Brassica juncea and Brassica napus seed as

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1 Evaluation of canola meal derived from Brassica juncea and Brassica napus seed as an energy source for feedlot steers Jayakrishnan Nair 1, Gregory B. Penner 1, Peiqiang Yu 1, H. A. (Bart) Lardner 2, Tim McAllister 3, Daalkhaijav Damiran 1,2, and John J. McKinnon 1,4 1 Department of Animal and Poultry Sciences, University of Saskatchewan, Saskatoon, Saskatchewan, Canada S7N 5A8; 2 Western Beef Development Centre, Humboldt, Saskatchewan, Canada S0K 2A0; and 3 Lethbridge Research Centre, Agriculture and Agri-Food Canada, Lethbridge, Alberta, Canada T1J 4B1. Received 12 March 2015, accepted 15 July Published on the web 11 November Nair, J., Penner, G. B., Yu, P., Lardner, H. A., McAllister, T., Damiran, D. and McKinnon, J. J Evaluation of canola meal derived from Brassica juncea and Brassica napus seed as an energy source for feedlot steers. Can. J. Anim. Sci. 95: This study evaluated the substitution of barley grain with two sources of canola meal (CM) derived from Brassica napus and B. juncea on performance of feedlot cattle. Crossbred steers [n300; initial body weight (BW) kg] were allotted to 25 pens with each pen randomly assigned to one of five treatments. The control backgrounding diet consisted of 39% barley silage, 30.4% barley grain, 22.8% brome hay and 7.8% supplement, while the control finishing diet consisted of 88.3% barley grain, 4.4% barley silage and 7.3% supplement (dry matter basis). The control diets contained no CM during backgrounding and finishing. Treatment diets included 15 and 30% B. napus or B. juncea meal during backgrounding and 10 and 20% during finishing, with canola meal replacing barley grain in both phases. In each phase the data were analyzed as a 22 factorial plus a control. Cattle fed CM substituted diets during backgrounding had greater (PB0.05) dry matter intake (DMI), average daily gain (ADG) and final BW relative to those fed the control diet. Gain to feed ratio (G:F) and calculated net energy for maintenance (NE m ) and gain (NE g ) were not affected (P0.05) by treatment. During finishing, DMI and ADG did not differ (P0.05) across treatments. Feed efficiency, NE m and NE g decreased (PB0.05) at the 20% CM level relative to 10%. Over the entire feeding period, G:F, NE m and NE g were reduced (PB0.05) with higher inclusion of CM in the diet. The percentage of cattle grading Canada AAA was reduced (PB0.05) by CM. These results indicate that regardless of type CM has a lower net energy value than barley grain and that it is not an equivalent energy substitute for cereal grains over the entire feeding period. Key words: Backgrounding, canola meal, feedlot performance, finishing, carcass quality Nair, J., Penner, G. B., Yu, P., Lardner, H. A., McAllister, T., Damiran, D. et McKinnon, J. J L e valuation du tourteau de canola de rivé des graines de Brassica (B.) juncea et B. napus comme source d e nergie chez les bouvillons des parcs d engraissement. Can. J. Anim. Sci. 95: Cette e tude avait pour but l e valuation de la substitution du grain d orge par deux sources de tourteau de canola (CM «canola meal»)de rive es de Brassica napus et B. juncea sur la performance des bouvillons des parcs d engraissement. Les bouvillons croise s[n300 ; poids corporel initial (BW «body weight») kg] ont été attribués à 25 enclos avec chaque enclos attribué aléatoirement a` l un de cinq traitements. La die` te de semifinition témoin consistait de 39 % d ensilage d orge, 30,4 % de grains d orge, 22,8 % de brome et 7,8 % de supple ments, tandis que la die` te de finition témoin consistait de 88,3 % de grain d orge, 4,4 % d ensilage d orge et 7,3 % de supple ments [sur une base de matie` res sèches (DM «dry matter»)]. Les die` tes te moins ne contiennent pas de CM pendant les phases de semi-finition et de finition. Les die` tes traitements incluaient 15 et 30 % de tourteau de B. napus ou de B. juncea pendant la semi-finition et 10 et 20 % pendant la finition. Le tourteau de canola remplace les grains d orge dans les deux phases. Dans chaque phase, les donne es ont e té analyse es selon un arrangement factoriel 22 plus un témoin. Les bouvillons ayant rec u les die` tes substituées de CM pendant la phase de semi-finition avaient de plus grandes (PB0,05) ingestions de matie` res se` ches (DMI «dry matter intake»), gains moyens quotidiens (ADG «average daily gain»)etbwàla fin par rapport aux bouvillons ayant rec u la die` te te moin. Il n y a pas eu d effet (P0,05) du traitement sur l indice de consommation (G:F «gain to feed ratio») et l e nergie nette calcule e pour le maintien (NE m ) et le gain (NE g ). Pendant la finition, les DMI et ADG ne diffe raient pas (P0,05) entre les traitements. L efficience alimentaire, le NE m et le NE g ont diminue (PB0,05) avec le niveau de 20 % de CM par rapport à 10 %. Sur toute la pe riode d alimentation, les niveaux de G:F, NE m et NE g étaient re duits (PB0,05) avec une plus grande inclusion de CM dans la die` te. Le pourcentage de bouvillons qui obtenaient la cote 4 Corresponding author ( john.mckinnon@usask.ca). Abbreviations: ADF, acid detergent fiber; ADG, average daily gain; BW, body weight; CM, canola meal; CP, crude protein; DDGS, dried distillers grain with solubles; DM, dry matter; DMI, dry matter intake; EE, ether extract; G:F, gain: feed, NDF, neutral detergent fiber; NE g, net energy for growth; NE m, net energy for maintenance; TDN, total digestible nutrients Can. J. Anim. Sci. (2015) 95: doi: /cjas

