Effect of macroalgae enriched with microelements on egg quality parameters and mineral content of eggs, eggshell, blood, feathers and droppings

This study presents results obtained from feeding experiment on laying hens, which were fed with the diet supplemented with two marine macroalgae: Enteromorpha prolifera and Cladophora sp., enriched with microelements [Cu(II), Zn(II), Co(II), Mn(II), Cr(III)]. The applicability of the preparation was tested on five experimental groups of laying hens and one control group. In the control group, microelements were supplemented in the inorganic form, whereas in experimental groups, Cu, Zn, Co, Mn and Cr were replaced by macroalgae enriched with a given microelement ion. During feeding experiment, weight of laying hens, weight of eggs, eggshell thickness and mineral content of blood, feathers, droppings, eggs content (separately yolk and egg white) and eggshell were measured. Also egg number was counted and microclimate (temperature and relative humidity) was monitored. Supplementing bio-metallic feed additives to the diet of laying hens resulted in higher microelement transfer to eggs and enhanced the colour of yolk. It was also found that the presence of Enteromorpha prolifera and Cladophora sp. in laying hens diet influenced advantageously eggs weight, eggshell thickness as well as body weight of hens. On the basis of these results, it could be concluded that Enteromorpha prolifera and Cladophora sp. enriched with microelement ions could be potentially used as mineral feed additives in laying hens feeding.     

Evaluating the nutritional value of date pits and demonstrating their application in laying hen diets

This experiment was carried out to study the feeding value of ground date pits (DP) (Phoenix dactylifera L.) with and without enzyme supplementation on laying hens’ performance. Apparent metabolizable energy value of DP was determined by the total collection method using 10 adult Leghorn cockerels. After that, a total number of 144 Lohmann 50‐week‐old LSL‐Lite hens were randomly allocated into six groups consisting of four replicates of six birds, based on a 3 × 2 factorial arrangement of the treatments. Six iso‐caloric and iso‐nitrogenous experimental diets including I‐corn–soya bean meal‐based control, II‐corn–soya bean meal oil‐based control and III‐ corn–soya bean meal‐based diet (180 g/kg DP) were formulated. Each of the diets was supplemented with two levels of an enzyme (0.0 and 0.07 g/kg Natozim Plus). The experiment lasted 10 weeks after 7 days of adaptation. The results revealed that there was no significant difference in feed intake, feed conversion ratio, egg production, egg mass, eggshell weight, eggshell thickness and Haugh unit among the treatments. Dietary inclusion of DP significantly decreased body weight gain (BWG), egg weight and yolk colour score. On the other hand, corn–soya bean meal‐based control diet with vegetable oil significantly increased egg weight and BWG of birds in comparison with other treatments. The serum biochemical metabolites were not affected by DP and enzyme supplementation. Thus, DP can be used as alternative feedstuff in laying hen diets, up to 18% of the diet with little effect on the performance of hens, including egg weight, and also, it had an adverse effect on yolk colour. Eventually, in terms of performance, the results failed to demonstrate any positive effect of Natozim Plus on either the controls or 18% DP diets.     

Effect of marine by‐product meals on hen egg production parameters,yolk lipid composition and sensory quality

