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Fall Calving in Hot Weather                                                            The Midwest Cattleman · September 9, 2021 · P9

                                 By Mark Z. Johnson
         After a mild summer, the  fresh water is vital.  If calves
      heat continues just as fall  don’t have access to streams
      calving herds will begin see- or ponds and are therefore
      ing calves hit the ground.   dependent on water tanks,
      With  this  in  mind,  we  focus  make sure the tank sits low
      on the challenges faced in fall  enough and water levels in-
      calving herds in hot weather.   side are high enough for baby
      The primary challenge is the  calves to have access.
      impact high temperatures           Drovers
      have on newborn and young
         While fall calving is often
      easier  than calving in the
      winter and early spring,
      when      temperatures        are
      high it can create unhealthy
      conditions for calves.    The
      thermoneutral zone for a
      young calf is between 50 – 77
      degrees Fahrenheit.   Like-
      wise, cows calving in hot
      weather are more likely to
      become overheated and ex-
      hausted sooner in the pro-
      cess  than  a  cow  calving  in
      cooler temperatures.    This
      can lead to prolonged calving
      and more stress on both cow
      and calf.   When fall calving
      is taking place during high
      temperatures, beware of the
         •Heat stress is actually
      harder on young calves than
      cold stress.  When calves are
      heat stressed they lose appe-
      tite, eat less and are quicker
      to become dehydrated.
         •Newborn calves have an
      immature “thermostat”  and
      accordingly have more prob-
      lems regulating body tem-
      perature during weather ex-
         •Shade and fresh water
      are critical.   In addition to
      milk, calves need more fresh,
      cool water in hot weather to
      prevent dehydration, keep
      their    rumen      functioning
      correctly and maintaining
      health and appetite.
         •Effects of  heat stress on
      the dam can also negatively
      impact calves by reducing
      the transfer of passive immu-
      nity and subsequent weaning
         •Black hided calves are
      more susceptible to heat
      stress than calves of lighter
         Critical “Best  Practices”
      for fall calving herds include
      providing ample shade for
      calving cows and the young
      calves.  Shade and plenty of
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