Top PDF THE PERFORMANCE OF LAYING HENS FED DIFFERENT CALCIUM SOURCE

THE PERFORMANCE OF LAYING HENS FED DIFFERENT CALCIUM SOURCE

THE PERFORMANCE OF LAYING HENS FED DIFFERENT CALCIUM SOURCE

Couto et al. (2008) stated that calcium source effect on egg production. The use of calcium carbonate produced higher egg production than dicalcium phosphate (Silva and Santos, 2000). Supplementation of 50% limestone with oyster shell increased egg production (Ahmad and Balander, 2003). Marine calcium can replace up to 45% of calcitic limestone with no effects on performance or egg quality (Pelicia et al., 2007). Lesson and Summers (2005), Safaa et al. (2008) and Saunders-Blades et al. (2009), stated that limestone and oyster shell could be used as a source of calcium for hens feed with no effect on egg production. Oyster shell and limestone both provide Ca in the form of Ca carbonate, and each contain about 38% of Ca (NRC, 1994). Leeson and Summers (2005) stated that oyster shell is more expensive than limestone. Ogawa et al. (2004) stated that eggshell contains 94.4% Ca CO 3 , 0.73% Ca 3 (PO 4 ) 2 , 0.84% Mg CO 3 and 3.3% protein. According to Gongruttananun (2011) eggshell contains 5.35% protein, 34.89% calcium and 0.001% phosphorus. The research results of Schaafsma et al. (2000) showed that eggshell powder contains minerals (Ca, Mg, P, Sr, Zn, Fe, B, Cr, F, Se, N, F and V), protein, amino acids and hormones. The hormones of the eggshell are calcitonin (10-25 ng/g) and progesterone (0.30 to 0.33 ng/g). Nakano et al. (2001) stated that eggshell contains glycosaminoglycans and calcium. The research of Nakano et al. (2002) found galactosaminogycan in eggshell. Nakano et al. (2003) stated that amino acids contained within the eggshell are threonine, serine, glycine, methionine, alanine, isoleucine, valine, tyrosine, phenylalanine, histidine, lysine, arginine, proline and hydroxyproline. Davis et al. (2008) stated that the eggshell contained Salmonella. The cooking temperature of 82.5°C can kill Salmonella of eggshell. Kismiati et al. (2012) reported that fortification phosphorus with H 3 PO 4 5% increased phosphorus content and kill bacteria of the eggshell. Phosphorus is a critical aspect of laying hen nutrition in hot climates (Usayran et al. 2001). Phosphorus from animal products is generally considered to be well utilized (NRC, 1994). Snow et al. (2004) stated that phosphorus level of the feed affected on egg production. Kingori (2011) stated that eggshell
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Cobalt and Vitamin B 12 in Diets for Commercial Laying Hens on the Second Cycle of Production

Cobalt and Vitamin B 12 in Diets for Commercial Laying Hens on the Second Cycle of Production

The supplementation of cobalt and vitamin B 12 in diets for commercial laying hens on the second production cycle w as studied. Four hundred and eighty light commercial laying hens, Lohmann LSL, w ere used at initial phase of forced molting laying period. The trial w as conducted in a randomized design. The plots w ere the treatments w hich w ere constituted by combination of five cobalt levels (0.00; 0.30; 0.60; 0.90 and 1.20ppm) and tw o vitamin B 12 levels (w ithout and w ith 10 µ /kg) , and the split-plots w ere four periods (21, 42, 63 and 84 days) during the second period of production, w ith 4 repetitions and 12 hens per experimental unit. Food and w ater w ere provided ad libitum and eggs w ere collected tw ice daily. Performance and egg quality parameters w ere evaluated. At the end of experimental period, tw o layers from each treatment w ere slaughtered, and liver and blood samples w ere taken for analysis. Performance and egg quality w ere not different (p>0.05) among cobalt supplementation levels, alt h o u g h eg g d am ag e d at a w ere d if f eren t (p < 0 . 0 5 ). Supplementation w ith vitamin B 12 decreased egg w eight. No influence of cobalt or vitamin B 12 supplementation w as seen on the concentration of cobalt in the liver and yolk as w ell as on blood analysis (hematrocrit, hemoglobin, erythrocytes, and leukocytes). The results revealed that vitamin B 12 supplementation w as important for commercial laying hens on the second cycle of production, but not cobalt supplementation.
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Calcium and available phosphorus levels for laying hens in second production cycle

