Sprinkling coarse marble powder during the afternoon, toward the end of the laying period, may increase eggshell quality

The aim of this study was to investigate the effects of time, particle size (PS) and level of calcium supplementation above the requirements toward the end of the laying period on egg production and eggshell quality. A total of 675 Isa-Brown layer hens were distributed in a completely randomized factorial arrangement of 3×3×3, using three sprinkling times (08.00, 12.00, 16.00 hours), PC (mash, granular and large size) and amounts (0 g control, 0.75 g/day/h, 1.50 g/day/h) of marble sprinkling as a calcium source. All hens were fed a commercial layer diet from 55 to 67 weeks of age. Sprinkling of 1.50 g marble reduced ( P  < 0.05) egg production compared to 0.75 g marble, and feed efficiency (FE) compared to that of 0 and 0.75 g marble. Sprinkling of 0.75 and 1.50 g marble increased ( P  < 0.01) eggshell weight, shell strength and shell thickness compared to that of 0 g marble. The interaction of sprinkling time-by-PS-by–quantity of marble was significant for egg production ( P  < 0.05), FE and shell strength ( P  < 0.01). Results showed that sprinkling of coarse marble powder to complete diet increased shell strength without reduction in egg production and FE.     

饲粮不同代谢能、粗蛋白质水平对新杨绿壳蛋鸡产蛋后期生产性能、蛋品质及血清生化指标的影响

本试验旨在通过研究饲粮不同代谢能、粗蛋白质水平对新杨绿壳蛋鸡产蛋后期(44~56周龄)生产性能、蛋品质及血清生化指标的影响,得出其产蛋后期饲粮代谢能和粗蛋白质的适宜配比。选取768羽体重相近的43周龄末新杨绿壳蛋鸡,随机分为6组,每组4个重复,每个重复32羽。采用2×3因子(代谢能水平为10.87和11.08 MJ/kg,粗蛋白质水平为15.00%、15.50%和16.00%)设计试验,共设计6种饲粮。试验预试期1周,正试期12周。结果表明:1)饲粮不同代谢能、粗蛋白质水平对绿壳蛋鸡产蛋后期产蛋率和料蛋比有显著影响(P0.05),饲粮代谢能和粗蛋白质水平在产蛋率上表现出极显著的交互作用(P0.01),其中,高能低蛋组(代谢能为11.08 MJ/kg,粗蛋白质为15.00%)产蛋率最高,料蛋比最低。2)饲粮较高粗蛋白质水平(16.00%)能显著提高绿壳蛋鸡产蛋后期鸡蛋的哈氏单位(P0.05);饲粮较高代谢能水平(11.08 MJ/kg)能显著提高绿壳蛋鸡产蛋后期鸡蛋的蛋黄颜色(P0.05);饲粮代谢能和粗蛋白质水平在蛋品质上未表现出显著的交互作用(P0.05)。3)高能低蛋组绿壳蛋鸡血清尿素氮含量最低;饲粮较高代谢能水平(11.08 MJ/kg)能显著降低绿壳蛋鸡血清总胆固醇含量(P0.05)。综上,在本试验条件下,饲粮代谢能、粗蛋白质水平分别为11.08 MJ/kg和15.00%时,更有利于绿壳蛋鸡产蛋后期生产性能的发挥和蛋品质的改善。     

The effect of dietary calcium source, concentration and particle size on calcium retention, eggshell quality and overall calcium requirement in laying hens

