ABSTRACT:The study was conducted to evaluate the effect of zinc and manganese source (inorganic vs. organic) in the diet for hens on laying performance, eggshell quality and chosen parameters of bones. Experiment was carried out on 84 Hy Line Brown hens, from 25 to 70 weeks of age, allocated to seven experimental groups, each containing 12 hens individually caged on wire-mesh floor. All layers were fed the same basal diet contained in 1 kg 52 mg Zn and 30 mg Mn. In experimental treatments basal diet was supplemented with 30 mg Zn/kg and 50 mg Mn/kg and inorganic forms of Zn (ZnO) and Mn (MnO) were gradually replaced (in 0, 50 or 100%) with their organic sources (amino acid complexes). Egg production, egg weight, feed intake and feed efficiency were not affected by dietary treatments. Substitution of Zn and Mn oxides with amino acid complexes of microelements had also no effect on physical and geometrical parameters of tibia, ash content in tibia and in toes, eggshell percent, eggshell thickness and eggshell density, but improved (P < 0.05) eggshell breaking strength in late phase of laying cycle (at 62 and 70 weeks of age). Obtained results indicate that use of organic complexes of Zn and Mn could alleviate the negative effect of hen age on eggshell breaking strength.

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ABSTRACT:The aim of the study was to evaluate the effect of organic acids and the prebiotic fructans on egg production and eggshell quality when added to the layer diet with different levels of calcium and phosphorus. The experiment was carried out on 168 Bovans Brown hens, allocated to 14 groups of 12 replications. Each hen (replication) was kept in an individual cage 40 cm × 40 cm in size. A 2 × 7 factorial arrangement, with two dietary levels of calcium and phosphorus (normal -3.70% Ca, 0.65% P, and reduced -3.25% Ca, 0.60% P) and with diets supplemented by selected additives (none, 0.75% inulin, 0.75% oligofructose, 0.50% volatile fatty acids (VFA), 0.25% medium chain fatty acid (MCFA), 0.30% VFA + 0.20% MCFA, 0.75% inulin + 0.50% VFA) was used. The experiment was carried out over 34 weeks, from the age of 26 to 70 weeks. There were no statistically confirmed effects of the factors studied in this experiment on egg performance, i.e. laying rate, egg mass, feed intake and feed conversion. Reducing the dietary levels of Ca and P significantly decreased eggshell percent, thickness, density and breaking strength. The additives used had a considerable effect on eggshell quality at 46, 58 and 70 weeks of age, and these positive effects were most pronounced in the case of inulin and MCFA. There was no significant interaction between Ca and P dietary levels and the additives used. It was thus concluded that selected feed additives which lower the pH of the diet and intestinal content can beneficially influence eggshell quality in older high-producing laying hens.

An experiment was conducted with 72 Bovans Brown laying hens to determine the effect of dietary crude glycerin on laying performance; egg quality; retention of N, Ca, and P; and metabolizability of energy. The dietary treatments consisted of a control corn-soybean diet containing 6% corn starch (17% CP, 2,775 kcal/kg of AME(n), 0.81% lysine, 0.36% methionine, 3.60% Ca, and 0.37% available P) and 3 experimental diets. In the experimental diets, 2, 4, or 6% crude glycerin (a coproduct of commercial biodiesel production from rapeseed) was substituted for corn starch. During the experimental period (28 to 53 wk of hen age), the dietary level of glycerin had no significant effects on performance indices [i.e., egg production (mean value of all 4 dietary treatments was 95.6%), egg weight (60.4 g), daily egg mass (57.8 g/hen), daily feed consumption (121 g/hen), and feed conversion (0.477 g of egg mass/g of feed consumed)]. No significant treatment effects were found for egg quality parameters (albumen height, Haugh units, yolk color and thickness, density and breaking strength of eggshell), excretion and retention of N, Ca and P, or metabolizability of energy. Linear regression analysis revealed that the AME(n) value of crude glycerol was 3,970 kcal/kg (as-is basis). The results of this study demonstrated that crude glycerin may be incorporated to a level of 6% in the diet of laying hens without any detrimental effect on egg performance, egg quality, nutrient retention, and metabolizability of energy.

In an experiment on 84 Lohman Brown hens (from 26 to 68 weeks of age), the effect of the different dietary levels of maize distillers dried grains with solubles (DDGS) on laying performance and egg quality was studied. Experimental diets were isocaloric and isonitrogenous and contained 0, 5, 10, 15 or 20% DDGS. The diet with 20% DDGS was also supplemented with NSP-hydrolizing enzymes or with enzymes and additional amounts of lysine and methionine. In the first phase of the laying cycle (26-43 weeks of age) the dietary level of DDGS did not significantly affect the laying rate, daily weight of laid eggs, feed intake and feed conversion. In the second phase of the cycle (44-68 weeks of age), there were no differences in egg production parameters between groups fed diets with 0, 5, 10 and 15% DDGS. A dietary level of 20% DDGS negatively affected laying rate and daily weight of eggs, however, addition of NSP-hydrolizing enzymes to the diet reduced in part this negative influence. The level of DDGS in the diet had no effect on albumen height, Haugh units, eggshell thickness, density and breaking, or sensory properties of boiled eggs. Yolk colour score significantly increased when DDGS was included in the diet.