2 600 CANADIAN JOURNAL OF ANIMAL SCIENCE Canada AAA étaient réduit (PB0,05) par le CM. Ces re sultats indiquent que le CM, sans égard au type, a une plus faible valeur d e nergie nette que les grains d orge et qu il n est donc pas un substitut e nerge tiquement équivalent aux grains ce réaliers sur toute la pe riode d alimentation. Mots clés: Semi-finition, tourteau de canola, performance en parc d engraissement, finition, qualite de carcasse Recent expansion of western Canada s canola-crushing industry has resulted in canola meal (CM) becoming increasingly available as a feed source for cattle. Traditionally, CM has been used as a protein source for ruminants; however, with increasing supply and competitive pricing it is possible that the livestock sector will place increasing emphasis on its value as an energy source in addition to its protein value. This shift would mimic that observed over the past decade with corn and wheat-based dried distillers grains with solubles (Walter et al. 2010; He et al. 2013). Newer varieties of canola, such as the yellow-seeded Brassica juncea, generate CM with a greater protein and reduced acid and neutral detergent fiber content than meal derived from conventional B. napus (Rahman and McVetty 2011). As a result, the energy value of B. juncea CM is likely to be higher than that of meal derived from B. napus. Very few studies have addressed the use of CM as an energy source for cattle. McKinnon et al. (1993) reported a linear increase in average daily gain (ADG) of backgrounded yearlings when CM content increased from 0 to 30% in a low-energy [2.67 Mcal kg 1 dry matter (DM)] total mixed ration. It was concluded that the energy balance of the diet was improved by protein supplementation. In a companion study to the present feedlot trial, He et al. (2013) fed individually housed growing steers CM derived from B. napus and B. juncea at 15 and 30% (DM) replacing barley grain during the backgrounding and finishing stages. The results showed that there was no difference in ADG during backgrounding and finishing, whereas dry matter intake (DMI) was greater and gain:feed (G:F) reduced for cattle fed both CM varieties at 30% inclusion. Further work is required to evaluate the energy value of these two varieties of CM under pen-fed conditions to further refine inclusion levels with respect to optimizing feedlot performance and carcass characteristics. The objectives of this study were to evaluate the effect of substitution of barley with CM derived from B. juncea and B. napus at two levels in backgrounding and finishing diets with respect to performance and carcass characteristics of growing beef cattle. MATERIALS AND METHODS Housing and Experimental Design A total of 300 crossbred steers ( kg) were purchased from commercial sources and transported to the Beef Cattle Research and Teaching Unit of the University of Saskatchewan. Upon arrival, they were ear tagged and processed according to Zenobi et al. (2014) and implanted with Ralgro TM (Intervet Inc., Kirkland, QC) and reimplanted with Revalor XS TM (Intervet Inc., Kirkland, QC) 60 d later. From arrival to the start of the trial, steers were fed an adaptation diet consisting of 35.2% barley silage, 28.5% brome hay and 36.3% fortified grain screening pellets (DM). Animals were cared for according to the guidelines of the Canadian Council on Animal Care (2009) as per the approved University of Saskatchewan Animal Care Protocol # The experiment was designed as a completely randomized design with a 2 (type of CM) by 2 (dietary level of inclusion) factorial arrangement of treatments plus a control, a design analogous to that of He et al. (2013). Steers were weighed on 2 consecutive days at the beginning of the trial and the average was used as the start of test weight. The steers were stratified by weight and randomized within weight group to one of 25 outdoor pens with 12 head per pen. Each pen was assigned randomly to one of the five dietary treatments as described below. The targeted end point for the trial was 645 kg liveweight (unshrunk basis), at which time the steers were sent as a group for slaughter at Cargill Foods, High River, AB. Treatments and Dietary Composition Single lots of canola meal derived from B. napus and B. juncea were used for this study (Table 1). The trial included a 54-d backgrounding phase and a 153-d finishing phase. During the backgrounding phase, the control diet Table 1. Chemical composition of solvent-extracted canola meals derived from Brassica napus or Brassica juncea seed Canola meal type B. napus z B. juncea z Nutrients (% DM basis) zy CP EE ADF NDF Ash Ca P x NE m NE g x z B. napusbrassica napus; B. junceabrassica juncea; CPcrude protein; EEether extract; ADFacid detergent fiber; NDFneutral detergent fiber; Cacalcium; Pphosphorus; NE m and NE g net energy of maintenance and gain (Mcal kg 1 DM). y Analyzed by Cumberland Valley Analytical Services, Inc. Hagerstown, MD. x Net energy content for maintenance and gain is calculated by summative energy equation (National Research Council 2001).

