Abstract:
HIGH-PROTEIN WHEATS IN POULTRY DIETS SURISDIARTO* and D.J. FARRELL* SUMMARY Experiments on high-protein wheats in poultry diets been carried out. Assays with broiler chicks indicated lysine was the only limiting amino acid for growth on diets on wheat containing crude protein (CP) greater than Threonine was fourid to be the second limiting amino acid growth after lysine in diets based on wheat containing CP than 16%. However, growth on the wheat-based diets did not that on the commercial, control diet. dietary-protein level and Experiments designed using wheat-based diets, have that based 16%. for less equal chicks for maximum growth level increased in the highlight the importance lysine) in broiler diets. to determine the interaction of lysine requirement of broiler chicks, showed that lysine requirement of increased linearly as the dietary CP range 12 to 26%. The results also of amino acid balance (relative to lysine and/or methionine In a layer experiment, supplementation to the basal diets based on 13.7, 16.2 and 16.5%. containing lysine and methionine at 90% of CP wheats (as fed) requirement did not generally elicit significant the layer responses either on hen-day (HD) egg production (81, egg weight egg mass I (g/b/d). Intakes of 396 and 825 mg/b/d of (g) or methionine and lysine respectively, were sufficient to maintain maximum laying performance. Layer diets, based on high-protein sources, wheats with very little contribution of other protein yield egg productions as efficient as on commercial laver crumbles. the lysine content (%I the protein level of cereals increases, resulting in a greater of this extra protein decreases, possibility of a lysine deficiency when high-protein wheats predominate in practical poultry diets. Biely (1969) I Turner (19701, Turner and Payne (1971) and Gardiner and Dubetz (1977) found that lysine was the first limiting amino acid in wheat protein for poultry and threonine was second limiting (Toep;fer et Gardiner and Dubetz (1977) found that Eli. 1972) 0 In contrast, zthionine in wheat protein was the second limiting amino acid Ivan and Farrell (1975) with rats, for poultry. In studies found that lysine was the only iinliting amino acid for rats in * Department of Biochemistry, Microbiology and Nutrition, University of New England, Armidale, NSW 2351 285 The use of high-protein wheat in poultry diets has been studied widely by many workers. Simmond (1962) reported that as diets based on wheat -containing 17% CP,C' Experimenting with laying hens, Turner (1970) concluded that high-protein wheat could be the sole protein.. source in laying diets when supplemented with lysine. The work of Turner and Payne (1971) confirmed that diets containing high-protein wheat (17.5% CP) supported egg-product ion equal to that on diets containing 10.7% CP. It was reported by Gardiner and Dubetz (1974) that diets containing a 19.7% CP wheat supplemented with lysine supported growth of broiler chicks as well as did traditional diets. Gardiner and Dubetz (1977) were in agreement with Turner (1970) in that high-protein wheats could be used as the sole protein source in laying diets when supplemented with lysine. Studies on the amino ,acid requirements of chicks have been made by many workers (Almquist 1947 ; Grau 1948 . Almquist 1952 ; Nelson et al. 1960 ; Klain et al. 1960 ; Dobkon et al 1964 ; Dean anrS<;tt 1965 ; GOUT and Morris 1985) ,Gra; (1948) and Almquist (1952) found that as the protein level of the diet increases, the lysine requirement for maximum growth at a particular protein level also increases when expressed as a percentage of the diet. Recent experiments conducted by Morris et al. (1987) concluded that the requirement of lysine by the chick is a simple linear function of the dietary protein content. The objectives of these current experiments were (i) to determine the sequence of amino acids limiting broiler growth, (ii) to study the influence of protein levels on lysine requirement of the chicks using wheat-based diets, and (iii) to examine the use of high-protein wheats in laying diets. MATERIALS AND METHODS Experiment 1: broiler qrowth on different wheat-based diet One hundred and twenty eight male, one-day-old broilers of a commercial strain were used in each of these experiments. The