Effects of multiple environmental and nutritional factors in laying hens

1. A large experiment on multiple factors and levels of those factors was carried out to test the hypothesis that in production experiments responses can be measured separately and then applied as if interactions are rare.

2. Significant interactions of any order were indeed found to be rare, except for the interaction between temperature and dietary protein content.

3. Responses to temperature, light intensity, protein content and feeding system were reasonably consistent with earlier reports.

4. The rarity of interactions validates the use of a previously‐published additive model.     

Studies on effects of nutritional factors on bone structure and osteoporosis in laying hens

1. A modern hybrid strain of laying hen (Hisex) was fed from point of lay to 68 weeks on a control diet and diets containing oystershell, fluoride, 1,25‐dihydroxycholecalciferol, ascorbic acid, a lower concentration of phosphorus and a combination of a lower concentration of crude protein and higher concentration of vitamin K. Hens from a much older strain (Brown Leghorn J‐line) were fed on the control diet.

2. Plasma variables were measured during lay. End‐of‐lay trabecular and medullary bone volumes in the proximal tarsometatarsus and free thoracic vertebra were measured by histomorphometry.

3. The majority of Hisex hens were considered to be osteoporotic by the end of lay. In contrast, none of the J‐line were osteoporotic.

4. None of the nutritional treatments affected trabecular bone volumes. Medullary bone volumes were increased significantly by feeding oystershell or fluoride.

5. There was no phenotypic correlation between egg production and trabecular bone volume in the Hisex hens.

6. The experiment provided evidence that osteoporosis in laying hens, as assessed by trabecular bone volumes, is not caused by calcium deficiency and could not be prevented by any of the nutritional treatments studied.     

蛋鸡生产中难题的解决（上）

１育成期对于蛋鸡的产蛋量主要取决于前期饲养，这一点始终强调得不够。我们看到鸡群蛋大小不令人满意、出现无法说明的高死亡率以及因食欲差而出现的饲养问题等。这些症状完全由于后备母鸡生长不良和不合适的光照刺激所致。不同品种的褐壳蛋鸡有它自己的体重和体格指标。种鸡标准依季节和气候条件的变化而不同，但应接近标准而使每个品种达到最大的生产效果。日粮类型会有些变化，但表１中的日粮可作为中国一般条件下的良好指南。在高温条件下，代谢能值可能减少约２０９ｋＪ／ｋｇ。确定育雏料和育成料的饲喂时间是灵活的，主要取决于鸡的…     

Relationships between fear of humans, productivity and cage position of laying hens

1. The productivity and behavioural responses of laying hens to humans were examined in relation to the effects of tier, row and position of the cage along the row over three consecutive 4-week periods. 2. Birds from the top tier had lower hen-day production, lower egg mass output and poorer efficiency of food utilisation than birds from the bottom tier in the third period. 3. Birds from the top tier showed greater avoidance of an approaching experimenter when in their cage or when on a table. 4. The production variables were significantly correlated with a number of behavioural responses to humans and a novel object, and with the corticosteroid response to handling/blood sampling. 5. The data suggest that birds from the top tier were more fearful of humans and that this higher level of fear may have been responsible for their lower productivity.     

Nutritional and environmental factors involved in egg shell quality of laying hens.

1. Two experiments were conducted to assess the effects of lighting regime, dietary calcium source and sodium bicarbonate on production variables and egg shell quality of White Leghorn hens. In both experiments, hens were assigned to one of three lighting programmes that provided evening, morning or intermittent (midnight) lighting supplements in addition to natural daylight. Experimental diets used in the first study were formulated to contain (1) ground oyster shell flour, (2) limestone flour, or (3) and (4) the same +2/3 of the calcium source as hen-size oyster shell grit. The same 4 diets plus those containing hen-size limestone or hen-size limestone and oyster shells were used in experiment II. Additionally, diets in the first experiment contained either 0 or 10 g/kg sodium bicarbonate. 2. Hen-day egg production and food consumption were not affected by any of the experimental treatments. Hens fed on oyster shell diets or exposed to intermittent lighting regimes laid eggs of the highest specific gravity. Shell quality, as measured by specific gravity, was not affected by the addition of dietary sodium bicarbonate. 3. As expected, elevated temperatures (greater than 32 degrees C) significantly reduced egg shell quality. However, this effect was variable particularly in experiment II which used younger hens. 4. The shell quality of eggs from hens exposed to intermittent lighting in experiment II was significantly higher in each of the 4 sampling periods: morning (08.00-12.00), afternoon (12.00-16.00), evening (16.00-20.00) and night (20.00-08.00). 5. It is suggested that midnight lighting programmes provide a means of supporting egg shell quality of older laying hens during the summer months without a significant reduction in egg production.     

