以下藏獒毛色遺傳理論可以印證在絕大部分的藏獒繁殖上,只有極少部份與理論有所出入,與獒友分享
藏獒毛色问题
Coat Color Genetics in Tibetan Mastiffs
Have you ever been to a show that sports Tibetan Mastiffs appearing in a variety of colors and asked yourself where these colors come from, or how a breeder can predict what colors will appear in a given litter? Well, hopefully, this article and some color photos will begin to shed some light on this colorful subject. Before we get to the fun stuff, however, we will have to review a little genetics.
你看过藏獒的展赛吗，看着那些参赛的藏獒被毛的各样颜色，你一定会问这些颜色从哪来或者繁育者怎么预测即将出生的一窝獒的颜色？好，希望此文章和一些彩图能够给解决这个问题带来益处。在我们进入正题前，我们必须掌握一些遗传学（的知识）。
Most vertebrates, including dogs, have two copies of every chromosome (except sex chromosomes). Since genes are part of the chromosomes, this means that there are two copies of every gene present in every cell of every dog. However, the two copies do not have to be identical. They can be different versions (alleles) of the same gene. For example one could be an allele for Black coat and one for Gold coat. Hmmm, this must be a Black and Gold spotted dog! No, because some alleles are dominant to others. Since Black is dominant to Gold, this dog will appear as solid Black.
大多数脊椎动物，包括狗，（他们的）染色体是对生的（性染色体除外）。[注1] 鉴于基因是染色体中的一些片段，这就得出每只狗的每一个细胞内（的染色体上）都有着两套基因。[注2] 然而，这两套基因却不一定是相同的。他们可以是不同的等位基因版本[注3]。例如：（在1个染色体上的两个基因）它可以一个黑色基因另一个是金色基因。恩，这不意味着它就是黑-金斑点了吗？不！因为有些等位基因对于别的（隐性基因）是显性的。由于（决定）黑（色的基因）对于（决定）金（色的基因）是显性的，所以这只獒应该是纯黑的。
译者注：
注1：染色体的个数和染色体上所载的遗传信息，决定物种的性质，性别和特征。如：人有23条染色体，其中第23条即X/Y染色体，决定性别。所有染色体，可以通过动物的任意一个细胞，在高倍电子显微镜下观察。
注2：基因是染色体上一些呈直线排列的遗传单位。由于来自父母双方的影响，每一对藏獒的染色体分别带有来自父亲和母亲的基因。
注3：通俗的说：基因是一种序列。严谨的说：基因是编码有功能的蛋白质多肽链或RNA所必须的全部核酸序列（通常是DNA的序列）。因此，基因是不同的。
Although the above example shows a simple relationship between two alleles located at one gene locus, coat color in dogs is ultimately quite complicated and not fully understood. Many genes, some of which have more than two allele choices, control the variety of colors and patterns seen in canine coat color. The many different genes interact by intricate rules, to create the final coat.
尽管上述例子显示了在（染色体上）同一个基因位置的等位基因的简单关系，但最终决定狗的被毛颜色（的因素）是很复杂的，尚不能（为我们所）完全理解。很多基因，（他们可以）控制犬科动物的复杂的被毛颜色和图案，并最终决定犬的被毛，而（这些基因中）有些基因要多于两个的等位基因。（正是）这些不同的又遵循着难以被理解的规律相互作用的基因创造了（藏獒）最终的毛色。
For the sake of discussion, each gene locus and all the alleles related to coat color are given alphabetical designations. Dominant alleles are shown in capital letters and recessive alleles are given in lower case letters. For the purposes of this article, only those loci and alleles seen in the Tibetan Mastiff will be discussed. Given that this breed is so colorful, that happens to be most of them.
