Agricultural and Food Science in Finland 513 A G R I C U L T U R A L A N D F O O D S C I E N C E I N F I N L A N D Vol. 7 (1998): 513–521. © Agricultural and Food Science in Finland Manuscript received August 1998 A G R I C U L T U R A L A N D F O O D S C I E N C E I N F I N L A N D Vol. 7 (1998): 513–521. Research Note Effects of restricted methionine and energy intake on egg weight and shell quality Tuomo Kiiskinen Agricultural Research Centre of Finland, Animal Production Research, FIN-31600 Jokioinen, Finland Eija Helander Suomen Rehu Oy, PO Box 105, FIN-00241 Helsinki, Finland An experiment involving two laying hen hybrids and four dietary treatments was conducted to study the effects of dietary methionine restriction (MR) (3,05 g/kg, MR 100; 2,65 g/kg, MR 87; 2,25 g/kg, MR 74) and energy restriction (ER) on egg production assessed as egg weight, egg weight classification and shell quality of eggs during the later laying phase from 46 to 70 wk of age. Daily methionine intakes were 305 (MR 100), 273 (MR 87), 229 (MR 74) and 326 (ER) mg per bird. ER was 89% of the calculat- ed supply of MR100. MR did not significantly affect hen-day production (%) but reduced linearly (P<0.001) egg weight. Average egg weights were 64.0 (MR 100), 63.1 (MR 87) and 60.6 g (MR 74). ER reduced egg weight to the same extent as MR 87 but its percentage laying was lower (P<0.05) than MR 87. Due to decreased egg weight feed conversion was considerably poorer for MR 74 than MR 100. Interactions between restriction and hybrid for egg production and feed intake, indicate differences in the requirements of methionine and energy between the two laying hybrids. Significant differences in shell quality were only observed between hybrids. However, the results concerning shell defects and shell quality parameters (shell strength, specific gravity) indicated an improvement for MR 74. In the classification of eggs MR increased linearly (P<0.001) the proportion of first class eggs, de- creased the proportion of large (63–73 g) and extra large (>73 g) eggs, but increased medium (53–63 g) and small (<53 g) sized eggs. ER did not significantly affect the proportion of eggs in the quality classification, but did significantly (P<0.05) reduce the proportion of extra large eggs. The results suggest that methionine restriction is an effective means for reducing egg weight which may also improve shell quality. Key words: diet, egg shell quality, egg weight Introduction There are at least two reasons for controlling egg size during the second half of the laying period. For one thing large eggs cause reduced prices and for another we can expect that shell quality improves when egg size decreases. It has been indicated that the quantity of shell deposited on the egg either remains constant or increases slightly as the hen ages, although relative shell weight decreases (Roland et al. 1975, 1978, Ro- 514 A G R I C U L T U R A L A N D F O O D S C I E N C E I N F I N L A N D Kiiskinen, T. & Helander, E. Effects of restricted methionine and energy intake on eggs land 1979). This means that shell quality declines with hen age due to a continued increase in egg size and the constant amount of shell being spread as a thinner egg layer. There are several nutritional factors which influence egg weight. Energy and protein restric- tion have been used for layers in order to avoid excessive intake which can lead to bird fatness and increased feeding costs. If the restriction has been severe enough, egg weight has decreased. Unfortunately the majority of the trials have started at the beginning of the laying period and there is a lack of information for production dur- ing the later laying phase. Auckland and Wilson (1975) found that energy restriction of about 92% from 56 to 68 weeks of age depressed the rate of