Effects of boron supplementation of adequate and inadequate vitamin D3-containing diet on performance and serum biochemical characters of broiler chickens

In this study, supplementation of two levels (5 and 25 parts per million; ppm) of boron into broiler diets including 125 kg⁻¹(inadequate) and 2000 kg⁻¹(adequate) vitamin D₃as investigated. The effects of supplementation on performance and biochemical characters (Ca, P, Mg, glucose and ) of broilers from 1 to 45 days of age were evaluated. Boron provided significant increases in performances of chicks fed both adequate and inadequate vitamin D₃-containing diets. The improvements in the inadequate vitamin D₃-containing group were higher than that of adequate vitamin D₃-containing group. The boron addition had a positive effect on Ca, P and alkaline phosphatase levels of chicks. Boron might be regarded as beneficial in inadequate vitamin D₃-containing broiler feed.     

Effects of dietary boron supplementation on some biochemical parameters, peripheral blood lymphocytes, splenic plasma cells and bone characteristics of broiler chicks given diets with adequate or inadequate cholecalciferol (vitamin D3) content

(1) The effects of 5 and 25 mg/kg boron supplementation of diets with inadequate (6.25 microg/kg) or adequate (50 microg/kg) cholecalciferol (vitamin D3) content on some biochemical parameters, tibia characteristics, peripheral blood lymphocyte and splenic plasma cell counts of broilers were investigated. (2) Supplementation of the diet with boron affected plasma concentrations of boron, iron, copper and zinc and also tibia boron, zinc and calcium concentrations but did not have any effect on tibia iron or copper concentrations or tibia ash and tibia weight values. (3) Boron supplementation caused significant increases in splenic plasma cell count but decreased the proximal and distal tibia growth plate widths. There was no effect of boron supplementation on peripheral blood alpha-naphthyl acetate esterase (ANAE) content. Whole blood haematocrit and haemoglobin counts were significantly increased by boron supplementation but there were no effects on leucocyte ratios such as eosinophil, basophil, monocyte, lymphocyte and thrombocyte. (4) In general, the findings of the present study support the hypothesis that boron has an important biological role that affects the mineral metabolism of animals by influencing both biochemical and haematological mechanisms.     

Vitamin D3 requirement of young chicks receiving diets varying in calcium and available phosphorus

1. Three battery experiments were conducted with broiler chicks during the 2nd and 3rd week of life. Graded amounts of cholecalciferol (D3) were added to maize-soyabean meal diets that were designed to be (a) severely deficient in available phosphorus (P), (b) marginally deficient in calcium (Ca) or (c) adequate in both available P and Ca. 2. With diets containing 1.0 g available P and 6.3 g Ca/kg (assay 1), graded doses of D3 between 0 and 37.5 mu/kg produced linear (P 0.05) positive responses in both weight gain and tibia ash. With a D3 concentration of 1250 mug/kg, 250 times the requirement recommended by the NRC, bone ash was increased (P 0.05) over that of birds fed 37.5 mug/kg, and neither weight gain nor food intake were reduced. 3. With a P- adequate diet (4.5 g available P/kg) containing 8.5 g Ca/kg (assay 2), weight gain and bone ash increased linearly (P 0.05) upon supplementing the basal diet with 0, 2.5 and 5.0 mug D3/kg. Higher doses of D3 did not elicit further responses, and chicks fed on a diet containing 1250 mug D3/kg gained as fast and had bone ash values that did not differ from those of chicks receiving 5, 10, 20 or 40 mug D3/kg. 4. When the maize-soyabean meal basal diet was fortified with Ca and P to achieve adequate amounts of Ca (10.1 g/kg) and P (4.5 g available P/kg) in assay 3, dietary additions produced results similar to those obtained in assay 2 where P was adequate and Ca was slightly deficient. Again, chicks receiving a surfeit of D3 (1250 mug/kg) exhibited weight gains and bone ash values that were as great as those of chicks receiving 5, 10, 15 or 30 mug D3/kg. 5. It is apparent that young chicks have a high tolerance for excess D3, and chicks fed on diets that are severely deficient in available P continue to respond to D3 in excess of 37.5 mug/kg.     

