Newsletter – 2023 – February

President's Message

From the DCRC President’s Desk
By William “BJ” Jones, DVM

Greetings from America’s Dairyland!

We have been having a particularly mild winter in our part of the Midwest. I spend a large part of my day outside or in freestall dairy barns, and these mild temperatures have been greatly appreciated! I know that has not been the case throughout the country, with several of you experiencing blizzards and severe weather, but I sincerely hope that you all are surviving the weather without too many issues. I like to think we are through the worst part of winter and I love the increased amount of daylight we are seeing.

Some big things have been happening at DCRC. One is that we have been striving to increase our international outreach the last couple of years. While those initiatives have been delayed by the COVID-19 pandemic, we are proud to be participating in Dairy Tech UK on Feb 1. If you are in attendance, please stop by the booth to meet our featured speakers.

Plans are underway for our annual meeting in Salt Lake City, Nov. 14-17. This event will be extra special with a post conference, including the Academy of Dairy Veterinary Consultants. Watch our newsletters and website for details on this exciting partnership.

One of my favorite parts of DCRC annual meetings is the Excellence in Dairy Reproduction Awards, sponsored by Hoard’s Dairyman and the Dairy Cattle Reproduction Council. I have had the good fortune to work with several herds that have done well in the contest. Some common threads from herds I have worked with include:

  • Teamwork – All have quarterly management meetings with herd managers and key employees, owners, nutritionists, veterinarians, bankers, consultants and reproductive specialists. Everyone working and communicating together for the common goals of the dairy have been key.

  • Treat cows like royalty – The best cow comfort, hoof care, nutrition and cooling all add up to happy cows with outstanding reproduction.

  • Set up weekly repro plans and follow them – There are several ways to achieve one’s goals, but we favor first service fertility programs followed up with aggressive heat detection and weekly herd checks. Make it part of your routine each week and the results will be additive.

  • Genetics – I think genomics have been a game changer in pushing through barriers and helping us achieve levels of reproduction that would have been unheard of even five to 10 years ago.

If you think you have a herd with outstanding reproduction, nominate the dairy for this awards program. Nominations open March 1 and close April 30. We would love to see a record number of herds nominated this year!

Are you looking for another resource to “up your bovine repro game”? Check out “The Repro Spot YouTube channel.” Victor Gomez Leon, Kansas State University dairy extension specialist, and Jennifer Spencer, Texas A&M University dairy extension specialist, collaborated to produce these “spots” after interviewing dairy specialists.

Feel free to share other bovine repro resources with your DCRC colleagues. Send these to JoDee Sattler at: jodee@dcrcouncil.org.

Research Summaries

Evaluation of walking activity data during pregnancy as an indicator of pregnancy loss in dairy cattle
Chen and G. Ferreira

Pregnancy loss or abortion is usually detected when cows that were previously diagnosed as pregnant demonstrate estrous behavior. If remained undetected for long periods, pregnancy losses may represent large economical losses. The use of walking activity monitors is widely used to detect estrus in dairy cows. However, little is known about the value of monitoring walking activity to detect pregnancy losses. Therefore, the objective of this study was to evaluate if pregnant cows display activity peaks measured by pedometers. The hypothesis is that pregnant cows do not show these activity peaks. If this is confirmed, activity peaks in pregnant cows could be indicative of pregnancy loss.

Animals, reproductive management, and activity monitors

Data from a dairy herd milking 250 cows was used in the study:

  • 75% of the herd was purebred Holsteins, with the remainder being purebred Jerseys.
  • Reproductive management was based on a Double-Ovsynch protocol in the first artificial insemination (AI), with re-synch for subsequent AI.
  • Only cows that were confirmed pregnant and calved at 275 ± 7 days of gestation were included in the analysis.
  • Walking activity was measured using leg-based pedometers.
  • Activity peaks were identified using a peak search algorithm and filtered to ensure peaks were not caused by management routines, such as trimming, vaccinations, and change of pens.

Results

  • 537 pregnancies were used in the study.
  • Almost 15% of pregnant cows showed at least one activity peak throughout the pregnancy.
  • On average, pregnant cows displayed 1.53 peaks in activity per pregnancy.
  • Also, peaks were observed, on average, at around 100 days of pregnancy.

