Investigations on the effects of rape oil quality,choline and methionine concentration in diets for laying hens on the trimethylamine content of the eggs,on trimethylamine metabolism and on laying performance

Abstract

An experiment was conducted to study the effects of graded levels of choline addition (0, 500, 1000 and 4000 mg/kg diet) in laying hen diets prepared either with degummed or refined rape oil on the performance, sensory properties and trimethylamine (TMA) contents of the eggs. Furthermore, the diets containing no supplemented choline or 4000 mg choline/kg diet were tested with adequate or inadequate methionine supply (4.2 vs. 2.8 g methionine/kg diet). TMA metabolism and N-balance were measured for the latter diet types, but only with the diets containing refined rape oil. Therefore, a total of 12 and 4 diets were tested in the feeding (n = 60) and balance study (n = 9). Laying performance (23 – 75 weeks of age) was not significantly influenced by increasing choline additions with the exception of feed-to-egg mass ratio which decreased significantly linearly (p _linear = 0.003). However, a significant interaction between choline addition and laying month was detected which was caused by a depression of performance of the unsupplemented control group occurring from the sixth laying month. The most obvious effect of an inadequate methionine supply was a temporary drop in performance between the third and sixth laying months. The mean TMA-concentration in pooled egg yolks [μg/g] increased with dietary choline concentration [mg/kg] in an exponentially related fashion (y = 1.14 + 4E^?10 ? x^2.71, r² = 0.962) and suggested only a minor influence of total dietary choline on TMA content up to approximately 2000 mg choline/kg. Individual TMA-concentrations varied greatly from 0.4 – 1.5 μg/g, from 2.2 – 34 μg/g and from 18.4 – 75 μg/g for eggs with a normal, aberrant and heavily aberrant odour, respectively. It is concluded that a total choline concentration of at least approximately 1500 mg/kg is necessary to maintain a maximal laying performance. An inadequate methionine supply cannot be compensated by an increased addition of choline. Neither degummed nor refined rape oil influenced the TMA content of eggs.     

Quail FMO3 Gene Cloning,Tissue Expression Profiling,Polymorphism Detection and Association Analysis with Fishy Taint in Eggs

Quail eggs comprise a significant and favourable part of table eggs in certain countries. Some quail eggs, however, present fishy off-flavor which directly influences their quality. It is reported that flavin-containing monooxygenase 3 (FMO3) is associated with fish-odour trait in human and animal products. FMO3 is responsible for the degradation of trimethylamine (TMA) in vivo. Loss-of-function mutations in FMO3 gene can result in defective TMA N-oxygenation, giving rise to disorder known as “fish-odour syndrome” in human, as well as the fishy off-flavor in cow milk and chicken eggs. In order to reveal the genetic factor of fishy taint in quail eggs, we cloned the cDNA sequence of quail FMO3 gene, investigated FMO3 mRNA expression level in various tissues, detected SNPs in the coding region of the gene and conducted association analysis between a mutation and the TMA content in quail egg yolks. The 1888 bp cDNA sequence of quail FMO3 gene encoding 532 amino acids was obtained and characterized. The phylogenetic analysis revealed quail FMO3 had a closer relationship with chicken FMO3. The FMO3 mRNA was highly expressed in liver and kidney of quail. Nine SNPs were detected in the coding sequence of quail FMO3 gene, including a nonsense mutation (Q319X) which was significantly associated with the elevated TMA content in quail egg yolks. Genotype TT at Q319X mutation loci was sensitive to choline. With addition of choline in the feed, the quails with homozygote TT at the Q319X mutation loci laid fish-odour eggs, indicating an interaction between genotype and diet. The results indicated that Q319X mutation was associated with the fishy off-flavor in quail eggs. Identification of the unfavorable allele T of quail FMO3 gene can be applied in future quail breeding to eliminate fishy off-flavor trait in quail eggs.     

