The effect of ahemeral light and dark cycles on patterns of food intake by the laying hen

1. Diurnal food intake rhythms of laying hens were studied under 21, 24 and 30‐h cycles, using either a constant 12‐h photoperiod or a 10‐h scotoperiod in each cycle. The feeding patterns essentially followed a circadian periodicity under all experimental situations. The peak in food intake which normally occurs before “sunset” in a 24‐h cycle was consistently observed to be timed from the onset of the previous dark period in each light and dark cycle, regardless of cycle length.

2. This study demonstrates that the laying fowl makes use of an endogenous biological rhythm to regulate its feeding behaviour. A light to dark transition in a light and dark cycle is the primary signal for phase‐setting the pattern of food intake.     

Food intake of the laying hen following crop loads of maize oil and other nutrients

The metabolisable energy (ME) of the diet of laying hens at an ambient temperature (Ta) of 20 degrees C was abruptly changed from 10.9 MJ/kg to 12.9 MJ/kg, or vice versa. Food intake during the next 14 d was significantly reduced by the low ME diet and was increased by the high ME diet, that is, the expected compensatory changes in food intake did not occur. Laying hens given the same change of diet as above but kept at 32 degrees C did not show any change in food intake within 14 d. Thus ME intake increased with the high ME diet and decreased with the low ME diet. Daily doses of 10 ml maize oil/kg body weight given directly into the crop of laying hens at a Ta of 20 degrees C, resulted in an immediate, significant, reduction of food intake such that total ME intake remained the same as with normal feeding. Daily doses of 3 ml maize oil/kg, given as before, resulted in an immediate, significant, reduction in food intake at a Ta of 20 degrees C but at a Ta of 32 degrees C food intake remained unchanged; consequently daily ME intake increased. Loading the crop with glucose or sucrose, at Ta 20 degrees C, in quantities which provided a similar ME as 3 ml maize oil/kg, reduced food intake but the adjustment was less precise and daily ME intake increased. Loading with glycerol or protein hydrolysate decreased both food and ME intake. Crop loads of starch were as effective as maize oil in bringing about a significant and compensatory reduction of food intake. Similar volumes of water or liquid paraffin placed in the crop did not affect food or ME intake. A similar weight or cellulose placed in the crop reduced food and ME intake.     

Effects of cholecalciferol or calcium deficiency on oestrogen metabolism in the laying hen

1. Seventeen 32-week-old White Leghorn laying hens were induced to become deficient in calciferol or in calcium (laying thin or soft shelled eggs) by withdrawing either cholecalciferol (27.5 micrograms/kg diet) or calcium (31 g/kg diet) supplements from the control diet. 2. The metabolic fate and metabolic clearance rate (MCR) of intravenously injected 3H-oestradiol-17 beta were then monitored for 40 min. 3. In both the calciferol and calcium-deficient groups a major oestrogen sulphate pathway was particularly affected, resulting in a decreased conversion of oestradiol-17 beta-3-sulphate to oestradiol-17 alpha-3-sulphate, with a concomitant reduced MCR of oestradiol-17 beta from plasma. 4. The metabolic defect was corrected by feeding the control diet. 5. Because the metabolic defect observed in calciferol deficiency occurred in Ca deficiency in a more severe form, we conclude that the more immediate cause was calcium rather than calciferol deficiency. To our knowledge, this is the first observation of a calcium-deficient effect on oestrogen sulphate metabolism in vivo.     

Evaluation of the dietary interaction of calcium and phosphorus in the high producing laying hen

