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1.
The objective of this study was to investigate the effects of yeast culture (YC) on the growth performance, caecal microbial community and metabolic profile of broilers. A total of 350 1-day-old healthy Arbor Acres broilers were randomly assigned to seven treatment groups. The first group received a basal diet without YC supplementation, whereas the remaining groups received a basal diet supplemented with either YC fermented for 12, 24, 36, 48 or 60 hr, or a commercial YC product (SZ2). MiSeq 16S rRNA high-throughput sequencing was used to investigate the bacterial community structure, and gas chromatography–mass spectrometry was used to identify the metabolites in the caeca of broilers. The broilers that received a diet supplemented with YC had a higher average daily gain and average daily feed intake than those received YC-free or SZ2-enriched diets. The feed conversion ratio (FCR) of YCs fermented for 24 hr resulted in the best feed efficiency, whereas the FCR of YC fermented for 60 hr resulted in poor feed efficiency (p < .05). In the caeca of broilers, the bacterial communities were well separated, as determined by principal component analysis, and the proportions of the eight genera were significantly different among the seven groups (p < .05). The genus Akkermansia was the most abundant when the diet supplemented with YC fermented for 24 hr (p < .05). Furthermore, the Firmicutes/Bacteroidetes ratio was positively correlated with the FCR in the caecum (r = .47, p < .005). Five differentially expressed metabolites (i.e., L-alanine, benzeneacetic acid, D-mannose, D-arabitol and cholesterol) were identified in the caeca of broilers that received diets supplemented with YCs fermented for 24 or 60 hr. In summary, the different fermentation times of the YCs can markedly improve the growth performance and FCR of broilers by altering the caecal microbial community, and the growth performance which is related to the changes in key metabolic pathways.  相似文献   

2.
To investigate the effects of different levels of enzymatic hydrolysate of dietary locust bean gum on nutrient digestibility, intestinal morphology and microflora of broilers, a total of 768 one-day-old Arbor Acres (AA) broiler chicks were randomly divided into 6 treatments with 8 replicates per treatment and 16 birds per replicate. The treatments were as follows: (1) CON, basal diet; (2) ANT, basal diet +62.5 mg/kg flavomycin; (3) LBG, basal diet +0.1% locust bean gum; (4) ELBG-0.1, basal diet +0.1% enzymatic hydrolysate of LBG; (5) ELBG-0.2, basal diet +0.2% enzymatic hydrolysate of LBG; and (6) ELBG-0.3, basal diet +0.3% enzymatic hydrolysate of LBG. The digestibilities of ether extract, crude protein and dry matter were increased (p < .01) in broilers fed the ELBG-0.3 diet compared with the CON and LBG diets on day 21. Duodenal villus height and the ratio of the villus height to crypt depth were greater (p < .01) in broilers fed the ELBG-0.3 diet than the CON, ANT and LBG diets. Jejunum villus height was higher (p < .05) in broilers fed the ELBG-0.2 and ELBG-0.3 diets than the CON diet. The number of caecal Escherichia coli was reduced (p = .01) in broilers fed the ELBG-0.2 and ELBG-0.3 diets compared with the CON diet. The number of caecal Lactobacilli was greater (p < .05) in broilers fed the ELBG-0.3 diet than the CON and ANT diets. In summary, the addition of 0.3% locust bean enzymatic hydrolysate can increase the surface area of intestinal villi and the number of beneficial bacteria, inhibit the proliferation of harmful bacteria, maintain the balance of intestinal microflora and improve the digestibility of nutrients.  相似文献   

3.
An experiment was conducted with Arbor Acres broiler chickens that were fed 3 experimental diets—a control diet containing an adequate level of available phosphorus (AP) and 2 diets that were deficient in AP but supplemented with phytase at a level of either 500 or 750 phytase units/kg—to assess the effects of a novel microbial phytase supplement in broilers fed AP-deficient diets on growth performance and mineral utilization. Similar average daily gain, feed intake, and feed efficiency (P > 0.05) were obtained among broilers fed different diets. Compared with broilers fed the control diet, broilers fed diets with phytase had greater (P < 0.05) retention of Ca, P, and Zn. Moreover, the levels of Cu, Zn, Mg, and Mn in the tibia bone at 28 d of age, and Zn and Mn at 42 d of age in birds fed diets with phytase exceeded (P < 0.05) those of birds fed the control diet. Supplementation of phytase increased Zn and Mg contents in the plasma at 42 d of age. Birds responded similarly to phytase supplemented at a level of 500 or 750 phytase units/kg in terms of growth performance, mineral retention, and mineral content in the serum and bone. Therefore, with the supplementation of this novel phytase, it is possible to reduce the dietary levels of P and other minerals to below the recommended levels of the Feeding Standard of Chicken in P. R. China (ZB B 43005-86).  相似文献   

