High vitamin D3 requirements in broilers for bone quality and prevention of tibial dyschondroplasia and interactions with dietary calcium, available phosphorus and vitamin A

1. Two experiments were carried out to investigate responses in performance and bone compositional and structural characteristics in broilers fed diets containing 4 concentrations of vitamin D3 (5, 20, 125 and 250 microg cholecalciferol/kg) at different concentrations of calcium, available phosphorus and vitamin A. 2. In experiment 1, body weight and tibia breaking strength were maximised at 14d with 250 microg vitamin D3/kg, tibia ash was maximised with 125 microg vitamin D3/kg. A high incidence of tibial dyschondroplasia (TD) was decreased to very low levels with 125 microg vitamin D/kg. 3. At 42d, performance and bone characteristics showed no response to vitamin D3 concentrations above 20 microg/kg. 4. Dietary vitamin A within the range 2-4 to 4.5 mg retinol/kg did not show any interaction with vitamin D3 status at either age. 5. In experiment 2, responses to vitamin D3 were strongly influenced by dietary calcium/available phosphorus. With 13 g calcium and 5 g available phosphorus/kg, performance and bone characteristics responded to vitamin D3 concentrations up to 125 microg/kg but more was needed at less optimal concentrations of calcium and available phosphorus. TD incidence was minimised with 250 microg/kg. 6. This study shows that high dietary concentrations of vitamin D3 can prevent TD. It is concluded that the vitamin D3 requirement of broilers up to 14 d of age at optimal dietary calcium and available phosphorus concentrations may be in the range 35 to 50 microg/kg for cortical bone quality and up to 250 microg/kg for prevention of TD. The vitamin D3 requirement for cortical bone quality after 14 d is not higher than 20 microg/kg. These requirements are much higher than earlier estimates and may be related to higher calcium requirements of modern broiler genotypes. Current regulations limiting maximum vitamin D3 concentrations in broiler starter diets may need to be reviewed.     

Effects of carboxy methyl cellulose and thymol + carvacrol on performance,digesta viscosity and some blood metabolites of broilers

This study was conducted to evaluate the effects of thymol + carvacrol as plant essential oils on performance, digesta viscosity and some blood metabolites of broilers fed diets supplemented with carboxy methyl cellulose (CMC) and/or thymol+carvacrol. In a completely randomized design with a 2 × 3 factorial arrangement, two levels of CMC (0% and 2%) and three levels of thymol+carvacrol (0, 100 and 200 mg/kg) were used. Each of the six dietary treatments was fed to five replicate pens of 12 birds each from 0 to 42 days of age. Body weight gain (BWG), feed intake, feed conversion ratio (FCR), intestinal digesta viscosity and pH, plasma lipids and some blood metabolites were recorded. The inclusion of 2% CMC decreased (p < 0.05) BWG by 2.2% and increased FCR by 2.3% at 42 days of age. Carboxy methyl cellulose significantly increased the digesta viscosity and decreased serum total cholesterol, but had no significant effect on triglyceride, pH, HDL, LDL and other blood metabolites measured in this experiment. Thymol+carvacrol had no effect on feed intake, but significantly increased (p < 0.05) BWG from 1 to 42 days of age and improved FCR (p < 0.05) by the addition of 100 and 200 mg/kg thymol+carvacrol respectively. Inclusion of thymol+carvacrol at levels of 100 and 200 mg/kg in the diets decreased digesta viscosity and serum total cholesterol (p < 0.05) and also increased AST at a 200 mg/kg thymol+carvacrol without any effect on creatine kinase (CK). Thymol+carvacrol significantly increased total protein (TP), albumin and globulin (p < 0.05). In conclusion, CMC at an inclusion level of 2% of diet increased digesta viscosity and reduced growth performance. However, thymol+carvacrol decreased digesta viscosity and consequently improved the performance of broilers fed the CMC‐based diet. Therefore, thymol+carvacrol addition to viscose‐based diets might be helpful to alleviate the negative effects of viscous compounds in poultry diets.     

