Maataloustieteellinen Aikakauskirja Vol. 60: 673—683, 1988 Industrial amino acids in diets for piglets and growing pigs J. INBORR 1 and K. SUOMI 2 ' Finnish Sugar Co. Ltd., Finnfeeds Ltd., Forum House, Brighton Road, Redhill, Surrey RHI 6YS, England 2 Agricultural Research Centre, Swine Research Station, SF-05840 Hyvinkää, Finland Abstract. Two production trials with piglets and one with slaughter pigs were carried out in order to investigate the effects of reducing the protein content in the diets followed by an addition of industrial amino acids on performance and health status. In the first piglet trial the crude protein content of the control diet was decreased from 20 to 18.3 % and in the second from 18.3 to 16.7 %. In the trial with growing pigs, the protein content of the control diet was decreased from 17.0 to 15.5 %. Industrial L-lysine, DL-methionine and L-threonine were added to the low protein diets toget the same levels of these amino acids as in the control diets. Piglet performance was similar on all treatments indicating equal availability of added and protein-bound amino acids. Health status of piglets on the low protein diets was considerably improved, indicating less predisposition to post weaning diarrhoea. Pigs on the low protein amino acid fortified diet tended to gain weight faster (788 vs. 743 g/day; p<0.07) and had higher carcass quality than pigs on the control diet. Feed utilization was improved by 4 % on the low protein diet, although, the improvements were not signifi- cant. Index words; industrial amino acids, lysine, methionine, theorine, piglet, pig, performance, diarrhoea Introduction In Finland, as in many other countries, pro- tein is both quantatively and pricewise a limit- ing factor in pig feed manufacture. Finnish domestic production of protein raw materials (rape, peas, beans, meat and bone meal etc.) cannot meet the demand and, therefore, sub- stantial amounts of soybean (SBM) and fish meal have to be imported. The protein supply of growing pigs is a question concerning the content of amino 673 JOURNAL OF AGRICULTURAL SCIENCE IN FINLAND https://www.c-info.fi/en/info/?token=uMrsRk9821a3Yx1p.PnrEQr9-FANSE_-Dr2dmRQ.A53ve_yedDU0Z68Q3MpZIGBY3QdYAOlRSLTwukkJboSlbJHt9hJRgrW0rbKVNGyFS7zVI949MDxifFeQBSBIzY8aI4KYh5B3Sq1QesJ0E6kJpmUzWHpbhxHXtkvb9hpoudhv0KYEGRyeAwkWXKiiNzCCQQLb5fy0sCo7wNP8bFX35Ag2 acids in the diet. Appropriate amounts of es- sential amino acids have to be provided to achieve maximum protein utilization. Accord- ing to Fuller et al. (1979) are lysine, threo- nine and histidine the first limiting amino acids in barley for growing pigs. When feed- ing barley and SBM, the most limiting amino acids are lysine, methionine and threonine (Madsen et al. 1987). However, diets defi- cient in one or more amino acids can be sup- plemented with free or synthetic amino acids to achieve an optimum balance in the diets. The pig cannot use surplus amino acids for lean production. Any surplus of absorbed amino acids will be oxidized. The carbon skeletons of the amino acids are included in the energy yielding metabolic pathways, while nitrogen, after transamination and deamina- tion, is excreted from the body in the form of urea. To achieve maximum protein utili- zation, an “ideal protein’’, as described by Cole (1980), should be formed containing the exact amounts of essential amino acids to meet the requirements of the pig. The in- creased production and use of industrial ami- no acids makes this possible. However, there is not enough data regarding the amino acid requirements of growing pigs and bioavaila- bility of protein-bound amino acids to apply this concept to practical feed formulation of today. There is some inconsistency in the results reported from