4.
1. Performance, gait score (GS), tibial dyschondroplasia (TD), and tibia bone mineralisation and breaking strength were determined in 2880 male and female Ross 208 broilers fed on diets with two different concentrations of dietary metabolisable energy (ME) (11.00 or 12.00 MJ/kg) and 4 different concentrations of available phosphorus (aP) adjusted for dietary ME content (4.0, 4.5, 5.0 or 5.5 g/kg aP in starter and 3.5, 4.0, 4.5 or 5.0 g/kg aP in finisher diets containing 12.00 MJ/kg). 2. Tibia ash, calcium (Ca) and phosphorus (P) contents in broilers given diets with low ME (11.00 MJ/kg) were greater than those of broilers given diets with higher ME (12.00 MJ/kg). Tibia ash, Ca and P contents increased curvilinearly with increasing dietary aP content. The dietary aP level had no effect on GS. 3. Dietary concentration of ME or aP had no effect on tibia breaking strength. 4. Walking ability, as measured by GS, was negatively correlated with the body weight (BW) of tested birds at 23 and 35 d of age, but the dietary ME content or aP level had no significant effect on GS at 35 d of age. 5. The results indicated that bone mineral content had no clear correlation with the walking ability of broilers.  相似文献   

5.
ABSTRACT

1. This study determined the effects of three protein sources (PS), each at two digestibility crude protein (DCP) levels, on performance, gut morphology and fermentation characteristics in the hindgut of broilers.

2. It was hypothesised that broilers fed ingredients high in indigestible CP, i.e. rapeseed meal (RSM) or maize gluten (MG), could potentially cause reduced growth, impaired gut health, and more protein fermentation products in caecal digesta. Increasing the DCP level in each of the indigestible CP diets may compensate for these detrimental effects.

3. In total, 288 one-d-old male Ross 308 broilers were used in a completely randomised 3 × 2 factorial design, with six replicate pens per treatment. Three PS: soybean meal (SBM), rapeseed meal (RSM) or maize gluten (MG), and two DCP levels: 15.8 and 17.2% were used.

4. Broilers fed SBM had increased feed intake and BWG and improved FCR compared with those fed RSM and MG diets. Broilers fed high DCP had better performance compared with those on low DCP. No significant effects of PS or DCP level were found on gastrointestinal tract development, caecal ammonia or volatile fatty acid concentrations.

5. Broilers fed SBM had longer villi, smaller crypts and increased villus height to crypt depth ratio compared with those fed RSM and MG diets. Broilers fed RSM diet had a lower caecal pH, and had 16.5% and 14.9% more branched chain fatty acid contents in caecal digesta compared with those fed SBM and MG diets, respectively, indicating more proteolytic fermentation.

6. Replacing SBM by RSM and MG negatively affected growth performance and gut morphology. Hindgut protein fermentation was substantially increased in RSM fed birds.

7. To a certain extent, retarded growth performance in RSM and MG fed birds could be counterbalanced by increasing the dietary level of digestible CP.  相似文献   

6.
The experiment was carried out on 96 female broilers, allocated to eight groups of 12 birds kept in individual cages. Two basal wheat‐ and soyabean meal‐based diets containing 150 g/kg of rapeseed expeller cake were formulated, differing in the level of P: 7.1 g/kg in diet H or 5.9 g/kg in diet L. Rapeseed cake supplied 3.15 μmol alkenyl glucosinolates per gram of diet. The eight treatments were: basal diets only, basal diets + phytase (1000 U/kg), basal diets + organic acid blend (OA, 6 g/kg), or basal diets + both additives. Diets were fed from day 8 to 28 of life. The results showed that the lower dietary P content and OA supplementation did not significantly affect feed intake or BWG, while both increased (p < 0.001) after phytase supplementation. Tibia ash content as well as tibia ultimate strength were lower (p < 0.001) in birds fed diets L compared with diets H, and increased (p < 0.01) with phytase supplementation of diet L, while OA had no influence on either parameter. Dietary P levels and OA supplementation had no influence on the pH of gut digesta, but the pH of jejunal digesta increased following phytase supplementation (p < 0.01). Morphological measurements of the small intestinal mucosa of chicks indicated that OA added to diet L depressed villi height (p < 0.001) and crypt depth (p < 0.001); both parameters increased after phytase supplementation (p < 0.01). The lower total SCFA as well as acetic, propionic and butyric acid concentrations in caecal digesta indicated lower activity of caecal microflora in birds fed diets L compared with H. OA supplementation had no influence, while phytase supplementation increased the concentration of acetic acid in caecal digesta. Supplementation of diets with either phytase or OA increased thyroid weight by 16% (p < 0.01) and 11% (p < 0.05) respectively. The increase in thyroid weight because of phytase supplementation was greater at the lower dietary P level, and the greatest when both phytase and OA were added to the diet.  相似文献   

