Apparent Digestibility Of Starch Research Articles

PSXII-22 Ruminal in situ dry matter and starch degradability in grain sorghum silage, as affected by processing and storage time

Abstract Our previous studies showed that processing sorghum silage at harvest and storing for approximately 150 d, improved average daily gain (ADG), feed efficiency (FE) and apparent total tract digestibility (ATTD) of starch when included as the basal ingredient in diets fed to growing Angus heifers. However, differences in animal performance and nutrient digestibility disappeared when the same sorghum silage was fed again after 1 yr of storage. An experiment was performed to evaluate the effects of kernel processing and storage time on ruminal in situ degradability of sorghum silage (SS). A grain sorghum (ADV2450IG, Advanta seeds, Irving, TX) was harvested (Claas Jaguar 930, Harsewinkel, Germany) at the late-dough stage of grain maturity. Treatments were applied at harvest and consisted of sorghum berry processing (PRO) with a specific SS kernel processor (196 mm rolls of 125 teeth each, 40% speed differential, 1.1 mm roll gap), or not processed at all (NPR). Silage was chopped at 15 mm theoretical length of cut and ensiled in polyethylene ag bags (60 m long and 2.74 m diameter), for 455 d. Samples were taken from each treatment on d 0, 66, 112, 157, 202, 246, 291, 336, 381, 426, and 455 and were kept frozen until analyzed. Samples were dried but not ground, to avoid affecting treatments. Ruminal in situ degradability of dry matter (DM) and starch was determined by incubating nylon bags for 24 h in duplicate, in the rumen of four ruminally cannulated steers consuming a corn silage-based diet. Data were analyzed as a randomized block design with repeated measures. The fixed effect of treatment, day and their interaction were included in the model and the repeated subject was considered the animal within treatment. A storage day × treatment interaction was detected for in situ DM degradability (P < 0.001). The PRO treatment increased (P < 0.05) in situ DM degradability at 66 and 202 d of storage and tended to increase it (P = 0.07) at 157 and 291 d of storage. An effect of storage day (P < 0.05) was observed for in situ starch degradability and because there was no interaction with treatment (P = 0.43), treatments means were compared across storage days. No differences were detected in ruminal in situ digestibility of DM or starch when silage was stored for 202 d, when compared with d 0 (P = 0.43), while starch degradability increased when silage was stored for 202 and 291 d (P < 0.03). At 381 d of storage, no differences were detected for starch degradability when compared with d 0. In conclusion, berry processing of sorghum when harvested for silage, increased ruminal in situ DM degradability. However, those differences disappear after more than 200 d of storage, in agreement with animal performance data previously reported by our group.

154 Reduction of particle size of field peas increases net energy and digestibility of starch when fed to growing pigs

Abstract Two experiments were conducted to test the hypothesis that particle size of field peas and location of production may affect the apparent ileal digestibility (AID) of starch, the standardized ileal digestibility (SID) of amino acids (AA), and net energy (NE). One source of peas from the U.S., and two sources from Canada were procured. The U.S. peas were ground to 265, 457, or 678 µm, whereas the two Canadian peas were ground to 411 and 415 µm, respectively. A basal diet containing corn and soybean meal as the sources of energy, starch, and AA, and five diets containing corn and soybean meal and 50% of each source of peas were formulated. Pigs were fed the same diets in Exp. 1 and 2, but an N-free diet was also used in Exp. 1. In Exp. 1, barrows [n = 7; initial body weight (BW) = 60.6 kg; SD = 2.1] that had a T-cannula installed in the distal ileum were allotted to a 7 × 7 Latin square design with seven diets and seven periods. Ileal digesta were collected and analyzed for Cr and AA. In Exp. 2, pigs (n = 24; initial BW = 30.8 kg; SD = 1.0) were used in a 6 × 6 Latin square design with six calorimetry chambers and six periods. To determine NE, feces and urine were quantitatively collected and O2 consumption and CO2 and CH4 productions were measured. In both Exp. 1 and 2, the statistical model included diet as the main effect and pairwise comparisons were used to separate the means. Contrast coefficients were also used to determine linear effects of particle size within the U.S. peas. Results from Exp. 1 indicated that the SID of AA was not influenced by the origin of the peas or by particle size, except that the SID of Arg was linearly (P = 0.042) increased (Table 1) as particle size of U.S. field peas was reduced. The AID of starch in the U.S. peas ground to 265 µm was greater (P < 0.05) than in the two Canadian sources, and the AID of starch and NE in diets were linearly (P < 0.001) increased as particle size was reduced. The NE in U.S. peas ground to 678 µm was less (P < 0.05) than in all other pea samples. In conclusion, AID of starch, SID of AA, and NE did not differ between field peas grown in Canada and peas grown in the U.S., but reducing the particle size of field peas resulted in improved digestibility of starch and energy by pigs.

47 Inclusion of black soldier fly (Hermetia illucens) larvae frass as an alternative protein source in the diet of Florida native yearling ewes.

