Earth tempering of stable air has attracted great attention as a sustainable air conditioning method in pig houses. At summer time air cooling of income air strongly reduces heat stress and required ventilation rate. ...Earth tempering of stable air has attracted great attention as a sustainable air conditioning method in pig houses. At summer time air cooling of income air strongly reduces heat stress and required ventilation rate. At winter time heating costs can be reduced. The effect of air condition using geothermal energy was investigated in a farrowing house. Underneath the foundation of the farrowing house 88 non perforated ribbed tubes （diameter： 20 cm） were piped in a depth of 1.6-2.0 m. Over a period of 12 month following data were recorded at hourly intervals and analyzed： outside air temperature, as well as air temperature in the air supply duct and in the compartments. Incoming air （supply duct） was heated up to 20 ℃ during winter time and in summer time cooled by up to 15 ℃ compared to the outside air temperature. In contrast to the outside air diurnal variation, temperature fluctuations of the incoming air were reduced by 90%. Due to cooling of the incoming air at summer time the stable inside temperature could be limited to maximal 29 ℃（maximum outside temperature was 35℃）. Earth-tube heat exchangers with non perforated ribbed tubes were very efficient for air conditioning in farrowing houses. They were a cost effective supplement for sustainable cooling and heating of farrowing houses.展开更多
[ Objective ] To study the influence of sows farrowing performance on the growth of 21-day-old weaned piglets and their correlation. [ Methods ] A total of 1 350 Duroc x Landrace Yorkshire piglets produced by 2-6 fet...[ Objective ] To study the influence of sows farrowing performance on the growth of 21-day-old weaned piglets and their correlation. [ Methods ] A total of 1 350 Duroc x Landrace Yorkshire piglets produced by 2-6 fetal Landrace x Yorkshire sows from 118 litters within a month were selected to be the test objects. All the newborn piglets were lactated by their parent sows. The test groups were divided according to different numbers （6 - 17） of live birth. The variance analysis were conducted on birth weight, litter weight at birth, number of 21-day-old weaning piglets, weaning weight, weaninl2g weight of litter, weaning survival rate and relative individual weight gain among different weeks. [ Results] Sows farrowing performance had significant influence on the growth performance of 21- day-old piglets. However, the influences among different traits varied, some were even on the contrary. With the increase of the number of live birth, the birth weight, weaning weight of litter and weaning survival rate showed a decline trend. And when the number of live birth was equal or more than 14, the weaning sur- vival rate dropped to below 90% （P 〈 0.01 ） ; when the number of live birth was 13, the litter weight at birth and weaning weight of litter reached the peak. What- ever the number of live birth increased or decreased, the weaning weight showed a regular decline trend. [ Conclusions] When the number of live birth changed from 11 to 13, the maximum values of the economic indicator （weaning weight of litter） and the technical specifications （weaning survival rate） were achieved.展开更多
This study investigated the effects of isomaltooligosaccharide(IMO)and Bacillus in perinatal diets on the duration of farrowing and post-weaning estrus,serum reproductive hormone concentrations,and gut microbiota and ...This study investigated the effects of isomaltooligosaccharide(IMO)and Bacillus in perinatal diets on the duration of farrowing and post-weaning estrus,serum reproductive hormone concentrations,and gut microbiota and its metabolites of sows.Multiparous sows(n=130)were fed diets without IMO(control,CON group),or diets containing only IMO(IMO group),IMO and Bacillus subtilis(IMOS group),IMO and Bacillus licheniformis(IMOL group),and IMO and B.subtilis and B.licheniformis(IMOSL group),respectively.The results indicate that the duration of farrowing and post-weaning estrus was shorter in sows in the IMOS,IMOL,and IMOSL groups,and the weaning-estrous interval was lower in sows in the IMOL greoup.In addition,the lowest fecal score was observed in the IMOL group during d 106 to 112 of gestation.Sows in most of the treatment groups had a higher concentration of serum prolactin and prostaglandin at farrowing,but a lower serum concentration of estradiol,oxytocin,and progesterone on d 18 of lactation than sows in the CON group.The treatment groups had a higher abundance of Candidatus Methanoplasma and Bacillus and a lower abundance of Escherichia-Shigella in their feces at farrowing.Furthermore,the treatment groups had higher concentrations of total short-chain fatty acids(SCFA)in feces at farrowing and a higher concentration of branched fatty acids in feces on d 18 of lactation.Furthermore,the abun-dance of Bacillus in feces was positively correlated with serum prostaglandin concentrations and fecal total SCFA of sows at farrowing,but was negatively correlated with the duration of farrowing.Overall,dietary IMO and Bacillus supplementation affected the concentration of serum reproductive hormones and the duration of farrowing and post-weaning estrus,and the gut microbiota is a key factor.展开更多
