Pathology of vitamin D deficiency in growing turkeys

Turkey poults were fed a vitamin D-deficient diet and examined for clinical signs and structural changes of bone and parathyroid glands. Vitamin D-deficient poults developed ricketic changes during days 10 to 14. Control poults (deficient diet plus vitamin D) did not develop rickets. In deficient poults, lengths of proliferating-prehypertrophied zones of growth plates increased significantly in the proximal tibiotarsus but were only slightly elongated in the distal tibiotarsus. Unmineralized hypertrophic chondrocyte zones increased in length rapidly in conjunction with a decrease in the length of mineralized hypertrophic degenerative zones; this occurred more rapidly in proximal than in distal tibiotarsus. Other ricketic changes included decreases in bone ash, total femoral bone ash (calcium, phosphorus, magnesium), bone length, and body weight. Plasma alkaline phosphatase was increased, calcium was normal, and phosphorus was normal or elevated. Parathyroids were hyperplastic and had foci of degeneration. Vitamin D3 metabolites 25OHD3, 1,25(OH)2D3, and 24,25(OH)2D3 were rapidly depleted. Increase in bone ash Ca/P ratios in deficient poults suggests that phosphorus may be selectively released from ricketic bone. Low 25OHD3 and 1,25(OH)2D3 of control poults early in the experiment suggests that 1,400 IU of vitamin D3/kg of feed may not be an adequate level of vitamin D3 for growing turkey poults.     

Vitamin D doses for alpacas (Lama pacos)

OBJECTIVE: To assess the effectiveness of cholecalciferol (D3) doses for maintaining adequate vitamin D status in crias and adult female alpacas at pasture. DESIGN: A field experiment during winter and early spring in a herd on a farm in South Australia. ANIMALS AND PROCEDURE: Crias, usually less than 6 months of age and female alpacas, aged 2 to 6 years, were given a single subcutaneous dose of 0, 1000 or 2000 IU D3/kg body weight. Plasma concentrations of 25-hydroxycholecalciferol (25-OH D3), phosphorus, calcium and vitamins A and E and alkaline phosphatase activity were measured at intervals over a period of 16 weeks after treatment. RESULTS: Crias not given a vitamin D supplement had reduced growth rate during winter and one animal showed clinical signs of rickets. Vitamin D treatment had no effect on the body weight of mature females. Vitamin D supplements increased the 25-OH D3 and phosphorus concentrations in plasma of both crias and adult females; alkaline phosphatase activity was not affected by treatment. CONCLUSION: It is suggested that for alpacas in southern Australia a subcutaneous dose of 1000 IU D3/kg body weight to crias in late autumn and again in mid winter and to adult females in mid winter should prevent vitamin D inadequacy.     

Effects of dietary supplementation with vitamin C or vitamin E on cardiac lipid peroxidation and growth performance in broilers at risk of developing ascites syndrome

OBJECTIVE: To assess effects of high dietary amounts of vitamin C or vitamin E and oxidative stress on the heart and growth performance of broilers maintained at an altitude of 2,200 m above sea level. ANIMALS: 360 chicks (1-day-old broilers). PROCEDURE: Birds were randomly assigned to 3 groups (120 chicks/group). Each group of birds was fed a specific diet (control group, basal diet containing 12 mg of vitamin E (DL-alpha-tocopherol acetate)/kg of feed without additional ascorbic acid; vitamin E group, basal diet supplemented with 75 mg of vitamin E/kg of feed; and vitamin C group, basal diet supplemented with 400 mg of ascorbic acid/kg of feed) throughout the entire 7 weeks of the study. Feed consumption and body weight of chicks were recorded on a weekly basis. Nine randomly selected birds from each group were euthanatized each week. Remaining birds were euthanatized at the end of the study. Samples of cardiac tissues were obtained to measure thiobarbituric acid reactive substances (TBARS), an indicator of oxidative stress. RESULTS: Vitamin E-supplemented diets resulted in better growth performance, lower rates of feed conversion, and lower TBARS content. Vitamin C-supplemented diets resulted in lower feed consumption and lower rates of feed conversion. When used separately, neither of the vitamins had any effect on mortality attributable to ascites syndrome. CONCLUSION AND CLINICAL RELEVANCE: It is recommended that diets supplemented with vitamin C, vitamin E, or both be fed to broilers maintained at an altitude of 2,200 m above sea level to improve growth performance.     