performance trials regarding the effect of adding industrial amino acids to diets for growing pigs (Eggum et al., 1985 a; 1985 b). Supplementation of low protein piglet feeds with industrial amino acids resulted in satisfactory performance and amino acid bal- ance equivalent to that of the corresponding high protein unsupplemented feeds (Rogerson and Campbell, 1982; Miller et al. 1986 b; Campbell, 1978). However, when the crude protein content of the feeds was gradually decreased, other amino acids than the added ones become limiting, resulting in poorer per- formance (Nielsen et al., 1984; Gunther and Kruse, 1986; Eggum et al., 1985 a and 1985 b). The protein content and quality of piglet feeds can influence the health status of young pigs. Miller et al. (1986 a) showed that some proteins, due to their antigenicity, can induce immunological reactions in the small intestine of newly weaned piglets causing morphologi- cal changes in the gut wall. This immune- mediated intestinal damage, referred to as the malabsorption syndrome, may predispose the pig to postweaning diarrhoea. By decreasing the protein content of creep and post wean- ing diets, the hypersensitivity response to the feeds can be reduced resulting in improved performance and health status (Bertschinger et al., 1986, Miller et al. 1986 b). Soybeans contain relatively large amounts of raffinose, which is poorly hydrolyzed and absorbed in the small intestine of pigs. Con- sequently, on SBM based diets, relatively large amounts of this sugar will arrive in the large intestine, where it may have a laxative effect (Katz et al. 1973). Furthermore, SBM has been shown to give similar effects regarding secretion/absorption balance in the small in- testine of piglets as E. coli (Nabuurs and Hoogendoorn, 1985). The factors involved are not clearly known. In conclusion, an im- proved health status of piglets following a reduced protein content of the feeds by reduc- ing the inclusion rate of SBM may be conse- quent to reducing the amount of harmful fac- tors in the feed rather than the protein con- tent per se. The purpose of the trials reported in this paper was to investigate the effects of adding industrial amino acids to piglet and pig feeds with reduced protein content on performance and health status. Materials and methods Animals and design Trial I. This trial was carried out at the Swine Research Station in Hyvinkää. A total of twenty-four new-born litters of L-, Y- and L*Y crossbred sows, comprising 7 or more piglets, were allotted to two treatments of 674 twelve replicates each. Litters from sisters or closely related sows were allocated to differ- ent treatments, and litters were from both gilts and multiparous sows. The piglets were accustomed to the ex- perimental diets from one week of age, and had free access to the diets from two weeks to the end of the trial at eight weeks of age. The feeds were offered in self-feeders. Water was provided through nipples and available continuously. The piglets were weaned at 5 weeks by removing the sow from the farrowing pen, in which piglets stayed until the end of the trial. Trial 2. In this trial, carried out at Munk- kila Experimental Station in Paimio, forty- eight crossbred (L*Y) piglets, weaned at an age of five weeks and averaging 14 kg in live weight, were allotted to two treatments of twenty-four animals, each group comprising 10 gilts and 14castrates. Piglets on each treat- ment were allocated to four replicates into pens with six piglets on a sex and live weight basis. There was one pen with gilts only, one with four gilts and two castrates and two pens with castrates only on each treatment. Dur- ing the three week experimental period, piglets were fed ad lib from self-feeders, having