Tierärztliche Fakultät - Digitale Hochschulschriften der LMU - Teil 02/07

Das Ziel der vorliegenden Arbeit ist es, die Auswirkung von präoperativ verabreichten Schmerzmitteln (Meloxicam, Metamizol) bzw. des Lokalanästhetikums Procainhydrochlorid auf den kastrationsbedingten, vor allem den postoperativen Schmerz zu untersuchen.

Die Untersuchung wurde an vier bis sechs Tagen alten gesunden Ferkeln durchgeführt. Die Tiere wurden in die Versuchsgruppen I bis VI eingeteilt. Die nicht kastrierte Kontrollgruppe (I) wurde lediglich wie bei einer Kastration fixiert. Tiere der Kontrollgruppe (II) wurden ohne Verabreichung von Schmerzmitteln kastriert. 15 Minuten vor der Kastration wurde Tieren der Meloxicam-Gruppe (III) 0,4 mg/kg KGW Meloxicam i.m., Tieren der Meloxicam+Metamizol-Gruppe (IV) 0,4 mg/kg KGW Meloxicam und 50 mg/kg KGW Metamizol und Tieren der Metamizol-Gruppe (V) 50 mg/kg KGW Metamizol i.m. verabreicht. Tieren der Lokalanästhesie-Gruppe (VI) wurde 5 mg/kg KGW (0,5 ml) Procainhydrochlorid 15 Minuten vor der Kastration in jeden Hoden appliziert. Kurz vor der Fixation bzw. Kastration und eine, vier und 28 Stunden danach wurden Blutproben entnommen und ein, sieben und 14 Tage nach der Kastration wurden die Wunden mit Hilfe eines Wundscores beurteilt.

Um postoperative und zum Teil auch intraoperative Schmerzen zu beurteilen, wurde die Kortisolkonzentration im Blut gemessen. Die Ergebnisse der beiden Kontrollgruppen I und II zeigen, dass Kortisol nicht durch Handling und Blutentnahme bedingten Stress, jedoch aufgrund der neuroendokrinen Stressreaktion durch erhebliche kastrationsbedingte Schmerzen, eine Stunde nach der Kastration stark ansteigt, nach vier Stunden bereits nachlässt und nach 28 Stunden wieder den Basalwert erreicht.

Tiere, welchen präoperativ Meloxicam appliziert wurde, zeigen eine Stunde nach der Kastration nur einen sehr geringen Kortisolanstieg und damit eine erhebliche Verringerung der postoperativen Schmerzen gegenüber ohne Schmerzausschaltung kastrierten Ferkeln. Hingegen scheint eine alleinige Metamizol-Applikation die Schmerzen nach der Kastration weniger effektiv als Meloxicam zu mindern. Tiere, die unter Lokalanästhesie kastriert wurden, zeigen eine Stunde nach der Kastration im Mittel den höchsten Kortisolanstieg. Dies deutet auf mindestens vergleichbare, wenn nicht größere Schmerzen durch die intratestikuläre Lokalanästhesie mit Procainhydrochlorid im Vergleich zur Kastration ohne Schmerzausschaltung hin.

In der vorliegenden Untersuchung beeinflussen weder Kastrationsschmerz oder Stress durch Handling und Blutentnahmen die Stoffwechselparameter Glukose und Laktat, noch sind kastrations- und belastungsbedingte Muskelschäden mit Hilfe der Gewebeenzyme AST, CK, LDH und α HBDH zu messen. Innerhalb von 28 Stunden nach der Kastration treten bei keiner Gruppe Wundheilungsstörungen auf, die zum Anstieg der Leukozytenzahlen führen. Innerhalb von 14 Tagen sind mit Ausnahme der Ferkel der Metamizol-Gruppe, die nach 14 Tagen einen geringgradig höheren Wundscore aufweisen, keine Unterschiede des Wundheilungsverlaufs oder der Ferkelverluste festzustellen.

Daraus folgt, dass die Kastration unter intratestikulärer Lokalanästhesie mit Procainhydrochlorid die Forderung nach einer Verringerung der Schmerzen bei der Kastration von Saugferkeln nicht erfüllt. Hingegen erweist sich die einmalige präoperative Injektion des nichtsteroidalen Antiphlogistikums Meloxicam sowohl im Hinblick auf die Schmerzreduzierung als auch aufgrund der Praktikabilität als die Methode der Wahl.

