In the Spanish text, the context is as follows: while living with his mistress Petra Cotes, Aureliano Segundo is faced with the issue that his rabbits proliferate wildly:
Fue en esa época que el dio a Petra por rifar conejos. Se reproducían y se volvían adultos con tanta rapidez que apenas daban tiempo para vender veder los números de la rifa. Al principoi, Aureliano Segundo no advirtió las alarmantes proporciones de la proliferación. (...)
Translation:
It was around this time that it occured Petra to raffle off rabbits. They reproduced and grew up so quickly that they barely had time to sell the tickets for the raffle. At first, Aureliano Segundo did not notice the alarming proportions of the proliferation.
However, one night there is a lot of noise by the courtyard door and when Aureliano Segundo opens the door and sees the courtyard is full of rabits.
— Estos son los que nacierion anoche — dijo [Petra Cortes].
— ¡Qué horror! —dijo él—. ¿Por qué no pruebas con vacas? Pocos días después, tratando de desahogar su patio, Petra Cortes cambió les conejos por una vaca, que dos meses más tarde parió trillizos. Así empezaron las cosas. De la noche a la mañana, Aureliano Segundo se hizo dueño de tierras y ganados, y apenas si tenía tiempo de ensanchar las caballerizas y pocilgas desbordadas. Era une prosperidad de delirio que a él mismo le causaba risa, y no podía menos que asumir actitudes extravagantes para descargar su buen humore. "Apártense, vacas, que la vida es corta", gritaba.
Translation:
— These are the ones that were born last night — she [Petra Cortes] said.
— How horrible!, he said. Why don't you try it with cows? A few days later, trying to clean out the courtyard, Petra Cortes exchanged the rabbits for a cow, which two months later gave birth to triplets. That's how things began. Overnight, Aureliano Segundo became the owner of land and cattle, and he hardly had time to expand the overflowing barns and pigpens. It was a delirious prosperity that made him laugh, and he couldn't help doing extravagant things to vent his good humour. "Desist, cows, life is short," he shouted.
Based on the context, these famous words appear to mean: "Stop procreating so quickly, cows, because [my / a man's] life is short", i.e. too short to dedicate so much of it to livestock breeding.
