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1.
One-day-old broiler chicks were housed on litter treated with 0, 0.9, 3.6, or 7.2 kg of boric acid per 9.3 m2 of floor space. After 15 days, average body weights were 340.7 g, 278.1 g, and 213.2 g for chickens exposed to 0, 3.6, and 7.2 kg boric acid/9.3 m2, respectively (P < or = 0.05). Feed conversion was 1.68 and 2.29 in chickens exposed to 0 and 7.2 kg boric acid/9.3 m2 (P < or = 0.05). In a second experiment, after birds ingested feed treated with 2500 and 5000 ppm of boric acid for 2 weeks, body weights were 254.8 g and 149.6 g, respectively. The chickens in the control group weighed an average of 285.0 g (P < or = 0.05). The 5000 ppm treatment group had a feed conversion of 1.70, vs. 1.45 in the controls (P < or = 0.05). A dose-related feathering abnormality was evident in treated chickens. No significant histopathologic changes were observed. Livability, weight gain, and feed conversion were not adversely affected in broilers as a result of exposure to litter treated with boric acid at recommended levels of 0.4-0.9 kg/9.3 m2. 相似文献
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3.
In this study, supplementation of two levels (5 and 25 parts per million; ppm) of boron into broiler diets including 125 IU kg(-1) (inadequate) and 2000 IU kg(-1) (adequate) vitamin D3 was investigated. The effects of supplementation on performance and biochemical characters (Ca, P, Mg, glucose and AP) 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. 相似文献
4.
《The Journal of Applied Poultry Research》2014,23(4):661-670
A total of 750 one-day-old male broiler chicks were randomly fed 5 dietary treatments with 5 replicate pens per treatment. The 5 dietary treatments fed for 42 d were a corn-soybean meal basal diet without antibiotic (control); a mixture of 10 ppm of avilamycin + 60 ppm of salinomycin as antibiotic growth promoters (AGP); 0.1% phenyllactic acid (PLA); 0.2% PLA; and 0.4% PLA. The BW gain and FE were significantly improved in AGP and PLA groups compared with control group. The white blood cells and heterophil counts were significantly higher in the PLA-supplemented groups compared with AGP and control groups, but the heterophil-to-lymphocyte ratio was lower in the control group than other groups. The plasma IgY concentration was significantly increased in birds fed PLA-supplemented diets, but the plasma IgA and IgM concentrations were not different among the treatment groups. In addition, the antibody titer against Newcastle disease virus was significantly higher in PLA-treated compared with control and AGP-treated groups. Neither PLA nor AGP treatments affected the cecal aerobes andSalmonella content; however, cecalLactobacillus population increased in chickens fed 0.1% PLA, and total coliform bacteria population significantly decreased in chickens fed various levels of PLA and AGP. Dietary supplementation of PLA did not affect the pH, lightness, and redness of breast meat, but the water-holding capacity and shear force value increased and the yellowness decreased significantly when birds were fed PLA. It was concluded that dietary supplementation of 0.1 and 0.2% PLA improves BW gain and FE of broiler chickens. In addition, PLA supplementation increases the immune characteristics and the number of lactic acid bacteria, decreases the number of coliform bacteria, and improves the meat quality attributes of broiler chickens. Thus, dietary PLA could be a viable alternative to antibiotics in broiler diets. 相似文献
5.
Role of litter in the transmission of Campylobacter jejuni 总被引：3，自引：0，他引：3
Autoclaved or non-autoclaved used broiler litter that was experimentally contaminated with Campylobacter jejuni was capable of infecting specific-pathogen-free chicks maintained in modified Horsfall isolators. Artificially infected chicks became fecal shedders of C. jejuni, resulting in contamination of both autoclaved and non-autoclaved used broiler litter. Fecal shedding of C. jejuni by litter-reared, artificially infected chicks persisted for at least 63 days after chicks were transferred to an isolation unit with a wire floor, which prevented coprophagy. C. jejuni was consistently recovered from water and litter in units housing directly and indirectly infected birds, indicating environmental contamination. These experiments demonstrate the potential role of litter in the perpetuation and transmission of C. jejuni infection in commercial chickens. 相似文献
6.
