Effect of dietary concentrations of fat and energy on fat deposition in broilers divergently selected for high or low abdominal adipose tissue

1. Fat deposition in abdominal, mesenterial, sartorial and gizzard adipose tissues (AT), liver, breast muscle, skin and carcase was studied in male broilers, selected for high (HF) and low (LF) abdominal fat and fed on diets differing in energy density and total fat content. 2. There were no significant differences in body weight in the experimental groups. The relative weight (g/kg body weight) of the dissected adipose tissues was higher in HF than in LF birds. Fat concentration in the AT (sartorial excepted), skin and body was higher in the HF compared with the LF birds. The lines did not differ significantly in liver and breast muscle fat content. 3. Abdominal AT was affected by selection or dietary fat more than other AT and total body fat. 4. In the HF birds increasing energy density from 12.3 to 13.4 MJ/kg (dietary fat kept constant: 5.46 g/MJ) significantly increased the weight of the abdominal, mesenterial and sartorial AT. Increasing dietary fat (at both energy densities) decreased the weight of the AT, whereas increasing both energy and fat did not affect it. In the LF birds, similar but milder and insignificant trends were observed. It is suggested that this interaction has biological significance.     

Selecting broilers for low or high abdominal fat: Initial observations

1. Two lines of broiler breeders were selected for three generations using a high (fatty line) or a low (lean line) ratio of abdominal fat to live weight as criterion in males at 9 weeks of age.

2. The heritability of this character remained high in both lines.

3. By the third generation, the progress achieved was much more marked in males than in females. The difference between the females of both lines was nevertheless significant.

4. The differences between the two lines were already discernible at 4 weeks of age.

5. Selecting for low or high abdominal fat content was accompanied by a better food conversion ratio in males of the lean line.

6. Selecting for the amount of abdominal fat produced similar effects on the other fatty deposits.     

Selecting broilers for low or high abdominal fat: Distribution of carcass fat and quality of meat

1. Carcass fat distribution and meat quality were studied in 52‐d‐old cockerels of the 4th generation of selection for low ('lean') or high ('fat') abdominal fat content.

2. Compared with lean birds, there was four times more abdominal fat, 2.8 times more subcutaneous fat and 1.5 times more fat deposited between the leg muscles in fat birds. Chemical estimation of the fat content of thigh muscle, however, revealed no difference between these two lines.

3. No clear differences were observed for cooking losses, flavour and juiciness, while tenderness appeared to be a little higher in fat birds.

4. These results suggest that breeding for a low abdominal fat depot is advantageous in terms of carcass quality.     

Functional microRNA screening for dietary vitamin E regulation of abdominal fat deposition in broilers

ABSTRACT

1. Functional microRNA (miRNA) screening for abdominal fat tissue with different dietary vitamin E (VE) levels was performed to reveal miRNAs, genes and metabolic pathways involved in abdominal fat deposition in broilers.

2. A total of 240, one-day-old healthy female chicks were randomly allocated into five dietary treatments containing either 0, 20, 50, 75 or 100 IU DL-α-tocopherol acetate. The sequencing of miRNAs from abdominal fat tissues was performed. The target genes of miRNAs were predicted and enrichment analysis for these genes was performed. Diets supplemented with 50 IU VE significantly diminished abdominal fat deposition in broilers at day 35 of age.

3. A total of 29 miRNAs were differentially expressed between control and 50 IU VE treatment. Ten of the 23 target genes were enriched in four signalling pathways: tight junction, SNARE interactions in vesicular transport, regulation of autophagy and proteasome.

4. This study identified miRNA, target genes and pathways in dietary VE treatment for broilers, providing new insights into the miRNA regulation of abdominal fat deposition in broilers.     

