Off The Beaten Track
ADDING VALUE TO LIFE

Our Sheep, Pasture & Herd Health Story

Ok – so we bought our first batch of Dorpers, and started applying selection criteria which we believed were essential to our business model (www. Metebusinessmodel.com), i.e. fertility, lambing interval, before weaning growth and after weaning growth. We were disillusioned – only a handful of the registered Dorper ewes made the grade. This started very interesting and enlightening research, some of this below:

Dorper

Breed improvement in the Dorper sheep breed is based mainly on subjective assessment in the show ring (See 1. Lategan below). The low levels of genetic variation and heritability estimates derived for subjective traits suggest that genetic progress in such traits is feasible although genetic gains will be quite slow, and selection of breeding stock on the basis of subjective traits should be discouraged because genetic improvement in these traits would be difficult to achieve partly due to the associated very low additive genetic variance (See 2. Zishiri O.T et. al. below). Fortunately there are a handful of Dorper breeders (See 3. Kleinkoppie Dorper Stud below) which use BLUP breeding values. Novel methods such as genomic breeding values as a complement to BLUP breeding values as well as screening of elite animals for Single Nucleotide Polymorphisms (SNPs) for traits of economic importance should be gradually introduced to breeders as a way of making ‘subjective assessment farmers’  lose great emphasis on subjective or visual traits.

1 Lategan, D, Dorpers in die nuwe eeu. Brosjure & Handleiding, Dorper Skaaptelersgenootskap van Suid Africa, ISBN: 978-0-620-42249-9.

2  Zishiri, O T, Cloete, S W P, Olivier, J J and Dzama, K, Genetic parameter estimates for subjectively assessed and objectively measured traits in South African Dorper sheep

3 www.kleinkippiesdorper.co.za

 

Crossbreeding

– the Dorper experience led us to investigate further

We considered crossbreeding in order to take advantage of the different and complementary strong points of the Dorper (see above) and other breeds and to utilize hybrid vigour. However, much of the crossbreeding in the South African sheep industry is haphazard, does not utilize systems that optimize the advantages of crossbreeding, and are not sustainable over several years, i.e. Doprer and Merino crosses, etc. The system we were looking for would require:


1


Easy to implement and maintain –greatly increased labour in flock management, or breeds or crossbreds that are in short supply or very expensive, it will not be sustainable and may not result in increased net income.

2

Properly utilize the strong points of different breeds (complementarity) – Different breeds of sheep excel for different economically important traits. A well designed crossbreeding system utilizes these breed differences in a strategic manner to improve the efficiency of meat production over pure Dorper breeding.

3

Optimize the amount of hybrid vigor – The amount of hybrid vigor is maximized in the offspring of a ram and ewe of two unrelated breeds. It is not possible to maintain the maximum amount of hybrid vigor in all systems, but a good crossbreeding system will be able to maintain high levels of hybrid vigor.

4

Produce a uniform product – For ease of management and acceptance in the market, the commercial products from our flock (market lambs) should be as uniform as possible.

             

As with most things in life, deciding on the best crossbreeding system for our flock was an exercise in compromises.


And then it happened – Romanov

Music to our ears – “The infusion of Romanov genes into a population ‘(Dorpers)’ via crossbreeding advances the onset of puberty, increases ovulation rate and decreases ewe mass.” 4 – Problem solved!

Not so – unfortunately the Romanov breeding project that was part of a government research trial lost momentum and was discontinued!

After around 3 years of searching for the remnants of the Romanov’s from the Breeding program, we found a Romanov ram well – sort of!

4 Greeff, J G, Langenhoven, J and Wyma G.A, Puberty and ovulation rate of Romanov, Dorper, and their crosses during the
first breeding season Irene Animal Production Institute, Private Bag X2, Irene, 1675 Republic of South Africa

 

This is now the model:

1.    A flock of 150 ewes is maintained, 15 Purebred Dorpers, 35 Commercial Dorpers, 125 Dorper x Romanov Crossbred ewes

2.      20% of ewes are replaced each year.

3.     All ewe replacements are produced within the system, and all rams are purchased.

4.      Purebred Dorper ewes raise 1.4 lambs per ewe exposed (A and B ewes).

5.      There is 15% HV (I) for lambs reared per ewe exposed.

6.      There is 15% HV (M) for lambs reared per ewe exposed.

7.       Purebred lambs weigh 25 kg at weaning.

8.      There is 5% HV (I) for lamb weaning weight.

9.      There is 6% HV (M) for lamb weaning weight.

10.   There is a 5% increase in weaning weight for lambs sired by terminal ram breed sires (T breed rams).

HV (I) = Individual Hybrid Vigour

HV (M) = Maternal Hybrid Vigour



 














The result - MEAT

System

% Ewes required to   breed replacement ewes

No. of lambs weaned

Kg Weaned

Kg Lambs weaned   relative to purebreeding

Purebreeding

(Dorper   Only)

29%

476

10 796

100

Two-breed   Cross

(Dorper   X Romanov)

29%

539

12 753

118

Rotational

24%

592

14 425

134

Composite

25%

564

13 495

125

Terminal

29%

536

13 190

122

Suffolk   x Dorper

26%

620

16 152

150

Suffolk   X (Dorper x Romanov)

24%

612

15 752

146

Suffolk   x  (Dorper x Romanov) Rotational

25%

596

15 183

141

Suffolk   x  (Dorper x Romanov) Composite

 

 

 

 


But of-course it al starts with PASTURE - but not just any pasture

'You are ready to keep animals once you are a pasture expert' - my dad.



Please contact us for more information.