Sublines of chickens selected for high antibody (HA) or low antibody (LA) response that differed at the major histocompatibility complex (MHC) were tested for response to Eimeria tenella. In Expt. 1, the first exposure to E. tenella was natural (in floor pens), and chicks were challenged orally 21 days later with 0, 928, or 1855 oocysts. In Expt. 2, chicks were reared in wire-floored batteries, vaccinated orally with 928 oocysts, and challenged orally 12 days later with 15,844 oocysts. Corticosterone (20 mg/kg) was mixed with feed from 24 hr before vaccination to 120 hr after vaccination in Expt. 2. In Expt. 1, LA chicks had more-severe cecal lesions but gained relatively more body weight after challenge than did HA chicks. In Expt. 2, cecal lesions were least severe in HA chicks that had been fed corticosterone, most severe in LA chicks fed corticosterone, and intermediate in chicks that were not fed corticosterone. No differences in response to E. tenella occurred as a result of haplotypes at the MHC. 相似文献
7.
The experiments examined the physiological response of growing cockatiel chicks to varying levels of dietary vitamin A (VA) or beta-carotene and the rate of liver VA uptake. Adult cockatiels breeding pairs (n=10 pairs) were fed a VA-deficient diet for approximately 90 days prior to onset of egg laying. Breeding pairs were then allowed to feed their chicks diets containing either 0 IU VA/kg, 4000 IU VA/kg, or 2.4 mg beta-carotene/kg. After 5 weeks, chicks fed 0 IU VA developed poor feathering, facial dermatitis and reduced body weight (p<0.05). Liver VA was higher in chicks fed 4,000 IU VA or 2.4 mg beta-carotene vs. those fed 0 IU VA (p<0.05). Duodenal beta-actin and 15,15'-dioxygenase mRNA expression was similar to that of growing chickens, and greatest for cockatiel chicks fed 0 IU VA (p<0.01). Chicks fed 0 IU VA had keratinization of the bursa and oral mucosa, and reduced bursa development and lymphocyte density (p<0.05). Finally, when chicks fed 0 IU VA were orally gavaged with 20 IU VA/g body weight, maximal liver retinol uptake occurred between 0 and 24 h and reached a plateau at 36 h. These data demonstrate that VA deficiency can be prevented with 4,000 IU VA/kg diet or 2.4 mg beta-carotene/kg diet, although beta-carotene conversion to VA may be lower in cockatiels than chickens. 相似文献
8.
L. S. Meriwether B. D. Humphrey D. G. Peterson K. C. Klasing E. A. Koutsos 《Journal of animal physiology and animal nutrition》2010,94(5):e115-e122
These trials examined whether the demonstrated effects of embryonic and dietary carotenoid exposure on the inflammatory immune response in fast growing chickens also occur in slow growing chickens. The systemic and local inflammatory responses of chicks were examined in two experiments with two in ovo lutein levels (C+, carotenoid replete; or C?, carotenoid‐deplete), two dietary lutein levels (0 or 40 mg lutein/kg diet), and two inflammatory challenges [no exposure or lipopolysaccharide (LPS)‐vaccinated]. At 24 h after LPS vaccination, spleen weight was not affected by diet or in ovo lutein, but liver weight increased from C+ eggs (p < 0.01), and in LPS‐vaccinated chicks fed 0 mg lutein (p < 0.05), but not in chicks fed 40 mg lutein. Plasma carotenoids and liver carotenoids were reduced post‐LPS (p < 0.05). Splenic IL‐6 mRNA abundance was the greatest post‐LPS in C? chicks fed 40 mg lutein vs. C+ chicks fed 40 mg lutein (p < 0.05). Hepatic IL‐6, iNOS and TGFβ and splenic iNOS and TGFβ were not affected by in ovo or dietary lutein. The systemic and local inflammatory results are similar to those observed in fast growing chickens, and support that lutein‐depleted birds have greater inflammatory responses. 相似文献
9.
