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                     42 BC HOLSTEIN NEWS ❆ CHRISTMAS 2021 Observations From the Field
The Fall Open Industry Session Genetic Update – Part One
Paul Meyer, Sales Manager, WestGen
Twice a year, producers, geneticists and industry stake- holders get together for virtual sessions to introduce new concepts and provide updates for upcoming genetic evaluations. These sessions are well attended and provide the Canadian industry and the Genetic Evaluation Board that represents the various entities with valuable input and feedback from across the country. The October sessions were interesting as always and focused on topics like Feed Efficiency, Body Weight, Indirect Herd Life, the difference between Haplotypes and Gene Tests and introduced a new Herd Report for milk recording herds. Below is a synopsis of some of the main topics discussed.
Plans to Incorporate Feed Efficiency in LPI and Pro$
Presented by Gerrit Kistemaker and Caeli Richardson (Lactanet)
Feed Efficiency:
• Officially introduced as a genetic trait in April 2021
• Not yet added to the LPI or Pro$
The consensus is that Feed Efficiency should be added to both indexes but it is not yet clear what the weight should be.
Approach:
Since Pro$ and LPI do not account for feed efficiency adding the value of better Conversion of feed to energy would be beneficial. There is no concern about double counting from other pieces already in the formulas.
• Pro$ is expressed in Dollars
• Express Feed Efficiency in Dollars
• Add Feed Efficiency expressed in Dollars to Pro$
• Here is how the correct weight is realized:
Accounts for:
• Possibility of 5+ lactations
• Probability of survival to later lactations
• Milking, dry periods, and growing heifer
Across the cow’s lifetime, 1 kg of more efficiently converted Dry Matter Intake (DMI) during the cow’s first lactation
• Lifetime savings of:
• 0.58 + 1.00 + 1.65 = 3.23 kg Dry Matter • 0.055 kg Methane
• a total savings of $0.89
$0.89 in lifetime savings per 1 kg of Dry Matter saved in first lactation (Richardson et al., 2019)
Express Feed Efficiency in Dollars
Feed Efficiency evaluations reduce Dry Matter Intake (DMI) by 53 kg per 5 points of breeding value
• After peak in first lactation
• 10.6 kg per breeding value point
Combine 10.6 kg with $0.89 per kg
Each 1 point of breeding value increase in Feed Efficiency in a sire’s proof is expected to reduce feed cost in daughters by $9.43
This estimate is certainly an underestimation of the true economic impact of reducing feed intake
• Proof reliabilities are relatively low which reduces the expected impact
• The 53 kg impact is the reduction in Dry Matter Intake after the peak rather than the whole lactation
Adjusting the Pro$ Value
We can adjust Pro$ by adding:
• 9.43 *(FE – 100) for animals with a Feed Efficiency evaluation
• For animals without a FE evaluation, we assume they are average (i.e.: 100) and no adjustment is therefore applied
Impact on Pro$
Reviewing all genotyped bulls, Pro$ impact ranges from ‐$170 (FE=82) to +$160 (FE=117). Proof correlations for GPA bulls with Feed Efficiency become slightly more positive.
• Pro$: 0.17
• Pro$ with FE adjustment: 0.21
How to make FE Adjustment to LPI?
As LPI is not expressed on a Dollar scale, creating an adjustment for the LPI that has a similar weight as for Pro$ would be the approach. Since the LPI scale is approximately 40% of the Pro$ scale, we would use an adjustment that is 40% of the Pro$ value
• 0.4 * 9.43 = 3.77
Adjust LPI
• We can adjust LPI by adding:
• 3.77 *(FE – 100) for animals with a Feed Efficiency evaluation
• For animals without a FE evaluation, we assume they are average (i.e.: 100) and no adjustment is therefore applied
Impact on LPI
Reviewing all genotyped bulls, LPI impact ranges from ‐68 (FE=82) to +64 (FE=117). Similar to Pro$, proof correlations for GPA bulls with Feed Efficiency become slightly more positive.
• LPI: 0.17
• LPI with FE adjustment: 0.20
Summary
A method to include Feed Efficiency in LPI and Pro$ has been proposed
• Calculate Dollar value for inclusion in Pro$
• Use similar weight for inclusion in LPI
Feed Efficiency correlation with indexes increases ~ 0.04 by doing so and this would be a conservative estimate of the impact of Feed Efficiency.