Effectiveness of dietary 25‐ and 1‐hydroxycholecalciferol in combating tibial dyschondroplasia in broiler chickens

1. Three experiments were carried out to determine the effects of feeding diets containing different concentrations of cholecalciferol, 1 a‐hydroxychole‐calciferol (1‐HCC), 25‐hydroxycholecalciferol (25‐HCC), 1,25‐dihydroxycholecalcif‐erol (1,25‐DHCC) and ascorbic acid on the incidences and severities of tibial dyschondroplasia (TD) at 3 weeks of age in male broiler chicks.

2. In experiment 1, replacing 75 μg cholecalciferol/kg with the same weight of 25‐HCC decreased significantly (P<0.01) the incidence of TD from 65 to 10%.

3. In experiment 2, the incidence of TD in the control group was lower, but feeding amounts of 25‐HCC up to 250 μg/kg had a linear effect on the incidence of TD that was significant at P=0.06. There was no effect or interactions with dietary addition of 250 mg ascorbic acid/kg. Dietary addition of 5 μg 1‐HCC/kg decreased TD incidence from 21 to 5%, though the effect was not significant (P>0.1).

4. TD incidence in experiment 3 was too low to determine an effect of 25‐HCC or 1,25‐DHCC on TD incidence, though in this, as in both other experiments, the severities of TD lesions were always lower with diets containing cholecalciferol metabolites.

5. Hypercalcaemia was not observed after feeding up to 250 μg 25‐HCC/kg in either experiments 2 or 3.

6. It is concluded that 25‐HCC may be an effective practical means of improving broiler leg health by alleviating the incidence and severity of TD.     

25-羟胆钙化醇与维生素D_3对北京鸭生产性能和骨骼发育的影响

试验选用2 160羽1日龄北京鸭,按4×3两因素设计随机分成12个处理,每处理6个重复;分别饲喂不同水平的25-羟胆钙化醇(25-OH-D3)(0、35、70、105μg/kg)与维生素D3(2 500、3 000、3 500 IU/kg)的日粮,探讨25-OH-D3在肉鸭日粮中的使用效果。结果表明:不同水平25-OH-D3对北京鸭生产性能没有显著影响;添加105μg/kg较35、70μg/kg显著降低45日龄北京鸭胸肌率(P<0.05);70、105μg/kg 25-OH-D3较35μg/kg显著提高了胫骨磷含量(P<0.05)。添加3 500、3 000 IU/kg维生素D3较2 500 IU/kg显著提高15～35日龄北京鸭日增重(P<0.05);添加3 500 IU/kg维生素D3较3 000、2 500 IU/kg显著提高14、45日龄胫骨钙含量(P<0.05)。25-OH-D3和维生素D3对14日龄胫骨中钙、磷含量和45日龄胫骨磷含量分别存在极显著(P<0.01)和显著(P<0.05)地交互作用。综合本试验可得出,北京鸭日粮中添加3 000 IU/kg维生素D3和70μg/kg 25-OH-D3效果最佳。     

Can betaine partially replace or enhance the effect of methionine by improving broiler growth and carcase characteristics?

1. Growth rates and carcase characteristics were measured in male broiler chickens fed on a control diet deficient in methionine (c. 2·8 g/kg methionine) or a series of diets containing graded levels of betaine or DL-methionine or both additives. 2. We aimed to answer 2 main questions. First, can betaine replace part of the methionine in a broiler ration? Secondly, is there a synergism between methionine and betaine? 3. Birds given the control diet or that supplemented only with betaine ate less, grew more slowly, had higher food convension ratio (FCR) and varied more in mass at 42 d than birds fed diets with DL-methionine. Adding 1·2 g/kg DL-methionine to the control ration produced the heaviest birds at 42 d (2500 g) with the 2nd heaviest breast muscle (366 g). 4. After correcting for treatment differences in body mass (analysis of convariance), birds fed on the control diet and the diet supplemented with betaine only, had relatively lighter breast muscles but relatively heavier abdominal fat pads than those of birds given diets supplemented with DL-methionine. However, adding betaine to diets containing added methionine further improved the relative breast muscle yield. 5. After correcting for differences in body mass between treatments, birds fed on diets containing most methionine had lighter viscera than birds fed diets deficient in methionine. This demonstrated gut plasticity, suggesting that the viscera enlarged to sequester methionine from low-methionine diets. 6. Our data refute the hypothesis that betaine can substitute for methionine in broilers fed diets that are marginally deficient in methionine plus cystine. However, betaine may improve carcase composition, especially breast meat yield.     

