Total Tract Digestibility Of DM Research Articles

The effect of replacing conventional alfalfa hay with lower-lignin alfalfa hay on feed intake, nutrient digestibility, and energy utilization in lactating Jersey cows

Lower-lignin (LoL) varieties of alfalfa (Medicago sativa L.) have been developed in recent years, and have the potential to positively impact animal performance. The objective of this study was to evaluate the effects of increasing the proportion of LoL alfalfa hay in diets fed to lactating dairy cows. Research plots were planted with a conventional variety (CON; Dairyland Hybriforce 3400), and 2 LoL varieties (LLG; 54HVX42 and LLB; Aflorex HiGest 460). After harvest, the LoL varieties were blended in equal proportions for feeding. Twelve multiparous Jersey cows (100 ± 4 d in milk) were used in a 3 × 3 Latin square with 3 periods of 28 d. Cows were assigned to 3 diets containing 0 (CNTRL), 16.1 (MdLL), and 32.2% (HiLL) of the diet DM as LoL alfalfa hay, which replaced CON. The CON alfalfa had average CP, NDF, and lignin contents (DM basis) of 20.5 ± 1.15, 42.1 ± 1.37, and 6.81 ± 0.57%, respectively, while the LoL alfalfa averaged 19.8 ± 0.75, 39.9 ± 1.56, and 6.07 ± 0.28%, respectively. No difference was observed in DMI (20.4 ± 0.61 kg/d). No difference in milk yield was observed, averaging 31.0 ± 1.02 kg/d across treatments. Similarly, no difference was observed in ECM yield (averaging 36.2 ± 1.43 kg/d). Feed conversion (ECM/DMI) tended to increase linearly with LoL alfalfa inclusion (1.74 to 1.80 ± 0.03). No difference was observed for milk fat yield and content (1.39 ± 0.075 kg/d and 4.51 ± 0.219%) or milk protein yield and content (1.06 ± 0.041 kg/d and 3.43 ± 0.096%). Total methane production quadratically decreased from CNTRL to MdLL then increased to HiLL (441, 389, 412 ± 18.2 L/d, respectively). No differences were observed on total-tract digestibility of DM (averaging 67.2 ± 0.55%) and NDF (averaging 50.9 ± 1.56%). No difference was observed in the concentration of DE, ME or NEL was observed averaging 2.82 ± 0.021, 2.51 ± 0.027, and 1.72 ± 0.030 Mcal/kg respectively. Our results suggest that replacing CON alfalfa with LoL alfalfa has no effects on milk production, milk composition, or nutrient digestibility but may improve feed efficiency.

Scaling-up fungal pretreatment of lignocellulose biomass: Impact on nutritional value, ruminal degradability, methane production, and performance of lactating dairy cows

Scaling-up fungal pretreatment of lignocellulose biomass (LCB) for ruminant nutrition has become a major research challenge in recent years. This study systematically investigated the effectiveness of fungal (Pleurotus ostreatus) pretreatment (for 30 days under solid state fermentation (SSF)) of large quantities (8400 kg) of lime-pasteurized wheat straw, in terms of improvement in nutritional value, in vitro ruminal fermentation characteristics and methane (CH4) production potential. We further investigated the effects of stepwise replacement of untreated wheat straw (UTWS) with the lime pasteurized P. ostreatus treated wheat straw (PTWS) on dry matter intake (DMI), apparent total tract digestibility, production performance, CH4 emission and feed efficiency of lactating dairy cows. The results revealed that PTWS had lower lignin (P< 0.001), hemicellulose (P< 0.001) and cellulose (P< 0.05) contents and higher crude protein (CP; P< 0.001) content and cellulose to lignin ratio (P< 0.01), as compared to UTWS. The PTWS had higher in vitro DM digestibility (IVDMD; P< 0.001), total gas production (IVGP; P< 0.01), total volatile fatty acids (VFAs, P< 0.01) and propionate (P< 0.05) concentration, and lower (P< 0.05) pH and CH4 gas production during 72 h in vitro fermentation. Notably, the fungus degraded 33.3 % lignin at the expense of 6.56 % cellulose, and markedly increased CP content (46.3 %), IVDMD (20.2 %), IVGP (16.8 %) and VFAs (10.0 %) production, and decreased CH4 production (10.3 %). The aflatoxin B1 concentration of PTWS was <5.0 µg/kg, and mycelium concentration was 181.9 mg/kg DM, reflecting safe and effective tretment of the straw. Replacement of 32 % UTWS in total mixed ration with the PTWS, increased DMI (0.84 kg/day; P = 0.01), apparent total tract DM digestibility (5.5 g/100 g; P< 0.05) and milk yield (1.17 liter/day; P= 0.032), and decreased CH4 emission (1.45 g/kg DMI; P< 0.05). In conclusion, hydrated lime can replace traditional high-tech pasteurization methods for the fungal pretreatment of LCB, and present prospects for scaling up the process for ruminant nutrition.

