The utilization of raw and autoclaved faba beans (Vicia faba L., var. minor) and faba bean fractions in diets for growing boiler chickens

The effects of the inclusion of raw and autoclaved whole faba beans (Vicia faba; RFB and AFB respectively) or faba bean fractions (cotyledons and hulls) in diets for growing broiler chickens (0-4 weeks of age) on performance, intestinal physiology and jejunal histological structure have been studied in three experiments. Significant decreases in body-weight as well as lower food consumption and higher food intake:weight gain ratio were observed in those animals fed on diets containing 250, 350 and 500 RFB/kg in the diet. Birds fed on AFB diets (500 g/kg) had significantly greater body-weights than chicks fed on RFB or raw faba bean cotyledons (RC). Significant increases in the relative lengths of duodenum, jejunum, ileum and caeca, pancreas relative weight, and intestinal transit time of birds fed on diets containing 250, 350 and 500 g RFB/kg compared with control birds were observed. Including AFB (500 g/kg) in the diet significantly increased body-weight and significantly decreased pancreas weight compared with RFB (500 g/kg)-fed birds. The inclusion of RFB hulls had no effect on these variables. Dehulling or autoclaving of faba beans, or both, proved to have no significant effect on relative lengths of duodenum, jejunum, ileum and caeca, nor on caecal volatile fatty acid concentration in birds fed on 500 g faba beans/kg diet. Electron microscopy of the jejunal mucosa revealed discrete hyperplasia of polysomes and mitochondrial swelling in those animals fed on AFB (500 g/kg) or AC (426.4 g/kg). Pronounced strangulations were also observed along the microvilli, whose length was similar to that of control birds. The inclusion of RFB hulls, either autoclaved or raw, led to no ultrastructural changes in the enterocytes, as detected by electron microscopy. Birds fed on diets containing the cotyledons of RFB (RC, 426.4 g/kg) rather than whole RFB showed the same ultrastructural disorders as RFB (500 g/kg)-fed birds. The present study shows that factors other than those usually claimed, i.e. protease inhibitors, phytates, tannins and lectins, may be contributing to the low nutritional value of V. faba seeds for growing chickens.     

三种维生素对仔鸡发育及组织维生素含量的影响

目的：　研究日粮维生素Ａ（ＶＡ）、维生素Ｄ（ＶＤ）、维生素Ｅ（ＶＥ）在营养方面的相互影响。方法：　在基础日粮中添加不同剂量的维生素组成试验日粮进行动物试验,测定肉鸡的增重、饲料转化率和组织维生素含量。　结果：　当饲粮ＶＥ含量为２０ ＩＵ／ｋｇ 时,采食每千克饲粮添加２０ ０００ＩＵ ＶＡ的仔鸡增重显著低于采食每千克饲粮添加１ ５００ＩＵ 的仔鸡（Ｐ＜ ０．０５）;高ＶＡ组鸡的血浆和肝脏ＶＥ含量非常显著低于低ＶＡ组（Ｐ＜ ０．０１）,表明日粮高水平ＶＡ可能抑ＶＥ的吸收;当饲粮ＶＡ含量为３０ ０００ＩＵ／ｋｇ、ＶＥ为２０ＩＵ／ｋｇ 时,随ＶＤ水平极度提高,雏鸡体重呈下降趋势。而饲粮ＶＤ含量为２００ＩＵ和１ ０００ＩＵ／ｋｇ 对鸡生长及血液和肝脏ＶＡ、ＶＥ含量无显著性影响;当ＶＥ水平提高到２００ ＩＵ／ｋｇ,ＶＤ水平提高到８ ０００ ＩＵ／ｋｇ 时,雏鸡体重显著增加（Ｐ＜ ０．０５）;在相同ＶＤ水平下,高水平ＶＥ日粮组试鸡的体重均高于低水平日粮组。结论：日粮ＶＡ、ＶＤ和ＶＥ间存在着显著的相互影响,在配制动物日粮时应注意ＶＡ、Ｄ和Ｅ的适宜比例关系。     

Prevention of immunologic stress contributes to the growth-permitting ability of dietary antibiotics in chicks.

