TY - JOUR
AU1 - Kpogo, Agbee L
AU2 - Jose, Jismol
AU3 - Panisson, Josiane C
AU4 - Agyekum, Atta K
AU5 - Predicala, Bernardo Z
AU6 - Alvarado, Alvin C
AU7 - Agnew, Joy M
AU8 - Sprenger, Charley J
AU9 - Beaulieu, A Denise
AB - Abstract The objective of this project was to determine the impact of feeding growing pigs with high wheat millrun diets supplemented with a multi-carbohydrase enzyme (amylase, cellulase, glucanase, xylanase, and invertase activities) on nutrient digestibility, growth performance, and greenhouse gas (GHG) output (carbon dioxide, CO2; nitrous oxide, N2O; methane, CH4). Three experiments were conducted utilizing six treatments arranged as a 3 × 2 factorial (0%, 15%, or 30% wheat millrun; with or without enzyme) for the digestibility experiment or as a 2 × 2 factorial (0% or 30% wheat millrun; with or without enzyme) for the performance and GHG experiments. The digestibility, performance, and GHG experiments utilized 48 individually housed pigs, 180 pigs housed 5 per pen, or 96 pigs housed 6 per chamber, respectively. Increasing wheat millrun up to 30% in the diet of growing pigs resulted in decreased energy, nitrogen (N) and phosphorus (P) apparent total tract digestibility and net energy content (P < 0.01). Overall, average daily gain (ADG) and gain to feed ratio were reduced in pigs fed wheat millrun (P < 0.05). Enzyme supplementation had minimal effects on the digestibility or performance parameters measured. Feeding diets with 30% millrun did not affect GHG output (CH4: 4.7 and 4.9; N2O: 0.45 and 0.42; CO2: 1,610 and 1,711 mg/s without or with millrun inclusion, respectively; P > 0.78). Enzyme supplementation had no effect on GHG emissions (CH4: 4.5 and 5.1; N2O: 0.46 and 0.42; CO2: 1,808 and 1,513 mg/s without or with enzymes, respectively; P > 0.51). Overall, the carbohydrase enzyme had minimal effects on parameters measured, regardless of wheat millrun inclusion (P > 0.10). Although energy, N and P digestibility, and ADG were reduced, the inclusion of up to 30% wheat millrun in the diet has no effect on GHG emissions from growing pigs (P > 0.10). Introduction Wheat millrun is a coproduct that is readily available and commonly used in North America, especially western Canada (Nortey et al., 2007). It is obtained after removing the endosperm during wheat milling; hence, it is high in nonstarch polysaccharides (NSP; Slominski et al., 2004; Woyengo et al., 2014). Current efforts to reduce production costs have resulted in increased usage of coproducts such as wheat millrun and wheat bran for swine feed (Zijlstra and Beltranena, 2013). Pigs do not have the digestive enzymes required to hydrolyze NSP, limiting the availability of nutrients from these ingredients (Barrera et al., 2004; Woyengo and Nyachoti, 2011; Agyekum and Nyachoti, 2017). Some improvement in nutritional quality may be achieved by adding enzymes (NSP enzymes/carbohydrases) that break down the cell wall barrier to release unavailable or bound nutrients (Bedford, 2000). Carbohydrases may increase the energy value of an ingredient, reduce the undigested organic matter in the feces, and make the inclusion of low-quality raw materials possible (Paloheimo et al., 2010). Additive or synergistic responses when two or more carbohydrases are combined have been observed (Adeola and Cowieson, 2011; Zeng et al., 2018). Pig production accounts for only 9% of GHG emissions from the livestock sector (Gerber et al., 2013). However, if the expected growth in global pork production is achieved, GHG emissions could increase considerably and mitigation efforts should be considered. Conceivably, the use of high-fiber coproducts may result in increased greenhouse gas (GHG) emissions, especially CH4, from the barn due to increased fermentation in the large intestine (Philippe and Nicks, 2015). GHG emissions from high-fiber diets are influenced by the fermentability and solubility of the dietary fiber (Philippe and Nicks, 2015). For example, more energy from CH4 was lost when sows were fed diets that contained sugar beet pulp than those containing wheat bran, and this was attributed to the higher digestibility of the sugar beet pulp than the wheat bran (Le Goff et al., 2002). It is apparent that interventions allowing a reduction in GHG emissions while including coproducts into swine diets will be very beneficial to the pork industry. This study was designed to determine the impact of wheat millrun supplemented with a multi-carbohydrase enzyme on growth performance, nutrient digestibility, and GHG emissions in pigs. We hypothesized that wheat millrun addition would decrease performance and nutrient digestibility and increase GHG emissions and that the carbohydrase enzyme would mitigate these negative effects. Materials and Methods Animal protocols were reviewed and approved by the Animal Research Ethics Board at the University of Saskatchewan for compliance with principles established by the Canadian Council on Animal Care Guidelines for Humane Animal Use (CCAC, 2009). Animals and experimental diets Diets (Table 1) were designed to be typical of those fed in western Canada and were formulated using published standardized ileal digestible (SID) and net energy (NE) values to meet or exceed the nutrient requirements for growing-finishing pigs (NRC, 2012). Wheat millrun was included at the expense of wheat. The NE content was allowed to decrease with the increase in wheat millrun inclusion (from 2.46 to 2.34 Mcal NE/kg). The enzyme comprised of 300 units of glucanase, 1,000 units of xylanase, 1,900 units of cellulase, 4,200 units of amylase, and 150 units of invertase per gram of enzyme (Superzyme-W; Canadian Bio-Systems Inc., Calgary, AB, Canada)—was added at the manufacturer recommended dose of 1 kg/tonne of finished feed. Diets used for exp. 1 contained 0.4% celite (IMCD Canada, Brampton, ON). Experiment 1 utilized six treatments, arranged as a 3 × 2 factorial in a randomized complete block design (RCBD) with wheat millrun 0%, 15%, or 30% and enzyme 0 or 1 mg/kg as main factors. Experiments 2 and 3 utilized four treatments, arranged as a 2 × 2 factorial in an RCBD, with 0% and 30% wheat millrun, with and without the multi-carbohydrase enzyme. Table 1. Ingredient and nutrient composition (as-fed basis) of the wheat millrun inclusion diets for the performance,1,2 greenhouse gas emission,1,2 and the digestibility study2 Item . 