lay by about 3 percentage units and egg weight by 1.1 g. An earlier start of the restriction (32 wk) resulted in a marked depression of laying. Kiiskinen (1974, 1977) restricted layers’ feed intake from 47–50 weeks of age for 5–6 months. A 92–98% restriction did not affect the rate of lay but did reduce egg weight by between 0.4 and 1.8 g. Methionine intake restriction has been stud- ied to control egg weight and to improve shell quality (Petersen et al. 1983, Jackson et al. 1987). A low daily methionine supply of 255–263 mg per bird did not markedly influence egg produc- tion (%) when birds were older than 38–43 weeks of age. Egg weight was reduced by between 1.5– 2.5 g and shell quality improved. The aim of the present study was to examine the effects of methionine and energy restriction on egg production, egg weight, weight classifi- cation and shell quality in particular during the later laying phase. Material and methods Birds and housing This study was conducted with 864 MÄ16 (Mäkelä) and 864 LSL (Lohmann White) hens and it started when the birds were 46 wk of age. Hens were kept in 2-tier batteries and housed three hens per cage (640 cm2/ hen). Tempera- ture of 18±2°C and 15 h of light per day were maintained. Water was provided ad libitum from nipple drinkers. Experimental design The experiment which included 6 four weeks periods (46 to 70 weeks), had a 2 x 4 factorial design consisting of two hybrids and four die- tary restrictions. Each dietary treatment group consisted of 24 replicates containing six adja- cent cages (18 birds). Dietary treatments were randomly allocated between 4 successive repli- cates including the same hybrid. Experimental diets and feeding Four dietary treatments were used: (1) methio- nine 100% (MR 100); (2) methionine 87% (MR 87); (3) methionine 74% (MR 74) and low ener- gy diet (ER). Composition of experimental di- ets is shown in Table 1. The cool pelleted diets were formulated from soybean meal and cere- als. Methionine restricted (MR) diets had a cal- culated metabolizable energy (AME) content of 10.7 MJ/ kg. AME content of the low energy (ER) diet was 9.8 MJ/ kg. The lower AME value of ER was achieved by omitting wheat and soy- bean oil. The ER diet was formulated to contain more protein, added minerals and vitamins than the other diets due to an intake restriction of around 115 g/ hen/ day compared to 120 g/ hen/ day for the methionine diets. Experimental procedures Eggs were collected and recorded daily for each replicate. Feed intake was measured on a repli- cate basis by weighing feed consumed during each 4 week period. Four replicates (2 MÄ16, 2 LSL) of hens fitted with a numbered foot ring 515 A G R I C U L T U R A L A N D F O O D S C I E N C E I N F I N L A N D Vol. 7 (1998): 513–521. per dietary treatment were weighed at the be- ginning and at the end of the trial. In the last weighing the condition of plumage in the neck, back, breast, wings and tail was also evaluated on a scale from 1 to 4 (1= bare or nearly bare, 4= good or complete plumage). Thirty two eggs per treatment in the sixth period were collected from the same replicates used for egg quality determinations (shell strength, specific gravity, albumen height, proportions of egg components: albumen, yolk, shell). Specific gravity was meas- ured by the Archimedes’ method and a Wazan compression force meter was used for the deter- mination of shell strength. Albumen height was evaluated by Ames HU micrometer (Haugh Unit). The number of broken, cracked and shel- less eggs for one day production were checked once per period during the last 5 periods. Egg quality and egg weight classification data was obtained from the egg packing company. Chemical analysis and statistics The proximate analysis was performed using standard procedures (AOAC 1984) for each