Effects on performance and eggshell quality of particle size of calcium sources in laying hens' diets with different Ca concentrations

Abstract

The objective of this study was to evaluate the effect of particle size of a dietary Ca source on egg production and eggshell quality when added to hens' diets that have different levels of calcium. The experiment was carried out on 216 ISA Brown hens (25 to 70 weeks of age), allocated to 9 groups of 12 replicates (cages), with two birds in each cage. A 3 × 3 factorial arrangement was used, with three dietary levels of calcium (3.20, 3.70 and 4.20 %) and three levels of dietary substitutions (0, 25 and 50 %) of fine particles of limestone (FPL, diameter 0.2-0.6 mm) with large particles of limestone (LPL, diameter 1.0-1.4 mm) as a Ca source. <br><br> The level of Ca in the diet had no effect on egg production, mean egg weight, feed intake, feed conversion ratio or eggshell quality parameters (<i>P</i> > 0.05). Substitution of FPL with LPL did not affect laying performance indices or eggshell quality at 30, 43 and 53 weeks of age (<i>P</i> > 0.05); however, it increased (<i>P</i> < 0.05) eggshell percentage, thickness, density and breaking strength in older hens (69 weeks of age). In conclusion, the results of this study demonstrated that a level of 3.20 % Ca in a layer's diet is sufficient through the entire laying cycle to maintain good egg production and eggshell quality and that partial (25 or 50 %) substitution of fine- with large-particle limestone can, irrespective of the level of Ca in the diet, improve eggshell quality in aged laying hens.

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S.wi atkiewicz1, A. Arczewska-Wosek1, J. Krawczyk2, M. Puchaa2, and D. Jzeak3

1National Research Institute of Animal Production, Department of Animal Nutrition and Feed Science, Balice, Poland

2National Research Institute of Animal Production, Department of Animal Genetic Resources Conservation, Balice, Poland

3Pozna University of Life Sciences, Department of Animal Nutrition and Feed Management, Pozna, Poland Correspondence to: S.wi atkiewicz ([email protected])

Received: 6 November 2014 Revised: 13 May 2015 Accepted: 6 July 2015 Published: 31 July 2015

Abstract. The objective of this study was to evaluate the effect of particle size of a dietary Ca source on egg production and eggshell quality when added to hens diets that have different levels of calcium. The experiment was carried out on 216 ISA Brown hens (25 to 70 weeks of age), allocated to 9 groups of 12 replicates (cages), with two birds in each cage. A 3 3 factorial arrangement was used, with three dietary levels of calcium (3.20,

3.70 and 4.20 %) and three levels of dietary substitutions (0, 25 and 50 %) of ne particles of limestone (FPL, diameter 0.20.6 mm) with large particles of limestone (LPL, diameter 1.01.4 mm) as a Ca source.

The level of Ca in the diet had no effect on egg production, mean egg weight, feed intake, feed conversion ratio or eggshell quality parameters (P >0.05). Substitution of FPL with LPL did not affect laying performance indices or eggshell quality at 30, 43 and 53 weeks of age (P >0.05); however, it increased (P <0.05) eggshell percentage, thickness, density and breaking strength in older hens (69 weeks of age). In conclusion, the results of this study demonstrated that a level of 3.20 % Ca in a layers diet is sufcient through the entire laying cycle to maintain good egg production and eggshell quality and that partial (25 or 50 %) substitution of ne- with large-particle limestone can, irrespective of the level of Ca in the diet, improve eggshell quality in aged laying hens.

1 Introduction

Eggshell quality is one of the most signicant issues in the egg industry. Protection of the embryo from the detrimental effects of various environmental elements, regulation of gas and water exchange, and supplying calcium for embryonic development are the most important functions of the eggshell (Narushin and Romanov, 2002). Insufcient eggshell quality,i.e. low breaking strength or the presence of shell defects, negatively affects the economic protability of egg production, as well as decreasing the hatchability of eggs. Moreover, eggshell quality is also a very important concern for consumers, as high resistance to breaking and lack of shell

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Effects on performance and eggshell quality of particle size of calcium sources in laying hens diets with different Ca concentrations

defects are necessary in order to protect against the penetration of pathogenic bacteria into eggs.

