Effects of phytase supplementation on production performance,egg and bone quality,plasma biochemistry and mineral excretion of layers fed varying levels of phosphorus

Excessive fecal excretion of phosphorus (P) has increasingly become an environmental issue due to oversupply of P in layer rations, and thus it is imperative to minimize safety margins for P to ensure the sustainability of the egg industry. In this study, a 12-week feeding trial (22 to 34 weeks of age) was conducted to evaluate the effects of phytase supplementation on production performance, plasma biochemistry, egg and bone quality and P excretion of laying hens fed various levels of non-phytate P (NPP). Forty-eight Lohmann white laying hens were randomly allocated to one of six corn–soybean meal–oat-based diets: diets containing 2.0, 2.5 or 3.0 g/kg NPP without phytase, and diets containing 1.0, 1.5 or 2.0 g/kg NPP with phytase (1 000 U/kg diet) where phytase inclusion was expected to provide 1.0 g/kg NPP to laying hens, thus making the phytase-unsupplemented treatment served as a control for the phytase-supplemented treatment accordingly. Productive performance was recorded during the experimental period. Blood and egg samples were collected, and digestibility studies were conducted at weeks 6 and 12 of the experiment. Bone mineralization was evaluated at the end of the experiment. Egg weight and egg production, feed consumption, BW and feed conversion ratio of laying hens fed lower NPP diets supplemented with phytase were comparable to those of hens fed high NPP phytase-unsupplemented controls. Eggshell thickness, specific gravity, Haugh units, tibia bone mineral density, tibia ash percent, plasma P and other biochemical parameters were not significantly different among dietary treatments. Total P intake, excretion and retention were affected by diet (P < 0.001), but its deposition in eggs was not significantly different. Contrast analysis further showed that total P excretion of phytase present vs phytase absent was averagely reduced by 40.4 mg/hen per day (P < 0.01). Moreover, total P excretion was linearly (P < 0.01) reduced with lowering dietary NPP, and this relationship was similar regardless of whether phytase was supplemented or not. The results from this study indicated that NPP levels in laying hen diets could be reduced to 1.0 g/kg (excluding the portion of NPP released by phytase) with the inclusion of phytase, without negative effects on production performance and health of the hens, thereby diminishing P excretion into environment.     

The impacts of fermented feed on laying performance,egg quality,immune function,intestinal morphology and microbiota of laying hens in the late laying cycle

Fermented feed has the potential to improve poultry gastrointestinal microecological environment, health condition and production performance. Thus, the present study was undertaken to explore the effects of fermented feed on the laying performance, egg quality, immune function, intestinal morphology and microbiota of laying hens in the late laying cycle. A total of 360 healthy Hy-Line Brown laying hens aged 80 weeks were used to conduct a 56-day study. All hens were randomly separated into two treatment groups, with five replicates of 36 hens each as follows: basal diet containing 0.0% fermented feed (CON) and 20% fermented feed (FF). Subsequent analyses revealed that fermented feed supplementation was associated with significant increases in laying rates together with reduced broken egg rates and feed conversion ratio for hens in FF group (P < 0.05). There were additionally significant increases in both albumen height and Haugh unit values in hens following fermented feed supplementation (P < 0.05). Fermented feed was also associated with increases in duodenal, jejunal and ileac villus height (P < 0.05). Laying hens fed fermented feed had higher immune globulin (Ig)A, IgG, IgM levels (P < 0.01,) and higher interleukin 2, interleukin 6, tumour necrosis factor α and interferon γ (P < 0.05) concentrations than CON. Analysis of the microbiota in these laying hens revealed the alpha diversity was not significantly affected by fermented feed supplementation. Firmicutes abundance was reduced in caecal samples from FF hens relative to those from CON hens (30.61 vs 35.12%, P < 0.05). At the genus level, fermented feed was associated with improvements in relative Lactobacillus, Megasphaera and Peptococcus abundance and decreased Campylobacter abundance in laying hens. These results suggest that fermented feed supplementation may be beneficial to the laying performance, egg quality, immunological function, intestinal villus growth and caecal microecological environment of laying hens at the end of the laying cycle.     