batch of experimental diets. Measured crude pro- tein contents of the diets were about 5 g/kg low- er than calculated values (Table 1). Amino acids were hydrolysed (6N HCI, 110°C, 23 h) prior to analysis. Before hydrolysis methionine and cys- tine were oxidised using performic acid. Amino acids were analysed with a Beckman 6300 ami- no acid analyser. Determined methionine and lysine contents (Table 2) were lower than calculated values part- ly due to the lower protein content (Table 1). Calculating values based on a 89% dry matter content, methionine concentrations were 2.55 g/ kg (MR100), 2.27 g/ kg (MR87), 1.92 g/ kg (MR74) and 2.80 g/ kg (ER). Corresponding Table 1. Composition of experimental diets. Methionine Low energy diets diet (ER) MR100/MR87/MR74 Soybean meal g/kg 125 150.0 Barley " 360 475.0 Oats " 240 260.0 Wheat " 150 – Soybean oil " 20 – Limestone " 86 90.0 Dicalcium phosphate " 12 12.5 Sodium chloride " 3 3.2 Premixes1) " 4 4.3 DL-methi- onine " 0.8/0.4/– 0.9 Calculated Crude protein g/kg 142 150 Ca " 36.3 38.0 P available " 3.0 3.1 AME MJ/kg 10.7 9.8 Methionine g/kg 3.05/2.65/2.25 3.25 Lysine g/kg 6.50 7.50 Analysed content (on a 89% DM basis) Crude protein g/kg 137 144 Crude fat " 46 29 Crude fibre " 57 70 Ash " 92 92 1) Added vitamins, trace elements and carotinoid pigments MR100 = methionine 100%, MR87 = methionine 87%, MR74 = methionine 74% AME = apparent metabolizable energy, DM = dry matter Table 2. Dietary amino acid content (g/kg DM). Amino acid MR100 MR87 MR74 ER Methionine 2.86 2.55 2.16 3.15 Cystine 3.59 3.68 3.76 3.80 Lysine 6.22 6.50 6.39 7.77 Arginine 8.83 9.22 9.15 10.38 Isoleucine 5.42 5.66 5.55 6.22 Leucine 10.33 10.72 10.56 11.83 Threonine 5.08 5.24 5.17 5.90 Histidine 3.81 4.07 4.02 4.41 Phenylalanine 7.21 7.37 7.32 8.18 Tyrosine 4.98 5.15 5.20 5.84 Valine 7.03 7.24 7.08 7.92 MR100 = methionine 100%, MR87 = methionine 87%, MR74 = methionine 74% ER = energy restriction, DM = dry matter 516 A G R I C U L T U R A L A N D F O O D S C I E N C E I N F I N L A N D Kiiskinen, T. & Helander, E. Effects of restricted methionine and energy intake on eggs mean lysine contents of the MR diets was 5.67 g/ kg and that for the ER diet 6.92 g/ kg. Performance and egg quality data were sub- jected to the analysis of variance using the GLM procedure of SAS (SAS 1988). The model in- cluded the effects of restriction and breed and their interaction (Snedecor and Cochran 1989). Six cages of three hens (total 18 hens) formed an experimental unit. Residuals were checked for normality and plotted against fitted values by using the UNIVARIATE and PLOT procedures of SAS. Comparisons between treatment means were made using Tukey test. Frequencies of re- jected eggs (total) were analysed with the CAT- MOD procedure of SAS having effects of restric- tion and breed and their interaction in the mod- el. Treatments with methionine or energy restric- tion (MR 87, MR 74 or ER) were compared to the unrestricted treatment (MR 100) using the CONTRAST statement. Results and discussion Egg production and egg weight In general, hen-day production 77–80% was sim- ilar for each dietary treatment excluding LSL hens fed the ER diet (Table 3). Methionine re- striction did not significantly affect laying of either hybrid. Based on daily feed intake (Table 3) and measured methionine content (Table 2), daily methionine supplies per bird were 305 mg (MR 100), 273 mg (MR 87), 229 mg (MR 74) and 326 mg (ER). In the study of Petersen et al. (1983) methionine supply varied from 255 to 300 mg / hen / day and they did not observe signifi- cant differences in hen-day production between 38 and 102 weeks of age. Jackson et al. (1987) used dietary methionine contents of 0.233– 0.383%, which corresponded to a daily intake of 268–448 mg. These authors demonstrated a reduction of