0% . 15% . 30% . Ingredients,%  Wheat millrun — 15.00 30.00  Wheat 61.85 47.78 33.70  Barley 24.80 24.96 25.11  Canola oil 1.50 1.60 1.70  Soybean meal 9.00 8.00 7.00  Limestone 1.20 1.20 1.20  Monocalcium phosphate 0.30 0.15 —  Salt 0.30 0.30 0.30  l-Lysine HCl, 78% 0.34 0.31 0.28  dl-Methionine, 99% 0.03 0.03 0.03  l-Threonine, 98.5% 0.08 0.08 0.08  Vitamin and mineral premix3 0.20 0.20 0.20  Celite 0.40 0.40 0.40 Analyzed nutrient composition  Dry matter, % 92.28 92.15 92.00  Crude protein, % 17.11 18.00 18.64  Gross energy, Mcal kg−1 3.84 3.88 3.86  Ether extract, % 2.60 3.97 4.04  Calcium, % 0.63 0.67 0.72  Phosphorus, % 0.46 0.50 0.56  Soluble dietary fiber,% 3.18 2.78 4.28  Insoluble dietary fiber,% 12.94 14.80 17.51  Total dietary fiber, % 16.12 17.57 21.80 Indispensable amino acids, %  Lysine 0.92 0.89 0.88  Methionine 0.28 0.16 0.14  Threonine 0.58 0.55 0.50  Trypthophan 0.67 0.54 0.54  Arginine 0.84 0.65 0.57  Histidine 0.43 0.42 0.39  Isoleucine 0.67 0.69 0.65  Leucine 1.21 1.24 1.15  Phenylalanine 0.81 0.85 0.76  Valine 0.87 0.86 0.82 Dispensable amino acids, %  Alanine 0.73 0.67 0.69  Aspartic acid 1.10 1.00 1.01  Cystine 0.32 0.21 0.18  Glutamic acid 3.10 3.86 3.67  Glycine 1.30 1.18 1.15  Proline 1.33 1.41 1.28  Serine 0.67 0.65 0.58  Tyrosine 2.01 2.42 2.31 Net energy, Mcal kg−1 (Calculated) 2.43 2.39 2.35 Item . 0% . 15% . 30% . Ingredients,%  Wheat millrun — 15.00 30.00  Wheat 61.85 47.78 33.70  Barley 24.80 24.96 25.11  Canola oil 1.50 1.60 1.70  Soybean meal 9.00 8.00 7.00  Limestone 1.20 1.20 1.20  Monocalcium phosphate 0.30 0.15 —  Salt 0.30 0.30 0.30  l-Lysine HCl, 78% 0.34 0.31 0.28  dl-Methionine, 99% 0.03 0.03 0.03  l-Threonine, 98.5% 0.08 0.08 0.08  Vitamin and mineral premix3 0.20 0.20 0.20  Celite 0.40 0.40 0.40 Analyzed nutrient composition  Dry matter, % 92.28 92.15 92.00  Crude protein, % 17.11 18.00 18.64  Gross energy, Mcal kg−1 3.84 3.88 3.86  Ether extract, % 2.60 3.97 4.04  Calcium, % 0.63 0.67 0.72  Phosphorus, % 0.46 0.50 0.56  Soluble dietary fiber,% 3.18 2.78 4.28  Insoluble dietary fiber,% 12.94 14.80 17.51  Total dietary fiber, % 16.12 17.57 21.80 Indispensable amino acids, %  Lysine 0.92 0.89 0.88  Methionine 0.28 0.16 0.14  Threonine 0.58 0.55 0.50  Trypthophan 0.67 0.54 0.54  Arginine 0.84 0.65 0.57  Histidine 0.43 0.42 0.39  Isoleucine 0.67 0.69 0.65  Leucine 1.21 1.24 1.15  Phenylalanine 0.81 0.85 0.76  Valine 0.87 0.86 0.82 Dispensable amino acids, %  Alanine 0.73 0.67 0.69  Aspartic acid 1.10 1.00 1.01  Cystine 0.32 0.21 0.18  Glutamic acid 3.10 3.86 3.67  Glycine 1.30 1.18 1.15  Proline 1.33 1.41 1.28  Serine 0.67 0.65 0.58  Tyrosine 2.01 2.42 2.31 Net energy, Mcal kg−1 (Calculated) 2.43 2.39 2.35 1Studies used 0% and 30% diets only. 2Each diet was divided into two portions and supplemented with a multi-carbohydrase enzyme (0.1%) to create three additional diets. The enzyme contained 300 units of glucanase, 1,000 units of xylanase, 1,900 units of cellulase, 4,200 units of amylase, and 150 units of invertase per gram of enzyme (Superzyme-W; Canadian Bio-Systems Inc., Calgary, AB, Canada). 3Supplied vitamins and minerals per kilogram of complete diet: vitamin A, 8,000 IU; vitamin D, 1,500 IU; vitamin E, 30 IU; vitamin B12, 0.02 mg; menadione, 2 mg; thiamine, 1 mg; biotin, 0.1 mg; niacin, 20 mg; riboflavin, 12 mg; pantothenate, 12 mg; folic acid, 0.50 mg; pyridoxine, 2 mg; iron, 100 mg; zinc, 100 mg; manganese, 40 mg; copper, 15 mg; selenium, 0.30 mg; and iodine, 1 mg. Open in new tab Table 1. Ingredient and nutrient composition (as-fed basis) of the wheat millrun inclusion diets for the performance,1,2 greenhouse gas emission,1,2 and the digestibility study2 Item . 0% . 15% . 30% . Ingredients,%  Wheat millrun — 15.00 30.00  Wheat 61.85 47.78 33.70  Barley 24.80 24.96 25.11  Canola oil 1.50 1.60 1.70  Soybean meal 9.00 8.00 7.00  Limestone 1.20 1.20 1.20  Monocalcium phosphate 0.30 0.15 —  Salt 0.30 0.30 0.30  l-Lysine HCl, 78% 0.34 0.31 0.28  dl-Methionine, 99% 0.03 0.03 0.03  l-Threonine, 98.5% 0.08 0.08 0.08  Vitamin and mineral premix3 0.20 0.20 0.20  Celite 0.40 0.40 0.40 Analyzed nutrient composition  Dry matter, % 92.28 92.15 92.00  Crude protein, % 17.11 18.00 18.64  Gross energy, Mcal kg−1 3.84 3.88 3.86  Ether extract, % 2.60 3.97 4.04  Calcium, % 0.63 0.67 0.72  Phosphorus, % 0.46 0.50 0.56  Soluble dietary fiber,% 3.18 2.78 4.28  Insoluble dietary fiber,% 12.94 14.80 17.51  Total dietary fiber, % 16.12 17.57 21.80 Indispensable amino acids, %  Lysine 0.92 0.89 0.88  Methionine 0.28 0.16 0.14  Threonine 0.58 0.55 0.50  Trypthophan 0.67 0.54 0.54  Arginine 0.84 0.65 0.57  Histidine 0.43 0.42 0.39  Isoleucine 0.67 0.69 0.65  Leucine 1.21 1.24 1.15  Phenylalanine 0.81 0.85 0.76  Valine 0.87 0.86 0.82 Dispensable amino acids, %  Alanine 0.73 0.67 0.69  Aspartic acid 1.10 1.00 1.01  Cystine 0.32 0.21 0.18  Glutamic acid 3.10 3.86 3.67  Glycine 1.30 1.18 1.15  Proline 1.33 1.41 1.28  Serine 0.67 0.65 0.58  Tyrosine 2.01 2.42 2.31 Net energy, Mcal kg−1 (Calculated) 2.43 2.39 2.35 Item . 0% . 15% . 