饲料生产和贮存中影响维生素稳定性的因素

维生素是一类动物代谢所必需而需要量极少的低分子有机化合物,它们主要以辅酶和催化剂的形式广泛参与体内代谢的多种化学反应,从而保证机体组织器官的细胞结构和功能正常。如果缺乏可引起机体代谢紊乱,影响动物健康和生产性能,严重时可导致动物死产。     

Factors affecting length of productive life in Swedish commercial sows

The objective of this study was to investigate factors that might influence the length of productive life in Swedish crossbred (Landrace x Yorkshire) sows. The data set consisted of 20,310 sows farrowing between 2001 and 2004 in 21 commercial piglet-producing herds. Productive life (PL) was defined as the number of days between first farrowing and removal or termination of data collection. In addition to the overall risk analysis of PL, another 4 longevity traits were analyzed (competing risk analyses): reproductive disorder-determined length of PL (RPL), udder problem-determined length of PL (UPL), lameness-determined length of PL (LPL), and mortality-determined length of PL (MPL). Analyses were performed by using survival analysis, applying a Weibull model with 6 time-dependent and 1 time-independent variable (age at first farrowing). The factor with the largest contribution to the likelihood function for PL was days after farrowing, followed by parity, the herd x year combination, the total number of piglets born, days between weaning and next farrowing, farrowing month, and age at first farrowing. For all 4 competing risk traits, the factors contributing most to the likelihood function were days after farrowing, the herd x year combination, and parity, with a varied order between traits. The hazard for removal was greatest 30 to 40 d after farrowing (after weaning) for PL, UPL, and LPL (P < 0.001). However, for MPL the hazard was greatest just after farrowing (0 to 10 d), and for RPL the hazard peaked at 70 to 100 d after farrowing. The hazard for removal was, compared with parity 1, less in parities 2 to 7 and greater from parity 8 for PL (P < 0.001). The hazard was greatest in parity 1 (P < 0.01) for RPL, UPL, and LPL, whereas for MPL the hazard increased with greater parity number and was markedly greater from parity 9 (P < 0.001). Sows with litters of 9 piglets or less had a greater hazard for removal than sows with litters of 12 to 13 piglets (P < 0.001). Intervals between 120 and 122 d from weaning to the next farrowing showed the lowest hazard for removal (P < 0.001). The influence of farrowing month displayed no clear pattern for PL. Sows of 14 mo or older at their first farrowing had a 20% greater hazard for removal than younger sows (P < 0.001). The hazard for removal was greater for smaller litters in all parities but was more accentuated in greater parities. Overall, days after farrowing was the main risk factor for sow removal. Removal hazard was greatest shortly after weaning, and this peak increased with greater parity number.     

Factors affecting piglet mortality in loose farrowing systems on commercial farms

Crating sows in farrowing systems greatly restricts their normal behaviour (e.g. movement, nest-building, leaving the nest site for defecation), which is usually justified by the assumption that piglet mortality is higher with loose-housed sows. Based on experiments showing that this is not the case, farrowing crates were banned in Switzerland in 1997, with a 10-year transitional period. Since then, many farms have introduced loose farrowing systems, enabling an analysis of risk factors for piglet mortality in crateless farrowing systems based on a large sample size. Data from a Swiss sow recording scheme (UFA2000) were analysed using generalised linear mixed-effects models with an underlying Poisson distribution. Average total piglet mortality for the years 2002 and 2003 on 99 farms (N = 12457 litters) with loose farrowing systems amounted to 1.36 liveborn piglets per litter. The number of crushed piglets was 0.64 piglets per litter, whereas the number of piglets that died for other reasons was 0.72 piglets per litter.Herd size, pen size, possibility of confinement of the sow, presence of piglet protection bars and year of data collection did not significantly influence total piglet losses, losses due to crushing and losses due to reasons other than crushing. With greater litter size at birth, significantly more losses occurred due to all reasons (total, crushed, others). Total piglet mortality and losses for reasons other than crushing were significantly higher in older sows. Losses were therefore mainly attributable to sow-related characteristics rather than to the design of the farrowing pen.     

Factors affecting the mortality of weaned piglets during commercial transport between farms

Factors affecting the number of weaned piglets found dead after commercial transport between farms were studied by means of multilevel Poisson regression. Information relating to 58,682 piglets during 109 journeys in different EU countries was collected at the end of each journey by means of questionnaires. Overall, 0.07 per cent of all the transported piglets were found dead on arrival, and deaths of piglets were recorded in 13.8 per cent of journeys. The final regression model, which was calculated using the complete records from 105 journeys, included the total duration of the journey, the mean outside temperature during the journey, whether the piglets were fasted before transport, whether drinking water was provided, the type of ventilation in the vehicle and the interaction between journey duration and the mean outside temperature. The duration of the journey and the mean outside temperature showed a significant interaction effect, with a gradual increase in the predicted number of dead piglets with increasing journey duration as the outside temperature increased. Providing the piglets with drinking water and having mechanically assisted ventilation (fans) in the vehicle during the journey significantly reduced the number of deaths, as did fasting the piglets before transport.     