The effect of replacing soya bean oil with glycerol in diets on performance,egg quality and egg fatty acid composition in laying hens

The objective of this experiment was to replace soya bean oil with glycerol in laying hen diets and assess the change’s effect on performance, parameters of egg quality and the egg fatty acid profile. A total of 60 44-week-old Hy-Line W36 laying hens were distributed according to a completely randomised experimental design into four treatments consisting of glycerol substitutions for soya bean oil dietary at varying inclusion levels (0%, 25%, 50% and 75%), with five replicates of three birds each. Dietary treatments had no significant effect on BW change, egg production, feed intake, feed conversion ratio, egg weight and egg mass of laying hens. The inclusion of glycerol in the diet of laying hens had no significant effect on egg specific gravity, eggshell breaking strength, eggshell weight, eggshell thickness, egg shape index, albumen index, yolk index, haugh unit, albumen pH, yolk pH and egg yolk colour values. The inclusion of glycerol in the diet of laying hens had no significant effect on palmitic, palmitoleic, stearic, oleic and linolenic acid contents of the egg yolk. The linoleic acid and polyunsaturated fatty acid contents of the egg yolk significantly decreased with the higher levels of dietary glycerol supplementation (P<0.05). The results of this study show that it is possible to replace 75% of soya bean oil (4.5% in diet) with glycerol.     

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.     

Thermoregulatory,behavioral and productive responses of laying hens supplemented with different types and dosages of phytases raised in a hot environment: An integrative approach

This study had the following objectives: (i) to evaluate the thermoregulatory and behavioral responses of light laying hens supplemented with different types and dosages of phytases in the two day shifts; and (ii) to integrate the thermoregulatory and behavioral responses with performance of these birds raised in a hot environment. 270 light laying hens of the Hy-Line White lineage, with a body weight of 1.60 ± 0.092 kg were distributed in a completely randomized design in a 2 × 2 + 1 factorial model with two types of phytases (bacterial and fungal) and two dosages (450 and 900 FTU), and a control diet. The day shift (morning and afternoon) was considered as a fixed effect in the factorial arrangement. Principal component analysis (P_CA), correspondence analysis (C_A) and canonical discriminant analysis (C_DA) were used. There was no interaction (P > 0.05) between phytases and dosages for thermoregulatory responses. Respiratory rate (R_R), cloacal temperature (C_T), and surface temperature with feathers (S_TWF) and featherless (S_TF) were higher (P < 0.001) in the afternoon. Birds show different thermoregulatory and behavioral responses in the two shifts of the day. We also observed that birds supplemented with bacterial and fungal phytase showed similar thermoregulatory and behavioral responses to the control group in both day shifts. Expression of the “eating” activity was greater in the morning, while the birds remained sitting longer in the afternoon. Egg production was higher (P < 0.001) in birds supplemented with bacterial phytase. The phytase dosages had no effect on thermoregulatory, behavioral or performance responses. Egg production, feed conversion per dozen eggs corresponded to 81.1% of the differences between bacterial and fungal phytase supplementation and group control. Thus, we conclude that: (i) phytase dietary supplementation has no effect on the thermoregulatory responses of laying hens reared in a hot environment; (ii) birds supplemented with bacterial phytase showed higher egg production; and (iii) phytases (450 and 900 FTU) do not interfere with productive, behavioral and thermoregulatory responses.     

Untersuchungen über die Wirkung von Vitamin B12 und behandeltem Sojaschrot bei der Mast von Küken

To examine the effects of dietary conjugated linoleic acids (CLA) on lipid metabolism and antioxidant capacity in laying hens, Hy-Line Brown layers (n = 384, 52 weeks old) were randomly allocated to one of four dietary treatments. Each treatment had six replicates of 16 hens each. All birds were assigned to acorn-soybean meal-based diet containing a mixture of CLA at 0%, 1%, 2% or 4% for six weeks. With increasing dietary CLA, egg weight and feed intake decreased, and yolk colour was darkened. Feed efficiency was improved at 1% and 2% dietary CLA. Serum triglyceride concentration was significantly reduced by CLA in a dose dependent manner. A linear decrease in total cholesterol and low-density lipoprotein cholesterol, and an increase in high-density lipoprotein cholesterol levels were observed after CLA supplementation. With increasing dietary CLA, the deposition of two major isomers of CLA (c9, t11; t10, c12) in yolk lipids increased linearly, the proportion of saturated fatty acids increased and monounsaturated fatty acids decreased significantly. The proportion of polyunsaturated fatty acids was highest at 1% CLA. Compared to the control, CLA supplementation significantly increased the activities of superoxide dismutase and glutathione peroxidase, inhibited hydroxyl radicals and superoxide anion production, and decreased the malonaldehyde concentrations in both serum and liver. The results demonstrated that dietary CLA meliorated serum lipid profiles and enhanced the antioxidant capacity of laying hens.     