Calcium and available phosphorus levels for laying hens in second production cycle

Keshavarz & Nakajima (1993), Oliveira et al. (1997), and Oliveira (2001) working with Ca levels between 2.80 and 4.40 also did not observe any effect on layer egg weight. As for egg mass, Araujo et al. (2005) worked with 3.5 to 4.2% Ca levels and verified that egg mass increased with increasing dietary Ca levels. In terms of avP levels, Andrade et al. (2003) also did not find any effect on egg weight when feeding layers with 0.094 to 0.494 avP. On the other hand, Barreto (1994) observed that the highest egg weight was obtained when layers were fed 0.34% avP as compared to 0.15 and 0.45% avP. Frost & Roland (1991) fed layers with 0.30, 0.40, or 0.50% avP and observed that egg weight was reduced with 0.30% avP. The differences found by Barreto (1994) and Frost & Roland (1991) relative to the present study are probably due to the lower feed intake verified by the birds in those experiments, which therefore did not consume excessive avP. In the present study, birds with the highest feed intake consumed more avP than those of the experiments of Barreto (1994) and Frost & Roland (1991). This excessive avP was not utilized and excreted, consequently not influencing egg weight. Daghir et al. (1985) recommended 0.25% avP as the minimum level required for average egg weight.
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Estimates of Methionine and Sulfur Amino Acid Requirements for Laying Hens using Different Models

Estimates of Methionine and Sulfur Amino Acid Requirements for Laying Hens using Different Models

There are two main advantages of using the broken- line method compared with the exponential and the second-order methods. Firstly, the broken-line method estimates AA requirements based on the best response, not taking into account safety margins or economic aspects. Secondly, the broken-line method applies to real conditions and objective cases, whereas the other methods are based on hypotheses and subjective cases, such as economic issues. Non-liner exponential and second-order models use a confidence interval (in most cases 95%) with probability of error (5 %), which reduces the accuracy of these two models (Mack et al., 1999; Baker et al., 2002). Also, the highest coefficient of determination of each performance parameters (except for EC) was obtained with broken-line regression. Thus, broken-line regression provided the best estimates of AA requirements. Many researchers reported that broken-line regression is the best method for estimating amino acid requirements (Mack et al., 1999; Baker et al., 2002; Bregendahl et al., 2008), which is consistent with the findings of the present experiment.
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INFLUENCE OF PLANT ESSENTIAL OILS ON SELECTED PARAMETERS OF THE PERFORMANCE OF LAYING HENS

INFLUENCE OF PLANT ESSENTIAL OILS ON SELECTED PARAMETERS OF THE PERFORMANCE OF LAYING HENS

The experiment was designed to investigate the effects of feed supplementation with essential oils on egg weight and body mass of laying hens. Hens of the laying breed Isa Brown were randomly divided at the day of hatching into 3 groups (n=26) and fed for 45 weeks on diets which differed in kind of essential oil supplemented. Hens were fed from day 1 by the standard feed mixture. Laying hens accepted fodder ad libitum. In the control group hens took feed mixture without additions, in the first experimental group the feed mixture was supplemented with 0.25 ml/kg thyme essential oil and in the second one hens got hyssop essential oil in the same dose of 0.25 ml/kg. The housing system satisfied enriched cage requirements specified by the Directive 1999/74 EC. The useful area provided for one laying hen presented 943.2 cm 2 . The equipment of cage consisted of roosts, place for rooting in ashes – synthetic grass, nest
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The effect of essential plant oils on mineral composition of egg mass and blood parameters of laying hens

The effect of essential plant oils on mineral composition of egg mass and blood parameters of laying hens