Effect of supplemental vitamin D3 concentration on concentrations of calcium, phosphorus, and magnesium relative to protein in subcellular components of the longissimus and the distribution of calcium within longissimus muscle of beef steers

The effect of supplementing diets with various levels of vitamin D3 to provide 0, 0.5, 1, and 5 million IU/(steer x d) for 8 d before slaughter on the mineral content and localization of Ca in LM and muscle fragments was studied during the postmortem aging process. Twelve feedlot steers of three biological types were given access to the four levels of vitamin D for 8 d before slaughter. Differential centrifugation techniques were used to determine the concentrations of minerals relative to protein in different muscle fragments on d 3 and 21 postmortem. Electron microscopy visualization of bound Ca indicated that vitamin D3 mobilized Ca from the sarcoplasmic reticulum and transverse tubule system into the myofibrils. Bound Ca was concentrated near the Z-line at the A-band/I-band juncture within the sarcomere. Supplementing steers with 1 and 5 million IU/(steer x d) of vitamin D3 increased (P < 0.05) Ca, P, and Mg concentrations per unit of protein in the cytosol. Soluble cytosolic Ca concentrations were greater (P < 0.05) on d 21 than on d 3 postmortem only when steers were supplemented with 5 million IU/d. Concentrations of Ca, P, and Mg in isolated tissues were increased (P < 0.05) in nuclei and myofibrilar proteins by supplementing steers with 1 and 5 million IU/ (steer x d) of vitamin D3. All supplemental vitamin D3 treatments also increased (P < 0.001) Mg concentrations in the cytosol, regardless of aging treatment, and increased Mg concentrations (P < 0.04) within the mitochondria at d 3 postmortem. Thus, supplementation of feedlot steers with vitamin D3 at levels of 0.5 to 5 million IU/(steer x d) increased Ca concentrations within respiring muscle, resulting in increased bound tissue Ca concentrations. When the respiring muscle was converted to meat, the increased bound tissue Ca resulting from vitamin D3 treatment released Ca concentrations into the cytosol during aging (P < 0.05). Results of this study indicate that vitamin D3 supplementation increased total cytosolic Ca, P, and Mg concentrations in meat.     

ORIGINAL ARTICLE: Effect of the level of cholecalciferol supplementation of broiler diets on the performance and tibial dyschondroplasia

A study was conducted to evaluate four different cholecalciferol levels (NRC; modified), using diets supplemented with 200 (control), 1500, 2500 or 3500 IU/kg of cholecalciferol (VIT‐D3). Each treatment was assigned to 3 pens of 17 broiler chicks of a commercial strain grown in an open‐sided house with sidewall curtains. At 21and 42 days, BW and feed conversion (FCR) were determined. At 42 days, five birds per pen were slaughtered to evaluate tibia and toe ash of the right leg, and incidence and severity of tibial dyschondroplasia (TD) of the left tibia and also measured dressing percentage and breast meat yield. Serum calcium and phosphorus concentrations were also determined. Haemagglutination inhibition antibody titre against Newcastle disease virus and lymphoid organs weight/body weight ratio were also determined. At both 21 and 42 days, the BW of birds fed 1500 IU/kg to 3500 IU/kg of VIT‐D3 was significantly greater than birds fed 200 IU/kg. Similarly, better FCR was observed in birds those fed diets of high level of VIT‐D3. No significant difference was observed for mortality at any age. Better dressing percentage and breast meat yield were noted in birds fed diets containing 2500 or 3500 IU/kg VIT‐D3. Both tibia and toe ash contents were increased (p < 0.05) progressively with increased concentrations of cholecalciferol in feed. The incidence of TD (percentage of birds having TD scores greater than zero) was significantly (p < 0.05) influenced by level of 3500 IU VIT‐D3/kg at 42 days. The severity of TD in birds fed diets containing 200 IU/kg VIT‐D3 was apparently higher than birds fed diets with higher levels of VIT‐D3. Concentrations of calcium and phosphorus minerals in the serum increased progressively with the high level of VIT‐D3 supplementation to birds at both 21 and 42 days of age. Feeding levels of 1500 or 3500 IU of vitamin D3 did positively affect the immune system within the parameters measured. It may be concluded that performance, bone mineralization, blood chemistry and immunity against disease in broilers could be maintained when supplementing high level of VIT‐D3 incorporated in broiler diets.     