Investigations on the effects of rape oil quality, choline and methionine concentration in diets for laying hens on the trimethylamine content of the eggs, on trimethylamine metabolism and on laying performance

An experiment was conducted to study the effects of graded levels of choline addition (0, 500, 1000 and 4000 mg/kg diet) in laying hen diets prepared either with degummed or refined rape oil on the performance, sensory properties and trimethylamine (TMA) contents of the eggs. Furthermore, the diets containing no supplemented choline or 4000mg choline/kg diet were tested with adequate or inadequate methionine supply (4.2 vs. 2.8 g methionine/kg diet). TMA metabolism and N-balance were measured for the latter diet types, but only with the diets containing refined rape oil. Therefore, a total of 12 and 4 diets were tested in the feeding (n = 60) and balance study (n = 9). Laying performance (23 -75 weeks of age) was not significantly influenced by increasing choline additions with the exception of feed-to-egg mass ratio which decreased significantly linearly (P(linear) = 0.003). However, a significant interaction between choline addition and laying month was detected which was caused by a depression of performance of the unsupplemented control group occurring from the sixth laying month. The most obvious effect of an inadequate methionine supply was a temporary drop in performance between the third and sixth laying months. The mean TMA-concentration in pooled egg yolks [microg/g] increased with dietary choline concentration [mg/kg] in an exponentially related fashion (y = 1.14 + 4E(-10) x x(2.71), r2 = 0.962) and suggested only a minor influence of total dietary choline on TMA content up to approximately 2000mg choline/kg. Individual TMA-concentrations varied greatly from 0.4 - 1.5 microg/g, from 2.2 - 34 microg/g and from 18.4 - 75 microg/g for eggs with a normal, aberrant and heavily aberrant odour, respectively. It is concluded that a total choline concentration of at least approximately 1500 mg/kg is necessary to maintain a maximal laying performance. An inadequate methionine supply cannot be compensated by an increased addition of choline. Neither degummed nor refined rape oil influenced the TMA content of eggs.     

Quality of eggs from Lohmann Brown Classic laying hens fed black soldier fly meal as substitute for soya bean

Soya bean is the main protein source in poultry feed but rising prices make an alternative protein source necessary. Insects, such as the black soldier fly (Hermetia illucens), may be an attractive solution for hens, although little information is available on their effect on egg quality. The present study aims to fill this gap by testing the effect of 100% replacement of soya bean with H. illucens larva meal in the diet of Lohmann Brown Classic laying hens for 21 weeks. At the end of the trial, the eggs were characterized for parameters such as weight, colour, proximate composition of albumen and yolk, and content of carotenoids, tocopherols and cholesterol. The fatty acid profile of yolks was also determined. Hens fed the insect-based diet produced eggs (HIM group) with a higher proportion of yolk than the group fed the soya bean-based diet (SBM group). HIM was associated with redder yolks (red index 5.63 v. 1.36) than SBM. HIM yolks were richer in γ-tocopherol (4.0 against 2.4 mg/kg), lutein (8.6 against 4.9 mg/kg), β-carotene (0.33 against 0.19 mg/kg) and total carotenoids (15 against 10.5 mg/kg) than SBM yolks. The fatty acid composition of HIM yolks was almost identical to that of SBM yolks. Finally, HIM yolks contained 11% less cholesterol than SBM yolks. These results suggest that H. illucens larva meal is a suitable total substitute for soya bean meal in the diet of Lohmann Brown Classic laying hens. A sustainable alternative to the plant protein source therefore seems feasible.     

Effects of feeding deoxynivalenol (DON)-contaminated wheat to laying hens and roosters of different genetic background on the reproductive performance and health of the newly hatched chicks

A total of 216 23-week-old laying hens from two different genetic backgrounds (half of the birds were Lohmann brown [LB] and [LSL] hens, respectively) and 24 adult roosters were assigned to a feeding trial to study the effect of increasing concentrations of deoxynivalenol (DON) in the diet (0, 5, 10 mg/kg) on the reproductive performance of hens and roosters, and the health of the newly hatched chicks. Hatchability was adversely affected by the presence of DON in LB hens’ diet, while the hatchability of the LSL chicks was significantly higher than LB chicks. An interaction effect between DON in the hens’ diet and the breed was noticed on fertility, as the fertility was decreased in the eggs of LB hens receiving 10 mg/kg DON in their diet and increased in the eggs of LSL hens fed 10 mg/kg DON. Moreover, spleen relative weight was significantly decreased in the chicks hatched from eggs of hens fed contaminated diets, while gizzard relative weight was significantly decreased in LB chicks with 10 mg/kg DON in their diet compared with the control group. On the other hand, the chicks’ haematology and organ histopathology were not affected by the dietary treatment. Additionally, the presence of DON in the roosters’ diet had no effect on fertility (the percentage of fertile eggs of all laid eggs). Consequently, the current results indicate a negative impact of DON in LB hens’ diet on fertility and hatchability, indicating that the breed of the hens seems to be an additional factor influencing the effect of DON on reproductive performance of the laying hens.     