Response of broiler chickens to different levels of calcium,non-phytate phosphorus and phytase

1. Five hundred and seventy six-d old Ross 308 broiler chicks (6 cages per diet, 8 birds per cage in 3 × 2 × 2 factorial arrangement) were fed on maize–soybean meal-based diets containing three concentrations of Ca (6, 8 or 10 g/kg), two concentrations of non-phytate phosphorus (NPP) (3 or 4 g/kg) and two levels of exogenous microbial phytase (0 or 500 FTU/kg) from d 0 to 35.

2. Body weight (BW), feed intake (FI) and mortality records were collected. Two birds per replicate were killed at 24 d of age to obtain tibia samples.

3. Increasing Ca level significantly reduced the FI and body weight gain (BWG) between hatch and 10 and 24 d, especially with the phytase-supplemented diets. However, phytase supplementation of the diet containing 4 g NPP/kg improved the FI and BWG at d 10 and 24. At d 24, phytase supplementation improved feed conversion ratio (FCR) of birds that consumed diets containing high NPP. The overall FCR was better in birds offered the phytase-supplemented, medium-Ca diet.

4. There was a significant reduction in length, width and breaking strength of the tibia bone in birds fed on a diet with high Ca and low NPP. Phytase supplementation improved the tibia ash content and bone breaking strength of chicks fed on the diet containing 8 and 4 g/kg Ca and NPP, respectively. The Ca content of the tibia bone was low in birds fed on diets with 6 and 4 g/kg Ca and NPP, respectively, but this was counteracted by phytase supplementation.

5. Birds fed on diets with 4 g/kg NPP had the best carcass percentage and parts yield. Phytase supplementation to high-Ca diets significantly reduced the carcass yield of birds.

6. These results confirmed the detrimental effect of high dietary Ca on phytase activity and subsequent growth and bone development of birds, especially when NPP is in short supply.     

Influence of phytate level on broiler performance and the efficacy of 2 microbial phytases from 0 to 21 days of age

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.     

饲粮添加不同水平维生素D_3对肉仔鸡生长性能和骨磷代谢利用的影响

本试验旨在研究饲粮中添加不同水平维生素D3(VD3)对肉仔鸡生长性能及骨磷代谢利用的影响。试验选用480只1日龄艾拔益加肉公雏,采用2×4双因子完全随机设计,设2个饲粮非植酸磷水平[0.45%和0.23%(实测值为0.44%和0.21%)]与4个VD3添加水平(0、1 000、2 000和4 000IU/kg),共8个组,每组6个重复,每个重复10只鸡。试验期21d。结果表明,与0.21%非植酸磷水平相比,0.44%非植酸磷水平显著提高肉仔鸡平均日增重(ADG)、平均日采食量(ADFI)、胫骨灰分含量和胫骨灰分磷含量(P0.05),显著降低料重比(F/G)和胫骨灰分磷绝对沉积率(P0.05);与不添加VD3相比,饲粮中添加VD3显著提高肉仔鸡ADG、15~21和1~21日龄ADFI、胫骨灰分含量和胫骨灰分磷绝对沉积率(P0.05),显著降低1~21日龄肉仔鸡F/G(P0.05);0.21%非植酸磷水平下,与不添加VD3相比,饲粮中添加VD3显著降低肉仔鸡死亡率(P0.05),显著提高21日龄肉仔鸡胫骨灰分磷重量(P0.05),添加2000IU/kg VD3显著提高14日龄肉仔鸡胫骨灰分磷重量(P0.05);0.44%非植酸磷水平下,与不添加VD3相比,饲粮中添加VD3显著提高肉仔鸡胫骨灰分磷重量(P0.05)。以上结果表明,饲粮中添加VD3可提高肉仔鸡的生长性能并降低死亡率,促进磷在骨骼中的代谢利用。     

Interaction between dietary 1,25‐dihydroxycholecalciferol and calcium and effects of management on the occurrence of tibial dyschondroplasia,leg abnormalities and performance in broiler chickens

1. Two experiments were performed to compare the relative effectiveness of feeding 1,25‐dihydroxycholecalciferol (1,25‐DHCG) in minimising leg abnormalities in broilers with other methods and to investigate interactions between dietary 1,25‐DHCC and calcium.