ac- cess to one feeder per pen. Water was provid- ed through nipples (one per pen) and availa- ble continuously. All piglets were penned in the same row of an automatically air-conditioned enclosed sec- tion with a row of pens on each side of the central passage. One third of the 1.6*2.4 m concrete floor of the pens was slatted. Pens were partitioned by a 60 cm high solid steel wall and an additional 30 cm steel-pipe con- struction. During the first week, temperature was 25°C and decreased 2°C weekly. Trial 3. The trial was carried out at Munk- kila Experimental Station in Paimio. Forty- eight crossbred (L*Y) young pigs, with an average live weight of 22.5 kg, were random- ly allotted to six replicates of two treatments on a sex and live weight basis. There were four pens with castrates only and two with gilts only on each treatment. The pigs were fed twice a day (0800 and 1500 hours) in a trough according to general feeding recommenda- tions based on energy requirements of grow- ing slaughter pigs (Salo et ai., 1982). Aver- age daily feed intake was 2.2 kg per pig. Daily feed allowances were corrected weekly accord- ing to average per live weights. Water was provided through nipples (one per pen) and available one hour after each feeding. The replicates were allotted to two similar, automatically air-conditioned enclosed depart- ments and penned in the same type of pens as in trial 2. The feeding troughs, facing the central passage, provided 30 cm space per pig. The experimental diets were fed from 30 kg LW to slaughter. Prior to the experimental period, all pigs were offered the same diet con- taining 17 % CP and 50 ppm carbadox (Meca- dox). Treatments All diets were formulated to meet the nutri- tional requirements of weaned piglets (trial 1 and 2) and growing pigs (trial 3). The piglet feeds were crumbled and the pig feed was pelleted. L-lysine was added as the mono- hydrochloride. L-threonine and DL-methio- nine were added in pure crystalline form. Trial I. The diets were formulated to con- tain different amounts of crude protein (CP) and the same amounts of lysine and threonine. Soybean meal (SBM) and fish meal were sub- stituted with barley to reduce CP content in diet 2. L-lysine and L-threonine were added to diet 2 and both diets were medicated with carbadox (Mecadox). The CP content of diet 1 and 2 was 20.0 and 18.3 %, respectively. The composition of the diets is shown in table 1. Trial 2. The diets were formulated to con- tain different amounts of crude protein with the same amounts of lysine, methionine and threonine. The CP content of the diets were 18.3 and 16.7 % for treatment 1 and 2, respec- tively. Different amounts of L-lysine was ad- ded to the diets. In addition, DL-methionine and L-threonine were added to diet 2, in which SBM was substituted with barley to reduce the 675 676 Table 1. Composition of the experimental diets, g/kg. Treatment Trial 1 Trial 2 Trial 3 12 12 12 Barley 400 457 707 760 Barley, heat-treated 402 454 Oats 50 50 Dehulled oats, steamed 300 300 370 370 Soybean meal (SBM) 140 88 156 100 SBM, extruded 100 45 Fish meal 70 60 60 60 20 20 Fat blend 5 5 7 7 Skim milk powder 25 25 6 6 Whey powder 20 20 Glucose 35 35 20 20 Molasses (sugar beet) 15 15 Dicalcium phosphate 17 19 16 16 18 18 Calcium carbonate 3 3 6 6 6 6 Sodium chloride 1.5 1.5 2 2 Potassium lignosulph. 