Evaluation of milk yield and milkability traits of different genotype cows during lactation

Abstract

Dairy herds in Europe and the United States of America were selected for high milk production under intensive farming conditions. Even under optimal management conditions, selection for the increase of milk yield has reduced dairy cattle health and reproductive efficiency worldwide [1]. This raises doubts whether these high-cost genotypes are suitable for organic farming systems [2], [3]. The evaluation of milk production and milk ability traits of different genotype Lithuanian black and white cattle population (n = 528) was carried out by the data of state enterprise Agricultural Information and Rural Business Center and in a herd of an organic farm. The aim of this study was to investigate the milk yield and milk ability traits during lactation of Lithuanian Black and White and Holstein cows with cows of different genotypes. The milk yield, milking speed, the highest milk flow, and milking time were investigated during the study. Evaluated traits were measured with De Laval electronic milk meter, “Apro Windows” software. All records were obtained during 305 days of lactation. Statistical data analysis was conducted using SPSS 25.0 (SPSS, Inc., Chicago, IL, USA) soft ware.The data were presented using descriptive statistics and normal distribution analysis methods, Kolmogorov–Smirnov test. The Pearson correlation (r) was determined to define the linear relationship between investigated traits from Ap ro Windows software. Multiple comparisons were calculated using the Tukey test. We observed that the highest milk yield and the highest milk flow rate were detected in cows with Lithuanian Black and White breed genotype (Lithuanian Black and White, Lithuanian Black and White x Holstein, Lithuanian Black and White x Holstein x Lithuanian Black and White) during all stages of lactation. Milking time of these cows during the first two stages of lactation was longer, compared to cows of other genotypes (P < 0.05). An average positive correlation was estimated between the stage of lactation and milk yield (r = 0.397), high milk flow(r = 0.331), (P < 0.001). We estimated that of all fixed effects (stage of lactation, genotype, interaction of stage of lactation with genotype) the biggest influence on milk yield, highest milk flow, milking speed, milking time was produced by the stage of lactation (P < 0.001); a genotype showed the highest impact only on milking time (P < 0.01).