Apparent Total Tract Digestibility Of Nutrients Research Articles

Asparagopsis taxiformis inclusion in grass silage-based diets fed to Norwegian red dairy cows: Effects on ruminal fermentation, milk yield, and enteric methane emission

Efforts to mitigate enteric methane (CH4) emission from ruminants by using the red macroalgae Asparagopsis taxiformis (AT) have demonstrated promising results both in vitro and in vivo. We assessed the effects of wild harvested and freeze-dried AT inclusion in the grass silage-based diets of Norwegian Red dairy cows on feed intake, milk yield and composition, rumen fermentation and CH4 emission. Fifteen (9 rumen cannulated and 6 intact) multiparous cows with an average (±SD) covariate period milk yield (MY) of 33.0 (3.8) kg/day were used in the experiment. The cows were divided into three groups (n = 5) after blocking for cannulation, and initial MY. After feeding on a common diet for 21 days (i.e., Covariate period), the groups were randomly allocated to three treatments: Control (no seaweed), 0.125%AT (Control + 0.125%AT, on organic matter (OM) basis) and 0.25%AT (Control + 0.25%AT, on OM basis). The cows were adapted to their diets for 13 days, followed by 39 experimental days for data collection. Inclusion of AT at 0.125% level did not affect dry matter intake (DMI, kg/d) but signicantly reduced both MY and energy corrected milk yield (ECM, kg/d) (P < 0.05) with a tendency for lower CH4 production (g/d) relative to the control group. Dry matter intake, ECM and CH4 production were reduced (P < 0.05) by 0.25%AT inclusion relative to the Control group. Apparent total tract nutrient digestibility (%), ECM per kg DMI, CH4 yield (g CH4/kg DMI) and CH4 intensity (g CH4/kg ECM) were not affected by AT inclusion. Inclusion of AT, at both levels, significantly reduced (P < 0.05) ruminal fluid total short chain fatty acids and molar proportions of actate, while increasing (P < 0.05) the molar proportion of propionate and isovalerate. Inclusion of AT decreased contents (%) of milk fat (P = 0.018) and protein (P = 0.010) resulting in significanly lower fat and protein yields. Lactose content (%) was higher for the AT groups (P = 0.021) but this did not compensate for lower MY resulting in lower milk lactose yield. Milk iodine content increased in a dose dependent manner with AT inclusion. In conclusion, AT inclusion at 0.25% level reduced CH4 emission from dairy cows with a grass silage-based diets. However, the reduced DMI for the 0.25%AT group along with reduced MY and elevated milk iodine content for both AT groups, for this particular harvest of AT, would suggest possible constraints for large scale inclusion of AT in dairy cow production.

Feeding live or inactive yeast to primiparous Jersey cows: nutrient digestibility, rumen fermentation, and milk fatty acid profile

ABSTRACT The aim of this study was to evaluate the effects of live yeast (LY) or inactive yeast (IY) on intake and apparent total-tract digestibility of nutrients, ruminal fermentation, milk yield and composition, milk fatty acid profile, N utilisation, and microbial protein synthesis of primiparous Jersey cows. Twelve primiparous Jersey cows were employed, with an average body weight of 403 kg, a lactation period of 100 days, and average daily milk output of 14.7 kg. The experimental diets were: 1 – CON (no additives); 2 – LY (inclusion of 40 g/day of live yeast); 3 – IY (inclusion of 40 g/day of inactivated yeast wall). Cows fed LY exhibited the greatest DM intake. Cows’ intake IY had the greatest digestibility of DM, OM, and NDF. Feeding IY reduced ruminal concentrations of acetate, isobutyrate, and branched-chain fatty acids. Cows fed either LY or IY increased the production of milk and FCM. Cows under the LY treatment had greater milk fat content. Cows fed LY had the greatest N intake. Yeast treatments also increased the absorbable purine estimation. Supplementing primiparous dairy cows with yeast products, especially live yeast, improved dry matter intake by positively influencing digestibility, particularly for starch and NDF.

Dietary supplementation with live or autolyzed yeast: Effects on performance, nutrient digestibility, and ruminal fermentation in dairy cows

This study was conducted to evaluate the effects of live or autolyzed yeast supplementation on dairy cow performance and ruminal fermentation. Two experiments were conducted to evaluate performance, feed sorting, total-tract apparent digestibility of nutrients, purine derivatives excretion, N utilization, ruminal fermentation, and abundance of specific bacterial groups in the rumen. In Exp. 1, 39 Holstein cows (171 ± 40 d in milk and 32.6 ± 5.4 kg/d milk yield) were blocked according to parity, days in milk, and milk yield and randomly assigned to the following treatments: Control (CON); autolyzed yeast (AY) fed at 0.625 g/kg DM (Levabon, dsm-firmenich); or live yeast (LY) fed at 0.125 g/kg DM (Vistacell, AB Vista). Cows were submitted to a 2-wk adaptation period followed by a 9-wk trial. In Exp. 2, 8 ruminal cannulated Holstein cows (28.4 ± 4.0 kg/d milk yield and 216 ± 30 d in milk), of which 4 multiparous and 4 primiparous, were blocked according to parity and enrolled into a 4 × 4 Latin square experiment with 21 d-periods (the last 7 d for sampling). Cows within block were randomly assigned to treatments sequences: control (CON2); live yeast (LY) using the same product and dietary concentration as described in Exp. 1; or autolyzed yeast fed at 0.625 g/kg DM (AY) or 0.834 g/kg DM (AY2). In Exp. 1 and 2, nutrient intake and total-tract apparent digestibility were not affected by treatments. Sorting for long feed particles (>19 mm) tended to be greater in cows fed yeast supplements than CON in Exp.1. Efficiency of N conversion into milk N was increased when feeding yeast supplements in Exp. 1. 3.5% Fat-corrected milk yield tended to be greater in cows fed yeast supplements than CON. Feed efficiency was increased when yeast supplements were fed to cows in relation to CON in Exp. 1. In Exp. 2, yield of fat-corrected milk and fat were greater in cows fed yeast supplements compared with CON2. Uric acid concentration and output in urine were increased when feeding yeast supplements when compared with CON2. Neither ruminal pH nor total volatile fatty acids were influenced by treatments. The current study did not reveal treatment differences in ruminal abundance of Anaerovibrio lipolytica, genus Butyrivibrio, Fibrobacter succinogenes, Butyrivibrio proteoclasticus, or Streptococcus bovis. Yeast supplementation can increase feed efficiency without affecting nutrient intake and digestibility, ruminal volatile fatty acid concentration, or ruminal abundance of specific bacterial groups. Supplementing live or autolyzed yeast, regardless of the dose, resulted in similar performance.