production at early ages (30 and 43 wk) but not later. It seems that a marked me- thionine restriction up to 230 mg / hen / day does not affect percentage laying if the restriction begins at the age of 45 weeks. This is consider- ably less than the NRC (1994) recommendation of 300 mg / hen / day, for optimal production (g / hen / day) and feed efficiency. ER reduced considerably laying of the LSL hens and a significant (P<0.05) interaction be- tween restriction and hybrid (R x H) was ob- served for hen-day production. Obviously LSL has a higher energy requirement than MÄ16 and therefore energy supply was insufficient for LSL fed diet ER. Metabolizable energy (ME) require- ments of a caged hen in this production phase is 1.20–1.25 MJ / day (Salo et al. 1982). Accord- ing to tables 1 and 3 calculated ME intake was 1.14 MJ / day among the ER hens and 1.28 MJ / day among the MR 100 hens. So the energy re- striction was 89%. In this trial MÄ16 produced more (P<0.05) eggs than LSL. In the earlier comparisons LSL has layed either higher (Kiiskinen and Huida 1990, Pärko and Stolt 1993, Suomen Siipikarja 1996) or equal number of eggs than MÄ16 (Kiiskinen 1996), dur- ing the entire production period. MR reduced linearly (P<0.001) egg weight. The average reduction was 0.9 and 3.4 g for MR87 and MR74, respectively. Petersen et al. (1983) reported a reduction of 1.6–2.3 g in egg weight, during a methionine restriction of 85%. In the study of Jackson et al. (1987) a maximum reduction of 4–4.5 g was obtained when methio- nine restriction was around 70%. Although ER in the present study was rather severe, its effect on egg weight was less marked than that of MR. On average ER reduced egg weight by 0.7 g. During this laying phase hybrids produced eggs of the same average weight. Feed intake and feed efficiency Hens consumed approximately all offered feed (Table 3). The MÄ16 hens, which were fed the MR74 diet, ate less (P<0.05) than comparable hybrids fed MR diets. Apparently the methio- nine content of MR74 was insufficient for MÄ16 and caused a reduction in feed intake. This im- plies a difference in methionine requirement 517 A G R I C U L T U R A L A N D F O O D S C I E N C E I N F I N L A N D Vol. 7 (1998): 513–521. between hybrids. The ER hens ate a little bit more than the restricted ration 115 g/day. This was possible if birds died during the period for which feed was weighed into the small contain- ers of the feed chain. As a result of decreased egg weight and production, MR74 had a higher feed conversion ratio (FCR) and this effect was significant (P<0.05) among MÄ16 hens. Also ER increased FCR of both hybrids, but differences compared with MR 100 were not significant. In this laying phase MÄ16 utilized feed more effi- ciently (P<0.001) than LSL. Mortality, body weight and plumage Mortality varied between 2.1 and 3.5% and was not greatly influenced by the choice of die- tary restriction. Corresponding restriction meth- ods have not been reported to increase mortality (Petersen et al. 1983, Jackson et al. 1987, Auck- land and Wilson 1975, Kiiskinen 1974, 1977). There were significant (P<0.01) differences in body weight between dietary treatments at the end of the trial (Table 4). MR decreased the fi- nal weight linearly (P<0.001) and also ER re- duced weight (P<0.05) compared to MR100. Only MR100 hens increased their weight during the trial. Also Petersen et al. (1983) noted a re- duced weight gain in methionine restricted hens. The MÄ16 hens were heavier (P<0.001) than LSL hens both at the beginning and at the end of the trial. This distinction has been also observed in the earlier reports (Kiiskinen and Huida 1990, Pärko and Stolt 1993, Suomen Siipikarja 1996). Reduction of body weight of LSL refers that the Table 3. Effect of dietary treatment and laying hen hybrid