Boluses of controlled release glass for supplementing ruminants with cobalt

Boluses of controlled release glass containing cobalt and weighing approximately either 60 g or 14.5 g were administered to 22 steers and 21 sheep respectively. The steers were housed and slaughtered at intervals between 17 and 145 days after dosing. The boluses released more than 0.85 mg cobalt daily. In both untreated and dosed animals serum and liver vitamin B12 concentrations were at the upper end of the normal range. Two types of glass were administered to sheep. In five wethers one glass released 0.07 mg cobalt per day, and in 16 grazing lambs a second glass released more than 0.15 mg cobalt per day. Fourteen of the boluses were recovered from the lambs up to 276 days after dosing. The concentration of B12 in serum of lambs increased significantly from a mean +/- sd of 1.64 +/- 0.47 to 2.02 +/- 0.04 ng/ml serum and the concentration in liver from 3.84 +/- 0.85 to 4.99 +/- 0.72 micrograms/g dry weight liver.     

反刍动物营养中铜的研究进展

铜是反刍动物必需微量元素之一。文中论述了铜在反刍动物体内的分布及消化代谢特点、作用机制 ,反刍动物铜营养需要量 ,影响铜利用的因素以及外源铜在反刍动物日粮中的添加利用。     

Controlled release technology for the control of helminths in ruminants

Release rates from controlled release devices are determined by the device itself and thus are accurate, reproducible and predictable, whereas in general, prolonged or slow release systems are sensitive to environmental conditions. Diffusion and dissolution are the principal means of achieving controlled release. A diffusion system is specific for the active ingredient and release rate decreases proportionately to the square root of time because of a decreasing concentration gradient or an increasing diffusion path. In dissolution systems, the choice of matrix determines the rate of dissolution and release rates are linearly related to the area of dissolution which can be maintained constant. Consequently, this system has general application, a sharp cut-off point and can be used for more than one ingredient simulatenously. Potential disadvantages of controlled release technology centre on unacceptable tissue residues and parasite resistance to the chemicals used. Advantages include, the ability to programme the release of compounds to achieve specific effects for various periods, decreasing the frequency of dosage and increasing the choice of compounds for the control of parasitic infections. Sufficient epidemiological information should be available before controlled release technology is implemented. Existing anthelmintics and control strategies can be used to achieve an enhanced, but expected result, e.g., prolonged reduction in pasture contamination to protect both ewes and lambs. In future it should be possible to devise compounds and strategies appropriate to the unique features of controlled release technology, e.g., compounds which interrupt or inhibit the growth and development of parasites. Environmental impact should be low because of the specific effect and low dosage of the chemical used.     

Induction of oral lesions in broiler chicks by supplementing the diet with copper.

Copper sulfate was added to the diet of broiler chickens from 1 day to 3 weeks of age at the rate of 0.05% to 0.20% in order to evaluate its influence on the incidence of oral lesions. Both the incidence and severity of oral lesions showed a significant linear increase as the concentration of copper sulfate increased. Adding a level of sulfate equivalent to that produced by the highest level of copper sulfate failed to induce oral lesions. The severity of gizzard erosion also increased as the concentration of copper increased. Dietary copper sulfate supplementation should be considered a possible cause of oral lesions seen during the necropsy of avian species.     

影响反刍动物铜吸收利用的因素

铜是动物必需的微量元素之一,大量的试验研究已证实,铜具有广泛的生物学作用,它与畜禽的生长性能,繁殖性能,免疫功能等关系密切。铜的缺乏对畜禽的造血功能,神经系统,心血管系统,骨骼生长,被毛生长发育等均会造成不同程度的影响。1铜的吸收代谢机制1.1铜的吸收和转运动物体内的     

影响反刍动物硒、铜生物利用率的因素

日粮中微量元素的生物利用率(bioavailability)及其影响因素在反刍动物与非反刍动物间差别很大。通常，反刍动物日粮中纤维含量高，其中大部分经瘤胃微生物发酵而被消化。但是，微量元素和饲料中的纤维络合及和消化道中未消化完全的纤维粘附影响了其在反刍动物体内的生物利用率。并且，饲料中也存在多种拮抗物质干扰了它的吸收代谢。另外，在弱酸性(pH6．0～6．8)的瘤胃环境中多种微量元素及形成的金属络合物以不溶形式存在。硒、铜是反刍动物机体内多种酶的组成成分，但其吸收代谢受诸多因素影响。本文简要分析硒、铜为反刍动物利用的影响因素，并比较了它们的无机形式和有机形式在生物利用率匕的差异。     

