Eggshell Breaking Strength Research Articles

The Role of Magnesium and Calcium in Eggshell Formation in Tsaiya Ducks and Leghorn Hens

Tsaiya ducks and Leghorn hens are the two major laying birds raised in Taiwan. They are all excellent egg layers. Tsaiya ducks are small in body size (1.3 kg) with bigger egg weight (65 g) and stronger eggshell breaking strength than eggs from hens. The eggshell consists mainly of calcium carbonate, hence calcium plays an important role in the eggshell formation. Magnesium is also present in eggshell in small amounts, which may have effect on maintaining eggshell quality. In comparison studies, it was shown that the duck eggshells contained higher calcium and lower magnesium content than chicken eggshells. The eggshell magnesium content was not affected by the dietary magnesium levels (690-2380 ppm) in ducks, but in hens, it increased linearly with dietary magnesium levels. The palisade layer (5000×) of the eggshell was found to have a compact form for ducks while there are many hallow vesicles in chicken eggshells. The eggshell magnesium deposition model is different for ducks and hens with ducks having a one-peak and hens having a two-peak model. The calcium deposition model is similar for both birds. Both the carbonic anhydrase specific activity and total activity in the shell gland mucosa of ducks are higher than those in hens. Ducks retain higher magnesium and lower calcium in the shell gland mucosa and secret less magnesium and more calcium into the shell gland lumen for eggshell deposition. The ATPase specific activity is maintained fairly constant during the eggshell forming stage, indicating continuous calcium transport into the shell gland lumen for eggshell formation. The magnesium content in duck eggshells is much lower than that in hens indicating that the magnesium content in the eggshell may have an effect on eggshell quality. (Asian-Aust. J. Anim. Sci. 2003. Vol. 16, No. 2 : 290-296)

산란계에 있어 생균제의 첨가가 계란품질 및 배설물내 유해가스 함량에 미치는 영향

본 연구의 목적은 생균제를 산란계에 급여하였을 때 계란품질 및 배설물내 암모니아태 질소 함량에 미치는 영향을 조사하기 위하여 실시하였다. 사양시험은 36주령 ISA brown 산란계 144수를 공시하였으며, 처리구로는 옥수수－대두박 기초 사료구(Con; basal diet), 기초 사료구에 생균제를 0.3%(PB0.3; basal diet + 0.3% probiotics)와 0.6%(PB0.6; basal diet + 0.6% probiotics) 첨가한 구로 구성되었다. 총 28일간의 사양시험 기간동안, 산란율, 난중 그리고 난각 강도에 있어서는 처리간에 차이는 있었지만 유의적인 차이를 보이지 않았다(P<TEX>$>$</TEX>0.05). 난각의 두께에 있어서는 PB0.6 처리구가 유의적으로 높게 평가되었다(linear effect, P<TEX>$<$</TEX>0.01). 난황색에 있어서는 생균제를 첨가함에 따라 대조구와 비교하여 통계적으로 높게 평가되었으며(linear effect, P<TEX>$<$</TEX>0.02), 난황계수에 있어서도 생균제를 첨가함에 따라 개선되는 경향을 나타내었다(linear effect, P<TEX>$<$</TEX>0.04). 배설물내 암모니아태 질소 함량에 있어서는 PB0.6 처리구가 다른 처리구와 비교하여 유의적으로 낮게 평가되었다(linear effect, P<TEX>$<$</TEX>0.04). 결론적으로, 산란계 사료내 생균제의 첨가가 난각두께, 난황색 및 난황계수를 증가시키는 것으로 사료되며, 배설물내 암모니아태 질소 함량을 감소시킴을 알 수 있었다. This study was conducted to investigate the effects of feeding probiotics on the egg quality and excretal noxious gas in laying hens. One hundred forty four, 36 weeks old ISA brown commercial layer, were employed in a 28 d feeding trial with a 7 d adjustment period. Dietary treatments are 1) control(basal diet), 2) PB0.3(basal diet+0.3% probiotics), 2) PB0.6(basal diet+0.6% probiotics). For overall period, hen-day egg production, egg weight and egg shell breaking strength tended to increase (P>0.05) by dietary probiotic supplementation. Egg shell thickness was improved by supplementation of probiotics(linear effect, P<TEX>$<$</TEX>0.01). Diets PB0.3 and PB0.6 improved the yolk color compared to control diet(linear effect, P<TEX>$<$</TEX>0.02). As supplementation level of probiotics increased in the diets, egg yolk index tended to increase(linear effect, P<TEX>$<$</TEX>0.04). <TEX>$NH_3$</TEX>-N concentration in excreta fed PB0.6 diet was significantly (P<TEX>$<$</TEX>0.04) lower than either control or PB0.3 diet. In conclusion, supplementing probiotics to a Corn-SBM diet for laying hens increased egg shell thickness, yolk color and decreased egg yolk index, and decreased excretal <TEX>$NH_3$</TEX>-N concentration.