7.
肉仔鸡低钙磷日粮添加植酸酶的研究   总被引：1，自引：0，他引：1  
选取160只1日龄AA肉仔鸡,随机分成4组,研究在低钙、磷日粮和正常钙、磷日粮中添加植酸酶对肉仔鸡生产性能及钙、磷利用的影响。结果表明：植酸酶显著提高了肉仔鸡的日增重和采食量,并且以采食低钙、磷加酶日粮的肉仔鸡增重效果最为明显（P＜0．01）;显著降低了采食低钙、磷日粮肉仔鸡的料重比（P＜0．05）。采食低钙、磷加酶日粮肉仔鸡的胫骨灰分、钙含量和血清总钙、无机磷浓度显著提高（P＜0．05）;但采食正常钙、磷加酶日粮肉仔鸡上述胫骨与血清指标变化不大,表明植酸酶促进了肉仔鸡对低钙、磷日粮中钙和磷的吸收利用。  相似文献   

8.
A total of 336 one‐day‐old Hubbard broiler chickens were randomly distributed among 8 groups, each containing six replicates (7 chickens/replicate). From 1 to 40 days of age, the groups fed the same starter, grower and finisher diets. The control group was unsupplemented; zinc bacitracin (ZnB) group received the antibiotic at 0.5 g/kg; fungal phytase (FP) groups received 250, 500 and 1000 U/kg diet of Aspergillus niger phytase (FP_250, FP_500 and FP_1000 groups), respectively; bacterial phyatse (BP) groups received 250, 500 and 1000 U/kg diet of Escherichia coli phytase (BP_250EP, BP_500EP and BP_1000EP groups) respectively. Considering the whole experimental period, body weight gain was unaffected by ZnB and different concentrations of bacterial and fungal phytase; however, the feed conversion ratio of the group fed a diet supplemented with 500 U of BP was better (p < 0.01) than those fed with a diet supplemented with 500 U of FP. BP_250 group had a higher (p < 0.05) apparent digestibility of ether extract compared to FP_250 group. In conclusion, bacterial phytase at 500 U may enhance performance of broiler chickens fed during days 1–40 of age and yield similar growth performance and economic efficiency to those of eB‐supplemented groups.  相似文献   

9.
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10.
Phytate is an antinutrient in animal feeds, reducing the availability and increasing the excretion of nutrients. Phytases are widely used to mitigate the negative influences of phytate. This trial was designed to compare the efficacy of 2 Escherichia coli-derived phytases on broiler performance and bone ash as influenced by dietary phytate level. A total of 1,024 Arbor Acres male broilers were used with 8 replicate pens of 16 birds/pen. Experimental diets were based on low available phosphorus (avP; 1.8 g/kg) with low (6.40 g/kg) or high (10.65 g/kg) phytate. The low-avP diets were then supplemented with mono-dicalcium phosphate to increase the avP level to 4.5 g/kg, 500 phytase units/kg of phytase A, or 500 phytase units/kg of phytase B to create 8 experimental diets. Feed intake, BW gain, FCR, and livability were influenced by a P source × phytase interaction. Feed intake, BW gain, and livability were reduced and FCR was higher in broilers fed low-avP diets, particularly in the presence of high phytate. Phytase A or phytase B improved feed intake, BW gain, and FCR, particularly in the high-phytate diet. However, broilers fed phytase A ate more and were heavier than broilers fed phytase B. Tibia ash was lowest in broilers fed the low-avP diet and highest in broilers fed the diet supplemented with mono-dicalcium phosphate. Phytase increased tibia ash, and broilers fed phytase A had an increase in tibia ash compared with broilers fed phytase B. In conclusion, high dietary phytate reduced broiler performance. Phytase A and phytase B improved bone ash and growth performance, especially in the high-phytate diets. However, phytase A was more efficacious than phytase B, regardless of the level of phytate.  相似文献   