Effect of dietary enzymes on the ileal digestibility and abdominal fat content in broilers

The effects of purified cellulase and a commercial feed enzyme (FE) containing cellulase, hemicellulase, pectinase and so on, on the performance, abdominal fat content, digestibility of ileal contents and metabolizable energy of broilers were examined. Male broiler chicks (Cobb strain) were divided into three groups: control, cellulase (1 U/g feed) and FE (0.6 mg/g feed) with seven replicates. Chicks were raised under a temperature condition of 25°C in wire bottom cages for 12 days from 15 days of age. Feed (corn–soybean meal diet: crude protein, 21%; metabolizable energy, 3000 kcal/kg) and water were offered ad libitum. Dietary cellulase had a negative effect on the bodyweight gain and feed conversion ratio. The FE had no effect on bodyweight gain, but tended to improve the feed conversion ratio. The ileal crude protein and ash digestibilities were improved by the FE, but not by the cellulase. Furthermore, cellulase decreased the abdominal fat content and the FE increased metabolizable energy. In conclusion, digestion is enhanced and an improvement in performance is brought about by FE and, interestingly, fat metabolism is affected by cellulase by an unknown mechanism.     

Effect of dietary fat and cholesterol level on growing pigs selected for three generations for high or low serum cholesterol at age 56 days.

Thirty-six female pigs selected for three generations for high (HS, n = 18) and low (LS, n = 18) serum cholesterol at 56 d of age were used to test the hypothesis that the two populations would respond differently to a high-fat, high-cholesterol diet (HD) and a low-fat, low-cholesterol diet (LD). The animals were four-way crosses (Chester White x Landrace x Large White x Yorkshire). All pigs were fed a standard corn-soybean meal starter diet from weaning (at 4 wk) to 8 wk of age and a grower diet from 8 to 12 wk of age. Initial serum total cholesterol concentration at 12 wk of age was higher (P less than .05) in HS than in LS pigs (94.6 vs 76.9 mg/dL, respectively). The effect of genetic background persisted throughout the 13-wk experiment (25 wk of age); there was no interaction between diet and genetic background in serum total cholesterol (final concentrations were 114.3 mg/dL in HS-HD; 107.0 mg/dL in HS-LD; 105.9 mg/dL in LS-HD; and 89.7 mg/dL LS-LD). Trends over time revealed significant effects of diet (P less than .01) and genetic background (P less than .01) on serum total cholesterol. There was no effect of genetic background on high-density lipoprotein-cholesterol concentration; high-density lipoprotein-cholesterol as a percentage of serum total cholesterol was similar for all groups: 43% for HS-HD, 48% for HS-LD, 42% for LS-HD, and 45% for LS-LD.(ABSTRACT TRUNCATED AT 250 WORDS)     

Growth and adipose tissue metabolism in young pigs fed cimaterol with adequate or low dietary protein

The beta-adrenergic agonist, cimaterol, was fed to young growing pigs to determine whether the carcass compositional changes observed in finishing pigs fed a beta-adrenergic agonist would be manifest in young animals. Furthermore, because cimaterol increased the deposition of lean mass in finishing pigs, it could have a protein sparing effect in young pigs that are rapidly accreting muscle mass and have a high dietary protein requirement. Pigs were fed cimaterol (at 0, .25 and .50 mg X kg-1 diet) and either an adequate (18%) or restricted (14%) protein diet from about 10 to 60 kg body weight. Pigs that were fed the 14 compared with 18% protein diet grew slower and ate less but had the same gain-to-feed ratio. These pigs also had shorter carcasses, less lean muscle and more fat deposition (assessed by carcass measurements and carcass chemical composition) than pigs that received adequate protein. Plasma protein and albumin concentrations were greater and plasma cholesterol, triglyceride and fatty acid concentrations were lower in pigs fed high compared with low dietary protein. Dietary cimaterol had no effect on any of the growth or carcass variables or on adipose tissue metabolism. When fed the high protein diet, cimaterol-supplemented pigs had smaller livers and stomachs. Dietary cimaterol did not have any major detectable effects on these young pigs, nor was there any evidence for a protein sparing effect.     

Effect of L-carnitine supplementation on utilisation of energy and protein in broiler chicken fed different dietary fat levels.

