Weighing and Condition Scoring Replacement Heifers and Dairy Cows (AG0505)

John Moran, Kyabram
Updated: February 2006

This Agriculture Note describes the importance of monitoring growth of heifers to profitable dairy farming operations. It includes condition scoring diagrams.

Monitoring growth

Well grown heifers are important to profitable dairy farming. Most dairy farmers and advisers can recognise whether heifers are in good or poor condition, but few can judge whether heifers have achieved target live weights for their particular age.

Target weights for age can be used as guides as to the level of feeding management and are early indicators of problem areas that require attention. They are presented in an accompanying Agriculture Note “Heifer nutrition from weaning to first calving”. These target weights are often used as the average rather than the minimum, meaning that many heifers are still too small. For minimum joining weights, the average should be 30 to 50 kg above the target.

The best way to monitor the success of feeding programmes for heifers is to regularly weigh them, at least every 3 months. The routine use of chest girth tapes is not recommended as they invariably overestimate live weight. Most commercially available “weigh tapes” were developed from live weight/chest girth relationships using beef cattle, which have more compact hindquarters than dairy heifers. Weigh tapes have been found to overestimate live weight by up to 40 kg in 6 month old Friesian heifers.

Cattle scales

Cattle scales can be either mechanical or electronic. Electronic scales have digital readouts that are easier to read than the clock face readout on mechanical scales.
Electronic scales can cost from $1000 to $2500. The more expensive scales allow the storing of data in the unit which can be transferred directly to a computer, thereby eliminating human error in data capture. They can also allow for the storage of previous weights in the readout unit, to instantaneously show live weight changes up to that particular weighing date.

Some herd improvement organisations have cattle scales for hire. Alternatively, several farmers could form a syndicate to share the purchase cost. Individual farmers could then install their own platform, to be permanently located in cattle yards, with the same readout unit being moved from farm to farm.

Table 1. A list of suppliers of cattle scales

Heifers should be weighed at the same time each day, as this minimises the variation in gut fill arising from patterns of grazing throughout the day. It is preferable that animals are not offered water until after they are weighed, as this also minimises any variations in live weight.

Cattle scales can have many roles on dairy farms. In addition to monitoring heifer growth, they can be used to calculate drenching rates for stock, check live weight changes in milking cows during different stages of lactation or even weighing round bales of hay or silage.

Measuring wither height

Wither height is a good measure of bone growth in heifers and therefore frame size. Frame size can influence the area between the pelvic bones, and hence the ease of calving. It can also influence abdominal capacity and hence appetite of milking cows. Wither height is measured as the highest point on the heifer’s shoulder, immediately above the front legs.

Animals should be standing quietly, but not with their head in a head bail, as this alters their natural stance. If there is a platform in the cattle crush, the wither height stick should be carefully positioned to measure the animals' height where it is actually standing, and not from the cement or dirt floor of the cattle yards. Target wither heights are presented in an accompanying Agriculture Note “Heifer nutrition from weaning to first calving”.

Body condition of cows and heifers

Benefits of improving body condition

Cows in early lactation cannot eat enough feed to support the milk production of which they are genetically capable. What they do is to draw on their body fat reserves as an additional energy source to support extra production.

Research at Ellinbank some years ago showed that, if the body condition of cows in the condition range 3-6 is improved by one score by the time of calving, the likely benefits are:

• an extra 10 kg of milk fat over the following lactation
• an increase in milk fat test of about 0.3% during the first five weeks of lactation
• a reduction of six days in the interval from calving to first oestrus.

The optimum condition for cows and heifers at calving is score 5-6. The increased incidence of metabolic and calving disorders associated with cows at scores greater than this would offset any possible production benefits.

Feed required to improve cow condition

When it comes to putting on a condition score, the number of kg of live weight in each additional condition score for mature cows vary depending on the breed:

Weight gain obviously requires energy, but the amount of extra energy that is needed depends on whether the cows are still milking or not. Research has shown that cows use feed more efficiently while they are still milking than when they are dry.

For every kg of weight gained during late lactation, we currently estimate that 44 MJ of metabolisable energy are required. For every kg of weight gained when the cows are dry, about 57 MJ of energy are required.

To put half a condition score on a Friesian cow in late lactation, 21 kg of live weight need to be gained. This requires an additional 44 MJ x 21 kg = 924 MJ of metabolisable energy above the energy required for maintenance, milk production and pregnancy. To improve body condition by half a condition score when the cows are dry requires an additional 57 MJ x 21 kg = 1197 MJ above maintenance and pregnancy.

