Effect of damage to the teat end on the experimental induction of mastitis in dry cows with Corynebacterium pyogenes.

The teat ends of 12 dry cows were contaminated with Corynebacterium pyogenes. To determine whether a pre-existing (an)aerobic bacterial infection of the udder was a predisposing factor for a C pyogenes mastitis they included infected and uninfected quarters. Anaerobic bacteria could not be found and mastitis was not induced. When the teats were contaminated with C pyogenes after the teat ends had been injured 30 of the quarters became infected, and anaerobic bacteria were demonstrated in many quarters.

[Oxytetracycline and oral herd treatment: a literature review]. / Oxytetracycline en orale koppelbehandeling: een literatuuroverzicht.

Pharmacotherapeutic, pharmacodynamic and pharmacokinetic aspects of oral mass medication with oxytetracycline (OTC) in pigs, calves and poultry are discussed in this review. Clinical studies with successful therapeutic results are scarce in literature; however, OTC is still frequently used for mass medication. Some practical advice to improve the bioavailability of OTC is given. This mainly concerns the reduction of the interaction between calcium ions and OTC. OTC may be useful for oral mass medication when applied as a prophylactic drug. Pharmacological studies are required in order to provide more knowledge about the efficacy of OTC-mass medication. Additional information can be acquired from the field by improving and extending the reciprocal co-operation between field veterinarians and diagnostic laboratories. This may lead to a more justified choice from the various possibilities of antimicrobial use in livestock.

Relationship Between Paratrichadorus sp. Density, and Growth of Wheat in Pots.

The effect of a Paratrichodorus sp. (close to P. tunisiensis) on the growth of wheat (Triticum durum Desf.) was investigated in pots containing different nematode densities and maintained in a growth chamber at 20 C for 40 days. The relation between fresh weight of tops and initial nematode density was according to the equation y = m + (1 - m)z(PT). This suggests a tolerance limit of 1.4 nematodes/cm(3) of soil under the conditions of the experiment; taking into account the effect of the great nematode mortality, it is estimated to be between 0.15 and 0.35 nematodes/cm(3) soil. Models of the growth of the plants and the multiplication of the nematodes (assuming a constant mortality of the nematodes in the absence of roots) which explain the relation between initial and tinal nematodes densities at initial densities greater than 1 nematode/cm(3) soil are described in an appendix. Sections of nematode infested roots showed disorganization of root structure clue to abnormal proliferation of lateral roots. Nematode feeding on the root cap and apical meristem caused cessation of root elongation and induced abnormal production of lateral root primordia.