Adjusting the French dairy selection index (INEL) to a quota situation

Abstract

Selection of dairy cattle in France is carried out by means of an overall economic index for dairy traits (INEL). Weights for each trait were updated in 1993 to account for the occurrence of milk quotas and additional penalty when fat content is higher than a reference. The paper clarifies which rationale, assumptions and parameters were used, from both economic and genetic viewpoints, to examine potential of alternative solutions. Most important assumptions were that quotas and surfaces were constant over time and that economic margins accounted for fixed costs. The eventual solution (INEL 1993) gave no weight to fat yield per cow since INEL 1993 = 1.15 (protein yield (kg) + 3 protein content (g/kg) ). Selection according this index is expected to increase protein content and protein/fat ratio. Fat content is expected to decrease for the Holstein breed and to be almost constant for the Normande and Montbéliarde breeds .