Abstract The objective of the study was to evaluate the effects of partially replacing soybean meal (SBM) with black soldier fly larvae frass (BSFL) on nutrient digestibility, growth performance, and blood profile of ewes consuming diets with approximately 10% SBM on a DM basis. Six yearling Florida native ewes, averaging (mean ± SD) 44 ± 3 kg BW were enrolled in a replicated 3 × 3 Latin square design with 3 experimental periods of 21 d each (14 d adaptation + 4 d samples collection + 3 d washout). First 14 d of each period, ewes were housed in 7.4 × 1.8 m individual pens with rubber mats, one automatic waterer and two plastic feeders. During collection, ewes were moved to 1.4 × 0.7 m metabolic crates equipped with an individual waterer and feeder and two trays for the collection of feces and urine. Animals were fed TMR ad libitum twice daily at 0730 and 1530 h consisting of different levels of SBM replacement with BSFL, as follows: no replacement (CON), partial replacement of SBM with 25% BSFL (BSFL25) and 50% BSFL (BSFL50) on a DM basis. Data on DM and nutrient intake, excretion, and apparent digestibility, and also plasma concentrations of glucose and blood urea nitrogen (BUN), and urine concentrations of allantoin, urine blood nitrogen, and uric acid, were collected. Data were analyzed with SAS 9.4 evaluating orthogonal polynomial contrasts to determine linear and quadratic effects of SBM replacement with BSFL for each response variable. The intakes of DM, NDF, ADF, EE, and starch were greater for BSFL25 compared with control (Quadratic effect; P < 0.01) while no differences were observed between BSFL25 and BSFL50. Similarly apparent digestibilities of DM, NDF, ADF and starch was less for BSFL25 than CON (Quadratic effect; P ≤ 0.01). Intake of CP linearly increased (P < 0.01) with BSFL, while apparent digestibility of CP linearly decreased and that of EE increased, with inclusion of BSFL. There was a quadratic effect of BSFL on total feces excretion (P < 0.01) and water consumption (P < 0.01) being greater in BSFL25 compared with CON. Urine BUN (P < 0.01) and urine nitrogen (P < 0.01) linearly increased with BSFL inclusion. Results indicate that partial replacement of SBM with BSFL in the diet of yearling Florida native ewes may quadratically increase feed intake and decrease nutrient apparent digestibility. Further research is needed to explore the long-term implications of incorporating BSFL into animal diets, considering their impact on overall growth and performance.

Endogenous Enzyme Activities, Digestibility of Nutrients and Digestive Physiology as Affected by High Inclusion of Cottonseed Meal in Broiler Chicken Diets

A 3 × 3 factorial study examined the performance, endogenous enzyme activities and apparent ileal digestibility of nutrients, including energy, protein, starch, dry matter, amino acids and minerals of birds fed diets containing graded levels of cottonseed meal (CSM) with or without microbial enzymes. Nine iso-caloric and iso-nitrogenous diets were formulated mainly from wheat/sorghum/soybean meal. Three levels of CSM none (0%), low (5%, 10%, and 15%) or high (6%, 12%, and 18%) in the starter, grower, and finisher diets, respectively, were included. The diets were supplemented with three levels of a composite xylanase and beta-glucanase product at 0, 100 or 150 mg/kg diet. Each of the nine dietary treatments was randomly assigned to 6 replicates, with 10 birds per replicate. Feed intake (FI) and weight gain (WG) were recorded on day 10, 24 and 35, and feed conversion ratio (FCR) was obtained from the data, while enzyme activities and nutrient digestibility were measured on samples collected on day 10 and 24, and day 24 only, respectively. Feed intake up to day 35 decreased (P < 0.05) significantly with increasing enzyme supplementation. On the CSM-containing diets, enzyme supplementation at 100 or 150 mg/kg improved WG up to day 24, with the heaviest birds (1514 g/b) observed in the low CSM with 100 mg/kg enzyme group. Enzyme supplementation improved (P < 0.01) FCR all through the growth phases and also improved (P < 0.05) ileal crude protein and starch digestibility. High levels of CSM decreased the digestibility of starch, but this was improved (P < 0.05) by enzyme supplementation, showing an interaction between CSM and microbial enzyme on starch digestibility. The digestibility of arginine, glutamic acid and threonine improved with increased CSM inclusion, and that of methionine improved with increased enzyme supplementation. There was an interaction effect (P < 0.01) between CSM and enzyme on magnesium digestibility. Cottonseed meal inclusion improved the digestibility of copper and potassium and reduced the digestibility of phosphorus, while that of calcium and manganese was increased (P < 0.01) with enzyme supplementation. At day 10, lipase activity was increased (P < 0.05) by higher CSM levels, while on day 24, general proteolytic activity was highest (P < 0.05) when 100 mg enzyme was supplemented in the diet. These results indicate that relatively high levels of CSM in diet have no negative effects on the growth and digestive physiology of broiler chickens when supplemented with xylanase and β–glucanase.

Reduction of particle size of field peas (Pisum sativum L.) increases net energy and digestibility of starch when fed to growing pigs, but there is no difference in nutritional value between peas from the United States and peas from Canada.

Two experiments were conducted to test the hypotheses that particle size of field peas and location where peas are grown do not affect apparent total tract digestibility of nutrients and gross energy, digestible energy (DE), metabolizable energy (ME), and net energy (NE), apparent ileal digestibility (AID) of starch, or standardized ileal digestibility (SID) of crude protein (CP) and amino acids (AA). In both experiments, 3 sources of field peas were used. One source was obtained from the United States and 2 sources were obtained from Canada (i.e., Canada 1 and Canada 2). The U.S. field peas were ground to 678, 457, or 265 µm, whereas the 2 sources of Canadian peas were ground to 411 and 415 µm, respectively. Therefore, 5 batches of field peas were used in both experiments. A basal diet contained corn and soybean meal as the only source of energy, starch, and AA, and 5 diets containing corn and soybean meal and 50% of each source of field peas were also formulated. The ratio between corn and soybean meal was 1.92:1 in all diets. In experiment 1, an N-free diet was also used to calculate basal endogenous losses of AA and CP, but in experiment 2, no N-free diet was used. In experiment 1, 7 barrows (initial body weight = 60.6 ± 2.1kg) that had a T-cannula installed in the distal ileum were allotted to a 7 × 7 Latin square design with 7 diets and 7 periods. In experiment 2, 24 pigs (initial body weight = 30.8 ± 1.0kg) were housed in 6 calorimeter chambers with 4 pigs per chamber. The 6 chambers were allotted to one of the 6 diets using a 6 × 6 Latin square design with 6 consecutive periods of 15 d. Results of experiment 1 demonstrated that the SID of CP and AA was not influenced by the origin of the peas or by the particle size, but the AID of starch increased (linear, P < 0.001) as particle size was reduced from 678 to 457 or 265 µm. Results of experiment 2 indicated that growing location did not affect concentrations of DE, ME, or NE of field peas, but concentrations of DE, ME, and NE increased (linear, P < 0.05) when particle size was reduced from 678 to 457 or 265 µm. In conclusion, field peas grown in Canada or the United States have the same nutritional value, but starch digestibility and NE increase if the particle size of field peas is reduced.