为了讨论方便，每一个基因位置和与之相关的被毛（颜色）都按字母顺序给出，显性基因用大写字母隐性基因用小写字母。出于本文的目的（是说明藏獒颜色的决定因素），只有那些跟藏獒相关的基因和位置才在本文讨论。假定（藏獒）这个品种就是这么多颜色，（实际情况也）绝大多数都是如此。
Okay, back to our example. The gene locus involved in the example is the Agouti, or A locus. Three alleles of this gene are found in the Tibetan Mastiff: the allele for Black, designated A; the allele for Gold Ay; and the allele for Black and Tan, designated at. These alleles are given here in order of dominance, where Black is the most dominant (epistatic) and Black and Tan is the most recessive (hypostatic). Although there are three different alleles that are found in the Tibetan Mastiff breed, any given dog can only carry one or two of the three; two copies of the same allele, or two different alleles.
好了，回到我们上边的例子。例子里面提到的基因位于（染色体上的）Agouti（位置），也称“A位基因”。[注4] 现在有三种（决定藏獒毛色的）基因已经被发现了：黑色基因，标为A；金色基因，标为Ay；黑+栗色（即铁包金），标为at。这些基因按显性次序给出，其中，黑色最显性（强势）而黑+栗色最隐性（弱势）。尽管在藏獒这个品种发现了这三种基因，任何一只藏獒只可能携带这三种的基因中的两种或者一种：两份都是同样的，或者两份不一样的。
注4：为了方便中文读者理解，改译为“A位基因”。同以下决定黑色的A没有任何联系。
Why two? Well, every dog has two sets of chromosomes (they get one set from each parent) and each set of chromosomes contains one copy of each gene. Hence every dog has two copies of each gene, one from each parent. In our example, the dog is A/Ay. This is written so that we see both alleles, Black and Gold, with the most epistatic allele, Black, written first. Remember, this dog appears Black, but so would a dog that is A/A or A/at. Thus, if a dog appears Black (image 1), we may have no idea what the second allele is until we breed that dog and find out what is passed to the offspring. Likewise, dogs that are Ay/Ay or Ay/at will appear Gold (image 3), as Gold is epistatic to Black and Tan. Only when a dog is at/at does it appear Black and Tan (image 6).
为什么是两个？因为每只藏獒都有来自父母的2套染色体（从父母各继承一套）；而每套中，都包含一份与其来源相同的基因。{注5] 也就是每一只藏獒有2个分别来自其父母的（决定毛色的）基因。在我们的例子里，是A/Ay。这么写我们可以把两个基因都看到，黑和金，最强势的基因（黑）写在前面。这条狗表现出黑色，不过同样是黑色的狗也可以是A/A,A/at。因此，如果一条狗表现是黑色的被毛（图1），我们不知道它的第二个基因是什么，不过我们可以用它来繁殖，看他传给后代的是什么来推断知道。同理可知：一条金色的狗基因型可能是Ay/Ay和Ay/at（图3）,因为金色对铁包金显性，只有at/at的基因型的狗才会是铁包金（图6）。
{注5]：所谓两套是指来自父亲母亲。所谓N个是指染色体个数。
What we call “Gold” actually ranges in color from Cream (image 2) to deep Red (image 4), with the precise shade being determined by modifying genes. These modifying genes are called rufous polygenes and act like, well, a collection of checkers (lets say red and white checkers). For example, if a dog has mostly red checkers in its collection, it will appear Red. If a dog has mostly white checkers, it will appear Cream, and if a dog has a balance of red and white checkers, it will appear Gold. Each puppy receives a handful of checkers from each parent, so Red puppies are unlikely to come from two Cream parents and vice versa. These same genes work to determine the shade of tan on Black and Tan dogs. The dogs shown in images 5, 6, and 7, are all Black and Tan (determined by the A locus), but the tan varies considerably. So, as in the example above, Black and Red-Tan puppies are unlikely to come from parents that are Cream and/or Black and Cream-Tan.
