RESEARCH ON LONGEVITY AND CAUSE OF REDUCTION OF HERD LIFE IN HOLSTEIN COWS Mădălin GAVRILĂ, Gheorghe Emil MĂRGINEAN, Alexandru KELEMEN University of Agronomic Sciences and Veterinary Medicine of Bucharest, 59 Mărăşti Blvd, District 1, 011464, Bucharest, Romania, Phone: +4021.318.25.64, Fax: + 4021.318.25.67 Corresponding author email: gavrilaimadalin@gmail.com Abstract Through this research we intend to analyze the Holstein herds in farms of various sizes from Teleorman County to highlight the productive performance of the breed and to emphasize the similarities, respective the differences that were found in the studied farms and furthermore, another goal of the study was to show that the breed is very valuable.The Holstein cows studied for this paper are from various origins (Germain, France, Netherlands). The material studied is represented by the dairy cows that were send to slaughterhouse from 5 farms, representing 1200 heads.The lifetime of the animal is defined by two aspects, namely, the biological longevity and the productive longevity.We can observed, from the data processed and interpreted by us, that the greatest biological longevity was registered in farm 1 (6.27 years), where the productive longevity was 3 years old.The highest frequency of reproductive disturbances was registered in the farm No.4 (58.33%) and farm No. 3 (55%).The data held by us from the 5 farms that were analyzed shows higher rates of reproductive disorders comparative to that established by Curelariu of 43.66% et al (1980) and Vidu of 28,52%(2002).The herds analyzed are characterized by a mean of 5.71 years for the biological longevity with a variability between 5.10 years and 7.24 years, which is consistent with the literature. Key words: milk, biological longevity, reproductive longevity, dairy cow INTRODUCTION A particularly very important indicator for animal welfare is the longevity, as a result of the health welfare. The lifetime of the animal consist of two parts, namely the biological longevity and the productive longevity. Both components of the animal life are influenced by the following factors: the degree of genetic improvement, the direction of exploatation, the applied technology and health. The biological longevity can be defined as beeing the time elapsed from birth until the death, as a result of natural causes. Normally, lifespan of the cattle is between 15 and 18 years, being influenced by the physiological and environmental factors. The reproductive longevity or the exploitation period is between the first calving and the final lactation of the cow.It can be expressed by the number of lactations or years of exploitation. High productive longevity is reflected by high yields of milk and by a larger number of calves per cow, which leads to increased economic efficiency (Georgescu, 1990; Vidu, 2002). From an economic perspective, it is desirable for productive cows to achieve the production peak at an early age, to keep production constant for as long as possible and to obtain at first the lactation a milk production as close to the maximum level. 284 Scientific Papers. Series D. Animal Science. Vol. LVIII, 2015 ISSN 2285-5750; ISSN CD-ROM 2285-5769; ISSN Online 2393-2260; ISSN-L 2285-5750