Breeding for Kappa Casein to Increase Cheese Yield

The Bullvine seldom talks about the processing of milk into product when it comes to writing about the breeding of dairy cattle. We expect it happens even less frequently that dairy cattle breeders consider the yield their processor obtains in products from the milk they ship. The different kappa casein genotypes found in today’s dairy cattle can have a significant effect on the volume and quality of cheese produced from milk. Here are some interesting details that we found from our research on this subject.

The Situation

Dairy cattle are evaluated for their ability to produce the percentage of protein in milk and the total protein yield. Milk processors find that: 1) some milks clot quickly, its cheese is firm and produces the most cheese per unit of milk; 2) some milks clot, but not quickly, and have varying degrees of firmness and produces 10%-15% less cheese, and 3) some milks do not clot. Cheese makers are not prepared to buy milk that fits into the latter category. Studies from Europe and North America have found a strong association between the kappa casein genotype BB and milk that clots quickly, produces firm cheese and has a high volume of cheese yield.

The situation of poor or non-clotting milk came to international attention in the 1970’s when Italian cheese makers were no longer able to make their cheeses from the milk from certain farms. After studying the situation, it was determined that some daughters from North American Holstein sires produced milk that was not desirable for cheese making. In-depth study identified the problem to be with the kappa casein produced by these non-Italian sires’ daughters.

Kappa Casein Alleles

At least nine alleles have been identified for kappa casein. Specifically, three alleles, A, B, and E, dominate in global dairy cattle populations. Initially, it was thought that two alleles, A and B, were the main ones present in dairy cattle. However, a third allele, E, was found to exist approximately 10% of the time. E is the allele associated with the milk that does not clot to make cheese.

Cheese Yield by Genotype

A synopsis of the published findings on kappa casein genotypes follows:

Cheese from the milk of BB cows’ clots 25% faster and is twice as firm as cheese made from AA cow’s milk.
Milk from BB cows produces 1.0- 1.5 lbs (about 10%) more cheese per cwt of milk than milk from AA cows.
Milk from AB cows is about midway between BB and AA cows for clotting speed, firmness, and yield.
Milk from EE cows does not clot and is not suitable for cheese making
Milk from AE cows is also considered by most cheese makers to be unsuitable.
The literature is not informative on the properties of milk from BE cows. There are suggestions that it may be similar to milk from AA cows when it comes to cheese making.
A 1985 study by Okigbo, Richardson, Brown and Ernstrom found that milk with impaired clotting properties was not improved by mixing it with an equal amount of well-clotting milk.

General Stat’s with respect to Kappa Casein

Initially, our focus was on kappa casein relative to North American dairy cows. However, we found interesting information from published studies in Italy, France, Estonia, The Netherlands, Scandinavia, and Turkey. Milk for cheesemaking is important in these countries because from 40% to 75% (Italy) of the national milk is used to make cheese. Some additional facts include:

About 10% of North American Holsteins are BB.
North American Jerseys have a significantly higher percent BB than do Holsteins. Likely the result heavy use of two BB Jersey sires from twenty years ago.
Globally Brown Swiss are reported to be 35% BB.
Holsteins in Europe have between 15% and 23% BB
Water Buffalo are almost 100% BB. India, the world’s largest milk producing country, gets half its milk from Water Buffalo.

What About Current Holstein Sires?

Table 1 is the frequency of occurrence for the kappa casein genotypes for the top North American proven or most used Holstein sires.

Table 1 – Kappa Casein Genotype Profiles for North American Holstein Sires

Grouping	Total Sires	BB	AB	AA	BE	AE	EE
Most Registered Daughters – USA*	20	2	6	4	4	4	0
Most Registered Daughters – Canada**	20	2	8	5	0	5	0
Top Proven TPI Sires ***	20	4	8	6	1	1	0
Top Proven NM$ Sires ***	20	2	7	6	2	3	0
Top Proven CM$ Sires ***	20	2	6	6	2	4	0
Top Proven LPI Sires ***	20	6	6	5	0	3	0
Top Proven Pro$ Sires ***	20	6	6	6	1	1	0
Average (%)		17%	34%	26%	7%	16%	0%

* For time period two weeks prior to April 03, 2017
** Based on registrations in 2016
*** April 2017 Proofs

Some points that should be noted from this table include:

The sires in Table 1 have a higher occurrence of BB (17%) than in the general cow population (10%).
There are no EE sires but the 16% level of AE should concern breeders and A.I studs when it comes to cheese firmness and lost potential yield in the future.
The frequency of BB & AB is higher in the Canadian sire proof groupings than in other groupings.
The overall 38% gene frequency of the B allele gives hope that genetic progress to eliminating E and reducing the A allele should be possible in the not too distant future.

Some BB daughter proven sires that topped or were near the top of the groupings in Table 1 are listed in Table 2.