Effects of increasing dose of a hybrid bacterial 6-phytase on apparent total tract nutrient digestibility, release of free myoinositol, and retention of calcium and phosphorus, and growth performance of pigs

The objective of this study was to investigate the effects of increasing doses of a hybrid bacterial 6-phytase on apparent total tract digestibility (ATTD) of energy and nutrients, plasma level of free myoinositol, retention of calcium (Ca) and phosphorus (P), and growth performance of growing pigs fed Ca and P deficient diets. A total of 15 barrows [21.5 ± 1.4 kg BW; Duroc × (Landrace × Yorkshire)] were allotted to a triplicated 5 × 5 Latin square design with 5 dietary treatments and 5 periods per each square. Pigs were individually housed in a metabolism crate. Five dietary treatments consisted of 5 levels of phytase (0, 500, 1000, 1500, and 2000 FTU/kg) supplemented to a basal diet containing nutrients meeting the requirement except for Ca and P. The basal diet was deficient in total Ca and P by 2.2 and 1.7 g/kg below the recommendations from NRC, respectively. Data were analyzed using orthogonal polynomial contrasts using Proc MIXED of SAS and the optimal phytase levels were determined by a broken line analysis using Proc NLMIXED. Increasing phytase supplementation increased (linear: P < 0.01; quadratic: P < 0.01) ATTD of Ca and P and retention of Ca and P. Increasing phytase supplementation increased (linear: P < 0.05; quadratic: P < 0.05) myoinositol contents in plasma. Based on broken line analyses, ATTD of Ca and retention of Ca were increased until phytase supplementation were increased from 0 to 668 ± 65 FTU/kg (P < 0.01) and 0 to 668 ± 69 FTU/kg (P < 0.01), respectively. The ATTD of P and retention of P were increased until phytase supplementation contents were increased from 0 to 780 ± 86 FTU/kg (P < 0.01) and 0 to 773 ± 93 FTU/kg (P < 0.01), respectively. Myoinositol contents in plasma were increased (11.4 to 22.8 µmol/L) until phytase supplementation were increased from 0 to 705 ± 212 FTU/kg (P < 0.05). Increasing phytase supplementation linearly increased (P < 0.05) average daily gain and tended to linearly increase (P = 0.053) gain to feed ratio. In conclusion, supplementation of a hybrid bacterial 6-phytase improved ATTD of Ca and P, retention of Ca and P, complete hydrolysis of phytate, and growth performance of pigs compared with pigs fed a Ca and P deficient basal diet. Supplementation of a hybrid bacterial 6-phytase at a range of 650 to 800 FTU/kg feeds provided the optimal improvement of Ca, P, and phytate utilization.

Effects of betaine on growth performance and intestinal health of rabbits fed different digestible energy diets.

An experiment was conducted to determine the effects of betaine on growth performance and intestinal health in rabbits fed diets with different levels of digestible energy. During a 36-d experiment, a total of 144 healthy 35-d-old weaned New Zealand white rabbits with a similar initial body weight (771.05 ± 41.79g) were randomly distributed to a 2 × 3 factorial arrangement. Experimental treatments consisted of two levels of digestible energy (normal: 10.20 and low: 9.60MJ/kg) and three levels of betaine (0, 500, and 1,000mg/kg). Results indicated that rabbits fed the diet with low digestible energy (LDE) had reduced body gain/feed intake on days 1 to 14 and 1 to 36 (P < 0.05), increased the apparent total tract digestibility (ATTD) of neutral detergent fiber, acid detergent fiber (ADF), and n-free extract, and decreased the ATTD of gross energy (GE), crude fiber, and organic matter (OM; P < 0.05). The LDE diet upregulated the gene abundance levels of duodenum junctional adhesion molecule-3 (JAM-3) and downregulated the ileum toll-like receptor 4, myeloid differentiation factor 88, and interleukin-6 (IL-6; P < 0.05). Activities of amylase, lipase, trypsin, and the immunoglobulin M content in the jejunum were decreased in the LDE treatment group (P < 0.05). Dietary betaine supplementation increased the ATTD of GE, dry matter (DM), ADF, and n-free extract by LDE (P < 0.05). The villus height, crypt depth, and goblet cell numbers were decreased, and the villus-crypt ratio was increased in the duodenum (P < 0.05). The gene abundance levels of duodenum IL-2 were downregulated, and the duodenum JAM-2 and JAM-3 were upregulated (P < 0.05). Furthermore, the addition of betaine to the LDE diet increased the ATTD of GE, DM, and OM in rabbits (P < 0.05). Gene abundance levels of ileum IL-6 and duodenum JAM-3 were upregulated (P < 0.05). In summary, LDE diets can reduce the activity of intestinal digestive enzymes and decrease the ATTD of nutrients. However, the addition of betaine to LDE diets improved the intestinal barrier structure and nutrient ATTD in rabbits, with better results when betaine was added at an additive level of 500mg/kg.

Lactational performance, enteric methane emission, and nutrient utilization of dairy cows supplemented with botanicals