Vitamin A nutrition of growing cockatiel chicks (Nymphicus hollandicus)

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.     

Evaluation of phytase concentration needed for growing-finishing commercial turkey toms

1. Growth performance, serum bone markers, and bone strength and mineralisation were determined in tom turkeys grown from 9 to 17 weeks of age. 2. Dietary non-phytate phosphorus was formulated to be reduced by 1.0 g/kg in the low phosphorus diet compared to a control diet and phytase was added to provide 0, 150, 300, 450 or 600 units/kg activity to the low phosphorus diet. 3. From 9 to 12 weeks of age, body weight and gain:food were reduced by the low phosphorus diet without added phytase, compared to the adequate phosphorus diet. Increasing the concentration of phytase linearly increased these growth parameters. There were no significant growth responses at 17 weeks of age. 4. Serum osteocalcin was reduced by increasing dietary phosphorus at 12 weeks of age when growth was affected, but not at later ages. Serum pyridinoline was reduced by higher dietary phosphorus and decreased linearly with increasing phytase activity at 17 weeks of age. 5. Fracture force of the ulna and femur increased linearly with increasing phytase activity but bone strength was not affected when corrected for bone cross-sectional area. Bone strength of the ulna and ash concentration of the ulna and tibia were increased by higher dietary phosphorus. Humerus and ulna ash increased linearly with increasing phytase activity. 6. Water-soluble phosphorus content of the litter was increased by higher dietary phosphorus and addition of phytase to the low phosphorus diet. The increase in water-soluble phosphorus content of the litter when phytase was fed may indicate that phosphorus could be fed at a lower concentration than used in this trial, at least in the finisher diet when phytase is added to the food. 7. Bone fracture force, strength and ash were generally optimised when 450 units/kg phytase activity was added to the low phosphorus diet. However, growth performance was best in the grower I (9 to 12 weeks) phase when 600 units/kg phytase was added to the diet.     

Vitamin A deficiency in turkey poults.

Vitamin A deficiency was diagnosed in a commercial flock of 13,000 4-6-week-old turkey poults in the summer of 2004. The birds were initially submitted for examination because of a 3% increase in the reported daily mortality of the flock. Clinically, affected birds had stunted growth and ruffled feathers, showed signs of incoordination, and were depressed. At necropsy, pale white pseudomembranous to mucoid material was observed on the mucosal surface of the tongue, oral cavity, portions of the esophagus, and the crop of some birds. Histologically, there was squamous metaplasia of the mucosal epithelium of the oral mucosa, esophagus, sinuses, nasal glands, bronchi, proventriculus, and the bursa of Fabricius. Vitamin A was not detected in the feed sample at a detection limit of 0.5 mg/kg. Serum vitamin A concentrations in 7 birds were very low and ranged from 0.05 to 0.1 mg/L. Vitamin A concentrations in livers were extremely low (0.1 mg/kg wet weight, 1/7 poults) or undetectable (< 0.1 mg/kg wet weight, 6/7 poults). A diagnosis of vitamin A deficiency was made based on gross and microscopic lesions and vitamin A concentrations in serum, liver, and feed. To the authors' knowledge, this is the first documented case of vitamin A deficiency in poults submitted from a commercial meat turkey producer comparatively depicting the gross and microscopic lesions with those found in other species of birds and mammals.     