以上，我们所说的金色，事实上（颜色的范围）可以从奶酪色到深红色，颜色的深浅由一组叫做“修改基因”的基因决定。这些修改基因叫做红褐色因子群，它们的控制作用就象一个棋子组合（红和白的跳棋子）。例如：如果在它的因子群里绝大多数是红色的棋子，它就会显示出红色。如果它的因子群里面绝大多数是白的棋子，它的被毛就会是奶酪色。如果红白相当，那就显示出金色。（这类藏獒的）每只小狗都从父母那里接受一定数量的红色因子群，所以红色的小狗不大可能是两只奶酪色的父母所出；反之亦然。这样的基因作用也决定了铁包金狗的金色部分的颜色深浅。图5、6、7都是铁包金（甲位置的基因决定），不过金色部分变化相当大。同理，在上面的例子里，铁包金（深红）不大可能出自两条金色（奶酪色）、铁包金（奶酪色）的父母。
So far, the discussion has focused solely on dogs that have what is called full pigmentation. That is, their genetic makeup allows them to develop all colors to their fullest extent: pitch blacks and bright reds, golds, and creams. There are some genes whose effect is to dilute the pigmentation. In other words, whatever A locus alleles the dog has will be expressed as expected, but the pigmentation will be diluted, even in the eyes and on the nose leather. In the Tibetan Mastiff, two different genes cause dilution effects. Each of these genes has only a dominant and one recessive allele.
到现在为止，我们仅仅讨论了有全色的狗，就是说，它们的基因决定它们可以显示出最完整的颜色：沥青般的黑色、亮丽的红、金、奶酪色。除此以外，（在藏獒的染色体中）还有一些基因，它们可以稀释这些颜色。换言之，不管甲位置的基因让狗显示出什么颜色，这些颜色都可能会被稀释；（这些基因）甚至（可以控制）稀释眼睛和鼻子皮的颜色。对藏獒来说，有两种基因导致稀释，（他们位于染色体不同位置）。
The first of these genes is the Dilute, or D locus. The dominant allele D is necessary for full pigmentation. The effect of the recessive allele d when homozygous (two identical alleles in the same dog), is to dilute Black coat and nose and eye pigment toward Blue/Grey. Although this gene is completely separate from the A locus, there is an interaction that produces the final color of the dog. So, if a dog is A/-, d/d (where the dash represents any allele choice) it will appear Blue/Grey (image 8). If a dog is at/at, d/d then it will appear Blue/Gray and Tan (image 9).
第一个是Dilute，或者说“D位基因”。这个显性的D位基因对表现出全色是必须的；双隐性的时候，由于隐性基因的作用，稀释黑被毛和鼻子眼睛的颜色，让它们呈现蓝灰色。尽管这个基因（在染色体的位置上）完全跟A位基因分开，但它们之间的一种相互作用造就了狗的最终颜色。因此，一只狗的基因如果是A/-,d/d（横杠“-”表示可以是任意一种类型的毛色基因）那这只狗就显示出蓝灰色（图8），如果一只狗的基因是at/at,d/d，那么这只狗就显示蓝灰包金（图9）。
The second gene that serves to dilute coat and pigment is the Brown, or B locus. This gene works the same way as the D locus. That is, when both copies of the B gene are recessive (b), in this case the Black coloration fades to Chocolate/Brown. Again, this gene is completely separate from the A locus, but the interaction of the two loci determines the final color of the dog. Thus, if a dog is A/-, b/b it will appear Chocolate/Brown (image 10). If a dog is at/at, b/b it will appear Chocolate/Brown and Tan (image 11). Again, one dominant allele B is necessary in any dog to get the normal black pigment.
第二个起稀释被毛颜色作用的基因是Brown，称为“B位基因”。这种基因的作用方式跟D位基因一样。就是说：当两份B位基因都是隐性的时候起作用，这种情况下它把黑色变成巧克力褐色。这个基因也完全独立于A位基因，也是它们之间的相互作用决定了狗的最终颜色。因此，如果一只狗的基因型是A/-,b/b,这只狗就会出现巧克力色或者褐色（图10），如果一只狗是at/at，b/b，它就会出现巧克力褐色包金（图11）。同样，有B位基因的显性基因狗就会显示正常的黑色。
Finally, a dog can receive a pair of recessive alleles at both the D and B loci. Although, for the moment, and to our best knowledge, the Western world has not produced a Tibetan Mastiff with this genetic makeup, it is thought that one would appear somewhat like a Weimaraner in color. The TMCA currently refers to this color as Double Dilute. Of course, this would dilute the black coat and pigment in Black and Tan dogs as well, so there could be dogs that can appear as Double Dilute and Tan (at/at, b/b, d/d).
