Utilization of oil in seed meals determined with chickens at different ages.

Abstract

UTILIZATION OF OIL IN SEED MEALS DETERMINED WITH CHICKENS AT DIFFERENT AGES S. Askbrant and D.J. Farrell** Fat digestibity and metabolizable energy (ME) of 9 diets were determined with chickens at 6 different ages ranging from 1 to > 16 w88kS. To a basal diet (602) was added 40% (1) full-fat rice bran (2) full-fat sunflower seed (3) full-fat rapeseed (4) full-fat soybean or (5) extruded soybean. The other 3 diets contained the basal diet and each of the seed meals with oil returned to equal the full-fat product. There was no difference in the ME of birds on the same diet within the age groups 1-3 weeks, 5-7 weeks and > 16 weeks. Apparent digestibility (%) of fat increased at the three different ages; values were a2.7r 85.2 and 88.3; mean values for the rice bran-based diet were 61.0, 73.5 and 85.6 respectively. For the full-fat rapeseed, sunflower and soybean-based diets mean digestibility (%) of the oil was 78.0, 93.0 and 79.0; when the oil was returned to the meals corresponding values were 91.2, 91.2 and 90.5. Mean ME increased with age of bird from 14.25 to 14.69 MJ/kg DM. Differences between the mature birds and groups of younger birds were different (P<0.05). ME of full-fat and extruded soybeans was 14.58 and 15.41 MJ/kg DM; values for full-fat rap8S8ed were 19.50 and 19.01 with the oil added back. Corresponding values for soybean were 14.58 and 15.98. INTRODUCTION There is evidence to suggest that young chickens do not metabolize dietary energy to the same extent as adult birds (Mollah et al. 1983). As the young chick ages it appears to improve its ability to digest oils and fats (Duckworth et al. 1950; Fedde et al. 1960; Annison 1974; Hakansson 1974) particularly the lipid in some vegetable by-products (Warren et al. 1985). Furthermore when oil is extracted from an oil seed meal this oil may be better digested Wan when in the unextraoted meal, but this may also depend, in part, on age of bird. The aim of the present study was to determine 9 with birds of different ages, the metabolizable energy (ME) and fat digestibility of full-fat oil seed meals, rice bran and the seed meals when extracted and the oil returned. MATERIALS AND METHODS Diets Four hundred grams of either full-fat rapeseed meal, sunflower meal, soyabean meal s extruded soyabean meal or rice bran were added to 6OOg of basal diet (940 g milled sorghum, 6Og meat and bone meal plus minerals and vitamins). * I . ** Present address: Department of Animal Nutrition and Management, Swedish University of Agricultural Sciences, Uppsala, Sweden Department of Biochemistry, Microbiology and Nutrition, University of New England* Armidale, N.S.W. 2351 182 Each extracted meal plus the corresponding oil were also added to the basal diet in the same amount as in the unextracted meal. Sunflower seed hulls were also returned with the oil to the meal in the same amount (130 g/kg) as found in the extracted sunflower meal. Ingredients and chemical composition of diets are given in Table 1. TABLE 1 Ingredient and chemical composition of test diets. Animals Sixty, one-day-old broiler chiokens were reared in a battery brooder on a commercial broiler diet. At 7 days of age, 27 ghicks of similar bodyweight were randomly assigned to 9 oages in a room at 22 C and offered one of the 9 diets ad libitum for one week. Birds were then rerandomised to the 9 aages in a room at 25'C and each assigned to one of the 9 diets. Both experiments were . replicated. Eighteen broilers aged 49 days were allocated at random to individual cages in a room at 22'C and offered one of the 9 test diets for one week. They were then rerandomised and the experiment repeated. ' Eighteen mature crossbred cockerels (>16 weeks) were placed. in individual cages in a room at 22'C and offered one of the 9 diets for one week. They were then rerandomised and allocated to dietary treatments for one week. Thus the experimental design was 9 diets x 6 ages x 2 replicates. Experimental Procedure For the first three days birds were allowed to adjust to the experimental conditions. On day 4 feed was removed for 3 h and plastic sheets were placed under the cages designed for excreta collection. During the last 4 .-days feed intake and fee'd*`spillage were measured and excreta collected daily. At the end of day 7 feeders were removed and 3 h later excreta collected. 183 . Chemical and statistica analvsis Exoreta were dried at 70�C to cmnstant weight, then f'itlaly mi.thd. Dr*y matter, ether extraot and gross energy wore measured on reyre~ant~Uv@ z~n(Ua~ of feed and excreta according to standard prooedurss ( AOAC 1980) Nitrogen was measured on the feed samples (Ivan et al. 19711). l Data were analysed using an analysis of variance and differences between means were tested using the Studentized Range. Missing data were estimated according to Steel and Torrie (1960). The chemical composition of the 9 diets is given in Table 1. The oil content (%) of the raw ingredients on a DM basis was: rapeseed 43.0, rapeseed meal 2.1; sunflower seed 43.9; sunflower meal 0.9; soybean seed 23.0; soybean meal 1.0; extruded soybean 21.2 and rice bran 23.4. One adult cockerel (>16 weeks) did not consume sufficient feed and excreta from a bird aged 7 weeks , on diet 3, were not collected completely. These data were not used. Analysis of variance showed that there was no difference (P<O.O5) between measurements of birds on the same diets within each of the three age groups (1-3 weeks, 5-7 weeks, >16 weeks). The data were therefore analysed according to these three age groups with four replicates per diet. The apparent digestibility of oil in the 9 diets at three ages is shown in Table 2. As birds aged there was a significant (P<O.Ol) increase in the apparent digestibility of dietary oil. Respective values (%I were 82.7, 85.2 and 88.3. TABLE 2: The apparent digestibility of oil (%) and the metabolizable energy (MJ/kg) of experimental diets at three different ages. 184 The lowest mean digestibility (%I was for diet 2 (73.5) containing rice the highest diet 6 (93.0) containing full-fat sunflower seed meal. A comparison of diets with the full-fat meal and the oorresponding meal plus returned oil was: for rapcsssod (78.0 VY. 91.2); sunFlowN* (oj.0 ~8. 