10 10 L-lysine HCI 1.8 2.0 3.3 1.3 2.6 DL-methionine 0.5 0.2 0.7 L-threonine 1.0 0.9 0.8 Premix* 4.0 4.0 4.0 4.0 1.7 1.7 Carbadox, ppm 50 50 50 50 Calculated values ME, MJ/kg 14.2 14.1 14.1 14.0 13.0 13.0 FU/kg 1.05 1.05 1.05 1.05 0.97 0.97 DCP, g/kg 180 160 160 145 150 130 Lysine, g/kg 11.5 11.5 11.7 11.7 9.8 9.8 Methionine, g/kg 4.3 4.3 4.0 4.0 3.2 3.2 Threonine, g/kg 8.0 8.0 7.2 7.2 6.1 6.1 * vitamins and trace elements according to requirements. CP content. The composition of the diets is shown in table 1. Trial 3. The diets were formulated to con- tain different amounts of crude protein with the same amounts of lysine, methionine and threonine. CP content of diet 1 and 2 was 17.0 and 15.5 %, respectively. In diet 2, SBM was substituted with barley to reduce the CP con- tent. L-lysine and DL-methionine were added to both diets and L-threonine only to diet 2. The composition of the diets is shown in ta- ble 1. Measurements Trial I. Piglets were individually weighed at birth, at weaning and at the end of the trial. Feed consumption, mortalities and the occur- ranee and severity of diarrhoea (scale of severity in table 4) were recorded. Scouring piglets were treated with antibiotics. Trial 2. The piglets were individually weighed at the beginning and at the end of the trial. The feeders were refilled once a day ac- cording to feed consumption and the amounts consumed were recorded. During the trial, the health status of the piglets was monitored and in case of diar- rhoea, affected piglets were treated with an antibiotic (Orimysin). Trial 3. All pigs were weighed at the begin- ning of the experiment and then at 14-day in- tervals up to an average LW of 70 kg. After that, pigs were weighed once a week and animals exceeding 102 kg LW were slaugh- tered the following day. Slaughter weights and 677 Table 2. Chemical composition of the experimental diets, g/kg. Treatment Trial 1 Trial 2 Trial 3 12 12 12 Dry matter 888 891 885 885 878 875 Crude protein 200 183 183 167 170 155 Ether extract 33 34 36 34 28 28 Crude fibre 37 34 37 30 43 41 Ash 62 54 47 43 43 53 N-free extracts 556 586 582 611 594 598 Calcium 11.6 10.3 8.8 8.5 9.6 9.1 Phosphorous 10.6 10.0 7.6 7.5 8.9 8.6 Lysine 10.7 10.8 11.8 10.9 Available lysine 10.0 10.1 11.3 10.5 Methionine 3.9 4.1 3.8 4.2 Cystine 3.6 3.6 5.0 4.9 Threonine 7.8 7.5 7.3 7.2 Tryptophan (cal.) 2.7 2.4 2.4 2.2 carcass quality were measured individually. Feed allowance of each replicate (pen) was weighed daily and recorded. In case of feed refusals or diarrhoea, daily feed allowances were temporarily decreased. The health sta- tus of the pigs was monitored during the ex- perimental period. Analytical methods All feeds were compounded at the Munk- kisaari feed mill in Helsinki. The dry matter, crude protein, crude fibre, crude fat (ether ex- tract), ash and sodium chloride contents of the feeds were determined in the feed mill labora- tory. Amino acid content of the feeds of trial 1 was determined at the National Laboratory of Agricultural Chemistry, whereas calcium, phosphorous of all feeds and the amino acid content of the feeds in trials 2 and 3 were ana- lysed at Viljavuuspalvelu. Proximate composition of the feeds was determined by standard methods. Amino acids were assayed at the National Laborato- ry of Agricultural Chemistry with an automat- ic amino acid analyser (Chromakon 400) fol- lowing hydrolysis and separation by ion- exchange chromatography, and available ly- sine was determined by difference following pre-treatment of the samples with fluorodin- itrobenzene (Pao et ai. 1963), whereas the methods described by AO AC (1984) were used at Viljavuuspalvelu. Tryptophan was not as- sayed. In a laboratory test, the pH of the diets in trial 2 was measured after mixing 20 g feed into 50 ml of a) distilled water (natural pH) and b) 0.2 M HCI solution (pH 1.70) at 40°C. A third diet (diet 3) was prepared by adding 1 % citric acid to diet 1. pH was measured at 5, 10, 20, 30, 40, 50 and 60 minutes after mix- ing. pH values were measured with a PHM 83 AUTOCAL meter. Statistical analysis Analysis of variance (one way classification) was used for the performance and feed intake measurements of trial 1. Results from trial 2 and 3 were calculated by using the RSI statisti- cal program (Digital Co.) and mean perfor- mance values were compared by unpaired Stu- dent’s T-test. Diarrhoea index values were compared by Chi2-test. Mortality values were compared by using F-test and unequal vari- ance t-test. Results and discussion The chemical composition of the feeds is shown in table 2. Exept for the crude protein, Table 3. Piglet performance during the experimental period, mean values. 