Written by Glenn Selk, Oklahoma State University
Research and ranch experience has shown
What about the situation where large round bales of hay are being fed to the cows and heifers? If the cows have unrestricted access to the hay around the clock, then the best method of influencing the time of calving is via the time of day that the supplement is being fed. At Oklahoma State University, the switch from supplement feeding in daytime to late afternoon/early evening feeding encouraged 72% of the cows to calve between 6 AM and 6 PM. These cows had 24/7 access to large round bales of grass hay. Before the change was made, when supplement was fed during the morning hours, the ratio of night time versus day time calving was nearly even, with half of the calves born at night and half during the day.
Some ranchers (usually with small herds) have reported success controlling access to the large round bales. The hay is fed within a small enclosed pasture or lot near a larger pasture where the cows graze during the day. In the evening, the gate to the area where the hay is placed is opened and the cows are allowed to enter and consume hay during the night. The next morning, they are moved back to the daytime pasture to graze until the following evening. In this manner, the nighttime feeding is accomplished with hay or silage only.
Whatever method fits your operation should be utilized. The advantages of heifers/cows being observed with daylight during calving is obvious. Also during winter months, baby calves born in the warmer part of the day with radiant heat from the sun to reduce cold stress, have a better chance for early colostrum consumption and therefore survival.