Two experiments were conducted to investigate the effects of canola seed (CS) andprocessing including grinding and pelleting condition on bird performance and nutrientutilization. The first experiment examined the apparent metabolizable energy (AME) of CS.A reference and test diet containing 150 g/kg CS was used. AME and AMEn values of CSwere 21.08 and 19.63 MJ/kg DM, respectively. The second experiment examined perfor-mance and digestibility and used a 2 × 3 factorial arrangement of treatments. Factors were:pelleting condition (cold-pelleted at 65 ◦C or steam-pelleted at 85 ◦C) and diet: canola mealplus oil, whole canola seed (WCS) or hammer-milled canola seed (HCS). A total of 672 maled-old Ross 308 broiler chicks were randomly assigned to treatments, each replicated eighttimes, with 14 birds per replicate. Birds received a common diet until d 10 when they weregiven test grower diets to d 24 followed by finisher diets from d 24 to d 35. Wheat-SBMbased test diets were isoenergetic and isonitrogenous. Grower and finisher contained CS at114 g/kg and 130 g/kg respectively, entirely replacing canola meal and canola oil in controldiets. Inclusion of CS decreased feed intake (FI) relative to control diets from d 10 to 35(P < 0.01). Regardless of pelleting, there was no difference in FI between birds fed eitherWCS or HCS. Weight gain (WG) was highest in control fed birds relative to WCS or HCSbetween d 10 and d 35 (P < 0.01). In the same period, HCS improved FCR of the birds com-pared to control (P < 0.05). From d 10 to d 24, an interaction between pelleting and dietwas detected for FCR indicating that steam-pelleting increased FCR in the birds fed WCS(P < 0.05). On d 24, ileal fat digestibility was reduced in birds fed WCS in steam-pelleteddiets resulting in an interaction between pellet condition and diet (P < 0.01). By same inter-action on d 35, steam-pelleting reduced fat digestibility in birds fed WCS or HCS (P < 0.001).It can be concluded that although inclusion of CS resulted in a depression for FI and WG, FCRwas improved in birds fed HCS in cold-pelleted diets. Prior grinding of CS did not benefitbird performance or nutrient utilization when compared with WCS.
Please cite this article in press as: Barekatain, M.R., et al., Effects of grinding and pelleting condition on effi-ciency of full-fat canola seed for replacing supplemental oil in broiler chicken diets. Anim. Feed Sci. Tech. (2015),http://dx.doi.org/10.1016/j.anifeedsci.2015.05.020
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1. Introduction
The price of fat and oil is increasing due to increased demand from the biofuel industry and food sector, and thus thecosts of broiler feed have subsequently increased. Some broiler producers are including full-fat canola seed (CS) in broilerdiets to reduce costs. Canola seed can contribute substantially more to the metabolizable energy (ME) than oil-extractedsolvent or expeller canola meal. It contains approximately 400 g/kg oil and 210–230 g/kg protein (Fenwick and Curtis, 1980)making it an attractive feed ingredient for broilers. However, the level of inclusion is typically below the amount for completeremoval of supplemental oil mainly due to concerns about residual glucosinolate and isothiocyanate. Research conductedby Summers et al. (1982) showed a reduction in weight gain and feed intake (FI) of broilers fed diets containing 175 g/kgor higher CS, but the quality of the diet was not a strong indicator of bird performance as the fat levels in the experimentaldiets were different. In another study conducted by Meng et al. (2006), inclusion of 150 g/kg CS in a mash diet from d 5 to18 resulted in lower fat and protein digestibility and negatively affected apparent ME corrected for nitrogen (AMEn) of thediet. These reports suggest uncertainty in nutrient utilization, and complete substitution of supplemental oil with CS hasnot been fully practiced in the poultry industry.
