The fabled 100kg weaner!
Young deer have their highest potential for growth in the first six months of life. All deer grow more slowly in winter, and some are affected more than others (Eastern reds slow down more than English and hybrids).
So the race is on from now until April to maximise the liveweight of fawns before we are beaten by shortening daylength.
The easiest time to get ahead on pre-winter liveweight in our pastoral system is in the first half of lactation. The energy density and amount of feed offered to hinds is the major driver of fawn growth rates at this time.
Suckling fawn growth rates rarely get above 400g/day on standard ryegrass/clover pastures, but up to 700g/day has been recorded in fawns reared by hinds on high quality chicory/red clover swards.
Recent work at Invermay has shown that fawns suckling hinds on a high energy ration (12.5 MJME/kgDM - comparable to very high quality spring pasture) are able to grow 100g/day faster in the early weeks of lactation compared to those on a lower energy diet (10.3 MJM/kgDM).
As we well know, pasture quality tends to be declining by the time hinds hit peak lactation (6 weeks after birth), but the above data show the gains that can be made by paying attention to pasture quality. Keeping fawning paddocks in a vegetative state, sowing late-heading cultivars and looking at options for alternative forages will all give gains.
It appears that feed energy content is the major driver of hind lactation. Hinds do not increase milk production in response to higher protein levels in feed. In fact 12% crude protein appears to be OK for lactating hinds - this would be too low for ewes or cows. This is useful information when faced with needing to supplement hinds in a dry summer where some of the available options may be low in protein.
Red hinds will increase their intake of feed when grazing lower quality pastures to ensure they meet their daily energy requirements for milk production and maintain condition. This finding is interesting because there is still that effect of hind dietary energy on fawn growth rate mentioned above - mum can increase her intake, but baby is better off when she is offered a high energy ration.
And there is a limit to what a hind can do when offered rubbish grass or baleage. Poor quality feeds such as these pass more slowly through the gut and there is a point where intake cannot increase enough to get the required energy from the diet. Most baleage is only about 10 MJME/kgDM or worse - from the preceding information it is obvious that it's not a good option for lactating hinds, but one that is commonly seen!
As fawns start to graze, their growth rates become more highly dependant on the quality of the forage on offer, so maintaining feed quality just becomes more important.
All this comes back to what we have been banging on about for years - managing our pastures to maintain quality for as long as possible into the summer, looking at where high quality forage options can fit into the system, and the use of high energy supplements where indicated.
Despite the myth that deer thrive on a bit of rough tucker, when it comes to getting high fawn growth rates on mum, quality wins every time.