Performance,Egg Quality Traits,and Serum Metabolite Concentrations of Laying Hens Affected by Dietary Supplemental Chromium Picolinate and Vitamin C Under a Heat-Stress Condition

A 3?×?2 factorial experiment consisting three levels (0, 200, and 400 μg/kg) of chromium (chromium picolinate) and two levels (0 and 250 mg/kg) of vitamin C was employed to evaluate the effects of these dietary supplements on performance, egg quality traits, and serum biochemical parameters of heat-stressed laying hens (Lohmann LSL-Lite) from 66 to 74 weeks of age. Feed intake increased when birds were given either 400 μg/kg chromium or 250 mg/kg vitamin C (P?<?0.05), but the birds that received both chromium and vitamin C consumed feed similar to those that received only chromium. Dietary treatments had no effect on egg production, egg mass, egg volume, feed conversion ratio, and body mass (P?>?0.05). The birds that fed on diet with chromium or vitamin C produced eggs with higher shell mass and thickness compared to the control. Both eggshell mass and thickness decreased when vitamin C and chromium were supplemented simultaneously, and birds given the diet supplemented with 400 μg/kg chromium and 250 mg/kg vitamin C had eggshell mass and thickness similar to those of the control group. The serum concentration of chromium increased due to increasing level of dietary chromium (P?<?0.05). The birds that received diet with chromium and vitamin C had higher serum concentrations of chromium compared to those that received only chromium (P?<?0.05). Similarly, the hens that received chromium and vitamin C had higher serum concentrations of calcium and phosphorus compared to the hens fed with other treatments (P?<?0.05). The birds given with supplemental chromium exhibited lower serum glucose, total cholesterol, and triglycerides concentrations but higher serum albumin and total protein concentrations compared to the other groups (P?<?0.05).     

A Combination of Zinc and Pyridoxine Supplementation to the Diet of Laying Hens Improves Performance and Egg Quality

The objective of this study was to investigate whether zinc, along with pyridoxine, is effective in improving performance and egg quality of laying hens. One hundred and twenty, 28-week-old Hy-Line laying hens were assigned to four treatment groups, 30 hens each. The birds were fed a basal diet or the basal diet supplemented with either 30 mg of zinc/kg of diet, 8 mg of pyridoxine/kg of diet, or 30 mg of zinc plus 8 mg of pyridoxine/kg of diet. Feed conversion (P < 0.01) and egg production (P < 0.01) improved most when both zinc and pyridoxine were supplemented to the diet. Eggshell weights were also greatest (P < 0.01) when the diet was supplemented with both pyridoxine and zinc. Egg-shape index was, however, greatest with zinc-supplemented diet (P < 0.004). Haugh unit was greatest in eggs of hens fed a diet supplemented with both zinc and pyridoxine (P < 0.01). Dietary zinc and pyridoxine supplementations together increased plasma calcium and phosphorous concentrations (P < 0.002). The results of the present study suggested that zinc (30 ppm) and pyridoxine (8 ppm) supplements, when used together, are recommended in terms of a better performance and egg quality in laying hens.     

Influence of high vitamin E dosages on retinol and carotinoid concentration in body tissues and eggs of laying hens

The aim of the study was to contribute to the discussion of overdosing vitamin E in laying hens. A total of 45 laying hens, divided into 5 groups were fed diets supplemented with either 0; 100; 1000; 10 000 or 20 000 mg dl‐α‐tocopheryl acetate/kg diet over a period of 10 weeks. Concentrations of vitamins A and E were measured in plasma, various tissues and egg yolk. Furthermore egg yolk colour and some carotinoids were measured in egg yolks. None of the vitamin E doses significantly influenced performance of the hens. As expected, vitamin E concentration in plasma, all tissue samples and egg yolk was significantly increased with increasing tocopherol content in the diet. The egg yolk showed the highest vitamin E concentration, followed by liver and muscles. Feeding 1000 mg α‐tocopheryl acetate per kg diet resulted in an increase of vitamin A concentration in the liver. Very high doses (10 000 and 20 000 mg/kg diet) significantly decreased retinol concentration in the liver and egg yolk, as well as carotinoid concentration in the egg yolk. The lower carotinoid concentration in egg yolk resulted in a decreased intensity of egg yolk colour. A prooxidative and/or competitive effect of very high doses of vitamin E with other fat soluble substances has been discussed.     