Influence of particle size and origin of field peas on apparent ileal digestibility of starch and amino acids and standardized ileal digestibility of amino acids when fed to growing pigs.

The objective was to test the hypothesis that particle size and origin of field peas influence the apparent ileal digestibility (AID) of starch, crude protein (CP), and amino acids (AA) and the standardized ileal digestibility (SID) of AA. Three sources of field peas were procured. One source was from the United States and two sources were from Canada. The U.S. source and one of the sources from Canada (i.e., Canada 1) were each divided into two batches and ground to achieve a target particle size of 250 or 450µm, whereas the other source from Canada (i.e., Canada 2) was only ground to a target particle size of 250µm. Each batch of field peas was included in one diet as the only source of AA. An N-free diet was used to determine the basal endogenous losses of CP and AA. Six barrows (initial weight: 50.5kg; SD = 3.7) that had a T-cannula installed in the distal ileum were randomly allotted to a 6 × 6 Latin square design with six diets and six 7-d periods. Ileal digesta from pigs were collected for 2d after 5d of adaptation. Data were analyzed using a statistical model that included batch of field peas as the fixed effect and animal and period as the random effects. Contrast statements were used to analyze the effects of particle size, origin, and the interaction between particle size and origin. Results indicated that the AID of starch was increased by reducing the particle size in the U.S. source of field peas, but that was not the case for the Canada 1 source (interaction; P < 0.001). Particle size did not influence the AID of CP or AA, but the Canada 2 source of field peas had greater (P < 0.05) AID of Trp, Ala, Cys, Gly, and Tyr than the field peas from the United States. The SID of CP and AA was also not affected by the particle size of field peas. The SID of CP and Trp was greater (P < 0.05), and the SID of His, Ile, and Thr tended (P < 0.10) to be greater in the Canada 2 source compared with the U.S. source, but no differences between the two Canada sources were observed. In conclusion, a few differences in SID of AA between field peas produced in the United States and peas produced in Canada were observed, but there was no effect on SID of AA of reducing the particle size of field peas from 450 to 250µm, whereas the AID of starch increased by reducing the particle size only in the field peas from the United States.

Effect of wheat middling incorporation into wet corn distillers grains with solubles on apparent diet digestibility and ruminal fermentation characteristics in growing and finishing diets.

Two separate cross-over experiments were conducted to evaluate the effects of incorporating wheat middlings into wet corn distillers grains with solubles (WDGS) on apparent diet digestibility and ruminal fermentation characteristics in growing and finishing diets. In experiment 1, four ruminally cannulated heifers (313 ± 42.9kg) were limit fed a high-energy growing diet that included WDGS (CON) or WDGS + wheat middlings (CON + WM) at 40% of diet dry matter (DM). The diet also contained (DM basis) 39.5% dry-rolled corn, 7.5% supplement, and 13% warm-season grass hay. In experiment 2, four ruminally cannulated Holstein steers (321 ± 17.4kg) were fed a finishing diet that included WDGS (CON) or WDGS + wheat middlings (CON + WM) at 30% of diet DM. The diet also contained (DM basis) 60.3% dry-rolled corn, 2.7% supplement, and 7.0% warm-season grass hay. Experiments consisted of two 15-d periods that were conducted concurrently. Each period included 10 d of diet adaptation, 4 d of fecal collection, and 1 d of ruminal fluid collection. Fecal samples were collected on days 11 to 14 of each period and composite samples were analyzed for chromium to estimate apparent diet digestibility. On day 15, ruminal fluid samples were collected prior to feeding and again at 2, 4, 6, 8, 12, 18, and 24-h post-feeding. In experiment 1, DM, organic matter (OM), neutral detergent fiber (NDF), and acid detergent fiber (ADF) intake did not differ (P ≥ 0.11) between diets; however, starch intake was greater (P = 0.03) for heifers fed CON + WM compared with CON. Apparent DM, OM, NDF, and starch digestibilities were similar between diets (P ≥ 0.13), but feeding CON + WM tended to lead to lesser (P = 0.06) apparent ADF digestibility. Ruminal pH and total volatile fatty acid concentrations did not differ between diets (P ≥ 0.16); however, ruminal ammonia concentrations tended to be less (P = 0.09) for CON + WM compared with CON. In experiment 2, DM intake did not differ (P = 0.65) between diets. Apparent DM digestibility was greater (P = 0.01) for CON + WM compared with CON but the difference was small. Intake and apparent digestibility of OM, NDF, ADF, and starch did not differ (P ≥ 0.25) between diets. Ruminal ammonia concentrations were lesser (P = 0.03) while ruminal pH was greater (P = 0.02) for CON + WM compared with CON. Overall, incorporation of wheat middlings into WDGS had minimal impacts on feed intake, apparent diet digestibility, and ruminal fermentation characteristics when fed to growing and finishing cattle.

