In cattle breeding, the saying goes “You get what you select for”. Another saying is “The birds eventually come home to roost”. Both these saying have come true for the dairy cattle breeding industry over the past seventy years. Breeders selected for ever-increasing milk yield, increased stature and frame and udders held high off the ground. As a result, today, cows produce almost three times more milk, they are about 5-6” taller and weigh 30% more and udder depth, under good management, is not the problem it once was for machine milking.
However, with that focused attention on those attributes came: 1) lower and lower conception in milking cows; 2) less healthy animals of all ages; 3) more difficult calvings followed by less vigor in new borns; 4) an increase in heritable defects; 5) feet and mobility problems in housed animals; and 6) … the list goes on. Unknowingly, at least in Holsteins, the bloodlines used as parents for the next generation, up to now, have carried health and functional problems that breeders have only gradually become aware of.
Change In Breeding Approach
The turning point in the downward slide for an improved functional cow came when breeders said, “That’s Enough”. They were seeing too many on-farm issues that were robbing them of some hard-earned increased profit. In the past couple of decades, breeds, genetic evaluation centers and A.I. organizations have commenced to produce information on calving ease, SCC, fertility, likeability, temperament, milking speed and some more traits. But the breeders’ needs for health information on a genetic basis has been largely ignored. It was said … it could not be addressed.
Breeding the ‘disposable cow’ (aka calve her in once and don’t be concerned if she ever calves again), has become unacceptable because of the current low farm gate milk price, the high cost of rearing replacement cows and the decreased revenue from the sale of breeding stock. Increased labor costs and many other factors also demand that attention be paid to traits long ignored.
Having said that there is good news. Breeds, A.I. organizations, genetic evaluation centers and private breeding companies have gathered on-farm data for health issues and are generating genetic values for health traits. Some of this information has been available and some is coming available now.
Information to Assist with Breeding for Health Traits
In North America, CDCB, Zoetis, CDN and A.I companies have been putting considerable resources into researching and analyzing animal health data. The outcome is genetic indexes for health traits. Some of the ones recently announced are as follows:
CDCB – New Health Traits
Over the past two years CDCB have added genetic indexes for cow livability (LIV) and gestation length (GL) and in April ’18 will be adding the following sire health indexes (Source -New Genetic Evaluations for Health Traits – www.uscdcb.org):
- Displaced Abomasum
- Mastitis Resistance
- Retained Placenta
CDCB/AIPL-USDA is currently doing further research and plans to appropriately incorporate these health indexes into the NM$ formula in the future.
Zoetis – Focuses on Health/Wellness
Zoetis has been publishing sire indexes for WT$ and DWP$ for a while now. Interestingly, it has just announced the addition of genomic-based measurements for three calf-wellness traits – livability, respiratory disease and scours to its Clarifide® Plus service. (Source – Wellness Is Now A Profitable Choice – Clarifide® Plus/Ultra Plus – http://zoetis.com/animal-genetics/dairy/clarifide/clarifide-plus.aspx).
The end result will be an expanded DWP$ index for ranking sires that places the following weights on cow and calf traits:
- Calf Wellness 8%
- Cow Wellness 25%
- Cow Production 32%
- Cow function/Type 10%
- Cow Longevity 19%
- Reproduction 6%
CDN – Health Indexes
In 2016, CDN added a combined health index to its already extensive list of genetic indexes. This combined index is for the following three metabolic diseases (MDR) – clinical ketosis, sub-clinical ketosis and displaced abomasum. Then in Dec ’17 CDN released an additional wellness genetic index for digital dermatitis (DD). All CDN indexes, including the presence of any haplotypes, can be found for individual animal at https://www.cdn.ca-animal-query.
Other Organizations Also Publish Health Indexes
A.I. organizations often publish health/wellness indexes including Semex’s Immunity+® (reference TBV’s article on Immunity+®). All breeders need to do is ask their semen sales rep or go to the A.I. website for health indexes on sires.
For some time now, New Zealand, the Nordic countries and the EU have been publishing genetic indexes for the cows best suited to their environments and for health traits. Breeders interested in knowing more about the genetics for health traits in those regions can search out details by going to their national data sites or Interbull.