3 NAIR ET AL. * CANOLA MEAL AS AN ENERGY SOURCE FOR FEEDLOT STEERS 601 Table 2. Composition and nutrient analysis of backgrounding diets Canola meal type and inclusion level B. napus z B. juncea z Control 15% 30% 15% 30% Diet composition (% DM basis) Barley silage Bromegrass hay Barley grain Supplement B. napus meal B. juncea meal Backgrounding supplement composition (% DM basis) Ground barley Limestone Urea Mineral, vitamin premix y Nutrient composition (% DM basis) z CP EE ADF NDF Ca P z B. napus Brassica napus; B. junceabrassica juncea; CPcrude protein; EEether extract; ADFacid detergent fiber; NDF neutral detergent fiber; Cacalcium; Pphosphorus. y Mineral, vitamin premix for backgrounding diets containing 4.6% salt, 5.5% Ca, 0.55% P, 1.8% Na, 0.41% Mg, 0.37% K, 0.18% S and 5.3 mg Co, 203 mg Cu, 18.3 mg I, 182 mg Fe, 532 mg Mn, 1.5 mg Se, 602 mg Zn, 26 mg F and 430 mg monensin per kg and IU vitamin A, IU vitamin D and 550 IU vitamin E per kg supplement. consisted of 39% barley silage, 22.8% brome hay, 30.4% barley grain and 7.8% vitaminmineral supplement (DM) and was formulated to 12.2% crude protein (CP) and 1.48 and 0.89 Mcal kg 1 DM of net energy for maintenance (NE m ) and net energy for growth (NE g ), respectively, in order to target 1.3 kg d 1 weight gain (Table 2). In the treatment diets, CM derived from B. napus and B. juncea replaced barley grain at 15 and 30% of the diet (DM). This resulted in CM replacing 50 and 100% of the barley in the control diet, respectively. At the end of backgrounding, steers were transitioned to final finishing diets so that cattle fed low CM backgrounding diets were stepped up to low CM finishing diets and high CM backgrounding diets to high CM finishing diets without re-randomization. During finishing, the control diet consisted of 88.3% barley grain, 4.4% barley silage and 7.3% vitaminmineral supplement (DM) and was formulated to 12.1% CP and 1.85 and 1.22 Mcal kg 1 DM of NE m and NE g, respectively (Table 3). The four treatment diets were achieved by replacing barley grain with B. napus or B. juncea meals at 10 and 20% of the diet (DM). The inclusion levels of both B. napus and B. juncea meals for the backgrounding and finishing phases were based on the results of the companion study by He et al. (2013), who reported Table 3. Composition and nutrient analysis of finishing diets Canola meal type and inclusion level B. napus z B. juncea z Control 10% 20% 10% 20% Diet composition (% DM basis) Barley silage Barley grain Supplement B. napus meal B. juncea meal Finishing supplement composition (% DM basis) Ground barley Prairie pride pellets y Limestone Urea 4.0 Mineral, vitamin premix x Nutrient composition (% DM basis) z CP EE ADF NDF Ca P z B. napusbrassica napus; B. junceabrassica juncea; CPcrude protein; EEether extract; ADFacid detergent fiber; NDF neutral detergent fiber; Cacalcium; Pphosphorus. y Contains wheat bran, wheat shorts, wheat middlings, number 1 and 2 feed screenings, barley grain and refuse screenings with guaranteed minimum analysis of 15% crude protein and 3% crude fat and maximum 12.5% crude fiber. x Mineral, vitamin premix for finishing diets containing 4.6% salt, 8.4% Ca, 0.37% P, 1.8% Na, 0.6% Mg, 0.52% K, 0.16% S and 5.3 mg Co, 18.2 mg I, 95 mg Fe, 546 mg Mn, 1.5 mg Se, 596 mg Zn and 460 mg monensin per kg and IU vitamin A, 5480 IU vitamin D3 and 550 IU vitamin E per kg supplement. that relative to a barley-based control diet there was no effect of canola meal type (B. napus or B. juncea) or level of inclusion (15 or 30% DM) on ADG or G:F during backgrounding, whereas 30% inclusion of CM regardless of type resulted in greater DMI and poorer feed efficiency relative to inclusion at 15% during finishing. In both feeding phases, all diets were formulated to meet or exceed National Research Council (NRC 2000) nutrient requirements for the targeted level of growth. Calcium to phosphorus ratios were formulated to range from 1.5:1 to 2:1. Monensin sodium was incorporated in the vitamin mineral supplement pellet and formulated to provide 33 mg kg 1 (DM). Dietary NE m content of both backgrounding and finishing phases were calculated based on animal performance using the retained energy formula for large frame steer calves [RE0.0493BW 0.75 ) ADG ; NRC 1996] as per Zinn et al. (2002). Net energy of gain was calculated from NE m assuming NE g NE m as per Zinn and Shen (1998). Prior to the start of the trial, all steers were fed a common backgrounding diet. Steers fed both CM types were transitioned to the final backgrounding diet by