1. Four different sources of calcium in isonitrogenous and isoenergeric diets were fed to laying hens for 2 weeks when they were 56 and 57 weeks old. The calcium source blends were as follows: 29% fine limestone (LF)+71% large limestone (LG), 32% LF+68% eggshell, 32% LF+68% oyster shell, 50% LF+50% LG. The contents of these blends of calcium in the diets were as follows: 103.3, 93.3, 93.3 and 93.3 g/kg, respectively. 2. The coefficients of calcium retention were significantly higher in 50:50 LF:LG (0.578) and 32:68 LF:eggshell (0.576). The midnight feeding significantly improved the coefficient of calcium retention in all mixtures except 50:50 LF:LG. 3. In the mixtures 29:71 LF:LG and 32:68 LF:oyster shell, there were significantly greater eggshell quality, eggshell weight, eggshell thickness and eggshell strength. Midnight feeding had no significant effect on eggshell quality. 4. In the ration with oyster shells, 96.5% of the retained calcium was deposited in the eggshell, but in rations 32:68 LF:eggshell and 50:50 LF:LG the utilisation was only 73.9 and 78.6%, respectively. 5. To ensure good quality eggshells in the last third of production, the recommendation for calcium is 4.1 g/kg (900 g/kg dry matter, feed intake 110 g/d). As a source of calcium in this stage of production, a feed mixture containing two-thirds large particles should be used (limestone grit or oyster shell).     

Voluntary food and calcium intake by the laying hen

Two experiments, each of 40 d duration, are described in which a diet rich in calcium (3.5% Ca) or one deficient in calcium (1% Ca), but with oyster shell offered separately, were fed ad libitum to four laying hens. The voluntary consumption of food and oyster shell was automatically recorded every 2 h. The hourly consumption of the high Ga diet increased during the afternoon while the daily pattern of consumption was modified by the position of the egg in the clutch.

When the low Ca diet was fed with oyster shell, the daily consumption was increased but the effect of the position of the egg in the clutch was reduced. The ingestion of oyster shell was very high between 16.00 and 20.00 h when egg calcification was in progress; after the last oviposition of the clutch this elevated level of intake remained though to a lesser degree. In relation to the stage of egg formation, the voluntary intake of oyster shell increased sharply between 4 and 12 h after the former oviposition.

These results confirm that the laying hen can discriminate between food and calcium intake. It seems that appetite for calcium is firstly related to light‐dark cycles with a modulation of the afternoon peak by ovulation and then egg shell calcification.     

Thyroid hormone periodicity in healthy adult geldings

Serum samples were collected from 10 healthy geldings every 4 h for three consecutive days and the triiodothyronine (T3) and thyroxine (T4) concentrations determined by radioimmunoassay. There were significant differences in the hormone concentrations related to time. The mean (+/- sd) T3 concentration peaked around 08.00 h at a level (54.06 +/- 14.02 ng/dl) significantly (P less than .001) higher than the lowest concentration (38.71 +/- 10.81 ng/dl) around midnight. Although the highest mean T3 level was 08.00 h, this value was not significantly different from the noon and 16.00 h levels. Likewise, the mean T3 level at midnight was not significantly different from the 20.00 h and 04.00 h levels, resulting in a plateau from 08.00 h to 16.00 h and a trough from 20.00 h to 04.00 h. The mean (+/- sd) T4 concentration peaked around 16.00 h at a level (2.43 +/- .81 micrograms/dl) significantly (P less than .01) higher than the lowest concentration (1.79 +/- .63 micrograms/dl) around 04.00 h.     