In order to gain an overview of game husbandry in Germany 800 questionnaires were sent to game farmers all over Germany through the Association of Spare-Time Farmers. Of the questionnaires distributed, a total of 266 were completed and returned (response rate: 33.3 %). In addition, visits were paid to 137 of those game reserves in order to verify the game farmers´ statements on site.

The majority of the reserves contained red deer, fallow deer or a mixed population of red and fallow deer (92.8 %). Sika deer (3.0 %) and wild boars (4.2 %) only played a subordinate role in game farming. Game reserves for wild boars were most commonly pure hunting reserves (75.0 %), whereas the majority of red and fallow deer (39.8 %) and sika deer (37.5 %) were farmed for hobby purposes. The reserves varied in size from less than 2 ha to more than 40 ha, most reserves having an area of 2 to 10 ha. The average number of animals per reserve was relatively constant irrespective of the size of the reserve, so that the legally permissible population density of 10 animals per ha in the case of fallow deer or 6.7 animals per ha in the case of red deer was usually exceeded in the reserves with an area of less than 5 ha.

Special shelters were provided in 63.5 % of all reserves. In 79.3 % of reserves the number and size of the feeding sites was such that all animals were able to eat at the same time. Most game farmers fed their animals once a day, and in 28.6 % of the reserves there was a possibility of strangers feeding the animals as well. Water was supplied via automatic waterers, water troughs or flowing water bodies. The height of the fence varied between 1.90 m and 2.20 m. The majority of reserves were equipped with a trap door entry (79.7 %). 83.0 to 92.3 % of all reserves had acute-angled corners in the fencing.

In 83.3 % of the wild boar and in 62.5 % of the sika deer reserves there had been no diseases, whereas in 56.2 % of the red deer and in 60.2 % of the fallow deer reserves 1 to 15 cases of disease had occurred per reserve and year. These were mainly injuries, parasitic infestation or lameness. The number and percentage of diseases of the musculoskeletal system, the airways and the digestive system as well as injuries were highest in the reserves smaller than 2 ha. The highest percentage of disorders of the digestive system in red and fallow deer was associated with trough feeding.

Deworming was never performed in 37.5 to 66.7 % of the reserves, and in 88.5 to 100 % of the reserves there had never been any ectoparasite treatments. Regular cleaning of the feeding sites was performed in 50.0 to 96.4 % of the reserves, and in 35.2 to 53.8 % the shelters were cleaned on a regular basis. 38.0 to 62,5 % of the game farmers took regular fecal, blood, ground and other samples in order to check on the animals´ state of health and the hygienic condition of the reserve. The most common parasites found were gastrointestinal worms, the small and large liver fluke, and lungworms (Dictyocaulus filaria and Varestrongylus sagittatus).

All in all, a number of deficiencies in game husbandry in Germany have been identified within the framework of this paper. These deficiencies can only be remedied by introducing more precise legal provisions for reserve approval, by improving veterinary control of the reserves, and by more expertise on the part of the game farmers.

The objective of this study was to evaluate mutual influence of different pathogens in the development of pneumonia and bronchopneumonia in pigs. Bronchoalveolar lavage fluid of 91 clinically unsuspected and 197 pigs with respiratory problems, were examined. A postmortal examination was done in 128 pigs.

In the analysis, M. hyopneumoniae, M. hyorhinis, PRRSV (US-Type), PRRSV (EU-Type), PCV-2, Influenzavirus Type A, α-hämolytic Streptococcus, β-hämolytic Streptococcus, P. multocida, B. bronchiseptica, H. parasuis and A. pleuropneumoniae, were taken into consideration. The pathological-anatomical examination was evaluated with the prospect of the existence of an interstitial, catarrhal-purulent bronchopneumonia and pleuritis. All examined pathogens were found more often in the clinically suspected animals than in the group of clinically unsuspected animals. This difference was significant for α-hämolytic Streptococcus, H. parasuis, M. hyopneumoniae and M. hyorhinis. PCV-2 and α-hämolytic Streptococcus were isolated most frequently in BAL. The pathogen A. pleuropneumoniae was isolated culturally in two cases from BALF.

A comparison of detection frequency in different weight groups showed that M. hyopneumoniae, M. hyorhinis, P. multocida and B. bronchiseptica occurred more often in heavier, older animals. H. parasuis occurred most frequently in animals with a body weight of ≤ 7,5 kg.

