D) or every 3 d (L/3D), 240 mg N/kg BW every 3 d (M/3D), or 360 mg N/kg BW every 3 d (H/3D). Hay, ort, urine, and fecal samples were collected during the last 6 d of each period and ruminal fluid during the last 3 d. Total digestible OM intake was greater in L/1D (6660 g/d; P &amp;lt; 0.01) compared to CON (4498 g/d) and increased linearly in steers supplemented intermittently (5145, 6170, and 6698 g/d for L/3D, M/3D, and H3/D, respectfully; P &amp;lt; 0.01). Total tract OM digestibility was similar between CON and L/1D, L/3D, and H/3D (58.21, 61.21, 60.82, and 60.91%, respectively; P ≥ 0.10) but was greater in M/3D steers (63.30%; P ≤ 0.02). Reducing frequency of protein supplementation to every 3-d improved forage intake and utilization similar to daily supplementation when provided at medium (240 mg N/kg BW) or high (360 mg N/kg BW) levels. Improved efficiency of nitrogen recycling likely buffered disruptions in protein supply, maintaining intake and digestibility of low-quality forage without daily supplementation. Supplementation of protein every 3 d at 240 g N/kg BW appears to the most biologically effective strategy, increasing intake of LQF and maximizing OM digestibility and N utilization.

321 Extrusion of Grass Silage Increase Intake and Milk Yield in Dairy Cows

Abstract This research evaluated effects of grass silage extrusion on dairy cow performance. A grass dominated (70% timothy, 26% meadow fescue, 3% red clover and 1% undefined) first cut ley was harvested on June 13, 2019, and 10 days later near Uppsala, Sweden (58°83′ N, 17°82′ E). Crops were wilted (45% DM for early cut, 50% DM for late cut), round baled and wrapped into plastic film for ensiling. At feeding out, bales were chopped in a TMR feeder, and a portion was processed in an extruder, where screws shear the material under pressure, for further particle size reduction and cell wall break up. Eight Swedish Red cows in two blocks (4 ruminally fistulated, 143 ± 38 DIM and 4 intact, 68 ± 10 DIM) were used in a Latin square design experiment with 4 periods of three weeks each and 4 treatments. The 2x2 factorial arrangement of treatments included silage from early or late harvest that was chopped or extruded. Silage was fed separately ad libitum and supplemented (daily amounts on an as fed basis) with 2 kg of soybean meal, a compound feed (6 kg for fistulated and 8 kg for intact cows), and 120 g of a mineral mix. Extrusion increased silage DMI (1.8 kg/d, P &amp;lt; 0.001) with greater effect at late harvest (P = 0.021 for interaction between processing and harvest) and milk yield (1.8 kg ECM/d, P = 0.004) with a tendency to greater effect at late harvest (P = 0.055). Extrusion depressed total tract OM digestibility (2.3 percentage points, P &amp;lt; 0.001), eating time (0.5 h/d, P = 0.014), rumination time (2.0 h/d, P &amp;lt; 0.001) and rumen pH (0.1 units, P = 0.008). Extrusion improves intake and milk production in dairy cows, despite depressed digestibility.

Digestion characteristics and prediction of digestible energy and total digestible nutrients in beef cattle finishing diets containing traditional and by-product lipid sources

Our objective was to determine effects of supplemental fat sources on digestion and energy predictions in feedlot diets containing several lipid sources. Five ruminally fistulated steers (520 ± 41 kg of BW) were fed in a 5-period Latin square design. Dietary treatments included control (CORN) or 4 finishing diets containing (1) 4.8% added corn oil (OIL), (2) 4.8% beef tallow (TAL), (3) 25.5% corn condensed distillers solubles (CCDS), or (4) 56% wet distillers grains plus solubles (WDGS). Total-tract OM digestibility was multiplied by dietary OM content to determine digested OM (DIGOM; % of DM). Measured dietary DE (Mcal/kg) was converted to TDN using 4.4 Mcal of DE/kg of TDN. The unsaturated-to-saturated total fatty acid ratio of omasal samples of steers fed WDGS was greater than that for other treatments ( P = 0.01). Apparent total-tract diet NDF digestibility was least for steers fed OIL ( P < 0.04). The difference between TDN (% of DM) and DIGOM (% of DM) increased ( P < 0.01) as dietary GE increased across treatments. These results suggest DIGOM (% of DM) does not relate to TDN (% of DM) on a consistent basis when high-fat by-products are used and that measured DE (Mcal/kg) is needed to predict performance. In finishing diets containing WDGS, additional DE is not accounted for when evaluating only DIGOM. Measuring DE content of diets used in digestion trials is important when trying to estimate feeding values.