Evaluation of whelks as an alternative source of calcium in laying hens

Currently ground limestone and oyster shell are the common sources of calcium for laying hens. Processed whelk (Buccinum undatum) shell contains approximately 34.8% calcium, very similar to the 38% value for commercial oyster shell and ground limestone. The objective of this study was to evaluate the effect of feeding whelk shells to laying hens on performance, egg and bone quality, and calcium balance. White Leghorn hens were fed a basal diet and either one-third large particle oyster shell (>1.4-4 mm) + two-thirds ground limestone (OS/GL), one-third large particle whelk shells (>1.4-4 mm) + two-thirds ground whelk (W/GW), 100% ground limestone (GL), or 100% ground whelk shells (GW) starting at 20 wk of age for 14 28 d periods. Production data were comparable among calcium sources for the first 8 periods of production. During periods 9 to 14, feed consumption for hens fed GW was lower (P < 0.05) than for hens fed OS/GL. For periods 12 to 14, hens fed W/GW consumed less feed (P < 0.05) than those fed OS/GL and GL. Body weights were less (P < 0.05) for hens fed both forms of whelks at the end of periods 12 to 14. Egg production was not affected (P < 0.05) by treatment up to period 10. During period 11, egg production was lower (P < 0.05) for the hens fed GW compared to OS/GL and GL. For periods 12 to 14, hens fed both forms of whelks produced lower (P < 0.05) numbers of eggs than those fed OS/GL and GL. Hens fed GW produced fewer (P < 0.05) eggs than those fed W/GW. Feed conversions for hens fed W/GW and GW were less efficient (P < 0.05) during periods 12 to 14. Higher environmental temperatures occurred during periods 12 to 13, which may have negatively affected the performance of hens fed whelks. However, there were no differences (P < 0.05) among treatment means for egg weight, egg specific gravity, and shell breaking strength. GW resulted in a lower (P < 0.05) calcium balance than the other treatments for period 14.     

Parental diet effects on egg component weights and shell quality

An experiment was conducted to investigate the effects of feeding laying hens a low protein and energy diet (LPE), a high protein and energy diet (HPE), and a commercial protein and energy diet (control) on whole egg components, egg weight, and shell quality. The hens were fed their respective diets from 15 to 30 wk of age. At 30 wk of age, egg component weight and percentages were measured along with eggshell quality. The results demonstrated that birds fed the LPE diet had significantly lower albumen, yolk, and total egg weights that the control and HPE groups. The LPE group had significantly lower levels of total albumen protein than the control group. The HPE hens had significantly lower shell thickness and pore concentration than the LPE group, demonstrating that dietary levels of CP and ME can alter not only shell quality component but also albumen protein levels.     

不同日粮组成对蛋鸡生产性能及鸡蛋品质的影响

选用５７６只１５４日龄海赛克斯蛋鸡探讨不同日粮组成对蛋鸡生产性能及鸡蛋品质的影响。共计３个处理，每个处理４个重复，每个重复４８只鸡，全阶梯三层笼养，自由采食、饮水，进行产蛋率大于８０％的饲养试验。试验期为４周。试验结束后，对各处理的产蛋率、只日产蛋量、料蛋比、破蛋率、每千克蛋耗料成本及蛋的品质指标进行统计分析。试验结果表明，采食３种日粮的试鸡在产蛋量、破蛋率、采食量等指标差异不显著（Ｐ＞０．０５），但采食无鱼粉日粮的试鸡料蛋比、死淘率最低，每千克蛋饲料成本最低（Ｐ＜０．０５），且产蛋率最高（Ｐ＜０．０５）。蛋形指数、蛋壳厚度、蛋壳强度、哈氏单位４项指标上３个处理间无明显差异（Ｐ＞０．０５）。     

Calcium intake in relation to ovulation and oviposition when access to oyster shell is time-restricted or unrestricted

White Leghorn hens were fed either a conventional diet containing 40 gCa/kg from oyster shell, or one low in Ca (3 g/kg) with oyster shell offered separately. In experiment 1 access to oyster shell was unrestricted; in experiment 2. Access was time-restricted to the first 6 h of the photophase of the 14L:10D photoperiod. Irrespective of time-restriction, hens offered oyster shell laid heavier eggs, but shell thickness was reduced. On days on which only ovulation occurred, time-restricted hens consumed significantly less Ca than unrestricted hens. In contrast, on days on which only oviposition occurred, time-restricted hens consumed significantly more Ca than unrestricted hens. These results suggest that when access to oyster shell is time-restricted to morning hours Ca consumption occurs in response to a Ca deficit persisting from the previous period of shell calcification.     