chicks were segregated on the basis of live weight into groups of eight chicks, and given one of four experimental diets, in four replicates. They were grown to 15 d in Experiments 1.1 and 1.2, and to 12 d in Experiments 1.3 and 1.4. The chicks were housed in electrically heated four-deck battery brooders with wire-mesh floors, and illumination was cant inous. Feed and water were supplied ad libitum. The chicks and uneaten feed were weighed at the end ofthe experiment. Four basal diets, formulated to be deficient in lysine, methionine and threonine, contained mainly four different wheats. All diets were of equal energy and CP and were fed in mash form. Composition of the basal diets and calculated amino acid contents are presented in Tables 1 and 2 respectively. Synthetic L-lysine (L) alone or plus DL-methionine (M) or plus DL-methionine and L-threonine (T) were added to the basal 286 diets to satisfy the chick's requirement ( Commercial broiler-starter crumbles obtained were used Agricultural Products, Tamworth, diet.It should be noted that NaCl was added to but not to diets 1.1 & 1.2 SCA 1987 1 m from Fielders as the control diets 1.3 & 1.4 Table 1, Composition (g/kg) of basal diets for Experiments 1.1 to 1.4. Table 2, Amino acids contents ((a; I on air-dry basis based on determined values for individual dietary ingredients) of basal diets for Experiments 1.1 to 1.4 and amino acid requirement of chicks O-4 weeks (SCA 1987). 287 The data obtained were subjected to analysis of variance using the NEVA program (Burr 1980) and Duncan's multiple-range test (Steel and Torrie 1960) was used to determine differences between means. Experiment 2 : effect of alterinq lysine and protein contents of broiler diets Experiments 2.1 and 2.2 were designed to measure chick growth rate and feed-conversion ratio on 20 diets containing 5 dietary lysine concentrations (g/kg CP) at each of 4 dietaryprotein levels, using wheat-based diets. one-day-old broilers of a Six hundred and forty male, commercial strain were used in each of the two experiments. The chicks were segregated on the basis of live weight into were fed ad libitum on dry-mash groups of 8 chicks, and --in four experimental diets with water cant in&&y available, replicates. Diets were introduced at one day of age and fed to 21 d. Chicks and uneaten feed were weighed at days 7 I 14 and 21. Data obtained at 21 d were subjected to analysis of variance 198C) and Duncan's multiple-range using the NEVA program (Burr test (Steel and Torrie 1960) was used to determine differences between means, diets varying in CP contents were In Experiment 2.1, obtained by formulating a summit diet (260 g CP/kg) and a basal diet (140 g W/kg). The range of protein levels tested was from in increments of 40 g W/kg. 260 g CP/kg down to 140 g CWkg, The summit diet was formulated by fixing the lysine content at 11.2 g/kg diet (43 g lysine/kg CP) and all other essential amino (SCA acids at not less than 1.4 times the chick's requirement 1987). The range of lysine contents was from 43 g/kg CP to 63 g/kg CP in increments of 5 g/kg CP. In Experiment 2.2, the summit diet was formulated to be 240 to give a range of g W/kg and the basal diet was 12G g CP/kg, protein levels from 240 g U/kg down to 120 g CP/kg with increments of 40 g CP/kg. The summit diet was formulated by fixing the lysine content at 11.3 g/kg diet (47 g lysine/kg CP) and all other essential amino acids at as close as possible to The range of (SCA 1987) requirement those of the chick's lysine contents was from 47 g/kg CP to 63 g/kg CP in increments of 4 g/kg CP. Glycine was incorporated in the summit diet to achieve N content equal to 240 g W/kg but all other essential amino acids remain as close as cossibie to these of the chick's requirement &CA 1987). l In both experiments, diets with were formulated by blending together in appropriate portions. All diets formulated to contain 13.0 MJ ME/kg. and basal diets of both experiments contents are presented in Table 3. intermediate protein levels the summit and basal diets in both experiments were Composition of the summit and calculated amino acid 288 Table 3, Composition (g/kg) of summit and basal diets and amino acids contents (% I on air-dry basis based on determined values for individual dietary ingredients) for