维生素A对鹅生长性能及血清生化指标的影响

本试验旨在研究不同水平维生素A对青农灰鹅生长性能、血清生化指标及组织中维生素A含量的影响。选用1日龄青农灰鹅200只,随机分为5组,每组4个重复,每个重复10只鹅。各组在玉米-豆粕型基础饲粮中分别添加0、1 500、3 000、6 000和12 000 IU/kg的维生素A。试验期12周。结果表明:1)饲粮添加维生素A能显著提高1～4、5～12周龄青农灰鹅平均日增重和平均日采食量(P<0.05),降低死淘率,但对料重比影响不显著(P>0.05)。2)4周龄时,添加6 000 IU/kg维生素A显著降低了血清尿酸含量(P<0.05),添加3 000和6 000 IU/kg维生素A极显著提高了血清碱性磷酸酶活性(P<0.01),但对血清总蛋白、血糖和尿素氮的含量影响不显著(P>0.05);12周龄时,添加6 000 IU/kg维生素A显著降低血清血糖和尿酸含量(P<0.05),极显著提高了血清碱性磷酸酶活性(P<0.01),但不同水平维生素A对血清总蛋白、尿素氮的含量影响不显著(P>0.05)。3)随着饲粮中维生素A添加水平的提高,血清及肝脏中维生素A含量极显著增加(P<0.01)。由此可见,本试验条件下,以生长性能作为衡量标准,1～4周龄青农灰鹅饲粮维生素A适宜添加水平为8 000 IU/kg,5～12周龄为9 000 IU/kg;以血清生化指标作为衡量标准,1～4、5～12周龄维生素A添加水平均以6 000 IU/kg为宜。     

大口黑鲈维生素A需求量

为了评定大口黑鲈饲料中维生素A的需求量,本研究在基础饲料中添加不同量(0、1 000、2 000、3 000和4 000 IU/kg)的维生素A醋酸酯,配制5种不同维生素A含量(实测维生素A含量分别为415、1 406、2 755、3 501和4 646 IU/kg)的等氮等能饲料(粗蛋白质含量48.47%;总能18.15 M J/kg)。用上述饲料饲喂初始体重为(52.75±0.12)g的大口黑鲈49 d,每个处理设3个重复,每重复30尾鱼。结果表明:随着饲料中维生素A水平从415 IU/kg升高到2 755 IU/kg,试验鱼的增重率、特定生长率、饲料效率和蛋白质效率均显著升高(P0.05);而随饲料维生素A水平的进一步增高,上述指标则呈平稳的趋势。随着饲料中维生素A水平从415 IU/kg升高到3 501 IU/kg,鱼的肝脏中维生素A含量、肝脏总超氧化物歧化酶活性、血清溶菌酶活性,头肾白细胞呼吸爆发活性、血清补体活性及血红蛋白含量显著升高(P0.05),而肝脏丙二醛含量显著降低(P0.05);随饲料维生素A水平的进一步增高,上述指标变化幅度较小。饲料中不同维生素A水平对鱼的血清总蛋白含量和红细胞压积的影响不显著(P0.05)。分别以增重率和肝脏维生素A含量为评价指标,采用折线模型求得,大口黑鲈对饲料中维生素A的最适需求量分别为2 600和3 550 IU/kg;而以非特异性免疫为评价指标,通过方差分析得出的最适需求量与以肝脏维生素A含量为评价指标所得出的需求量相近。本研究得出,大口黑鲈对饲料中维生素A水平的最适需求量为2 600~3 550 IU/kg。     