Effect of sweet green pepper on yolk color and performance of laying hens

An experiment was conducted to evaluate the effects of sweet green pepper (SGP) on the performance and egg quality of commercial laying hens. A total of 144 Hy Line W36 egg layers were randomly assigned to 4 treatments with 9 replicate groups of 4 hens each. Treatments consisted of the following diets: 1) basal diet (BD), 2) BD + 75 ppm SGP, 3) BD + 125 ppm SGP, 4) BD + 225 ppm SGP. The diets contained 2,730 kcal/kg metabolizable energy and 15.5% crude protein. Egg production and egg quality were monitored for 16 weeks. Feed intake, hen-day egg production, egg mass, and feed conversion per dozen were not significantly affected by the addition of SGP to the diets. The addition of 225 ppm of SGP decreased egg weight. Specific gravity, albumen height, Haugh unit, yolk weight, albumen weight, albumen percentage, and yolk yellowness (b*) were not significantly affected by the addition of SGP. The addition of SGP to the diets increased yolk percentage, yolk color using a Roche fan, and yolk redness (a*). Based on these data, SGP was shown to be a useful feed ingredient for laying hens; it can be included in diets without negative effects on performance and egg quality. However, owing to the depression of egg weight with the inclusion of SGP, it may be of interest to producers and industry to control egg size in old layers and possibly improve shell quality. The addition of SGP to the diets impacted yolk color and may be useful in specialty markets.     

Effects of δ-aminolevulinic acid and vitamin C supplementation on iron status, production performance, blood characteristics and egg quality of laying hens

An experiment was conducted to evaluate the effects of laying hen diets supplemented with δ-aminolevulinic acid (ALA) and vitamin C (VC) on productive performance, iron status and egg quality. A total of 252 Hy-line brown commercial laying hens were fed two levels of VC (0 and 500 mg/kg) and three levels of ALA (0, 5 and 10 mg/kg) in a 2 × 3 factorial arrangement from 57 to 63 weeks of age. Each treatment contained seven replicates with six hens in each replicate. Supplementation of the diet with both ALA and VC resulted in a significant increase in egg production during 4-6 weeks (p < 0.05). The haematocrit (HCT), total iron-binding capacity (TIBC), white blood cell (WBC), total protein and albumin concentrations were not affected by the dietary treatments. However, ALA and interactive effect of ALA and VC were observed to increase the RBC, haemoglobin and serum iron concentrations (p < 0.05). In addition, inclusion of both ALA and VC increased blood lymphocyte percentage in relation to hens not supplemented with ALA (p < 0.05). Moreover, single effect of ALA or VC improved (p < 0.05) the yolk colour unit and albumin height from 3 to 6 weeks. The egg shell colour was increased (p < 0.05) by the effect of ALA. The addition of VC also led to an increase (p < 0.05) of the Haugh unit at the end of the experiment. However, neither ALA, nor VC exerted an effect on egg weight, egg shell breaking strength or egg shell thickness. The results demonstrate that dietary ALA and VC supplementation can improve the iron status and egg quality of laying hens.     

洪江雪峰乌骨鸡和罗曼粉蛋鸡鸡蛋营养成分和蛋品质比较

试验旨在比较洪江雪峰乌骨鸡和罗曼粉蛋鸡的鸡蛋营养成分和蛋品质,为洪江雪峰乌骨鸡蛋用新品系选育提供依据。随机选取40周龄的洪江雪峰乌骨鸡(绿壳)、洪江雪峰乌骨鸡(粉壳)和罗曼粉壳蛋鸡各100只,每品种鸡随机分为5个重复,每个重复20只,在相同饲粮和饲养管理方式下进行饲养,45周龄收集鸡蛋检测营养成分和蛋品质指标。结果表明:洪江雪峰乌骨鸡绿壳蛋的蛋黄比例极显著高于罗曼粉壳蛋(P<0.01),蛋重、蛋壳厚度、哈氏单位极显著低于罗曼粉壳蛋(P<0.01),洪江雪峰乌骨鸡粉壳蛋的蛋重和蛋壳厚度极显著低于罗曼粉壳蛋(P<0.01);洪江雪峰乌骨鸡蛋中的多不饱和脂肪酸和硒元素含量均极显著高于罗曼粉壳蛋(P<0.01),洪江雪峰乌骨鸡绿壳蛋胶原蛋白含量极显著高于罗曼粉壳蛋(P<0.01)。综上所述,洪江雪峰乌骨鸡鸡蛋蛋黄比例高,蛋黄多不饱和脂肪酸、胶原蛋白、硒和锰含量高,适合作为优质禽蛋开发。     

