Breeding Worth
New Zealand ranks dairy bulls and cows by Breeding Worth (BW) for their expected ability to breed profitable and efficient replacements. The ranking compares across ages and breeds.
Currently the traits (Breeding Values or BV’s) included in Breeding Worth and their associated economic values are:
Breeding Worth = (Protein x $8.215) + (Milkfat x $1.570) + (Milk Volume x $-0.085) + (Liveweight x $-1.171) + (Fertility x $2.867) + (Residual Survival x $0.043) + (Somatic cell x $-30.001).
Updated February 2010, AEU
In general the higher the BW of the bull the more profit likely to be produced by his offspring. The top bulls in New Zealand are now in the $310-220 BW range. Some care needs to be taken when using this figure, as the economic weights used in its calculation are specifically based on the New Zealand economic environment.
Comparing across breeds
New Zealand’s Animal Evaluation Model ranks animals across breeds.
As Jerseys are generally smaller and produce less milk than Holstein-Friesians, most Jersey sires will have negative values for stature, liveweight and milk volume on an across-breed base. Holstein-Friesians will have unfavourable Daughter Fertility % when comapred to Jerseys and Crossbred bulls. In m
To help you evaluate individual bulls/breeds fairly, LIC has presented Stature, milk litres, liveweight and fertility proofs within breed for its offshore website and catalogues. Breed averages for traits that are markedly different between breeds are indicated in the table below.
Bull Breed Averages
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HOL-FRI
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JERSEY
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KIWICROSS
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AYRSHIRE
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Breeding Worth |
23
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32
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82
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-56
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Milk Volume BV |
684
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-674
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-28
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-22
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Liveweight BV |
56.3
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-62.0
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-6.0
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6.5
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Stature |
1.12
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-1.07
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-0.16
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-0.20
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Fertility BV |
-3.6
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1.5
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1.7
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-6.8
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Calving Difficulty BV |
3.4
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-3.1
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-1.0
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-0.8
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Milkfat BV |
11.0
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-4.4
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10.5
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-10.9
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Protein BV |
17.9
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-11.8
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6.3
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-3.1
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Updated June 2010, AEU
Traits Other than Production (TOP)
The general range for most traits is between -1.00 and +1.00. Bulls with TOP Breeding Values (BV) between -0.30 and +0.30 are not expected to influence much change in the trait.
The descriptors of rump width, capacity and dairy conformation are assessed in relation to the animal’s size. This is different to almost all other major dairying countries and is beneficial because it enables the identification of animals that leave strength, width and desirable frame traits regardless of the animal’s stature (refer to Comparing across breeds).
Farmers score two-year-old heifers for the four traits related to their management at milking time (adaptability to milking, shed temperament and milking speed) and the overall acceptability of the heifers as herd member
(overall opinion).
Fertility % (within breed)
The objective for herd reproductive performance in most New Zealand herds is to achieve high pregnancy rates in a short time period following the planned start of mating, and to maintain calving intervals very close to 365 days.
The fertility BV refers to the expected percentage extra likelihood of a cow to conceive, sustain a pregnancy and calve in the first 42 days of the herd’s calving period. A fertility BV of 8% indicates that 4% more daughters are expected to calve in this period compared to a bull with a BV of 0%.
Total Longevity (days)
A sire transmits half of its longevity BV to its daughters.
Consequently, a bull with a longevity value of +200 days is expected to leave daughters that will last 100 days longer in the average New Zealand herd, than a bull with longevity of zero.
Longevity is a feature of New Zealand dairy animals.
Calving Difficulty %
The calving difficulty BV evaluates the suitability of a bull for use over yearling heifers. This trait has a low heritability, and therefore generally lower reliability. LIC assigns each bull to one of three groupings – Easy < 1.20, Average (between 1.20 and 7.20), Difficult > 7.20).
New Zealand Fat and Protein %
The fat % and protein % are estimates of a sire’s ability to transmit milk components. In a grass-based system the daughter of a bull that transmits a 5.0% fat test, and a cow with 4.0% fat could be expected to test 4.5%.
Percentage New Zealand genetics
Percentage New Zealand genetics indicates the degree of New Zealand bloodline in each sire’s ancestry.
To be classified KiwiFriesian a Holstein-Friesian sire must have more than 50% KiwiFriesian bloodline.
Gestation Length
A Breeding Value to evaluate shorter gestation length to tighten calving patterns when used towards the end of the herd’s mating period. On average we would expect to shorten the gestation by three days using a bull with a gestation length BV of –6.
Once A Day (OAD)
The OAD BV evaluates the tendency of a bull’s progeny to be more efficient in a once a day farming system. The biggest factor in making OAD successful is milking the right cows.
A higher OAD Index is more desirable. As a rule, Jerseys are more efficient in a OAD system.
Somatic Cell Count (SCC)
Somatic cell BV indicates a bull’s tendency to breed daughters that are susceptible to lower or higher somatic cell counts. A score of 0.5 equates to approximate 35,000 extra SCC transmitted to daughters. A negative SCC score is more desirable.
High Input
High input farmers are not just interested in BW. They want animals producing high milksolids, and with good type (especially udder support) to carry the extra milk volume. The High Input index uses information and economic weights appropriate for the average high input system (in New Zealand).
High Input index considers all seven traits in Breeding worth (weighted differently) plus udder overall. Generally, the High Input index places slightly more emphasis on the somatic cell score, and weights almost one-tenth of the index on the udder.
NZAEL Genetic Base
As of June 26, 2010 the New Zealand Animal Evaluation system has changed its genetic base to the group of cows that were born in 2000 (from 1995 base) and that had performance records for all traits in the evaluation system in the dairy season 2002/03.
For the Breeding Worth (BW) index you can expect the reported BW for each animal to be approximately $41 lower prior to this genetic base change.