The effect of used pine-shaving litter from broiler floor pens on Salmonella colonization resistance was evaluated in broiler chicks. One-day-old chicks were placed in floor pens on fresh unused litter or on used litter. All chicks were challenged orally with 10(4) S. typhimurium at 3 days of age. The study was replicated in three trials with used litter that was collected and stored for 1 day (Trial 1), 4 days (Trial 2), or 50 days (Trial 3) before the start of each trial. Cecal concentrations of volatile fatty acids (VFAs) were significantly higher (P < 0.05) in chicks placed on used litter than in chicks on new litter. In all three trials, the number of Salmonella in the cecal contents and the number of Salmonella cecal-culture-positive chicks was significantly lower (P < 0.01) at 10 days and 20 days of age in the chicks on used litter than in the chicks on new litter. The results indicated that newly hatched chicks reared on used litter had higher cecal VFA concentrations and higher resistance to Salmonella colonization than chicks reared on new litter. 相似文献
10.
葡多酚对肉鸡生产性能和免疫机能的影响 总被引：1，自引：1，他引：0
试验旨在探讨日粮中葡多酚对肉鸡生产性能和免疫机能的影响。选用1日龄健康爱拔益加(AA)肉仔鸡公雏鸡240只,随机分配到对照组及试验Ⅰ、Ⅱ、Ⅲ组4个处理组中,空白对照组饲喂基础日粮(不含葡多酚),试验Ⅰ、Ⅱ、Ⅲ组分别在基础日粮中添加葡多酚7.5、15、22.5 mg/kg,试验期42 d。结果表明,在0~3周龄,试验Ⅲ组采食量最高,生长速度较快;在3~6和0~6周龄,试验Ⅰ组日增重和饲料效率最佳,而试验Ⅱ组略低于对照组。葡多酚对肉仔鸡的免疫器官发育无显著影响,7.5 mg/kg葡多酚有增加肉仔鸡外周血中CD3+、CD8+、αβ和γδ T细胞数量的潜力。因此,肉仔鸡日粮中添加适量葡多酚可促进生长,调节免疫机能。 相似文献
11.
A study was conducted to evaluate the effects of ochratoxin A (OA) on Escherichia coli-challenged broiler chickens. Day-old broiler chicks were separated into two groups of 92 chicks each, with one group fed a control mash diet, and the other fed a mash diet containing 2 ppm OA. On day 14, each group was further separated into two groups, with one group inoculated with E. coli O78 (1 x 10(7) colony-forming units/0.5 ml), whereas the other group was not inoculated with E. coli. After E. coli inoculation on day 14, four birds from each group were euthanatized at 1, 2, 3, 5, 7, 10, 14, and 21 days postinoculation. Escherichia coli infection caused dullness, depression, huddling, and diarrhea. Mortality was 14.3% in chicks infected with E. coli but fed no OA. Mortality increased to 35.7% in chicks fed OA and infected with E. coli. Decreased body weight and reduced feed intake were observed in chicks fed OA, and the effects were more pronounced in chicks fed OA and infected with E. coli. Increased serum levels of aspartate aminotransferase, alanine aminotransferase, uric acid, and creatinine and decreased levels of total proteins, albumin, globulins, calcium, and phosphorus were observed in OA-fed birds. Escherichia coli infection did not cause significant alteration in any of the serum biochemical parameters. The presence of OA in poultry rations increased mortality and the severity of an E. coli infection. 相似文献
12.