Other reports have indicated that grinding and heat treatment of CS are beneficial in enhancing the nutrient utilization(Muztar et al., 1978; Salmon et al., 1988). It is believed that disruption of structure resulting in degradation of subcellular lipidglobules may improve oil digestibility. In comparison to a mash diet, steam-pelleting was shown to enhance the nutritivevalue of whole CS in maize and soybean meal diets (Shen et al., 1983). However, to our knowledge, little is known aboutthe influence of pre-pellet hammer-mill grinding on CS utilization. The role of pelleting process on fat utilization in broilerdiets is still unclear. Furthermore, the effect of pelleting conditions, in particular temperature, for efficiency of CS is notfully understood. Thus, the present study was designed to determine AME of CS and examine performance and nutrientdigestibility of broilers fed diets containing CS as the major supplemental fat source. The effect of grinding and pelletingconditions on nutrient utilization were examined.
2. Materials and methods
2.1. Analysis of test articles
Table 1 shows the chemical analysis of the test articles CS and canola meal. Each sample was analyzed in duplicate usingAOAC (2005) methods of 982.30E for total lysine, 920.39 for crude fat, 975.44 for reactive lysine, 978.10 for crude fiber,973.18 for NDF and ADF, and 942.05 for ash at the Agricultural Experiment Station Chemical Laboratory at University ofMissouri with the exception of gross energy (GE) that was analyzed at University of New England using the method andequipment described in the AME section below.
2.2. Apparent metabolizable energy of CS
Two experimental diets were formulated as shown in Table 2. The reference treatment consisted of a common corn-soybean meal diet without enzyme supplementation, formulated to meet or exceed the nutrient requirements of broilerchickens as described in the Ross 308 manual (2007). The method of AME measurements was similar to the proceduresdescribed by Toghyani et al. (2014). Canola seed test diet contained 150 g/kg of the unground seed substituting the energyyielding ingredients of the reference diet. Both diets were fed in a pelleted form and fresh water and feed were availableto all birds for ad libitum intake throughout the experiment. A total of 72 male broiler chickens were used in the AMEmeasurement randomly assigned to 2 treatments each replicated 6 times. From d 1 to d 10 and d 10 to d 18, birds were fedconventional starter and grower diets respectively. From d 18, birds were fed the experimental diets (basal and CS test diets)for 4 d (adaptation period) followed by a 72-h energy balance assay from 22 to 25 d of age. During the 72-h collection period,feed consumption was recorded and the entire excreta were collected to calculate energy and nitrogen intake and excretion.The gross energy (GE) content of experimental diets and excreta were determined using an adiabatic bomb calorimeter(IKA® Werke, C7000, GMBH and Co., Staufen, Germany) with benzoic acid as the standard.
The AME and AMEn of the reference (basal) and test diets (DM basis) were determined using the following equations:
AME(MJ/kg) = (GEI − GEE)/FI
AMEn = AME −[8.22 × (NI − NE)/FI
]
The AMEn of the CS sample was calculated using the following formula:
CS AMEn (MJ/kg DM) = basal AMEn −[(basal AMEn − test diet AMEn)/percentage of inclusion rate
]
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where GEI is gross energy intake and GEE is gross energy output of excreta (MJ/kg of DM); 8.22 is nitrogen correction factor(Hill and Anderson, 1958); NI is nitrogen intake from the diet and NE is the nitrogen output from the excreta (kg); FI is thefeed intake (kg).
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Table 1Chemical analysis (g/kg unless otherwise specified) of solvent-extracted canola meal and full-fat canola seed used in the study (as is basis).a
a Values are the mean of duplicate samples.b Carpenter assay: fluoro dinitrobenzene reaction with epsilon amino group of lysine.c Acid detergent fiber.d Neutral detergent fiber.
Table 2Experimental diets for AME determination of canola seed.
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2.3. Experimental design and diets
A 2 × 3 factorial arrangement of treatments was employed to investigate CS inclusion under various pelleting conditions.Factors were: pelleting conditions: cold-pelleting (65 ◦C) or steam-pelleting (85 ◦C); and diet: canola meal + oil (control),whole canola seed (WCS), or hammer-milled canola seed (HCS). For HCS diets, seeds were finely ground before being mixedinto the compete diets. Experimental diets contained 114.5 g/kg CS or equivalent as solvent canola meal plus canola oil fromd 10 to 24 (grower) and 130 g/kg CS (or canola meal plus oil) from d 24 to 35 (finisher). All diets were formulated to meet therequirements of Ross 308 broiler chickens (Ross, 2007). Diets were formulated in such a way that CS replaced only canolameal and canola oil in the control diet so that no oil was supplemented to the diets containing CS.
