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Simple Summary: Factors such as social isolation, environmental unpredictability, and the need for physical containment are commonly present in experimental flow respirometry trials, which in turn are highly likely to induce voluntary and the autonomic fear responses in animals. These responses can introduce biases, often invisible, to study interpretations. In this study, we employed a protocol to train 30 Nellore cattle for non-ventilated and valved facial mask flow respirometry trials. The training lasted 127 days and consisted of gradually altering the animals' environment and associating it with positive stimuli. During this period, we evaluated the pattern of evolution of the animals' reactivity through behavioral and physiological measures. An unsupervised artificial intelligence model was employed to identify dissimilarity patterns among the animals. Overall, animals classified as less reactive (n = 17) presented reduced aversive behavioral responses to containment (e.g., trunk movement, attempts to remove the mask) and to the use of the valved facial mask, while those more reactive (n = 13) had a progressive increase in these responses. At the end of the training, less reactive animals could be contained in the chute and wear the valved facial mask for 25–30 min without apparent behavioral and physiological changes. Training is instrumental in identifying and selecting cattle that exhibit greater cooperation with experimental conditions required in flow respirometry assays, like restraint and the use of a valved facial mask. In our study, a tailored training protocol for Nellore cattle facilitated their participation in flow respirometry assays with a valved facial mask. Over 127 days, 30 entire Nellore males, weighing 450 ± 25 kg and averaging 32 ± 2 months, underwent training from May to September 2022. The regimen involved gradually altering the animals' environment and providing positive reinforcement, divided into three phases. Physiological and behavioral responses to containment routines and facial mask use were meticulously assessed. Principal component analyses revealed dissimilarity patterns among the animals. Animals classified as less reactive showed increased acceptance of handling, reduced reactions to weighing, and greater tolerance of the facial mask. In the final phase, the least reactive animals tolerated wearing a valved mask for extended periods without notable changes in respiratory rate. The training protocol effectively identified and selected Nellore cattle displaying enhanced cooperation with restraint and mask use during flow respirometry assays, without apparent behavioral or physiological alterations. [ABSTRACT FROM AUTHOR]

We used a high‐precision weighing system and flow‐through respirometry to quantify cutaneous evaporative water loss rates in woolly sheep (wool thickness, ca. 6.5 cm) and haired goats (coat thickness, ca. 2.5 cm), while simultaneously recording parallel data obtained from (1) a flow‐through ventilated capsule, (2) a closed hand‐held electronic evaporimeter chamber, and (3) a closed colorimetric paper disc chamber. In comparison to the weighing system and respirometry, used here as a "gold standard" measure of cutaneous evaporative water loss rate, we found relatively good agreement with data obtained from the flow‐through ventilated capsules. However, we found poor agreement with data obtained from the closed electronic evaporimeter chambers (underestimated by 60%, on average) and the closed colorimetric paper disc chambers (overestimated by 52%, on average). This deviation was likely associated with a requirement for shaved skin in the closed chamber methods. Our results therefore cast doubt on the validity of the closed chamber methods for measurement of cutaneous evaporative water loss rates in furred and fleeced mammals, and instead show that more accurate values can be obtained using flow‐through ventilated capsules. Highlights: Flow‐through ventilated capsules are more accurate than closed chamber methods for measuring cutaneous evaporative water loss rate in furred and fleeced mammals. The requirement for shaved skin may explain the apparent inaccuracy of the closed chamber methods [ABSTRACT FROM AUTHOR]

Thirty four lambs and twenty multiparous Morada Nova ewes with 3 ± 1.2 years of age were evaluated in a semi-extensive system for assessments of their suckling activities when they were 10-40 days old. The body mass (kg) and biometric measurements were also assessed at each 15 days from birth to 90 days of age. From 15 to 90 days of age, single lambs had superior (P < 0.05) body mass than those twins. Both for single and twins the daily weight gain substantially decreased (P < 0.05) after thirty days of age. There was a high correlation (i.e., r > 0.90; P < 0.05) between all biometric measurements and body mass of lambs. Both for single and twins the frequency of suckling decreases (P < 0.05) as the lambs grows older. At 20 days, mothers of twin lambs prevented more (P < 0.05) the suckling attempts than those of single lambs. Both for single and twin lambs the suckling success was lower (P < 0.05) when they were 20 days of age. The present study sheds some light on how the dynamics between growth performance of Morada Nova lambs and the maternal investment are linked [ABSTRACT FROM AUTHOR]

Training is instrumental in identifying and selecting cattle that exhibit greater cooperation with experimental conditions required in flow respirometry assays, like restraint and the use of a valved facial mask. In our study, a tailored training protocol for Nellore cattle facilitated their participation in flow respirometry assays with a valved facial mask. Over 127 days, 30 entire Nellore males, weighing 450 ± 25 kg and averaging 32 ± 2 months, underwent training from May to September 2022. The regimen involved gradually altering the animals' environment and providing positive reinforcement, divided into three phases. Physiological and behavioral responses to containment routines and facial mask use were meticulously assessed. Principal component analyses revealed dissimilarity patterns among the animals. Animals classified as less reactive showed increased acceptance of handling, reduced reactions to weighing, and greater tolerance of the facial mask. In the final phase, the least reactive animals tolerated wearing a valved mask for extended periods without notable changes in respiratory rate. The training protocol effectively identified and selected Nellore cattle displaying enhanced cooperation with restraint and mask use during flow respirometry assays, without apparent behavioral or physiological alterations.

This review makes an attempt to characterize the physical attributes of heat tolerance, thermal equilibrium and thermal stress thresholds for dairy cows living in tropical environments, with a particular emphasis on pasture-based systems. Under such circumstances, the radiant heat load is the principal climatic factor that determines rates of heat and mass exchanges between cows and the environment. This fact may explain why simple mechanistic models based on air temperature and humidity are not adequately predicting thermal stress thresholds for cattle in tropical regions. To overcome this limitation, the Index of Thermal Stress for Cows (ITSC) and Index for the time spent in shade (ITS), which account for various sources of thermal radiation, were proposed to predict autonomous and behavioral thermoregulation of cows. Overall, the evolutionary adaptation of cattle in tropics favored animals that have cutaneous surface with a skin well protected against penetration of ultraviolet solar radiation (UV), covered by a coat surface with high thermal conductivity. For Holstein breed, although predominantly black animals absorb greater levels of short-wave solar radiation, they may present better protection of skin than white ones. However, dark-colored cows in tropical pastures have potential to absorb as much as 640 W m -2 of thermal radiation. This amount of heat load would require close to 1,300 g h -1 of cutaneous evaporative water loss through sweating to prevent increases to body temperature, where cows do not have access to shade. Cows are motivated to reduce time spent grazing and to seek shade when solar irradiance exceeds 550 W m -2 , levels that in equatorial latitudes are likely to occur between 08:00 and 16:00h. This information may help producers improve the welfare of cows, as they can determine more comfortable hours for them to graze, for example, by employing nocturnal grazing. Over the daytime, cows should have access to areas with shade and this could include shade provided via solar panels, which has the potential to improve thermal comfort and sustainability of dairy production in tropical areas., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Santos, Saraiva, Gonzaga Neto, Maia, Lees, Sejian, Maia, Medeiros and Fonsêca.)