What Is Body Condition Score (BCS)
First, let us define what is body condition scoring (BCS). BCS is a method of evaluating fatness of thinness in cows according to a 5 point scale. The score can be used to fine-tuned dairy herd nutrition and health.
Body condition plays a big role in the productivity, reproduction, health and longevity of dairy cows. By observing the thinness and fatness of a cow, we are able to tell if there is any sort of nutritional deficiencies, health problems or improper herd management. BCS is a good way to troubleshoot problems and improve the health, longevity and the productivity of the dairy herd.
For example, if the cow is fat, this may be due to poor nutrition or reproduction management. A fat cow is also more susceptible to metabolic problems and infections and therefore will have more difficulty at and after calving. Usually, over-conditioning occurs during the last 3 - 4 months of the lactation cycle when the milk production level has decreased, but the dietary energy and total nutrient levels have not been reduced accordingly.
When the cow is too thin on the other hand, this will cause lower production and milk fat levels. This is primarily due to insufficient energy and protein reserves to maintain the milk production level. Thin cows usually do not show heat or conceive until they start to regain, or at least maintain their body weight. Special care must be taken when feeding these animals in order to maintain production while increasing the body reserves.
Regardless of the farming system or cow genetics, in general, milk production is optimised when mature cows calve between BCS 5.0 - 6.0. However, increasing BCS over 5.0 in mature cows and 5.5 in first and second calvers is not recommended. Overly high BCS will reduce production benefits and increase the risk of metabolic health disorder. Therefore, the idea BCS targets are a compromise between wanting cows with sufficient energy reserves for milk production while simultaneously not wanting the cow to be so fat that it affects the cow's health.
Body Condition Scoring Scale
The body condition scoring in dairy cattle is a visual and tactile evaluation of body fat reserves using a 5-point scale with an increment of 0.25-point where a score of 1 denotes a very thin cow while a score of 5 denotes a very fat cow and 3 is an average body condition.
Relationship between body condition to dry matter intake, milk production, reproduction and health
Figure below shows the relationship between body condition and the production cycle of dairy cows.
Dry Matter Intake
There is a negative correlation between body condition score (BCS) and dry matter intake. What this basically means is that cows with high BCS before calving will usually have a lower feed intake in the critical transition period around the time of calving. This could cause the loss of body condition and deepen the negative energy balance cows experience after calving.
In general, BCS and milk production curves are mirror image. Cows producing the most milk experience the greatest change in body condition and the lowest BCS in early lactation. With that being said, BCS and milk production does not have a linear relationship. Cows with a BCS or 3.0 or 3.5 at calving produce more milk than those that have a lower or higher score. One reason this could happen is because there is an increase in energy available from body stores up to a BCS of 3.5 and negative effects of BCS on dry matter intake after that point. It is expected that the BCS of cows will decrease in the first 60 days of calving. It is recommended that the cows lose no more than 0.5 - 1.0 point in score.
Energy balance plays a huge role in the reproductive performance of a dairy cow. The current energy status as well as the past status will influence the cow's ability to reproduce. Greater change in BCS between calving and first breeding and lower BCS at the first breeding consistently are associated with reduced pregnancy rates. With that being said, studies have showed diet changes were not able to overcome BCS loss in early lactation. Therefore, the best way to control BCS at breeding is to manage BCS at calving.
The body condition of dairy cattle during calving and in early lactation is associated with the incidence of important metabolic disorders in dairy cows, particularly ketosis. It has been shown that the risk of ketosis is about 2 times greater for cows calving at BCS > 3.5 compared to those calving at BCS 3.25. The rate of both clinical as well as subclinical ketosis is also higher in dairy cattle with higher BCS. One report showed that cows with BCS < 2.5 or > 3.5 were 13% or 30% respectively more likely to suffer from milk fever compared to cows with BCS of 3.0. Cows with high BCS tend to mobilise more energy from body reserves. This will reduce dry matter intake while increasing the milk production. Both these factors contribute to metabolic disease risk.
When to Condition Score
A management programme that allows time for any corrective action to be taken is essential
Scoring should be done:
1. Drying off (7-8 weeks pre-calving)
2. Pre-calving (3 weeks pre-calving)
Ideally, for dairy cows, the score at drying off should be close to that for calving and ideally not more than half a score above. This "fit not fat" condition would be able to help avoid having to slim cows off as this leads to metabolic disorders.
As for maiden heifers, special attention is required as they are "nutritionally" on a knife edge. A good example would be the loss of one condition score equates to 15 kg liveweight in a heifer, versus 30kg in an adult cow. This is also evident during mid lactation phase. Heifers need to gain 90 kg for one condition score versus 60 kg in an adult cow.
It has been demonstrated that a cow's body condition is associated with her overall performance and that body condition scoring is a valuable tool in dairy herd management. In scoring a dairy cattle, the tail head and loin are the major areas to evaluate. Target scores help determine what sort of condition to aim for during different phases of lactation. If done in a right way, BCS can greatly improve the dairy herd nutrition, health and production of milk. Proper conditioning can be accomplished by body condition scoring by paying very careful attention to the animals, ensuring they have their nutrient needs met but not exceeded.