on egg production and feed intake. Egg Egg Egg Feed FCR laying weight prod. intake kg/kg % g g/h/d g/h/d MÄ16 MR100 80.0 64.2 51.4B 119.5B 2.33A MR87 79.0 63.4 50.0B 119.5B 2.40AB MR74 77.8 60.5 47.0A 117.5A 2.51B ER 78.2 63.2 49.4AB 116.2A 2.36A Mean 78.8 62.8 49.4 118.2 2.40 LSL MR100 77.1ab 63.8b 49.1b 119.7b 2.46ab MR87 79.5b 62.8b 49.8b 119.9b 2.42a MR74 77.8ab 60.7a 47.1ab 119.9b 2.57b ER 73.4a 63.3b 46.4a 116.4a 2.53ab Mean 76.9 62.7 48.1 119.0 2.49 SEM 1.04 0.23 0.61 0.34 0.034 Significance Restriction (R) ** *** *** *** *** Hybrid (H) * NS ** ** *** R x H * NS * ** NS MR linear NS *** *** – – A–B, a–b Means in the same column with a different superscript letter are significantly (P<0.05) different. Significances: NS = non-significant, * = P<0.05, ** = P<0.01, *** = P<0.001 MR100 = methionine 100%, MR87 = methionine 87%, MR74 = methionine 74%, ER = energy restriction SEM = standard error of mean R x H = interaction between restriction and hybrid FCR = feed conversion ratio 518 A G R I C U L T U R A L A N D F O O D S C I E N C E I N F I N L A N D Kiiskinen, T. & Helander, E. Effects of restricted methionine and energy intake on eggs daily allowance of feed was insufficient for this hen hybrid. Dietary restriction had no signifi- cant effect on feather cover (Table 4). Egg quality and egg components Eggs laid by the MR74 hens contained signifi- cantly (P<0.05) less shell defects than eggs of the MR100 hens (Table 5). Shell strength and specific gravity of MR74 and ER were non-sig- nificantly higher than MR100 (Table 6). Petersen et al. (1983) and Jackson et al. (1987) found for the greatest methionine restriction in partic- ular improved egg shell quality and their results support those of the present study. Shell and egg white quality (Haugh) of LSL eggs were signif- icantly (P<0.001) better than those of MÄ16 eggs. ER increased (P<0.05) the proportion of egg white and decreased that of yolk and shell. MR did not significantly affect the proportions of each egg component. Shafer et al. (1996) fed higher methionine levels and found that methio- nine intake did not influence the relative yield of albumen and yolk but did increase the crude protein content of these components. Eggs of L S L c o n t a i n e d m o r e e g g w h i t e , l e s s y o l k (P<0.05) and more shell (P<0.05) than eggs of MÄ16. These results concerning differences in the proportion of albumen and yolk between hybrids are consistent with earlier observations (Kiiskinen and Huida 1990). Quality and weight classifications of eggs M e t h i o n i n e r e s t r i c t i o n i n c r e a s e d l i n e a r l y (P<0.001) the proportion of first class eggs and Table 4. Effect of dietary treatment and laying hen hybrid on body weight and feather score. Body weight kg Feather 46 wk 70 wk score total Restriction (R) MR100 1.84 1.90c 12.1 MR87 1.84 1.84bc 11.7 MR74 1.82 1.74a 12.2 ER 1.84 1.77ab 13.1 SEM 0.015 0.022 1.38 Hybrid (H) MÄ16 1.88 1.90 12.2 LSL 1.78 1.72 12.3 SEM 0.011 0.016 0.98 Significance R NS *** NS H *** *** NS R x H NS NS NS MR linear NS *** NS a–c Means in the same column with a different superscript letter are significantly (P<0.05) different. Significances: NS = non-significant, 0 = P<0.1, ** = P<0.01, *** = P<0.001 MR100 = methionine 100%, MR87 = methionine 87%, MR74 = methionine 74%, ER = energy restriction SEM = standard error of mean R x H = interaction between restriction and hybrid FCR = feed conversion ratio Table 5. Effect of dietary treatment and laying hen hybrid on the incidence of egg shell defects. Restriction Hybrid MR100 MR87 MR74 ER MÄ16 LSL Broken % 5.1 5.7 3.7 4.4 4.7 4.8 Cracked " 7.4 8.6 5.9 6.9 7.6 6.8 Shelless " 2.8 2.5 1.1 2.3 2.9 1.4 Other " 0.03 1.3 0.7 2.0 0.4 1.6 Total1) " 15.4 18.2 11.5 15.5 15.7 14.6 1) MR74 differed significantly from MR100 (P<0.05). 