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Cold Winter Climates
Figure 5.17. Relationship between body condition score of cattle at calving and the time taken to return to heat. Cows in poorer condition take longer to cycle after calving, and the efect can be partially overcome by improving nutrition post-
calving. Source: Graham, J. 1982 Proc. Aust. Soc. Anim. Prod. 14, 309-12.
5.6.2. Failure to Produce a Live Calf
Calf mortality at birth can be a major production loss in beef breeding enterprises. Calves that die at, or
soon after birth can easily reach 10 of all calves born, particularly in heifers. Common causes of calf mortality
at birth are: • Small or low BCS heifers being unable to fully push
the calf out • High birth weight or broad shouldered calves
becoming stuck in the pelvis • Mis-presentation of calf during birth one or more
feet back, breech, etc. • Genetic disorders
• Failure of mother to accept and suckle the newborn. In many cases, diicult calving can have a signiicant
detrimental efect on the cow such as paralysis, uterine prolapse, infection, and in the worst cases, death.
Animals afected by this condition are obvious choices for removal from the breeding herd.
If necessary to maintain breeder numbers, cows who lost a calf through mis-presentation and are in good health
at joining time can be retained, as they are no more likely than any other cow to have a mis-presentation in
the future.
Selection of bulls with desirable genetics for calving ease will help reduce calf mortality at birth.
5.6.3. Failure to Raise a Calf to a Healthy Weaner
There are a range of factors that can lead to a cow not raising a healthy calf. These include;
• Failing to suckle the calf suiciently. This is often associated with poor teat or udder conformation or
breakdown and is a reason to consider culling the cow
• Low milk supply failing to provide suicient nutrition
Body Condition at Calving v. Time to First Heat
BCS Days to First Hea
t
Low Nutrition Post Calving High Nutrition Post Calving
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Beef Breeder MANUAL
to the calf. Often the cow is healthy and fat but the calf is poor, and this is a reason to consider culling
the cow • Death or injury to calf by misadventure. Like
mis-presentation at birth, misadventure has no genetic basis and herd productivity will not be
improved by removing afected cows. Under these circumstances, the cow can be retained if suicient
pasture is available to support her for a year before she breeds again
• Structural breakdown of the cow, reducing her ability to forage and maintain a productive body
condition score, and consequently being unable to supply suicient milk for her calf. These cows may
be culled. Determining when to cull a cow because of udder
faults is dependent on the impact the fault is having on production Fig. 5.18. Collapsed udders with ballooned
teats make drinking suicient milk diicult for the calf, and its growth may be afected. In such cases, the cow
should be culled. Less signiicant udder faults may not have immediate
production afects but udder and teat conformation are moderately heritable, so by selecting replacement
heifers only from dams with good teats and udders, the proportion of cows in the herd with well-structured
and productive udders increases substantially over successive generations. Cows with undesirably shaped
but functioning udders may be kept for producing feeder animals only. Otherwise, such animals should be
culled if adequate replacement breeders are available.
5.6.4. Cast-for-Age