Effects of a supplementation of 80 mg L-carnitine per kg diet were studied in broiler chicken at two dietary levels of fat (4 and 8%) and different feeding levels (ad libitum in a growth trial, 95 and 85% of ad libitum in a balance trial). A low-carnitine basal diet adequate in amino acid concentration was used. In the growth trial, each diet was fed to 9 groups of 10 birds each for 16 days from day 5 of live onwards. Growth and feed intake were determined. At the end of the trial, birds were killed and homogenised for subsequent empty body analysis. Accretion of protein and energy was determined using a representative blank group killed at the beginning of the trial. In the balance trial, 8 individual birds were used per treatment. Birds were offered the feed at approximately 85 and 95% of ad libitum intake, which was determined with separate birds for both fat levels. Excreta were quantitatively collected three times daily for 8 consecutive days beginning on day 17 individually for each bird. Supplemented L-carnitine did not significantly affect any response criterion. However, growth and feed conversion tended to be improved by about 5% in the carnitine supplemented diets when fed ad libitum. An interaction between carnitine and fat level occurred with regard to feed conversion, indicating that carnitine had a positive effect at the high fat level, but not at the low fat level. L-carnitine did not positively affect the metabolisability of energy (ME/GE) and the efficiency of energy utilisation (RE/GE or RE/ME). Similarly, no significant carnitine effect was determined with regard to N accretion and the efficiency of utilisation of dietary protein in both trials. It is concluded that endogenous carnitine synthesis is not the limiting factor for energy utilisation in broiler chicken, even at high dietary fat concentration. Occasionally reported positive effects of supplemental carnitine were likewise caused by reasons other than improved energy or protein utilisation. Further studies on amino acid utilisation and catabolism should consider marginal amino acid supply.     

半胱胺对肉仔鸡脂肪合成代谢的影响

21日龄艾维茵商品代肉仔鸡96只,随机分成2组,分别为基础日粮组和添加半胱胺(cysm ine,CS)组。研究CS对肉仔鸡血浆中胰岛素、肝脏中苹果酸脱氢酶(MDH)水平的影响。结果表明:在42日龄以前,CS使体内胰岛素和MDH水平高于对照组;在42日龄以后,使体内胰岛素和MDH水平低于对照组。     

Influence of low levels of dietary aflatoxins on Eimeria tenella infections in broilers

The present study was conducted to evaluate the adverse effects of an interaction between low levels of dietary aflatoxins (AF) and Eimeria tenella infection on broiler chicks. A set of 1-day-old chicks were raised for 35 days in the following groups: a control group, a group fed AF, a group fed AF and inoculated with E. tenella (AF + E.ten), and a group inoculated with E. tenella alone. AF in the contaminated diet were given at 200 ppb starting from the seventh day after hatching while E. tenella was inoculated at a dose of 5 × 10⁴ sporulated oocysts per chick at the 14th day after hatching. Worsened performance traits and high mortality were all observed in the treated birds, particularly the AF + E.ten group. Lesion scores and oocyst outputs were not different within groups. Chickens fed with AF had significantly increased serum ALT and ALP activities as well as decreased albumin content. They also showed hepatomegaly, hepatocytic vacuolation and necrosis, an atrophied bursa of Fabricius, and a thymus with tissue depletion. E. tenella-infected broilers displayed a significant reduction in packed cell volume, hemoglobin content and lymphocyte percentage, and showed hemorrhagic typhlitis. The deficits in hepatic function and hematologic parameters as well as the gross pathological, and histopathological changes, were more common and more severe in the group that was exposed to both aflatoxicosis and coccidiosis than in the groups exposed to either treatment alone. Thus, the combination of aflatoxicosis and E. tenella infection may influence the course of coccidial infection due to additive effects.     

