Effects of heat stress and diet on milk production and feed and energy intake of Sarda ewes

Ten Sarda dairy ewes (5th-6th month of lactation; 1995 ± 353 g/d of milk yield) were divided into two isoproductive groups and fed two different diets (high and low fiber) from May 20th to June 18th 2003, to evaluate diet effects on milk yield and intake. In addition, the relationships between meteorological conditions, measured during that unusually hot period, and milk yield and quality, dry matter intake, NDF or NDL were determined, to study animal responses to heat stress. Diet did not have any significant effect on the evaluated parameters. Milk yield was reduced by 20% (0.39 kg/d per head) as minimum temperatures changed from 9-12 °C to 18-21 °C. Similar milk yield reduction was observed as mean temperature-humidity index (THI) went from 60-65 to 72- 75. As wind speed increased from 1.5-2.5 m/s to 2.5-4 m/s, milk yield increased by 10%. Milk composition was not affected by heat stress throughout the experiment except for milk somatic cell count, which was increased by high temperatures. Dry matter, fibre and net energy intake varied significantly during the trial, with consistent and marked decreases as heat load increased

Cold markedly influences milk yield of Sardinian dairy sheep farms

The effects of cold stress on milk production have been widely examined in cattle and goats but little studied in dairy sheep. For this reason, the milk production of 10 dairy sheep farms, located throughout the Sardinian island, was analysed in relation to winter and early-spring meteorological conditions. From January 1st to March 31st, in 2003 and 2004, bulk milk production data were collected every 48 hours. From January 15th to April 30th of the same years, bulk milk production was also measured daily in five out of the ten studied farms. During the same periods, meteorological data were collected from stations of the Weather Forecast Service of Sardinia located near the farms. To determine the effects of meteorological conditions on milk yield, analysis of variance using the SAS (SAS Institute Inc., Cary, NC, USA) mixed procedure was performed. The results showed that minimum and mean temperatures, as well as number of hours under a critical threshold temperature (-3 °C, 0 °C and 3 °C), influenced milk yield, with a progressive decrease in milk yield as unfavourable cold conditions increased. In particular, as minimum temperatures decreased from the optimal values of 9-12 °C down to -3 °C, milk yield decreased by 25% (0.30 kg/d per head), with relevant decreases as temperatures went below 0-3 °C. In addition, in the daily dataset decreases up to 30% (0.40 kg/d per head) in milk yield occurred, as mean temperatures went below the optimal values of 15-18 °C. Other factors such as maximum temperature, wind speed, rainfall, relative humidity, Wind Chill Index (WCI) and number of hours under 7 °C and 10 °C did not significantly influence milk yield. The only interaction that significantly influenced milk yield was that between wind speed and number of hours under -3 °C. In fact, in particularly cold days, wind increased animal discomfort, thus negatively influencing milk production. Non significant variations occurred between the two years studied, while production differed significantly among farms, probably due to differences in their managerial techniques. In conclusion, cold stress can markedly decrease milk yield of dairy ewes even in Mediterranean climatic conditions

Effects of heat stress on milk yield in Sardinian dairy sheep farms

The effects of heat stress on milk production of dairy ewes have been very little studied, especially under Mediterranean conditions. For this reason, such effects were studied in ten Sarda dairy sheep farms associated to the Sardinian Breeders Association, located throughout Sardinia. They had whole farm milk yield records registered every 48 hours from April 1st until July 15th, in the years 2003 and 2004. Meteorological data were obtained from data collected by meteorological stations of the Weather Forecast Service of Sardinia located near each farm. To determine the effects of meteorological conditions on milk yield, analysis of variance using the SAS (SAS Institute Inc., Cary, NC, USA) mixed procedure was performed. The results showed that Sarda dairy sheep were highly sensitive to high temperatures, especially when they persisted for long periods. All analysed meteorological factors, except for wind speed, significantly influenced milk yield. Milk yield was more influenced by minimum air temperatures than by any other meteorological parameter. Increases in minimum temperatures from the optimal range of 9-12 °C up to 27-30 °C caused on average a decrease in milk yield of 36% (0.35 kg/d per head). The highest milk yields were observed at maximum air temperatures ranging from 24 to 30 °C and at mean temperatures varying from 15 to 18 °C, with progressive decreases, up to 20% (about 0.22 kg/d per head), at higher temperatures. The effects of duration of temperatures higher than some threshold values on milk yield were also relevant. Optimal air relative humidity for milk production was between 65 and 75%, in accordance with values reported in the literature. Rainfall negatively influenced milk yield, probably because it disturbs grazing, with decreases up to 23% (0.20 kg/d per head) under conditions of 6 mm-cumulative rainfall in two days. Milk production was also influenced by Temperature Humidity Index (THI), with a decrement of 25% (0.23 kg/d per head) as THI increased from 60-65 to 72-75.Wind influenced milk yield only when associated with other meteorological factors; it alleviated the negative effects of heat stress on milk yield at higher speed values. In conclusion, despite of their small body size, which should favour heat exchange and thermoregulation, milk yield of Sarda ewes was markedly reduced by heat stress

Para -Aminosalicylic acid in the treatment of manganese toxicity. Complexation of Mn2+ with 4-amino-2-hydroxybenzoic acid and its N -acetylated metabolite

Manganese excess can induce in humans a neurological disorder known as manganism. A possible remedy should be chelation therapy, even though a chelation schedule for manganism has not been currently established. para-Aminosalicylic acid (PAS) has demonstrated effectiveness in reducing manganism symptoms. In this work, a study of the protonation equilibria of para-aminosalicylic acid and of its N-acetylated metabolite (Ac-PAS) and of their complexation reactions with Mn2+ is presented, and also extended to the main essential metal ions Cu2+ and Fe3+. A number of complementary techniques (potentiometry, spectrophotometry, fluorimetry, EPR) have been used for a thorough comprehension of the protonation and complex formation equilibria, with the addition of DFT calculations, which provide insights into the relative stabilities and electronic properties of the formed species. Both PAS and Ac-PAS form 1 : 1 and 1 : 2 metal : ligand complexes with the target Mn2+ ion; surprisingly the N-acetylated metabolite forms stronger complexes, whose implications in chelation therapy have been pointed out by a speciation study. It is presumed that the relatively small metabolite can penetrate across the blood-brain-barrier and exert its Mn-mobilizing action intracellularly in vulnerable neurons

New perspective for an old drug: Can naloxone be considered an antioxidant agent?

Background: Experimental evidence indicates that Naloxone (NLX) holds antioxidant properties. The present study aims at verifying the hypothesis that NLX could prevent oxidative stress induced by hydrogen peroxide (H2O2) in PC12 cells. Methods: To investigate the antioxidant effect of NLX, initially, we performed electrochemical experiments by means of platinum-based sensors in a cell-free system. Subsequently, NLX was tested in PC12 cells on H2O2-induced overproduction of intracellular levels of reactive-oxygen-species (ROS), apoptosis, modification of cells' cycle distribution and damage of cells’ plasma membrane. Results: This study reveals that NLX counteracts intracellular ROS production, reduces H2O2-induced apoptosis levels, and prevents the oxidative damage-dependent increases of the percentage of cells in G2/M phase. Likewise, NLX protects PC12 cells from H2O2- induced oxidative damage, by preventing the lactate dehydrogenase (LDH) release. Moreover, electrochemical experiments confirmed the antioxidant properties of NLX. Conclusion: Overall, these findings provide a starting point for studying further the protective effects of NLX on oxidative stress