Journal of Animal Behaviour and Biometeorology
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Assessment of testis histopathological changes and spermatogenesis in male mice exposed to chronic scrotal heat stress
Tung Nguyen Thanh, Phuoc Dang Van, Thuan Dang Cong, Tam Le Minh, Quoc Huy Nguyen Vu
Elevation of scrotal temperature may be injurious to spermatogenesis and leading cause male infertility. Scrotal heat stress reduces the number and motility of spermatozoa, fertilization ability of the surviving sperm and poor fertilization-embryo. This study was designed to investigate the effect of heat stress (at 37 °C, 40 °C and 43 °C) on histopathological features of testicular tissue in scrotal heat exposed male mice. Experimental and control groups were sacrificed after completion of five weeks heat exposure period. The testes were fixed and stained hematoxylin-eosin (H&E) for qualitative and quantitative analysis of histopathological alterations and spermatogenesis according to Johnson scoring system. The results indicated that mice exposed to heat-stress mice exhibited degenerated and disorganized features of spermatogenic epithelium and reduced spermatogenic cells. Heat stress exposure (40 °C and 43 °C) shows the significantly reduced Johnson score compared to the control condition (P < 0.05 and P < 0.001, respectively). Meanwhile, scrotal heat exposure at 37 °C did not reach significantly changes in Johnsen’s testicular histopathological score. The seminiferous tubule structure and spermatogenesis were completely disrupted in mice exposed to 43 °C. Percentage of high Johnsen score point was decreased in mice in heat-stress exposure group, while the ratio of low Johnsen score points was gradually increase. Spermatogenesis in male mice exposed to chronic scrotal heat stress is disrupted at 43 °C. In conclusion, this study attempted to develop an animal model for studying the male reproductive system. Johnsen scores system was standardized to assess murine testicular histopathology in the seminiferous tubule cross-section. Collectively, these results indicated a negative impact on histopathological alterations and spermatogenesis arrest following chronic scrotal heat stress.
Effect of wetting method on the broiler transport in Brazilian Northeast
Daniel Gurgel Pinheiro, José Antonio Delfino Barbosa Filho, Nítalo André Farias Machado
The aim of this study was to evaluate the efficiency of the load wetting method to attenuate the ambience of the load the transport of broilers. Fourteen commercial consignments were monitored over a 25 km route, and in seven of these, the load wetting was carried (LW) out while in the other seven no wetting was done (LD). The temperatures of the side, top and rear load boxes were analyzed by infrared thermography. The central row load boxes were evaluated by geostatistics, using temperature variability (TA), relative humidity (RH) and the enthalpy comfort index (ECI). The mean was compared by Student's t-test (P < 0.05). The results showed that load wetting has a momentary effect (P < 0.05). The boxes located in the central rows in the LW showed a higher (P < 0.05) ECI compared to those in the LD. In addition, areas classified as lethal were formed in the LW. In conclusion, load wetting was not an efficient method to attenuate the ambience of load during the commercial transport of broilers, as it only has momentary and transient effects.
Temperature effect on the maximum swimming speed of jack mackerel Trachurus japonicus through muscle contraction monitoring
Nofrizal, Farhan Ramdhani, Takafumi Arimoto
The purpose of this study is to know the effect of temperature on fish muscle contraction of jack mackerel (Trachurus japonicus), which muscle contraction will determine the tail beat frequency and maximum swimming speed. The maximum swimming speed of was evaluated according to the measurement of the muscle contraction time with electric stimuli of 2-7 V, 50 ms. Fish were separated into four groups for temperature acclimation at 10, 15, 18 and 22 °C to reflect typical changes in seasonal water temperature in Japan. Results showed that the swimming speed of the fish was positively related to the tail-beat frequency at all temperatures. The muscle contraction time was also affected by the acclimated temperature, which longer at the lower temperature than higher ones. Mean contraction time (Tm) was 45.1 ms at 10 °C, 32.7 ms at 15 °C, 32.9 ms at 18 °C, and 31.9 ms at 22 °C, respectively. The mean of maximum tail-beat frequency (Fmax) obtained from Fmax = ½ Tm was 11.4 Hz at 10 °C, 15.8 Hz at 15 °C, 16,4 Hz at 18 °C, and 16.6 Hz at 22 °C. These were used to estimate the maximum swimming speed (Umax) at each temperature, resulting in 9.45 FL s-1 at 10 °C, 13.5 FL s-1 at 15 °C, 14.0 FL s-1 18 °C, and 14.2 FL s-1 at 22 °C. The seasonal temperature effects on the swimming performance of T. japonicus, which lower water temperature in the winter made low swimming performance.