Final answer:
The season when cows experience the highest percentage of abortions is winter due to nutritional challenges, stress, and increased risk of diseases.
Step-by-step explanation:
The season when cows experience the highest percentage of abortions is winter. This pattern is likely to be observed due to several factors. First, during winter, cows may face nutritional challenges as the availability of fresh pasture decreases. Second, cows may experience increased stress due to harsh weather conditions. Third, winter is also a time when certain diseases and infections, such as the bovine viral diarrhoea virus (BVDV), can pose a greater risk to pregnant cows.