The objective of this study was to evaluate lactational performance, enteric gas emissions, ruminal fermentation, nutrient use efficiency, milk fatty acid profile, and energy and inflammatory markers in blood of peak-lactation dairy cows fed diets supplemented with Capsicum oleoresin or a combination of Capsicum oleoresin and clove oil. A 10-wk randomized complete block design experiment was conducted with 18 primiparous and 30 multiparous Holstein cows. Cows were blocked based on parity, days in milk, and milk yield (MY), and randomly assigned to 1 of 3 treatments (16 cows/treatment): (1) basal diet (CON); (2) basal diet supplemented with 300 mg/cow per day of Capsicum oleoresin (CAP); and (3) basal diet supplemented with 300 mg/cow per day of a combination of Capsicum oleoresin and clove oil (CAPCO). Premixes containing ground corn (CON), CAP, or CAPCO were mixed daily with the basal diet at 0.8% of dry matter intake (DMI). Supplementation of the diet with CAP or CAPCO did not affect DMI, MY, milk components, and feed efficiency of the cows. Body weight (BW) was increased during the last 2 wk of the experiment by CAP and CAPCO, compared with CON. The botanicals improved BW gain (0.85 and 0.66 kg/d for CAP and CAPCO, respectively, compared with -0.01 kg/d for CON) and CAP enhanced the efficiency of energy utilization, compared with CON (94.5% vs. 78.4%, respectively). Daily CH4 emission was not affected by treatments, but CH4 emission yield (per kg of DMI) and intensity (per kg of MY) were decreased by up to 11% by CAPCO supplementation, compared with CON and CAP. A treatment × parity interaction indicated that the CH4 mitigation effect was pronounced in primiparous but not in multiparous cows. Ruminal molar proportion of propionate was decreased by botanicals, compared with CON. Concentrations of trans-10 C18:1 and total trans fatty acids in milk fat were decreased by CAP and tended to be decreased by CAPCO, compared with CON. Total-tract apparent digestibility of nutrients was not affected by treatments, except for a tendency for decreased starch digestibility in cows supplemented with botanicals. Blood concentrations of β-hydroxybutyrate, total fatty acids, and insulin were not affected by botanicals. Blood haptoglobin concentration was increased by CAP in multiparous but not in primiparous cows. Lactational performance of peak-lactation dairy cows was not affected by the botanicals in this study, but they appeared to improve efficiency of energy utilization and partitioned energy toward BW gain. In addition, CH4 yield and intensity were decreased in primiparous cows fed CAPCO, suggesting a potential positive environmental effect of the combination of Capsicum oleoresin and clove oil supplementation.

Extruded diet macronutrient digestibility: plant-based (vegan) vs. animal-based diets in client-owned healthy adult dogs and the impact of guardian compliance during in-home trials

IntroductionPlant-based (vegan) diets for dogs are commercially available, however, research investigating long-term nutritional adequacy of these diets is scarce. Use of client-owned animals has become increasingly popular for apparent total-tract nutrient digestibility (ATTD) studies, yet low guardian compliance with the study protocol, such as providing daily dietary intake information, is a challenge. However, the impact of low diet reporting compliance on the overall ATTD results is unknown.MethodsSixty-one, client-owned healthy adult dogs completed a randomized, double-blinded longitudinal study. Dogs were randomly assigned into two groups that were fed either a commercial extruded meat-based diet (MEAT, n=30) or an experimental extruded vegan diet (PLANT, n=31) for 12 weeks. At the end of the study, pet guardians performed a 72-hour total fecal collection for ATTD assessment. Pet guardians were asked to complete a food diary for the duration of the trial, however only a subset of guardians (n=35) provided this food diary at the end of the study.ResultsNo evidence of an association between pet guardians providing a food diary and apparent digestibility coefficients (ADC) of crude protein (CP) (p=0.14), crude fat (EE) (p=0.72), and dry matter (DM) (p=0.68) was found. Apparent digestibility coefficients for CP (p=0.52), EE (p=0.78), and DM (p=0.43) did not differ between PLANT and MEAT. Body weight and age were found to be associated with CP (p=0.03) and DM (p=0.01) digestibility, but no association with EE (p=0.07) digestibility was present.DiscussionThese results indicate that vegan- and animal-based diets with similar nutrient profiles can have comparable nutrient digestibility. Moreover, presence or absence of a guardian-reported food diary had no effect on the overall results of the ATTD study. Further studies investigating guardian compliance for ATTD trials are needed to develop a standardized protocol and reduce current challenges and limitations related to pet guardian’s participation in digestibility trials.

356 Dietary Fenugreek Seed Extract Improves Dry Matter Intake, Apparent Total Tract Nutrient Digestibility, and Alters Whole Blood Transcriptome of Holstein Dairy Heifers

Abstract This study was conducted to evaluate the effects of dietary supplementation of a fenugreek seed extract (SAP) as a source of saponins on dry matter intake, blood metabolites, apparent total tract nutrient digestibility, and whole blood transcriptome of Holstein dairy heifers. Eight heifers (BW = 477 ± 23.8 kg) were stratified by BW and then randomly assigned to one of two treatments in a cross-over design with two 35-d experimental periods and a 14-d wash-out between the two periods. The heifers were housed individually in eight dry lot pens. Each pen was equipped with one GrowSafe intake node. Treatments were 1) corn silage-based diet with no additive (CON) and 2) corn silage-based diet plus 2 g ·animal-1·day-1 of SAP. Variables such as DMI and apparent total tract nutrient digestibility were analyzed as a randomized block design using the GLIMMIX model of SAS (SAS 9.4, SAS Inst. Inc., Cary, NC) using animal as the experimental unit. Blood metabolites that were measured repeatedly over time were analyzed using repeated measures and tested for the effect of treatment (CON vs. SAP), period, day of collection, and the day × treatment interaction. Dairy heifers fed supplemental SAP had greater (P ≤ 0.05). DMI and apparent total tract digestibility of dry matter, crude protein, and neutral detergent fiber compared with CON. Dairy heifers fed supplemental SAP had decreased (P = 0.03) blood urea nitrogen and greater (P = 0.01) blood glucose concentration compared with CON. Pathway analysis via gene set enrichment analysis revealed increased (FDR ≤ 0.05) transcript levels for gene sets belonging to ISG15 antiviral mechanism, metabolism of proteins, citric acid cycle and respiratory electron transport, ATP synthesis by chemiosmotic coupling, and complex I biogenesis in dairy heifers fed supplemental SAP compared with CON. Decreased (FDR ≤ 0.05) transcript levels for gene sets associated with erythrocytes take up/release carbon dioxide, release/take up oxygen, and O2/CO2 exchange in erythrocytes were also observed with SAP supplemental group. Taken together, our results revealed that fenugreek seed extract can be used as an effective dietary supplement for dairy heifers to improve intake and digestibility, and alter the host transcriptome toward improved energy and amino acid metabolism, improved antiviral immune status, and reduced oxidative stress damage.

