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.     

Effect of Diets Supplemented with Different Levels of Manganese,Zinc, and Copper from their Organic or Inorganic Sources on Egg Production and Quality Characteristics in Laying Hens

This experiment was conducted to evaluate the effect of zinc, manganese, and copper sources (inorganic vs. organic) in the diet on laying performance and eggshell quality characteristics. One hundred and eighty Hy-Line W-36 layers at 38 weeks of age were allocated to 36-layer cages of five hens each. Each six cages were randomly assigned to one of the six experimental diets fed from 38 to 53 week of age. In three experimental treatments, the basal diet was supplemented with 65–75–7 or 65–75–7 or 40–40–7 mg/kg of Zn, Mn, and Cu, respectively, from their oxide or sulfate sources. Three other groups were fed diets supplemented with 20–20–3.5 or 40–40–7.5 or 60–60–10.5 mg/kg of organic forms of Zn, Mn, and Cu, respectively. Dietary treatments significantly did affect feed intake (P < 0.001), feed conversion ratio (P < 0.001) and percentage of broken eggs (P < 0.05). Substitution of Zn and Mn oxides (65 and 75 mg kg⁻¹, respectively) with equal amounts of their sulfate forms significantly improved feed intake, feed conversion ratio, percentage of broken eggs, and Haugh Unit (P < 0.05). In addition, laying hens maintained their performance when substitution of Zn and Mn oxides and Cu sulfate (65, 75, and 7 mg kg⁻¹, respectively) reduced up to 20, 20, and 3.5 mg kg⁻¹ by amino acid complexes of the microelements. The results showed that a corn–soybean diet supplemented with the organic forms of Zn, Mn, and Cu at a dosage 50% to 75% lower than NRC recommendation is sufficient to maintain laying performance and can improve eggshell and albumen qualities of the egg in 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.     

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 paradoxical effects of progesterone on the eggshell quality of laying hens

This study demonstrates the effects of progesterone on eggshell quality and ultrastructure by injecting progesterone into laying hens 2 and 5 h post-oviposition, respectively. Progesterone injected 2 h post-oviposition (P₄-2 h) improved eggshell quality with a significant decrease (P < 0.01) in the thickness of the mammillary layer and a significant increase (P < 0.01) in the thickness of the effective layer in the eggshell ultrastructure compared to the control. Progesterone injected 5 h post-oviposition (P₄-5 h) damaged the eggshell quality by significantly reducing (P < 0.01) the effective layer thickness. Progesterone injected delayed obviously (P < 0.01) the following oviposition. Moreover, the concentrations of Thr, Cys, Leu, Lys, and His in the eggshell membranes were significantly higher (P < 0.05) in the P₄-2 h treated hens whereas Val and Lys were significantly lower (P < 0.05) in P₄-5 h treated hens compared to the control. Therefore, progesterone shows paradoxical effects on eggshell quality depending on the injection time-points post-oviposition, which could explain the contradictions in previous related reports. P₄ injected affected the content of amino acids in eggshell membranes, especially lysine which contributed to eggshell quality. In addition, P₄ injected 2 h after oviposition improved eggshell quality by promoting the premature fusion of mammillary knobs. This work contributed to a novel insight to understanding the mechanism of improving eggshell quality.     

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.     

Dietary supplementation with sodium bicarbonate or sodium sulfate affects eggshell quality by altering ultrastructure and components in laying hens

