By David Cantrel
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 use of larger beef breeds and cattle with larger birth weights. 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.
The easiest and most practical method of inhibiting nighttime calving at present is by feeding cows at night; the physiological mechanism is unknown, but some hormonal effect may be involved. Rumen motility studies indicate the frequency of rumen contractions falls a few hours before parturition. Intraruminal pressure begins to fall in the last two weeks of gestation, with a more rapid decline during calving. It has been suggested that night feeding causes intraruminal pressures to rise at night and decline in the daytime.
In a Canadian study of 104 Hereford cows, 38.4 percent of a group fed at 8 a.m. and again at 3 p.m. delivered calves during the day.
A British study utilizing 162 cattle on four farms compared the percentages of calves born from 5 a.m. to 10 p.m. to cows fed at different times. When cattle were fed at 9 a.m., 57 percent of the calves were born during the day, versus 79 percent with feeding at 10 p.m. In field trials by cattlemen utilizing night feeding when 35 cows and heifers were fed once daily between 5 p.m. and 7 p.m., 74.5 percent of the calves were born between 5 a.m. and 5 p.m.
In the most convincing study to date, 1,331 cows on 15 farms in Iowa were fed once daily at dusk; 85 percent of the calves were born between 6 a.m. and 6 p.m. Whether cows were started on the night feeding the week before calving started in the herd, or two to three weeks earlier made no apparent difference in calving time.
On many large ranches, it is physically impossible to feed all of the cows after 5 p.m. In those instances, the ranch manager should plan to feed the mature cows earlier in the day, then feed the first calf heifers at dusk. The heifers, of course, are the group of females that are of greatest need of observation during the calving season.
Various means have been employed to effectively reduce animal loss at calving time. Skilled personnel should be available to render obstetric assistance and neonatal care to maximize percentage calf crop weaned in the cattle operation. Currently, evening feeding of cattle seems to be the most effective method of scheduling parturition so assistance can be available during daylight hours.
David Cantrell is the agriculture Extension educator for Pittsburg County. Contact him at 918-423-4120.