Performance of Holstein calves receiving increased nutrient intake through the addition of skim milk or milk replacer powder to the whole milk

The purpose of this research was to describe the performance of Holstein calves before and after weaning when total solids in their daily milk were increased with skim milk or milk replacer powder. Forty-five female Holstein calves (body weight = 39.5 ± 1.61 kg) were assigned in random to 1 of 3 treatments: 1) whole milk (WM) with total solids of 123 ± 4.1 g/kg, 2) whole milk + skim milk powder (WM + SM) with total solids of 181 ± 6.2 g/kg, and 3) whole milk + milk replacer powder (WM + MR) with total solids of 184 ± 9.7 g/kg. Calves received 6 l/day of milk from days 2–14, 7 l/day from days 15–35, 6 l/day from days 36–42, 5 l/day from days 43–49, and then 2 l/day from days 50 until weaning (d 56). Calves remained in the study until day 90. Calves exhibited no difference in their pre- and post-weaning starter consumption. Although pre-weaning feed conversion efficiency was slightly different among calves, post-weaned calves receiving WM were more efficient in converting feed nutrients to body weight gain. Evolution of body frame development was slightly different among calves. However, WM + SM-fed calves had greater body length at weaning. Pre-weaning weight gain and body weight at weaning were greater when calves consumed high-solids milk based on SM or MR. Feeding WM + SM increased the number of days with diarrhea, which resulted in the highest proportion of calves in this group to receive antibiotics treatment. Amount of electrolytes administered per calf as well as days with antibiotic therapy were generally lesser in WM-fed calves. Slight treatment differences were noted in post-weaning total-tract digestion of DM, CP and OM in calf starter. However, fat digestibility was greatest in calves consuming WM + SM. Overall, our findings indicate that a high-solids milk feeding strategy based on SM or MR improved calf growth rate in the pre-weaning phase while having no effect on starter consumption. However, diarrhea incidence increased when calf nutrient intake was increased through SM.

278 Effect of Feeding CARS on Digestibility in Finishing Cattle Diets

Abstract An experiment was conducted to evaluate the digestibility of a novel liquid feed, Condensed Algal Residue Solubles (Veramaris, Blair, NE) in finishing cattle diets. Mass production of algae to harvest omega-3 fatty acids results in byproduct production of CARS (25.4% DM, 19.3% CP, 8.3% Fat, 9.96% Na on DM basis), made up of the de-oiled algae cells and residual fermentation substrates. The CARS product has generally recognized as safe (GRAS) status. Six ruminally and duodenally cannulated crossbred steers were assigned randomly to 1 of 3 treatments over 3 collection periods, for a 3 x 3 replicated Latin Square design. Treatments differed by increasing inclusion of CARS (0, 2.5, and 5% of diet DM) fed with CARS replacing steam flaked corn (72, 69.5, and 67% of diet DM as CARS inclusion increased). All diets contained 15% dry distillers grains, 8% alfalfa haylage, and 5% supplement. Cattle were dosed with 10 g of titanium dioxide per day. Duodenal and fecal samples were collected four times per day across four days and composited by period for each animal. Fecal samples were analyzed for titanium dioxide concentration to determine fecal output and diet digestibility. Data were analyzed with CARS inclusion and period as fixed effects and animal as a random effect. Orthogonal contrasts were used to test linear and quadratic effects of CARS inclusion. There were no significant differences for DM intake and OM intake between the different CARS inclusions (P ≥ 0.17), averaging 7.76 kg DM/d and 6.94 kg OM/d. Total tract DM digestibility was not affected by treatment (P ≥ 0.71) and averaged 73.0%. Total tract OM digestibility was also not different between treatments (P ≥ 0.93) and averaged 71.1%. Replacing steam flaked corn with CARS up to 5% of diet DM in finishing cattle diets did not affect diet digestibility.