The effect of including 5% marine by‐product meals in feeds of laying hens on egg production, composition and sensory characteristics was tested. Marine by‐product meals were prepared using two methods: (i) cooking (100°C/10 min) followed by drying (60°C/24 hr) or (ii) grinding followed by drying. The raw materials used for meal production were scallop or squid viscera, shrimp heads or whole mackerel. A total of 108 laying hens were allocated to nine diet treatments; one control diet (corn and soya bean based) and eight experimental diets, containing 95% of the control feed and 5% of the experimental meal for three weeks. Daily intake was higher in hens fed the dried mackerel and cooked shrimp meals. All the experimental treatments showed significantly higher concentration of n‐3 HUFA in yolk reserves and phospholipids compared to the control (0.12–0.13 g per 100 g), especially those with scallop or squid prepared by both methods (0.53–0.95 g per 100 g). Scallop, squid and shrimp meal inclusion in the feed produced eggs with more astaxanthin (0.22 mg per 100 g) while this carotenoid was absent in the control and mackerel treatments. Visual evaluation of raw yolk colour increased with the inclusion of marine by‐product meals with higher values in hens fed shrimp heads (13), followed by scallop viscera (11), squid viscera (9), and with similar values for mackerel and control (4). The taste, aroma, texture and colour of cooked eggs from different treatments were not statically different when evaluated by a panel of 60 untrained people. These results suggest that meals from marine by‐products are a better alternative for improving egg yolk composition by increasing n‐3 HUFA when compared to fishmeal as they also increase astaxanthin and yolk pigmentation without affecting egg sensory characteristics.     

日粮中添加辣诺素对海兰褐蛋鸡产蛋性能和蛋品质的影响

本试验旨在研究日粮中添加辣诺素（辣木和诺丽果的提取物）对蛋鸡生产性能及蛋品质的影响。将产蛋高峰期（22周龄）的海兰褐商品蛋鸡540只随机分为6个处理,每个处理6个重复,每个重复15只鸡。负对照组（NC）饲喂基础日粮,正对照组（PC）饲喂添加50 mg/kg杆菌肽锌的基础日粮,4个试验组分别饲喂添加0.25、0.50、0.75和1.00 g/kg辣诺素（LNS）的基础日粮。试验期24周。结果显示：①日粮处理对蛋鸡试验前期和后期生产性能均无显著影响（P>0.05）,试验后期添加0.50和0.75 g/kg辣诺素有改善料蛋比的趋势（P=0.087）;日粮处理对试验前期和后期鸡蛋蛋形指数、蛋壳强度、蛋壳厚度、蛋黄重和哈氏单位均无显著影响（P>0.05）,但日粮中添加杆菌肽锌和辣诺素有提高蛋壳强度的趋势（P=0.062）,其中以添加0.75g/kg辣诺素组鸡蛋强度最高。②与正、负对照组相比,添加辣诺素显著增加了生蛋黄和熟蛋黄的罗氏蛋黄色比率（P<0.05）,显著降低了蛋黄胆固醇的含量（0.25 LNS组除外）（P<0.05）。③与负对照组相比,添加0.50 g/kg辣诺素显著提高了鸡蛋总黄酮、二十二碳六烯酸（DHA）、卵磷脂、亚麻酸和亚油酸含量（P<0.05）。综合以上试验结果,辣诺素作为饲料添加剂具有提高鸡蛋营养品质的功能,考虑到添加成本,产蛋鸡日粮中添加0.25~0.50 g/kg为宜。     

Rare earth element‐enriched yeast improved egg production and egg quality in laying hens in the late period of peak egg production

The objective of this study was to determine the effects of rare earth element‐enriched yeast (RY) on egg production, coefficient of total tract apparent digestibility (CTTAD), egg quality, excreta gas emission and excreta microbiota of laying hens. A total of 216 ISA brown laying hens of 52 weeks of age were used in a 5‐week feeding trial and data were collected every week. Birds were randomly allotted to three dietary treatments each with six replicates and 12 hens per replicate. Each cage (38 cm width × 50 cm length × 40 cm height) contained one hen. Treatments consisted of corn–soya bean meal‐based diet supplemented with 0, 500 or 1000 mg/kg of RY. From weeks 55 to 56, inclusion of RY linearly increased (p < 0.05) egg production. The CTTAD of nitrogen was increased (linear, p < 0.05) with increasing dietary level of RY. In week 55, yolk height and Haugh units were increased linearly (p < 0.05) with increasing dietary RY content. However, no significant effects were observed in terms of excreta emissions and excreta microbiota in laying hens. In conclusion, dietary supplementation with RY improved egg production and CTTAD of nitrogen and slightly improved egg quality in laying hens of the late period of peak egg production.     

