I was going through some old files on my computer and came across this article that I feel is worth sharing again.
Calving season has started for many ranchers in the area, and many ranchers are supplementing their herd’s diet by feeding hay during the winter months.
This may give these producers some advantages when it comes to controlling what time of day their cattle will calve.
According to Glenn Selk, Beef Specialist, Oklahoma State University, it is generally accepted that adequate supervision at calving has a significant impact on reducing calf mortality.
Adequate supervision has been of increasing importance with the higher price of live calves at sale time. On most ranching operations, supervision of the first calf heifers will be best accomplished in daylight hours and the poorest observation takes place in the middle of the night.
Therefore, the easiest and most practical method of inhibiting nighttime calving at present is by feeding cows in the evening.
Rumen motility studies indicate the frequency of rumen contractions fall a few hours before parturition (giving birth).
Intra-ruminal pressure begins to fall in the last 2 weeks of gestation, with a more rapid decline during calving. It has been suggested that night feeding causes intra-ruminal pressures to rise at night and decline in the daytime.
The concept is called the Konefal method. A Canadian rancher, Gus Konefal reported his observations in the 1970’s. In a follow-up Canadian study of 104 Hereford cows, 38.4% of a group fed at 8:00 am and again at 3:00 pm delivered calves during the day, whereas 79.6% of a group fed at 11:00 am and 9:00 pm actually calved during daylight hours.
In a more convincing study, 1331 cows on 15 farms in Iowa were fed once daily at dusk, 85% of the calves were born between 6:00 am and 6:00 pm.
Kansas State University scientists recorded data on five consecutive years in a herd of spring calving crossbred cows at the Kansas State University Agricultural Research Center at Hays, Kansas.
They recorded the time of calving (to within the nearest one-half hour). Births that could not be estimated within an hour of occurrence were excluded.
Cows were fed forage sorghum hay daily between 4:00 and 6:00 pm. For statistical purposes, the day was divided into four-hour periods.
• Between 6 and 10 a.m., 34.23% of the calves were born;
• Between 10 a.m. and 2 p.m., 21.23% of the calves were born;
• Between 2 and 6 p.m., 29.83% of the calves were born;
• Between 6 and 10 p.m., 8.41% of the calves were born;
• Between 10 p.m. and 2 a.m., 4.4% of the calves were born;
• Between 2 a.m. and 6 a.m., 1.91% of the calves were born.
It is interesting to note that 85.28% of the calves were born between 6 a.m. and 6 p.m.
This is very similar to Iowa data when cows were fed at dusk. , Feeding the forage in the early evening hours undoubtedly influenced the percentage of cows calving in daylight hours. (Jaeger, Abstracts 2002 Western Section of American Society of Animal Science.)
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 a.m. and 6 p.m..
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.
Cumulatively, the results of these and other studies suggest that at the very least first calving heifers should be fed at dusk to increase the chance they will calve during daylight hours so that assistance can be provided if needed.
Time of feeding will also influence the calving time of cows as well, but as a rule, cows should require less assistance than heifers.
Source; Night time versus day time feeding influences time of calving, Glenn Selk, Oklahoma State University Extension