Supplementing flaxseed meal with sucrose, flaxseed oil, or both: Effects 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 yield, diversity, and relative abundance of ruminal bacterial taxa, ruminal fermentation profile, production performance, milk fatty acids (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 the following (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 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.

Effects of the palmitic-to-oleic ratio in the form of calcium salts of fatty acids on the production and digestibility in high-yielding dairy cows

The form of fat supplements, degree of saturation, and the fatty acid (FA) profile influence cows' production response. The objective was to determine the effects of supplemental fats in the form of calcium salts (CS) of FA (CSFA) with different ratios between palmitic (PA) and oleic (OA) acids on nutrient digestibility and cow performance. Forty-two dairy cows were assigned to 3 groups and fed (for 13 wk) rations that contained 2.2% CSFA (on a DM basis) with increasing PA-to-OA ratios as follows: (1) CS45:35, 45% PA and 35% OA; (2) CS60:30, 60% PA and 30% OA; and (3) CS70:20, 70% PA and 20% OA. Rumen and fecal samples were taken for VFA and digestibility measurements, respectively. Increasing the PA-to-OA ratio linearly decreased the milk and ECM yields, whereas a quadratic effect was observed for milk fat concentration (3.55%, 3.94%, and 3.87% in the CS45:35, CS60:30, and CS70:20 groups, respectively) and fat yield. Dry matter intake was highest in the CS60:30 group (33.7 kg/d) and lowest in the CS70:20 group (31.6 kg/d), and a tendency of quadratic effect was observed for calculated energy balance with no difference in BW gain among the groups. The milk-to-DMI ratio was decreased, and the ratio of ECM-to-DMI tended to decrease when the PA-to-OA ratio increased. The highest apparent total-tract digestibilities of DM, OM, and protein were observed in the CS60:30 cows, and NDF tended to decrease with increasing PA-to-OA ratio; however, digestibility of the total FA and FA subgroups (16- and 18-carbon FA) were not different among groups. Across treatments, the 18-carbon FA digestibility was higher than the 16-carbon FA digestibility. Under the current study conditions, the CS60:30 cows had the highest fat concentration and fat yield; energy output in milk; DMI; and digestibility of DM, OM, and protein. However, further research is required to fine tune the optimal FA ratio in supplemental fat sources to maximize production and efficiency under various conditions, such as production level, stage of lactation, and diet composition.

Effectiveness of near-infrared spectroscopy to predict the chemical composition of feces and total-tract apparent nutrients digestibility estimated with undigestible neutral detergent fiber or acid-insoluble ash in lactating buffaloes' feces

Following a comparison of nutrient total-tract digestibility estimates in lactating buffaloes using single-point undigestible NDF (uNDF) or acid-insoluble ash (AIA) as internal markers, the potential of fecal near-infrared spectroscopy (NIRS) to provide calibration equations for the assessment of the chemical composition of feces and nutrient total-tract digestibility estimated with internal markers was explored. Chemical analyses were performed on 147 fecal samples from lactating buffaloes reared on 5 farms in central Italy (Naples). Each farm fed a silage-based TMR to the buffaloes, and the TMR was sampled in the 2 d before the fecal collection. The TMR and individual fecal samples were collected and analyzed for DM, OM, ash, AIA, ether extract (EE), starch, fiber fractions (amylase-treated NDF without residual ash [aNDFom], amylase-treated NDF inclusive of residual ash [aNDF], ADF without residual ash [ADFom], ADF, hemicellulose, cellulose, ADL, uNDF), N, CP and CP bound to aNDF (NDICP) and to ADF (ADICP). The uNDF content was determined through a 240-h in vitro fermentation and employed, together with AIA as markers, to estimate the total-tract apparent digestibility and total-tract digestibility of DM, OM, ash, N, CP, EE, aNDFom, aNDF, NDIP, ADFom, and ADF, ADIN, ADL, hemicellulose, cellulose, starch, NFC, and the B3 fraction of N (NB3). No correlation was found between DM and OM digestibility estimated with AIA and uNDF as internal markers. Weak correlations were detected for all the other nutients digestibilities, and strong correlations were observed for EE, ADFom, hemicellulose, NDIN, ADIN, NB3, NFC, and starch. The sample set (n = 147) was divided in a calibration set (n = 111) and a validation set (n = 36) to "train" and "validate" the fecal NIRS curve through an external validation process. An estimation usable for preliminary or initial evaluation was obtained for N, CP, and aNDF fecal content. An excellent prediction was obtained for total tract digestibility of ADIN (R2 = 0.90) when estimated with uNDF as the internal marker. The NIRS technology was not able to accurately predict all the other traits and the estimated nutrient digestibility of lactating buffalo diets from fecal spectra.