4 602 CANADIAN JOURNAL OF ANIMAL SCIENCE a two-step adaptation process in which the steers were fed 50% of the allocated CM for the first 3 d followed by the final diet for the remaining backgrounding period. During finishing, there was a seven-step adaptation period, which lasted for 21 d during which the diet composition changed every 3 d in such a way that the barley silage and hay contents of the diet were gradually decreased and the barley grain content increased to the formulated levels of the finishing diet. Canola meal inclusion was adjusted to the final finishing levels by the first step of diet adaptation. The two varieties of CM were sourced by the Canola Council of Canada from Bunge Canada (Altona, MB). The B. juncea meal was sourced from a separate crush from the same plant that utilized only seeds derived from B. juncea. Both meals were solvent extracted. The barley silage (cv. AC Rosser) was grown at the University of Saskatchewan. Barley grain, brome hay and the vitamin mineral pellets were purchased from commercial sources. Prior to feeding, the barley grain was dry rolled (Roskamp Champion, Waterloo, IA) to a processing index [i.e., volume weight of barley after processing expressed as a percentage of its volume weight before processing (DM basis)] of 78%, and brome hay was ground through a 9.5-cm screen using a tub grinder (Haybuster H-1000, DuraTech Industries International, Jamestown, ND). Data Collection and Analysis Feed was delivered using a feed mixer equipped with a digital scale (Farm Aid Equipment Inc., Model 430, Corsica, SD) to each pen once daily starting at The cattle were fed for ad libitum intake with a target of 5% feed refusal. Bunks were read each morning and the daily feed allotted was based on the residual feed in the bunk prior to feeding and the amount fed the previous day. Every 2 wk before feeding, the bunks were cleaned, the weights of orts were recorded and sampled, and remaining orts were returned to the original bunk. Steers were weighed individually at 0800 before feeding on 2 consecutive days at the start and end of each phase. Body weights were also taken before the 0800 feeding every 4 wk during backgrounding and every 2 wk during finishing. Performance parameters (DMI, ADG and G:F) were calculated based on shrunk body weight (live weight96%). Bunk samples of TMR were collected every 2 wk from each pen and composited on a treatment basis. Samples of barley silage and hay were collected every week and DM was determined to adjust daily feeding amounts as necessary. Rolled barley grain, CM and vitaminmineral supplements were sampled every 2 wk. Ort DM content was used to correct the DMI for each pen for each 2-wk period. All samples of feed and total mixed rations were composited on a monthly basis and a representative sample was saved for chemical analysis. Chemical Analysis The forage and the bunk samples were dried in a forced air oven at 558C for 72 h. After drying, the forage samples were ground through a 1-mm screen using a hammer mill (Christy & Norris 8 Lab mill, Christy Turner Ltd. Chelmsford, UK) while the concentrate samples were ground (1 mm) using a Retsch mill (Retsch ZM 100 grinder, Haan, Germany). Total mixed ration samples were analyzed in duplicate according to the Association of Official Analytical Chemists (AOAC 2000). Samples were analyzed for DM (Method ; AOAC 2000), ash (Method ; AOAC 2000), CP using the Kjeldahl method (Method ; AOAC 2000), neutral detergent fiber (NDF) with the addition of heat stable a-amylase and sodium sulfite (Method ; AOAC 2000), acid detergent fiber (ADF) (Method ; AOAC 2000) and ether extract (Method ; AOAC 2000). Calcium and phosphorus were analyzed using the dry ashing procedure [Methods and , respectively; AOAC (2000)]. Calcium was determined using an atomic absorption spectrophotometer (ice 3000 series, Thermo scientific, Waltham, MA) equipped with a Cetac ASX 260 auto sampler (Cetac technologies, Omaha, NE). Phosphorus concentrations were determined at 410 nm on a Helios delta spectrometer (Thermo Fischer Scientific, Waltham, MA). The CM samples were analyzed by Cumberland Valley Analytical Services (CVAS, Hagerstown, MD) according to the Association of Official Analytical Chemists (2000). Samples were analyzed for DM by drying at 1358C (Method ; AOAC 2000), CP (Method ; AOAC 2000) using a Leco FP-528 Nitrogen Combustion Analyzer (Leco, St Joseph, MI), ADF (Method ; AOAC 2000), NDF by the method of Van Soest et al. (1991) with the addition of amylase and sodium sulfite, ash (Method ; AOAC 2000) and fat (Method ; AOAC 2000) using a tecator extraction unit. Carcass Traits Steers were slaughtered at a commercial meat-processing plant (Cargill Foods, High River, AB) at an average BW of 645 kg at the end of a 153-d finishing period. Hot carcass weight was determined immediately and the carcasses were chilled for 24 h and evaluated by camera according to the Canadian Beef Grading Agency (CBGA 2009) regulations. Grade data included yield estimation and subjective estimates of marbling. The YG included: Canada 159% or more; Canada 258 to 54%; Canada 353% or less. Marbling scores were: Bdevoid; A trace, AA slight; and AAA small to moderate; prime slightly abundant or greater (CBGA 2009). Statistical Analysis The mixed model procedure of SAS software (version 9.3; SAS Institute, Inc., Cary, NC) was used to compare the effects of treatment on performance and carcass quality. As the experiment was designed as a twotwo factorial plus a control, two models were run. First, all