1. In a 6 x 7 factorial experiment using 2688 22-week-old laying hens of the Lohmann-SL strain kept in cages (4 birds/cage), diets containing six calcium (20, 25, 30, 35, 40, 45 g calcium/kg) and seven phosphorus concentrations (3.2, 4.2, 5.2, 6.2, 7.2, 8.2, 16.2 g total phosphorus/kg (Pt)) were combined orthogonally. The resulting 42 treatments were replicated 8 times so that a replicate consisted of a double cage of 2 x 4 hens. The experiment lasted 40 weeks (10 x 28 days). 2. The experimental diets, based on maize and soyabean meals contained 11.5 MJ metabolisable energy/kg and 175 g/kg protein. Different dietary calcium and phosphorus contents were obtained by substituting oat hulls with limestone and dicalcium phosphate. 3. Mortality, egg production, egg weight, egg mass, food intake and food conversion efficiency were determined as well as the breaking strength, thickness of shells and the percentage of eggs with defective shells. 4. All responses measured were significantly influenced by the variance sources (calcium, phosphorus, interaction). Most of the production traits responded asymptotically to increasing dietary phosphorus concentration, the greatest increases or decreases generally being seen between 3.2 and 5.2 g Pt/kg. Further but weaker increases were seen between 5.2 and 8.2 or 16.2 g Pt/kg. 5. Increases in dietary calcium content always resulted in curvilinear responses. In all cases optimal effects were obtained with diets containing 25 g calcium/kg and the worst values at 45 g calcium/kg. The interaction between calcium and phosphorus was recognised by strong performance depressions and a high mortality at combinations of the lowest phosphorus concentration (3.2 g/kg) with high calcium contents (35 to 45 g/kg). These were largely offset by increasing dietary phosphorus. Thus, between 7.2 and 16.2 g Pt/kg and 25 and 45 g Ca/kg a plateau was formed where only small differences in egg production were observed. 6. From the three egg shell characteristics measured, breaking strength and shell thickness responded differently to the percentage of eggs with defective shells. While breaking strength and shell thickness were respectively negatively and positively influenced by increasing dietary phosphorus and calcium contents, both elements affected the proportion of eggs with defective shells.(ABSTRACT TRUNCATED AT 400 WORDS)     

Effects of food intake regulation on the energy metabolism of laying hens

1. The effects of dietary energy restriction on the energy metabolism of post‐peak‐of‐lay hens of two hybrid layer strains were studied by indirect calorimetry.

2. Starving and resting rates of heat production (SHP and RHP) were measured, over 1‐d periods, at intervals during a 25‐week period in which the experimental birds were individually restricted to 80% of their previous energy intake ad libitum.

3. In both strains mean RHP per bird was about 7% lower in the restricted birds than in controls fed ad libitum, but when RHP was expressed in terms of metabolic body size (kg^0.75) the two groups did not differ.

4. Mean SHP per bird was about 18% lower in the restricted birds of both strains than in the corresponding controls; the decrease in SHP per kg^0.75 was 12%.

5. Heat increment of feeding and calculated maintenance energy were higher, and net availability of metabolisable energy for maintenance and production was lower, in the restricted than in the control groups.

6. Gross efficiencies of egg production, in terms of both mass and energy, increased in the restricted birds.

7. Live‐weight and total carcass energy after 25 weeks of restriction were respectively about 15% and 30% lower in the restricted groups of both strains than in the groups fed ad libitum.     

Voluntary feed intake by lactating sows

Data from 3559 lactations in the Moorepark herd over a seven-year period were analysed. An increase in intake was associated with increasing litter size, increasing parity and lower pregnancy weight gain. Higher farrowing house temperatures were associated with lower intakes resulting in sows farrowing in July eating 10% less than sows farrowing in mid-winter. Higher weaning age was also associated with increased consumption. Review of the literature shows a number of other factors to be associated with variation in intake including breed of sow, system of feeding and system of sow management. Intake of higher energy diets is sometimes depressed but energy consumed may be increased. Sows fed low protein diets in pregnancy consume more of high protein diets in lactation but this is not so when a high protein pregnancy diet is fed.     

