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Laying performance and nitrogen balance in hens fed organic diets with different energy and methionine levels

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Laying performance and nitrogen balance in hens fed organic diets with different energy and methionine levels
  Laying performance and nitrogen balance in hens fed organic diets with different energy and methionine levels *   J. Koreleski 1  and S. Ś wi ą tkiewicz  National Research Institute of Animal Production, Department of Animal Nutrition and Feed Science32-083 Balice, Poland  (Received 19 September 2008; revised version 3 November 2008; accepted 20 March 2009)ABSTRACT In a model experiment, 72 Bovans brown hens from 24 to 53 weeks of age were allocated to 4 groups with 18 replicates. Each hen (replicate) was kept in an individual cage. Layers were fed basal organic diets with lower or higher metabolizable energy (ME  N ) contents resulting from including 1% rape seed oil. The diets formulated according to organic limitations on feedstuff choices were either not supplemented or supplemented with 0.6 g·kg -1  DL-methionine (Met) to increase total dietary methionine and SAA levels to 2.94 g and 5.21 g·kg -1 , respectively. In the experiment, egg  production, feed intake, feed conversion, egg quality parameters and nitrogen (N) balance indices were determined. Met supplementation of the diet had a positive effect on laying rate, feed intake and feed conversion (P<0.001). Egg and yolk weight were also increased by Met, but yolk contribution in egg was not changed. The higher energy level decreased daily feed intake, but had no effect on other  performance parameters. The increased dietary energy level positively affected N retention measured as % of N intake (P<0.05). Adding Met increased daily N retention (P<0.05) and N retention as % of N intake (P<0.01) and decreased N content in excreta (P<0.05), but the differences in daily N excretion were not con fi rmed statistically. Nevertheless, it could be calculated for the whole experimental period (350 days) that feeding the higher energy- and methionine-supplemented diet decreased N excretion in manure by 56 and 63 g N per hen.KEY WORDS: laying hens, organic diet, methionine, energy, N-balance, performance  Journal of Animal and Feed Sciences, 18, 2009, 305–312 *  Supported by Statutory Activity, Project No. 4246.1 1  Corresponding author: e-mail:  306 ORGANIC DIETS WITH METIONINE – LAYING PERFORMANCE INTRODUCTIONThe proportion of methionine and sulphur-containing amino acids (SAA) to lysine in organic diets is generally lower as compared with conventional complete diets. Low methionine levels in organic diets can be prevented in part by the use of legume seeds, expellers and maize gluten (Zollitsch and Baumung, 2004) or by an increased level of dietary protein. Insuf  fi cient dietary methionine levels and amino acid imbalances in diets increase nitrogen excretion to the environment (Scholtyssek et al., 1991; Summers, 1993). Supplementation with limiting methionine improves laying performance in commercial practice of intensive feeding; response to added methionine is affected by the energy level in a diet (Harms et al., 1998). In organic production, DL-methionine is, however, not listed as an additive allowed in Europe, but its use is being discussed in the USA (Moritz et al., 2005). Despite the minor role of organic egg production in Europe (Windhorst, 2005), in order to protect the environment against a greater mass of manure resulting from lower digestibility and excess of nitrogen (N) in excreta, the possibility of supplementing methionine to organic diets should be discussed and considered.The effect of methionine supplementation on N excretion is not fully established in organic diets for egg production. The aim of the present work was to evaluate the effect of dietary energy and DL-methionine (Met) supplementation of organic diets for laying hens on laying performance, egg quality, N retention and N excretion in excreta.MATERIAL AND METHODSThe trial was conducted with 72 Bovans brown hens from 24 to 53 weeks of age allocated to 4 groups in 18 replicates. Each hen (replicate) was kept in an individual cage (40 × 40 cm) with a wire fl oor to afford possibilities for excreta collection. During the experiment, layers were provided with water and feed ad libitum , and were exposed to a 14 L:10 D lighting schedule with a light intensity of 10 lux.Hens were not pastured and the feed components used were admissible in organic production, but not certi fi ed. Hens were fed the basal organic diets (Table 1) with a lower or higher content of metabolizable energy (ME  N ) resulting from adding 1% rape seed oil. The nutrient contents of diets were formulated according to requirements for lying hens (Smulikowska and Rutkowski, 2005), but taking into account organic feeding limitations for feed choice. The basal diets contained a relatively low Met level (2.34g · kg -1 ) and were either not supplemented or supplemented with 0.6 g · kg -1  DL-Met (98%, Degussa) to increase total Met and SAA contents to 2.94 g and 5.21 g · kg -1 , respectively.   