The huge impact of eggshell quality on the protability of the egg industry was proved by several early studies showing that damaged eggs, i.e. eggs with shell defects, account for 6 10 % of all eggs produced (Washburn, 1982; Roland, 1988;Bain, 1997), and most egg deciencies relate to eggshell problems (Pavloski et al., 2012). One of the main concerns is the decrease in eggshell quality with hens age (Al-Batshan et al., 1994; Arpasova et al., 2010), since the incidence of cracked eggs can exceed 20 % in hens late in the production cycle (Nys, 2001). This trend can be attributed to increases in total egg weight without sufcient increases in shell deposition (Roland, 1980), and to disorders in the vitamin D3

Published by Copernicus Publications on behalf of the Leibniz Institute for Farm Animal Biology.

302 S.wi atkiewicz et al.: Ca level and particle size in layers diet and eggshell quality

metabolism in older hens (Abe et al., 1982). For these reasons, there is still a high level of interest in studies of factors affecting eggshell quality, and efcient ways of improving eggshell indices are of critical importance for the poultry industry.

Because of the chemical composition of eggshells, i.e. the fact that 95 % of the shell is made up of calcium carbonate, an optimal supply of Ca to hens is the most important nutritional factor determining eggshell quality. Providing the layer with an optimal amount of Ca is crucial in order to ensure proper calcication of the eggshell; however, the results of several earlier experiments demonstrated that the published values for hens Ca requirements (NRC, 1994) were adequate for optimum shell formation and further increases in Ca dietary level above 3.63.9 % usually had no positive inuence on eggshell quality indices (Leeson et al., 1993;Bar et al., 2002; Keshavarz, 2003; Valkonen et al., 2010; Pastore et al., 2012). The results of some studies have indicated, however, that replacing ne limestone with coarse limestone, which is characterised by prolonged retention times in the gizzard and is dissolved more slowly, thus supplying the hen more evenly with Ca (ensuring the maintenance of an adequate Ca blood level overnight, when the process of shell calcication is intensive), may positively inuence eggshell quality (Guinotte and Nys, 1991; Pavlovski et al., 2003; Koreleski andwi atkiewicz, 2004; Lichovnikova, 2007). Therefore, the aim of this study with laying hens was to evaluate the effect of different dietary Ca levels and particle sizes of the dietary Ca source, i.e., the level of substitution of ne-particle with large-particle limestone, on eggshell quality and egg production indices throughout the entire laying period.

2 Material and methods

2.1 Birds and experimental diets

The Local Cracow Ethics Committee for Experiments with Animals approved all experimental procedures relating to the use of live animals. A total of 216 17-week-old ISA Brown hens, obtained from a commercial source, were placed in a poultry house in cages (two birds per cage) on a wire-mesh oor under controlled climate conditions. The cage dimensions were 30 cm 120 cm 50 cm, equating to 3600 cm2

total oor space. During the pre-experimental period (17 to 24 weeks of age), a commercial laying hens diet (170 g kg1 crude protein, 11.6 MJ/kg apparent metabolisable energy (AMEn) N, 37.0 g kg1 calcium and 3.8 g kg1 available phosphorus) was offered ad libitum.