Causal agent associations could be ascertained more frequently in the group of clinically suspected animals than in the group of clinically unsuspected pigs. Remarkably noticeable was that both α-hämolytic Streptococcus as well as M. hyopneumoniae were associated with M. hyorhinis, PRRSV (EU-Type), P. multocida and B. bronchiseptica. These pathogens seemed to favour infections with the above mentioned four causal agents, or that α-hämolytic Streptococcus occurs more when pigs are infection with other pathogens.

P. multocida and B. bronchiseptica were both associated significantly with M. hyopneumoniae, α-hämolytic Streptococcus, PRRSV (EU-Type) and PRRSV (US-Type) respectively. Furthermore a correlation of clinical and pathological examinations scores could be seen for M. hyopneumoniae and α-hämolytic Streptococcus. These two agents were isolated more frequently and semi quantitatively more often in BALF, with increasing severity of clinical and pathological-anatomical changes.

The importance of multiple infections with different causal agents for the disease picture of pneumonia and bronchopneumonia was analysed. A multiple infection with five or more agents was detected significantly more often in the group of clinically suspected animals than in the group of unsuspected pigs. The number of animals, where two or less than two pathogens were detected in the BALF, was significantly higher in the group of clinically unsuspected pigs than in the group of clinically suspected pigs.

The higher the clinical examination score was, the higher were the number of animals, where 5 or more different pathogens could be detected. A similar connection could be seen in the pathological-anatomical examination score.

The more different agents were isolated in BALF in one animal, the higher was the average pathological-anatomical examination score. The results of the analysis in weight groups, showed that with an increase in weight, the number of animals with ≥ 5 and ≤ 2 different agents increased.

This could be due to the different husbandry systems which could cause an infection with various pathogens. Infections with different pathogens are more likely in exploratations with continuous occupation of animals from different origins. A multiple infection is more unlikely in closed exploratations.

BAL can be seen as suitable to diagnose pneumonia or bronchopneumonia in pigs. A cultural and molecular biological evaluation of several samples should be done to enable the initiation of suitable prophylactic and therapeutic measures. A serological examination is given pr

By assessing the results of this study, guidance should be provided regarding intramuscular injection volumes of medicines for pigs meeting animal welfare standards.Totally, 252 pigs were included in the trial. Tissue reactions of varying injection volumes were investigated in three groups formed according to age. Group 1 comprised suckling piglets 3 - 28 days of age. Piglets of Group 2 were 4 - 12 weeks old and Group 3 was formed of fattening pigs and sows.

Studying the effect on haptoglobin concentrations of an intramuscular injection of NaCl, Stellamune® Mycoplasma, Suvaxyn® M.hyo, M+PAC® or Myofer® 100, only the vaccine M+PAC® (2 ml dosage) showed an increase above the upper value of the normal range (1.42 +/- 0.6 mg/ml).

The local tolerance of two antibiotics (Terramycin® 100 and Draxxin®) was studied in three age groups. The three mycoplasma vaccines (Stellamune® Mycoplasma, Suvaxyn® M.hyo, M+PAC®) were tested in suckling as well as weaned piglets and the PRRSV-vaccine (Ingelvac® PRRS MLV) only in weaned piglets. The studied criteria comprised the laboratory parameters leukocytes, AST and CK. Additionally, the injection sites were assessed clinically over a period of six day post injectionem as well as pathoanatomically and histologically.

After a single injection of Terramycin® 100 or Draxxin®, determined leukocyte values did not point to any inflammatory reactions in any of the age groups. The injection of Terramycin® 100 resulted in elevated AST enzyme values above the maximum reference standard of 35 U/l in weaned piglets, fattening pigs and sows as well as after application of Draxxin® to suckling and weaned piglets. After administration of Draxxin®, creatine kinase values rose above the limit (2000 U/I) in all age groups while after application of Terramycin® 100, elevated values of CK were only found in the groups of fattening pigs and sows. Comparing the two antibiotics, the clinical investigation of injection sites resulted in significant differences in suckling piglets and partly highly significant differences regarding individual experimental parameters in the age groups of weaned piglets and fattening pigs/sows. Comparing the three age groups and evaluating the injection sites macroscopically, predominantly highly significant differences were observed concerning the parameter “extension score 3D”. Equally, significant or highly significant results were recorded when the two antibiotics were compared separately according to age groups. Histologically, extreme myodegeneration as well as coagulation necrosis were seen. The latter was demarcated by a massive inflammatory vallum with fibroblastic budding. Giant cell formation as well as myofibrillar calcification additionally to adipose cell and vascular necrosis was found in the age groups of the “weaned piglets” and of “fattening pigs/sows”.

