Mixed Mating Groups (MMG)
Depending on your industry, Mixed Mating Groups is known by a different name:
- Multi-sire Joining (Australian Beef)
- Multi-sire pastures (US Beef)
- Syndicate sire mating (Australian sheep)
- Mass Spawning (Aquaculture)
- Open Pollination (Plants)
- Cohort Management (Swine + any other industry with downstream multipliers)
It can also be applied wherever groups of breeding individuals need to be assembled for later mating, including regular flow of animals through the breeding system, and “topping-up” of groups of animals at different AI stations, multiplier herds, or even countries, while accommodating the animals already in these groups. It may also have application in conservation programs where there is limited control of mating, as noted here.
Some breeding operations mate each group of females with a group of males, leaving no control on who mates with who in the resulting mating group. The benefits include fewer mating paddocks/tanks, possibly ‘fairer’ management group effects, and possibly better fertility. However, it is also likely that the numbers of matings per male is rather skewed, with one or a few males mating most of the females. Realised allocations can be detected by pedigree allocation of progeny to parents using genetic markers.
MateSel handles the allocation of males and females into ‘syndicate’ groups for mating purposes. [Alternatively, you can use the MatingGroup field in your datafile to control which group each individual is a candidate for, as described later.] These are called Mixed Mating Groups (MMG). This results in the same number of groups of males and of females, such that each male group is mated to one female group. These groups can contain different numbers of individuals, as dictated by the user. MateSel simultaneously handles the allocation of male group to female group for communal mating. However, this is achieved by changing individuals between the groups: For both input and output purposes, Male group 1 is always mated with Female group 1, etc.
You can target reduced Progeny Inbreeding in the final MMG solution, and Matesel handles this by allocating members to syndicate groups appropriately, and allocating syndicate groups to each other appropriately. You can also target progeny genotypes for individual markers. Moreover, you can target different trait profiles for the different mating groups.
Classic solutions to this problem involve making sire syndicates of closely related individuals and/or individuals of similar EBV profile, in order to ensure that whatever bull(s) actually gets the mating(s), the progeny outcome will be reasonably consistent. MateSel does not need to do this directly, because, as usual, it focuses on outcome in progeny, and the parents have to fall in line behind that. However, the tendency will be for closer relationships within both male and female groups, especially where emphasis on inbreeding avoidance is strong. However, desires on genetic marker genotype outcomes and trait profiles also affect how MateSel forms syndicates of males, and of females … and how it allocates these syndicate groups to each other. Should I use Mixed Mating Groups?
Of course, this is your choice. You may have to use MMG for biological reasons, or you may choose to use MMG for logistical or cost reasons. Whatever, if you are going down this path, it helps to use as much relevant information and appropriate optimisation as possible to help minimise the impact of the compromises that are involved.
Main Data File Differences
Section titled “Main Data File Differences”- If you are using Mixed Mating Groups, then MaxUse value should be 0 or 1 – simply to indicate availability as a candidate. Values greater than 1 are treated as if they were 1.
MMG Videos
Section titled “MMG Videos”There are three videos, all using the MateSel Legacy version: