Improve Egg Shell Quality Research Articles

Evaluation of Egg Quality and Performance in Late-Lay Hens Fed Different Combinations of Copper, Manganese, and Zinc Complexed with Sulfate or Amino Acid Ion

Dietary inclusion of copper (Cu), manganese (Mn), and zinc (Zn) can improve egg shell quality through changing the membrane structure. This study aimed to compare the responses of egg shell to different mineral sources. In this study, 60-week-old laying hens (n = 378) were assigned to one of seven treatments with 18 replicates each in an RCBD. Treatments included the following: control (basal + sulfated minerals (CuSO4, MnSO4, and ZnSO4)), and basal + amino acid complexed (AAC) minerals (AAC Cu, AAC Mn, AAC Zn, AAC Cu + Mn, AAC Mn + Zn, AAC Zn + Cu). Trace minerals were added to a basal diet containing 20 ppm MnSO4 and 20 ppm ZnSO4 to achieve overall target concentrations of 20 ppm Cu, 60 ppm Mn, and 60 ppm Zn. The hens were fed the treatment diet for 15 weeks, and egg production and egg quality were assessed during weeks 5, 10, and 15 of the experiment. Egg shells, egg contents, and excreta were analyzed for Cu, Mn, Zn, Ca, and P during weeks 10 and 15. No treatment differences (p > 0.05) were observed for production or egg quality. Differences between excreta mineral content were observed. The mineral content of egg shells and egg contents did not differ (p > 0.05) at any time point. The mineral source did not affect egg mineral deposition and egg quality measures (p > 0.05). Some AAC trace minerals enhanced retention of zinc, calcium, and manganese, although AAC Cu increased Cu excretion. Taken together, feeding AAC trace minerals does not significantly affect egg production or egg quality during the late-lay period. More research is needed to demonstrate whether Cu excretion is increased when feeding AAC Cu due to increased bioavailability or other factors.

Effects of Zinc, Manganese, and Taurine on Egg Shell Microstructure in Commercial Laying Hens After Peak Production.

Much strive has been made to improve egg shell quality in laying hens. This study was conducted to evaluate the effects of two microminerals, zinc and manganese, besides taurine semi-essential amino acid on eggshell quality after peak production of Hy-line laying hens. A total of 720 laying hens were assigned to 18 treatments in a completely randomized design (3 × 3 × 2 factorial) at week 71. Experimental period included 8-week adaptation and using 18 dietary treatments for about 6weeks. Dietary treatments included Zn (0, 80, and 160mg/kg), Mn (0, 90, and 180mg/kg), and taurine (0 and 1960mg/kg). Supplementation of 90mg Mn and 1960mg taurine in laying hens' diet after peak of production improved egg shell quality without any negative effect on the internal quality of the egg. Egg specific gravity significantly increased in response to Zn, Mn, and taurine in comparison with control treatment (P < 0.05). Applying 1960mg taurine/kg diet significantly improved calcite crystal's structure and eggshell strength in comparison with control treatment (P < 0.05). It was concluded that adding Mn and taurine can positively affect eggshell quality of laying hens post peak period.

The effects of dietary calcium and phosphorus level, and feed form during rearing on growth performance, bone traits and egg production in brown egg-type pullets from 0 to 32 weeks of age

In a 3 × 2 factorial arrangement, effects of feed form (crumbles (CWS), mash (MWS), both with inclusion of 3% finely ground wheat straw, or crumbles with inclusion of 3% oat hulls (COH)), and dietary Ca and P (high and low Ca-P) from 0 to 16 wk of age were studied on growth performance, bone characteristics, and gizzard development of egg-type pullets. The cross-over effect of feeding strategy during rearing on laying performance and egg shell quality was studied from 19 to 32 wk of age. From 0 to 16 wk, ADG, ADFI, and feed conversion ratio (FCR) were improved with CWS and COH compared to MWS, but ADG and FCR were improved with MWS compared to CWS and COH from 11 to 16 wk. Uniformity of BW till 11 wk, and tibia breaking strength at 6 and 16 wk were higher with CWS and COH compared to MWS. Tibia ash content at 11 wk and relative empty proventriculus + gizzard weight (EPG) were lower with CWS and COH compared to MWS, also relative EPG at 11 and 16 wk was higher with COH compared to CWS. At 25 wk BW was lower with MWS compared to CWS and COH, but BW was equal for all treatments at 32 wk. The FCR for egg production was improved with COH compared to MWS. Egg shell parameters were not affected by feed form during rearing. Low Ca-P decreased BW uniformity at 6 wk, relative keel bone weight and ash content at 11 wk, tibia ash content at 11 and 16 wk, increased relative EPG at 6 wk, and improved egg shell quality at 32 wk of age. It was concluded that feeding CWS and COH compared to MWS increased growth performance, but had no clear cross-over effect on egg production. Low dietary Ca-P led to a lower bone mineralization during rearing, nevertheless improved egg shell quality at 32 wk.