肉雏鸡日粮中不同钙、磷、VD_3、锰、锌水平的组合效应的研究

本研究应用５因子５水平部分实施的２次回归几乎正交旋转组合设计，采用玉米－豆粕型基础日粮和４３２只ＡＡ（ＡｒｂｏｒＡｃｒｅｓ）肉用公雏，研究日粮中锰（Ｍｎ）、锌（Ｚｎ）、钙（Ｃａ）、有效磷（ａｖ．Ｐ）、维生素Ｄ３（ＶＤ３）５因素不同添加水平的组合效应，探讨５因素与指标间的相互关系。结果表明，由二次响应面分析得出的生产函数二次曲线稳定点的预测值为３５８．７１，对应５因素组合的预测值分别为Ｃａ＝１．０１％，ａｖ．Ｐ＝０．４９％，ＶＤ３＝２１１０．７５１ＩＵ／ｋｇ，Ｍｎ＝１４１．２５ｍｇ／ｋｇ，Ｚｎ＝１７５．８５ｍｇ／ｋｇ，Ｃａ、ａｖ．Ｐ、Ｚｎ是影响生长的主因素；肉雏鸡日粮中Ｃａ、ａｖ．Ｐ、Ｍｎ、Ｚｎ、ＶＤ３任一因素的添加水平过高都会影响其它４营养素的吸收和利用；Ｍｎ－ＳＯＤ、肝锰、肾锰以及血清钙和磷、肝锌分别是反映Ｍｎ、Ｃａ、ａｖ．Ｐ、Ｚｎ营养状况的敏感指标。     

维生素D对蛋雏鸭生长性能及免疫功能的影响

试验选取1日龄健康、体重相近的金定蛋雏鸭180只,随机分为5个处理组,每个处理6个重复,每个重复6只试鸭。采用玉米-豆粕型基础饲粮,Ⅰ组试验鸭饲喂基础饲粮,Ⅱ～Ⅴ组分别饲喂在基础饲粮中添加110、220、550、1000 IU/kg维生素D的试验饲粮,试验期4周。旨在研究不同维生素D添加水平对1～28日龄蛋雏鸭生长性能及免疫功能的影响,以探讨维生素D的适宜添加量。结果表明,添加550 IU/kg维生素D能显著提高蛋雏鸭平均日增重、降低料重比(P<0.05),显著提高IgA、IgG、T3、T4含量(P<0.05),并显著降低Cort含量(P<0.05)。由此可见,在玉米-豆粕型基础饲粮中添加适量的维生素D可提高蛋雏鸭生长性能及免疫功能。通过二次回归模型分析,估测蛋雏鸭日粮中维生素D的适宜添加量为523.1～560.6 IU/kg。     

Effects of saturated and unsaturated fats with vitamin E supplementation on the antioxidant status of broiler chicken tissues

The influence of fish oil (highly unsaturated) and beef tallow (highly saturated) with vitamin E (100 IU/kg) supplementation on the antioxidant status of broiler chicken cockerels was investigated. Chicks were fed a control diet with no added fat, 40 g/kg each of fish oil and beef tallow diets, respectively, from 11 to 42 days of age. Tocopherol concentration and the rate of lipid peroxidation, thiobarbituric acid reactive substance (TBARS) in liver, fatty acid composition of the liver lipids, blood serum total antioxidant status (TAS), and reduced glutathione (GSH) content were determined. Vitamin E supplementation of the diet increased liver alpha-tocopherol content in chicks regardless of the type of dietary fat. Fish oil diet resulted in higher liver TBARS value while beef tallow diet showed lower values compared to the control diet. Vitamin E supplementation reduced liver TBARS as well as serum GSH, and raised serum TAS for all diets. Serum GSH was the same for vitamin E supplemented diets regardless of the fat supplement. Fish oil diets resulted in a significant increase in hepatic lipid n-3 PUFA content. A significant positive correlation was found between liver TBARS and n-3 PUFA content. No relationships were established, however, between liver TBARS and n-6 PUFA or saturated fatty acids. The results suggest that feeding oils rich in n-3 PUFA increases tissue concentration of these fatty acids, consequently increasing tissue lipid peroxidation and reducing the antioxidative status of broiler chickens. Supplementing high levels of vitamin E with such oils may increase tissue oxidative stability. Serum TAS or GSH may be used as a measure of antioxidative status in chickens.     

