In Western Europe the transition from the Iron Age to the Roman period is the scene of a rapid economic and agro-pastoral evolution characterized in particular by a modification in the shape of the cattle. Understanding this phenomenon, its implementation mechanisms and development dynamics represents a major challenge in archaeozoology. In our study a local and regional approach of the evolution in cattle morphology is carried out first on the scale of the middle Seine valley, then of the northern Gaul. Its purpose is to observe and compare the evolution rates in domestic cattle between Middle La Tène and the fifth century AD, and with the help of a tight chronological and geographical grid, to estimate to what extent the shape of the cattle has been influenced by the indigenous cultures, the Roman economic pattern or even the environment. This osteometrical study is based on the Log Size Index method and on a measurement corpus of 12,969 bones collected on sites located on 117 communes in France (for most of them), Belgium, the Netherlands and Switzerland. The results we obtained show local specificities in terms of breeding methods and animal morphologies, observed on a very fine scale and taking place long before the Conquest. Moreover the growth patterns of the various herds happen to be different and to evolve under the impetus of the developing Roman economic pattern. This work thus points out an essential aspect of the agro-pastoral turmoil that took place in Gaul at the turning point of our era. The Roman pattern is not the cause of the morphological changes of the cattle, nor of the diversity in cattle shapes in Gaul, but it provokes a reshaping of the agricultural systems and a redefining of the breeding strategies which boost and completely change the cattle growth patterns.