30% . Ingredients,%  Wheat millrun — 15.00 30.00  Wheat 61.85 47.78 33.70  Barley 24.80 24.96 25.11  Canola oil 1.50 1.60 1.70  Soybean meal 9.00 8.00 7.00  Limestone 1.20 1.20 1.20  Monocalcium phosphate 0.30 0.15 —  Salt 0.30 0.30 0.30  l-Lysine HCl, 78% 0.34 0.31 0.28  dl-Methionine, 99% 0.03 0.03 0.03  l-Threonine, 98.5% 0.08 0.08 0.08  Vitamin and mineral premix3 0.20 0.20 0.20  Celite 0.40 0.40 0.40 Analyzed nutrient composition  Dry matter, % 92.28 92.15 92.00  Crude protein, % 17.11 18.00 18.64  Gross energy, Mcal kg−1 3.84 3.88 3.86  Ether extract, % 2.60 3.97 4.04  Calcium, % 0.63 0.67 0.72  Phosphorus, % 0.46 0.50 0.56  Soluble dietary fiber,% 3.18 2.78 4.28  Insoluble dietary fiber,% 12.94 14.80 17.51  Total dietary fiber, % 16.12 17.57 21.80 Indispensable amino acids, %  Lysine 0.92 0.89 0.88  Methionine 0.28 0.16 0.14  Threonine 0.58 0.55 0.50  Trypthophan 0.67 0.54 0.54  Arginine 0.84 0.65 0.57  Histidine 0.43 0.42 0.39  Isoleucine 0.67 0.69 0.65  Leucine 1.21 1.24 1.15  Phenylalanine 0.81 0.85 0.76  Valine 0.87 0.86 0.82 Dispensable amino acids, %  Alanine 0.73 0.67 0.69  Aspartic acid 1.10 1.00 1.01  Cystine 0.32 0.21 0.18  Glutamic acid 3.10 3.86 3.67  Glycine 1.30 1.18 1.15  Proline 1.33 1.41 1.28  Serine 0.67 0.65 0.58  Tyrosine 2.01 2.42 2.31 Net energy, Mcal kg−1 (Calculated) 2.43 2.39 2.35 1Studies used 0% and 30% diets only. 2Each diet was divided into two portions and supplemented with a multi-carbohydrase enzyme (0.1%) to create three additional diets. The enzyme contained 300 units of glucanase, 1,000 units of xylanase, 1,900 units of cellulase, 4,200 units of amylase, and 150 units of invertase per gram of enzyme (Superzyme-W; Canadian Bio-Systems Inc., Calgary, AB, Canada). 3Supplied vitamins and minerals per kilogram of complete diet: vitamin A, 8,000 IU; vitamin D, 1,500 IU; vitamin E, 30 IU; vitamin B12, 0.02 mg; menadione, 2 mg; thiamine, 1 mg; biotin, 0.1 mg; niacin, 20 mg; riboflavin, 12 mg; pantothenate, 12 mg; folic acid, 0.50 mg; pyridoxine, 2 mg; iron, 100 mg; zinc, 100 mg; manganese, 40 mg; copper, 15 mg; selenium, 0.30 mg; and iodine, 1 mg. Open in new tab Pigs (Camborough Plus females × C337 sires; PIC Canada Ltd., Winnipeg, MN, Canada) with an initial body weight (BW) of 60.2 ± 2.2 kg were used in the three experiments at the Prairie Swine Centre Inc. (Saskatoon, SK. Canada). Experiment 1: nutrient digestibility Forty-eight barrows were randomly assigned to one of the six dietary treatments in four blocks providing eight pigs per treatment. Pigs were housed individually in 1.5 × 1.5 m crates in an environmentally controlled room. Each crate was equipped with a single-space feeder and nipple drinker. Pigs were fed equivalent to three times maintenance energy requirements (197 kcal ME/kg BW0.60; NRC, 2012). The feed was divided into two equal meals and presented at 0830 and 1500 hours. Pigs were allowed free access to water throughout the experiment. Feed intake was recorded throughout the adaptation and collection periods, and individual BW was recorded before the adaptation period and the start and end of the collection period. Fecal samples were collected for 4 d following a 7-d period for diet adaptation. The fecal grab samples were collected at 0900 and 1530 hours, pooled by crate, and immediately frozen (−20 °C) for the duration of the collection period. Chemical analysis Fecal samples were dried in a forced-air draft oven at 55 °C for 72 h (Jacobs et al., 2011). The feed and oven-dried feces were then ground in a centrifugal mill (Model ZM 100, RETSCH GmBH & Co., Rheinische Straβe, Germany) through a 1-mm screen. The dry matter (DM) content of the feed and feces was measured by drying at 135 °C in an airflow-type oven for 2 h (method 930.15; AOAC 2007). Acid insoluble ash content was analyzed in both feed and feces, according to van Keulen and Young (1977). The gross energy content of the feed and feces was analyzed using an adiabatic bomb calorimeter (6400 automatic Isoperibol system, Parr Instruments Company, IL, USA) with benzoic acid as the standard. The total, insoluble, and soluble dietary fiber content of the feed was determined according to AOAC 991.43 (AOAC, 2007) using an ANKOM 200 fiber analyzer (ANKOM Technology, Macedon, NY, USA). Crude protein (CP; N × 6.25) content of the feed and feces was analyzed using combustion with an automatic analyzer (LECO FP 528, Saint Joseph, MI, USA; Method 990.3; AOAC, 2007). Phosphorus in feed and feces was analyzed by a colorimetric method using a spectrophotometer (method 965.17; AOAC, 2007). Calculations Apparent total tract digestibility (ATTD) of gross energy, N, P, and DM was calculated based on the indicator method using the following equation (Adeola, 2000): ATTD, % = [1 − (NF× MD)/ (ND× MF)] × 100(1) Where NF is the nutrient concentration in feces; ND is the nutrient concentration in the diet; MD is the marker concentration in the diet; and MF is the marker concentration in feces NE was estimated according to NRC (2012) using the following equation: NE = (0.700×DE)+(1.61×EE)+(0.48×Starch) −(0.91×CP)−(0.87×ADF)(2) Where DE is digestible energy, EE is ether extract, CP is crude protein, and ADF is acid detergent fiber. Experiment 2: growth performance A total of 180 pigs were housed in pens (2.4 × 1.7 m) in groups of five in an environmentally controlled room. Pigs were selected such that BW and SD were comparable among pens. Pens were randomly assigned to one of the four experimental diets providing three pens per treatment in each of three blocks (n = 9 pens per treatment). Within each block, an equal number of barrows and gilts of equal BW were used and equalized between treatments. Data collection Pigs were weighed individually and feed disappearance was determined on day 1 and at 14 d intervals until day 56. Pigs were marketed weekly and were sent to a commercial abattoir when they reached a minimum BW of 128 kg. Before loading, pigs were weighed and tattooed by pen. The journey from the barn to the abattoir required 8 h, and pigs were not fasted before shipping. Slaughter weight, fat, loin depth, and carcass yield were collected on each pig after slaughter. Experiment 3: GHG emissions Housing The study utilized 96 pigs randomly assigned to one of the four dietary treatments. Pigs were housed in two identical environmental chambers (Figure 1), with each chamber having a separate manure pit (collection tub) and ventilation. The interior of each chamber measured 4.2 × 3.6 × 2.7 m (L × W × H) with a pen for holding pigs within. The ceilings and internal walls were lined with stainless steel to eliminate emissions from these surfaces. The chambers were equipped with commercial feeders and nipple water drinkers. Each chamber operated on a negative pressure ventilation system. During