1 2 � SEMTreatment Piglets 123 120 Live weight, kg/piglel at birth 1.59 1.58 NS NS NS 0.028 at 5 weeks of age at 8 weeks of age 9.54 9.61 0.186 19.06 19.34 0.350 Live weight gain, g/d/piglet from birth to 5 weeks from 5 to 8 weeks 227 230 NS NS 5.007 11.104451 464 from birth to 8 weeks Feed intake, kg/piglet from birth to 5 weeks from 5 to 8 weeks from birth to 8 weeks 312 317 0.32 0.49 NS NS 0.085 0.72815.50 15.88 15.82 16.37 Feed conversion, kg feed/kg gain from 5 to 8 weeks 1.64 1.66 NS • p<0.05, NS=non significant the corresponding feeds in each trial did not differ very much. Calcium and phosphorous levels were consistently somewhat higher in control diets (treatments 1). The higher inclu- sion rate of SBM may have increased the Ca and P content of these diets. Trial I Performance results are shown in table 3. There were no significant differences in per- formance between treatments. Piglets on treatment 2 had equal LW at 5 and 8 weeks, a slight non-significant higher DWG and equal feed intakes than piglets on treatment 1. Feed utilization was equal on both treatments. Thus, energy utilization (FU/kg gain) was not affected by the amino acid addition, in contrast with the results of Eggum et al. (1985 b). The availability of added industrial amino acids has been considered to be 100 % (Han- kahan, 1987; Madsen and Mortensen, 1977; Huisman et al., 1985). Results from several trials, however, imply lower values for added amino acids than for protein-bound ones (Eggum et al., 1985 a; Jorgensen and Fer- nandez, 1987). Increasing the frequency of feeding from one to two or more times per day improved availability of added amino acids (Batterham, 1974; Batterham and O’Neill, 1978; Partridge et al., 1985; Buraczewska and Buraczewski, 1980). Leibholz et al. (1986) reported equal absorption rates of added and extruded (L-lysine HCI + maize, 142°C) L-lysine in pigs. Krawielitzki et al. (1982) reported an absorption coefficient of approximately 94 °7o for orally administered ISN-Iysine and Huisman et al. (1985) 98— 99 % for MC-L-methionine. There are also results indicating that added lysine was more efficiently utilized by pigs than natural lysine (Fuller et al. 1986; Hankahan, 1987). The results from this trial indicate that the utilization of the added amino acids was equal to that of the protein-bound ones. In spite of a lower CP content, diet 2 provided sufficient amounts of essential amino acids and non-es- sential nitrogen to achieve equal performance to diet 1. According to the diarrhoea index and mor- tality percentage, the health status of piglets on treatment 2 was considerably better than of those on treatment 1. Two litters on treat- ment 1 and none on treatment 2 were medi- cated due to diarrhoea (table 4). Nielsen et al. (1984) and Eggum et al. (1985 a, b) also 678 4 Table 4. Health status of the piglets during the experimental period, mean values of litters. Treatment 1 2 significance Diarrhoea index A 321 148 ** Mortality, % from start to 5 weeks 2.44 0.83 NS from 5 to 8 weeks 3.33 * from start to 8 weeks 5.69 0.83 * Litters with no diarrhoea 7 6 Litters medicated due to diarrhoea 2 0 • p<0.05, •* pcO.OOI A scale of severity; 1 = normal faeces, 2 =soft