comparison with control group in shell (P 0.05) and albumen (P 0.05). Significantly (P 0.05) lowest content of potassium was recorded in E2 against control and E1. The contents of iron and manganese in table eggs were not markedly affected of oils addition in feed mixture. Values of manganese were balanced in all groups. The concentration of zinc was significantly (P 0.05) lower after pumpkin and flaxseed oil addition compared to the control in eggs albumen. Significant (P 0.05) differences in content of copper were observed only in eggs yolk and egg shell. Tendency (P 0.05) of a higher copper content in albumen was found in the control group in comparison with experimental groups. Relative to mineral composition, yolks from egg produced by hens fed the control treatment (no oil) were significantly different only from those derived from hens fed the diet supplemented with 2.5% canola oil + 2.5% soybean oil, which presented lower mineral content (Faitarone et al., 2013). The effect of dietary plant extracts added into feed mixture of layers on the content of phosphorus, calcium and magnesium in eggshell were not significant (Lokaewmanee et al., 2014). Herke et al. (2016) also reported that phytogenic additive including essential oil may significantly affect mineral composition in poultry products. In the study of Aydin et al. (2001) who researched effect of conjugated linoleic acid and olive oil on nutritional composition of eggs yolk and albumen contents of Mg, Na and Cl of eggs yolks stored at 4°C for 10 week was significantly higher in eggs from conjugated linoleic acid fed laying hens. The lower concentrations of Ca, Zn and Fe in the yolk were found in the treatment with conjugated linoleic acid compared to the control. In contrast, eggs from laying hens fed the conjugated linoleic acid diet had greater concentrations of Fe, Ca and Zn and lower concentrations of Mg, Na and Cl in albumen relative to eggs from hens fed control diet. Total Fe level in the albumen of the eggs from conjugated linoleic acid fed laying hens was 22-fold greater than those from hens fed control diet. Feeding olive oil along with conjugated linoleic acid
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Performance and egg quality of Embrapa 051 laying hens subjected to different feeding programs

Performance and egg quality of Embrapa 051 laying hens subjected to different feeding programs

The yolk index behaved the same way as the yolk percentage, with lower values for the Lohmann Brown line receiving 100% basal diet (only in the third productive cycle evaluated) and the other three treatments did not differ. This value obtained by the Lohmann Brown line in the third cycle (0.37) was the only one lower than that recommended to maintain the internal quality of the eggs, which is in the range of 0.39 to 0.45 (Eisen et al., 1962). As the weeks pass, the birds produce eggs with higher percentages of yolk, consequently, the yolk index decreases. This may be the explanation for the reduction in this variable to the result obtained by the Lohmann Brown line in the third cycle, since the birds of this line are precocious and may have presented this change in production earlier than the Embrapa 051 line.
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Effect of the levels of calcium and particle size of limestone on laying hens

Effect of the levels of calcium and particle size of limestone on laying hens

tested for the tibia density and stated that bones of poultry fed 3.8% calcium had higher densities than those fed on 1.8% calcium. This proves that the elevated levels of calcium in the diet increases bone density. The best result of the interaction (calcium level and limestone particle size) on bone density coincided with the best result of bone resistance to breakage, which occurred at 4.12% calcium associated with coarse limestone indicating a positive and narrow correlation between results of these two variables. No significant effects (P>0.05) of calcium levels and limestone particle size or their interaction (calcium × size) were observed on the digestive tract proportion to the body weight of laying hens during production stage (Table 7). The result is consistent with the findings of Geraldo et al. (2006), who noted no significant effect of calcium and limestone texture on the digestive tract percentage of laying hens.
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Effects of different levels of expanded perlite on the performance and egg quality traits of laying hens

Effects of different levels of expanded perlite on the performance and egg quality traits of laying hens

ABSTRACT - The influence of different levels of expanded perlite on the performance and egg quality traits was studied in laying hens. Forty Lohmann Brown females at 30 weeks of age were randomly assigned to four groups consisting of five replicates with two hens in each. Four diet groups were supplemented with 0% (control group), 1%, 2%, and 3% perlite, respectively. Feed and water were provided ad libitum. There were no significant differences in final body weight, feed intake, egg yield, and egg weight. Feed conversion ratio and egg weight decreased with addition of 2% perlite. Dietary perlite supplementation has no significant effects on shape, yolk, and albumen index. Haugh unit was affected significantly by addition of 2% perlite. Fecal pH, dry matter, and NH 3 -N did not significantly differ among treatments. Dietary perlite has no negative
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Internal quality of laying hen eggs fed on protease at different storage and stocking conditions

Internal quality of laying hen eggs fed on protease at different storage and stocking conditions

Although fresh eggs are excellent, the maintenance of their chemical and physical characteristics on the market for commercialization is a challenge. Egg processing in Brazil, a tropical country, occurs on farms and the eggs reach the commercial outlets at room temperature when they should have been refrigerated at 10-13°C and relative air humidity of 70- 85%, immediately after laying (Barbosa et al., 2009; Moreng & Avens, 1990). Further, since the refrigeration of eggs is not mandatory, it constitutes a negative point in egg quality. Eggs are normally refrigerated by the final consumer (Figueiredo et al., 2011). So that the benefits provided by eggs are enhanced, costs with feed should be decreased and storing strategies for a longer shelf period at each age should be undertaken, without diminishing their performance.
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Organic Egg Production, Egg Quality, Calcium Utilization, and Digestibility in Laying Hens Fed with Mushroom (Flammulina velutipes) Stem Waste

