Highlights from the AMERICAN DAIRY SCIENCE ASSOCIATION Virtual Annual Meeting 2020

Marj Faust

Introduction

The Annual Meeting of the American Dairy Science Association (ADSA) is an indispensable forum for worldwide scientific exchange on work to understand and advance all aspects of dairy science from farm to fork.  The Association’s 2020 meeting was held in late June and used a new virtual (online) format.

This year’s ADSA Annual Meeting was composed of more than 800 recorded scientific presentations of original research across a range of topics including, Animal Health; Lactation Biology; Nutrition; Dairy Foods, Milk Protein and Enzymes; Forages and Pastures; Reproduction; Growth and Development; Breeding and Genetics; Production, Management, and the Environment; Animal Behavior and Well-Being; and Education and Teaching.  In addition, question and answer chat rooms and roundtable sessions were held to facilitate dialogue by researchers.  Specifically, we debated research needs of genetics companies in two thought provoking roundtable sessions, “Unmet Needs for Optimizing Reproductive Performance,” and “Genetic and Genomic Evaluation in 2020.”  Morning, afternoon, and late-night sessions enabled active participation by researchers around the world and in different time zones.

Scientific presentations with direct application to dairy genetics programs are summarized to provide dairies and their genetics advisors with up to date actionable information.

U.S. CDCB Health Trait Evaluations for Jerseys

Gaddis and Co-workers at U.S. Council on Dairy Cattle Breeding (CDCB) and American Jersey Cattle Association.

  • Scientific report on Health Trait evaluations released by the U.S. CDCB in April 2020.
  • S. national evaluations for Jerseys enabled by a significant influx of dairy data inspired by the American Jersey Cattle Association.
  • Incidence levels for Jerseys were similar, and slightly lower than levels for Holsteins.
  • Positive PTAs are desirable and indicate greater resistance to the respective diseases for animals and their progeny.
  • Researchers were able to identify real differences among sires for daughter resistance to these 6 health disorders.

Table 1. Incidence rates and Predicted Transmitting Abilities (PTA) for health traits in Jerseys

  • These six economically important health traits have been incorporated into Net Merit $ (NM$) and the Association’s Jersey Performance Index™ (JPI).
  • Take Home and Actionable:
    • These health traits provide Jersey dairies with effective tools for creating long-term permanent genetic progress in disease resistance.
    • Use of a selection index such as JPI™ provides a balanced approach for incorporating disease resistance into herds’ genetic selection decisions making.

 





 

Genetics of Passive Immunity in Calves

Haagen and Co-workers at Penn State Univ. and the Univ. of MN Morris.

  • Serum Total Protein is an indicator of passive transfer of immunity or IgG levels in the blood of young calves. Serum Total Protein (STP) is measured using a refractometer.
  • Failure of Passive Transfer indicates insufficient passive transfer of immunity, as measured using calf serum refractometer results.
  • Researchers reported measurable heritability for Serum Total Protein.
  • Favorable genetic correlations of STP and Productive Life, Cow Livability, and Net Merit $ (NM$) were found. This means that higher genetic merit for STP was associated with higher merit for these three traits related to lifetime profitability.
  • On the other hand, researchers reported finding that STP was uncorrelated genetically with Somatic Cell Score.
  • Take Home and Actionable:
    • Passive Immunity is a unique trait that may offer a new genetic/genomic tool to improve lifetime viability and profitability.
    • More comprehensive data and studies are required.
    • Let your genetics advisors know of your support to continue research and development for this trait.

 





 

Can We Select for (Against) Twinning?

Vukasinovic and Co-workers at Zoetis Inc.

Sewalem and Co-workers at ABS Global, Inc.

  • During the past ~20 years, researchers at the University of Wisconsin have conducted extensive work to understand the genetic control of twinning in cattle.
  • The UW researchers have reported that rates of twinning are 4.5 – 5.0% for Holsteins and are lowest for first calf heifers.
  • In addition, their work has shown that the trait is heritable and can be selected for (against) genetically.
  • Reports at the 2020 American Dairy Science Association meeting made by Zoetis and ABS Global further validate the findings from longstanding University of Wisconsin research. Using data collected on dairies, it is feasible to rank sires based on their genetic contribution to the risk of twinning for daughters.
  • The Zoetis researchers also conveyed findings that measurable genetic differences can be identified for abortion risk, thereby enabling genetic selection to reduce this risk for daughters.
  • Take Home and Actionable:
    • Twinning and abortions are traits with important health and economic implications for several breeds, and genetic decision-making for the traits is feasible.
    • Let your genetics advisors know how much priority should be given to genetic evaluations for twinning and abortions for your herd’s genetic program.

 





 

Genomic Evaluation of Heifer Livability

Neupane and Co-workers at USDA Animal Genomics and Improvement Laboratory.

  • Youngstock represent the dairy’s genetic and financial investment in its future.
  • By today, extensive national data are available to investigate genetic traits that may help support this critical youngstock enterprise within the dairy.
  • Using national multi-breed data, researchers studied Heifer Livability and reported an overall death rate of ~4% for heifers from 2 days up to 18 months of age. Considerable variability was evident with heifer loss rates in herds ranging from 1% to 25%.
  • Their findings indicated that the overwhelming majority of losses occurred in young calves, with 2/3 of losses occurring before calves reach 6 months of age.
  • Measurable heritability, but low for a Heifer Livability. Favorable genetic correlation with traits including production traits, Productive Life, and even female fertility.
  • Heifer Livability is planned for release to the industry by the U.S. CDCB in December 2020.
  • Take Home and Actionable:
    • Will want to revisit this trait when the December 2020 evaluation data are available to identify the genetic selection indexes where the Heifer Livability trait has been incorporated.