faeces, 3 = fluid faeces, 4 =moderate diarrhoea, 5 =severe diarrhoea index =severity * number of affected pigs * days reported a decreased incidence of diarrhoea of piglets fed low protein, amino acid forti- fied diets. However, the reductions in CP con- tent were greater than in this trial. Reducing the SBM content in the feed per se may improve the health status of piglets, while it has been shown that SBM can give similar responses to E. Coli in the small in- testine regarding the secretion/absorption bal- ance (Nabuurs and Hoogendoorn, 1985). Furthermore, raffinose, which is abundant in SBM, is poorly hydrolyzed in the small intes- tine of the piglet. Consequently, on SBM based diets, substantial amounts of this laxa- tive trisaccharide (galactose + sucrose) will ar- rive in the large intestine causing looser stools (Katz et al. 1973) or fermentation diarrhoea in a similar way as when large amounts of su- crase are fed to young pigs (Just, 1983). The reduction in the incidence of diarrhoea may also be due to a reduced antigenicity of the diet (Miller et al., 1986 b and Bertschinger et al., 1986). Trial 2 There were no differences in performance between treatments during the 3 week period (table 5). Piglets on treatment 2 had slightly higher LW throughout the trial. Feed intake was the same on both treatments. Piglets on treatment 1 were treated on three occations and on treatment 2 on two occations due to diarrhoea. As in trial 1, the results indicate that despite a lower dietary protein concen- tration, diet 2 provided sufficient amounts of amino acids to achieve the same performance as diet 1. Moreover, the utilization of the ad- ded free amino acids seems to be equal to that of the protein-bound ones. The pH values of the diets measured dur- ing one hour are plotted in figure 1. The nat- ural (values at 0 minutes) pH of diet 1 was 0.17 Table 5. Performance and antibiotic treatments during the experimental period, mean values per piglet. Treatment 1 sd. 2 sd. * Piglets 24 24 Initial weight, kg Final weight, kg Weight gain, kg Daily weight gain, g Feed intake, kg 14.21 24.56 1.0 14.34 24.75 1.1 2.6 2.0 10.35 545 2.3 123 10.41 548 1.5 81 NS 20.3 0.4 20.3 0.4 Feed/gain, kg/kg 1.96 0.04 1.95 0.03 NS Antibiotic treatments, total number 3 2 * p< 0.05, NS =non significant 679 units higher than for diet 2. When 1 % citric acid was added to diet 1, the pH decreased by 0.67 units. Mixing the feeds into a 0.2 M HCI solution (pH 1.7) decreased pH of the feeds rapidly followed by a slow increase. After 20 minutes, pH values of the mixtures increased very slowly. The pH of diet 1 was highest and that of diet 3 lowest, diet 2 having intermedi- ate pH values. Prohaszka and Baron (1980) reported higher HCI-binding capacity of high protein diets compared with low protein ones. Gas- tric pH was higher in pigs receiving the high protein diets causing marked increases in the faecal E. Coli counts. The lower acid buffer- ing effect of diet 2 compared to diet 1 may be a consequence of the higher inclusion rate of monohydrochloride L-Iysine, but also due to a lower protein content. This might have a decreasing effect on the pH-level in the stomach of the piglet effectively preventing pathological bacteria from entering the small intestine and proliferate. Trial 3 Exess protein is catabolized and the nitro- gen is excreted in the urea. The formation of 1 mol urea requires 4 mol ATP and the syn- thesis of 1 mol ATP requires 85 kJ metaboliz- able energy. However, on experimental basis, Shiemann et al. (1971) and Just (1982) esti- mated the energy cost of urea synthesis and excretion to be much higher showing that pro- tein is a poor source of energy, and should not therefore be provided in surplus. Pigs on