the trial, fresh outdoor air entered the airspace through ceiling inlets and was conditioned to desired settings using an air-conditioning unit (Raka-060 CAZ, Setra Systems, Boxborough, MA, USA) or a 10 kW electric heater (Chromalox, Dimplex North America Ltd., Cambridge, ON, Canada). The pre-conditioned room air passed through a filtration unit (Circul-Aire USA-H204-B, Dectron International, Roswell, GA, USA) with a 0.6-m-diameter centrifugal fan (Delhi BIDI-20, Delhi Industries Inc., Delhi, ON, Canada) and entered the chambers through an actuated inlet located on the ceiling of each chamber. Air from each chamber was exhausted through one sidewall fan (H18, Del-Air Systems Inc., Humboldt, SK, Canada). Figure 1. Open in new tabDownload slide A schematic diagram of the chambers used to collect greenhouse gas from the pigs and manure (adapted from Alvarado, 2011). Figure 1. Open in new tabDownload slide A schematic diagram of the chambers used to collect greenhouse gas from the pigs and manure (adapted from Alvarado, 2011). A CO2 sensor (CM-0016, CO2meter.com, FL, USA) and a relative humidity/temperature sensor (Hobo U12-013, Onset Computer Corp., MA, USA) were installed on the ceiling in each chamber. Air velocity measurements were obtained at the air duct outlets with an ALNOR 501 anemometer (RVA501 Data Logging Vane Anemometer, TSI Incorporated, Shoreview, MA, USA). Water consumption in each chamber was measured at the drinker with meters (C700 polymer ABB, Atlantic Liquid Meters, ON, Canada) calibrated prior to experiment initiation. Experimental procedures A week prior to introduction to the chambers, groups of pigs (55 ± 2 kg BW) were selected, housed in groups, and fed their assigned treatment diet. This ensured that the pigs were adapted to the diets and limited aggression prior to going into the chambers. At the beginning of each of four replicates, six grower pigs of the same sex were brought into each chamber. The sexes were alternated between chambers and treatments. Feed and water were supplied ad libitum. The pigs were housed in the chambers for 14 d to allow for the stabilization of atmospheric gases prior to measurements on day 15. Temperature, relative humidity, and manure depth were recorded daily throughout the experiment. Gas emissions On day 15, air velocity measurements were taken before and after gas sampling to determine the airflow rate. Before gas collections, Tedlar bags (Saint-Gobain Chemware Tedlar, Fisher Scientific Company, Ottawa, ON, Canada) and Teflon tubes were flushed with clean air (Air ultra-zero, Praxair, Saskatoon, SK, Canada). Air samples were then pumped through Teflon tubes (approximately 0.4 cm internal diameter) from the chamber (close to the exhaust fans, ensuring that the air collected was representative of the air leaving the chamber) into Tedlar bags with the aid of a vacuum apparatus. Samples were then transferred to an Exetainer tube (Labco Ltd, Ceredigion, UK) using a 20-mL syringe with a needle inserted into the septum of the Tedlar bag and purged three times before withdrawing a 20-mL sample which was then injected through the septum of the 12-mL evacuated Exetainer tube. The following equations were used to calculate gas emissions: E= C × Q(3) Q = V × A(4) Where E = gas emissions (mg/s), C = gas concentration in room measured close to the exhaust duct (mg/m3), Q = volumetric airflow rate (m3/s), V = air speed (m/s), and A = exhaust fan duct area (m2). Gases (CO2, CH4, and N2O) were analyzed and quantified by gas chromatography (GC; Scion 456-GC, Scion Instruments, Livingston, UK) at the GHG laboratory in the Department of Soil Science, University of Saskatchewan. About 2 mL from the Exetainer tube was injected and gases were separated on a column packed with Hayesep N and Hayesep D polymers (HayeSeparations Inc. Bandera, TX); CO2 was detected using a thermal conductivity detector (120 °C), CH4 by flame ionization (120 °C), and N2O with electron capture (330 °C). Each analysis took 2 to 6 min. Injectors and oven temperature were maintained at 85 °C. Statistical analysis Statistical analyses for each experiment utilized an analysis of variance (ANOVA) for an RCBD with a factorial arrangement of treatments using the SAS mixed model procedure (version 9.4; SAS Institute, Inc. Cary, NC). The univariate procedure (Shapiro–Wilk test) of SAS was used to verify data normality. The digestibility data model included wheat millrun and the multi-carbohydrase enzyme and their interaction as fixed effects and block as a random effect; the pig was the experimental unit. The digestibility data were further analyzed for the linear effects of wheat millrun addition using the SAS GLM procedure. The model for growth performance and carcass characteristics data included wheat millrun and the multi-carbohydrase enzyme and their interaction as fixed effects, block as random effect, and pen as the experimental unit. Each chamber of six pigs was considered the experimental unit in the GHG emissions study. Significant differences between means were declared at P ≤ 0.05, and the tendency toward significance was considered at 0.05 < P ≤ 0.10. The Tukey–Kramer test was used to separate means that were declared significant. Results There were no interactions between wheat millrun inclusion and enzyme supplementation for any of the digestibility, performance, or GHG emission parameters measured. The main effects are, therefore, presented. Experiment 1: nutrient digestibility Data for ATTD for DM, nitrogen, energy, NE, DE, and P are presented in Table 2. The ATTD of DM, energy, N, and P were reduced linearly (P ≤ 0.05) with increasing wheat millrun inclusion. The ATTD of DM and energy was reduced with the addition of the enzyme (P < 0.05). Further, increasing the inclusion of wheat millrun in the diets linearly reduced the DE and NE contents of the diets (P < 0.05), while enzyme supplementation tended to reduce diet DE (P = 0.06) and NE content (P = 0.08). Enzyme supplementation, however, did not affect the ATTD of N or P (P > 0.10). Table 2. Effects of wheat millrun inclusion and multi-carbohydrase supplementation on apparent total tract digestibility of energy and minerals of diets fed to grower pigs (60 kg body weight) in the nutrient digestibility study1 Item . Millrun, % . . . SEM . Enzyme . . SEM . P-value2 . . . 