Yak interferon-alpha loaded solid lipid nanoparticles for controlled release

To explore the potential of a novel animal interferon formulation for controlled release, the yak interferon-alpha (IFN-α) glutathione S-transferase (GST) fusion protein was expressed in Escherichia coli (E. coli) and the purified recombinant IFN-α was encapsulated into solid lipid nanoparticles (SLN) by double emulsion solvent evaporation (w/o/w) method. The particle size and zeta potential of IFN-α-loaded SLN were 124.2 ± 10.2 nm and −11.2 ± 0.6 mV. The encapsulation efficiency of IFN-α and loading capacity of the SLN were 83.7 ± 4.5% and 1.73 ± 0.15%, respectively. In vitro release study and antiviral assay demonstrated that the IFN-α released from the SLN in a 16-day period exhibited antiviral activity in Madin-Darby bovine kidney (MDBK) cells against vesicular stomatitis virus (VSV), and showed a release pattern of an initial burst release followed by a sustained and slow release. Cytotoxicity assay in cell culture demonstrated that the SLN were not toxic. The results of this exploratory study suggest that the IFN-α-loaded SLN could be a useful formulation for controlled release in veterinary therapeutics.     

An evaluation of a controlled release system for selenium in lambs

The efficacy of 100-day controlled release anthelmintic capsules containing Se for increasing and maintaining the Se status of lambs was evaluated. Capsules containing either 7.7 or 13.9 mg of Se increased the mean blood Se concentrations from 1.50 +/- 8.4 nmol/l in the unsupplemented lambs to 440 +/- 29.8 and 990 +/- 83.4 nmol/l respectively 100 days after their administration. Blood Se concentrations then declined to 250 +/- 21.5 and 380 +/- 50.1 nmol/l respectively by day 210. The addition of 13.9 mg of Se to a 100-day controlled release anthelmintic capsule is an effective method of protecting lambs from Se deficiency for at least 180 days.     

Effects of supplementing laying rations with certain B-complex vitamins

Two tests, using commercial White Leghorn layers and simplified rations, were conducted to determine the need for certain supplemental B‐vitamins. Varying levels of a multiple supplement (containing riboflavin, pantothenic acid, niacin and choline) were used in the first test. A factorial arrangement of treatments, using single and combination additions of riboflavin, pantothenic acid and niacin, was employed in the second test.

During the first test all supplemental vitamin levels resulted in a highly significant increase in egg production and egg size. The lowest dietary supplemental vitamin level was just as adequate as higher levels. Food consumption, body weight gain, viability and specific gravity of eggs were not significantly affected by B‐vitamin fortification.

Riboflavin supplementation resulted in a significant increase in egg production in the second test. The specific gravity of eggs was significantly decreased due to riboflavin supplementation. The addition of niacin and pantothenic acid to the basal ration did not significantly influence performance. Riboflavin was the only vitamin which exerted an appreciable influence on egg size during the second test.     

Potential problems associated with the controlled release of anthelmintics in grazing animals

A high, constant and sustained release of drug appears to be a major requirement to avoid a late season rise in pasture infectivity that may result in production losses in calves in autumn or Type II osteragiasis in the following spring. The timing of administration is of crucial importance and will vary in regions of different epidemiology, such as between northern and southern United States. Lack of a standard and reliable technique for pasture larval counts has resulted in some negative or erratic results which are open to question. Although controlled release anthelmintics offer advantages of convenience, a comparison of the economic benefits at present favours prophylactic treatment of dairy heifers with conventional anthelmintics 3 and 6 weeks after spring turnout in northern regions of the Northern Hemisphere. There is a serious risk that boluses based on controlled release by diffusion will behave like slow decaying insecticides and select strongly for drug resistance, especially if farmers administer them in succession throughout the grazing season. There are, however, 2 features in the design of a controlled release device that in theory may minimize the risk of rapid selection for resistance: a high and constant release of anthelmintic followed by a rapid decline to zero as the device becomes exhausted. Under these conditions, the device may even prolong the useful life of an anthelmintic to which resistance has already developed. This paper was presented at Pfizer Symposium on The Application of Sustained Release Anthelmintic Dosage Forms in the Control of Parasites in Grazing Animals at the World Association for the Advancement of Veterinary Parasitology (W.A.A.V.P.) 10th International Conference, 18-20 August 1983, Perth, W.A., Australia.     