乳酸锌对蛋鸡生产性能及蛋壳质量的影响

本试验旨在研究乳酸锌对蛋鸡生产性能及蛋壳质量的影响。试验采用单因子随机分组试验设计,选取1600只360日龄的罗曼粉壳蛋鸡,随机分到4个处理组,各处理组8个重复,每个重复50只鸡。基础饲粮采用为玉米－豆粕型粉状饲粮,处理1饲喂基础饲粮＋60mg／kg－水硫酸锌（以锌计）,处理2饲喂基础饲粮＋60mg／kg乳酸锌（以锌计）,处理3饲喂基础饲粮＋40mg／kg乳酸锌（以锌计）,处理4饲喂基础饲粮＋60mg／kg锌（－水硫酸锌和乳酸锌提供的锌各一半）。试验结果表明,在产蛋鸡饲粮中100％以乳酸锌替代硫酸锌（提供的锌含量为60mg／kg）,能显著降低平均破蛋率,提高平均蛋壳强度和平均蛋壳厚度（P〈0．05）,死亡率最低,对蛋鸡的平均产蛋率、平均蛋重、平均日采食量和平均料蛋比无显著影响（P〉0．05）。     

酶制剂、益生素对杂粕饲粮品质改善效果的研究

采用单因素完全随机设计,研究杂粕日粮中添加0.015%的酶制剂和0.15%的益生素与豆粕日粮饲喂蛋鸡的效果差异。结果表明,与豆粕相比,加酶或加益生素的杂粕日粮降低蛋鸡产蛋率、产蛋量、蛋重和蛋鸡采食量;通过添加益生素或酶制剂,杂粕日粮在饲料转化率上与豆粕日粮效果相当;与豆粕日粮相比,加酶或加益生素的杂粕日粮不影响蛋壳厚度和软破蛋率,也不影响能量和蛋白质代谢率,但显著降低排泄物中蛋白质含量。可见,一定程度上加酶或加益生素能可提高杂粕的利用率,但其实用效果与豆粕日粮还有一定差距。     

Safety of Improved Milbond-TX When Fed to Laying Hens at Higher-Than-Recommended Levels

A corn-soybean meal diet was supplemented with 0, 1, or 2% Improved Milbond-TX (IMTX, a hydrated sodium calcium aluminosilicate) for Hy-Line W-36 laying hens selected for good or poor eggshell quality. Supplementing the diet with IMTX had no detrimental effects on egg weight, eggshell weight, albumen quality, feed consumption, or feed conversion during 5 consecutive 28-d periods. Increase in BW over the 5-mo experimental period was not influenced by the addition of IMTX. Results from this study show that an accidental oversupplementation of a laying hen diet with up to 8 times the recommended level of IMTX of the manufacturer, which may occur due to a feed mill mixing error, should not result in adverse performance of laying hens nor should it affect the concentration of moisture in the excreta.     

Effect of dietary defatted diatom biomass on egg production and quality of laying hens

Background： This study was to determine if feeding laying hens with defatted diatom microalgal biomass （DFA） from biofuel production affected their egg production and health status. Methods： Five replicates of 5 individually caged ISA Babcock White leghorn hens were fed 4 diets, including a corn-soybean meal control diet, a diet containing 7.5% DFA substituting for soybean meal, and diets containing 7.5% or 15% DFA substituting for corn and soybean meal. Body weights, feed intake, feed conversion ratio （FCR）, rate of egg production, egg size, egg mass, and several characteristics of eggs were determined at 4 and 8 wk. Venous blood was sampled at 4 and 8 wk for measurement of 5 biomarkers of health. Results： The15% DFA diet decreased （P 〈 0.05） feed intake, egg production, and plasma uric acid concentrations as compared with the control diet, but increased （P 〈 0.05） egg albumen weight and height compared with the 7.5% DFA diets. The two levels of DFA produced dose-dependent （P 〈 0.05） changes in three color measures of egg yolk, without affecting four hen plasma biochemical indicators of health. Conclusions： Feeding laying hens with 7.5% DFA in the corn-soybean meal diet for 8 wk had no adverse effect on their health, egg production, or egg quality, but 15% inclusion reduced feed intake, egg production, and efficiency of feed utilization.     

