The genetic
terminology of filial generations (F)
has been a bit misused on the web concerning breeding-back, and I am guilty of
it as well. While I used an “F” for any crossbred generation, no matter which
genotypic combination, it should only be used when F1, F2, F3… individuals are
mated to each other respectively if you want to use that terminology in a
genetically correct sense.
True
F-cross products are interesting for breeding strategies because they are the
most efficient way to fixate alleles in a more or less controlled way (while
rampant cross combinations end up in genetic chaos) and to watch the Mendelian
rules of inheritance (yes, most of the traits of a living organism are
polygenetic, let us assume that for each of the single loci the Mendelian rules
do apply). An F1 cross has one full set of chromosomes from one parental breed
and one from the other. It has maximum heterozygosity that is possible between
the two breeds, and is only homozygous for traits that are shared by the two
breeds anyway. No matter how good the animal looks, how often you back-cross its
offspring to it, it will not be able to increase the amount of homozygosity in
the herd. Using an F1 bull for a long time can only spread the desired alleles
in the population, but does not stabilize it. An individual that is half-pure
does not have a chance of being homozygous for any of the desired traits except
for those that are already shared by the parental breeds, no matter how good it
looks.
Mating two
F1 individuals to each other (they do not necessarily have to be siblings, but
just be of the same genotype) would theoretically result in a continuum between
the pure versions of the two breeds (how much offspring is necessary to see the
full range of possible trait combinations depends on combinatorics).
A true F2
individual has the chance to be homozygous for desired traits of both breeds,
whereas a back-cross (B, in genetic nomenclature) with one of the founding
breeds, no matter how good it works out, does not – a back-cross will be
homozygous for many traits of the one breed, but for none of the desired ones
of the other. Therefore, a back-cross is not a step forward, while using a true
F2 for the next generations is more efficient than those of any combination, no
matter how good they look.
In a postfrom 2015, I proposed the creation of a stable line using a breeding plan based
on true F-matings. This concept has its practical challenges, and of course
provokes inbreeding. Before I am going to cover the “true F” individuals I was
able to find in the Lippeaue Taurus herd, I want to outline another topic where
I think siblings matings played a role.
Large-horned
Heck cattle
Heck cattle
is extremely variable regarding horn size. I define horn size via two factors:
a) horn length and b) thickness. Both factors vary from rather meagre to very
large in this breed. Some Heck cattle actually have extremely large horns
compared to most other breeds – in effect, looking only at the one end of the
spectrum we see in Heck cattle, one would say this breed is one of the
largest-horned breeds in the world. Just look at individuals like this, this or
this. Why do some Heck cattle have that large horns? Readers familiar with this
topic will know that the Wildgehege Neandertal, one of the most important Heck
cattle breeding sites after World War II, used a half-Heck cattle half-Watussi
cow in the 1950s for breeding. Because it was only one individual half a
century ago, you barely recognize Watussi influence in modern Heck cattle
(except for individuals like that for example, if you have an eye for it). But
they kept on selecting for large horns, and therefore many of the Heck cattle
of the Neandertal lineage have respectable horns. Still not that huge, however.
Walter Frisch,
who had been breeding Heck cattle for more than two decades, probably created
the Heck cattle lineage with the best horns in terms of aurochs-likeness (go here for more on this lineage). He
consciously used inbreeding in order to stabilize desired traits (I assume that
the focus was mainly on horns), including parent-offspring matings but of
course also siblings matings.
Horn size,
as a quantitative trait, is very likely based on many different gene loci that
complement and/or summarize each other. The aurochs had a set of wildtype alleles
on these loci that produced the horn dimensions it had. Domestic cattle most
likely have mutations on these loci (some breeds perhaps only on some of them,
others maybe on all) that either shrink horn size down in most cases, or in
rare cases, augment it. I am not aware of any work on the genetic background of
horn size, so my assumptions are just based on general basics – I’d be very
grateful if someone discovered material on this topic and would direct it to
me.
In any
case, very large-horned breeds such as Watussi must have at least one or two
alleles that cause those super-large horns. I cannot say whether these are wild
type or not (the fact that their horns are larger than in the aurochs does not
rule out that these alleles are wild type, f.e. if there were other loci whose
wild type alleles normally counteract the super-growth of those horns that are mutated
in the very large horned breeds). The fact that there are occasionally very
large-horned Heck cattle with horns as thick as in Watussi implies to me that
the alleles for such dimensions are probably recessive or incompletely
dominant, otherwise there would be sequences of individuals which constantly
display and pass on huge horns. Those alleles are probably floating around in
the Neandertal and Wörth lineage heterozygously. Inbreeding, and especially
siblings matings, probably lead to the more or less fixation of alleles for
rather large horns in the Wörth lineage (though not completely, please read on)
and occasionally even those that cause a very large-horned phenotype in Watussi
become fixed homozygous in an individual. There are two examples in the former
Wörth lineage that I know of: the bull Arturo and the cow Erni. Both are the
result of siblings matings. In 2013, there was a Heck cow on the island which
had rather small and thin horns, quite unlike the rest of the herd. Walter
Frisch told me such individuals still pop out on occasion just like those with
the oversized horns. It would be interesting to know if those very small horned
members of the lineage are the result of siblings matings as well.