Dietary sodium (Na) levels were related to the content of the eggshell matrix. We therefore speculated that dietary Na supplementation as sodium bicarbonate (NaHCO₃) or sodium sulfate (Na₂SO₄) may improve eggshell quality. Additionally, dietary NaHCO₃ or Na₂SO₄ supplementation may further affect eggshell quality in different ways due to differences in anions. This study investigated and compared the effects of dietary Na supplementation in either NaHCO₃ or Na₂SO₄ form on laying performance, eggshell quality, ultrastructure and components in laying hens. A total of 576 29-week-old Hy-Line Brown laying hens were randomly allocated to 8 dietary treatments that were fed a Na-deficient basal diet (0.07% Na, 0.15% Cl) supplemented with Na₂SO₄ or NaHCO₃ at 0.08, 0.18, 0.23 or 0.33% Na for 12 weeks. No differences were observed in laying production performance with dietary Na supplementation. Dietary Na supplementation resulted in quadratic increases of eggshell breaking strength in both Na₂SO₄ and NaHCO₃ added groups (P < 0.05), and Na₂SO₄-fed groups had a quadratic increase in the eggshell ratio at week 12 (P < 0.05). Compared with supplementing 0.08% Na, dietary supplementation of 0.23% Na increased the effective thickness (P < 0.05) in both Na₂SO₄ and NaHCO₃ added groups, but decreased the thickness and knob width of the mammillary layer (P < 0.05). A linear increase on the calcium content of the shell was only observed with Na supplementation from NaHCO₃ (P < 0.05). No differences were observed in Na contents of the shell with dietary Na supplemented by both sources. Dietary Na addition had a quadratic increase on uronic acid contents of shell membrane in NaHCO₃-fed groups (P < 0.05). Moreover, the sulfated glycosaminoglycan (GAG) contents of shell membranes increased linearly with dietary Na supplementation (P < 0.05). Dietary supplementation of 0.23% Na from Na₂SO₄ increased the sulfated GAG contents of calcified eggshell (P < 0.05). Additionally, compared with NaHCO₃-fed groups, Na₂SO₄-fed groups had higher eggshell breaking strength, thickness, eggshell weight ratio, effective thickness and the sulfated GAG contents of calcified eggshell at week 12. Overall, dietary supplementation of NaHCO₃ or Na₂SO₄ could increase eggshell breaking strength, which may be related to increased sulfated GAG contents in eggshell membranes and improved ultrastructure. Higher eggshell breaking strength, thickness and eggshell ratio could be obtained when the diet was supplemented with 0.23% Na from Na₂SO₄.     

Effects of dietary Bacillus subtilis and inulin supplementation on performance,eggshell quality,intestinal morphology and microflora composition of laying hens in the late phase of production

Eighty Lohmann White laying hens were used to investigate the effect of dietary inclusion of Bacillus subtilis and inulin, individually or in combination, on egg production, eggshell quality, tibia traits, Ca retention, and small intestine morphology and microflora composition from 64 to 75 weeks of age. Hens were randomly distributed into 4 treatment groups, with 5 replicates per treatment and 4 hens per replicate. Treatment groups were fed basal diet (control), basal diet plus 1 g/kg B. subtilis (2.3 × 10⁸ cfu/g), basal diet plus 1 g/kg inulin, or basal diet plus a synbiotic combination of 1 g/kg B. subtilis (2.3 × 10⁸ cfu/g) and 1 g/kg inulin. Dietary supplementation of B. subtilis, inulin or synbiotic improved (P<0.05) feed conversion, egg performance, eggshell quality and calcium retention compared with the control. B. subtilis and synbiotic groups exhibited the highest (P<0.05) increase in egg production and egg weight. Inulin and synbiotic groups exhibited the highest (P<0.05) increase in eggshell thickness and eggshell calcium content, and the lowest (P<0.05) eggshell deformations. Unmarketable eggs were 8.4% (P<0.05) of the total eggs produced by the control group compared to 3.5%, 1.7%, and 1.5% for the B. subtilis, inulin and synbiotic groups, respectively. Tibia density, ash, and Ca content increased (P<0.05) by inulin and synbiotic inclusions, compared with the control. B. subtilis, inulin, and their synbiotic combination increased (P<0.05) villus height and crypt depth in all intestinal segments, compared with the control. B. subtilis and inulin modulated the ileal and caecal microflora composition by decreasing (P<0.05) numbers of Clostridium and Coliforms and increasing (P<0.05) numbers of bifidobacteria and lactobacilli, compared with the control. Colonization of the beneficial microflora along with increasing the villi–crypts absorptive area were directly associated with the improvements in performance and eggshell quality. It can be concluded that egg production and eggshell quality of laying hens can be improved (P<0.05) in the late phase of production by dietary inclusion of B. subtilis and inulin.     