2. Adding 5 μg 1,25‐DHCC/kg to a diet containing 12 g calcium/kg was more effective than early food restriction or meal feeding in preventing leg abnormalities but was found to cause a growth depression.

3. The second experiment, which had a factorial design, with diets containing 7.5, 100 and 12.5 g calcium and 0, 2.0, 3.5 and 5.0 μg 1,25‐DHCC/kg, showed linear and quadratic interactions between these dietary factors. Diets with higher concentrations of both 1,25‐DHCC and calcium resulted in growth depression associated with hypercalcaemia.

4. The incidence of tibial dyschondroplasia (TD) at 3 weeks of age was highest with the basal diet containing 7.5 g calcium/kg and was markedly reduced by addition of 1,25‐DHCC and/or calcium. The incidence was very low or non‐existent when 1,25‐DHCC was fed at 3–5 μg/kg or greater.

5. Feeding 5 μg/kg 1,25‐DHCC had no effect on plasma 1,25‐DHCC concentrations, although at the higher dietary calcium contents plasma concentrations of 25‐hydroxy‐ and 24,25‐dihydroxy‐cholecalciferol were lower in those birds fed 1,25‐DHCC.

6. It is concluded that 1,25‐DHCC is most effective in preventing TD without accompanying growth depression when it is fed in conjunction with diets containing less than 10 g calcium/kg.     

Effects of dietary supplemental methionine source and betaine replacement on the growth performance and activity of mitochondrial respiratory chain enzymes in normal and heat‐stressed broiler chickens

This study aimed to evaluate the effects of dietary supplemental methionine (Met) source and betaine (Bet) replacement for Met on performance and activity of mitochondrial respiratory chain enzymes (MRCEs) in normal and heat‐stressed broiler chickens. Total of 1,200‐day‐old Ross 308 chicks were allocated to two houses, each consisted of 12 treatments, five replicates of 10 birds each with 2 × 2×3 × 2 (temperature × Met source × Met level × Bet, respectively) split‐plot factorial arrangement. Met level in the basal diets was 70% requirements (Req) that was increased to the requirement or 130% by supplemental dl ‐ or l ‐Met. Bet was or was not substituted at the rate of 30% supplemental dl ‐ or l ‐Met. Feed conversion ratio (FCR) in chicks fed 70% l ‐Met was lower than those fed 70% dl ‐Met diet during 1–10 days (p = 0.04). Broilers fed diets containing requirement or 130% Met, regardless of its source, showed higher weight gain (WG) than those received 70% Met diet during 11–42 days (p < 0.001). Feed intake (FI) of broilers fed 130% Met diet was decreased compared to other two groups during 11–42 days (p < 0.05). One hundred thirty percent Met requirement diet resulted in lower FCR comparing to other two groups during 11–42 days (p < 0.001). Heat‐stressed birds grew less than those under normal condition (p < 0.05). Broilers fed Req Met diet under normal temperature exhibited higher activities of complexes (Cox) I and III (p < 0.05). Cox I activity in heat‐stressed birds fed Bet + diet was similar to those fed Bet‐diet under normal temperature (p = 0.046). It is concluded that performance and the activities of Cox I and III were increased as the level of Met increased. Bet replacement for 30% supplemental Met resulted in similar consequences comparing to non‐Bet replacement diets on performance, but increased the activity of Cox III. l ‐Met was effective than dl ‐Met at the cellular level. High ambient temperature depressed performance and MRCE activity.     

Moderate excess of dietary vitamin E does not exacerbate cholecalciferol deficiency in young broiler chicks

1. The combined effect of moderate excess dietary vitamin E and marginal amounts of dietary cholecalciferol on the performance and tibia bone ash of young male broiler chicks was evaluated. Vitamin E (α‐tocopheryl acetate) and cholecalciferol were added to a commercial diet not already supplemented with these vitamins, at concentrations of 0 and 150 mg/kg, and 1.875, 5 and 25 μg/kg, respectively, and fed to chicks for 23 d.

