The automated collection of phenotypic measurements in livestock is becoming increasingly important to both researchers and farmers. The capacity to non-invasively collect real-time data, provides the opportunity to better understand livestock behaviour and physiology and improve animal management decisions. Current climate models project that temperatures will increase across the world, influencing both local and global agriculture. Sheep that are exposed to high ambient temperatures experience heat stress and their physiology, reproductive function and performance are compromised. Body temperature is a reliable measure of heat stress and hence a good indicator of an animals’ health and well-being. Non-invasive temperature-sensing technologies have made substantial progress over the past decade. Here, we review the different technologies available and assess their suitability for inferring ovine heat stress. Specifically, the use of indwelling probes, intra-ruminal bolus insertion, thermal imaging and implantable devices are investigated. We further evaluate the capacity of behavioural tracking technology, such as global positioning systems, to identify heat stressed individuals based on the exhibition of specific behaviours. Although there are challenges associated with using real-time thermosensing data to make informed management decisions, these technologies provide new opportunities to manage heat stress in sheep. In order to obtain accurate real-time information of individual animals and facilitate prompt intervention, data collection should be entirely automated. Additionally, for accurate interpretation on-farm, the development of software which can effectively collect, manage and integrate data for sheep producer’s needs to be prioritised. Lastly, understanding known physiological thresholds will allow farmers to determine individual heat stress risk and facilitate early intervention to reduce the effects in both current and subsequent generations.

Betaine increases the synthesis of creatine, an energy-rich amino acid that increases adenosine triphosphate (ATP) and has neuroprotective properties which may improve post-natal lamb survival. This study determined whether maternal betaine supplementation during gestation would improve body weight, thermoregulation, time to stand and suck, colostrum intake and survival to weaning of twin lambs. Twin-bearing Merino ewes received dietary betaine at either 0 g/day (Control, CTL), 2 g/day from ram introduction to parturition (Early betaine, EB) or 4 g/day from Day 80 of gestation to parturition (Late betaine, LB). Ewes were housed individually during parturition and measures were collected at 4, 24 and 72 h and Day 7 post-partum, and at marking (53.2 ± 0.2 days of age) and weaning (99.3 ± 0.2 days of age). The EB treatment resulted in heavier lambs at weaning compared with CTL and LB lambs (p < 0.05). Time to stand and suck from birth was longer in EB lambs (p < 0.05), whereas, the interval from birth to first suck was shorter for LB lambs (p < 0.05). Lamb survival rate was the highest for LB lambs at 72 h and Day 7 (p < 0.05), and lowest for EB lambs on Day 7 (p < 0.05). These data indicated that betaine supplementation at 4 g/day during the second half of pregnancy improved twin lamb survival to Day 7 and shortened the interval from birth to first suck; whereas feeding ewes 2 g/day of betaine for the duration of pregnancy increased twin lamb body weight at weaning, but increased both the time to attain behavioural milestones and mortalities before Day 7.

Remote-sensing technology facilitates longitudinal collection of body temperature during periods of hot or cold environmental stress without human interference, producing high-frequency measurements whilst reducing labour and stress to the animal. A pilot study was conducted to validate an improved, minimally invasive method for the continual measurement of vaginal temperature (VT) in female sheep. A silicon mould of a modified controlled internal drug release (CIDR) device (Zoetis Animal Health, Parsippany), was manufactured to securely house a temperature logger (Micro-T 16-bit; Star Oddi, Iceland) and allow direct contact at the collection site. These temperature-sensing CIDR devices were validated against manual rectal temperature (RT) measurements collected from 15 mature, non-pregnant, non-lactating Merino ewes. Rectal temperature was measured from each individual, six times per day in 2-h intervals for 14 consecutive days. The simultaneous measures of VT and RT did not differ significantly within each ewe (P > 0.05) and demonstrated a moderate linear relationship (R2 = 0.62, P < 0.05). The mean (± SEM) difference between RT and VT was small (0.010 ± 0.004 °C), with a 95% confidence interval of − 0.26 to 0.29 °C. Additionally, the coefficient of variation was lower on average for VT (0.49%) compared to RT (0.59%). Differences among paired readings were likely due to interval variation as well as penetration depth, air influx and faecal temperature when collecting RT. The initial silicone manufacturing costs were high (2200 AUD), with each unit costing 1.25 (AUD) thereafter; however, the temperature-sensing CIDR device was an effective and efficient research tool for the remote monitoring of body temperature. While further validation of these devices within extensive grazing environments is warranted, the collection and analysis of longitudinal physiological data from ewes has the potential to improve a variety of management aspects related to extensively grazed ewes maintained and joined in harsh conditions.

No abstract