351 Effects of Replacing Soybean Hulls with Molasses During the Receiving Period of Feedlot Steers

Abstract An experiment was conducted to evaluate the effects of replacing soybean hulls with molasses in the receiving diets of weaned feedlot steer-calves on growth performance, nutrient digestibility, enteric methane emissions, and blood inflammatory marker. Eighteen growing Angus crossbred steers (293 ± 11 kg body weight) were used in a completely randomized design with two diets, which were considered treatments. Diets consisted of (DM basis): 1) 46% corn silage, 25% dried distillers grains with solubles, 27% molasses, 0.5% limestone, and 1.5% vitamins and mineral packet (MOL), and 2) 46% corn silage, 22% dried distillers grains with solubles, 30% soybean hulls, 0.5% limestone and 1.5% vitamins and mineral packet (SBH). The experiment consisted of a 42-d period. On d -2 and -1, steers were weighed, and the average was considered initial body weight. On day -1, after weighing, steers were transported via truck and trailer for 12 h (6 h in one direction then 6 h back to the facility) to induce stress experienced by calves when shipped to another location as is standard in the beef industry. Steers were provided hay the evening they returned to the facilities. Steers were stratified by initial body weight and randomly assigned to individual pens, which were randomly assigned to one of the two treatments (MOL or SBH; n = 9 steers/treatment). Dietary treatments started on d 0. Other body weight measurements were recorded on d 7, 14, 21, 28, 35, 41 and 42. Final body weight was considered the average of two consecutive weights recorded on d 41 and 42. Blood samples were collected via venipuncture on days corresponding to body weight measurements. Feed intake data was collected daily by measuring dry matter of feed offered and orts refused. From d 14 to 20, breath samples were collected, using the sulfur hexaflouride technique, to determine enteric methane production, and feces were collected to determine apparent total tract nutrient digestibility. Data were analyzed using the MIXED procedure of SAS and steer as the experimental unit. The model included the fixed effect of treatment. Initial (P = 0.82) and final body weight (P = 0.64) were not affected by treatment. Additionally, no effects of treatment were observed on dry matter intake (P = 0.80) or average daily gain (P = 0.48). Data on enteric methane emissions, nutrient digestibility, and plasma LPS binding protein are still being analyzed. Preliminary data indicate that molasses can replace soybean hulls as an energy source in feedlot receiving diets without affecting animal performance.

193 Apparent Total Tract Nutrient Digestibility of Frozen Raw, Freeze-Dried Raw, Fresh, and Extruded Dog Foods and Their Effects on Fecal Characteristics and Metabolites of Adult Dogs

Abstract Various pet food diet formats are now available. Processing methods are known to impact nutrient digestibility and are thought to affect pet health but are poorly studied. Therefore, the objective of this study was to determine the apparent total tract macronutrient digestibility (ATTD) of frozen raw, freeze-dried raw, fresh, and extruded dog foods and assess their effects on fecal characteristics, and fecal metabolites of healthy adult dogs. Ten healthy adult spayed female dogs were used in a replicated 5x5 Latin square study to test the following diets: Chicken and Barley Recipe [extruded diet; Hill’s Science Diet (EXT)], Chicken and White Rice Recipe [fresh diet; Just Food for Dogs (FRSH)], Chicken Formula [raw frozen diet; Primal (FRZN)], Chicken and Sorghum Hybrid Freeze-dried Formula [hybrid freeze-dried raw diet; Primal (HFD)], and Chicken Dinner Patties [raw freeze-dried diet; Stella &amp; Chewy (FD)]. The experiment was composed of five 35-day periods. Total feces excreted during a 5-day total collection phase was frozen until analyses and ATTD calculations. On the first day of fecal collections, one fresh fecal sample was collected for measurement of pH, dry matter (DM) content, and bile acid (BA) and fermentative metabolite concentrations. Data were analyzed statistically by Mixed Models using SAS 9.4, with P &amp;lt; 0.05 being significant. Widespread differences were noted among diets. Wet and DM fecal output was greater for EXT than other diets, and wet fecal output was greater for FRSH than FRZN, HFD, and FD. Protein ATTD was greater for FRZN and FD than other diets, and greater for HFD than FRSH and EXT. Fat ATTD was greater for HFD than FRZN and EXT, and less for EXT than other diets. Fecal pH was less in EXT and FRSH than other diets. Fecal scores were greater (looser) in EXT and FRSH than FRZN and FRZDR. Fecal DM% was greater in FD than other diets, and greater in FRZN and HFD than EXT and FRSH. In general, fecal short-chain fatty acids were highest in EXT, intermediate in FRSH and HFD, and least in FRZN and FD. Fecal branched-chain fatty acids were greatest in FDF, intermediate in EXT, FRZN, and FD, and least for FRSH. Fecal phenols and indoles were greatest in HYB and least in FRSH, with others being intermediate. Fecal primary BA were greater in FRSH than other diets, while fecal secondary BA were greater in FRZN than HFD, FRSH, and EXT, greater in FD than FRSH and EXT, and greater in HFD than FRSH. In summary, the diets tested were very different in regard to nutrient digestibility, fecal characteristics, and fecal metabolites. More research is necessary to distinguish how ingredient source, diet processing, macronutrient composition, and other factors may contribute to these differences.

PSXII-25 Examining Relationships Between Residual Feed Intake Classification, Enteric Emissions, and Apparent Total Tract Digestibility in Yearling Beef Heifers

