Intake requirements

Day length influences

Red deer exhibit strong seasonal responses to day length (photoperiod) resulting in variations to food intake and subsequently live weight gain throughout the year. In general these are: low intake and low liveweight gain in winter (short day length) and high intake and liveweight gain in summer (long day length).

Intake is also influenced by the amount of pasture offered to the animal. In all seasons, liveweight gain increases with increased pasture availability, up to 6-8 kg DM/hd day offered. This is about the same as a post-grazing residual of 1500-1600kgDM/ha or 8cm. The more that is offered, the more that can potentially be eaten, up to a maximum where increased available pasture dry matter has no more influence on intake and liveweight gain. 

Figure 3: Predicted mean daily voluntary food intake of pregnant and non-pregnant hinds relative to day length (hours between sunrise and sunset) during indoor feeding.(Scott, I.C., Asher, G. W., Barrell, G.K., Juan, J.V. (2012).

Pasture

Intake is also influenced by the amount of pasture offered to the animal. In all seasons, liveweight gain increases with increased pasture availability – up to 6-8 kg DM/hd day offered. This is about the same as a post-grazing residual of 1500-1600kg DM/ha or 8cm. The more that is offered, the more that can potentially be eaten However there is a point where increased available pasture dry matter has no further influence on intake and liveweight gain. 

Nevertheless increasing pasture allowance does not compensate for the seasonal differences in intake and liveweight gain expressed by the animals. Feed intake and liveweight gain of red deer is influenced by pasture quality, which varies with the time of year. 

The feed requirements of deer differ depending on their age, stage of growth, the season, feed quality, environment and management. To maintain good levels of production throughout the year the feed supply has to match the stage of production and seasonal requirements in terms of usable or 'metabolisable' energy ('ME'), protein and trace elements.

In New Zealand, pasture is the basis of the majority of deer feeding systems, however pasture growth is not as well matched to the deer production system as it is to sheep, beef and dairy systems.

Intake is influenced by the amount of pasture offered to the animal (referred to as pasture cover, pre-grazing mass or height) and the quality of the pasture as poor quality pasture is digested more slowly by the animal, therefore reducing intake.

It is important to understand the different feed requirements for maintenance and growth.
Among the issues that need to be understood are seasonality and its effects on the growth of young deer, their feed requirements and practical day-to-day management.

Deer will make nearly 40% of their annual weight gain in spring, so supplying the highest quality pasture is a major priority from as early as late August when the deer growth spurt starts.

A failure to meet target weights gives early warning that feed management needs fine tuning. This is important for deer because of their seasonal growth cycle. An ability to grow well in spring and summer must be efficiently utilised, since missed opportunities at that stage cannot be caught up in winter. Ideally, producers should weigh at the end of autumn, winter and summer to monitor progress.

The Deer Feed App is a simple calculator that uses the hind weight and the calf weaning weight and days to weaning to calculate total feed requirements of the hind or hind/calf pair to meet the liveweight targets set. 

The Deer Feed App can also calculate the requirements of growing weaners. Weaner feed requirements are calculated based on size and gender.

Acknowledgement: Deer Industry New Zealand would like to acknowledge D Stevens and M Casey for the development of the initial version of the Feed intake calculation.

Information on Growing weaners for the spring venison market is available in a convenient DINZ Deer Fact sheet. Download your own copy here >>

Autumn to winter

Autumn management is important for maintaining the growth rate targets of young stock and enabling farmers to meet venison production schedules and good life time reproductive performance. The weaning decision has an impact as management of feed quality and diet change on farm through weaning can help maintain growth rates. Weaning young stock back on to feed they are used to can help reduce any potential check in growth rates.

At weaning stag fawns are heavier than hinds (2-5 kg) as a result of heavier birth weight and greater live weight gain over lactation. 

The live weight at 1 June is an important benchmark for farmers as it is a good indicator of the animal’s potential slaughter weight/date or 12 month weight. From a management perspective weight gain between weaning and June 1 should be maximised as growth rates are low over winter and the next opportunity for good growth rates is early spring.  

To achieve 150 g/day+ post weaning  

• Feed quality > 11.5 MJ ME/kg
• A green leaf content > 90%

Winter

In winter, (June and July), the potential for weaner growth is lowest from about 40-145g/day depending on the amount of feed offered (pasture allowance) and the residual. Weaners with elk genetics will continue to grow at a faster rate in winter than red weaners. To achieve higher growth rates, over 100g/day, the allowance has to be very high and of high quality (at least 8kgDM/hd or a post grazing height of 10-12cm). In practice on farm this is difficult to achieve and may compromise other stock.

Farmers can target maintenance requirements from pasture with additional supplements such as hay, silage or baleage (ME 10.5) if required. Lower feed allowances of 4-5kg DM/hd day target liveweight gains of about 80g/day. Research has shown there is a low response in live weight gain to high levels of winter feeding ie with costly supplements.