PSXIII-16 Selected Feed Additives to Improve Diet Digestibility and Carcass Quality of Feedlot-Finished Angus Crossbred Steers

Abstract Our objective was to evaluate the effects of supplementation using different feed additives on the apparent digestibility and carcass traits of feedlot-finished steers fed a diet consisting of 35% forage and 65% concentrate. This study was a randomized block experimental design with two treatments: Diet containing sodium monensin + virginiamycin (MO+VM, 20 ppm and 15 ppm, respectively); and Diet with a blend of essential oils (Crina Ruminants, 90 ppm) + exogenous α-amylase (Ronozyme Rumistar, 560 ppm) + 25-hydroxy-vitamin-D3 (Hy-D, 0.1 ppm), (EO+ENZ+HYD), with nine repetitions each (pens), where each experimental unit was represented by a pen (with two animals each). Thirty-six 50% Angus blood steers with an average initial weight of 400 kg were evaluated along an experimental period of 112 days, with 28 adaptation days and 84 evaluation days, divided into 3 periods of 28 days each. The digestibility evaluation was carried out at the end of the first and third experimental periods, both in a continuous time of 48 hours. For this, daily intake and leftovers were measured, total feces were collected, diets and leftovers from each pen were sampled for laboratory analysis. At the beginning and end of the experiment, using ultrasound, carcasses were analyzed for loin eye area, marbling ratio, subcutaneous fat thickness (SFT), and rump fat thickness (RFT). Means were compared by ANOVA using the GLM procedure (SAS, 1993), adopting a significance level of 5%. Fecal output (kg· day-1), both in dry matter and natural matter, and fecal DM content were similar between treatments (P &amp;gt; 0.05). Feeding EO+ENZ+HYD reduced (P &amp;lt; 0.05) fecal starch percentage by 20% and improved (P &amp;lt; 0.05) the apparent digestibility of DM and starch (5.16%, 67.40% and 95.50%) compared with the use of MO+VM (6.41%, 66.47% and 94.27%). These better results suggest an effect of a more favorable fermentation of the diet caused by modulation of the ruminal microbiota, optimization in the use of starch and increase in microbial protein synthesis caused by supplementation with EO+ENZ+HYD. Animals supplemented with EO+ENZ+HYD had greater (P &amp;lt; 0.05) RFT (12.22 mm) at slaughter compared with those supplemented with MO+VM (10.42 mm), and greater marbling and RFT gain over the finishing period (0.58 points and 7.50 mm) than those supplemented with MO+VM (0.32 points and 5.93 mm) after 112 days of feedlot. In conclusion, the blend of essential oils + exogenous α-amylase + 25-hydroxy-vitamin-D3 was effective in replacing the combination sodium monensin + virginiamycin, improving the apparent digestibility of DM and starch, as well as increasing marbling and carcass cover fat deposition of feedlot-finished steers.

PSXIII-17 Feeding Sorghum Silage: Effects of Grain Processing on Intake and Apparent Total Tract Digestibility of Backgrounding Beef Heifers

Abstract This study evaluated the effect of processing sorghum silage (SS) at harvest on dry matter intake and nutrient digestibility of beef cattle. A dual-purpose sorghum (ADV2450IG, Advanta seeds, Irving, TX) was harvested (Claas Jaguar 930, Harsewinkel, Germany) at the late-dough stage of grain maturity and processed (PRO) or not (NPR) with a specific SS cracker (196 mm rolls of 125 teeth each, 40% speed differential, 1.1 mm roll gap). Whole-plant was chopped at 15 mm and ensiled in polyethylene ag-bags (60 m long and 2.74 m diameter) for 60 d until the beginning of a performance trial which was followed by the digestibility trial. From a performance trial with eight heifers/pen and 12 pens total (six per treatment), one heifer (13 ± 1.5 mo and 251,4 ± 36.3 kg of BW) by pen was randomly selected for the digestibility trial. Two backgrounding diets containing (DM basis), 90.5% SS either PRO or NPR, 6.5% soybean meal (expeller) and 3% supplement (ROC90, Provimi, Argentina); continued to be offered ad libitum for an extra 3 d of adaptation, while feed and feces were collected the next 4 d. Feed was individually offered once daily, and orts were collected the following day. Fecal samples were collected twice daily and apparent total tract digestibility was determined using uNDF240h as a marker. Data were analyzed as a completely randomized design using pen as the experimental unit, and initial BW as a covariate. Dry matter (DM) and organic matter (OM) intake tended (P &amp;gt; 0.07) to be greater, while starch intake was greater (P &amp;lt; 0.03) for the NPR treatment. intake of NDF, ADF and CP were not affected by treatments. No differences (P &amp;gt; 0.10) were detected for DM, OM, NDF, ADF and CP digestibility, while starch digestibility was greater (P &amp;lt; 0.001) by processing (93.55 vs. 86.48 for PRO and NPR, respectively). In conclusion, processing sorghum silage at harvest increased apparent total tract digestibility of starch when SS was fed to backgrounding beef heifers.

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.

339 An Evaluation of the Effects of Feeding an Exogenous Fibrolytic Enzyme Product on the Growth Performance and Apparent Nutrient Digestibility of Growing Bison Calves Fed in a Commercial Feed Yard

Abstract While exogenous enzyme supplementation has been tested in ruminants as early as the 1960’s, industry adoption of such technologies has been slow. With high feed costs, technologies such as feed enzyme could potentially help producers to lower the production cost by improving feed efficiency. A 69-day growing experiment was conducted at a commercial feed yard in Western NE using bison calves [n = 228; initial body weight (BW) = 269 kg, SD = 41 kg] to determine the effects of supplementation of an exogenous fibrolytic enzyme from T. reesei on calf dry matter intake (DMI), growth performance and nutrient apparent digestibility. A completely randomized design was utilized with two treatments, control (CON) or enzyme (CX), and four pens, with calves assigned randomly to pen and pen assigned to TRT (48 to 66 calves per pen). Individual calf BW were obtained on day 0, day 35, and day 69. The DMI was measured daily by pen, with feed offered adjusted daily and fecal samples were composited and analyzed on pen-basis. Data were analyzed using JMP statistical software, with initial BW included as a covariate in the analyses. Average daily gain and DMI in calves fed the CX treatment was 7% greater (0.895 vs. 0.830 kg/d; P = 0.02), and 11% less (7.83 vs. 8.75 kg/d; P = 0.02) than in calves fed the CON treatment, respectively, resulting a 18% numeric improvement in feed efficiency for calves fed the CX treatment compared with calves fed the CON treatment. Apparent starch digestibility tended to improve (P = 0.07) by 15% in calves fed the CX treatment compared with calves fed the CON treatment, while apparent neutral detergent fiber (NDF) digestibility (as a percent of NDF) was numerically improved by 9% in calves fed the CX treatment compared with calves fed the CON treatment. Although the mode of action warrants further investigation, these data suggest that feeding an exogenous fibrolytic enzyme product may be beneficial for growing bison calves, likely in part because of greater apparent nutrient digestibility.

