Page 226 - The Welfare of Cattle

ranGe beef CoW and CaLf heaLth and WeLfare 203

birth. For mature cows on larger ranches, the percentage of calves lost during delivery is less than
2%, and again, on smaller ranches more calves die, at approximately 3%. Most likely, the difference
in success between such ranches is the amount of observation and assistance provided by ranch
personnel.
Some calves suffering from difficult delivery will survive for a short while but are still suffering
the consequences of the birthing trauma and may die within the first 24–48 hours. Again, human
intervention can substantially impact survival rates. Ranch personnel can provide the calf with
supplemental oxygen, warmth, protection from the elements, and assure that the calf is obtaining
colostrum and then milk from the dam. Although healthy newborn calves are typically very robust
and can survive in pretty harsh weather conditions, there is a limit to their survivability. Calves suf-
fering from dystocia are far more susceptible to the adverse effects of bad weather. Of all calves that
die within the first 3 weeks after birth, approximately 50% of deaths are attributable to birth-related
problems or weather-related causes.
Frostbite can occur in newborn calves less than 3 weeks old during bouts of extreme cold.
Frostbite will most commonly affect ears and tail because these extremities have very low blood
flow when calves are chilled. If only the ears and tail are affected, calves will lose the tips of these
body parts, but typically survive without further liability. Sometimes feet are also affected, and
these calves have to be euthanized. In more extreme cold, some calves will die, and calves affected
by dystocia are particularly at risk, as described above.
There are numerous management tactics used to decrease the likelihood and the impact of
dystocia. Replacement heifers are managed and fed for optimal growth to assure they are appropri-
ately sized and prepared for delivery of calves. Heifers are bred to calving ease bulls to minimize
the likelihood of excessively sized calves at birth. Heifers near the time of delivery are monitored
for impending delivery and assisted when needed. Newborn calves are monitored for vitality and
managed more intensively if they appear compromised by the delivery. Most ranches have a calv-
ing facility where a limited number of compromised dams and calves can be temporarily protected
from extreme weather. Breeding management that produces a discreet calving season makes all of
these objectives easier to accomplish because all the cattle are in similar stages of gestation and calf
delivery at approximately the same time so that personnel effort can be focused.
The first 3 weeks after birth are referred to as the calf neonatal period. The primary challenges
after the first 48 hours are infectious conditions, and the most common are gastrointestinal infections
with viruses or protozoal agents. These cause diarrhea and loss of body fluid and electrolytes, which
in turn make the calf very sick and these problems can potentially be lethal. If they are identified
early, which requires careful observation and oversight by ranch personnel, calves can be success-
fully treated. Bacterial infections of the gastrointestinal tract also occur and these can be more
life-threatening because these enteric bacterial pathogens such as Escherichia coli, Salmonella, or
Clostridia produce toxins and are capable of invading and damaging other organ systems. On most
ranches, these infections occur at a lower frequency than in other cattle management systems. Ranch
management can limit the occurrence and spread of enteric disease agents in calves by changing
the location of calving dams or of cow/calf pairs during the calving season to limit the amount of
contamination of the environment, and thus the exposure of calves to the infectious agents.
After the first 3 weeks, calves are still susceptible to a variety of infectious challenges, but dur-
ing this period the most likely infections affect the respiratory tract. Susceptibility to respiratory
infections continues to be the primary disease challenge through weaning and beyond, including
growing stocker and feedlot calves.
Looking at the entire time period from birth through weaning, disease and death loss occur
with decreasing frequency over time. On western ranches, 2%–3% of all calves will die during or
at delivery. Of the calves born alive, approximately 4% of calves die between birth and weaning.
A third of these losses of live-born calves occur during the first 24 hours, another third of the losses
occur over the 3 weeks of the neonatal period, and the remaining third die between 3 weeks and