Farmed red deer and wapiti crossbreds in New Zealand calve in early summer, from late October through to early December. Most hinds within the herd will complete calving within a 3-week period, although there will typically be a few hinds conceiving at later oestrous cycles that calve later in the following few weeks.
Peri-natal (around the time of birth) and post-natal (more than 24 hours after birth) mortality of calves is the single biggest source of reproductive wastage occurring on NZ deer farms, accounting for about 8% of calves born (see Reproductive Wastage). While it is recognised that there will always be losses around calving, there are ways to reduce overall calf mortality. This can involve simple on-farm changes in management and calving environments.
Why do hinds need a good calving environment?
A significant proportion of calf losses occur because the calving environment is suboptimal for the needs of all individuals within the herd. This relates to the specific behaviour of hinds around the birthing process.
Hinds approaching birth seek isolation from their herd-mates and actively search for a suitable calving site. Such search behaviour is often seen as fence-line pacing starting 24-48 hours before birthing starts. Typically the hind will seek an elevated position with good ground cover as the preferred calving site (e.g. tussock slopes). This affords good visualisation of the surrounding terrain as well as shelter for the calf.
When such calving environments are in short supply there can be considerable competition between hinds for prime sites, leading to conflicts in which the dominant hinds prevail. This is especially the case when several hinds are at the same pre-calving stage. Sub-ordinate hinds that fail to secure a good calving site often become stressed and this can lead to a disrupted birthing process, three consequences of which are:
- The hind fails to adequately bond with its calf within the first few hours of birth, leading to calf abandonment. This results in the calf dying of starvation and dehydration 2-3 days later typically wandering around the paddock crying out for mum.
- The actual birthing process is disrupted, forcing the agitated hind to move around while calving. This can lead to a difficult birthing process that causes fatal damage to the newborn (often stillborn) calf termed ‘dystocia’. Typically affected calves are dead at birth or die within a few hours.
- In some cases the birthing goes to plan but the calf has insufficient cover in which to hide especially if it is disturbed (e.g. by other hinds seeking a good birthing site). Such calves tend to wander in search of suitable cover, and can become the victims of misadventure especially getting lost outside the birth paddock or getting entangled in fences.
What is the ideal calving environment?
Consideration to providing hinds better calving paddocks can pay big dividends by improving calf survival. Key points are as follows:
- Keep hind stocking rates reasonably low (<8 per ha) over calving to minimise competition over the birthing period. If the hinds are likely to have a highly synchronised calving (e.g. from artificial insemination programmes) it is important to further reduce the stocking rate to <4 hinds per ha until the birthing period is finished.
- Design calving paddocks around the provision of suitable cover particularly provision of shade for calving, calf security and protection from the weather. Sometimes these may seem to be the ‘roughest’ paddocks due to the presence of shrubs, tussock, rocks, gulleys, etc, but actually contain ideal birthing sites. However, there is also a need to provide lactating hinds with high-quality pasture to optimise calf growth…if this is compromised by the use of low-productivity ‘rough’ land for calving, a strategy is required to give hinds access to better pastures after birth (e.g. as simple as opening the gate to a better paddock next door).
- If ‘rough’ calving paddocks are not available (e.g. on intensive lowland farms) it may be necessary to create calving sites and calf hide-out sites. For example, leaving un-mown or un-grazed strips of long grass in the middle of the intended calving paddocks can provide a better calving environment. However, it is recommended that such strips should be sited away from fence-lines to reduce the temptation for calves to go through fences.
- Minimise outside disturbance during and immediately after calving (e.g. no dogs in the calving paddock). Such disturbances can be particularly devastating when hinds are birthing if they prematurely leave the newborn calf there is a danger that the maternal bonding process will be disrupted.
For more details around causes of calf mortality see Reproductive wastage >>
What is ‘dystocia’?