National consumer survey of dairy food preferences and purchase interest

Camire and Co-workers at the Univ. of Maine, Atlantic Corp., and the Univ. of Southern Maine

  • Researchers conducted a national consumer survey and economic assessment aimed at understanding and defining market opportunities for locally produced and marketed dairy products.
  • Survey responses were compiled from more than 19,000 dairy consumers representing all 50 U.S. states.
  • Significant proportion of respondents (at least 50%) indicated that they were unaware or unsure about local (within 75 miles) dairy farms, dairy processors, and dairy products in stores.
  • Researchers also reported that subgroups of respondents indicated they are willing to pay more to access local conventional and organic dairy products.
  • Also, respondents were interested in learning more about local dairy product options.
  • The research team is in the process of developing and making available an online tool for use by dairies, processors, and retailers to better characterize market opportunities for dairy products that are produced and marketed in their local area.
  • Take Home and Actionable:
    • Opportunities exist for dairies and local processors to target unmet consumer demands in their area.
    • We will want to revisit this when the online tool is completed and available for industry use.

Timing of AI and Herd Variability in Pregnancy Results when Using Sex-sorted Sperm.

Drake and Co-workers at Teagasc, Univ College Dublin, ICBF, and CEVA Sante Animale.

  • Study was designed originally to investigate whether conception rates (CR) from sex sorted semen and timed AI can be improved by conducting inseminations later than indicated by current protocols.
  • Researchers reported finding no difference in conception results between cows inseminated with sex sorted semen using timed AI at 16 and 22 hours after the last GnRH.
  • On the other hand when comparing conventional and sex sorted semen results, herd to herd differences were large despite the fact that all herds achieved acceptable conception rates with timed AI (16 hours after last GnRH) using conventional semen.
  • Herds with average to high sexed semen performance had conception rates for sex sorted semen relative to rates for conventional semen (CRsexed / CRconventional) that ranged from 80% to more than 100%.
  • For herds with the lowest performance from sex sorted semen, comparable relative rates (CRsexed / CRconventional) were only 48% to 77%.
  • These findings of large herd to herd differences in pregnancy rates with sex sorted semen echo results from work completed by my teams and results reported by other researchers.
  • Take Home and Actionable:
    • By today, very good and even excellent performance can be attained using sex sorted semen. However, some herds may still be striving to achieve their desired results.
    • When conception rates from sex sorted semen are lower than desired, dairies may benefit from comprehensive troubleshooting. Sex sorted semen tends to be less robust or “forgiving” than conventional semen, thus the following list highlights key areas for herds to initiate comprehensive troubleshooting.
      • Sire selection – Sires differ greatly in sex sorted semen conception rates. In addition, research results continue to confirm that a sire’s conception rate for conventional semen is an inadequate predictor of conception rates for sex sorted semen. This highlights the importance of seeking out and using reliable sire fertility measures specifically based on sex sorted semen results.
      • Semen thawing – To ensure maximum viability of the product, it is best to use thaw time and temperature guidelines recommended by the genetics company that produced the semen. Typical guidelines for sex sorted semen are to thaw semen in 95℉ to 98℉ (35℃ to 37℃) for 30 to 45 seconds. Using a thermometer in the thaw water helps confirm that the target temperature is reached and maintained.
      • Accuracy of thermometers – Periodic checks (at least every 6 months) of thermometers will identify those that have drifted out of calibration. Temperature controlled thaw units should receive periodic checks as well.
      • Semen handling – For sex sorted semen, thaw only the number of straws that can be inseminated in 5 minutes. Ensure that thawed semen is protected from temperature shocks, including pre-warming AI guns and other equipment that may come in contact with straws, and protecting loaded AI guns from cold and extreme heat.
      • Insemination technique and semen deposition – Using AI guns designed specifically for 1/4 cc straws can help minimize opportunities for semen loss due to straw alignment problems in universal guns. Semen should be deposited in the body of the uterus just in front of the cervix.
      • Heat stress on breeding females – Heat stress may compound lower fertility achieved when using sex sorted semen. Researchers in this field generally have advised providing cooling for animals especially during the critical periods of follicular growth and from ovulation to day 1 or 2 after estrus.

Sources

ABS Global, Inc.  2009.  Achieving Maximum Semen Fertility with ABS Sexation®https://docs.google.com/viewer?url=http://www.abstechservices.com/upload/library/Achieving_Maximum_Fertility_wABSSexation.pdf

American Dairy Science Association.  2020.  Virtual Annual Meeting.

DeJarnette, M.  2009.  Handling Procedures for 1/4 cc Straws.  Select Reproductive Solutions.  Select Sires, Inc.  SS121-0209-5K.  http://www.selectsires.com/programs/docs/0209_handling_procedures.pdf?version=20180803

Hansen, P. J.  2019.  Reproductive physiology of the heat-stressed dairy cow: implications for fertility and assisted reproduction.  Anim. Reprod. vol. 16, no.3.  Belo Horizonte July/Sept. 2019.  Epub Nov 28.  https://www.scielo.br/scielo.php?pid=S1984-31432019000300497&script=sci_arttext

Selk, G.  2006.  Oklahoma Beef Cattle Manual.  Chapter 24.  Artificial Insemination.  http://agecon.okstate.edu/cattleman/files/bcm_chapter_24.pdf

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