Effects of a blend of cinnamaldehyde-eugenol and capsicum (Xtract® Ruminant 7065) and ionophore on performance of finishing Holstein steers and on characteristics of ruminal and total tract digestion

ABSTRACT Our objective was to evaluate the interaction of supplemental essential oils (EO) and monensin (MON) on performance and digestion. Two levels of EO (0 vs 0.011% Xtract®) and two levels of MON (0 vs 33 mg/kg) were evaluated in a 2 × 2 factorial arrangement. Treatment effects on 216-d growth performance were evaluated in 96 Holstein steers. Supplemental MON enhanced (P ≤ 0.05) ADG, DMI and gain efficiency. Without EO, MON improved (P < 0.05) gain efficiency and dietary NE. However, in diets with both EO and MON, gain efficiency and dietary NE were not different from non-supplemented diets (interaction, P < 0.10). Treatment effects on characteristics of digestion were evaluated using four cannulated steers. Ruminal digestion of OM and N were greater for MON alone. Ruminal digestion of OM and N were similar for EO-alone vs MON-alone, but not by the combination of the two (interaction P ≤ 0.02). Supplemental MON enhanced (P ≤ 0.02) total tract digestion of OM and N. We conclude that supplemental EO-alone or MON-alone may enhance gain efficiency and NE value of the diet. However, effects are negated when fed in combination. Treatment effects on performance are consistent with digestion measures.

Association of fibre degradation with ruminal dissolved hydrogen in growing beef bulls fed with two types of forages.

The present study investigated the association between fibre degradation and the concentration of dissolved molecular hydrogen (H2) in the rumen. Napier grass (NG) silage and corn stover (CS) silage were compared as forages with contrasting structures and degradation patterns. In the first experiment, CS silage had greater 48-h DM, neutral-detergent fibre (NDF) and acid-detergent fibre degradation, and total gas and methane (CH4) volumes, and lower 48-h H2 volume than NG silage in 48-h in vitro incubations. In the second experiment, twenty-four growing beef bulls were fed diets including 55 % (DM basis) NG or CS silages. Bulls fed the CS diet had greater DM intake (DMI), average daily gain, total-tract digestibility of OM and NDF, ruminal dissolved methane (dCH4) concentration and gene copies of protozoa, methanogens, Ruminococcus albus and R. flavefaciens, and had lower ruminal dH2 concentration, and molar proportions of valerate and isovalerate, in comparison with those fed the NG diet. There was a negative correlation between dH2 concentration and NDF digestibility in bulls fed the CS diet, and a lack of relationship between dH2 concentration and NDF digestibility with the NG diet. In summary, the fibre of CS silage was more easily degraded by rumen microorganisms than that of NG silage. Increased dCH4 concentration with the CS diet presumably led to the decreased ruminal dH2 concentration, which may be helpful for fibre degradation and growth of fibrolytic micro-organisms in the rumen.

Substitution of wheat straw with sugarcane bagasse in low-forage diets fed to mid-lactation dairy cows: Milk production, digestibility, and chewing behavior