Sometimes hinds experience difficulties during birthing which can lead to an inability to expel the calf. This is termed ‘dystocia’. Such severe cases of dystocia are not as common now as they were at the start of deer farming in the 70’s and early 80’s.
How do I detect problem calvings?
Calving should be observed discretely from a distance, but preferably from a vehicle and position that the hinds are comfortable with. There are often signs that animals are in distress around calving, including constant fence-pacing (e.g. beyond two hours) and in many cases, the prolonged appearance of part of the calf (e.g. head or legs) sticking out without delivery progressing.
When do I intervene?
The sight of a distressed hind experiencing a difficult birth can be quite disturbing but it is difficult to know when to intervene and assist with the removal of the stuck calf. Firstly, in most cases of a difficult birth the hind will actually eventually expel the calf naturally, but often with the loss of the calf. Secondly, in removing the hind from the herd for yarding there is a risk of disturbing other calving hinds. Thirdly, once assistance has been performed the hind is unlikely to bond with the calf if it is still alive leaving you with a calf to hand-rear.
In most cases where assistance needs to be given, the prime motivation is to save the hind and the survival of the calf is secondary (in many cases the calf will already be dead). Fortunately, distressed hinds will often separate from the rest of the herd, and it is usually possible to direct her out of the calving paddock simply by opening a gate to let her out on her own accord. This avoids disturbing the rest of the herd. Once yarded the hind should be settled into a darkened room and left to rest for a few minutes. At this stage a decision needs to be made as to whether the calf extraction can be done easily by simply applying gentle torsion to the calf (as can be the case in many backwards, rear feet presentations) or veterinary assistance is required due to a difficult calf presentation (e.g. mal-presentation of front feet) or a decomposing dead calf. Preferably discuss with your vet before you intervene on your own, and you should not intervene for much longer than twenty minutes.
- In the case of the presentation of a live calf after a difficult delivery it may occasionally be possible to get the hind to accept it by leaving them together in a quiet pen for a few hours. However, highly stressed hinds seldom accept their calves.
- Following calf extraction the hind may need antibiotic treatment, and then returned to pasture.
- The question then remains as to her fate. Will she be prone to further difficult calvings? Most farmers today would mark such a hind for eventual culling.
Calves are heavily reliant on the lactational output of their dams for their nutrition over their first 3-4 months of life.
The quality of lactation influences pre-weaning calf growth, the period of greatest growth potential in the animal’s life.
If lactational outputs are compromised through poor nutrition, this will have consequences not only on calf weaning weights but can also influence other aspect of their performance throughout life. For example, young hinds may fail to enter puberty as 16 month-old animals because of long-term effects of poor pre-weaning growth on puberty live-weight thresholds. For more information, see Puberty >>
There is sometimes a compromise between providing hinds with a good calving environment (i.e. plenty of rank pasture cover for birthing) and subsequently providing hinds good nutritional environment to support optimal lactation (i.e. shorter highly palatable and digestible pasture). However, with proactive management there are generally ways around this issue. Rank pasture is good for the calf but not the hind, so a compromise is to leave strips of rank pasture, but maintain the rest of the paddock in a good vegetative state for high quality pasture for the hind.
After about two weeks from birth calves will generally tag alongside mum rather than hide out. It is at this stage that hinds and calves can be safely moved to new paddocks. However, before doing so ensure that all hinds have completed calving and that all calves are at foot: it is possible that late-born calves are still hiding out and may be left behind.
Moving hinds with calves at foot
The best approach to moving hinds and calves is to simply leave the gates open to the new paddock and leave the deer to find their way there. Hinds will then quietly guide their calves through unfamiliar gateways. However, before shutting the gates, check to ensure there are no calves left behind in the calving paddock.
After a few moves, calves will become accustomed to gateways and the process of rotating hinds and calves around paddocks becomes easier and quicker. In this way, optimum feeding management can be implemented to ensure the hind lactates well and that the calf has every chance of rapid growth.
