Heterosis and combining ability for body weight in a diallel cross of three chicken genotypes

The aim of the study was to evaluate heterotic and combining ability effects for growth in nine chicken genotypes. A 3?×?3 complete diallel mating system involving two indigenous breeds named Venda (V) and Naked Neck (N) and one commercial broiler breed named Ross 308 (R) were used. The nine genetic groups of crosses were reared up from hatch to 13 weeks of age in deep litter open house. Body weights of 180 chicks (20 chicks per genetic group), recorded at 0, 3, 5, 7, 9, 11, and 13 weeks of age, were used to estimate heterosis, general combining ability (GCA), and specific combining ability (SCA). Results showed that the Ross 308 had the heaviest body weight at all weeks of measurement except for hatch. With respect to crosses, the V × R and its reciprocal cross, R × V had the heaviest body weights at 13 weeks. Heterosis estimates for body weight were higher in the Venda male × Ross 308 female and Venda male and Naked Neck female crosses. GCA was significant (P?≤?0.01) for body weight from hatch to 13 weeks of age while SCA and reciprocal effects were both significant (P?≤?0.05) for body weight at all ages of measurement except for hatch. The Ross 308 gave the highest positive effect of GCA for body weight except for hatch. V × N gave the highest and positive effects of SCA for body weight.     

Postpartum performance in a diallel cross among lines of mice selected for litter size and body weight

Postpartum dam performance was studied in a complete diallel design involving five lines of mice. The selection criterion in each line was: large litter size at birth (L+); large 6-wk body weight (W+); an index for large litter size and small 6-wk body weight (L+W-); the complementary index (L-W+) and random (K). Females from the five lines and 20 reciprocal F1 crosses were mated to sires of a randomly selected control line (CC). Correlated responses in average direct genetic and average maternal genetic effects for dam body weight and litter size at parturition persisted throughout lactation, indicating important pleiotropic effects. Major correlated responses occurred for litter weight, feed intake and litter feed efficiency, primarily due to average direct genetic effects. Using general combining ability and net line effects as criteria for choosing among lines, L+ had a distinct advantage if the objective was to increase litter size in a crossing program. If the objective was to maximize litter weaning weight, then W+ would be favored for net line effects, while L+ and W+ would be about equivalent for general combining ability. None of the lines had an advantage for litter feed efficiency. Direct heterosis for dam weight at 12 and 21 d of lactation averaged 2.7 and 1.9%, while for litter size the respective averages were 7.4 and 7.3%. The W+ X L+W- cross exhibited overdominance for litter size. Direct heterosis was moderate for feed intake and litter weight, but was negligible for litter feed efficiency because of the mathematical relationship among the three traits. Maternal heterosis for preweaning progeny growth was suppressed because of heterosis for litter size in the dam. Grand-maternal effects on growth of the young were small and would not be an important consideration in choosing among these lines in a crossbreeding program.     

Reproductive performance in a diallel cross among lines of mice selected for litter size and body weight

Genetic factors affecting female reproductive performance in lines of mice with a known history of selection were estimated from a 5 X 5 diallel cross. Lines were selected as follows: large litter size at birth (L+); large 6-wk body weight (W+); an index for large litter size and small 6-wk body weight (L+W-); the complementary index (L-W+) and randomly (K). Partitioning of direct and correlated responses for litter size, 6-wk body weight and related traits into average direct genetic (li) and average maternal genetic (mi) effects indicated that the magnitude of differences in li exceeded those in mi. Lines having positive responses in li were W+ greater than L+ greater than L-W+ for dam body weight, L+ greater than L+W- greater than W+ for litter size and L+ greater than (W+, L+W-) for litter birth weight, whereas L-W+ responded negatively for litter size. A positive association was found between mi for litter size and dam body weight, W+ and L-W+ being high and L+ and L+W- low for both traits. Female infertility and time from male exposure to parturition had relatively small correlated responses. Line rankings in general combining ability (gi) and net line effects were similar for the respective traits. Depending upon the line and trait involved, the relative contribution of average direct genetic and line direct heterotic (hi) effects to general combining ability [gi = (1/2) li + hi] varied. Line heterosis refers to average heterosis in crosses involving that line. Direct heterosis ( hij ) for each trait differed considerably among crosses. The three crosses showing the highest hij for litter size at birth, W+ X L-W+ (1.78), L+ X W+ (1.28) and L-W+ X L+W- (1.22), possibly had loci contributing directional dominance to litter size with frequencies of parental lines deviating in opposite directions relative to mean gene frequency. The correlation between absolute difference in parental line means and hij for litter size was not significant, suggesting that the magnitudes of absolute differences in parental means were not reliable predictors of divergence in gene frequency. Crossbred performance increased linearly with midparent values for litter size at birth (b = .88 +/- .09, R2 = .92) and dam parturition body weight (b = 1.13 +/- .04, R2 = .99), the latter trait showing an increase (P less than .01) in heterosis as midparent values increased.     