The Effects of Harvest Maturity of Eragrostis tef 'Moxie' Hay and Supplemental Energy Source on Forage Utilization in Beef Heifers.

The phenological stage of maturity of grasses and supplementation program can impact forage utilization in grazing beef cattle. However, the potential interaction between harvest maturity of Eragrostis tef (teff) hay and energy supplement source was yet to be fully evaluated. Therefore, our objective was to determine the effects of harvest maturity of teff hay and supplemental energy sources on nutrient intake, apparent total-tract nutrient digestion, nitrogen (N) utilization, and ruminal fermentation characteristics in beef heifers. A split-plot design with teff hay harvest maturity as the whole plot and supplemental energy source as the subplot was administered in a three-period (21 d), three × three Latin square design. Six crossbred beef heifers (804 ± 53.6 kg of body weight; BW) were allocated to two harvest maturities (early- (EH]) or late-heading (LH)) and to two supplemental energy sources (no supplement (CON), or rolled corn grain or beet pulp pellet fed at 0.5% of BW). Data were analyzed using SAS. There was no harvest maturity × energy supplement interaction. Although harvest maturity had no impact on total dry matter intake (DMI), crude protein (CP) intake was greater (p < 0.01) for EH than LH heifers. Total intakes of dry (DM) and organic matter (OM) were also greater (p < 0.01) for supplemented than CON heifers, whereas acid detergent fiber (ADF) intake was greater for beet pulp heifers compared to heifers fed the CON diet and supplemental corn grain. Harvest maturity had no impact on ruminal pH. However, mean ruminal pH was lower (p = 0.04), duration pH < 6.2, and molar proportions of butyrate and branched-chain fatty acids were greater (p ≤ 0.049) for heifers fed corn grain compared to CON and beet pulp diets. Heifers fed EH hay had greater (p ≤ 0.02) apparent total-tract DM, OM, CP, NDF, and ADF digestibility than heifers fed LH hay. Although there was no supplemental energy effect on microbial nitrogen (N) flow, it was greater (p < 0.01) for EH than LH heifers. Apparent N retention, which did not differ, was negative across all diets. In summary, delaying the harvest of teff hay from the EH to LH stage of maturity compromised nutrient supply, which was not attenuated by feeding supplemental corn grain and beet pulp at 0.5% of diet DM. Because N retention was negative across harvest maturity, there might be a need to provide both energy and protein supplements to improve growth performance when feeding teff hay to beef cattle.

Enteric methane emission of dairy cows supplemented with iodoform in a dose–response study