Detection of Transgenic and Endogenous Plant DNA Fragments and Proteins in the Digesta,Blood, Tissues,and Eggs of Laying Hens Fed with Phytase Transgenic Corn

The trials were conducted to assess the effects of long-term feeding with phytase transgenic corn (PTC) to hens on laying performance and egg quality, and investigate the fate of transgenic DNA and protein in digesta, blood, tissues, and eggs. Fifty-week old laying hens (n = 144) were fed with a diet containing 62.4% PTC or non-transgenic isogenic control corn (CC) for 16 weeks. We observed that feeding PTC to laying hens had no adverse effect on laying performance or egg quality (P>0.05) except on yolk color (P<0.05). Transgenic phyA2 gene and protein were rapidly degraded in the digestive tract and were not detected in blood, heart, liver, spleen, kidney, breast muscle, and eggs of laying hens fed with diet containing PTC. It was concluded that performance of hens fed diets containing PTC, as measured by egg production and egg quality, was similar to that of hens fed diets formulated with CC. There was no evidence of phyA2 gene or protein translocation to the blood, tissues, and eggs of laying hens.     

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.     

Effects of Increasing Supplementation of Magnesium in Diets on Productive Performance and Eggshell Quality of Aged Laying Hens

Magnesium (Mg) concentrations in diets have been associated with performance and eggshell quality of laying hens, but the results have been inconclusive. In this experiment, the effects of increasing concentrations of dietary Mg on productive performance and eggshell quality of aged laying hens were evaluated. A total of 640 Hy-Line Brown laying hens of 72 weeks of age were randomly allotted to one of four dietary treatments with four replicates per treatment. A commercial-type basal diet containing 1.6 g/kg Mg was prepared, and three additional diets were prepared to contain 2.3, 2.6, or 3.0 g/kg Mg in diets by adding 1.0, 1.5, or 2.0 g of MgO to the basal diet. The diets were fed to hens ad libitum for 5 weeks. Results indicated that Mg concentrations in eggshells were increased (linear, P?<?0.01) with increasing concentrations of Mg in diets. Increasing concentrations of Mg in diets decreased (linear and quadratic, P?<?0.01) broken and shell-less egg production, but improved (linear, P?<?0.05) eggshell strength. Feed intake was decreased (linear, P?<?0.05) with the concentrations of Mg in diets, but hen-day egg production, egg weight, feed conversion ratio, and Haugh unit were not affected by increasing concentrations of Mg in diets. Hunter L* and a* values of eggshell were decreased (linear, P?<?0.05) as the concentrations of Mg in diets increased. In conclusion, feeding aged laying hens with diets containing increasing concentrations of Mg up to 3.0 g/kg improves eggshell strength, but has no detrimental effects on laying performance.     

Effect of dietary supplementation of Ligustrum lucidum on performance,egg quality and blood biochemical parameters of Hy-Line Brown hens during the late laying period