After injection of Mycoplasma hyopneumoniae vaccines, AST enzyme values rose above the maximum range limit (8 – 35 U/I) only after application of 4 ml Suvaxyn® M.hyo to suckling piglets and after administration of 2 ml M+PAC® to weaned piglets.

The findings of the clinical investigation of the injection site were either depending on the used vaccine or the applied volume. Predominantly highly significant differences were determined by macroscopic investigation of the injection site comparing the vaccines separately within dose volumes and age groups. Significant differences were seen when comparing dose volumes of Suvaxyn® M.hyo (2 and 4 ml) in the two age groups (suckling and weaned piglets) and of M+PAC® (1 and 2 ml).

The results of the histologic investigation showed that the type of tissue reaction predominantly depends on the composition of the vaccine. Consequently, marked differences were found between the three used mycoplasma vaccines, however, the histological findings were predominantly uniform within the treatment groups.

Concerning the tissue reaction, an obvious difference was observed between the two dose vol

Overall 1664 piglets from two Bavarian farms were examined weekly with regard to the aetiology of umbilical hernia. The 1664 piglets were fathered by 24 boars from three artificial insemination centres in Bavaria and one artificial insemination centres in Baden-Württemberg, Germany.

The main concern was the connection of umbilical hernia with a possibly existing omphalitis (inflammation of the umbilicus), particularly during the suckling period. In addition to this, the impact of the litter number of the sows, the birth weight, the gender, the length of the umbilicus and the occurrence of umbilical abscesses were investigated.

The piglets were included in the test on the first or second day of life. After determination of their gender and weight, the piglets were given numbered ear tags to enable their proper identification until the 12th week of life, the end of the investigations. The clinical check-up included visual and palpatory examination of the umbilicus and the umbilical cord in a weekly rhythm. After weaning the investigation was restricted to weekly palpation of the umbilicus and its surroundings. The various parameters such as epithelisation, swelling, reddening, oedematisation, exudate, umbilical abscess and umbilical hernia were evaluated according to a scoring system.

After an analysis of the results, it was possible to recognise connections between the occurrence of umbilical hernia and boars or the occurrence of umbilical hernia and the piglets of young sows. Furthermore, inflammations of the umbilicus correlated with litters of old sows, increasing birth weight, increasing length of the umbilicus and female piglets. No connection was found between an inflammation of the umbilicus and an umbilical hernia. Interestingly there was a connection identified between umbilical abscesses and hernias.

In summary it can be said that a severely pronounced, persistent inflammation of the umbilicus (omphalitis) does not necessarily lead to an increased occurrence of umbilical hernia. Primarily heredity transmission through the parent animals appears to have the greatest influence on the occurrence of umbilical hernias and thus also on the culling of piglets with umbilical hernias.

Über die Lokalisation, Morphologie und Kompartimentierung aviärer myeloider Zellen ist zum derzeitigen Stand der Forschung nur sehr wenig bekannt, und das obwohl dieses Wissen unverzichtbar für das Verständnis der Funktion dieser Zellen und damit der grundlegenden Mechanismen der Immunabwehr beim Vogel ist. In der vorliegenden Arbeit wurden daher drei stark exponierte Organsysteme, nämlich die äußere Haut, die Bursa und die Lunge immunhistologisch mit verschiedenen myeloiden Markern untersucht und die positiven Zellen hinsichtlich ihrer Morphologie und ihrer Verteilung im Gewebe ausgewertet. Bei den untersuchten Hühnern handelte es sich um Weiße Leghörner im Alter von neun bis zwölf Wochen. An Antikörpern wurden der Panleukozytenmarker 16-6, die gegen Monozyten, Makrophagen und interdigitierende DCs gerichteten mAks KUL01 und CVI-ChNL-68.1, die für MHC II-Moleküle spezifischen mAks 2G11 und LD42, der mit reifen Gewebemakrophagen reagierende mAk CVI-ChNL-74.2, der gegen follikuläre DCs gerichtete mAk CVI-ChNL-74.3 sowie der mAk 3-6, ein Antikörper mit unbekannter Spezifität, eingesetzt. Bei den Hautproben kamen zusätzlich die für g/δ T-Zellen beziehungsweise α/β T-Zellen spezifischen mAks anti-TCR-1 und anti-TCR-2 zum Einsatz.

