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Probability of red and red wapiti crossbred yearling females achieving pregnancy at 16-18 months of age

From Asher et. al., 2004

 

This graph shows the range of live weights (kg) for yearling (16-18 months of age) hinds from the Wapiti introgression study (Asher et. al., 2004) and the probability of achieving pregnancy as yearlings.  Note: the old recommended live weight of 65kg (Kelly & Moore 1977: Fisher & Fennessy 1985) only achieves ~ 70% predicted yearling pregnancy even for essentially red (E 0.1) animals.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 


Key:   - 0-15% Wapiti (WS ~1))

- 15-25% Wapiti (WS ~ 2)

- 25-35% Wapiti (WS ~ 3)

- >35% Wapiti (WS ~ 4)

 

From this graph the predicted live weights achieve 90% pregnancy are in the table below:

 

Predicted live weights required for yearling hinds to achieve 90% pregnancy for 10% increments in wapiti genes

 

Estimated

wapiti %

90% pregnancy

live weight (kg)

0

81

10

81

20

85

30

106

40

127

50

~137

 

Most farms in the wapiti introgression study surpassed the 81-85kg live weight necessary for 90% pregnancy for animals with less than 20% wapiti genetics; which is why we considered 20% wapiti to be an acceptable cut off point to consider animals as ‘red deer’ for management.

However the jump between 20-30 and 30-40% wapiti of 21kg for each increasing 10% of wapiti genes makes for more challenging targets to achieve.

 

In the current study on young deer; the mean yearling female live weight in mid-January was 84kg and the mean DNA estimated percent wapiti genes was 13% so the group on average was comfortably on track for >90% pregnancy at the 81-85% target.  However the ‘wapiti’ (>20% wapiti genes) yearling females within the group were at a mean live weight 87 kg and mean DNA estimated percent wapiti genes of 38%.  This still left them on average ~40kg to the target of 127kg to ensure a 90% pregnancy.  In order to reach ~127kg by April they would have to gain approximately 450g per day.  Note: these ‘wapiti’ females were venison animals not breeding stock so were slaughtered before 127kg.

 

References

 

Asher, G.W., Archer J.A., Scott I.C., O’Neill K.T., Ward J. and Littlejohn R.P. (2004) Reproductive performance of pubertal red deer (Cervus elaphus) hinds: Effects of genetic introgression of wapiti subspecies on pregnancy rates at 18 Months of age.  Report to DEEResearch

Fisher, M.W. and Fennessy, P.F. 1985.  Reproductive physiology of female red deer and wapiti.  Proceedings of a Deer Course for Veterinarians; Course No. 2; Deer Branch New Zealand Veterinary Association, Ashburton, NZ. 88-100.

Kelly, R.W. and Moore, G.H. 1977.  Reproductive performance in farmed red deer.  NZ Ag. Sci. 11:179-181.