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.     

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 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.     

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 probiotic supplementation on performance traits,bone mineralization,cecal microbial composition,cytokines and corticosterone in laying hens

Recent researches have showed that probiotics promote bone health in humans and rodents. The objective of this study was to determine if probiotics have the similar effects in laying hens. Ninety-six 60-week-old White Leghorn hens were assigned to four-hen cages based on their BW. The cages were randomly assigned to 1 of 4 treatments: a layer diet mixed with a commercial probiotic product (containing Enterococcus faecium, Pediococcus acidilactici, Bifidobacterium animalis and Lactobacillus reuteri) at 0, 0.5, 1.0 or 2.0 g/kg feed (Control, 0.5×, 1.0× and 2.0×) for 7 weeks. Cecal Bifidobacterium spp. counts were higher in all probiotic groups (P<0.001) compared with the control group. The percentage of unmarketable eggs (cracked and shell-less eggs) was decreased in both 0.5× and 2.0× groups compared with the control group (P=0.02), mainly due to the reduction of shell-less eggs (P=0.05). The increases in tibial and femoral mineral density and femoral mineral content (P=0.04, 0.03 and 0.02, respectively), with a concomitant trend of increases in humerus mineral density and tibial mineral content (P=0.07 and 0.08, respectively), occurred in the 2.0× group. However, the bone remodeling indicators of circulating osteocalcin and c-terminal telopeptide of type I collagen were similar among all groups (P>0.05). In addition, the plasma concentrations of cytokines (interleukin-1β, interleukin-6, interleukin-10, interferon-γ and tumor necrosis factor-α) and corticosterone as well as the levels of heterophil to lymphocyte ratio were similar between the 2.0× group and the control group (P>0.05). In line with these findings, no differences of cecal tonsil mRNA expressions of interleukin-1β, interleukin-6 and lipopolysaccharide-induced tumor necrosis factor-α factor were detected between these two groups (P>0.05). These results suggest that immune cytokines and corticosterone may not involve in the probiotic-induced improvement of eggshell quality and bone mineralization in laying hens. In conclusion, the dietary probiotic supplementation altered cecal microbiota composition, resulting in reduced shell-less egg production and improved bone mineralization in laying hens; and the dietary dose of the probiotic up to 2.0× did not cause negative stress reactions in laying hens.     

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.     

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.     

Effects of the different levels of dietary trace elements from organic or inorganic sources on growth performance,carcass traits,meat quality,and faecal mineral excretion of broilers

ABSTRACT

This experiment was conducted to evaluate the effects of different sources and levels of trace elements on growth performance, carcass composition and mineral excretion levels of broilers. In a completely randomised experimental design, 900 one-day-old male Ross-308 broilers were assigned to 5 treatments, with 6 replicates of 30 birds each. The control group (CITE) was fed with a basal diet containing regular inclusion levels of inorganic trace elements. Treatment groups were supplied with reduced levels (30% and 50% of the regular level) of inorganic (ITE) or organic trace elements (OTE), respectively. Groups 50% ITE, 30% OTE and 50% OTE diets had equivalent average daily gain (ADG), average daily feed intake (ADFI), feed to gain ratio (F/G ratio) and mortality rate compared with group CITE in any phase. However, compared with group CITE chicks in group 30% ITE have lower ADG and ADFI and higher F/G ratio. The carcass yields were not affected by dietary treatments. Compared with group CITE, in groups 30% ITE, 50% ITE, 30% OTE and 50% OTE the shear force values of the breast muscle were only 71.8%, 83.4%, 63.5% and 59.4% (p < 0.05), respectively. Birds received diets containing reduced levels of trace elements had diminished excretions of Mn and Zn throughout the entire period (p < 0.01). In conclusion, the reduced supplementation of trace elements had no or slightly negative impact on growth performance, carcass yield and meat quality, but decreased faecal mineral excretion. Moreover, the trace element supply as OTE played a limited role on performance and excretion and was only partly beneficial for animal performance in case the trace element supply was reduced to 30%.     