At week 25, the hens were randomly assigned to one of nine treatments, each comprising 12 replicates (cages) with two hens in each cage, and fed experimental diets until week70. The composition of the experimental cerealsoybean diets is given in Table 1. During the experiment, the hens had free access to mash feed and water and were exposed to a 14 L:10 D lighting schedule. A 3 3 factorial arrangement was

used, with three dietary levels of Ca (3.20, 3.70 and 4.20 %) and with three levels of substitutions (0, 25 and 50 %) of ne particles of limestone (FPL, diameter 0.20.6 mm) with large particles of limestone (LPL, diameter 1.01.4 mm) as a Ca source. The nutritional composition of the experimental diets was calculated based on the chemical composition of raw feedstuffs, and the metabolisable energy value was calculated on the basis of equations from European tables (Janssen, 1989). The chemical composition of the feed materials was analysed using conventional methods (AOAC, 2000). Amino acids were determined in acid hydrolysates, after the initial peroxidation of sulfur amino acids, in a colour reaction with a ninhydrin reagent using a Beckman System Gold 126AA automatic analyser. Calcium content was determined using ame atomic absorption spectrophotometry and phosphorus content was determined using the calorimetric method (AOAC, 2000).

2.2 Measurements

During the experiment, feed intake, and the number and weight of laid eggs were recorded and laying performance, daily egg mass, daily feed intake, and feed conversion per 1 kg of eggs and per individual egg were calculated. At weeks 30, 43, 56 and 69, one egg from each hen was collected to determine eggshell quality, using the EQM (Egg Quality Microprocessor) system (Technical Services and Supplies, York, England) as described by Krawczyk et al. (2013). Another egg was collected for the measurement of shell breaking strength using an Instron 5542 apparatus equipped with a 500 N load cell. The eggs were compressed at a constant crosshead speed of 10 mm min1 and the breaking strength was determined at the time of eggshell fracture.

2.3 Statistical analysis

The data were subjected to statistical analysis using a completely randomised design, in accordance with the general linear model (GLM) procedure of Statistica 5.0 (StatSoft, Inc., Tulsa, OK, USA). All data were analysed using twoway ANOVA. When signicant differences in treatment means were detected by ANOVA (F test), Duncans multiple range test was applied to the individual means. Statistical signicance was considered to be P 0.05.

3 Results and discussion

3.1 Laying performance

Mean egg production, averaged across all dietary treatments throughout the rst phase of the laying cycle (25 to 40 weeks of age), was 95.5 %, egg weight was 59.9 g, daily egg mass was 57.3 g hen1, daily feed consumption was 113 g hen1 and feed conversion was 1.97 kg of feed/1 kg of eggs. Throughout the second phase (41 to 70 weeks) these

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S.wi atkiewicz et al.: Ca level and particle size in layers diet and eggshell quality 303

Table 1. Composition and nutrient content of experimental diets in grams per kilogram of air-dry matter.

Item Reduced dietary Standard dietary Increased dietary level of Ca level of Ca level of Ca

Corn 417.1 423.1 456.1 Wheat 240.0 210.0 150.0 Soybean meal 230.0 236.0 244.0 Rapeseed oil 13.0 19.0 26.0 Limestone 78.0 90.0 102.0 Monocalcium phosphate 12.5 12.5 12.5 NaCl 3.0 3.0 3.0 DL-Methionine 1.4 1.4 1.4 Vitaminmineral premix1 5.0 5.0 5.0

Nutrient content:Metabolisable energy, MJ kg12 11.60 11.60 11.60

Crude protein 170.0 170.0 170.0 Lys 8.35 8.35 8.35 Met 4.10 4.10 4.10 Ca 32.0 37.0 42.0 Total P 3.15 3.15 3.15 Available P 3.90 3.90 3.90

1 The premix provided the following per 1 kg of diet: vitamin A 10 000 IU; vitamin D3 3000 IU; vitamin E 50 IU; vitamin K3 2 mg; vitamin B1 1 mg; vitamin B2 4 mg; vitamin B6 1.5 mg; vitamin B12 0.01 mg; Ca-pantotenate

8 mg; niacine 25 mg; folic acid 0.5 mg; choline chloride 250 mg; manganese 100 mg; zinc 50 mg; iron 50 mg; copper 8 mg; iodine 0.8 mg; selenium 0.2 mg; cobalt 0.2 mg.