To evaluate the effect of hammer milling, CS was first finely ground with wheat in a same proportion as formulated priorto adding to the mixer. A 2.0 mm hammer-mill screen was used to grind the seeds. Each of the diets was mixed and dividedinto two batches and then either steam-pelleted (85 ◦C) at The University of Sydney, Camden, NSW or cold-pelleted (nosteam at maximum 65 ◦C) at the University of New England, Armidale, NSW. A Palmer PP300 pellet press (Palmer MillingEngineering, Griffith, NSW, Australia) was used to steam-pellet the experimental diets located at the University of Sydney,Camden, NSW. The die dimensions were 4-mm diameter and 45-mm length. The conditioning temperature was beingautomatically regulated via a computer software package (Gordyn & Palmer, Hallam, Vic, Australia) equipped to the pelletpress (Selle et al., 2013). Cold-pelleting was undertaken at 65 ◦C and pelleting conditions were monitored and maintainedat a constant ampere draw of the load meter for the mill motor to ensure consistency of pelleting conditions for eachdiet (Toghyani et al., 2014). The ingredient composition, calculated nutrient composition and gross chemical analysis ofexperimental diets is given in Table 3. Protein and energy contents of the experimental diets were maintained at the samelevel. The CS sample was analyzed prior to feed formulation. The ME values of 37.26, 10.04, 8.37 MJ/kg were used for canolaoil, SBM and canola meal, respectively.
2.4. Housing and general management
A total of 672 male day-old Ross 308 broiler chickens, vaccinated for Marek’s disease and infectious bronchitis, wereobtained from the Baiada commercial hatchery in Tamworth, NSW. Forty eight floor pens (42 cm × 75 cm) were used withsoft wood-shavings as litter to house the birds in a climate-controlled system. The pens were randomly assigned to each ofsix treatments, with each replicated eight times, with 14 birds per replicate. Temperature was set at 33–34 ◦C on the first dayof the experiment and then gradually decreased by 1 ◦C every second day until a stable temperature of 24 ◦C was reachedby d 21. A lighting program of 18 h light and 6 h darkness was maintained throughout the trial except the first week whenbirds had 23 h of light. Birds had access to feed and water ad libitum. Feed consumption and body weight were recorded ona pen basis at the beginning and the end of each phase of feeding. FCR, corrected for mortality, was then calculated.
2.5. Sample collection and nutrient digestibility analysis
Ileal digesta and organs were sampled on d 24 and d 35. Three birds per replicate were randomly selected, weighedand subsequently euthanized by cervical dislocation. The empty weight of duodenum, jejunum, ileum, proventriculus, andgizzard were measured in one bird of each replicate. The ileal contents of three birds were collected by gentle squeezing ofileal contents into ice-cold plastic containers, and pooled by each replicate pen, and then stored at -20 ◦C and freeze-driedbefore conducting further analyses.
Dry matter and fat content of diets and digesta were determined using methods of AOAC (2005). The N content analysis ofthe diets and digesta samples was performed using a LECO FP-2000 automatic analyzer (Leco Corporation, MI, USA). Aminoacid determination was conducted by hydrolyzing the samples with 6 M HCl (containing phenol) for 24 h at 110 ± 2 ◦C inglass tubes sealed under vacuum conducted by Evonik Ltd, Singapore. Titanium contents of ileal and diet samples weremeasured using a UV spectrophotometer following the method described by Short et al. (1996). Subsequent digestibilitycoefficients for different nutrients were calculated using the following formula:
Apparent ileal digestibility coefficient:
= (NT/Ti)d − (NT/Ti)i
(NT/Ti)d
where, (NT/Ti)d was the ratio of nutrient (NT) and titanium (Ti) in diet; (NT/Ti)i was the ratio of nutrient (NT) and titanium(Ti) in ileal digesta.
The Animal Ethics Committee of the University of New England approved all the experimental procedures.
