More lambs! (2019 lambing - post #2)

This white 3yr old ewe has had two black lambs (1M, 1F)
- between 5:00 & 5:30am on Tuesday morning, the 27th Aug.

This black, pet, 2yr old ewe had black twin ewe lambs
also on the 27th of August - but in the evening...

First few lambs... (2019 lambing - post #1)

My first set of twin lambs arrived early Sunday morning (probably just a little before 1:35am, 18/8)...
1M, 1F - and they are BOTH moorit, out of a black dam, by a moorit sire.

Then late Monday (just before 10:15pm, 19/8), this 6yr old moorit ewe had a BIG single ewe lamb, also moorit (as expected, with both parents being moorit)... But look at this lamb's face & tail! SO cute!
This marking (spotting?!) MUST be somewhat recessive, as neither dam nor sire show it!

A little more about colour genetics... (Sheep Colours as it relates to my flock - Part 3)

There are other loci that are of interest in relation to colour genetics, but I'm not going to say much about them!

One that must be mentioned is the S-locus - the spotting genes!

How they work seems to be a little controversial, and I haven't had a lot of spotting in my flock, so can't comment much.
~ If it is dominant, I probably don't have it currently.
~ If it is incompletely dominant, then I may have it, hidden...
~ And if it is recessive, then I probably do have it, hidden!

 Triplet lambs born in my flock - two of which appear to have been spotty

One of the same lambs last lambing with her own twins

The moorit one of her twins is one of the two ram lambs that I used this year...

 

Links:

A few web-pages with more information, inc more about the A-locus alleles...
Some of these have photos of sheep with various genetics.
It must also be noted that some of these sites deal with specific breeds of sheep.

http://woolshed1.blogspot.com/…/sheep-farm-husbandry-breedi…
http://americanromney.org/color-genetics/agouti/…
http://everranch.com/Farm/Sheep/Gotlands/P06GotlandColor.htm
http://www.fiberfirstfarm.com/fleece-color.html

"Coloured" vs. White (Sheep Colours as it relates to my flock - Part 2)

You may have noticed that in discussing moorit, I have by-passed white. This is because the genetics that affect whether a sheep is white or coloured involve different loci (plural of locus) than the question of black vs. brown!

There are two main loci that I need to mention in this post:
~ A-locus
~ E-locus


E-locus

I want to deal with the E-locus first.

There are two main alleles at the E-locus that are of some interest to me:
~ The dominant allele at the E-locus is often termed "dominant black", and produces a solid coloured sheep - that will be either black or moorit, depending on it's B-locus alleles. This "dominant black" over-rides the expression of A-locus alleles.
~ The recessive allele at the E-locus allows the expression of the A-locus.

As far as I am aware, I do not have the "dominant black" in my flock. I really do not know for certain if this allele is in any sheep in New Zealand, but I suspect that it may well be in NZ in some of the more exotic breeds that have been brought into NZ in more recent decades.


A-locus / Agouti locus

The main reason that the E-locus is of any interest to me, is that it involves the concept of "colour" over-riding white. In contrast, with A-locus alleles, the usual rule of thumb is that white is more dominant...

There are quite a number of alleles believed to exist at the A-locus. The A-locus / Agouti locus is often called the "pattern locus". The word "pattern" is very important as it is not a matter of which colour, so much as "which pattern" - with different patterns featuring different amounts and locations of white & colour!

The most dominant A-locus allele seems to be one that makes a totally white sheep. The most recessive seems to be one that produces a totally coloured sheep.
 In between those ends of the spectrum, many of the A-locus alleles are "incompletely dominant". So, for the most part, when a sheep inherits two different alleles, it will display the white markings from both alleles!

I'm not clear on all the A-locus alleles in my flock - though there are some very striking colour patterns that I know I have never had! A sheep that came into my flock a few years ago seems to have introduced an allele that I didn't have immediately prior, as I've seen certain distinctive characteristics that I've not noticed before.



