Renáta Toušová

Relationships between milk fatty acids composition in early lactation and subsequent reproductive performance in Czech Fleckvieh cows.

Increase of milk yield after calving causes changes in milk fatty acids (FA) composition and simultaneously corresponds with reproduction performance decrease. The objective of this study was to evaluate the relationships between milk FA group composition (SFA, saturated fatty acids; MUFA, monounsaturated fatty acids; and PUFA, polyunsaturated fatty acids) during the first 5 lactation weeks and subsequent reproductive results (INT, calving to first service interval; NUM, number of services per conception, and DO, days open) in Czech Fleckvieh cows. A total of 1231 individual milk samples from 382 cows were collected and subsequently analyzed. Simultaneously, body condition score (BCS) was weekly evaluated as well. Software SAS 9.1 was used for statistical analysis. Daily milk yields increased whereas BCS, milk fat and protein contents decreased during period observed. The reduction of basic milk components (% of fat, % of protein) was associated with increased SFA and decreased MUFA, respectively PUFA contents. Significant (P<0.01-0.05 days) increase in NUM (+0.15 to +0.29 AI dose) and DO (+8.16 to 15.44 days) were detected in cows with the lowest SFA content. On the contrary, cows with the highest content of MUFA presented significantly (P<0.01-0.05) higher values of NUM (+0.13 to +0.30) and DO (+7.26 to +15.35 days). Milk FA groups composition in early lactation potentially used as NEB indicators, especially SFA and MUFA proportion, affected subsequent reproductive results of Czech Fleckvieh cows. Therefore, its post-partum values could serve as predictors of potential fertility of dairy cows.

The comparison of milk production and quality in cows from conventional and automatic milking systems

The objective of this study was to evaluate the effects of two different types of milking systems (conventional parlour vs. automatic milking system) and the season of the year on the composition and hygienic quality of milk from Czech Fleckvieh cows. A total of 500 cows were involved; 200 and 300 in conventional and automatic milking systems, respectively. Bulk milk samples were collected for 12 months from July 2010 to June 2011. The following milk components and quality indicators were determined: % of fat, % of protein, % of lactose, % of fat-free dry matter (FFDM), % of casein, urea content, somatic cell count (SSC), total germ count (TGC) and milk freezing point (FP). The data were processed and evaluated with MS Excel and the statistical software SAS 9.1. Significantly higher (P<0.05 – 0.01) contents of fat, protein, FFDM and casein and increased TGC were observed in the automatic milking system, whereas SCC and FP were significantly lower (P<0.01). The highest contents of fat, protein and casein, and the lowest lactose content were found in the winter season. The highest contents of FFDM, urea and SCC were observed in autumn, whereas TGC was highest in summer (P<0.05 – 0.01). Only FP was not influenced by the season.