11.
Phytase is an enzyme that has the ability to release phosphorous (P) from phytate by hydrolyzing inositol-phosphate linkages. Recently, thermostable phytases have gained great consideration because the reduction in phytase activity was found when exposed to heat during feed pelleting. In this study, the effects of the granular thermostable phytase (Aspergillus niger) on growth performance and nutrient utilization of broilers were investigated. A total of 96 21-day-old Arbor Acres broilers were randomly distributed into six treatments including basal diet (control) and basal diet supplemented with 500, 1,000, 2,000, 4,000, 8,000 U of phytase/kg. In general, the metabolizable energy (ME) and the apparent and true availability of dry matter (DM), organic matter (OM), ether extract (EE), crude protein (CP), and amino acids (AA) showed both linearly (p < .01) and quadratically (p < .01) increase with increasing levels of phytase in the diet. Additionally, diet supplementation with phytase could improve (p < .05) body weight (BW), average daily gain (ADG), and feed/gain (F/G) on day 42 compared with the control. The results suggested that diet supplementation of the granular thermostable phytase in the crumbled pellets could improve chicken growth performance and nutrient utilization.  相似文献   

12.
A feeding trial was designed to assess the effect of super dosing of phytase in corn–soya‐based diets of broiler chicken. One hundred and sixty‐eight day‐old broilers were selected and randomly allocated to four dietary treatment groups, with 6 replicates having 7 chicks per treatment group. Two‐phased diets were used. The starter and finisher diet was fed from 0 to 3 weeks and 4 to 5 weeks of age respectively. The dietary treatments were consisted of normal phosphorus (NP) group without any phytase enzyme (4.5 g/kg available/non‐phytin phosphorus (P) during starter and 4.0 g/kg during finisher phase), three low‐phosphorus (LP) groups (3.2 g/kg available/non‐phytin P during starter and 2.8 g/kg during finisher phase) supplemented with phytase at 500, 2500, 5000 FTU/kg diet, respectively, to full fill their phosphorus requirements. The results showed that super doses of phytase (at 2500 FTU and 5000 FTU/kg) on low‐phosphorus diet improved feed intake, body weight gain, ileal digestibility (serine, aspartic acid, calcium, phosphorus), blood P levels and bone minerals such as calcium (Ca), P, magnesium (Mg) and zinc (Zn) content. It could be concluded that super doses of phytase in low‐phosphorus diet were beneficial than the normal standard dose (at 500 FTU/kg) of phytase in diet of broiler chicken.  相似文献   

13.
 研究了3个不同品牌的微生物植酸酶在两个不同磷酸氢钙添加水平（0.44%和0.77%）下对肉仔鸡生产性能和钙磷消化率的影响。试验结果表明：与正常磷酸氢钙添加水平（1.1%）的对照组相比,降低磷酸氢钙用量并添加植酸酶后肉仔鸡的采食量和日增重与对照组接近,饲料转化率有一定提高,死淘率和腿病发生率与对照组差异不显著。降低磷酸氢钙用量并添加植酸酶能够一定程度的提高肉仔鸡对灰分的消化利用率（P＞0.05）,显著提高磷的消化利用率（P＜0.05）,并大幅提高24日龄肉仔鸡的钙表观消化率（P＜0.01）,小幅提高42日龄肉仔鸡的钙表观消化率（P＞0.05）, 不同品牌植酸酶的作用效果存在一定差异。  相似文献   