The fruit of Ligustrum lucidum (FLL, Nuzhenzi in Chinese) is an important traditional medicine, and have attracted significant research attention because of their various biological activities. However, there are few research reports available on the use of FLL as a feed additive in livestock nutrition, particularly in layers. This study was conducted to determine the effects of supplementation of the diet of laying hens with FLL on laying performance, egg quality and blood metabolites. A total of 360 72-week-old hens were allocated to three dietary treatments (eight replications of 15 hens/treatment group) and were fed either a control diet or a diet supplemented with an inclusion level of 0.25% or 0.50% of FLL powder in the final feed, until 78 weeks of age. Hens were housed in a three-tier cage system. Feed and water were provided ad libitum. Blood samples and eggs were collected at the end of the experiment. The results showed that dietary supplementation with FLL did not affect egg weight, feed conversion ratio, eggshell thickness, albumen height, egg yolk color, eggshell breaking strength or egg shape index. However, FLL supplementation significantly decreased (P<0.001) mortality, cracked-egg rate and blood serum levels of cholesterol, low-density lipoprotein cholesterol, triglycerides and alanine aminotransferase, and increased (P<0.001) blood serum levels of high-density lipoprotein cholesterol. No differences in serum levels of total protein, albumin, glucose, calcium, aspartate aminotransferase or alkaline phosphatase were observed in hens fed FLL compared with the control group. It can be concluded that FLL, at a supplementation level of 0.25% final feed, can be used as an effective feed additive to improve the performance of laying hens during the late laying period.     

Early rearing enrichments influenced nest use and egg quality in free-range laying hens

In Australia, free-range egg production pullets are typically reared indoors, but adult layers get outdoor access. This new environment may be challenging to adapt to, which could impair egg production and/or egg quality. Adaptation might be enhanced through rearing enrichments. We reared 1386 Hy-Line Brown® chicks indoors with three treatments across 16 weeks: (1) a control group with standard litter housing conditions, (2) a novelty group providing novel objects that changed weekly, and (3) a structural enrichment group with custom-designed structures to partially impair visibility across the pen and allow for vertical movement. Pullets were transferred to a free-range system at 16 weeks of age with daily outdoor access provided from 25 until 64 weeks. Daily egg production at different laying locations (large nests, small nests and floor), weekly egg weights and egg abnormalities were recorded from 18 to 64 weeks old. External and internal egg quality parameters of egg weight, shell reflectivity, albumen height, haugh unit, yolk colour score, shell weight and shell thickness were measured at 44, 52, 60 and 64 weeks. There was a significant interaction between rearing treatment and nest box use on hen-day production from weeks 18 to 25 (P < 0.0001) with the novelty hens laying the most eggs and the control hens the fewest eggs in the nest box. Similarly, from 26 to 64 weeks, the novelty hens laid more eggs in the large nest boxes and fewer eggs on the floor than both the structural and control hens (P < 0.0001). Egg weight and abnormalities increased with age (P < 0.0001), but rearing treatment had no effect on either measure (both P ≥ 0.19). Rearing treatment affected shell reflectivity and yolk colour with the control hens showing paler colours across time relative to the changes observed in the eggs from enriched hens. The novelty hens may have established nest box laying patterns as they were more accustomed to exploring new environments. The differences in egg quality could be related to stress adaptability or ranging behaviour. This study shows that enriching environments during rearing can have some impacts on production parameters in free-range hens.     

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.     

Effects of dietary chromium and zinc on egg production, egg quality, and some blood metabolites of laying hens reared under low ambient temperature

This experiment was conducted to evaluate the effects of chromium (chromium picolinate, CrPic) and zinc (ZnSO₄·H₂O) on egg production, egg quality, and serum insulin, corticosterone, glucose, cholesterol, and total protein concentrations of laying hens reared under a low ambient temperature (6.8°C). One hundred twenty laying hens (Hy-Line; 32 wk old) were divided into 4 groups, 30 hens per group. The laying hens were fed the control diet (T1) or the control diet supplemented with either 400 μg of Cr/kg of diet (T2), 30 mg of Zn/kg of diet (T3), or 400 μg of Cr plus 30 mg of Zn/kg of diet (T4). Although the dry matter intake (DMI) was similar (p>0.05) for all treatment groups, supplemental chromium and zinc either individually or together increased live-weight change, egg production, and improved feed efficiency (p<0.05). However, no significant differences were observed between T4 and T2 or T3. Compared to T1, supplemental chromium and zinc increased egg weight, eggshell weight, eggshell thickness, egg specific gravity, and Haugh unit (p<0.05) in T2, T3, and T4 groups, among which there was no significant difference. Serum insulin concentration increased (p<0.05) and corticosterone concentration decreased (p<0.05) with dietary chromium and zinc supplementation. Serum glucose and cholesterol concentrations decreased (p<0.05) and protein concentrations increased (p<0.001) with dietary chromium and zinc supplementation in all treatment groups. The results of this study indicated that either supplemental dietary chromium or zinc increased plasma insulin and decreased corticosterone concentrations and that had a positive effect on performance of laying hens under low ambient temperature.     

