The aim of the study was to determine the influence of suckling period on milk production of sheep from Bulgarian Dairy Synthetic Population (BDSP) grown in the Еxperimental base of the Agricultural Institute in Shumen. Total 5023 record are analyzed for milk yield for monthly control days of 601 ewes (born 2007th -2012th years) produced from 1 to 6 lactations. To achieve unbiased evaluation was used animal model for test day. The statistical analysis included the following factors: month of the controls, consecutive lactation, age in days to the date of the control day, days suckling period and the number of lambs for the relevant lactation of the animal. The results show that the duration of the suckling period influences the milk productivity of sheep from BDSP. In ewes with suckling period of lambs exceeding 30 days, production of milk progressively decreases from 0.911 liters to 0.554 liters (-0.357) at suckling period of 80 -90 days. Improving the management of the flock towards reducing the suckling period can lead to a significant increase in milk production.

Objective of the study was to establish the present generated genetic structure in the sheep from the nucleus herd of the Bulgarian Dairy Synthetic Population on the Experimental Farm of Agricultural Institute -Shumen. Subject of study are the ewes borne during the period 2007-2012 with available records for the main selection traitsmilk yield and prolificacy. On the basis of the information from the pedigree books was build up a database of the pedigrees of 601 ewes. For each individual was constructed a genetic code representing the breed belonging of the ancestors back to third pedigree level. The established genotypes are formed with the participation of the breeds: 1 -Bulgarian Dairy Synthetic Population; 2 -Lacaune; 3 -Chios; 4 -East Friesian; 9 -with unknown pedigree. For the particular period of study, the genetic structure of the herd is formed by 33 genotypes. The highest portion of 78.21% is that of the ewes produced by linebreeding, shared by the BDSP genotype (53.91%) and those with genetic component from EF (24.3%). The F 1 crossbreds with Lacaune and Chios (9.99 and 3.33%), the genotypes of the offspring resulted from them after mating with BDSP rams (2.16, 1.16 and 0.33%), and those of unknown pedigree from the side of one of the parents (1.83%) do not affect the overall genetic structure of the herd. With regard to the degree of grading from the different breeds, there are 15 genetic groups formed in the herd. The established variability of genotypes and genetic groups is to be grounded on the principle of forming the scientific hypothesis for evaluation of the genetic effects -additive and non-additive. Disregarding the non-additive genetic component in the process of crossbreeding would result in biased estimate of the genetic variability and in wrong prediction for the further development of the genetic structures of the population.

Article InfoThe purpose of the present study was to analyse the genetic variance (additive, dominance, epistatic) of milk yield and the resulting genetic effects in Bulgarian Dairy Synthetic Population (BDSP) sheep in the framework of an experiment for introduction of Chios and Lacaune sheep in the breeding and selection schedule of BDSP. A test-day model was used including daily milk yields as separate observation. The observed genetic variance was substantial, comprising 0.33 of the total variance. The proportion of the additive genetic variance was 0.23, while that of nonadditive: 0.10 of the total variance. The observed genetic effects were statistically significant, and dominance genetic effect was positive (137.18). Additive genetic effect was also positive (27.86), and together with the dominance variance it constituted the major part of genetic variance. The epistatic genetic effect was negative (-33.15). The estimates of additive genetic effects and non-additive deviations for tested genetic groups showed diversity and deviations depending on the percentage of blood of the different breeds and pathways of genotypes' formation.

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Abstract. The aim of this study was to determine the quality and quantity of the wool yolk of the rams from Caucasian merino breed in order to improve their technological features. The analyses included seven rams and eleven rams at the age of 18 months. Thirty-six individual wool samples from two parts of the body (side and thigh) were studied. The following wool parameters were investigated: percentage of the dirty areas of the wool (on the side and the thigh), fat amount, sweat amount, pH of sweat, laboratory wool yield, and color of greasy wool on the side. Percentage of the dirty areas of the wool by categories and topographic ranges varied from 30.79% to 41.52%, indicating that the wool yolk of Caucasian rams was of sufficient quantity and good quality. The percentage of the fats in wool yolk to the greasy wool was relatively high (23.25% in the rams at the age of 18 months and 25% in the rams) and had a negative impact on the wool yield. The ratio of fat/sweat was 1.91:1 in rams and 1.44:1 in rams at the age of 18 months). The higher relative part of the fat compared to the sweat was an indicator of good protective properties of the wool yolk. That allowed to protect the technological properties of the wool.

Abstract. The aim of the study was to establish the levels of the main selection traits which determine the technological wool production in the rams

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