14.
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   

15.
Cereal grains such as maize and wheat are used extensively in feed formulations for poultry as the primary source of carbohydrates. High cost of these grains in many developing countries necessitates the evaluation of other ingredients that are grown locally. Sweet potato is one such crop. The study was conducted as a proof of concept experiment to test the hypothesis that in the presence and absence of enzyme, sweet potato roots when included in diets of broiler chickens may affect the total metabolisable energy content of the diets which may exert certain influences on dry matter digestibility of these diets as well as impacting on production and certain gut parameters. A total of 120 chicks were raised on a commercial starter feed from day 0 to 19. On day 22, the birds were individually weighed and allocated to 96 single bird metabolism cages to conduct a 7‐day classical apparent metabolisable energy (AME) assay. The test diets contained 0% and 25% sweet potato flour (SPF) with and without enzyme supplementation (Rovabio Excel AP T‐flex) and replicated 24 times. AME of the control diet with and without enzyme was 14.05 and 13.91 MJ/kg whilst the AME of the SPF diets with and without enzymes were 13.45 and 13.43 MJ/kg respectively. AME of SPF was 12.08 MJ/kg. Birds fed the SPF had significantly reduced end weights (p = .002) and weight gains (p < .001) leading to significantly higher intake (p = .004) and FCRs (p < .001) in birds. These effects in growth parameters highlight the need to balance dietary protein and total amino acids when using SPF in broiler diets and may not be a negative effect of SPF per say as AME and dry matter digestibility of SPF diets were comparable to the control diet. The level of sucrase activity in the jejunum was significantly (p < .001) lower due to enzyme inclusion. Use of SPF in the current study did not negatively influence the activities of the brush border enzymes maltase and sucrase, gut morphology in the jejunum of broilers or the load of Enterobacteriaceae in the caecal of birds. This finding is promising in that the gut parameters associated with digestive capacity and gut health were not compromised with feeding of SPF to broilers.  相似文献   

16.
植酸酶对种鸡生产性能及种蛋孵化性能影响的研究   总被引：9，自引：1，他引：8  
种鸡在生产条件下，利用植酸酶水解饲料中植酸的原理，观察商品植酸酶替代磷酸氢钙对种鸡生产性能和种蛋孵化性能的影响和评价其实际可应用性。选用２８～３６周龄的肉用黄种鸡（ＮＫ２７１），在饲料中添加３００单位植酸酶替代磷酸氢钙（ＤＣＰ）提供的１．８ｇ无机磷。结果表明：植酸酶使种鸡的产蛋率（＋０．６６％）、日耗料量（－０．７１％）、破蛋率（－９．３％）、不合格种蛋（－４．９５％）、种蛋受精率（＋０．２９％）和１２天活胚率（＋０．７８％）均得到改善，但差异不显著（Ｐ＞０．０５）；而入孵种蛋健雏率（＋１．８９％）、１２天活胚蛋健雏率（＋１．６６％）和残次雏率（－１６．１１％）则优于对照组，差异极显著（Ｐ＜０．０１）。因此，可以认为不仅在种鸡饲料中可用商品植酸酶替代磷酸氢钙，而且对种鸡和种蛋的几乎全部重要生产和繁殖指标，都有不同程度的良好作用。根据目前市场上磷酸氢钙的品质（含氟量）状况，使用植酸酶能够大幅度减轻以至于杜绝由磷酸氢钙导致的氟中毒问题。同时能够预见，使用植酸酶可以大幅度降低排泄物中的含磷量，并能减少对自然环境的污染。可见，植酸酶在种鸡饲料中具有重要的实际应用价值。  相似文献   

17.
采用306只艾维茵肉鸡研究低磷日粮中添加两种不同植酸酶对肉鸡生产性能、养分利用率及氮、磷排泄的影响。试验共分3个处理组,即对照组、试验Ⅰ组和试验Ⅱ组,每个处理组3个重复,每个重复34只鸡。对照组饲喂正常磷水平的日粮;试验Ⅰ组饲喂低磷＋植酸酶Ⅰ的日粮;试验Ⅱ组饲喂低磷＋植酸酶Ⅱ的日粮。试验结果表明,添加植酸酶替代日粮中部分无机磷,肉鸡的日增重和日采食量与对照组相比降低,但差异不显著（P＞0.05）;提高了肉鸡的存活率（P＜0.05）和钙、磷利用率（P＜0.05）;同时氮利用率有一定程度改善（P＞0.05）,显著减少了氮、磷的排泄量（P＜0.05）。添加植酸酶Ⅰ与添加植酸酶Ⅱ相比,肉鸡的日增重与日采食量提高（P＜0.05）,氮的排泄量显著降低（P＜0.05）,磷的排泄量没有差异。  相似文献   

18.
1. Various theories have been proposed to explain the reduced performance of broilers when given feeds excessively high in protein, but a satisfactory solution to this problem had, up to now, not been found. Three experiments were conducted to test the hypothesis that the efficiency of utilisation of protein (ep) is a linear–plateau function of the ratio between the feed apparent metabolisable energy and digestible crude protein contents (AMEn:DCP) and that dietary protein quality, feed allocation and sex do not influence this relationship.

