Strain differences in the erythrocyte and spermatozoan head dimensions of White Leghorn cocks

Differences amongst the length, breadth and area of erythrocyte nuclei, and the length, breadth, shape and area of the heads of spermatozoa were observed in six strains of White Leghorn cocks. Erythrocyte nuclear and spermatozoan head dimensions were negatively correlated. The negative correlations were explained on the basis of cellular oxidation rate.     

Effects of restricted feeding in the growing and laying periods on the performance of White Leghorn by Australorp crossbred and White Leghorn strain cross chickens

1. The effects of restricted feeding in the rearing and laying periods on the performance of three White Leghorn cockerel by Australorp pullet crossbred strains and one White Leghorn strain cross were studied in two experiments.

2. After feeding ad libitum in the rearing period, mean body weights of the three crossbred strains at 20 weeks of age were 1.75, 1.66 and 1.55 kg and that of the White Leghorn strain cross was 140 kg. The differing restrictions during rearing reduced mean body weight at 20 weeks by 14 to 33% and increased the time to sexual maturity by 8 to 23 d.

3. All restriction regimes during rearing increased mean egg weight and tended to reduce mortality in the laying period. Optimum hen‐day egg number over 64 weeks of lay was obtained following mild restriction (14% body weight reduction) of the two heavier strains or ad libitum feeding of the lighter strains. Over 48 or 64 weeks of lay, egg number per hen housed (at 18 to 20 weeks of age) was optimised after moderately restricting (14 to 21% body weight reduction) the crossbred strains or feeding the White Leghorn strain cross ad libitum.

4. Over 64 weeks of lay, mortality was reduced from 19.3% to 10.5% in the lightest crossbred strain, in which a high proportion of deaths were associated with Marek's disease and lymphoid leucosis, by restriction during rearing.

5. Restricting food intake by 7 or 8% throughout the laying period reduced hen‐day and hen‐housed egg number and mean egg weight of all four strains. The reduction in hen‐day egg number associated with food restriction during lay was less for the heavier strains that had also been restricted during rearing.

6. Metabolisable energy intakes required to support maximum production over 64 weeks of lay were 1.23 to 1.36 MJ/d.     

环境温度对来航公鸡某些血浆成分及酶类活性的影响

本试验在人工气候室条件下研究了环境温度对鸡血浆成分及酶活性的影响。试验鸡为１６月龄健康巴布考克种公鸡，温度处理分别为７．５±１℃、１２．５±１℃、１７．５±１、２２。５±１℃、２７．５±１℃和３２．５±１℃，处理时间７天，采用１３．８８和１１．７０ＭＪ／ｋｇ两种种能量水平的饲料，每种温度处理组１０只鸡，测定的血液指标有：总蛋白、白蛋白、血糖、磷酸肌酸激酶、乳酸脱氢酶、胆固醇活性。结果表明，磷酸肌酸激酶活性在高温下明显升高；乳酸脱氢酶在高温和次温条件下明显升高；其它指标在高低温情况下均无显著变化。本试验饲料能量浓度对血浆各项指标均无影响。     

Tamoxifen advances puberty in the White Leghorn hen.

1. Tamoxifen (TAM) administration advances puberty in cockerels. In the present study the effect of TAM administration on the sexual development of White Leghorn hens was studied. 2. Two-week-old White Leghorn females were injected intramuscularly with TAM on alternate days at doses of 0.1 mg (0.1 TM), 1 mg (1TM), 5 mg (5TM) and 10 mg/kg body weight (10TM) respectively, while the controls were injected with maize oil (vehicle). The experiment was terminated at 23 weeks of age, when all the control hens laid eggs. Sample autopsies were made on chicks of 6, 14 and 23 weeks of age. 3. Body growth was not affected by any of the treatments. 4. Comb growth was accelerated by all doses of TAM, while hematocrit increased in the 1TM, 5TM and 10TM hens. 5. Egg laying advanced in the 0.1TM and 1TM birds, was delayed in 5TM hens and did not occur at all in the 10TM females. 6. TAM caused a precocious increase in plasma oestrogen and androgen, suppressed adiposity in a dose-related manner and, at low doses, advanced the development of the gonadal system. 7. At 23 weeks of age, when the gonadal system of the controls was fully active, TAM caused a dose-related depression in abdominal fat, liver, ovary, and oviduct weights, plasma total lipids and calcium concentrations and a dose-related increase in plasma oestrogen and androgen titres, and comb weight. 8. It seems that TAM increased gonadotropic activity and its androgen stimulating action, but suppressed peripheral signs of the elevated plasma oestrogen titres. Low doses of TAM enhanced gonadotropic activity and egg laying but the antioestrogenic effect depressed development of the gonadal system, suppressing egg production when high doses were administered. It therefore seems that oestrogens are necessary for normal ovarian development in hens.     