Factors affecting hatchability during commercial incubation of Ostrich (Struthio camelus) eggs

1. A batch of 320 ostrich eggs from 9 different farms in Zimbabwe were incubated in a single stage operation and the fate of each was recorded.

2. Hatchability was only 37.2% and the result of high rates of infertility and contamination (22.2% and 22.8% respectively); it varied between eggs from different farms.

3. Embryonic mortality was high at the start and end of incubation, a pattern similar to that of other domestic birds.

4. Mortality of late stage embryos was related to percentage water loss and mass specific water vapour conductance of the shell, with extremes of the ranges causing the highest mortality.

5. Microbial contamination of the eggs was a significant problem and varied in eggs from different farms indicating that more attention is needed in both breeder bird and nest management.     

Evaluation of phytase concentration needed for growing-finishing commercial turkey toms

1. Growth performance, serum bone markers, and bone strength and mineralisation were determined in tom turkeys grown from 9 to 17 weeks of age. 2. Dietary non-phytate phosphorus was formulated to be reduced by 1.0 g/kg in the low phosphorus diet compared to a control diet and phytase was added to provide 0, 150, 300, 450 or 600 units/kg activity to the low phosphorus diet. 3. From 9 to 12 weeks of age, body weight and gain:food were reduced by the low phosphorus diet without added phytase, compared to the adequate phosphorus diet. Increasing the concentration of phytase linearly increased these growth parameters. There were no significant growth responses at 17 weeks of age. 4. Serum osteocalcin was reduced by increasing dietary phosphorus at 12 weeks of age when growth was affected, but not at later ages. Serum pyridinoline was reduced by higher dietary phosphorus and decreased linearly with increasing phytase activity at 17 weeks of age. 5. Fracture force of the ulna and femur increased linearly with increasing phytase activity but bone strength was not affected when corrected for bone cross-sectional area. Bone strength of the ulna and ash concentration of the ulna and tibia were increased by higher dietary phosphorus. Humerus and ulna ash increased linearly with increasing phytase activity. 6. Water-soluble phosphorus content of the litter was increased by higher dietary phosphorus and addition of phytase to the low phosphorus diet. The increase in water-soluble phosphorus content of the litter when phytase was fed may indicate that phosphorus could be fed at a lower concentration than used in this trial, at least in the finisher diet when phytase is added to the food. 7. Bone fracture force, strength and ash were generally optimised when 450 units/kg phytase activity was added to the low phosphorus diet. However, growth performance was best in the grower I (9 to 12 weeks) phase when 600 units/kg phytase was added to the diet.     

猪用植酸酶产品功效的比较

正植酸酶产品在每单位酶释放的磷值上存在差异。同样,实验室对植酸酶活性的分析也存在差异。因此,在比较植酸酶活性和添加水平时必须谨慎。一种可以比较不同植酸酶产品活性以确定不同产品间替代率的方法,是在指定的磷释放值(如,释放0.10%的有效P)上比较它们的功效。     

植酸酶的耐热性及其耐热机理的研究进展

植酸是谷物、豆类和油料等作物中磷和肌醇的主要存贮形式[1],同时对保持机体磷的平衡起着重要的作用。以植酸磷形式存在的磷因单胃动物体内缺乏能分解植酸磷的酶而难以被利用,从而造成许多问题:①磷资源的浪费。一方面饲料中的磷得不到有效利用;另一方面则需加入大量无机磷以满     

植酸酶的特性及稳定性效果的对比研究

试验就植酸酶的相关特性及其在此基础上的应用选择功效进行研究,并对市场上占有率较高的三个国产知名企业生产的植酸酶产品(P1、P2、P3)进行稳定性研究,比较这三种植酸酶产品在不同pH值、不同温度下(室温、80℃水浴、90℃常湿)和不同储存时间的酶活,为生产实践中合理选择使用植酸酶提供参考依据。结果表明,P2在酶活高峰pH值4.5～5.0表现出的酶活显著高于P1和P3(P0.05)。高温稳定性效果P3显著优于P1和P2(P0.05)。     

植酸酶包埋后酶活和热稳定性变化的规律研究

为了了解植酸酶在包埋状态下酶活及酶性的变化,分别对酶的释放情况和热稳定性进行了研究.结果表明,随着时间的延长,包埋酶释放出的酶活逐渐上升(P＜0.01),60min时达到最大值;而未包埋酶释放出的酶活逐渐下降(P＜0.01),60 min时达到最小值.包埋酶和未包埋酶在30、40、50、60、70、80、90和100℃的条件下,随着温度的升高,残留的植酸酶活力下降(P＜0.01).对于包埋酶,当温度升高到70℃时,植酸酶相对酶活仍保持在93%(P＞0.05);当温度升高到80℃时,植酸酶的相对酶活才明显下降(P＜0.01),不过在100℃时,仍能保持67%的酶活(P＜0.01).对于未包埋酶,当温度升高到60℃时,植酸酶相对酶活明显下降(P＜0.01);当温度升高到100℃时,植酸酶相对酶活仅有23%(P＜0.01).通过在统一温度条件下,对包埋酶和未包埋酶处理组的相对酶活的对比发现,在50℃以下时,二者差异不显著,当温度超过60℃时,包埋酶的相对酶活极显著高于未包埋酶.     