Table 2 – Leading BB Daughter Proven Sires

Sire	NAAB Code	Sire Stack	Rank
Aikman	250HO01043	Snowman x Baxter x Goldwyn	#2 LPI, #20 Pro$
Aikosnow	200HO03914	Snowman x Baxter x Goldwyn	#4 Pro$, #14 LPI
Balisto	29HO16714	Bookem x Watson x Oman	#20 TPI
Bob	7HO11752	Bookem x Oman x Manat	#8 TPI
Camaro	250HO01109	Epic x Freddie x Lucky Star	#9 LPI, #19 Pro$
Donatello	7HO11525	Robust x Planet x Elegant	#14 US Registered, #14 CM$, #17 NM$
Dragonheart	7HO12111	Epic x Planet x Elegant	#1 Pro$, #4 LPI
Facebook	200HO03753	MOM x Airraid x Shottle	#20 CAN Registered
Impression	200HO00560	Socrates x Potter x Durham	#1 CAN Registered
Living	200HO06573	Epic x MOM x Shottle	#12 Pro$, #19 LPI
Punch	7HO11207	Boxer x Oman x Manat	#13 Pro$, #18 LPI
Rookie	7HO11708	Bookem x Bronco x Shottle	#9 TPI
Trenton	7HO13094	Sterling x Robust x Planet	#9 CM$, #12 NM$

One BB genomically evaluated sire is in the top registered USA sire grouping in Table 1:

Jedi (7HO13250) (Montross x Supersire x Bookem) #8 US Registered

What About Genomic Sires?

With over half of the semen being used coming from genomically evaluated sires it is important to consider this category. In some herds, only genomic sires are used. However, to summarize the kappa casein genotype frequency for this group is not reasonable as many of the top sires on the April 2017 listings are too young to have semen available yet. As well the usual cautions that The Bullvine gives apply do not overuse any one genomically evaluated sire as their indexes range from 55% to 75% REL. Moreover, take into consideration the future inbreeding coefficient of these sires as a breeder may already have those sires close up in their animals’ sire stacks.

Some genomically evaluated Holstein and Jersey sires that are BB for kappa casein that are worthy of breeder consideration include:

Table 3 – High Ranking BB Genomic Evaluated Sires

Sire	NAAB Code	Sire Stack	CM$	NM$	TPI/JPI	LPI	Pro$
Holstein
Achiever	29HO18296	Yoder x Altafrido x Robust	1062	1023	2788	3332	2902
AltaCraig	11HO11749	Stoic x Supersire x Massey	842	806	2643	3188	2498
AltaForever	11HO11821	Silver x Freddie x Obrian	774	746	2642	3313	2767
Baylor	551HO03419	Delta x Bob x Uno	874	846	2735	3379	2722
Cam	7HO13592	Jedi x Moonray x Bookem	893	876	2727	3263	2709
Cardinals	200HO10668	Yoder x McCutchen x Robust	804	785	2682	3108	2155
Galahad	200HO10755	Penmanship x Jacey x McCutchen	732	678	2636	3377	2695
McGuffey	551HO03350	Montross x Robust x Mac	834	820	2683	3199	2657
Medley	29HO18343	Yoder x Balisto x O-Style	986	966	2779	3447	2962
Powerfull-PP	224HO04510	Powerball-P x Supersire x Colt-P	670	635	2462	2962	2225
Selfie	224HO04273	Supershot x Aikman x Larson	749	734	2561	3231	2561
Yale	7HO13328	Yoder x Altafrido x Robust	836	824	2683	3286	2654
Jersey
AltaBlitz	11JE01320	Axis x Kilowatt x Karbala	619	593	173	1803	1701
Charmer	29JE04009	Chili x Dividend x T-Bone	630	588	178	2010	1824
Halt	29JE03989	Harris x Hendrix x Redhot	664	628	187	1911	1744
Joyride	200JE10011	Rufus x Paramunt x First Prize	152	139	48	2014	1712
Torpedo	250JE01456	Santana-P x Fastrack x Nathan	408	390	118	1823	1514
Tyrion	203JE01632	Hulk x Action	782	736	231	1755	1587

Take Home Ideas

The Bullvine offers the following ideas for breeders and breeding industry people to consider:

Cheese Making: In the future, it is entirely possible that cheese processors will not buy milk from Holstein herds that cannot guarantee that their cows are at least a high percentage are BB. Jersey herds and totally BB Holstein herds are likely to be paid a premium for this milk.
Niche or Mainstream: In the next five years breeding to increase the percent of BB females will be niche. However, as more and more milk is used to make cheese selection for the B allele and away from the E allele is likely to be mainstream. Selecting sires on total protein without regards to the kappa casein profile of those sires should become a practice from the past.
Breeding Animals: Breeders and breeding organizations would be well advised to commence selecting for the B allele when it comes to sire and ET donor selection. An achievable objective would be for A.I. studs to only enter BB and AB bulls into stud starting in 2019. Breeders are advised not to flush any females that are EE, AE and perhaps even BE starting in 2019 or before. Breeders need to ask their semen sales reps for a sire’s kappa casein profile before buying semen. Bull kappa casein profiles are not included in CDCB or CDN files but are most often included in A.I. stud electronic bull files or hard copy catalogs.
Research: More research is taking place in many countries of the impact of kappa casein genotype on cheese production. At the University of California (Davis) there are major projects underway on how to use genetic engineering to eliminate the E allele and to fast track changing Holsteins into being BB.

The Bullvine Bottom Line

One characteristic, like kappa casein, cannot rule the breeding, milk production and milk processing industries. However, with a higher and higher percentage of dairy cows’ milk being used to make cheese, breeding for animals with the BB kappa casein genotype can no longer be ignored or thought not to be important. Breeders are advised to ask their semen suppliers for the kappa casein profiles of sires before they purchase semen. Starting immediately sires with EE and AE profiles should be avoided and if the semen is already in the tank then even throwing it out may make good business sense. Because producing females that are EE or AE will delay when premiums may be possible for milk sold for making cheese.