PSIII-5 Endosperm Hardness in Corn Affects the Digestibility of Energy and Fiber, and Increased Drying Temperature Reduces Amino Acid Digestibility

Abstract Two experiments were conducted to test the hypothesis that corn source and drying temperature influence the ileal digestibility of starch and amino acids (AA), as well as apparent total tract digestibility (ATTD) of gross energy (GE) and total dietary fiber (TDF) in diets for growing pigs. Two corn sources (i.e., soft or hard endosperm) were procured, and sources were divided into two drying batches (i.e., 35 or 120 oC). Therefore, four corn sources were used. In experiment 1, ten pigs (67.00 ± 2.98 kg) with a T-cannula installed in the distal ileum were allotted to a replicated 5 × 5 Latin square design with five diets and five periods giving ten replicates per diet. A nitrogen-free diet and four diets containing each source of corn as the only AA source were formulated. Data were analyzed in a 2 × 2 factorial arrangement of treatments using the MIXED procedure of SAS. The model included corn source, drying temperature, and the interaction between corn source and drying temperature. Results indicated that neither source nor drying temperature influenced the apparent ileal digestibility of starch in corn (Table 1), but the standardized ileal digestibility of most AA was less (P &amp;lt; 0.05) in corn dried at 120 oC compared with corn dried at 35 oC. In experiment 2, 40 pigs (20.82 ± 1.74 kg) were housed in metabolism crates and allotted to four diets with ten replicate pigs per diet. The four corn-based diets used in experiment 1 were also used in experiment 2. Feces and urine were collected using the marker-to-marker approach with 5-day adaptation and 4-day collection periods. Data were analyzed as explained for experiment 1. Results indicated that diets containing hard endosperm corn had greater (P &amp;lt; 0.05) ATTD of TDF compared with diets containing soft endosperm corn. The ATTD of GE and the concentration of metabolizable energy (ME) in hard endosperm corn were also greater (P &amp;lt; 0.05) compared with soft endosperm corn. Diets containing corn dried at 120 oC had greater (P &amp;lt; 0.05) ATTD of TDF compared with diets containing corn dried at 35 oC, but drying temperature did not influence ATTD of GE or ME. In conclusion, endosperm hardness did not influence the digestibility of AA and starch; however, drying corn at 120 oC resulted in reduced digestibility of AA. Hard endosperm corn had greater ATTD of GE and TDF, but drying temperature did not influence energy digestibility.

303 Interactive Effects of Pelleting and Particle Size Reduction of Corn on Ileal Digestibility of Starch and Amino Acids in Corn-Soybean Meal Diets Fed to Pigs

Abstract The objective was to determine the interactive effects of particle size reduction and pelleting on the apparent ileal digestibility (AID) of starch and the standardized ileal digestibility (SID) of amino acids (AA) in corn-soybean meal diets fed to pigs. Six corn-soybean meal based diets were arranged in a 3 × 2 factorial with 3 particle sizes of corn (i.e., 700, 500, or 300 μm) and 2 diet forms (i.e., meal or pelleted). An N-free diet was also used and there were, therefore, a total of 7 diets. Pigs were allowed ad libitum access to feed and water. Pigs (n = 7; initial body weight = 59.30 kg; SD = 2.77) that were equipped with a T-cannula in the distal ileum were allotted to the 7 diets using a 7 × 7 Latin square design with 7 periods. Ileal digesta were collected for 2 days after 5 days of adaptation. The statistical model included diet as fixed effect and pig and period as random effects. Contrast coefficients were used to determine effects of diet form, linear effects of particle size, and the interaction. Results indicated that the AID of starch was linearly increased (P = 0.001) with reduced particle size of corn and pelleted diets had greater (P = 0.029) AID of starch than meal diets (Table 1). The SID of Leu, Lys, Met, Phe, Thr, and Val linearly increased with reducing particle size, but the increase was greater in pelleted diets than in meal diets (interaction, P &amp;lt; 0.05). The SID of Arg, His, Ile, and Val also linearly increased (P &amp;lt; 0.05) as the particle size of corn was reduced, and the SID of all indispensable AA except Trp was greater (P &amp;lt; 0.05) in pelleted diets than in meal diets. In conclusion, reducing the particle size of corn from 700 to 300 μm increased the AID of starch and the SID of AA, but the AID of starch and the SID of most indispensable AA was greater in pelleted diets than in meal diets. If there were interactions, the effects of reducing particle size were greater when corn particle size was reduced from 500 to 300 μm in meal diets and from 700 to 500 μm in pelleted diets.

