Matching calves & dams

Matching calves & dams

Why is dam-calf matching important?
Assignment of parentage (pedigree) to calves is important for genetic improvement programmes and is vital information for assigning Breeding Values (BV’s) in DEERSelect. It requires a knowledge of both parents for each calf.

How do I work out match-ups?
Some farmers assign parentage based on hind:calf suckling behaviour before weaning on the basis that the sire identification is linked to hind identification (i.e. mating records). This assumes that hinds will only suckle their own progeny. This is probably true in most cases, but cross-suckling has been observed in farmed red deer in NZ. Therefore, it must be accepted that behavioural observation will contain a certain level of error. Unfortunately we cannot ascertain what this is, as the level of cross-suckling probably varies across farms. Some studies suggest it could be as high as 10% on some intensively farmed units, but it is likely to be considerably lower than this on most farms.

Practical effective matching
For effective matching up, all hinds and calves need to be easily identifiable. For this they both need good, clean easy-to-read ear tags or collars.  Most farmers will obtain suckling information by bringing the hinds and calves into the yards and separating them for several hours, before reuniting them back in the paddock.  At this point the calves will seek their mothers and suckle.  With the aid of good binoculars calf:hind parings can be noted and recorded. Given the possibility of a degree of cross-suckling it would be advisable to repeat this more than once if highly accurate records are needed.  Alternatively some farmers simply make repeated casual observations of hind:calf pairs over a period of weeks in their paddocks, following calf tagging in January or February.  
These observations can be easier immediately following provision of supplementary feeds (e.g. barley).  Generally a valid hind:calf pair is established when the same pairing is observed on more than two occasions.

DNA Assessment
The more accurate way to assign parentage is to use DNA assessment of sire, dam and progeny. This requires submitting tissue samples to the appropriate laboratory (Genomnz and Genemark) along with all possible stag:hind mating combinations. Tissue samples can include pulled hair (with follicles attached; not suitable for newborn calves but okay from weaning onwards), blood samples or ear tissue punches…all provide suitable quality of DNA. Semen can also be used for stags.

In the laboratory the DNA is extracted and amplified, then assessed for allelic variation using either microsatellite markers or a SNP marker panel. The DNA markers chosen for the assessment all show natural variation. The assignment of parentage is done by a process of exclusion of unshared variants.

For many stud farms the hinds and stags may already have been screened, and it simply becomes a matter of tissue sampling progeny and new animals annually.