0 . 15 . 30 . . No . Yes . . Enzyme . Linear (Millrun) . Total tract digestibility, %  Dry matter 86.5 84.7 83.9 0.28 87.3 82.8 0.22 <0.01 <0.01  Energy 87.3 84.9 81.5 0.01 85.0 84.2 0.01 0.05 <0.01  N 86.4 85.3 83.5 0.53 85.1 85.0 0.44 0.89 <0.01  P 52.6 43.5 41.1 0.60 46.2 45.2 0.52 0.33 0.02 Digestible energy, Mcal kg−1 3.50 3.47 3.34 0.01 3.45 3.42 0.01 0.08 <0.01 Net energy, Mcal kg−1 2.46 2.44 2.34 0.01 2.43 2.40 0.01 0.06 <0.01 Item . Millrun, % . . . SEM . Enzyme . . SEM . P-value2 . . . 0 . 15 . 30 . . No . Yes . . Enzyme . Linear (Millrun) . Total tract digestibility, %  Dry matter 86.5 84.7 83.9 0.28 87.3 82.8 0.22 <0.01 <0.01  Energy 87.3 84.9 81.5 0.01 85.0 84.2 0.01 0.05 <0.01  N 86.4 85.3 83.5 0.53 85.1 85.0 0.44 0.89 <0.01  P 52.6 43.5 41.1 0.60 46.2 45.2 0.52 0.33 0.02 Digestible energy, Mcal kg−1 3.50 3.47 3.34 0.01 3.45 3.42 0.01 0.08 <0.01 Net energy, Mcal kg−1 2.46 2.44 2.34 0.01 2.43 2.40 0.01 0.06 <0.01 1Values are means of eight individually housed pigs. 2No interaction between millrun and enzyme (P > 0.10). Open in new tab Table 2. Effects of wheat millrun inclusion and multi-carbohydrase supplementation on apparent total tract digestibility of energy and minerals of diets fed to grower pigs (60 kg body weight) in the nutrient digestibility study1 Item . Millrun, % . . . SEM . Enzyme . . SEM . P-value2 . . . 0 . 15 . 30 . . No . Yes . . Enzyme . Linear (Millrun) . Total tract digestibility, %  Dry matter 86.5 84.7 83.9 0.28 87.3 82.8 0.22 <0.01 <0.01  Energy 87.3 84.9 81.5 0.01 85.0 84.2 0.01 0.05 <0.01  N 86.4 85.3 83.5 0.53 85.1 85.0 0.44 0.89 <0.01  P 52.6 43.5 41.1 0.60 46.2 45.2 0.52 0.33 0.02 Digestible energy, Mcal kg−1 3.50 3.47 3.34 0.01 3.45 3.42 0.01 0.08 <0.01 Net energy, Mcal kg−1 2.46 2.44 2.34 0.01 2.43 2.40 0.01 0.06 <0.01 Item . Millrun, % . . . SEM . Enzyme . . SEM . P-value2 . . . 0 . 15 . 30 . . No . Yes . . Enzyme . Linear (Millrun) . Total tract digestibility, %  Dry matter 86.5 84.7 83.9 0.28 87.3 82.8 0.22 <0.01 <0.01  Energy 87.3 84.9 81.5 0.01 85.0 84.2 0.01 0.05 <0.01  N 86.4 85.3 83.5 0.53 85.1 85.0 0.44 0.89 <0.01  P 52.6 43.5 41.1 0.60 46.2 45.2 0.52 0.33 0.02 Digestible energy, Mcal kg−1 3.50 3.47 3.34 0.01 3.45 3.42 0.01 0.08 <0.01 Net energy, Mcal kg−1 2.46 2.44 2.34 0.01 2.43 2.40 0.01 0.06 <0.01 1Values are means of eight individually housed pigs. 2No interaction between millrun and enzyme (P > 0.10). Open in new tab Experiment 2: growth performance Including wheat millrun in the diets tended to reduce the day 42 and final BW (Table 3; P = 0.10) and reduced average daily gain (ADG) from day 29 to 42 (P < 0.05) and overall (P < 0.05). Similarly, from day 29 to 42 of the experiment, gain to feed ratio (G:F) was reduced (P < 0.05), and there was a reduction in G:F for the overall period (P < 0.05) when pigs were fed diets with 30% wheat millrun. Wheat millrun inclusion had no significant effects on ADFI. Enzyme supplementation reduced G:F during the initial 14 d (P < 0.05) but did not affect BW, ADG, or ADFI. Table 3. Effect of dietary wheat millrun and multi-carbohydrase supplementation on performance of growing pigs in the performance study (60 kg)1 Item . Millrun, % . . Enzyme . . Pooled SEM . P-value2 . . . 0 . 30 . No . Yes . . Millrun . Enzyme . Body Weight, kg  Initial 60.1 60.3 59.8 60.6 1.27 0.63 0.10  Day 14 76.0 75.8 76.1 75.6 1.12 0.92 0.62  Day 28 92.1 91.6 91.9 91.8 0.71 0.50 0.88  Day 42 107.3 105.8 106.6 106.4 1.03 0.10 0.84  Day 56 120.6 118.9 119.6 120.0 0.72 0.10 0.69 Average daily gain, kg d−1  Day 1 to 14 1.13 1.10 1.16 1.08 0.07 0.68 0.14  Day 15 to 28 1.16 1.13 1.13 1.15 0.04 0.28 0.42  Day 29 to 42 1.09 1.02 1.05 1.05 0.04 0.03 0.90  Day 43 to 56 0.94 0.95 0.91 0.98 0.04 0.91 0.11  Day 0 to 56 1.10 1.07 1.09 1.08 0.02 <0.05 0.65 Average daily feed intake, kg d−1  Day 1 to 14 2.47 2.47 2.47 2.47 0.12 0.98 0.98  Day 15 to 28 2.84 2.88 2.87 2.86 0.06 0.60 0.91  Day 29 to 42 2.88 2.94 2.87 2.95 0.07 0.58 0.42  Day 43 to 56 3.19 3.31 3.20 3.30 0.26 0.24 0.32  Day 0 to 56 2.85 2.90 2.85 2.90 0.05 0.41 0.51 Gain to feed ratio  Day 1 to 14 0.45 0.45 0.47 0.43 0.02 0.74 <0.05  Day 15 to 28 0.41 0.39 0.40 0.40 0.02 0.19 0.68  Day 29 to 42 0.38 0.35 0.37 0.36 0.01 <0.01 0.38  Day 43 to 56 0.32 0.30 0.31 0.30 0.01 0.34 0.91  Day0 to 56 0.39 0.37 0.38 0.37 0.01 0.01 0.20 Item . Millrun, % . . Enzyme . . Pooled SEM . P-value2 . . . 0 . 30 . No . Yes . . Millrun . Enzyme . Body Weight, kg  Initial 60.1 60.3 59.8 60.6 1.27 0.63 0.10  Day 14 76.0 75.8 76.1 75.6 1.12 0.92 0.62  Day 28 92.1 91.6 91.9 91.8 0.71 0.50 0.88  Day 42 107.3 105.8 106.6 106.4 1.03 0.10 0.84  Day 56 120.6 118.9 119.6 120.0 0.72 0.10 0.69 Average daily gain, kg d−1  Day 1 to 14 1.13 1.10 1.16 1.08 0.07 0.68 0.14  Day 15 to 28 1.16 1.13 1.13 1.15 0.04 0.28 0.42  Day 29 to 42 1.09 1.02 1.05 1.05 0.04 0.03 0.90  Day 43 to 56 0.94 0.95 0.91 0.98 0.04 0.91 0.11  Day 0 to 56 1.10 1.07 1.09 1.08 0.02 <0.05 0.65 Average daily feed intake, kg d−1  Day 1 to 14 2.47 2.47 2.47 2.47 0.12 0.98 0.98  Day 15 to 28 2.84 2.88 2.87 2.86 0.06 0.60 0.91  Day 29 to 42 2.88 2.94 2.87 2.95 0.07 0.58 0.42  Day 43 to 56 3.19 3.31 3.20 3.30 0.26 0.24 0.32  Day 0 to 56 2.85 2.90 2.85 2.90 0.05 0.41 0.51 Gain to feed ratio  Day 1 to 14 0.45 0.45 0.47 0.43 0.02 0.74 <0.05  Day 15 to 28 0.41 0.39 0.40 0.40 0.02 0.19 0.68  Day 29 to 42 0.38 0.35 0.37 0.36 0.01 <0.01 0.38  Day 43 to 56 0.32 0.30 0.31 0.30 0.01 0.34 0.91  Day0 to 56 0.39 0.37 0.38 0.37 0.01 0.01 0.20 1Data are presented as least-square means of nine replicate pens with five pigs per pen. 2No interaction between millrun and enzyme (P > 0.10). Open in new tab Table 3. Effect of dietary wheat millrun and multi-carbohydrase supplementation on performance of growing pigs in the performance study (60 kg)1 Item . Millrun, % . . Enzyme . . Pooled SEM . P-value2 . . . 