An experiment was conducted to evaluate whether dietary reduction and sex class affect nutrient intake, digestibility, purine derivative (PD) excretion and heat tolerance coefficient in lambs. Thirty-five hair lambs (14.5 ± 0.89 kg initial body weight (BW), 2 months old) were used in a completely randomized study with a 3 × 3 factorial arrangement, three sex classes (11 intact males, 12 castrated males and 12 females) and three levels of feeding (ad libitum, 300 and 600 g/kg/dry matter (DM) feed restriction) for 120 days. Intact and castrated males showed higher intakes of DM and neutral detergent fibre corrected for ash and protein (NDFap) than females. At 300 g/kg/DM feed restriction, NDFap digestibility was lower in intact males than in other classes; however, no differences were found between classes when subjected to ad libitum feeding or 600 g/kg/DM. The basal endogenous nitrogen and endogenous urinary losses were highest in intact males. Allantoin, uric acid and PD excretion, as well as PD absorption and microbial protein production were lowest in the animals subjected to 600 g/kg/DM feed restriction. Microbial protein synthesis (MPS) was highest in animals subjected to 600 g/kg/DM feed restriction. The lowest temperatures were observed in animals subjected to 600 g/kg/DM feed restriction. The heat tolerance coefficient was highest in animals subjected to 600 g/kg/DM feed restriction. In conclusion, feed restriction reduced the time spent on feeding and rumination but increased the digestibility of DM. The restriction level of 600 g/kg/DM maximized MPS and infrared thermography indicated an elevated heat tolerance coefficient.

In this Research Communication we describe the effect of temperature and humidity index (THI) on various physiological traits, the plasma heat shock protein 70 (HSP70), heat shock protein 90 (HSP90) and cortisol levels and other blood parameters in crossbred buffalo (Nili-Ravi × Murrah) and Mediterranean buffalo to compare their tolerance to heat stress. As expected, crossbred buffalo had a significantly higher rectal temperature (RT), body surface temperature (BT), respiratory rate (RR), HSP70 and HSP90 levels in summer compared to spring and winter. RT and BT were also significantly higher in spring compared to winter. A significant correlation existed between THI and RT (r = 0·81) and RR (r = 0·84). Importantly, in summer the crossbred buffalo had a significantly lower RT, BT and RR and higher HSP70, HSP90 and cortisol levels than the Mediterranean buffalo. In conclusion, higher THI was associated with significant increase in RT, RR, BT, HSP70, HSP90 and cortisol levels, and the crossbred buffalo were more heat tolerant than Mediterranean buffalo.

Exposure of livestock to high heat loads negatively affects animal’s productivity. Genetic selection for heat tolerance using quantitative approaches has been developed by making use of the milk recording information merged with the meteorological information in the test date. The main conclusions of the studies following this approach have been that there is genetic variability in the response to heat stress (HS), that a genotype by environment interaction between thermal comfort and HS conditions exists and that there is a genetic antagonism between HS tolerance and high milk production. This approach has the advantage of adding no extra costs to the existing milk recording schemes, but it has some disadvantages. Current milk recording information does not seem to fully capture the productive response to high heat loads. Moreover, the antagonism between heat tolerance and high milk production may offset the benefits of selection for this trait if heat-tolerant animals are less productive. The use of new tools from phenomics, genomics and transcriptomics can help in achieving an accurate selection of heat-tolerant animals without damaging progress in milk production. New phenotypes for this selection are measure of body temperature and respiration rates together with measures of indicators of heat tolerance in milk, through the use of mid IR spectroscopy. The use of commercial DNA chips to perform genome wide association studies or comparison of whole genome DNA sequence of animals of heat adapted and temperate climate breeds could also provide useful genomic information. Finally, RNA sequencing together with the recent discovery of the possibility to use the milk transcriptome instead of tissue biopsies could help to discover differentially expressed genes under HS and thermoneutrality. The existence of powerful tools to achieve better phenotypes to identify tolerant v. susceptible animals and to gain insights about the genetic mechanisms underlying HS response to be able to disentangle the genetic puzzle of heat tolerance may make possible the selection of heat-tolerant and still productive animals.