2. Vitamin E concentration and its combinations with cholecalciferol did not significantly (P> 0.05) affect food intake, weight gain, food efficiency and bone ash. These variables were significantly (P< 0.001) lower in chicks fed on the diets supplemented with 1.875 μg cholecalciferol/kg compared with the values observed with the 2 other concentrations of this vitamin. There were no differences in the effects of 5 and 25 μg cholecalciferol/kg diet on the above variables.

3. It was concluded that vitamin E, at a concentration of 150 mg/kg diet, did not aggravate a mild cholecalciferol deficiency.     

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.     

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。     

Effects of a New Recombinant Phytase on the Performance and Mineral Utilization of Broilers Fed Phosphorus-Deficient Diets

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).     

Evaluation of Heat-Stable Phytases in Pelleted Diets Fed to Broilers from Day Zero to Thirty-Five During the Summer Months

Supplementing phytase to broiler diets has been shown to improve phytate P digestibility in commercial broilers. Broiler rations are typically pelleted to promote improved broiler performance, but high pelleting temperatures can inactivate phytase enzymes. Before the introduction of heat-stable phytase products, phytase enzymes were generally added postpelleting to limit the effect of pelleting temperature on phytase activity. Therefore, the objective of this study was to evaluate postpelleting phytase activity of 3 concentrations of 2 heat-stable phytase enzymes and their efficacy when fed to 0- to 35-d-old broilers. After pelleting the phytase-supplemented diets at 93.3°C, the retained phytase activities of the 2 enzymes were similar, suggesting equivalent heat stability. Supplementing phytase to deficient nonphytate P diets improved FCR by 3% (P ≤ 0.05) compared with the FCR of birds fed an unsupplemented deficient diet. No differences in tibia ash (TA) were detected between the 2 phytase sources; however, TA of birds fed supplemental phytase at the 2 greatest concentrations was improved (P ≤ 0.05) compared with the TA of birds fed nonphytate P-deficient diet. These results suggest that the prepelleting inclusion of heat-stable phytase enzymes may be a viable alternative to postpellet application of phytase for improving P utilization in broilers.     

Supplementation of broiler diets with high levels of microbial protease and phytase enables partial replacement of commercial soybean meal with raw,full‐fat soybean

A 3 × 3 + 1 factorial, involving three levels of protease (0, 15,000 or 30,000 PROT/kg) and three levels of phytase (1,000, 2,000 or 3,000 FYT/kg), was used to evaluate the effect of replacing commercial soybean meal (SBM) with raw, full‐fat soybean (RFSB) at 75 g/kg of diet for broilers. A control diet was used for comparison. Each treatment was replicated six times, with nine birds per replicate. The concentration of trypsin inhibitors (TIs) in the test diets was approximately 10,193.4 TIU/kg. Regardless of enzyme supplementation, feed intake (FI) and body weight gain (BWG) of birds in the control group were superior to those on the test diets. Birds that received the protease‐free test diets had reduced FI and BWG, but when supplemented with protease, were similar to the control diet in BWG, FI (except 0–35 days) and feed conversion ratio (FCR). When the test diet was supplemented with elevated levels (extradose) of protease and phytase, the BWG was improved during 0–10 days (p = .05) and 0–24 days (p < .01). Regardless of protease supplementation, the weight of thighs was lower for birds fed the test diets. Birds that received the control diet had smaller weight of pancreas. Increasing the level of phytase supplementation reduced (p < .05) the weight of the pancreas. The apparent ileal digestibility (AID) of CP and AA was higher in birds on the control diets, but this was also improved in test diets by protease supplementation. The activities of trypsin (7%), general proteolytic (11%) and lipase (12%) were slightly increased because of protease supplementation. Mucosal depth and apparent villus surface areas were increased by about 2.9% and 20%, respectively, due to supplementation of elevated level of phytase. It can be concluded that RFSB could partially replace SBM in broiler diets, provided the diets are supplemented with elevated levels of protease and phytase.     