Genetic analysis of juvenile growth and carcass traits in a full diallel mating in selected colored broiler lines

The juvenile growth and carcass traits were evaluated in a 4 × 4 full diallel crossing involving four colored broiler chicken lines viz., Naked neck (NN), Dwarf, Punjab Broiler-1 (PB-1), and Punjab Broiler-2 to study the performance and crossbreeding parameters. The data on 2,280 chicks were analyzed using least squares techniques to assess the effect of genetic group, and the significant traits were further analyzed for crossbreeding parameters. Genetic group had significant influence on the body weights and carcass traits. The cross of PB-1 × NN recorded significantly (p ≤ 0.05) higher body weight at 6 weeks of age. The data revealed that general combining ability (GCA), specific combining ability (SCA), maternal ability (MA), sex-linked effect (SE), and purebred effects significantly influenced the growth and carcass traits in the broiler crosses. The crossbred PB-1 × NN showed positive heterosis for growth as well as carcass traits. The results suggest that GCA, SCA, SE, and MA are important in the inheritance of the body weights and carcass traits indicating the presence of both additive and nonadditive genetic variation along with reciprocal effects. Therefore, pure line selection along with development of specialized sire and dam lines followed by crossing will improve the growth performance and benefit the poultry farmers. It is concluded that PB-1 as a male line and NN as a female line performed significantly higher, therefore, may be used for improving the performance of colored broilers.     

网地结合饲养方式对肉仔鸡的影响

1方法 1.1鸡种及处理 选择1日龄艾维茵鸡苗1000只,随机分成两组,每组为500只,一组利用垫料地面饲养,一组为网地结合饲养.     

家蚕杂交组合配合力测定实验初报

通过对家蚕5对杂交组合的经济性状与其杂交亲本及全国指定统一对照种品种菁松×皓月、本地对照品种新蚕三号的杂交优势分析比较,结合饲育性状表现,评选出优良的杂交组合.结果表明: 871×872、338×329、夏芳×秋白3对杂交组合的产茧量、茧质和抗性等育种指标的综合成绩均优于或相当于对照种,表现出超亲的杂种优势.     

丹参提取剩余物对肉仔鸡生产性能和血清抗氧化指标的影响

试验旨在研究日粮中添加不同水平的丹参提取剩余物对肉仔鸡生产性能和血清抗氧化指标的影响。选用1日龄爱拔益加(AA)肉仔鸡320只,随机分成4个处理,每个处理8个重复,每个重复10只鸡。处理1为对照组,饲喂基础日粮;处理2、3、4为在基础日粮中分别添加0.3%、0.5%和1%丹参提取剩余物的试验组。试验第21、42日龄,空腹称重,统计耗料量,计算生产性能;翅静脉采血,测定血清总抗氧化能力(T-AOC)、超氧化物歧化酶(SOD)活性、谷胱甘肽过氧化物酶(GSH-Px)活性和丙二醛(MDA)含量。结果显示,日粮中添加0.3%、0.5%和1%丹参提取剩余物对于肉仔鸡的生产性能没有显著影响(P>0.05)。日粮中添加0.3%丹参提取剩余物对于肉仔鸡血清抗氧化指标的影响差异不显著(P>0.05);日粮中添加0.5%丹参提取剩余物对于肉仔鸡血清总抗氧化能力(T-AOC)影响差异不显著(P>0.05),可以提高超氧化物歧化酶(SOD)、谷胱甘肽过氧化物酶(GSH-Px)活性,但是差异不显著(P>0.05);日粮中添加1%丹参提取剩余物可以显著提高肉仔鸡血清总抗氧化能力(T-AOC)、超氧化物歧化酶(SOD)活性、谷胱甘肽过氧化物酶(GSH-Px)活性(P<0.05),同时可以显著降低血清丙二醛(MDA)含量(P<0.05)。由此可见,在肉仔鸡日粮中添加丹参提取剩余物可以提高肉仔鸡的抗氧化能力,其中添加比例为1%时作用效果最佳。     

Origin of Clostridium perfringens isolates determines the ability to induce necrotic enteritis in broilers

