ANALÝZA DÉLKY BŘEZOSTI PŘI VÍCEČETNÝCH PORODECH U ČESKÉHO STRAKATÉHO A HOLŠTÝNSKÉHO SKOTU

Abstract

In the work we have evaluated multiple births (calving between the years 1992 and 2003) in Czech Fleckvieh and Holstein cattle. We have compared the length of pregnancy in case of twins and triplets with the length of pregnancy of the same cow during the previous lactation when only one calf was born. Total number of observed multiple births of both strains was 686 cases – including 508 births of twins and 178 births of triplets. Mathematical statistical procedures have been made by standard mathematical methods using a SPSS 15.0 for Windows, Release 15.0.0 (6 Sep 2006) program. The results we have reached showed a significant (P ≤ 0.01) decrease in pregnancy length in multiple births. These results have appeared in both observed strains. Czech Fleckvieh cattle showed the length of pregnancy 281.57 days in case of twins (previous pregnacy with one calf was 287.41 days long) and in case of triplets it was 277.09 days (previous pregnancy was 287.17 days long). Decrase in pregnancy length was therefore by 5.84 days in case of twins and by 10.08 days in case of triplets. A similar tendency was found also in Holstein cattle, where the length of pregnancy in case of twins was 274.98 days (previous pregnancy with one calf was 279.66 days long) and in case of triplets was 271.12 (280.27 with one calf). Also in this case the shortening of the pregnancy with twins (by 4.68 days) and with triplets (by 9.15 days) was significant (P ≤ 0.01). Both observed strains showed the highest number of multiple births in the second to fifth pregnancy. These pregnancies showed the 75.07 % of all the multiple births – twins were 52.77 % and triplets were 22.3 %. On the other hand the lowest ratio of multiple births was in case of the first calving (total 2.33 %).