0 . 30 . No . Yes . . Millrun . Enzyme . Body Weight, kg  Initial 60.1 60.3 59.8 60.6 1.27 0.63 0.10  Day 14 76.0 75.8 76.1 75.6 1.12 0.92 0.62  Day 28 92.1 91.6 91.9 91.8 0.71 0.50 0.88  Day 42 107.3 105.8 106.6 106.4 1.03 0.10 0.84  Day 56 120.6 118.9 119.6 120.0 0.72 0.10 0.69 Average daily gain, kg d−1  Day 1 to 14 1.13 1.10 1.16 1.08 0.07 0.68 0.14  Day 15 to 28 1.16 1.13 1.13 1.15 0.04 0.28 0.42  Day 29 to 42 1.09 1.02 1.05 1.05 0.04 0.03 0.90  Day 43 to 56 0.94 0.95 0.91 0.98 0.04 0.91 0.11  Day 0 to 56 1.10 1.07 1.09 1.08 0.02 <0.05 0.65 Average daily feed intake, kg d−1  Day 1 to 14 2.47 2.47 2.47 2.47 0.12 0.98 0.98  Day 15 to 28 2.84 2.88 2.87 2.86 0.06 0.60 0.91  Day 29 to 42 2.88 2.94 2.87 2.95 0.07 0.58 0.42  Day 43 to 56 3.19 3.31 3.20 3.30 0.26 0.24 0.32  Day 0 to 56 2.85 2.90 2.85 2.90 0.05 0.41 0.51 Gain to feed ratio  Day 1 to 14 0.45 0.45 0.47 0.43 0.02 0.74 <0.05  Day 15 to 28 0.41 0.39 0.40 0.40 0.02 0.19 0.68  Day 29 to 42 0.38 0.35 0.37 0.36 0.01 <0.01 0.38  Day 43 to 56 0.32 0.30 0.31 0.30 0.01 0.34 0.91  Day0 to 56 0.39 0.37 0.38 0.37 0.01 0.01 0.20 Item . Millrun, % . . Enzyme . . Pooled SEM . P-value2 . . . 0 . 30 . No . Yes . . Millrun . Enzyme . Body Weight, kg  Initial 60.1 60.3 59.8 60.6 1.27 0.63 0.10  Day 14 76.0 75.8 76.1 75.6 1.12 0.92 0.62  Day 28 92.1 91.6 91.9 91.8 0.71 0.50 0.88  Day 42 107.3 105.8 106.6 106.4 1.03 0.10 0.84  Day 56 120.6 118.9 119.6 120.0 0.72 0.10 0.69 Average daily gain, kg d−1  Day 1 to 14 1.13 1.10 1.16 1.08 0.07 0.68 0.14  Day 15 to 28 1.16 1.13 1.13 1.15 0.04 0.28 0.42  Day 29 to 42 1.09 1.02 1.05 1.05 0.04 0.03 0.90  Day 43 to 56 0.94 0.95 0.91 0.98 0.04 0.91 0.11  Day 0 to 56 1.10 1.07 1.09 1.08 0.02 <0.05 0.65 Average daily feed intake, kg d−1  Day 1 to 14 2.47 2.47 2.47 2.47 0.12 0.98 0.98  Day 15 to 28 2.84 2.88 2.87 2.86 0.06 0.60 0.91  Day 29 to 42 2.88 2.94 2.87 2.95 0.07 0.58 0.42  Day 43 to 56 3.19 3.31 3.20 3.30 0.26 0.24 0.32  Day 0 to 56 2.85 2.90 2.85 2.90 0.05 0.41 0.51 Gain to feed ratio  Day 1 to 14 0.45 0.45 0.47 0.43 0.02 0.74 <0.05  Day 15 to 28 0.41 0.39 0.40 0.40 0.02 0.19 0.68  Day 29 to 42 0.38 0.35 0.37 0.36 0.01 <0.01 0.38  Day 43 to 56 0.32 0.30 0.31 0.30 0.01 0.34 0.91  Day0 to 56 0.39 0.37 0.38 0.37 0.01 0.01 0.20 1Data are presented as least-square means of nine replicate pens with five pigs per pen. 2No interaction between millrun and enzyme (P > 0.10). Open in new tab Wheat millrun inclusion or multi-carbohydrase supplementation did not affect days to market, market weight, slaughter weight, loin depth, or dressing percentage (Table 4). However, backfat depth was reduced by 7% (P < 0.05), whereas carcass yield increased marginally from 61.8% to 62.4% with the inclusion of 30% wheat millrun (P < 0.05). Backfat depth tended to be increased when the diets were supplemented with the multi-carbohydrase enzyme (P = 0.07). Table 4. Effect of wheat millrun inclusion and multi-carbohydrase supplementation on carcass traits in the performance study . Millrun, % . . Enzyme . . Pooled SEM . P-value1 . . Item . 0 . 30 . No . Yes . . Millrun . Enzyme . Days to market 68 69 69 68 2.57 0.46 0.31 Final body weight, kg 132.25 131.81 132.05 132.01 0.41 0.42 0.94 Slaughter weight, kg 105.84 105.10 105.38 105.56 0.54 0.19 0.75 Backfat depth, mm 16.71 15.54 15.74 16.50 0.75 <0.01 0.07 Loin depth, mm 66.82 68.41 67.97 67.27 1.05 0.28 0.63 Carcass yield, % 61.80 62.42 62.29 61.94 0.36 0.01 0.13 Dressing, % 80.03 79.74 79.80 79.96 0.28 0.35 0.60 . Millrun, % . . Enzyme . . Pooled SEM . P-value1 . . Item . 0 . 30 . No . Yes . . Millrun . Enzyme . Days to market 68 69 69 68 2.57 0.46 0.31 Final body weight, kg 132.25 131.81 132.05 132.01 0.41 0.42 0.94 Slaughter weight, kg 105.84 105.10 105.38 105.56 0.54 0.19 0.75 Backfat depth, mm 16.71 15.54 15.74 16.50 0.75 <0.01 0.07 Loin depth, mm 66.82 68.41 67.97 67.27 1.05 0.28 0.63 Carcass yield, % 61.80 62.42 62.29 61.94 0.36 0.01 0.13 Dressing, % 80.03 79.74 79.80 79.96 0.28 0.35 0.60 1No interaction between millrun and enzyme (P > 0.10). Open in new tab Table 4. Effect of wheat millrun inclusion and multi-carbohydrase supplementation on carcass traits in the performance study . Millrun, % . . Enzyme . . Pooled SEM . P-value1 . . Item . 0 . 30 . No . Yes . . Millrun . Enzyme . Days to market 68 69 69 68 2.57 0.46 0.31 Final body weight, kg 132.25 131.81 132.05 132.01 0.41 0.42 0.94 Slaughter weight, kg 105.84 105.10 105.38 105.56 0.54 0.19 0.75 Backfat depth, mm 16.71 15.54 15.74 16.50 0.75 <0.01 0.07 Loin depth, mm 66.82 68.41 67.97 67.27 1.05 0.28 0.63 Carcass yield, % 61.80 62.42 62.29 61.94 0.36 0.01 0.13 Dressing, % 80.03 79.74 79.80 79.96 0.28 0.35 0.60 . Millrun, % . . Enzyme . . Pooled SEM . P-value1 . . Item . 0 . 30 . No . Yes . . Millrun . Enzyme . Days to market 68 69 69 68 2.57 0.46 0.31 Final body weight, kg 132.25 131.81 132.05 132.01 0.41 0.42 0.94 Slaughter weight, kg 105.84 105.10 105.38 105.56 0.54 0.19 0.75 Backfat depth, mm 16.71 15.54 15.74 16.50 0.75 <0.01 0.07 Loin depth, mm 66.82 68.41 67.97 67.27 1.05 0.28 0.63 Carcass yield, % 61.80 62.42 62.29 61.94 0.36 0.01 0.13 Dressing, % 80.03 79.74 79.80 79.96 0.28 0.35 0.60 1No interaction between millrun and enzyme (P > 0.10). Open in new tab Experiment 3: GHG emissions Pigs fed 30% wheat millrun diets consumed about 22% more water and excreted 31% more manure than pigs fed the 0 wheat millrun diets (P < 0.05; Table 5). Table 5. Effect of wheat millrun and multi-carbohydrase supplementation on greenhouse gas emission rate in grower pigs (60 kg body weight) housed in an environmental chambers1,2 Item . Millrun, % . . Enzyme . . Pooled SEM . P-value3 . . . 0 . 30 . No . Yes . . Millrun . Enzyme . Gas, mg s−1  Methane 4.7 4.9 4.5 5.1 3.40 0.78 0.51  Nitrous oxide 0.45 0.42 0.46 0.42 0.06 0.79 0.65  Carbon dioxide 1,610 1,711 1,808 1,513 214 0.57 0.15  Water, L/pig/d 8.3 10.1 9.6 8.8 0.43 0.05 0.29  Manure4, L/pig/d 3.9 5.1 4.5 4.5 0.25 <0.01 0.90 Item . Millrun, % . . Enzyme . . Pooled SEM . P-value3 . . . 0 . 