Last update: March 26, 2012 02:27:30 PM E-mail Print

 

Slaughtering Characteristics of the Afrino 

J.J. Olivier & J.A.N. Cloete*

Landboukollege, Grootfontein, Middelburg, K.P.

Grootfontein Agricultural College, Middelburg, C.P.

* Carnarvon Experimental Station 

THE Afrino is a white-woolled mutton breed; its primary product is mutton and its secondary product wool. The revenue that the producer receives from mutton is determined by die number of animals marketed, carcass mass and the grading of the carcass. The number of animals marketed is determined by the reproduction rate. The Afrino's reproduction rate is already known (134% lambs weaned per ewe mated). Very little is known, however, of the Afrino's carcass qualities.

During 1984, 50 F3 and F4 Afrino ewes were mated to four Afrino rams at the Carnarvon Experimental Farm. All lambs born have been allocated to the following treatments within generations:

25% slaughtered at 100 days

25% slaughtered at 120 days

25% slaughtered at 35 kg live mass

25% slaughtered at 40 kg live mass

 

The lambs ran under veld conditions and the normal dosage and inoculation program has been adhered to. Lambs were fasted for 12 hours before being slaughtered. After slaughter the carcasses were hung for 24 hours at 4°C before any measurements were taken. The C-fat-thicknesses (eye muscle fat) was measured according to the method described by Bruwer, Naudé and Vosloo (1984). The data was analysed utilising a smallest square analysis to correct for fixed effects as a result of sex, birth status and dam's age.

The lamb carcasses were too light at the 100-day and 120 day ages, although some of the lambs were marketable at these ages. It can be seen from Table 1 that the desired carcasses reached a live mass of 35-40 kg. According to Bruwer et at (1984), the desired degree of fatness is reached if the C-fat-thickness (between 3 and 4 lumbar vertebra) is 4-9 mm. Lambs slaughtered at 35-40 kg body mass reached these average fat thicknesses (Table 1). According to the Meat Board (1981) slaughter lamb production should be directed at a carcass with optimal fat weighing 18-20 kg. With these guidelines it is clear that lambs slaughtered at 40 kg live mass were the nearest to the norm. The somewhat lower kill-out percentage, which occurred at 40 kg, is ascribable to the fact that the animal carried more wool at that age.

It took the lambs an average of 204 days to reach the 40 kg live mass. At this age they can already be shorn, yielding additional revenue.

 

In the case of Afrino lambs the optimum carcass is reached at a live mass of 40 kg. Under extensive conditions it took an average of 204 days to reach this mass. Under favourable conditions this mass should, however, be reached at an earlier age. Some lambs reached 40 kg at an early age (158 days) while it took others considerably longer (250 days) to reach this mass. It also appears that the lambs have not accumulated too much fat at an early age and a low carcass mass. This is important as not all lambs can be marketed at the stage of reaching the desired body mass and consequently must be held over. An investigation is presently underway to ascertain at what age and/or mass Afrino lambs become overfat.

 

Literature

BRUWER, G.G., Naudé R.T.. & VOSLOO, W.A., 1984. Objektiewe evaluering van die karkasgradering:stelsel van Lammers en skape. Vleisraadfokus Des. 8

VLEISRAAD, 1981. Die produsent se belange in die graderingstelsel. Vleisraadfokus, Junie 19.

 

Published

Afrino Manual 1986