5 NAIR ET AL. * CANOLA MEAL AS AN ENERGY SOURCE FOR FEEDLOT STEERS 603 diets were compared against each other in a completely randomized design with Tukey s test used for mean separation. Second, canola meal type, level and type level interaction were analyzed as a two two factorial using data from just the CM treatments. Denominator degrees of freedom were determined using the Kenward Roger option. Analysis of covariance was used to determine the effects of end of backgrounding BW on finishing performance. Yield and quality grade data were analyzed using GLIMMIX (SAS software, version 9.3; SAS Institute Inc., Cary, NC) with a binomial error structure and logit data transformation. Significant differences and trends were declared at P B0.05 and P B0.10, respectively. RESULTS AND DISCUSSION Chemical and Nutrient Profile of the Two Canola Meals and Total Mixed Diets It was not possible to statistically analyze differences in chemical composition between the two CM varieties as they were each derived from a single oil extraction from B. napus or B. juncea seed. However, it is evident from Table 1 that the B. napus meal had lower CP, NE m and NE g and higher ether extract (EE), ADF and NDF content than B. juncea meal. Calcium and phosphorus levels were similar across the two meal types. The chemical composition of the B. napus and B. juncea meal reported in Table 1 are similar to that reported in other studies (Bell 1993; Newkirk et al. 1997; Montoya and Leterme 2009; He et al. 2013). Ingredient make-up and nutrient composition of the backgrounding and finishing diets are presented in Tables 2 and 3. While statistical analysis of differences between treatment diets was not carried out, supplementing CM in both phases of the trial, regardless of type, numerically increased dietary CP concentration relative to the control and at each level of inclusion. As well, in both phases, diets supplemented with B. juncea meal had greater CP and reduced EE concentrations than those supplemented with B. napus meal. Acid detergent fiber and NDF content of the backgrounding diets increased with greater inclusion of CM, regardless of type, relative to control. At both inclusion levels, diets supplemented with B. juncea meal had reduced ADF and NDF contents relative to B. napus meal. Similarly, finishing diets based on B. juncea had numerically less ADF and NDF than those based on B. napus, while the 20% CM treatments had higher ADF than the 10% treatments. Phosphorus content in both backgrounding and finishing diets increased at the higher level of CM inclusion, regardless of CM type. These effects of CM type and level on diet chemical composition can be explained based on the chemical composition of the two meal types. Mechanical and solvent extraction of oil from canola seed concentrates the remaining protein, fiber and mineral fractions in the meal (Bell and Keith 1991; Assadi et al. 2011). A similar concentration of dietary nutrients has been reported when other high-protein, high-fiber by-products [i.e., wheat and/or corn dried distillers grain with solubles (DDGS)] replaced barley grain in feedlot diets (Beliveau and McKinnon 2008; Gibb et al. 2008; Walter et al. 2010). Rahman and McVetty (2011) indicated that yellow-seeded Brassica genotypes (i.e., B. juncea) have a thinner and translucent seed coat with a larger embryo than black/brown seed genotypes (i.e., B. napus). Lignin content of the yellow seed hull is also reduced (Slominski et al. 1994). These differences result in higher oil and protein content of the yellow seed coat types relative to the black seed coat types. Differences in nutrient content (i.e., CP, ADF, NDF) of the seed is thus reflected in differences in the resulting meal and explains the effects of meal type and level on nutrient composition of the diets in the current study. Animal Performance The effects of replacing barley with 15 and 30% B. napus and B. juncea meals on 54-d backgrounding performance are presented in Table 4. No treatment effects due to level of CM inclusion were detected. As well, no type inclusion level interactions were detected. Final BW, ADG, DMI, and G:F were not different (P0.05) among steers fed the two CM types. However, relative to steers fed the CM-supplemented diets, end of backgrounding BW (397 vs. 384 kg); ADG (1.60 vs kg d 1 )and DMI (8.9 vs. 8.3 kg d 1 ) were reduced (PB0.01) for steers fed the control diet. Relative to the control, G:F was greater (0.186 vs ; P0.04) for cattle fed the 30% B. juncea treatment. Changes in dietary CP could potentially influence growth performance. However, the control diet was formulated to 12% CP and designed to meet the nutrient requirements of 350 kg steers gaining 1.3 kg d 1 according to NRC (2000). Actual gains averaged 1.36 kg d 1 (Table 4). In addition, there was no effect (P0.05) of treatment on dietary NE m or NE g content as calculated from animal performance, indicating that the improved