最后，只有在理论上藏獒可以在D位基因和B位基因置都是隐性基因，然而到现在为止，就我们所知道的，西方国家还没有培育出这样基因结构的藏獒，有人猜测可能会出现德国威玛猎狗似的颜色。TMCA当前把这样的颜色叫双稀释，当然，这样的机理可以作用于黑色獒也可以作用于铁包金中的黑色部分造就成双稀释色包金（at/at, b/b, d/d)。
Gold dogs with dilution are a little more complicated. They still appear gold, but appear more washed-out than normal, and their nose leather may appear Blue/Grey, Chocolate/Brown, or some muddy combination of the two. These dogs are Ay/-, d/d (where the dash represents either Ay or at), Ay/-, b/b, or Ay/-, b/b, d/d. The TMCA refers to ALL of these colors as Gold Dilute (image 12), as determining exactly which dilutions are at work may be difficult.
金色狗的稀释就要复杂一些，它们仍然显示金色，但跟正常颜色相比有点“洗过”的感觉，它们的鼻子皮肤可能会显示蓝灰色，巧克力褐色，或者有些是两种颜色的组合。这些狗的基因型是Ay/-，d/d（里面“-”代表Ay或者at），Ay/-,b/b或者Ay/-，b/b,d/d（图12）。TMCA统称所有这些颜色为金色减色，因为要想知道哪些基因起稀释作用很困难。[注6]
注6：因为引起色泽变化的还有前面提到的因子群。
So far, so good, and the above mechanisms are well established in the dog world, but what follows is not. There is one type of Black Tibetan Mastiff that is turning up more frequently in American litters. Breedings of two Black and Tan dogs (at/at mated with at/at) are yielding puppies that are all Black. This is completely unexpected! Since the allele for Black, A, is dominant to Black and Tan, at, neither of the parents could be carrying Black, or that dog would appear Black itself. So, some other explanation must exist for these dogs to appear solid Black. Breeders have found that when bred, these dogs produce as if they were Black and Tan, not as Black. So, genetically, they are just what one would expect, at/at. One explanation for the conundrum would be that there is a recessive modifying gene present that completely masks the tan, yielding a Black dog. In some cases, a few tan hairs develop between the toes or under the tail, and over time may become more traditional in patterning. However, at birth, these Black pups are indistinguishable from the true Black colored puppies (A/-). The TMCA is now referring to these as Masked Black and Tans and denotes them in registration as Black (and Tan). A Black (and Tan) female is seen in image 13. These Masked Black and Tans can also appear in matings of Gold dogs and the explanation is exactly the same. Of course, this parenthetical descriptor also applies to dogs masked with any of the dilute colors: Blue/Grey (and Tan), Chocolate/Brown (and Tan), and Double Dilute (and Tan).
