Magnesium metabolism in the laying fowl

Laying fowls were fed on synthetic diets containing 49, 118, 486, 655, 1242 and 2176 mg/kg magnesium. Magnesium intake and plasma concentration were significantly correlated: 49% of the plasma Mg was diffusible. The hens fed on magnesium‐deficient diets (49 to 118 mg/kg magnesium) were hypomagnesaemic while those receiving 2176 mg/kg were hypermagnesaemic. In the deficient hens the liver showed magnesium depletion, increased calcium content and decreased fresh weight. Skeletal muscle was unaffected by the dietary variations in Mg. The magnesium concentration in the femur was positively correlated with the plasma magnesium concentration. Femurs showed a loss of magnesium and increased mineralisation (especially of the medullary bone) in deficient hens, and a net gain of magnesium in the birds receiving 2176 mg/kg magnesium. The magnesium concentrations in egg shells, albumen and yolk were also positively correlated with the plasma magnesium concentration. The shells of eggs laid by magnesium‐deficient hens were thin, a reflection, apparently, of the reduced plasma calcium levels associated with the decreased bone mobilisation.     

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.     

矮脚黄鸡、新兴黄鸡、广西三黄鸡产蛋性能比较研究

本试验对广东地区矮脚黄鸡、新兴黄鸡、广西三黄鸡等品种种鸡产蛋性能进行了比较研究。结果表明,矮脚黄鸡的适应性、抗病性较强,死淘率低（6．31％）,料蛋比低（5．05）,产蛋整齐性好,从开产到产蛋率达80％的天数短（25天）;新兴黄鸡产蛋期产蛋教高达182．44枚,破蛋率低,为1．55％;广西三黄土鸡开产日龄早（148日龄）,日采食量低（164．83g）,产蛋期只总耗料量为41．37kg。矮脚黄鸡对广东地区高温、多湿的环境适应性较强,适合在广东地区饲养。     

The feeding of oxytetragycline to growing and laying ducks

Three hundred and eighty‐four Aylesbury ducklings were divided into two groups. From 8 days of age one group was fed on a basal ration and the other this ration supplemented with 45 g. of oxytetracycline hydrochloride per ton of food. The antibiotic tended to increase live‐weight gain and to thin the alimentary canal, but the only significant difference was in the weights of 1 cm. lengths of the caeca.

Three hundred Khaki Campbell laying ducks were kept in two groups, one group being fed on a basal pelleted diet and the other this diet supplemented with 100 g. of oxytetracycline hydrochloride per ton. Egg production was significantly increased by the antibiotic, but body weight was not significantly affected. There was a tendency for the alimentary canal to be thinned by the antibiotic, but the only significant difference was in the average percentage weights of the small intestine.     

Comparisons of the skeletal systems of growing broiler and laying strain chickens

Skeletal systems of growing broiler and laying strain chickens were compared in an attempt to establish whether the rapid growth rates of broilers lead to qualitative or quantitative skeletal deficiencies. Qualitative comparisons included studies of bone histology and of bone ash, density and compression strength. Quantitative comparisons related bone weight to body weight. Bone “ matured “ very rapidly, as judged by its density, ash content and weight relative to bird weight in the first fortnight of life and thereafter more slowly in both broilers and laying strain birds. After the age of I week bones “ matured “ mainly by replacement of water by mineralised osteoid—the degree of mineralisation of osteoid being a less important factor in bone “ maturation “. There were no significant differences from the viewpoint of either quality or quantity between the skeletal systems of broilers and laying strain birds of the same age. At equal body weights, however, broilers had skeletal systems which were both qualitatively and quantitatively less “ mature “ than those of laying strain birds. These differences were most marked during early life when the rate of skeletal “ maturation “ was high.     