산란계 사료에서 우렁쉥이껍질 첨가가 계란 품질에 미치는 영향

본 내용은 미이용수산자원인 우렁쉥이 껍질의 성분상의 특성을 활용하여 착색제, 난각과 타우린 강화제로의 이용방법을 제시함으로서 폐기되고 있는 천연자원의 효율적인 재활용을 도모하는 한편, 합성색소의 생체기능학적 문제점을 해결하고 축산농가의 생산비 절감에 기여함을 그 목적으로 실시하였으며 실험결과는 아래와 같다. 산란계사료에 우렁쉥이 껍질을 1<TEX>$\sim$</TEX>5% 첨가했을 때의 산란율과 계란의 무게가 일반사료구(대조구)와 비슷한 경향을 보여 우렝쉥이 껍질첨가가 산란계의 산란성적에 영향이 없는 것으로 나타났다. 난황색도는 우렁쉥이 껍질 최소첨가량인 1<TEX>$\sim$</TEX>2% 첨가구에서 이상적인 Roche color fanscore (RCFS) 12<TEX>$\sim$</TEX>13 수준을 나타내고 3% 이상의 첨가구에서는 15 이상의 RCFS를 나타내어 첨가량이 증가할수록 카로티노이드의 축적량이 급격히 증가함을 알 수 있었으나 4% 이상에서는 축적률이 저조한 경향을 보였다. 계란 비중과 파괴강도는 일반란인 대조구의 경우는 점차 감소하거나 유지되었으나 우렁쉥이 껍질 첨가구는 급격히 증가하는 경향을 보였다. 이러한 효과는 2주부터 뚜렷하였으며 3주째에는 4% 첨가구의 경우 일반란보다 2.4% 비중이 증가한 것으로 나타나 전체적으로 우렁쉥이 껍질 첨가량이 증가할수록 난각의 파괴강도와 계란비중이 급격히 증가하였으나 4% 이상 첨가구에서는 그 증가폭이 감소하는 경향을 보였다. 계란 타우린 함량은 우렁쉥이 껍질 첨가량이 증가할수록 계란내 단백질 함량은 일정한데 비해 급격히 증가하는 경향을 보여 일반란인 대조구의 경우 18.53<TEX>$\pm$</TEX>3.09mg% 정도 함유되어 있는 반면 우렁쉥이 껍질 4% 첨가구인 경우 108.10<TEX>$\pm$</TEX>2.44mg% 정도 함유되어 있는 것으로 나타나 사료에 첨가한 우렁쉥이 껍질내 타우린(2.13%)이 계란으로 잘 이행되는 결과를 보였다. 전체 결과에 따라 우렁쉥이 껍질은 첨가량에 따라 산란계 사료용 합성 착색제를 대체할 수 있는 천연 착색제(색소원)로 사용 가능하며 부가적인 효과로 난각 강화 및 타우린이 강화되는 것으로 나타났다. This study was conducted to evaluate the feeding value of ascidian tunic shell the effects of its dietary supplementation on laying performance, egg-yolk pigmentation, egg-shell strength and egg taurine content. A total of 168 brown layers at the age of 29wks in commercial cage were fed for 4 wks with 7 different diets containing ascidian tunic shel1(AST) at varying levels of 0<TEX>$\sim$</TEX>5% Dm or 0% AST with 100ppm carophyll red. No differences were found in egg production and weight among the treatments indicating that ascidian tunic shell did not adversely affect the laying performances. Adding the ascidian tunic shell to the diets increased egg-yolk pigmentation compared to the control and resulted in simillar or better effect on egg-yolk pigmentation compared to 100ppm carophyll red. The data suggest that ascidian tunic shell may be used as feed ingredients in layer diet enrichment of egg-yolk pigmentation in the place of carophyll red(chemical pigment). Specific gravity and breaking strength of egg shell were significantly increased by the adding ascidian tunic shell to the diet, suggesting that ascidian tunic shell may be used as feed ingredients for increasing egg shell strength. Also taurine content of egg was significantly increased with increasing supplementation of ascidian tunic shell to the diet(p<0.05). Therefore, ascidian tunic shell may be used as feed ingredients in laying hen diet to improve egg quality such as egg-yolk pigmentation, egg-shell strength and egg taurine enrichment.

