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 & 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 looses 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, Palm Kernel Expeller 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.
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.