Milking Temperament and Its Association with Test-Day Milk Yield in Bulgarian Murrah Buffaloes.

The goal of this research was to evaluate milking temperament and its relationship with test-day milk (TDMY0) yield in Bulgarian Murrah buffaloes. This study involved 90 buffalo cows reared under a tie-stall production system which were milked twice a day with a milking pipeline. The behavioral responses of the buffaloes were reported during preparation for milking and during actual milking. The average temperament score during preparation for milking was 1.83, and 1.93 during milking itself. The most common reaction was leg lifting (18.9%), followed by cows moving on the stall bed (10%), definite kicking (9.9%), and 13.3% managing to remove the milking cluster during milking. The frequency of buffaloes showing adverse reactions (scores 4 and 5) increased considerably during milking compared to preparation for milking. Repeated scoring of temperament during the same lactation did not show a significant difference in the frequency of temperament assessments both in preparation for milking and during milking. The minimal difference may be due to the accuracy of the assessment or a momentary change in the condition of the animals during the two scorings. Cows with the most unwanted milking behavior (scores 5 and 4) had the highest LS means for TDMY, 8.18 kg and 7.65 kg, respectively. The reasons for these buffaloes remaining until later lactations was their high milk yield and the injection of oxytocin before milking, which helps them to be fully milked.

Influence of Heat Stress and Physiological Indicators Related to It on Health Lipid Indices in Milk of Holstein-Friesian Cows.

The aim of the survey was to study the effect of heat stress (HS) on health lipid indices in milk of Holstein-Friesian cows. The study was conducted in a cattle farm with Holstein-Friesian cows in the region of Karnobat (Southeastern Bulgaria) in 2018. Cows were housed in semi-open free stall dairy barn, fed year-round ad libitum with a total mixed ration. The study included 22 cows on different parities studied in two periods - at thermo-neutral environment conditions and at heat stress, respectively, May and August. Extraction of milk fat was performed by the Rose-Gottlieb method. Conditions of HS lead to changes in the values of health lipid indices associated with a decrease in the values of Atherogenic index (AI), Thrombogenic index (TI), Lipid Preventive Score (LPS) and Desaturase (18) index (DI 18) and an increase in Health promoting Index (HPI), polyunsaturated fatty acids/saturated fatty acids (PUFA/SFA), unsaturated fatty acids/saturated fatty acids (UFA/SFA), mono unsaturated fatty acids (MUFA), Desaturase (16) index (DI 16) and hypocholesterolaemic/hypercholesterolaemic ratio (h/H). Increasing the Temperature-humidity index (THI) above 72, results in a decrease in the AI values and an increase in those of the PUFA/SFA. The values of health lipid indices showed a moderate positive correlation with those of THI (PUFA/SFA - 0.36) with rectal temperature (h/H, MUFA/SFA, UFA/SFA) rp from 0.36 to 0.37, and with respiratory rate (h/H, PUFA/SFA), rp of 0.33 and 0.31, respectively. Under the influence of heat stress, changes in the metabolic processes occur in the body of dairy cows leading to changes in the fatty acid content of milk related to the improvement of health lipid indices in terms of human health due to an increase in UFA and reduction in SFA.

Immobilization of acetylcholinesterase on nanostructure polyacrylonitrile membranes.

PAN membranes with integrated gold nanoparticles (GNPs) into membrane pores were prepared for immobilization of acetylcholinesterase. Two types of polymer membranes were used-non-modified and chemically modified with NaOH. PAN+GNP membranes were investigated with respect to their water-permeation and electron-conducting properties and the results were compared to those, obtained for the initial membranes without GNPs. The SEM analyses showed morphology change in the different membranes. The chemical modification was an essential step in the preparation procedure in order to obtain more homogeneous distribution of the GNPs. AChE was covalently immobilized onto nanostructured membranes using 1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide hydrochloride. The relationship between immobilization factors and enzyme activity were examined by the series of contour plots. The selections of the immobilization variable range were extremely precise in the 3-level-3-factor fractional design. The results indicated that the optimal conditions for AChE immobilization were: 0.025% enzyme solution; immobilization temperature, 4 degrees C and immobilization time, 15 h. The biochemical characteristics and kinetic parameters of immobilized enzyme were determined.

The influence of the support nature on the kinetics parameters, inhibition constants and reactivation of immobilized acetylcholinesterase.

Acetylcholinesterase (AChE) was immobilized on two different composite membranes constituted by a chemically modified poly-acrylonitrile (PAN) membrane plus a layer of tethered chitosan of different molecular weight, 10 kDa or 400 kDa. AChE was also directly immobilized on a chemically modified PAN membrane with NaOH and ethylenediamine (EDA) without chitosan. To know how the different supports affected the enzyme activity and the kinetic parameters, the AChE activity was studied in the soluble form and in the insoluble form with all the three types of modified PAN membranes. The best performance was obtained by the modified PAN membrane having the chitosan with the lower molecular weight. The results concerning the AChE inhibition by methyl-paraoxon and the subsequent reactivation by pyridine-2-aldoxime methochloride (2-PAM) are presented and discussed. The composite membrane having chitosan with the lower molecular weight appeared to be potentially useful for applications in the field of biosensors.