The growth-permitting ability of antibiotics fed to broiler chicks was studied as it relates to the state of activation of the immune system. In Experiment 1, chicks were fed two levels of antibiotics (0 or 100 mg streptomycin + 100 mg penicillin/kg diet) and were raised either in an environment with poor sanitation to create a chronic immune stress or in a clean environment. Chicks raised in the unsanitary environment and not fed antibiotics had significantly lower (P < 0.05) rates of weight gain and efficiencies of feed utilization, and higher levels of plasma interleukin-1, compared with chicks raised in the clean environment or chicks raised in the unsanitary environment and fed antibiotics. Adding antibiotics to the diet of birds in the clean environment did not affect any variable. In Experiment 2, chicks were raised in a conventional environment and fed two levels of an antibiotic (0 or 100 mg tetracycline/kg diet). After a 15-d feeding period, half of the chicks were injected with Salmonella typhimurium lipopolysaccharide to create an acute immunologic stress. Feeding antibiotic resulted in improved weight gain, feed consumption and efficiency of feed utilization. Lipopolysaccharide-injected birds developed heavier livers, spleens and intestines relative to body weights and higher rectal temperatures and hepatic metallothionein concentrations, presumably due to an immunologic stress. Omitting antibiotic from the diet resulted in similar changes. These results indicate that feeding antibiotics may permit growth by preventing immunologic stress and associated metabolic changes brought about by monokines including interleukin-1.     

Hormonal responses to protein restriction in two strains of chickens with different growth characteristics

The hormonal response to protein restriction was studied in breeds of chickens with different rates of growth and body size. Fast-growing (broiler) chicks and lighter-weight (White Leghorn) birds were fed isoenergetic 5% (low) and 20% (control) protein diets ad libitum starting at 2 wk of age. At 4 wk of age, one-half of each group continued receiving the initial diet, while the other half was fed the alternate diet for two additional weeks. Growth was decreased in birds fed the low protein diet due to restriction of protein, sustained low feed intake and hence possibly insufficient energy for growth. Birds fed low protein diets had higher plasma growth hormone (GH) concentrations (325% in Leghorns and 233% in broilers) compared with controls. Plasma concentrations of somatomedin-C in protein-restricted Leghorn and broiler chicks were only 50 and 34% of those of controls, respectively. Similarly plasma concentrations of thyroxine (T4) and triiodothyronine (T3) were reduced in protein-deprived birds compared with those fed adequate protein. Plasma T3 concentrations of restricted birds were 48 (Leghorns) and 47% (broilers) of those of controls, whereas plasma T4 concentrations were 44 (Leghorns) and 41% (broilers) of those of controls.     

Evaluation of turmeric extract on performance indices impressed by induced aflatoxicosis in broiler chickens

The purpose of this study was evaluation of ethanolic turmeric extract (ETE; Curcuma longa) effect on overall performance including body weight (BW), body weight gain (BWG), feed intake and feed conversion ratio (FCR) weekly and cumulative for a period of 4 weeks with 300 commercial broiler chicks (Ross strain). These chicks were randomly divided into four groups with three replicates of 15 chicks in each replicate. In group A, chickens were fed a basal diet, in group B, chickens were fed a basal diet plus 3 ppm productive aflatoxin. In group C, chickens consumed a basal diet plus 0.05% ETE and in group D, chickens received a basal diet with 0.05% ETE plus 3 ppm productive aflatoxin. Aflatoxin production by Aspergillus parasiticus (PTTC NO:1850) in maize was according to the Shotwell method. The results revealed that there were no significant differences in BW, BWG and FCR between groups fed turmeric at 0.05% and the control group. The supplement of ETE in a diet containing 3 ppm aflatoxin can significantly improve performance indices compared with the group that consumed aflatoxin alone. In conclusion, our results suggest that turmeric extract (Curcuma longa) can provide protection against the negative effects of aflatoxin on performance of broiler chickens.     

Aluminum and Acid Effects on Calcium and Phosphorus Metabolism in Young Growing Chickens (Gallus gallus domesticus) and Mallard Ducks (Anas platyrhynchos)

