PT  - JOURNAL ARTICLE
AU  - Bezdíček, Jiří
AU  - Šubrt, Jan
AU  - Filipčík, Radek
TI  - The relationship between the level of inbreeding and milk production of cows in the first lactation period
DP  - 2014 Dec 28
TA  - Acta Universitatis Agriculturae et Silviculturae Mendelianae Brunensis
PG  - 107--116
VI  - 53
IP  - 2
AID - 10.11118/actaun200553020107
IS  - 12118516
AB  - The objective of the present study was to explore the effect of the level of inbreeding on milk efficiency of cows and on the content of milk components (fat and protein) in the 1<sup>st</sup> standard lactation period (305 days). The level of inbreeding (F<sub>x</sub>) of inbred cows ranged between 1.25 and 12.5%. Efficiency parameters of inbred cows were compared with their contemporaries - half-sisters after the father (n=2567), raised on the same farm whose first lactation ended in same year. Out of the total database (567,036 cows) created in 1980-2002 we incorporated 885 inbred cows. To allow detailed analyses the inbred cows were divided into 3 groups according to the coefficient F<sub>x</sub> (1.5-2.3%, 3.0-5.0% and 8.0-12.5%). The database was evaluated using the analysis of variance with 8 fixed effects including the commercial type, own breeding value and breeding value of mother, average efficiency of mother, reproduction parameters (year and age at calving and interval between the 1<sup>st</sup> and 2<sup>nd</sup> lactation) and total number of lactations. The statistical programme SAS 8.2 - GLM procedure (Copyright c 1999-2001 by SAS Institute Inc., Cary, NC, USA) was used for statistical analyses. Compared to their contemporaries the 323 kg reduction of milk production of inbred cows with the lowest value of F<sub>x</sub> (1.5-2.3%) was insignificant; the decrease in the relative content of fat and protein was insignificant by 0.01 and 0.02%, respectively. Comparisons between contemporaries and inbred cows with F<sub>x</sub> at the level of 3.0-5.0% showed a highly significant 407 kg reduction in milk efficiency. The fat content in milk of inbred cows increased by 0.11% (p