Carcass conformation comparisons of growing broiler and laying strain chickens

The conformations of growing broiler and laying strain chickens were compared in an attempt to discover whether, in the course of selecting broilers of high growth potential, the conformations of such birds had been so altered as to predispose them to skeletal failure. It was found that broilers had essentially similar proportions by weight of their various body complexes to laying strain birds of equal body weights. Broilers had slightly greater trunk proportions and lower leg proportions than laying strain birds of equal weights but the differences were insufficiently great to explain satisfactorily the supposed predisposition of the broiler leg skeleton to failure. Broilers, at any given body weight, had bones shorter in length than laying strain birds, explaining the more compact appearance of the broiler when compared with the more slender laying strain bird. A compact skeletal system is one which would appear less rather than more likely to fail.     

开放式鸡舍商品蛋鸡光照管理技术

我国大部分地区自然光照条件是上半年一般冬至(12月22日左右)到夏至(6月22日左右)日照时间由短逐渐变长，称为渐长期；下半年即从夏至到冬至由长渐缩短，称为渐短期。     

蛋种鸡育成饲养管理技术措施

7～20周龄这段时间称为育成期.育成期管理的好坏,直接影响产蛋鸡的生产性能,它是奠定鸡成熟后的体质、蛋重、产蛋率和种用价值的基础条件.现将育成期饲养管理技术措施简述如下.     

浅谈鸡群产蛋率突然下降的原因与防锖

在生产实践中,常常会遇到产蛋鸡群产蛋率突然下降的情况。现就鸡群产蛋率突然下降的原因和防制办法简述如下。     

AA父母代种鸡高产技术措施

我公司１９９７年４月８日从北京爱拔益加育种公司引进ＡＡ父母代种鸡２２４５１套，经过科学的饲养管理，严格选育，２４周末育成合格种鸡２１６０９套，育成率９６．２５％，６６周末累计产合格种蛋４０６２４９２个，平均入舍鸡只产蛋１８８个，产健雏３５４９４１５只，平均入舍鸡只产雏１６４．２６只，各项指标都已超出了ＡＡ公司的生产指标，取得了良好的经济效益和社会效益，现将高产技术总结如下，以供参考。１严格限饲，控制体重１．１１～２周自由采食，充分饲喂，促使雏鸡多吃高蛋白营养的育雏料以充分发育骨架，并使母鸡在２周…     

夏季提高蛋鸡产蛋率的主要措施

夏季日照强，气温高，昼夜温差小，而鸡没有汗腺，对高温的适应力差。此时，蛋鸡采食量会减小，体重减轻，如果不及时采取一些防治措施，将最终导致蛋鸡的产蛋率下降，蛋壳质量降低，严重影响养鸡的经济效益。因此，夏季防暑降温，加强饲养管理，缓解热应激是提高蛋鸡夏季产蛋率的必需措施。     

蛋鹌鹑对饲料食盐耐受量的研究

鹌鹑作为仅次于鸡、鸭的“第三养禽业” ,在我国规模化饲养已有十多年的历史了。它是公认的高产、高效益的产业之一 ,当今世界饲养量 1 0亿多只 ,我国饲养近 2亿只 ,居世界之首 ,但对其研究报道并不多见 ,尤其是有关饲料食盐含量对它的生产性能和蛋壳品质的影响的研究报道更少。食盐是动物机体不可缺少的物质 ,对机体维持体液渗透压、膜电位、酸碱平衡和神经肌肉的正常兴奋性等都起着重要作用 ,但如给饲过多也可引起动物慢性或急性中毒 ,造成动物生产性能下降 ,死亡率上升。张珊珊 ( 2 0 0 0 )报道 ,产蛋鹌鹑因采食咸鱼粉 (含盐量为 1 1 6 …     