301 Effects of Different Sources and Particle Sizes of Field Peas on Ileal Digestibility of Amino Acids and Starch by Growing Pigs

Abstract The objective was to test the hypothesis that particle size and origin influence the apparent ileal digestibility (AID) of starch and the standardized ileal digestibility (SID) of amino acids (AA) in field peas. Three sources of field peas were procured. One source was from the U.S. and 2 sources were from Canada. The U.S. source and 1 of the sources from Canada (i.e., Canada 1) were each divided into 2 batches and ground at 200 or 400 µm, whereas the other source from Canada (i.e., Canada 2) was only ground at 200 µm. Each source of field peas was included in one diet as the only source of AA. An N-free diet was used to determine the basal endogenous losses of crude protein (CP) and AA. Barrows (n = 6; initial body weight: 50.5 kg; SD = 3.7) that had a T-cannula installed in the distal ileum were randomly allotted to a 6 × 6 Latin square design with 6 diets and six 7-d periods. Ileal digesta from pigs were collected for 2 days after 5 days of adaptation. The statistical model included source as the fixed effect and animal and period as the random effects. Contrast statements were used to analyze effects of particle size, origin, and the interaction between particle size and origin. Results indicated that the AID of starch was increased by reducing the particle size of the U.S. source, but that was not the case for the Canada 1 source (interaction; P &amp;lt; 0.001; Table 1). No interactions were observed for the SID of CP or AA. The SID of CP and AA was not affected by particle size of field peas. The SID of CP and Trp was greater (P &amp;lt; 0.05) and the SID of His, Ile, and Thr tended to be greater in the Canada 2 source (P &amp;lt; 0.10) than in the U.S. source. In conclusion, a few differences in the SID of AA in field peas produced in the U.S. or Canada were observed, but there was no effect on SID of AA of reducing the particle size of field peas from 400 to 200 µm. However, the effect of particle size on the AID of starch was greater in field peas from the U.S. compared with field peas from Canada.

Effects of Supplementation of a Mycotoxin Mitigation Feed Additive in Lactating Dairy Cows Fed Fusarium Mycotoxin-Contaminated Diet for an Extended Period.

Fusarium mycotoxins are inactivated by rumen flora; however, a certain amount can pass the rumen and reticulum or be converted into biological active metabolites. Limited scientific evidence is available on the impact and mitigation of Fusarium mycotoxins on dairy cows' performance and health, particularly when cows are exposed for an extended period (more than 2 months). The available information related to these mycotoxin effects on milk cheese-making parameters is also very poor. The objective of this study was to evaluate a commercially available mycotoxin mitigation product (MMP, i.e., TOXO® HP-R, Selko, Tilburg, The Netherlands) in lactating dairy cows fed a Fusarium mycotoxin-contaminated diet, and the repercussions on the dry matter intake, milk yield, milk quality, cheese-making traits and health status of cows. The MMP contains smectite clays, yeast cell walls and antioxidants. In the study, 36 lactating Holstein cows were grouped based on the number of days of producing milk, milk yield, body condition score and those randomly assigned to specific treatments. The study ran over 2 periods (March/May-May/July 2022). In each period, six animals/treatment were considered. The experimental periods consisted of 9 days of adaptation and 54 days of exposure. The physical activity, rumination time, daily milk production and milk quality were measured. The cows were fed once daily with the same total mixed ration (TMR) composition. The experimental groups consisted of a control (CTR) diet, with a TMR with low contamination, high moisture corn (HMC), and beet pulp; a mycotoxins (MTX) diet, with a TMR with highly contaminated HMC, and beet pulp; and an MTX diet supplemented with 100 g/cow/day of the mycotoxin mitigation product (MMP). The trial has shown that the use of MMP reduced the mycotoxin's negative effects on the milk yield and quality (protein, casein and lactose). The MTX diet had a lower milk yield and feed efficiency than the CTR and MMP HP-R diets. The MMP limited the negative effect of mycotoxin contamination on clotting parameters, mitigating the variations on some coagulation properties; however, the MMP inclusion tended to decrease the protein and apparent starch digestibility of the diet. These results provide a better understanding of mycotoxin risk on dairy cows' performances and milk quality. The inclusion of an MMP product mitigated some negative effects of the Fusarium mycotoxin contamination during this trial. The major effects were on the milk yield and quality in both the experimental periods. These results provide better insight on the effects of mycotoxins on the performance and quality of milk, as well as the cheese-making traits. Further analyses should be carried out to evaluate MMP's outcome on immune-metabolic responses and diet digestibility.

Lactation performance, milk fat output, and nutrient digestibility responses to the addition of liquid molasses or yeast culture in dairy cows fed super-conditioned corn

Increased diet fermentability may decrease ruminal pH and fiber digestibility, and increase the flow of trans fatty acids (FA) to the lower tract ultimately leading to milk fat depression. We recently showed that feeding super-conditioned corn, a new method of corn processing (95°C for 6 min in super-conditioner) for ruminants has potential to the reduction in milk fat yield caused by changes in ruminal pH and increased trans FA in milk fat. Supplementing yeast culture (YC) and replacing starch with sugar sources in diet can counteract the negative effects of high fermentable diets by improving ruminal pH and milk fat output. This study aimed to evaluate the effect of feeding beet liquid molasses (LM) and YC on intake and total-tract digestibility of nutrients, milk yield and composition, ruminal fermentation, milk FA profile, and plasma concentrations of glucose, nonesterified FA, β-hydroxybutyric acid, and urea N in early-lactation dairy cows fed high-starch diets containing super-conditioned corn. Twelve primiparous and 18 multiparous Holstein cows (mean ± SD; 67 ± 12 d in milk and 42 ± 2.1 kg of milk at the beginning of the experiment) were blocked by parity, pre-experimental milk yield, and DIM. Cows were used in a randomized complete block design experiment with 14 d as covariate period and 37 d for the experimental period. The following dietary treatments were fed as total mixed rations: (1) control diet (CTRL = no YC or LM supplementation), (2) LM supplementation at 5% of the diet dry matter (MOL diet), and (3) CTRL supplemented with 10 g/d of YC (YST diet). Diets were formulated to be isonitrogenous and isoenergetic. Intake of nutrients and apparent total-tract digestibility of crude protein and starch did not change across treatments. In contrast, cows fed the YST diet had the greatest apparent total-tract digestibility of dry matter, organic matter and neutral detergent fiber. Compared with the CTRL diet, yield of 4% FCM increased by 2.4 and 1.8 kg in cows fed MOL or YST, respectively. The ruminal molar proportions of acetate and butyrate increased in cows fed the YST or MOL diets, respectively, but the proportion of ruminal propionate was not affected by treatments. Milk fat concentration increased by supplementing both LM and YC and the milk yield of total trans-18:1 dropped by 45% and 18% relative to CTRL with MOL or YST diets, respectively. While the MOL diet increased the milk proportion and yield of de novo FA, no treatment effects were observed for the proportion and yield of preformed FA in the milk fat. Apart from β-hydroxybutyric acid concentration in plasma, which was greatest in cows fed MOL, remaining blood metabolites were not affected by treatments. Overall, MOL and YST diets increased 4% FCM and milk fat concentration and reduced the proportion of total trans-18:1 FA in milk fat in cows fed a concentrate based on super-conditioned corn. These responses were associated with increased ruminal pH and the molar proportions of acetate and butyrate with feeding the MOL and YST diets.

