Table 1 Population, biological and economic parameters for four alternative breeding schemes for Gumz sheep

Proportion of populations in

Production unit

1.0

1.0

0.95

0.90

Central nuclei

0.05

0.10

Proportion of ewes lambing

0.48

0.80

–

–

Lifetime use (years) of:

Rams in central nucleus

–

–

0.67

0.67

Rams in villages

2.5

2.5

2.5

2.5

Ewes in central nucleus

5

5

Ewes in villages

5.0

5.0

5

5

Mating ratio (F/M)—villages

35

35

35

35

Mating ratio—central nucleus

–

–

35

35

Lambing interval (years)

0.60

0.60

0.60

0.60

Conception rate—central nucleus

–

–

0.85

0.85

Conception rate—villages

0.85

0.85

0.85

0.85

Age at first lambing (years)

1.14

1.14

1.14

1.14

Twinning rate

1.32

1.32

1.32

1.32

Survival of rams—villages

0.85

0.85

0.85

0.85

Survival of rams—central nucleus

–

–

0.85

0.85

Survival of ewes—villages

0.85

0.85

0.85

0.85

Survival of ewes—central nucleus

–

–

0.85

0.85

Lamb weaning rate—village

0.85

0.85

0.85

0.85

Weaning rate—central nucleus

–

–

0.90

0.90

Suitability for breeding^a

0.90

0.90

0.90

0.90

Fixed costs per ewe (Birr)

12.0

12.0

158.9

158.9

Variable costs per ewe (Birr)

12.05

12.05

11.37

11.37