Since the ban on growth-promoting antibiotics in animal feed in the European Union, necrotic enteritis has become a major cause of mortality in broiler chickens. Despite the importance of the disease, the pathogenesis is still not completely understood. In the current study, Clostridium perfringens strains isolated from healthy flocks and isolates from outbreaks of necrotic enteritis were evaluated for the ability to cause gut necrosis in an intestinal loop model in laying hens and in an experimental infection model in broilers. High, intermediate and low alpha toxin producing strains were chosen from each isolation source. Only the isolates from field outbreaks induced necrotic gut lesions, independent of the amount of alpha toxin produced in vitro. It was also shown that alpha toxin producing isolates from calf hemorrhagic enteritis cases were not able to induce necrotic enteritis in poultry. These results suggest the presence of host specific virulence factors in C. perfringens strains, isolated from chickens with intestinal necrotic enteritis lesions.     

荞麦蜂花粉多糖对肉仔鸡免疫功能、血脂及抗氧化能力的影响

试验旨在观察日粮中添加荞麦蜂花粉多糖对肉仔鸡免疫功能、血脂及抗氧化能力的影响。将200羽1日龄AA肉仔鸡随机分为空白对照组、试验1、2、3组,每组5个重复,每个重复10羽。其中对照组饲喂基础日粮,试验1、2、3组分别在基础日粮中添加500.0、1000.0、1500.0 mg/kg的荞麦蜂花粉多糖。饲养试验期为42 d。结果表明,与对照组相比,试验1、2、3组可显著提高肉仔鸡脾脏指数、胸腺指数与血清IgG含量,能显著升高血清SOD与GSH-Px活性,降低MDA含量（P<0.05）。另外,试验2、3组还可显著提高法氏囊指数与血清IgA、IgM含量,并明显降低血清胆固醇含量（P<0.05）。但各试验组对肉仔鸡生长性能、甘油三酯含量无明显影响（P>0.05）。试验结果表明,基础日粮中添加荞麦蜂花粉多糖,可明显促进肉仔鸡免疫功能,降低血清胆固醇,并明显提高肉仔鸡抗氧化能力。提示荞麦蜂花粉多糖可能是一种较好的纯天然肉仔鸡免疫增强剂与抗氧化剂。     

Determination of optimal dietary selenium levels by full expression of selenoproteins in various tissues of broilers from 1 to 21 d of age

The current NRC dietary selenium (Se) requirement (0.15 mg/kg) of broilers is primarily based on growth performance data reported in 1986. Our study aimed to determine optimal dietary Se levels of broilers fed a practical corn-soybean meal diet for the full expression of selenoproteins in various tissues. A total of 384 one-d-old male broilers (n = 8 replicates/diet) were fed a basal corn-soybean meal diet or the basal diet supplemented with 0.1, 0.2, 0.3, 0.4 or 0.5 mg Se/kg in the form of Na₂SeO₃ for 21 d. Regression analysis was conducted to evaluate the optimal dietary Se levels using broken-line, quadratic or asymptotic models. The activity of glutathione peroxidase (GPX) in the plasma, liver, kidney and pancreas, iodothyronine deiodinase (DIO) in the plasma, liver and pancreas, and thioredoxin reductase (Txnrd) in the liver and pancreas, the mRNA levels of Gpx1, Gpx4, Dio1, selenoprotein (Seleno) h, Selenop and Selenou in the liver, Gpx4, Dio1, Txnrd1, Txnrd2, Selenoh, Selenop and Selenou in the kidney, and Gpx1, Gpx4, Selenoh and Selenou in the pancreas, and the protein levels of GPX4 in the liver and kidney of broilers were influenced (P < 0.05) by added Se levels, and increased quadratically (P < 0.05) with the increase of added Se levels. The estimates of optimal dietary Se levels were 0.07 to 0.36 mg/kg based on the fitted broken-line, quadratic or asymptotic models (P < 0.001) of the aforementioned selenoprotein expression in the plasma, liver and kidney, and 0.09 to 0.46 mg/kg based on the fitted broken-line models (P < 0.001) of the aforementioned selenoprotein expression in the pancreas. The results indicate that the optimal dietary Se levels would be 0.36 mg/kg to support the full expression of selenoproteins in the plasma, liver and kidney, and 0.46 mg/kg to support the full expression of selenoproteins in the pancreas of broilers fed a practical corn-soybean meal diet from 1 to 21 d of age.     

Determination of optimal dietary selenium levels by full expression of selenoproteins in various tissues of broilers from 22 to 42 d of age

The current NRC dietary selenium (Se) requirement (0.15 mg/kg) of broilers from 22 to 42 d of age is primarily based on a previous study reported in 1986, which might not be applicable to modern classes of rapidly growing broilers. The present experiment was conducted to determine the optimal dietary Se level for meeting metabolic and functional Se requirements of broilers fed a corn-soybean meal diet from22 to 42 d of age. A total of 336 Arbor Acres male broilers at 22 d old were randomly assig...     

