An apparent nutritional lactational stress infertility in dairy herds

Abstract

Extract

Sir.—I refer to the paper by Day(1 Day, A. M. 1979. Induced termination of the calving season. N.Z. vet. J., 27: 22–29. [Taylor &; Francis Online], [Web of Science ®] , [Google Scholar]) on induction of parturition in a dairy herd. This report was read with a considerable degree of interest as it included results which are significantly different from those which we would have expected from extensive field experience in New Zealand and overseas.     

Letters to the editor

Sir;- Outbreaks of ovine abortions caused by Campylobacter fetus fetus (previously C. fetus intestinalis) occur sporadically in mimy areas of New Zealand. The devastating effects on some flocks have stimulated recent studies of the disease,^(1)(3)(7) and have also led to the commercial production of a single strain vaccine (Campylovexin; Wellcome N.Z. Ltd, Auckland). However, it has been shown that single strain C. Fetus vaccines do not protect against serologically distinct strains.⁽²⁾ Since at least two different serotypes of C. fetus fetus are present in New ZealandY) it is not surprising that the commercially available vaccine is only partially effective in some outbreaks.⁽⁷⁾     

Breeding unsoundness in the ram: The incidence of contributing conditions

Extract

Whenever disease is discussed in terms of beef production, in New Zealand it is certain to include infertility (brucellosis, vibriosis), metabolic diseases (bloat, staggers) and possibly exotic diseases and their prevention. On the rare occasion that parasitism is considered it tends somehow to find itself, along with selenium and other deficiency diseases, under a general heading of nutrition or management. This is probably because, while parasitism is still recognized as an infectious disease with clear clinical signs in severe cases, the tendency is to ignore its presence unless nutritional or management changes force a confrontation.     

Evaluation of a screening programme for identification of mannosidosis heterozygotes in angus cattle

Sir, — In recent years, much research effort has been directed towards identifying the cause of Ryegrass staggers (RGS). Many promising leads have been investigated, including studies of fungi in soil, ryegrass leaves, and dead leaf litter that could produce tremorgenic mycotoxins⁽³⁾. Several groups of fungi produce tremorgens⁽⁴⁾ which, when injected into sheep, produce symptoms similar to those in field outbreaks of RGS. However, under field conditions, populations of these fungi have not been shown to differ significantly between toxic and non-toxic pasture⁽⁷⁾ (McKenzie &; Byford, unpublished data).     

Swine dysentery

Extract

Sir, — We have just received a copy of the N.Z. Veterinary Journal for August, 1975 (Vol. 23, No.8) containing a most interesting communication by Pearce and Smith on the epidemiology, diagnosis and treatment of swine dysentery.     

Chemoprophylaxis of fascioliasis with triclabendazole

In a field experiment, moderate to heavy natural concomitant infections with immature and mature Fasciola hepatica were treated with triclabendazole at a dose rate of 10 mg/kg and an efficiency of 99.8% was achieved. Subsequent treatments of all susceptible farm animals at the same dose rate at intervals of eight to eleven weeks were carried out for 14 months; no patent infections could be detected in sheep and cattle during the whole period. Evidence is presented that pasture contamination with liver fluke was reduced to a negligible level for a further 12 months after the final treatment. It is suggested that, if regular treatments with triclabendazole are given within the pre-patent period of Fasciola hepatica infection for the whole season, the infection can be eradicated or reduced to such a low level that control of the disease could be maintained with less frequent strategic drenching for a considerable period.     

A goat mortality study in the southern North Island

A study was undertaken to indicate the importance of different causes of death in goats and to investigate the management factors which influence these problems. Over a 15 month period, 324 dead goats were received from 67 farms in the Horowhenua, Wairarapa, Wanganui and Wellington regions. Although a wide range of diseases was encountered in the study, the major causes of mortality could be divided into 4 groups: problems directly related to management, microbial diseases, nematode parasitism, and trace element related deficiencies and toxicities. The highest proportion of deaths related directly to management problems and included deaths from hypothermia, mismothering, premature birth, ruminal acidosis, pregnancy toxaemia, trauma, and plant and chemical toxicities. In larger flocks, microbial diseases including Pasteurella pneumonia and yersiniosis were major problems. Deaths from nematode parasitism were predominantly observed in goats 12 months of age and older. White muscle disease (selenium/vitamin E deficiency) was the major trace element deficiency causing death in goats.

The influence of factors including age of goat, flock size and management practices on the major causes of death are discussed.     

Protection by iron salts against sporidesmin intoxication in sheep

A number of iron compounds have been shown to protect sheep against the harmful effects of the facial eczema toxin, sporidesmin. Various salts were found to be effective; the oxidation state of the metal was not important although water-solubility did appear to be a prerequisite for prophylactic activity. The effect of iron salts was additive with that of zinc, and it is suggested that the protective action of these compounds results from their ability to inhibit the absorption of copper, consistent with the previously-proposed freeradical mechanism for sporidesmin toxicity.     

The amended insulin to glucose ratio and diagnosis of insulinoma in dogs

Amended insulin to glucose ratios were calculated from the concentrations of serum insulin and blood glucose measured concurrently during either a glucagon tolerance test or after feeding in healthy dogs. Values greater than 30 𝛍U/mg which are supportive of a diagnosis of insulinoma were obtained at certain times during the test period. Amended insulin to glucose ratios calculated from serum insulin and blood glucose concentrations obtained during a glucagon tolerance test and an oral glucose tolerance test on a dog with an insulinoma were less than 30 𝛍U/mg, or equivocal, at different times during the test period. This indicates that under some circumstances healthy dogs may have elevated amended insulin to glucose ratios, and dogs with insulinoma may have a normal amended insulin to glucose ratio. Care is essential for interpretation of amended insulin to glucose ratios, and a diagnosis of insulinoma using the ratio must be made in conjunction with appropriate clinical signs of hvnoglvcaemia.