30 . No . Yes . . Millrun . Enzyme . Gas, mg s−1  Methane 4.7 4.9 4.5 5.1 3.40 0.78 0.51  Nitrous oxide 0.45 0.42 0.46 0.42 0.06 0.79 0.65  Carbon dioxide 1,610 1,711 1,808 1,513 214 0.57 0.15  Water, L/pig/d 8.3 10.1 9.6 8.8 0.43 0.05 0.29  Manure4, L/pig/d 3.9 5.1 4.5 4.5 0.25 <0.01 0.90 1Gas measurements taken after 14 d. Manure stored below the pens within each chamber. 2Values are means of four replicates (chambers) with six pigs per chamber. 3No interaction between millrun and enzyme (P > 0.05). 4Manure refers to a combination of feces and urine. Open in new tab Table 5. Effect of wheat millrun and multi-carbohydrase supplementation on greenhouse gas emission rate in grower pigs (60 kg body weight) housed in an environmental chambers1,2 Item . Millrun, % . . Enzyme . . Pooled SEM . P-value3 . . . 0 . 30 . No . Yes . . Millrun . Enzyme . Gas, mg s−1  Methane 4.7 4.9 4.5 5.1 3.40 0.78 0.51  Nitrous oxide 0.45 0.42 0.46 0.42 0.06 0.79 0.65  Carbon dioxide 1,610 1,711 1,808 1,513 214 0.57 0.15  Water, L/pig/d 8.3 10.1 9.6 8.8 0.43 0.05 0.29  Manure4, L/pig/d 3.9 5.1 4.5 4.5 0.25 <0.01 0.90 Item . Millrun, % . . Enzyme . . Pooled SEM . P-value3 . . . 0 . 30 . No . Yes . . Millrun . Enzyme . Gas, mg s−1  Methane 4.7 4.9 4.5 5.1 3.40 0.78 0.51  Nitrous oxide 0.45 0.42 0.46 0.42 0.06 0.79 0.65  Carbon dioxide 1,610 1,711 1,808 1,513 214 0.57 0.15  Water, L/pig/d 8.3 10.1 9.6 8.8 0.43 0.05 0.29  Manure4, L/pig/d 3.9 5.1 4.5 4.5 0.25 <0.01 0.90 1Gas measurements taken after 14 d. Manure stored below the pens within each chamber. 2Values are means of four replicates (chambers) with six pigs per chamber. 3No interaction between millrun and enzyme (P > 0.05). 4Manure refers to a combination of feces and urine. Open in new tab Emission rates are presented in Table 5. Feeding pigs with 30% wheat millrun included in their diets had no effect on the GHG measured in this experiment. The highest concentration of gas emitted was CO2 at 1,610 and 1,711 mg/s, without or with wheat millrun inclusion, respectively (P > 0.05), followed by methane (4.7 and 4.9; P > 0.05) and nitrous oxide (0.45 and 0.42; P > 0.05). There was no effect of enzyme supplementation on GHG concentrations (P > 0.05). Discussion Strategies to reduce the impact of the livestock sector on the environment are gaining prominence. One feeding strategy for the swine industry is to rely more on coproducts and reduce “human” grade food fed to pigs. This allows pigs to convert these coproducts, which may otherwise be waste products, into quality protein (Zijlstra and Beltranena, 2013; Makkar, 2018). Wheat millrun is produced during flour milling, and, primarily due to economics and availability, its inclusion in swine diets is increasing (Nortey et al., 2007; Woyengo et al., 2014). However, the high-fiber content of most milling coproducts, including wheat millrun, limits energy and nutrient availability in nonruminants. Enzyme inclusion to improve digestion and utilization of nutrients has been suggested. Due to synergistic or additive actions, multi-carbohydrase enzymes are believed to improve digestion and performance more than individual carbohydrases (Zeng et al., 2018). Diets were formulated on a least-cost basis, assuming caloric intake would be similar, regardless of the energy content of the diet (Beaulieu et al., 2009; Quiniou and Noblet, 2012). Additionally, this ensures that any improvement in ADG or G:F would be from the enzyme addition and not from fat (Jacela et al., 2010). Nitrogen and P digestibility was not improved, and energy and DM digestibility were reduced in the current study with enzyme supplementation. This was contrary to our hypothesis and to the results of others (Omogbenigun et al., 2004; Emiola et al., 2009; Chen et al., 2020) who reported improved DM and energy digestibility from multi-carbohydrase supplementation. Moreover, Chen et al. (2020) reported that the improved nutrient digestibility was accompanied by reduced CO2 emissions, illustrating the potential for this strategy. Although multi-carbohydrases could present a synergistic effect, the composition and concentration of the individual enzymes are imperative in producing a positive effect. The reduction in DM digestibility and a tendency to reduced energy digestibility observed in the present digestibility study may explain the reduced G:F in the first 14 d of the performance study with enzyme supplementation. Lu et al. (2019) reported reduced growth when xylanase was fed to weanling pigs. The authors suggested that the negative impact on nutrient digestibility and growth was due to the digestive enzyme secretion or activity being affected by the supplementation. This is supported by an earlier study by Fan et al. (2009), who observed a significant reduction in amylase and lipase activities in piglets’ digesta when xylanase was supplemented in the diet. There was a reduction in ADG and G:F in pigs fed the high wheat millrun diets in the current study. Stewart et al. (2013) also reported a reduction in ADG, G:F, and dressing percentage when corn was replaced with wheat millrun or soybean hulls in a corn–soybean-based diet fed to growing pigs. Conceivably, comparable to the present work, these results are due to the higher NSP content in the wheat millrun diets than the diets without wheat millrun. Contrary to the results of Beaulieu et al. (2009) and Quiniou and Noblet (2012), the pig fed the diets with reduced energy failed to compensate with increased feed intake. Unlike in the current study, energy content of the diets in these earlier trials was manipulated with the use of several ingredients, including oil or fat, thus another indication that the NSP content of the high wheat millrun diets limited intake. The lower NE (Table 1) in the wheat millrun inclusion diets might have been responsible for the 7% reduction observed in backfat depth as this parameter is mainly influenced by the energy intake in the finishing phase (Smit et al., 2018). This could explain the tendency to increased backfat depth in the diets supplemented with enzymes, proving that the enzyme provided surplus energy