91 .%) ; soybean (79.0 vs. 90.5) and extruded soybean (89.5). brant and Metabolizable energy of the 9 diets aged mean ME increased with age from between the mature birds and the two but not between the two former groups. rice bran based diet (21, and highest meal (15.61 MJ/kg). This was followed values, Table 3 is also shown in Table 2. As birds* 14.25 to 14.69 MJ/kg. Differences younger groups were significant (P<O.Ol), The lowest ME was 12.23 MJ/kg for the on diet 3 containing full-fat rapeseed by diets 6, 7 and 8 which had similar Mean metabolizable energy (DM basis) of full-fat ingredient and the oil-extracted ingredient with oil returned. Contribution of the basal diet ME(MJ/kg) was 8.23, 8.30 and 8.28 at the three-different ages. The mean ME of the ingredients are given in Table 3. Extruded and full-fat soybean values were 14.58 and 15.41 MJ/kg respectively, despite the fact that the former had almost 2% less oil. There was a major difference between the ME of full-fat soybean and of soybean meal plus oil. The latter was 1.4 MJ/kg DM higher than the former. DISCUSSION (1974) and in general animal nutrition by Wiseman (1984aL There is The digestibility of fats and oils in poultry was reviewed by Annison substantial evidence to suggest that as birds increase in age their ability to digest lipid improves (Hartel 19861, particularly of animal fats (Fedde et al. 1960; Hakansson 1974; Wiseman 1984bL This was confirmed in the present study although the amount of oil in the diets was generally high (Table 1). As would be expected there was a corresponding increase in ME with level of dietary lipid, and generally within a diet ME increased with increasing lipid digestibility. There was however substantial variation between replicates particularly in fat digestibility indicating within bird variation. There is very little information on the digestibility of oil in full-fat oil seed meals with the exception of soybean meal. Such seed meals may increase this variation among birds in oil digestibility. 185 Diet 2, containing 40% rice bran, gave the lowest ME and fat digestibility in the young birds. These values increased in the adult cockerels. Warren et al. (1985) made similar observations and reported apparent digestibility values for rice bran oil of 37% for chicks (lo-14d) and 93% for adult cockerels. Corresponding ME values (MJ kg DM) were 10.2 and 14.84; these may be compared with 10.07 and 12.85 found here. The lower ME value found here for cockerels is supported by a lower lipid digestibility of 90.5% but this may also indicate an interaction between rice bran and the basal diet. Warren et al. (1989 diluted a complete broiler diet with rice bran, while here the basal diet was 94% milled sorghum plus meat and bone meal. Rapeseed and soybean contain growth inhibitors. Some of these are destroyed on heating and may account for the higher digestibility of the oils when returned to the meals which are heated during oil extraction. Furthermore this depression in digestibility was not found for extruded soybean which is not oil-extracted but is subjected to high temperature in this process. Finally lipid release during chemical extraction may be more difficult in the full-fat meals compared to when the return of free oil to the meals is undertaken. The amounts of oil in the diets (Table 1) are generally higher than those used in practice. It is known that at increasing levels, particularly of added fat, the ME value of the fat declines (Wiseman 1984b). It may not be meaningful therefore to calculate the ME of the individual oils for comparative purposes (Table 3) although values are within the expected range. These results are preliminary in nature but they do highlight the complexity of the evaluation of oils and fats in poultry nutrition; in particular, source of oil, its form and the age of birds are important. The future of the oil seed meal industry is uncertain but there is clearly the need to evaluate further those meals which may be available to the animal industry in the future and contain considerable amounts of residual oil depending on economic circumstances. ACKNOWLEDGEMENTS We thank Contentinal Grain (Australia) Pty. Ltd.* Moree, for a gift of the oilseeds, meals and oil. REFERENCES A.O.A.C. (1980) Methods of Analysis', 7th ed. Association of Official Analytical Chemists Washington D.C. ANNISON, E.F. (1974). In 'Energy Requirements of Poultry', p. 135, editors T.R. Morris and B.M. Freeman (British Poultry Science: Edinburgh). DUCKWORTH, J.t Naftalin, J.M. and DalgarnO, A.C. (1950). J. Agric. Sci, (Camb). 40: 39. FEDDE, M.R. WAIBEL, R.E. and BLURGER, R.E. (1960). J, Nutr. 70: 447. HAKANSSON, J. (1974). Swedish J. Agric, Res. &: 33. HARTEL, H. (1986). Br. Poult. Sci. 27: 11. IVAN, M., CLACK, D.J. and WHITE, G.C.(1974) Lab. Pratt. 23:184. STEEL9 R.G.D. and TORRIE, JiH. (1960) 'Principles and Prohures of Statistics'. (McGraw-Hill: New York) WARREN9 B.M., HUME, I.D. and FARRELL, D.J. (1985). -Proc. 3rd A.A.A.P. Animal Science Congress, Seoul, Korea, p. 637. WISEMAN, J. (i984a). 'Fats in Animal Nutrition'. Butterworths, London. WISEMAN, J. (1984b). In 'Fats in Animal Nutrition', p. 277, editor J. Wiseman (Butterworths: London), 186