In conclusion, activity peaks can be displayed by cows while pregnant, and they may represent false positives for estrous detection. Therefore, activity peaks should be used with care if activity monitors are used to detect pregnancy losses in dairy cows.

Access the paper at: https://www.sciencedirect.com/science/article/pii/S2666910222001466


Hormone use for reproductive diseases and heat induction in relation to herd-level reproductive performance in Dutch dairy farms
Wicaksono, B. van den Borne, W. Steeneveld, T. van Werven, and H. Hogeveen

Using reproductive hormones, either to treat reproductive diseases or timed artificial insemination (TAI) protocols, allows for better reproductive performance in dairy herds. However, the effectiveness of reproductive hormone use has been evaluated in the past at the cow level, rather than the herd level. Therefore, this study’s goal was to evaluate the association of herd-level use of reproductive hormones to treat reproductive diseases and for TAI protocols with reproductive outcomes.

Herds included, hormone use, and reproductive outcomes

Data were collected from five large veterinary practices in the Netherlands:

  • Data were collected from 754 Dutch dairy farms.
  • Hormone use by herd was classified into prostaglandin, gonadotropin releasing hormone (GnRH), and progesterone.
  • Hormone data were gathered as number of doses by 100 head of cattle based on sales.
  • Three observations per farm (one for each year of the study; 2017-2019) were included in the analysis.
  • Herds were classified into four levels of hormone use – no use, low, medium, and high users – based on the 33rd and 66th percentiles of hormone use.
  • Herd-level reproductive outcomes were calving interval, calving to first insemination interval, and number of inseminations per cow.
  • Data on herd size, milk production, and insemination records were also collected.

Results

  • The median annual hormone use was 36.1 doses per 100 adult dairy cows, considering all herds.
  • The most commonly used hormone was prostaglandin, followed by GnRH. Little progesterone was used in the herds included in this study.
  • In comparison to herds that do not use reproductive hormones, the calving interval was 9.3, 6.5, and 6.2 days shorter for herds in the high, medium, and low hormone use categories, respectively.
  • The calving to first insemination was 16.4, 12.0, and 7.9 days shorter for herds in the high, medium, and low categories for hormone use, in comparison to non-user herds, respectively.
  • High and medium users needed 0.3 and 0.2 more inseminations to get their cows pregnant than herds that were non-users, respectively.

In summary, via a herd-level analysis, the level of reproductive hormones use was associated with reproductive performance in Dutch dairies, with higher levels of hormone use being associated with shorter calving and calving to first insemination intervals. However, greater levels of hormone use were associated with a greater number of inseminations to get cows pregnant.

Access the paper at: https://www.sciencedirect.com/science/article/pii/S0167587722002665?via%3Dihub


Increased parity is negatively associated with survival and reproduction in different production systems
I.J. Lean, H.M. Golder, S.J. LeBlanc, T. Duffield, and J.E.P. Santos

Dairy cattle longevity has decreased in most milk-producing countries. Cow culling in the United States and Canada is greater than 30%. In three dairies of the studies analyzed, first lactation cows comprised more than 40% of the herd. Profit and rapid genetic gains are complex tradeoffs that must be considered. Increased production is associated with reduced pregnancy per artificial insemination or extended days open. Lower-producing cows may not be bred, or breeding will cease sooner, and nonpregnant cows may be culled before the end of standard lactations. In addition, reproductive failure is one of the leading factors of culling in many dairy herds.

This study aimed to provide an understanding of the role of parity in risks for removal and reproductive failure. Also, the study strived to quantify associations of parity with survival and reproductive performance, statistically controlling for the level of milk production in cows in intensively fed herds and predominantly pasture-fed herds. Researchers examined the survival of cows and reproductive performance of different parities. They hypothesized that parity, production system (categorized as pasture-based or intensively fed with a mixed or component-fed ration), milk, milk fat or protein percentage, and milk solids production would influence the probability of survival, the hazard of not being bred (HNBRED), pregnancy to first breeding (PREG1), the hazard of pregnancy (HPREG), or odds of becoming pregnant in a lactation (OPAL).