饲粮添加共轭亚油酸对肉仔鸡肠道黏膜免疫反应的影响 总被引：1，自引：0，他引：1
本试验旨在研究饲粮添加共轭亚油酸(conjugated linoleic acid,CLA)对肉仔鸡肠道黏膜免疫反应的影响。试验选用72只1日龄健康、体重相近的爱拔益加(AA)雄性肉仔鸡,随机分配到对照组和CLA组,分别饲喂基础饲粮和在基础饲粮中添加1%CLA的饲粮,每组6个重复,每个重复6只鸡。21日龄屠宰取样。结果表明:CLA组肉仔鸡空肠食糜分泌型免疫球蛋白A(secretory immunoglobulin A,SIgA)含量(P<0.01)和空肠SIgA基因mRNA表达水平(P<0.01)均高于对照组;饲粮添加CLA显著提高肉仔鸡空肠过氧化物酶体增殖物激活受体γ(PPARγ)基因mRNA表达水平(P<0.01),但转化生长因子β4(transforming growth factor-β4,TGFβ4)基因mRNA表达水平在2组之间没有显著差异(P>0.05);CLA组肉仔鸡Peyer氏结CD8+T细胞亚群百分数(P<0.01)和淋巴细胞转化率(P<0.05)均显著高于对照组。由此可见,饲粮添加1%CLA提高了21日龄肉仔鸡空肠SIgA水平,激活PPARγ可能是CLA调节SIgA表达的途径之一。饲粮添加1%CLA影响21日龄肉仔鸡空肠黏膜细胞免疫功能。 相似文献
13.
A. Abd El‐Wahab C. F. Visscher A. Beineke M. Beyerbach J. Kamphues 《Journal of animal physiology and animal nutrition》2013,97(1):39-47
Foot pad dermatitis (FPD) is a very common disease affecting poultry and is mostly caused by bad litter condition. This study aimed to test the effects of poultry diets with normal levels of electrolytes compared with a surplus level of electrolytes with and without using floor heating. Eighty two‐week‐old ♀ turkey poults were reared over 3 weeks on wood shavings, divided randomly into four groups. Two groups were fed normal levels of electrolytes (1.60 g Na; 7.80 g K/kg diet), and the other two groups were fed surplus levels of electrolytes (3.10; 15.3 g/kg diet). In each dietary treatment, half of the birds were exposed to floor heating. Half of the birds in each group were exposed for 4 h/day to wet litter (35% water) in adjacent separate boxes. External assessment of foot pads was performed weekly. High dietary electrolytes increased the severity of FPD significantly (3.65 ± 1.03). Floor heating is likely to be highly effective in significantly reducing the severity of FPD (2.36 ± 0.588). Despite forced water intake, the litter became drier when floor heating was in use. Combining low Na and K levels with a floor heating system reduced the scores of FPD by approximately 60%, compared with high electrolyte levels without floor heating. Therefore, both dietary electrolyte levels and floor heating markedly affected FPD via litter moisture. 相似文献
14.
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. 相似文献
15.
Effect of virginiamycin on serum carotenoid levels and long, segmented, filamentous organisms in broiler chicks. 总被引：2，自引：0，他引：2
P C Allen 《Avian diseases》1992,36(4):852-857
Virginiamycin (Stafac 20) was mixed with feed at three levels recommended for chickens--5.5, 11, and 22 mg/kg (respectively 5, 10 and 20 g/ton)--and fed to broiler chicks. When fed from 1 day through 2 weeks of age, the drug appeared to retard infection of the lower small intestine by long, segmented, filamentous organisms (LSFOs), and at 2 weeks of age serum carotenoids in treated chicks were significantly higher than levels found in unmedicated chicks. However, as chicks were grown out to 4 and 6 weeks of age, the drug did not completely prevent eventual LSFO infection, even at the highest dose, and mean serum carotenoid levels in treated chicks were not significantly different from levels in control chicks. However, chicks fed at the level of 22 mg/kg had fewer LSFOs. Withdrawal of virginiamycin from treated chicks at 4 weeks of age allowed LSFO infection to occur but did not significantly affect serum carotenoid levels. When the drug was fed for 2 weeks at 22 mg/kg to 2-week-old chicks already infected with LSFOs, the bacteria could no longer be detected, suggesting that virginiamycin may aid the natural decline in LSFO population. Coincident with this treatment, serum carotenoids were higher, but not significantly so. Virginiamycin did not significantly increase the mean body weights of chicks in any of these experiments. 相似文献
16.