519 A G R I C U L T U R A L A N D F O O D S C I E N C E I N F I N L A N D Vol. 7 (1998): 513–521. Table 7. Effect of dietary treatment on the classification and distribution of eggs to the different weight classes, measured by the egg packing company. 1st class 2nd class Unqua- Weight distribution of the 1st class eggs lified <53g 53–63g 63–73g >73g % % % Restriction (R) MR100 78.8a 17.1b 4.2b 0.1a 18.9a 69.6b 11.4c MR87 80.2a 16.0b 3.7ab 0.1a 24.7b 67.5b 7.7b MR74 82.9b 14.1a 3.0a 1.0b 44.9c 50.8a 3.3a ER 79.9a 16.3b 3.9b 0.2a 22.5ab 68.5b 8.8b SEM 0.56 0.42 0.20 0.05 0.93 0.60 0.49 Significance R *** *** *** *** *** *** *** MR linear *** *** *** *** *** *** *** a–c Means in the same column with a different superscript letter are significantly (P<0.05) different. Significances: NS = non-significant, *** = P<0.001 MR100 = methionine 100%, MR87 = methionine 87%, MR74 = methionine 74% SEM = standard error of mean Table 6. Effect of dietary treatment and laying hen hybrid on mean egg quality traits measured in the poultry house. Restriction (R) SEM Hybrid (H) SEM Significance MR100 MR87 MR74 ER MÄ16 LSL R H R x H Shell strength(N) 28.7 27.5 30.2 29.6 0.70 26.9 31.2 0.49 NS *** NS Spec. gravity .0814 .0818 .0821 .0832 .00067 .0790 .0853 .00047 NS *** NS Haugh 79.5 80.6 80.2 81.2 0.88 78.9 81.8 0.62 NS ** NS Egg components % white 60.6a 61.1ab 60.3a 61.9b 0.31 60.8 61.2 0.22 *** NS NS yolk 29.0 28.6 29.1 28.2 0.29 29.1 28.3 0.20 NS * NS shell 10.2 10.1 10.1 9.7 0.14 9.8 10.2 0.10 NS * NS a–b Means in the same row with a different superscript letter are significantly (P<0.05) different. Significances: NS = non-significant, * = P<0.05, ** = P<0.01, *** = P<0.001 MR100 = methionine 100%, MR87 = methionine 87%, MR74 = methionine 74%, ER = energy restriction SEM = standard error of mean R x H = interaction between restriction and hybrid FCR = feed conversion ratio N = newton decreased (P<0.001) that of second class and unqualified eggs (Table 7). Effects of energy restriction were not significant. MR decreased linearly (P<0.001) the proportion of large (63– 73 g) and extra large (>73 g) eggs and increased (P<0.001) those of medium (53–63 g) and small (<53 g) eggs (Table 7). ER reduced significant- ly (P<0.05) extra large eggs, but did not influ- ence the proportion of eggs classified in other weight classes. Using a maximum price of 1.40 Fmk per kilo feed and price differences in the quality and weight classes of eggs and account for the cost of methionine, restriction of this amino acid can 520 A G R I C U L T U R A L A N D F O O D S C I E N C E I N F I N L A N D Kiiskinen, T. & Helander, E. Effects of restricted methionine and energy intake on eggs produce a profit of around 10 pennies per kilo- gram of eggs. Conclusions Restriction of methionine intake (74%) during the later phase of the laying period proved to be an effective means to decrease egg weight. It did not affect laying intensity and appeared to im- prove egg shell quality. A relatively severe en- ergy restriction (89%) was not as effective in decreasing egg weight and seemed to reduce lay- ing percentage. Acknowledgements. This study was financially supported by Suomen Rehu Oy for which the authors present their warmest appreciation. References AOAC 1984. Official methods of analysis. 14th edition. Association of Official Analytical Chemist. Arlington, Virginia. 