Inheritance of bone characteristics affecting osteoporosis in laying hens

1. Heritabilities of a range of morphometric, radiological and strength characteristics were measured in the bones of end-of-lay hens. 2. Tibial strength (TSTR), humeral strength (HSTR) and keel radiographic density (KRD) were moderately to strongly inherited and were combined in a Bone Index which was used as a basis for selection. Data are available on 6 generations/cohorts of hens (n=1306), the last 3 of which are the progeny of divergently selected birds. 3. All bone characteristics used in the Bone Index responded rapidly to divergent selection and were strongly correlated with each other. In the last generation, the lines differed by 25% for TSTR, 13% for HSTR and 19% for KRD. The heritability of the index was 0.40. 4. There were no apparent genotype by environment interactions between birds housed at 2 different locations. 5. The incidence of bone fractures was significantly decreased in the line selected for high bone strength compared to the line selected for low bone strength. Humerus fracture incidence differed by a factor of 6 between the lines in the last generation. There was a strong quadratic relationship between tibia strength and overall fracture incidence (r2=0.92, P<0.01). 6. The results imply that selection for enhanced bone strength can be used as a long-term strategy for alleviating the problems of osteoporosis in laying hens.     

广西鸡舍内主要环境因子变化对蛋鸡生产性能的影响

为了解广西鸡舍内主要环境因子变化对蛋鸡生产性能的影响,本试验以全封闭笼养蛋鸡舍为对象,于2018年04月-2018年5月,每天监测鸡舍内环境的温度、相对湿度、CO2、NH3、H2S、SO2浓度变化,测定点设在鸡舍的前中后位置,每隔3 d测定鸡舍内细菌的总数,并分析各种环境因子与蛋鸡生产性能的相关性。结果显示,4月份和5月份蛋鸡舍内的温度与相对湿度均呈正相关关系,与CO2和NH3浓度均呈负相关关系(P<0.01),温度在29.1℃~30.2℃时,温度与产蛋率呈显著负相关(P<0.05);日均相对湿度与日均CO2浓度均呈负相关关系(P<0.01),5月份日均相对湿度与舍内日均NH3浓度呈负相关关系(P<0.05);4月份和5月份舍内日均CO2浓度与NH3浓度呈正相关关系;舍内温度、相对湿度、CO2浓度和NH3浓度与鸡舍内环境空气细菌总量有一定相关性;鸡舍内环境空气细菌总量与日均蛋鸡淘汰率、日均破蛋率相关关系不明显。试验表明,全封闭鸡舍内温度的升高对本地蛋鸡的产蛋率有显著影响,应及时调整通风和降温措施,以免影响蛋鸡的产蛋率。     

A spatial factor influencing food consumption in laying hens

1. A reduction in the number of cages occupied by laying hens in a row of battery cages lead to a mean increase in food intake per bird of about 4% compared with birds housed in similar rows in which all the cages were occupied.     

