Tolerance to Tick-Borne Diseases in Sheep: Highlights of a Twenty-Year Experience in a Mediterranean Environment

Abstract

The European landscape is characterised by a range of diverse farming systems. These relate not only to varied geographical environments and animal genetic resources, but also to different social and cultural contexts for farming and food production. This diversity is unique to Europe and, among the European countries, Italy is the home for a great variety of native breeds because of its complex orography and its long boot shape with very different climatic conditions from north to south. In the 1980’s, two of us moved from northern Italy to Apulia and soon came to appreciate the differences between the biotic and abiotic features of northern environment and the Apulian one. One of the most impressive differences were the enzootic tick borne diseases (TBD) and the related responses of the animals. As a consequence, much of our professional life has been devoted to the challenges posed by the diseases and to the study of the genetic peculiarities of native breeds both per se and in terms of their tolerance to TBD. This report is a review of the results obtained in a 20-year experience investigating the haematological features and tolerance to tick-borne diseases in Mediterranean native sheep breeds mainly Apulian native breeds compared to exotic breeds under various experimental conditions. In the wake of William Thomson (Lord Kelvin), a pioneer in thermodynamics and electricity, who said in 1891 that when you can measure what you are speaking about, and express it in numbers, you know something about it, but when you cannot measure it, your knowledge is of a meager and unsatisfactory kind, the central concept or research theme that guided all our research efforts stems from the notion that direct measurement of disease phenotypes and/or physiological features such as the hematological pattern provides a direct assay for measuring disease changes and the attitude of a genetic pool in facing disease. The work is concerned with the following main issues:  Haematological pattern of Apulian native sheep breeds  Breeds and tolerance to TBD in Apulia  Response to experimental anaemia  Response to Anaplasma ovis infection in experimentally infected sheep.