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1.
Luteal activity and effect of dietary energy restriction on follicular development in lactating cows
Antonella Comin, Tanja Peric, M. Montillo, Maria Cristina Veronesi, Vittorio Marchi, Alberto Cappa, Alberto Prandi, 2017, izvirni znanstveni članek

Opis: The aim of this research has been to evaluate the presence of anomalies in the ovarian cycle activity during postpartum and to verify whether 72-hr dietary fasting during the dominance phase, the phase before ovulation, might modify the ovarian follicle population. The presence of anomalies in ovarian cycle activity has been evaluated in 30 Italian Friesian cows starting from 20 days postpartum until 211 days of lactation. Long oestrus and brief dioestrus or scarce luteal activity have been the main anomalies found through measuring progesterone concentrations in the whey. Until 100 days of lactation, the BCS values of the problematic animals have been significantly lower than those in animals with normal ovarian activity. After 100 days of lactation, the ovarian anomalies continued to appear despite the fact that all the animals have reached comparable BCS values. Starting from the results of this trial, the effect of 72-hr dietary fasting on dominant follicles has been studied in six cows. Ultrasonography revealed that the diameter of the follicles at 71 days postpartum has been significantly lower than at 181 days. A 72-hr dietary restriction at 101 and 211 days postpartum did not affect the size of the dominant follicle. However, at 101 days postpartum, half of the animals presented follicular cysts. The effect of fasting differed if the animal has been in early postpartum or 211 days of lactation. Further researches are necessary to understand how different metabolic conditions can modify the follicular population but on the other hand the study shows the utility for farmers and field veterinarians of monitoring the resumption of the ovarian cycle postpartum through the whey progesterone concentrations.
Najdeno v: ključnih besedah
Povzetek najdenega: ... dairy cow, cyclic activity, follicles, fasting...
Ključne besede: dairy cow, cyclic activity, follicles, fasting
Objavljeno: 06.04.2017; Ogledov: 1270; Prenosov: 0
.pdf Polno besedilo (651,67 KB)

2.
Cortisol and DHEA concentrations in the hair of dairy cows managed indoor or on pasture
Tanja Peric, Mirco Corazzin, Alberto Romanzin, Stefano Bovolenta, Alberto Prandi, M. Montillo, Antonella Comin, 2017, izvirni znanstveni članek

Opis: This study was conducted in order to assess the changes of cortisol and dehydroepiandrosterone (DHEA) concentrations in hair of Italian Simmental dairy cows managed indoor in tie-stall barns or grazing on high mountain pasture. In experiment I, animals were kept in tie-stalls throughout the year (n = 27). In experiment II, animals remained on mountain pastures during summer (from 20th June to 20th September) and then kept indoors in tie-stalls for the rest of the year (n = 18). At the end of July, following vertical transhumance, dairy cows were moved to a pasture located at a higher altitude. In the two studies, hair samples, obtained using clippers from the animal's forehead, were collected on the 20th June (P1), 20th July (P2), 20th August (P3), 20th September (P4) and 20th October (P5) and analysed for cortisol and DHEA. In experiment I, DHEA concentration was unaffected by sampling time (P > 0.05), whereas, cortisol/DHEA ratio was similar between P1 and P2 (P > 0.05) and then increased during the experimental period reaching the highest value at P5 (P < 0.05). In experiment II, dairy cows had higher concentration of DHEA during grazing compared to cows kept indoors (P < 0.05), conversely cortisol/DHEA ratio decreased from P1 to P2 (P < 0.05), remained constant from P2 to P3 (P > 0.05) and then increased from P3 to P4 (P < 0.05), the highest value was recorded at P5. In conclusion, cortisol and DHEA concentrations and their ratio measured in the hair of dairy cows can be useful to evaluate the allostatic load in animals managed indoor in tie-stall barn or grazing on mountain pasture.
Najdeno v: ključnih besedah
Ključne besede: Dairy cow, Mountain pasture, Hair, Cortisol, DHEA
Objavljeno: 28.05.2017; Ogledov: 1458; Prenosov: 0
.pdf Polno besedilo (205,07 KB)

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