Production characters of primiparous females of a five-breed diallel

Data included pubertal, reproductive and lactation records of primiparous females produced in a diallel of Angus, Brahman, Hereford, Holstein and Jersey. Brahman heifers were oldest, tallest and heaviest at puberty, while Jersey heifers were youngest, shortest and lightest. Crossbred heifers were 22 d younger (P less than .01) at puberty than straightbred heifers; no significant differences were detected between the two groups for weight or height at puberty. Dairy heifers (Holstein and Jersey) required fewer services (P less than .05) to conception than beef heifers. The difference between straightbred and crossbred heifers for number of services to conception was small and nonsignificant. Rank of straightbreds for age at conception was similar to their rank for age at puberty except that Holstein required 1.2 fewer services and were younger at conception than Jersey. Crossbreds were 41 d younger (P less than .05) at conception than straightbreds. Brahman had the longest gestation length and were oldest at first calving; Jersey had the shortest gestation length and Holstein were youngest at first calving. Straightbred heifers gestated 1.3 d longer and were 45 d older (P less than .05) at first calving than crossbred heifers. Dairy females had greater peak and total milk yield than beef females (P less than .01). Overall straightbred and crossbred means for peak milk yield and total milk yield did not differ significantly.     

中草药添加剂对肉鸡抗氧化能力和红细胞免疫功能的影响

为了解中草药添加剂对肉鸡抗氧化和红细胞免疫功能的影响,选用80只1日龄AA肉鸡,随机分为对照组(C)和试验组(T),每组40只。对照组饲喂基础日粮,试验组在基础日粮中添加1%中草药添加剂,连续饲喂20d。在试验初(0d)和试验末(20d),分别测定血清超氧化物歧化酶(SOD)、谷胱甘肽过氧化物酶(GSH-Px)活性、丙二醛(MDA)含量、红细胞C3b受体花环率(E-C3bRR)和免疫复合物花环率(E-ICRR)。结果表明:0d时两组鸡抗氧化能力和红细胞免疫功能测定值差异不显著(P>0.05);20d时试验组与对照组比较,血清SOD、GSH-Px活性和E-C3bRR分别提高8.51%、7.49%和10.23%(P<0.05);血清MDA含量和E-ICRR分别下降5.85%和7.87%(P<0.05)。     

家蚕配合力效应及杂种优势研究

本文通过对中日系各3个品种15项性状的配合力效应分析和杂种优势测定,结果表明,性状间的一般配合力和特殊配合力存在明显差异,特殊配合力和杂种优势率最优的组合,其中系品种的一般配合力是最高的,而日系品种反而是最低的,说明一个组合的好坏,不能单从原种考虑,最终应从杂交组合本身优良与否来评定。     

Characterization of relative growth of empty body and carcass components for bulls from a five-breed diallel

Slaughter and carcass data were obtained on 197 bulls produced in a diallel involving Angus, Brahman, Hereford, Holstein and Jersey that were slaughtered at either 6, 9, 12, 15, 18, 24, or 30 mo of age. Bulls were given ad libitum access to a 72% TDN diet on an individual basis from 6 mo of age until slaughter. Empty body weight (EBWT) was determined as the sum of the weights of blood, hide, hard drop, soft drop (minus contents of the digestive tract), and carcass weight (CWT), which were recorded at slaughter. Carcass protein (CPROT) and fat (CFAT) were based on weights and chemical analyses of lean and fat tissue and bone of the carcass. Empty body protein (EBPROT) and fat (EBFAT) were based on weights and chemical estimates of the components of the empty body. Growth of EBWT, EBPROT, EBFAT, CWT, CPROT, and CFAT relative to either live weight (LWT), EBWT, or CWT were investigated using the allometric equation. Breed-type differences existed (P less than .01) for the growth of EBWT relative to LWT. Comparisons of general combining abilities revealed that Angus, Hereford, and Jersey generally had lower maturing rates of EBWT relative to LWT and that Brahman and Holstein had higher maturing rates. Across breed-type, relative growth rates indicated that fat and protein were later-maturing components relative to LWT, EBWT, or CWT, which implies that other components mature relatively earlier. Relative maturing rates of components studied were not important in explaining differences in body composition that have been previously reported for these breed-types.     

