Effect of time of day and type of shading on the physiological responses of crossbred calves in tropical environment

Lima, Patrícia de Oliveira; Souza, João Batista Freire de; Lima, Renata Nayhara de; Oliveira, Francisca Cedma de Sousa; Domingos, Hérica Girlane Tertulino; Tholon, P.; Miranda, Maria Viviane Freitas Gomes de

doi:10.14269/2318-1265.v01n01a02

Cited by 6 publications

(9 citation statements)

References 5 publications

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“…Lower respiratory rates in calves in shaded hutches are consistent with earlier observations that have shown in average 10.4 breaths/min lower respiratory rates (47.3 vs. 57.7 breaths/min) for shaded calves than for calves in hutches without shade when measured at 15:00 o’clock [ 14 ]. In the present study, differences were greater; by 25.9 and 17.8 breaths/min higher maximal respiratory rates in average on days 2 and 3, respectively ( Fig 5A ), in unshaded calves compared to shaded ones ( P < 0.001 for both days).…”

Section: Resultssupporting

confidence: 91%

“…A small number of studies on calves that measured rectal temperatures or respiratory rates used THI as environmental variable. It is also important to note, that data for the current study were collected in a continental region, in which low daytime humidity is a prevailing characteristic, while the referred experiments were done in tropical [ 14 , 15 ] or humid subtropical environments [ 4 ], therefore, comparison of the present results with earlier data is difficult.…”

Section: Resultsmentioning

confidence: 92%

“…Recent studies on heat stress of dairy calves tested different housing methods [ 4 , 16 ] or compared the stress-reducing efficiency of artificial vs. natural shade [ 14 ]; all using only rectal temperature and respiratory rate as indicators of heat stress. Here, the analysis was focused on ear temperature and heart rate as well that could be measured non-invasively and inexpensively both having the potential to assess heat stress in non-producing young calves.…”

Section: Resultsmentioning

confidence: 99%

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Assessment of heat stress in 7-week old dairy calves with non-invasive physiological parameters in different thermal environments

et al. 2018

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We estimated thermal stress in 7-week old Holstein bull calves during a warm episode in summer to study acute physiological responses of calves to heat stress. Data were collected over a 5-day period: day 1 (control), day 2 (heat stress), and a 3-day post-stress period in shaded (n = 8) and unshaded (n = 8) thermal environments. On the control day, both groups were shaded. Thermal environment was characterized by relative humidity, ambient temperature, and the temperature–humidity index (THI). Physiological variables included respiratory rate, rectal temperature, ear skin temperature and heart rate. Correlations between animal-based and meteorological indices were calculated, and ambient temperature correlated slightly better with physiological measures than THI. Rectal temperature was the only animal-based parameter that showed stronger correlations with the thermal indices when calculated for the shaded than for the unshaded environment [r = 0.42 vs. r = 0.47, P = 0.032 (ambient temperature), r = –0.39 vs. r = –0.45, P = 0.012 P = 0.015 (relative humidity), r = 0.41 vs. r = 0.46, P = 0.022 (THI)]. No differences were found between groups during the control day for any of the physiological parameters. During days 2 and 3, average and maximal values of respiratory and heart rates were higher in unshaded calves than in shaded ones. Maximal respiratory rates were in average by 25.9, 17.8 and 10.1 breaths/min lower in shaded calves than in unshaded calves for days 2, 3 and 4, respectively (P < 0.001, P < 0.001 and P = 0.024). Maximal heart rate was 127.4 ± 8.5 vs. 99.2 ± 6.3 beats/min on the heat stress day (P < 0.001), and 121.0 ± 6.9 vs. 103.4 ± 7.7 beats/min on day 3 (P = 0.006) in unshaded and shaded calves, respectively. Maximal body temperatures were higher measured either in the rectum or on the ear skin in unshaded calves than in shaded ones (with 0.5 and 1.6°C, P = 0.040 and P = 0.018, respectively), but only on the heat stress day. Based on our results, shading of young calves may be adequate for alleviating acute heat stress in continental regions. Ambient temperature is appropriate to estimate acute heat stress in dairy calves.

