Monthly model for genetic evaluation of laying hens. II. Random regression

1. We investigated the use of monthly production records for genetic evaluation of laying hens, derived from a test day model with random regression in dairy cattle and compared it with other models. 2. Records of 6450 hens, daughters of 180 sires and 1335 dams, were analysed using a model with restricted maximum likelihood (REML): traits considered were monthly and cumulative egg production. Five models were studied: (1) random regression with covariates derived from the regression of Ali and Schaeffer (Canadian Journal of Animal Science, 67: 637-644, 1987) (RRMAS), (2) random regression with covariates derived from quartic polynomial (RRMP4), (3) fixed regression with covariates derived from Ali and Schaeffer (FRM), (4) multiple trait (MTM) and (5) cumulative (CM). 3. The models were compared on the basis of Spearman rank correlations of individual breeding values and sire breeding values estimated from subsets of full-sib split data. The hens (about 10% per generation) which ranked highest on their estimated breeding values from different models were compared phenotypically with their full records. 4. The estimates of heritability resulting from RRMP4 were biased upward from the estimates obtained from MTM, so this model was discarded. The heritabilities for monthly productions from RRMAS and MTM showed a similar pattern. They were high for the 1st month of production, decreased to their lowest value at about month 5 of production and increased again to the end of lay. 5. Spearman rank correlations between animal breeding values estimated by monthly models (RRMAS, FRM and MTM) were high, between 0.91 and 0.98, whereas those between estimates of monthly models and CM were lower, from 0.85 to 0.87. The correlations estimated either from intermittent months of measurements (odd vs even months) or full records were generally high, from 0.93 to 0.99. Information from odd months of production could be sufficient for cost-efficient recording schemes. The RRMAS generally had the highest correlation of sire breeding values between subsets of full-sib records, followed by MTM, RM and CM. Monthly models selected hens with higher productivity than the cumulative model. 6. In conclusion, genetic evaluation based on monthly production may be better than using cumulative production and RRMAS appeared to be the best among the models tested here.     

蛋鸡产蛋期饲养技术要点

蛋鸡词养周期较长,一般可分为育雏期、育成期、产蛋期等阶段,其中产蛋期最长,也是蛋鸡养殖盈利的重要时期,现代高产蛋鸡产蛋期鸡只身体负荷大,如果词养技术跟不上会严重影响鸡只健康状况和生产性能。从现实看,蛋鸡从业者饲养管理水平参差不齐,即便是大型规模养殖场,精细化饲养也做得不到位,造成鸡只体况不佳、鸡蛋质量差、产蛋率低等问题,小、散户更为明显。本文结合生产实际,重点从词养、营养供给方面对高产蛋鸡产蛋期词养技术进行了总结归纳。     

Behaviour of laying hens in aviaries--review. Part 1: Social and resting behaviour of hens

This literature review gives information about important behaviour categories of laying hens kept in aviary systems. Based on current knowledge, the differences in behaviour of hens in aviaries compared to the behaviour of hens living under "close to natural" conditions are assessed quantitatively and qualitatively. The focus of this first review is put on resting and particularly on social behaviour. So far "optimal" group size for laying hens and consequences of oversized groups for the well-being of laying hens are unknown, thus, rendering further research necessary. Referring to the resting and social behaviour of laying hens, proposals for the design of the housing system aviary are given. A second part will deal with feeding, reproductive and dustbathing behaviour.     

Segmented polynomial model for estimation of egg production curves in laying hens

1. A model for estimating egg production curves in layers was developed and tested against other existing models. The model uses a three segment polynomial (constant—cubic—linear) and is reparameterised to estimate variables of practical importance.

2. The model predicted future production based on partial data better and estimated egg production curves as well as the currently existing models.     

Vitamin E hypervitaminosis in laying hens.

The aim of this investigation was to contribute to the problem of overdosing vitamin E. A total of 80 laying hens, divided into 5 groups, were fed diets supplemented with 0, 100, 1000, 10,000 and 20,000 mg/kg vitamin E over a period of 20 weeks within two brooding tests. Laying performance and hatching parameters were registered. All vitamin E doses did not significantly influence health and performances of hens. Vitamin E content of eggs increased from 1 to 4, 21, 46 and 51 mg per egg with vitamin E supplementation. High doses decreased oxidative stability of abdominal fat, vitamin A concentration of liver and egg yolk colour. In both tests vitamin E supplements of 10,000 and 20,000 mg/kg feed resulted in a decrease of living hatched chicken, which demonstrated an adverse effect. Further studies seem to be necessary to explain the effect.     