“True F”
individuals in the Lippeaue population
Once again
I take the Lippeaue population as my study subject. It is the herd I know best
by far; I can trace down the identity and descent of almost all animals, and know
what they look(ed) like thanks to stock lists and a photo archive I was
provided by Margret Bunzel-Drüke and Matthias Scharf from the ABU. They use(d)
only three to four breeds, what makes it comparably easy to comprehend the
diversity of breed combinations and phenotypes. They have been breeding for
more than twenty years now, what makes it the longest-lasting active cross-breeding
project at the moment and therefore their herd has many of the possible
combinations of the four founding breeds and some rather progressed individuals
(the youngest individuals should be of the sixth cross generation by now). This
alone makes the herd very insightful. And, furthermore, it is a very enjoyable
fact that many of the Lippeaue Taurus cattle indeed look very satisfying.
I would
love to have the same opportunities with the TaurOs herds, especially as ever
more and more cross combinations and grown crossbreed animals appear on the
scene, but I have no personal contact to the TaurOs Project and therefore have limited
possibilities on this project.
Using the
material I have I searched for “true F” individuals of various genotypes in the
Lippeaue population, also including animals that have been selected out or sold
to other locations.
With the exception of Londo's, all photos are courtesy of Matthias Scharf, so please do not replicate without permission.
With the exception of Londo's, all photos are courtesy of Matthias Scharf, so please do not replicate without permission.
Heck x Sayaguesa
A rather
good Heck x Sayaguesa bull (Lucio) was used as a breeding bull on several sub-herds
in the Lippeaue for many years, grazing alongside good cows like Lerida of the
same combination. Consequently, there were a number of true F2 animals of that
combination.
Leila, a
daughter of Lucio and Locusta, was one of these. She seemingly looked quite
good overall, although her horns were not satisfying in terms of curvature and
volume. She left a number of descendants in the herd that are still present in
the current population.
 |
| Leila |
Lippe, a
daughter of Lucio and Lerida, was quite good in terms of body and skull shape.
She had (or has, she did not stay for long in the herd and I do not know her
fate) a powerful shiny black coat colour, which is – although rather aesthetic
to me – of course not desirable for a cow. What would be excusable if she had
good horns, but for some reason she happened to have tiny horns that resemble
those of Chianina a lot. This is surprising, as neither their founding Heck
cattle nor Sayaguesa nor F1 crosses of that combination have such small horns.
One explanation might be that both breeds have alleles that shrink down horn
size but on different loci, and only F2 and subsequent combinations can be
homozygous for both loci and display that small horn size. It is just a
theoretic assumption as the genetic background of horn size apparently is not
studied.
She did not
leave descendants that I know of.
 |
| Lippe |
Loreley II
was a fullblood sister of Lippe, but did not look that convincing (based on the
photos I have), that is why I found her among the individuals that where
selected out too. Her horns were not that good and she has no sexual
dichromatism either, plus a white spot on the belly. The body shape and
proportions look good, but she is rather young on the photos. She did not leave
a track in the Lippeaue population.
 |
| Loreley II |
Luxus was a
fullblood brother of Leila. His trunk looks rather elongated on the photos, the
head was short and the horns comparably small and not much inwards-curving. But
his overall impression was not that bad as his colour was accurate, the body
slim and the backline curved, so he was used as a breeding bull at Disselmersch
(one of the sub-herds) for some time, and produced four descendants, of which
none were kept for long.
 |
| Luxus; the other photos don't show this saddle |
Lumumba was
a son of Lucio and Lerida. It seems like he looked average, although his rump
was rather heavy at the age of 2 already.
 |
| Lumumba |
Heck x Chianina
I was
unable to find true F2 for this combination. The reason for that is that the
ABU only used one half-Chianina bull for breeding, Luca, at Hellinghauser
Mersch, where there were no half-Chianina cows. A pity, it would have been
interesting to see F2 of this combination.
(Heck x Chianina) x Sayaguesa
This
combination seems to be the right mix to me – all three breeds are contained,
and in an advantageous quantitative relation. This combination also includes
all important aurochs traits. Note that counting this three-breed-combination
as a genotype requires that these F1 are actually second-generation crosses,
not first-generation. Lamarck, for example, is a second-generation cross bull but
F1 for this genotype.