Acidification is associated with increased mortality, reduced growth, and bone abnormalities in birds. Associated with acid deposition is an increase in aluminum availability due to solubilization from soil and other sources. (Conversely, experimental diets containing aluminum sulfate have much reduced pHs.) The present studies compare the effects of two levels of dietary acid (sulfuric acid) (0.122 and 0.56 mol H⁺ per kg feed; 0.056 and 0.277 mol sulfate per kg feed) and dietary aluminum (aluminum sulfate at 0.1 and 0.5%; sulfate at 0.056 and 0.277 mol sulfate per kg feed) on bone growth, mineralization, and phosphorous/calcium homeostasis in growing birds (chickens and mallard ducks). Growth was reduced by the high acid (chicken) and aluminum (ducks and chickens) diets. A reduction in bone mineralization was observed in birds receiving aluminum-containing diets [low aluminum diet: decreased tibia ash, calcium, and phosphorus (chickens); high aluminum diet: decreased tibia dry weight, % of ash and mg; ash, calcium (chickens, ducks as % of ash), and phosphorus (chickens mg/duck, % of ash)]. Moreover, plasma concentrations of inorganic phosphate were reduced in chicks on the high aluminum diet. There were also marked decreases in bone growth and mineralization [tibia weight, ash (mg), calcium (mg), phosphorus (mg)] and plasma concentrations of 1,25-dihydroxy vitamin D₃ in chicks on the high acid diet compared to those on a control diet. These changes were probably due to reduced feed intake; changes in bone indices being of a greater or similar magnitude in pairfed control. There was little change in bone indices, growth rate or feed consumption in ducklings receiving either the low or high acid diets. It is concluded that aluminum directly adversely affected bone mineralization whereas acid effects are mediated in part by changes in feed consumption. Received: 22 July 1997/Accepted: 29 November 1997     

Effect of viscosity on digestion of nutrients in conventional and germ-free chicks

A study was conducted with conventional and germ-free broiler chicks to obtain more information on the role of the intestinal microflora in the anti-nutritive effects of NSP in broiler chicks. As the NSP source, highly methylated citrus pectin (HMC) was used at a dose level of 30 g/kg in a maize-based diet. The diets fed to the germ-free chicks were gamma-irradiated, whereas those fed to the conventional chicks were not. Feeding the HMC diet to conventional birds depressed weight gain and food utilization (P < 0.05), whereas in germ-free birds only weight gain was reduced (P < 0.05). Feeding the HMC diet to conventional birds reduced digestibilities of energy and starch at the end of the jejunum. Ileal digestibilities of starch and energy were not strongly affected when birds were fed on the HMC-containing diet. Faecal digestibilities of organic matter, crude fat, starch and amino acids, N retention and metabolizable energy were reduced when conventional chicks were fed on the HMC diet. Feeding the HMC diet to germ-free birds hardly affected faecal digestibility of nutrients and N retention, whereas metabolizable energy was increased. Feeding the HMC diet to conventional or germ-free birds increased the viscosity of the digesta in the small intestine. This increase in digesta viscosity was more pronounced in conventional than in germ-free birds. The pH of ileal digesta was reduced when HMC was added to the diet of conventional chicks, but not in germ-free chicks. Feeding the HMC diet to conventional birds markedly affected morphology of the gut wall, whereas in germ-free chicks very little effect was found on gut morphology. Based on the results of the present study, it is concluded that the gastrointestinal microflora mediates the magnitude of the anti-nutritive effects of HMC in broiler chicks. However, the exact role of the microflora in chicks in the magnitude of the anti-nutritional effects of HMC could not be derived from the present study, since the results might have been influenced by gamma-irradiation of the diets fed to the germ-free chicks.     

Dietary n-3 and n-6 fatty acids alter avian metabolism: metabolism and abdominal fat deposition

The effects of dietary saturated fatty acids and polyunsaturated fatty acids (PUFA) of the n-3 and n-6 series on weight gain, body composition and substrate oxidation were investigated in broiler chickens. At 3 weeks of age three groups of chickens (n 30; ten birds per group) were fed the fat-enriched experimental diets for 5 weeks. These diets were isonitrogenous, isoenergetic and contained 208 g protein/kg and 80 g edible tallow, fish oil or sunflower oil/kg; the dietary fatty acid profiles were thus dominated by saturated fatty acids, n-3 PUFA or n-6 PUFA respectively. Resting RQ was measured in five birds from each treatment group during weeks 4 and 5 of the experiment. There were no significant differences between treatments in total feed intake or final body mass. Birds fed the PUFA diets had lower RQ and significantly reduced abdominal fat pad weights (P<0.01) compared with those fed tallow. The dietary lipid profile changes resulted in significantly greater partitioning of energy into lean tissue than into fat tissue (calculated as breast lean tissue weight:abdominal fat mass) in the PUFA groups compared with the saturated fat group (P<0.01; with no difference between the n-3 and n-6 PUFA groups). In addition, the PUFA-rich diets lowered plasma concentrations of serum triacylglycerols and cholesterol. The findings indicate that dietary fatty acid profile influences nutrient partitioning in broiler chickens.     

