Newsletter – 2014 – May

President's message

Welcome to the May issue of the Dairy Cattle Reproduction Council’s E-Newsletter. Since our last edition, we’ve been busy implementing initiatives and honing our focus on producers. A great example is the new DCRC Expert Sharing that allows you to bring the experts into your monthly management meeting. More details to come soon!

One of these activities has been updating sponsorship opportunities. Check out this document to learn more about how you can participate. Don’t miss out on the many possibilities to reach out to your target audience.

Work also continues on developing new materials in the “members-only” section of our website. This is where you can access exclusive information like the latest webinar featuring the University of Florida’s Dr. Jose Santos. Dr. Santos discussed the “Role of Animal Health on Reproduction of Dairy Cows”. Watch here if you missed it.

Meanwhile, the program committee is hard at work developing an insightful agenda for the 2014 Annual DCRC meeting in Salt Lake City, Utah, November 13 — 14. We’ll unveil more details soon, but make your plans now to attend the conference this fall. See you there!

Research Summaries

What Factors Influence Reproduction Beyond the Voluntary Waiting Period?
Swedish researchers recently investigated the factors affecting a reproductive performance indicator at the cow level adjusted for herd reproductive management strategy—in this case, the voluntary waiting period. The study, published in the April Journal of Dairy Science, found that the chance for pregnancy was lower for:

  • Cows with severe problems at claw trimming compared with cows with no problems at trimming (only for second- and higher-parity cows)
  • Cows with a record of reproduction-related disease (For example, metritis, endometritis, etc.)
  • Cows of second- and higher-parity with records of dystocia compared with cows with no record of dystocia
  • First-parity cows in the group with the highest milk yield compared with first-parity cows in the group with the lowest milk yield
  • Cows of third- and higher-parity in the group with the lowest milk yield compared with cows in higher yielding groups
  • Cows with a twin birth compared with cows with a single birth

The researchers also noted that the chance for pregnancy decreased when the milk fat-to-protein ratio increased and as the somatic cell count increased. They concluded that factors that are known to affect reproductive efficiency also affect the chance of cows being pregnant 30 days following the voluntary waiting period.

Access the abstract.

Heat Stress a Big Problem for Cows in Moderate Climates
A retrospective study published in the May 1 Journal of Theriogenology investigated the relationship between the temperature-humidity index (THI) and the conception rate (CR) of lactating dairy cows. The aim was to estimate a threshold for this relationship and to identify periods of exposure to heat stress relative to breeding in an area of moderate climate.

The researchers also compared three different heat load indices related to CR: mean THI, maximum THI and number of hours above the mean THI threshold.

They found that the THI threshold for the influence of heat stress on CR was 73.

Negative effects of heat stress, however, were already apparent at lower levels of THI, and 1 hour of mean THI of 73 or more decreased the CR significantly. The CR of lactating dairy cows was negatively affected by heat stress both before and after the day of breeding.

  • The greatest negative impact of heat stress on CR was observed 21 to 1 day before breeding. When the mean THI was 73 or more in this period, CR decreased from 31% to 12%.
  • Compared with the average maximum THI and the total number of hours above a threshold of more than or 9 hours, the mean THI was the most sensitive heat-load index relating to CR.

These results indicated that the CR of dairy cows raised in moderate climates is highly affected by heat stress.

Access the abstract.

Cows Have Flooring Preferences at Calving
Since calving is the ultimate goal of a reproductive program—and is also a period when actions can impact the following reproductive cycle—it makes sense to carefully manage this event and make improvements when possible.

A recent study published in the February Journal of Dairy Science at the University of British Columbia investigated the flooring preference of Holstein dairy cows housed individually in maternity pens during the 30 hours before calving.

Seventeen multiparous cows were moved, on average, two days before expected calving date into an individual maternity pen with three different flooring surfaces: sand, pebble-top rubber mats or concrete flooring, each covered with about 6 inches of straw.

Results showed lying bouts increased during the hours closest to calving, regardless of flooring. The number of lying bouts did not differ between flooring types precalving, but cows had more lying bouts on sand and concrete compared with rubber at calving.

Cows spent more time lying down on sand and concrete compared with rubber precalving, but lying times did not differ between treatments at calving.