Effects of enzyme-treated soy protein on performance,digestive enzyme activity and mRNA expression of nutrient transporters of laying hens fed different nutrient density diets

It has been shown that enzyme-treated plant protein can increase performance and promote intestinal health, and save dietary protein. However, our understanding of the effects of enzyme-treated soy protein on performance and intestine function in laying hens, and its rational use, remains limited. The experiment was conducted to study the effect of enzyme-treated soy protein (ETSP) in different nutrient density diets on performance, egg quality, digestive enzyme activity and mRNA expression of amino acid transporters of laying hens. A total of 1 200 Lohmann laying hens (52 wk of age) was randomly divided into a 3 × 2 factorial design that included three nutrient levels: [positive control (PC), metabolisable energy (ME): 2 680 kcal/kg, CP: 15.5%; negative control 1 (NC1), ME: 2 630 kcal/kg, CP: 15%; negative control 2 (NC2), ME:2 580 kcal/kg, CP: 14.5%] and 2 ETSP levels (0 and 0.5%) for 12 weeks. Each treatment had 10 replicates with 20 birds. With the decrease of dietary nutrition density, egg production rate (P = 0.07) and feed conversion ratio (FCR) (P = 0.06) were reduced. Yolk colour was decreased, and yolk index was increased. Supplemented ETSP improved FCR (P = 0.05) and qualified egg rate (P < 0.05). The mass loss rate of egg was decreased after storage for 30 days (P < 0.05). An interaction between nutrient density and ETSP was observed on albumen height and Haugh unit (P < 0.05), and the effects were most noticeable in hens fed 0.5% ETSP in NC2 group. An increase in the activity of trypsin in duodenum (P < 0.05) and the relative expressions of jejunum peptide transporter 1 (PepT1) (P < 0.05) and B⁰ system neutral amino acid transport carrier (B⁰AT) mRNA (P < 0.01) was observed during ETSP supplementation. The nutrient density and ETSP supplementation had no significant effect on microbiota in the cecal contents. Overall, the results in this study indicated that the ME decreased 100 kcal/kg and CP decreased 1% in diet of laying hens had a decreasing trend on production performance, no effects on enzyme activity, amino acid transporter mRNA, and gut microbiota, whereas 0.5% ETSP can increase activity of trypsin, PepT1 and B⁰AT mRNA relative expressions, and improve FCR, qualified egg rate.     

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.     

Melamine in eggs,plasma and tissues of hens fed contaminated diets

A study was conducted to evaluate the excretion pattern of melamine from feed into eggs, plasma, kidney, liver and muscle of laying hens. In particular, 90 laying hens were randomly allocated to three dietary treatments and fed diets contaminated with melamine at a level of 2.5, 25 and 250 mg of melamine/kg of diet for T1, T2 and T3 groups, respectively. The diets were offered in six replicate boxes (five hens each) for 13 days. Eggs were collected from each group for melamine quantification on days 0, 1, 3, 6, 9 and 13. At the end of the experimental period, one hen per box was randomly selected and slaughtered to collect plasma, liver, kidney and muscle samples. During the experiment, feeding diets with increasing levels of melamine had no effect (P > 0.05) on weight gain, feed intake, egg production, egg weight and mortality of laying hens. The melamine in eggs increased from day 1 after melamine ingestion and reached a plateau between days 6 and 13 of melamine ingestion. At steady-state condition, the melamine egg concentrations increased (P < 0.01) with treatments, being 0.026, 0.352 and 4.631 mg/kg for T1, T2 and T3, respectively. Similarly, the carryover of melamine from feed to egg increased (P < 0.05) with the levels of melamine in the diets, varying from 0.50 to 0.70 and 0.84 for T1, T2 and T3, respectively. The melamine was detected in plasma of all tested groups, increasing (P < 0.01) with levels of melamine in the diets (0.030, 0.266 and 4.102 mg/l in T1, T2 and T3, respectively). Melamine was not detected in kidney, liver and muscle of hens fed T1. Except for kidney sampled in the T3, no melamine concentration higher than 2.5 mg/kg, representing the maximum allowable limit set by the US Food and Drug Administration and European Union for food and feeds, was measured. The melamine resulted higher in plasma and kidneys than in the liver and muscle both in T2 and T3. The results confirmed the presence of an excretion pattern of melamine from feed to eggs and tissues in laying hens.     