2 Calculated according to European Table (Janssen, 1989) as a sum of metabolisable energy (ME) content of components.

characteristics were 92.0 %, 62.4 g, 57.7 g, 117 g hen1 and2.06 kg kg1, respectively, and throughout the entire experimental period (25 to 70 weeks) they were 93.3 %, 61.4 g,57.2 g, 116 g and 2.03 kg kg1, respectively. Neither the dietary level nor the source of Ca (FPL vs. LPL) affected laying performance indices (P >0.05). The results of our study may suggest that 3.20 % Ca in the diet is sufcient to supply hens requirements for egg production and to maintain good laying performance. Similarly, Cufadar et al. (2011) found no differences in egg production, egg weight, egg mass, feed intake and feed conversion ratio when moulted layers were fed diets with 3.0, 3.6 or 4.2 % of Ca. Pelicia et al. (2009) reported that increasing dietary levels of Ca (3.004.50 %) did not inuence laying performance in hens at the end of the production cycle (58 to 70 weeks of age). In contrast, Saafa et al. (2008) showed that, late in the production cycle (58 to 73 weeks of age), hens require more than 3.5 % of Ca in the diet for optimal laying performance, since an increase in Ca dietary levels to 4.0 % improved egg production, egg mass and the feed conversion ratio. More recently, de Araujo et al. (2011) found that the egg performance of laying hens fed a diet with 4.14 % dietary Ca was signicantly higher in comparison with the performance of layers fed diets containing3.92 or 4.02 % of Ca.

The ndings of this experiment conrm the results of sev

eral earlier studies with laying hens, in which the absence of any positive effects of increasing the particle sizes of dietary limestone on egg production and feed conversion ratio was

noted (Cheng and Coon, 1990; Guinotte and Nys, 1991; Koreleski andwi atkiewicz, 2004; Saafa et al., 2008; De Witt et al., 2009). Olgun et al. (2013) even reported that the replacement of ne particles with very large particles of limestone (> 5 mm) negatively affected laying performance, egg mass and feed intake in hens from 25 to 37 weeks of age.

3.2 Eggshell quality

The mean eggshell percentage, averaged across all dietary treatments throughout the experimental period at 30 weeks of age, was 11.0 %; at 43 weeks of age, 10.8 %; at 59 weeks of age, 10.9 %; and at 69 weeks of age, 10.9 % (Tables 25). Mean eggshell thickness averaged 415, 392, 386 and 388 m; eggshell density averaged 87.7, 85.5, 86.6 and87.5 mg cm2; and eggshell breaking strength averaged 48.9,42.5, 41.9 and 40.4 N, respectively, at 30, 43, 56 and 69 weeks of age. Eggshell quality indices were unaffected by dietary Ca levels (P >0.05) at 30, 43, 56 and 69 weeks of age. Thus, the results of our study conrm several earlier ndings indicating that the published NRC (1994) values for the Ca requirements of hens are adequate for obtaining good eggshell quality. Similarly, no effects of dietary Ca level (3.04.2 %) on eggshell quality, i.e. shell breaking strength, relative weight and thickness, were observed in an experiment with moulted hens (Cufadar et al., 2011). Jiang et al. (2013) even reported that laying hens fed diets with high Ca concentrations (4.4 %) had decreased shell thickness

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304 S.wi atkiewicz et al.: Ca level and particle size in layers diet and eggshell quality

Table 2. Effects of dietary treatments on eggshell quality at 30 weeks of age.