Experiments 2.1 and 2.2. Experiment 3 : eqq production Two hundred and forty one-day-old single comb White Leghorn New Hampshire (SCWL x NH) and two hundred and forty Black X 289 (SIRO-CB) brown-egg layers I of the same ace kustralorp we 1-e reared in floor pens with electrically heated brooders:Co&;erciaI. starter crumbles obtained from Fielders Agricultural Products, . Tamworth, were offered ad libitum in galvanized-iron suspended feeders to six weeks ofage. Grower crumbles, from the same feedmill, were then provided ad libitum to eight weeks of qe, and then in restricted amounts to the onset of lay (18 weeks of age). Water was continously available. The chicks were vaccinated against Marek's disease and were beak-trimmed at the hatchery. At 18 heeks of age, the pullets were housed in single-bird cages in a naturally-ventilated, enclosed shed and had access to experimental diets in a feed trough common to five cages. Water was provided at all times and illumination was 16 h a day. Three basal diets, based on three different wheats (WL 13.7% CP ; WH 16.2% CP and WT 16,5% CP on air-drv basis) were formulated to be 13.0 MJ ME;ko and 16.5% CP b; fixing the lysine and methionine conteits at 90% of'the recomended requirement for layers &CA 1987). Composition of the basal diets and its calculated nutrient content are presented in Table 4. Shown in Table 5 are the amino acids contents based on determined values for individual dietary ingredients. Table 4, Composition (g/kg) of the basal diets for Experiment 3. 290 Table 5, Amino acid contents (% t on air-dry basis based on determined values for individual dietary ingredients) of basal diets for Experiment 3. Each of the basal diets was then divided into four fractions into which synthetic L-lysine or DL- methionine or a combination of both were added to cover 110% of requirement for both amirw acids to give a 2 x 3 x 2 x 2 factorial design ( 2 strains I 3 difierent wheats 2 levels; of lysine and 2 levels of methionine). Commercia; layer crumbles were used as the contml diet. Details of the test diets are given in Tabie 6. Table 6, Details of the treatment diets for Experiment 3. 291 Measurements cmmenced at 20 weeks and finished at 6C weeks of age. Feed consumption (g/d) I lysine and methionine intakes (mg/d) were calcuiated every four weeks. Hen-day egg producticn (%I was recorded for each one-week period. Egg mass (g/b/d) was measured weekly from a one-day collection. Egg specific gravity was determined by flotation in saline solutions ascending from 1.060 to\ 1.090 speci.fic gravity in increments of 0.005 Woisey aDd Hamilton 1977) and wab observed e.very four weeks -from a three-day egg collection. The birds were weighed every eight weeks and mortality was recorded daily. The data obtained were subjected to analysis of variance using the NEVA program (Burr 1980) and Duncan's multiple-range test (Steel and Torrie 1960) was usGl to determiKe differences between means. RESULTS AND DISCUSSION Experiment 1 : broiler qrowth on different wheat-based diets Body weight gain (BWG,g/d) and feed-conversion ratio (FCR, feed/gain) .of Experiments 1.1 to 1.4 are presented in Table 7. Table 7, Mean + SD of weight gain (E;WG g/d> and FCR (feed/ gain)-of broilers grown from l'to 15 d in Experiments 1.1 and 1.2 I and from 1 to 12 d in Experiments 1.3 and 1.4 fed basal diet supplemented with L-lysine (L) I DL-methionine (K> I and L-threonine CT), 292 There were significant differences (P<O,Ol) in both BWG and FCR in all experiments. Only in Experiment 1.1 was there a response to an amino acid other than to lysine. In all cases supplementation did not increase growth or imprdve FCR to that on the commercial diets. In all experiments, lysine supplementation increased BWG sionificantly (P<@.