For most deer farmers, the principal reason for keeping adult stags on the farm is for their use as sires, for which the most crucial time is the rut (or ‘roar’). Sire stags represent a major genetic and financial investment in the herd. There are a number of management considerations around the optimal and safe use of such high-value animals.
When should I join stags and hinds for mating?
Hinds generally start cycling (ovulating) in late March to early April, but some hinds can actually start cycling in early March. To capture the benefits of early calving it is necessary to join stags and hinds as early in March as possible. It is now normal practice on New Zealand deer farms to join the sexes within the first or second week of March, although some farmers are opting for late February joining to identify very early cycling hinds (see DEERSelect).
What is the best ratio of hinds to stags?
While it is acknowledged that some sire stags have successfully mated 100-120 hinds during the rut, such high ratios carry considerable risk of pregnancy failure, especially in single-sire mating situations. Even though the rut is very intense in terms of overt stag behaviour, sire stags have limits to their libido and mating capability. Also, individual stags vary enormously in their mating ability.
- Safe adult stag:hind ratios range from 1:30 to 1:50 depending on stag age, 2 and 3 year old stags generally have lower mating capability than older stags.
- Safe yearling stag:hind ratios range from 1:8 to 1:12, highlighting their lower libido and their inexperience.
If oestrous synchronisation procedures are used to tighten calving spread, it is very important to reduce stag:hind ratios for mating (e.g. 1:10-15) as stags have considerable difficulty serving multiple oestrous hinds in one day.
Single-sire versus multi-sire mating
- Single-sire mating, in which a single stag has sole access to a group of hinds for mating, guarantees the paternity of the offspring. However, it carries risks around stag failure. Care should be taken to observe for normal mating behaviour of single-sire stags during the rut and quickly replace any stags that show no interest in oestrous hinds. Another risk management option is the replace all single-sire stags with ‘chaser stags’ mid-late rut.
- Multi-sire mating management is often seen as a lower risk option but cannot guarantee paternity of specific stags. Care must be taken to ensure that competing sires have adequate space to develop non-overlapping rutting territories in order to minimise combat. Also, it is important not to mix antlered and non-antlered stags. The latter would be at a serious disadvantage and unlikely to effectively sire offspring.
Indications of non-performance
For both systems, it is important to frequently monitor what each stag is doing in the field, and look for signs that the stag is not performing for whatever reason. A particular indication is sitting down and failure to roar. Others continue to mount hinds but owing to fatigue, fails to complete the job. Watch for signs of exhaustion, which may include severe weight loss. Lameness (particularly in the hind legs) is another indicator of fatigue.
What are ‘chaser’ sires?
‘Chaser’ sires are replacement sires used to minimise pregnancy failure in single-sire mating situations. Generally, the primary sire is given access to the hinds for a period equivalent to 1 or 2 oestrous cycles (20-40 days), then replaced for the remainder of the rut with another stag….’the chaser’. Sometimes this simply involves rotating primary sires around the various hind mating groups.
Removing stags after the rut?
Restricting the joining period provides some control over the spread of calving. Stag removal after a set period of mating ensures that late cycling hinds do not conceive to produce late-born calves. Such hinds are generally identified at pregnancy scanning and culled. More and more farmers are opting to remove the tail end of the calving season by removing stags early.
If left to their own devices, stags will generally opt to remove themselves from the hinds once the main mating period is over. However, it may be necessary on occasions to actively remove rutting stags (this also applies when replacing sires with chasers). This is a process requiring care and caution. Rutting stags can be quite belligerent about their eviction!
Mating yearling hinds with yearling stags
There has been much debate over the years about mating practices for yearling (R2) hinds. Low pregnancy rates have occasionally been blamed on the use of older sires over the young hinds. While there is little actual evidence for this, it has become common practice on NZ deer farms to join yearling hinds with yearling stags at ratios 1stag:8-12 hinds. Joining generally occurs quite early (mid-late February) to allow for a period of socialisation to optimise mating success. While yearling stag mating systems have not yet been shown to improve conception rates over that of adult stags, they are relatively simple to set up and manage.