Greetings from Bozeman! March in Montana—some people are done calving, some are just getting started, and others are a month or more out yet. Making sure those calves get off to the best start possible is an important piece of our bottom line. Some sources cite an average rate of perinatal calf mortality of 3.5‐5.0%. Of the 29.3 million head of beef cows that calved in 2012, USDA estimates 1.0 ‐1.5 million head of calves were lost. What are some of the causes of these calf deaths?
In one large study summarizing over 83,000 calf births, 44% of calves that died had difficult births. In fact, calves born to cows with dystocia were 5 times more likely to die as calves born without assistance. Survival rates were lowest for calves that were relatively smaller for their genetic group, gender, and age of dam. Large calves only had increased mortality when born to first‐calf heifers, and calves born to first‐calf heifers were more susceptible to bad weather.
The vast majority of losses occur within1‐3 days after birth—one Fort Keogh study cites 68% of calves lost were lost during this time frame. Calf sickness issues such as scours and pneumonia can cause mortality also. Remember that the calf’s immune system starts with colostrum, and adequate and immediate intake are critical to set up the calf to fight off disease; this is called passive immunity. Colostrum quality is impacted by age of dam, nutritional status, and other factors. Consult your local veterinarian for information regarding diseases you should include in pre‐calving vaccination for your cow herd. In a large Nebraska study, calves with failure of passive immunity were twice as likely to be ill before weaning and 5 times more likely to die before weaning than calves with adequate passive immunity.
Good animal husbandry practices also are critical for reducing the incidence of neonatal calf sickness. Providing pairs with a clean, dry place goes a long way to support their continued health.