Abstract Improving feed efficiency in beef heifers may help reduce enteric emissions and improve economic returns for producers. The objective of this project is to assess the relationship between traditional residual feed intake (RFI) efficiency classification, enteric gas emissions, and apparent total tract nutrient digestibility in growing yearling heifers. Angus crossbred heifers (n = 74, BW = 408 ±27.1 kg) were blocked by BW and randomly assigned to pen groups. All heifers were fed a common haylage-based diet for ad libitum intake. Insentec feeding stations (Insentec B.V., Marknesse, The Netherlands) were used to measure individual feed intake and feeding behavior data. To measure enteric gas emissions of methane (CH4), carbon dioxide (CO2), and oxygen (O2), heifer groups were rotated through pens with GreenFeed trailers (C-Lock Inc., Rapid City, SD, USA) weekly. Apparent total tract digestibility was determined by collecting fecal samples from each heifer every 9 h over three days, composited and dried at 65 °C for 96 h, and analyzed for nutrient values (A&amp;L Canada Laboratories, London, ON, Canada). Nutrient digestibility was determined for each heifer using acid-insoluble ash (AIA) and undigestible neutral detergent fiber (uNDF) as internal markers. RFI was determined using a regression of midpoint BW and ADG and then heifers were ranked by RFI quartile group. Data were analyzed using PROC GLIMMIX in SAS, with efficiency quartile group as the fixed effect and pen as a random effect, comparisons between quartile groups were assessed with a Tukey test. As expected, efficient (least RFI) heifers had decreased dry matter intake (8.5 vs 10.1 ± 0.20 kg/d, P &amp;lt; 0.01), less bunk visits (70 vs 112 ± 6 visits/day, P &amp;lt; 0.01), spent greater time per visit (2.46 vs 1.31 ± 0.249 min/visit, P &amp;lt; 0.01), and consumed more feed per visit (145 vs 104 ± 11.9 g DM/visit, P &amp;lt; 0.03), which resulted in a faster eating rate (65 vs 98 ± 5.0 g DM/min, P &amp;lt; 0.01), and produced decreased enteric CO2 emissions (7,653 vs 8,120 ±122.6 g/d, P = 0.05) compared with inefficient (greatest RFI) heifers. Additionally, when using AIA as the internal marker, efficient heifers showed greater digestibility of organic matter (89.8 vs 91.4 ± 0.49 %, P = 0.02) and NDF (20.2 vs 30.0 ± 2.66 %, P = 0.04) apparent total tract digestibility, while using uNDF as the internal marker showed no difference (P &amp;gt; 0.20) between efficiency groups. These data indicate that more efficient yearling heifers consume less feed, have reduced enteric gas emissions, and have improved organic matter and NDF apparent total tract digestibility.

272 Effects of Increasing Dose of a Novel Hybrid Bacterial 6-Phytase on Apparent Total Tract Nutrient Digestibility, Release of Free Myoinositol, and Retention of Calcium and Phosphorus in Pigs

Abstract The objective of this study was to investigate the effects of increasing dose of a novel hybrid bacterial 6-phytase on apparent total tract digestibility (ATTD) of energy and nutrients, plasma concentrations of free myoinositol, and retention of calcium (Ca) and phosphorus (P). A total of 15 barrows (21.5 ± 1.4 kg BW) were allotted to a triplicate 5 × 5 Latin square design with 5 dietary treatments and 5 periods per each square. Pigs were individually housed in a metabolism crate. Five dietary treatments consisted of 5 levels of phytase-supplemented diets with increasing phytase units (0, 500, 1,000, 1,500, and 2,000 FTU/kg). Diets contained nutrients meeting the requirement except for Ca and P. Degree of deficient Ca and P content in the NC diet were 0.22 and 0.17%, respectively. Each period lasted 10 days consisting of a 5-d adaptation period and 5-d collection period for total collection. Data were analyzed using orthogonal polynomial contrasts using the Proc MIXED and optimal phytase levels were determined using the NLMIXED of SAS. The increasing phytase supplementation linearly increased (P &amp;lt; 0.05) average daily gain (651 to 695 g/d) and tended to linearly increase (P = 0.072) gain to feed ratio (0.53 to 0.56). Increasing phytase supplementation linearly increased (P &amp;lt; 0.01) ATTD of Ca and P and retention of Ca and P and also showed quadratic effects (P &amp;lt; 0.01). Increasing phytase supplementation linearly increased (P &amp;lt; 0.01) myoinositol content in plasma and also showed quadratic effects (P &amp;lt; 0.05). Broken line analyses showed that ATTD of Ca (P &amp;lt; 0.01) and retention of Ca (P &amp;lt; 0.01) were increased until phytase supplementation were increased (79.4 to 92.1% and 77.4 to 91.4%) from 0 to 671 FTU/kg (SE = 67; P &amp;lt; 0.01) and 0 to 668 FTU/kg (SE = 72; P &amp;lt; 0.01), respectively. Broken line analyses showed that ATTD of P (P &amp;lt; 0.01) and retention of P (P &amp;lt; 0.01) were increased (59.0 to 80.1% and 55.7 to 78.2%) until phytase contents were increased from 0 to 783 FTU/kg (SE = 91; P &amp;lt; 0.01) and 0 to 776 FTU/kg (SE = 76; P &amp;lt; 0.01), respectively. The broken line analyses showed that myoinositol contents in plasma (P &amp;lt; 0.01) were increased (13.2 to 23.2 µmol/L) until phytase supplementation were increased from 0 to 624 FTU/kg (SE = 174; P &amp;lt; 0.01). In conclusion, increasing phytase supplementation up to 2,000 FTU/kg feed improved ATTD of Ca and P, retention of Ca and P, complete hydrolysis of phytate, and growth performance of pigs compared with a P-deficient diet. Phytase supplementation at a range of 600 to 800 FTU/kg feeds provided the optimal improvement of Ca, P, and phytate utilization.

PSXII-24 Examining Relationships Between Residual Feed Intake Classification, Enteric Emissions, and Apparent Total Tract Digestibility in Late Gestation Beef Heifers