Enteric methane (CH4) emission is one of the major greenhouse gasses originating from cattle. Iodoform has in studies been found to be a potent mitigator of rumen CH4 formation in vitro. This study aimed to quantify potential of iodoform as an anti-methanogenic feed additive for dairy cows and investigate effects on feed intake, milk production, feed digestibility, rumen microbiome, and animal health indicators. The experiment was conducted as a 4 × 4 Latin square design using four lactating rumen, duodenal, and ileal cannulated Danish Holstein dairy cows. The treatments consisted of four different doses of iodoform (1) 0 mg/day, (2) 320 mg/day, (3) 640 mg/day, and (4) 800 mg/day. Iodoform was supplemented intra-ruminally twice daily. Each period consisted of 7-days of adaptation, 3-days of digesta and blood sampling, and 4-days of gas exchange measurements using respiration chambers. Milk yield and dry matter intake (DMI) were recorded daily. Rumen samples were collected for microbial analyses and investigated for fermentation parameters. Blood was sampled and analyzed for metabolic and health status indicators. Dry matter intake and milk production decreased linearly by maximum of 48% and 33%, respectively, with increasing dose. Methane yield (g CH4/kg DMI) decreased by maximum of 66%, while up to 125-fold increases were observed in hydrogen yield (g H2/kg DMI) with increasing dose of iodoform. Total tract digestibility of DM, OM, CP, C, NDF, and starch were unaffected by treatments, but large shifts, except for NDF, were observed for ruminal to small intestinal digestion of the nutrients. Some indicators of disturbed rumen microbial activity and fermentation dynamics were observed with increasing dose, but total number of ruminal bacteria was unaffected by treatment. Serum and plasma biomarkers did not indicate negative effects of iodoform on cow health. In conclusion, iodoform was a potent mitigator of CH4 emission. However, DMI and milk production were negatively affected and associated with indications of depressed ruminal fermentation. Future studies might reveal if depression of milk yield and feed intake can be avoided if iodoform is continuously administered by mixing it into a total mixed ration.

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.

A newly developed strain of Enterococcus faecium isolated from fresh dairy products to be used as a probiotic in lactating Holstein cows.

The objective of this study was to determine the ability of an isolated strain (EGY_NRC1) or commercial (NCIMB 11181) Enterococcus faecium as a probiotic for lactating cows. Two experiments were conducted: In Experiment 1, the effects of three levels (1, 2, and 3 g/kg diet, DM basis) of isolated and commercial E. faecium on in vitro ruminal fermentation kinetics, gas, methane (CH4) and nutrient degradability were determined. In Experiment 2, thirty multiparous Holstein cows (633 ± 25.4 kg body weight) with 7 days in milk, were randomly assigned to 3 treatments in a completely randomized design in a 60-day experiment. Cows were fed without any additives (control treatment) or supplemented with 2 g/kg feed daily of E. faecium EGY_NRC1 (contain 1.1 × 109 CFU/g) or commercial E. faecium NCIMB 11181 (contain 2 × 1012 CFU/g). Diets were prepared to meet cow's nutrient requirements according to NRC recommendations. Probiotic doses were based on the in vitro Experiment 1. Feed intake, digestibility, blood parameters and lactation performance were evaluated. In Experiment 1, the isolated E. faecium linearly and quadratically increased (P < 0.001) in vitro total gas production (TGP), the degradability of dry matter (dDM) and organic matter (dOM) while decreased (P < 0.05) methane (CH4) percent of TGP, NH3CH4 production, and pH. The commercial E. faecium increased TGP and decreased (P < 0.01) CH4 production, pH and increased the dDM and dOM, short chain fatty acids and ruminal NH3-N concentration. In Experiment 2, the isolated E. faecium increased (P < 0.01) total tract digestibility of DM, neutral and acid detergent fiber, daily milk production and feed efficiency compared to the control treatment without affecting feed intake and milk composition. Moreover, the isolated E. faecium increased (P < 0.05) the proportion of C18:1 trans-9, C18:2 cis-9-12 and C18:2 trans-10 cis-12. Both isolated and commercial E. faecium improved (P < 0.01) organic matter, crude protein and nonstructural carbohydrates digestibility, increased serum glucose (P = 0.002) and decreased serum cholesterol (P = 0.002). Additionally, both E. faecium strains decreased C23:0 (P = 0.005) in milk. In conclusion, the use of E. faecium (isolated and commercial) at 2 g/kg DM of feed improved feed efficiency and production performance, with superior effects on animal performance from isolated E. faecium compared to the commercial one.