Responses of IsaBrown laying hens to a pre-layer diet containing additional calcium and to dietary protein and lysine concentrations during lay

IsaBrown pullets were obtained from a commercial breeder at 15 (Expt 1) and 16 (Expt 2) weeks of age and housed in either single-bird or multiple 5-bird cages in a high rise, windowless layer house in which temperatures were maintained below 30˚C by computerised control of fans and evaporative cooling pads. In Expt 1, they were fed either a grower diet or a pre-layer diet consisting of the grower diet containing additional calcium to 18 weeks of age and then maintained during lay to 56 weeks of age on diets containing either 160 or 180 g crude protein (CP)/kg. In Expt 2, they were fed the grower diet to 19 weeks of age and then 1 of 5 diets similar in all ingredients except that the lysine concentration varied between 7.35 and 8.95 g/kg in increments of 0.4 g/kg. The L-lysine HCl supplements were added in lieu of solka floc, an inert cellulose supplement. In Expt 1, mortality was low (2.25%), peak egg production was high (95–98%), and the mean rate of lay at 56 weeks of age was above 88%. The diet fed prior to lay had no significant effect on production during lay. Feed intake and egg production were similar for hens fed both dietary protein levels during lay, and egg weight and egg mass output were greater for hens fed the diet containing 180 g CP/kg. Hens in multiple-bird cages ate significantlyless feed for a significantly smaller daily egg mass output. In Expt 2, increasing the dietary lysine concentration significantly reduced feed intake and significantly increased lysine intake, egg shell breaking strength, and albumen height. Multiple-caged hens had a significantly lower hen-housed egg production as a result of a 7-fold increase in mortality compared with hens in single cages, due mainly to cannibalism. The daily lysine requirement formaximum egg production approximated 940 mg for hens in single cages and 975 mg for hens in multiple-bird cages.

Editorial

IsaBrown pullets were obtained from a commercial breeder at 15 (Expt 1) and 16 (Expt 2) weeks of age and housed in either single-bird or multiple 5-bird cages in a high rise, windowless layer house in which temperatures were maintained below 30˚C by computerised control of fans and evaporative cooling pads. In Expt 1, they were fed either a grower diet or a pre-layer diet consisting of the grower diet containing additional calcium to 18 weeks of age and then maintained during lay to 56 weeks of age on diets containing either 160 or 180 g crude protein (CP)/kg. In Expt 2, they were fed the grower diet to 19 weeks of age and then 1 of 5 diets similar in all ingredients except that the lysine concentration varied between 7.35 and 8.95 g/kg in increments of 0.4 g/kg. The L-lysine HCl supplements were added in lieu of solka floc, an inert cellulose supplement. In Expt 1, mortality was low (2.25%), peak egg production was high (95–98%), and the mean rate of lay at 56 weeks of age was above 88%. The diet fed prior to lay had no significant effect on production during lay. Feed intake and egg production were similar for hens fed both dietary protein levels during lay, and egg weight and egg mass output were greater for hens fed the diet containing 180 g CP/kg. Hens in multiple-bird cages ate significantlyless feed for a significantly smaller daily egg mass output. In Expt 2, increasing the dietary lysine concentration significantly reduced feed intake and significantly increased lysine intake, egg shell breaking strength, and albumen height. Multiple-caged hens had a significantly lower hen-housed egg production as a result of a 7-fold increase in mortality compared with hens in single cages, due mainly to cannibalism. The daily lysine requirement formaximum egg production approximated 940 mg for hens in single cages and 975 mg for hens in multiple-bird cages.

