The Evaluation of Dehulled Canola Meal as a Replacement for Soybean Meal in the Diets of Growing and Finishing Pigs

Transcription

1 The Evaluation of Dehulled Canola Meal as a Replacement for Soybean Meal in the Diets of Growing and Finishing Pigs J.F. Patience, D. Gillis and C.F.M. de Lange Executive Summary The major restriction to expanded use of canola meal in swine diets is its low level of energy digestibility. There are many approaches that one might take to address this problem, but in this series of experiments, mechanical dehulling was considered as one possible alternative. Therefore, two experiments were conducted to evaluate the acceptability of dehulled canola meal to swine and to determine the performance of growing and finishing pigs using this product to replace at least half of the soybean meal in their diet. The acceptability study revealed some problems with the product, as the pigs reduced feed intake in approximate proportionate to the quantity of dehulled canola meal in the diet. In the performance study, the pigs performed very well on the diets containing dehulled canola meal, suggesting that the product can be used successfully in swine diets. Dehulled canola meal has considerable promise in the pig industry, if the dehulling process is economical and can produce a uniform product. Because there appears to be a tendency to concentrate certain antinutritional factors in the low fibre fraction, care must be taken to ensure that this is minimised. Introduction Canola meal has achieved considerable success in the Canadian feed industry, supplying protein in varying proportions relative to soybean meal in swine, cattle and poultry diets. However, it has not yet achieved the stature of soybean meal in the Canadian feed market, due in part to its relatively low concentration of digestible energy (Patience et al., 1995). The low digestible energy content in the meal is due in large part to the presence of the hull which constitutes about 16% of the seed and about 25% of the meal; the hull fraction has a very low digestibility (Bell and Shires, 1982). Some research had previously been carried out on dehulled Westar canola meal. Christison and Bell (1992) reported that as dehulled canola meal replaced increasing quantities of soybean meal, growth rate and feed intake declined. Feed conversion was affected to a much lesser extent, suggesting that palatability and not nutrient availability was the problem. This was confirmed by digestibility studies which revealed that as dehulled canola meal replaced soybean meal, energy and nitrogen digestibility remained essentially constant. However, related work on growing pigs suggested no improvement in nutrient utilization in dehulled meal as compared to commercially-available canola meal (Bell, 1993). Further research was therefore requested by the industry to determine if newer approaches to dehulling could overcome the inconsistent response and provide an opportunity to increase canola meal utilization in swine. The opportunity certainly exists to expand canola meal utilization in Canada, as the acreage assigned to canola seed is rapidly expanding. For example, more than 4 million hectares were seeded to canola in 1993, an increase of 40% since 1991 (Canada Grains Council, 1993). Prairie Swine Centre Inc., Saskatoon, Canada. Monograph No

2 Objectives 1. To determine the acceptability to growing and to finishing pigs of dehulled canola meal. 2. To determine the performance of pigs fed dehulled canola meal as a replacement for soybean meal. Materials and methods Acceptability studies In the first experiment, growing pigs and finishing pigs were used to investigate the willingness of pigs to consume diets containing increasing amounts of dehulled canola meal in replacement of soybean meal over a four week period. Forty gilts with an average starting weight of 24.2 kg, and another 40 gilts with an average starting weight of 58.4 kg were used in the growing and finishing trials, respectively. In both trials, pigs were housed in individual pens measuring 1.83 m X 0.91 m and equipped with fully-slatted concrete floors, PVC-planking pen dividers, one single-space aluminum dry self-feeder and one nipple drinker. An one-week acclimation period prior to the start of the experiment allowed the pigs to adjust to the pen and their new surroundings. At weekly intervals over the four week experimental period, feed disappearance and bodyweight change were determined. Four experimental diets were used for the study with growing pigs (Table 1). They represented a transition, in 4 steps, from no dehulled canola meal (control) to complete replacement of soybean meal. Thus, dehulled canola meal represented 0%, 8.5%, 17.0% or 25.5% of the diets. The finisher diets (Table 4) were similarly formulated, representing a transition, in 4 steps, from no dehulled canola meal (control) to complete replacement of soybean meal. Thus, dehulled canola meal represented 0%, 7.7%, 15.4% and 23.1% of the diets. In all cases, diets were formulated within phase to contain equivalent amounts of digestible energy, total amino acids and macrominerals. Based on an earlier digestibility experiment (de Lange, 1993), the D.E. content of dehulled canola meal was found to be 3,608 kcal/kg, while that of normal, hulled canola meal was 3,126 kcal/kg, expressed on an as fed basis. The grower diets contained 3200 kcal DE/kg and 0.90% lysine; the finisher diets contained 3200 kcal DE/kg and 0.85% lysine. Performance studies The second experiment similarly consisted of two parts, one to evaluate pigs in the growing phase and a second for pigs in the finishing phase. Pigs were housed 6 per pen in pens measuring 2.36 m X 1.68m (growing phase) or 5 pigs per pen in similarly sized pens (finishing phase). Each pen was equipped with fully-slatted concrete floors, PVC-planking pen dividers, one single-space aluminum dry self-feeder and one nipple drinker. Four experimental diets was used for the study with growing pigs (Table 3) and four different diets were used for the finishing experiment (Table 4). In each instance, the control diet contained soybean meal as Prairie Swine Centre Inc., Saskatoon, Canada. Monograph No

