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This is further helped by the use of bulls selected specially for use with heifers, and which produce lower
birth weight calves. Heifers that calve early in the calving period are also less likely to have dystocia issues as the
shorter gestation period tends to reduce the size of the calf.
First calving heifers must be fed suiciently well to ensure that they milk well and support good calf growth, but
also to enable the mother to continue their own growth and development. This involves feeding to at least a level
that enables the heifer to maintain liveweight during the lactation period, and particularly between calving and re-
mating to ensure that she resumes cycling quickly, and is able to achieve a second pregnancy in the shortest
timeframe. If heifers are not achieving target condition scores
they must be relocated to better quality and quantity of pasture, supplementary feed, or the calves weaned
early.
5.8. Relationship Between Feeding
and Breeding
The level of nutrition is one of the major factors inluencing both male and female cattle fertility. The
nutritional status of the animal is relected by body weight and body condition. Reproductive performance
is closely related to live weight and body condition at the time of mating, thus weighing and body condition
scoring are an essential part of any breeding program, and cattle should be evaluated on a regular basis.
For heifers that have not yet calved, an adequate quantity of feed is essential to maintain these non-
lactating animals in a condition score of at least 3.0. This will increase fertility and they will be more likely to breed
and produce a calf. Improving the body condition score of cows from 3.0 to 4.0 will increase pregnancy rates by
up to 20 and conception will occur in a shorter period post-calving Figs. 4.1, 5.17.
Lactating cows that have calves at foot should be returned to a condition score of 3.0 to enable satisfactory
pregnancy rates to occur and for the cow to rebreed in the minimum timeframe. To ensure this, lactating
cows require a higher level of nutrition than is required for non-lactating cows to compensate for the energy
demands of the suckling calf. It is essential that cows re-breed quickly so that they can
produce a calf each year. This will not happen if they do not get enough good quality feed. At conception,
the BCS should be at least 3.0. Body condition may subsequently be managed to rise up to 4.0 by calving;
to allow the cow to produce adequate milk for the calf and become pregnant again.
Body condition during pregnancy also has a signiicant efect on calving and the resulting calf. A best practice
management program will ensure that the body condition of pregnant cows is monitored from 100
days before they are due and until calving the third trimester, so that body condition can be managed to
an ideal range using nutrition.
Consequences of cows that are below an ideal body condition during the third trimester of pregnancy
include;
• A higher chance of abortions • Poor reproductive cycling and re-conception
• Longer intervals between calves • Less colostrum production and poorer calf immunity
• Poor milk production and weaker calves. Over-fat cows, as indicated by a BCS at or approaching
5.0, sufer similar problems to under-conditioned cows, and tend to have larger calves and higher rates of calving
diiculty dystocia.
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6.1. Calf Processing
