Page 46 - BCHNews-Spring2021-Web
P. 46

 Observations From the Field
April Showers – Gain Worth the Pain
   Metaphorically, the April genetic updates are ‘April showers that will bring May flowers.’ They will include some important changes that require an investment in time to ensure proper understanding, but those changes will improve our genetic evaluations. No one likes change, of course, so that’s the difficult part. This piece will try to summarize, as briefly as this long- winded person is capable of, the highlights of a key new trait being added, new numbers that make our proof values more relatable, and adjustments to Type numbers that remove unintended bias.
Feed Efficiency Evaluations make their Debut
Following on the heels of the US, where Feed Efficiency evaluations were introduced in December, Lactanet is now introducing Feed Efficiency evaluations in Canada. The trait itself is an important addition, but so is knowing that the way Canada has chosen to express it is quite different from that of our southern neighbour. In Canada, the overall objective is to select for cows that use less feed at the same level of production and body size after peak of lactation. The aim is not to reduce feed intake in early lactationwhenanimalsaretypically in a negative energy balance. The trait takes into account energy required for Maintenance and Production and selects for animals that have an increased efficiency of turning feed into energy. It is important to understand that the Canadian evaluation for Feed Efficiency is not correlated with Production or Body Size – it is not intended to affect the size of the cow nor affect milk production. Simply stated, feed efficient cows will have a lower feed intake, all other things being equal.
Some points to understand about the Canadian Feed Efficiency evaluations – let’s start by making clear that when looking at a sire proof, the relationship with average Dry Matter Intake (DMI) of his daughters is not expected to be very high. Daughters will be varied in their production levels
and that affects DMI; daughters will be varied in size which also affects DMI. Expect that a 5-point increase in Feed Efficiency relative breeding value will equate to an expected daily decrease in feed intake of 0.24kg and translating to approximately 60 kg less feed consumed between 61 and 305 days in milk. This is about a 1% reduction in feed intake.
Most sires do not have daughters with feed efficiency data yet, and reliabilities will be lower than for other traits. Average reliability in our top 100 GPA LPI bulls will be around 41% with ranges from 36% to 46%, while in the top 100 Proven LPI list we can expect an average reliability of 51% with many bulls around the 46% reliability mark.
This is new for all of us. As I write this in mid-March, I have no idea which sires will be the trait leaders nor who the laggards will be. We will learntogetheronproofdayinApril! That said we know that selection for Feed Efficiency will reduce Dry Matter Intake. It has been designed to be uncorrelated with Energy Corrected Milk and Body Weight. FeedEfficiencyhaslowcorrelations with all other traits we are currently evaluating. For now, we will see Feed Efficiency for Holsteins only and only for those bulls that have been genomically tested. In addition, only Lactanet DHI herds will receive feed efficiency genetic values for their females. For the initial phase of introduction, the trait will not be included in either the LPI or Pro$ index formula.
Improvements for
Interpretation of Proof
Education and extension efforts have occasionally produced tables on the relationship between bull proofs and expected daughter performance. Incorporating some expected daughter performance indicators into Lactanet internet pages as a standard practice is expected to help quantify differences between sires for different traits. Most visibly, on the summary page for bulls on the CDN (Lactanet) site, the Breed Average
column for the Functional Traits will be replaced with a single value for interpretation. These numbers will relate to each trait specifically. For example, Herd Life will see the 100 in the Breed Average replaced with a +/- % survival to 4th calving. Each trait will have its own description, so some effort will be required to provide context to the number. However, once understood, it will make a proof number more relatable delivering increased value in helping producers understand genetic evaluations and in managing the expectations in breeding decisions.
Additional detail and proof interpretation numbers can be found on the Health page for sires for the Metabolic Diseases, Fertility Disorders and for the individual lesions associated with Hoof Health.
to all animals instead of just those with recently scored daughters. Another benefit is that the formula can be adjusted to fit industry needs. Composite indexes will be used for Mammary System, Feet & Legs, Rump, and Dairy Strength. Major type composites will then be combined into an overall Conformation composite. These changes will not necessitate any trait name changes; however, adjustments will be added to type composites for all three breeds. For example, the Mammary System composite will be adjusted to ensure a neutral or positive correlation with Teat Length (longer) and to ensure neutrality with Stature. Feet & Legs composite will be adjusted to ensure neutrality with Rear Legs Side View as well as with Stature. No adjustments are being made for the
Paul Meyer, Sales Manager, WestGen
animals and those with extreme scores. We can expect changes to Mammary System, Feet & Legs, Rump, Dairy Strength and Conformation proofs as a result of the introduction of composites and from the adjustments made to these composite formulas to neutralize the impact of stature, teat length and rear leg side view. These adjustments then can also change LPI, Pro$ and Herd Life ratings and rankings. Adding further disruption, the annual April base change will also occur, plus an updated Pro$ formula that applies the latest financial metrics.
There will be plenty within the April genetic evaluations to digest. New Feed Efficiency evaluations could usher in an important new focus, that despite low reliabilities in the early going, could have significant economic impact for producers. New proof interpretation tools will help producers understand the expected impact of selection on individual traits and new Type Composites with adjustments to neutralize the impact of Stature, Teat Length and Rear Leg Rear View all make the new proof numbers more highly anticipated than usual. Add the regular annual base adjustments applied in the April run, and we will need some April showers to provide us with a day or two to digest it all!
  Implementation of
Composite Indexes for
Major Type Traits
Discussion in early 2019 at the Open IndustrySessionregardingchanges to the classification scorecard trait Stature to include a new defect called “too tall,” led to a request to have Lactanet examine a move to Composite indexes and to include an adjustment for stature to make each composite “stature neutral.” It’s taken two years (and lots of discussion), but April proofs will see the composite approach introduced alongside the neutralization of stature’s influence for Holstein, Jersey, and Ayrshires.
The concept of composites in essence mimics the classification approach to scoring, where weightings on individual linear trait scores generate the composites. Our genetic evaluations until now have always treated the Major traits (Mammary System, Feet & Legs, Dairy Strength, Rump and Overall Conformation) as individual traits. Going forward we will combine genetic evaluations for the descriptive traits in each section, at specified weights, to form the genetic evaluation for each major type trait. Benefits of composites for Conformation traits include better reflection of current scoring in genetic evaluations and having this same formula applied
moment to the Rump composite; however, further study could lead to an adjustment to neutralize or reduce the influence Stature also has on it. No adjustments are being made to Conformation either, but they are coming in through the adjusted composite indexes for Mammary System and Feet & Legs.
As a result of these adjustments, significant change is expected for many animals especially to older

   44   45   46   47   48