Q. Swennen N. Everaert M. Debonne I. Verbaeys C. Careghi K. Tona G. P. J. Janssens E. Decuypere V. Bruggeman J. Buyse 《Journal of animal physiology and animal nutrition》2010,94(3):375-384
The aim of this study was to investigate the influence of isoenergetic substitution between the three energy delivering macronutrients in pre‐starter diets on performance and intermediary nutrient metabolism in broiler chickens. From hatch until 5 days of age, 600 chicks, collected during peak of hatch, were fed one of the three experimental pre‐starter diets with isoenergetic (13 MJ metabolisable energy/kg) substitutions between fat (43 vs. 108 g/kg), protein (126 vs. 240 g/kg) and carbohydrates (391 vs. 510 g/kg). After 5 days, commercial grower and finisher diets were provided. Pre‐starter composition influenced body weight until slaughter age, although not statistically verifiable. Broilers fed the low protein (LP) pre‐starter had the lowest body weight in relation to chickens on the low carbohydrate or low fat pre‐starter diet. After hatch, chicks on the LP pre‐starter diet were able to use the residual yolk sac more rapidly to fulfil their protein requirement, which is reflected in small intestine and liver development. Also, plasma metabolite levels were influenced mostly by the LP pre‐starter, indicating that the main focus for the requirements of newly hatched chicks should be on proteins. Furthermore, optimal nutrition during the first day’s post‐hatch should take into account the contribution of the yolk. 相似文献
17.
1. Two experiments were carried out to study the relationship between growth, liver aspartate aminotransferase (Asp AT) and dietary pyridoxine to determine the pyridoxine requirement of chicks fed on diets containing crystalline essential amino acids with glutamic acid (GA) or diammonium citrate (DAHC) as the non-essential nitrogen source. 2. In one experiment purified diets containing isolated soy-protein with 0 or 3 mg pyridoxine/kg were used. The deficient chicks were significantly lighter, coverted food less efficiently and liver Asp AT activity was decreased. When deficient chicks were offered an adequate diet performance improved and Asp AT activity rapidly increased. 3. In the second experiment diets containing crystalline amino acids GA or DAHC combined with 0, 1 or 3 mg pyridoxine/kg (GA: 0, GA: 1, GA: 3, DAHC: 1, DAHC:3) were used. Growth rates of chicks fed on GA: 1 and GA: 3 were similar, whereas chicks fed on DAHC: 1 were significantly lighter than those given DAHC: 3. The growth data indicated a pyridoxine requirement for chicks fed on the GA diets of not more than 1mg/kg and of more than 1 mg/kg in those fed on diets containing DAHC. Asp AT activity varied significantly with dietary content of pyridoxine but not with the nitrogen source. When Asp AT activity was used to assess pyridoxine requirements, there was nof difference between chicks fed on GA or DAHC diets. 相似文献
18.
