Character process model for semen volume in AI rams: evaluation of correlation structures for long and short-term environmental effects Ingrid David, Loys Bodin, Gilles Lagriffoul, Eduardo Manfredi and Christèle Robert-Granié Genet. Sel. Evol., 39 1 (2007) 55-71 DOI: 10.1051/gse:2006033