3 the sole protein supplement. In the second test diet, canola meal was used to replace 95% of the soybean meal (grower trial) or 50% of the soybean meal (finishing trial). Dehulled canola meal was incorporated into the final two test diets at the rate of 15% (grower trial) or 10% (finishing trial). A second dehulled canola diet contained supplemental energy (100 kcal/kg) and amino acids, to determine if energy and/or amino acids were possibly limiting animal performance, that is to determine if the digestible energy or amino acid content of dehulled canola meal had been previously overestimated. Pigs were selected for test on the basis of bodyweight and sex; there were 2 blocks of males and 3 blocks of females in the each of the growing and of the finishing trial. In the growing trial, each weight block started on test when the block average weight was 25±3 kg; pigs were then weighed biweekly until the pen average weight was 60 kg at which time the pen was removed from the experiment. In the finishing phase, each weight block started on test when the block average weight was 70±3 kg; pigs were then weighed biweekly until the heaviest pen within the block reached a minimum average weight of 105 kg, at which time that block was considered to be off test for the performance portion of the study. However, the pigs remained on the experimental diets until they were marketed at a body weight of approximately 106 kg. These experiments were reviewed internally at Prairie Swine Centre Inc. and by the University of Saskatchewan Animal Care Committee to ensure adherence to Canadian Council of Animal Care guidelines. Chemical Analysis The dehulled canola meal was analysed by Dr. Sandy McCurdy, POS Pilot Plant, Saskatoon for phytate, sinapine and glucosinolate content. Statistical Methods All data were analyzed by analysis of covariance, with initial weight as the covariate, using the GLM option of SAS (SAS Institute, Inc., 1985) according to the Randomized Complete Block design of the experiment. Effects due to initial weight and block were identified along with treatment. Results Experiment 1 Overall performance on the control diets was very good. Growing pigs on the control diet achieved an average daily gain of 0.87 kg/day and a feed conversion of 2.26:1; finishing pigs on the control diet grew at the rate of 0.96 kg/day with a feed conversion of 2.94:1. The overall results of the two trials are summarized in Table 5. During the growing period, increasing the content of dehulled canola meal resulted in a linear decrease in average daily gain, average daily feed and feed efficiency (P < 0.05). During the finishing period, the reduction was much more modest and was not statistically significant P > 0.05). The reduction in feed intake approached statistical significant (P < 0.10). The weekly data for the first experiment are presented in Tables 6 (growing phase) and 7 (finishing phase). While the reduction in average daily gain, average daily feed and feed ecfficiency associated with Prairie Swine Centre Inc., Saskatoon, Canada. Monograph No

4 increasing dietary proportions of dehulled canola meal appeared throughout the 28-day experimental period, the greatest decline occurred earlier in the study, suggesting that some degree of adaptation took place. The weekly data for the finishing phase also revealed an early reaction by the pigs to the presence of dehulled canola meal. The response appeared to be somewhat dose dependent. Significant reductions in average daily gain and average daily feed were observed in week 1 (P < 0.05); the decline in feed efficiency during the first week approached statistical significance (P < 0.10). By the fourth week, feed intake was very similar across all treatments. Experiment 2 In experiment 2, the pigs responded very well to the dehulled canola meal, with no reduction in average daily gain, average daily feed or feed efficiency during the finishing period (P > 0.05) and only a trend (P < 0.10) towards reduced average daily gain in the growing period. The performance of the pigs fed canola meal was identical to those fed soybean meal, although feed conversion did appear to be somewhat poorer than the control (P > 0.05). There was no suggestion that energy or protein quality had been underestimated in the dehulled canola meal, as the performance on the two diets based on the new product were similar to the that on the control treatment. Similarly, there was no effect of dietary treatment on carcass traits, such as leanness, fatness or predicted yield. Based on overall index, animals on all treatments produced high quality carcasses. Discussion Mechanical dehulling of canola has been viewed as one way to address the issue of low energy digestibility in the resulting meal. The demand for higher energy diets puts canola meal at a disadvantage compared to soybean meal in the domestic and global marketplace. In the first experiment, the pigs did not accept the dehulled meal very well, particularly in the growing period, suggesting that palatability could be an issue with the new product. The reduction in feed intake was much less pronounced in the finishing pigs. Part of the explanation could be the higher levels of glucosinolates and sinapine which appeared to concentrate in the dehulled meal (Table 10). In the second experiment, pigs performed very well on the dehulled meal, showing almost signs of refusal and performing equal to those pigs fed the soybean meal control diet. Performance of both the growing pigs and the finishing pigs was excellent, demonstrating that dehulled canola meal can be successfully incorporated into diets for high producing pigs. Thus, formulating diets using dehulled canola meal to be isocaloric and estimated to be equal in meeting the pigs needs for essential amino acids resulted in excellent performance and suggests that, if the process of mechanical dehulling is feasible, offers considerable promise to the canola industry. Care would have to Prairie Swine Centre Inc., Saskatoon, Canada. Monograph No