Development of furnished cages for laying hens

1. A 3-year trial was carried out of cages for laying hens, occupying a full laying house. The main cage designs used were 5000 cm2 in area, 50 cm high at the rear and furnished with nests and perches. F cages had a front rollaway nest at the side, lined with artificial turf. FD cages also had a dust bath containing sand over the nest. H cages had two nest hollows at the side, one in front of the other. They were compared with conventional cages 2500 cm2 in area and 38 cm high at the rear. 2. Cages were stocked with from 4 to 8 ISA Brown hens per cage, resulting in varied allowances of area, feeder and perch per bird. No birds were beak trimmed. In F and FD cages two further treatments were applied: nests and dust baths were sometimes fitted with gates to exclude birds from dust baths in the morning and from both at night; elevated food troughs, with a lip 33 cm above the cage floor, were compared with standard troughs. 3. Management of the house was generally highly successful, with temperature control achieved by ventilation. Egg production was above breeders' standards and not significantly affected by cage design. More eggs per bird were collected when there were fewer birds per cage but food consumption also then tended to be higher. 4. The number of downgraded eggs was variable, with some tendency for more in furnished cages. Eggs laid in dust baths were often downgraded. Those laid at the back of the cage were frequently dirty because of accumulation of droppings. H nests were unsuccessful, with less than 50% of eggs laid in the nest hollows. However, up to 93% of eggs were laid in front rollaways, and few of these were downgraded. 5. Feather and foot damage were generally less in furnished than in conventional cages, greater where there were more birds per cage. With an elevated food trough there was less feather damage but more overgrowth of claws. In year 2, mortality was greater in cages with more birds. 6. Pre-laying behaviour was mostly settled in front rollaway nests. Dust baths were used more for pecking and scratching than for dust bathing. Comfort behaviour was more frequent in furnished cages than conventional, although still not frequent. Locomotion was strongly affected by number of birds per cage or by space per bird, being reduced by crowding. Most birds perched at night except in one treatment providing only 10.7 cm perch per bird. 7. Behaviour was more unrestricted and varied, and physical condition was better, in furnished than in conventional cages. However, egg production will cost more in furnished cages, partly because more eggs are downgraded. Dust baths must be fitted with gates that the birds cannot open from outside, but gates for nest boxes were found unnecessary. If a low perch is fitted it must be far enough from the back of the cage for birds to walk there. 8. Where there was less space per bird (more birds per cage) than the requirements in the 1999 European Commission Directive on laying hens, there were: fewer eggs per hen, but still above the breeders' target; lower food consumption; more feather and foot damage, but less than in conventional cages; higher mortality in one trial out of three; less freedom of movement. However, the results were still very good even with 8 birds per cage, and support the principle that furnished cages provide an acceptable way of protecting the welfare of laying hens.     

Climatic adaptation of laying hens

Summary Three hundred Warren Isabrown female day old chicks were raised for 18 weeks in 3 distinct artificial climates described as temperate (20°C, 60% RH), hot dry (32°C, 40% RH) and hot humid (32°C, 90% RH). At 18 weeks each group was divided into 3 and re-allocated to 3 similar air-conditioned laying rooms as during the growing period. Different diets were fed to the 3 groups up to 18 weeks. The energy needed in order to produce the same average live body weight at 18 weeks was similar in all the 3 climatic chambers. The effect of treatments in the growing period was not significantly different (P>0·05) for most of the parameters subsequently measured during the laying period. The exception was the body weight gain between 18 and 38 weeks and the food and energy intakes. However, apart from the sexual maturity, all these parameters were negatively influenced (P<0·05) by the effect of hot climates during the laying period irrespective of method of rearing. The results of this study seem to indicate that ambient temperature experienced during the first 18 weeks after hatching has little effect on subsequent productivity and that rearing birds at high ambient temperature does not acclimatise them to these conditions better than rearing them under temperate conditions.