307KORELESKI J., Ś WI Ą TKIEWICZ S.The Local Krakow Ethic Committee for Experiments with Animals approved all experimental procedures relating to the use of live animals. During the experiment, the number and weight of eggs were registered daily, feed consumption was recorded monthly, and laying rate, daily egg mass, daily feed intake and feed conversion ratio per kg of eggs and per egg were calcula-ted.At 48 weeks of age, one egg from each hen (18 eggs from each treatment) was collected to determine egg quality indices, i.e. albumen height, Haugh Units, yolk colour, egg shell thickness and egg shell density. The eggs were analysed using semi-automated egg quality equipment (QCM+, Technical Services and Supplies (TSS), York, UK). The eggs were weighed, cracked, and albumen height was measured with an electronic gauge (QCH device, TSS, York, UK). The albumen height was converted to Haugh Units using the HU formula (Eisen et al., 1962) by Eggware software (TSS, York, UK). Yolk colour was measured using Table 1. Composition of basal diets, g · kg -1 ItemLower energy dietHigher energy diet Component  wheat (grinded)47.9045.90 barley (grinded)8.008.00soyabean seeds (heated)17.0017.50 pea seed (grinded)14.0014.50grass meal2.502.50rape seed oil -1.00limestone8.408.40dicalcium phosphate1.401.40 NaCl0.300.30vitamin-mineral premix 1 0.500.50  Nutrients content  metabolizable energy 2 , MJ 11.25 11.45 crude protein (analysis) 1658.332.344.613.500.35Lys (analysis)Met (analysis)Met + Cys (analysis)Ca 3 P available 31  contained no antioxidants and feed additives, supplied to 1 kg of diet, IU: vit. A 10 000; vit. D 3  3000; mg: K  3  2; B 1  1; B 2  4; B 6  1.5; B 12  0.01; Ca-pantotenate 8; niacine 25; folic acid 0.5; choline-Cl 250; Mn 100; Zn 50; Fe 50; Cu 8; J 0.8; Se 0.2 and Co 0.2 2  according to European Table of Energy Values for Poultry Feedstuffs (1989) as a sum of ME  N  content of feed components calculated on base of nutrients content 3  calculated from tables of feed composition  308 ORGANIC DIETS WITH METIONINE – LAYING PERFORMANCE an electronic colorimeter (QCC device, TSS, York, UK) and expressed in Roche scale points. Shell thickness was measured near the equator of the egg using an electronic micrometer (QCT device, TSS, York, UK). Egg shell density (dried shell weight per unit of shell area, mg/cm 2 ) was calculated by Eggware software (TSS, York, UK). A further 18 eggs from each treatment were collected for measurement of egg shell breaking strength, using an Instron Testing Machine, Model 5542 (Instron Ltd., High Wycombe, England), equipped with a 500 Newton load cell. The eggs were compressed at a constant crosshead speed of 10 mm/min, and breaking strength was determined at the moment of egg shell fracture.During 5 days at beginning of the 36th week of age, nitrogen balance was estimated. Feed consumed was measured and total collection of excreta from 5 replicates of each group was carried out. Excreta were weighted each day and stored at -20 o C. After thawing the excreta were weighted again, homogenized and representative samples for analysis of nitrogen and dry matter content were taken.  N contents in diets and in excreta were estimated by the Kjeldahl method (AOAC, 1990) using a Kjeltec Auto 1030, Tecator. N-balance indices were calculated tak-ing into account amounts of N ingested and N excreted. The amino acid content of diets was analysed in acid hydrolyzates in a colour reaction with the ninhydrin reagent, using a Beckman-System Gold 126 AA auto-matic analyser. Sulphur-containing amino acids were estimated after preoxidation to sulphone.Data were subjected to two-way factorial analysis of variance. The signi fi -cance of differences between means was determined by Duncan’s multiple range test and differences were considered signi fi cant at P ≤ 0.05. Statistical analyses were performed with Statistica 5.0 PL software (Statsoft Inc.).RESULTS During the entire experimental period no deaths were recorded among the hens. Laying performance was affected by the dietary Met level (Table 2). Met supplementation of the diet improved the laying rate, egg weight, daily mass of laid eggs, and feed conversion per egg and kg of eggs (P<0.001). Daily feed intake was altered both by dietary Met and energy level (P<0.05); supplementation of Met increased feed consumption, whereas the higher energy level decreased it. The energy content of the diet did not affect other performance  parameters. Among egg quality parameters (Table 3), only yolk mass was increased when hens were fed the Met-supplemented diet, but the relative yolk weight (in % of egg) was the same as in the unsupplemented diet. Egg shell characteristics   309KORELESKI J., Ś WI Ą TKIEWICZ S.were not changed when the methionine or energy content in the diet was in-creased.The positive effect of the higher dietary energy level and methionine supple-mentation on nitrogen balance (Table 4) was statistically con fi rmed in the case of N retention in % of N intake (P<0.05 and P<0.01). Moreover, supplementing the diet with Met increased daily N retention and decreased N content in excreta (P<0.05). In relation to daily N excretion the differences were not statistically con fi rmed (Table 4).DISCUSSIONIn the present experiment, the proportion of dietary Met to lysine (Lys) in the organic basal diet at both energy levels was 28.1. For that reason the diet could be classi fi ed as Met inadequate when compared the value of 43.6 recommended in intensive hen feeding (Smulikowska and Rutkowski, 2005) and the ideal ratio of to 47.0 on a true digestible basis for maximum egg mass (Bregendahl et al., 2008). Table 2. Effect of methionine addition and metabolizable energy level in the diet on performance indicesItemMetabo-lizable energy levelMethionine additionSEMEffect of -+meanenergymethio-nineinter-actionLaying rate, %Lower89.995.892.8 1.04NS***NSHigher86.994.690.8Mean88.495.2Egg weight, gLower54.859.657.2 0.638NS***NSHigher54.758.656.7Mean54.759.1Daily mass of eggs, g per henLower49.257.053.1 1.14NS***NSHigher47.655.551.5Mean48.456.3Daily feed intake, g  per henLower 121 123 122 0.336**NSHigher 120 121 121Mean 121 122Feed, g per 1 eggLower 135 128 132 1.39NS***NSHigher 138 128 133Mean 137 128Feed, kg per 1 kg of  eggsLower 2.46 2.15 2.31 0.048NS***NSHigher 2.53 2.19 2.36Mean 2.50 2.17 NS–P>0.05, * - P ≤ 0.05, *** - P ≤ 0.001
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