Effect of a mixture of conjugated linoleic acid isomers on growth performance and antibody production in broiler chicks

The effect of dietary conjugated linoleic acid (CLA) isomers mixture on antibody titres against sheep blood erythrocytes (SRBC) and immunoglobulin (Ig) G concentration in plasma was studied in broiler chickens. In experiment 1, male and female broiler chicks (11 d of age, Cobb strain) were fed a diet supplemented with 10 g CLA or 10 g safflower-seed oil/kg diet for 2 weeks. An SRBC suspension (5:100, v/v) in a phosphate buffer was intravenously injected at 18 d of age and a blood sample was taken from the wing vein at 25 d of age. Chicks fed the CLA-supplemented diet had enhanced first antibody titres in plasma to SRBC as compared with those fed the safflower-seed oil-supplemented diet, irrespective of sex differences. In experiment 2, male broiler chicks (8 d of age, Ross strain) were fed a basal diet or a diet containing 10 g CLA/kg diet for 3 weeks. CLA in the CLA diet partially replaced the soyabean oil in the basal diet. The SRBC suspension was intravenously injected at 15 and 25 d of age and a blood sample was obtained at 21 and 29 d of age. The first antibody titres against SRBC were higher in chicks fed the CLA diet than those in chicks fed the basal diet, but the second titres were not. Plasma IgG concentrations in chicks fed the CLA diet were higher than those in chicks fed the basal diet on both sampling days. The results showed that dietary CLA enhanced antibody production in broiler chickens.     

Evidence of a glucose-insulin imbalance and effect of dietary protein and energy level in chickens selected for high abdominal fat content

Effects of dietary protein or energy level on growth and physiological parameters were investigated in growing chickens selected for high (fat line, FL) or low (lean line, LL) abdominal fat but similar body weight. The FL birds deposited consistently more abdominal fat (about two-fold) and had poorer feed conversion, irrespective of diet. Increasing the ratio of energy to protein increased fat deposition similarly but at different levels. Body weight and feed consumption showed only minor and inconsistent differences and feed consumption following a fast and body temperature in the fed or the fasted-state showed no differences between lines. Fasting plasma glucose levels were similar for both lines at hatching but consistently lower in FL birds thereafter. This was matched by higher fasting plasma insulin levels. A similar relationship was also observed in fed FL birds at 2 weeks of age. Glucose disposal rate was faster in FL birds at 4 and 6 weeks but normal by 8 weeks. The glucose-induced insulin release was higher in FL birds at 6 and 8 weeks, indicating a normal sensitivity to insulin at a young age, with the development of a tissue insulin resistance by 8 weeks of age. The primary mechanism responsible for the fattening of FL birds appears therefore to be greater insulin release from the pancreas of the FL birds soon after hatching.     

Involvement of lipoic acid in plasma metabolites, hepatic oxygen consumption, and metabolic response to a beta-agonist in broiler chickens

The present study was conducted to determine the role of alpha-lipoic acid (LA) in plasma metabolites, hepatic O2 consumption, and beta-adrenergic response in broilers. In Expt 1, 12-d-old female broiler chicks were divided into three dietary groups and fed on diets with or without LA (5 or 50 mg/kg) until 4 or 6 weeks of age, as a 2 x 3 factorial arrangement. The dietary LA had no effect on growth rates (body weight, abdominal fat, breast muscle, and liver). The higher level of LA increased plasma non-esterified fatty acid and decreased plasma triacylglycerol concentrations only at 6 weeks of age. A 42% increase in hepatic respiration was observed in the 4-week-old chickens given 50 mg LA/kg diet. In Expt 2, 3-d-old female broiler chicks were treated with or without dietary LA at 50 mg/kg. At 30 and 31 d old, isoproterenol (2 mg/kg body weight per h) was continuously infused into a wing vein for 2 h, and changes in plasma glucose, triacylglycerol, and non-esterified fatty acid concentrations were analysed. Isoproterenol increased plasma glucose over basal levels maximally at 60 min. Furthermore, the glucose increase in the LA-treated chickens was 35% greater than that of the controls at this time. Plasma non-esterified fatty acid and triacylglycerol concentrations were decreased by the isoproterenol infusion, regardless of LA administration. Therefore, the present study suggests that dietary LA has repartitioning effects on energy metabolism in chickens (although this depends on age-related metabolic state) and is a possible facilitator in the beta-adrenergic response of plasma glucose to a beta-agonist.     

