Cows reproduction and fertility is one of the most subtle physiological functions that depends on the health of the whole organism. It is a crucial indicator, influencing the profitability of dairy herds. Results of the poor management of reproduction are most often observed after half a year or even later and the correction of these mistakes also takes a good deal of time. Consequently, cattle breeders are looking for new methods that could help to avoid reproduction problems. One of the best methods is assuring the recommended body conditions for cows during all production phases, especially at calving. The objectives of this study were to determine the relationship between body condition score (BCS) and some fertility parameters: days to first observed heat (DFH), days to first service (DFS), conception at first service (FSC), calving interval (CI) and weight of newborn calves (WC). The research was carried out from 2006 to 2007 during indoor and pasturable periods. According to the BCS of dry cows, 3 investigated groups of cows were formed, each containing 22 Lithuanian White and Black cows of 1 to 5 lactations: control group (n = 22), experimental group I (n = 22) and experimental group II (n = 22). The body condition of the experimental cows was scored 6 times a year at critical lactation and dry periods according to the system that uses a scale from 1 to 5 for the body condition cows by Jones and Heinrichs, which evaluates regions of cows’ back, rump, loin and tailhead. The worst fertility indexes were determined mostly in fat cows group. Cows of group II B had the longest CI (429 d.), the lowest conception at first insemination (CFI) (31.81%), the longest period between the first and the last heat (88.86 d.) (p < 0.05), they required more breedings to conceive (2.05) (p ≥ 0.1). The authors think one of the reasons was that the biggest fall of BCS was also noted in the fat cows group (II B) at peak lactation. In group II B we detected a positive correlation between BCS at dry off and WC and also the service period. In order to avoid fertility problems it is important periodically to BCS cows and to warrant the correct BCS, especially at dry off. BCS should be used to identify cows at risk for failure to conceive at first AI and it could be a potential selection criterion for the fertility of cows.
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