Intermittent lighting and dietary sodium bicarbonate supplementation for laying hens at high temperatures

Point-of-lay pullets were housed in 2 temperature-controlled rooms maintained at a constant 32°C with either a conventional 16 h light : 8 h dark (16L : 8D) or an intermittent 3L : 1D lighting regimen. They were fed either a conventional layer diet (12·0 MJ of ME and 199 g crude protein/kg) or this diet supplemented with 1% sodium bicarbonate (NaHCO3). Production and egg shell quality measurements were made at 8-week intervals from 22 to 62 weeks of age. All measures were influenced by age. The 3L : 1D regimen significantly increased feed intake (P &lt; 0·001), weight gain (P &lt; 0·01), egg weight (P &lt; 0·001), egg shell breaking strength (P &lt; 0·001), and shell thickness (P &lt; 0·01). Significant age×light interactions were observed for feed intake, egg production, and egg mass. Hens in the 3L : 1D regimen ate significantly (P &lt; 0·001) more food and produced significantly (P &lt; 0·01) greater egg mass to 46 weeks of age. No significant differences were observed after 46 weeks. Although not significant, NaHCO3 consistently improved shell breaking strength. The response was small in the 16L : 8D regimen (3%) compared with the 3L : 1D environment (7%), the latter being additional to the 14% improvement resulting from the use of the 3L : 1D regimen. The results indicate advantages from the use of intermittent lighting and dietary NaHCO3 supplementation at high temperatures.

Fluoride tolerance of laying hens

1. One thousand Silver Grey Hyline hens were given drinking water containing 5 concentrations of added sodium fluoride (0, 6, 10, 14 and 20 mg/1) over a 17‐week growth and 57‐week laying period. The natural fluoride content of the water was 0–21 mg/1 during the growing period and 0–29 mg/1 throughout lay. 2. During the rearing phase, efficiency of food utilisation and mortality were not significantly affected by the fluoride concentration of the water. Weight gain and food intake decreased in the 10 and 14 mg/1 fluoride treatments. 3. During the laying period, the fluoride content of the water had a significant effect on egg production, but eggshell breaking strength was not significantly influenced. 4. Post mortem analyses, carried out at the end of lay (74 weeks of age), showed that carcase weight and the fluoride content of the os femur increased significantly as the fluoride concentration in the water increased; the increase in bone fluoride followed a linear pattern. 5. Histopathology showed no evidence of changes in the livers or kidneys; liver weights and breaking strength of the os femur were unaffected by the amount of fluoride consumed. 6. The data showed that under commercial conditions, laying birds can tolerate ingesting 4–453 mg fluoride/day for up to 74 weeks.

Fatty Liver-Hemorrhagic Syndrome Observed in Commercial Layers Fed Diets Containing Chelated Minerals

This study was originally conducted to determine the effect of various chloride levels and consumption of chelated versus non-chelated minerals on egg production and eggshell breaking strength. However, the focus of this report changed after fatty liver-hemorrhagic syndrome (FLHS) was observed in hens that consumed diets containing chelated minerals. No FLHS was observed in hens that consumed a diet that contained non-chelated minerals. Four hundred thirty-two 35-week-old commercial laying hens were housed in individual cages in groups of nine hens each. The treatments were factorially arranged (3 x 2) such that six experimental diets differing in chloride levels and in source of minerals were fed for six 28-day laying periods. A significantly higher mortality attributed to FLHS was observed in hens that consumed the diets having chelated minerals as compared with hens that consumed the diets with non-chelated minerals. No difference in mortality was observed among the hens fed the various chloride diets.

