MORPHOMETRIC CHARACTERIZATION OF PIROT PRAMENKA

: The strategy of conservation of endangered sheep populations implies morphological and genetic characterization, as basic preconditions for their conservation. The aim of this study was to determine the morphometric characteristics, their correlations and the index of physical development of Pirot pramenka, which has the status of the most endangered population in Serbia. The measuring was performed on 30 sheep, aged 3 years, reared in the area of Stara Planina. The descriptive statistical procedure was performed using the statistical package Statistica (version 8). The average height at the withers was 56.31 cm, body length 62.93 cm, chest width 18.37 cm, chest depth 25.96 cm, chest circumference 77.59 cm, shin circumference 6.70 cm. The strongest and significantly positive correlation (P <0.05) was found between chest depth and height at withers (0.65), body length (0.58) and body weight (0.56). Pirotska pramenka has slightly higher indices of format, chest and massiveness, in relation to breeds Vitoroga Žuja and Travnik Pramenka. These morphometric traits suggest that, compared to previous research, the body frame of Pirot pramenka sheep did not change significantly, which means that there were no crosses with other breeds due to geographical isolation and enthusiasm of breeders to preserve the indigenous Pirot pramenka which was the starting point for following authentic brands: Pirot lamb, cheese and carpet. Hence the biological and moral imperative: to preserve this highly endangered population.


Introduction
Strains (ecotypes) of the indigenous breed of sheep -Pramenka were formed during a long process of evolution in certain biological areas, limited by geographical entities, in different feeding and housing conditions, which resulted in their specific morphological and production performance.However, the expansion of high yielding breeds in the race for profit, on the one hand, as well as the depopulation of the rural environment, on the other hand, caused some strains of Pramenka to become endangered in their biological survival.Pirotska pramenka is one of the most endangered sheep populations in Serbia.According to data of the Domestic Animal Diversity Information System (DAD-IS), in 2021, 207 females and 25 males are reared in Serbia.The effective size of the population is 89 heads, which classifies it as highly endangered and is at risk of complete extinction.At the same time, it is the source of extraordinary national brands: Pirot lamb, Pirot carpet and Pirot cheese, which imposes its preservation as a biological, economic and moral imperative.The first step in the concept of sustainable use of genetic resources is their identification, description, development and monitoring, and subsequently their conservation.The variability and differentiation of different strains of pramenka in the Balkans has been the subject of numerous studies: Mioč et al. (1998;2003) performed tests on Lika and Dubrovnik Pramenka, while Antunović et al. (2013) and Novoselec et al. (2020) determined the morphometric properties of Travnik pramenka.Važić et al. (2016;2017a;2017b) compared the exterior measures of the Privor, Dub and Kupreška pramenka, while Ćinkulov et al. (2003) conducted research on Tsigaia and Pihler et al. (2019) examined the phenotypic variability of Vitorog Žuja breed.
Morphometric measurements of sheep are important because they are a reflection of breed standards (Verma et al., 2016).They provide us with valuable information about the morphological structure and ability to develop an animal.Linear body measurements are an indicator of an animal's growth during life (Attah et al., 2004) and are helpful in predicting body weight and carcass characteristics (Thiruvenkadan, 2005).Determining different body measurements of animals is of great importance in assessing the quantitative parameters of meat, and helps in the development of appropriate selection methods (Kumar et al., 2017) and proper implementation of breeding and selection work.Body weight of farm animals is useful information in determining daily feeding need, growth assessment, medication administration, and its changes are a possible indicator of certain animal health problems on the farm or herd (Paresd et al., 2014).There are no current researches in the available literature that refer to the morphometric characterization and indices of physical development of the Pirot Pramenka.
Taking into account the above, the aim of this paper is to present the results of external measurements and body development indices of Pirot Pramenka, which can be used as a basis for morphometric characterization, which is a necessary prerequisite for the preservation of this highly endangered sheep.

