The aim of our study was to determine up to what extent the number of services per calving (NSPC) affects dairy cow productive and reproductive performance. The study contains data from the Latvian Agricultural Data center about 26888 Latvian Brown (LB) and Holstein Black and White (HBW) breed cows that were born from year 2005 -2010, closed at least 5 full lactations and were culled from herds. In data set we have included data about cow milk productivity (calculated in ECM), longevity traits and reproduction traits. The reproduction traits included the number of services per conception (NSPC), calving interval (CI) and calving to conception interval (CCI) in the first five lactations. The average lifespan of LB and HBW dairy cows was 3149.5 days and in this period 39570.6 kg ECM were obtained. LB breed cows were characterized by 23.5 days longer lifespan and by 6035.4 kg ECM lower lifetime milk productivity than HBW breed cows, but they showed higher reproduction trait scores than LB breed group. HBW cows had a significantly (p < 0.05) higher NSPC, CCI, number of milking days (MD) and CI than LB breed cows in all five analyzed lactations. The NSPC in the first lactation increased the calving age at the fifth lactationcows with NSPC in the first lactation > 4, fifth time calved 170.7 days in LB breed group and 190.8 days in HBW breed group later than cows with one NSPC in the first lactation.
Latvian brown (LB) cow breed is economically most important livestock breed in Latvia. In last 5 years in Latvian farms rapidly increases Holstain black and white cow population, however LB breed cows is more resistant against environment and climate changes than relatively new Holstain breed cows. More resistant is genetic resource LB cows. In study was observed data from Latvian Agriculture data center about Latvian brown (LB) cows with different breed blood admixture. Cows, included in data base was born in time period from 2003-2007 year and closed at least 1 full lactation. The aim of the study was to determine how different amount of Latvian brown cow bloodiness affects cow productivity and longevity. Latvian brown cow milk yield significantly lower (p<0.05) was in first lactation (4826.1 kg), but it increased until fifth lactation (5891.8 kg). Opposite situation was occurred with milk dry matter content, milk fat content significantly higher was in first lactation, but until 5th lactation it decreased by 0.84%, similar situation was occurred with milk protein content. Significantly highest milk yield grouped by dominant breed bloodines was observed in group with Brown Swiss bloodiness (4887.3 ± 26.3 kg; p<0.05), but highest protein content in genetic resources group (4.31 ± 0.02 %). Average lifespan in LB cow population was 2463.0 days (in average 6.7 years or about 5 lactations.
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