Effects of corn silage and grain expressing α-amylase on ruminal nutrient digestibility, microbial protein synthesis, and enteric methane emissions in lactating cows

Increasing ruminal starch digestibility has the potential to improve microbial protein synthesis (MPS), milk production, and feed efficiency. Enogen corn (Syngenta Seeds LLC) expresses high α-amylase activity, and we evaluated effects of Enogen corn silage (CS) and grain (CG) on ruminal starch digestibility, MPS, and milk production in lactating dairy cows. Fifteen Holstein cows (6 ruminally cannulated and 9 noncannulated; average ± standard deviation at the beginning of the trial: 170 ± 40 d in milk; milk yield, 37.2 ± 7.73 kg/d; body weight, 714 ± 37 kg) were used in a replicated 3 × 3 Latin square design (28 d per period) with 3 treatments: a diet containing isoline CS and CG (control, CON); a diet with Enogen CS and isoline CG (ECS); and a diet with Enogen CS and CG (ECSCG). Dry matter (DM; 30%), starch (35% of DM), and particle size distribution of the isoline and Enogen CS were similar. However, the mean particle size of Enogen CG was larger (1.05 vs. 0.65 mm) than that of the isoline CG. Cannulated cows were used for digestibility and nutrient flow measurements, noncannulated cows were used for enteric CH4 measurements, and all cows were used for production evaluation. Dry matter intake (DMI) and milk yield were greater for ECS and ECSCG compared with CON (26.7 and 26.6 vs. 25.1 kg/d and 36.5 and 34.1 vs. 33.1 kg/d, respectively) without a difference between ECS and ECSCG. Milk protein yield was greater (1.27 vs. 1.14 and 1.17 kg/d) for ECS compared with CON and ECSCG. Milk fat content was greater (3.79 vs. 3.32%) for ECSCG compared with ECS. Milk fat yield and energy-corrected milk did not differ among treatments. Ruminal digestibilities of DM, organic matter, starch, and neutral detergent fiber were not different among treatments. However, ruminal digestibility of nonammonia, nonmicrobial N was greater (85 vs. 75%) for ECS compared with ECSCG. Total-tract apparent starch digestibility was lower (97.6 and 97.1 vs. 98.3%) for ECS and ECSCG compared with CON, respectively, and tended to be lower (97.1 vs. 98.3%) for ECSCG compared with ECS. Ruminal outflows of bacterial OM and nonammonia N tended to be greater for ECS than for ECSCG. Efficiency of MPS tended to be greater (34.1 vs. 30.6 g of N/kg of organic matter truly digested) for ECS versus ECSCG. Ruminal pH and total and individual short-chain fatty acid concentrations did not differ among treatments. Concentration of ruminal NH3 for ECS and ECSCG was lower (10.4 and 12.4 vs. 13.4 mmol/L, respectively) compared with CON. Methane per unit of DMI decreased for ECS and ECSCG compared with CON (11.4 and 12.2 vs. 13.5 g/kg of DMI, respectively) without a difference between ECS and ECSCG. In conclusion, ECS and ECSCG did not increase ruminal or total-tract starch digestibility. However, the positive effects of ECS and ECSCG on milk protein yield, milk yield, and CH4 per unit of DMI may show potential benefits of feeding Enogen corn. Effects of ECSCG were not apparent when compared with ECS, partly due to larger particle size of Enogen CG compared with its isoline counterpart.

Effects of Processing Methods and Conditioning Temperatures on the Cassava Starch Digestibility and Growth Performance of Broilers.

As an important food crop, cassava is rich in nutrients and high in starch content and is widely used in the production of industrial raw materials. However, the utilization value of cassava is limited due to the reduction of planting area and the existence of anti-nutritional factors. Therefore, we evaluated in vitro cassava starch digestibility and in vivo growth performance of broilers in a 3 × 3 factorial arrangement of treatments using three processing methods (mechanical crushing (MC), steam conditioning (SC), and puffing conditioning (PU)) and three conditioning temperatures (60, 75, and 90 °C) to screen for the optimal processing method and conditioning temperature to improve the utilization of cassava. In the in vitro cassava starch digestion study, the digestibility and digestion rate (p < 0.01) were higher at conditioned 90 °C than that at 60 or 75 °C, and PU was higher than SC and MC (p < 0.01) (0.25-2 h). The amylose content and amylose/amylopectin at conditioned 60 °C or PU were lower (p < 0.01) than that of 75 or 90 °C or SC, whereas the opposite was true for amylopectin content (p < 0.01). The resistant starch content of SC or PU was lower (p < 0.01) than MC. In the in vivo study, broilers fed diets conditioned at 60 °C or SC had a lower (p < 0.05) feed-to-gain ratio than those fed diets conditioned at 90 °C or PU diets. The ileum apparent digestibility of starch and AME were higher (p < 0.05) for broilers fed SC diets than for those fed MC diets. These results indicate that cassava starch promoted starch digestion rate by reducing amylose content and amylose/amylose under PU combined with a conditioning temperature of 60 °C, ileum digestibility of starch in broilers fed SC diets was higher than MC diets regardless of conditioning temperature, and SC diets increased AME and decreased F/G to promote growth performance of broilers.