Selenium influences growth via thyroid hormone status in broiler chickens

As there is a possibility that Se influences the growth of animals via thyroid hormone metabolism, the following three experiments were undertaken in order to determine the effects of dietary Se on growth, skeletal muscle protein turnover and thyroid hormone status in broiler chickens. Broiler chickens were raised on a Se-deficient diet until 12 d of age and then used for the experiments. In Experiment 1, twenty-eight birds were randomly assigned to four groups and fed purified diets with the following amounts of Se supplementation: 0.0, 0.1, 0.3 and 0.5 mg Se/kg diet. Dietary Se supplementation significantly increased plasma 3,5,3'-triiodothyronine (T3) concentration and improved growth, while plasma thyroxine (T4) concentration was decreased. In Experiment 2, twenty-eight birds were assigned to four groups and fed either a Se-deficient diet or a Se-supplemented diet (0.3 mg Se/kg diet) with or without the supplementation of iopanoic acid, a specific inhibitor of 5'-deiodinase (5 mg/kg diet). The growth was promoted and feed efficiency was improved by dietary Se supplementation as was also observed in Experiment 1. However, this effect of Se was halted by iopanoic acid supplementation. Hepatic 5'-deiodinase activity was elevated by Se and inhibited by iopanoic acid. In Experiment 3, birds were fed on the following diets to show that Se influences growth of birds via thyroid hormone metabolism: Se-deficient diet, Se-supplemented diets (0.1 and 0.3 mg/kg) and T3 supplemented diets (0.1 and 0.3 mg/kg diet). Lower dietary T3 supplementation (0.1 mg/kg diet) resulted in growth promotion similar to Se supplementation, while higher level of T3 caused growth depression. Furthermore, it was observed that the rate of skeletal muscle protein breakdown tended to be increased by Se similarly to the effect of T3. In conclusion, it was shown in the present study that Se deficiency depresses growth of broilers by inhibiting hepatic 5'-deiodinase activity which causes lower plasma T3 concentration.     

Barley beta-glucans alter intestinal viscosity and reduce plasma cholesterol concentrations in chicks.

Ninety-six 14-d-old male broiler chicks were divided into three dietary groups and fed a corn-soybean meal diet, a barley diet with beta-glucanase and that diet without beta-glucanase. All diets contained 4 g cholesterol/kg. Average daily body weight gain, plasma total cholesterol concentration, LDL cholesterol concentration and digestibility of lipids and protein were lowest (P < 0.05) in the chicks fed the barley diet without beta-glucanase and highest (P < 0.05) in the chicks fed corn-soybean meal diet. Supplementation of the barley diet with beta-glucanase resulted in greater (P < 0.05) average daily weight gain, plasma total and LDL cholesterol concentrations and digestibility of lipids. Viscosity of small intestinal digesta was greatest in chicks fed barley, lowest in those fed the corn-soybean diet and intermediate in chicks fed enzyme-treated barley. Significant (P < 0.01) negative correlations occurred between viscosity of the small intestinal contents and average daily weight gain, plasma total and LDL cholesterol concentrations, and digestibility of lipids and protein. A lower concentration of insoluble beta-glucans in small intestinal digesta of the chicks fed barley supplemented with beta-glucanase compared with the chicks fed the unsupplemented barley diet reflects hydrolytic activity of the supplemental beta-glucanase in the diet.     

Influence of broccoli extract and various essential oils on performance and expression of xenobiotic- and antioxidant enzymes in broiler chickens

The aim of our present study was to examine the regulation of xenobiotic- and antioxidant enzymes by phytogenic feed additives in the intestine and the liver of broilers. A total of 240 male Ross-308 broiler chickens (1 d old) were fed a commercial starter diet for 2 weeks. On day 15, the birds were assigned to six treatment groups of forty birds each. The control (Con) group was fed a diet without any additive for 3 weeks. The diet of group sulforaphane (SFN) contained broccoli extract providing 0.075 g/kg SFN, whereas the diets of the other four groups contained 0.15 g/kg essential oils from turmeric (Cuo), oregano (Oo), thyme and rosemary (Ro). Weight gain and feed conversion were slightly impaired by Cuo and Oo. In the jejunum SFN, Cuo and Ro increased the expression of xenobiotic enzymes (epoxide hydrolases 1 and 2 and aflatoxin B1 aldehyde reductase) and of the antioxidant enzyme haeme oxygenase regulated by an 'antioxidant response element' (ARE) compared to group Con. In contrast to our expectations in the liver, the expression of these enzymes was decreased by all the additives. Nevertheless, all the additives increased the Trolox equivalent antioxidant capacity of the jejunum and the liver and reduced Fe-induced lipid peroxidation in the liver. We conclude that the up-regulation of ARE genes in the small intestine reduces oxidative stress in the organism and represents a novel mechanism by which phytogenic feed additives improve the health of farm animals.     