Sugarcane bagasse (SB) is a low-quality roughage source that is often plentiful during times of forage shortage. It is generally less costly compared with other conventional sources of forage. We hypothesized that SB could be used as a source of roughage for dairy cattle by replacing wheat straw (WS), another low-quality forage. This study evaluated the effects of replacing WS with SB in diets offered to mid-lactation dairy cows on milk production and fatty acid profile, intake, digestibility, chewing activity, and ruminal fermentation. Nine multiparous Holstein cows averaging (mean ± standard deviation) 105 ± 12 d in milk, 42.1 ± 2.9 kg of milk/d, and 617 ± 59 kg of body weight were used in a replicated 3 × 3 Latin square with 21-d periods. Treatments were (% of dietary dry matter, DM): (1) 0SB, diet containing 0% SB and 27% WS, (2) 9SB, diet containing 9% SB and 18% WS, and (3) 18SB, diet containing 18% SB and 9% WS. Sugarcane bagasse had greater organic matter (OM; 94.1 vs. 85.1% of DM), neutral detergent fiber (NDF; 86.2 vs. 76.4% of DM), acid detergent fiber (ADF; 62.9 vs. 45.2% of DM), and lignin (19.9 vs. 10.3% of DM) concentration, but less crude protein (CP; 2.63 vs. 3.72% of DM) concentration than WS. Sugarcane bagasse also had greater physically effective NDF (total dietary NDF multiplied by % of TMR on the 8-mm + 19-mm sieves, peNDF8; 63.2 vs. 40.6% of DM) and undegraded NDF after 288 h of incubation (uNDF288; 35.5 vs. 21.2% of DM) contents than WS. The undegraded NDF after 30 h of incubation (uNDF30) content was similar for all diets; however, peNDF8 concentration and proportion of long particles (retained on a 19-mm sieve) increased linearly as SB inclusion in the diets increased. Cows increasingly sorted against long particles as SB replaced WS. Intakes of DM (26.53 kg/d) and NDF (8.58 kg/d) did not differ among the treatments, but intakes of OM and CP decreased, whereas ADF and uNDF288 intakes increased with SB inclusion level. Total-tract digestibilities of OM, CP, and NDF decreased linearly as SB replaced WS. Milk yield (37.0 kg/d), energy-corrected milk yield (ECM; 38.2 kg/d), feed efficiency (1.44 kg ECM yield/kg DM intake), and milk composition (fat, 3.89%; true protein, 2.90%) did not differ among diets. Increasing SB concentration of the diet linearly increased rumination time, but ruminal pH (ruminocentesis, 4 h after feeding) decreased. Total volatile fatty acid concentration increased linearly, whereas acetate:propionate decreased linearly, as SB replaced WS. The results indicate that replacement of WS with increasing levels of SB in low-forage diets with similar uNDF30 concentrations did not affect performance of mid-lactation dairy cows. We conclude that SB can be used as a fiber source in diets fed to dairy cows in mid-lactation; however, the decrease in total-tract digestibility of diets may decrease lactational performance when fed to high-producing dairy cows.

Evaluating Strategies to Reduce Ruminal Protozoa and Their Impacts on Nutrient Utilization and Animal Performance in Ruminants - A Meta-Analysis.

Several studies have evaluated the effects of complete or partial ruminal protozoa (RP) inhibition; however, to this date, no practical suppressant has been identified and used in large scale. This meta-analysis quantitatively evaluates the effectiveness of multiple strategies on inhibiting RP numbers and their influence on ruminal fermentation and animal performance. This study compared 66 peer-reviewed articles (16 manuscripts for complete and 50 manuscripts for partial RP inhibition that used supplemental phytochemicals and lipids, published from 2000 to 2018, to inhibit RP in vivo. Data were structured to allow a meta-analytical evaluation of differences in response to different treatments (complete RP inhibition, phytochemicals, and lipids). Data were analyzed using mixed models with the random effect of experiment and weighted by the inverse of pooled standard error of the mean (SEM) squared. Supplemental phytochemicals and LCFA had no effects on inhibiting RP numbers; however, supplemental MCFA had a potent antiprotozoal effect. Both complete and partial RP (supplemental phytochemicals and lipids) inhibition decreased methane production, total tract digestibility of OM and NDF, and ruminal NH3-N concentration and increased propionate molar proportion. Methane production, molar proportions of acetate and propionate, total tract NDF digestibility were affected by the interaction of treatment (supplemental phytochemicals and lipids) and RP numbers. Supplemental phytochemicals and lipids can be effective in reducing methane production when RP numbers is below 7 Log10 cells/mL, especially by supplemental saponins, tannins, and MCFA. In terms of animal performance, supplemental tannins could be recommended to control methane emissions without affecting animal performance. However, their negative effects on total tract digestibility could be a drawback when feeding tannins to ruminants. The negative effects of supplemental lipids on milk fat composition should be considered when feeding lipids to ruminants. In conclusion, ruminal protozoa play important roles on methanogenesis, fiber digestion, and ruminal NH3-N concentration, regardless of experimental diets and conditions; supplemental phytochemicals and lipids can be effective on reducing methane production when RP numbers is below 7 Log10 cells/mL. Among these partial RP inhibition strategies, supplemental tannins could be recommended to control methane production.