PSVIII-17 Nutrient Digestibility of Beef Steers Consuming Finishing Diets with an Added Nutritional Packet in a Calf-fed System

Abstract The effects of a nutritional packet containing a direct-fed microbial combined with vitamins/electrolytes offered to beef steers in a calf-fed system on apparent total tract nutrient digestibility were evaluated. Angus crossbred steer-calves (n = 60; BW = 234 ± 4 kg) were assigned to a randomized complete block design (block = body weight; steer = experimental unit) and stratified into 2 treatments: a) control (no packet, finely-ground corn carrier only); and b) 30 g of DM/animal-daily of a nutritional packet [live-yeast (Saccharomyces cerevisiae; 8.7 Log CFU/g), Vitamin C (5.4 g/kg of Ascorbic acid), Vitamin B1 (13.33 g/kg of Thiamine hydrochloride), and electrolytes of NaCl (80 g/kg) and KCl (80 g/kg)]. Animals were individually offered [electronic feed-bunks (Smart-Feed/C-Lock Inc.)] a steam-flaked corn-based finishing diet ad libitum, once daily for 233 d. Treatments were offered during the first (phase-1) and last (phase-2) 60 d on feed. At the conclusion of each phase, feed samples were collected once daily (1400 h), while fecal samples twice daily (0700 and 1700 h) from each steer during 4 consecutive days. Fecal and feed sample composites were dehydrated (55oC), ground (1 mm), and analyzed to assess DM, OM, NDF, ADF, and hemicellulose. The 288-h indigestible NDF was used as dietary internal marker to estimate fecal output and used to calculate nutrient digestibility. Data were analyzed using the GLIMMIX procedure of SAS. Intake of DM, OM, and fiber components during both digestibility trials were not affected (P ≥ 0.56) by treatments. Steers offered the nutritional packet had increased (P &amp;lt; 0.01) apparent total tract digestibility of DM, OM, NDF, ADF, and hemicellulose by at least 2.4, 2.4, 8.3, 10, and 7.5%, respectively, in both digestibility phases. Superior nutrient digestibility without affecting nutrient intake may justify a potential enhanced carcass energy deposition.

Feeding corn germ instead of corn grain on the performance of Holstein dairy cows fed low-forage diet and human-edible feed conversion efficiency

Using corn germ (CG) instead of corn grain could maintain dairy cow performance and might increase the efficiency of human food production. The primary objective of this study was to evaluate the effects of replacing corn grain with CG on the performance, nutrient intake, and digestibility of dairy cows. It also aimed to investigate the effect of CG on the efficiency of human food production in high-producing Holstein dairy cows in early lactation. Nine multiparous Holstein cows with 65.6 ± 8.5 DIM, milk yield of 55.6 ± 4.5 kg/d, and body weight of 611.3 ± 43.3 kg (mean ± SD) were used in a 3 × 3 Latin square design with 21-d periods. Treatments were (1) control treatment (CT, diet contains corn grain), (2) alternative treatment (AT, diet where corn grain was replaced with CG), and (3) balanced treatment (BT, diet where corn grain was replaced with CG but with the same energy content as CT). Control and balanced diets were isoenergetic (6.61 MJ/kg of DM); however, AT had higher energy (6.77 MJ/kg of DM). Treatments had no effect on dry and organic matter intake. NDF intake, however, was higher in CG diets compared with CT (P = 0.0001). Total-tract digestibility of DM tended to be reduced (P = 0.08), and OM digestibility was reduced (P = 0.05) by the inclusion of CG in diets. Whole and energy-corrected milk production were greater in AT compared with CT and BT (P < 0.05). Milk yield was similar in cows fed CT and BT. Treatments had no effect on milk composition or feed efficiency. Diet CT, when compared with CG diets, had lower efficiency in terms of human-edible feed conversion efficiency (HeFCE) and net food production (P < 0.05). Diet BT had greater HeFCE and net production of human-edible CP than AT (P < 0.05). Plasma BHBA, non-esterified fatty acids, and glucose concentrations were not affected by treatments, but plasma cholesterol was higher in cows that consumed CG diets (P = 0.04). The results indicate that, in high-producing early lactation dairy cows fed high concentrate diets, net food protein production can be substantially improved without lowering milk production through the reduction of dietary starch from 30.2 to 24.8% by replacing corn grain with CG.

Intake, ruminal fermentation parameters, and apparent total-tract digestibility by beef steers consuming Pensacola bahiagrass hay treated with calcium oxide.