Effect of low‐ or high‐CP diet with cold‐pressed oil supplementation on growth,immunity and antioxidant indices of growing quail

This study was to investigate the effect of dietary protein levels and supplementation with two cold‐pressed oils on the performance, immunity and antioxidant indices of growing Japanese quails. A 3 × 4 factorial experiment, using 3 dietary crude protein (CP) levels (22%, 24% and 26%) and 4 supplemental herbal oils levels: control without additives, 250 mg marjoram (Mar), 250 mg thyme (Thy) and 125 mg Mar + 125 mg Thy per kg diet. A total of 720 unsexed, 7‐day‐old quail chicks were randomly distributed into twelve treatment groups (4 replicates per group of 15 chicks in each). The live body weight (LBW) on 42 days and body weight gain (BWG) from 7 to 42 days were significantly improved (p < 0.01 and 0.05) in chicks fed 24% or 26% CP compared with those of the 22% CP group. The groups fed diets supplemented with Mar or in combination with Thy oil exhibited significantly better LBW, BWG and feed conversion ratio (FCR) than the control at all periods except BWG from 21 to 42 days and FCR from 7 to 21 days were not significant. Feed intake was gradually decreased with increasing dietary CP level or adding herbal oils during the periods 21–42 and 7–42 days of age. Plasma triglycerides, cholesterol, total lipids and malondialdehyde were decreased by cold‐pressed oils supplementation, but the activity of reduced glutathione and superoxide dismutase was increased (p < 0.01) compared with the control. In conclusion, quails fed a diet containing 24% or 26% CP or diets supplemented with Mar or Thy oils or both exhibited improvement in the performance, lipid profile, immunity and antioxidant capacity without any detrimental impacts on the other studied parameters.     

Effect of dietary citric acid on the performance and mineral metabolism of broiler

The objective of this study was to investigate the effect of dietary citric acid (CA) on the performance and mineral metabolism of broiler chicks. A total of 1720 Ross PM3 broiler chicks (days old) were randomly assigned to four groups (430 in each) and reared for a period of 35 days. The diets of groups 1, 2, 3 and 4 were supplemented with 0%, 0.25%, 0.75% or 1.25% CA by weight respectively. Feed and faeces samples were collected weekly and analysed for acid insoluble ash, calcium (Ca), phosphorus (P) and magnesium (Mg). The pH was measured in feed and faeces. At the age of 28 days, 10 birds from each group were slaughtered; tibiae were collected from each bird for the determination of bone mineral density, total ash, Ca, P, Mg and bone‐breaking strength, and blood was collected for the measurement of osteocalcin, serum CrossLaps^®, Ca, P, Mg and 1,25(OH)₂Vit‐D in serum. After finishing the trial on day 37, all chicks were slaughtered by using the approved procedure. Birds that were fed CA diets were heavier (average body weights of 2030, 2079 and 2086 g in the 0.25%, 0.75% and 1.25% CA groups, respectively, relative to the control birds (1986 g). Feed conversion efficiency (weight gain in g per kg of feed intake) was also higher in birds of the CA‐fed groups (582, 595 and 587 g/kg feed intake for 0.25%, 0.75% and 1.25% CA respectively), relative to the control birds (565 g/kg feed intake). The digestibility of Ca, P and Mg increased in the CA‐fed groups, especially for the diets supplemented with 0.25% and 0.75% CA. Support for finding was also indicated in the results of the analysis of the tibia. At slaughter, the birds had higher carcass weights and higher graded carcasses in the groups that were fed the CA diets. The estimated profit margin was highest for birds fed the diet containing 0.25% CA. Birds of the 0.75% CA group were found to have the second highest estimated profit margin. Addition of CA up to a level of 1.25% of the diet increased performance, feed conversion efficiency, carcass weight and carcass quality, but only in numerical terms. The addition of CA up to 0.75% significantly increased the digestibility of macro minerals, bone ash content, bone mineral density and bone strength of the broiler chicks. It may, therefore, be concluded that the addition of 0.75% CA in a standard diet is suitable for growth, carcass traits, macromineral digestibility and bone mineral density of broiler chicks.     