Influences of urea fermentation potential on growth performance, dietary energetics, digestive function, and blood urea N in Holstein steers fed a finishing diet based on steam-flaked corn where metabolizable protein supply was otherwise in excess of theoretical requirement

ABSTRACT Objectives This study was conducted to examine the effect of urea fermentation potential (UFP) on digestive function, BUN, growth performance, and dietary energetics, in steers fed a finishing diet based on steam-flaked corn containing 15% dried distillers grains with solubles. Materials and Methods Four UFP levels were evaluated (−0.30, 0.10, 0.50, 0.90). The UFP levels were manipulated by dietary urea inclusion level of 1.20, 0.80, 0.40 and 0%, respectively (DM basis). Results and Discussion Dietary UFP did not affect (P > 0.10) ruminal digestion of feed N. Ruminal starch digestion decreased with increasing UFP (linear effect, P = 0.02). Ruminal digestion of starch and OM tended to be maximal (quadratic effect, P ≤ 0.07) at dietary UFP of 0.1%. Increasing UFP decreased flow to duodenum of nonammonia-N (linear effect, P = 0.04), and microbial N (linear effect, P = 0.05). Duodenal flow of feed N was not affected (P = 0.18) by dietary UFP. Increasing dietary UFP decreased total-tract digestion of OM (linear effect, P = 0.02), starch (linear effect, P = 0.03), and digestible energy (linear effect, P = 0.03). Increasing dietary UFP decreased ruminal pH (linear effect, P = 0.01) 1 h after feeding. Thereafter, the influence of dietary UFP on ruminal pH was not appreciable. Increasing dietary UFP decreased ruminal ammonia-N 1 h after feeding (linear effect, P Implications and Applications Even when finishing diet formulations otherwise exceed MP requirements, dietary UFP level remains a relevant factor to optimize dietary energy use. Dietary UFP levels greater than 0.50% could negatively affect digestion, gain efficiency, and dietary NE use.

Alfalfa leaves as a protein source: Replacement value of alfalfa leaves for soybean-meal protein in forage-based diets fed to mature ewes

Four ruminally and duodenally cannulated mature ewes (BW65.8 4.6kg) were used in a 4x4 Latin square designed experiment to investigate the replacement value of alfalfa leaves (AL) for soybean meal (SBM) protein. Ewes received basal diets consisting of bromegrass hay, cracked corn, and one of four protein supplements. Diets were formulated to be isonitrogenous by replacing SBM with AL on a nitrogenous basis. Supplement treatments were 100% SBM; 33.3% AL and 66.7% AL and 33.3% SBM and 100% AL. Experimental periods were 14 days with 10 days of diet adaptation followed by 4 days of ruminal, duodenal, and fecal sample collection. Replacing SBM with AL decreased intake of OM and NDF (quadratic; P&lt;.02). Intake of N increased as AL replaced SBM, which resulted in a cubic effect (P=.06). Organic matter flow and tru ruminal OM digestibility were not affected (P.18) by replacement of SBM with AL. Lower and total tract OM digestibility increased from the 33.3% AL to the 66.7% AL diet and decreased from the 66.7&amp; AL to the 100% AL dietary treatment resulting in cubic effects (P=.01 and .03, respectively). Nitrogen flow and true ruminal N digestibility were not influenced (P.18) by supplemental protein treatment. Greater lower tract N digestibility for 33 and 67% AL resulted in a quadratic effect (P=.05, whereas total tract N digestibility was not affected (p.13) by replacing SBM with AL. No treatment differences (P.20) were detected for NDF flow or ruminal NDF digestibility. Digestibility of NDF entering the small intestine tended to respond quadratically (P=.09) with a tendency for a cubic effect (P=.08) for tor total tract NDF digestibility as a result of greater digestibility of 66.7% ALdiet. Ruminal pH increased quadratically (P=.0004), while ruminal NH3, N tended to decrease linearly (p=.10) as AL replaced SBM. Ruminal particulate and fluid passage rates were not influenced (P .21) by replacing SBM with AL. Total VFA concentrations within the rumen decreased in a quadratic (P=.05) fashion. Acetate:propionate ratio responded quadratically (P=.0001) due to higher acetate:propionate ratios for diets containing a combination of supplementary protein. Alfalfa leaves can replace soybean meal as a protein supplement; however, greater nutritional value was apparent when the two protein sources constituted the supplement.