Effects of Dietary Form of Selenium on Its Distribution in Eggs

The objective of this experiment was to investigate the selenium distribution in eggs from hens fed diets supplemented with Se from sodium selenite (SS) or selenium-enriched yeast (SY). One-day-old female chickens of Hy-Line Brown breed were randomly divided into four groups according to dietary treatments and, for the subsequent 9?months, were fed diets which differed only in the form or amount of Se supplemented. During the whole experiment, group 1 (control) was fed basal diet (BD) with only background Se level of 0.13?mg/kg dry matter (DM). Diets for groups 2 and 3 consisted of BD supplemented with an Se dose of 0.4?mg/kg DM either in the form of SS or SY, respectively. Group 4 was fed BD supplemented with 0.9?mg Se/kg DM from SY. After 9?months of dietary treatments, the Se levels in egg yolk and albumen from hens fed unsupplemented diet were almost identical whereas eggs from hens given diet supplemented with SS showed significantly higher Se deposition in yolk than in albumen (P?相似文献   

Probing the effects of dietary selenised glucose on the selenium concentration,quality, and antioxidant activity of eggs and production performances of laying hens

Selenised glucose (SeGlu) is a newly invented organic selenium compound being synthesised through the selenisation reaction of glucose with NaHSe. We hypothesised that glucose could be used as a carrier for the stable low-valent organoselenium to enhance the selenium concentrations of eggs. To probe the effects of SeGlu on production performances of laying hens, egg selenium concentration, egg quality, and antioxidant indexes, 360 Hy-Line Brown laying hens were randomly assigned to three treatment groups fed with a basal diet alone or the diet supplemented with 5 or 10 mg/kg of Se from SeGlu. The results showed that SeGlu treatment not only enhanced (P < 0.001) the Se concentration in albumen and yolks, glutathione peroxidase activity, and total antioxidant capacity of eggs but also increased (P = 0.032) the Haugh unit of eggs being stored for 2 weeks, while the production performances and egg qualities of fresh eggs were not affected. Moreover, SeGlu supplementation linearly (P < 0.001) increased the scavenging ability of superoxide radicals in eggs. Briefly, SeGlu can enhance the selenium deposition and antioxidant activity of eggs, thereby meeting the nutritional requirement for Se-deficient humans.     

Impact of an energy- and nutrient-reduced diet containing 10% lignocellulose on animal performance,body composition and egg quality of dual purpose laying hens

In response to ethical concerns regarding the killing of day-old male chicks of layer breeds, the use of dual purpose chickens is increasingly discussed in public while data on nutritional requirements of dual purpose laying hens are not available. The present study examined the impact of an energy- and nutrient-reduced diet containing lignocellulose on performance, body composition and egg quality of dual purpose hens. Female Lohmann Dual chicks were allocated to 12 pens and fed two different diets for 52 weeks: a control (CON) and a treatment diet (LC), based on CON but diluted with 10% lignocellulose. During the trial, animal performance, whole-body composition and egg quality parameters of hens were consistently ascertained. The results showed that LC-fed hens had lower body weights compared to those receiving CON (p < 0.05). During the laying period, feed intake was increased in LC-fed hens (p < 0.001). LC-fed hens showed a higher egg production and egg mass resulting in an improved feed efficiency (p < 0.05) and laid smaller eggs compared to CON-fed hens (p < 0.001). At 52 weeks of age, bodies of LC-fed hens had higher protein and lower fat contents than those fed with CON diet (p ≤ 0.001). Mean body weight was positively correlated to the body fat content (p = 0.004) and body fat content was negatively correlated to the egg production (p = 0.043). Analyses of the egg quality showed that yolk mass at all sampling points and albumen mass at 27 and 42 weeks were lower in hens fed with diet LC compared to those fed with diet CON (p< 0.05). In conclusion, the feeding of energy- and nutrient-reduced diets containing 10% lignocellulose reduced the body fat content and simultaneously improved the laying performance in dual purpose hens.     

