An Ounce of Breeding is Worth a Ton of Feeding
Breeding Worth (BW) is the index used to rank cows and bulls on their expected ability to breed profitable, efficient replacements.
Herds that are more resilient to farm system changes and illness are going to make you more profit as their rates of production vs input are likely to be higher and more reliable. The Breeding Worth Index helps farmers achieve a genetically strong herd and benefit from greater genetic gains faster, which means you can increase your farm profit more and more each year.
Effective emphasis on individual traits within BW.
What is Breeding Worth?
Our National Breeding Objective (NBO) in New Zealand is to breed dairy cows that efficiently convert feed into profit. We rank cows and bulls on their ability to meet this objective using the index known as Breeding Worth (BW).
There are nine traits included in BW that have been identified as having a direct economic value to the NZ dairy sector. These traits can be categorised as either 'Production efficiency' traits or 'Robustness' traits.
The effective emphasis of the nine individual traits within BW are split between 64% production efficiency traits and 36% robustness traits (see pie chart). Updating the liveweight evaluation and adding udders to BW has resulted in a slight reduction in the emphasis on production efficiency traits and an increase in the emphasis on robustness traits.
How Breeding Worth impacts your herd's value and farm profit
Herd quality has a direct impact on a farmer's profitability. Herds that are more resilient to farm system changes and illness are going to make you more profit as their rates of production vs input are likely to be higher and more reliable.
The Breeding Worth Index helps farmers achieve a genetically strong herd and benefit from greater genetic gains faster, which means you can increase your farm profit more and more each year.
Your breeding plan will set you up for future seasons and have a lasting impact on your herd. That's where Breeding Worth (BW) can help you make informed decisions to improve your herd's profit through genetic gain.
The information you choose to focus on will depend on what your herd objective is. While you won't see changes immediately in your herd, the decisions you make now will have an impact on your production for several seasons. Knowing you have accurate and meaningful data in Breeding Worth is critical to aid your decision-making.
Six steps to a high BW herd Steps during mating to improve BW
Production efficiency traits
Milk protein and milk fat yield
Cows that produce more protein and fat will bring in more income for the dairy farm business.
Milk volume
Cows that produce the same quantities of fat and protein but with more volume incur costs to the dairy farm business.
Liveweight
Included in BW as the 'efficiency' part of production efficiency. There is a positive correlation between liveweight and milk production and between liveweight and feed requirements for maintenance and growth. If not included, selection would lead to successive generations getting heavier and the costs to feed these heavier cows would increase.
Robustness traits
Somatic cell
Cows with lower somatic cell counts have better survival, lower costs due to mastitis, and fewer penalties due to bulk somatic cell count being lower.
Fertility
More fertile cows calve earlier and therefore typically have longer lactations before drying off. Fertile cows have better longevity than less fertile cows.
Functional survival
Cows that fail for functional reasons such as udder breakdown have reduced longevity and lead to increased costs associated with rearing more replacements. Having more mature cows in the herd (the engine room of the herd) will positively impact profitability.
Body condition score
Cows that maintain condition easily can be dried off later. This increases lactation length and boosts potential production and profit, compared with cows that lose condition easily.
Udder overall
Cows with poor udder conformation add costs to the farm system due to an increased risk of developing mastitis or being culled due to their udder failing.
How Breeding Worth is calculated
BW is calculated by combining breeding values with the appropriate economic values for each trait and adding them all together.
Breeding Values (BV): An estimate of a cow or bull's genetic merit for a trait. e.g. Will his or her daughters produce milk solids efficiently, and be robust herd members?
Economic Values (EV): An estimate of the future dollar value of a unit change in each trait to a NZ dairy farmer.
BW is expressed as $ net farm income per 5 tonnes of dry matter. A bull whose BW is $300 is expected to produce daughters that are on average $150 (half of the bull's BW) more profitable than a bull whose BW is $0. Importantly, animals can be compared using BW across different breeds, herds and ages.
How Breeding Worth impacts your herd value and farm profit
Herd quality has a direct impact on a farmer's profitability. Herds that are more resilient to farm system changes and illness are going to make you more profit as their rates of production vs input are likely to be higher and more reliable.
The Breeding Worth Index helps farmers achieve a genetically strong herd and benefit from greater genetic gains faster, which means you can increase your farm profit more and more each year.
Your breeding plan will set you up for future seasons and have a lasting impact in your herd. That's where Breeding Worth (BW) can help you make informed decisions to improve your herd's profit through genetic gain.
The information you choose to focus on will depend on what your herd objective is. While you won't see changes immediately in your herd, the decisions you make now will have an impact on your production for several seasons. Knowing you have accurate and meaningful data in Breeding Worth is critical to aid your decision making.
Reliability
The other number that is reported alongside BW is reliability. Reliability measures how much information has contributed to the BW evaluation for that animal. We show reliability on a scale of 0 to 100%, with reliabilities closer to 100% representing more information on progeny and ancestors being available for that bull.
High-reliability bulls are unlikely to have large shifts in their BW when more daughters are added. In contrast, bulls with lower reliabilities are more likely to have large shifts in their BW as we add more daughters. Learn more about reliability.
Delving deeper - no two bulls are the same
Two bulls can have exactly the same BW but will have reached it through very different strengths. The best bull for your herd is one that fits your herd breeding objective.
Source: https://www.dairynz.co.nz/animal/animal-evaluation/interpreting-the-info/breeding-worth/
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