Abstract Improving feed efficiency on forage-based systems can be an important tool for beef producers to reduce their environmental footprint. The objective of this project is to assess the relationship between traditional residual feed intake (RFI) efficiency classification, enteric gas emissions, and apparent total tract nutrient digestibility in late gestation beef heifers. Pregnant Angus crossbred heifers in late gestation (n = 72, BW = 576 ± 45.8 kg) were blocked by expected calving date and randomly assigned to pen groups. Heifers had ad libitum access to a common haylage-based diet formulated to meet nutritional requirements for the last eight weeks of gestation. Individual feed intake and behavior data were recorded daily using Insentec feeding stations (Insentec B.V., Marknesse, The Netherlands). Groups of heifers were rotated through pens with access to GreenFeed trailers (C-Lock Inc., Rapid City, SD, USA) to measure enteric gas emissions of methane (CH4), carbon dioxide (CO2), and oxygen (O2). To determine individual apparent total tract digestibility, fecal samples were collected from each heifer every 9 h over three days, mixed, dried at 65 °C for 96 h, and analyzed for nutrient values (A&amp;L Canada Laboratories, London, ON, Canada). Nutrient digestibility was determined for each heifer using acid-insoluble ash (AIA) and undigestible neutral detergent fiber (uNDF) as internal markers. Heifer RFI was determined using predicted DM intake as a regression of midpoint BW and ADG, and heifers were classified by RFI quartile group. Data were analyzed using PROC GLIMMIX in SAS, with efficiency quartile group as the fixed effect and pen as a random effect, comparisons between quartile groups were assessed with a Tukey test. Heifers classified as efficient (lowest RFI) had decreased DMI (8.2 vs 10.7 ± 0.21 kg/d, P &amp;lt; 0.01), less bunk visits (43 vs 64 ± 5 visits/day, P &amp;lt; 0.01) and greater time per visit (4.8 vs 3.0 ± 0.53 min/visit, P = 0.05). Efficient heifers also had reduced CH4 (219 vs 245 ± 6.2 g/d, P = 0.03) and CO2 (7,517 vs 8,074 ± 165.9 g/d, P = 0.01) emissions compared with inefficient (greatest RFI) heifers. However, apparent total tract digestibility of organic matter, crude protein, NDF, ADF, starch, and sugar using AIA (P &amp;gt; 0.08) or uNDF (P &amp;gt; 0.06) as internal markers were not correlated with heifer efficiency. These data indicate that more efficient heifers in late gestation consume less feed and have reduced enteric emissions, despite no differences in apparent total tract digestibility.

Effects of particle size reduction of meadow hay on feed intake, performance, and apparent total tract nutrient digestibility in dairy cows

ABSTRACT Forage-based diets are encouraged in organic dairy cattle production as this can increase the net human food supply, but their voluminous nature can limit dry matter intake (DMI) and performance. This study investigates the effects of a substantial particle size reduction of hay on dairy cows’ feed intake, performance, and body characteristics, as well as on apparent total tract digestibility (ATTD). Eighteen lactating Holstein cows were allocated to two balanced feeding groups. The control group received long stem hay with a conventional particle size (CON), the experimental group received chopped hay (RED). Both groups were supplemented with concentrates (3.6 kg/d, DM basis). After 14 adaptation days, data were collected for 20 consecutive days. A covariate period of 21 days preceded the experimental feeding period. Particles retained on the 19-, 8- and 4-mm screens and on the pan of the Penn State Particle Separator accounted for 21%, 20%, 20% and 39% of the RED hay. CON hay consisted of 72% large particles, followed by 8%, 7% and 13% retained on the other screens. Average DMI levels of cows in the CON group reached 20.8 kg/d, with a nonsignificant increase (+1.05 kg/d) in the RED group (p = 0.28). Intakes of both NFC (+0.65 kg/d, p = 0.01) and CP (+0.28 kg/d, p = 0.05) were significantly greater in the RED group, resulting in a slightly increased milk yield (+0.8 kg energy corrected milk/d) (p = 0.45), likely because the ATTD decreased significantly when feeding RED hay. No impact was observed on energy balance (103.7 vs 103.9%, p = 0.95), feed conversion efficiency (kg ECM/kg DMI), or N use efficiency. Overall, the results indicate increases in intake of NFC and CP in the RED group when feeding a hay-based (>83%, DM basis) diet, but also a decrease in nutrient digestibility, likely due to increased passage rate, potentially because of the high fraction of hay particles < 4 mm. In conclusion, hay-based rations with a lower proportion of fine particles should be tested to exploit the potential of particle size reduction in terms of improving hay use efficiency.

Evaluation of the Available Energy Value and Amino Acid Digestibility of Brown Rice Stored for 6 Years and Its Application in Pig Diets.

Long-term storage may reduce the nutritional quality of brown rice, so the present study aimed to evaluate the nutritional values of long-term-stored nutrition in pig diets. In Exp. 1, 18 Landrace × Yorkshire (L × Y) barrows with an initial body weight (IBW) of 25.48 ± 3.21 kg were randomly assigned to three treatments, including a corn-based diet, one-year-stored brown rice (BR1) diet, and six-year-stored brown rice (BR6) diet, to determine the digestible energy (DE) and metabolizable energy (ME) values of stored brown rice. In Exp. 2, 24 barrows (L × Y; IBW: 22.16 ± 2.42 kg) fixed with ileal T-cannula were randomly allotted to four dietary treatments, including a corn diet, two stored brown rice diets, and a nitrogen-free diet, to evaluate the amino acid (AA) digestibility of the stored brown rice. In Exp. 3 and 4, 108 crossbred weaned piglets (L × Y; IBW: 9.16 ± 0.89 kg) and 90 crossbred growing pigs (L × Y; IBW: 48.28 ± 3.51 kg) were allotted to three treatment diets, including a control diet and two stored brown rice diets, respectively, to investigate the application of stored brown rice in weaned piglets and fully grown pig diets. The results indicated that there was no significant difference in the DE and ME values between corn and stored brown rice (p > 0.05), while the apparent ileal digestibility (AID) of arginine, histidine, asparagine + aspartic acid (Asx), and the standardized ileal digestibility (SID) of arginine and histidine were higher in the stored brown rice diet compared to the corn diet (p < 0.05). Compared to the corn, the stored brown rice showed no significant effects on growth performance, nutrient-apparent total tract digestibility (ATTD), and serum biochemical indices (p > 0.05) but showed decreased activity in the various digestive enzymes in the duodenum, jejunum, and ileum of the weaned piglets (p < 0.05). Also, the stored brown rice diet showed no significant effects on growth performance, carcass traits, meat quality, as well as the fatty acid profiles in the longissimus dorsi muscle of fully grown pigs compared with the corn diet (p > 0.05). In conclusion, the brown rice stored for 6 years under good conditions had no obvious changes in the available energy and nutrient values. Although it may reduce digestive enzyme activity in the small intestines of the piglets, the stored brown rice showed no obvious adverse effects on growth performance and meat quality and can be effectively used in pig diets.