维生素A对青农灰鹅屠宰性能和免疫性能的影响

试验选用1日龄青农灰鹅200只,随机分为5个处理,每处理4个重复,每重复10只。在玉米-豆粕型日粮基础上分别添加0(Ⅰ组)、1500(Ⅱ组)、3000(Ⅲ组)、6000 IU/kg(Ⅳ组)和12000 IU/kg(Ⅴ组)的维生素A,试验期为12周。结果表明:日粮添加维生素A能显著提高12周龄青农灰鹅屠宰率、全净膛率、半净膛率(P<0.05),但对4周龄鹅屠宰性能的影响不显著(P>0.05);基础日粮添加维生素A能极显著提高4周龄青农灰鹅胸腺指数及淋巴细胞转化率(P<0.01),显著提高12周龄胸腺指数(P<0.05),极显著提高12周龄法氏囊指数和淋巴细胞转化率(P<0.01),日粮添加维生素A能显著提高免疫后7、14 d鹅禽流感抗体效价(P<0.05)。结果显示,日粮中添加维生素A可提高青农灰鹅的屠宰性能和免疫性能。综合各项指标,本试验条件下,0～4周龄和5～12周龄维生素A添加水平均以7000 IU/kg为宜。     

Effect of Vitamin C on pulmonary hypertension and muscularisation of pulmonary arterioles in broilers

1. Three hundred and eighty 1-day-old Arbor Acres broilers were divided into control (A) and experimental (B, C, D, and E) groups. 2. After 14 d of age the experimental groups were subjected to a cool temperature challenge by lowering the temperature 1 to 2°C per day down to 12°C, and maintaining this temperature until 7 weeks of age. 3. At the same time, l.5 mg/kg 3,3,5-triiodothyronine (T 3 ) was added to the diet of groups D and E, and 500mg/kg ascorbic acid (vitamin C) to the diet of groups C and E. 4. The incidence of pulmonary hypertension syndrome (PHS), body weight gain and feed intake were measured weekly. Lung and blood samples were collected weekly from 10 birds per group beginning on d 14, and the percentage of thick-walled peripheral lung vessels (%TWPV) and packed cell volume (PCV) were determined. 5. The lower ambient temperature and diets supplemented with T 3 increased PHS incidence and % TWPV and decreased body weight gain. 6. There was an increase in PCV after 5 weeks of age under lower ambient temperature 3 and the PCV values 14 were also significantly increased by T 3 . 7. Vitamin C supplementation reduced PHS incidence and % TWPV but did not change packed cell volume, body, weight gain, feed intake, or feed conversion. 8. It is concluded that vitamin C reduced PHS and the associated muscularisation of pulmonary arterioles induced by exposing broilers to cool environmental temperatures and feeding them with T 3 .     

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。     

Effect of dietary supplementation with vitamins E and C on production performance, immune responses and antioxidant status of White Leghorn layers under tropical summer conditions

1. The effects of vitamin E (DL-alpha-tocopheryl acetate) and vitamin C (ascorbic acid) supplementation on performance, some immune variables and antioxidant status of White Leghorn layers (aged 44-56 weeks) exposed to tropical summer conditions were investigated. 2. Both vitamins E and C significantly improved the egg production, food conversion efficiency, antibody responses to inoculated sheep red blood cells (SRBC) and Newcastle disease virus (NDV) vaccine, lymphocyte proliferation in response to mitogen and activities of antioxidant enzymes red blood cell catalase (RBCC) and glutathione peroxidase (GSH-PX) in layers. Vitamin C increased the inflammatory response to phytohaemagglutinin-P (PHA-P) inoculation. 3. Supplemental vitamin C at 200 mg/kg diet significantly increased eggshell weight, eggshell thickness, and shell breaking strength. However, no effect of supplemental vitamin E on eggshell quality was observed. 4. Vitamins E and C, as well as interactions between them, significantly influenced the activities of glutathione reductase and lipid peroxidase. A combination of vitamin E at 125 IU/kg with vitamin C at 200 mg/kg diet had an additive effect on reducing the activity of oxidative enzyme lipid peroxidase (LP) and increasing the activity of antioxidant enzyme glutathione reductase (GSHR). 5. It is concluded that vitamin E (125 IU/kg) and vitamin C (200 mg/kg) could independently alleviate the effects of heat stress on production performance and immunological variables of layers. However, combination of both the vitamins at the above-mentioned concentrations is beneficial in eliciting higher antioxidant status in laying hens exposed to tropical summer conditions.     