铜对反刍动物瘤胃微生物及纤维降解影响的研究进展

反刍动物瘤胃中栖居有大量的微生物,这些微生物对纤维物质的降解起着重要作用。微量元素铜不仅是反刍动物生长发育繁殖所必需的,也是瘤胃微生物生长所必需的。适当剂量铜的添加有助于瘤胃纤维降解菌群数量的增加,从而促进纤维物质的降解。     

反刍动物饲用尿素缓(控)释技术研究进展

尿素缓(控)释技术包括物理缓释法、化学缓释法、抑制脲酶活性法和近年来出现的包被尿素法。本文对几十年来关于饲用尿素缓(控)释方法进行了综述,指出物理方法中以糊化淀粉尿素和糖蜜尿素舔砖较为可行,但这两种方法并没有提高尿素氮的利用率;化学缓释法中以羟甲基脲最为可行;抑制脲酶活性法普遍存在瘤胃微生物对之产生适应性的问题;包被尿素法可以根据瘤胃微生物对氨气的需要进行控释,开发经济、无毒无害并可生物降解的包膜材料是今后研究的重点。不同生态区位瘤胃微生物对氨气的动态营养需要模式是进一步提高饲用尿素缓(控)释效果的理论基础。     

Feeding value of pastures for ruminants

Perennial ryegrass is the primary forage component of ruminant diets in New Zealand. It is persistent and palatable, and immature ryegrass has a high nutritive value (NV). However, seedhead development substantially lowers its feeding value (FV) as fibre concentration increases, the rate and extent of digestibility decreases, and voluntary intake declines. Ryegrass pastures are susceptible to accumulation of endophytic and saprophytic fungi in dead material at the base of the sward, especially when mature and laxly grazed. Feeding forage legumes to ruminants grazing grass-dominant pastures will improve animal performance and lessen the reliance on a single species to meet all nutritional requirements. The FV of forage is a function of intake and NV, measured by chemical analyses and animal feeding trials. Performance of individual animals grazing forages is usually limited by energy intake because structural fibre can slow digestion and clearance from the rumen and because of competition between individuals for available feed. The use of metabolisable energy (ME) content of forage to signify FV can give a reasonable indication of animal performance, but it should be used in conjunction with chemical analyses to improve the accuracy of predictions. The relationship between FV, pasture production, animal performance and profitability is complex. The importance of skilled management to maintain pasture quality and optimise animal performance under inconsistent climatic conditions should not be underestimated. Acceptable animal performance with minimal veterinary intervention requires good nutrition, but the genetic potential of livestock in New Zealand cannot be met solely by grazing pasture, especially when a high utilisation of pasture is required to maintain quality and profitability. Producers are responding to industry demands to reduce the seasonality in supply of milk and meat by changing lambing and calving dates, and extending lactation length in dairy cows. Social changes include adoption of once-daily milking in the dairy industry. Some changes have necessitated increased use of supplements and others can be met by feeding forages with a higher FV than ryegrass, all of which require an improved knowledge of feed quality. This information is available through rapid and inexpensive near infrared spectroscopy (NIRS) analysis, enabling animal nutritional needs to be balanced by appropriate nutrient supply. It is essential that producers continue to improve animal welfare, limit excessive use of fertilisers and meet the demands of overseas consumers. Good nutrition, with an increased use of legumes and other forages to complement ryegrass pastures, will enable these objectives to be achieved.     

Feeding value of pastures for ruminants

Perennial ryegrass is the primary forage component of ruminant diets in New Zealand. It is persistent and palatable, and immature ryegrass has a high nutritive value (NV). However, seed-head development substantially lowers its feeding value (FV) as fibre concentration increases, the rate and extent of digestibility decreases, and voluntary intake declines. Ryegrass pastures are susceptible to accumulation of endophytic and saprophytic fungi in dead material at the base of the sward, especially when mature and laxly grazed. Feeding forage legumes to ruminants grazing grass-dominant pastures will improve animal performance and lessen the reliance on a single species to meet all nutritional requirements.

The FV of forage is a function of intake and NV, measured by chemical analyses and animal feeding trials. Performance of individual animals grazing forages is usually limited by energy intake because structural fibre can slow digestion and clearance from the rumen and because of competition between individuals for available feed. The use of metabolisable energy (ME) content of forage to signify FV can give a reasonable indication of animal performance, but it should be used in conjunction with chemical analyses to improve the accuracy of predictions.

