Climate change is a major global threat to the sustainability of livestock systems. Climatic factors such as ambient temperature, relative humidity, direct and indirect solar radiation and wind speed influence feed and water availability, fodder quality and disease occurrence, with production being most efficient in optimal environmental conditions. Among these climatic variables, ambient temperature fluctuations have the most impact on livestock production and animal welfare. Continuous exposure of the animals to heat stress compromises growth, milk and meat production and reproduction. The capacity of an animal to mitigate effects of increased environmental temperature, without progressing into stress response, differs within and between species. Comparatively, small ruminants are better adapted to hot environments than large ruminants and have better ability to survive, produce and reproduce in harsh climatic regions. Nevertheless, the physiological and behavioral changes in response to hot environments affect small ruminant production. It has been found that tropical breeds are more adaptive to hot climates than high-producing temperate breeds. The growing body of knowledge on the negative impact of heat stress on small ruminant production and welfare will assist in the development of suitable strategies to mitigate heat stress. Selection of thermotolerant breeds, through identification of genetic traits for adaption to extreme environmental conditions (high temperature, feed scarcity, water scarcity), is a viable strategy to combat climate change and minimize the impact on small ruminant production and welfare. This review highlights such adaption within and among different breeds of small ruminants challenged by heat stress.

Are insects the farm animal of the future? A key agenda for agricultural production systems is the development of sustainable practices whereby food and feed can be produced in an environmentally efficient manner. These goals require novel approaches to complex problems and demand collaboration between scientists, producers, consumers, government and the general population. The provision of feed for animals is a major contributor to land and water use and greenhouse gas (GHG) emissions. Further, overfishing and a reduction in available land and water resources on which crops can be grown has led to an increase in price of protein ingredients such as fish meals and oils and soybean meals. Determination of novel solutions to meet the feed protein requirements of production animals is key to the development of sustainable farming practices. The Australian pork industry aims to develop production systems that efficiently use available resources (such as feed and energy) and limit the production of emissions (such as manure waste and GHGs). Invertebrates (insects e.g. black soldier flies) are naturally consumed by monogastric and aquatic species, yet the large-scale production of insects for feed (or food) is yet to be exploited. Most insects are low producers of GHGs and have low land and water requirements. The large-scale production of insects can contribute to a circular economy whereby food and feed waste (and potentially manure) are reduced or ideally eliminated via bioconversion. While the concept of farm-scale production of insects as domestic animal feed has been explored for decades, significant production and replacement of traditional protein sources has yet to be achieved. This review will focus on the potential role of insect-derived protein as a feed source for the Australian pig production industry.

Heat stress negatively impacts on a variety of animal production parameters. Advances in management strategies have alleviated some of the negative impacts of thermal stress on farm animals, but production continues to markedly decrease during heat events in summer, particularly in dairy cattle. In this paper we introduce a Dairy Risk Assessment Program (DRAP). The DRAP is a user-friendly software package designed to assist users in predicting heat loads in dairy cow herds. DRAP was developed over three Australian summers using climatic data (temperature, humidity, solar radiation and wind speed), cow production data (milk yield and milk quality), and physiological data (respiration rate and body temperature). The data were used to develop mathematical algorithms which can predict animal response to climatic variables. This software package is designed to be used by the dairy industry to better manage cows during times of elevated environmental temperatures by equipping producers, managers, and dairy industry personnel with Dairy Heat Load Index (DHLI) values which were calculated based upon site information, stock characteristics, management practices, and mitigation variables specific to their dairy production unit. When a heat event is imminent producers can then introduce management strategies such as providing shade or additional water troughs or implementation of nutritional strategies. Some of these nutritional strategies include dietary chromium picolinate, betaine and antioxidant supplementation or altering the rate of starch fermentation. These nutritional strategies are discussed at some length in this paper.

Pigs are comparatively less heat tolerant than other species of production animals, which poses challenges for stock productivity and management during seasonal heat waves that occur in summer. The issues surrounding heat and pig production are predicted to increase, based on the actions of climate change increasing the intensity, frequency and duration of heat waves. Furthermore, future growth areas of pig production are going to be in tropical regions such as South-east Asia and Latin America. Efforts by the pig to dissipate excess body heat come at a cost to health and divert energy away from growth, compromising efficient pig production. Management of heat stress requires multiple strategies, and recent research is improving the understanding of the application of nutritional strategies to ameliorate the effects of heat stress. In particular the use of feed additives is an important, flexible and economical method to alleviate heat stress and the intensive nature of pig production lends itself to the use of additives. Some specific examples include antioxidants, betaine and chromium, which have been proved effective or being tested in mitigating some certain impacts of heat stress in pigs. The aim of this review is to summarise recent advances in the nutritional management of heat stress in pigs.

Heat exposure (HE) results in decreased production in ruminant species and betaine is proposed as a dietary mitigation method. Merino ewes ( n = 36, 40 kg, n = 6 per group) were maintained at thermoneutral (TN, n = 18, 21 °C) or cyclical HE ( n = 18, 18–43 °C) conditions for 21 days, and supplemented with either 0 (control), 2 or 4 g betaine/day. Sheep had ad libitum access to water and were pair fed such that intake of sheep on the TN treatment matched that of HE animals. Heart rate (HR), respiration rate (RR), rectal (T _R ) and skin temperatures (T _S ) were measured 3 times daily (0900 h, 1300 h, 1700 h). Plasma samples were obtained on 8 days for glucose and NEFA analysis. The HE treatment increased T _R by 0.7 °C (40.1 vs. 39.4 °C for HE and TN respectively p < 0.001), T _S by +1.8 °C (39.3 vs. 37.5 °C, p < 0.001) and RR by +46 breaths/min (133 vs. 87 breaths/min, p < 0.001) compared to TN. The 2 g betaine/day treatment decreased T _R (39.8, 39.6 and 39.8 °C, p < 0.001), T _S (38.7, 38.0 and 38.5 °C, p < 0.001) and RR (114, 102 and 116 breaths/min for control, 2 and 4 g betaine/day, p < 0.001) compared to control. Betaine supplementation decreased plasma NEFA concentrations by ~25 μM (80, 55 and 54 μmol/L for 0, 2 and 4 g/day respectively, p = 0.05). These data indicate that dietary betaine supplementation at 2 g betaine/day provides improvements in physiological responses typical of ewes exposed to heat stress and may be a beneficial supplement for the management of sheep during summer.