Compensatory growth after under-nutrition in market turkeys: effect of low protein feeding and realimentation on body composition

Turkey poults were fed starter diets containing either 29 or 20 per cent crude protein. Live‐weight at 6 weeks was depressed by about 30 per cent in poults fed the low protein diet. From 6 to 10 weeks of age four protein levels were fed but carcass studies were restricted to the groups which received adequate amounts of protein at this stage. Sixty poults from each treatment were slaughtered for carcass studies at 6 weeks of age, and also at 7 weeks when the undernourished poults had reached the body weight attained by fully fed groups at 6 weeks. Further samples were taken for carcass analysis at 20 weeks of age.

Percentage body fat was increased and percentage protein in the fat‐free dry matter was decreased by feeding a low protein starter diet from o to 6 weeks. Poults fed the low protein starter diet retained nitrogen more efficiently during the period of undernutrition and in the first stages of recuperation. Following a return to full feeding at six weeks, body protein content was quickly restored, but a longer period was required before their body fat percentage was reduced to the level of fully fed controls.

The organs which were weighed were little affected, except in the case of the gizzard and liver which became proportionately heavier in retarded turkeys at 6 weeks of age. Only spleen weight appeared to have been reduced in relation to total body weight but it occupied a similar proportion in high and low groups when compared on a fat‐free basis. Some, but not all, of the organs weighed were restored to normal proportions by 20 weeks of age. However, dressing percentage and economic value of carcasses at market weight were not materially affected by early nutritional treatment.     

饲粮维生素A添加水平对7～12月龄梅花鹿生长性能、血清生化指标及初角茸生长的影响

本试验旨在研究饲粮维生素A添加水平对7~12月龄梅花鹿生长性能、血清生化指标及初角茸生长的影响。选取40只7月龄平均体重为(39.64±4.10)kg的健康雄性梅花鹿,随机分成4组,每组10个重复,每个重复1只,分别饲喂在基础饲粮(含5 mg/kgβ-胡萝卜素)中添加0(对照组)、2 500、5 000和10 000IU/kg维生素A的试验饲粮。试验期从7月龄开始至12月龄结束。结果表明:1)饲粮维生素A添加水平对梅花鹿生长性能无显著性影响(P0.05)。2)与对照组相比,饲粮添加2 500、5 000IU/kg维生素A显著提高梅花鹿血清免疫球蛋白A(IgA)含量、总超氧化物歧化酶(T-SOD)活性(P0.05),饲粮添加2 500、5 000、10 000IU/kg维生素A显著提高谷胱甘肽过氧化物酶(GSH-Px)活性(P0.05),饲粮维生素A添加水平对血清免疫球蛋白G(IgG)、免疫球蛋白M(IgM)、丙二醛(MDA)、睾酮(T)及雌二醇(E2)含量无显著性影响(P0.05)。3)5 000IU/kg维生素A添加组初角茸干茸重显著高于对照组(P0.05),但与其他2组差异不显著(P0.05)。由此得出,在本试验条件下,适量添加维生素A能够增强7~12月龄梅花鹿免疫和抗氧化功能,提高初角茸干茸重。7~12月龄梅花鹿饲喂以玉米和苜蓿草粉为主的饲粮时,饲粮维生素A适宜添加水平为2 500~5 000IU/kg。     

Effects of dietary supplemental L-carnitine and ascorbic acid on performance, carcass composition and plasma L-carnitine concentration of broiler chicks reared under different temperature.