Organic Egg Production, Egg Quality, Calcium Utilization, and Digestibility in Laying Hens Fed with Mushroom (Flammulina velutipes) Stem Waste

Mushroom and antibiotics were mixed with diet formulated by the National Research Council (NRC, 1994) specification using a feed mixer in a Feed Mill (Jilin Hanghong Animal Husbandry Co. Ltd, China) to treat all the diets equally. All the representative samples in triplicate were obtained and analyzed for proximate components according to the procedures of AOAC, (2004). Nitrogen was determined using an FP- 528 nitrogen determinator (LECO Corporation, USA). The amount of amino acids was measured using a Hitachi L-8800 automatic amino acid analyzer (Hitachi, Japan). The analyzed nutritional composition of the experimental diet and FVW were presented in Table 1.
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Effect of Different Levels of Methionine, Protein and Tallow on the Productive Performance and Egg Quality of Laying Hens in the Late-phase Production

Effect of Different Levels of Methionine, Protein and Tallow on the Productive Performance and Egg Quality of Laying Hens in the Late-phase Production

All experimental procedures used in this experiment were approved by the Animal Care Committee of the Ferdowsi University of Mashhad. A completely randomized experimental design was applied in a 3×2×2 factorial arrangement, with three dietary MET levels (0.35, 0.31 and 0.27%), two dietary PRO levels (14.3 and 12.87%) and two dietary TAL levels (3 and 1%), with a constant level of linoleic acid (1.55 ± 0.02%). One hundred forty-four of 70-wk-old hens layers (Hi-line W36) with initial body weight (BW) of 1,687 ± 15.8 g and similar egg production, egg weight, and egg specific gravity, were used in the experiment. The hens were randomly divided in to 12 combinations of MET, PRO and TAL (4 replicates of 3 hens per treatment). Each three hens were housed in a battery cage (40.6 × 45.7 cm) in a house with temperature maintained as close to 21°C as possible and a 16L: 8D lighting program. All hens were fed an experimental diet from 70 to 76 wk of age. They were supplied with feed and water ad libitum. The experimental diets were formulated to have simila AMEs and minerals levels, according to the nutritional requirements suggested in the Hi-line W36 Commercial Managemnt Gguide (Hy-Line International, 2009-2011). Ingredients and the nutrient composition of the experimental diets are shown in Table 1.
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Effect of the Inclusion of Organic Copper, Manganese, And Zinc in The Diet of Layers on Mineral Excretion, Egg Production, and Eggshell Quality

Effect of the Inclusion of Organic Copper, Manganese, And Zinc in The Diet of Layers on Mineral Excretion, Egg Production, and Eggshell Quality

The maintenance of performance, even at the lower levels of OTM inclusion observed in the present experiment, indicates two important facts. The first is that, due to their greater bioavailability, OTM sources are more efficient to maintain layer production performance and eggshell quality than ITM sources. The second suggests that commercial layer diets current contain excessive amounts of inorganic trace minerals, which is a cause of concern both in terms of egg production and quality, by triggering Table 2 – Excretion (mg/kg) of copper, manganese, and zinc; egg mass (gram of egg/bird/day); and specific gravity of eggs from laying hens in the laying second cycle fed with organic trace minerals.
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Egg Quality of Hens Fed Different Digestible Lysine and Arginine Levels

Egg Quality of Hens Fed Different Digestible Lysine and Arginine Levels

This experiment aimed at evaluating the influence of the supplementation of digestible lysine and digestible arginine at different ratios in the diet fed to layers between 24 to 44 weeks of age on egg quality. In total,320 Lohmann LSL laying hens were allotted according to a completely randomized design in a 2 x 4factorial arrangement, consisting of two digestible lysine levels (700 or 900 mg/kg of diet) and four digestible arginine levels (700, 800, 900,or 1000 mg/kg of diet). Diets contained, therefore, digestible Lys:Arg ratios of 100, 114, 128, and 142 when the diet contained 700 mg digestible lysine per kg of diet, and 78, 89, 100, and 111 when 900 mg digestible lysine per kg was supplemented. The data obtained with digestible arginine levels were fitted to polynomial regression equations, and with digestible lysine, the F test (5% probability) was used to compare the means. The following variables were evaluated: egg weight; internal egg quality (yolk percentage and index, albumen percentage, Haugh units), eggshell quality (specific gravity andeggshell percentage); and whole egg, albumen, and yolk solids content. Digestible lysine and arginine interaction did not affect egg quality. Increasing levels of digestible lysine and arginine reduced eggshell quality and albumen solids, respectively. The levels of these amino acids suggested to improveegg quality are 700 mg digestible lysine and 700 mg digestible arginine/kg of feed at a Dig Lys: Dig Arg ratio of 100.
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Relação treonina: lisina digestíveis em rações com baixo nível de proteína bruta para galinhas poedeiras leves de 24 a 40 semanas de idade Silvana Marques Pastore