到现在为止，上述的（颜色决定）机制在藏獒界运行良好，但以下例子就不是了。有一种黑色獒在美国繁殖的藏獒里面常出现。让两只铁包金藏獒繁殖幼崽（都带有确切的at/at），出生的全是黑色的，完全出乎意料！因为黑色的基因型是A对铁包金at显性，两只种獒都不可能携带基因A，否则种獒就会呈现黑色。对这些黑色小狗的出现必然存在（关于如何确定毛色的）另一个解释。繁育者发现这些小狗养大后，它们（的毛色）就是铁包金的。因此，在基因上，它们就只能是人们预期的一样：at/at。一个对此的解释就是有隐性的“修改基因”把金色遮盖，使他们显示黑色。（此外，）在有些时候，这种藏獒的脚趾间和尾巴下面会出现一些金毛，随时间长大后，会显现出正常的（铁包金）样子。但刚出生时，这些黑狗跟真正的A/-的黑狗没什么两样。TMCA把这样的狗称做掩式铁包金，注册时称做黑（铁包金）（英文是：Black(and Tan)）图13是一只黑（铁包金）母狗。这种遮盖现象也会在用两只金色狗交配的后代出现，解释跟前面的一样。当然，父辈遗传的稀释因子也会作用于掩式铁包金的狗：蓝灰（铁包金），巧克力褐色（铁包金），双稀释（铁包金）。
For clarity, and to move us to the fun part, a couple of genetic word definitions will help; the first is phenotype. This refers to what is seen. A Tibetan Mastiff’s color phenotype may be Black, for example, or Black and Tan. The second word is genotype, which describes the genetic recipe (our alphabet soup) carried by that dog. For example, a Tibetan Mastiff genotype may be A/at (which may appear as a Black phenotype), or at/at (which may appear as a Black and Tan phenotype).
为了清楚说明下述内容，有两个遗传学概念会有所帮助。第一个是表型，是指从外观上看到的样子。例如：一只藏獒的颜色表型可以是黑色或铁包金。第二个是是基因型，是指控制表型表达的基因的类型（用字母表示）。例如：一只藏獒的基因型可以是A/at（从表型上看它是黑色的），或者at/at（从表型上看它是铁包金的）。
Oh yeah, here is the fun part. Ready? 好，现在是有意思的部分，（你）准备好了吗？
Let’s look at an illustration using dogs that are phenotypically Black (not including the masked Black and Tans), that is, these are Black dogs with no tan points, although they may have markings like white on the chest (to be discussed in a future article). Keep in mind that Black dogs must have at least one copy of the dominant allele A. Now for this dog to be full-pigmented Black, it must also have at least one dominant allele D and at least one dominant allele B. If we do not know any more than how the dog appears, the genotype of this dog can then be written, A/-, B/-, D/- (as alleles represented by the dashes cannot change the phenotype -- how the dog appears). So, we cannot tell by looking at the dog whether it is carrying any or all of the recessive alleles. Only breeding will reveal whether this dog is carrying the Gold allele (Ay), the Black and Tan allele (at), the recessive Blue/Grey allele (d), or the recessive Chocolate/Brown allele (b).
让我们用典型黑色（不是掩式铁包金）来做个说明，就是说，他们没有金色斑点，尽管他们可能有白色胸毛（在以后的文章中讨论）。记住黑色的必然有至少一分A基因（译者：此处A指决定毛色的A基因，不是A位基因。）。这只黑色是全色的，那它必然有B位基因和D位基因。如果我们对这狗的外观并不知道更多，这个狗的基因型就是A/-,B/-,D/-（不管“-”代表什么基因都不能改变狗的外观）因此我们不能仅靠它的外观说出这狗携带的其他隐形基因。只有靠让它繁殖才能确定它携带的隐性基因是：（决定毛色的）金色基因(Ay)，（决定包色的）铁包金基因(at)，（影响颜色显示的，使之成为）蓝/灰色的隐性D位基因(d)，（影响颜色显示的，使之成为）巧克力/棕色的隐性B位基因(b)，四个中的哪些。
So, how does a breeder find out the exact genotypes of his/her breeding stock?
那么，繁育者怎么知道他用来繁殖的狗是哪种基因型呢？
The first thing to remember is that each parent contributes to their offspring exactly one of the two alleles it is carrying for every gene in its chromosomes. This means that when the sperm containing one allele of each gene fertilizes the egg containing one allele of each gene, then the offspring will once again have two alleles for each gene. As an example, lets’ say a breeder crosses a Black dog (image 1) with a Gold ***** (image 3). For simplicity sake, it is assumed that no recessive dilution alleles are carried by either parent. So, the Black sire has to be A/- because he is Black, and the Gold dam has to be Ay/- because she is Gold. The result yielded 8 puppies: 4 Blacks, 2 Golds, and 2 Black and Tans.