耐镉乳酸菌对蛋鸡组织和鸡蛋中镉残留及部分矿物元素沉积的影响

试验旨在探明耐镉乳酸菌对蛋鸡的脏器系数、镉在蛋鸡组织及鸡蛋中的残留及钙、铁、锌、锰、铜和硒在组织和鸡蛋中沉积的影响。试验分为5组：对照组,饲喂基础日粮;镉组,基础日粮+5 mg/kg镉（以氯化镉的形式添加）;乳酸菌组,基础日粮+1×10¹⁰ CFU/kg耐镉乳酸菌;镉+低剂量乳酸菌组,基础日粮+5 mg/kg镉+1×10¹⁰ CFU/kg耐镉乳酸菌;镉+高剂量乳酸菌组,基础日粮+5 mg/kg镉+1×10¹¹ CFU/kg耐镉乳酸菌,试验期6周。试验期末,采集各组蛋鸡血液,测定总抗氧化力（T-AOC）和超氧化物歧化酶（SOD）活力;采集各组蛋鸡内脏组织和鸡蛋,计算脏器系数,同时测定组织和鸡蛋中镉、钙、铁、铜、锌、锰及硒元素含量。结果显示,与对照组相比,镉及乳酸菌组显著提高了蛋鸡总抗氧化能力（P<0.05）。各处理组中,镉组脾脏指数最低,镉加乳酸菌组脾脏指数显著高于镉组（P<0.05）;与对照组相比,乳酸菌组显著提高心脏指数（P<0.05）。镉组致蛋鸡肝脏和肾脏中镉残留量远高于其他组织,补加耐镉乳酸菌显著减少了心脏的镉残留量（P<0.05）。与对照组相比,镉组显著降低肾脏钙、脾脏和卵黄的锰含量（P<0.05）;与对照组相比,镉加低剂量耐镉乳酸菌显著增加肾脏锰含量、卵黄铁含量及肾脏和脾脏铜含量（P<0.05）;镉在鸡蛋中的残留量较低,与对照组相比,镉组显著降低鸡蛋铁、锰元素含量（P<0.05）,补加耐镉乳酸菌显著增加铁、锌、锰和硒元素含量（P<0.05）。结果表明,在蛋鸡日粮中添加1×10¹⁰ CFU/kg的耐镉乳酸菌,可显著提高蛋鸡血清总抗氧化力水平和蛋鸡的心脏指数,显著改善镉暴露导致的脾脏萎缩和心脏镉的残留量;同时显著增加锰、铜、铁在肾脏、脾脏及卵黄中的含量及铁、锌、锰和硒在鸡蛋中的含量。     

Studies on the use of wheat rich in crude protein in the feeding of broilers. 1. Experimental procedure, weight gains, food consumption and food efficiency]

A fattening trial was carried out with 8 groups of broilers each comprising 1225 birds. Within this trial tests were made to replace the protein feeds of newly hatched chicks over a period of up to 56 days of age, by wheat rich in crude protein. If wheat with a high crude protein content is fed supplementation with lysine and methionine will be necessary depending on the kind of protein feed used. No supplementation with amino acids is required if rations of fish meal + extracted soya bean meal are used despite their reduced content of these amino acids. The broilers consumed larger quantities of the wheat + extracted soya bean meal+fish meal ration than of the mixtures containing no fish meal. Food requirements per unit of weight gain were the same for the mixtures containing high-protein wheat and for the standard maize ration. The lowest food consumption per unit of weight gain was computed for the wheat + extracted soya bean meal diet supplemented with amino acids. The same quantities of lysine, thioamino acids and threonine were necessary for broilers receiving the wheat rations as for birds of the standard group. Protein feed may be saved by using high-protein wheat in the fattening of broilers. The rates of weight gain obtained with these rations are the same or even better than those achieved with rations of maize + fish meal+soya bean meal.     