5 be focused on the various antinutritional factors in canola, such as glucosinolates and sinapine to ensure that they are not concentrated in the low fibre fraction resulting from dehulling. References Bell, J.M Nutritional evaluation of dehulled canola meal for swine. Pages in 10th Project Report: Research on Canola Seed, Oil and Meal. Canola Council of Canada, Winnipeg, MB. Bell, B.J. and Shires, A Composition and digestibility by pigs of hull fractions from rapeseed cultivars with yellow and brown seed coats. Can. J. Anim. Sci. 62: Canada Grains Council Canadian Grains Industry Statistical Handbook 93. Canada Grains Council, Winnipeg, Manitoba, Canada. Christison, G.I. and Bell, J.M Dehulled canola meal for weanling pigs. Pages in Ann. Res. Rpt., Prairie Swine Centre, Saskatoon, SK. Patience, J.F., Thacker, P.A. and de Lange, C.F.M Swine Nutrition Guide. Prairie Swine Centre Inc., Saskatoon, SK. 274 pp. SAS Institute Inc SAS user s guide: Statistics. 5th Ed. SAS Institute, Inc. Cary, NC. 956 pp. Prairie Swine Centre Inc., Saskatoon, Canada. Monograph No

6 Table 1. Formulation of diets utilized in the acceptance trial with growing pigs - Expt. 1. Diet 1 Diet 2 Diet 3 Diet 4 INGREDIENTS Barley Wheat - HRS Soybean meal - 47% Dehulled canola meal Dicalcium phosphate Limestone Salt PSC Vitamin premix PSC Mineral premix Canola oil NUTRIENTS D.E., kcal/kg Crude protein, % Lysine, % T.S.A.A., % Threonine, % Calcium, % Phosphorus, % Sodium % NB. All amino acid contents are presented as total amounts. 1 Provided per kg of diet: Vitamin A, 8,250 IU; Vitamin D 3, 825 IU; Vitamin E, 40 IU; menadione, 4 mg; thiamine, 1 mg; riboflavin, 5 mg; niacin, 35 mg; d-panthothenic acid, 15 mg; Vitamin B 12, 25 µg; d-biotin, 200 µg; folic acid, 2 mg. 2 Provided per kg of diet: copper, 50 mg; iron, 80 mg; manganese, 25 mg; zinc, 100 mg; iodine, 0.5 mg; selenium, 100 µg. Prairie Swine Centre Inc., Saskatoon, Canada. Monograph No

7 Table 2. Formulation of diets utilized in the acceptance trial with finishing pigs - Expt. 1. Diet 5 Diet 6 Diet 7 Diet 8 INGREDIENTS Barley Wheat - HRS Soybean meal - 47% Dehulled canola meal Dicalcium phosphate Limestone Salt PSC Mineral premix PSC Vitamin premix Canola oil NUTRIENTS D.E., kcal/kg Crude protein, % Lysine, % T.S.A.A., % Threonine, % Calcium, % Phosphorus, % NB. All amino acid contents are presented as total amounts. 1,2 Please refer to Table 1 for details on vitamin and trace mineral supplementation levels. Prairie Swine Centre Inc., Saskatoon, Canada. Monograph No

8 Table 3. Formulation of diets utilized in the performance trial with growing pigs - Expt. 2. Ingredient Diet 9 Diet 10 Diet 11 Diet 12 Barley Wheat Soybean meal - 47% Canola meal Dehulled canola meal Lysine HCl dl-methionine l-threonine Dicalcium phosphate Limestone Salt PSC Mineral premix PSC Vitamin premix Canola oil Nutrients, calculated DE, kcal/kg 3,200 3,200 3,200 3,300 Protein, % Lysine, % dlysine, % dt.s.a.a., % dthreonine, % dtryptophan, % dtsaa:dlys dthr:dlys dtrp:dlys Calcium, % Phosphorus, % Sodium, % Chloride ,2 Please refer to Table 1 for details on vitamin and trace mineral supplementation levels. Prairie Swine Centre Inc., Saskatoon, Canada. Monograph No