不同添加量植酸酶对蛋鸡生产性能的影响

选择42周龄海兰褐蛋鸡1200只,随机分成5组,设正对照组、负对照组和3个试验组。3个试验组分别饲喂负对照组日粮基础上含不同添加量植酸酶(150、300、600U/kg)的日粮(营养标准相对正对照组低0.12%有效磷)。试验期60d,考察不同添加量的植酸酶对蛋鸡生产性能的影响。试验结果表明:150U/kg添加组与正对照组生产性能相比,产蛋率提高0.22%,蛋重、采食量、料蛋比分别降低0.16%、0.42%和0.47%,统计上均无显著差异(P>0.05);150U/kg添加组与300、600U/kg添加组相比统计上也无显著差异(P>0.05)。这表明饲料中使用150U/kg该植酸酶可达到与目前市场上普遍使用300U/kg植酸酶的效果,也能满足蛋鸡营养(磷)需要。     

Effects of food regulation during the growing and laying stages on the productivity of broiler breeders

1. From 1 to 22 weeks of age 720 Ross 1 parent stock pullets were given regulated amounts of food to achieve 90, 100 or 110% of a target weight (R90, R100 or R110, respectively) while from 23 to 64 weeks of age they were fed 80 or 100% of a set allowance (L80 or L100, respectively). One hundred and fifty Ross 1 parent stock males were on the R110 treatment and then either the L80 or L100 during breeding.

2. Mean number of settable (> 53 g) eggs per hen housed was 131, 131 and 135 and mean number of chicks hatched per hen housed was 108, 101 and 101, respectively, for the R90, R100 and R110 treatments. These differences were not statistically significant.

3. Mean number of settable eggs per hen housed was 116 and 148 and mean number of chicks hatched per hen housed was 94 and 112, respectively, for the L80 and L100 treatments (P<0.001).

4. Fertility and hatchability were improved but uniformity of the birds was decreased by restricting food intake.     

Influence of graded levels of calcium and vitamin K in the diets of laying hens during the growing phase and their effects on the laying phase

The aim of this study was to evaluate the effect of dietary supplementation of vitamin K (vit K) and Ca in the diets of laying hens on bone and blood parameters and performance during the growing phase and the effects on the laying phase up to 32 weeks. The study utilized 120 Hy‐Line W‐36 pullets in the growing phase (13–18 weeks), 80 laying hens in the production phase (20–32 weeks), distributed in a completely randomized design in a 2 × 5 factorial arrangement, two levels of Ca (0.8 and 1.4%) and five levels of vit K supplementation (0, 2, 8, 16 and 32 mg/kg) with four experimental units. An experimental diet was fed during the growing phase, and the commercial diet was fed during the production phase and were analysed for biochemistry and bone variables at 18 and 32 weeks. In pullets, a significant interaction of levels of vit K and Ca was observed for total serum calcium (mg/dl), Seedor index, Ca in the bones (%) and medullary bone (%). Pullets at 18 weeks of age, receiving diets with 1.4% Ca, displayed a quadratic effect of vit K with better results for these variables with 17.86, 14.59, 14.48 and 16.80 mg/kg of vit K, respectively. For level 0.8% Ca no effect of vit K was observed. The treatments during the growing phase had no effect on egg production, performance and biochemistry serum until 32 weeks. Medullary bone (%), there was a significant interaction for 1.4% Ca and a quadratic effect for vit K, with greater medullary bone areas observed with 6.09 mg/kg vit K in the diet. Supplementation with vit K in a diet with 1.4% Ca during the growing phase allowed for an increase in the area of medullary bone at 18 weeks, which was maintained until 32 weeks.     

日粮维生素水平对生长期蛋鸡影响的研究

选用4因素3水平正交试验设计，研究日粮维生素A、D3、E对生长期蛋鸡的影响。结果如下：6周末体重随VE水平的提高而提高，但差异不显著。14周末体重受VE的显著影响。高水平（100mg／kg）组显著大于低水平（10mg／kg）组与中水平（40mg／kg）组（P＜0．01），中、低水平之间差异不显著。血清新城疫抗体效价随VA水平的提高而显著提高（P＜0．05）。高水平VA和高水平VE组合组显著高于其它组（P＜0．05）。胫骨中的钙含量随VA水平的提高显著提高（P＜0．01）。VD3对体重、抗体滴度和胫骨Ca含量无显著影响。