The relationship between FV, pasture production, animal performance and profitability is complex. The importance of skilled management to maintain pasture quality and optimise animal performance under inconsistent climatic conditions should not be underestimated. Acceptable animal performance with minimal veterinary intervention requires good nutrition, but the genetic potential of livestock in New Zealand cannot be met solely by grazing pasture, especially when a high utilisation of pasture is required to maintain quality and profitability.

Producers are responding to industry demands to reduce the seasonality in supply of milk and meat by changing lambing and calving dates, and extending lactation length in dairy cows. Social changes include adoption of once-daily milking in the dairy industry. Some changes have necessitated increased use of supplements and others can be met by feeding forages with a higher FV than ryegrass, all of which require an improved knowledge of feed quality. This information is available through rapid and inexpensive near infrared spectroscopy (NIRS) analysis, enabling animal nutritional needs to be balanced by appropriate nutrient supply. It is essential that producers continue to improve animal welfare, limit excessive use of fertilisers and meet the demands of overseas consumers. Good nutrition, with an increased use of legumes and other forages to complement ryegrass pastures, will enable these objectives to be achieved.     

Use of erythrocyte copper:zinc superoxide dismutase activity and hair or fleece copper concentrations in the diagnosis of hypocuprosis in ruminants

Changes in the activity of superoxide dismutase, a copper-containing enzyme in erythrocytes (ESOD), and changes in copper in hair or fleece were compared with the changes in plasma copper during copper depletion and repletion in steers, lambs and ewes. During depletion the decline in ESOD began later than the decline in plasma copper: the lag varied from 0 to 80 days in individual steers and it was least evident when young rapidly growing lambs were subjected to severe depletion. ESOD activity eventually declined at only one-third to one-seventh of the rate shown by plasma copper, the difference being particularly marked in severely depleted lambs. Repletion of ESOD began after repletion in plasma copper and continued more slowly particularly in growing animals. Hair and fleece copper also responded relatively slowly to depletion and repletion. Low values of ESOD and hair or fleece copper may have diagnostic significance, indicating a more prolonged or intense deficiency of copper and a higher probability of clinical and production responses to copper therapy than low plasma or liver copper values.     

藏羊营养缓释技术的研究

对 3类营养缓释弹丸进行体外耐受性试验 ,结果表明 :A型弹丸具有良好的耐酸、耐碱、耐水、耐磨、耐压功能 ,B、C型次之。将A型弹丸每 2枚分为 1组 ,共分 8组 ,分别称重后 ,经瘤胃瘘管或直接灌服的方法 ,投服给 8只供试羊 ,并且在其降解的第 2 ,8,1 5,30 ,45 ,60 ,75和 90d分别收集被降解后弹丸 ,阴干后称重。结果表明 :A型反刍家畜营养缓释弹丸在羊瘤胃中第 2 ,8,1 5 ,30 ,45 ,60 ,75和 90d的降解率分别为 0 97% ,5 2 9% ,1 6 1 7% ,31 63 % ,34 2 6% ,41 47% ,43 76 %和 49 73 %。据此得出A型弹丸的有效降解率方程符合抛物线模型 :P =-0 0 0 0 9t2 +0 1 63 1t - 0 0 0 52 8,其中P为降解量 ,t为降解天数。由此方程可确定该缓释弹丸的有效降解天数为 60d。 60d内弹丸的降解量方程为P =0 1 0 91t +0 2 875 ,弹丸的降解量与降解天数呈强直线相关 (r=0 9698)。     

反刍动物秸秆基础日粮补饲苜蓿的组合效应

本文综述了反刍动物秸秆基础日粮补饲苜蓿的组合效应，并对该类饲料组合效应的产生机理进行了归纳，指出经作者改进的卢德勋（2003）提出的组合效应综合评定指数（MFAEI）可对饲料间组合效应进行整体量化．指导反刍动物秸秆基础日粮的补饲。     

The necessity of supplementing laying hen diets with linoleic acid

Results from four experiments with laying hens have been re‐examined using the means of individual 28‐d periods during egg production to investigate the influence of the developing ovary and linoleate storage during growth on the linoleic acid requirement of the laying hen.

Apart from a possible beneficial effect during the first few weeks of production, little increase in egg weight occurs when birds are fed on conventional rearing diets and then fed on laying diets containing linoleic acid in excess of requirement.

After depletion of linoleate reserves, dietary supplementation with linoleic acid significantly increases egg weight at any age.

The necessity of supplementing diets for laying hens with linoleic acid is discussed.