Study selection criteria and animal data

  • Survival analyses were done based on 9 studies conducted between 1995 and 2020 (30,780).
  • 13 studies were conducted from 1992 to 2020 in Australia, the United States, and Canada, and included pasture- or nonpasture-fed (intensively fed) herds (32,783).
  • Studies were conducted from 1992 to 2020 in Australia, Canada, and the United States (32,783), including predominantly pasture- (n= 4,108) or nonpasture-fed (intensively fed; n= 28,675) herds.
  • There were 38.5% of cows in the sample in parity 1, 27.3% in parity 2, 16.7% in parity 3, 9.0% in parity 4, and 8.6% in parity ≥5.
  • Inclusion criteria for reproduction included an observational or randomized controlled trial that provided details on parity, milk production, and reproductive measures, including time to first insemination or pregnancy, and censoring for those events.
  • Multilevel models were used to evaluate the fixed effects of parity, milk, milk solids, milk fat and protein percentage and yield, and production system on reproductive outcomes.

Results

  • Compared with cows of parity 1, parity ≥5 cows had a greater HNBRED [hazard ratio (HR) = 2.45], lower HPREG (HR = 0.73), and reduced OPAL (odds ratio = 0.36).
  • Parity ≥5 cows had similar PREG1 to other parities, except for parity 1. All milk production measures had quadratic associations with OPAL, indicating that either low or high production, or concentration of solids within a cohort reduced OPAL.
  • This reduced OPAL reflected a greater HNBRED for lower milk yield, milk protein, and fat-yielding cows.
  • Both milk yield and milk protein percentage had quadratic associations with HPREG.
  • When centered milk yield was categorized into quartiles, small differences in HPREG existed.
  • Milk fat percentage (HR = 0.901), fat yield (kg/d; HR = 0.78), protein yield (kg/d; HR = 0.71), and milk solids yield (kg/d; HR = 0.84) were all linearly associated with reduced HPREG.
  • Differences in production systems did not have substantive effects on PREG1 but did for HNBRED, HPREG, and OPAL.

In conclusion, parity and reproduction associations were influenced by milk and milk solids. Older cows had lower reproductive performance. Pregnancy at first breeding was different among parities and less influenced by milk. Associations of parity with removal for all reasons indicate a need to develop better strategies to increase the longevity of dairy cows.

Access the paper at: https://doi.org/10.3168/jds.2021-21672

Featured Column

Optimize the use of sexed semen

During the last half of the 20th century (approximately 1955-2005), dairy cattle reproduction performance steadily declined. A variety of factors – from increased milk production to more inbreeding to less than optimal nutrition – may have contributed to the decline.

Reproductive physiologists, geneticists and other dairy industry experts collaborated – with some of it fostered by the Dairy Cattle Reproduction Council (DCRC) – to reverse negative reproduction trends. During the 2022 DCRC Annual Meeting, Paul Fricke, University of Wisconsin dairy cattle reproduction professor and extension specialist, described the “reversal,” which started in 2002, as a “reproduction revolution.” “The dramatic increase in reproduction has occurred during the past decade (or so),” he stated.

While improved genetics, nutrition and management protocols helped improve dairy cattle reproduction, adoption of fertility programs, such as timed artificial insemination (TAI) and ovulation resynchronization (“resynch”) after a nonpregnancy diagnosis, played an important role in increased reproduction performance. Additionally, coupling fertility programs with new technologies for estrous detection, based on activity monitoring systems, effectively helped achieve higher pregnancy rates.

During this revolution, sexed semen performance and economics improved. However, sexed semen performance still lags conventional semen performance. Use of sexed semen increases genetic progress in dairy herds through increased dam selection intensity (Khalajzadeh et al., 2012). Other strategies include genomic testing or pedigrees to identify genetically superior heifers and cows, use of sexed semen to inseminate genetically superior dairy heifers and lactating cows balanced for replacement needs (Weigel et al., 2012), and use of beef semen to inseminate low genetic merit heifers and cows to produce crossbred calves with increased value in the beef market (Ettema et al., 2017). “This has led to a rapidly evolving trend to use sexed Holstein semen, conventional Holstein semen, and conventional beef semen to inseminate Holstein females in the United States,” Fricke reported.

Improving fertility with sexed semen

Given sexed semen’s important role in helping dairy producers “right size” their herds and capitalizing on the herd’s best genetics, Fricke focused his presentation on management strategies to improve the fertility of sexed semen in nonlactating heifers and lactating dairy cows.