Investigation of resistance of bacteria from commercial poultry sources to commercial disinfectants

Concern by consumers about food safety has resulted in increased pressure on poultry companies to develop effective sanitation programs. Salmonella isolates in hatcheries are often the same species isolated from processing plants. Resistance develops in bacteria after prolonged exposure to disinfectants. The methods available in published literature to detect the efficacy of disinfectants are labor intensive and do not consider how bacteria behave when adhered to a solid surface. We used a recently developed technique, which utilizes the actual surfaces on which the disinfectant is to be applied, to evaluate the degree of resistance to four commercially available disinfectants of 17 bacterial isolates from poultry hatcheries. We found that bacterial isolates within the same genus and species have different sensitivities to the same disinfectant. In addition, disinfectants with similar but not identical chemical formulations have different efficacies against the same bacteria.     

液态植酸酶膜处理及其稳定性研究

本实验通过高效液相色谱法(HPLC)分析植酸酶发酵液相对分子质量大于2000的物质中,植酸酶的含量为77.52%,植酸酶的相对分子质量约40000,实验分别选用截留相对分子质量为5000和100000的超滤膜处理植酸酶发酵液,超滤后植酸酶蛋白含量达90%。在25℃避光保存6个月,液态植酸酶样品浊度有所上升,但未见明显沉淀现象。     

Heat stability of endogenous and microbial phytase during feed pelleting

Heat stability of commercial preparations of phytase has been of concern for quite some time, and efforts have been made to develop new preparations of this enzyme. A study was conducted to determine the stability of commercially available phytase product (granulate; Phytase A) and the new experimental product (powder; Phytase B). In the in vitro study, incubation of 100 mg of each of Phytase A and B with 200 μl of buffer for 2 min (30 s at desired temperature) resulted in 27.6 and 10.4% loss of activity at 60 °C and 80.6 and 53.9% at 70 °C, respectively. Both enzyme products were further subjected to steam pelleting in feed mills located in Manitoba and British Columbia. In the Manitoba study, the temperature of pellets as recorded at the discharge averaged 67 °C and was similar to that determined in British Columbia (70 °C). Under such temperatures, which may have been lower than the actual temperatures within the pellet mill, the loss of endogenous phytase activity averaged 58.5% (from 451 to 187 U kg^− 1) and 42.5% (from 287 to 165 U kg^− 1) in the two mills, respectively. Following correction for endogenous phytase activity, Phytase A and B recovery averaged 36.4 and 49.9%, respectively, at the Manitoba site and 44.1 and 49.4% at the British Columbia site. It appears evident from this study that the heat stability of enzyme (protein) per se rather than the granulation technology is a primary factor determining the stability of microbial phytase during steam pelleting.     

提高真菌植酸酶热稳定性的方法

植酸酶(Phytase)能提高饲料中磷及其他养分的利用率,减少粪便中磷的排泄量,同时还能降低植酸(盐)的抗营养作用,在饲料中添加植酸酶对提高畜禽生产性能及减轻环境污染有着重要意义。真菌植酸酶具有pH作用范围广、活性高和易提纯等优点,是生产植酸酶的最佳来源。但是真菌植酸酶热稳定性普遍较低,不能完全满足饲料加工的要求。本文综述了在提高真菌植酸酶热稳定性研究方面的最新进展,讨论了其进一步的研究方向。     

影响牧草再生性的因素分析

对影响牧草再生性的诸因素进行了分析,阐明了牧草再生性对刈割和放牧利用方式的响应,以及刈割和放牧后牧草体内贮藏的碳水化合物和氮素在再生中的变化规律及作用,为草地的放牧利用和刈割提供了理论和技术依据。     

影响饲料安全的因素

本文阐述了原料、饲料添加剂和加工工艺对饲料安全造成的负面影响,并提出相应对策。     

糖及硫酸铵对植酸酶热稳定性的影响

植酸酶可作为单胃动物的饲料添加剂,其饲喂效果已在世界范围内得到肯定。但目前植酸酶在饲料中的推广和应用还相当有限,主要原因在于:1)植酸酶在天然原料中含量太低,难以大量生产;2)植酸酶的热不稳定性使其不能完全满足饲料加工、贮藏和使用的要求。随着基因工程技术的发展,植酸酶在天然原料中含量太低的问题已基本得到解决,但植酸酶的热稳定性问题仍然存在。饲料加工制粒中有一个短暂的高温阶段,温度一般在75～93℃,植酸酶的活性在此高温下,将大幅度不可逆丧失。为提高植酸酶的热稳定性,我们探讨了海藻糖、葡萄糖、甘露醇、硫酸铵对植酸酶…