Other Management Articles
- Building A Herd of High-Producing, Healthy Cows with Low Involuntary Culling
- Culling Heifers: When and Why and the Impact on Herd Economics
- Economics Matter in Culling Decisions
- What is an ideal BCS at calving?
- Facts about Somatic Cell Counts
- First Layer of Defense Against Mastitis
- The When and Why of Milking Procedures
- Are Mastitis Vaccines a “Cure All”?
- Growing Heifers to Be Your Best Cows
- A Look in the Mirror
- Fertility Potential: The Bull + The Cow + The Inseminator + The Environment
A traditional way of considering body condition around the time of calving was ensuring cows had enough reserve to buffer their way to high production. With new research, the thinking on this has changed in recent years. Dairy cattle are typically in a negative energy balance in early lactation, the energy and protein needed to support maintenance and production is more than they can consume. The net result of this is using their body reserves, causing a loss of body condition. Low body condition at breeding is associated with lower conception. Building a cow that starts with a bit of extra reserve seemed like a good management decision. In papers from around 2001, recommendations for Body Condition Score (BCS) at calving were 3.25 to 3.75, with a goal to limit changes in BCS by less than 1 point. A change of about 0.75 BCS loss was deemed as ideal.
But is it ideal? Recently there have been studies looking at BCS at calving, weight loss after calving, and their impact on reproduction. Animals that lost more weight post calving had poorer reproduction. Several research groups have compared cows that lost >0.5 BCS, cows that maintained between 0 and 0.5 loss, and animals that gained weight. With very little difference in milk production, there was a significant difference in first service conception, with a doubling of the conception from those that lost weight to those that maintained, and a tripling of conception from those that lost to those that gained weight.
What was the biggest driver of this change? The starting BCS of cows at calving! Cows that were heavier at calving lost more weight. Thinner cows were more likely to maintain their weight, yielding better reproduction. These conclusions are logical if we compare them to athletes. Trim and in shape athletes perform better. It seems to be that way with our cows, too.
How do we keep cows from losing weight? How do we drive them into the dry period without excess weight? Timely reproduction in the previous lactation prevents excess gain of body condition. There have been several studies that show BCS at dry off is driven by days in milk at conception. The current data shows that animals that conceive past 130 DIM are at a much higher risk for elevated BCS at dry off and more reproductive problems in the next lactation. Middleton and Pursley have dubbed this the High Fertility Cycle.
Researchers are suggesting that our new targets for calving BCS should be 2.75 to 3.25. Personally, I have seen this lack of big changes in BCS associated with farms that have successful reproduction. I believe this is an important concept to grasp, but I do think we need to be cautious in how we apply it as this has been shown on only a few farms at this point.
We also must consider health and production in our BCS matrix. How does calving BCS interact with these two factors? BCS of 3.5 or greater two weeks before calving was associated with decreased dry matter intake before and after calving, increased weight loss, fatty liver, Ketosis, and more calving problems, which all led to poorer reproductive performance. This seems to support most of the reproductive researchers’ suggested BCS goals. Low BCS cows also had problems though. There is a health risk for animals who drop below a 2.5 BCS. We need to watch the lower end as well as the top end to ensure we do not limit the reserves an animal has available, which can increase health issues, culling, lameness and may limit immune responses.
Our business is milk production, so how does calving BCS interplay with our income source? Low BCS cows have lower milk fat. They do not have the extra fat to pass through into the milk. High BCS cows can have extremely high milk fat early in lactation, which can be a sign of impending health problems. Fat is the reserve of the cow and if they are going to lose some weight, they will need that reserve to support production. Cows that lost weight generally had higher production. Their reserves supported production. Roche determined the optimum BCS at calving for production was a 3.5, with others showing that reducing BCS caused losses in production of 50 KG for 3.25 BCS and 114 kg for a BCS of 3 in the first 90 days in milk. When dropping BCS below 3 towards 2 there is significant regression in milk production.
With this information, what should we target? During the 2020 ADSA Discover conference the consensus among all the transition cow physiology gurus was 3.0-3.25 BCS (unpublished personal communication). This is a good target that blends ideal reproduction, health, and production. When we can blend animals’ welfare with good production and ideal reproduction, we have created a target that will stand the test of business and society.
The Genetic Connection
Feed efficiency in dairy cattle is being carefully evaluated by dairy producers and environmental agencies around the world. Feed efficient cows generate higher income over feed costs than cows that are less efficient. High body condition is not only a risk factor in cow health, it indicates an inefficient use of feed, as the animal is generating fat rather than milk. In addition to understanding BCS and adjusting management factors to reduce fluctuation in body condition, genetic selection for higher Feed Efficiency and Feed Saved can help to improve the income over feed costs for the herd.
Cows that experience a smooth transition period and maintain stable body condition generally have fewer metabolic disorders and health problems. Genetic selection for improved disease resistance (CDCB Health and Zoetis wellness traits), calving ability (DCE) and daughter fertility (DPR) will support the success of best management practices through the transition period.