Year: 2012
Type: dissertation
Abstract: Declining dairy cow fertility, largely attributable to increasing milk yields, is of major \nconcern to dairy farmers worldwide. New tools for reproductive management, to \nreplace exogenous hormones, would be of great interest. Chemical communication in \ncattle has been suggested to cause modifications of the oestrous cycle. Here, \nreproductive parameters were monitored in ten dairy heifers during five oestrous \ncycles. They were exposed to distilled water (control) or oestrous urine and vaginal \nmucus (treatment). Four of them were also subjected to intensive blood sampling to \nstudy the treatment effect on the LH pulsatility pattern (LHP) preceding the \npreovulatory LH surge (LHS).We found that the treatment had significant effects on \nwhen the different signs of oestrus occurred and on the intensity of oestrus expression. \nThere was a tendency for treatment to have an effect on LHS characteristics whereas \nLHP was significantly affected by the treatment. To find a quick bioassay to detect \nbioactive bovine body fluids, two heifers and two bulls were exposed to different body \nfluids while their heart rates were registered. Although the exposure caused significant \neffects, they were not of sufficient magnitude to be useful. Further attempts to find a \nbioassay to identify oestrus-specific compounds included using the face fly as a \nbiological detector. Female flies were allowed to choose between either oestrous (OU) \nor luteal urine (LU) and distilled water (control) in a Y-tube olfactometer. Flies were \nsignificantly repelled by OU, but not by LU. Gas chromatography coupled with \nelectroantennographic detection (GC-EAD) revealed no behaviourally active, oestrusspecific \ncompounds. Comparison of chromatograms, however, showed that cetyl \nalcohol was more abundant in OU than in LU. When tested at different doses, the \nlowest dose of cetyl alcohol was found to attract flies, while the second lowest dose \nwas repellent. \n \nWe found effects of exposure to body fluids on cyclicity in heifers, as well as on \nheart rate in cattle, which supports the existence of bovine pheromones. We also found \nthat the face fly could discriminate between OU and LU, probably based on the amount \nof cetyl alcohol in the samples. Neither monitoring of heart rate, nor using the face fly \nas a biological detector, were suitable bioassays for detection of bovine pheromones. \n
Author: Kristina Nordéus
Language: English
Subfield: Animal Science and Zoology
Domain: Life Sciences
SDG: Zero hunger
Open Access status: green
Funder: Sveriges Lantbruksuniversitet
OpenAlex ID: W143560245