《The Journal of Applied Poultry Research》2009,18(2):193-202
Normal or elevated selenium status of broilers, which is influenced by dietary selenium sources, improves the bird’s ability to overcome the adverse effects of reactive oxygen metabolites. The objective of this study was to evaluate the effects of feeding graded levels of peroxidized poultry fat on blood and hepatic glutathione peroxidase (GSH-Px), and hepatic glutathione reductase activity in broiler chickens fed either inorganic sodium selenite (SEL) or organic selenium enriched in the organic selenium yeast product Sel-Plex (SP). Nine starter diets, varying in levels of oxidized fat (0, 3, and 6 mEq/kg) and dietary selenium sources, were fed to 360 male chicks from hatch to 21 d of age. Sel-Plex or SEL was added to the basal diet to provide either 0 or 0.2 ppm of supplemental selenium in the diets. Blood and hepatic samples were obtained for each treatment group at 21 d of age. Neither peroxidized fat nor selenium source significantly altered the activity of hepatic glutathione reductase (P ≤ 0.05). Blood GSH-Px was influenced significantly by both fat and selenium source (P ≤ 0.05), but the fat × selenium source interaction was not significant (P ≥ 0.3). A selenium source effect on the hepatic GSH-Px activity (P ≤ 0.05) was evidenced by higher GSH-Px activity, even in the basal diet with no added peroxidized fat. An increase in GSH-Px activity was seen in the erythrocyte and hepatic samples in both the SEL and SP treatments when peroxidized fat was given at 3 mEq/kg, but in the erythrocytes and in the hepatic tissues from SEL-supplemented birds, there was an apparent inhibition of GSH-Px activity. This inhibition was not seen in the hepatic tissue samples from SP-fed birds. Because elevated GSH-Px activity is indicative of oxidative stress, it was concluded that dietary SP supplementation resulted in better selenium and redox status in broilers than did SEL. These results indicate that the dietary selenium supplied in an organic form (selenium yeast as SP) improved the selenium and redox status in broilers, leading to greater resistance to oxidative stress than when the inorganic form of selenium (SEL) was fed. 相似文献
19.
Effects of feeding growing broiler chickens with practical diets containing sweet lupin (Lupinus angustifolius) seed meal 总被引：1，自引：0，他引：1
1. Two experiments with growing broiler chickens were carried out to study the effects of the inclusion in their diets of whole or dehulled lupin (Lupinus angustifolius) seed meal on productive and physiological parameters. The effects of the addition of a commercial protease (1 g/kg, Bio-Feed Pro, Novo. Nordisk, Madrid) were also tested. 2. Diets were formulated to contain the same amounts of energy (12.55 kJ/g) and protein (210 g/kg). Raw whole (not heat treated) or dehulled sweet (low in alkaloids) lupin seed meal (400 and 320 g/kg, respectively) were used to formulate the lupin-based diets, and the protein content was completed with either defatted soybean or casein. 3. Final body weight and feed intake of chickens fed diets containing whole lupin seed meal (400 g/kg) were lower than controls, but gain:feed ratios were not different. The presence of soybean or casein in the diet did not affect productive parameters. Birds fed dehulled (320 g/kg) instead of whole lupin seed meal had similar body weight, feed intake and gain:feed values to controls. The addition of a commercial protease (1 g/kg, Bio-Feed Pro CT) to whole lupin/soy or whole lupin/casein diets tended to increase feed intake and final weight of the birds. 4. Plasma uric acid concentration was higher, and plasma cholesterol and triglycerides lower, in chicks fed whole lupin but not in those fed dehulled lupin seed meal. Plasma amino acid concentrations were not different from controls in birds fed lupin diets. 5. Apparent ileal digestibility of amino acids was not different from controls for the different lupin diets. The relative weight of the liver was higher than controls in lupin-fed birds, but not in those fed enzyme supplemented lupin-based diets. Liver concentrations of DNA tended to rise, while those of glycogen tended to decrease and liver RNA was lower in lupin-fed chicks. 相似文献
20.
The objective of this study was to evaluate 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 phosphorus 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 supplemented with 0, 250, 500, or 1,000 FTU 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 conversion as a result of feeding the different sources of inorganic phosphorus. The digestibility of phosphorus was significantly lower (P = 0.01) for chicks fed diets 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, feed conversion showed a linear improvement (P = 0.03) with increasing levels of phytase inclusion (days 0 to 33). Phytase supplementation resulted in linear increases 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 supplemented with dicalcium phosphate, tricalcium phosphate or defluorinated phosphate was similar and therefore production costs could be lowered by choosing the cheapest inorganic phosphorus source when formulating diets for poultry. When diets were formulated to meet dietary phosphorus requirements, the growth of broilers was not enhanced with phytase supplementation. However, increases in feed conversion and bone breaking strength and its potential to impact culling and mortality in broiler operations may be sufficient justification for the routine inclusion of phytase in diets fed to broilers. 相似文献