Comparison of serum biochemical profiles of male broilers with female broilers and White Leghorn chickens.

Male broiler chickens were compared to female broiler chickens and male White Leghorns with respect to a 15-parameter serum biochemical profile at 9, 20, 30 and 42 days of age in order to determine which, if any, of the parameters tested might be useful in the identification of birds susceptible to sudden death syndrome. In comparison to female broilers, male broilers had significantly lower (p less than 0.01) total protein levels at 20 days of age and significantly higher (p less than 0.01) cholesterol levels at 30 days of age. Compared to male White Leghorns, in which sudden death syndrome has not been reported, male broilers had significantly lower (p less than 0.01) levels of cholesterol and creatinine at nine days of age, total protein at 9 and 20 days of age and albumin at 20 days of age and significantly higher (p less than 0.01) levels of potassium at nine days, uric acid at 9, 20 and 30 days, lactate dehydrogenase at 20, 30 and 42 days and cholesterol at 30 days of age.     

Complete nucleotide sequence of mitochondrial DNA in White Leghorn and White Plymouth Rock chickens

Among the chicken breeds, White Leghorn (WL) and White Plymouth Rock (WR) are major breeds and have different history in their establishments. Whole mitochondrial DNA of the breeds were sequenced in order to elucidate the genetic relationship between the breeds. The lengths of the two WL and two WR mitochondrial DNA were found to be 16 788 and 16 785 base pairs, respectively. When the DNA sequences were compared, the similarity was found to be 99.96% (six nucleotide differences). In addition, the present study conformed the existence of an extra nucleotide ‘C’ in NADH dehydrogenase subunit 3 (ND3) of the chicken mitochondrial DNA, which has been consistently observed in Galliformes.     

Catecholamines in ovarian follicles during the ovulatory cycle of White Leghorn hens

Dopamine (DA) concentrations in the largest ovarian follicle (F1) showed significant decrease at 12 and 8 h prior to ovulation. Nor-epinephrine (NE) and epinephrine (E) concentrations in the F1, sampled at different times of the ovulatory cycle, were found to increase with the approach of ovulation time. However, the concentration of epinephrine in the F1 was low just after oviposition compared with the immediate two previous stages investigated. The concentrations of DA, NE and E in the second largest follicles (F2) did not vary significantly during the ovulatory cycle. Average concentration of DA was low and that of NE and E high in the F1 compared with the respective concentrations in the F2.     

白来航鸡慢羽品系遗传分析

对白来航鸡慢羽品系第９世代的１２个数量性状进行了遗传参数的遗传力、表型相关、遗传相关、环境相关估测与分析,证明该系遗传性能趋于稳定,成为培育高产自别雌雄配套系中一个重要品系。     

Nucleic acids in the spermatozoa of pure and strain crosses of White Leghorn cockerels

Nucleic acids (DNA and RNA) were estimated in the spermatozoa of three pure strains (M, N and P) and three strain crosses (N X P, M X N and P X M) of White Leghorn cockerels. The average DNA content was 2.31 +/- 0.06 X 10(-9)mg/sperm. Most was found in the P X M strain cross and least in the P strain. The DNA content of the P strain was significantly lower than that in the other strains and it also had the lowest fertility and hatchability of all the strains. The average RNA content in poultry spermatozoa was 0.0522 +/- 0.0038 X 10(-9)mg/sperm. Again, most RNA was found in the P X M strain cross and least in the P strain. The P X M strain cross had a significantly higher RNA content than the rest of the strains. Thus, the P X M strain contained the most DNA and RNA whereas the P strain had least.     

