Abstract
The transition period is the most stressful for dairy cows in terms of metabolic rate and characterized by dynamic changes in the hormonal profile, loss of appetite, negative energy balance, nutrient and vitamin deficiencies, compromised immunity and oxidative stress. The aim of the research was to balance the increase in cows’ productivity and the consumption of nutrients from the feed during the transition period through the use of energy feed additives (EFS), high protein feed concentrate (PFC) in combination with biologically active (BA) substances. Thirty-six dairy cows of black-motley breed were divided into 3 groups: (1) The main diet (G0, n = 12), not supplemented with additives, (2) additive 1 (G1; supplemented with 0.5 kg EFS / cow per day, n = 12), (3) additive 2 (G2; supplemented with 0.5 kg EFS; 0.5 kg PFC and 0.06 kg BA / cow per day, n = 12). The experimental part of the feeding lasted for 20 days before calving and the first 100 days after calving (DPP). Blood samples were collected during the first and the third months after calving. The biochemical analyzer was used to measure blood serum components. The milk yield was recorded monthly throughout lactation. BCS losses from 7 days prior to calving to 28 DPP were -0.29 for Gr2, -0.42 for Gr1 and -0.60 for Gr0. Feeding with additive 2 (Gr2) increased milk yield (p≤0.05) in the first 100 DPPs and (p≤0.001) 305 DPPs compared to G0. The number of samples with SCC ≥ 500 000 / ml. per 100 DPP was 51% in the Gr0 group, 27% in Gr1, 25% in Gr2. Also, microbiological control showed an excess of Bacterial cells in the milk of cows from group G0, which correlates with SCC indicators. Cows from Gr2had a lower content of ketone bodies (P≥0.001) and higher (P≥0.001) antioxidant activity of blood serum compared to Gr0. Cows from Gr2 had an increase in ALT activity by1.4 times (P <0.05) from the first to the third months after calving.
Keywords: dairy cattle, metabolic homeostasis, feed, transition period