To determine the effect of CaO-treated Pensacola bahiagrass (Paspalum notatum) hay on intake, ruminal fermentation parameters, and apparent total-tract digestibility of nutrients, nine ruminally cannulated Angus-crossbred steers were used in a triplicated 3×3 Latin square design. Steers had ad libitum access to either 1) untreated dry hay (DH; n = 8); 2) hay at 50% DM treated with 8.9% CaCO3 (dry matter [DM] basis; CC; n = 9); or 3) hay at 50% DM treated with 5% CaO (DM basis; CO; n = 8). Water was added to reach 50% DM in the CC and CO diets. Ruminal fluid and blood samples were collected every 3h for 24h. Ruminal fluid was analyzed for pH, volatile fatty acids (VFA), and ammonia-nitrogen (NH3-N). Blood was analyzed for plasma urea nitrogen (PUN). Hay and fecal samples were collected for 4 d, four times daily for hay and twice daily for feces, to determine apparent total-tract digestibility of nutrients. The hay provided to steers during the digestibility period was analyzed for in vitro organic matter digestibility (IVOMD) for 48h. Data were analyzed as repeated measures for blood and ruminal fermentation parameters. Total DM intake was not affected (P ≥ 0.674) by treatment. A treatment effect (P < 0.001) was observed for average ruminal pH, where steers consuming CO had the greatest pH (P < 0.001). Ruminal concentration of NH3-N tended (P = 0.059) to be reduced in steers consuming CO. There was a treatment × time interaction (P = 0.023) on concentrations of PUN, where at 3h DH and CO were lesser than CC (P ≤ 0.050) and at 21h DH was lesser than CC (P = 0.020). Total VFA, acetate, propionate, butyrate, branched-chain VFA, and valerate concentrations were affected by treatment (P ≤ 0.035), where a reduction (P ≤ 0.034) occurred in steers consuming CO. No treatment differences were observed for total-tract digestibility of DM (P = 0.186), organic matter (P = 0.169), or crude protein (P = 0.152); however, steers consuming DH had greater neutral detergent fiber (P = 0.038) than CC and tended to be greater than CO (P = 0.082). The CO hay had greater (P = 0.005) IVOMD compared with DH and tended (P = 0.100) to be greater than CC. Bahiagrass hay treated with CaO may reduce ruminal fermentation, as indicated by decreased total VFA concentration without altering DM intake. The addition of CaO did not improve the digestibility of bahiagrass hay in vivo; however, in vitro results are contradictory and warrant further elucidation.

339 Effects of a Blend of Mannan and Glucan on Growth Performance and Immunocompetence of Newly Weaned Beef Steers

Abstract We examined the effects of dietary supplementation of a blend of mannan and glucan on the growth performance, diet digestibility, and whole-blood immune gene expression of newly weaned beef steers during a 42-d receiving period. Forty-eight newly weaned Angus crossbred steers (2 d post-weaning; 199 ± 13 kg of initial BW) were randomly assigned to 1 of 2 treatments: basal diet with no additive (CON; n = 24) or a basal diet top-dressed with 5 g of a blend of mannan and glucan (MANGLU; n = 24). Average daily gain (ADG) was calculated from weekly BW. Blood samples were collected on days 0, 14, and 42 for measurement of plasma glucose and NEFA. Expression of 84 immune-related genes was analyzed on blood samples collected on day 42. Beginning on days 37 to 42, total mixed ration, refusals, and fecal samples were collected once daily to determine apparent total tract digestibility of DM, CP, NDF, and ADF using indigestible NDF as an internal marker. Immune gene expression data was analyzed using a GeneGlobe Data Analysis Center. All other data were analyzed as a randomized complete block design using the GLIMMIX procedure of SAS. Over the 42-d feeding trial, MANGLU tended to increase final BW (P = 0.07) and ADG (P = 0.06). Compared to CON, beef steers fed supplemental MANGLU had greater DM digestibility (P = 0.03) and tended to have greater NDF digestibility (P = 0.09). No treatment effects (P &amp;gt; 0.10) on plasma glucose and NEFA on d 14 and 42 were detected. Compared with CON, MANGLU increased (P ≤ 0.05) the expression of five immune-related genes involved in recognition of and mounting immune defense against microbial pathogens. In conclusion, this study demonstrated that supplemental MANGLU enhances beef cattle immunocompetence and productivity during feedlot receiving period.

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.