2.6. Statistical analysis
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The six treatments of three diets (control, WCS and HCS) and pelleting conditions (cold- and steam-pelleted) in a 3 × 2factorial arrangement were subjected to statistical analysis using 2-way ANOVA of GLM procedure of SAS (2003) to assessthe main effects and 2-way interactions. Data were checked for normal distribution. One cage constituted an experimentalunit and the values presented in the tables are means with pooled standard error of mean (SEM) (n = 48). If a significant
a Formulated to supply 12,000 IU vitamin A, 5000 IU vitamin D3, 75 IU vitamin E, 3 mg vitamin K, 3 mg, thiamine, 8 mg riboflavin, 55 mg nicotinic acid,13 mg pantothenic acid, 5 mg pyridoxine, 0.2 mg biotin, 2.0 mg folic acid, 0.016 mg vitamin B12 per kg of diet.
b Formulated to supply 16 mg copper, 1.25 mg iodine, 40 mg iron, 120 mg manganese, 0.30 mg selenium and 100 mg zinc per kg of diet.c Phyzyme® XP TPT (Danisco Animal Nutrition – DuPont) provided phytase activity of 500 FTU/kg feed. The product is thermostable up to 95 ◦C.
es
3
3
Ta
(dfww
d Xalanase (Danisco Animal Nutrition – DuPont) provided activity of 2000 FTU/kg of feed.e Values in parenthesis are measured amino acids (total).
ffect was detected, differences between treatments were separated by a Least Significant Difference test (Fisher’s test). Alltatements of significance are considered on a P-value less than 0.05. Tendencies were specified for 0.05 < P < 0.10.
. Results
.1. Chemical analysis, metabolizable energy and growth performance
The results of proximate analysis, amino acids and reactive lysine conducted on CS and canola meal are shown in Table 1.he measured AME and AMEn values of CS determined in experiment 1 were 21.08 and 19.63 MJ/kg DM, respectively andre shown with the diets in Table 2.
In feeding trial, dietary treatments significantly affected FI of the birds as shown in Table 4. Inclusion of CS to the dieteither hammer-milled or whole) decreased (P < 0.01) FI compared to birds consuming the control diet (d 10–d 35). Noifference in FI between birds receiving WCS and HCS was detected for the finisher phase of feeding and when assessed
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or d 10–d 35. A pellet condition by diet interaction was detected for FI during the d 10–d 24 period (P < 0.05) that the FIas lower in birds fed both WCS and HCS than those fed the control diet when the diets were subjected to cold-pelletinghereas FI was lower only in the birds fed HCS when compared to those fed control diets subjected to steam-pelleting.
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Table 4Effect of canola seed inclusion, whole (WCS) or hammer-milled (HCS) and pelleting condition on performance of broiler chickens from d 10 to 35.a,b
Diet Pellet Feed intake (g/bird) Body weight gain (g/bird) FCR
d 10–24 d 24–35 d 10–35 d 10–24 d 24–35 d 10–35 d 10–24 d 24–35 d 10–35
Canola meal + oil Cold 1549 a 2125 3674 1102 1321 2423 1.415 a 1.609 1.518Steam 1503 ab 2098 3601 1100 1289 2389 1.366 ab 1.628 1.507
WCS Cold 1457 bc 1989 3446 1092 1263 2355 1.334 b 1.577 1.463Steam 1501 abc 2014 3515 1056 1273 2329 1.423 a 1.584 1.510
HCS Cold 1490 bc 1965 3456 1094 1236 2330 1.363 ab 1.592 1.484Steam 1453 c 1986 3439 1068 1293 2361 1.361 ab 1.537 1.457SEM 6.99 12.84 15.48 6.99 8.73 9.18 0.010 0.008 0.006
Main effectsCanola meal 1526 2111 a 3637 a 1101 1305 2406 a 1.390 1.619 a 1.513 aWCS 1479 2002 b 3481 b 1074 1268 2342 b 1.378 1.581 ab 1.486 abHCS 1472 1976 b 3447 b 1081 1264 2345 b 1.362 1.564 b 1.470 bCold- pelleted 1499 2026 3525 1096 1273 2369 1.371 1.592 1.488Steam- pelleted 1486 2033 3518 1075 1285 2360 1.383 1.583 1.491
a Each value for each treatment represents the mean of 8 replicates.b Means within a column not sharing a superscript differ significantly at the P < 0.05 level for the treatment effects and at the P level shown for the main
effects.