Spring to summer

Towards the end of winter the weaner will respond to increasing day length (Aug 10-20th) and therefore will respond to increasing feed quality and quantity so high quality silage and grain can be fed to supplement late winter pasture. From mid-August onwards young stock should be offered high pasture allowances (leaving 8cm of pasture post grazing) to capture the benefit of the high potential liveweight gain in spring. Live weight gain in spring is about 4-6 times higher than in winter.

• R1 year weaners require high quality and high pasture allowance (8-10 kgDM/hd/day) in spring to ensure they reach good slaughter weights. 
• Hybrid weaners require higher allowances than red deer to achieve maximum live weight gain. 
• Young hinds need to be fed well to achieve puberty and good conception weights. R2 hinds need to reach target live weights, depending on genotype, well before mating. (See Puberty in hinds for further detail)

Feeding young stags

Young stags have a high protein requirement for antler development

Table courtesy of P.F. Fennessy and J.M Suttie, Antler Growth: Nutritional and Endocrine Factors

Post-rut and winter

Breeding stags at the end of the rut are usually in poor body condition. Provision of additional feed post rut, such as silage or grain, and shelter will prevent death of stags over winter.

Pre rut and rut

In summer, prior to the rut stags can gain considerable weight and increase their fat reserves therefore the feed management of breeding stags should be targeted so that they are in the best condition to survive the rut. The stags have little interest in feed and are more interested in fighting and mating during the rut. The feed requirement of mature stags in autumn (rut) is less than half of their requirement at other times of the year. Stags can lose up to 30% of their liveweight during the rutting period.

Velvet antler stags

Velvet stags need to be well fed from post rut to October/Nov to ensure good antler growth. Any restriction in feeding over this period has a significant negative effect on antler growth.

The genetics of an animal determine the potential productivity of that animal. The nutrition that the animal gets then helps express that potential. Finally how we manage the environment of the animal to gain the required nutrition creates the final outcome. So, how we manage our farm has as much influence on the expression of genetics as nutrition might have.

Much research has focused on feeding the stag during its adult life, trying to gauge what to feed and when. Previous studies conclude that “any restriction in feeding stags for maintenance or growth phases, particularly from autumn until spring has a significant and negative impact on antler growth in New Zealand pastoral-based feeding systems.”
Jermy (2002) rightly states ‘most importantly, antler potential is quickly compromised by poor nutrition. The simple message is to feed well, but overfeeding will not deliver anything other than what the stag is genetically capable of.”

To avoid the problems of low pasture growth during late autumn until early spring it is recommended to provide supplementation. Recent research has also highlighted that it is not how much weight an adult stag loses in autumn that counts, but how fast he regains that condition in spring (Gaspar-Lopez et al 2010). This means that ensuring plenty of feed is available in the early spring, around casting time, is important to maximise velvet production.

While additional protein has not improved the velvet production of well-fed stags, it is important to remember what that means. Often stags in New Zealand are fed on silage during the winter and well into the spring. Silage is a product that has already been fermented and this means that although crude protein concentration may look adequate, often the digestion process does not yield enough protein to meet the stags’ requirement. This is especially important in early spring when antler growth is initiated around button drop.

Moving to specialist silages that are based around legumes and chicory can help increase the true protein supply to the animal. Today, practically this is being surpassed by the use of fodder beets, swedes and new formulations of proprietary processed feed nuts, although there have been no formal velvet growth trials with controls reported as we understand it.

In recent years the basic winter forage diet for the AgResearch Invermay herd of mixed age stags on grass pasture baleage (or silage) was changed to a specific crop baleage fed ad lib for the winter and pre casting period in combination with 1.2kg of whole grain barley. With both red clover and lucerne sources, wastage was almost nil in comparison with pasture silage. Velvet weights average 4.07kg compared with 3.78kg the previous year.

Button Drop

After button drop the stag needs a diet that is well balanced to provide enough energy and protein to ensure good velvet growth. Often spring pasture is fine for this period, but it has to be remembered that the stag needs enough at this time. The pasture needs to be of good length and unsoiled.
This period begins in early August. Often stags are still on pasture silage through August and this will mean that the added protein requirement will not be adequately met. On a commercial farm the recognition of this factor has been documented to improve velvet weight by approximately 0.5 kg/head (Thayer 2002) when the system was changed from silage until September to stags going onto good quality (1800-2000kg /DM) pasture in early August.

A final factor in velvet growth is the mineral intake of the stag. Little research has been done to verify the concentrations of minerals in the diet. Some Chinese research with Sika deer suggests that the dietary concentration of calcium and phosphorus be 0.89 and 0.52% of the diet respectively for maximum velvet antler growth (Wang et al. 1997). Ca and P levels in the diet had effects on Ca contents in antler serum at the antler-harvesting stage, but no effects on P contents. However, much of the calcium and phosphorus required comes from remodelling of the stags bones and so the supply of more calcium has little overall effect on velvet weight. The amounts of other minerals that are essential for cell proliferation, such as copper and zinc, have not been specifically investigated although the role of adequate copper levels at least has been considered very important.

Management factors also play an important role in optimising production.  The key to advancing velvet growth is in the 3 to 4 week post rut recovery period and in the pre casting period. Beneficial nutrition effects are enhanced by forming stable cohorts of similarly aged stags from as early as yearling age and to avoid adding in new animals or mixing groups.