Das Ziel der vorliegenden Arbeit war es, herauszufinden in wieweit die Therapie einer metabolischen Azidose bei Durchfallkälbern durch die orale Verabreichung von Natriumbikarbonat per Kälberschlundsonde möglich ist und ob der Pansensaft-pH-Wert Einfluss auf die Resorption des in den Pansen eingegebenen Puffers hat. Es sollte festgestellt werden, ob es eine bestimmte für alle Kälber mit einer gering- bis mittelgradigen metabolischen Azidose geltende Menge an Natriumbikarbonat gibt, die oral verabreicht in der Lage ist diese Durchfallkälber zu therapieren, ohne dass Nebenwirkungen des Natriumbikarbonats auftreten. Das Patientengut bestand aus 32 bis zu vier Wochen alten Kälbern, die infolge eines Durchfallgeschehens eine metabolische Azidose aufwiesen. 50 g Natriumbikarbonat oral verabreicht war eine Puffermenge, die den Blut-pH-Wert und den BE-Wert der Kälber zumindest vorübergehend ausgeglichen hat, ohne dass deutliche Nebenwirkungen auftraten. Bei einigen Tieren dieser Untersuchung mussten weitere Pufferbehandlungen durchgeführt werden. Es gibt aber keinen eindeutigen Befund, der bereits im Voraus die Vermutung zulässt, welche Tiere eine weitere Pufferbehandlung benötigen. Bei Kälbern, die nach der Behandlung eine gute Tränkeaufnahme zeigen, ist eine ausreichende Wirkung der einmaligen Pufferbehandlung anzunehmen. Ein Einfluss des Pansensaft-pH-Wertes auf die Resorption des Natriumbikarbonats im Pansen konnte nicht festgestellt werden.

Die normale Entwicklung von Embryonen nach somatischem Zellkerntransfer („somatic cell nuclear transfer“, SCNT) hängt unter anderem von der erfolgreichen Reprogrammierung und Aktivierung von Schlüsselgenen ab. Ein Beispiel ist das Gen für den Transkriptionsfaktor Oct4, der im frühen Embryo nachweisbar und als Marker für pluripotente Zellen gilt. Die in klonierten Mausembryonen häufig beobachtete abnormale Expression von Oct4 wird als eine mögliche Ursache für die hohen Verluste und schweren Fehlentwicklungen nach Kerntransfer diskutiert. Beim Rind liegt im Vergleich zur Maus und anderen Spezies die Erfolgsrate am höchsten. Daher ist die Untersuchung der Reprogrammierung von OCT4 nach SCNT in der frühen Embryogenese beim Rind von besonderem Interesse. Um Fragen der epigenetischen Reprogrammierung des Rindergenoms und der Rolle von OCT4 nach SCNT nachzugehen, wurden bovine fetale Fibroblasten stabil mit einem Oct4-EGFP-Reportergenkonstrukt transfiziert. In den unilokulär stabil transfizierten Zellen mit unauffälligem weiblichen Karyotyp war in Analogie zur Inaktivität des endogenen OCT4-Gens in differenzierten Zellklonen keine EGFP-Fluoreszenz nachweisbar. Das Anschalten der Oct4-EGFP-Expression nach SCNT entsprach weitgehend der nach in vitro Fertilisation beobachteten Aktivierung des endogenen OCT4-Gens. In SCNT-Embryonen mit weniger als neun Zellkernen wurde keine EGFP-Fluoreszenz nachgewiesen. In allen Embryonen mit mindestens 17 Zellkernen war das Oct4-EGFP-Reportergenkonstrukt aktiv, was darauf hindeutet, dass Blastomeren nach der vierten Zellteilung den Oct4-Promotor aktivierten. Mittels konfokaler Laser Scanning Mikroskopie wurde an zentralen optischen Schnitten die Intensität der EGFP-Fluoreszenz jedes Embryos gemessen. Im Vergleich mit Tag 4 SCNT-Embryonen war die EGFP-Fluoreszenz in Tag 6 Embryonen deutlich stärker mit erheblichen Unterschieden in der Expressionshöhe zwischen einzelnen Embryonen. Dabei zeigten Embryonen mit einer niedrigeren EGFP-Fluoreszenz im Vergleich zu Embryonen mit stärkerer EGFP-Fluoreszenz einen erheblich höheren Anteil an Zellkernuntergängen (kondensierte und fragmentierte Zellkerne). 34 Tage nach dem Transfer von EGFP-exprimierenden Embryonen auf Empfängertiere wurden drei lebende und morphologisch unauffällige Feten gewonnen. In Fibroblasten, die aus diesen Feten isoliert wurden, war das Reportergenkonstrukt, analog zur normalen Inaktivierung des endogenen OCT4-Gens in differenzierten Zellen, inaktiviert. In SCNT-Embryonen aus den Oct4-EGFP-transgenen Fibroblasten dieser zweiten Generation („second round“ SCNT) wurde das Reportergenkonstrukt erneut regelmäßig aktiviert wie in den SCNT-Embryonen vom Ausgangszellklon („first round“ SCNT). Die Herstellung stabil transfizierter boviner fetaler Fibroblasten mit einer unilokulären Integration des Oct4-EGFP-Reportergenkonstruktes stellt eine wichtige Basis für ein breites Spektrum experimenteller Ansätze zur Aufklärung grundlegender Mechanismen nach Kerntransfer beim Rind dar.