高钼对艾维因肉鸡血清免疫球蛋白的影响

300只1日龄艾维因肉鸡健雏随机分为4组,分别饲以对照日粮(Mo 13mg/kg)和高钼日粮(Mo 500mg/kg,高钼Ⅰ组;Mo 1 000mg/kg,高钼Ⅱ组;Mo 1 500mg/kg,高钼Ⅲ组)6周。病理形态学观察,高钼Ⅱ、Ⅲ组雏鸡法氏囊与对照组比较淋巴细胞减少,网状细胞增生。免疫比浊法测定,高钼Ⅰ、Ⅱ、Ⅲ组血清IgG和IgM含量显著低于对照组(P<0.05或P<0.01),IgA含量与对照组差异不显著(P>0.05)。结果显示,日粮钼水平为1 000mg/kg及其以上时,雏鸡法氏囊结构受损,日粮钼水平为500mg/kg及其以上时血清IgG和IgM含量降低,雏鸡体液免疫功能受损。     

不同铬源在高添加水平下对肉仔鸡生长性能和组织铬含量的影响

在1～21日龄AA肉仔鸡日粮中添加高水平(8mg/kg)的5种铬源组成试验组日粮,对照组日粮不添加铬,进行饲养试验,研究铬在高添加水平下,不同的铬源对肉仔鸡生长性能的影响。结果表明:①CrY对21日龄肉仔鸡的日增重、日采食量和料重比没有不良影响(P>0.05),但CrPic、CrNic、CrMet和CrCl3分别使肉仔鸡的日增重下降8.06%、16.46%、9.06%、41.36%(P<0.05);CrMet使肉仔鸡日采食量增加11.33%(P<0.05),而CrCl3使肉仔鸡日采食量降低17.04%;CrPic、CrNic、CrMet和CrCl3使肉仔鸡的料重比升高12.7%、20%、22%、41.33%(P<0.05)。可见,CrMet和CrCl3对肉仔鸡生长性能影响最大,其次为CrNic和CrPic。②以CrCl3为铬源,8mg/kg能显著增加21日龄肉仔鸡的腹脂率63.01%(P<0.05),其它4种铬源对21日龄肉仔鸡的腹脂率没有显著影响(P>0.05),表明高添加水平条件下有机铬对肉仔鸡腹脂蓄积的影响比无机铬小。③在高添加水平下,铬源对0～21日龄肉仔鸡的肝脏铬含量、肾脏铬含量、胫骨铬含量有不同程度的影响。     

日粮蛋白质水平对肉仔鸡生产性能和免疫机能的影响

用5种蛋白质水平(0￣3周分别为19.44%、20.69%、21.56%、22.43%、23.26%;3～6周对应的为17.62%、18.78%、19.56%、20.34%、21.52%),研究了日粮蛋白质水平对肉仔鸡生产性能和免疫功能的影响。结果表明:日粮蛋白质水平对肉仔鸡增重和免疫功能均有显著影响,蛋白质不足或过量都将使肉鸡生产性能和免疫力下降,蛋白质不足比过量对肉鸡生长和免疫的更为不利。使肉鸡获得最大生产性能和最佳免疫力的蛋白质水平并不一致。本试验中,3周龄前获得最佳生产性能的蛋白质水平为22.43%,获得最佳免疫力的蛋白质水平为20.56%￣21.56%;3￣6周龄时二者基本一致为19.96%。     

Pulsatility of plasma growth hormone and hepatic growth hormone receptor characteristics of broiler chickens divergently selected for abdominal fat content

1. Plasma growth hormone (GH) pulsatility and hepatic GH receptor characteristics were compared in experimental lines of meat‐type chickens selected for high (HF) or low (LF) abdominal fat content.

2. Mean GH concentration, baseline and amplitude of pulses were slightly, but not significantly, greater in LF chickens. Length and frequency of pulses were similar.

3. LF chickens exhibited higher plasma triiodothyronine (T3) concentrations. This difference between genotypes disappeared when the diet was supplemented with 1 mg/kg T3.

4. Specific binding of GH to liver membranes was higher for the fat line but was depressed by T3 supplementation to the same level in both lines. No difference was observed between lines for affinity constants.