ADG may have been in response to increased DMI. Similar improvements in performance of growing cattle have been reported when other highprotein by-product feeds have been fed in excess of protein requirements. For example, McKinnon et al. (1993) reported a linear increase in ADG when dietary CP concentration was increased by CM supplementation from 11 to 19% in diets relatively low in energy (2.67 Mcal ME kg 1 DM), but not on higher energy diets (2.84 Mcal ME kg 1 DM). The authors attributed the response to an improved energy balance as CP intake increased for animals fed the low-energy diets. McKinnon and Walker (2008) noted improvements in ADG and feed efficiency that were similar to that seen in the present study when wheat DDGS replaced 50 or 100% of the barley grain in backgrounding diets of growing steers. Improved energy status of cattle fed high-protein diets can result from increased rumen fermentation activity due to increased levels of rumen ammonia and

6 604 CANADIAN JOURNAL OF ANIMAL SCIENCE Table 4. The effects of solvent-extracted canola meal derived from Brassica napus or Brassica juncea seed on 54-d backgrounding performance of steers Canola meal type and inclusion level B. napus z B. juncea z P value Control 15% 30% 15% 30% SEM D zyx T z L z TL z n, animals (pen) 12 (5) 12 (5) 12 (5) 12 (5) 12 (5) Initial Shrunk BW w (kg) Final Shrunk BW w (kg) 384.0b 396.6a 396.6a 395.0a 399.5a 2.57 B ADG z (kg d 1 ) 1.36b 1.59a 1.59a 1.56ab 1.65a B DMI z (kg d 1 ) 8.26b 8.96a 9.03a 8.74a 8.96a B G:F z (kg kg 1 ) 0.166b 0.178ab 0.176ab 0.178ab 0.186a NE zv m (Mcal kg 1 ) NE zv g (Mcal kg 1 ) z B. napusbrassica napus; B. junceabrassica juncea; SEMstandard error of mean; Ddiet; Ttype of canola meal; Llevel of inclusion; TLtypelevel interaction; ADGaverage daily gain; DMIdry matter intake; G:Fgain:feed; NE m and NE g net energy of maintenance and gain, respectively. y P value of diet based on all treatments including the control. x Tukey s test was performed for multiple comparison among diets when P50.05 on effect of diet (D). w Shrunken body weight calculated as 96% of live weight (National Research Council 2000). v Calculated based on performance (Zinn and Shen 1998; Zinn et al. 2002). a, b Means without a common letter differ among all treatments (PB0.05). branched-chain volatile fatty acids promoting the activity of fiber-digesting bacteria and thus increasing fiber digestion in the rumen (Miura et al. 1980; Yang 2002). As well, absorption, transamination, deamination and oxidative metabolism of excess dietary and microbial amino acids can provide energy to the animal. Improved animal performance is not, however, a consistent response to feeding high-protein by-product feeds. Gibb et al. (2008) did not see any response to supplementing wheat DDGS at 20 or 40% of diet DM in backgrounding diets. In a companion trial to the present study, He et al. (2013) reported no improvement in performance of growing steers when CM derived from B. napus or B. juncea was fed at 15 or 30% of diet DM. Differences in housing between experiments (group vs. individual fed) may account for some of the differences between studies, particularly for DMI and the resultant impact on feed efficiency. Due to the effects of treatment during the backgrounding period, analysis of covariance was initially run to determine the impact of end of backgrounding body weight on subsequent finishing performance. No significant effect of this covariate was found; thus, the data were re-analyzed using a reduced model. However, it should be pointed out that other factors besides end-of-backgrounding BW may have been impacted by backgrounding treatment (i.e., compensatory gain) and thus could have influenced growth performance during the finishing period. No effect of treatment (P 0.05) was observed on final BW (Table 5). Dry matter intake tended (P 0.07) to be reduced for control cattle relative to those fed the CM-based diets, while ADG tended to decrease (P 0.10) as the level of both meals increased. Both trends resulted in reduced G:F (PB0.01) for both meal types at the higher level of inclusion. As well, cattle fed CM, regardless of type, at the 10% level were more efficient (P 0.02) than cattle fed 20% CM-based diets. He et al. (2013) also reported a decline in feed efficiency as CM from either B. napus or B. juncea replaced barley grain in finishing diets at levels ranging from 15 to 30% of diet DM. Net energy for maintenance and gain values determined based on BW, ADG, and DMI followed a similar pattern to that of G:F, with the control diet exhibiting greater (P 0.01) values than the 20% CMbased diets. These results indicate that for finishing cattle, CM, regardless of type, has a lower net energy value than barley grain. As in the backgrounding phase, there was no CM typelevel interaction (P0.05) for any of the performance parameters during finishing. It is of interest to note that with respect to calculated dietary NE m values, inclusion of canola meal derived from