Research Note: Responses of Laying Hens on Saline Drinking Water to Dietary Supplementation with Various Zinc Compounds

Production variables, eggshell defects, eggshell quality, the concentration of calcium-binding protein (CaBP), and the activity of carbonic anhydrase (CA) in the shell gland mucosa were determined in hens receiving town water (10 mg Na/L), or town water supplemented with 2 g NaCl/L (796 mg Na/L). Five treatments were examined. Control hens received town water and a proprietary layer mash containing .17% Na. The remaining four treatments received the water containing NaCl (2 g/L). Hens of Treatment 2 were fed the proprietary layer mash and those of Treatments 3, 4, and 5 received, respectively, the layer mash containing supplements of Zn-methionine (Zinpro-200; .5 g/kg), Zn sulfate (ZnSO4·7H2 O; .46 g/kg), or chelated Zn-EDTA (.54 g/kg) to supply the same concentration of Zn (.1 g/kg). The treatments were applied for 6 wk.Hens receiving the saline drinking water without any dietary Zn supplement produced significantly (P < .05) more eggs with shell defects than hens receiving the town water. This increase in the incidence of eggshell defects was associated with significant reductions in eggshell breaking strength, the concentration of CaBP, and the activity of CA. Supplementing the saline drinking water with any of the three Zn compounds significantly reduced the incidence of eggshell defects and in some cases improved shell breaking strength, the concentration of CaBP, and the activity of CA.

Response of Early- and Late-Maturing Commercial Leghorn Pullets to Low Levels of Dietary Phosphorus

An experiment with a 2 × 2 factorial arrangement of treatments was used to determine differences in responses of early-maturing (EM) and late-maturing (LM) pullets fed low dietary P (.4% total P; LP) and normal dietary P (.7% total P; NP) levels. Six hundred pullets (18-wk-old) were equally and randomly allocated to the LP and NP treatments. Egg production, egg weight, egg specific gravity, and eggshell breaking strength were measured at 26 and 28 wk. When pullets were 28 wk of age, plasma total Ca (TCa), ionic Ca (Ca++), and inorganic P (Pi) concentrations, urine Ca concentrations, and urine pH, bone mineral content (BMC), bone density, total kidney weight, and kidney weight ratio (heavier kidney ÷ lighter kidney) were determined from 15 pullets each from EM-NP, EM-LP, LM-NP, and LM-LP treatments. The pullets with osteoporosis and pullets that died during the experiment were categorized into EM and LM groups.Results showed that LP caused severe adverse effects on LM pullets. The LM pullets fed the LP diet had high plasma Ca++ concentration, low plasma Pi concentration, increased urine Ca concentration, a high incidence of osteoporosis, mild kidney lesions, and elevated mortality compared with pullets subjected to the other treatments. The EM pullets fed the LP diet were also adversely effected by LP, but were less susceptible to osteoporosis and mortality. The LP diet improved eggshell quality, but this beneficial effect was only temporary. The severity of adverse effects of low dietary P was greater for LM than the EM pullets.

Effect of the manganese content in laying hen feed with different Ca and mineral levels on the egg shell quality and bone mineralization of hens

Four experiments with 270, 44, 432 and 66800 Leghorn hens were carried out to investigate the influence of various Mn additions to diets differed in mineral or Ca contents on egg shell quality. The addition of 300 mg Mn/kg diet improved significantly egg shell breaking strength by 4 N over one year. The supply of 50-500 mg Mn/kg diet for 10-24 weeks of the second half of laying year did not influence the egg shell quality. Addition of mineral mixture or Ca grit to layer rations with adequate or higher Mn levels did not influence egg shell strength. High mineral content in a low manganese diet increased number of cracks by 3%. Strength, weight and ash content of tibia were significantly reduced by feeding a low mineral level. Addition of 50-150 mg Mn per kg low mineral diet normalized partially tibia stability in young hens. It was concluded that supplied dietary Manganese influences calcification positively only in young hens. High levels of Ca did not influence the effects of Mn. 50 mg Mn per kg layers mixture have been considered as an essential supply.