@lL This indicates that lysine was the first limiting amino acid in the basal and. is in agreement with data of Turner and Payne (1971) and Gardiner and Dubetz Eiely (1969) t (1977) for poultry, and Ivan and Farrell (1975) for rats. Methionine suppiementation tc the basal diet, together with lysine, did not produce any significant difference either in BWG or FCR in all experiments, Threonine addition to the basal diet, together with lysine and methionine in Experiment 1.1, increased but did not improve FCR. In BWG significantly (P<O.Ol) I Experiments 1.2 I 1.3 and 1.4 neither methionine supplementation nor threonine addition to the basal diet together with lysine improved BWG and FCR. It can be concluded from these experiments that methionine was not the second limiting amino acid for growth after lysine in the test diets. Threonine may be the. second limiting amino acid after lysine in diets based on wheats containing less than 16% CP. Neither clethionine nor threonine was the second limiting amino acid for growth in diets base6 on wheats containing CP greater than 16%. Ivan and Farrell (1975) reported that lysine was the only 1iniitir.y amino acid in wheats for rats. In all of these contairiing CP greater than 17% experiments, the highest BWG and'the best FCR were achieved oz the commercial control diet. This was partly due to its form ; intake of crumbles is usually higher tixn that of mash. There is also reason to believe tLat Diets 1.1 & 1.2 keze suboptimal in KaCl. In Experinients 1.3 & 1.4 with added NaCl 2 3 small growth response on the basz, diets (Table 7) was obtained. In these latter experiments differences in gr-owtl? rate and FCR between the control and supplemented groups xere small although still significant (P<O.OSL It appears that there is not only a single aniino acid or a combination of essential amino acids in wheat protein limiting broiler growth, but other factors which these experiments failed to identify. Experiment 2 : effect of alterinq lysine and protein contents of broiler diets Mean + SD of BWG (g/d> and FCR (feed/gain) of broilers in and 9 Experiments 2.1 and 2.2 are presented in Tables 8 respectively. In both experiments BWG increased and FCR improved significantly (P<O.Ol) as protein levels increased. In Experiment lysine supplementation irrespective of protein level 2.1 gene;ally increased BWG and improved FCR significantly (P<O.Ol). In Experiment 2.2 I however I the pattern of response to dietary lysine on each dietary-protein level both in BlnJG and FCR was not consistent. On diets containing 12% CP I lysine supplementation 293 did not increase FVX i but improved FCR significantly (P<O.O1). On diets containing 16 I 20 and 24% CP I lysine supplementation generally did not consistently increase BKG nor irr,prove FCR significantly (P>O.C5). Lysine supplementation of the diet to give lysine concentration above 58 g/kg CP in Experiment 2.1 tended to depress BWC and above 51 g/kg CP in Experiment 2.2 generally did not pxodu:e significant differences in either BWG or FCR. Table 8, Mean + SD of BWG (g/d) ar,d FCR (feed/c&n) of broilers in Experiment 2.1 (0 - 21 d>. Table 9. Mean + SD of BWG (g/d) and FCR (feed/gain) of broilers in Experinlent 2.2 (0 - 21 61). 294 at each dietary protein level, growth In both experinients, reached a plateau at a lysine level where all other essential amino acids were balanced relative to lysine, and this indicates the importance of amino acid balance in diets. In Experiment 2.1, as lysine concentration increased from 43 to 58 g/kg CP I the amino acids relative to lysine came into balance. In Experiment 2.21 however, because all other amino acids in both the summit and basal diets were fixed at as close as possible to the amino acids relative acid balance required by the chicks, the amino to lysine tended to be increasingly out of balance as the lysine concentration in the diets increased from 51 to 63 g/kg CP. In Experiment 2.1 growth rates obviously reflected intake of lysine, and this finding is in agreement with that reported by Gous and Norris (1985). Our data FP- Experiment 2.2 suggest that amino acid imbalance is the major cause of the increased lysine requirement with increasing dietary protein content. It is almost impossible to formulate all amino acid requirements to be in 'ideal* balance. It was for this reason that the mzxinwn dietary crude protein was 24%.Even then it likely not all of the amino acids were in complete balance. In order to estimate the lysine dose-response giving miximum BWG or maximum efficiency of feed utilization, quadratic curves of BWG and FCR on lysine level (g/kg diet) of each dietary protein level (%> were fitted (Fig. l-4 1. Figure 1, Response of FCR to dietary-lysine concentration (g/kg 6iet) in Experiment 2.1. 