| There are many factors affecting the production level and health condition of growing pigs,and environmental temperature is considered to be one of the important factors.Developed countries have formed a complete set of process equipment,supporting specialized facilities and other supporting technologies to alleviate the impact of the thermal environment on pigs.As the Chinese pig industry has gradually become large-scale,intensive and technological in recent years,research on how to deal with the negative effects of heat stress has been carried out in many directions,such as feeding high-fat feeds,supplementing amino acids,adding anti-heat stress drugs,and improving resistant varieties.China’s measures to deal with the impact of the thermal environment have yet to be followed up,and there are few studies to deal with thermal environmental problems through temperature control technology.This experiment compares the effects of different cooling measures on pigs in summer climate through three common cooling facilities,and provides a theoretical basis for the selection of cooling measures for pig farms.In the experiment,the hybrid(Duroc ×Landrace × Large White)boar with the initial body weight(22.7±0.16)kg was selected as the research object,and 120 pigs of the same batch of test pigs were randomly divided into 3treatments,4 replicates for each treatment,and 10 pigs per replicate,and were housed in 3different cooling methods(fan,air-cooling fan,cooling pad-fan)in the pig house for 28 days,and observed the ambient temperature and humidity,production performance,blood biochemical indicators,etc.The results show:(1)Temperature and humidity:Different cooling measures have the effect of reducing the temperature inside the pig house.At the highest temperature of the day at noon,the fan group can be lowered by 2.5 °C,the air-cooling fan group can be lowered by 4.4 °C,and the cooling pad-fan group can be reduced by about 7.7 °C(P<0.05),the combination of wet curtain and negative pressure ventilation in the closed pig house greatly reduces the temperature and also improves the humidity in the pig environment.(2)Production performance:Different cooling methods will affect the growth performance of pigs.The ADG of the three groups of pigs were significantly different(P<0.05),and the pigs in the air-cooling fan group and the cooling pad-fan group were significantly higher than the fan group(P<0.01).The ADFI of the cooling pad-fan group was significantly higher than that of the fan group(P<0.05);the F/G of the three groups of pigs were significantly different(P<0.05),and the cooling pad-fan group was significantly higher than the fan group(P<0.01).(3)Biochemical indicators:Under the different cooling modes of summer pig houses,compared with the fan group,the AST of the air-cooling fan group has a downward trend(P>0.05),the ALT decreases significantly(P<0.05),and there is no significant difference in ALP and LDH;The ALP,AST,ALT and CK of the cooling pad-fan group all showed a downward trend(P>0.05),and there was no significant difference in LDH.The CK level of the cooling pad-fan group was significantly lower than that of the air-cooling fan group.(4)Antioxidant capacity:Compared with the air-cooling fan group,the T-SOD level of the fan group decreased significantly(P<0.05).(5)Immunity:Compared with the fan group,the T3 of the air-cooling fan group was significantly increased(P<0.01),the level of IL-6 was significantly decreased(P<0.05),and the level of TNF-α was significantly decreased(P<0.01).The level of TNF-α in the cooling pad-fan group decreased significantly(P<0.05),and the level of HSP70 in the air-cooling fan group was significantly lower than that in the cooling pad-fan group(P<0.05).According to the above measurement results,the growth performance of pigs in the wet curtain negative pressure fan unit is the best among the 3 groups.The cooling measures of the wet curtain negative pressure wind turbine and the cold air unit to a certain extent alleviate the influence of continuous hot climate on the immune function of growing pigs. |