（理解这个问题）最重要的是要记住：父母双方都各自从它们染色体中的双份基因中，分化出它们的后代的一份基因。这就是说，意味着每个精子和卵子各包含一份遗传基因，这样他们的后代在染色体基因位置上包含来自其父母的两种基因。[注7]举一个例子，我们假设一个培育者用一条黑公藏獒（图1）与一只金色母藏獒（图3）交配。为了简单起见，假设不存在稀释基因。黑獒必然是A/-因为它是黑色的，金獒必然是Ay/-，结果生出8条小獒：4黑2金2铁包金。
注7：精子和卵子结合形成受精卵（才能发育成动物），受精卵包含的基因因此来自父母。但是，由于父母各有两对影响毛色的基因，而后代又只有2对影响毛色的基因，父母各有一个基因在受精卵形成过程中损失掉了。
Why are there more Blacks than anything else? Where did those Black and Tans come from? To answer these questions, the breeder reasons backwards. If the breeding yields any Black and Tan puppies at all, and by knowing that their genotype MUST be at/at, then each parent must also carry at. So now the breeder knows exactly what the genotypes of the parents must have been. The Black parent was A/at and the Gold parent was Ay/at. To find the ratios of what the breeder should expect in the litter, a list of all combinations should be made.
为什么会有更多黑的呢？铁包金从哪里来的呢？要回答这个问题，繁育者需要倒着推演。由于这次繁殖产生了铁包金的小獒，根据知识可以知道铁包金的基因型是at/at,这样他们的父母必须都携带有at基因。黑獒的基因是A/at,金獒基因是Ay/at。想要预期一窝小獒出现各种颜色的几率，要做一个联合表。
The Black male can produce sperm containing the A allele, but he will produce an equal number with the at allele. The Gold female can produce eggs with the Ay allele and an equal number with the at allele. What follows is a list of all possible outcomes.
黑獒的精子包含A基因，也同时有相同数量的at基因，金獒的卵子包含Ay基因，同时也产生相同数量的at基因。下面就是他们后代染色体中（以上基因的排列组合后）出现的情况的表：
翻译版:藏獒毛色问题(全面答疑)A from father, Ay from mother offspring will be A/Ay and appear Black
A from father, at from mother offspring will be A/at and appear Black
at from father, Ay from mother offspring will be Ay/at and appear Gold
at from father, at from mother offspring will be at/at and appear Black and Tan
A来自父本Ay来自母本 后代基因型是A/Ay显示出黑色A来自父本at来自母本 后代基因型是A/At显示出黑色at来自父本Ay来自母本 后代基因型是Ay/at显示出金色at来自父本at来自母本 后代基因型是at/at显示出铁包金
Notice that the ratio is 2 Blacks to 1 Gold to 1 Black and Tan, which is the same as the 4:2:2 that was yielded in the litter. It is important to say that the 2:1:1 ratio is EXPECTED in the offspring, but not guaranteed. Statistical variation will determine what actually appears. Although many combinations are possible, most litters from these parents will yield colors near that ratio. A breeding between different Black and Gold parents could produce either all Black puppies, or half Black puppies and half Gold puppies. It is left to the reader to work out the genotypes necessary to produce these results.
注意（其后代表型的）比例是2黑比1金比1铁包金，跟生出的小獒4：2：2相符。（但是）非常重要的是2:1:1这个比率是估算的，（现实中）不能保证都是这样。从统计上的数字变化会确定实际（表型）的出现情况。尽管（其他影响毛色的）各种组合都可能出现，大多数（情况下）还是接近这个比例的。不同的黑父本和金母本交配结果可能会全是黑色的或者一半是黑色的一半是金的。留给读者自己推断父本母本是什么基因型。[注8]
注8：作者此处意思为，如果考虑到B位基因和D位基因的影响，以及遮盖基因的影响，毛色可能为全黑或一般是黑一般是金。
As another example, our breeder crosses a Black and Tan male having medium toned tan points, with a Gold female like the one pictured in image 3. Remember that the tan points on this male appear as a medium tan because of the rufous polygenes (in this case, a balanced checker collection). Assuming the Gold female (also with a balanced checker collection) is Ay/Ay, and knowing that the male is at/at; what will the breeder get? The male can only produce sperm with at and the female can only produce eggs with Ay, so all of the offspring will be Ay/at, and appear gold, right? Well, yes and no. All the offspring will be Ay/at alright, but because the male had a pattern of rufous polygenes that determined his tan points should be medium toned and the female the same medium toned Gold; the offspring could be anything from Red (having randomly received lots of red checkers from both parents) to Cream (having randomly received lots of white checkers from both parents).