INFLUENCES OF CALCIUM LEVELS WITH LIMESTONE PARTICLE SIZE ON LAYING PERFORMANCE , AND EGGSHELL QUALITY TRAITS OF LAYERS

The current study estimated the influences of nutritive calcium levels besides limestone particle size upon performance , egg production and egg quality in first-cycle of Golden Montazah layers. Experimental scheme was completely randomized in 3x4 factorial arranging (three Ca levels – 2.8, 3.0 or 3.2%, in addition four particle size distributions – (100% , 50% fine plus 50% coarse , 25% F and 75% C, or 100% ) Totalizing 12 treatments including three replicates with eight birds each. Limestone size was ranged from fine (F >0.6 mm) to coarse ( 1.9 <.C < 2.8 mm). There was a significant influence of dietary calcium levels with particle sizes or the interaction between the two influences on feed intake (g/hen/day ), egg production % , calcium intake and feed conversion. Particles of limestone were significant effect on eggshell quality including density , shell breaking strength, thickness, eggshell (%) as well as EWSA . Eggshell breaking strength was enhanced when replacing fine limestone by 75% and 100% of coarser limestone substitutions . Shell thickness was significantly higher in 3 or 3.2% Ca groups compared with 2.8% Ca group. The main effect of Limestone particles size generally improved egg shell quality with increasing coarsity inclusion level. Limestone particle size significantly affected internal egg quality traits. Regardless of calcium levels , while limestone particle size is consider , best performance results of egg production, eggshell quality plus some of internal egg quality were obtained by replacing fine limestone by 75% and 100% of coarser limestone particle size . In conclusion, the addition of calcium at level (3.0 - 3.2%) with supplying of coarse limestone (1.9mm< C <2.8mm) by 75 - 100% improves the performance of laying hen

Egg Shell Quality and Bone Status as Affected by Environmental Temperature, Ca and Non-Phytate P Intake and in vitro Limestone Solubility in Single-Comb White Leghorn Hens

Environmental temperature (ET) often changes the nutrient intake/output for layers. Changing feed formulations based on ET may need to be utilized to obtain optimum performance, shell quality and bone status. This study was conducted to investigate the effects of temperature, Ca intake, non-phytate P (NPP) intake and in vitro limestone solubility (LS) on egg-shell quality and bone status in commercial White Leghorn hens. Egg mass and shell weight per unit surface area (SWUSA) decreased with increasing ET (p lower than 0.05), especially when ET was 29.7 C (cycling mean ET)or a constant ET was 32.2 C. Feeding layers a low soluble larger particle size limestone instead of a highly soluble limestone produced beneficial effects for SWUSA at the thermoneutral ET (21.1 C) but the beneficial effect was less or disappeared when ET was higher than 26.6 C in EXP 1 and 2. Feeding layers 245 and 353 mg NPP/h/d supported satisfactory bone status at 21.1 C, however layers housed at higher than 30 C needed an additional intake of 50 mg NPP/h/d to support bone integrity. Results of EXP 1 and 2 indicates that 48 week old layers housed in thermoneutral or warmer ET require a minimum of 4.2 g Ca/h/d for maintaining optimum shell quality and bone integrity. Feeding low LS (34.1% in vitro solubility) improved egg shell quality only for hens housed in thermoneutral ET (21.1 C) and did not improve egg shell quality at higher ET (constant or cycling). Daily NPP intake of 245 and 353 mg/h/d supported optimum egg production and bone status at 21.1 C, respectively. A higher NPP and Ca intake may be required for bone status compared to egg production, especially in older hens.