treatment 2 had 6 °Jo higher DWG and consumed 2 % less feed than pigs on treatment 1 (table 6). Consequently, feed utili- zation was improved on treatment 2. Howev- er, none of the performance parameters was significantly different between treatments (p>0.05), but there was a tendency (p<0.07) to higher DWG on treatment 2. Pigs on treat- ment 2 consumed 0.44 kg protein per kg gain resulting in a 12 % improvement in protein utilization compared to pigs on treatment 1. Fig. I. Changes in pH levels of the diets in trial 2 during 1 hour after mixing with a 0.2 M HCI solution. The values at 0 minutes represent the natural pH of the diets. 680 Table 6. Performance and carcass quality, mean values per pig. Treatment 1 sd. 2 sd. • Pigs 24 24 Initial weight, kg 30.8 2.0 30.8 1.8 NS Final weight, kg 104.4 4.0 105.8 2.8 NS Weight gain, kg 73.7 3.7 75.0 3.0 NS Feeding period, d 100 96 Daily weight gain, g 743 83 788 84 NS Feed intake, kg 216.9 212.6 Feed/gain, kg/kg 2.95 0.13 2.84 0.12 NS Protein, kg/gain, kg 0.50 0.44 Slaughter weight, kg 75.5 3.7 76.3 2.8 NS Killing-out percentage 72.3 2.0 72.1 1.9 NS Carcass quality, % of carcasses in; E+ 33.3 58.3 E 33.3 16.7 I 33,4 25.0 R * p<0.05, NS =non significant These results are in good agreement with the results reported by Nasi (1986) from a simi- larly designed trial in which the crude protein levels were 18 and 16.5 % up to 45 kg LW, and 16.5 and 15.0 % from 45 to 105 kg LW in the control and experimental diets, respec- tively. During the finishing period, pigs fed the amino acid fortified diets had significant- ly lower feed : gain ratios, which shows the energy sparing effect of feeding balanced pro- tein. Also carcass quality was improved on the low-protein diets. Pigs on barley-SBM based high protein diets had higher weight gains and lower food : gain ratios than pigs fed low protein, lysine supplemented diets (Fuller et al., 1986). The reductions in live weight gain and increases in food : gain ratio in response to reducing lysine concentration, however, were greater with soya meal than with free lysine. When feed- ing growing pigs withbarley-SBM based diets, containing equal (diet 1 and 2) or decreased amounts (20 and 40 % less in diets 3 and 4, respectively) of SBM and adding synthetic ly- sine and methionine to diet 2, 3 and 4, Mad- sen and Mortensen (1987) did not find any difference in performance of pigs up to 90 kg LW between treatments. Up to 50 kg LW, however, pigs on treatment 4 had significantly lower DWG than pigs on treatments 1 and 2. Diet 2 had higher lysine content than the oth- er diets, which were isolysinic. In the present trial, SBM content of diet 2 was reduced with 36 %. Equal performance of growing pigs has also been reported by Easter and Baker (1983), Russell et al. (1983) and Hanrahan (1987) when low protein diets were fortified with syn- thetic amino acids to achieve levels equivalent to those in the corresponding high protein control diets. Carcass quality was markedly better on treatment 2, resulting in 58.3 % of the car- casses beeing classified as E+ carcasses. On treatment 1, only 33.3 % of the carcasses were classified in the E+ category. Hanrahan (1987) reported less P2-backfat for pigs on ly- sine fortified diets than on isolysinic, SBM based diets. The reduction in backfat was not significant. According to Eggum et al. (1985 b), higher RPE (retained protein energy) values result in leaner pigs and higher DWG. Health status was good on both treatments. Feed was withdrawn ten times on treatment 1 and five times on treatment 2 due to diges- tive upsets and/or feed refusals. 