Antimicrobial resistance in Swiss laying hens, prevalence and risk factors

Antimicrobial resistance is an emerging concern to public health, and food-producing animals are known to be a potential source for transmission of resistant bacteria to humans. As legislation of the European Union requires to ban conventional cages for the housing of laying hens on the one hand, and a high food safety standard for eggs on the other hand, further investigations about the occurrence of antimicrobial resistance in alternative housing types are required. In this study, we determined antimicrobial resistance in indicator bacteria from 396 cloacal swabs from 99 Swiss laying hen farms among four alternative housing types during a cross-sectional study. On each farm, four hens were sampled and exposure to potential risk factors was identified with a questionnaire. The minimal inhibitory concentration was determined using broth microdilution in Escherichia coli (n=371) for 18 antimicrobials and in Enterococcus faecalis (n=138) and Enterococcus faecium (n=153) for 16 antimicrobials. All antimicrobial classes recommended by the European Food Safety Authority for E. coli and enterococci were included in the resistance profile. Sixty per cent of the E. coli isolates were susceptible to all of the considered antimicrobials and 30% were resistant to at least two antimicrobials. In E. faecalis, 33% of the strains were susceptible to all tested antimicrobials and 40% were resistant to two or more antimicrobials, whereas in E. faecium these figures were 14% and 39% respectively. Risk factor analyses were carried out for bacteria species and antimicrobials with a prevalence of resistance between 15% and 85%. In these analyses, none of the considered housing and management factors showed a consistent association with the prevalence of resistance for more than two combinations of bacteria and antimicrobial. Therefore we conclude that the impact of the considered housing and management practices on the egg producing farms on resistance in laying hens is low.     

The nutritional value of broad beans for laying hens

1. Three trials were conducted to study the influence of diets containing between 40 and 550 g broad bean (Vicia faba, Major) meal/kg on performance, egg quality and pancreas characteristics of White Leghorn hens.

2. The effect of broad beans on performance depended on the dietary content. Up to 100 g/kg did not affect productivity. Contents higher than 200 g/kg depressed egg weight (P<0.05). At 550 g/kg, food intake, egg weight and rate of egg production decreased but efficiency of food conversion was not impaired.

3. At 550 g/kg broad beans caused an increase in albumen density (P < 0.01). Broad beans did not affect shell thickness.

4. The size, weight, moisture content and histology of the pancreas were not affected by broad bean intake.     

影响蛋鸡产蛋率的营养因素及调控措施

<正>禽蛋营养丰富,是人们日常生活的主要食品之一。随着人民生活水平的不断提高,对禽蛋的需求量不断加大,促进了蛋鸡养殖业的发展。而我国蛋鸡养殖水平不高,如产蛋高峰期维持时间短、产蛋率低、产蛋量少等,直接影响养禽业的经济效益。因此,采取有效的措施,提高蛋鸡的产蛋率成为广大养殖户关注的焦点。对此,本文从营养调控的角度就如何提高蛋鸡的产蛋率问题进行综合阐述。     

产蛋鸡胆固酵代谢及其影响因素

本文综述了产蛋鸡体内胆固醇的吸收、合成、转运、去路以及影响鸡蛋中胆固醇含量的主要因素.     

Interrelationships between dietary concentrations of sodium,potassium and chloride in laying hens

1. Twelve diets, representing the factorial combination of two concentrations of Cl‐ (0.8 and 1.4 g/kg), three concentrations of Na+ (0.5, 1.1 and 1.7 g/kg) and two concentrations of K+ (7 and 12 g/kg) were fed to groups of laying hens for 24 weeks and records taken of their productivity.

2. Different concentrations of Na+, K+ and Cl‐ showed highly significant interactions which were always similar. Thus, a deficiency of Na+ (0.5 g Na/kg) was aggravated by the restriction of Cl‐ (0.8 g/kg), but was partly compensated for by supplementing the diet with K+ (12 instead of 7 g/kg). Without a sodium deficiency other interactions occurred; for example, the higher concentration of K+ became unfavourable if the other two ions were also supplied at the higher concentrations.

3. These results show that, for the laying hen, the optimum concentrations of Na+, K+ and Cl‐ cannot be determined independently but depend upon the concentration of the two others in the diet.     