Efficiency of inorganic and organic iron sources under iron depleted conditions in broilers

1. A total of 240?d-old male Ross chicks (average BW 37·15?±?0·49?g) were fed on an iron (Fe)-deficient semi-synthetic diet (45?mg Fe/kg) from d 1-7 post hatching.

2. At d 7, all 240 chicks (average BW 140·15?±?1·4?g) with depleted Fe-stores were randomly assigned to three treatments on the basis of BW to study the efficiency of dietary inorganic and organic iron (Fe) utilisation. Each treatment had 4 replicates with 20 birds in each.

3. Dietary treatments were: maize-soyabean meal-based basal diet, containing 103 to 106?mg Fe/kg (control); and basal diets supplemented with an additional 80?mg/kg Fe either from an inorganic (FeSO₄?·?H₂O, 28% Fe) or organic (ferrous methionine chelate, 10% Fe) source. The starter and finisher diets were fed from d 7 to 21 and d 21 to 35, respectively.

4. Improved body weight gain and FCR during finisher phase and overall study period; and greater DM and CP retention, and excreta Fe excretion, at d 20 to 21 and d 34 to 35; were observed in birds fed on Fe supplemented diets when compared with birds fed on control diet. At d 35, the RBC, Hb, haematocrit, and Fe concentration in plasma, tibia and liver were higher in birds fed on Fe supplemented diets than birds fed on the control diet.

5. Supplementation of Fe in organic form resulted in greater Fe concentration in the tibia and liver and less Fe excretion at d 34 to 35, when compared with birds receiving inorganic Fe.

6. These results indicate the necessity to supplement Fe in the commercial diets of broilers; however, organic and inorganic sources of Fe supplementation at 80?mg/kg were equally effective in improving performance, nutrient retention and haematological indices. In addition, Fe supplementation through an organic source seems to be more efficient in depositing Fe in the haemopoietic organs (liver and tibia) of birds under Fe depleted conditions.     

Effects of essential oils from Liquidambar orientalis Mill. leaves on growth performance,carcass and some organ traits,some blood metabolites and intestinal microbiota in broilers

1. This study was carried out to investigate the effects of liquidambar essential oils (LEO) isolated from Turkish sweet gum (Liquidambar orientalis Mill.) leaves on growth performance, carcass, edible inner organs (EIO), gastrointestinal traits (gut), some blood metabolites and jejunum microbiota in broilers.

2. A total of 375 one-d-old male broilers (Ross 308) were randomly allocated to 5 treatments with 5 pens with 15 birds. The birds were fed on diets without antibiotics (CONT), with antibiotic (50 mg per kg, AB), with LEOs at 0.0405 (0.04LEO), 0.0811 (0.08LEO) or 0.1622 (0.16LEO) g/kg feed up to 42 d of age. The levels of LEOs included to diets were determined according to in vitro antimicrobial activity.

3. From d 1 to 42, the 0.08LEO treatment had higher live weight gain (LWG) compared to others. The 0.08LEO treatment increased feed intake (FI) compared to the CONT, AB and 0.04LEO. However, the feed conversion ratio (FCR) of these birds was lower than those in the AB and 0.16LEO treatments. From 1 to 42 d of age for LWG, the effects were quadratic and cubic, while those for FI and FCR were cubic and quadratic, respectively. Birds that fed 0.08LEO and AB diets had higher and lower carcass weights (CW) than those that fed other diets. The effect of LEO levels was cubic on the CW. The 0.08LEO and 0.16LEO decreased abdominal fat (AF) weight compared to the AB. The blood cholesterol decreased by the 0.04LEO and 0.08LEO treatments compared to the CONT. For the blood cholesterol, the effects of LEO levels were cubic. The 0.08LEO treatments decreased Escherichia coli counts in jejunum compared to the CONT and 0.16LEO.

4. Feeding a diet with LEO at 0.0811 g/kg might increase the LWG, FI and weights of carcass and AF, whereas it might decrease blood cholesterol and E. coli counts without affecting blood high-density lipoprotein, low-density lipoprotein, triglyceride, glucose, aspartate transaminase and alanine transaminase concentrations.