Monitoring and managing dry cow body condition scores and setting an ideal body condition target for the herd is critical to minimise the incidence of metabolic disease, say transition specialists Premier Nutrition.

As a result of analysis of their 2018 and 2019 TMS transition cow data, the company has identified definite trends that fat cows are more at risk of milk fever and LDAs, whilst thin cows suffer more retained placentas and metritis.

In addition, the data shows that calf mortality – where the calf dies within 24 hours of birth – is more prevalent in thinner dry cows.  However, this is reversed in heifers, and heavier animals are at greater risk.

Ideal body condition score

According to Premier Nutrition’s Dr Andrew Pine, for optimum transition performance his recommendation is to target a dry cow body condition score of between 3 – 3.25 and avoid excessive body condition score change as they become fresh cows. 

“Over 30% of dry cows have a poor body condition score as they approach calving and are more likely to suffer transition issues according to our data”, he commented. 

“This body condition measure allows us to gauge the cow’s ability to deal with the metabolic stresses at calving, and the analysis has proven that deviation from the ideal is directly linked to secondary issues such as ketosis, mastitis and delayed fertility, so it’s crucial to target a 3 – 3.25 body condition score as far as possible.”

Over-conditioned cows

With milk fever incidences particularly, the data reveals that as dry cow body condition scores rise, on average the incidence of milk fever also rises with fatter cows seeing a substantial rise in risk.  For example, cows with a BCS above 3.25 who then lose more than 0.25 condition points post-calving are twice as likely to suffer milk fever incidence as her thinner contemporaries. 

The LDA risk also increases substantially with fatter cows, warns Dr Pine.  

“At any condition score, milk fever and LDAs are an issue, but the risk is significantly higher in fatter cows with negative consequences stretching far into the next lactation.”

Interestingly, the study found the incidence of twins was greater in thinner cows, although the company challenges whether twins are making cows thin or do thin cows have a greater chance of holding twins?  Regardless, twins are a challenge to the industry but, because of the condition score link, it poses a major test with regard to the metabolic stress the cow is facing.

Production implications

The impacts of failing to manage dry cow body condition scores and fresh cow body condition losses are enormous, advises Dr Pine.  The data also highlights how undesirable body condition scores and subsequent metabolic disease incidences significantly impact production, including a compromise in milk yield, milk solids percentage and milk solid yields.

“Our data showed that 84% of transition cows experience some form of transition issue. As you can see in Table 1, milk yield from unaffected cows averaged 39.7 litres in the study, but almost every single transition issue caused a reduction in first test milk production results.  Some metabolic problems such as LDAs and ketosis are having major impacts, taking average production down to 30 and 26 litres respectively”, he warned.

Table 1: Average milk yield for animals affected by metabolic disease, lameness & mastitis compared to unaffected animals (blue line indicates average milk yield, all animals)

Table 1: Average milk yield for animals affected by metabolic disease, lameness & mastitis compared to unaffected animals (blue line indicates average milk yield, all animals)

For farms on cheese contracts, lower body condition scores showed a substantial impact on milk protein percent.  Cows with a score of 3.25 – 3.5 had solid yields (fat & protein) on average of 3.1kgs according to the data.  However, cows with a body condition score of 2.5 – 2.75 were yielding 2.8kgs; 300g less solids.  On a contract demanding solids, these cows are costing the farm money in terms of both milk and solid yields.

What is the overall financial implication of poor body condition management?  For a herd of 250 cows over a one-year period, the study showed the cost of transition when achieving the desirable BCS range is £83,500.  However, for fatter or thinner cows at undesirable BCS ranges, this cost increases to £93,500; that’s an extra £10,000 per year or equating to losses of between 0.35 to 0.4 pence per litre on every litre leaving the farm.

Recommendations

Recommendations from the company are clear and include:

  • Target a 3 – 3.25 body condition score on average to:

-  Avoid excessive BCS change

-  Avoid increased metabolic problems

-  Avoid reduced milk production

-  Avoid reduced fertility success

  • Aim for less than 20% of cows outside of this target BCS
  • If more than 20% of cows are outside target BCS:

-  Consider late lactation nutrition

-  Consider a ‘fat club’ if suitable/available conditions on farm

-  Focus on transition nutrition and management – key nutrients & technologies

And the company are already looking at how the data can help them to understand transition further.  For example, analysis to determine whether there needs to be a differential body condition score for different levels of production or different environmental conditions; that analysis has already begun.

TMS is a transition management system where dry and fresh cows are independently assessed on a large series of parameters each month by Premier Nutrition Assessors.  The data in this study comprised of 68,000 dry cows, 86,000 fresh cows (predominantly black and whites) and more than 2.7 million data points.