During the rut, non-breeding stag groups should be located with as much space as sensible feed conservation allows and as far from active breeding groups as is practical to reduce fence pacing, aggressive behaviour and extreme rut-related weight loss. Rapid post rut recovery with targeted feeding is readily achieved. Concentrates should be offered on an individual animal basis rather than by group feeding in troughs or lines. Bulky forages must be of the highest quality possible to counteract the rumen fill limitations to intake.

Feeding the hind well is important for the productivity and profitability of the farming system through her life time reproductive performance.

Pregnancy

About 65% of the mature breeding hind's life is associated with pregnancy and this is a dynamic process with changing feed requirements. Mature hinds (115-130kg LWT) increase their energy requirement during pregnancy and this should be reflected in farmer’s management. See feed budgeting >>

• 1.8-2 kg/hd/day of DM intake at week 18
• Increasing to 2.6-2.8 kg/hd/day of DM intake at week 30
• Restriction of feed supply during late pregnancy can lengthen gestation and result in later calving. (see Reproduction) 

The target over winter is to continue to maintain live weight of the hinds plus support the growing foetus. The voluntary intake of hinds increases rapidly in the last third of pregnancy and is reflected in increased hind liveweight of up to 20% (including foetus).

Hinds under feed stress are more susceptible to animal health issues. Farmers should be feeding in advance of forecast severe weather events.

Lactation

Lactation in deer can last for longer than 300 days with natural weaning of calves occurring in the third trimester of the following pregnancy therefore mid-lactation coincides with mating. Lactation is a period of high nutritional demand for the animal as it maintains both its calf growth and prepares for reproduction. The management of feed supply (quantity and quality) available to the hinds at this time of year can therefore impact on both the incidence and timing of conception. 

Research has shown that the body condition (BCS) of hinds during lactation has an influence on subsequent reproductive performance. 

• Hinds with a BCS < 2.5 are less likely to conceive than those with BCS > 3 and this could result in up to a 10% difference in pregnancy rate. 
• Hinds in very good condition (BCS = 4 to 5) will conceive up to 5 days earlier than those in poor condition. 
• Pre rut weaning also increases the chance of early conception, most likely due to the cessation of lactation allowing hinds to improve body condition.

Farm management systems need to target hind performance over lactation to ensure high productivity levels. On farm, during lactation, summer pasture quantity and quality are both declining. For farmers the decision is a compromise that has to be made between better calf performance and hind condition during mating. Where high quality pasture is not available calves may do better when post-rut weaning is used, but, for the hind this may result in later calving and possibly lower conception rates.

Feeding targets during lactation

• Allow 4 to 5 kg DM/day/hind of high quality feed for hinds with red calves at foot. Hinds with Wapiti calves should be allowed an additional 1-1.5 kg DM.
• Pasture covers need to be 1800+ kg DM for lactating hinds to ensure they can access enough feed to avoid live weight loss in late summer.
• If possible consider utilising highly palatable species (e.g. forage herbs, etc) in late lactation (February) when pasture quality is low. This will encourage calves to increase intake (and hence growth rates), and assist in development of rumen function which will minimise setbacks at weaning.
• Introduce hinds and calves to new feeds before weaning so that calves will make the most of it after weaning.
• Pasture quality is generally highest in spring (ME 12) and of greatest variability in summer (ME 7-10) as pastures go to seed and lose quality rapidly (reproductive and dead material increases). 
• Young calf growth rates are most influenced by the hind lactation and therefore how well hinds are fed. Live weight gain in un-weaned calves ranged from 220 to 700 g/day in Jan/Feb (reported from farm trials, Deer Master, Lincoln and AgResearch Invermay trials).

In order to achieve calf growth rates of 400g/day+ both the hinds and the calves need:

• High quality feed > 10.5 MJ ME/kg
• Pasture offered > 2500kgDM/ha, to ensure high intakes
• More green leaf (> 60%) and legume/chicory (>15%)

Late lactation is a critical period to maximise calf live weight gain on farm by improving the quality of the feed on offer potentially through the use of specialist pastures or crops. On most properties quality of pasture on fawning paddocks is the limiting factor to live weight gain.

Deer mate in autumn. If calves are weaned before mating, at three to four months old, there are only a few weeks for hinds to recover some of the body weight lost during lactation before they mate again. This may affect their conception rate – hinds with a Body Condition Score ('BCS') of less than 3 will conceive about five days later than hinds with a BCS over 4. The earlier hinds mate the better, so they should be fed well before mating. After mating, pregnant hinds can be fed to just maintain body weight – and then given supplementary feed just before giving birth.

Key points:

• Hinds need to be in good condition (BCS ≥ 3) before mating.
• However it is important to recognise that both lactation and the influence of declining pasture quality and quantity will make increasing hind condition before mating difficult.
• Supplementation with high quality feed may be needed especially when the season is difficult (drought or wet conditions). If possible identify hinds in poor condition before mating and feed preferentially to improve BCS. At this time a poor condition hind may also prompt a review of her general health, teeth wear and age.