| The ambient temperature,humidity,wind speed and solar radiation constituted the domestic thermal environment.In order to alleviate the degree of heat stress,the cattle industry pays more attention to housing microclimate environment regulation.On the basis of the air flow ventilation system is not affected by the humid climate control characteristics,design the profile cross ventilated,in order to improve the production of beef cattle in southern summer thermal environment.1.The thermal environment of the shed and thermoregulatory response of the Simmental and its hybrid cattle to add the profile cross ventilatedThis study was to investigate the thermal environment of the shed and thermoregulatory response of the Simmental and its hybrid cattle to add the profile cross ventilated.Simultaneous selection of Simmental and its hybrids were carried out in the barn with the profile cross ventilated.The summer was similar to the high temperature condition;the fan was used as the control group.There were no significant differences in temperature,humidity and wind speed between the treatment group and the control group.Every group lasted 7 days.The opening time of the fan was 8:00-19:00 every day during the whole test period.We measured the environmental and physiological indicators at 10:00,14:00 and 18:00 every day.The results showed that the wind speed of the treatment group was significantly higher than the control group,above 1.9 m/s(P<0.01),and the temperature humidity velocity index was significantly lower than the control group 1.39,1.51 and 2.50?(P<0.01).At 10:00,14:00 and 18:00,the respiration rate the treatment group was lower than the control group 8,9 and 10rr/min,the respiration rate of the Simmental was 11,12 and 12 rr/min,the skin temperature of hybrid cattle was lower than the control group 0.52,0.46 and 0.36?,the skin temperature of Simmental was lower than the control group 0.28,0.68 and 0.56 ?,the rectal temperature of hybrid cattle was lower than the control group 0.08,0.14 and 0.12 ?,the rectal temperature of Simmental was lower than the control group 0.18,0.15 and 0.20?(P<0.05).2.The thermal environment of the shed and thermoregulatory response of the Jinjiang cattle in two wind supply modesThis study was to investigate the thermal environment of the shed and thermoregulatory response of the Jinjiang cattle in two wind supply modes.Choose two similar size of the barn,divided into the profile cross ventilated group and the longitudinal relay group.Respectively,we selected 10 healthy adult Jinjiang cattle as the experimental livestock.At 10:00,14:00 and 18:00 time were measured environmental and physiological indicators,the test period for 6 days.The results show that the wind speed of the two groups was significantly higher than outside the barn(P<0.01),the ambient temperature,the temperature and humidity index,wind speed and relative humidity in the longitudinal and lateral groups was not significant;On the second day at 14:00,the profile cross ventilated group Jinjiang cattle the respiration rates was significantly higher than the longitudinal relay group(P<0.05),other time periods was not significant;On the first day at 14:00,on the third day at 18:00 and on the fifth day at 10:00,the profile cross ventilated group Jinjiang cattle skin temperature was significantly higher than the longitudinal relay group(P<0.05),on the sixth day,the longitudinal relay group Jinjiang cattle skin temperature was significantly higher than the profile cross ventilated group(P<0.05),other time periods was not significant;On the third day at 18:00,the profile cross ventilated group Jinjiang cattle rectal temperature was significantly higher than the longitudinal relay group(P<0.05).3.The thermal environment of the shed and thermoregulatory response of the Jinjiang cattle in two wind supply systemThis experiment was mainly discussed that the thermal environment of the shed and thermoregulatory response of the Jinjiang cattle in two winds supply system.The test was divided into two phases,the first was randomly selected Jinjiang cattle 10 in the house with the profile cross ventilated barn,and numbered.In the summer,similar to the high temperature conditions to daytime 08:00-18:00 when the fan for the daytime wind supply group to 08:00-18:00,19:00-07:00 fan for the full day wind supply group,two the test period was 7 days.There were no significant differences in outdoor temperature,relative humidity and wind speed between the two groups during test period.The environmental indicators and physiological indexes were measured at 10:00,14:00,18:00,22:00,02:00,02:00 and 06:00,respectively.The seconc phase was choose 8 Jinjiang cattle with similar age and weight the average weight of(430.5 ± 16.18)kg,which was randomly divided into two groups,each group of 4,tied for feeding.We divided into daytime wind supply group and full day wind supply group.Pre-feeding for two days,the official test for 15 days,a total of 17 days.At the beginning and the end of two consecutive morning fasting weighing,the average value set as the begin weight and the end weight,respectively.The daily dietary intake was recorded to feed the same diets during the test period.The results show that:(1)There was no significant difference in the ambient temperature between the daytime air supply group and the full day wind supply group at 22:00,02:00,06:00,10:00,14:00 and 18:00 during the first test period(P>0.05).At 22:00,02:00 and 06:00,the full day wind supply group was significantly lower than the daytime wind supply group 2.48,2.50,2.51?(P<0.01),and the wind speed was significantly higher than the daytime(P<0.01).The wind speed and temperature humidity velocity index of daytime wind supply group were not significantly different from those of daytime wind supply group at 10:00,14:00 and 18:00(P>0.05).The respiration rate and shin temperature of full day wind supply group of Jinjiang cattle was significantly lower than daytime wind supply group at 16,14,8 and 5 rr/min at 22:00,02:00,06:00 and 10:00(P<0.05).At 22:00 and 02:00,the rectal temperature was significantly lower than the full day wind supply group 0.10 and 0.16?(P<0.05).(2)The daily gain and total dry matter intake of Jinjiang cattle were increased by 26%and 3%,respectively,compared with the daytime wind supply group,but there was no significant(P>0.05)while the feed meat ratio was significant difference between two groups(P<0.05).As stated above,the conclusions are as follow:(1)The profile cross ventilated can reduce the ambient temperature of the shed,improve wind speed,significantly reduce respiration rates,skin temperature and rectal temperature of the cattle,to ease the impact of high temperature on beef cattle;Under the heat stress condition,the hybrid cattle had lower body temperature,and the hybrid cattle of Jinjiang as female parent had the heat resistance to adapt to the high temperature environm ent in summer.(2)When the high temperature was above 33?,the profile cross ventilated group and the longitudinal relay group con,Jinjiang cattle body temperature is not more than 39 ?critical body temperature,the increase respiration rates hints that Jinjiang cattle has evaporative heat loss characteristics;In the high temperature above 33 ? in the daytime,Air humidity less than 70%,Jinjiang cattle can express body temperature rhythm.(3)Compared with daytime wind supply,full day wind supply can reduce THVI at night,improve wind speed,significantly reduce the Jinjiang cattle respiration rates,skin temperature and rectal temperature,Increase body temperature difference;Full day wind supply can improve the feed utilization of Jinjiang cattle. |
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