Cows that calved on sand spent more time lying on sand at calving compared with the other two flooring types. Cows that calved on concrete did not show a flooring preference at calving.

These results indicate that rubber mats are the least preferred by dairy cows in the maternity pens, even when covered with a deep layer of straw.

Access the abstract.

Can You Lower Prepartum DCAD Levels Longer?
By Dr. Elliot Block, Research Fellow, Arm & Hammer Animal Nutrition

Lowering prepartum dietary cation-anion difference (DCAD) during the three weeks prior to calving to reduce postpartum metabolic disease is a tried and true strategy to help dairy cows successfully navigate the transition period.

This nutritional solution has been repeatedly shown to reduce incidence of health challenges, including retained placenta and hypocalcemia. These health challenges can have a significant, negative impact on reproductive performance.

In order to reduce social and nutrition stress from multiple pen moves and ration changes, some dairies need to lower DCAD levels longer than the traditional 21 days to take advantage of this nutritional management strategy.

In addition, some dairies are unable to create multiple prefresh groups because of facility limitations, which can make a 21-day lower DCAD diet difficult to implement.

Furthermore, the trend of shorter dry periods (about 40 days versus the traditional 60 days) also often means a change in time spent on lower DCAD diets.

Positive Results
Research1 from the University of Minnesota published in the September 2013 Journal of Dairy Science shows that feeding lower DCAD diets for 21 or 42 days has a positive effect on blood calcium status and milk production.

In the study, cows were fed:

  • A negative DCAD (-16 mEq/100 g of dry matter) for 21 days before calving
  • A negative DCAD (-16 mEq/100 g of dry matter) for 42 days before calving
  • A positive DCAD (+12 mEq/100 g of dry matter) for 42 days before calving

Results indicated:

  • Overall, cows in both groups fed the negative DCAD diet tended to have higher postpartum serum calcium compared with cows fed the positive DCAD diet.
  • Cows fed negative DCAD for 42 days prepartum tended to have higher postpartum serum calcium levels than cows fed negative DCAD for 21 days prepartum.
  • Feeding a negative DCAD diet for 21 days prepartum resulted in higher milk yield during the first 56 days of lactation compared with cows fed a positive DCAD diet prepartum.
  • Milk production was similar for cows fed negative DCAD prepartum diets for 42 days and 21 days. Milk fat and protein production were also similar.

On-Farm Application
The research reinforced what was already known about lowering DCAD levels in prefresh diets, but also added some practical applications to producers’ toolboxes:

  • The confirmation that cows can receive negative DCAD diets longer than 21 days can mean fewer pen moves for large herds because they don’t need to split prefresh groups.
  • Results also mean producers who do not have facilities that allow multiple prefresh groups can more easily adopt this nutritional management strategy for improved transition cow health and performance.

Click here to access the abstract and learn more about the study.

1 Weich W, Block E , Litherland N. Extended negative dietary cation-anion difference feeding does not negatively affect postpartum performance of multiparous dairy cows. J Dairy Sci 2013;96:5780-5792.

Featured Column
By Dr. Ronaldo Cerri, University of British Columbia, Faculty of Land and Food Systems

The addition of fatty acids to dairy diets has piqued the interest of dairy producers and nutritionists in recent years. That’s because adding supplemental fatty acids to dairy diets has shown positive effects on reproductive performance, possibly due to effects on cows’ energy balance.

This fat supplementation also has an independent effect on overall production and reproductive performance. However, there’s still much more to learn and understand about how fatty acids impact dairy cow performance.

Transition Cow Implications
The last weeks of gestation and first weeks of lactation pose the greatest risk for disease for dairy cows. Metabolic events that occur during this period impact early lactation performance and, at times, compromise the entire lactation. As a result, much attention has focused on possible effects of specific fatty acids, or fatty acid mixtures on metabolism, health and reproduction.

The transition period is characterized by a shift in nutrient requirements of dairy cows, leading to coordinated metabolic and endocrine adaptations in an attempt to meet the increased demand for nutrients.