Replacing corn with pearl millet (raw and sprouted) with and without enzyme in chickens' diet

An experiment was conducted to compare a commercial corn–soya bean meal diet with a pearl millet (raw and sprouted) diet containing less soya bean meal, alone or in combination with exogenous enzyme, on growth performance and ileal villus development of chicks. Two‐hundred‐and‐forty‐one‐day‐old male broilers (10/pen) were randomly allocated to one of the following dietary treatments: (i) a standard corn–soya bean meal control diet (CTL); (ii) a raw pearl millet‐soya bean meal diet (PM); (iii) a sprouted pearl millet‐soya bean meal diet (SPM); (iv) CTL + exogenous enzymes (CE); (v) PM + exogenous enzymes (PE); and (vi) SPM + exogenous enzymes (SPE) with four replicate pens/treatment. Body weight of birds at day 21 did not differ between those fed the CTL, and SPM and PE diets. In comparison with feeding broilers the CTL diet, feeding the PE and SPM diets caused significant decrease in feed intake, but with equivalent growth and feed efficiency. However, at day 21, feed conversion ratio did not differ between birds fed the CTL diet and those fed the PM, PE and SPM diets. At day 21, broilers fed the PM and PE diets had longer villi (p < 0.05) than those fed the CTL diet. At day 21, villi width was reduced (p < 0.05) by raw pearl millet supplementation than CTL diet. It is concluded that, in comparison with corn, broiler diets formulated with sprouted pearl millet or pearl millet with enzyme require less soya bean meal and can be used to improve growth performance traits and villus development.     

Studies on the energy and protein values of soya bean meal and two varieties of field beans using colostomised laying hens

Classical metabolisable energy values (at 90 per cent dry matter) for soya bean meal, Minor's tick bean meal and Throws MS bean meal determined in balance experiments using colostomised laying hens were 2.57, 2.47 and 2.39 kcal/g respectively. True digestibility coefficients for the crude protein of the beans were 90, 84 and 81 per cent respectively; the amino acid digestibility coefficients were generally close to those for crude protein.     

乳酸锌对蛋鸡生产性能及蛋壳质量的影响试验

本试验旨在研究乳酸锌对蛋鸡生产性能及蛋壳质量的影响。试验采用单因子随机分组试验设计,选取1600只360日龄的罗曼粉壳蛋鸡,随机分到4个处理组,各处理组8个重复,每个重复50只鸡。基础饲粮采用为玉米-豆粕型粉状饲粮,处理1饲喂基础饲粮＋60mg／kg-水硫酸锌（以锌计）;处理2饲喂基础饲粮＋60mg／kg乳酸锌（以锌计...     

乳酸锌对蛋鸡生产性能及蛋壳质量的影响

为研究乳酸锌对蛋鸡生产性能及蛋壳质量的影响,试验采用单因子随机分组试验设计,选取1600只360日龄的罗曼粉壳蛋鸡,随机分为4个处理组,每个处理组8个重复,每个重复50只鸡。础饲日粮为玉米-豆粕型粉状饲粮,处理1组饲喂基础饲粮+60 mg/kg一水硫酸锌(以锌计),处理2组饲喂基础饲粮+60 mg/kg乳酸锌(以锌计),处理3组饲喂基础饲粮+40 mg/kg乳酸锌(以锌计),处理4组饲喂基础饲粮+60 mg/kg锌(一水硫酸锌和乳酸锌提供的锌各一半)。结果表明,蛋鸡日粮中添加60 mg/kg乳酸锌(以锌计)能显著降低平均破蛋率、提高平均蛋壳强度(P<0.05)和明显提高平均蛋壳厚度,并且平均死亡率最低,但对蛋鸡的平均产蛋率、平均蛋重、平均日采食量和平均料蛋比无显著影响(P>0.05)。     