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.

Effects of rumen-protected arginine supplementation and arginine-HCl injection on site and extent of digestion and small intestinal amino acid disappearance in forage-fed steers.

Four ruminally and intestinally cannulated steers were used in a 4 × 4 Latin square to evaluate effects of rumen-protected Arg supplementation or intravenous Arg injection on small intestinal delivery of AA, site and extent of digestion, and ruminal fermentation. Steers were fed grass hay (7.2% CP, 67.6% NDF, 0.29% Arg) for ad libitum intake with no additional Arg (CON), 54-mg L-Arg/kg BW injected intravenously (Arg-INJ), 180-mg rumen-protected L-Arg/kg BW daily (Arg-RP180), or 360-mg rumen-protected L-Arg/kg BW daily (Arg-RP360). Half of each treatment dose was administered twice daily. Each period had a 7-d washout of hay only followed by a 14-d treatment and collection period. Ruminal disappearance (%) of Arg was greater (P < 0.001) for both Arg-RP treatments than CON and Arg-INJ, although the amount of Arg disappearing was greatest in Arg-RP360, followed by Arg-RP180, and least in CON and Arg-INJ (P < 0.001). Duodenal flow and small intestinal disappearance (g/d) of Arg was greatest in Arg-RP360, followed by Arg-RP180, and least in CON and Arg-INJ (P < 0.004). Ileal flow of Arg was greatest in Arg-RP360, intermediate in Arg-RP180, and least in CON (P = 0.01) because the proportional small intestinal disappearance of Arg was not different (P = 0.96). Steers fed Arg-RP360 had greater (P = 0.01) ileal flow of Orn and tended to have greater (P = 0.09) ileal flow of Glu than all other treatments. There were no differences in hay or total DMI, microbial efficiency, or OM, NDF, or ADF digestibility (P ≥ 0.10). Total N intake and duodenal N flow were greater in Arg-RP360 than all other treatments (P ≤ 0.02). Total tract N digestibility was greatest in Arg-RP360, followed by Arg-RP180, and least in CON and Arg-INJ (P = 0.003). Ruminal ammonia was greater (P = 0.004) in Arg-RP360 compared with CON and Arg-INJ and greater (P = 0.06) in Arg-RP180 than CON. There was no effect of treatment (P ≥ 0.37) on total VFA, acetate, propionate, or butyrate concentrations. Results indicate that feeding rumen-protected Arg increases small intestinal Arg flow with minimal effects on ruminal fermentation and total tract digestibility of OM and fiber.

Effects of different levels of lespedeza and supplementation with monensin, coconut oil, or soybean oil on ruminal methane emission by mature Boer goat wethers after different lengths of feeding

ABSTRACTMature Boer goat wethers were supplemented with 0.5% BW rolled corn and consumed pelleted alfalfa (CON), pelleted Sericea lespedeza (HSL; 6.4% condensed tannins), a 1:1 mixture of alfalfa and lespedeza (MSL), or alfalfa with monensin (ION; 22 mg/kg), coconut oil (CCO; 4%), or soybean oil (SBO; 4%). Total DM intake in the 20-wk study (3.86%, 3.75%, 3.52%, 3.69%, and 3.64% BW) and total tract OM digestibility determined every 5 wk (72.8%, 69.5%, 70.3%, 72.0%, and 71.1%) were not affected by treatment, although there were differences in nitrogen digestion (77.5%, 70.7%, 67.0%, 77.0%, 75.7%, and 73.6% for CON, MSL, HSL, ION, CCO, and SBO, respectively; SEM = 1.76). Ruminal methane emission was not influenced by period and was lowest among treatments for CON expressed as percentages of gross (10.3%, 6.8%, 6.3%, 7.2%, 6.5%, and 6.5%; SEM = 0.35) and digestible energy (14.8%, 10.2%, 9.3%, 10.6%, 9.8%, and 10.1% for CON, MSL, HSL, ION, CCO, and SBO, respectively; SEM = 0.62). In conclusion, both levels of lespedeza elicited similar depressions in ruminal methane emission, with a magnitude of change similar to that of an ionophore and coconut and soybean oils, and effects did not vary with week of the study.