Item Dietary % of grit in total amount Standard error Effect ofCa level of calcium carbonate used of the mean

0 25 50 Mean Ca Grit supple- Inter-level mentation action

Eggshell percent, % Reduced 10.72 11.21 11.00 10.98 0.062 0.321 0.185 0.156Standard 10.83 11.22 10.81 10.96 Increased 11.41 11.12 10.95 11.16 Mean 10.98 11.189 10.92

Eggshell thickness, m Reduced 419 413 401 411 3.887 0.335 0.891 0.333Standard 397 412 427 412 Increased 424 427 420 423 Mean 413 418 416

Eggshell density, mg cm2 Reduced 86.5 87.1 85.0 86.2 0.678 0.245 0.538 0.651Standard 85.9 88.6 89.5 88.0 Increased 87.7 88.3 91.0 89.0 Mean 86.7 88.0 88.5

Eggshell breaking strength, N Reduced 48.1 49.1 48.1 48.5 0.648 0.869 0.768 0.727Standard 47.0 50.3 49.0 48.8 Increased 50.8 49.1 48.1 49.3 Mean 48.6 49.5 48.4

Table 3. Effects of dietary treatments on eggshell quality at 43 weeks of age.

Item Dietary % of grit in total amount Standard error Effect ofCa level of calcium carbonate used of the mean

0 25 50 Mean Ca Grit supple- Inter-level mentation action

Eggshell percent, % Reduced 10.70 10.95 10.89 10.85 0.077 0.567 0.886 0.513Standard 10.46 10.82 10.66 10.64 Increased 11.01 10.64 10.62 10.79 Mean 10.72 10.80 10.72

Eggshell thickness, m Reduced 383 404 382 390 4.016 0.593 0.178 0.971Standard 385 399 384 389 Increased 401 405 389 398 Mean 390 402 385

Eggshell density, mg cm2 Reduced 84.6 87.2 85.8 85.9 0.685 0.865 0.871 0.181Standard 83.8 84.9 86.3 85.0 Increased 89.3 83.0 84.6 85.7 Mean 85.9 85.0 85.6

Eggshell breaking strength, N Reduced 42.4 43.6 42.2 42.8 0.554 0.902 0.578 0.854Standard 41.1 44.1 41.2 42.1 Increased 42.5 42.2 42.8 42.5 Mean 42.0 43.3 42.1

in comparison with a control group (3.7 % Ca). In contrast, Saafa et al. (2008) found, in a study with hens late in the production cycle, that eggshell quality, i.e. shell weight, thickness and density, was signicantly improved when dietary Ca levels were increased from 3.5 to 4.0 %. Moreover, the re-

sults of the study with very aged laying hens (58 to 93 weeks of age) indicated that Ca requirements for optimal eggshell quality in hens at that age are slightly higher than the NRC recommendations and amounts, i.e. 3.604.00 % (Bar et al., 2002).

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Table 4. Effects of dietary treatments on eggshell quality at 56 weeks of age.

Item Dietary % of grit in total amount Standard error Effect ofCa level of calcium carbonate used of the mean

0 25 50 Mean Ca Grit supple- Inter-level mentation action

Eggshell percent, % Reduced 10.42 11.04 11.09 10.85 0.062 0.990 0.035 0.599Standard 10.71 10.99 10.89 10.86

Increased 10.78 10.98 10.87 10.87Mean 10.63a 11.00b 10.95b

Eggshell thickness, m Reduced 372 388 386 382 1.495 0.067 0.039 0.579Standard 384 387 388 386

Increased 387 392 392 390Mean 381a 389b 389b

Eggshell density, mg cm2 Reduced 83.8 87.3 87.1 86.1 0.435 0.541 0.197 0.138Standard 84.5 87.7 87.8 86.6

Increased 88.4 86.8 86.5 87.2Mean 85.6 87.3 87.1

Eggshell breaking strength, N Reduced 39.0 41.8 41.3 40.7 0.498 0.203 0.067 0.651Standard 40.1 43.7 44.8 42.9

Increased 41.7 41.8 42.6 42.0Mean 40.3 42.5 42.9

a,b The values in the rows with different letters differ signicantly (P 0.05).

Table 5. Effects of dietary treatments on eggshell quality at 69 weeks of age.