Relação treonina: lisina digestíveis em rações com baixo nível de proteína bruta para galinhas poedeiras leves de 24 a 40 semanas de idade Silvana Marques Pastore

This trial was performed to determine the dietary digestible threonine-to-lysine (dig. Thr-to-Lys) ideal ratio for laying hens fed with low-protein diets from 24 to 40 weeks of age. At 24 weeks of age, two hundred forty Hy Line W-36 laying hens were randomly assigned to five treatments, represented by five dig Thr-to-Lys ratios (60; 67; 74; 81 and 88%), with eight replicates each one with six hens per experimental unit. Digestible Thr-to-Lys did not affect laying hen performance and egg quality, except for digestible Threonine intake, which showed linear increase as dig. Thr-to-Lys ratios increased. Linear broken-line model was chosen to analyze data according to lack of fit. According to linear broken- linen estimates, digestible Threonine ideal levels for optimum egg production, egg mass, feed efficiency of lysine utilization for egg mass, feed conversion per egg mass and dozens of eggs and nitrogen balance were 0.610; 0.580; 0.614; 0.599; 0.599 and 0.643%, which correspond respectively to dig Thr-to-Lys ratios of 80; 75; 80; 78; 78 and 83%. The digestible threonine-to-lysine ideal ratio for laying hens from 24 to 40 weeks of age is 80%.
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ENZYME COMPLEX AND WHOLE RICE BRAN ON THE PRODUCTIVE PERFORMANCE AND QUALITY OF EGGS FROM LAYING HENS AT THE SECOND PRODUCTION CYCLE COMPLEXO ENZIMÁTICO E FARELO DE ARROZ INTEGRAL SOBRE O DE- SEMPENHO PRODUTIVO E QUALIDADE DOS OVOS DE POEDEIRAS EM SEGUNDO

ENZYME COMPLEX AND WHOLE RICE BRAN ON THE PRODUCTIVE PERFORMANCE AND QUALITY OF EGGS FROM LAYING HENS AT THE SECOND PRODUCTION CYCLE COMPLEXO ENZIMÁTICO E FARELO DE ARROZ INTEGRAL SOBRE O DE- SEMPENHO PRODUTIVO E QUALIDADE DOS OVOS DE POEDEIRAS EM SEGUNDO

The objective of this study was to evaluate the performance as well as the quality of eggs from birds fed diets containing whole rice bran (RB), with or without the addition of an enzyme complex (EC) with different levels of metabolizable energy value. A total of 480 Hisex brown layers were used. The treatments consisted of diets based on corn (C), soybean meal (SBM), rice bran (RB), with or without the inclusion of the enzyme complex (EC) to the diets. Treatments 1, 2, 3, and 4 consisted of the presence of corn (C), soybean meal (SBM) and treatments 5, 6, 7, and 8 consisted of C, SBM, and 20% RB, with or without the inclusion the EC. Treatments 1, 3, 5, and 7 did not receive CE; however, in treatments 3 and 7 there was energy recovery of 100 kcal / kg (negative controls). The EC was added without energy recovery (on top) to treatments 2 and 6, and valued at 100 kcal / kg in treatments 4 and 8. Birds fed RB produced heavier eggs and yolk. Birds fed RB and that received the EC on top had higher feed intake. The highest Haugh unit and best feed conversion per dozen were observed in birds that received only the control treatment or the control diet supplemented with EC in a diet reformulated to 100 kcal ME/kg.
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Production of laying hens in different rearing systems under hot weather

Production of laying hens in different rearing systems under hot weather

Laying hens may have their performance impaired by stress, which is the main reason and triggers a series of undesirable behaviors, such as aggression, feather pecking and social deviance. The aggressions can be caused both in intensive rearing conditions and in small groups of animals that are kept in a semi-intensive system and can result in serious injuries, high mortality and great variability in production, as observed by Schmid and Wechsler (1997).

