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The postpartal period in high-yielding dairy cows can be characterized as a time when animal has to undergo several important changes affecting all the organism. After pregnancy and parturition, organism has to adapt itself to the lactation and this stressing experience contributes to the high incidence of health disorders. These include ketosis, fatty liver, milk fever, retained placenta, metritis, mastitis, laminitis, and other metabolic and reproductive disorders. They may become clinically manifested in later stages of the reproduction cycle but have their primary cause in early postpartal period. To overcome these problems, every farmer has to practice good herd health management, especially when considering the transition period. To discover the weak points of the herd management we can use some indices that can be determined from the blood samples of dairy cows after partuition. We collected blood samples from 170 dairy cows of Slovak spotted breed 1 to 8 weeks after parturition. None of them manifested clinical signs of any illness. We divided them into the 6 groups depending on the number of weeks post partum.We observed and evaluated the main blood-chemistry parameters of energy and liver metabolism (glukose, triglycerides, total lipids, total cholesterol, non-esterified fatty acids, beta-hydroxybutyrate, total bilirubin), protein metabolism (total immunoglobulins, total protein, albumine, Creatinin, urea) and levels of some serum enzymes (AST, GGT, ALP, CPK, LDH). Even though there were no alterations in the health status present in that time, we found out that some indices, mostly of energy and liver metabolism, such as serum levels of non-esterified fatty acids, triglycerids, etc. were altered. This fact can help us to trace the potentially threatened individuals and to iniciate the steps that would minimize further damage.
Many hypothalamic nuclei are involved in the regulation of food intake and energy homeostasis. An ultrastructural investigation of the hypothalamic ventromedial nucleus (VMN), a hypothetical “satiety centre” was performed to explore the morphological basis of altered feeding behaviour of old rats in an experimental model of fasting/refeeding. Young (5 months old, n = 12) and old (24 months old, n = 12) male Wistar rats were fasted for 48 hours, then refed for 24 hours and sampled thereafter. Brain tissue was fixed by perfusion, histological and ultrathin sections were obtained by routine methods. Although food intake was similar in control young and old rats, during refeeding old animals consumed less chow than young ones. The EM analysis of VMN neurones of old control rats revealed, besides typical age-related residual bodies, deep indentations of the nuclear envelope and the presence of long, undulating rough endoplasmic reticulum cisternae in the cell periphery. In both young and old rats fasting for 48 hours led to the expansion of Golgi complexes and increased folds of the nuclear envelope, which is suggestive of enhanced cellular activity of the VMN neurones. These fasting-induced alterations were sustained in the VMN neurones of refed rats in both age groups. The results showed that the VMN neurones of old control rats differ at the ultrastructural level from young ones. However, starvation and subsequent refeeding cause similar alterations in the hypothalamic neurones of “satiety centre” of both young and old rats.
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