| 1. |
- Nordéus, Kristina, et al.
(författare)
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A small expose on bovine pheromones: with special reference to modifications of the reproductive cycle
- 2016
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Konferensbidrag (refereegranskat)abstract
- The last decades have seen vast increases in dairy cow milk yield. At the same time, fertility rates are deteriorating, partly due to depressed estrous behavior, which makes it difficult for farmers to determine the optimal time for artificial insemination. Synthetic pheromones could possibly provide novel reproductive management tools. Much work has been done in this interesting field, but results vary greatly and bovine pheromones remain elusive. The aim herein is to provide an overview about bovine pheromones with emphasis on modifications of the estrous cycle.
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| 2. |
- Nordéus, Kristina, et al.
(författare)
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Changes in LH Pulsatility Profiles in Dairy Heifers During Exposure to Oestrous Urine and Vaginal Mucus
- 2012
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Ingår i: Reproduction in Domestic Animals. - : Wiley. - 0936-6768 .- 1439-0531. ; 47, s. 952-958
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Tidskriftsartikel (refereegranskat)abstract
- Difficulty in observing oestrus is a problem for many dairy farmers performing AI. Finding ways to synchronize oestrous cycles or strengthen display of oestrus without hormonal treatments would be of great interest because many consumers object to the use of exogenous hormones on healthy animals. Modification of reproductive cycles through chemical communication has been reported in several species including cattle. LH is an important regulator of the follicular phase and could possibly be subject to pheromonal influence. This study focuses on the effect of volatile compounds from oestrous substances on LH pulsatility preceding the preovulatory LH surge in cattle. Four heifers of the Swedish Red breed were kept individually in isolation. Exposure to water during the control cycle (CC), and bovine oestrous urine and vaginal mucus during the treated cycle (TC), started simultaneously with induction of oestrus. Blood sampling at 15-min intervals started 37 h after administration of PGF(2 alpha) and continued for 8 h. Monitoring of reproductive hormones, visual oestrus detection and ultrasonographic examination of the ovaries continued until ovulation had occurred. The mean concentration of LH at pulse nadir was significantly higher during TC (2.04 +/- 0.18 ng/ml) than during CC (1.79 +/- 0.16 ng/ml), and peak amplitude was significantly higher during CC (Delta 1.03 +/- 0.09) than during TC (Delta 0.87 +/- 0.09). No other parameters differed significantly between the two cycles. We conclude that the difference in LH pulsatility pattern may be an effect of exposing heifers to oestrous vaginal mucus and/or urine and that the mechanism behind this needs further investigation.
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| 3. |
- Nordéus, Kristina, et al.
(författare)
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Cycle-Characteristic Odour of Cow Urine Can Be Detected by the Female Face Fly (Musca autumnalis)
- 2014
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Ingår i: Reproduction in Domestic Animals. - : Wiley. - 0936-6768 .- 1439-0531. ; 49, s. 903-908
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Tidskriftsartikel (refereegranskat)abstract
- Due to declining dairy cow fertility rates, there is great interest in developing tools for oestrus detection. Compounds in the volatile profile of oestrous cows are suggested as oestrus-specific, but consistent results have not been presented. Certain haematophagous arthropods can discriminate stages of the mammalian reproductive cycle based on host volatiles. This study investigated whether the face fly, Musca autumnalis de Geer (Diptera: Muscidae), can discriminate between urine from cows in oestrus and urine collected during the luteal phase. Individual flies were tested in a two-choice behavioural assay with choice between odour of oestrous or luteal urine and water (control). Flies chose the control arm significantly more when exposed to oestrous urine than when exposed to luteal urine. Analysis of volatiles showed that 1-hexadecanol (cetyl alcohol) was released in greater amounts from oestrous urine than from urine collected during the luteal phase. In a dose response assay, flies were significantly attracted by 0.01 ng of 1-hexadecanol but significantly repelled by 0.1 ng, a pattern consistent with fly responses to urine. In conclusion, M. autumnalis can discriminate between oestrous and luteal urine, and this may be mediated by differences in 1-hexadecanol concentration.
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| 4. |
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| 5. |
- Nordéus, Kristina
(författare)
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Pheromones for modulating reproduction in cattle : biological potential of oestrus-related substances inintra- and inter-species chemical communication
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Declining dairy cow fertility, largely attributable to increasing milk yields, is of major concern to dairy farmers worldwide. New tools for reproductive management, to replace exogenous hormones, would be of great interest. Chemical communication in cattle has been suggested to cause modifications of the oestrous cycle. Here, reproductive parameters were monitored in ten dairy heifers during five oestrous cycles. They were exposed to distilled water (control) or oestrous urine and vaginal mucus (treatment). Four of them were also subjected to intensive blood sampling to study the treatment effect on the LH pulsatility pattern (LHP) preceding the preovulatory LH surge (LHS).We found that the treatment had significant effects on when the different signs of oestrus occurred and on the intensity of oestrus expression. There was a tendency for treatment to have an effect on LHS characteristics whereas LHP was significantly affected by the treatment. To find a quick bioassay to detect bioactive bovine body fluids, two heifers and two bulls were exposed to different body fluids while their heart rates were registered. Although the exposure caused significant effects, they were not of sufficient magnitude to be useful. Further attempts to find a bioassay to identify oestrus-specific compounds included using the face fly as a biological detector. Female flies were allowed to choose between either oestrous (OU) or luteal urine (LU) and distilled water (control) in a Y-tube olfactometer. Flies were significantly repelled by OU, but not by LU. Gas chromatography coupled with electroantennographic detection (GC-EAD) revealed no behaviourally active, oestrusspecific compounds. Comparison of chromatograms, however, showed that cetyl alcohol was more abundant in OU than in LU. When tested at different doses, the lowest dose of cetyl alcohol was found to attract flies, while the second lowest dose was repellent. We found effects of exposure to body fluids on cyclicity in heifers, as well as on heart rate in cattle, which supports the existence of bovine pheromones. We also found that the face fly could discriminate between OU and LU, probably based on the amount of cetyl alcohol in the samples. Neither monitoring of heart rate, nor using the face fly as a biological detector, were suitable bioassays for detection of bovine pheromones.
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| 6. |
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| 7. |
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| 8. |
- Nordéus, Kristina, et al.
(författare)
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The influence of oestrous substances on cyclicity and oestrous behaviour in dairy heifers
- 2012
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Ingår i: Acta Veterinaria Scandinavica. - : Springer Science and Business Media LLC. - 0044-605X .- 1751-0147. ; 54, s. 1-10
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Tidskriftsartikel (refereegranskat)abstract
- Conclusions: No evidence of altered oestrous cycle length or duration of oestrus after exposure of females to oestrous substances from other females was found. Expression of oestrus, and maybe also LH secretion, however, seemed influenced by the exposure, with the effect of treatment being suppressive rather than enhancing.
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