Fricke explained that heifers do not respond favorably to synchronization protocols based solely on GnRH and PGF2α, such as Ovsynch. The “key” is to include a controlled intravaginal progesterone insert (CIDR) during the protocol. This practice prevents heifers from displaying estrus until CIDR insert removal, which increases synchrony to the protocol. DCRC recommends the 5-day CIDR-Synch protocol (https://www.dcrcouncil.org/protocols) for dairy heifers. Fricke noted that 27% to 33% of heifers display estrus >24 hours before scheduled TAI with the 5-day CIDR-Synch protocol. “This makes detection of estrus during the 5-day CIDR-Synch protocol a requirement to achieve acceptable conception rates,” he remarked.

Lauber et al. (2021) conducted a field trial to compare reproductive management programs for submission of Holstein heifers for first insemination with sexed semen. The researchers evaluated:

  • CIDR5 (5-day CIDR-Synch)
  • CIDR6 (6-day CIDR-Synch)
  • EDAI (PGF2α on day 0 was followed by once daily detection of estrus [visual detection of tail-chalk removal and other signs] and AI)

The research team concluded that although delaying CIDR removal by 24 hours in a 5-day CIDR-Synch protocol suppressed early expression of estrus before TAI, delaying CIDR removal by 24 hours tended to decrease pregnancy per artificial insemination (P/AI) for heifers inseminated with sexed semen. Furthermore, submission of heifers to a 5-day CIDR-Synch protocol for first AI tended to increase P/AI and decrease the cost per pregnancy compared with EDAI heifers. Fricke explained that the decreased cost per pregnancy was due to decreased days on feed. Further, this decreased cost more than covered the cost of the 5-day CIDR-Synch protocol and resulted in an overall $17 decrease in cost per pregnancy compared with heifers inseminated to estrus after treatment with prostaglandin.

Timing of AI: Sexed vs. conventional semen

Is optimal AI timing different for sexed semen compared with conventional semen? It appears that the answer is “yes.” Bombardelli et al. (2016) evaluated the use of sexed semen in lactating cows with an activity monitoring system in Jersey cows to TAI based on increased activity. Overall, P/AI using sexed semen was greatest for Jersey cows inseminated between 23 and 41 hours after the onset of activity, which is later than the optimal timing for conventional semen of 4 to 12 hours (radiotelemetric system) after the onset of standing activity (Dransfield et al., 1998) or 8 to 16 hours (activity monitoring system) after the onset of activity (Stevenson et al., 2014).

“Inseminating high-producing cows later using sexed semen may be optimal for cows inseminated to estrus,” Fricke stated. This is because ovulation occurs later relative to the onset of estrus in high-producing cows as milk production near the time of estrus increases.

Fertility program: Optimal AI timing with sexed semen

What is the optimal timing of AI using sexed semen when the interval from timing of AI to ovulation is controlled using a fertility program at first service? To address this question, Lauber et al. (2020) submitted primiparous cows to a Double-Ovsynch protocol for first service that included a second PGF2α treatment 24 hours after the first in the breeding-Ovsynch portion of the protocol as described by Brusveen et al. (2009). The last GnRH treatment (G2) varied between treatments and TAI. To vary the interval between G2 and TAI, cows were randomized to two treatments to receive G2 either 16 (G2-16) or 24 (G2-24) hours before TAI, which was fixed at 48 hours after the second PGF2α treatment of the breeding-Ovsynch portion of the Double-Ovsynch protocol.

The research team found that G2-24 cows had fewer P/AI than G2-16 cows at 34 ± 3 days (44% vs. 50%) and 80 ± 17 days (41% vs. 48%) after TAI. Pregnancy loss and fetal sex ratio did not differ between treatments. Induction of ovulation earlier relative to TAI after a Double-Ovsynch protocol decreased P/AI in primiparous Holstein cows, whereas pregnancy loss and proportion of female fetuses did not differ between treatments.

First service insemination strategy

In a field study, Lauber et al. (2022) enrolled 742 lactating Jersey cows, which were randomized by ear tag number and within parity for submission, to either first service after a Double-Ovsynch (DO) protocol or a protocol for synchronization of estrus with twice-daily detection of estrus (EDAI) using sexed Jersey semen.