维生素A、D对肉鸡钙磷代谢相关激素水平的影响

试验旨在研究维生素A、D对肉鸡钙磷代谢相关激素水平的影响。采用4×4完全随机试验设计,将8日龄健康艾维茵雄性肉鸡384只称重后随机分为16个处理组。每个处理组设3个重复,每个重复8只鸡,试验期5周。其中,维生素A设4个添加水平,分别为1 500、3 000、15 000和45 000 IU/kg日粮。维生素D设4个添加水平,分别为500、1 250、2 500和5 000 IU/kg日粮。结果表明,45 000 IU/kg维生素A组的肉鸡血清BGP含量相对于1 500 IU/kg维生素A组有显著的降低趋势(P=0.08);随着日粮维生素A水平的增加(1 500～45 000 IU/kg),血清CaBP浓度呈趋于显著的一次线性降低趋势(P=0.092),血清维生素D3与CT含量也呈现降低趋势(P=0.12,P=0.18),其中,以15 000、45 000 IU/kg维生素A组较低,尤以45 000 IU/kg维生素A组最低;血清PTH含量呈显著的一次线性增加(P=0.029)。随着日粮维生素D水平的增加,血清维生素D3含量呈趋于显著的一次线性增加趋势(P=0.093),血清BGP浓度也呈一次线性增加趋势(P=0.14);其中,以2 500和5 000 IU/kg时较高,5 000 IU/kg时最高。由此可知,日粮维生素A过量引起肉鸡骨骼钙磷代谢发生障碍与血清CaBP浓度的降低及PTH浓度的增加有关,也与过量维生素A对维生素D的拮抗作用有关。     

Supranutritional oral supplementation with vitamin D3 and calcium and the effects on beef tenderness

Ultimate meat tenderness can be influenced by numerous preslaughter and postmortem management techniques. Increased levels of intracellular Ca2+, through postmortem injection, infusion, or marination, have been shown to improve the tenderness of cooked meat products. Oral supplementation with vitamin D3 effectively increases serum Ca2+ and has been hypothesized to increase muscle Ca2+ content, the activity of muscle proteases, and thus the tenderness of cooked beef. Individual Charolais x Hereford heifers (n = 191) were assigned to an unsupplemented control group or groups that were supplemented via oral bolus (for dose regulation purposes) with one of seven levels of vitamin D3 (1, 2, 3, 4, or 5 x 10(6) IU D3/d, 2 x 10(6) IU DS/d plus 75 g CaCO3 or 4 x 106 IU D3/d plus 75 g CaCO3) for 2, 4, 6, or 8 d antemortem. Individual feedlot performance, serum Ca2+ levels, and carcass data were collected, and eight longissimus steaks/carcass were used to obtain Warner-Bratzler shear force values measured at 2, 7, 14, and 21 d postmortem for longissimus steaks cooked to 70 degrees or 85 degrees C. Cattle supplemented with 4 x 10(6) IU D3/d plus 75 g of CaCO3 had lower daily feed intake (as-fed) and reduced (P < 0.05) average daily gains compared with controls during the 8-d supplementation period. Additionally, supplemented cattle had numerically higher dressing percentages, possibly due to less fill at the time of slaughter, because carcass weights and USDA yield grades did not differ (P > 0.05) across treatment groups. Supplementation with 1, 2, 3, 4, or 5 x 10(6) IU D3/d, for 2 or more days, increased (P < 0.05) serum Ca2+ concentrations compared with controls. Whereas cattle that received additional dietary Ca2+ in the form of CaCO3 had the lowest blood serum Ca2+ concentration. Although blood serum Ca2+ was increased, supplementation with any level of vitamin D3 for any length of time up to 8 d did not improve (P > 0.05) Warner-Bratzler shear force at 2, 7, 14, or 21 d of postmortem aging compared with controls when steaks were cooked to final internal temperatures of either 70 (control means 6.27, 4.91, 4.64, and 3.80 kg, respectively) or 85 degrees C (control means 7.31, 5.32, 4.69, and 4.46 kg, respectively). Results indicated that oral supplementation with vitamin D3 (at high or low doses) for 2 to 8 d before slaughter increased serum Ca2+ concentration but does not improve cooked longissimus tenderness.     