Effectiveness of Zinc Bacitracin on Production Traits and Energy Metabolism of Heat-Stressed Hens Compared with Hens Kept Under Moderate Temperature

Two experiments with a total of 100 White Leghorn hens (26 to 59 wk of age) and 120 Rhode Island Red chickens (4 to 12 wk of age) were conducted to study the effect of 100 mg zinc bacitracin (ZBA)/kg of feed on hens and chickens acclimatized to 20 or 34 C environments. Layers were provided ad libitum access to a diet containing 11.12 MJ ME/kg (1 MJ = .239 Mcal) and 174 g CP/kg supplemented with 0 and 100 mg ZBA/kg. Body weight gain, egg number, total egg mass, and feed efficiency of ZBA-treated hens kept at a moderate temperature (20 C) were not significantly improved by 3.5, 2.6, 3.3, and 3.1%, respectively. However ZBA supplementation induced a more pronounced increase in performance in heat-stressed hens. The respective traits were significantly improved by 66.3, 15.4, 16.9, and 5.9%. Additionally, treated hens maintained at 34 C consumed significantly more feed than untreated hens. Eggshell breaking strength of treated hens held under normal conditions was not significantly improved. Feeding ZBA to heat-stressed hens led to a statistically higher breaking strength. Supplementation with ZBA for hens acclimatized to 20 and 34 C reduced fasting heat production by 4.1 and 7.6%, respectively. However, in the 20 C environment the differences were significant at only one of seven ages. The upper critical temperature (UCT) of ZBA-treated hens increased significantly at both temperatures from 34 to 42 wk of age relative to the control group. No significant effects of ZBA on UCT were observed at 24 to 32 wk and 40 to 52 wk of age. Heat tolerance of chickens 4 to 12 wk of age fed ZBA was significantly improved by 23.7% (20 C) and 51.2% (34 C). Results indicated a clear response of ZBA on improving performance of hens acclimatized to 34 C, which was due to overall heat production, especially for hens kept at constant high temperature. The effect of ZBA on hens housed under thermoneutral (20 C) conditions was not statistically significant.

Effects of Particle Size and Origin of Calcium Sources on Eggshell Quality and Bone Mineralization in Egg Laying Hens

Eggshell quality and tibial ossification were studied in ISA brown egg-laying hens. Diet was supplemented with calcium sources differing in origin (seashells treated with phosphoric acid, oyster shells, and limestone) and particle size (ground or particulate). Egg production, egg mass, and feed efficiency were not affected by the origin or particle size of calcium sources. Feed consumption and live weight were higher in birds fed particulate sources, especially when ground and particulate oyster shells were compared. There was a significant interaction (source origin × particle size) in eggshell quality criteria. Egg weight was lower for hens fed ground limestone than for those fed ground seashells and particulate limestone. The latter group also had larger eggs than the group fed particulate oyster shells. Eggshell weight was higher for hens receiving particulate limestone than for those fed ground limestone and particulate oyster shells, but shell index values were similar whatever the calcium sources. Eggshell-breaking strength was higher in eggs of birds fed diets incorporating ground seashells and particulate limestone than in eggs of birds fed ground limestone. Tibial-breaking strength variables and percentage ash were greatly increased by the use of particulate calcium sources but were unaffected by the origin of calcium sources. Plasma concentration of total calcium was increased in the hens fed on the particulate seashell diet during eggshell formation. Plasma level of inorganic phosphorus was higher when the birds were given ground limestone. There was no effect of the particulate seashells and the ground limestone on metabolizable energy, nitrogen, and calcium retention.