The results? Mean days from PGF2α (day 24) to AI was greater for EDAI than DO cows, whereas the proportion of cows inseminated was greater for DO than EDAI cows (100% vs. 75%). “Thus, 75% of cows in the EDAI treatment were detected in estrus and inseminated, whereas 25% of cows were not detected in estrus and were submitted to TAI after an Ovsynch protocol for first service,” Fricke reported.

Bottom line: This study found that lactating Jersey cows submitted to a DO protocol for TAI at first service had more P/AI for both sexed and beef semen than cows inseminated after estrous synchronization.

For more details about these sexed semen trials, read Paul Fricke and Megan Lauber’s DCRC Annual Meeting proceedings paper, which can be found in the DCRC Member Center.

Featured Member

Editor’s Note: For each issue, DCRC interviews a member to learn more about his/her career, involvement with DCRC and thoughts about dairy cattle and reproduction. We encourage you to recommend someone for this feature by contacting JoDee Sattler at: JoDee@dcrcouncil.org

 

Tracy Burnett
University of Guelph Ridgetown Campus
Ridgetown, Ontario, Canada
DCRC member since 2013

Meet Tracy Burnett, the new DCRC vice president. Currently, she works at the University of Guelph’s Ridgetown Campus, a rural campus of the University of Guelph, which is centered on hands-on education and offers diploma programs in agriculture, environmental management, equine care, horticulture and veterinary technology, as well as other certificates and continuing education opportunities. The campus also has significant focus on research and knowledge transfer in these areas. The Ridgetown Campus is part of the Ontario Agriculture College and has a unique role in connecting with young, up-and-coming producers, especially within the dairy industry, through education.

Burnett’s work responsibilities revolve around teaching and research. She teaches the main dairy cattle courses offered at Ridgetown campus, which cover key topics in production, reproduction and management. Her research focuses on using technology for managing dairy cattle health and reproduction.

Unlike many of her professional colleagues, she was not raised in agriculture or the dairy industry. “My passion for the dairy industry started during my undergraduate degree at the University of British Columbia, where I worked as a summer student at their Dairy Education and Research Centre,” she explained. “Later, I worked for Agriculture and Agri Food Canada as a research assistant, which sparked my passion for research. Together, these opportunities inspired me to start studying dairy cattle and pursue grad school at the University of British Columbia; and the rest is history!”

Reproduction is fascinating

When Burnett first thought about what area of dairy production she wanted to focus on, she knew she wanted to choose something that could have a large impact on the lives and outcomes of the cows themselves. “Reproduction is a fascinating topic because it can be studied from basic science to applied, and any level in between,” she commented. “Reproduction is also extremely linked and imbedded into all other aspects of dairy farming, making it an exciting and important topic to study, which I feel is endless!”

Burnett joined DCRC in 2013 as a student member. Since then, she has followed the organization’s webinars, newsletters and conferences to keep up to date on the newest reproductive research and developments. “I am honored that I was asked to be part of DCRC as the vice president.”

Regarding DCRC’s influence on dairy reproduction education and improvement, Burnett commented that DCRC is an incredible source of information, which is made directly available to not only researchers and academia, but to producers themselves. “I find that DCRC puts extra emphasis on making information approachable,” she remarked. “We can see this through the design of newsletters, fact sheets, webinars and annual meetings, as well as the availability of content across multiple languages.

DCRC provides valuable resources

When asked to describe two things she learned about dairy reproduction due to DCRC, Burnett found it challenging to pick just two. “I am constantly impressed by the innovative research that is being presented through DCRC’s webinar series,” she said. “DCRC is one of the few webinar series that I try to set aside time to watch live. One of my go-to resources for teaching is always the protocol fact sheets for both cows and heifers. They are excellent!”

Regarding current and future dairy cattle reproductive challenges and opportunities, Burnett is excited about advances in using data from “precision technologies” to optimize reproductive management. “I welcome reproductive strategies that are more cow specific,” she commented. “I’m looking forward to seeing where this line of research takes us.”

However, Burnett is concerned about understanding how reproductive failure develops, and how animal and rearing factors play into reproductive issues with lactating cows. Research opportunities exist for addressing these challenges.

Industry Calendar