Item Dietary % of grit in total amount Standard error Effect of

Ca level of calcium carbonate used of the mean

0 25 50 Mean Ca Grit supple- Inter-level mentation action

Eggshell percent, % Reduced 10.61 10.96 11.05 10.87 0.037 0.263 0.010 0.590

Standard 10.92 11.04 11.09 11.02

Increased 10.84 10.99 10.98 10.94Mean 10.79a 11.00b 11.05b

Eggshell thickness, m Reduced 369 387 396 384 1.805 0.277 0.014 0.113

Standard 383 389 391 388

Increased 390 392 391 391Mean 381a 389b 393b

Eggshell density, mg cm2 Reduced 83.6 86.9 88.2 86.2 0.522 0.160 0.022 0.917

Standard 85.7 89.1 88.7 87.8

Increased 87.4 89.1 89.4 88.6Mean 85.5a 88.4b 88.8b

Eggshell breaking strength, N Reduced 39.4 41.3 39.9 39.2 0.485 0.135 0.009 0.456

Standard 38.5 42.7 43.2 41.5

Increased 40.2 41.0 40.4 40.5Mean 38.3a 41.7b 41.2b

a,b The values in the rows with different letters differ signicantly (P 0.05).

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306 S.wi atkiewicz et al.: Ca level and particle size in layers diet and eggshell quality

The source of Ca in the diet had no effect on eggshell quality at 30 and 43 weeks of age; however, substitutions of ne FPL with LPL increased eggshell percentage and thickness at week 56, as well as eggshell percent, thickness, density and breaking strength at week 69 (P <0.05). These results suggest that the use of large-particle limestone may improve eggshell quality in aged laying hens irrespective of dietary Ca level. The mechanism of this effect is probably connected with the possibility that the slower solubility of large-particle limestone (grit) and its prolonged retention time in the gizzard also makes Ca available at night, when there is no feed intake by hens but when the shell calcication process is occurring intensively (Roland and Harms, 1973). This would prevent the mobilisation of bone Ca and P reserves, a process which could affect eggshell quality (Farmer et al., 1986).The results of a study by Zhang and Coon (1997) showed that large-particle limestone (> 0.8 mm) with lower in vitro solubility was retained in the gizzard for a longer time, which signicantly increased in vivo solubility and could lead to improved Ca retention in layers. Results corresponding to our ndings were reported by Cufadar et al. (2011), who evaluated the effects of limestone particle sizes in moulted laying hens (76 weeks of age). They found that very large (> 5 mm) limestone particles benecially affected eggshell breaking strength; however, they observed a signicant interaction between Ca dietary level and limestone particle size, such that the positive effect of large-particle limestone was pronounced only when the diet was low in Ca. Saafa et al. (2008) observed a benecial inuence of diet supplementation with coarse limestone on eggshell density; however, neither shell weight and thickness nor the percentage of broken and shellless eggs was affected by limestone particle size. The results of an experiment by Skrivan et al. (2010) showed that the substitution of ne dietary limestone with coarse limestone(0.82.0 mm) can increase shell weight, shell thickness and shell Ca content, both in younger (24 to 36 weeks of age) and older layers (56 to 68 weeks), without any effect on shell breaking strength. In a recent study (Wang et al., 2014) the benecial effect of large-particle limestone on eggshell quality, i.e. eggshell breaking strength, was observed in laying ducks. By contrast, Olgun et al. (2013) found no effect of different sizes of limestone particles on eggshell quality throughout the rst phase of the laying cycle (25 to 37 weeks of age); furthermore, eggshells of hens fed diets with very large particles of limestone contained decreased amounts of Ca.

4 Conclusions

The results of this study suggest that a dietary level of 3.20 %

Ca in the diet is sufcient to maintain optimal egg production and eggshell quality in laying hens throughout the entire experimental period (25 to 70 weeks of age). Partial (25 or 50 %) substitution of ne-particle (diameter 0.200.60 mm)

with larger-particle limestone (1.001.40 mm) can improve eggshell quality, i.e. eggshell percent, thickness, density and breaking strength, in aged laying hens irrespective of Ca dietary level.

Edited by: K. WimmersReviewed by: two anonymous referees

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