295 Figure 2. Response of BWG to dietary-lysine concentration (g/kg diet) in Experiment 2.1 Figure 3, Response of FCR to dietary-lysine concentration (g/kg diet) in Experiment 2.2. 296 Figure 4. Response of BT;l'G tc, dietary-lysine concentration (g/kg diet) in Experiment 2.2. In Experiment 2.1 there were significant quahatic respcnscs in both EWG and FCR tc, increasing dietary lysine concqtratiori at with the exception of BKG at 26% each dietary protein level CP In Experiment 2.2, however, the pattern of response to was not di;tpr~o~ lysine concer-&rations, as already mentioned, con&Aent . When lysine requirement ( Y I g/kg diet 1 w a s the lysine required regressed against protein levels ( >( I % 1 I (gjkg diet) to maximize both BWG and FCR was linear to protein level of the diets (Fig. 5-6). The linear regression equations were : 297 Figure 5. The recgession of lysine required (VI for maxinxm FCR (.I and BWG b-1 on CP ievel (XI of the diet ill Expwiment 2.1 Figure 6, The regression of lysine Equired 03 for maxinxm FCR (.I and BWG b-1 on CP level (X) of the diet in Experlnent 2.2 298 The slopes of the lines in Experiment 2.1 (Fig.5) are 5 3 . 4 and 57 2 g lysim/kg CP for BWG and FCR respectively. Since the intercepts were not significantly different (P>@.Ol) from zero1 forcing the lines through the origin <Jives a slope of 57.5 and 57.6 g lysine/kg CP respectively for EWG and FCR. In Experiment 2 -2 (Fig.61 the slope of the lines are 60.0 and 56.7 g lysine/kg CP for BWG and FCR respectively. The intercepts were also not significantly different (P>@.Ol) from zero, forcing the i.Ines through the origin gives a slope of 57.8 g lysine/kg CP for BWG and 56,6 g lysine/kg CP for FCR. It can be concluded frorr:. this study that the lysine required for maximum BWG and the best FCR is 57.5 g lysine/kg CP. This finding is in agreement with that reported by Bdomgaardt and Baker (1973) and Morris (1989) I but higher than that reported by Morris et a1.(1987) these were 57 8 56 and 53 g lysine/kg CP respectiv??l.y. This discrepancy may be due to difference in actual protein cluality of the diets and possible to the strain of broiler used. Morris (1989) has examined the interaction of lysine and arginine on the linear relationship between lysine requirement and dietary protein content. There was no effect on high or low dietary arginine levels on the lysine/protein relationship. Morris (1989) showed also for methionine and tryptophan linear relationship similar to that found previously between dietary lysine and crude protein. In practical formulations, lysine requirement for chicks should be specified as a proportion of crude protein content rather *than as a proportion of the diet per se. From these ---studies lysine appears to be not more than 1.21% for each 20% of dietary crude protein at an ME of about 12.8 MJ/kg diet. Experiment 3: eqg production lysine and methionine strains, Main effects cf wheats, levels on intakes of layers and production performance are presented in Tables 10 and 11 respectively. In genera.1 the HD egg-production (%I on all diets was with the acceptably high throughout the experimental period, exception that there was a slight drop in egg production at 40 to 44 weeks of age (late Dec.-late Jan.), Feed intake was gradual.1.y increased from 20 to 32 weeks of age,and was relatively stable from 32 weeks of age to the end of the experiment, with a sljgbt reduction at 40 to 44 weeks of age.These results nay be due to the higher environmental temperature during that period which were 29.20.30.3oC for the maximum and 14.30~15,OoC for the minimum. Three birds died during the experiment. (P<O.O5) less feed than those on the other diets. The like11 Birds on the 13.7% U-wheat Giets consun:.ed significantly explanation for this finding is the higher (12.4 MJ ME/kg) 13.7% CP-wheat. As a determined ME content of diets based on result of differences in energy content of the diets and daily feed intake I all birds on all wheats-based diets had consumed an which is 1.46 MJ ME/b/d. Because all equal amount of energy, wheats-based diets, by calculation, had equal content of lysine and methionine, consequently birds on the 13.7% CP-wheat diets 299 also than consumed significantly (P<O.O5) less lvsine and A those on the other diets. methionine Table 10. Main effects