Table 5Effect of canola seed inclusion, whole (WCS) or hammer-milled (HCS) and pelleting condition on relative weight (g/100 g body weight) of organs anddifferent intestinal segments of broiler chickens at d 24 and 35.a,b
a Each value for each treatment represents the mean of 8 replicates.b Means within a column not sharing a superscript differ significantly at the P level shown for the main effects.
Weight gain (WG) was reduced (P < 0.05) as a result of inclusion of CS from d 10 to d 35 as shown in Table 4. An interactionbetween pelleting condition and diet was detected for FCR from d 10 to d 24 (P < 0.05). This indicated that FCR was improvedby cold-pelleting compared to steam-pelleting in birds fed WCS but not other diets. In addition, inclusion of HCS improved(P < 0.05) FCR from d 24 to d 35 or d 10 to d 35 compared to control only. No effect of treatments was observed on mortality ofthe birds throughout the study. Total mortality rate was 2.3% for the entire trial and was not related to any of the experimentaldiets.
3.2. Intestinal and organ weights
Relative organ weights collected from birds on d 24 and 35 are shown in Table 5. Gizzard weight was higher in the birdsfed steam-pelleted diets than cold-pelleted at d 24 and d 35 (P < 0.01). Similarly, feeding HCS resulted in heavier gizzardscompared to the birds fed control diets at d 35 (P < 0.05). The relative weights of duodenum (P < 0.05) and jejunum (P < 0.01)were greater in birds fed HCS compared to birds fed WCS diets. There was no interaction between pelleting condition anddiet for all the relative weight of organs measured.
Please cite this article in press as: Barekatain, M.R., et al., Effects of grinding and pelleting condition on effi-ciency of full-fat canola seed for replacing supplemental oil in broiler chicken diets. Anim. Feed Sci. Tech. (2015),http://dx.doi.org/10.1016/j.anifeedsci.2015.05.020
3.3. Nutrient digestibility
As shown in Table 6, an interaction between diet and pelleting condition was detected for the ileal N digestibility at d 35(P < 0.05). Steam-pelleting led to increased N digestibility in the birds fed WCS, but decreased N digestibility in the birds fed
a Each value for each treatment represents the mean of 8 replicates.b Means within a column not sharing a superscript differ significantly at the P < 0.05 level for the treatment effects and at the P level shown for the main
effects.
Table 7Effect of canola seed inclusion, whole (WCS) or hammer-milled (HCS), and pelleting condition on ileal amino acid digestibility coefficients of grower dietsat d 24.a,b
a Each value for each treatment represents the mean of 8 replicates.b Means within a column not sharing a superscript differ significantly at the P < 0.05 level for the treatment effects and at the P level shown for the main
ffects.