The present study was initiated to determine whether dietary supplemental L-carnitine and ascorbic acid affect growth performance, carcass yield and composition, abdominal fat and plasma L-carnitine concentration of broiler chicks reared under normal and high temperature. During the experiment, two temperature regimes were employed in two experimental rooms, which were identical but different in environmental temperature. The regimes were thermoneutral (20-22 degrees C for 24 h) or recycling hot (34-36 degrees C for 8 h and 20-22 degrees C for 16 h). One-day-old broiler chicks (ROSS) were used in the experiment. A 2 x 2 x 2 factorial arrangement was employed with two levels (0 and 50 mg/kg) of supplemental L-carnitine and two levels (0 or 500 mg/kg) of supplemental ascorbic acid in drinking water under thermoneutral or high temperature regimes. Body weight gain was affected by high temperature. However, body weight gain was significantly improved in animals receiving supplemental L-carnitine, ascorbic acid or L-carnitine + ascorbic acid compared to animals receiving unsupplemented diet under high temperature. On the other hand, supplemental L-carnitine or L-carnitine + ascorbic acid reduced body weight gain under thermoneutral condition. Supplemental ascorbic acid significantly improved feed conversion efficiency, the improvement was relatively greater under high temperature. The L-carnitine content in the plasma was higher in the groups receiving supplemental L-carnitine and ascorbic acid under high temperature, while broilers fed supplemental L-carnitine and ascorbic acid had a decreased level of plasma L-carnitine concentration under normal temperature. It is concluded that dietary supplemental L-carnitine or L-carnitine + ascorbic acid may have positive effects on body weight gain, carcass weight under high temperature conditions.     

Investigation on the growth of coprophagy-prevented rats with supplemented vitamin B12

The growth of coprophagy-prevented rats was compared under administration of normal levels of vitamin B12 and supplemented amounts. Two experiments in which supplemented amounts of vitamin B12 were administered were conducted under different conditions. Six rats per group were fed under coprophagy-allowed (conventional feeding) and coprophagy-prevented conditions respectively. In the first experiment, coprophagy-prevented rats were fed only feed containing recommended vitamin B12 level and forced fed hydrous faeces, vitamin B12 and folic acid respectively. In the second experiment, coprophagy-prevented rats were fed AIN-93G at the recommended vitamin B12 level (25 microg/kg diet), at 100 times the level and at 1000 times the level respectively. Body weight, feed consumption and amounts of each faeces type were determined in both experiments. In a comparison of body weight gain, we learned that coprophagy prevention reduced the values, but that there was no significant difference in the forced feeding group in the first experiment. Similar results were recognized in the second experiment. Vitamin B12 supplementation was not able to raise feed intake significantly and hence it obviously was not a severely limiting factor under the respective experimental condition which depressed feed intake.     

Effect of benzoic acid on growth performance, nutrient digestibility, nitrogen balance, gastrointestinal microflora and parameters of microbial metabolism in piglets

In order to investigate the effects of benzoic acid on growth performance, nutrient digestibility, nitrogen balance and gastrointestinal microflora of piglets, we conducted a performance experiment and a separate balance study. The performance experiment involved four different dietary treatments: (1) basal diet (negative control); (2) basal diet supplemented with benzoic acid at 5 g/kg; (3) basal diet supplemented with benzoic acid at 10 g/kg; (4) basal diet supplemented with potassium diformate at 12 g/kg. Each dietary treatment was assigned to nine replicate groups, each consisting of two piglets. Live weight, daily weight gain, feed intake and feed conversion ratio were monitored as performance parameters over a 35-day period. Supplementation of the diet with benzoic acid resulted in a dose-dependent increase in feed intake and body weight gain and an improved feed conversion ratio. Piglets fed the diet supplemented with benzoic acid at 10 g/kg outperformed the control piglets in mean feed intake, body weight gain and feed conversion ratio by 9%, 15% and 6% respectively. Growth performance of the piglets fed the diet with benzoic acid at 10 g/kg was similar to that of piglets fed the diet supplemented with potassium diformate. In the balance experiment three groups of six piglets each were fed either a control diet or diets supplemented with benzoic acid at 5 or 10 g/kg respectively. Benzoic acid did not significantly affect nutrient digestibility but increased nitrogen retention. Piglets fed the diets supplemented with benzoic acid at 5 or 10 g/kg retained 5% and 6% more nitrogen, respectively, than control piglets. Supplementation of benzoic acid did not influence the pH value or the concentration of ammonia in the gastrointestinal tract but reduced the number of bacteria in the digesta. In the stomach the number of total aerobic, total anaerobic, lactic acid forming and gram-negative bacteria was reduced; in the duodenum the presence of benzoic acid reduced the number of gram-negative bacteria and in the ileum the number of total aerobic bacteria in a dose-dependent manner. Benzoic acid also considerably reduced the concentration of acetic acid in the duodenum. In conclusion, the data of this study suggest that benzoic acid exerts strong antimicrobial effects in the gastrointestinal tract of piglets and therefore enhances growth performance and nitrogen retention.     