Synergetic effects of essential oils mixture improved egg quality traits, oxidative stability and liver health indices in laying hens fed fish oil

Omega-3 fatty acids are necessary for human health, although products containing higher proportions of these fatty acids make them more susceptible to lipid peroxidation. The current study was conducted to evaluate the synergetic effects of dietary supplementation of herbal essential oils mixture (Thymus vulgaris, Mentha piperita, Rosmarinus officinalis and Anethum graveolens) and dietary fat sources on egg quality traits, oxidative stability and liver health indices of laying hens. A total of 150 laying hens were randomly distributed among 6 experimental treatments with five replicates of five birds each. Dietary treatment consisted of three levels of herbal essential oils mixture (0, 100 and 200mg/kg) and two sources of fat (fish oil and soybean oil containing different ratios of n-6 to n-3 fatty acids) that fed during an 80 d feeding trial. The results showed that administrating fish oil, containing low ratio of n-6 to n-3 fatty acids, enhanced liver (P<0.05) malondialdehyde concentration, egg yolk color (P<0.05), and led to the reductions in liver relative weight, hepatic lipid percentage (P<0.05), serum alkaline phosphatase activity (P<0.01), as well as serum and egg yolk cholesterol contents (P<0.05). Moreover, herbal essential oils mixture resulted in the declines in blood cholesterol and triglyceride concentrations (P<0.01), enzymes activity of alanine aminotransferase and aspartate aminotransferase (P<0.01), as well as hepatic and serum malondialdehyde concentrations (P<0.05). Also, it caused the improvements in eggshell hardness and thickness (P<0.05). In general, the findings indicated that although dietary administration of fish oil increased the susceptibility of serum and liver to lipid peroxidation, feeding 200mg/kg essential oils mixture resulted in the best systemic and hepatic antioxidant responses, the modulated serum lipid profiles, and also the improved eggshell quality.

Evaluating the Effects of Salicornia Extract on Performance, Egg Quality and Blood Profile of Laying Hens

The current experiment was conducted to evaluate the effects of adding Salicornia extract to the drinking water on the performance, egg quality, and blood profile of laying hens. A total of 216 Hy-Line Brown laying hens at 40 weeks of age were used in a 10-week experiment. The birds were allotted into three experimental treatments with three replications per treatment and 24 birds per replication. The treatments were CON (basal diet), T1 (1 cc of Salicornia extract per liter of drinking water), and T2 (5 cc of Salicornia extract per liter of drinking water). The collected data were analyzed using the SAS package program. The results indicated that addition of Salicornia extract to the drinking water of laying hens did not cause any negative effects on the performance, egg quality, or blood profile. Compared to the control treatment, the treatments with Salicornia extract remarkably increased egg production (P<0.05) in the last week of the study, improved egg shell thickness and significantly reduced the egg breaking rate (P<0.05). The results of this study showed that the addition of Salicornia extract improved egg shell quality; thus, Salicornia extract can decrease the egg breaking rate and increase production on commercial farms.

EFFICACY OF TYLOSIN TARTRATE ON &lt;i&gt;MYCOPLASMA&lt;/i&gt; INFECTIONS AND EGGSHELL APEX ABNORMALITIES IN LAYER HENS UNDER FIELD CONDITIONS