Effects of ethylenediaminetetraacetic acid on phytate phosphorus utilization and efficiency of microbial phytase in broiler chicks

Previous studies have suggested that organic acids may improve P utilization in animals. To evaluate the ability of ethylenediaminetetraacetic acid (EDTA) to improve phytate P utilization and the possible synergistic effect between EDTA and microbial phytase (MP) an experiment was conducted using 360 Ross 308 broiler chicks. The experiment was carried out using a completely randomized design with a 3*2 factorial arrangement (0, 0.1 and 0.2% EDTA and 0 and 500 IU MP). Four replicate of 15 chicks per each were fed dietary treatments including (i) P-deficient basal diet [0.2% available phosphorus (aP)] (NC); (ii) NC + 500 IU MP per kilogram of diet; (iii) NC + 0.1% EDTA per kilogram of diet; (iv) NC + 0.1% EDTA and 500 IU MP per kilogram of diet; (v) NC + 0.2% EDTA per kilogram; and (vi) NC + 0.2% EDTA + 500 IU MP per kilogram of diet. Weight gain (WG), feed efficiency and serum Ca, P and alkaline phosphatase (ALP) were assessed. Addition of 0.2% EDTA to low aP diets resulted in significantly lower feed consumption (FC) and WG, but 0.1% EDTA did not depress WG compared to NC. Phytase supplementation of P-deficient diets significantly improved WG and feed efficiency, but it had no effect on FC. Microbial phytase supplementation significantly decreased ALP concentration. Results obtained in our study suggest no synergistic effect between phytase and EDTA in broiler chicks.     

Restriction of vitamin A and D in beef cattle finishing diets on feedlot performance and adipose accretion

Feedlot producers often exceed NRC recommendations for vitamin A and D supplementation; however, increased concentrations of these vitamins have been shown to limit adipocyte differentiation in vitro. A feedlot trial was conducted using 168 Angus crossbred steers (BW = 284 ± 0.4 kg) allotted to 24 pens. The experiment had a 2 × 2 factorial arrangement of treatments: no supplemental vitamin A or D (NAND), 3,750 IU vitamin A/kg dietary DM with no supplemental vitamin D (SAND), no supplemental vitamin A and 1,860 IU vitamin D/kg dietary DM (NASD), and 3,750 IU and 1,860 IU vitamin A and D/ kg dietary DM (SASD), respectively. Serum, liver, and intramuscular and subcutaneous adipose tissue retinol concentrations were decreased in (P < 0.001) in cattle fed the no supplemental vitamin A diets (NAND and NASD combined) compared with those consuming supplemental vitamin A (SAND and SASD combined) diets. In addition, intramuscular retinol concentration was 38% less than in the subcutaneous depot. Serum 25(OH)D(3) concentrations were reduced (P < 0.001) during the first 70 d when cattle were fed no supplemental vitamin D diets (NAND and SAND combined); however, liver 25(OH)D(3) concentrations remained unchanged (P > 0.10) through d 184. Serum and liver 25(OH)D(3) concentrations increased (P < 0.001) with vitamin D supplementation (NASD and SASD combined). The DMI, ADG, G:F, and morbidity were not affected (P > 0.10) by dietary concentration of vitamin A or D. There were vitamin A and D interactions (P < 0.03) for backfat thickness and USDA Yield grade. Cattle fed the NAND diet had greater (P < 0.03) Yield grades than other treatments because of greater (P < 0.005) 12th rib backfat thickness in NAND steers than the NASD and SAND steers. Vitamin D concentrations were attenuated and minimal carcass adiposity responses to vitamin D supplementation were observed. Feeding a diet without supplemental vitamin A increased (P < 0.05) Quality grades and marbling scores and tended (P = 0.06) to increase ether extractable lipid of the LM. As retinol and 25(OH)D(3) concentrations in feedlot cattle declined as a result of a lack of dietary supplementation, adipose accretion increased, resulting in elevated Quality and Yield grades. Withdrawal of supplemental vitamin A, D, or both from the finishing diet of feedlot beef cattle had minimal impact carcass composition.     