Beta-carotene supplementation of turkey diets varying in fat and retinol

1. The effects of supplementary beta-carotene (BC) at 0, 1.5, 15, 150, 1500 or 15,000 mg/kg diet on performance, incidence of leg problems, tibia ash, and plasma and liver concentration of BC and retinol of poults to 4 weeks of age were studied. 2. Body weight and food intake increased with dietary BC supplementation. Incidence of leg problems was not affected but tibia ash increased with BC supplementation. Plasma and liver BC and liver retinol increased with dietary BC but plasma retinol was not affected. 3. The effects of 0, 1.5, 15 or 150 mg BC/kg in diets containing either 30 or 60 g added fat/kg and either 1.2 or 12.0 mg retinol/kg on the above properties were studied in poults to 4 weeks of age. 4. Performance was not significantly affected by dietary fat. Efficiency of utilisation of food was depressed by the higher concentration of retinol. At 3 weeks of age birds given BC had fewer leg problems and higher tibia ash values than the control birds. Liver BC and retinol and plasma BC concentration increased with dietary BC. By 4 weeks, plasma and liver BC was higher and liver retinol was lower for birds given 1.2 compared with those given 12.0 mg/kg of retinol.     

中能中蛋白水平下维生素A、D3对0～6周龄肉仔鸡生产性能的影响

采用3×3随机交叉试验设计,研究中能中蛋白水平下日粮VA、VD3对肉仔鸡生产性能的影响。1日龄AA肉仔鸡540只随机分为9组,每组3个重复,每重复20只鸡。3个VA添加水平为3000、6000、12000IU/kg;3个VD3添加水平为200、400、800IU/kg;0～3和4～6周龄基础日粮代谢能、粗蛋白水平分别为12.34MJ/kg,21%;12.76MJ/kg,19%。结果表明:①日粮VA水平对体增重、耗料量、料重比、存活率均无显著影响(P>0.05);②随VD3添加水平的增加,体增重、耗料量、存活率显著增加(P<0.05);③综合考虑生产性能和经济效益,认为0～3和4～6周龄肉仔鸡日粮VA添加量均以3000IU/kg较为适宜,VD3添加量均以800IU/kg较为适宜。     

中能中蛋白水平下维生素A、D3对0～6周龄肉仔鸡生产性能的影响

采用3×3随机交叉试验设计,研究中能中蛋白水平下日粮VA、VD3对肉仔鸡生产性能的影响。1日龄AA肉仔鸡540只随机分为9组,每组3个重复,每重复20只鸡。3个VA添加水平为3000、6000、12000IU/kg;3个VD3添加水平为200、400、800IU/kg;0～3和4～6周龄基础日粮代谢能、粗蛋白水平分别为12.34MJ/kg,21%;12.76MJ/kg,19%。结果表明：①日粮VA水平对体增重、耗料量、料重比、存活率均无显著影响（P〉0.05）;②随VD3添加水平的增加,体增重、耗料量、存活率显著增加（P〈0.05）;③综合考虑生产性能和经济效益,认为0～3和4～6周龄肉仔鸡日粮VA添加量均以3000IU/kg较为适宜,VD3添加量均以800IU/kg较为适宜。