Effect of dietary Ptecticus tenebrifer powder on the fatty acid profile of egg yolk in laying hens

The poultry industry needs alternative feeds with no adverse effects on animal performance and egg quality. Insects represent effective animal feeds. However, Ptecticus tenebrifer (PT) has rarely been studied as an effective feed in terms of fatty acid contents. Therefore, we investigated the effect of dietary PT powder on the fatty acid profiles of egg yolks in laying hens. A total of 180 Hy-Line brown hens were divided equally into three groups (n = 60), with three replicates: the control group and two groups fed 2% and 4% PT powder, respectively. After 2 weeks, minor effects (P < 0.05) on oleic acid, dihomo-gamma-linolenic acid, and total monounsaturated fatty acids were observed among the groups. After 4 weeks, docosahexaenoic acid, docosapentaenoic acid, myristic acid, oleic acid, and total polyunsaturated fatty acids were slightly altered in the treatment groups (P < 0.05). For other fatty acids, the 2% and 4% PT groups had fatty acid concentrations similar to those of the controls. No differences in total n-6 and total n-3 were observed among the groups. In conclusion, using 2% and 4% PT powders did not notably change the fatty acid profiles of egg yolks and could replace some layer-hen feed without negative effects.     

Daily energy expenditure and water turnover in two breeds of laying hens kept in floor housing

Laying hens are increasingly kept in barn or free-range systems, which not only allows birds to move freely but also potentially entails higher energy expenditures due to higher locomotor activity. Therefore, the aim of our study was to quantify the daily energy expenditure (DEE) and water turnover in freely moving laying hens. For that purpose, 10 Lohmann Selected Leghorn (LSL) and 10 Lohmann Brown (LB) hens were obtained from a conventional breeding company at 17 weeks of age. The trial started when birds reached an age of 34 weeks. All 20 birds were kept together in the same littered floor pen (12.1 m²). The pen was equipped with perches, a nest box, feeding and nipple drinkers. The DEE was determined individually for all experimental birds (n = 20) for a total of nine days using the doubly labelled water (DLW) method. Lohmann Brown hens were heavier than LSL hens, but laying rate did not differ between the two breeds, that is, one egg per hen and day during the study period. Average egg mass was 63.1 ± 0.20 g in LB and 61.7 ± 0.12 g in LSL hens, which converted to an egg energy content of 420 and 410 kJ/egg, respectively. Dilution spaces for oxygen and hydrogen differed between the breeds but not the respective turnover rates. Total body water as a percentage of body mass (LB: 54.4%, LSL: 53.8%; SEM = 0.7, F_1,18 = 0.41, P = 0.513) and total water intake (TWI) per day (LB: 275 ml/day, LSL: 276 ml/day; SEM = 20, F_1,17 = 0, P = 0.994) did not differ between LB and LSL hens. Individual DEE increased with body mass in LB but not in LSL hens. Average DEE did not differ between the two breeds (LB: 1 501 kJ/day; LSL: 1 520 kJ/day; SEM = 32.1, F_1,17 = 2.54, P = 0.131). However, when comparing the DEE on a metabolic mass basis, LSL hens expended with 984 kJ/kg^0.75 on average significantly more energy per day than LB hens (895 kJ/kg^0.75; SEM = 20.3, F_1,18 = 10.1, P = 0.005). Our results suggest that the DLW technique is a viable method to measure the energy expenditure and water turnover over several days in laying hens. Furthermore, we show that laying hens kept in floor pens fit into the general pattern of DEE among wild birds.     

