Growth Rates

This year we have done a large recording of the potential of Dorper and White Dorpers under excellent pasture conditions to document the growth rates from birth to weaning and then to 150 days of age. Results are presented below:

All lambs were conceived by embryo transfer, and implanted in Merino ewes. 96% of the lambs were single births. No allowance was made for twin lambs. All merino ewes were run under normal pasture conditions and lambs were weaned onto good ryegrass, clover pastures. To make calculations easier, all lambs were assumed to have a 0 kg birthweight although the normal birthweight is 4 – 5 kgs. All lambs were run together from weaning to post weaning weighing.

Table 1 – illustrates the growth rates at Weaning (Wwt) and then at Post Weaning (Pwwt).

Table 2 – illustrates the % of animals that would be available for marketing at 144 days assuming a target of > 45 kgs liveweight. At this point 89.69% of ram lambs were ready and 21.26% of ewe lambs. A total of 50.89% including both sexes.

 

 Rams  No  WWT  Age g/d  PWT Age  g/d
 White Dorper  196  38.22 kgs  105 days  362.86  49.80 kgs  146 days  341.68
 Dorper   47  38.63 kgs   97 days  398.25  51.13 kgs  137 days  373.21
 Total Rams  243  38.30 kgs   104 days   369.26  50.09 kgs   144 days   348.18
               
 Ewes              
 White Dorper  203  33.80 kgs  105 days  320.42  41.82 kgs  146 days  286.75
 Dorper  56  34.88 kgs   97 days  359.59  41.50 kgs  137 days  302.92
 Total Ewes  259  34.03 kgs  104 days  328.34  41.74 kgs  144 days  290.14
               
 Total Drop  502  36.10 kgs   104 days  348.15  45.36 kgs   144 days   315.27
               
 Ram – Wwt to Pwwt    11.79 kgs  40 days  293.50      
 Ewe – Wwt to Pwwt    7.71 kgs  40 days  191.79      

 

 

 Weight @ Pwwt  Rams  Ewes  Total
 30 to 34.9 kgs  0%  1.97%  1.12%
 35 to 39.9 kgs  0.52%  26.38%  15.15%
 40 to 44.9 kgs  9.79%  50.39%  32.91%
 45 to 49.9 kgs  38.14%  19.69%  27.68%
 50 to 54.9 kgs  37.63%  1.57%  17.19%
 55 to 59.9 kgs  12.37%  0%   5.36%
 60 kgs +  1.55%  0%   0.67%
       

 

::: Kaya White Dorper Policy on Dermatosparaxis (skin fragility).

In my opinion Dermatosparaxis is a problem in White Dorper sheep in Australia, and I feel that it has the potential to cause major concerns in the White Dorper industry. To this point, I have not seen the disease in Dorpers (Black head) in Australia.

The problem has occurred because a couple of rams used in embryo collection in South Africa carried the disease. These rams bred exceptionally well and therefore have propagated the problem in Australia.

Our Solution  Kaya has DNA tested all its White Dorper breeding stock. We have identified carriers of the disease from embryos from 4 different South African studs, (2 rams and 2 ewes ). We have culled all breeding stock that has tested positive from our stud, and we will continue to test all breeding stock retained in the stud.

We recommend that stud breeders use only negative tested rams. We also guarantee that any semen or embryos sold will only come from tested rams and ewes.

It is our view that any progeny born in 2007 (at Kaya) will only come from confirmed negative tested animals. All 2006 progeny that are sold as stud breeding animals will be tested before sale.

Our Kaya Dorper and White Dorper Production sale (October 16th 2007) will only contain animals that are either 1) tested negative (DNA skin test) or 2) are progeny from tested negative parents (DNA parentage confirmation). 

I strongly disagree with Society subsidising the testing as it appears to be very limited in Dorpers and many flocks will not carry the disease BUT they are being forced to test. I would prefer to make it an individuals right to test or not to test. The commercial world will dictate who is correct.

I have tested all my breeding stock, but I have done so at full cost as I do not see why other breeders should pay for me to test my sheep.

 

 

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