Behavioural differences between laying hen populations selected for high and low efficiency of food utilisation

1. The effects on behaviour of selecting light-hybrid laying hens for high and low efficiency of food utilisation were investigated. Efficiency of food utilisation was measured as the proportional deviation of observed food consumption from expected food consumption. 2. Videograms of the day-time behaviour of 48 to 53-week-old individually caged hens from the F3 generation were analysed by instantaneous sampling. 3. Low-efficiency hens spent more time food-pecking, walking, pacing, and showing escape and aggressive behaviour than did high-efficiency hens. High-efficiency hens spent more than twice as much time resting and sleeping, and were never observed pacing prior to laying. 4. These differences were larger during the 2 h before laying than at other times of day. 5. Low-efficiency hens had poorer plumage, especially on the neck and the breast, and the poorer the plumage the more agitation they showed. 6. Time spent food-pecking was negatively correlated with laying frequency. 7. Differences in the occurrence of specific behaviour patterns, particularly those symptomatic of pre-laying frustration, partly explained differences in efficiency of food utilisation. Selection for higher efficiency of food utilisation might eliminate hens which are most frustrated prior to laying in cages.     

Effect of water: food intake ratios in laying hens on food metabolisable energy

It has been hypothesised that a relatively high water intake results in a lower food digestibility. The influence of water:food ratios on the metabolisability of a diet was investigated. With ad libitum water and food the water:food ratios varied between 1.17 and 2.47 and showed a positive relationship with metabolisable energy. In groups of hens receiving 40 g food and water sufficient to provide water:food ratios of 1, 2, 3 and 4, the results showed a non-significant negative regression of apparent metabolisable energy with water:food ratios.     

光照与蛋鸡饲养的关系

1 光照的意义 光照是一门科学,要想养好鸡,就必须要懂得这门学问.在蛋鸡饲养上,光照与雏鸡发育、青年鸡生长、成年鸡产蛋等都有着极密切的关系.实践证明,光照的时数与强弱、光照的颜色与波长、光照刺激的起止时间、黑暗期是否连续或间断,都会对蛋鸡的成活率、生长发育、体成熟、性成熟、产蛋率以及繁衍后代的公母交配活动等方面,产生重要的影响.光照是蛋鸡饲养的重要的环境条件之一.换句话说,没有光照条件的环境,是不能进行蛋鸡饲养活动的.     

Thermal panting and respiratory alkalosis in the laying hen

1. Changes in respiratory rate (f), rectal temperature (T_r ) and blood acid‐base values were measured in laying hens exposed to ambient temperatures (T_a) of 32, 35, 38 or 41 °G.

2. At T_a 32 °G there was no panting. At T_a 35 °G panting occurred without any increase in T_r but there was a slight alkalosis (pH 7.55).

3. At T_a 38 °G T_r increased and panting was accompanied by moderate alkalosis (pH 7.58).

4. At T_a 41 °G T_r increased considerably and severe alkalosis developed (pH 7.65).

5. From the relation between T_r , f and pH it is concluded that some degree of alkalosis is a normal response to panting in the laying hen.     

Effect of laying on food and water intake in dwarf and normal hens

1. Irrespective of whether the hen carried the dwarfing gene, dw, food intake on days when there was ovulation and oviposition was higher than on days when there was only oviposition.

2. The “ overconsumption “ in dw hens was greater than in the Dw hens.

3. Food intake and shell thickness were correlated, the relationship being particularly close in dw hens.

4. There was a consistent and positive correlation between food intake and weight of egg laid on the same day in both Dw and dw hens.     

高钙高蛋白日粮对海兰褐蛋鸡肾脏结构与功能的影响

旨在探讨高钙高蛋白日粮对海兰褐蛋鸡肾脏结构和功能的影响。将80只40日龄海兰褐蛋鸡随机均分为4组,对照组(组1)饲喂基础日粮(钙1.0%、粗蛋白17.5%),组2饲喂高钙(钙4.5%),组3饲喂高蛋白(粗蛋白27.0%),组4饲喂高钙高蛋白(钙4.5%、粗蛋白27.0%)饲料,试验期95天。第95 d各组随机抽取6羽,采集血清用全自动生化分析仪检测血清尿酸(UA)、尿素氮(BUN)和肌酐(CR)。采血后扑杀,解剖并观察肾的病理变化及组织学变化,ELISA法检测肾脏中炎性因子白细胞介素1(IL-1)、白细胞介素6(IL-6)、肿瘤坏死因子α(TNF-α)的水平。结果在试验第95天,组2和组3鸡的体重显著低于对照组(P0.05),血清BUN值极显著高于对照组(P0.01);组4鸡血清UA和BUN显著高于对照组(P0.05),血清CR极显著高于对照组(P0.01)。部分试验组鸡肾脏肿胀,内有白色糊状物。组织学观察发现肾小球炎性肿胀或萎缩,肾小管上皮细胞变性、坏死并脱离基底膜。3个试验组肾组织中的IL-1均极显著高于对照组(P0.01)、IL-6显著高于对照组(P0.05);组2、4肾组织中的TNF-α显著高于对照组(P0.05),组3TNF-α极显著高于对照组(P0.01)。结论:饲喂高钙高蛋白饲料会对鸡肾的结构和功能产生不同程度损伤。     