中国北京油鸡和引进白来航蛋鸡免疫性状的比较

选取同期孵化出雏的中国地方鸡种北京油鸡(Beijng-You Chicken,BYC)和引进蛋鸡品种白来航鸡(White Leghorn,WL)各250只母雏,在相同饲养条件和免疫程序下饲养,测定和对比异嗜性粒细胞(Heterophil)数量、淋巴细胞(Lymphocyte)数量和异嗜性粒细胞/淋巴细胞比率(Heterophil/Lymphocyte,H/L)、白细胞总数(Blood white cell count,BWCC)、绵羊红细胞(Sheep blood red cell,SRBC)免疫抗体滴度和不同日龄的禽流感(Avian Influenze,AI)、新城疫(Newcastle disease,ND)的免疫抗体滴度等免疫性状的差异.试验结果表明①北京油鸡的H/L值为0.36±0.21,白来航蛋鸡为0.52±0.51,二者呈极显著差异(P＜0.001);北京油鸡的白细胞总数明显高于白来航蛋鸡(P＜0.001);②SRBC抗体滴度在两品种之间差异不显著(P＞0.05);③14、28日龄两次免疫禽流感疫苗(H5N1毒株)后,在免疫后21、41、71、105天的4个测定日中,两个品种的禽流感免疫抗体滴度值均呈现先升高后降低的变化趋势,北京油鸡在4个测定日龄的AI免疫滴度值都均高于白来航蛋鸡,差异均达到极显著水平(P＜0.001);④同期免疫新城疫疫苗(LaSota毒株),在免疫后21、41、71和105天测定ND抗体滴度,北京油鸡在免疫后21天时达到最高,之后随日龄的增长而呈逐渐降低趋势;白来航蛋鸡在免疫后41天时抗体滴度水平达到最高,以后随日龄增长而下降.4个测定日龄的ND滴度水平北京油鸡均高于白来航蛋鸡.该研究结果初步显示,中国地方鸡种北京油鸡和引进白来航蛋鸡品种的免疫性状具有明显的遗传差异,北京油鸡的综合免疫性能和抗应激能力优于白来航蛋鸡.     

Effect of hypothalamic electrolytic lesions in White Leghorn and broiler male cockerels

1. This study compared the effect of bilateral electrolytic lesions of the basomedial hypothalamus (HL) in broiler and White Leghorn (WL) males. 2. Hypothalamic lesions were placed in WL at 10 weeks of age (body weight 1.1 kg) and in broilers, either at 6 weeks (body weight 1.5kg) or at 10 weeks of age (body weight 3.4kg). They were fed ad libitum until autopsy at 16 and 17 weeks of age for broilers and WL, respectively. 3. Hypothalamic lesions caused obesity (high percentage weight of abdominal adipose tissue) in both strains. Obese fowls with unimpaired reproductive systems were classified as OB and those with functional castration as FC (functionally castrated) or FCLC (functionally castrated with large comb). 4. All post-HL syndromes-OB, FC and FCLC-were present in WL, whereas all obese broilers (which are immature at this age) were classified as OB. 5. The percentage weight of abdominal adipose tissue in OB broilers was lower than in OB WL (3% vs 5%, respectively). 6. Daily food intake of OB broilers was higher than control at 12 to 15 weeks of age, regardless of time of placement of HL, whereas daily food intake of OB WL was significantly higher than that of control WL only during the first 2 weeks following HL. 7. Body weight of OB broilers at autopsy was 20% higher than control broilers, whereas body weight of OB WL was not significantly affected. 8. An additional group of broilers was reared to sexual maturity under food restriction until 28 weeks of age. HL were placed at 10 weeks of age (body weight 1.7 kg). Autopsy was performed after a 4-week period of ad libitum feeding. 9. There were OB as well as FC and FCLC among the HL, food-restricted broilers. Percentage weight of testes and spleen were reduced in OB fowls of both strains, but more so in OB WL. 10. Hyperphagia and weight gain were not observed during the ad libitum feeding period of those obese broilers after HL, indicating that hyperphagia and weight gain are secondary to obesity.     

Crossbreeding parameters of general immune response traits in White Leghorn chickens

