Last update: November 25, 2010 11:36:58 AM E-mail Print

 

PRODUCTION AND REPRODUCTION PERFORMANCE OF

THE CARNARVON AFRINO FLOCK

 

Dr. Gretha Snyman

Grootfontein Agricultural Development Institute, Private Bag X529, Middelburg (E.C.), 5900

 


The Afrino flock at the Carnarvon Experimental Station consists of 200 breeding ewes and is used primarily for the investigation of suitable selection criteria for Afrino sheep under extensive conditions. Research results obtained in this Afrino flock, run under similar conditions as in which the majority of Afrino sheep in South Africa have to produce and reproduce commercially, are applied in practice. For example, the Afrino is the first South African sheep breed in which the separation of ram and ewe selection objectives had been investigated and applied. Rams are selected on growth and fleece traits and ewes on reproductive traits, which incorporate fertility and mothering ability.

 

Management of the flock

Animals are kept under veld conditions and receive no supplementary feeding or licks. Mating takes place during a five week breeding season in April, where 4% rams are used. Rams are randomly allocated and hand-mated to the ewes. All lambs are identified and tagged at birth and birth weight as well as sex, birth status and pedigree information are recorded. Lambs are weaned at ap­proximately 100 days of age. All ram and ewe lambs are retained until the age of 16 months. Monthly body weights from five to twelve months, as well as at 16 months of age are taken for all lambs. Performance testing of wool traits is done at 16 months of age under the National Small Stock Improvement Scheme.

 

Selection procedures

Since 1987, only rams with above average indices for pre- and post weaning growth traits, as well as below average fibre diameter, were used in the stud. Emphasis was also placed on wool quality and evenness of fleece, while the amount of wool produced received little attention. Since 1991, all selection done in the flock has been based on BLUP of breeding values for the specific traits under selection.

 

Since 1985, all available young ewes, with the exception of those with conformation or wool faults, or those having a fibre diameter of more than 5% above average, were mated. Final ewe selection was done on the basis of total weight of lamb weaned after the first parity. Older ewes which failed to lamb or wean a viable lamb/s, were also culled.

 

Production and reproduction performance

The average production performance of Afrino ram and ewe lambs, recorded from 1980 to 2000 under veld conditions in the Carnarvon Afrino flock, is summarised in Table 1. In Table 2 the average performance of the reproducing ewes in the same flock is presented, while the average slaughter traits for Afrino lambs at Carnarvon are given in Table 3.

 

Table 1. Average production of Afrino ram and ewe lambs under veld conditions in the Carnarvon Afrino flock (1980 - 2000)

Trait                                                                                     Rams              Ewes

Birth weight (kg)                                    4.7           4.4

42-day body weight (kg)                              17.5          16.2

100-day weaning weight (kg)                          30.3          27.7

Average daily gain from birth to 100 days (g/day)    240           219

9-month body weight (kg)                             47.8          42.6

12-month body weight (kg)                            60.0          51.1

16-month body weight (kg)                            63.8          51.8

16-month fleece weight (kg)                          3.56          3.26

16-month clean fleece weight (kg)                    2.05          1.99

16-month fibre diameter (μm)                         20.3          20.6

16-month clean yield percentage                      57.6          60.6

 

 

Table 2. Average performance of reproducing Afrino ewes under veld conditions in the Carnarvon Afrino flock (1985 - 1999)

Body weight                                  60.0 kg

Raw fleece weight                            2.90 kg

Clean fleece weight                          1.80 kg

Fibre diameter                               21.6 μm

Clean yield percentage                       62.9  %

Staple length                                76.6 cm

Lambs born/ewe mated                         142  %

Lambs born/ewe lambing                       152  %

% Stillborn lambs                            3.4  %

Lamb survival rate                           94  %

Lambs weaned/ewe mated                       137 %

Milk production 4 weeks post partum          2.2 litre/day  (1995)

Milk production 8 weeks post partum          1.5 litre/day  (1995)

Total weight of lamb weaned/ewe/year         40.7 kg

 

 

Table 3. Average slaughter traits for Afrino lambs at Carnarvon (1986 - 1991)

Slaughter weight                            42.1 kg

Average daily gain (birth to slaughter)     184 g/day

Age at slaughter                            223 days

Carcass weight                              19.8 kg

Dressing percentage                         47.1 %

 

Genetic improvement in the Carnarvon Afrino flock                  

The genetic trends in the economically important traits are illustrated in Figures 1 and 2 for this flock. It is evident from Figure 2 that, since selection has been based on objective measurement of fibre diameter, fibre diameter decreased genetically by 2.3 µm. By utilising performance testing information, it was possible to genetically increase body weight and lifetime total weight of lamb weaned, while simultaneously decrease fibre diameter in the Carnarvon Afrino flock.

 

Fig 1. Genetic trends in weaning weight, 9-month and 16-month body weight and weight of lamb weaned in the Carnarvon Afrino flock

 

 
Fig 2. Genetic trends in 16-month clean fleece weight and fibre diameter in the Carnarvon Afrino flock