What Have Breeders Been Doing – Health Indexes for Most Used Sires
Sire ratings for health/wellness traits are not universally available so, until now, breeders have not been able to eliminate from consideration sires that rank below average for those traits. However, The Bullvine was able to obtain from Holstein US and Holstein Canada the list of sires with the most registered daughters and we thought breeders would be interested in knowing sire averages for the health/wellness traits. We have chosen to study the fifteen proven sires with the most registered daughters as proven sire lists remain relatively constant month to month and they are the ones which breeders have the most information on. The fact is that breeders are now using daughter proven sires only about 35-40% of the time, but the list of sires with only genomic indexes changes monthly and a base group is not as easily identified.
Table 1 – Health Indexes – 15 Most Used Proven US Holstein Sires*
|Trait **||Average Index||Index Range|
|Mastitis Resistance||97||86 – 108|
|Lameness||97||89 – 110|
|Displaced Abomasum||101||88 – 108|
|Retained Placenta||102||92 – 111|
|Ketosis||102||87 – 109|
|Metritis||102||93 – 109|
* Holstein US April ’82 “Registry Activity Bulls”
** Wellness Traits – Zoetis (12/2017) – Average 100 & Std Dev’n 5
A synopsis of Table 1 is that: 1) the most used US proven Holstein sires were below average for both mastitis resistance and lameness; 2) 38% of the time for the six metabolic diseases, the sire rating was below average; and 3) only 17% of the time was the sire ratings in the top 33% (above 105) of the breed. 38% of sire ratings below average and only 17% of sire ratings above +1 standard deviation means that genetic progress is not occurring. US purebred Holstein breeders will need to change their sire selection choices if they plan to genetically improve their herds for metabolic diseases.
Table 2 – Health Indexes – 15 Most Used Proven Canadian Sires*
|Trait**||Average Index||Index Range|
|Mastitis Resistance||105||102 – 111|
|Metabolic Diseases||99||94 – 104|
|Digital Dermatitis||103||97 – 111|
* Based of Holstein Canada 2017 Registrations
** CDN (12/2017) Average 100 & Std Dev’n 5
A synopsis of Table 2 is that: 1) Canada’s most used proven sires were, on average, just below average (99) for metabolic diseases; 2) 18% of the time for the three diseases the sire rating was below average; 3) 31% of the time sire ratings were in the top 33% (above 105) of the breed; and 4) Canadian Holstein breeders have paid attention to mastitis resistance in their sire selections. The picture may not appear to be as negative for purebred Canadian Holstein breeders, but remember that the Canadian stats do not include lameness, metritis and hypocalcemia.
The take home message is that breeders need these new genetic health/wellness indexes to breed an even more profitable cow.
Sires Rank Differently Depending On Total Merit Index
As sire ratings for health/wellness are not universally published and used, The Bullvine thought it would of interest to its readers to compare the top WT$ sires to their indexes for other total merit indexes. Listed below (Table 3) is that comparison.
Table 3 – Sire Index Comparisons – Top 10 WT$ Proven Holstein Sires (12/2017)
A few points stand out from Table 3: 1) Only AltaLeaf is in the top twenty sires for all of WT$, DWP#, TPI and NM$; 2) Penley and Zyke do very well for health/wellness but only make #68 – #100 for TPI and NM$; 3) only three of the top 10 WT$ sires crack the top 100 for TPI; and 4) only half of the top 10 WT$ sires are in the top 100 NM$ sires.
If breeders choose to put more emphasis on health/wellness traits they will need to forego some of the emphasis they have placed on production and type in the past.
The Bullvine Bottom Line
Selection using genetic indexes for health/wellness traits is only in its infancy in North American Holsteins. Of course, the reliabilities for the health/wellness traits will not match (only 2/3 as accurate) the reliabilities for the genetic indexes for production and type. However, breeders will now have information to use in selecting sires for many health/wellness traits.
The Bullvine strongly advises breeders to study the health/wellness traits that their herd needs genetic improvement in and to use only sires that are in the top 25% of the breed for the health/wellness traits they have identified (i.e. above 106 for displaced abomasum).