The aim of this study was to evaluate the possibility to predict outcomes of artificial insemi- nation (AI) in dairy cows based on in-line milk progesterone (P4) concentration. The research was carried out on the herd of loose housing 245 dairy cows of 2-4 lactations, with average milk yielding 11.000 kg per cow. Milk sampling, measuring, and recording of milk P4 concentration was carried out using the Herd Navigator (HN). The grouping was performed according to the following three indices: the first by reproductive condition – pregnant or not pregnant after AI, the second by P4 concentration from day 20 before AI to day 20 after AI, and the third by P4 concentration at AI time. There was a significant difference in P4 concentration in the group of pregnant cows from day 15 to day 9 before AI, and it was by 18.3% higher com- pared to that in the group of non-pregnant cows in the said period (p<0.01). The milk P4 concen- trations began to differ mostly from day 10 after AI. At that time, the average P4 concentration in the group of pregnant dairy cows was by 36.8% higher compared to that in the group of non-pregnant cows (p<0.01). A statistically significant difference between the ratio of the cows with high, medium, and low P4 concentration on days 20-16 before AI (p<0.01) was determined. The highest number of cows with up to 2-3 ng/ml P4 concentration became pregnant at the AI time.
In-line milk P4 records captured on day 10-15 before AI can be used to predict the proper for reproduction period. By P4 concentrations on day10 after AI, the ratio of pregnant cows in herd can be assessed.

The aim of this study was to compare the effect of controlled-release monensin on the automatic registered body condition score (BCS), and biomarkers registered using a fully automated inline analyzer, such as milk β-hydroxybutyrate (BHB), milk yield (MY) and milk lactate dehydrogenase (LDH).
Two experimental groups were formed: (1) monensin group (GK) supplemented with monensin (a monensin controlled release capsule (MCRC) of 32.4 g, n = 42) and (2) control group (GO) (capsule containing no monensin, n = 42). Treatment began 21 days before calving, and the experiment was finished one month after calving. In order to gather data about MY, BHB, and LDH, Herd Navigator a real-time analyzer (Lattec I/S, Hillerød, Denmark) was used together with a DeLaval milking robot (DeLaval Inc., Tumba, Sweden). BCS was measured using 3D BCS cameras (DeLaval, DeLaval International AB). All data were registered at one, 15 and 30 days after calving. The statistical analysis was performed using SPSS 26.0 (SPSS Inc., Chicago, USA) package. It was concluded that in the group of cows with monensin supplement (a monensin controlled release capsule of 32.4 g,), the body condition score was statistically significantly higher at the 15th (+0.24, p=0.003) and 30th (+0.52, p<0.001) days after calving, the productivity of cows in this group increased by 10.25% from the 1st to the 15th day and by 22.49% from the beginning of the experiment to the 30th day (p<0.001), lactate dehydrogenase activities at the 15th and 30th days after calving in this group were lower (p<0.001), and also in this group, the number of cows with a value of β-hydroxybutyrate of 0.06 mmol/L decreased from the beginning of the experiment to 30 days after calving by 4.70% (from 19.00% to 14.30%) compared with the control group.

The aim of the present study was to investigate inline lactate dehydrogenase (LDH) dynamic changes based on different cow factors – different number and stages of lactation, milk yield, and the status of reproduction in clinically healthy dairy cows.

In the Herd Navigator system, LDH activity levels (μmol/min per litre) were measured using dry-stick technology. A total of 378 cows were selected. According to their reproductive status, the cows were classified as belonging to the following groups: Fresh (1 – 44 days after calving); Open (45 – 65 days after calving); Inseminated (1 – 35 days after insemination); Pregnant (35 – 60 days after insemination and pregnant). According to their productivity, the cows were classified into the following groups: <15 kg/day, 15 – 25 kg/day, 25 – 35 kg/day and >35 kg/day. The cows were milked with a DeLaval milking robot (DeLaval Inc. Tumba Sweden) in combination with a Herd Navigator analyser (Lattec I/S. Hillerød Denmark).

In conclusion inline dynamic changes in the milk LDH concentration may increase together with the rise in the lactation period frequency. The highest LDH level determinated in the group of the fresh cows ranged from 5 to 10 DIM, while the highest LDH concentration level was found in the fresh cow milk. Thus, there was a positive relationship between the milk concentration of LDH and the milk yield.

The aim of this study was to determine how puerperal metritis influences the resumption of estrous cycle in dairy cows. The ovaries of 72 multiparous Holstein cows (38 healthy and 34 metritic – after treatment) were ultrasonographically scanned until the first ovulation post- partum and 7 days after to confirm the ovulation. All 72 cows were divided in to 4 groups: HSO (healthy with single ovulation) (n=29), MSO (metritic with single ovulation) (n=21), HDO (healthy with double ovulation) (n=9), and MDO (metritic with double ovulation) (n=13). The proportion of cows that had DO in the first ovulation postpartum was similar between M and H groups, 38.2% and 23.6%, respectively (p>0.05). There was a difference between HDO and MDO groups comparing the first dominant follicle ovulation postpartum (11.4±2.7 and 20±1 days, respectively p<0.05) and the diameter of the ovulatory follicles (15.3±1.9 mm and 17.3±1.7 mm, respectively p<0.05). The percentage of cows that had double follicle domi- nance in the first follicular wave after first ovulation was higher in the M groups (33.3% (MSO) vs. 6.9% (HSO) (p<0.05) and (69.2% (MDO) vs. 22.2% (HDO) (p<0.05)). The MSO group dominant follicle diameter was bigger for cows which had one dominant follicle (p<0.05). It might be concluded that dairy cows after puerperal metritis need more time until the first ovu- lation. Also, metritic cows have a higher risk for double dominance in the first follicular wave, after the first ovulation.