The hot and humid climates,as encountered in the southern region of China with the open housing,can adversely impact the sows undergoing heat stress during the most vulnerable period at lactation.Hence,a water-cooled ...The hot and humid climates,as encountered in the southern region of China with the open housing,can adversely impact the sows undergoing heat stress during the most vulnerable period at lactation.Hence,a water-cooled cover system(WCCs)for local cooling has essential practical value to improve productivity.The WCCs was developed for the sow crate of lactating sows separately,which performance was validated with the cooling efficiency in the sow occupied zone(SOZ)and physiological parameters.The results showed that the WCCs for the farrowing sows using aluminium plastic tubes connected in series could reach an appropriate cooling performance in adjacent units.The WCCs could decrease the SOZ air temperature by 3.0-4.5℃under the extremely hot climate when the indoor air temperature was 37℃,and maintain a suitable range(25-30℃)under the typical hot climate(<35℃).The respiration rate and skin temperature of farrowing sows had no significant difference between treatment group(WCC)and control group(sprinkle cooling)when the air temperature was below 30℃,but had a significant difference(p<0.05)when air temperature rose above 30℃.The control sows drank more during hot weather,and the feed intake was significantly lower than the sows with the WCCs(p<0.01).It was concluded that the WCCs could alleviate the heat stress of farrowing sows during typical hot climate.展开更多
针对基于Farrow结构的可变分数时延(Variable fractional delay,VFD)滤波器需求解大量子滤波器系数这一关键问题,本文将稀疏约束理论引入滤波器的权系数优化中,研究具有稀疏系数的Farrow结构滤波器。在极大极小(Minimax)准则下,通过添...针对基于Farrow结构的可变分数时延(Variable fractional delay,VFD)滤波器需求解大量子滤波器系数这一关键问题,本文将稀疏约束理论引入滤波器的权系数优化中,研究具有稀疏系数的Farrow结构滤波器。在极大极小(Minimax)准则下,通过添加L1正则化约束项改进权系数优化模型,在系数(反)对称性基础上进一步增加系数的稀疏度。然后,采用交替方向乘子法(Alternating direction method of multipliers,ADMM)进行权系数迭代求解。仿真实验表明,本文提出的基于稀疏约束的VFD滤波器在保证高延迟精度的同时,乘法器和加法器分别减少了47.69%和58.60%,极大地降低了系统运算量以及复杂度。展开更多
文摘Earth tempering of stable air has attracted great attention as a sustainable air conditioning method in pig houses. At summer time air cooling of income air strongly reduces heat stress and required ventilation rate. At winter time heating costs can be reduced. The effect of air condition using geothermal energy was investigated in a farrowing house. Underneath the foundation of the farrowing house 88 non perforated ribbed tubes （diameter： 20 cm） were piped in a depth of 1.6-2.0 m. Over a period of 12 month following data were recorded at hourly intervals and analyzed： outside air temperature, as well as air temperature in the air supply duct and in the compartments. Incoming air （supply duct） was heated up to 20 ℃ during winter time and in summer time cooled by up to 15 ℃ compared to the outside air temperature. In contrast to the outside air diurnal variation, temperature fluctuations of the incoming air were reduced by 90%. Due to cooling of the incoming air at summer time the stable inside temperature could be limited to maximal 29 ℃（maximum outside temperature was 35℃）. Earth-tube heat exchangers with non perforated ribbed tubes were very efficient for air conditioning in farrowing houses. They were a cost effective supplement for sustainable cooling and heating of farrowing houses.
文摘[ Objective ] To study the influence of sows farrowing performance on the growth of 21-day-old weaned piglets and their correlation. [ Methods ] A total of 1 350 Duroc x Landrace Yorkshire piglets produced by 2-6 fetal Landrace x Yorkshire sows from 118 litters within a month were selected to be the test objects. All the newborn piglets were lactated by their parent sows. The test groups were divided according to different numbers （6 - 17） of live birth. The variance analysis were conducted on birth weight, litter weight at birth, number of 21-day-old weaning piglets, weaning weight, weaninl2g weight of litter, weaning survival rate and relative individual weight gain among different weeks. [ Results] Sows farrowing performance had significant influence on the growth performance of 21- day-old piglets. However, the influences among different traits varied, some were even on the contrary. With the increase of the number of live birth, the birth weight, weaning weight of litter and weaning survival rate showed a decline trend. And when the number of live birth was equal or more than 14, the weaning sur- vival rate dropped to below 90% （P 〈 0.01 ） ; when the number of live birth was 13, the litter weight at birth and weaning weight of litter reached the peak. What- ever the number of live birth increased or decreased, the weaning weight showed a regular decline trend. [ Conclusions] When the number of live birth changed from 11 to 13, the maximum values of the economic indicator （weaning weight of litter） and the technical specifications （weaning survival rate） were achieved.