Crossbreeding parameters of immune response traits were estimated from a set of well characterized crossbred populations derived from three chicken lines selected over 12 generations for three different general immune response traits and their F1, F2 and backcrosses. The three traits investigated were the selection criteria from each of the lines, i.e. antibody response to the Newcastle disease virus vaccine 3 weeks after vaccination (ND3), cell-mediated immune response (response to phytohemagglutinin, PHA) and phagocytic activity measured as carbon clearance (CC). Crossbreeding parameters included direct and maternal additive line effects, direct and maternal heterosis as well as direct epistatic recombination loss. They were estimated as linear combinations of genetic group effects estimated using animal model methodology. Significant line differences were obtained for ND3 and, to a lesser extent, CC. They were mainly due to direct effects, maternal effects being significant for none of the 3 traits. Significantly negative direct heterosis effects were also observed for ND3 and CC, but not for PHA. Maternal heterosis effects were not estimated for CC. They were non significant for PHA, and negative and significant (− 0.78 ± 0.24) for ND3. The significant favourable recombination gain estimated for ND3 (3.21 ± 0.88) indicates that epistatic interactions could be important for this trait.The present work shows that it was worthwhile to complete second generation crosses to be able to assess to what extent immunity gained by selection is maintained in advanced crossbred generations, and to compare the transmission of immune traits implicated in different aspects of immunity.     

Genetic and phenotypic parameters for monthly egg production in White Leghorn hens

This article reports genetic and phenotypic parameters of monthly egg production and the influence of Box‐Cox transformation on the parameters from a population of White Leghorns, selected for feed efficiency. A total of 6450 daughters of 180 sires and 1335 dams were analysed by restricted maximum likelihood (REML) using a multivariate animal model. The traits considered were monthly egg productions, cumulative production of the first 5 months (S5), cumulative production of first 10 months (S10), and survivor egg production in the first cycle (S12). Two sets of data were analysed: the original data and with the Box‐Cox method transformed data. The results indicated that there were no great differences in the estimates between untransformed and transformed data. The estimates of heritability for monthly egg production were high for the first period, decreased to reach the lowest during peak production, and increased to the end of lay. The estimates of heritability for cumulative records were generally higher than monthly records. Genetic and phenotypic correlations among monthly egg production totals were generally high for contiguous periods and then decreased as the interval between months increased. The highest genetic correlation between monthly records and S5 was for the second month of production, whereas the correlations between monthly production totals and S10 and S12 reached their peak at the sixth and eighth months of production, respectively.     

Genetic adaptation of White Leghorn hens to life in single cages

Specific adaptations of selected lines to their conditions of management were found for egg production, but not for several other traits, when hens of different selection histories were tested under both conditions. Floor selected sublines were superior to cage selected sublines in floor pens but inferior when both were tested in individual cages. The study involved three populations of two sublines in each of which selection for egg production had been practised over seven generations. Under one management birds from the three populations were intermingled in large floor pens; under the other, among individual cages.

The role of social dominance as expressed in competition for food was explored. Floor selected hens were the more dominant in floor pens as well as in paired tests in cages.     

Response of White Leghorn and Nigerian cockerels to experimental salmonella infection

Summary Twenty-two Nigerian cockerels and 19 White Leghorn cockerels were each injected intramuscularly with 1·5×10⁹ viable organisms of a relatively avirulent strain ofSalmonella gallinarum (NCTC 10532). The Nigerian cockerels were more resistant to infection as judged by the values of the haemoglobin, haematocrit, red cell count, leucocyte count and antibody titre during the course of infection. The authors suggest that the higher resistance may be due to the earlier growth and higher organ weight of the bursa of Fabricius of the Nigerian breed than of the White Leghorn (Aire,1973).

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Sumario Ventidos pollos Nigerianos y diecinueve White Leghorn fueron inoculados individualmente vía intramuscular, con 1·5 × 10⁹ de una suspensión relativamente avirulenta de una cepa deSalmonella gallinarum (NCTC 10532). Los pollos Nigerianos fueron más resistentes a la infección, teniendo en cuenta los valores de hemaglobina, hematocrito, número de globulos rojos, leucocitos y título de anticuerpos durante el curso de la infección. Los autores sugieren, que la mayor resistencia de la raza Nigeriana, podría estar relacionada con el peso y desarrollo mástemprano de la bolsa de Fabricius.

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Résumé Trente deux coquelets Nigériens et dix neuf coquelets Leghorn blancs ont été infectés, chacun par une injection intramusculaire de 1·5 × 10⁹ germes vivants d'une souche relativement avirulente deSalmonella gallinarum (NCTC 10532). L'examen, tout au long de l'expérience, de l'hémoglobine, des hématocrites, la numération des hématies et des leucocytes et le titrage des anticorps ont montré que les coquelets Nigériens étaient plus résistants. Les auteurs suggèrent que cette résistance supérieure peut être due au développement plus précoce et au poids supérieur de la bourse Fabricius chez le coquelet Nigérien par rapport au coquelet Leghorn blanc (Aire, 1973).