For more on feed availability during this period, see Lactation >>
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 new-born 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.
Why is calving seasonal?
Red deer and wapiti calve in early summer. Seasonal reproduction ensures that calves are born in weather conducive to survival. In the northern continental regions, the calving period is also aligned with peak feed production, enabling the hinds to maximise milk production. This gives the calves the best chance to grow to the body size needed to survive their first winter. Also, the dam needs plenty of high-quality forage to maintain body condition during lactation in order to successfully reproduce in the following year.
What are the benefits of seasonal calving?
In lowland systems, early summer calving can dovetail well with other livestock species, such as spring-lambing sheep. Total farm outputs may be increased by optimising pasture utilisation by the different livestock species over the entire spring-summer period.
What are the other effects of seasonal calving?
Pasture production on NZ lowland farms peaks well before calving due to the benign climate. This can cause a misalignment between feed availability in spring and peak energy demands of lactating hinds in summer. However, there is generally a good alignment between red deer calving and lactation periods and feed production in our high-country systems.
What can be done to minimise unwanted effects of seasonal calving?
It is possible through good nutritional management of the hind at mating to bring forward calving by one to two weeks (see Mating management of adults).
Recent research has found a modest amount of genetic variation in seasonality within red deer strains that will allow for gradual (but permanent) advances of the calving season. Achieving this would require deer breeders to systematically collect information on hind conception dates (using ultrasound scanning) (see Foetal Ageing), parentage of calves and the determination by genetics of stag breeding values for early conception (see DEERSelect).
Manual by Ian Scott and Geoff Asher, AgResearch
Technical notes on images in the manual
This manual is a pictorial presentation of actual images of known-age red deer foetuses from 20 to 80 days of age. The images were obtained using a BCF Easi-Scan real time scanner fitted with a 5 MHz linear array rectal transducer. Mode selection was set at ‘Ovary/Early Pregnancy’ and the grid display was set at 1 cm.
Identical images are presented adjacently with and without annotation.
An attempt has been made to collate ‘typical’ freeze images for each age group. However, real time ultrasound imaging is ‘dynamic’, with the 2-dimensional plane of the ultrasound transducer slicing quickly through the conceptus to create a mind’s-eye view of the 3-D structures. The ‘art’ of foetal ageing lies in a rapid determination of this 3-D image through which its size, shape, and other morphological landmarks can together be treated to indicate age. This is further complicated by the particular orientation of the foetus as it is being scanned: is it in cross-section, longitudinal section or oblique section (see below for definitions).
Competency in foetal ageing improves with practice as one starts to develop the mental picture of the 3-D image from what can be seen on the screen. An experienced operator can make an accurate judgement of foetal age within 10 seconds of locating the foetus or other diagnostic structures. This manual, therefore, is designed to help operators calibrate their assessments.
Orientation of the image
The term ‘longitudinal’ refers to an image that is obtained by slicing the foetus from cranial (head) to caudal (tail) and may be:
- Sagittal – a longitudinal plane that slices the foetus from ventral to dorsal (belly to spine) dividing the body into right and left halves.
- Dorso-ventral – a longitudinal plane that slices the foetus from side to side (laterally) dividing the body into lower (ventral) and upper (dorsal) halves.
- Oblique – a longitudinal plane that slices through the foetus at an angle.
The term ‘cross-section’ refers to an image that divides the body into cranial and caudal (head and tail) portions (i.e. it is perpendicular to the longitudinal plane). A cross-section may also be at an oblique angle.
To download the Foetal Ageing Scanning Manual (for operators), click here >>
[1] Since within the first 70-80 days of gestation there is little effect of foetal genotype on the rate of foetal development, no adjustments are required for wapiti-type animals.
More resources
Asher, G.W., Fisher, M.W., Fennessy, P.F. (1996) Environmental constraints on reproductive performance of farmed deer. Animal Reproduction Science 42: 35-44.