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Effects of Dietary Inclusion of Guar Meal Supplemented by &beta;-Mannanase on Performance of Laying Hens, Egg Quality Characteristics and Diacritical Counts of White Blood Cells

Effects of Dietary Inclusion of Guar Meal Supplemented by &beta;-Mannanase on Performance of Laying Hens, Egg Quality Characteristics and Diacritical Counts of White Blood Cells

Abstract: Problem statement: Using Guar Meal (GM) in poultry diets has being limited because of having β-mannan, one of the Nonstarch Polysaccharides (NSP). In this study we try evaluating effects of enzyme supplementation of GM-included diets on productive performance of laying hens. Approach: A total number of 144 Lohmann LSL-Lite hens were divided in 24 cages (n = 6). Based on a 3 × 2 factorial arrangement of treatments, six iso-caloric and iso-nitrogenous diets including 3 levels of GM (0.0, 35.0 and 70.0 g kg −1 ) with and without enzyme (Hemicell® a β-mannanase-based enzyme, 0.0 and 0.6 g kg −1 ) were assigned to hens in 4 cages (replicates). Data was analyzed based on completely randomized design using GLM procedure of SAS. Results: Dietary GM inclusion significantly affected on Egg Production (EP) on weeks 2, 4 and 6 as well as the overall trail period. Hens fed the GM-included diets did have decreased EP compared to hens fed the control diet. Almost the same trend was observed in terms of Egg Mass (EM); so that hens fed the GM-included diets showed decreased EM compared to the hens fed the control diet. Enzyme supplementation did not have significant effect on EP in the present experiment, but EM was significantly improved in the hens fed the β-mannanase-supplemented diets on weeks 3, 6 and the overall experimental period. Dietary inclusion GM increased Feed Conversion Ratio (FCR) of laying hens compared to the hens fed the control diets on weeks 2, 4, 6 and overall trial period. Conclusion/Recommendations: Including GM in laying hens’ diets more than 3% may decrease productive performance. Supplementing corn- soybean or corn-soybean-GM diets by β-mannanase would have beneficial effects on performance of hens especially in terms of FCR and EP.
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Effects on performance and eggshell quality of particle size of calcium sources in laying hens' diets with different Ca concentrations

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

Because of the chemical composition of eggshells, i.e. the fact that 95 % of the shell is made up of calcium carbon- ate, 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 en- sure proper calcification of the eggshell; however, the results of several earlier experiments demonstrated that the pub- lished values for hens’ Ca requirements (NRC, 1994) were adequate for optimum shell formation and further increases in Ca dietary level above 3.6–3.9 % usually had no positive influence on eggshell quality indices (Leeson et al., 1993; Bar et al., 2002; Keshavarz, 2003; Valkonen et al., 2010; Pa- store et al., 2012). The results of some studies have indicated, however, that replacing fine 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 ad- equate Ca blood level overnight, when the process of shell calcification is intensive), may positively influence eggshell quality (Guinotte and Nys, 1991; Pavlovski et al., 2003; Ko- releski and ´Swi ˛atkiewicz, 2004; Lichovnikova, 2007). There- fore, 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 fine- particle with large-particle limestone, on eggshell quality and egg production indices throughout the entire laying period.
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Calcium in pre-laying and laying rations on the performance and quality of laying hens' eggshell

Calcium in pre-laying and laying rations on the performance and quality of laying hens' eggshell

ABSTRACT. The experiment evaluated the effect of different calcium (Ca) levels in pre-laying and laying diets on the performance and egg quality of laying hens. Two hundred and fifty-six 16-week-old Brown Hisex pullets were housed in a conventional shed. The experiment had a completely randomized design with 4 x 2 factorial arrangement (four calcium levels - 0.8, 1.3, 1.8 and 2.3% in pre-laying phase; two calcium levels - 2.5 and 3.5% in laying phase), totaling eight treatments with four repetitions of eight birds per experimental unit. The experiment started with 16-week-old hens receiving pre-laying diets provided until they were 18 weeks old. At this period, the laying diets started. Four 28-day cycles were evaluated for the following variables: production and egg weight, feed intake, feed conversion, mass of eggs and eggshell quality. Results show that a good performance was obtained with 0.8% calcium level in the pre-laying phase, whereas in the laying phase the 3.5% calcium level provided greater weight egg and better eggshell quality.
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