另外一个例子：我们的繁育者用一只铁包金（铁包金的金色适中）的公藏獒跟一只金色母藏獒交配。金色母獒象图3的颜色。记住公獒的金色部分是由上文的“修改基因”即：红褐色因子群决定的（在这个例子里，金色适中是因为在修改基因的作用下，红色白色相当）。假定这只金色母獒的基因型是Ay/Ay（而且也是具有红白相当的红色基因），我们知道公铁包金的基因型是at/at，我们能得到什么样的小骜呢？公獒只能产生带at基因的精子，母獒只能产生带Ay基因的卵子，所以，它们所有的后代都是Ay/ay，那么就都一定是金色了，是吗？是也不是。所有后代的基因型都是Ay/at是对的，但因为公獒还有一组“修改基因”即红褐色因子群决定他的金色适中，母獒也一样有着适中的金色；因此他们的后代可能从奶酪色（从父母得到了较多的白色因子）到红色（从父母得到了较多的红色因子）都有。
Cream is not recognized in all the international Tibetan Mastiff breed standards. Given this example, all the offspring are identical Ay/at (with the exception of the distribution of rufous polygenes), and are from parents having allowable colors under these standards, despite the fact that some of the puppies appear as a non-recognized Cream color. This is one of the inconsistencies the TMCA hopes is corrected in all future standards.
奶酪色不被国际藏獒繁殖标准承认。但是，给出的例子中，所有后代的基因型都统一是Ay/at（不考虑红色因子分布外），他们都是合乎标准的父母所生，而事实上有些小獒出现了不合标准的奶酪色。这是个矛盾，TMCA希望以后修改。[注9]
[注9]：奶酪色不被认可，呵呵。不一定适合中国呀。
One last interesting point, it is theoretically possible (but unlikely in the extreme) to breed a Black dog with a Gold dog and get all the possible colors discussed in this article. For this to happen, however, the genotypes of the parents would have to be A/at, D/d, B/b for the Black parent and Ay/at, D/d, B/b for the Gold parent. This cross will give Blacks, Golds, Black and Tans, Chocolate/Browns, Chocolate/Brown and Tans, Blue/Greys, Blue/Greys and Tans, Gold dilutes, Double Dilutes, and Double Dilutes and Tans (and masked dogs if those recessives are present). If the reader wants to work out the ratios, it is suggested he/she finds Punnet squares in an old genetics text and makes up one with 8 squares on a side. Good luck.
最后一个有趣的事情，理论上可行（不过极端不可能出现）：用一只黑獒和一只金獒交配可以出现本文讨论的所有毛色的藏獒，要使这个情况发生黑獒的基因型必须是A/at,D/d.B/b,金獒的基因型必须是Ay/at,D/d,B/b。这个交配可能会出现：黑，金，铁包金，巧克力褐色，巧克力褐色包金，蓝灰，蓝灰包金，稀释金色，双稀释色，双稀释色包金（如果隐性修改基因起作用还可出现掩盖色）。如果读者要计算出各种颜色出现的几率，建议他/她在旧遗传学课本里找到Punnet square,然后在一边乘8次方，祝好运！[注10]
[注10]2的八次方是指，在后代的染色体中的两对基因可能包含了以下所有基因片段的各种组合，A， Ay，at ，D，d，B，b，再加上隐性修改基因的作用方向，共8个因素，排列组合。
Charles W. Radcliffe
Matthew J. Taylor
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