9 Table 4. Formulation of diets utilized in the performance trial with finishing pigs - Expt. 2. Ingredient Diet 13 Diet 14 Diet 15 Diet 16 Barley Wheat Soybean meal - 47% Canola meal Dehulled canola meal Lysine Hcl dl-methionine l-threonine Dicalcium phosphate Limestone Salt PSC Mineral premix PSC Vitamin premix Canola oil Nutrients, calculated DE, kcal/kg 3,200 3,200 3,200 3,300 Protein, % Lysine, % dlysine, % dt.s.a.a., % dthreonine, % dtryptophan, % dtsaa:dlys dthr:dlys dtrp:dlys Calcium, % Phosphorus, % Sodium, % Chloride ,2 Please refer to Table 1 for details on vitamin and trace mineral supplementation levels. Prairie Swine Centre Inc., Saskatoon, Canada. Monograph No

10 Table 5. Overall effect of dehulled canola meal on the average daily gain, average daily feed and feed conversion of pigs during the growing and finishing phases - Expt. 1. Percent Dehulled Canola Meal S.E.M. Significant Item 0/0 8.5/ / /28.1 Effect 1 Growing phase Ave. daily gain, kg L Ave. daily feed, kg L Feed conversion L Finishing phase Ave. daily gain, kg NS Ave. daily feed, kg NS 2 Feed conversion NS 1 Treatment effect significant P < Linear effect significant, P < 0.10 Table 6. Effect of dehulled canola meal on the average daily gain, average daily feed and feed conversion of pigs during the growing phase - Expt. 1. Percent Dehulled Canola Meal S.E.M. Significant Item Effect 1 Initial wt. Kg Ave. daily gain, kg - day 0 to L - day 8 to L -day 15 to L - day 22 to L - day 0 to L Ave. daily feed, kg - day 0 to L - day 8 to L - day 15 to NS 2 - day 22 to L - day 0 to L Feed conversion - day 0 to L - day 8 to L - day 15 to L Prairie Swine Centre Inc., Saskatoon, Canada. Monograph No

11 - day 22 to L - day 0 to L 1 Treatment effect significant P < 0.05 Prairie Swine Centre Inc., Saskatoon, Canada. Monograph No

12 Table 7. Effect of dehulled canola meal on the average daily gain, average daily feed and feed conversion of pigs during the finishing phase - Expt. 1. Percent Dehulled Canola Meal Significant. Item S.E.M. Effect 1 Initial wt. kg Ave. daily gain, kg - day 0 to L - day 8 to NS - day 15 to NS - day 22 to NS - day 0 to NS Ave. daily feed, kg - day 0 to L - day 8 to NS - day 15 to NS - day 22 to NS - day 0 to NS 2 Feed conversion - day 0 to NS 2 - day 8 to NS - day 15 to NS - day 22 to NS - day 0 to NS 1 Treatment effect significant P < Linear effect singificant, P < 0.10 Prairie Swine Centre Inc., Saskatoon, Canada. Monograph No

13 Table 8. Effect of dehulled canola meal on the average daily gain, average daily feed and feed conversion of pigs during the growing and finishing phases - Expt. 2. Treatment 1 S.E.M. Significant Item Effect 2 Growing phase Initial wt., kg Final wt., kg Ave. daily gain, kg NS 3 Ave. daily feed, kg NS Feed conversion NS Finishing phase Initial wt., kg Final wt., kg Ave. daily gain, kg NS Ave. daily feed, kg NS Feed conversion NS 1 Treatment 1:control diet based on soybean meal; treatment 2: negative control based on standard canola meal replacing 95% (growing trial) or 50% (finishing trial) of soybean meal; treatment 3: dehulled canola meal at 15% (growing trial) or 10% (finishing trial) of the total diet; treatment 4: the same as treatment 3 except energy and amino acids were elevated relative to treatments Treatment effect significant, P < Treatment effect significant, P < 0.10 Prairie Swine Centre Inc., Saskatoon, Canada. Monograph No

14 Table 9. Effect of dehulled canola meal on the carcass traits of finishing pigs - Expt. 2. Treatment 1 S.E.M. Significant Item Effect 2 Market wt., kg Dressed wt., kg Lean, mm NS Fat, mm NS Yield, % NS Index NS 1 Refer to Table 8 for description of treatments. 2 Treatment effect significant, P < 0.05 Table 10. Phytate, sinapine and glucosinolate content of canola meal and meal fractions with various fiber contents (POS pilot) Fraction Yield, % Phytate, % Sinapine, % Glucosinolate Canola meal Fibre reduced material Fibre enriched material Data provided by Dr. S. McCurdy, POS Pilot Plant Prairie Swine Centre Inc., Saskatoon, Canada. Monograph No