Effects of Chromium Propionate on Egg Production,Egg Quality,Plasma Biochemical Parameters,and Egg Chromium Deposition in Late-Phase Laying Hens

This study was conducted to investigate the effects of chromium propionate on egg production, egg quality, plasma biochemical parameters and egg chromium deposition in late-phase laying hens. Four hundred thirty-two 60-weeks old laying hens were divided into four groups of 108 birds per group according to egg production. The dietary treatments consisted of the basal diet adding with 0, 200, 400, and 600 μg/kg chromium as chromium propionate. All laying hens were given feed and water ad libitum for 8 weeks. The addition of 400 μg/kg Cr as chromium propionate increased egg production (P?<?0.01) during the later 4 weeks, but decreased albumen height, yolk color score, and Haugh unit of eggs. Six hundred micrograms per kilogram Cr as chromium propionate supplementation improved shell thickness (P?<?0.05). 200 μg/kg Cr as chromium propionate supplementation decreased the uric acid concentration by 31 % (P?<?0.05). However, supplemental Cr did not affect the egg chromium deposition of hens (P?>?0.05). These data indicated that feeding of late-phase laying hens with chromium propionate could improve egg production, increase eggshell thickness, but do not result in abnormal levels of chromium deposition in eggs.     

Effect of Selenium from Selenium-Enriched Kale Sprout Versus Other Selenium Sources on Productivity and Selenium Concentrations in Egg and Tissue of Laying Hens

A 6-week trial was conducted to compare the effect of selenium (Se) from hydroponically produced Se-enriched kale sprout (HPSeKS), sodium selenite (SS), and Se-enriched yeast (SeY) in laying hens. A total of 144 40-week-old hens were randomly divided into four groups, according to a completely randomized design. Each group consisted of four replicates with nine hens per replicate. The dietary treatments were T1 (basal diet) and T2, T3, and T4 (basal diets supplemented with 0.30 mg Se/kg from SS, SeY, and HPSeKS, respectively). Results showed that Se supplement did not affect (p > 0.05) productivity and egg quality. Hens fed Se from HPSeKS and SeY exhibited higher (p < 0.05) Se bioavailability than hens fed Se from SS. Whole egg Se concentration of hens fed Se from HPSeKS was similar (p > 0.05) to that of hens fed Se from SeY, but higher (p < 0.05) than that of hens fed Se from SS. However, the breast muscle and heart tissue Se concentrations of hens fed Se from SS, SeY, and HPSeKS were not different (p > 0.05). The results of this trial demonstrated that Se from HPSeKS and SeY was more efficient than Se from SS on Se bioavailability and whole egg Se concentration in laying hens.     

The involvement of trimethylamine oxide in fish meal in the production of egg taint

Endogenous trimethylamine (TMA) oxidation was inhibited by giving (±)-5-vinyl-2-oxazolidenethione to laying hens that had been bred for low TMA oxidase activity. The addition of TMA oxide to the diet (5 g kg^?1) immediately produced an enormous increase in the TMA content of their eggs and a strong crab-like taint. Hens from another flock whose eggs were tainted when they were previously fed on capelin meal as a protein supplement (100 g kg^?1) again showed this abnormality when TMA oxide was added to the diet (0.5 g kg^?1) to simulate the amounts supplied by the meal. Tests with intravenous ¹⁴C-TMA demonstrated that their ability to oxidise TMA was lower than that of unaffected hens. Dietary TMA oxide and intravenous TMA reduced the oxidation of the test dose of ¹⁴C-TMA. The oxide had no effect when given intravenously and did not inhibit TMA oxidase in vitro. It was concluded that TMA oxide is an important source of TMA in fish meal and that tainting occurs when hens with inherently low TMA oxidase activity are overloaded with TMA derived from dietary TMA oxide and choline by the action of enteric bacteria. The sporadic occurrence of the taint in the field may be due partly to wide variations in the oxide content of fish meals.     

An Optimal Dietary Zinc Level of Brown-Egg Laying Hens Fed a Corn–Soybean Meal Diet

