Red blood count in dairy cows in periparturient period and in early lactation

The paper presents results of red blood count studies in dairy cows in the periparturient period and early lactation, when cows are in a state of extreme stress due to intensive endocrine and metabolic changes. Investigations were carried out on 20 cows of the Holstein-Friesian breed which were in their second to fifth lactation. Blood samples were drawn 15 days before calving, on the first day after partus (2-5h) and on days 15, 30, and 45 of lactation. The biggest average number of erythrocytes (7.00±0.48×1012/L blood), haemoglobin concentration (115.95±8.49 g/L blood) and haematocrit value (33.11±2.97%) were established on the first day after partus. This erythrocyte count was significantly higher against the value determined during the last two week of gravidity (p<0.01) and during the early stage of lactation (p<0.001). Haemoglobin and haematocrit concentration in the prepartal period and immediately after calving were statistically significantly higher (p<0.001) than on days 15, 30, and 45 of lactation. Haematological indexes: the average erythrocyte volume (MCV), average haemoglobin value in erythrocytes (MCH) and average haemoglobin concentration in erythrocytes (MCHC) were within the limits of the referent values. On the first day of partus, the erythrocyte sedimentation rate was significantly higher than in early lactation (p<0.01 on days 15 and 30, and p<0.001 on day 45). The results of the analyses indicated a decrease in all examined haematological parameters during the period of lactation, but the determined differences were not significant.