The aim of this report was to describe a clinical case of concurrent infection with Mycoplasma Gallisepticum (MG) and Mycoplasma Synoviae (MS) in layers, complicated with Escherichia coli and Pasteurella multocida, as well as to evaluate the efficacy of tylosin tartrate treatment (Pharmasin® 100% WSG, Huvepharma) on Mycoplasma under field conditions. A flock of 18,500 ISA Brown pullets, 21 weeks of age and MS positive, showed an increase in weekly mortality, with no influence on egg production. At 24 weeks of age, post mortem was carried out and blood samples were collected, as well as samples for microbiological cultures from the lesions. In necropsy, several findings of pericarditis, airsacculitis of posterior thoracic sacs, prolapse and egg yolk peritonitis were found. Sporadic neurological signs were also apparent and post mortem examination revealed yellow caseous exudate accumulations in cranial bones. Although egg production was not influenced, Eggshell Apex Abnormalities (EAA) were increased with a significant number of both broken and misshapen eggs together with discoloration. Elisa serological examinations for Infectious Bronchitis Virus (IBV) and Newcastle Disease Virus (NDV) were within vaccination program limits, but MS, MG and Avian Rhinotracheitis (ART) results showed a significant seroconversion. Microbiology also revealed the presence of Escherichia coli and Pasteurella multocida. On week 25, a drug treatment with tylosin tartrate was applied at a dose of 105 mg kg-1 body weight in drinking water for five consecutive days. Three days after treatment, misshapen, broken and discolored eggs were decreased. The mortality was also significantly decreased within a week since the beginning of tylosin administration and at 30 weeks of age was within acceptable levels. Post mortem evaluation confirmed the absence of previously gross lesions in primary organs. In summary, tylosin treatment in complicated Mycoplasma spp. infections under field conditions improved egg shell quality and decreased mortality, thus the economic losses linked to decreased egg production and labor costs were reduced.

Shell quality - everlasting problem in the today poultry science

Shell breakage (6-20%) is of major concern for its economic consequences and safety of egg consumption. A great deal of effort in the fields of nutrition, genetics and environmental conditions have been carried out to improve eggshell quality but understanding the formation of the eggshell fabric and the origin of shell defects is perhaps the key to solving eggshell problems. The aim of this review is to summaries new information on eggshell problems. The aim of this review is to summaries new information on eggshell formation and update the nutritional unfavourable environmental conditions.

An Examination of the P Requirements of Broiler Breeders for Performance, Progeny Quality and P Balance 2. Ca Particle Size

A 2 x 5 factorial production and balance study with 90 broiler breeders was performed to assess the effects calcium particle size and NPP levels. Cobb 500 broiler breeders, 24 wk of age, were fed 4.68 g Ca intake at peak using 2 particle sizes of dietary calcium carbonate (185.5 microns; 58.8% solubility and 3489.7 microns; 38.5% solubility) and 5 levels of dietary %NPP (0.2% to 0.4% NPP in 0.05% increments; corresponding to a daily intake of 288, 360, 432, 504 and 576 mg at peak intake). Egg production, specific gravity and egg wt were monitored from 24 to 40 wk of age and tibia relative strength at 45 weeks. A retention study was performed at 31 wk of age to determine Ca and P balance. No differences were noted in breeder bone integrity due to NPP intake, though eggs per hen housed and egg shell quality were affected. The breeders fed 288 mg NPP produced the largest number of eggs. The % P retention showed a positive linear response to increasing dietary NPP for breeders fed large particle limestone; but no response in hens fed small particle limestone. The amount of P excreted was increased with P intake but was minimized for hens fed large particle limestone. The amount of Ca excreted was significantly increased with increasing P intake. There was a significant linear increase in excreta Ca and linear decrease in % Ca retention for breeders fed increasing P intake along with small particle calcium but the amount of Ca excreted and % Ca retention was not statistically impacted by particle size. Feeding breeders large particle calcium carbonate increased the egg weight but did not significantly improve shell quality or tibia bone strength. The increased egg weight response for breeders fed large particle calcium carbonate in this short term experiment may have reduced the opportunity for large particle Ca to significantly improve egg shell quality. It can be concluded that particulate Ca sources can improve breeder performance and that dietary levels as low as 0.20% NPP (288 mg/day NPP intake) can be fed without impacting breeder performance; however dietary levels of >0.25%NPP (360 mg/day NPP intake) ensure adequate skeletal integrity.

EFFECT OF HUMIC ACID AND BIO-MOS SUPPLEMENTATION ON EGG PRODUCTION AND QUALITY PARAMETERS IN LOCAL HENS.