B. napus as a replacement for barley grain resulted in dietary NE m values that were 98.9 and 96.3% of the barleybased control diet. Respective values for the B. juncea diets were 98.4 and 97.3% (Table 5). If one compares the NE m value of barley grain (2.06 Mcal kg 1 DM; NRC 2000) to the NE m values for the two meals determined from chemical analysis in Table 1, B. napus meal would be predicted to have an energy value that is 85% of that of barley, while B. juncea would be 90.8%. Dry matter intake over the entire feeding period was similar (P0.05) among steers fed the two CM types (Table 6). Similar to the finishing phase, G:F, NE m and NE g were reduced (PB0.05) for both meal types at the higher level of inclusion. Performance results when other high-protein by-product feeds such as DDGS are used to replace barley grain vary with the by-product used and its dietary energy value. Gibb et al. (2008) noted a linear reduction in G:F similar to that observed by He et al. (2013) and the present study when wheat-based

7 NAIR ET AL. * CANOLA MEAL AS AN ENERGY SOURCE FOR FEEDLOT STEERS 605 Table 5. The effects of solvent-extracted canola meal derived from Brassica napus or Brassica juncea seed on 153-d finishing performance of steers Canola meal type and inclusion level B. napus z B. juncea z P value Control 10% 20% 10% 20% SEM D zyx T z L z TL z n, animals (pen) 12 (5) 12 (5) 12 (5) 12 (5) 12 (5) Initial shrunk BW w (kg) 384.0a 396.6b 396.6b 395.0b 399.5b 2.57 B Final shrunk BW w (kg) ADG z (kg d 1 ) DMI z (kg d 1 ) G:F z (kg kg 1 ) 0.149a 0.145ab 0.138b 0.144ab 0.141b B NE zv m (Mcal kg 1 ) 1.87a 1.85ab 1.80b 1.84ab 1.82ab NE zv g (Mcal kg 1 ) 1.23a 1.21ab 1.17b 1.20ab 1.19ab z B. napusbrassica napus; B. junceabrassica juncea; SEMstandard error of mean; Ddiet; Ttype of canola meal; Llevel of inclusion; TLtypelevel interaction; ADGaverage daily gain; DMIdry matter intake; G:Fgain:feed; NE m and NE g, net energy of maintenance and gain, respectively. y P value of diet based on all treatments including the control. x Tukey s test was performed for multiple comparison among diets when P50.05 on effect of diet (D). w Shrunk body weight calculated as 96% of liveweight (National Research Council 2001). v Calculated based on performance (Zinn and Shen 1998; Zinn et al. 2002). a, b Means without a common letter differ among all treatments (PB0.05). DDGS replaced barley grain at levels up to 60% of diet DM. In contrast, high-fat corn-based DDGS, which has a higher NE g value than wheat DDGS has been shown to improve feed efficiency when fed at 40% of the diet DM (Walter et al. 2010). In this regard, it is somewhat surprising that cattle fed diets formulated with B. juncea did not perform more efficiently than those fed diets with B. napus meal. However, it can be seen from Table 3 that differences between the two meals in ADF and NDF content of the CM formulated diets while obvious, were relatively minor and did not influence NE m or NE g content as calculated from animal performance. Carcass Traits There were no differences (P 0.05) in hot carcass weight or dressing percentage between cattle fed the control diet and those fed CM-based diets, with the exception of cattle fed 10% B. napus, which yielded heavier (PB0.02) carcasses than control cattle (Table 7). Cattle fed the 20% CM-based diets had reduced (P 0.05) dressing percentage and hot carcass weights (P 0.03) relative to those fed 10% CM-based diets. This again reflects the reduced energy content of CM relative to barley grain during finishing with the result that at the higher inclusion levels, both live and carcass gains were negatively Table 6. Comparison of overall performance of steers as affected by the type and level of canola meal included in the diet Canola meal type and inclusion level in the diet z B. napus B. juncea P value Control 11.3% y 22.6% y 11.3% y 22.6% y SEM D xw T w L w TL w n, animals (pen) 12 (5) 12 (5) 12 (5) 12 (5) 12 (5) Initial shrunk BW v (kg) Final shrunk BW v (kg) ADG z (kg d 1 ) DMI z (kg d 1 ) 10.1b 10.7a 10.6a 10.5ab 10.6a 0.11 B G:F z (kg kg 1 ) 0.152a 0.151a 0.147b 0.151ab 0.150ab NE zv m (Mcal kg 1 ) 1.84a 1.83ab 1.78b 1.82ab 1.81ab NE zu g (Mcal kg 1 ) 1.21a 1.19ab 1.15b 1.19ab 1.18ab z B. napus, Brassica napus; B. juncea, Brassica juncea; SEMstandard error of mean; Ddiet; Ttype of canola meal; Llevel of inclusion; TLtypelevel interaction; ADG, average daily gain; DMI, dry matter intake; G:F, gain:feed; NE m and NE g, net energy of maintenance and gain, respectively. y Based on 15 and 30% inclusion for 54-d backgrounding and 10 and 20% inclusion for 154-d finishing phase. x P value of diet based on all treatments including the control. w Tukey s test was performed for multiple comparison among diets when P50.05 on effect of diet (D). v Shrunken body weight calculated as 96% of liveweight (National Research Council 2001). u Calculated based on performance (Zinn and Shen 1998; Zinn et al. 2002). a, b Means without a common letter differ among all treatments (PB0.05).

