Cattle farming, as one of the most important branches of livestock production, has longbeen confronted with the chronic problem of the decline in reproductive performances. In 2005, thenumber of cattle around the world amounted to about 1,370,000,000 heads of cattle, while in 2012this number was just over a billion, which indicates the importance of applying differentreproductive protocols in order to increase production. Heat stress leads to disorders of thephysiological and reproductive processes, as the rise in body temperature caused by heat stress hasdirect negative consequences on numerous cell functions. The study included a total of 54 Holstein-Friesian cows, 28 experimental and 26 control cows from PD Butmir farm with 5 lactations onaverage. Hormone protocols for estrus and ovulation were used in June and July 2013. Cows in theexperimental group were subjected to a Presynch + 5dCoS2 protocol. Cows that did not conceiveafter this protocol were immediately subjected to resynchronization with Cosynch -72 protocol. Thesuccess rate of the Presynch + 5dCoS2 protocol was 19%, while in the case of Cosynch 72 it was33%, which was statistically significant (p <0,05). The first presynchronization and synchronizationprotocol (5dCoS2) did not significantly help to improve the conception rate after the firstinsemination postpartum, but it is evident that they had a positive effect on another protocol (COS72)in the form of reduction in embryonic mortality in the summer months when embryonic loss is thegreatest.The COS72 protocol provides satisfactory results in the summer, but good fitness and healthmanagement, as well as heat stress reduction in accordance with the location and farm design arethe preconditions for a successful estrus and ovulation synchronization program prior to artificialinsemination.

: During puerperium phase in cows, uterus goes through involution process, while ovaries restore supressed cyclicity as a result of gestation. After 10-20 days postpartum (PP) luteinizing hormone (LH) levels begin to raise and renewal of cyclicity after parturition is probably most important factor for cows to successfuly conceive again. observed in right ovaries of cows in both groups, while corpora lutea were bigger in multiparous cows. Numbers and sizes of corpora lutea, may give an insight in quality of restoration of ovarian cyclicity and a solid base for prediction on future reproductive performances.

Clinical and subclinical disorders and diseases cause reproductive failures and decline in milk production. Etiology of disorders is mainly because of pathological effect of microorganisms, lapses in nutrition and lodging, as well as in management. After partrition, body is under stress and milk yield is highest, which favors appearance of metabolic and infective diseases. Status of puerperium, number of lactation, body condition score and season of parturition, have highest effect to cyclic ovarian activity. Regular development of dominant follicles, ovulation, formation of corpus luteum and luteolysis is necessary for establishment of regular cyclic ovarian activity, which leads to better fertility. Experiment had included 50 cows during first 52 days of lactation. Cows were separated in two main groups, those with normal puerperium NP (n=32) and abnormal puerperium AP (n=18). Examinations have been performed during period of 6 to 52 days postpartum. Ovarian dominant follicles have been observed using diagnostic ultrasound linear scanner. The highest number of dominant follicles are present during first two examinations, then their number declines and later in last two examinations rise again. Decrease in number of dominant follicles in both groups is most expressed in period of 14-30 days. During first examination, left ovaries have more dominant follicles, compared with right ovaries, while during later examinations, it is changed in favor of right ovaries. Increased number of vital dominant follicles from period 38-45 days postpartum and absence of abnormal uterine content in lumen in same period postpartum is sign of upcoming fertile estrus. Benjamin Čengić et al. 182

________________________________________________________________________________________ KRKALIĆ, L., E. ŠATROVIĆ, N. VARATANOVIĆ, P. DŽAJA, K. SEVERIN: Seroprevalence of Chlamydia abortus in sheep in Bosnia and Herzegovina. Vet. arhiv 86, 373-381, 2016. ABSTRACT An epidemiological study was carried out to determine the seroprevalence of Chlamydia abortus (C. abortus) in sheep in Bosnia and Herzegovina. This was the fi rst systematic study of this kind carried out in Bosnia and Herzegovina. Samples were collected during 2012 and 19 sheep fl ocks, located in the different parts of the country and with a recorded history of reproductive failures (abortion, stillbirths and infertility) were involved. A representative sample from each fl ock was taken by a simple random sampling allowing the detection of seropositive animals within a fl ock with 95 % confi dence, with expected prevalence rates of 20 %, using the recommendations for determining the required necessary sample size to detect the presence of disease. In total 178 sheep blood sera were tested for the specifi c antibodies against C. abortus, with the use of enzymelinked immunosorbent assay (CHEKIT* Chlamydophila abortus Antibody Test Kit). The results showed that 77 (43.3 %) out of 178 ovine sera were seropositive for C. abortus infection, as indicated by the manufacturer’s interpretation of the results. The fl ock was considered to be positive if at least one animal was seropositive. The fl ock prevalence of C. abortus in the examined fl ocks was 84.2 % (16/19 fl ocks). The results of the present study indicate that C. abortus infection occurs frequently in sheep in Bosnia and Herzegovina.

Udder and udder diseases in cows have significant importance in dairy industry and reproduction. Because of intensive selection breeding in last several decades for high milk yield and management systems, udder in cows is under everyday's intensive straining, which makes it more susceptible to harmful inner and outer factors. Those are the reasons for development of various pathology conditions in mammary gland, which cause decrease in milk quality and yield, economy losses and stagnation in planned production. In general, mastitis is recognized as one of the biggest problem in dairy cattle, appeared in subclinical or clinical form. Because of previously mentioned problematic in dairy sector, this book describe various pathological conditions in udder and milk, as well as ways of prevention, therapy and eradication.

– Detection of subclinical mastitis in five different breeds of cows were done on the territory of a municipality Ključ, through all four year seasons by using the California mastitis test, at the level of the udder’s quarter with a certificate of bacteriological findings in order to justify their application in the diagnosis of mastitis. In total, 2150 cows of different breed composition: Simmental 1090, red Holstein 322, Holstein-Friesian 340, montafon 108 and various crossbreeds of 290 in total. After 1978 tested cows, 56.02% of cases had positive reactions to the California mastitis test. The most common positive reaction we found in the milk was in one or two quarters with the intensity of the reaction of one and two plus. The most common causes of mastitis were staphylococci, streptococci and mixed infections. Continuing use of these methods it is possible to timely detect the presence of subclinical mastitis and get satisfactory results in the prevention and treatment of mastitis as well as increasing the quantity and improving the quality of milk.