SC (P < 0.05), whereas no change was observed in control birds as a result of pellet temperature. Pelleting conditions hadifferent influences on N digestibility in different diets, where steam-pelleting increased N digestibility in WCS fed birds,ecreased N digestibility in HCS fed birds, and had no effect in the control group. Interaction between diet and pelletingondition was also detected for ileal fat digestibility at d 24 (P < 0.05) and d 35 (P < 0.001). At d 24, steam-pelleting at 85 ◦Ceduced fat digestibility in birds fed WCS while there was no effect on birds fed HSC or control diets. Fat digestibility wasncreased (P < 0.01) in birds fed WCS compared to those fed HCS when diets were cold-pelleted, the opposite of this result
as observed in the birds fed steam-pelleted diets. At d 35, an interaction between diet and pelleting condition was againbserved for fat digestibility (P < 0.001). Fat digestibility was lower in birds fed both CS containing diets as compared to thoseed control diets when steam-pelleting was applied, whereas such a difference was not observed in birds fed cold-pelletediets. At d 35, steam-pelleting significantly reduced ileal DM digestibility compared to cold-pelleting (P < 0.05). There was a
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endency (P = 0.066) for birds fed HCS to have lower ileal DM digestibility compared to controls.As shown in Tables 7 and 8, CS inclusion did not influence amino acid digestibility values at d 24 except for ileal Met
igestibility where a diet × pelleting condition interaction was detected (P < 0.05). Steam-pelleting resulted in higher ilealet digestibility than did cold-pelleting in birds fed HCS and control diets but not in the WCS group. Birds fed WCS had higher
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Table 8Effect of canola seed inclusion, whole (WCS) or hammer-milled (HCS), and pelleting condition on ileal amino acid digestibility coefficients of grower dietsat d 24.a,b
Main effectsCanola meal + oil 0.834 0.772 0.752 0.780 0.832 0.777 0.760 0.874WCS 0.842 0.774 0.762 0.783 0.845 0.786 0.766 0.885HCS 0.832 0.779 0.767 0.788 0.845 0.785 0.770 0.882Cold-pelleted 0.829 b 0.768 b 0.754 0.775 b 0.832 b 0.773 b 0.751 b 0.871 bSteam-pelleted 0.843 a 0.786 a 0.767 0.793 a 0.850 a 0.792 a 0.780 a 0.890 a
a Each value for each treatment represents the mean of 8 replicates.
b Means within a column not sharing a superscript differ significantly at the P level shown for the main effects.
ileal Met digestibility than those fed the control diet when cold-pelleted but not steam-pelleted (P < 0.05). Steam-pelletingled to higher ileal digestibility of Met, Ile, Leu, Val, His, Phe, Ser, Pro, Ala, Asp, Glu (P < 0.05) when compared to cold-pelleting.
4. Discussion
The AME content of CS for broilers reported in the literature is variable (Sibbald, 1977; Muztar et al., 1978, 1981; Assadiet al., 2011) ranging from 18.42 to 22.06 MJ/kg. This may be attributed to several factors including grinding and texture ofthe seed, agronomic differences, nutrient contents, antinutritional factor levels, and differing response of individual birds tothe palatability and seed texture (Sibbald, 1977; Assadi et al., 2011). The oil content of the CS samples used in the currentexperiment may provide evidence for relatively high AME value of the seed. The values of AME and AMEn are similar tothose reported by Assadi et al. (2011).
Taking improved FCR into consideration, it is evident from the results of the current study that the growth response of birdsfed cold-pelleted WCS and HCS with no supplemental oil was comparable to the control birds in the grower phase (d 10–d 24)with 114 g/kg CS in the diets. This is in agreement with previous studies (Salmon et al., 1988; Ajuyah et al., 1991) and is alsoin line with the nutrient digestibility values for DM, nitrogen and amino acids at the end of growing phase when no negativeimpact was observed attributed to the inclusion of WCS. It is noteworthy that the assessment of the entire period of studyshowed that WG in the birds fed WCS and HCS was approximately 60 g lower than control group. However, the improvedFCR of 2.7 and 4.3 points in the birds fed WCS (albeit not statistically significant) and HCS respectively, relative to canolameal plus oil would be expected to more than economically offset the lower WG (data not shown). Nevertheless, the adverseeffect of WCS or HCS inclusion on FI could possibly be a result of higher residual isothiocyanate levels in diets containing seedvs. meal, although not directly measured in the current trial. Isothiocyanates are formed from glucosinolates through theaction of the enzyme myrosinase (Tripathi and Mishra, 2007). The degree of adverse effect of dietary glucosinolate dependson the level and compositions of glucosinolates and their breakdown products. The breakdown products isothiocyanateand 5-ethenyl-1,3-oxazolidine-2-thione (goitrin) are known to be extremely bitter compounds (Tripathi and Mishra, 2007).Solvent-extracted canola meal undergoes heat treatment during processing to reduce myrosinase activity whereas the onlyheat treatment in diets containing WCS or HCS in the current study was from pelleting. Summers et al. (1982) concludedthat