Evaluation of productivity and somatic cell count in milk of different genotype of dairy cows.

Author: Loreta Albušienė Research supervisor: dr. Renata Japertienė Name of the Paper: Evaluation of productivity and somatic cell count in milk of different genotype of dairy cows. Structure of the Paper: literature review, research methodology, results and discussion, conclusions. List of Literature consists of 75 sources. Volume of the Paper - 48 pages. Presented: 5 tables, 14 figures. Methods: The scientific-investigative research was performed in the Animal breeding and nutrition department of the Veterinary academy of the Lithuanian Health Science University and in the 8 dairy farms in 2016 – 2019. The productivity and SLS of 1122 dairy cows of different genotype were evaluated. For analysis, cows were grouped by degree of holsteinization, genotype and season. Statistical analysis of the data was performed by the method of variance analysis (ANOVA). The aim of the thesis: to evaluate and compare the indicators of productive features of dairy cows having different genotypes. The goals of the thesis: To evaluate and compare the daily milk volume (kg), milk composition and SCC in milk (thousand / ml) of different genotypes. To evaluate and compare productivity and SCC of milk cows of different genotype during different seasons of the year. The results of the research: It was estimated that cows with different holstein blood levels had the highest milk yield and the lowest SCC in cows with up to 25% holstein blood level and lowest milk yield in cows with a holstein blood level of 50-75%. As the holstein blood level increases, SCC in milk increases. (p>0,05) The highest average milk fat and protein content was in cows with a holstein breed blood level of 75 to 100 %. The lowest milk fat content was in cows with holstein breed blood up to 25% and protein content in cows with holstein breed blood level between 50 and 75%. (p>0,05) Evaluation of cows with blood of Lithuanian black and white breeds showed that the highest milk yield (p0,05) were in cows with blood of Lithuanian black and white breed. Cows with blood of the Dutch black and white breed had the lowest SCC and high milk yield. The lowest milk yield was obtained from cows with blood of the British friesian breed. (p>0,05) The highest milk fat and protein content was in cows with German black and white blood. The lowest milk composition parameters were found in milk of British friesian blood cows. (p>0,05) Comparison of cows with blood of Lithuanian red and red and white population revealed that ayrshire and Swedish black and white cows with high milk yield and lowest SCC in milk. The highest milk content was found in cows with the blood of the red and white holstein breed, but the highest SCC in their milk. (p>0,05) No significant seasonal influence on milk composition was observed. The highest milk fat content was found in Swedish black and white cows and protein-rich cattle with red and white Holstein blood. (p>0,05) Evaluating and comparing productivity and SCC in milk of different genotypes during different seasons of the year, it was found that cows of all holstein breeds had the highest milk yield in spring, the lowest SCC in milk of all holstein breed blood cows was excreted in summer, except for pure-bred holstein cows with the lowest SCC in autumn. (p>0,05) There was no significant seasonal influence on the milk composition of cows with different degrees of holsteinization. (p>0,05) Cows with blood of Lithuanian black and white breeds had the highest milk yield in spring (p0,05) Cows that had blood from breeds belonging to the of Lithuanian red and red and white population, the highest milk yields were in spring, the lowest SCC was found in summer and autumn. No significant seasonal influence on milk composition was observed. (p>0,05