A pecking device as an environmental enrichment for caged laying hens

To improve the welfare of caged laying hens, a pecking device made of stones was introduced on the cage floor. Twenty‐four White Leghorn hens aged 15 months were divided into four groups: single‐housed hens with device, single‐housed control hens, pair‐housed hens with device and pair‐housed control hens. Hens housed with the device pecked at various pecking objects less often than control hens. Agonistic behavior was also lower in hens with the device than in hens without the device, implied a possibility of improvement in quality of pecking stimuli with the device. Not only time spent pecking, but also quality of pecking might be important to fill their need for stimulation. Both single‐ and pair‐housed hens more often pecked at the device in the evening. Response to various pecking objects also showed that pecking behaviors were most frequently expressed in the evening. Increased foraging at dusk is a well‐known habit; therefore, the increase in pecking behavior in the evening might reflect the hens' general circadian rhythm. These results indicate that the device made of stones could promote some instinctive behavior. Enhancement of behavioral repertories and reduced agonistic behavior with the pecking device might improve the welfare of caged laying hens.     

Salmonella in Belgian laying hens: an identification of risk factors

Since the 1980s, the prevalence of Salmonella in Belgian poultry layers and broilers has greatly fluctuated with a rise observed in 2003 and a significant decrease in 2005. In order to alleviate the risk at egg consumer level, it is crucial to understand the factors which influence the contamination and the spread of Salmonella in laying hens. To study such determinants we explored the Belgian data from the 2005 baseline study on the prevalence of Salmonella in laying flocks of Gallus gallus in the European Union. The response variables corresponded to presence or absence of Salmonella from dust and faecal samples taken from the environment of a Belgian layer flock. The explanatory variables included: region of Belgium, sampling time (month the flock was sampled), production type (cage or barn and free range), Salmonella vaccination status, flock age and flock size. Analyses of these data were performed using a bivariate logistic regression model assuming independence between the two responses and bivariate generalized estimating equations model, which incorporates the correlation between the two responses on the same flock. The main risk factor that was identified was rearing flocks in cages compared to barns and free-range systems. The results also showed a significant higher risk for Salmonella for a 1 week increase in flocks’ age as well as with a unit increase in the size of the flock.     

家禽肠道疾病及其预防措施专栏(五) 产蛋母鸡的慢性肠炎

目前处理慢性肠炎的方法,是在不知病因的情况下通过增强母鸡的抵抗力和提高其康复率来控制疾病.这是荷兰两位家禽疾病研究人员的结论.     

高温条件下大豆黄酮对产蛋前期种鸡产蛋性能和血清甲状腺激素水平的影响

选取 90只 1 55日龄岭南黄肉用种母鸡 ,随机分为 3组 ,每组 30只。其中对照组饲喂基础日粮 ,试验组Ⅰ喂基础日粮 +大豆黄酮 (Da)每千克饲料 3mg ,试验组Ⅱ喂基础日粮 +Da每千克饲料 6mg。预试期为 7d ,试验期 2 5d。各组混养 3只公鸡。采集试验处理前 1d ( 2 2℃ )、处理第 7天 ( 2 3℃ )、 1 1天 ( 30 5℃ )、 1 5天 ( 32 3℃ )的血样 ,测定甲状腺激素 (T3、T4 )水平。结果显示 :①与对照组相比 ,温度为 30 5℃ ,持续 2d ,试验组Ⅰ和Ⅱ的产蛋率分别提高 30 0 %和 4 4 3% ,蛋重分别提高 5 99% (P <0 0 5)和降低 2 89% ,受精率分别降低 2 0 4 %和提高3 85% ,破蛋率降低 ;当温度升至 31 5～ 33℃ ,持续 4d ,试验组Ⅰ和Ⅱ产蛋率、蛋重、受精率和破蛋率增加 ,但差异不显著。②处理第 1 1天 ,与对照组相比 ,试验组Ⅰ和Ⅱ的T3分别提高 2 5 6 %和 56 4 % ;处理第 1 5天 ,T3分别提高 75 8%和 6 3 6 %。③与对照组相比 ,处理第 1 1天 ,试验组Ⅰ和Ⅱ的T4 分别提高 32 2 %和降低 9 1 2 % ;处理第 1 5天 ,T4 分别降低 1 5 1 7%和提高 4 7 9% (P <0 0 5)。     

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.