Transition Cows Key to More Milk, Better Repro
If producers don’t see clinical milk fever and clinical ketosis, they often think all is good with the transition cows. But that is far from the truth.
“We miss the big picture when we only focus on clinical disease,” explains Thomas R. Overton, professor of dairy management at Cornell University. “When metabolism is off during the transition period the problem may or may not show up as clinical disease. But it does show up as lower milk production and reduced reproductive performance.”
Recent research has connected the dots between subclinical disease during the transition period and reduced milk production and lower reproductive performance. Thanks to several large datasets of commercial dairy herds we now know that subclinical ketosis and subclinical hypocalcemia lead to lower milk and reproductive performance.
“We need to shift our mindset from the transition cow as a disease opportunity to the transition cow as a production and reproduction opportunity,” says Overton. Producers who have made this shift in mindset routinely see more milk production – about 2 to 4 lbs/cow/day – and one to two units increase in 21 day pregnancy rate and less incidence of clinical disease. These production improvements are economically meaningful and they are achievable.
What the research tells us
In the last 10 to 15 years the industry has learned and implemented a lot of changes for transition cows, such as dietary cation anion diets (DCAD), controlled energy diets, and changes in groupings to name a few. But the large datasets collected and analyzed from commercial dairy herds have revealed even more opportunity exists to improve transition cow health and performance.
For example, a study by Chapinal et al, 2012, focused on calcium status, ketone levels and non-esterified fatty acids (NEFA). Herds with greater numbers of cows with low blood calcium at one week after calving had twice the rate of displaced abomasums, produced 6 to 8 lbs/cow/day of less milk on first test day and had a 30% decrease in first AI conception rates.
Another study by Ospina et al, 2010, looked at elevated NEFA and beta hydroxy butyric acid (BHBA) levels in transition cows. The researchers found that when more than 15% of cows in a herd had prepartum NEFA levels of ≥ 0.3 mEq/L that clinical disease incidence increased by 3.6%, pregnancy rate declined by 1.2%, and milk yield dropped by 529 lbs on a 305ME basis for both cows and heifers.
In herds where more than 15% of cows had postpartum NEFA levels of ≥ 0.6-0.7 mEq/L clinical disease incidence increased by 1.7%, pregnancy rate decreased by 0.9% and 305ME milk production declined by 640 lbs for heifers and 1,272 lbs for cows.
When looking at postpartum BHBA in those same herds, the researchers found that when more than 15% of cows in a herd had a BHBA ≥ 10-12 mg/dL clinical disease incidence increased by 1.8%, pregnancy rate declined by 0.8% and 305ME milk production dropped by 1,179 lbs for heifers and 732 lbs for cows.
In the Ospina research, a herd incidence rate of 15% was the alarm level. (This was the cut point most predictive of herd level opportunities.) In the study 75% of herds were above the alarm level for prepartum NEFAs and 40% of herds were above the alarm level for BHBA.
Another study by Lawton et al., 2015 JAM looked at the prevalence of hyperketonemia between three and 14 days in milk on 71 commercial dairies. They found that 50% of herds had more than 15% of cows with a BHBA above 1.2mmol/L.
As researchers have been doing more epidemiological studies of the data from commercial dairy herds the link between subclinical hypocalcemia and subclinical ketosis with reduced milk production and reproductive performance has become clear. Subclinical hypocalcemia and ketosis carry long-term economic consequences.
Make a difference
“We tend to focus on the challenges in our face when they occur,” says Overton. But clinical cases are just the tip of the iceberg. The good news is that subclinical hypocalcemia and subclinical ketosis, as well as many of the common transition cow problems; are preventable.
Overton says when DCAD diets were first introduced he was skeptical of the value because low potassium forages are readily available in the Northeast and many herds already have a very low incidence of clinical milk fever without feeding anions. But since this new research has shown the economic losses from subclinical disease he has become a believer. “I’ve become much more aggressive in using DCAD diets to combat subclinical problems and the results have been good.”
Producers tend to look for that one big nutritional tweak that will make a difference. But from what we have seen it can be a lot of little things that make the difference. Implementing DCAD diets, small changes in feeding management such as getting particle size right, grouping and stocking density, and heat stress all affect the transition cow’s ability to thrive.
It doesn’t take a lot to throw things out of balance. It may be a slug of cows freshening at once that changes the pen dynamics and increases competition at the bunk. It could be a change in forage quality that no one noticed. Sometimes the solution is found in ration formulation, but more often than not it is the other little things that make the difference.
“Whenever I ask producers if it is worth it to go after the extra milk and better reproductive performance the answer is yes,” says Overton. It takes an intensity of management, but many who have sought to minimize subclinical disease in transition cows have been successful. In fact, a review of Cornell data from 72 New York and Vermont herds shows that many herds do succeed:
|Health event < 31 DIM||Achievable Rate||Herds That Achieve That Rate|
|Subclinical ketosis BHBA ≥ 1.2mmol/L||< 15%||51.4 %|
|Displaced Abomasums||< 3%||76.8%|
|Retained Fetal Membranes||< 8 %||63.4%|
Clinical milk fever is a thing of the past on many farms. Today the opportunity lies in minimizing subclinical disease, stresses Overton. Producers who have changed their mindset in order to pursue the additional milk and reproductive performance that comes with minimizing subclinical disease are glad they did.
Take for example, a 1,000-cow dairy from northern New York. They were seeing 30+% of cows with subclinical ketosis as determined by weekly blood BHBA monitoring in the fresh pen. Those rates dropped to less than 15% and milk production increased by 3 to 4 lbs/cow/day over time. It wasn’t a big overhaul of the nutritional program; rather we identified that the particle size of the straw and hay in the dry cow rations was too long. Maintenance on the mixer and knives and getting feeding management right every day made a big difference in overall fresh cow health and performance. Changing your mindset about transition cows can make an economic impact on your dairy, too.
To learn more about what is achievable on farm, check out the New York State Cattle Health Assurance Program Transition Cow Guidelines at: https://ahdc.vet.cornell.edu/programs/NYSCHAP/docs/TransitionCowBenchmarks.pdf