Défense de thèse de doctorat en médecine vétérinaire "sheep under high altitude conditions"

Study of sexual characteristics of male and female sheep under high altitude conditions in Colombia

Jury

Henry GRAJALES (Univ. nationale de Colombie), Mouad CHENTOUF (INRA, Tanger), Christian HANZEN (ULg), Jean-François BECKERS (ULg), Isabelle DONNAY (UCL), Benoît MUYLKENS, président (UNamur), Robert MANDIKI (UNamur), Marianne RAES (UNamur), Nathalie KIRSCHVINK, promoteur (UNamur)

Résumé

As a tropical country, Colombia has an important potential for ovine production; a sheep population of around one million animals is raised without or with very poor technical support and knowledge. There is a sort of management followed by tradition from one generation to another and it could be said that is ancestral. During recent years technical support has begun to be implemented but it is in a small part of the farms. There are some native breeds and the others foreign adapted whose ancestors arrived many years ago, like the first Corriedale, coming from Australia or Romney Marsh and Hampshire imported from Great Britain. Recently new breeds have been imported from different countries, including wool and meat breeds. There are some associations with around one thousand breeders as registered partners; most of them are considered as small breeders, because they have less than ten animals in total.

The geographical location of Colombia classifies it as a non-seasonal equatorial tropical country not affected by a seasonal regime; in general two types of climatic periods, dry and rainy periods. The geographical distribution of two types of sheep depends on temperature: wool sheep are found at high altitudes and low temperatures and hair sheep are found at lower altitude and with an average temperature that is considerably higher (González et al., 2011).

Appropriate knowledge about reproduction physiology could be a clue to trigger the development of production of meat and wool sheep in high and low altitude regions. Knowing exactly how the most frequently used breeds, adapted foreign and native, behave under absence of seasonality but particular environmental conditions are part of the knowledge able to improve ovine production.

The research presented here is part of a North-South cooperation project between the University of Namur (Belgium) and the National University of Colombia (site of Bogota). The project aims at improving knowledge about reproductive aspects of sheep production in the high altitude regions of Colombia; first by developing a sheep investigation center under the direction of the National University of Bogota and secondly by performing field investigations in pilot farms. This thesis aims at characterizing reproduction physiology of four wool breeds, one native and three foreign adapted breeds raised under high altitude conditions.

For this purpose, four studies were performed:

Characterization of onset of puberty and onset of ovarian regularity in female Colombian Creole, Romney Marsh, Corriedale and Hampshire lambs

Characterization of onset of puberty and maturity in male Colombian Creole, Romney Marsh, Corriedale and Hampshire lambs

Characterization of reproductive ability in Colombian Creole, Romney Marsh, Corriedale and Hampshire adult ewes

Characterization of reproductive ability in Colombian Creole, Romney Marsh, Corriedale and Hampshire adult rams

La défense est publique

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