Londo is
the best one of the true F2 I found for this combination. He is the son of
Lamarck and 84 024, fullblood siblings. He resembles his father (which I is
still one of my favourite Taurus bulls of all) a lot, has a curved back line, thick
horns of an acceptable curvature and a correct colour. In contrast to his
father, he has a chance of being homozygous for all these good traits, but
unfortunately that also goes for the undesirable traits – he is smaller than
his father and has a comparably longish trunk. Nevertheless, I still think this
bull is qualitative because of its descent and looks, and it is currently used
as a breeding bull at Klostermersch-Süd. Recently a male calf he produced with
 |
| Londo |
42 621 is
the daughter of Lamarck and Loxia. Loxia is/was a very good-looking cow, a
full-blood sister of Lamarck. 42 621, however, did not work out well – diluted
coat, short snout, horns that did not look promising. Genetics work by
coincidence. Personally, I would have kept Loxia in the population, and in the
same herd with Lamarck. This siblings couple had the potential for really good
F2 individuals. I don’t know why Loxia was removed from the herd as she looked really
good, perhaps her behaviour was un-suited or other reasons.
 |
| 42 621 |
42 634 was
the daughter of Lamarck and Laola, another quite good cow. 42 632 however,
could have been better, as the horns were meagre, the colour had a slight
greyish tint and the hips where higher than the shoulders. She was slaughtered
because she was rather aggressive as well.
 |
| 42 634 |
Her
fullblood sister 79 808 worked out better in terms of body shape and also
horns. Her colour is very faint as well, but in another way than in 42 621.
While the coat of the latter was rather greyish, i.e. the amount of red pigment
was reduced, 79 808 seems to have a reduced amount of black pigment, hence the
beige colour like in Luca. So we are probably dealing with two different loci
here. She was removed this year and left no descendants as she was (or is)
quite young. Interestingly, her horns show the same kind of minor asymmetry
that is also seen in Lamarck and some Heck cattle of the Wörth lineage.
 |
| 79 808 |
79 844 is
the only other F2 bull of this combination that I know of. Another son of
Lamarck and Laola. He has a light colour saddle, but that saddle is not of such
a faint colour that I would say it is the result of a dilution factor, it can
also be a sign of lessened sexual dichromatism. But its face shows light
markings that are typical for Chianina-influenced animals that show diluted
colour variants. His body and head shape was not different from that of the
other young bulls at Hellinghauser Mersch at this time (as far as I can tell), and
its horns might have even become good or at least large, but its colour was
obviously unsatisfying so he was removed in 2014 or 2015.
 |
| 79 844 |
I have to
conclude that Londo is the only really satisfying true F2 of that combination
(despite its size) – well, genetics work by chance and five individuals are a
small sample size. But these five individuals tell us interesting things about
the parents. With the exception of Londo, all of Lamarcks’ F2 offspring have a
more or less diluted coat. Lamarck himself is not diluted; it might be that his
red pigmentation is reduced but it is not visible due to his solid black
colour, but his eel stripe and forelocks show a powerful yellow-red colour, so
I do not think so. Laola, 84 024 and Loxia definitely have a non-diluted wild
type colour phenotype. So those factors that caused a faint or diluted colour
in the F2 offspring must be recessive, and furthermore must be present heterozygously
in both parents of the diluted offspring. And since the quality of the dilution
is different between some of the animals, as outlined above, we might be
dealing with two loci instead of one. While the cows must not necessarily have
one allele for each of those two, Lamarck probably has one dilution allele on
both of these two loci. That’s bad luck considering that the chance of him
having one dilution allele from its Chianina grandparent is only 25% and that
he is one of the phenotypically best Taurus bulls of all. But I think that does
not dramatically decrease his value as a breeding bull at this stage,
considering that those dilution alleles are probably widely distributed in the
population anyway.
Lamarck has
been moved from Hellinghauser Mersch to Klostermersch-Nord, where there are no
cows of the same combination. But the new breeding bull at Hellinghauser
Mersch, the huge 42 623, is of the same combination as Lamarck and so he can
produce some more true F2 together with Laola and 84 024. From a genetic point
of view, using more good F2 bulls should help progressing the herd – continuing
to use half-pure bulls as breeding bulls will not effectively stabilize the
population on long-term sight while a F2 as a chance of being homozygous for
several desired loci of different founding breeds at the same time. The
subsequent goal should be to achieve a good F3 bull by placing the F2 with cows
of the same F-generation and genotype, which then is at least as or even more
stable than its father, and to use this as a new breeding bull and so further.
I think this could help to speed up the breeding process in a crossbreeding
herd as progressed as the Lippeaue population currently is, more so than using
half-pure bulls or than bulls of random combinations.