It is well documented that global warming is unequivocal. Dairy production systems are considered as important sources of greenhouse gas emissions; however, little is known about the sensitivity and vulnerability of these production systems themselves to climate warming. This review brings different aspects of dairy cow production in Central Europe into focus, with a holistic approach to emphasize potential future consequences and challenges arising from climate change. With the current understanding of the effects of climate change, it is expected that yield of forage per hectare will be influenced positively, whereas quality will mainly depend on water availability and soil characteristics. Thus, the botanical composition of future grassland should include species that are able to withstand the changing conditions (e.g. lucerne and bird's foot trefoil). Changes in nutrient concentration of forage plants, elevated heat loads and altered feeding patterns of animals may influence rumen physiology. Several promising nutritional strategies are available to lower potential negative impacts of climate change on dairy cow nutrition and performance. Adjustment of feeding and drinking regimes, diet composition and additive supplementation can contribute to the maintenance of adequate dairy cow nutrition and performance. Provision of adequate shade and cooling will reduce the direct effects of heat stress. As estimated genetic parameters are promising, heat stress tolerance as a functional trait may be included into breeding programmes. Indirect effects of global warming on the health and welfare of animals seem to be more complicated and thus are less predictable. As the epidemiology of certain gastrointestinal nematodes and liver fluke is favourably influenced by increased temperature and humidity, relations between climate change and disease dynamics should be followed closely. Under current conditions, climate change associated economic impacts are estimated to be neutral if some form of adaptation is integrated. Therefore, it is essential to establish and adopt mitigation strategies covering available tools from management, nutrition, health and plant and animal breeding to cope with the future consequences of climate change on dairy farming.

Heating the ambient air of a whole, or a portion of a food-processing facility to 50 to 60°C and maintaining these elevated temperatures for 24 to 36 h, is an old technology, referred to as heat treatment. There is renewed interest in adopting heat treatments around the world as a viable insect control alternative to fumigation with methyl bromide. There is limited published information on responses of the Indian meal moth, Plodia interpunctella (Hübner), exposed to elevated temperatures typically used during heat treatments. Time-mortality relationships were determined for eggs, fifth-instars (wandering-phase larvae), pupae, and adults of P. interpunctella exposed to five constant temperatures between 44 and 52°C. Mortality of each stage increased with increasing temperature and exposure time. In general, fifth-instars were the most heat-tolerant stage at all temperatures tested. Exposure for a minimum of 34 min at 50°C was required to kill 99% of the fifth-instars. It is proposed that heat treatments aimed at controlling fifth-instars should be able to control all other stages of P. interpunctella.

Their higher production performance and feed conversion efficiency make today's chickens more susceptible to heat stress than ever before. The increasing proportion of poultry production in tropical and subtropical regions makes it necessary to reconsider the long-term selection strategy of today's commercial breeding programmes. Also, the importance of the potential use of Naked neck and Frizzle genes is accentuated. Nutritional strategies aimed to alleviate the negative effects of heat stress by maintaining feed intake, electrolytic and water balance or by supplementing micronutrients such as Vitamins and minerals to satisfy the special needs during heat stress have been proven advantageous. To enhance the birds' thermotolerance by early heat conditioning or feed restriction seems to be one of the most promising management methods in enhancing the heat resistance of broiler chickens in the short run.

Resting heat production (H), respiratory rate (RR) and rectal temperature (Tr) were measured at different controlled temperatures (Tt) in Hariana (Bos indicus) and its F, crosses with Jersey (JH), Brown Swiss (BH) and Holstein Friesian (FH) (Bos taurus) breeds and the values obtained were used to assess their relative thermosensitivity.

The lowest Tt at which H significantly decreased from that at 17°c was 32°c for Hariana, JH and BH and 27°c for FH after exposure for 8 days. The corresponding values after exposure for 18 days were 37°c for Hariana and 32°c for all the three crossbred groups. Differences between the genetic groups were also significant. The lowest Tt at which metabolizable energy (ME) decreased significantly in comparison with those at 17CC was 32°c in all the genetic groups. The differences in ME intake between genetic groups were significant only at 32°c Tt. The lowest Tt at which RR significantly increased from those at 17°c were 32°c in Hariana, 27°c in JH, BH and FH for both 5 to 7 and 15 to 17 days of exposure. The corresponding Tt for increase in Tr was 37°c in Hariana, 32°c in JH and 27°c in BH and FH at both 5 to 7 and 15 to 17 days of exposure.

The ambient temperature at which H would have significantly decreased and RR and Tr increased from the respective values at 17CC Tt were calculated curvilinearly for different genetic groups. There were differences in these values of calculated ambient temperatures between genetic groups and between exposure durations in respect of H, RR, and Tr, indicating differences in thermosensitivity.