Written by Rachel Endecott, Beef Cattle Specialist
We’ve all experienced that middle‐of‐the‐night calving incident that sure would have been easier to manage if it had happened in the daylight. Some ranchers use an evening feeding strategy to shift more cows to calve during the day.
A case study comparing two sets of calving data with different feeding times illustrates this phenomenon well (Jaeger, et al. 2008. Professional Animal Scien st. 24:247). One group of cows was fed between 6 and 8 am (15 years of data, 1210 observations) and another group of cows was fed between 4 and 6 pm ( 5 years of data, 537 observations). Researchers divided the day into six, 4‐hour periods starting at 6 am and recorded the number of cows who calved during each 4‐hour period.
Cows who were fed in the morning had nearly equal distribution of cows calving during each period of the day. This resulted in nearly equal proportions of cows calving between 6 am and 6 pm (52%) and those calving between 6 pm and 6 am (48%).
Cows who were fed in the evening did not have an equal distribution of cows calving during each period of the day. In fact, 85% of cows calved between 6 am and 6 pm and only 15% calved between 6 pm and 6 am.
There are many factors in addition to timing of feeding that can override the timing of calving. Research in cattle and other species suggests that physical activity, daily variation in hormonal secretion, ambient temperature, or day length may play a role.
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