吡啶甲酸铬对产蛋鸡的生物安全性评价

本试验旨在研究饲粮添加不同水平吡啶甲酸铬对北京红商品产蛋鸡产蛋性能、血液生理生化指标、器官发育和主要脏器组织病理学变化的影响,进而评价吡啶甲酸铬对产蛋鸡的生物安全性。试验采用单因子完全随机设计,选用360只23周龄北京红商品产蛋鸡,按产蛋率和体重一致的原则随机分为4个组,每个组6个重复,每个重复15只鸡。各组分别在玉米-豆粕型基础饲粮中添加0、0.6、4.0和6.0 mg/kg(以铬计)的吡啶甲酸铬。预试期21 d,正试期70 d。结果表明:1)饲粮铬添加水平对试验全期产蛋鸡产蛋性能和器官指数无显著影响(P0.05)。2)饲粮铬添加水平除显著提高试验第35天产蛋鸡血浆谷草转氨酶活性(P0.05)外,对其他血浆生化指标和血液常规生理指标均无显著影响(P0.05)。3)饲粮铬添加水平对产蛋鸡主要内脏器官的发育均无明显影响,同时均未观测到产蛋鸡的心脏、肝脏、肾脏、卵巢和输卵管组织出现明显的病理学变化。以上结果表明,产蛋鸡玉米-豆粕型饲粮中吡啶甲酸铬的推荐添加水平为0.6 mg/kg时,具有10倍的安全系数,即饲粮中以吡啶甲酸铬形式添加6.0 mg/kg铬对产蛋鸡是安全的。     

Influence of dietary chromium yeast supplementation on apparent trace elements metabolism in growing camel (<Emphasis Type="Italic">Camelus dromedarius</Emphasis>) reared under hot summer conditions

This study aimed to evaluate the effect of dietary chromium (Cr) supplementation on the apparent metabolism of some trace elements in camel calves reared under hot summer conditions. The study was conducted on a total of 15 male camel calves (5–6 months old) reared under hot summer conditions for 12 weeks. The animals were housed individually under shelter and divided into three dietary treatment groups (diets supplemented with 0.0, 0.5, or 1.0 mg Cr/kg DM), five animals each. At the end of the study, a metabolic trial was conducted on all camels for the evaluation of trace elements metabolism. Cr excretion, absorption, and retention showed an increasing trend with the increasing level of dietary Cr supplementation. Dietary Cr supplementation at 0.5 mg Cr/kg DM to camel calves resulted in a significant (P < 0.05) increase in Cu and an increasing trend in Zn and Mn excretion via urine and feces. However, Fe retention increased significantly (P < 0.05) in camel calves fed on diet supplemented with Cr. Dietary Cr supplementation to camel calves resulted in an increasing trend of plasma Cr concentration, while plasma concentration of Cu and Zn tended to decrease and without any effect on plasma Fe concentration. The results of the present study suggests that care should be taken for the negative interaction of Cr with the utilization of other trace elements, in cases where Cr is supplemented to the diet as a feed additive to promote growth and immunity under hot climatic conditions.     

Effects of dietary chromium picolinate and ascorbic acid supplementation on egg production, egg quality and some serum metabolites of laying hens reared under a low ambient temperature (6 degrees C).