微生态益生菌粉在蛋鸡日粮中应用效果

在蛋鸡日粮中加入2～8％生物饲料添加剂——兹生态益生茵粉等量替代豆粕,以61周龄海兰褐鸡群为试验鸡群,通过7周的饲喂试验观察结果如下：饲料成本略有下降;鸡群料蛋比下降2．79～4．57％;能明显改善蛋鸡的产蛋性能,延迟蛋鸡产蛋后期产蛋率的下降速度,使只鸡每周可多盈利0．036～0．06元;能增加鸡蛋壳的颜色和硬度,加深鸡蛋黄的颜色和弹性;对去除鸡舍中的臭味有一定的效果。微生态益菌粉在蛋鸡饲料中的添加量以5～8％为宜。     

生物鱼粉在蛋鸡生产中的应用

利用角质蛋白质进行氨基酸工业化生产,使废料资源化,保持生态良性循环,作为进口鱼粉的替代品在蛋鸡生产中应用。     

The metabolism of labelled progesterone in the laying hen

Eight hours after administering 4–14C‐progesterone to laying hens four radioactive metabolites could be detected in the droppings. Excretion of labelled steroid products was still continuing 192 h after the injection. In blood a relatively high level of labelled progesterone was found 8 to 24 h after application. The last traces disappeared from blood after 72 h. Compared with mammals the hen metabolises progesterone at a slower rate.

Certain tissues were also examined 24 h after treatment. The adrenals showed a high level of labelled progesterone metabolites. The liver contained similar steroids as were found in the droppings. In the ovary, pituitary and skeletal muscle low or trace amounts of radioactive steroids were detected.     

产蛋鸡卵母细胞卵黄生成受体(OVR)的研究进展

OVR介导大量的血浆蛋白被产蛋鸡吸收到生长的卵母细胞中,是卵黄前体进入卵母细胞的瓶颈。到目前为止发现它不仅与最丰富、最重要的卵黄前体极低密度脂蛋白(VLDL)、卵黄蛋白原(VTG)结合,还结合丛生蛋白、α2-巨球蛋白(α2-M)、受体相关蛋白(RAP)、乳铁蛋白、核黄素结合蛋白(ribBP)等,这些成分占蛋黄干物质的绝大部分。OVR发生突变的蛋鸡,不能繁殖,并且具有严重的高脂血症。它所内吞的VLDL的数量是蛋黄胆固醇含量的决定因素,因此期望通过调控OVR来控制蛋黄胆固醇的含量。     

植酸酶对产蛋鸡生产性能和代谢的影响

磷酸氢钙是饲料中最主要的磷来源之一 ,无机磷资源不仅在我国 ,就是在全世界范围内 ,已经处于匮乏状态 ,磷资源的匮乏使饲用磷产品价格上升 ,增加了饲料成本。植物性饲料中有 65 %～86 %的磷以植酸磷的形式存在 ,这些磷源不仅不能为单胃动物有效利用 ,而且会对环境造成严重的污染。如果能将植酸磷中的磷释放出来供动物利用 ,减少磷酸氢钙的用量 ,可缓解供求矛盾 ,并减轻粪磷污染。本试验旨在应用植酸酶迈特 -5 0 0 0以减少产蛋鸡日粮中的磷酸氢钙用量 ,观察其对产蛋鸡生产性能和代谢的影响。1　材料与方法试验在南京市青龙山养鸡场进行 ,选…