Effect of selenium and vitamin E content of the maternal diet on the antioxidant system of the yolk and the developing chick

1. The effects of selenium and vitamin E supplementation of the maternal diet on their transfer to the egg yolk and tissues of the newly hatched chick and on the development of the antioxidant system in the chick liver in early postnatal life were investigated. 2. One hundred Cobb broiler breeder hens were divided into 10 equal groups and housed in pens at 25 weeks of age. Each hen received 1 of the treatment diets which included 0.2 or 0.4 mg/kg selenium, 40, 100, 200 mg/kg vitamin E or their combination. After 6 weeks, the hens were artificially inseminated once per week. From week 8, eggs were collected and placed in an incubator. After hatching, chicks from each group were reared (under standard commercial conditions) to 10 d of age. The chicks were fed on a standard starter commercial broiler diet. At the time of hatching, and at 5 and 10 days old, 4 chicks from each group were sacrificed and blood, liver and brain were collected for the subsequent biochemical analyses. 3. The inclusion of organic selenium or vitamin E in the commercial diet significantly increased their concentration in the egg and in the liver of 1-d-old chicks obtained from the eggs enriched with these substances. A positive effect of such dietary supplementation was seen at d 5 and d 10 of postnatal development. 4. There was a positive effect of selenium supplementation of the maternal diet on glutathione concentration in the liver of 1-d-old and 5-d-old chicks. A combination of a dietary selenium supplementation with high vitamin E doses further increased glutathione concentration in the liver. Dietary selenium supplementation significantly increased selenium-dependent glutathione peroxidase (Se-GSH-Px) activity in the liver of the 1-d-old and 5-d-old chicks and decreased liver susceptibility to peroxidation. 6. It is concluded that the nutritional status of the laying hen determines the efficiency of the antioxidant system throughout embryonic and early postnatal development of the offspring.     

Dietary cholecalciferol and phosphorus influence intestinal mucosa phytase activity in broiler chicks

1. The role of cholecalciferol and phosphorus in the regulation of intestinal mucosa phytase was investigated in broiler chicks. 2. A total of 144 7-d-old male broiler chicks were grouped by weight into 6 blocks of 4 cages with 6 broiler chicks per cage. Four maize-soybean meal-based mash diets were randomly assigned to cages within each block. The 4 diets consisted of cholecalciferol at 0 or 75 microg/kg and total phosphorus at 3.6 or 7.0 g/kg in a 2 x 2 factorial arrangement. The birds were given the experimental diets for 12 d under conditions which excluded ultraviolet light. 3. Broiler chicks fed on diets with the higher concentration of cholecalciferol had higher Vmax and Km of the mucosa phytase, weight gain, feed intake, feed efficiency and percentage tibia ash, higher ileal digestibility of dry matter, energy, phosphorus (P) and calcium (Ca), and increased retention of dry matter, nitrogen, P, Ca and energy. 4. Broiler chicks receiving diets with the higher P concentration showed lower Vmax and Km of the intestinal mucosa phytase but greater weight gain, feed intake, feed efficiency and percentage tibia ash, higher ileal digestibility of dry matter, energy, P and nitrogen, and increased retention of dry matter, energy, nitrogen and Ca. 5. In conclusion, both dietary P and cholecalciferol influenced the activity of intestinal mucosa phytase.     

Effects of microbial phytase and 1,25-dihydroxycholecalciferol on the absorption of minerals from broiler chicken diets containing different levels of calcium

The aim of this study was to investigate the effect of various calcium:total phosphorus (Ca:tP) ratios due to addition of microbial phytase and 1,25-dihydroxycholecalciferol [1,25-(OH)2D3] on the absorption levels of minerals. In a 42-day experiment repeated three times, 144 day-old male broiler chicks (ISA 220) were divided into six groups of eight chicks each. Diets containing two different (1:1 and 2:1) Ca levels were prepared. Groups 1, 2 and 3 received a diet of 1:1 Ca:tP ratio while Groups 4, 5 and 6 a diet of 1:2 Ca:tP ratio. These diets contained 1,25-(OH)2D3 and phytase in levels of 5 micrograms/kg and 600 FYT/kg, respectively. The faeces was collected to analyse the absorption of minerals. At the end of the study, the absorption levels of Ca, P, Zn, Mn and Cu were increased by the addition of phytase enzyme (p < 0.05). This effect was obvious in the 3rd week. On the other hand, in the 6th week only Ca and P absorption levels were influenced positively by the addition of phytase enzyme. The results proved the positive effect of phytase, an enzyme which is used for increasing the utilisation rate of phytate P, Ca and other minerals in broilers.     

