Recent studies have demonstrated photoperiodic changes in leptin sensitivity of seasonal mammals. Herein, we examined the interaction of season (long days (LD) versus short days (SD)) and recombinant ovine leptin (roleptin) on secretion of melatonin and prolactin (PRL) and on mRNA expression of suppressor of cytokine signaling-3 (SOCS-3) in the medial basal hypothalamus (MBH) in sheep. Twenty-four Polish Longwool ewes, surgically fitted with third ventricle (IIIV) cannulas, were utilized in a replicated switchback design involving 12 ewes per season. Within-season and replicate ewes were assigned randomly to one of three treatments (four ewes/treatment) and infused centrally three times at 0, 1 and 2 h beginning at sunset. Treatments were 1) control, Ringer-Locke buffer; 2) L1, roleptin, 0 . 5 mg/kg BW; and 3) L2, roleptin, 1 . 0 mg/kg BW. Jugular blood samples were collected at 15-min intervals beginning immediately before the start of infusions and continued for 6 h. At the end of blood sampling, a washout period of at least 3 days elapsed before ewes were re-randomized and treated with one of the treatments described above (four ewes/treatment). Ewes were then killed and brains were collected for MBH processing. Leptin treatments increased (P!0 . 001) circulating leptin concentrations compared with controls during both seasons in a dose-dependent manner. Overall, mean plasma concentrations of melatonin were greater (P!0 . 001) during LD than SD. However, leptin treatments increased melatonin concentrations during SD in a dosedependent manner and decreased it during LD. Similarly, plasma concentrations of PRL were greater (P!0 . 001) during LD than SD. However, unlike changes in melatonin, circulating PRL decreased (P!0 . 001) in response to leptin during LD. Semiquantitative PCR revealed that leptin increased (P!0 . 001) SOCS-3 expression in the MBH region during LD in a dosedependent manner. Data provide evidence that secretion of photoperiodic hormones such as melatonin and PRL are inversely regulated by leptin during SD and LD. However, the increase in expression of SOCS-3 in the MBH during LD compared with SD fails to fully explain these effects.

The push-pull perfusions of the infundibular nucleus-median eminence (IN/ME) were made in lactating ewes (nZ7) twice, to identify dopamine (DA)-derived salsolinol and the changes in its extracellular concentration in response to suckling. The perfusate collecting period in every ewe consisted of control non-suckling period, 1000-1230 h (five perfusates), and suckling period, 1230-1500 h (next five perfusates). Simultaneously, blood samples were collected from 1000 to 1500 h at 10-min intervals. The perfusate concentrations of salsolinol and DA were measured by HPLC, and plasma prolactin and GH concentrations were assayed by the RIA. Mean concentrations of salsolinol in perfusates collected from the anterior and posterior parts of the IN/ME (according to post-mortem localization of a perfusion site) increased significantly (P!0 . 05 and P!0 . 001 respectively) during the suckling period, when compared with those noted during the non-suckling period. While no DA was found in the anterior part, only vestigial amounts of DA were found in a few perfusates collected from the posterior part. Salsolinol was not detected in the IN/ME of ewes 10 weeks after weaning (seasonal anoestrus). Mean plasma prolactin and GH concentrations during suckling were significantly (P!0 . 001) higher than those noted during the non-suckling period. In conclusion, our current study reveals that salsolinol is present in the IN/ME of lactating ewes and that its extracellular concentration increases during suckling. Moreover, it supports the role of salsolinol as a neurotransmitter involved in the regulatory process of prolactin secretion at least during lactation.

Abstract. Changes in day length are a major factor in the productivity of farm animals showing reproductive seasonality. Parameters of milk production in sheep and goats are dependent on melatonin and prolactin concentrations. Changes in the prolactin secretion in lactating sheep have an effect on the amount of milk produced, synthesis of milk proteins, fat and immunoglobulins (i.e. milk composition). In the end the quality and commercial value of milk is determined as well. The aim of this study was therefore to find out the effect of day length and exogenous melatonin on the chemical composition of milk and the level of fatty acids. Subjects were 60 Polish Longwool Sheep. Animals were randomly assigned to three groups, Group I (n=20) – ewes raised under natural day length; Group II (n=20) ewes raised under natural day length and were implanted with melatonin; Group III (n=20) – ewes exposed to an artificially short photoperiod (16D:8L). Sheep were milked twice daily using the Alfa Laval Agri milking machine. Composite milk samples were collected every 28 days to determine chemical composition and fatty acid content. The results obtained showed that the administration of exogenous melatonin and the simulation of a short-day photoperiod during the summer period had significant effects on the milk levels of solids, protein, fat and lactose, and on the fatty acid content of sheep milk.

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P R O O F 4. Results 370 4.1. Land uses 370 4.2. Size of farm-holding, land prices, and grazing fees 372 4.3. Institutional economics 375 4.4. Institutional and legal frameworks 379 4.5. Forage deficit 381 4.6. Grazing infrastructure 385 4.7. Labor 388 4.8. Productivity estimates 390 4.9. Economic performance 395 4.10. Grazing management and trends 401 4.11. Main limiting factors 404 4.12. Interface to biodiversity 406 5. Discussion 408 References 414 European biodiversity significantly depends on large-scale livestock systems with low input levels. In most countries forms of grazing are organized in permanent or seasonal cooperations (land-owner/land-user agents) and covers different landscape such as alpine areas, forest, grasslands, mires, and even arable land. Today, the existence of these structures is threatened due to changes in agricultural land use practices and erratic governmental policies. The present chapter investigates six low-input livestock systems of grassland management with varying degrees of arrangements in different European countries and landscapes. These large-scale grazing systems (LSGS) are reindeer husbandry in Northern Sapmi (Fennoscandia), sheep grazing in the Polish Tatra mountains, cattle grazing in the Swiss and German Alps, cattle, sheep, and pig grazing in Baixo Alentejo, Southern Portugal, and sedentary sheep grazing in Central Spain. These systems showed very heterogeneous organizational patterns in their way of exploiting the pastoral resources. At the same time, these LSGS showed at least some of the following weaknesses such as poor economic performance, social fragility, and structural shortcomings for proper grazing management. Lack of proper mobility of herds/flocks or accession to specific grazing grounds can be a cause of environmental hazards. The surveyed LSGS are mostly dependent on public handouts for survival, but successive policy schemes have only showed mixed effects and, in particular study areas, clear inconsistencies in their aim to stop the general declining trend of LSGS. This research assumed that detailed system research may open the way for better-focused policy intervention, but policymakers need to take advantage of this period of support to push ahead for reforms. Recent European Union (EU) guidelines (2007-2013) on Rural Development Policy (RDP) and its operative scale of high nature value (HNV) farmland can easily fit the structure and functions of low-input grazing systems and LSGS. 352 Rafael Caballero et al.