| Summary: | One of the basic conditions of the economical success in milk production is the high and periodic reproduction of the cows. That means the parturition of a healthy calf from every cow per a year. The development and level of reproduction functions is very susceptible to the quantity and mainly quality of nutrition. The insuffi ciency in nutrition is strongly related to the fertility. The aim of this study was to evaluate the reproduction indicators depending upon the level of the milk yield and body condition of the Holstein cows at the family-owned farm. The basic dataset was obtained during the years 2004 – 2007. The milk yield and fertility data were gained from the herd records. The extreme values were removed from the basic set. Body condition score was evaluated every month. The groups according to the milk yield level and body condition score were evaluated. The basic statistical characteristics were determined in the groups of cows and in the evaluated sets. The effect of particular factors was proved by the one-factorial analysis of variance ANOVA. Increasing milk yield in the groups with milk yield up to 7000 kg of milk, 7000-8000 kg and more than 8000 kg had negative impact on the reproduction indicators. The differences in the length of calving to fififi rst service interval among particular groups were statistically signifififi cant (P ≥ 0.01). The average length of this interval was 96, 111 and 122 days for 1st, 2nd and 3rd group, respectively. In addition, the average length of calving to conception (service period) interval was 154, 165 and 171 days. There were found no signifi cant differences in numbers of services per conception. The average BCS at calving was 3.59 points. After calving BCS level decreased till the 6th month of lactation, where its level 2.43 points, then the BCS level increased. Average BCS level at conception was under 2.5 points. The variation of BCS during the lactation was 2 points.
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