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Adaptacion Climatica De Gallinas Ponedoras

Resumen Se leavantaron 300 pollitas de un día de nacidas, Warren Isabrown, por 18 semanas en 3 climas diferentes; templado (20°C, 60% HR), seco caliente (32°C, 40% HR) y caliente húmedo (32°C, 90% HR). A las 18 semanas cada grupo fue dividido en 3 y re-instalado en 3 cuartos de postura con aire acondicionado durante el período de crecimiento. Los 3 grupos recibieron diferentes dietas hasta las 18 semanas. La energía necesaria para producir el mismo peso promedio a las 18 semanas fue el mismo en las tres cámaras climáticas. El efecto del tratamiento durante el período de crecimiento no fue significativamente diferente (P>0·05) para la mayoría de parámetros medidos subsecuentemente durante el peródo de postura. La excepción fue el aumento en peso corporal entre las 18 y 38 semanas y la energía consumida. Sin embargo, aparte de la madurez sexual, todos los parámetros fueron afectados negativamente (P<0·05) por el efecto de los climas cálidos durante el período de postura, irrespectivamente del manejo. Los resultados de este estudio parecen indicar, que la temperatura ambiente experimentada durante las primeras 18 semanas después del nacimiento, tuvo poco efecto sobre la productividad y que la crianza de aves a temperatura ambiente alta, no las aclimata para esas condiciones mejor que levantandolas bajo un clima templado.

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Adaptation Climatique De La Poule Pondeuse

Resumé Trois cents poussins femelles d'un jour de souche Warren Isabrown ont été élevés jusqu'à l'âge de 18 semaines dans 3 climats artificiels distincts, respectivement tempéré (20°C, 60% HR), chaud sec (32°C, 40% HR) et chaud humide (32°C, 90% HR). A l'âge de 18 semaines chaque lot d'oiseaux a été divisé en trois et réparti à nouveau en 3 cellules de ponte conditionnées de la même façon que les salles de croissance. Différentes rations alimentaires sont nourries aux oiseaux jusqu'à l'âge de 18 semaines. La consommation d'énergie nécessaire pour produire le même poids vif à 18 semaines a été sensiblement égale dans les 3 climats. L'effet des traitements en période de croissance n'a pas été significativement différent (P>0·05) sur la presque totalité des paramètres étudiés en ponte, exception faite du gain de poids vif 18–38 semaines, des ingérés alimentaires et énérgétiques. Par contre, à l'exception de la maturité sexuelle, tous ces paramètres ont à chaque fois été influencés négativement (P<0·05) par les effets des climats chauds en période de ponte, indépendamment du climat d'élevage. Les résultats de cette expérience semblent indiquer que la température expérimentée pendant les 18 premières semaines après l'éclosion a eu peu d'effet sur la productivité ultérieure, et que l'élevage des oiseaux à hautes températures ambiantes ne leur confère pas une meilleure acclimatation à ces mêmes conditions que lorsqu'ils sont élevés en milieux tempérés.

     

Space needs of laying hens

1. Videotapes of hens under various conditions were used to measure the amount of space used by hens performing common behaviour patterns.

2. When turning, hens used 540 to 1006 cm², when stretching wings 653 to 1118 cm², when wing flapping 860 to 1980 cm², when feather ruffling 676 to 1604 cm², when preening 814 to 1270 cm² and when ground scratching 540 to 1005 cm².

3. All these measurements are above the 450 cm² bird recommended as the minimum space allowance by current EC regulations, which therefore do not ensure adequate hen welfare.     

Fluoride tolerance of laying hens

1. One thousand Silver Grey Hyline hens were given drinking water containing 5 concentrations of added sodium fluoride (0, 6, 10, 14 and 20 mg/1) over a 17‐week growth and 57‐week laying period. The natural fluoride content of the water was 0–21 mg/1 during the growing period and 0–29 mg/1 throughout lay.

2. During the rearing phase, efficiency of food utilisation and mortality were not significantly affected by the fluoride concentration of the water. Weight gain and food intake decreased in the 10 and 14 mg/1 fluoride treatments.

3. During the laying period, the fluoride content of the water had a significant effect on egg production, but eggshell breaking strength was not significantly influenced.

