Nutrition is one element of dairy management that can have a profound effect on the cow’s ability to conceive. Many key components of the ration – like energy levels – directly impact the dairy cow’s ability to become pregnant.
After all, reproduction only can be achieved when the proper ration and environment fulfills the animal’s maintenance and milk production requirements.
Within a properly balanced diet, specific feed ingredients can help improve reproductive success. For instance, ruminate on the influence of dietary anion-cation difference (DCAD), metabolizable protein (MP), essential fatty acids (EFAs) and immunity regulators in dairy rations. These feed ingredients work in tandem to promote cow health and productivity, which directly affect reproductive efficiency.
Consider the following factors to help nutritionally support your dairy’s reproductive program.
1. Formulate DCAD pre- and postpartum
Dairies have learned that feeding a negative DCAD diet (-8 to -12 meq/100g ration dry matter) for the three weeks prior to calving improves cow health and performance in the following lactation.
Research published in 2015 demonstrated that:
- Feeding the ration with negative DCAD levels reduced (p less than 0.05) the prevalence of subclinical hypocalcemia at day zero and one day in milk (20 percent and 34.3 percent) compared with the ration with positive DCAD levels (69.3 percent and 76.5 percent) on day zero and day one in milk.
- Incidence of clinical hypocalcemia (milk fever) was 0 percent in the ration with negative DCAD levels compared with 23.1 percent for the ration with positive DCAD levels (p less than 0.05).
The research illustrates how feeding a negative DCAD diet pre-partum positively impacts cow blood calcium status after calving. In turn, this positively impacts disease outcomes, milk production and reproductive efficiency.
Of course, ration DCAD strategies change following calving. Feeding a ration formulated for positive DCAD post-calving also benefits cow health and performance.
That’s because achieving a positive DCAD can help neutralize blood acid load caused by high milk production, ketone development and free fatty acids from body fat mobilization.
Plus, increasing the potassium component of DCAD will help replace what is lost through increased milk production, as well as assist cows in better dealing with heat stress.
Aim for a dietary potassium level of at least 1.7 percent of the total dry matter during non-heat-stress periods, and to at least 2 percent immediately before and during heat-stress periods of the year.
Postpartum ration DCAD levels depend on lactation stage. Recommendations are:
- +35 to +45 meq/100g ration dry matter for high-producing cows
- +30 to +35 meq/100g ration dry matter for mid-lactation cows producing less than 85 pounds of milk
- +25 to +30 meq/100g ration dry matter for late-lactation cows
Keep in mind that seasonality and climate can affect feedstuff DCAD levels. Be sure to test silage and other feed ingredients regularly with wet chemistry analysis to ensure that proper levels of DCAD are being fed at all times.
2. Don’t forget about MP
Simply focusing on DCAD levels alone – in the absence of accounting for MP – does not result in optimal rations. When you omit MP from consideration, you’re leaving opportunity on the table.
MP matters because it is the true protein that is digested post-ruminally, and the amino acids that are the components of protein are absorbed by the small intestine.
Absorbed amino acids are used for the synthesis of proteins essential for an animal’s growth, body condition maintenance, reproduction and milk production as well as supporting fetal growth. These are vitally important tasks and help explain why proper nutrition in the transition period helps lay the groundwork for a successful next lactation.
If dry cows do not receive enough MP, they will break down muscle and other protein sources in the body. It’s important to remember that early-lactation cows have an inability to consume sufficient protein to meet the mammary and nonmammary amino acid requirements.
That means that pre-fresh diets should be formulated to supply about 1,100 to 1,200 grams per day of MP.
When cows receive adequate levels of MP during this time frame, you’ll see benefits after calving. Research shows that MP fed in the close-up period was positively related to milk protein yield in early lactation as long as cows were fed more than 75 percent of their MP requirement in early lactation.
Don’t focus on DCAD to the exclusion of MP, because while you can certainly lock in DCAD levels, you can’t fully unlock your herd’s potential without MP’s key.
3. Boost conception rate with EFAs
Omega-3 and omega-6 EFAs are one of the solutions that have been identified to increase reproductive performance and immune function. EFAs aid in several significant biological functions (Table 1).
Data from five on-farm trials illustrate the positive health impacts that can be obtained by adding omega-3 and omega-6 EFAs to pre- and postpartum cow diets during the transition period.
Results showed that transition and pre-breeding diets enhanced with these EFAs:
- Resulted in 64 percent less embryonic death
- mproved reproductive performance
o Conception rate improved an average of 9.1 percent
o Pregnancy rate increased an average of 11.5 percent
The trial featured herds from across the U.S. Yet the upward trend in cow health and immune function from adding omega-3 and omega-6 EFAs to pre- and postpartum rations shows the positive impact this key feed ingredient has on cow health, productivity, reproductive performance and profitability regardless of location or management style.
University trials also indicate that adding omega-3 and omega-6 EFAs to transition cow rations improved immune function. Data show a 37 percent reduction of endometritis, a serious threat to reproductive performance.
4. Add immunity regulators
Lastly, immunity regulators have been shown to have a positive effect on dairy cow health and performance, thanks to the ability to bind mycotoxins and agglutinate harmful bacteria in the gastrointestinal tract that can impede immune function.
This is important because mycotoxins have been associated with several factors that reduce performance including irregular estrous cycles, embryonic mortalities, pregnant cows showing estrus and decreased conception rates.
When animals are fighting off a health challenge – whether locally or systemically – it affects the energy available for other biological processes, including cyclicity and pregnancy retention.
In addition, immune suppression caused by mycotoxins can be reversed by beta 1,3/1,6 glucans and mannans present in immunity regulators, allowing the cow to further protect itself against bacterial pathogens. Plus, nutrient uptake is maintained, leading to better feed efficiency and animal performance.
Keep in mind that optimal pregnancy rate and reproductive success takes efforts from all areas of the dairy. Work with your on-farm team as well as your veterinarian and nutritionist to identify opportunities for improvements.
Use nutritional tools such as DCAD, MP, EFAs and immunity regulators as part of an overall reproductive management strategy to help you achieve the outcomes you seek – optimal cow health, productivity, reproductive performance and profitability. 
References omitted but are available upon request. Click here to email an editor.
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Joel Pankowski
- Manager, Technical Services
- Arm & Hammer Animal Nutrition
- Email Joel Pankowski