Calculations performed in consideration of a continuously increasing world population have revealed that animal production needs to be enhanced worldwide by at least 2 % each year so as to provide sufficient feed. Yet, effective growth promoting agents, in terms of in-feed antibiotics, have been completely banned throughout Europe due to the possible development and spread of multiresistance in bacteria. New efficient, safe and inexpensive feed additives are therefore needed in order to maintain or even further improve performance levels in animal husbandry. Based upon this information, rare earth elements have been considered as promising natural feed additive. Thus, this study was designed to bring together the current research on rare earths in order to analyze the data obtained and to facilitate the discussion of its relevance to agricultural utilization.

The term rare earth elements comprises the elements scandium (21), yttrium (39), lanthanum (57) and the 14 chemical elements following lanthanum (58 -71) called lanthanoids. Favoring the tripositive oxidation state, rare earths present a high affinity for ionic bonding, thus a large number of both organic and inorganic rare earth salts may be formed. Nevertheless, rare earths may also form complexes especially with chelating oxygen ligands. In nature, rare earths occur in multiple minerals, such as bastnaesite and monazite which are mainly used for industrial production. Today, rare earths are part of several daily used devices such as lighters, television sets and computers. Additionally they are found in medical technology, nuclear engineering, automobile industry, military devices and even in spacecraft. Furthermore, rare earth-containing drugs are used for the treatment of hyperphosphatemia in chronic renal failure patients and for burn treatment. Based upon their paramagnetic properties, rare earths, especially gadolinium, have also been arranged as contrast agents in magnetic resonance imaging and computer tomography. In the future, among other uses, rare earths might be involved in cancer therapy, treatment and prevention of osteoporosis and atherosclerosis as well as organ transplantation.

In China, rare earths have been successfully used at low concentrations as feed additives and fertilizers for decades. Yet, careful interpretation of Chinese data is recommended due to the fact that Chinese papers are often only available in native language and furthermore not up to standard with Western scientific research reports, hence lacking statistical treatment of data and details of experimental methods. However, in China, both yield increases and quality improvements were achieved in multiple plant species including cereals, fruits and vegetables after rare earth application. Recommended application rates vary with the crop species, the application technique (soil, foliar or seed dressing) as well as the timing.

As feed additives, rare earths were shown to improve body weight gain and feed conversion in nearly all categories of farming animals (chickens, pigs, ducks, cattle). Additionally, improvements in milk production in dairy cows, in egg production in laying hens and in output and survival rate of fish and egg hatching of shrimps were noticed. Feed additives used thereby predominantly contain light rare earths (La, Ce, Pr, Nd) but even though both organic (nitrates, chlorides etc.) and inorganic (ascorbates, citrates etc.) rare earth feed additives are commercially available, organic ones are claimed to provide better results.

Based on the effects reported in Chinese studies, experiments were initiated under Western conditions in order to investigate the action of rare earths on both plant and animal growth. Several Western feeding trials conducted on animals have been able to demonstrate significant performance enhancing effects after dietary rare earth application, while results obtained from experiments on the effects of rare earths on plant growth have been c