306 Nutrient Digestibility and Dietary Energy Values in Growing Pigs Fed a Corn Distillers Dried Grains with Soluble (Cddgs)-Based Diet with Multi-Enzyme Supplementation

Abstract Dietary enzyme supplementation may enhance the digestibility and utilization of non-starch components of the diet by pigs. This study was conducted to evaluate the efficacy of a multi-carbohydrase enzyme (ENZ) in growing pigs for apparent ileal digestibility (AID) of amino acids (AA), apparent total tract digestibility (ATTD) of nutrients and energy values in a corn distillers dried grains with solubles (cDDGS)-based diet. A total of 12 ileal-cannulated pigs [initial body weight (BW) = 31.7 kg ± 3.04] were housed in individual metabolic crates for 21 days (Period 1) and subsequently transferred to individual floor pens for additional 28 days (Period 2). These animals were assigned to 2 diets (n = 6) in a completely randomized design (CRD). The diets were formulated on corn, soybean meal and cDDGS (30%) without (CON) or with ENZ supplementation. The ENZ (Proprietary xylanase/cellulase product, Kerry Inc.) was included in the diets at 200 g/tonne. Feeds were formulated to 1.15% SID lysine and met or exceeded nutrient requirements for growing pigs (NRC, 2012). Pigs were fed diets at three times maintenance energy requirement based on BW, which was assessed at every 2 weeks intervals throughout the study, Titanium dioxide was added to the diets as an indigestible marker. In period 1, pigs had 14 d of adaptation, followed by 4 d fecal and urine using the total collection method and 2 d ileal digesta collection. In period 2, pigs had 23 days adaptation, followed by 2 d fecal collection and 2 d illeal digesta collection. The AID of AA and gross energy (GE) and ATTD of nutrients and GE were calculated by an index method. Data were analyzed as a CRD, using pig as the experimental unit and enzyme supplementation as the main effect. Overall, average daily gain and gain:feed ratio of pigs were 857 and 918 g/d and 0.52 and 0.54 for CON and ENZ, respectively (P &amp;gt; 0.05). In period 1, ENZ supplementation improved (P &amp;lt; 0.05) the ATTD of dry matter (DM), ash, organic matter (OM), neutral detergent fiber (NDF), and GE by 4.4%, 26.8%, 2.8%, 11.3%, and 3.6%, respectively. Also, ENZ tended to improve (P &amp;lt; 0.10) the ATTD of crude protein (CP) by 7.4% and AID of threonine, CP, and GE by 6.6%, 7.6%, and 13.7%, respectively. In period 2, ENZ improved (P &amp;lt; 0.05) the ATTD of DM, ash, OM, CP, NDF, and GE by 5%, 30.1%, 3.4%, 4.1%, 19.6%, and 4.2%, respectively. similarly, EMZ improved (P &amp;lt; 0.05) the AID of threonine, CP, and GE by 4.2%, 6.0%, and 6.4%, respectively. In conclusion, multi-carbohydrase supplementation in a corn-SBM diet with 30% cDDGS increased the digestibility of nutrients and energy in growing pigs and may represent a useful strategy to optimize the utilization of such raw material.

Doses of orange (Citrus sinensis) essential oil for Nellore steers fed with a forage-based diet

The aim was to evaluate whether the doses of orange essential oil supplementation impact on dry matter intake (DMI), ruminal fermentation parameters, apparent nutrient digestibility, and methane production in Nellore steers fed with forage-based diet. A total of 32 rumen-cannulated Nellore steers (initial BW= 335±25 kg; age= 20±1 month) were assigned to individual pens in a randomized complete block design. Within block, steers were randomly assigned to treatments: CON= diet without orange essential oil (EO); 100EO= CON diet plus 100 mg orange EO/kg DM diet; 200EO= CON diet plus 200 mg orange EO/kg DM diet; and 500EO= CON diet plus 500 mg orange EO/kg DM diet. The main active compounds of the orange EO used were limonene (88.0 %) and myrcene (5.79 %). The experimental period lasted 28d, with 22d for adaptation and 6d for sample collection. From d23 to 27, samples of haylage, concentrate, and total fecal production were collected to determine the total tract apparent nutrient digestibility. Ruminal fluid was obtained from d28 at 0, 6, and 12 h after feeding to determine ruminal fermentation parameters and methane production. The difference was considered significant when P ≤ 0.05. No treatment effects were detected (P>0.05) to DMI or specific nutrient intake. The increasing levels of EO did not affect (P>0.05) the total apparent nutrient digestibility. No treatment effects were detected (P>0.05) for ruminal fermentation parameters in vivo. In ex situ, there was a treatment effect for acetate, total short-chain fatty acids (SCFA), methane, and relative energy loss (REL). For acetate, an increasing linear effect was observed for treatments that received EO for the variables production (g/kg) (P = 0.002) and gross energy (MJ/kg) (P = 0.002), with a higher concentration for the 500EO. For the total production of SCFA, there was an increasing linear effect of treatment with a higher concentration for 500EO for the variables production (g/kg) (P = 0.001) and gross energy (MJ/kg) (P = 0.001). For methane, a quadratic treatment effect was observed for the variables production (g/kg) (P = 0.045) and gross energy (MJ/kg) (P = 0.046), with lower concentrations for the 200EO. There was a decreasing linear treatment effect for REL(%) (P<0.001). The results for the use of orange EO as a manipulator of ruminal fermentation were promising and the dose of 500 mg/kg of DM showed a greater capacity to increase the energy efficiency of fermentation, with greater production of acids and lower production of methane, without affecting the voluntary intake of steers.

Feeding rumen-protected Capsicum oleoresin to dairy cows during the transition period and early lactation: Effects on nutrient digestibility, blood metabolites, and performance

Capsicum oleoresin (CAP), a plant extract derived from chili pepper plants, contains bioactive compounds reported to influence the energy metabolism in dairy cows. This study investigated the effects of feeding rumen-protected CAP during the transition period and early lactation on total-tract apparent digestibility of nutrients, serum metabolites [glucose, urea-N, non-esterified fatty acids (NEFA), and beta-hydroxybutyrate (BHB)], and milk yield and composition in dairy cows. Twenty-four healthy Holstein cows (12 multiparous and 12 primiparous) were enrolled to this study at − 4 wk from the expected calving date. Animals were blocked according to parity and expected calving date. Cows within block were randomly assigned to a control (CON) treatment without feed additives or to the CAP treatment, dietary supply of rumen-protected CAP at 100 mg/d. Pre-partum and post-partum data were analyzed separately. Dry matter intake and related dietary variables were not affected by treatments during the pre- or post-partum period. No differences were detected on digestibility of DM, organic matter, or crude protein during the pre-partum and post-partum periods. Serum metabolite concentrations were similar between treatment groups either during the pre-partum or post-partum periods. Milk yield tended to be greater (P = 0.07) in cows fed CAP than CON (31.7 and 28.5 kg/d, respectively). Fat-corrected milk yield was increased (P = 0.03) by feeding CAP. Milk fat yield (1.20 vs. 1.05 kg/d) and feed efficiency (1.72 vs. 1.50 kg milk/kg DM intake) were significantly greater (P ≤ 0.03) in cows fed CAP than CON. Feeding rumen-protected CAP at 100 mg/d during the transition period and early lactation increased fat-corrected milk yield, and improved milk fat and feed efficiency of dairy cows.