in broilers fed WCS, lower FI may be a problem and is likely attributed to diet palatability. This was indeed observedin the finisher period of the current study and was reflected in the overall 35 day performance. It is hypothesized that thedietary CS reduced palatability, FI and subsequent growth rate relative to canola meal plus oil in the current study dueto higher levels of active myrosinase and subsequent higher levels of hydrolyzed and products in seed relative to solventextracted meal. Further investigation is needed to elucidate any effect arising from myrosinase activity. Pellet quality of suchdiets and level of glucosinolate and erucic acids (Olomu et al., 1975) may also be regarded as determinants of the growthperformance and warrant more investigation as high levels of CS likely to have adverse effect on pellet durability index
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as well.In general, grinding may be used to disrupt the cell wall structure of feed ingredients and oil body structure within oil
seeds thus increasing the exposure of nutrients to the digestive enzymes which is believed to positively impact the birdperformance (Meng et al., 2006; Assadi et al., 2011). It is already well demonstrated that grinding WCS in mash diets favors
M.R. Barekatain et al. / Animal Feed Science and Technology xxx (2015) xxx–xxx 9
ird performance and ME content of the seed (Muztar et al., 1978; Shen et al., 1983). In the current study, however, grindingS with a hammer mill resulted in no additional improvement for the growth performance or nutrient digestibility whenroilers were fed pelleted diets suggesting that pelleting process per se may have possibly provided sufficient breakage tohe seed, therefore diminishing the influence of pre-pelleting grinding of CS. In addition, if pelleting does indeed sufficientlyulverize WCS and reduce myrosinase activity, higher levels of CS than those tested might be possible in the diet of broilersithout compromising the growth response (Shen et al., 1983). This would pose an interest for the commercial use of WCS
s the grinding process of CS would be cumbersome due to high oil content and small seed size. The grinding prior toiet preparation may also accelerate lipid oxidation and may reduce shelf life of the diet (Jia et al., 2008). Thus, it may bedvantageous to feed the CS without grinding when the diet is pelleted. However, it has been demonstrated that grindingf WCS is necessary when used in mash diets as seed rupture is necessary to optimize the nutrient utilization (Shen et al.,983).
Inclusion of HCS in the diets resulted in heavier gizzard and duodenum at the end of study. Possible influence of textureardness of the seed compared to the control diets may explain this observation. It is noteworthy that such effect wasot statistically significant for WCS fed birds for which there is no apparent explanation. Furthermore, steam-pelleting inhis experiment resulted in a higher relative weight of gizzard at both grower and finisher phase of feeding. Comparedo cold-pelleting, higher temperature applied to diets during steam-pelleting may have possibly influenced the hardnessnd pellet durability as shown by Abdollahi et al. (2010). Stimulatory effect of pellet hardness on gizzard developmentay therefore explain the heaver gizzards in the birds fed steam-pelleted diets because harder pellets will require moreechanical grinding leading to a well-developed gizzard (Abdollahi et al., 2010). It has also been shown by Abdollahi et al.
2011) that the proportion of particles in pelleted diets may increase by rising conditioning temperatures. They postulatedhat lubricative impact of moisture led to a decreased frictional force in die holes and higher amount of coarse particlesn diets pelleted at higher temperature that may possibly further explain the higher relative weight of gizzard in birds fedteam-pelleted diets.
In the finisher phase of feeding in contrast to the grower phase, inclusion of 130 g/kg WCS and HCS in the diets reducedat and N digestibility showing an interaction between pelleting method and diet. These differences for the digestibilityalues of grower and finisher diets may be attributed to the higher inclusion of WCS and HCS in finisher diets and may haveagnified the impact on nutrient utilization. Meng et al. (2006) showed that feeding WCS in mash diets had a negative
mpact on ileal fat, protein and AMEn content of the diet compared with canola meal plus oil. In the current experimentll diets were pelleted which may, at least in part, explain the discrepancy between our observations and those madey Meng et al. (2006) who fed mash diets. Some portion of oil in WCS may still be encapsulated in the peptide shell oilody structures impeding maximum fat utilization (Slominski et al., 2006). Supplementation of diets containing WCS withhytase and carbohydrases has been shown to be effective in minimizing fat encapsulation and therefore maximize nutrienttilization (Jozefiak et al., 2010). It is therefore possible that enzyme supplementation with protease, carbohydrase andhytase might contribute to enhanced bird performance in diets containing WCS at even higher levels than tested in theurrent experiment.