8 606 CANADIAN JOURNAL OF ANIMAL SCIENCE Table 7. Effect of inclusion of solvent extracted canola meal derived from B. napus or B. juncea on carcass characteristics of feedlot steers as affected by type and level of canola meal included in the diet Canola meal type and inclusion level B. napus z B. juncea z P value Control 10% 20% 10% 20% SEM z D zyx T z L z TL z Hot carcass weight (kg) 377.8b 390.2a 376.8b 385.2ab 384.1ab Dressing percentage l. thoracis area (cm 2 ) z Grade fat (cm) Quality grade (%) w Canada B Canada A Canada AA Canada AAA 57.1a 33.3b 35.2b 41.8b 46.3ab Yield grade v Canada Canada Canada z B. napusbrassica napus; B. junceabrassica juncea; SEMstandard error of mean; Ddiet; Ttype of canola meal; Llevel of inclusion; TLtypelevel interaction; l. thoracislongissimus thoracis. y P value of diet based on all treatments including the control. x Tukey s test was performed for multiple comparison among diets when P50.05 on effect of diet (D). w Quality grade: B4 (dark); Canada Atraces; Canada AAslight; Canada AAAsmall or greater. v Yield grade: Lean meat yield,%: Canada 159% to more; Canada 2, 58 to 54%; Canada 3, 53% or less. a, b Means without a common letter differ among all treatments (PB0.05). affected. Although the CM type level interaction was not significant (P 0.06), it indicates that for hot carcass weight the negative response was primarily associated with cattle fed B. napus meal. Supporting this argument is the fact that grade fat thickness was greater (PB0.05) for cattle fed B. juncea relative to those fed B. napus meal. There was no effect of treatment on longissimus thoracis area or yield grade. Quality grade, in particular the percentage of cattle grading Canada AAA, was reduced (P0.01) by CM diets relative to the control diet (Table 7). Marbling or intramuscular fat deposition is highly dependent on dietary energy density as well as the timing/duration of feeding high-energy diets (Crouse et al. 1984). The reduced percentage of AAA carcasses for cattle fed CM-based diets, particularly those based on meal from B. napus, is further reflective of the reduced energy density in CM relative to barley grain. CONCLUSION These results indicate that substitution of CM for barley grain at levels up to 30% of the diet DM in backgrounding diets will improve ADG and DMI, but does not improve feed efficiency with the exception of the 30% B. juncea treatment, where it was improved relative to the control. Substituting CM as an energy source for barley grain in finishing diets, however, resulted in decreased G:F ratios and a reduced percentage of carcasses grading Canada AAA or better. Net energy of maintenance and gain was reduced at the higher level of CM inclusion irrespective of meal type when measured over the entire feeding period. These results indicate that CM, regardless of type, is lower in energy content than barley grain and that it is not an equivalent energy substitute for cereal grains in finishing diets. Current price differences between CM and barley grain would also limit its value as an energy source in backgrounding diets. Results from the present trial and the companion study (He et al. 2013) indicate that further research is needed to evaluate the rumen and total tract digestibility characteristics of these CM varieties in backgrounding and finishing diets in order to further understand their roles as energy sources for feedlot cattle. ACKNOWLEDGEMENTS Appreciation is expressed to the Saskatchewan Agriculture Development Fund and the Canola Council of Canada for funding the research. The authors thank the staff of the Beef Cattle Research Unit of University of Saskatchewan (Saskatoon, SK) for their support with carrying out of the feedlot trial. Assadi, E., Janmohammadi, H., Taghizadeh, A. and Alijani, S Nutrient composition of different varieties of full-fat canola seed and nitrogen-corrected true metabolizable energy of full-fat canola seed with or without enzyme addition and thermal processing. J. Appl. Poult. Res. 20: Association of Official Analytical Chemists Official methods of analysis. 17th ed. AOAC International, Gaithersburg, MD. Beliveau, R. M. and McKinnon, J. J Effect of graded levels of wheat-based dried distillers grains with solubles on performance and carcass characteristics of feedlot steers. Can. J. Anim. Sci. 88:

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