It should be noted, however, that it is difficult to control liveweight gain during lactation because the extra energy provided will be partitioned between milk yield and body condition, and this can be unpredictable.

Feeds differ in their ability to improve a cow's body condition. The higher the energy concentration of a feed, the more easily animals will improve their condition. For example, cereal grains will be more efficiently used to improve body condition than will pasture hay or silage, which are much lower in energy.

In addition, farmers are generally attempting to improve cow condition in autumn and winter in Victoria because of the seasonality of calving. This coincides with cold and wet weather conditions when animals naturally need more energy. This extra energy for maintenance is included in the above estimates.

The time required to improve the condition of cows will depend on the quality of the diet. The greater the energy concentration, the shorter the time, because cows have the ability to eat greater quantities of high energy feeds compared to low energy feeds. However, 4-5 weeks is probably a realistic minimum period to put on one condition score regardless of the feed being offered. It is also important to note that in the month before calving, it will be difficult to make any improvements in condition because the calf is growing so rapidly at this time.

To get all cows into the desirable condition at calving, it may often be necessary to give preferential treatment to some of them. For example, because first calvers need extra feed for growth, and do not compete well with older stock for limited feed supplies, they should be managed as a separate group. Very high producers may also be the cows in the worst condition and they could require preferential treatment as well.

The aim of any system of feeding cows should be to ensure that all cows calve in the condition that a farmer considers to be most suitable to his/her farm situation. While various practical and economic factors will affect a farmer's decision, the underlying principle is that the higher the condition score at calving, the greater the body fat reserves available to improve production in early lactation.

The profitability of improving cow condition depends on the cost of supplying extra feed, the return on the milk produced, the body condition of the cows, and whether the cows are in late lactation or dry. In view of the variability of these factors, an evaluation of the profitability of various feeding strategies should be discussed with the dairy extension officer in your area.

Scoring the body condition of dairy cows

Everyone has different ideas of cow condition and use different terms to describe it. To overcome this language problem, a scale of eight body condition scores has been developed to visually assess cow condition.

Scoring is in numbers from 1 to 8 and the range is from an emaciated condition (score 1) through to very fat (score 8). The condition scoring system is mainly based on observations of different amounts of fat around the base of the tail and over the hips and back of cows.

The use of this condition scoring system enables dairy farmers to make an assessment of the condition of their cows. After deciding the most suitable condition for their cows at calving, they can then formulate the feeding management to achieve this condition. This ensures that feed is used efficiently and high production per cow is achieved.
Although these photographs are for Jersey cows, they can be used to visually assess body condition score with Fresian cows as well.

THE INDICATORS

Amount of fat on backbone, hips and ribs

Amount of fat around base of tail and prominence of pin bones

SCORE 1 No flesh over the skeleton. Backbone is sharp and is a very prominent ridge. It is very easy to feel individual lumbar vertebrae. The shape of each individual short rib can easily be felt.
SCORE 2 Area around base of tail is deeply sunken in. Backbone is a prominent ridge. Hips and pins are very prominent. The shape of the ends of the short ribs can be easily felt. It is easy to feel between the tops of the short ribs.
SCORE 3 Area around base of tail is sunken in. Backbone is a prominent ridge. Hips and pins are prominent. The ends of the short ribs can be easily felt. It is possible to feel between the tops of the short ribs with pressure.
SCORE 4 Area around base of tail is only slightly sunken in. Backbone is a raised rounded ridge. Slight fat covering over pins, hips and short ribs. The ends of the short ribs can be felt and are rounded. It is not possible to feel between the tops of the short ribs.
SCORE 5 Area around base of tail is almost filled out. Backbone is a rounded ridge. Even fat covering over pins, hips and short ribs. Only some of the short rib ends can be felt. It is not possible to feel between the tops of the short ribs.
SCORE 6 Area around base of tail is filled out. Back is rounded across the loins. Cannot feel the ends of the short ribs or between the tops of the short ribs. Tail head is still prominent.
SCORE 7 Back is flat across the loin. Backbone can only be felt by pressing down firmly. Cannot feel short ribs. Hips are well rounded. Tail head is a rounded ridge with some folds of fat either side.
SCORE 8 Backbone is covered by a thick layer of fat and cannot be felt. Cannot feel short ribs. Hips are no longer obvious. Tail head has large folds of fat on either side.

Acknowledgement

This note was written with the assistance of Richard Stockdale.

The previous version of this note was published in December 2001.