基金funding from Double first-class construction project of Hunan Agricultural University(SYL201802009,SYL201802015)the National Key Research and Development Program of China(2017YFD0500506,2016YFD0501209).
文摘This study investigated the effects of isomaltooligosaccharide(IMO)and Bacillus in perinatal diets on the duration of farrowing and post-weaning estrus,serum reproductive hormone concentrations,and gut microbiota and its metabolites of sows.Multiparous sows(n=130)were fed diets without IMO(control,CON group),or diets containing only IMO(IMO group),IMO and Bacillus subtilis(IMOS group),IMO and Bacillus licheniformis(IMOL group),and IMO and B.subtilis and B.licheniformis(IMOSL group),respectively.The results indicate that the duration of farrowing and post-weaning estrus was shorter in sows in the IMOS,IMOL,and IMOSL groups,and the weaning-estrous interval was lower in sows in the IMOL greoup.In addition,the lowest fecal score was observed in the IMOL group during d 106 to 112 of gestation.Sows in most of the treatment groups had a higher concentration of serum prolactin and prostaglandin at farrowing,but a lower serum concentration of estradiol,oxytocin,and progesterone on d 18 of lactation than sows in the CON group.The treatment groups had a higher abundance of Candidatus Methanoplasma and Bacillus and a lower abundance of Escherichia-Shigella in their feces at farrowing.Furthermore,the treatment groups had higher concentrations of total short-chain fatty acids(SCFA)in feces at farrowing and a higher concentration of branched fatty acids in feces on d 18 of lactation.Furthermore,the abun-dance of Bacillus in feces was positively correlated with serum prostaglandin concentrations and fecal total SCFA of sows at farrowing,but was negatively correlated with the duration of farrowing.Overall,dietary IMO and Bacillus supplementation affected the concentration of serum reproductive hormones and the duration of farrowing and post-weaning estrus,and the gut microbiota is a key factor.
基金the National Natural Science Foundation of China(Grant No.31302011).
文摘The hot and humid climates,as encountered in the southern region of China with the open housing,can adversely impact the sows undergoing heat stress during the most vulnerable period at lactation.Hence,a water-cooled cover system(WCCs)for local cooling has essential practical value to improve productivity.The WCCs was developed for the sow crate of lactating sows separately,which performance was validated with the cooling efficiency in the sow occupied zone(SOZ)and physiological parameters.The results showed that the WCCs for the farrowing sows using aluminium plastic tubes connected in series could reach an appropriate cooling performance in adjacent units.The WCCs could decrease the SOZ air temperature by 3.0-4.5℃under the extremely hot climate when the indoor air temperature was 37℃,and maintain a suitable range(25-30℃)under the typical hot climate(<35℃).The respiration rate and skin temperature of farrowing sows had no significant difference between treatment group(WCC)and control group(sprinkle cooling)when the air temperature was below 30℃,but had a significant difference(p<0.05)when air temperature rose above 30℃.The control sows drank more during hot weather,and the feed intake was significantly lower than the sows with the WCCs(p<0.01).It was concluded that the WCCs could alleviate the heat stress of farrowing sows during typical hot climate.
文摘针对基于Farrow结构的可变分数时延(Variable fractional delay,VFD)滤波器需求解大量子滤波器系数这一关键问题,本文将稀疏约束理论引入滤波器的权系数优化中,研究具有稀疏系数的Farrow结构滤波器。在极大极小(Minimax)准则下,通过添加L1正则化约束项改进权系数优化模型,在系数(反)对称性基础上进一步增加系数的稀疏度。然后,采用交替方向乘子法(Alternating direction method of multipliers,ADMM)进行权系数迭代求解。仿真实验表明,本文提出的基于稀疏约束的VFD滤波器在保证高延迟精度的同时,乘法器和加法器分别减少了47.69%和58.60%,极大地降低了系统运算量以及复杂度。