An experiment was conducted to estimate the optimal dietary zinc (Zn) level of brown-egg laying hens fed a corn–soybean meal diet from 20 to 40 weeks of age. A total of 120 20-week-old Beijing Red commercial laying hens were randomly allotted by bodyweight to one of five treatments with six replicates of four birds each in a completely randomized design, and fed a Zn-unsupplemented corn–soybean meal basal diet containing 27.95 mg Zn/kg by analysis and the basal diets supplemented with 30, 60, 90, or 120 mg Zn/kg as Zn sulfate (reagent grade ZnSO₄·7H₂O) for a duration of 20 weeks. Laying performance, egg quality, tissue Zn concentrations, and activities of serum alkaline phosphatase (AKP), and liver copper-Zn superoxide dismutase (CuZnSOD) were measured. Regression analyses were performed to estimate an optimal dietary Zn level whenever a significant quadratic response (P < 0.05) was observed. Tibia Zn concentration (P = 0.002) and serum AKP activity (P = 0.010) showed significant quadratic responses to dietary supplemental Zn levels. The estimates of dietary Zn requirements for brown-egg laying hens from 20 to 40 weeks of age were 71.95 and 64.63 mg/kg for tibia Zn concentration and serum AKP activity, respectively. The results from this study indicate that the tibia Zn might be a more suitable and reliable parameter for Zn requirement estimation, and the optimal dietary Zn level would be about 72 mg/kg for brown-egg laying hens fed a corn–soybean meal diet from 20 to 40 weeks of age.     

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 °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 °C (at thermo-neutral zone) or 6 °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 °C temperature were fed either a basal diet (low temperature-basal diet, LTB group) or the basal diet supplemented with either 400 µg of Cr per kg diet (Cr group), 250mg of L-ascorbic acid per kg diet (Vit C group) or 400 µg of Cr plus 250mg of L-ascorbic acid per kg diet (Vit C + Cr group) while hens kept at 18 °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 °C brought up to the values of the group reared under thermoneutral conditions (18 °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.     

Effects of Enterococcus faecalis on egg production,egg quality and caecal microbiota of hens during the late laying period

This study was conducted to determine the effects of diet supplementation of laying hens with Enterococcus faecalis (EF) on egg production, egg quality and caecal microbiota. A total of 360 Hy-Line Brown laying hens (72 weeks old) were divided into three groups with four replicates of 30 birds each. The laying hens were fed with the basal diet (Control), the basal diet + 3.75 · 10⁸ cfu EF/kg (Group I) or the basal diet + 7.5 · 10⁸ cfu EF/kg (Group II). The experiment lasted for 45 d. Eggs and caecal samples were collected at the end of the experiment. Results showed that dietary supplementation with EF did not affect the average daily egg weight, cracked egg rate, mortality and egg quality. However, EF supplementation caused a significantly increased laying rate and decreased feed/egg ratio (p < 0.05). The differences in caecal microbiota between Group II and the Control were significant. The relative abundance of Verrucomicrobia and Cyanobacteria at the phylum level, Rikenellaceae, Christensenellaceae and Veillonellaceae at the family level, and the Faecalibacterium, Christensenellaceae R-7 group and Eubacterium coprostanoligenes group at the genus level changed significantly in Group II compared with the Control (p < 0.05). In conclusion, the tested dietary supplementations with EF improved product performance and affected the caecal microbial community structure of laying hens during the late laying period.     

Effects of Dietary Supplementation of Zinc Oxide and Zinc Methionine on Layer Performance,Egg Quality,and Blood Serum Indices

The objective of this study was to evaluate the effectiveness of dietary zinc oxide (ZnO) and zinc methionine (Zn-Met) supplementation on layer performance, quality of egg, some blood constituents, and oxidative status in blood of laying hens. A total of 120 laying hens (Hisex Brown) 22-week-old were indiscriminately allotted into five groups of 24 hens with six replications (four birds/replicate). A complete randomized design experiment was performed including control (basal diet), two levels of ZnO (50 and 100 mg/kg basal diet), and two levels of Zn-Met (50 and 100 mg/kg basal diet) through 22 to 34 weeks of age. Supplementation of 100 mg of Zn-Met significantly (P = 0.001) increased feed intake compared to other treatment groups. The groups supplemented with 50 mg of ZnO and 100 mg of Zn-Met reported the significantly higher egg production rate (P = 0.002) and egg mass (P < 0.001) compared to other treated groups. All traits of egg quality were not statistically (P < 0.05 or 0.01) affected by ZnO or Zn-Met supplementation except shell thickness, Haugh unit score, and yolk to albumin ratio. Dietary supplementation of either ZnO or Zn-Met did not affect the oxidative parameters in serum except the activity of Cu-Zn-SOD. Serum triglyceride, total cholesterol, and LDL cholesterol (low-density lipoprotein) were significantly (P < 0.05) affected by Zn supplementation, while HDL cholesterol (high-density lipoprotein) did not affect. Compared to the control group, supplementation of ZnO or Zn-Met increased serum content of zinc with no differences among supplemental zinc doses. It could be concluded that dietary inorganic (ZnO) and organic (Zn-Met) supplemented up to 50 and 100 mg/kg, respectively, can be used as effective supplements to improve productivity of laying hens, serum zinc level, lipid profile (triglyceride and LDL cholesterol), and activity of Cu-Zn-SOD.     

