Management factors associated to the duration of postpartum anoestrus interval in Brown Swiss and Pirenaica beef cows

Abstract

A global analysis of several productive indicators and the postpartum anoestrous interval (PPI) of 549 beef cowswas carried out to determine the management factors related with postpartum ovarian reactivation in extensive mountainfarming systems. Multivariate statistic methods (Multiple Correspondence Analysis and Cluster Analysis) were usedto analyse the data due to the multifactorial nature of the processes involved. PPI was associated to four factors thatexplained 59% of the total inertia of the sample and were defined as follows: «Prepartum feeding level» (19% of theinertia), «Postpartum feeding level-Parity» (16.4%), «Suckling frequency» (13%) and «Calving difficulty» (10.5%).These factors were introduced into a Cluster Analysis that identified five types of cows: «Primiparous cows», «Twicedailysuckling», «Ad libitum suckling-Brown Swiss», «Autumn calving season» and «Spring calving season». Cowbreed was not related to PPI, although the Cluster Analysis associated the suckling-induced prolonged PPI with BrownSwiss animals. In Brown Swiss breed, PPI was longer in the spring than in the autumn due to nutritional differencesrather than to a seasonal effect. Autumn calving was better adapted to dry mountain conditions.