This experiment was conducted to evaluate the effects of chromium (chromium picolinate, Cr Pic) and vitamin C (L-ascorbic acid) supplementation on egg production and egg quality in laying hens (Hy-Line) kept at 18 degrees C (at thermo-neutral zone) or 6 degrees C (cold stress) in temperature-controlled rooms. One hundred and fifty laying hens (32 week-old) were divided into 5 groups, 30 hens per group. The laying hens kept at 6 degrees C temperature were fed either a basal diet (low temperature-basal diet, LTB group) or the basal diet supplemented with either 400 micrograms of Cr per kg diet (Cr group), 250 mg of L-ascorbic acid per kg diet (Vit C group) or 400 micrograms of Cr plus 250 mg of L-ascorbic acid per kg diet (Vit C + Cr group) while hens kept at 18 degrees C fed a basal diet (thermo-neutral-basal diet, TNB group). Performance and egg quality were significantly reduced in LTB group compared with TNB group. Supplemental chromium and vitamin C significantly increased live weight change, egg production, and improved feed efficiency in cold-stressed hens compared with group fed the basal diet at 6 degrees C brought up to the values of the group reared under thermoneutral conditions (18 degrees C). Egg production and egg weight were also greater in each supplemental group compared with the LTB group. Separately or as a combination, supplemental chromium and vitamin C increased serum insulin but decreased corticosterone, glucose and cholesterol concentrations. Results of the present study show that supplementing vitamin C and chromium, particularly as a combination, improved the performance of cold-stressed hens. Such a combination of supplement can offer a potential protective management practice in preventing cold stress-related losses in performance of laying hens.     

Studies on reducing the crude protein content of feeds fed to chicks and young hens (laying stock)]

2 rearing trials were carried out on a total of 8550 hybrid chicks (White Leghorn) to investigate in which way food mixtures containing reduced levels of crude protein (supplemented or unsupplemented with amino acids) might influence the growth of chicks and young hens. Decreases from 21.5% to 16.5% in the crude protein content of chicken feed and from 15% to 13% in feeds feed to young hens (greater than 8 weeks of life) did not reduce the live weight of birds at the end of the rearing period to any appreciable extent. No clearly defined differences were found to exist between the different types of feed tested concerning the amount of food and energy consumed per unit of weight gain and the mortality rate among the birds; it was shown, however, that the demand for crude protein per unit of weight gain was clearly reduced in birds reared at the lower crude protein level. For young hens receiving the diet poorer in protein the date when the birds began laying was slightly delayed. Otherwise, no statistically significant differences were found to exist between the young birds fed varying levels of crude protein, concerning the age at 50% laying performance and other parameters that are characteristic of the entire laying period (laying performance, weight of individual eggs, food consumption, mortality, fertilization of hatching eggs, hatchability of eggs). It appears that the feeding of a reduced protein diet to chicks and young hens (laying stock) did not have any detrimental effect on the growth and later laying performance of the birds. Apart from the fact that the demand for protein feeds is considerably reduced during the rearing period the costs of feeding per bird can also be cut down.     

Dietary Supplementation with Microencapsulated Lutein Improves Yolk Color and Lutein Content in Fresh and Cooked Eggs of Laying Hens

This study was conducted to compare the efficacy of diet supplemented with non-microencapsulated lutein (NL) and microencapsulated lutein (ML) in laying hens. A total of 270 Hy-line Brown laying hens (54 weeks old) were allocated to three groups with six replicates of 15 hens and were adapted to a wheat-soybean meal basal diet for two weeks. Next, the control birds were fed the basal diet, and the test birds were fed the basal diet supplemented with 600 mg/kg NL (12 mg/kg available lutein) or 90.1 mg/kg ML (10 mg/kg available lutein) for 35 days. Supplementation of lutein did not affect the productive performance of laying hens, but improved (P<0.05) the yolk color and red/green value (a*), with eggs from the ML group displaying improved color and a* values from the 15^th day of the experimental period. The blue/yellow value (b*) for the yolk showed an increase (P<0.05) through both NL and ML supplements. The yolk color of fried and boiled eggs and a* value of the yolk in fried eggs were improved (P<0.05) only through ML supplemented diet. Both NL and ML supplements resulted in lower (P<0.05) lightness and higher (P<0.05) a* values of yolk in boiled eggs, as well as higher (P<0.05) b* values in fried and boiled eggs. Yolk lutein content in fresh, fried, and boiled eggs was increased (P<0.05) in NL and ML groups with the latter being higher. In conclusion, ML improved yolk pigmentation and lutein retention in laying hens better than NL.