- Production standards for Afrino sheep
|Last update: August 18, 2011 10:18:19 AM|
PRODUCTION STANDARDS OF AFRINO SHEEP
J.J. Olivier. M.A. Badenhorst & J.A.N. Cloete
Agricultural College Grootfontein.
The trials which led to the development of the Afrino started 20 years ago at the Carnarvon experimental farm. Since 1969 a considerable amount of production standards have been collected of Afrinos in that specific area. An Afrino flock of 200 ewes has been mated annually during autumn since 1977. All the progeny were kept up to age 14-16 months and used to collect production data. From this it has been possible to collect reasonably accurate production data standards. These will now be discussed.
Besides this group an additional 50 ewes have been kept since 1986 at Carnarvon and a further 50 ewes at Tarka Conservation Area. The Tarka Conservation area is near Hofmeyr where the annual average rainfall is 4OOmm. This rainfall is almost double that of the Carnarvon Experimental farm. These two groups of ewes are mated annually during April & October for a period of 30 days. All young replacement ewes are mated for the first time at 12 months of old and all surplus ram Iambs and ewe Iambs are slaughtered at an age of 40 kg live mass. The data collected provides important information regarding production and reproduction of the Afrino under different environments.
The average reproduction rate (or lambing percentage) of the Afrino ewes at Carnarvon over a 3-year period since 1977 is presented in table 1. During the entire period the incidence of multiple births was about 157% and for every 100 ewes mated 130 Iambs were weaned. These results were obtained with autumn mating. It can be assumed that with spring mating a lower lambing percentage will occur. Despite of the high percentage of multiple births the percentage of stillborn Iambs and percentage of Iambs that die from birth to weaning age remains low (Table 1).
The experiments at Carnarvon and Tarka Conservation area since March 1986 have not been operating long enough to enable one to make accurate assumptions. Nevertheless interesting tendencies can be observed. In table 2 the number of Iambs weaned per 100 ewes available for mating is shown. Many of these ewes were mated while they had Iambs of a month age and younger at foot. A decided difference can be observed between the ewes of Carnarvon and those at Tarka conservation area. At Carnarvon large seasonal differences occur with the majority of Iambs being born in spring. At Tarka the majority of Iambs are also born in spring but the difference between spring and autumn lambing is smaller. It is also interesting to note that the annual lambing percentage (March & October) is higher at Carnarvon than at Tarka.
Of the original Afrinos at Carnarvon very few animals were slaughtered so available data is insufficient for accurate conclusions. However all surplus progeny of the 50 ewes at Tarka and Carnarvon since 1986 has been slaughtered. The average data over the years was poolled and this can be found in table 3.
All Iambs were slaughtered when they reached a live mass of about 40 kg. The average carcass mass varied between 16.5 kg and 18.3 kg. This variation was mainly due to varying slaughtering percentages which ranged from 46.7% to 49.6%. At Tarka the spring Iambs reached the slaughter mass at an earlier age (152 days) than the autumn Iambs (169 days). At Carnarvon this tendency was reversed with the autumn Iambs marketable at an earlier age than the spring Iambs. These differences can be ascribed to differences in the amount and pattern of the rainfall.
Table 4 illustrates what percentage of Iambs reached the required slaughter mass at a specific age. The marketing pattern of the autumn Iambs of Carnarvon and the spring and autumn Iambs of Tarka was much the same and all surplus Iambs were marketed at 8 months or younger. The spring Iambs of Carnarvon however required an extra 3 months before the last reached marketable mass. At the age of 8 months 73% of these surplus Iambs had reached the required marketable mass.
The average grease wool production of the Carnarvon flock was 3,2 kg per annum. During the last 5 years the average micron count was 22,4 micron with a yearly average variation from 22,1 to 22,9 micron.
This norm can be used as a basis to determine the profitability of Afrino farming. The woolled sheep management model of Grootfontein (Herselman 1989) is used to determine the gross margin above specified costs. The fixed and variable costs used for this purpose are kept constant in all cases. These are indicated in table 5.
The reproduction (lambing percentage) and wool production data obtained from the Carnarvon Afrinos over a considerable number of years is used as the norm. (Table 6). The marketing pattern of the surplus Iambs at Carnarvon is also used. Using this norm it was found that a gross margin of R90.53 per SSU was realised (Table 6). The question immediately arises as to how lambing percentage, wool production, fibre diameter and marketable age would affect the figure of R90.53, should these specific properties be altered. Because of the number of variables as well as the interaction between the variables (a rise in wool production results in lower reproduction) only a few probabilities are indicated in table 6.
If reproduction is lowered by 15% the gross margin is lowered by R7.36 (81 %) and if reproduction is raised by 10% the gross margin is raised by R4.49 or 5%. The effect of an increase of 1 kg in wool production and a reduction of 4,5% in the fibre diameter is also indicated in table 6. If the marketing pattern of Tarka is used an increase of R3.19 in the gross margin is obtained.
These norms and gross margins only have a bearing on this specific case and vary from area to area and even from farm to farm. The figures however stress the importance of the availability of accurate production to enable one to do accurate long term strategic planning.
Afrino manual 46 - 51.