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Abstract

The aim of this research was to determine rumination time (RT) and the subsequent milk yield, along with trait changes during lactation dependent on the reproductive status of dairy cows. 728 cows were selected for evaluation in regards to 1–150 days of milk production (DIM). According to their period of lactation and reproductive status, the cows were selected for the following groups: Inseminated (1–35 days after insemination, n=182), Open (45–90 days after calving, n=126), Fresh (1–44 days after calving, n=45); Not-pregnant (>35–60 days after inse- mination and not-pregnant, n=55); Pregnant (35–60 days after insemination and pregnant (n=320). The animals were milked with Lely Astronaut® A3 milking robots. The daily milk yield, rumination time, bodyweight, milk composition (fat, protein, lactose, somatic cell count and gynecological status date) were collected from the Lely T4C management program for analysis. We estimated the lowest productivity in the pregnant cows, where the average milk yield was 28.72 kg and the highest productivity in the fresh cow (p<0.001) (Table 1). The longest rumina- tion time was determined for the inseminated cows, statistically significantly higher at 9.92% (p<0.001) than in the non-pregnant cows, whose rumination time was the shortest. The statisti- cally reliably RT positively correlated with productivity (r=0.384, p<0.001) of the cows (from r=0.302 in the second lactation and r=0.471 in the first lactation to r=0.561 in multiparous cows; p<0.001). Rumination time, according to groups of cows by milk yield, had a tendency to increase (2.14 times) from 202.0± 87.38 (in cows with a productivity of less than 10 kg milk) to 431.6±33.91 (in cows with a milk yield higher than 50 kg) by the linear regression equation: y = 38.02x + 232, R² = 0.721 (p<0.001). The relation between the gynecological status and milk fat-protein ratio of the cows was statistically significant (χ2=2.974, df= 8, p <0.0001). The longest rumination time was determined for the inseminated cows (1 – 35 days after insemination), and the shortest for the not-pregnant cows (>35 – 60 days after insemination and not-pregnant). We can conclude that rumination time, subsequent yield, and milk trait change depends on the period of lactation and reproductive status of a dairy cow.
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Abstract

The objective of this study was to determine the association between subclinical acidosis (SARA) and subclinical ketosis (SCK) with biomarkers from an automatic milking system (AMS) measuring in relation to rumination time (RT), milk yield (MY), bodyweight (BW), milk temperature, the milk fat-to-protein ratio, and the electrical conductivity of milk at the udder quarters-level which can be read in fresh dairy cows. During the course of the study, all of the fresh dairy cows (n=711) were examined according to a general clinical investigation plan. The cows were selected for 1-30 days of milk (DIM) and were milked using Lely Astronaut® A3 milking robots with free traffic. Rumination time shows a statistically significant positive correlation with milk yield (milk temperature) and is negatively correlated with the fat and protein ratio. Healthy cows demonstrated the highest level of rumination time and the lowest milk temperature. The average BW for these cows was 1.64% lower than for the SARA group and the BW kg was 2.10% higher than SCK cows. MY was 14.01% lower in comparison with SARA and 6.42% higher in comparison with SCK. According to these results, some biomarkers from the AMS have an association with SARA and SCK. However, further research with a higher number of cows is needed to confirm this conclusion.
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