Effects of single or combined supplementation of probiotics and prebiotics on ruminal fermentation, ruminal bacteria and total tract digestion in lambs

Probiotics (beneficial living microorganisms) and prebiotics (fiber, cell wall material, mannan polysaccharides derived through hydrolysis of yeast cell walls) are feed additives that may have beneficial extra-nutritional pharmaceutical and/or metabolic effects on livestock health and growth performance. Due to differences in modes of action, their combination may have additive effects on digestion and fermentation in ruminants. For this reason, four male lambs (Dorper; 45.1 ± 2.7 kg initial weight) with “T” cannulas in the rumen were used in a 4 × 4 Latin square experiment to evaluate the effects of single or combined supplementation of probiotics and prebiotics on ruminal fermentation and total tract digestion. Dietary treatments consisted of a cracked corn-based basal finishing diet supplemented with: 1) no eubiotics (Control); 2) 3 g of live saccharomyces cerevisiae /lamb/day (2 × 1010 cfu/g, SC), 3) 3 g of mannan oligosaccharide (30 % w/w) plus b-glucans (20 % w/w) /lamb/day (MOS), and 4) combination of 1.5 g/day SC and 1.5 g/day MOS (SCMOS). Compared to controls, SC supplementation tended (P = 0.09) to increase total tract digestion of DM and OM, and increased (P < 0.05) total tract digestion of N, starch, and digestible energy (DE). Compared with Control, MOS increased total tract NDF (7.9 %, P < 0.01) and starch digestion, and tended to improve total tract digestion of (P = 0.09), N (P = 0.07), and DE diet (P = 0.07). Compared to Control, SCMOS increased (P ≤ 0.03) total tract digestion of all fractions evaluated, including a 4.2 % (P < 0.01) increase in DE. Although lambs fed MOS had greater (6.7 %, P = 0.02) NDF digestion than those fed SC, differences in total tract digestion of DM, OM, N, starch and DE diet were not appreciable (P ≥ 0.24). Compared with SC and MOS fed separately, SCMOS increased (P < 0.05) total tract digestion of N and NDF. Supplemental MOS and SCMOS tended (P = 0.09) to promote greater ruminal pH than the Control. Combining supplementation decreased (P ≤ 0.03) the molar proportion of butyrate and ruminal ammonia, consistent with decreased of ruminal concentration of C. aminophilum. Probiotic/prebiotic supplementation of high-energy lamb finishing diets enhances total tract digestion and digestible energy. Reduction hyper-ammonia producing ruminal bacteria with the combination probiotic plus prebiotic may contribute to improved dietary N economy. The combination of probiotics with prebiotics potentiate positive effects on digestion and ruminal fermentation in lambs fed a high-energy diets.

Comparative effect of Volvariella volvacea-treated rice straw and purple corn stover fed at different levels on predicted methane production and milk fatty acid profiles in tropical dairy cows

The objective of this study was to determine the effect of different concentrations of rice straw (RS) and purple corn stover (PCS) treated with Volvariella volvacea fed in total mixed rations (TMR) on ruminal fermentation, blood metabolites, calculated methane (CH4) production, and milk fatty acid profile in mid-lactation crossbred Holstein Friesian cows. The experimental design was a 2 × 2 factorial arrangement of treatments in a 4 × 4 Latin square design. Factor A included roughage type (V. volvacea-treated RS and V. volvacea-treated PCS), and Factor B included roughage (R)-to-concentrate (C) ratio (R:C) (50:50 and 60:40). The four dietary treatment combinations were 1) RS with an R:C ratio of 50:50 (RS50); 2) RS with an R:C ratio of 60:40 (RS60); 3) PCS with an R:C ratio of 50:50 (PCS50); and 4) PCS with an R:C ratio of 60:40 (PCS60). Different roughage sources did not alter total tract digestibility of DM, OM, and NDF (P > 0.05), but PCS increased NDF digestibility by 4.6 percentage units and CP digestibility by 15.6 percentage units. Roughage types influenced rumen propionic acid (C3) concentration 4 h after feeding with PCA increasing higher C3 concentration compared to RS at both R:C ratios. There was no interaction between roughage types and the R:C ratio for CH4 emission calculated based on volatile fatty acid profiles. However, roughage type impacted CH4 emission. Calculated CH4 concentration was lower in PCS than RS. Changing the R:C ratio did not alter milk production, milk composition, or somatic cell count (SCC). Moreover, roughage type did not influence milk production and milk composition, except for SCC which was lower in PCS. Roughage type and the R:C ratio independently influenced milk fat arachidonic acid (C20:4n-6) concentration. Furthermore, the PCS group had higher conjugated linoleic acid (CLA) than the RS groups. The proportion of total C18:0 and cis-9 C18:1 in milk fat increased 10% with the feeding of PCS50 and PCS60. However, milk cis-9, trans-11 C18:2 increased by 61% in the PCS group (P < 0.01). In conclusion, PCS increased rumen C3 and milk fat CLA and arachidonic acid concentration and decreased CH4 production compared to the RS. The PCS treated with V. volvacea could be used for up to 60% of TMR for dairy cows.