Hammer Mill Versus Roller Mill Grinding of Corn for Commercial Egg Layers

Three trials were conducted to determine differences in particle size characteristics of corn processed with a hammer mill vs. that processed with a roller mill. The particle size (geometric mean diameter) for corn processed with the roller mill ranged from 1,343 to 1,501 μm whereas that of corn processed with the hammer mill ranged from 814 to 873 μm. The trials demonstrated that the differing particle size characteristic of feed milled with hammer mill versus roller mill did not significantly influence the performance of commercial laying hens as measured by body weight, percentage of hen-day egg production, egg weight, average daily feed consumption, feed efficiency (grams of feed per gram egg produced), egg shell breaking strength, or mortality.

Comparison of the Use of Dietary Aluminum with the Use of Feed Restriction for Force-Molting Laying Hens

Use of a high level of dietary aluminum was compared with a conventional feed restriction procedure for force-molting of Single Comb White Leghorn hens. Six replicate groups of 10 or 12 hens, 72 wk of age, housed 2 per cage, were randomly assigned to Treatments A and B, and 12 replicate groups were assigned to Treatment C. Hens in Treatments A and B were fed ad libitum a corn-soybean meal diet (15% CP, 3.5% Ca and .35% available P) containing .3% Al as aluminum sulfate. Hens in Treatment C were completely feed restricted for 10 days. Oyster shell was provided at 27 g/bird in Treatments B and C on the day before the start of the molting procedure. Water was provided ad libitum for all treatments. The effective photoperiod was reduced to 9 h. A diet containing 13% CP and 1% Ca was provided at 45 g/bird per day, starting 2 or 3 days following cessation of egg production and continuing until Day 28. On Day 29 the photoperiod was increased to 16 h, and hens were fed a layer diet.Egg production completely ceased by Day 7 for hens in Treatment C and almost ceased (3%) by Day 15 for hens in Treatments A and B. Body weight loss for hens in Treatment C was significantly greater than for aluminum-treated hens after 10 days. Feed intake of Al-fed hens averaged 43 g/hen per day. During a 14-wk postmolting period, no significant differences among treatments were observed in feed intake, egg production, and egg shell breaking strength. No differences among treatments were observed in plasma total calcium and inorganic phosphorus measured during the molting or the postmolting period. The results indicate that dietary aluminum can be used as a force-molting agent for laying hens.

Use of High Levels of Dietary Aluminum and Zinc for Inducing Pauses in Egg Production of Japanese Quail

The effect of using a high level of dietary aluminum (.3% Al, as aluminum sulfate) was compared with that of using dietary zinc (1.5% Zn as zinc oxide) for force molting Japanese quail hens. A basal diet (2.5% Ca and .35% available P) was fed alone or supplemented with Zn or Al for 7 days in Trial 1 and for 4 days in Trial 2. Light was maintained at 16 h light (L):8 h dark (D) in Trial 1 and reduced to 8L:16D during Days 1 to 14 in Trial 2. In Trial 1, feed intake averaged 23, 11, and 7 g/hen/day during Days 1 through 7 for the control, Al, and Zn treatments, respectively. Both the Al and Zn treatments significantly (P<.05) reduced body weight. In both trials, egg production approached 0% by Days 3 and 5 for hens in the Zn and Al treatments, respectively. In Trial 2, egg shell breaking strength was significantly (P<.05) reduced by dietary Al and Zn. Aluminum significantly reduced plasma inorganic P, measured on Day 5.In Trial 3, diets containing graded levels (0, .05, .10, or .15%) of Al were fed to Japanese quail hens for 28 days. Both .10% and .15% Al significantly (P<.05) reduced egg shell breaking strength during Days 8 through 12 and body weight at Day 28. Feeding .15% Al significantly reduced feed intake and egg production.Results demonstrated that high levels of dietary Al can negatively affect egg production of Japanese quail. If dietary Al is present in high enough amounts, it can induce pauses in egg production, possibly through its effect on feed intake, P metabolism, or both.