Characterization of a velogenic Newcastle disease virus isolated from broilers in Saudi Arabia

A highly virulent Newcastle disease virus (SA84) was isolated from a large broiler operation in Saudi Arabia. The mean death time of chicken embryos given the minimum lethal dose, the pathogenicity of the isolate for 8-week-old chickens, the plaque characteristics, and the intracerebral pathogenicity index indicated that the isolate is of the viscerotropic velogenic pathotype.     

Influence of dietary protein and sex on walking ability and bone parameters of broilers

1. The study was conducted to investigate the effect of dietary protein on the walking ability and bone parameters of broilers reared under summer temperatures which ranged from 26 to 32C(+/-2C). 2. Three different dietary protein combinations were used. The diets (per kg) were: low protein with 205 g crude protein and 12.94 MJ ME, 184 g crude protein and 12.75 MJ ME; medium protein with 219 g crude protein and 12.99 MJ ME, 201 g crude protein and 12.87 MJ ME; and high protein with 238 g crude protein and 12.99 MJ ME, 216 g crude protein and 12.96 MJ ME from 0 to 4 and 4 to 7 weeks of age, respectively. Body weights of birds were recorded and birds' walking ability (gait scoring) were scored for each bird, according to 3 categories (completely normal to immobile, at 4 and 7 weeks). Tibia parameters and tibia plateau angles were also determined at 7 weeks. 3. Birds fed on the low protein were lighter than those fed on the medium or high protein diets. At 7 weeks, birds with poor walking ability weighed 149 g less than birds with no walking difficulty. 4. Bone parameters were not affected by dietary protein, sex or gait score. There was a significantly positive correlation between bone strength and radiographic density. Bone strength was also significantly correlated with bone weight and length.     

沙棘叶黄酮对热应激条件下肉仔鸡抗氧化能力的影响

本试验研究在热应激条件下日粮中添加不同水平的沙棘叶总黄酮(TFH)对内仔鸡抗氧化能力的影响.采用单因子试验设计,选用300只1日龄从雄性肉用仔鸡(其中240只为试验鸡,60只作为后备鸡),随机分4个处理组,每组4个重复,每个重复15只.分别饲喂在基础日粮的基础上分别添加TFH 0、250、500、1000 mg/kg的日粮,试验期4周.结果表明:(1)添加1000 mg/kg TFH能增强热应激前后血清、肝脏和腿肌内铜-锌-超氧化物歧化酶(Cu-Zn-SOD)活性(P<0.05).(2)TFH能增强热应激前后血清、胸肌和腿肌内总抗氧化能力(T-AOC)活性(P<0.05).(3)添加1000mg/kgTFH可使血清、肝脏、腿肌和胸肌中丙二醛(MDA)含量显著降低(P<0.05).因此,TFH可通过提高肉鸡组织器官的Cu-Zn-SOD和T-AOC活性,降低MDA含量来增强机体在热应激条件下的抗氧化能力,从而降低热应激对其造成的氧化损伤.     

牛磺酸对肉仔鸡生产性能、免疫器官发育及抗氧化能力的影响

选用240只1日龄AA肉仔鸡,随机分为5组,每组3个重复.对照组饲喂玉米-豆粕型基础日粮,试验组在基础日粮中添加0.05%、0.10%、0.15%和0.20%的牛磺酸,试验期42 d.结果表明:(1) 日粮中添加0.10%牛磺酸,能够显著提高肉仔鸡平均日增重和饲料转化率(P＜0.05),显著提高3周龄肉仔鸡脾脏指数和6周龄法式囊指数(P＜0.05),显著提高肉仔鸡血清和3周龄肝脏超氧化物歧化酶(SOD)活性(P＜0.05),并显著降低3周龄血清和肝脏丙二醛(MDA)含量(P＜0.05).(2)添加0.15%的牛磺酸显著提高3周龄肉仔鸡脾脏和胸腺指数(P＜0.05).(3)日粮中添加0.20%的牛磺酸对肉仔鸡生产性能、免疫器官发育和抗氧化能力没有显著影响(P＞0.05).     

Flock data reported from a poultry slaughter house (broilers)]

Six broiler flocks have been compared with regard to the occurrence of attributes according to an examination protocol. Approved birds were scrutinized per random sample, condemned birds altogether. Parameters of examination were body weight occurring attributes (computed single and cumulated) count of dead and condemned birds in fattening period, transport and on slaughter line as well. Each flock was conspicuous in one or another respect. The graduation of the flocks was possible using the factors losses in the fattening period count of condemnation losses in the total production line coefficient of variation of weights attributes occurring in the meat inspection cumulated count of all attributes leading to condemnation. Results demonstrate, that graduation of different flocks by means of quantitative measurements is possible.