Interactive effects of vitamins A and K3 on laying performance,egg quality,tibia attributes and antioxidative status of aged Roman Pink laying hens

Extending laying cycle is a tendency in hen breeding, but egg quality declines as laying hens age. The present study was conducted to investigate the interactive effects of vitamins A and K₃ on laying performance, egg and tibia quality, and antioxidative status of aged Roman Pink laying hens. In a 3 × 3 factorial arrangement, 1 080 87-week-old laying hens were allocated to nine groups with eight replicates in each group. Deficient, adequate and excess vitamins A (0, 7 000 and 14 000 IU/kg) and K₃ (0, 2.0 and 4.0 mg/kg) were supplemented into a basal diet with 1 320 IU/kg of vitamin A and 0.5 mg/kg of vitamin K₃. After 2 weeks of adaption to basal diet, hens were fed corresponding diets for 8 weeks. Vitamins A and K₃ did not significantly affect the laying performance. However, they showed interactive effects on yolk ratio at week 93 as well as tibia weight and diameter (P < 0.05), and hens fed deficient vitamins A and K₃ had the highest yolk ratio and tibia weight, but the lowest tibia diameter. Compared with deficient addition, adequate or excess vitamins A and K₃ increased yolk color at weeks 93 and 97 (P < 0.05). Compared with hens fed deficient or excess vitamins, hens fed adequate vitamins A and K₃ had higher eggshell strength at week 93 or 97 (P < 0.05). Increasing vitamin A elevated plasma total superoxide dismutase (T-SOD) activity and decreased hepatic glutathione peroxidase (GSH-Px) activity (P < 0.05). Excess vitamin K₃ increased hepatic T-SOD activity (P < 0.05). Vitamins A and K₃ exhibited interaction on the activities of antioxidative enzymes in eggshell gland (P < 0.05), and adequate or excess vitamins A and K₃ increased the activities of GSH-Px, T-SOD and catalase (CAT). Adequate and excess vitamin A up-regulated the mRNA expression of GSH-Px1, GSH-Px3 and SOD1 in eggshell gland (P < 0.05). Vitamins A and K₃ showed interactive effects on CAT mRNA expression in eggshell gland (P < 0.05) and hens fed adequate vitamins A and K₃ had the highest CAT mRNA levels. In conclusion, dietary addition of vitamins A and K₃ improved the eggshell quality and yolk color as well as antioxidative status in eggshell gland of aged laying hens. Adequate vitamins A and K₃ showed beneficial effects and excess levels did not exhibit superior effects.     

Effects of feeding transgenic corn with mCry1Ac or maroACC gene to laying hens for 12 weeks on growth,egg quality and organ health

The objective of the present study was to investigate the effect of feeding two transgenic corn lines containing the mCry1Ac gene from Bacillus thuringiensis strain (BT-799) and the maroACC gene from Agrobacterium tumefaciens strain (CC-2), respectively, on growth, egg quality and organ health indicators. Expression of the mCry1Ac gene confers resistance to Pyrausta nubilalis and the maroACC gene confers tolerance to herbicides. Healthy hens (n=96 placed in cages; 3 hens/cage) were randomly assigned to one of four corn–soybean meal dietary treatments (8 cages/treatment) formulated with the following corn: non-transgenic near-isoline control corn (control), BT-799 corn, CC-2 corn and commercially available non-transgenic reference corn (reference). The experiment was divided into three 4-week phases (week 1 to 4, week 5 to 8 and week 9 to 12), during which hens were fed mash diets. Performance (BW, feed intake and egg production) and egg quality were determined. Following slaughter at the end of 12 weeks of feeding (n=8/treatment), carcass yield and organ weights (heart, liver, spleen, lung, kidneys, stomach and ovary) were recorded; organs and intestines were sampled for histological analysis. Analysis of serum biochemistry parameters to assess the liver and kidney function were performed. No differences in BW, egg production and production efficiency were observed between hens consuming the control diet and hens consuming the BT-799 or CC-2 diet. Haugh unit measures and egg component weights were similar between the control and test groups. Carcass yield was not affected by the diet treatment. Similar organosomatic indices and serum parameters did not indicate the characteristics of organ dysfunction. All observed values of the BT-799 and CC-2 groups were within the calculated tolerance intervals. This research indicates that the performance, egg quality, organ health and carcass yield of laying hens fed diets containing the BT-799 or CC-2 corn line were similar to that of laying hens fed diets formulated with the non-transgenic near-isoline corn with comparable genetic backgrounds.