2. A ‘linear–plateau’ model successfully described the efficiency of protein utilisation (ep) as a function of AMEn:DCP in all three experiments. In Experiment 1, with both sexes being both ad libitum and control fed, the breakpoint was at 58.6 MJ AMEn/kg DCP. In Experiment 2, both sexes were fed balanced and unbalanced protein series, and at different rates, the slopes of the ascending part of the linear–plateau relationships for the different treatments were the same for all treatments (0.0204), and the inflection point was at 71 MJ AMEn/kg DCP. Using similar treatments in Experiment 3, the breakpoint for the balanced protein was 72 MJ/kg and for the unbalanced, 64, with a combined slope of 68 MJ AMEn/kg DCP.

3. The three experiments provide adequate evidence that ep is a linear–plateau function of the dietary AMEn:DCP ratio with a breakpoint of around 66.2 ± 1.98 MJ AMEn/kg DCP. Below this critical ratio, food intake declines as does protein and lipid retention.

4. That broilers, like pigs, exhibit an energy-dependent phase when high-protein feeds are offered is of practical importance when formulating pre-starter feeds for broilers and starter feeds for turkey poults as the ep of such feeds may well fall below the maximum due to the lack of dietary energy required to process the high dietary protein contained in such feeds resulting in poorer performance than expected.  相似文献   


19.
文章旨在探讨植酸酶对饲喂低水平钙磷日粮肉鸡生长性能和养分表观消化率的影响。试验将平均初始体重为（61.56±0.66）g的1日龄肉鸡随机分为4组,每组4个重复,每个重复38只。对照组饲喂正常钙磷水平的玉米豆粕型日粮,T1～T3组饲喂低钙磷水平的玉米豆粕型日粮+0、1000和1500?FIU/kg植酸酶,试验分为1～21?d和22～42?d两个阶段。结果：对照组和T3组42?d肉鸡的体重显著高于T1组（P＜0.05）,同时T3组22～42?d以及1～42?d肉鸡的平均日增重较T1组分别显著提高8.01%和5.05%（P＜0.05）。T3组22～42?d肉鸡饲料报酬较其他组分别显著提高3.3%、3.09%和3.73%（P＜0.05）。对照组和T3组钙表观消化率显著高于T1和T2组（P＜0.05）,T3组干物质、氮和钙沉积率显著高于对照组和T1组（P＜0.05）,同时T3组磷沉积量最高（P＜0.05）。T1组蛋氨酸和苏氨酸表观消化率显著低于T3组（P＜0.05）,同时T1组亮氨酸、异亮氨酸、甘氨酸和丙氨酸回肠表观消化率均表现最低（P＜0.05）。结论：玉米豆粕型低钙磷日粮中添加植酸酶能有效提高钙、磷的营养价值及干物质、氮和氨基酸的代谢率。在较高剂量（1500?FTU/kg）时,对生长后期肉鸡的饲料报酬和氨基酸消化的效益最大。 [关键词]植酸酶|肉鸡|生长性能|养分消化  相似文献   

20.
A randomized controlled trial (RCT) was carried to evaluate the effect of a feed additive on Campylobacter contamination of broilers reared in commercial conditions. Twenty‐four broiler flocks naturally contaminated with Campylobacter were enrolled in the RCT: 12 were assigned to a control group (C) fed with a conventional finishing feed from 4 weeks of age to slaughter (around 35 days), and the other group of 12 flocks (S) was fed with a finishing feed supplemented with 250 ppm of a patented feed additive (an ion‐exchanged clay compound) previously proven to reduce Campylobacter contamination in broiler caeca under experimental conditions. Enumeration of Campylobacter colonies in caeca (8 per flock) was carried out following ISO standards before feed distribution and at slaughter. Before treatment, the caecal Campylobacter load tended to be lower in C flocks (7.1 ± 1.9 log CFU/g, CI95% [6.6–7.5]) than in S flocks (7.7 ± 1.0 log UFC/g, CI95% [7.5–7.9]) (p = .05). At slaughter, the bacterial load was similar in the S (7.7 ± 1.0 log CFU/g, CI95% [7.5–7.9]) and C groups (7.5 ± 1.2 log CFU/g, CI95% [7.2–7.8]) (p = .73). Therefore, the feed additive had no significant effect on the caecal Campylobacter load at slaughter under the tested conditions. The logistical constraints inherent in field trials and the natural variability of Campylobacter contamination in naturally infected broiler flocks make it difficult to reproduce experimental results in in situ farm conditions. RCT testing of an intervention strategy in commercial situation is therefore a key step in evaluating pre‐harvest interventions against food‐borne pathogens.  相似文献   

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