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.     

Welfare of organic laying hens kept at different indoor stocking densities in a multi-tier aviary system. I: egg laying,and use of veranda and outdoor area

Multi-tier aviary systems are becoming more common in organic egg production. The area on the tiers can be included in the net area available to the hens (also referred to as usable area) when calculating maximum indoor stocking densities in organic systems within the EU. In this article, results on egg production, laying behaviour and use of veranda and outdoor area are reported for organic laying hens housed in a multi-tier system with permanent access to a veranda and kept at stocking densities (D) of 6, 9 and 12 hens/m² available floor area, with concomitant increases in the number of hens per trough, drinker, perch and nest space. In a fourth treatment, access to the top tier was blocked reducing vertical, trough and perch access at the lowest stocking density (treatment D6x). In all other aspects than stocking density, the experiment followed the EU regulations on the keeping of organic laying hens. Laying percentage was significantly lower (P<0.05) in D12 compared with the other stocking densities (90.6% v. 94.3% (±0.7)), most likely due to the concomitant reduction in nest space and drinker availability per hen. No systematic effects of density were found on other laying variables (egg weight, eggs laid outside nests, aviary side preferences). Number of hens using the veranda increased with stocking density. Hens primarily used the range near the house (within 50 m) and hens kept at the lowest stocking density and the smallest group size appeared to use the outdoor area more extensively, based on an assessment of vegetation cover (P<0.05). For the measures reported here, the welfare consequences of increased stocking density were assessed to be minor; additional results are reported in the associated article (Steenfeldt and Nielsen, 2015).     

Effect of inorganic phosphate supplementation on egg production in Hy-Line Brown layers fed 2000 FTU/kg phytase

Phytase has long been used to decrease the inorganic phosphorus (Pi) input in poultry diet. The current study was conducted to investigate the effects of Pi supplementation on laying performance, egg quality and phosphate–calcium metabolism in Hy-Line Brown laying hens fed phytase. Layers (n = 504, 29 weeks old) were randomly assigned to seven treatments with six replicates of 12 birds. The corn–soybean meal-based diet contained 0.12% non-phytate phosphorus (nPP), 3.8% calcium, 2415 IU/kg vitamin D₃ and 2000 FTU/kg phytase. Inorganic phosphorus (in the form of mono-dicalcium phosphate) was added into the basal diet to construct seven experimental diets; the final dietary nPP levels were 0.12%, 0.17%, 0.22%, 0.27%, 0.32%, 0.37% and 0.42%. The feeding trial lasted 12 weeks (hens from 29 to 40 weeks of age). Laying performance (housed laying rate, egg weight, egg mass, daily feed intake and feed conversion ratio) was weekly calculated. Egg quality (egg shape index, shell strength, shell thickness, albumen height, yolk colour and Haugh units), serum parameters (calcium, phosphorus, parathyroid hormone, calcitonin and 1,25-dihydroxyvitamin D), tibia quality (breaking strength, and calcium, phosphorus and ash contents), intestinal gene expression (type IIb sodium-dependent phosphate cotransporter, NaPi-IIb) and phosphorus excretion were determined at the end of the trial. No differences were observed on laying performance, egg quality, serum parameters and tibia quality. Hens fed 0.17% nPP had increased (P < 0.01) duodenum NaPi-IIb expression compared to all other treatments. Phosphorus excretion linearly increased with an increase in dietary nPP (phosphorus excretion = 1.7916 × nPP + 0.2157; R² = 0.9609, P = 0.001). In conclusion, corn–soybean meal-based diets containing 0.12% nPP, 3.8% calcium, 2415 IU/kg vitamin D₃ and 2000 FTU/kg phytase would meet the requirements for egg production in Hy-Line Brown laying hens (29 to 40 weeks of age).