of wheats I strains q lysine and methionine levels on intakes of layers from 20 to 60 weeks of age in Experiment 3. Differences in these amino acids intakes did not elicit any significant differences in either HD-egg production (%I, egg weight (g) or egg mass (g/b/d). This finding is probably due to the higher minimum lysine and methionine intakes (on the 13.7% U-wheat diets) which were 912 and 445 mg/b/d respectively than the recomended levels ( SCA 1987 1. Body weight gain was affected by wheats ; it decreased significantly (P<O.Ol) as wheat protein increased. The reason for this finding is unknown. Lysine or methionine alone or in combination generally did not yield significant differences in hen performance. Two possible explanations for this aret firstly, the average lysine and methionine intakes were 825 and 396 mg/b/d in diets containing both amino acids at 90% of the laying's requirement &CA 1987) I are sufficient to maintain maximum egg production. Turner (1970) found that lysine supplementation to the basal diet comprised mainly of wheats as the sole protein source, increased HD-egg production to a level similar to those on the control diets, which was 67.5%. Since their experiment was run over 12 weeks and the birds were 24 weeks cf age when the experiment commenced, the ED-egg production of 80% should be expected. It was reported further that egg weight increased significantly by lysine supplementation. Unfortunately, Turner (1970) did not calculate iMake of lysine, but since the lysine content of the 300 basal diets was 80% of the laying requirement, this level was probably low enough to obtain responses to lysine Supplementation. Secondly I these results indicate that highprotein wheats ..(16.2 and 16.5% CP) have similar protein quality to normal wheats (13.7%). Karunaa jeewa (1985) found that sprouted wheats also had a similar protein quality to normal wheats. Table 11, Main effects of wheats I strains I lysine (L) ' and methionine (M) levels on production performance from 20 to 60 weeks of age in Experiment 3. There was no significant difference in HD egg production (%I birds laid significantly SIRO-CB between strains. However, SIRO-CB (P<O.Ol) smaller eggs than SCWL x NH. As a result, birds also produced a significantly (P<O.Ol) lower egg mass.SIROCB birds consumed significantly (P<O.Ol) more feed and gained significantly (P<O.Ol) greater body weight than SCWL x NH. These findings are not surprising and are due to known strain differences in performance. Egg specific gravity (not presented in a tabular form) on diets declined from 1.0886 to 1.0755 as the birds aged but not affected by supplementation of lysine or methionine. is in agreement with that reported by Gardiner finding Dubetz (1977). all was This and There was also a significant interaction between strain x lysine on HD egg production and between strain x methionine on egg weight (Table 121 Lysine supplementation to the basal diets did not produce significant difference in HD egg production of l 301 SIRO-CB birds; In SCWL x NH birds, however HD egg production was increased significantly (P<O.O5) by lysine supp1ementation.A lysine requirement of more than 805 mg/d is needed. This is in agreement with a suggested intake of 833 mg/d for a 50-g egg mass/day. A similar response was observed ,in egg weight by methionine supplementation. The SCA (1987) recomendation for methionine-of 389 mg/d is in adequate for the SCWL x NH strain to maintain maxiinum egg weight over 40 weeks of lay. Uzu and Larbier (1985) found that crossbred (ISA brown) semi-heavy laying hens fed diets based on maize and soybean oilmeal yielded optimum laying rate and egg weight when daily lysine intake was 790 mg/b/d. Higher lysine intake had no additional effects. Table 12, Effect of interaction on HD egg production methionine (M) on egg lysine 8 methionine between strain x lysine (L) (%I and between strain x weight (9) and intake of (mg/b/d) and ME (MJ/b/d). It was assumed that birds would consume on average 110 therefore fixing lysine and g/b/d. This was an underestimate, methionine contents of the basal diets at 90% of requirement (SCA 1987) was probably too generous to get production responses to those amino acid supplementations. 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