4. Post mortem analyses, carried out at the end of lay (74 weeks of age), showed that carcase weight and the fluoride content of the os femur increased significantly as the fluoride concentration in the water increased; the increase in bone fluoride followed a linear pattern.

5. Histopathology showed no evidence of changes in the livers or kidneys; liver weights and breaking strength of the os femur were unaffected by the amount of fluoride consumed.

6. The data showed that under commercial conditions, laying birds can tolerate ingesting 4–453 mg fluoride/day for up to 74 weeks.     

The Edinburgh modified gage for laying hens

1. Behaviour, production and welfare of ISA Brown medium hybrids were assessed in 2 trials (each from 20 to 44 weeks of age) of a novel design of cage for laying hens: the Edinburgh Modified Cage (EMC).

2. The EMC was 600 mm wide, 450 mm deep and 450 mm high at the rear; it had a softwood perch and at one side a 250 mm wide nest box (containing litter or artificial turf) with a dust bath direcdy above. It housed 4 birds and provided 675 cm^2/bird in the main cage with an additional 281 cm² /bird in the nest box. The nest box and dust bath had automatically controlled doors which were closed at night. There were 18 EMC; in the first trial these were compared with 6 control cages with perch but without next box or dust bath.

3. Hens spent 32 to 37% of day time on the perch, 5 to 7% in the dust bath and 5 to 6% in the nest. At night 92 to 98% roosted on the perch.

4. Initially only 55 to 70% of eggs were laid in the nest box partly because some eggs were laid before dawn. Once the door was retimed to open 3h before lights‐on the proportion rose to 91 to 96%. Very few eggs were laid in the dust bath. Pre‐laying behaviour lasted longer in treatments with nest boxes (55 to 76min) than in control cages (48min); disturbance was slight in all treatments, but lowest in control cages.

5. Dust baths were well used, with on average 61% of hens dust bathing during a 3‐h afternoon observation period compared with only 17% in control cages. Two birds could use the dust bath simultaneously.

6. It was concluded that although a number of minor design features still required attention the EMC has potential to reduce the disadvantages of conventional cages for welfare while retaining their advantages and has possible commercial application.     

Multiplicative random regression model for heterogeneous variance adjustment in genetic evaluation for milk yield in Simmental.

A multiplicative random regression (M-RRM) test-day (TD) model was used to analyse daily milk yields from all available parities of German and Austrian Simmental dairy cattle. The method to account for heterogeneous variance (HV) was based on the multiplicative mixed model approach of Meuwissen. The variance model for the heterogeneity parameters included a fixed region x year x month x parity effect and a random herd x test-month effect with a within-herd first-order autocorrelation between test-months. Acceleration of variance model solutions after each multiplicative model cycle enabled fast convergence of adjustment factors and reduced total computing time significantly. Maximum Likelihood estimation of within-strata residual variances was enhanced by inclusion of approximated information on loss in degrees of freedom due to estimation of location parameters. This improved heterogeneity estimates for very small herds. The multiplicative model was compared with a model that assumed homogeneous variance. Re-estimated genetic variances, based on Mendelian sampling deviations, were homogeneous for the M-RRM TD model but heterogeneous for the homogeneous random regression TD model. Accounting for HV had large effect on cow ranking but moderate effect on bull ranking.     

Different soil media for free-range laying hens

1. A replicated experiment compared bird use, soil structure, grass wear and free-moving nematode populations in 4 different soil media (recycled vegetable compost, 90% recycled vegetable compost and 10% sand, re-used topsoil and sterilised topsoil) all with established grass swards within the range area of a large free-range laying hen unit. 2. The birds initially spent a greater proportion of their time on the two topsoil swards in comparison to the two compost-based swards. However, once the whole flock of hens had prolonged access to the different swards (unfenced areas) there were no significant differences in the number of birds that frequented the different sward types. 3. The two compost-based soil media had 33% fewer nematodes per g of dry soil compared to the two topsoil-based media. However, the rate of loss of grass from the subplots was greater with the two compost-based soil media; this was probably due to the greater porosity of these types of soil media.     