Performance and egg quality of laying hens fed flaxseed: highlights on n-3 fatty acids,cholesterol, lignans and isoflavones

Flaxseed is a rich source of α-linolenic acid and phytoestrogens, mainly lignans, whose metabolites (enterodiol and enterolactone) can affect estrogen functions. The present study evaluated the influence of dietary flaxseed supplementation on reproductive performance and egg characteristics (fatty acids, cholesterol, lignans and isoflavones) of 40 Hy-Line hens (20/group) fed for 23 weeks a control diet or the same diet supplemented with 10% of extruded flaxseed. The flaxseed diet had approximately three times the content of lignans (2608.54 ng/g) as the control diet, mainly secoisolariciresinol diglucoside (1534.24 v. 494.72 ng/g). When compared with the control group, hens fed flaxseed showed a similar deposition rate (72.0% v. 73.9%) and egg yield. Furthermore, there was no effect of flaxseed on the main chemical composition of the egg and on its cholesterol content. Estradiol was higher in the plasma of the control group (1419.00 v. 1077.01 pg/ml) probably due to the effect of flaxseed on phytoestrogen metabolites. The plasma lignans were higher in hens fed flaxseed, whereas isoflavones were lower, mainly due to the lower equol value (50.52 v. 71.01 ng/ml). A similar trend was shown in eggs: the flaxseed group had higher level of enterodiol and enterolactone, whereas the equol was lower (198.31 v. 142.02 ng/g yolk). Secoisolariciresinol was the main lignan in eggs of the flaxseed group and its concentration was three times higher then control eggs. Flaxseed also improved the n-3 long-chain polyunsaturated fatty acids of eggs (3.25 v. 0.92 mg/g egg), mainly DHA, however, its oxidative status (thiobarbituric reactive substances) was negatively affected. In conclusion, 10% dietary flaxseed did not affect the productive performance of hens or the yolk cholesterol concentration, whereas the lignans and n-3 polyunsaturated fatty acid content of eggs improved. Further details on the competition between the different dietary phytoestrogens and their metabolites (estrogen, equol, enterodiol and enterolactone) should be investigated.     

Effect of different dietary energy and protein sources on antioxidant status,fresh yolk fatty acid profile and microstructure of salted yolks in laying ducks

The study investigated whether different dietary energy and protein sources affect laying performance, antioxidant status, fresh yolk fatty acid profile and quality of salted yolks in laying ducks. In all, 360 19-week-old Longyan ducks were randomly assigned to four diets in a factorial arrangement (2×2). The four diets consisted of two energy sources, corn (CO) or sorghum (SO) and two protein sources, soybean meal (SM) and rapeseed meal with corn distillers dried grains with solubles (RMD), and each treatment contained six replicates of 15 birds each. The experimental diets were isocaloric (metabolizable energy, 10.84 MJ/kg) and isonitrogenous (CP, 17%). The results showed that egg production, average egg weight, egg mass and feed conversion ratio were not affected by diets (P>0.05). Plasma contents of reduced glutathione (GSH), GSH/oxidized glutathione and total antioxidant capacity were lower (P<0.05) in ducks fed the RMD diets compared with those fed SM diets with a substantial increase (P=0.006) in plasma content of malondialdehyde (MDA). Egg yolks from ducks fed SO diets had higher proportions of polyunsaturated fatty acids (PUFA) and lower saturated and monounsaturated fatty acids compared with CO diets (P<0.001). Similarly, ducks fed RMD diets had a higher content of PUFA and n-6/n-3 ratio in fresh yolks (P<0.001), and increased salted yolk MDA, carbonylated proteins content and incidence of hard salted yolks (P<0.05) compared with SM diets. Scanning electron microscopy showed that salted yolks contained rougher polyhedral granules and fewer fat droplets, and were surrounded with a layer of bunchy fibers in ducks fed SO+RMD than those fed CO+SM diet. In conclusion, the current study showed that feeding laying ducks with diets containing SO or RMD reduced antioxidant capacity and increased egg yolk concentrations of PUFA. It appeared that egg yolks from ducks fed these diets were more sensitive to lipid peroxidation and protein oxidation during salting, and reduced the quality of salted yolks.