1141 p. Auckland, J.N. & Wilson, S.B. 1975. Effects of moderate energy restriction on light and medium hybrid laying hens. British Poultry Science 16: 23–29. Jackson, M.E., Hellwig, H.M. & Waldroup, P.W. 1987. Shell quality: potential for improvement by dietary means and relationship with egg size. Poultry Sci- ence 66: 1702–1713. Kiiskinen, T. 1974. Rajoitettu ruokinta muniville kanoille. Siipikarja 56: 170–175. – 1977. Rehun rajoitus munintakauden lopulla kannat- taisi meilläkin. Siipikarja 59: 7–8. – 1996. Tilasekoituksien vaikutukset munantuotantoon. Suomen Siipikarja 78: 24–26. – & Huida, L. 1990. Effects of two feeding regimens on production and egg quality of six laying hen hybrids. Annales Agriculturae Fenniae 29: 113–126. NRC 1994. Nutrient requirements of poultry. Ninth revised edition. National Research Council. Washington DC. 155 p. Petersen, C.F., Sauter, E.A., Steele, E.E. & Parkinson, J.F. 1983. Use of methionine intake restriction to im- prove egg shell quality by control of egg weight. Poul- try Science 62: 2044–2047. Pärkö, J. & Stolt, J. 1993. Humppilan kanatalousaseman tulokset 1992–1993. Siipikarja 75: 190–191, 193. Roland, D.A. Sr. 1979. Factors influencing shell quality of ageing hens. Poultry Science 58: 774–777. –, Sloan, D.R. & Harms, R.H. 1975. The ability of hens to maintain calcium deposition in the egg shell and egg yolk as the hen ages. Poultry Science 54: 1720– 1723. –, Putnam, C.E. & Hilburn, R.L. 1978. The influence of age on ability of hens to maintain egg shell calcifica- tion when stressed with inadequate dietary calcium. Poultry Science 57: 1616–1621. Salo, M-L., Tuori, M. & Kiiskinen, T. 1982. Rehutaulukot ja ruokintanormit. 70 p. Helsinki. SAS 1988. SAS/STAT User’s Guide (Version 6, 4th Ed.). SAS Institute Inc., Cary, NC. 1686 p. Shafer, D.J., Carey, J.B. & Prochaska, J.F. 1996. Effect of dietary methionine intake on egg component yield and composition. Poultry Science 75: 1080–1085. Snedecor, G.W. & Cochran, W.G. 1989. Statistical Meth- ods (8th Ed.), Iowa State University Press, Ames. 503 p. Suomen Siipikarja 1996. Humppilan koeasema. Hybridi- vertailukokeen tulokset 1995–1996. Nr 2 p. 9, 12– 13. 521 A G R I C U L T U R A L A N D F O O D S C I E N C E I N F I N L A N D Vol. 7 (1998): 513–521. SELOSTUS Metioniinin ja energian saannin rajoittamisen vaikutukset kananmunan painoon ja laatuun Tuomo Kiiskinen ja Eija Helander Maatalouden Tutkimuskeskus ja Suomen Rehu Oy Ylisuuret kananmunat alentavat tuottajahintaa. Me- tioniiniaminohapon ja energian saannin rajoittamisen vaikutusta selvitettiin munantuotannon, erityisesti munan painon ja kuoren laadun kannalta. Metionii- nipitoisuuden rajoitus rehussa oli 87 ja 74% vertai- lutasoon nähden. Rehua annettiin kaikille metionii- niryhmille enintään 120 g/kana/päivä. Energiarajoi- tuksessa rehun muuntokelpoisen energian pitoisuus oli 91.5% vertailuryhmän pitoisuudesta ja kun re- huannos rajoitettiin 115 g:aan päivässä, oli energia- rajoitus kokonaisuudessaan 89%. Koe suoritettiin ikä- välillä 46–70 vk ja siinä käytettiin kahta kanahybri- diä (MÄ16, LSL). Metioniinin rajoitus ei vaikuttanut merkitsevästi kanojen munintaan, mutta pienensi lineaarisesti mu- nan painoa. Munan keskipainot olivat 64.0 (100%), 63.1 (87%) ja 60.6 g (74%). Energiarajoitus alensi munan painoa yhtä tehokkaasti kuin 87%:n metionii- nirajoitus, mutta muninta jäi LSL-kanalla merkitse- västi heikommaksi. Voimakas munan painon lasku aiheutti 74%:n metioniinirajoituksella huomattavan rehuhyötysuhteen suurenemisen. Tulokset viittaavat metioniinin ja energian tarpeen eroihin hybridien vä- lillä. Kuoren laatua koskevissa tuloksissa oli havaitta- vissa sen parantumista runsaalla metioniinin ja ener- gian rajoittamisella. Munan laatuluokituksessa metio- niinirajoitus lisäsi merkitsevästi ykkösluokan munia ja vähensi suurten (63–73 g) ja ylisuurten (>73 g) munien osuutta. Energiarajoitus ei vaikuttanut mer- kitsevästi laatuluokitukseen, mutta vähensi merkitse- västi ylisuurten munien määrää. 522 A G R I C U L T U R A L A N D F O O D S C I E N C E I N F I N L A N D Kiiskinen, T. & Helander, E. Effects of restricted methionine and energy intake on eggs Title Introduction Material and methods Results and discussion Conclusions References SELOSTUS