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Section: Resultssupporting

confidence: 91%

Section: Resultsmentioning

confidence: 92%

Section: Resultsmentioning

confidence: 99%

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Assessment of heat stress in 7-week old dairy calves with non-invasive physiological parameters in different thermal environments

et al. 2018

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“…Even with the rise in rectal temperature in the afternoon, the values are within the limits of variation established by Dukes (1996) for dairy calves (38.0 -39.3 °C). Façanha et al (2011) also found that Holstein calves in temperate climates had a higher respiratory rate at 15:00 h. compared to measurements made at 7:00 h. Similar results were found by Lima et al (2013) studying crossbred calves in equatorial environment. However, in the current study, the respiratory rate did not show a significant change at different times of the day (Table 2).…”

Section: Resultsmentioning

confidence: 55%

“…Some studies have been conducted to evaluate the physiological responses of calves in different types of facilities (Cunha et al, 2007a;Façanha et al, 2011;Lima et al, 2013). In addition, the analysis of thermal images of animals by infrared thermography to detect heat stress situations (Nääs et al, 2014, Torquato et al, 2015 and health status (Hoffmann et al, 2013) has grown in recent years.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of Physiological Responses of Calves During Rainy Season in the Semiarid Environment

Dantas¹,

Souza²,

Lima³

et al. 2016

Acta Vet Bras

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Heart rate, cardiac vagal tone, respiratory rate, and rectal temperature in dairy calves exposed to heat stress in a continental region

et al. 2018

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Changes in non-invasive stress biomarkers were studied in shaded (n = 8) and non-shaded (n = 8) Holstein bull calves exposed to extreme heat load conditions in a continental region. Ambient temperature and humidity data were recorded for the S and NS hutch and exercise pen environments. Temperature-humidity-index (THI) was also calculated. Respiratory rate, rectal temperature, heart rate, and the root mean square of successive differences between R-R intervals (RMSSD) were recorded as animal-based indicators during three periods: (1) day 1, control day, during which all calves were shaded for 24 h (shade removal from non-shaded calves at 2400 h); (2) day 2, heat stress day, with shade over shaded calves; and (3) days 3-5, post-stress period, with shade over shaded calves. On the heat stress day, the maximum temperatures were 44.3 and 46.7 °C for the non-shaded hutch and pen environments, respectively. The temperatures were with 6.2 and 6.9 °C (P = 0.015 and P = 0.008) and the THIs were with 5.9 and 4.2 units higher (P = 0.020 and P = 0.032) in the non-shaded than in the shaded environment for the hutch and exercise pen, respectively. Shaded calves had with 42.3 ± 3.2 breaths/min higher respiratory rate than non-shaded ones on the heat stress day at 1200 h (P = 0.001), which was moderated to 20.1 ± 2.4 breaths/min at 1600 h (P = 0.023). Significant differences in respiratory rate occurred earlier than in any other animal-based parameter between shaded and non-shaded calves on day 2. The only significant group difference in rectal temperature was found at 1200 h on day 2 when THI exceeded 91 units, with 0.59 °C higher values for non-shaded calves (P = 0.045). The heart rate on days 2 and 3 was higher for non-shaded calves than for shaded ones. Group differences were also significant at 0800 h (18.2 ± 1.2 beats/min, P = 0.008), 1200 h (22.3 ± 1.4 beats/min, P = 0.003), 1600 h (15.3 ± 0.8 beats/min, P = 0.012), and 2000 h (19.0 ± 1.1 beats/min, P = 0.010) on day 2. Following a rapid daytime reduction, RMSSD showed a nighttime overcompensation in non-shaded calves on day 3 (between 0000 and 0600 h) and day 4 (between 0000 and 0800 h), exceeding the levels recorded on day 1 (control) and the levels for shaded calves, thus suggesting a recovery of the autonomic nervous system from heat stress. Based on our results, shading effectively reduced heat stress as evidenced by heart rate and RMSSD in addition to traditional measures of heat stress. Respiratory rate and heart rates exhibited by non-shaded calves support that the well-being of pre-weaned calves can be impaired in continental regions during following a heat stress day without providing shade.

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Effect of time of day and type of shading on the physiological responses of crossbred calves in tropical environment

Cited by 6 publications

References 5 publications

Assessment of heat stress in 7-week old dairy calves with non-invasive physiological parameters in different thermal environments

Assessment of heat stress in 7-week old dairy calves with non-invasive physiological parameters in different thermal environments

Evaluation of Physiological Responses of Calves During Rainy Season in the Semiarid Environment

Heart rate, cardiac vagal tone, respiratory rate, and rectal temperature in dairy calves exposed to heat stress in a continental region

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