Photos:

These  first two photos show white ewes with their lambs. Both of these ewes carried a coloured A-locus allele, and both of them carried one moorit allele (& one black allele) at the B-locus. In both of these cases, the sire was coloured (so had two coloured A-locus alleles), and moorit (so had two alleles for moorit at the B-locus). Thus the sires passed on coloured A-locus alleles and moorit B-locus alleles to all the lambs
 

This photo is of a moorit ewe with a white lamb and a moorit lamb. The sire of these lambs was white, but carried a coloured A-locus allele, as well as having both black and moorit alleles at the B-locus.

This photo is of a black ewe (that did also carry moorit at the B-locus - a fact I know for two reasons - firstly, her sire was moorit, and secondly, she later had some moorit lambs). The sire of her lamb was white, and would probably not have carried any coloured A-locus alleles.

This final photo is a bonus for yesterday's post about moorit. It shows some shorn sheep - a darker-coloured moorit ewe (left), a lighter-coloured moorit ewe (centre), and a black ewe (right), as well as a white ewe behind the others (and possibly a woolly lamb tucked in there too). It gives a good comparison of the colour differences between moorit & black!

Moorit (Sheep Colours as it relates to my flock - Part 1)

What is moorit?

~ Moorit is a brown colour, occurring in some sheep.
~ Genetically, it is not the same as black. Although many people use terms like "black" and "brown" to describe any/all coloured sheep, truly moorit-coloured sheep are not "black" and most so-called "black" sheep are not actually "moorit"!

Genetics of moorit

First, basic genetics (which is about all I know!)...
A sheep should inherit one "allele" at each "locus" from each parent. Which means that they get two "alleles" for each locus (one from each parent). If they inherit two alleles the same at that locus, they are "homozygous" for that trait. If they inherit two different alleles at that locus, they are heterozygous for that trait.

All sheep (even white ones) have genetic information for "black" vs. "brown", at the "B-locus".
Black is the dominant allele. Moorit brown is recessive to black...
~ If a sheep inherits moorit from both parents, it will be moorit. As it has two alleles for moorit, it can only pass on moorit alleles to its offspring.
~ If a sheep inherits black from both parents, it will be black. As it has two alleles for black, it can only pass on black alleles to its offspring.
~ But... if it inherits black from one parent and moorit from the other, the black overrides the moorit and the sheep is black... BUT it still carries both black and moorit - and it can pass on either to its offspring (only one to any given offspring).

Moorit in my flock

This is why I mostly use moorit-coloured rams - I know that if every lamb born has at least one moorit-coloured parent, I know that every lamb born will carry moorit.
Sometimes I have used a ram that is not moorit (whether black or white) - but when I do, I try to only put them over moorit-coloured ewes, so that their lambs will inherit moorit from their dams.

Currently:
~ ALL my flock carry moorit
~ 1/2 of my flock ARE moorit (inc the ram hogget)
~ 1/3 of my flock are black
~ 1/6 of my flock are white

That will change with lambing. However...
~ I used only moorit rams this breeding season, so all lambs born will inherit moorit from at least one parent.
~ Moorit ewes will all have moorit lambs.
~ Black ewes could have either black or moorit lambs
~ White ewes could have white, black, or moorit lambs (but statistically can be expected to have 50% white, 25% black & 25% moorit)



Photos (all from previous years):

Two pet lambs - moorit brown one on the left, black one on the right

Three pet lambs - moorit lamb in the middle

Pet twin lambs - both moorit, but one was always darker in colour than the other...
and in this photo they have lightened significantly since birth

A black ewe with twins - one black and one moorit
Note the ewe's nose colour is distinctly black (compare with the lambs in the 3rd photo & the ewe in the last photo),
even though her black fleece has "bleached" a bit in colour, and looks quite brown

Another black ewe (her fleece was still darker as she was younger), also with twins where one is black & one is moorit

A white ewe with triplets - inc one moorit lamb and two black lambs

A moorit ewe with triplets - also inc one moorit and two black