This study was designed to investigate the inclusion effect of humic acid (HA) and mannanoligosaccharide (Bio-Mos) into laying hen diets on egg production and egg quality. Gimmizah layers (n=210) 30 wk of age were fed a control diet , 0.1 , 0.2 and 0.3% humic acid and 0.1 , 0.2 and 0.3 % Bio-Mos for 90 days . Feed consumption was measured weekly and feed conversion was calculated.. Mortality was recorded daily. The number of eggs and egg weight were recorded daily throughout the experimental period. Also a sample of 30 eggs from each group was collected randomly to determine egg quality every 30 days. The results were summarized as follow: egg weight and egg production for hens supplemented with humic acid and Bio-Mos were significantly increased compared with the control group. Dietary treatments had insignificant effect on feed intake. No significant effect of humic acid or Bio-Mos had insignificantly effect on egg shape index, albumin (%), Haugh unit and egg yolk index. Whereas, egg shell thickness was significantly (p0.05) increased compared with the control group. In conclusion, supplementation of humic acid and Bio-Mos during laying period significantly increased egg production, egg weight and improved egg shell quality.

Effects of an aqueous alfalfa extract on production performance, egg quality and lipid metabolism of laying hens

The present study was conducted to evaluate the effect of an aqueous alfalfa extract (AAE) on production performance, egg quality and lipid metabolism of laying hens between 28 and 36 weeks of age. Four groups of commercial hens (Hy-Line Brown) were fed with diets containing 0, 0.05%, 0.1% and 0.15% AAE. Dietary AAE had no effect on egg production parameters (p > 0.05). Shell strength was increased (linear and quadratic effects; p < 0.05) with gradient addition of AAE. Furthermore, shell strength was notably higher (p < 0.05) in 0.1% and 0.15% AAE groups than the control group. With an exception of serum low and high density lipoprotein cholesterol, serum total triglycerides and liver cholesterol concentration (day 42), lipid indices in yolk, serum and liver were lowered (linear and quadratic effects; p < 0.05) at day 42 and day 56 as AAE in diets increased, as well as the enzyme activities of acetyl-CoA carboxylase (ACC) and β-hydroxy-β-methylglutaryl-CoA (HMG-CoA) reductase. In relation to the control group, cholesterol and triglycerides in yolk, liver and serum and serum very low density lipoprotein cholesterol were lower in 0.15% AAE-treated birds at day 42 and day 56. It also significantly decreased activities of ACC, HMG-CoA reductase and fatty acid synthetase (FAS) at day 56. The 0.1% AAE decreased triglycerides in yolk, liver and serum, as well as the activities of ACC and FAS at day 56. These data suggest that dietary AAE could be applied to improve egg shell quality and modify the lipid status of laying hens and eggs.

Effect of Dietary Organic Acid Supplementation on Egg Production, Egg Quality and Some Blood Serum Parameters in Laying Hens

The present study was carried out to determine the effect of dietary organic acid mixture supplementation on performance (body weight changes, feed intake, feed efficiency, egg production) egg quality and concentration of some blood serum parameters in laying hens. A total 53 week old 44000 white Lohmann LSL laying hens which were allotted into 4 groups, each containing 11000 hens. The hens were fed with diets (17% CP% and 2795 Kcal Kg ME). Supplemented with 0% (control group No. 1), 260 ppm 1 (group, 2), 520 ppm (group 3) and 780 ppm (group, 4) of organic acid mixture (formic acid and salt of butyric, propionic and lactic acids). The dietary organic acids significantly modify live body weight in groups 2 and 3 and non significantly improved in group 4 when compared with control one. Organic acids supplementation at 780 ppm (group 4) significantly increased egg production by about 5.77% compared with the untreated group, while the lower levels (groups 2 and 3) showed non significant effect. On the other hand dietary organic acid had no effect on the average egg weight, while showed a higher percentage of small, medium and X-large egg size and reduction in large egg size compared with control group. The results revealed that no effect of organic acid on feed intake but improvement egg mass and feed efficiencies was observed. Higher inclusion level of organic acids (780 ppm) improved egg shell quality and non significantly increased egg shell calcium and protein content, improved yolk index, while slightly reduce albumen index. The data revealed that linear increase of serum calcium and concentration of total serum protein. From the obtained data can be concluding that organic acid supplementation at level 780 ppm of laying hens diet improve live body weight, improve persistence of lay and from economical point of view we can concluded that organic acid addition (780 ppm) amazing increase the economical efficiency of layer production.