Efficacies of phytase, phosphorolytic enzymes (phytase + acid phosphatase), an enzymic "cocktail" (phytase + acid phosphatase + pectinase + citric acid), a novel Aspergillus niger (fungal) mycelium (FM), and FM enriched in phytase and antioxidants were investigated in growing broilers (Days 1 to 21) fed wheat-based diets. Broilers were fed the following seven diets at 0.69% Ca: 1) a negative control diet, 0.17% nonphytate P (NPP); 2) Diet 1 + 750 phytase units/kg diet; 3) Diet 1 + 750 phytase units + 3,156 units acid phosphatase/kg diet; 4) Diet 1 + 750 phytase units + 3,156 acid phosphatase units + 1,900 units of pectinase/g diet + 3% citric acid; 5) Diet 1 + 4% FM; 6) Diet 1 + 4% FM + 1,300 phytase units + 2% ascorbic acid and 1% of glucose oxidase; and 7) a positive control diet (Diet 1 + 0.24% NPP from dicalcium phosphate). The dietary treatments were fed to four pen replicates of eight birds each. Prior to feed formulation, mycelium and antioxidants dosages were optimized on Diet 1 by an in vitro technique and an experimental design module of a statistical software package. Phytase addition increased BW gain (BWG), feed intake, and P retention. Subsequent addition of acid phosphatase resulted in further increases in BWG, feed intake, and toe ash and reduced digesta viscosity; however, neither P nor Ca retention were improved. Body weight gain and feed intakes superior to those found in chicks fed Diet 7 were observed in birds receiving the cocktail of enzymes (Diet 4) or FM. Chicken fed Diet 6 had the highest percentage of toe ash and retained 76 and 51% of P and Ca, respectively. Supplementation of wheat-based 0.17% NPP diets with FM increased bursa of Fabricius weights and reduced the intestinal surface covered by Peyer's patches.

Chickens from 22 to 42 days of age were fed a basal diet supplemented with α-tocopheryl acetate (150 mg·kg -1 ), extracts of coneflower, thyme or sage (560 mg·kg -1 ), marigold xantophylls (20 mg lutein·kg -1 ), mix of synthetic antioxidants (48.6 mg·kg -1 ) or β-apo-8-carotenoic acid ethylester (40 mg·kg -1 ). On day 42 the chickens were slaughtered, breast muscles were excised, frozen (-20 o C) and stored for 6 months.Dietary supplementation with plant extracts, synthetic antioxidants or pigments did not affect performance. Sage extract increased the level of stearic acid (C 18:0 ), arachidonic acid (C 20:4 ), DHA and n-3 PUFA and decreased oleic acid and α-linolenic acid (C 18:3 ) contents and PUFA n-6/n-3 ratio in lipids of stored breast meat. Additives did not favourably affect TBA-RS values in meat. In chickens fed the control diet or supplemented with 150 mg·kg -1 α-tocopheryl acetate, stored meat contained 1.72 or 6.45 mcg·g -1 α-tocopherol, respectively. Dietary synthetic xantophyll negatively influenced sensory indices in boiled meat.

The rate of phytate P removal from feed (level of dephosphorylation, DL) and the extent to which the molecule of phytic acid is deprived of phosphate moieties (conversion degree, CD) were studied in vitro and in a feeding trial with broilers fed corn-soybean diets. In the in vitro model, phytase A asymptotically increased DL and CD. Phytase B influenced DL only at low dosages of phytase A [0 or 250 phytase activity units (FTU)/kg], but it enhanced CD irrespective of phytase A activity. In the feeding trial, 3-phytase A and 6-phytase A (at 750 FTU/kg) exerted similar effects on broiler performance and similarly influenced bone mineralization, P retention, and Ca retention. Phytase B [6,400 acid phosphatase activity units (ACPU)/kg] enhanced feed intake, BW gain (BWG), toe ash, and P retention but not the retention of Ca. Myo-inositol fed at 0.1% significantly increased BWG, but it reduced P retention. Under conditions of a higher CD (excess of phytase B), 3-phytase A was more effective in enhancing performance than 6-phytase A, but it reduced Ca retention. Lower phytase B activities (0 to 3,200 ACPU/kg) with added 6-phytase A were more necessary for optimal growth of chickens than for enhanced P and Ca retention (4,800 to 6,400 ACPU/kg). The efficacy of both forms of phytase A and phytase B depended on the Ca level in feed. There is enough evidence to conclude that myo-inositol phosphates resulting from simultaneous action of 3-phytase A and phytase B affect bird physiology differently than intermediates accumulated by the action of 6-phytase A and phytase B.