Compact-calving systems are better suited to dual-purpose than dairy cow breeds, particularly when nutrient supply is limited
Résumé
This study aimed to explore adaptive trajectories of dairy and dual purpose breeds in contrasting
grazing-based feeding systems (FS). About 500 lactations were recorded at the INRA farm of Le Pinau-
Haras, equally distributed among breeds (Holstein: HO or Normande: NO) and FS (High or Low).
It was possible to study the different steps of the reproductive process by combining milk progesterone
information (three times a week) with intensive oestrous behaviour recording and pregnancy diagnosis
(ultrasonography). Holstein produced more milk (+2294 kg in the High FS, +1280 kg in the Low FS)
and lost more body condition than NO. Cows in the Low FS produced less and lost more body condition
than in the High FS. NO resumed ovarian activity earlier (-5 d) and showed a higher proportion of
normal cyclicity patterns (+22%) than HO. There was no difference in ovulation detection rates between
breeds or FS. The NO had a higher re-calving rate than HO (+19%). Feeding system was not associated
with cyclicity and re-calving rate. By limiting their milk yield, NO did not experience a severe negative
energy balance, unlike HO. This resulted in better reproductive performance for NO, suggestive of
greater suitability to a compact calving system.
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