5. It is concluded that direct selection for leanness has a less pronounced, if any, effect on GH pulsatility as compared with selection for food conversion efficiency; therefore, different physiological mechanisms are triggered to achieve leanness.     

大豆黄酮对肉仔鸡体内脂肪合成代谢的影响

大豆黄酮(Daidzein,Da)是异黄酮类植物雌激素的一种,具有强心、降血脂、对抗雌激素依赖性肿瘤生长的作用,还具有抗溶血、抗氧化等作用。Da能改变血中GH和IGF-1等激素的水平,促进动物生长,并使胎儿生长加速,促进大鼠和猪的体液免疫和细胞免疫功能。虽然对Da的研究取得了一定的进     

Effects of dietary vitamin K levels on bone quality in broilers.

This study was conducted to evaluate the effects of dietary vitamin K (menadione) on bone quality in cage-raised broilers. Three hundred and sixty male broilers were randomly allotted to one of six treatments, with six replicate pens per treatment and 10 chicks per pen. Broilers were fed one of six diets including a control diet or the control diet plus graded levels of vitamin K (0.5 mg/kg, 2 mg/kg, 8 mg/kg, 32 mg/kg and 128 mg/kg). Water and feed were provided ad libitum during the 7-week experimental period. Results indicated that vitamin K supplementation of broilers diets significantly effected bone quality and feed efficiency. The treatment containing vitamin K at 8 mg/kg improved growth performance (during weeks 6-7) and bone quality (during weeks 0-3). In our study, hydroxyapatite binding capacity of serum osteocalcin (during weeks 0-3), bone breaking strength, bone flexibility, bone ash weight increased linearly (P < 0.05) and bone mineral density, bone mineral content increased quadratically (P < 0.05) with increasing supplementation of vitamin K. In conclusion, to gain optimum bone quality and broiler performance, our studies suggest that the concentration of vitamin K in broilers diets should be 8 mg/kg, 2 mg/kg, and 2 mg/kg, for the starter, grower and finisher phases, respectively. Furthermore, it was shown that the starter period is an important phase for improving bone quality. In addition, this study validated the mechanism of vitamin K effects on bone quality. Vitamin K boosts the carboxylation of osteocalcin and decreases the concentration of serum under-carboxylated osteocalcin enhancing hydroxyapatite binding capacity of serum osteocalcin and improving bone quality.     

Protein and energy metabolism in two lines of chickens selected for growth on high or low protein diets

1. Genetic adaptation was investigated in broilers selected for seven generations on a normal (A) or a low (B) protein diet.

2. Protein and energy metabolism were studied in males from these selected lines fed on a diet of intermediate protein content.

3. All selected birds retained more nitrogen than those studied 10 years previously.

4. There was no difference in nitrogen retention between groups, although relative growth rate of group B birds was higher.

5. Heat productions relative to gross energy intake were 0.38 (group B) and 045 (group A). Energy retentions relative to gross energy intake were 0.39 (group B) and 0.35 (group A); the difference being primarily due to higher fat retention in group B.

6. Using a common maintenance requirement for metabolisable energy, group B utilised metabolisable energy for growth (0.78) better than did group A (0.71).

7. At 53 d of age plasma glucose (10%) and insulin (50%) were higher in group B than in group A.     

不同来源的脂肪对肉仔猪生产性能、腹脂含量和脚胫着色的影响

本试验目的旨在探讨大豆油、猪油、鱼油3种不同脂肪对艾维茵肉仔鸡生产性能、腹脂含量和脚胫着色的影响。试验选用606只1日龄的艾维茵肉仔鸡，随机分为3组，每组两个重复，每个重复101只，于0日龄－14日龄、15日龄－28日龄、29日龄－42日龄3阶段分别饲喂同一水平的大豆油、猪油和鱼油，3阶段的添加量分别为1．0％、2．0％、2．4％。试验结果表明，全期比较，豆油组具有最高的日增重和脚径色素级别；猪油组的腹脂含量最高，而鱼油组腹脂含量最低；鱼油组脚胫色素级别最差；3组间的饲料增重比均差异不显著。