Research at the University of Florida in 2010 and 2012 has shown interesting results with regards to the effect of different dietary fatty acids on feed intake, milk yield and milk components.1

Researchers tested changes in the fatty acid profile of transition dairy cows’ diets. This study evaluated the impacts of supplementing diets containing small amounts of long-chain fatty acid (< 1.8%) with either mostly saturated-free fatty acids or with calcium salts enriched with polyunsaturated fatty acids containing the essential fatty acids (EFA) linoleic and alpha-linolenic during the last 50 days of gestation and first 90 days of lactation. Results showed:

  • Cows fed EFAs had improved milk yield, particularly first-lactation cows.
  • Milk protein yield was greater for first-lactation cows fed EFAs, but fat yield did not differ
  • Cows fed EFAs had greater feed efficiency.

Impact on Reproduction and Fertility
Results for feeding supplement fat also tended to be positive on pregnancy rate, particularly when strategies included differential dietary fatty acid profiles during the transition and breeding periods.

Fertility responses to fat feeding were best when moderate amounts of unsaturated essential fatty acids of the Omega-3 and Omega-6 families were fed.

For multiparous cows, feeding fat during the transition period resulted in a numerical increase in milk production, but no difference with fat source was observed in more recent studies. When Omega-3 and Omega-6 essential fatty acids were manipulated in the diet, a positive effect in lactation performance and fertility were observed.

The benefits to fertility were observed primarily because of reduced pregnancy loss in the first 60 days of gestation.

Furthermore:

  • Sources rich in Omega-3 fatty acid seem to increase pregnancy by improving embryo survival
  • Sources rich in Omega-6 fatty acid improve pregnancy because of increased fertilization and embryo quality

Overall, feeding supplemental fat has beneficial effects in follicle development, as well as oocyte and early embryo development, which seems to be independent of energy status.

1 Cerri RLA, Thatcher WW, Santos JEP. Nutrition and Reproduction: Focus on Fatty Acids. In Proceedings. 2013 Dairy Cattle Reproduction Council Annual Meeting.

Feature Member

Dr. Barry Kleppe
Waunakee Veterinary Service, S.C.
Waunakee, WI 53597
Member Since 2011

In each issue of the DCRC e-newsletter we will feature a current member who will share what they’ve learned from DCRC and the value they have seen in being a member.

Waunakee Veterinary Service is a six person, dairy-exclusive veterinary practice providing reproductive, production medicine and sick cow services. The majority of our clients are commercial dairies and our practice area is primarily northern in Dane County, Wisconsin, but it does extend south of Madison periodically and into the surrounding counties.

I am one of six veterinarians, all of which are partners in the practice. We provide the dairy health services needed by our dairy clients. My typical day runs the gamut from emergency care to herd health exams and protocols.

Dairy Background
I was raised on a 45-cow dairy farm in Iowa County Wisconsin. I earned a bachelor’s degree in dairy science and a masters degree in dairy science from the University of Wisconsin-Madison. My masters degree research focused on liver metabolism.

I earned my veterinary degree from the University of Wisconsin-Madison School of Veterinary Medicine. Upon graduation, I joined Waunakee Veterinary Service.

DCRC Influence
To me, reproduction seems to be the key to dairy profitability. Nutrition is obviously key to success, as is raising young stock. But we have to get cows and heifers pregnant to keep the dairy production cycle going.

I joined the organization about three years ago after watching with interest since it began. Several Waunakee Veterinary Service clients have had herds nominated for the DCRC reproductive awards and it became logical step to join DCRC.

I’ve found that DCRC provides an excellent compilation of the various synch protocols and through the information presented at annual meetings, one can get an idea how each stacks up against each other. I also appreciate the economic analysis of the value of a pregnant animal and the economics of dairy reproduction in general.

Repro Challenges
We seem to have overcome the perception that high producing herds cannot achieve high levels of reproduction success.  In a large part this is due to our use of the various synchronization protocols. However, I am concerned that consumers will object to our use of reproductive hormones. In spite of the fact that we can explain the science and safety of those hormones, my suspicion is that consumers will not be happy.

As an industry, we will have to adjust and use the newer activity monitors and other technologies with limited use of reproductive hormones. While I like that technology, I am somewhat concerned about the impact on reproductive performance and whether we can maintain the current level of success many dairies have achieved. I believe with time and experience, we can do so.

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