Analysis of the free range behaviour of laying hens and the genetic and phenotypic relationships with laying performance

1. Over twelve 28-d laying periods (almost one year), 272 laying hens of the Lohmann Silver strain, individually tagged with transponders, were monitored on their ranging behaviour and laying performance in an aviary system with an adjacent winter garden. 2. From laying periods 1 to 12, the daily frequency of passages between the barn and the winter garden of individual hens, showed an antagonistic trend compared to the average duration of single visits. While the frequency of passages decreased until the end of the recording period to 8 passages per hen and day, the average duration of single visits increased to a maximum of 32 min per hen. 3. The heritability estimates for the traits, length of stay in the winter garden and frequency of passages were higher for the last 5 laying periods than at the beginning of the recording period. For the last 5 laying periods, the estimates for the duration of stay in the winter garden varied between h(2) = 0.21 and 0.32 and for the frequency of passages, between h(2) = 0.30 and 0.49. 4. Most of the estimated heritabilities for the rate of lay were on an expected medium level (h(2) = 0.09 to 0.45). Deviant h(2)-values to a few laying periods were based on low additive genetic variances or high environmental variance. 5. Genetic correlations between both free range traits and the laying performance were negative (r(g length of stay) = -0.34 and r(g passage frequency) = -0.08). 6. Generally, there seems to be a possibility to influence the ranging behaviour through selection. Further investigations with different genotypes and varying dates of exposure to the laying environment, should be carried out to clarify possible influences on other traits and the negative correlation with laying performance.     

高峰产蛋鸡发生传染性喉气管炎的诊治

邳州市一蛋鸡专业户饲养4000只产蛋高峰期的蛋鸡于今年3月份发生了传染性喉气管炎,畜主认为是慢性呼吸道感染,用阿奇霉素进行治疗,连用4d不见效果,反而病情加重并出现死     

蛋鸡产蛋后期的营养调控

蛋鸡产蛋后期精准的营养调控可延缓蛋鸡的衰老,延长产蛋期,提高经济效益.本文从能量、蛋白质、维生素、矿物元素的营养需要等方面对蛋鸡产蛋后期的营养调控进行总结,以期能够对产蛋鸡后期的营养调控提供参考.     

Relationships between genetic, environmental and nutritional factors influencing osteoporosis in laying hens

1. The effects upon bone quality of feeding limestone in flour or particulate form and housing type (cage or aviary) in lines of hens divergently selected for high (H) or low (L) bone strength over 7 generations were investigated. 2. As in previous generations, highly significant phenotypic differences between lines were observed in all measured bone traits at peak egg production (25 weeks) and towards the end of production (56 weeks) in both cage and aviary systems. 3. At 25 weeks there were no significant effects on bone variables of feeding particulate limestone although a significant reduction in osteoclast number was observed at this age. By 56 weeks osteoclast numbers were further reduced in hens fed particulate limestone and beneficial effects on some bone variables were observed in this treatment group. 4. The genotypic and dietary improvements upon bone quality were independent and additive at both ages. There were very few interactive effects. 5. Hens with the freedom to move in an aviary environment during the laying period had improved bone status compared to caged siblings. Environmental and genotypic effects were additive. 6. There were no effects of line on egg production although H line hens had slightly higher egg production by 56 weeks. Egg numbers were unaffected by diet. Eggshell thickness and strength were unaffected by line but hens fed particulate limestone had thicker- and stronger-shelled eggs over the production period as a whole. 7. We conclude that; (a) genetic selection is extremely effective in improving bone strength and resistance to osteoporosis; (b) allowing hens freedom to exercise can also improve bone strength but may increase the risk of keel damage if they do not have genetically-improved bone status; (c) feeding hens a particulate form of limestone from 15 weeks onwards can also increase bone strength and eggshell quality; (d) genetics, environment and nutrition all have independent and additive effects on bone status in laying hens but the relative effectiveness of these factors is genetics > environment > nutrition.     

产蛋鸡春季饲养管理技术措施

一、合理调整日粮营养水平 1.减少能量饲料 产蛋鸡在冬季气温较低的情况下,代谢能含量一般为每千克11.72兆焦,春季气温变暖后,如果继续喂高能量饲料,会使鸡体重增加,影响产蛋率。所以春季应降低鸡饲料中的代谢能。如果把鸡饲料中的代谢能含量降低到11.30兆焦,则可显著提高鸡的产蛋率。