Reproductive parameters of suckling cows' herds in Alentejo

Abstract

The area of permanent pasture has been increasing in Alentejo representing nowadays over 1.15 million ha, of which about 700 000 ha under cover of cork and holm oaks, where more than 80% are considered poor. Cattle, whose population has increased steadily over the past 20 years, are the dominant zootechnical species, constituting 54.9% of the population in terms of livestock units (INE, 2011).

The study that took place between 2000 and 2008 refers to the reproductive performance of suckler cows from 30 farms with areas between 100 and 800 ha, with montado. On these farms more than 50% of births were concentrated between January and April, a percentage that has increased during the study. Calving interval (IP) was more favorable for cows aged between 5.5 and 7.5 years (mean 427 days), increased to an average of 440 days in cows older than 8 years and reached an average of more than 478 days in primiparous cows younger than 3.5 years.

The lowest average of IP (419 days) was recorded for cows that calved in February.

The IP for cows calving on this period averaged 427 days when the following spring was wet, or 451 days in the case of a drier spring and were longer (mean 488 days) in the driest year, September 2004 to August 2005.

Suckler cows from farms in the Alentejo Litoral presented a lower mean IP (417 days), which decreased to an average of 398 days in the case of cows calving in February.