Učinkovitost sustava automatske detekcije tjeranja u junica smeđeg goveda kada se rabi seksirano sjeme na velikoj farmi mliječnih goveda

The identification of cows and heifers in heat and their timely artificial insemination (AI) is an important issue for large dairy units. The objective of the research was to study the efficiency of insemination of oestrous Brown Swiss heifers using am automated heat detection system (AHD) compared to heat detection by visual observation (VO). The AHD system application increased the fertility of heifers by 8.9% when using conventional semen (unsexed) and by 14.4% using sexed semen. The number of services per conception when using sexed semen decreased from 3.7±1.08 with VO to 2.4±0.68 with AHD. Two-factor analysis of variance showed that an 89% effect of managerial decisions such as the detection of heifers in heat by means of AHD and the use of sexed semen on the efficiency of insemination. This study showed that professional breeders and veterinarians should pay particular attention to AI management when making these managerial decisions in large dairy units.Identifikacija krava i junica koje se tjeraju i njihovo pravovremeno umjetno osjemenjivanje (AI) predstavljaju problem za velike mliječne farme. Cilj je ovog istraživanja bio ispitati učinak osjemenjivanja junica smeđeg goveda u estrusu uporabom sustava automatske detekcije tjeranja (AHD) u usporedbi s detekcijom tjeranja vizualnim promatranjem (VO). Primjena AHD sustava povećala je plodnost junica za 8,9 % kod uporabe konvencionalnog (neseksiranog) te za 14,4 % kod uporabe seksiranog sjemena. Broj umjetnog osjemenjivanja po začeću prilikom uporabe seksiranog sjemena spustio se s 3,7±1,08 s VO na 2,4±0,68 uporabom AHD sustava. Analiza dvaju čimbenika odstupanja pokazala je da je učinak upravljačkih odluka poput detekcije junica koje se tjeraju pomoću AHD-a i uporaba seksiranog sjemena na učinkovitost osjemenjivanja bio 89 %. Ova studija pokazala je da bi profesionalni uzgajivači i veterinari posebnu pozornost trebali posvetiti upravljanju umjetnim osjemenjivanjem u provedbi tih upravljačkih odluka na velikim mliječnim farmama

Changes in the Spectrum of Free Fatty Acids in Blood Serum of Dairy Cows during a Prolonged Summer Heat Wave

This experiment was conducted to study the effect of a prolonged hot period on the fatty acid (FA) composition in blood serum of dairy cows. Eighteen multiparous Holstein cows were randomly assigned to the hyperthermia group (HYP, n = 8) in August (summer season) and the control group (CON, n = 10) in October (autumn season). Blood from animals of the HYP group was collected in one heat wave, which was preceded by a long period of heat stress (HS, temperature-humidity index (THI ≥ 72)). Blood from cows of the CON group was collected under thermal comfort conditions (THI < 68). The spectrum of free fatty acids (FFA) in the blood serum was analyzed by gas chromatography. The concentration of FFA increased, including saturated FAs and monounsaturated FAs, in the blood serum of cows under conditions of prolonged HS. This was associated with the mobilization of FA into the bloodstream from adipose tissue, as a consequence of negative energy balance. An increase in the ratio of n-6/n-3 polyunsaturated FAs may indicate biomembrane dysfunction and adversely affect dairy cows. This study showed that prolonged periods of heat can affect the FA composition of blood. How much this leads to changes in the FA composition of milk and the quality of food products remains to be seen in further research