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.

53 Relationships Between Fecal Characteristics, Ruminal Ph, Intake and Digestion in Feedlot Cattle

Abstract The objectives were to: 1) determine the relationship of fecal characteristics with ruminal pH, dry matter intake (DMI) and dry matter digestion and 2) determine the ability of fecal characteristics to predict ruminal pH, DMI, and dry matter digestion. Data were collected in two metabolism studies using eighteen ruminally cannulated steers (n = 36). Each study was a completely randomized design evaluating the effect of a direct-fed microbial during an acidosis challenge. Ruminal pH, DMI, total tract DM digestion and fecal characteristics (fecal pH, washed fecal particle size and mucin casts) were measured for 4 d after the acidosis challenge. Rumen pH was not correlated (P ≥ 0.15) with mucin cast score or mean fecal particle size but was negatively associated with fecal pH (r = -0.42; P &amp;lt; 0.01). Total tract DM digestion was correlated (r ≥ 0.53; P ≤ 0.02) to fecal pH and fecal particle sizes between 1180 and 2360 µm. Dry matter intake was correlated (r ≥ 0.41; P &amp;lt; 0.01) to mean fecal particle size and fecal particle sizes between 2360 and 4750 µm. Multiple regressions were performed with the GLMSELECT procedure of SAS 9.4 using stepwise selection. Ruminal pH was best predicted (r2 = 0.20) by fecal pH and fecal particle size between 1400 and 1700 µm. Total tract DM digestion was best predicted (r2 = 0.92) by fecal pH, mucin cast score, and fecal particle size between 3350 and 1700 µm. Dry matter intake was best predicted (r2 = 0.51) by mean fecal particle size, fecal pH and fecal particle size between 1400 and 850 µm. Overall, results indicated fecal pH was correlated to ruminal pH and total tract DM digestion. Fecal characteristics including washed particle size can also predict total tract DM digestion in feedlot cattle.

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.

279 Evaluation of Green Grass Inclusion on Digestibility and Fatty Acid Flow in Finishing Diets of Beef Cattle

Abstract Six ruminally and duodenally cannulated steers were utilized in a 3 × 3 replicated Latin square experiment to determine duodenal fatty acid (FA) flow. Treatments consisted of 3 levels of Green Grass (GG, Sunseo Omega 3; Chungcheong Duk-Do, South Korea), a feed comprised of sesame meal, giant kelp, cassava, and sorghum, at 0, 15, and 30% of diet DM. Data were analyzed using the MIXED procedure of SAS with treatment and period as fixed effects and animal as a random effect. There were no differences in DMI, organic matter (OM) intake, total tract DM or OM digestibility (P ≥ 0.16). Intake of NDF and ADF increased linearly (P &amp;lt; 0.01) from 0 to 30% GG inclusion. Total tract digestibility of NDF was the poorest (P ≤ 0.02) for GG0 with no differences between GG30 and GG15 (P = 0.33). Total tract ADF digestibility was poorest for GG30 (P &amp;lt; 0.01) while GG0 and GG15 were not different (P = 0.17). Fatty Acid values were reported as relative abundance of the total FA present in duodenal samples. The lowest (P &amp;lt; 0.01) concentration of saturated FA was GG30 (70.3%) while GG0 and GG15 were not different (P = 0.83; 78.2%). The concentration of unsaturated, mono-unsaturated, poly-unsaturated, and trans FA responded quadratically (P &amp;lt; 0.01) with no difference between GG0 and GG15 and increasing to GG30. Omega-6 FA tended to decrease linearly (P = 0.06) from 0 to 30% GG inclusion (4.91 and 3.85 g/d, respectively). Omega-3 FA increased linearly (P &amp;lt; 0.01) from 0 to 30% GG inclusion (1.84 and 10.78 g/d, respectively). These data suggest increasing inclusion of GG up to 30% of diet DM does not affect DM or OM digestibility. Greater inclusions of GG resulted in more unsaturated and omega-3 FA concentrations in the duodenum.