Effects of reduced dietary calcium and phytase supplementation on calcium and phosphorus utilisation in broilers with modified mineral status

1.?The impact of modified mineral status and dietary Ca:P ratio on Ca and P utilisation was measured in chicks with or without phytase supplementation.

2.?In a preliminary study, 4 diets were given to chicks from 3 to 15 d of age: D1 (6·5 g P/kg and Ca:P = 1·5) and D2, D3 and D4 (6·0, 5·4 and 5·0 g P/kg, respectively, and Ca:P = 1·2). Growth performance was similar across diets. Tibia ash was similar in chicks given D1 and D2, but was gradually depressed from D2 to D4 (?22%).

3.?In the depletion period, two groups of chicks, with similar performance, but with different mineral status were achieved by feeding them, from 5 to 15 d of age, diets with a similar Ca:P ratio of 1·2, but containing 6·3 or 5·2 g P/kg.

4.?During the subsequent 11 d of the repletion period, chicks from each of the two previous groups were given one of the 4 diets containing 5·7 g P/kg, but differing in their Ca (8·3 and 5·3 g Ca/kg) and microbial phytase (0 or 1000 FTU, Natuphos®) levels in a 2 × 2 × 2 factorial arrangement.

5.?At the end of the repletion period, the initially depleted chicks could not be differentiated from the non-depleted chicks, indicating the capacity of chicks to compensate for their initial depleted mineral status.

6.?Interaction between dietary Ca and phytase levels was not significant. Phytase improved growth performance and bone characteristics. Reduced dietary Ca enhanced feed intake and growth rate, but depressed bone dry matter and ash weight.

7.?At the end, diets supplemented with phytase maximised bone ash weight when chicks were fed with a Ca:P ratio of 1·5 but elicited the highest growth rate when chicks were fed with a Ca:P ratio of 0·9.     

Prediction of ingredient quality and the effect of a combination of xylanase, amylase, protease and phytase in the diets of broiler chicks. 2. Energy and nutrient utilisation

1. In order to investigate the effects of xylanase, amylase, protease and phytase in the diets of broiler chickens containing graded concentrations of metabolisable energy (ME), two 42-d experiments were conducted using a total of 2208 broiler chicks (8 treatments with 12 replicate pens in each experiment). 2. Four diets including one positive and three negative control diets were used. Three maize/soybean meal-based negative control (NC) diets were formulated to be identical in available phosphorus (P), calcium (Ca) and amino acids but NC1 contained approximately 0.17 MJ/kg less ME than NC2 and approximately 0.34 MJ/kg less ME than NC3. A positive control (PC) was fed for comparison and was formulated to be adequate in all nutrients, providing approximately 0.63 MJ/kg ME, 0.13% available P, 0.12% Ca and 1 to 2% amino acids more than NC1. 3. The reduction in nutrient density between NC1 and PC was determined using ingredient quality models Avichecktrade mark Corn and Phychecktrade mark that can predict the response to exogenous enzymes in maize/soybean meal-based broiler diets. Supplementation of each diet with or without a cocktail of xylanase, amylase, protease and phytase gave a total of 8 dietary treatments in a 4 x 2 factorial arrangement. The same treatments and diet designs were used in both experiments but conducted in different locations using different batches of maize, soybean meal and minor ingredients. 4. In both experiments, digestibility was improved by the addition of exogenous enzymes, particularly those for P, Ca and certain amino acids. In addition, the supplementation of the PC with enzymes elicited a positive response indicating that over-the-top addition of xylanase, amylase, protease and phytase may offer a nutritionally and economically viable alternative to feed cost reduction. 5. It can be concluded that the digestibility of nutrients by broilers fed on maize/soybean meal-based diets can be improved by the use of a combination of xylanase, amylase, protease and phytase.     