Relative Performance and Immune Response in White Leghorn Layers Fed Liquid DL-methionine Hydroxy Analogue and DL-methionine

The relative performance and immune response was evaluated in White Leghorn layers fed liquid DL-methionine hydroxyl analogue-free acid (MHA-FA) relative to dry DL-methionine (DLM) in maize-soybean-sunflower based diets. Three graded levels of methionine (Met) from DLM or MHA-FA were added to the basal diet containing 0.27% Met on an equimolar basis to achieve 0.30, 0.36 and 0.42% Met in the diet. Each diet was fed ad libitum to 25 replicates of one bird (individual feeding) each, from 24 to 40 weeks of age. A regime of 16 h light was provided and all the layers were kept under uniform management throughout the experimental period. None of the parameters studied were influenced by the interaction between source and level of Met in diets. Similarly, the majority of parameters, except for daily feed consumption and immune response (influenced by level) and egg specific gravity and shell thickness (influenced by source), were not affected by either source or level of Met in the diets. Feed consumption was significantly lower in the birds fed a diet containing 0.42% Met compared to those fed lower levels of Met. The cutaneous basophilic hypersensitivity response to PHA-P and antibody titre (32 and 40 wk) to inoculation of sheep red blood cells increased significantly by increasing the concentration of Met in the diet from 0.30 to 0.36%. Thus, the Met requirement for immune competence was higher than for optimum production. The source of Met significantly influenced the egg specific gravity and shell thickness. The specific gravity and shell thickness of eggs increased significantly when MHA-FA was used as the source of Met in the diet compared to DLM. From the study it is concluded that Met requirement for immune competence (360 mg/b/d) is higher than for optimum production (300 mg/b/d). MHA-FA was comparable with DLM as a source of Met for production performance and immunity, when the bioavailability of MHA-FA was considered as 88% of DLM. Further, MHA-FA improved egg shell quality compared to DLM.

The Influence of Dietary Calcium and Protein on Third Cycle Hens Under Heat Stress

An experiment was conducted to evaluate the response of heat-stressed hens to increases in dietary calcium at two protein levels. Criteria evaluated included feed consumption, energy consumption, egg weight, egg production, egg specific gravity, and calcium and phosphorus solubilization and excretion. There were no effects of different calcium levels on egg production or egg weight. Increasing dietary calcium from 3.5% (2.9 g/hen/day) to 3.9% (3.2 g/hen/day) significantly increased egg specific gravity. Further increases in calcium intake however, did not improve egg shell quality. Protein level had no influence on egg production or egg specific gravity.

Effect of 1α,25‐dihydroxycholecalciferol on egg shell quality and egg production

1. The effect of replacing dietary cholecalciferol (D3) by 1 alpha,25-dihydroxycholecalciferol (1,25-(OH)2D3) on egg shell quality and egg production was tested on 32-week-old White Leghorn laying hens over 9 weeks. 2. Hens fed on a diet supplemented with 5 micrograms 1,25-(OH)2D3/kg diet, tended to lay more eggs, and the eggs had significantly higher specific gravity and percentage shell than eggs from control hens fed on a diet supplemented with 27.5 micrograms D3/kg diet. 3. The effect became apparent after about 4 weeks of treatment and persisted until the end of the test. 4. Hens fed on a diet without D3 supplement started to lay very thin or soft shelled eggs within 4 weeks, suggesting that the birds' reserves of D3 or its metabolites were depleted within this period. 5. The results suggest that 1,25-(OH)2D3 can be substituted for D3 in layer diets to improve egg shell quality.