Effect of short-term abomasal corn starch infusions on postruminal fermentation and blood measures

It is possible that some of the systemic responses to subacute ruminal acidosis (SARA) may be caused by increased intestinal starch fermentation. The objective of this experiment was to evaluate the effect of abomasal infusion of up to 3 g of corn starch/kg body weight (approximately 1.6 kg of starch/d) on fecal measures of fermentation, plasma acute phase proteins, and white blood cell populations. Six ruminally cannulated cows in late lactation were randomly assigned to duplicate 3 × 3 Latin squares with 21-d periods. Cows were fed a 20.6% starch TMR twice daily and during the last 7 d of each period cows were abomasally infused with corn starch at 0 (CON), 1 (ST1), or 3 (ST3) g/kg body weight split into 2 bolus infusions, provided every 12 h. Fecal samples were collected at 0, 6, 12, and 18 h following feeding on d 21 and were analyzed for pH, VFA, lactic acid, and lipopolysaccharide (LPS). Composite fecal samples were used to estimate apparent total-tract nutrient digestibility using undigested neutral detergent fiber as an internal marker. Blood samples were collected at 0 and 6 h relative to feeding on d 14, 18, and 21 of each period. Concentrations of haptoglobin and serum amyloid A in plasma were measured in all samples, 0 h samples on d 14 and 21 were used to measure white blood cell populations, and 0 h samples from d 14, 18, and 21 were used for flow cytometric analysis of γδ T cells. Data were analyzed in SAS using models that included fixed effects of treatment and period and the random effects of cow and square. For blood measures, d 14 samples collected before the initiation of abomasal infusions were included as covariates. Time (d or h) was added as a repeated measure in variables that included multiple samples during the abomasal infusion period. A contrast was used to determine the linear effect of increasing abomasal corn starch. Abomasal corn starch linearly decreased fecal pH and linearly increased fecal total VFA and LPS, but effects were modest, with fecal pH, total VFA, and LPS changing from 6.96, 57.7 mM, and 4.14 log10 endotoxin units (EU) per gram for the CON treatment to 6.69, 64.1 mM, and 4.58 log10 EU/g for the ST3 treatment, respectively. This suggests that we did not induce hindgut acidosis. There were no effects of treatment on apparent total-tract starch digestibility or fecal starch content (mean of 96.9% and 2.2%, respectively). Treatment did not affect serum acute phase proteins or most circulating white blood cells, but the proportion of circulating γδ T cells tended to linearly decrease from 6.69% for CON to 4.61% for ST3. Contrary to our hypothesis, increased hindgut starch fermentation did not induce an inflammatory response in this study.

Propionic acid-based additive with surfactant action on the feeding value of rehydrated corn grain silage for dairy cows performance

Eighteen Holstein cows with 218 ± 106 days in milk (mean ± SD) and average daily milk yield of 22 ± 7.6 kg (mean ± SD) were assigned to six 3 × 3 Latin squares to evaluate the effects of using a propionic acid-based additive with surfactant action (Mycoflake™; Kemin South America, Indaiatuba, SP, Brazil) at the ensiling of rehydrated corn grain on its nutritional value and animal performance. Dry ground corn grain (998 μm) was rehydrated to reach 400 g/kg fresh matter of moisture, with or without the additive, and ensiled in 200-L plastic drums. Treatments were prepared as follows: rehydrated corn grain silage (RCGS) stored for 30 d as a negative control (30CON), RCGS stored for 60 d as a positive control (60CON) and RCGS treated with Mycoflake™ at 2 L/t and stored for 30 d (30MYC). The animals were offered a total mixed ration containing 399 g/kg whole-plant corn silage, 98 g/kg Tifton haylage, 207 g/kg RCGS (according to treatment), 98 g/kg citrus pulp, 173 g/kg soybean meal and 25 g/kg mineral-vitamin mix in total diet dry matter (DM). Ruminal DM disappearance (DMD) of RCGS was evaluated in situ using two canulated Holstein cows after 12, 24 and 48 h of incubation. Total tract apparent digestibility (TTAD) of nutrients was determined using the indigestible neutral detergent fiber content as a marker measured after 288 h of incubation in a canulated Holstein cow. Although no change in soluble protein content was observed for the 30MYC silage, its NH3-N content was greater than 30CON in both DM (P = 0.01) and total N (P = 0.02) basis, and did not differ from 60CON. The proportion of NH3-N in soluble N of 30MYC was the highest compared to both 30CON (P = 0.02) and 60CON (P < 0.01). The 30MYC RCGS presented lower geometric mean particle size and greater surface area than both 30CON (P < 0.01) and 60CON (P < 0.01). Although the pH of 30MYC RCGS did not differ from 30CON and 60CON, its lactic acid content (11.9 g/kg DM) was greater than both 30CON (9.28 g/kg DM; P = 0.05) and 60CON (8.10 g/kg DM; P = 0.01). No changes in ruminal DMD were observed for 30MYC RCGS against 30CON. There were no changes on dairy cows performance fed the 30MYC RCGS against 30CON. Cows fed 30MYC RCGS presented a different pattern of sorting behavior against 30CON and 60CON, resulting in lower intake of physically effective fiber than both 30CON (P = 0.01) and 60CON (P = 0.02), although no effect on ruminating and chewing activities was observed. No effect on TTAD of nutrients was observed for cows fed 30MYC RCGS against 30CON. Mycoflake™ hampered the formation of aggregates in RCGS, and did not enhance proteolysis. Despite changes in sorting behavior, the additive did not affect performance of dairy cows.