Material and Methods
Pirot pramenka originated in eastern Serbia, in the vicinity of Pirot, after which it was named.It is also reared in the municipalities of Dimitrovgrad, Bela Palanka and Babušnica.It is a small, lively, mobile and late-maturing sheep, with combined production traits, meat-milk-wool.It belongs to the long-tailed Pramenka.The sheep have white, fine wool, and there are also heads with black and thick wool.The fleece is semi-open, with funnel-shaped strands.The sheep are hornless, and the rams are horned.Milk yield is 75-80 kg in lactation, which lasts about 180 days.Pirot Pramenka is mature and ready for breeding at the age of 16-18 months.Fertility is 100-115%.The characteristics of this sheep, like most Pramenka, are pronounced resistance, adaptability and modesty.The research was conducted on 30 sheep of Pirot Pramenka, aged about 3 years, reared in the area of Stara Planina, in the winter.The diet consisted of meadow hay (ad libitum) and 0.3 kg of corn, per head/day.Taking body measurements of sheep was done with the help of Litin's stick and ribbon, and determining body weight, with the help of livestock weight scales.The measurement was performed by one person, with the help of an assistant.The influence of the evaluator was excluded in this study.Each sheep was measured on a flat surface, on the left side of the animal.The following body measurements were taken: height at withers, body length, chest width, chest depth, tail length, chest circumference, pelvic width, shin circumference and body weight.
HW: The height at withers represents the vertical distance from the base, behind the front hoof, to the highest point at the withers (the area between the 2nd and 5th dorsal vertebrae).
DT: The body length represents the distance from the anterior edge of the shoulder-blade joint to the posterior point of the sciatic hump.
CHW: Chest width represents the distance at the narrowest point behind the shoulder blades.
CHD: The chest depth represents the vertical distance from the lower edge of the sternum to the highest point at the withers.
CHC: Chest circumference is the body circumference, measured at the chest just behind the shoulder blades and measured with a ribbon PW: The width of the pelvis represents the distance between the outer edges of the tuber ischii.
SHC: The shin circumference is measured with a ribbon at the thinnest point on the shin of the front leg.
The body weight of the animal is measured using livestock weight scales.Indices are the absolute values of a measurement in relation to another body measurement, expressed as a percentage.These indices are used to determine the proportions of the animal body and to more precisely compare the development of individuals (Ćinkulov et al., 2003).According to Ćinkulov et al. (2003), the following are calculated: format index, chest index, chest depth index, body compactness index, massiveness index, pelvis and chest index, leg length index and forehead width index.(Mitić, 1987), Dubrovnik Pramenka (Mioč et al., 2003) Dublje, Privor and Kupreš Pramenka strains (Važić et al., 2017), Lika (Mioč et al., 1998) and Travnik Pramenka strains (Novoselec et al., 2020) and Vitorog Žuja (Pihler et al., 2019), we can conclude that in the present study, in terms of height at withers ( 56.31 cm), Pirot Pramenka had similar values with Pag and Rab sheep and slightly higher vaues than Krk sheep.The value obtained for body length (62.93 cm) was higher compared to the Krk strain and lower than other Pramenka strains.In terms of chest depth (25.96 cm) and shin circumference (6.7cm), Pirot pramenka had lower values than the mentioned Pramenka strains, while it had higher value for chest width (18.37 cm), compared to the Lika Pramenka (16.64 cm) and the Pag sheep (17.11 cm) and similar to the Vitoroga Žuja (18.89 cm).If we compare the above exterior measures of Pirot Pramenka with older data (Mitić, 1987) for the same population, we can conclude that, in regard to its exterior, this Pramenka remained almost the same (height at withers 55 cm), which means that it was least exposed to other breeds of sheep and changes in production technology.Differences in terms of morphometric properties compared to other populations of Pramenka are a consequence of different nutritional and production statuses of the animals (Table 2).The determined indices of body development follow their body measures.These indices are used to determine the proportions of animal bodies as well as for a more precise comparison of individuals (Ćinkulov et al., 2003).Pirot pramenka had slightly higher indices of format, chest and massiveness in relation to Vitoroga Žuja and Travnik Pramenka, which is in accordance with the research of Ćinkulov et al (2008) as well as Ćurković et al. (2016), who have determined minimal genetic differentiation between seven strains of Pramenka, which is explained by similar agroecological rearing conditions as well as population mixing throughout the long history of population migrations.The correlation coefficients between individual phenotypic traits of Pirot pramenka are shown in Table 5.A positive correlation between phenotypic traits and body weight of sheep was determined.The strongest and significantly positive correlation (P<0.05) was found between chest depth and height at withers (0.65), followed by body length (0.58) and body weight (0.56).High correlation coefficients between individual morphometric traits of Pirot Pramenka sheep indicate that these variables and their combinations can be used in breeding selection procedures.

Results and Discussion
These morphometric traits suggest that, compared to previous research, the body frame of Pirot Pramenka sheep has not changed significantly, which is useful information and the first step in the program of conservation of this genetic resource from extinction.The next step within the global strategy of preservation is determination of the genetic structure of this population, which will be the subject of our further research.

Conclusion
Pirot Pramenka has the status of a highly endangered population and is at risk of complete extinction.Its preservation is a biological and moral imperative since it is source of important national brands: Pirot lamb, Pirot cheese and Pirot carpet.The first step in this strategy is morphometric characterization of the population.Compared to previous studies, the body frame of this Pramenka did not change significantly, which means that there were no crosses with other breeds due to geographical isolation and the desire of breeders to preserve the autochthonous Pirot Pramenka.By analyzing the correlations between individual body measures and the weight of Pirot Pramenka sheep, a positive correlation was determined.The strongest and significantly positive correlation (P<0.05) was found between chest depth and height at withers (0.65), body length (0.58) and body weight (0.56).Pirot pramenka had slightly higher indices of format, chest and mass in relation to Vitorog žuja and Travnik Pramenka.Since the morphometric characteristics of the animals are a reflection of the breed standard, their determination is a necessary precondition for the preservation of this highly endangered sheep population.
Ključne reči: pirotska pramenka, morfometrijske osobine, korelacije, indeksi Descriptive statistical processing of data related to external measurements and indices in the population of Pirot Pramenka was performed using the statistical package Statistica (version 8).

Table 1 . Morphometric properties of Pirot Pramenka
SD = standard deviation; SEM = mean standard error; CV = coefficient of variabilityTable 1 shows that the highest value of the coefficient of variation was established in the following traits: horn length (35.63%) and tail length (17.85%).Pirot pramenka sheep in this study had lower body weight, lower height at withers, lower values for body length and chest depth, and higher values for chest width and tail length, compared to the desirable body measures listed in the Main Breeding Program for Indigenous Sheep Breeds 2020-2024.According to body development, Pirot Pramenka belongs to the group of less developed sheep, with a smaller body format.If we compare it with Liplje Bardoka

Table 3
shows the body development indices of Pirot Pramenka sheep.The highest coefficient of variation (15.75%) was recorded in the chest and pelvis index and the lowest (4.25) in the leg length index.

Table 3 . Indices of body development of Pirot Pramenka
Mean = arithmetic mean; SD = standard deviation; SEM = mean standard error; CV = coefficient of variability