from the diet deposited in the backfat. The backfat depth directly affects carcass yield, and pigs with excessive backfat depth are penalized, and thus it is not surprising that there was an increase in carcass yield with the wheat millrun inclusion diets. The inclusion of wheat millrun and supplementation with enzymes in the diets of the growing pigs did not significantly increase enteric GHG emissions in the current study. Similar to what has been shown by others (Atakora et al., 2011; Trabue and Kerr, 2014; Philippe et al., 2015), CO2 was the highest of the GHG emitted among the three gases determined in this study. Carbon dioxide is mainly from animal respiration. It has been reported that CO2 from the pig is more likely to be influenced by pig activity and less by diet composition (Atakora et al., 2011; Philippe et al., 2015). However, Schrama et al. (1998) discovered that high-fiber diets reduced physical activities in pigs. They related the reduction to the gradual release of energy and the “bulkiness” of the high-fiber diets. In contrast, Laitat et al. (2015) reported an increase in pig activity due to higher feeding time required by fattening pigs consuming high-fiber diets. The relatively confirmed spaces of our chambers precluded accurate measurements of pig activity in our study and it was not measured. Methane emissions in swine production are primarily from methanogens breaking down organic matter in the pig’s digestive tract and in the slurry (Philippe and Nicks, 2015). These bacteria, mainly from the family Methanobacteriaceae, are abundant in the hindgut of pigs (Mi et al., 2019). Therefore, CH4 production may be increased by high dietary fiber as the high fiber increases the activity of the methanogenic community (Le Goff et al., 2002). For example, Jarret et al. (2011) reported an increase in CH4 production when high-fiber diets containing distiller dried grains with soluble (DDGS), sugar beet pulp, and high-fat rapeseed meal were fed to growing pigs. In contrast, our study showed no significant difference among the dietary treatments for CH4 output. Perhaps the type of fiber in the diets may be responsible for the different results. Sugar beet pulp is a highly fermentable fiber source with 25% of its total dietary fiber (TDF) being soluble, whereas just about 6% of TDF in wheat millrun is soluble (Garcia et al., 2015; Wang et al., 2016), and thus the soluble fiber content of the 30% wheat millrun diets was comparable to the control (Table 1). However, similar to the results from the current study, others have found no significant difference in CH4 emissions with increased fiber content. For example, Pepple et al. (2011), in a study designed to measure GHG from a DDGS and a non-DDGS barn, reported no significant differences in CH4 production. Pepple et al. (2011) opined that high variability in the CH4 emissions and a low CH4 production from manure from the DDGS barns were possible reasons for the lack of difference. Research has shown that N2O emissions are mainly influenced by the age of the manure (Laguë et al., 2013). The N2O from manure primarily arises through incomplete nitrification or denitrification by microorganisms (Oenema et al., 2005). Also, N2O emissions are related to the excretion of N; therefore, a reduction of N in the manure could result in a potential reduction of N2O during the storage of manure (Atakora et al., 2011). The reduction of the CP in the diet fed to pigs is, therefore, another potential diet manipulation to reduce GHG (Liu et al., 2017). In the current study, N2O emissions were determined after 14 d; therefore, the age of the manure could have resulted in no statistical difference between the diets. Pepple et al. (2011) and Montalvo et al. (2013) also had no difference in N2O emissions when coproducts were added to the diets of pigs. The failure of the multi-carbohydrase enzyme to have an effect on emissions could be due to the lack of an effect on dry matter or energy digestibility. The higher manure (slurry) output reported in the current study could be due to the high-fiber content and low digestibility of the 30% wheat millrun diet. High water consumption, coupled with water wastage, could also be a contributing factor. Comparable data were reported by Anderson et al. (2012) and Trabue and Kerr (2014), who reported an increase in DM manure output when pigs were fed diets containing DDGS when compared with a corn–soybean meal diet. The increase was attributed to the higher fiber content on the DDGS diets. Due to the limited activity of endogenous enzymes in the large intestine, most of the fiber in high-fiber diets is not completely fermented and, therefore, is excreted in the feces (Kiarie et al., 2013). The 30% wheat millrun diets had 35% more insoluble dietary fiber and 35% more TDF (Table 1) than the 0% wheat millrun diets. Conclusions The present study results failed to demonstrate an interaction between the multi-carbohydrase supplementation and wheat millrun inclusion in diets of growing pigs. The multi-carbohydrase enzyme effect on GHG emission, nutrient digestibility, and growth performance was not markedly higher in the wheat millrun diets. Even though wheat millrun inclusion increases the fiber content in swine diets, the addition of up to 30% of wheat millrun will not significantly increase the GHG produced by the pigs, and multienzyme supplementation in the wheat millrun diets will have minimal effects on emissions. Further research, including life cycle assessment modeling utilizing these data, is required to determine the effects of these treatments on GHG output from the manure. 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TI - Greenhouse gases and performance of growing pigs fed wheat-based diets containing wheat millrun and a multi-carbohydrase enzyme
JF - Journal of Animal Science
DO - 10.1093/jas/skab213
DA - 2021-10-01
UR - https://www.deepdyve.com/lp/oxford-university-press/greenhouse-gases-and-performance-of-growing-pigs-fed-wheat-based-diets-DYPs4S0nKv
VL - 99
IS - 10
DP - DeepDyve
ER -