氧化鱼油对蛋鸡生产性能、蛋品质及血清抗氧化指标的影响

本试验旨在研究饲粮添加氧化鱼油对蛋鸡生产性能、蛋品质及血清抗氧化指标的影响。选择720只体重相近的38周龄海兰灰蛋鸡,随机分为4个组,每组6个重复,每个重复30只鸡。将新鲜鱼油和过氧化物值(POV)为1 200.10 meq O2/kg的氧化鱼油按不同比例分别加入基础饲粮中,组成新鲜鱼油组(FFO组)、0.25%氧化鱼油组(OFO1组)、0.50%氧化鱼油组(OFO2组)和1.00%氧化鱼油组(OFO3组)。试验期4周。结果表明,试验期内各氧化鱼油组显著降低了蛋鸡的平均蛋重(P<0.05),与FFO组相比,OFO1、OFO2和OFO3组平均蛋重分别降低了0.9%、0.9%和1.7%(P<0.05);氧化鱼油组显著降低了鸡蛋蛋黄颜色和哈氏单位(P<0.05),对蛋壳颜色影响差异不显著(P>0.05);与FFO组相比,OFO3组显著降低了蛋鸡血清谷胱甘肽过氧化物酶活性(P<0.05),显著提高了血清丙二醛含量(P<0.05)。由此可见,蛋鸡饲粮中鱼油被氧化在一定程度上影响了蛋鸡生产性能、蛋品质和血清抗氧化指标。     

维生素E对免疫抑制产蛋鸡生产性能和蛋品质的调控效应

试验探讨维生素E对免疫抑制蛋鸡生产性能和蛋品质的调控效应,选取健康的尼克褐产蛋鸡270只,随机等分为5组,每组3个重复,每重复18只。第Ⅰ组为对照组,第Ⅱ~Ⅴ组为免疫抑制组,对第Ⅱ~Ⅴ组鸡在试验第5、6、7 d进行腿部肌肉注射80 mg/kgBW环磷酰胺(CTX),第Ⅰ组注射等量生理盐水。Ⅰ、Ⅱ组饲喂基础日粮(维生素E含量44.59 mg/kg),Ⅲ、Ⅳ、Ⅴ组在基础日粮中分别添加50、100、200 mg/kg维生素E。结果显示:①免疫抑制产蛋鸡的产蛋率、平均蛋重和平均日采食量显著降低(P<0.05),破蛋率显著升高(P<0.05)。基础日粮中添加50 mg/kg维生素E显著提高免疫抑制产蛋鸡的产蛋率、平均蛋重和平均日采食量(P<0.05),但仍低于对照组Ⅰ(P<0.05);显著降低料蛋比和破蛋率(P<0.05)。②免疫抑制产蛋鸡的蛋壳厚度、蛋壳强度和哈氏单位显著降低(P<0.05),蛋形指数和蛋黄颜色无显著改变(P>0.05);50 mg/kg维生素E添加量显著提高免疫抑制产蛋鸡的蛋壳厚度、蛋壳强度和哈氏单位(P<0.05),与对照组Ⅰ无显著差异(P>0.05)。因此,免疫抑制显著降低产蛋鸡的生产性能和蛋品质;基础日粮中添加维生素E对免疫抑制蛋鸡的生产性能和蛋品质具有明显的调控效应,且以50 mg/kg添加量效果较好。     

