Dr Ronald Annett, AFBI Hillsborough

By Dr Ronald Annett, AFBI, Hillsborough

RESEARCH being undertaken on NI farms is demonstrating how a carefully planned replacement breeding policy can deliver significant economic and environmental benefits to the hill sheep sector.

The research programme, jointly funded by DARD, AgriSearch and LMC is co-ordinated by AFBI Hillsborough on six commercial hill farms across the Mournes, Sperrins and Antrim Glens.  The aim is to develop breeding strategies, which are economically sustainable as well as delivering environmental benefits by reducing emissions of greenhouse gases (GHG).

Ewe fertility is the key driver of production efficiency and profitability in sheep flocks hence the main focus of the project has been to develop more productive and easily managed ewes for the hill environment.

Building on progress already achieved using crossbred ewes on the hill this project has been evaluating two very different replacement breeding strategies:

 1) A criss-cross between Blackface and Swaledale, aimed at hard hill areas.

 2) A 3-way cross combining Lleyn or Belclare, Highlander and Texel, suited to more ‘green’ hill areas.

 Ewes were lambed for the first time at 2 years old and results from the first phase of the trial (1 and 2 crop ewes) are outlined in Table 1.  The criss-cross horned ewes were around 4 to 5 kg lighter than the 3-breed crosses and therefore require less feed inputs so they should maintain their body condition better on the more extreme hills.

 Overall ewes achieved high levels of performance for their age with less than 10% ewes barren and rearing on average 1.21 lambs each.  There was little difference in ewe performance between the two breeding strategies examined.

The key indicator of both economic and environmental sustainability is ewe efficiency.  This is measured in terms of the weight of lamb weaned per kilogram of ewe body weight and therefore considers the combined effects of ewe fertility, mortality and lamb growth rates on lamb output.

  With the exception of Texel X ewes, whose lower litter size tended to limit lamb output, all the breeds evaluated achieved efficiencies of around 0.90 and above, which effectively means that the average lamb output of each ewe was equivalent to an impressive 90-100% of their body weight.        

The study is continuing for a further 2 years to investigate lamb output from the older 3 and 4 crop ewes, and to assess the effects of replacement breeding strategy on ewe longevity.

 Further information on the study to-date can be obtained by visiting the AFBI and AgriSearch stands at the ‘NSA Sheep NI 2013’ in Ballymena market on Mon, July 1.  For details browse www.agrisearch.org

Table 1.  Effect of replacement breeding strategy on hill ewe performance (1 and 2 crop)

 

Weight at mating (kg)

Conception rate

(%)

Lambs weaned per ewe lambed

Total weight weaned (kg/ewe)

Ewe efficiency

(kg lamb weaned per kg ewe)*

Criss-cross

 

 

 

 

 

Blackface X

47

91

1.14

44.5

0.92

Swaledale X

48

92

1.36

46.8

0.96

 

 

 

 

 

 

3-breed crosses

 

 

 

 

 

Belclare X

53

98

1.20

48.7

0.91

Highlander X

50

96

1.31

48.7

0.97

Lleyn X

51

100

1.13

44.8

0.88

Texel X

53

94

1.10

43.9

0.82

·        Target = 1 kg lamb weaned for every kg ewe body weight