Breaking strength: An alternative indicator of toxic effects on avian eggshell quality

AbstractA method for measuring the breaking strength of avian eggshells is presented along with a brief review of the literature relating shell strength to chlorinated hydrocarbon exposure. The effect of dietary DDE on shell strength is compared with its effect on shell thickness in the mallard duck (Anas platyrhynchos L). Shell strength was significantly reduced at a lower dietary DDE concentration than was shell thickness. The potential utility of strength measurement as an end‐point in toxicology studies is discussed.

Effect of Summer Cyclic Temperatures Versus Moderate Temperature on Laying Hen Performance

Three trials were conducted to determine the effects of seasonal temperature extremes on laying hen performance. The temperatures used were a constant 21 C vs. a 24-hr linear temperature cycle that ranged from 24 to 35 to 24 C. Results show that percent hen-day production and eggshell breaking strength did not differ significantly between the temperature regimens. The laying hens exposed to the 24- to 35- to 24-C regimen gained significantly less body weight, consumed significantly less feed, and laid eggs that were significantly smaller than the hens exposed to a constant 21-C temperature.

Response of Different Commercial Strains of Laying Hens to Short Total Photoperiods in Interrupted Night Experiments During Days of 24 and 28 Hours

Experiments were conducted: 1) as pilot experiments in which each experimental unit, replicated two or three times, consisted of 15 hens, 2) as practical experiments in which each of four strains was replicated twice in two rooms containing 200 to 265 hens, and 3) as commercial experiments in which each experimental unit consisted of 4 strains of 1000 hens but in which no replication occurred.Short total photoperiods were used in interrupted night experiments with 24-hr and 28-hr days. A light regimen of 2L:6D:2L:18D yielded similar results as 12L:16D for percent egg production, egg mass, egg shell breaking strength, and feed efficiency. Exposure to 28-hr days, in comparison with 24-hr days, resulted in a reduction of number of eggs produced but did not reduce egg mass produced. In one of four strains, the increase in egg size and reduction in number of eggs produced was significantly (P<.05) less than in the other three strains. Under the 28-hr day regimens shell breaking strength was consistently greater (P<.01) than under 24-hr light regimens.In an additional experiment, no relationship was found in egg breakage during transport between two populations of eggs that differed in eggshell breaking strength as a result of differences in light regimens received by the hens.Short (2L:10D:2L:10D or 2L:12D:2L:8D) and very short (2L:12D:1/4L:9 3/4D) interrupted night regimens generally yielded lower egg production than 16L:8D or 8L:10D:2L:4D light regimens. There was an indication that there might be strain differences in the response to the interrupted night regimen.Exposure to 2L:6D:2L:18D for 6 weeks at the start and 8 weeks at the end of an 11-month experimental period, with 16L:8D given during the remainder of the period, resulted in lower egg production during the last 8 weeks and no compensatory improvement in egg shell breaking strength or egg weight in comparison with continuous exposure to 16L:8D.

Fluorosis in the Laying Hen

One hundred fifty Single Comb White Leghorn hens of two strains previously selected for either high eggshell strength (HES strain) or low eggshell strength (LES strain) were treated for 8 weeks with sodium fluoride added to a practical-type corn-soybean meal basal diet at 0, 300, 600, 900, or 1200 ppm. The HES strain was found to be more sensitive to fluorosis than the LES strain. High levels of dietary fluoride produced greater decreases in feed consumption, egg production, eggshell breaking strength, eggshell weight, and eggshell thickness in the HES strain than in the LES strain, despite the fact that the absolute intake of fluoride was greatest in the LES strain. Fluoride treatment significantly increased bone magnesium content in both strains and plasma phosphorus in the HES strain but did not significantly affect bone breaking strength or the concentrations of total calcium, ionized calcium, or magnesium in plasma of either strain. High fluoride treatment (1200 ppm) reduced the growth of HES progeny after 8 weeks of treatment of the hens, but LES progeny were not affected. These results suggest that the decreased sensitivity of the LES strain to fluoride may relate to its relatively greater (ca. 14%) volume of bone in which most absorbed fluoride is deposited.