Potential Role of 1,25 Dihydroxycholecalciferol in Egg Shell Calcification

Several experiments were conducted to determine if circulating 1,25 dihydroxycholecalciferol (1,25(OH)2 D3) concentrations correlated with the laying hens’ ability to calcify egg shells. Total Ca and 1,25(OH)2 D3 concentrations in plasma of hens selected to produce high quality egg shells averaged greater than 34% of concentrations found in egg shells of the hens’ counterparts producing poor quality egg shells. Immature female chickens had low (60 to 117 pg/mL) levels of circulating 1,25(OH)2 D3; concentrations were similar for immature females later classified to be either poor or good egg shell calcifiers. However, differences in 1,25(OH)2 D3 concentrations became progressively greater with age in the two groups and reached statistical significance (P<.05) at 56 to 64 wk of age.Feeding 1α, hydroxycholecalciferol (1α-OH-D3) or D3 to laying hens for 22 wk resulted in significantly improved egg shell quality (∼ 7%) for those fed lα-OH-D3. No differences in egg weight, egg production, or egg mass were observed. Tibial calcification and breaking strengths were significantly improved by feeding lα-OH-D3. Hens producing eggs with superior egg shell quality have higher concentrations of circulating 1,25(OH)2 D3 than similar hens producing poor egg shells. Dietary supplementation of 1 hydroxylated vitamin D metabolites may be useful in improving egg shell quality.

Use of Methionine Intake Restriction to Improve Egg Shell Quality by Control of Egg Weight

The purpose of these experiments was to determine if the increase in egg weight that occurs with increasing age of hens could be reduced by the control of methionine intake to improve egg shell quality. Four methionine intakes were compared with diets in which all other nutrient intakes remained constant. Daily methionine intakes were 300, 285, 270, and 255 mg per bird. Each treatment was fed to 15 replicates of three birds each. The three-bird replicates received 300 g feed per three-hen cage per day. During Experiment 1, the diets were fed to smaller size pullets of a commercial egg strain from 38 to 62 weeks of age. In the second study, the birds were selected from the larger body size population and fed the diets from 38 to 70 weeks. This was followed by an 8-week force-molt and then continued from 78 to 102 weeks.The reduced methionine intake (255 mg in Experiment 1 and 270 and 255 mg in Experiment 2) significantly reduced the egg weight increase when compared to the 300 mg intake. The same results were obtained during the postmolt period.Egg shell quality, as measured by specific gravity, was improved in both trials when methionine intake was restricted. Shell quality of eggs produced by hens fed 255 mg daily was significantly superior to eggs produced by birds fed 300 mg. Improvement in shell quality when hens reached 50 weeks of age occurred with all treatments as compared to 300 mg. Hen-day egg production was not adversely affected.

Effects of Dietary Calcium Sources and Particle Size on Laying Hen Performance

A total of 462 high producing commercial type laying hens were used to determine the effects of various calcium sources and particle size on egg shell quality and laying hen performance. Neither calcium source, particle size, nor level of calcium had a statistically significant effect on egg weight, percent hen-day egg production, or feed conversion among individual treatments. The results indicate that the addition of large particle oyster shell does significantly improve egg shell quality when substituted for a portion of the pulverized calcium source, even though the hens are consuming adequate calcium (>3.75 g/hen/day), with improvement being significantly greater after 24 weeks of lay. It was also concluded that the calcium from oyster shell, in any form, is more available than that of limestone for egg shell formation. Aragonite was shown to support performance equal to that of pulverized limestone at the 3.5% calcium level.

The Failure of Pullet-Sized Dicalcium Phosphate to Improve Egg Shell Quality of Hens

Two experiments were conducted in which 250 Babcock B-300 hens were used. Three commercial-type layer diets were fed. In the control diet phosphorus was supplied in the form of fine-granular dicalcium phosphate. In a second diet, phosphorus in the form of pullet-sized dicalcium phosphate was substituted for all phosphorus from the fine-granular phosphate present in the control diet. In a third diet, pullet-sized limestone was substituted for an equal amount of calcium from fine-granular limestone present in the control diet (Exp. 2 only). The results of these studies indicated that the inclusion of pullet-sized dicalcium phosphate or pullet-sized limestone in the diet of laying hens had no influence on specific gravity of eggs, egg weight, egg production or serum calcium. Dietary treatment had no significant influence on feed consumption of birds in Exp. 1, however, the inclusion of pullet-sized dicalcium phosphate in the diet of birds in Exp. 2 significantly decreased feed consumption.