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 Plus tôt dans la vie Plus tôt dans la vie
1st Lact. Cow
1st Lact. Cow
Lactations ultérieures
Lactations ultérieures
Earlier in life Earlier in life
1st Lact. Cow
1st Lact. Cow
Later Lactations
Later Lactations
    0.58 kg DMI 0.58 kg DMI
1 kg DMI
1 kg DMI
1.65 kg DMI
1.65 kg DMI
  Development of Genetic Evaluations for Body Maintenance
Presentation by Allison Fleming (Lactanet)
Introduction
Launch of Feed Efficiency evaluations provides an opportunity to explore a new genetic evaluation for Body Maintenance. Lactanet is now in the data exploration, preparation and planning stage. It is known that bigger cows have greater maintenance requirements. Genetic evaluations for Body Maintenance could be another tool to reduce feed costs and improve profitability. Current Feed Efficiency evaluations are independent of metabolic body weight.
Terminology
Body Weight = Total body weight (ex.: scale weight)
Metabolic Body Weight = Weight of metabolically active tissue and calculated as Body Weight x 0.75. Metabolic Body Weight has a direct relationship with maintenance requirements
Body Maintenance requirements = Energy needed just to maintain her body
Approximated Maintenance Costs = Relationship between Body Weight Measurements
• Weak genetic correlations between Body Weight and production traits
• Negative genetic correlation between Body Weight and
third lactation cows
AvAevreargaegeBBooddyyWeeigighhttbyDays in Miliklk
Average Body Weight Trend for Cow
Average Body Weight Trend for Cows <75 DIM
    Margin Over Feed Cost (Hagan, 2020)
Maintenance Requirements in Pro$
750
750
    body weight and body maintenance requirements. 540 kg cow
• ~ $2.55/d maintenance feed costs
• $3,723 over four years 840 kg cow
• ~ $3.25/d maintenance feed costs
• $4,745 over four years
Genetics of Body Weight
Body Weight is a moderately heritable trait (0.25 to 0.41) • Genetically correlated with conformation traits
550
550
00 7676 115353 229229305305
estimated from classification records
Maintenance costs represent ~20% of accumulated posAtv‐8e00r
2000 2005
80
2009
2014
2018
Body weights derived from heart girth measurements which are an indicator of true body weight
Body Weight Records
Many cows will have their body weight recorded around the first or second test day after calving. The majority of cows have only one body weight record per lactation
Distribution of Body Weights
The average weight of all Holstein cows in the data set is 652 kg
Trend for Cows <75 DIM
Since 2010, weights have been increasing 4.3 kg/year for
• Focus will be on the Holstein breed
7 700 700
 Daughter profitability calculations used for Pro$ try to 700
account for differences in maintenance requirements 650 650 650
• $ maintenance feed cost per day
• Based on deviation from average breed body we60ig0ht550
 0
76 153Days in Milk / Jours e2n29lait 305
600 600
550
Vision and Continuing Research
50
Average Body Weight Trend for Cows <75 DIM
 550
2000 2005
2009
2014
2018
Year of Birth / Année de naissance Year of Birth / Année de naissance
    rearing expenses for the average cow 5502000
Body Weight Data Source
800 737.
Body weight data has been collected as part of Lact73a7n.5 et 67
East (Valacta) Feed Advisory Services for more than 20 years. Thus, over 3 million body weight records can675be found in the database. A subset of ~800,000 records from612. ~500,000 Holstein cows in ~5,000 herds were used. 612.5
age ABvoedryagWe eBiogdhyt WbyeiDgahyt sbyinDMayislkin Milk
2005
Days in Milk / Jours en lait Days in Milk / Jours en lait
• Multi‐trait single‐step genomic evaluation
• Weight in first, second and third lactations
• More than 25,000 genotyped cows with a body weight record
Final result: a single breeding value expressing body maintenance requirements relative to breed average. Most obvious home is within Pro$
• Has an economic value
• Incorporated in an index balanced with production to maximize selection for profitability.
2009
 5
737.5 5
675
5
612.5
Year of Birth / Année de naissance
0
 Average Body Weight (kg) Poids corporel moyen (kg)
Average Body Weight (kg) Poids corporel moyen (kg)
Average Body Weight (kg) Poids corporel moyen (kg)
Average Body Weight (kg)
Average Body Weight (kg) Poids corporel moyen (kg)
Poids corporel moyen (kg) Average Body Weight (kg)
Poids corporel moyen (kg)
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