By Eric Mousel, University of Minnesota Beef Team
With calving season here, I thought it might be helpful to examine five common myths surrounding calving time.
Consider how you might answer these long-held beliefs, and then read down to see what research suggests.
1. Myth: A first-calf heifer should be helped as soon as she begins laboring.
Stage one of the calving process is called pre-calving where she will start to get uncomfortable, muscles will begin to contract and she will display the signs she is about to go into heavy labor.
Pre-calving in first calf heifers can last as long as 8 hours. Once a heifer has reached stage two where heavy labor begins, membrane bubble protrusion or calf parts should be visibly observed within an hour and noticeable progress should be observed every subsequent hour.
If there is no observable progress, the heifer should be assisted. Furthermore, once an intervention has begun, if no discernable progress has been made through intervention in 30 minutes, a veterinarian should be called.
2. Myth: Cow outfits that feed at night will have more cows and heifers calve during the day.
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. Conversely, 79.6 percent of calves were born during the day when a group was fed at 11 a.m. and 9 p.m.
A British study utilizing 162 cows on four different farms compared the percentages of calves born from 5 a.m.-10 p.m. to cows fed at various times. When cattle were fed at 9 a.m., 57 percent of the calves were born during the day, vs. 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, when 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 or 2 to 3 weeks before calving made no difference in calving time.
3. Myth: Calf birthweights will be higher if the winter is really cold.
Research conducted at the University of Nebraska and Oklahoma State University have consistently shown that winter temperature does have a significant impact on calf birthweight; where colder winter temperatures during gestation does tend to result in heavier birthweight calves. The biological explanation of this phenomena is that during cold weather, blood circulation in the cow’s body is kept closer to the core of the animal to conserve heat, providing additional nutrition to the gestating calf resulting in a bigger calf at birth. Conversely, when temperatures are warmer, blood is circulated away from the core and closer to the outer surface tissues to help dissipate heat. Less blood at the core of the animal reduces nutrient flow to the gestating calf resulting in a smaller calf at birth.
4. Myth: Cows and heifers should be checked every two hours during the night.
Unless a cow or heifer is actively in labor, there is no evidence that checking two hours is needed. Largely, the visual observation interval used by herdsmen during the calving season depends upon the weather, ambient air temperature, snow cover, mud conditions and those types of things.
5. Myth: Calves get a better start if they are born inside.
Fact: It Depends
Generally speaking the opposite tends to be true; however, this is a very situation specific statement. Research indicates that calves born outside in the natural environment have a higher survival rate than calves born inside a building or shed.
Largely this is because it is very difficult to keep indoor facilities clean and the concentration of pathogens in an indoor facility tends to be much higher than outside.
That being said, extremely cold weather, muddy pen conditions, calving difficulties, etc. all contribute to good reasons to put cows inside to calve, and in those scenarios, the risks associated with calving indoors probably far outweigh the risks of calving out in the elements.
I hope this has been helpful in dispelling or confirming some frequently conversed myths concerning calving. Of course, you can always email me at firstname.lastname@example.org with your thoughts. Best of success in your 2017 calving season.