The influence of dietary boron supplementation on egg quality and serum calcium, inorganic phosphorus, magnesium levels and alkaline phosphatase activity in laying hens

This study was performed to investigate the influence of dietary boron (B) supplementation on egg production, interior and exterior egg quality and serum parameters related to egg formation in laying hens. Two hundred and twenty four, 18 week old, Hyline Brown 98 strain hens were assigned to 7 groups with 4 replicates. After 10 days of adaptation the hens were fed for 8 weeks on diets supplemented with 0, 5, 10, 50, 100, 200 and 400 mg/kg (diet) B (H(3)BO(3)). Live weight, feed consumption and egg production were reduced in the 400 mg/kg B supplemented group. Increases were determined in serum Ca, inorganic P and Mg levels and serum ALP activity was not influenced by supplemental B. Boron changed the interior and exterior quality of eggs. In particular, high level of B supplementation reduced live weight, feed consumption and egg production and changed some blood metabolites.     

Effects of Source of Inorganic Phosphorus and Phytase Supplementation on Performance, Physiological Parameters and Bone Mineralization in Broilers

The objective of this study was to eval- uate the effects of inorganic phosphorus source and phytase addition on performance, nutrient digestibility and bone mineralization in broiler chickens. In Exp. 1,150 two-day old, male broiler chicks were fed a corn-soybean meal basal diet supplemented with phos- phorus provided by dicalcium phosphate, tricalcium phosphate or defluorinated rock phosphate. Five cages containing 10 birds were allotted to each of the three treatments. In Exp. 2,120 three-day old, male broiler chicks were fed the basal diet from Exp. 1 supplemen- ted with 0,250,500 ,or 1,000 P-＇rU phytase per kg of diet. Six cages containing five chicks were allotted to each of the four treatments. In Exp. 1, there was no difference in weight gain, feed intake or feed conver- sion as a result of feeding the different sources of in- organic phosphorus. The digestibility of phosphorus was significantly lower （P =0.01 ） for chicks fed di- ets supplemented with tricalcium phosphate than for chicks fed the other two diets. However, despite the lower digestibility, serum phosphorus levels did not differ among the three treatments. For Exp. 2, feedconversion showed a linear improvement （P = 0.03 ） with increasing levels of phytase inclusion （ days 0 to 33 ）. Phytase supplementation resulted in linear increa- ses in the digestibility of dry matter （P = 0.02 ）, crude protein （ P --- 0.04 ） and energy （ P 〈 0.01 ）. Chicks fed 1,000 FTU/kg phytase had significantly higher bone calcium （ P = 0.05 ） and bone breaking strength （P = 0.04 ） than chicks fed the basal diet on day 33. In conclusion, the results of the current study indicated that the performance of birds fed diets sup- plemented with dicalcium phosphate, tricalcium phos- phate or defluorinated phosphate was similar and therefore production costs could be lowered by choo- sing the cheapest inorganic phosphorus source when formulating diets for poultry. When diets were formu- lated to meet dietary phosphorus requirements, the growth of broilers was not enhanced with phytase sup- plementation. However, increases in feed conversion and bone breaking strength and its potential to impact culling and mortality in broiler operations may be suf- ficient justification for the routine inclusion of phytase in diets fed to broilers.     

饲粮维生素D水平对产蛋初期蛋鸭产蛋性能、血液生化及胫骨指标的影响

采用单因子完全随机试验设计研究饲粮维生素D水平对120日龄雌性龙岩麻鸭产蛋性能,血液生化及胫骨指标的影响,进而探讨产蛋初期蛋鸭维生素D需要量。选取1 260只120日龄健康的福建龙岩麻鸭随机分为6个处理,每处理6个重复,每重复35只。各处理组蛋鸭随机饲喂维生素D水平分别为0、800、1 600、2 400、3 200、4 000 IU/kg的试验饲粮。饲养期为21 d。结果表明:维生素D水平对产蛋初期龙岩麻鸭产蛋性能、蛋品质以及血浆钙、磷含量、碱性磷酸酶活性均无显著影响(P>0.05),基础饲料上添加维生素D显著降低血浆中甲状旁腺激素的含量(P<0.05),但各添加组间无显著差异(P>0.05),饲粮维生素D含量显著影响胫骨钙、磷及灰分含量(P<0.05),维生素D水平为800 IU/kg时,获得较好的骨骼质量,维生素D水平对胫骨长度、胫骨管围、折断力、骨密度、骨矿物盐含量无显著影响(P>0.05)。因此,龙岩麻鸭产蛋初期饲粮维生素D适宜添加量为800 IU/kg。