681 References Aoac. 1984. Official methods of analysis. Ed. Associa- tion of Official Agricultural Chemists, Washington, D.C. Batterham, E.S. 1974. The effect of frequency of feed- ing on the utilization of free lysine by growing pigs. Br. J. Nutr. 31: 237—242. & O’Neill, G.H. 1978. The effect of frequency of feeding on the responseby growing pigs to supplements of free lysine. Br. J. Nutr., 39: 265—270. Bertschinoer, H.U., Eggenberger, E., Jucker, H. & Pfirter, H.P. 1979. Evaluation of low nutrient, high fibre diets for the prevention of porcine Escherichia coli enterotoxaemia. Veterinary microbiology 3, 281—290. Buraczewska, L., Lachowicz, J. & Buraczewski, S. 1980. 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Eds.), p. 131—134. Nielsen, H.E., Danielsen, V., Eggum, 8.0. & Chwall bog, A. 1984. Tilskud af aminosyrerne lysin, metionin og freonin til foderblandningermed lavt proteininhold til fravaennede grise. Statens Husdyrbrugsforsog, Med- delelse nr 545. Näsi, M. 1986. Puhtaitten aminohappojen käyttö siko- jen ja siipikarjan ruokinnassa. Maataloustieteen päivät. Suomen maataloustiet. seur. tiedote, No 7: 112—118. Pao, S.R., Carter, F.L. & Frampton, V.L. 1963. Anal. Chem. 35, 1927—1930. Partridge, 1.G., Low, A.G. & Keal, H.D. 1985. A note 682 on the effect of feeding frequency on nitrogen use in growing boars given diets with varying levels of free lysine. Anim. Prod. 40: 375—377. Prohaszka, L. & Baron, F. 1980, The predisposing role of high dietary protein supplies to enteropathogenicE. Coli infections of weaned pigs. Zbl. Vet. Med. B, 27, 222—232. Rogerson, J.C. & Campbell, R.G. 1982. The response of early-weaned piglets to various levels of lysine in diets of moderate energycontent. Anim. Prod. 35; 335—339. Russell,, L.E., Cromwell, G.L. & Stahly, T.S. 1983. Tryptophan, threonine, isoleucine and methionine sup- plementation of a 12 % protein, lysine supplemented, corn-soybean meal diet for growing pigs. J. Anim. Sci. 56, 1115—1123. Salo, M-L., Tuori, M. & Kiiskinen, T. 1982. Rehu- taulukot ja ruokintanormit. 70 p. Helsinki. Shiemann, R., Nehring, K., Hoffmann, L., Jentsch, W. & Chudy, A. 1971. Energetische Futterbewertung und Energienormen. VEB Deutscher Lantwirtschaftsverlag, Berlin. 344 pp. Ms received SELOSTUS Teollisesti luotetut aminohapot porsaiden ja sikojen rehuissa Inborr, J. 1 and Suomi, K. 2 1 Suomen Sokeri Oy, Finnfeeds Ltd Forum House, Brighton Road, Redhill, Surrey RH! 6YS, England 1 Maatalouden tutkimuskeskus, Sikatalouden tutkimusasema 05840 Hyvinkää Kolmessa tuotantokokeessa, kaksi pikkuporsailla ja yksi kasvavilla sioilla, tulkittiin rehun raakavalkuaista- son alentamisen vaikutusta kasvuun, rehun hyväksikäyt- töön ja ripulin esiintymiseen. Vähemmän valkuaista si- sältävien rehujen (koerehujen) lysiinin, metioniinin ja treoniinin määriä nostettiin samaan tasoon kuin kontrol- lirehun lisäämällä niitä puhtaina aminohappoina. Ensimmäisessä porsaskokeessa rehun valkuaistasoa alennettiin 20 %:sta 18,3 %:iin ja toisessa 18,3 °7o:sta 16,7 %:iin. Kasvavilla sioilla tehdyssä kokeessa rehun raaka- valkuaistasoa alennettiin 17,0 %;sta 15,5 %:iin. Teollis- ta L-lysiiniä, DL-metioniinia ja L-treoniinia lisättiin koe- teltuihin, jotta niiden määrä olisi sama kuin kontrolli- rehussa. Porsaiden kasvussa ja rehun hyväksikäytössä ei ryh- mien välillä ollut eroja. Tulokset viittaavat siihen, että lisättyjen aminohappojen ja rehuvalkuaisen aminohap- pojen käyttökelpoisuus oli yhtä hyvä. Vähemmän valku- aista sisältäviä rehuja saaneiden porsaiden terveydentila oli huomattavasti parempi kuin kontrolliryhmän (vähem- män vieroilusripulia), mikä viittaa siihen, että ripulialt- tius oli pienempi. Koeryhmän siat kasvoivat 6 % nopeammin (788 vs. 743 g/pv; pc 0,07) ja käyttivät rehua 4 % tehokkaammin hy- väkseen kuin kontrolliryhmän. Myös koeryhmän teuras- laatu oli parempi. Erot eivät olleet tilastollisesti merkit- seviä. 683