Some mechanisms of reduction of carotenoid levels in chickens infected with Eimeria acervulina or E. tenella.

The levels of plasma carotenoids were markedly reduced in broiler cockerels infected with Eimeria acervulina or E. tenella. The mechanisms of this depigmentation differed between the two species, being primarily associated with interference of absorption of xanthophyll (carotenoids) from the intestinal lumen with E. acervulina infection and with leakage through the damaged wall of the cecum with E. tenella infection. Chicks reared on an essentially carotenoid-free diet and inoculated with E. acervulina showed no detectable levels of carotenoids in the blood 48 hours after being changed to a diet containing 30 mg of xanthophyll/kg. Conversely, uninoculated chicks and chicks inoculated with E. tenella showed significant and similar increases in plasma levels of carotenoids. Chicks reared on a diet containing xanthophyll and inoculated with E. tenella showed a more rapid decrease in plasma carotenoids than did uninoculated controls when changed to a xanthophyll-free diet. In chicks fed high xanthophyll diets containing chromic oxide, no indication of malabsorption was seen in chicks infected with E. tenella compared with uninoculated controls, whereas chicks inoculated with E. acervulina showed significantly less xanthophyll absorption. Conversely, a marked increase in the xanthophyll : Cr2O3 ratio was observed in the cecal contents of chicks inoculated with E. tenella compared with uninuoculated controls or those inoculated with E. acervulina. Studies of uninoculated chicks pair-fed with chicks inoculated with E. acervulina or E. tenella indicated that the decrease in plasma carotenoids and increases in intestinal pH are not associated with the reduced intake of feed associated with infection. The studies involving uninoculated birds with reciprocal chagnes between high and low xanthophyll diets indicated that plasma carotenoids are a more rapid and sensitive means of measuring changes in pigmentation levels than are visual skin scores carotenoid levels from the skin.     

Effect of lead and niacin on growth and serotonin metabolism in chicks

Interactions of lead and niacin were studied in growing broiler chicks fed one of four experimental diets from day-old to 3 wk of age. The diets were a low niacin basal diet (LN), the basal diet supplemented with 40 mg of niacin/kg (control), the basal diet supplemented with 2000 mg lead/kg, as lead acetate (LN + Pb) and the basal diet supplemented with both niacin and lead (control + Pb). Growth and feed efficiency were reduced significantly by lead. The lead-associated growth depression was less severe in chicks fed the low niacin diet as indicated by a significant lead X niacin interaction. The relative weights of two brain regions (telencephalon and diencephalon) and the adrenal glands were greater in lead-treated chicks than in their nonlead-treated counterparts. Plasma and telencephalon tryptophan were lower in lead-treated chicks than in nonlead-treated chicks. Diencephalon tryptophan was lower in chicks fed the LN diet than in chicks fed the control diet. Brain serotonin was lower and 5-hydroxyindoleacetic acid was higher in both brain regions of lead-treated chicks than in nonlead-treated chicks. The data indicate that tryptophan and serotonin metabolism were altered by lead treatment, whereas niacin was without effect. The interaction of lead and niacin on growth does not appear to be related to alterations of serotonin metabolism in the central nervous system.     

Effect of dietary conjugated linoleic acid on body composition and energy balance in broiler chickens

The effect of dietary conjugated linoleic acid (CLA) on body composition and energy metabolism was investigated in broiler chickens. Male broiler chicks were assigned to receive either a control diet (1 % sunflower oil) or a diet containing CLA (1 % of a 1:1 mixture of trans-10, cis-12 and cis-9, trans-11 isomers of octadecadienoic acid). The diets were fed ad libitum for 3 weeks and there were eight replicates per diet, each replicate including four chickens so that each treatment had thirty-two animals. The proportion of body fat was lower in the control group than in the CLA group. No significant differences as to the proportions of body water, ash and protein were observed. Feed and energy intake were significantly lower in CLA-fed birds. The percentage of ingested energy lost in excreta was higher after CLA feeding and heat expenditure as a percentage of ingested energy was lower in the CLA-fed group. The CLA-fed group showed a higher percentage of SFA and lower percentages of MUFA and PUFA in carcass fat. It is concluded that CLA stimulated de novo fatty acid synthesis and lowered desaturase activity.     