Relationships between genetic, environmental and nutritional factors influencing osteoporosis in laying hens

1. The effects upon bone quality of feeding limestone in flour or particulate form and housing type (cage or aviary) in lines of hens divergently selected for high (H) or low (L) bone strength over 7 generations were investigated. 2. As in previous generations, highly significant phenotypic differences between lines were observed in all measured bone traits at peak egg production (25 weeks) and towards the end of production (56 weeks) in both cage and aviary systems. 3. At 25 weeks there were no significant effects on bone variables of feeding particulate limestone although a significant reduction in osteoclast number was observed at this age. By 56 weeks osteoclast numbers were further reduced in hens fed particulate limestone and beneficial effects on some bone variables were observed in this treatment group. 4. The genotypic and dietary improvements upon bone quality were independent and additive at both ages. There were very few interactive effects. 5. Hens with the freedom to move in an aviary environment during the laying period had improved bone status compared to caged siblings. Environmental and genotypic effects were additive. 6. There were no effects of line on egg production although H line hens had slightly higher egg production by 56 weeks. Egg numbers were unaffected by diet. Eggshell thickness and strength were unaffected by line but hens fed particulate limestone had thicker- and stronger-shelled eggs over the production period as a whole. 7. We conclude that; (a) genetic selection is extremely effective in improving bone strength and resistance to osteoporosis; (b) allowing hens freedom to exercise can also improve bone strength but may increase the risk of keel damage if they do not have genetically-improved bone status; (c) feeding hens a particulate form of limestone from 15 weeks onwards can also increase bone strength and eggshell quality; (d) genetics, environment and nutrition all have independent and additive effects on bone status in laying hens but the relative effectiveness of these factors is genetics > environment > nutrition.     

日粮中添加辣诺素对海兰褐蛋鸡产蛋性能和蛋品质的影响

本试验旨在研究日粮中添加辣诺素（辣木和诺丽果的提取物）对蛋鸡生产性能及蛋品质的影响。将产蛋高峰期（22周龄）的海兰褐商品蛋鸡540只随机分为6个处理,每个处理6个重复,每个重复15只鸡。负对照组（NC）饲喂基础日粮,正对照组（PC）饲喂添加50 mg/kg杆菌肽锌的基础日粮,4个试验组分别饲喂添加0.25、0.50、0.75和1.00 g/kg辣诺素（LNS）的基础日粮。试验期24周。结果显示：①日粮处理对蛋鸡试验前期和后期生产性能均无显著影响（P>0.05）,试验后期添加0.50和0.75 g/kg辣诺素有改善料蛋比的趋势（P=0.087）;日粮处理对试验前期和后期鸡蛋蛋形指数、蛋壳强度、蛋壳厚度、蛋黄重和哈氏单位均无显著影响（P>0.05）,但日粮中添加杆菌肽锌和辣诺素有提高蛋壳强度的趋势（P=0.062）,其中以添加0.75g/kg辣诺素组鸡蛋强度最高。②与正、负对照组相比,添加辣诺素显著增加了生蛋黄和熟蛋黄的罗氏蛋黄色比率（P<0.05）,显著降低了蛋黄胆固醇的含量（0.25 LNS组除外）（P<0.05）。③与负对照组相比,添加0.50 g/kg辣诺素显著提高了鸡蛋总黄酮、二十二碳六烯酸（DHA）、卵磷脂、亚麻酸和亚油酸含量（P<0.05）。综合以上试验结果,辣诺素作为饲料添加剂具有提高鸡蛋营养品质的功能,考虑到添加成本,产蛋鸡日粮中添加0.25~0.50 g/kg为宜。     

Effect of excess dietary sodium, potassium, calcium and phosphorus on excreta moisture of laying hens

