Introduction

Turkey has a very young human population which is increasing rapidly, therefore the need for foods of animal origin is also increasing. The sheep population of 29.4million heads (FAO, 2002) in the country is an important resource for meeting this demand. This sheep population represents the first and seventh place in Europe and the world, respectively. The great majority (97%) of this sheep population is composed of indigenous breeds which have low production levels. However these breeds can continue to be productive under harsh climate and poor feeding and management conditions which they have adapted to over hundreds of years. In the arid, semi-arid and hilly areas of Turkey these breeds serve their breeders as food for life and as a source of economic income. The conservation of these indigenous sheep breeds as genetic resources might also assist the adaptation of farm animals to new environmental conditions which might occur in the future. It is important that the natural resources be preserved while simultaneously producing enough food to satisfy the demands of a growing human population (Boyazoglu,2002).

As a result of crossbreeding and shrinking breeding areas, the numbers of the purebred indigenous Imroz and Kivircik sheep breeds are decreasing. Because of this, these breeds have been included in a project for the conservation of indigenous breeds as genetic resources in Turkey.

This study was carried out to investigate the fertility, milk production and body weight of ewes and the survival and growth characteristics of lambs of the indigenous Imroz and Kivircik sheep breeds.

Land and Climate

Imroz (Gokceada) is the name of an island in the Aegean Sea, off north-western Anatolia. The Imroz sheep breed has been found on this island for more than one hundred years. The Imroz and Kivircik sheep breeds are raised in the Marmara Region. This region encompasses the transition between the Black Sea and Aegean Regions. The climate is predominantly Mediterranean; however, dry season aridity is not as great as along the Mediterranean coast. Temperature and rainfall vary markedly within relatively short distances. Average temperatures are 23-27°C in the warmest months and 1-8°C in the coldest months, with an annual precipitation of 590-810 mm. A relatively superior topography and denser population have contributed to make the region one of the most intensively cultivated in the country. Therefore sheep in this region have to compete with field crops (Figure 1). Success in this competition will largely depend on the intensification of sheep breeding and as such there is the need to determine the real production potential of the indigenous sheep breeds under intensified conditions (Yalcin,1986).

Figure 1. The ewe flock grazing in spring time.

Imroz

The breed is among the smallest sheep breeds in the country. Animals are predominantly white, with black marks around the mouth, nose and eyes, on the ears and rarely on the tip of the legs. The tail is thin and long, usually reaching below the hocks. Rams have strong spiral horns extending sideways; ewes are usually polled but up to 30% of the ewes may have small scurs. The head is narrow and its profile is straight. The wool is very coarse and long, and it covers the top of the head (Figures 2 and 3).

Kivircik

This is a medium-sized breed. Animals are white with long, thin tails, usually reaching the hocks. Rams have horizontal spiral horns extending sideways; ewes are usually polled. The ears are relatively short and extend horizontally. The fleece is of carpet-wool type, but the wool is of better quality than the wool of all other indigenous breeds in Turkey (Demir, 1997) (Figures 4 and 5).

Materials and Methods

This study was carried out in Marmara Animal Breeding Research Institute in the years 2000 and 2001. The purebred samples of the Imroz and Kivircik genotypes, which were gathered in the Institute for the conservation of these breeds as genetic resources, were used in the study. The sheep were collected from a number of villages, which still have pure-bred samples of these breeds, by an expert committee formed by the Institute for the Conservation of Genetic Resources Project in Marmara Region.

The two breeds were managed in the same flock at the Institute. The ewe flock was kept indoors during the winter months and then taken to pasture as the weather conditions improved. Before the mating season, 400-600 g/head of concentrated feed produced at the Institute was given daily to the ewes. A similar program was also used to prepare the ewes for parturition. Oestrus detection was performed daily by using teaser rams and ewes were mated with the selected rams. The lambs were kept together with their dams in individual boxes for the first three days after birth, then a flock composed of suckling lambs and their dams was formed. The suckling program of the lambs lasted for three months (90 days) on average. During this program, grass hay and lamb grower feed were given to the lambs to speed up rumen improvement.

To assess the fertility characteristics of the ewes, the conception rate, rate of infertility of ewes, birth rate, rate of single births, rate of prolific births, lamb production and litter size traits were determined for each genotype group. The body weights (after shearing) of ewes (2-7 years of age) were determined by weighing with a scale sensitive to 0.1 kg.

Milk yield in one lactation and lactation lengths were investigated. On milk control days, lambs were not allowed to suckle. The formulation below was used to calculate milk yield of any ewe in one lactation as;


where:

M = milk yield of any ewe in one lactation(kg);
A1= the first control date;
D = date of birth;
k = milk yield in the first control (kg);
k and k’ = milk yields of consecutive controls (kg);
A and A’ = consecutive control dates (day) and
S = drying off date.

The survival rates of the lambs were evaluated up to the age of weaning (90days). To determine this characteristic all lambs that died and the reasons for death were recorded.

The statistical comparisons between genotype groups in respect of the milk production traits and live weight of ewes were made by t-test (Ozdamar, 1999).

The lambs were weighed monthly with a scale sensitive to 0.1 kg. The absolute 90th day live weights of lambs were calculated by the interpolation method. The birth and weaning weights of lambs were given in Least-Squares Means. The effects of some environmental factors which affect the growth of the lambs were determined using the Least-Squares Means method and the significance of the differences between the groups was determined with a contrast test (Ozdamar, 1999).

Figure 2. Imroz ewe and ram.


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