Protein and energy relations in the broiler chicken. 8. Comparison involving protein- and lysine-adequate and inadequate diets on lipid metabolism

Chickens were fed on diets containing either 12.8 MJ, 150 g crude protein (nitrogen x 6.25)/kg or 12.8 MJ, 200 g crude protein/kg to determine differences in metabolism. The diet containing 12.8 MJ, 150 g crude protein/kg contained either 8 or 12 g lysine/kg. Treatment variables examined in vitro were lipogenesis, glucose production and hepatic enzyme activities to compare metabolism in chicks fed on a low-protein, lysine-supplemented diet and a diet formulated to contain the required amount of lysine from intact protein. Growth was similar in chicks fed on diets containing either 12.8 MJ, 154 g crude protein with 12 g lysine/kg or 12.8 MJ, 200 g crude protein/kg. Net glucose production was greater (P less than 0.05) in liver explants from chickens fed on diets containing either 12.8 MJ, 154 g crude protein with 12 g lysine/kg or 12.8 MJ, 200 g crude protein/kg than in explants from chickens fed on 12.8 MJ, 150 g crude protein with 8 g lysine/kg. Pyruvate use for glucose production was greater (P less than 0.05) in chickens fed on a diet containing 12.8 MJ, 150 g crude protein with 8 g lysine/kg. The findings from the present study suggest that crystalline and 'natural' lysine additions to chick diets may influence metabolism differently.     

Dietary fat and triiodothyronine (T3) interactions in the broiler chicken.

Male, Indian River, broiler chickens growing from 7 to 28 d were fed on diets containing 180 g crude protein, 300, 600 or 1200 kcal fat calories and 0 or 1 mg T3/kg diet. Birds were bled and sacrificed at d 28, 29 and 30. Measurements taken at these intervals included in vitro lipogenesis (IVL), growth and feed consumption and hepatic enzyme activities. Plasma metabolites as well as thyroid hormones were also determined. Dietary fat levels did not influence growth or feed intake. In contrast, T3 decreased growth and feed intake by 25% without altering the efficiency of feed utilization. Dietary T3 and additional fat decreased IVL and lipogenic enzyme activities. Dietary T3 increased plasma T3 and decreased plasma T4. Dietary fat energy levels had no effect upon plasma thyroid hormone levels. Although both additional dietary fat and T3 modify broiler lipid metabolism, there was no additional treatment effect when high-fat diets were supplemented with T3. In contrast to previous reports, T3 did not increase any parameter associated with lipid metabolism.     

Conjugated linoleic acid enhanced the immune function in broiler chicks

This study was undertaken to investigate the growth performance and immune responses of broiler chicks fed diets supplemented with conjugated linoleic acid (CLA). Two hundred and forty day-old Arbor Acre male broiler chicks were randomly allotted into four dietary treatments with different inclusion levels of CLA (0, 2.5, 5.0 or 10.0 g pure CLA/kg) for 6 weeks. Growth performance, lysozyme activity, peripheral blood mononuclear cell (PBMC) proliferation, prostaglandin E2 (PGE2) synthesis and antibody production were investigated. There were no significant differences in growth performance among treatments (P>0.05). Chicks fed 10.0 g CLA/kg diet produced 40 % and 49 % more lysozyme activity in serum and spleen than the control group at 21 d of age (P<0.05). Dietary CLA enhanced the PBMC proliferation in response to concanavalin A at the age of 21 and 42 d (P<0.05). Systemic and peripheral blood lymphocytic synthesis of PGE2 in chicks fed 10.0 g CLA/kg diet was significantly decreased by 57 % and 42 % compared to chicks fed control diet (P<0.05). Antibody production to sheep red blood cell and bovine serum albumin were elevated in either 2.5 or 10.0 g CLA/kg dietary treatments (P<0.05). The results indicated dietary CLA could enhance the immune response in broiler chicks, but did not alter the growth performance.