1. Four experiments were conducted to investigate the effects of dietary concentrations of sodium, potassium, calcium or phosphate on the water intake and excreta moisture of laying hens. A fifth experiment examined the effect on these variables of increasing amounts of 2 different sodium salts (chloride or bicarbonate) and the interactions with 2 levels of dietary phosphorus. 2. All experiments involved individually caged laying hens fed on diets varying in 1 or 2 minerals in replacement for washed sand. The experimental diets contained mineral concentrations that either met or exceeded the expected requirement of the hens. The diets were given for a 7 or 8 d feeding period and food and water intakes were measured and excreta were collected for the last 48 h of each feeding period. These data were corrected for evaporative water loss to the environment during the collection period. 3. Increasing dietary concentrations of sodium, potassium or phosphorus gave linear increases (P<0.001) in the water intake of the laying hens and linear increases (P<0.01) in the moisture content of their excreta. Each 1 g/kg increase in dietary mineral increased the moisture content of the excreta by 9.04 (+/- 1.57), 11.95 (+/- 2.02) and 5.59 (+/- 0.31) g/kg (+/- standard error) for sodium, potassium and phosphorus, respectively. Increasing concentrations of dietary calcium did not significantly affect the water intakes or excreta moisture levels of the laying hens. 4. The fifth experiment showed that, although there was a sodium x phosphorus interaction (P<0.05), the effects of the 2 mineral additions were approximately additive. There were no significant differences (P>0.05) in water intakes or excreta moisture contents due to the 2 different sodium salts (chloride or bicarbonate).     

Effects of dietary particulate limestone, vitamin K3 and fluoride and photostimulation on skeletal morphology and osteoporosis in laying hens

1. Female chicks of a White Leghorn strain were fed three different diets from one day old: control, additional vitamin K3 (10 mg/kg), and a diet containing a combination of additional vitamin K3, sodium fluoride (10 mg/kg) and limestone in particulate rather than powdered form. At 16 weeks photoperiod was increased for half the birds from 8:16 L:D to 16:8 L:D immediately or by one hour per week to the same ultimate photoperiod for the other half. 2. Age at first egg was lower by 4.0 d for birds on the fast lighting regime but there were no overall effects of lighting on bone quality at either 25 or 70 weeks. 3. Additional vitamin K3 resulted in higher proximal tarsometatarsus cancellous bone volumes at 15 weeks and throughout the laying period compared with controls. Plasma osteocalcin concentrations were unaffected by vitamin K3 supplementation during growth. 4. The combination diet resulted in beneficial responses of 12 to 20% in most bone characteristics in hens at 70 weeks. The magnitude of these effects was similar to a previous study involving a particulate calcium source alone (Fleming et al., Poultry Science, 39: 434-440, 1998b). We conclude that the beneficial effects of the combined treatment over the lifetime of the hens were attributable mainly to the presence in the diet of a calcium source in particulate form.     

饲粮钙磷水平对笼养北京白鸡蛋壳质量及产蛋性能的影响

<正> 笼养来航鸡蛋壳质量是尚未完全得到解决的问题。母鸡产蛋后期蛋重增大而沉积钙的能力有限,使蛋壳变薄容易破损。影响蛋壳质量的原因有:蛋鸡对沉积钙的能力,激素的分泌,饲粮钙磷水平与维生素D的含量,磷与钙在血液中的比例,以及钙磷的贮存与动员中互相制约的关系等。     

Effect on shell strength of feeding supplemental sources of calcium to adult laying hens given insoluble grit during the rearing period

1. An experiment was conducted to determine the separate and combined effects of giving insoluble grit during the rearing period and small or large particle size (0.3 mm and 3 to 8 mm in diameter) limestone or oyster shell, as extra sources of calcium, during the laying period. 2. For the entire laying period the extra sources of calcium resulted in improved shell strength but, overall, grit-supplements during the rearing period did not affect either egg shell strength or other performance traits. 3. An analysis for interactions however revealed that limestone of larger particle size coupled with rearing period-grit resulted in improved egg-shell strength during the last quarter of the laying period.