Effect of low dietary concentrations of Acacia mearnsii tannin extract on chewing, ruminal fermentation, digestibility, nitrogen partition, and performance of dairy cows

The supplementation of dairy cows with tannins can reduce the ruminal degradation of dietary protein and urine N excretion, but high concentration in the diet can impair ruminal function, diet digestibility, feed intake, and milk yield. This study evaluated the effect of low concentrations (0, 0.14, 0.29, or 0.43% of diet in DM basis) of a tannin extract from the bark of Acacia mearnsii (TA) on milking performance, dry matter intake (DMI), digestibility, chewing behavior, ruminal fermentation, and N partition of dairy cows. Twenty Holstein cows (34.7 ± 4.8 kg/d, 590 ± 89 kg, and 78 ± 33 d in lactation) were individually fed a sequence of 4 treatments in 5, 4 × 4 Latin squares (with 21-d treatment periods, each with a 14-d adaptation period). The TA replaced citrus pulp in the total mixed ration and other feed ingredients were kept constant. Diets had 17.1% crude protein, mostly from soybean meal and alfalfa haylage. The TA had no detected effect on DMI (22.1 kg/d), milk yield (33.5 kg/d), and milk components. The proportions in milk fat of mixed origin fatty acids (16C and 17C) and the daily secretion of unsaturated fatty acids were linearly reduced and the proportion of de novo fatty acids was increased by TA. Cows fed TA had linear increase in the molar proportion of butyrate and linear reduction in propionate in ruminal fluid, whereas acetate did not differ. There was a tendency for the ratio of acetate to propionate to be linearly increased by TA. Cows fed TA had a linear reduction in the relative ruminal microbial yield, estimated by the concentrations of allantoin and creatinine in urine and body weight. The total-tract apparent digestibility of neutral detergent fiber, starch, and crude protein also did not differ. The TA induced a linear increase in meal size and duration of the first daily meal and reduced meal frequency. Rumination behavior did not differ with treatment. Cows fed 0.43% TA selected against feed particles >19 mm in the morning. There were tendencies for linear decreases in milk urea N (16.1-17.3 mg/dL), urine N (153-168 g/d and 25.5-28.7% of N intake), and plasma urea N at 6, 18, and 21 h postmorning feeding, and plasma urea N 12 h postfeeding was reduced by TA. The proportion of N intake in milk (27.1%) and feces (21.4%) did not differ with treatment. Reductions in urine N excretion and milk and plasma urea N suggest that TA reduced ruminal AA deamination, whereas lactation performance did not differ. Overall, TA up to 0.43% of DM did not affect DMI and lactation performance, while there was a tendency to reduce urine N excretion.

Effects of isoquinoline alkaloids on apparent ileal digestibility of amino acids, crude protein, starch, and acid hydrolyzed ether extract and apparent total tract digestibility of energy and crude protein by growing and finishing pigs fed corn-soybean meal diets

Two experiments were conducted to test the hypotheses that a preparation of isoquinoline alkaloids (IQ) obtained from Macleaya cordata included in corn-soybean meal (SBM) diets increases apparent ileal digestibility (AID) of nutrients, increases apparent total tract digestibility (ATTD) of gross energy (GE) and crude protein (CP) and increases plasma amino acids (AA) and protein when fed to growing or finishing pigs. Experiment 1 utilized 12 barrows (body weight: 27.1 ± 2.10 kg) equipped with a T-cannula in the distal ileum, which were allotted to 4 treatments and 4 periods for 12 replicates per treatment. Treatments included a corn-SBM basal diet and three diets formulated by adding 40, 80, or 160 mg/kg of IQ to the basal diet. In experiment 2, twelve T-cannulated barrows (BW: 77.2 ± 6.23 kg) were allotted to the same treatments as in experiment 1, but diets were fed for 3 periods for a total of 9 replicate pigs per treatment. Each period had a 10-day adaptation period, followed by fecal sample collection on day 11 and 12, and ileal digesta collection on day 13 and 14. Results indicated that AID of some AA increased when IQ was included at 40 or 160 mg/kg in experiment 1, but a reduction (P < 0.05) in the AID of acid-hydrolyzed ether extract (AEE) and starch was observed at 80 mg/kg IQ. Including 80 mg/kg IQ to diets in experiment 2 increased the AID of CP, whereas 40 mg/kg IQ resulted in an increased (P < 0.05) AID of His, Met, and Pro, and a tendency (P < 0.10) for an increase in AID of Ile, Leu, Lys, Cys, Gly, and Tyr. The ATTD of CP was also increased (P < 0.05) if the diet containing 80 mg/kg IQ was fed in experiment 2. Albumin was reduced (P < 0.05) in plasma of finishing pigs fed 40 mg/kg IQ in experiment 2. Including 80 mg/kg IQ in a diet for growing pigs increased (P < 0.05) plasma Lys, and adding 80 or 160 mg/kg increased (P < 0.05) plasma Asp, but a reduction (P < 0.05) in some plasma AA as 160 mg/kg IQ was added to diets for finishing pigs was observed. In conclusion, IQ may be added to diets for growing and finishing pigs to increase the AID of AA and CP, with optimal results observed at inclusion levels of between 40 and 80 mg/kg IQ.