Utilization of DM and most amino acids were not affected by feeding of CS. These observations confirm similar availabilityf amino acids between the CS and canola meal as well as proving potential benefit of incorporation of canola in poultry dietsBarbour and Sim, 1991). It can be said that the heat labile amino acids Lys and Cys in particular were not affected by steamelleting when compared to cold pelleting. The effect of steam conditioning and pellet temperature on digestibility of fat inS, to our best knowledge, has not been studied. Therefore, further research is needed to compare WCS inclusion in mash andelleted diets in order to elucidate the effect of pelleting and grinding on nutrient utilization. In the current study, the growthesponse of birds fed steam- or cold-pelleted did not differ regardless of diet composition. However, the interaction betweenhe diet and pelleting condition indicated that steam-pelleting may reduce DM and fat digestibility in diets containing wholer hammered seeds although steam-pelleting improved amino acid digestibility. Abdollahi et al. (2011) showed that applying5◦ and 90◦ C for the steam conditioning had a negative effect on nutrient utilization and performance of wheat based broileriets compared to 60◦ C. However, in that experiment the fat digestibility was not examined. In the present study, the lowerat digestibility was observed in the WCS diets subjected to steam pelleting and high conditioning temperature. Pelletingrocess has been shown to have substantial effects on feed component, gastrointestinal development and subsequent birderformance (Abdollahi et al., 2013). In our study, we used two different pellet presses with same die size to compareold-pelleting and steam-pelleting for the same batch feeds. Thus, it is probable that in addition to the effect of appliedemperatures and steam conditioning, some less controllable pelleting process characteristics such as die frictional forceave been different for the two pelleting machines affecting the degree of starch gelatinization, starch damage and proteinuality (Abdollahi et al., 2013). Regarding fat digestibility for finisher diets, a negative effect of carbohydrate solubilizationay also play a role in fat utilization, however little contribution of soluble carbohydrate is expected from CS particularly
t low level of inclusion. It may also be possible that phytase and xylanase used in the study have been somehow partiallyeactivated by high temperature of steam-pelleting. Therefore, in comparison with cold-pelleting, the nutrient utilizationay have been affected. This effect was not seen for control diets which may be related to the fact that control diets contained
Please cite this article in press as: Barekatain, M.R., et al., Effects of grinding and pelleting condition on effi-ciency of full-fat canola seed for replacing supplemental oil in broiler chicken diets. Anim. Feed Sci. Tech. (2015),http://dx.doi.org/10.1016/j.anifeedsci.2015.05.020
o CS. Nevertheless, such explanation still does not apply to the birds fed grower diets containing HCS which makes it difficulto draw a firm conclusion to explain the interaction between diets and pelleting conditions for fat utilization. This requiresurther investigation.
10 M.R. Barekatain et al. / Animal Feed Science and Technology xxx (2015) xxx–xxx
5. Conclusion
It can be deduced from the current study that supplemental oil may be replaced by WCS and HCS in cold-pelleted growerdiets. However, regardless of pelleting conditions, the inclusion of WCS and HCS in diets particularly at a higher level infinisher diets may result in a depression in FI and WG which may not be compensated by an improved FCR when the seed isnot ground prior to pelleting. The lack of performance differences in birds fed pelleted diets containing WCS or HCS suggeststhat CS may be included in growing broiler pelleted diets without grinding at the tested level. However, pelleting conditionsremains as a determining factor when using high levels of CS in broiler diets given that the steam-pelleting at 85 ◦C decreasedfat digestibility of broilers fed CS in particular for finisher diets.
Conflict of interest
The authors have no conflict of interest to declare.
Acknowledgments
This research was conducted within the Poultry CRC, established and supported under the Australian Government’sCooperative Research Centers Program. We are thankful of the help of Aaron Cowieson and University of Sydney for steampelleting feeds. The amino acid analysis of all diets and digesta samples were conducted by Evonik (South East Asia) Pte. Ltd.(Singapore) for which we are grateful.
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