Transcriptional response of porcine skeletal muscle to feeding a linseed-enriched diet to growing pigs

Background： To investigate the effect of feeding a linseed-enriched diet to growing-finishing pigs on gene expression in skeletal muscle, pigs were fed with a linseed-enriched diet for 0, 30, 60 and 90 d. Transcriptional profiles of longissimus dorsi muscle were measured using Affymetrix Genechip.Results： Results showed that 264 genes were identified as differentially expressed genes（DEGs）. The strongest transcriptional response was clearly observed at 30 d. DEGs were assigned to several main functional terms,including transcription, apoptosis, intracellular receptor-mediated signaling, muscle organ development, fatty acid metabolic process, cell motion, regulation of glucose metabolic process, spermatogenesis and regulation of myeloid cell differentiation. We also found that transcriptional changs of several transcription cofactors might contribute to n-3 PUFAs regulated gene expression. In addition, the increased expression of IGF-1, insulin signaling pathway and the metabolism of amino acids might involve in the muscle growth induced by feeding a linseedenriched diet. The results also provide the new evidence that the expression changes of PTPN1, HK2 and PGC-1αmight contribute to the regulation of insulin sensitivity by n-3 PUFAs.Conclusions： Our finding provided correlative evidence that feeding the linseed enriched diet affact expression of genes involved in insulin signaling pathway and the metabolism of amino acids.

妊娠109d母猪背膘过厚导致脂毒性胎盘环境且使繁殖性能下降

研究探讨了妊娠109日龄母猪背膘厚对母猪和仔猪生产性能的影响。从种猪场收集了846头3~5胎次的经产大白母猪的相关数据。根据妊娠109 d时母猪的背膘厚(≤16,17~18,19~20,21~22,23~24和≥25 mm)分为6组。对母猪繁殖性能的评价包括窝产仔数、初生窝重和21日龄断奶窝重、分娩胎盘重、胎盘效率和母猪泌乳日采食量。测量与血脂和胎盘脂质浓度相关的参数,对数据进行分析,以确定背膘厚、胎盘脂质和仔猪性能之间的关系。各组间的出生仔猪数、产活仔猪数、寄养仔猪数和断奶仔猪数差异不显著(P> 0.05)。初生窝重和断奶窝重、仔猪初生重、断奶重、胎盘效率以及出生体重<800 g的仔猪数量和比例与背膘厚呈显著的二次效应(P> 0.05)。在泌乳期,母猪的日采食量在妊娠109 d时随背膘厚度的增加而线性降低(P> 0.05)。虽然甘油三酯和低密度脂蛋白胆固醇(LDL-C)无显著差异,但随着母猪背膘厚的增加,母猪和脐带血中胆固醇、高密度脂蛋白胆固醇(HDL-C)和游离脂肪酸(FFA)浓度均显著升高(P <0.05)。随着母猪背膘厚的增加,胎盘脂质浓度也显著增加(P <0.05)。此外,背膘厚和胎盘脂质浓度与体重<800 g的仔猪数呈正相关(P <0.01),而与初生重、窝产仔重和断奶仔猪重呈负相关(P <0.01)。综上所述,妊娠末期母猪背膘厚与仔猪出生和断奶体重相关。胎盘异位脂质堆积引起的脂毒性可能是造成这种相关性的原因。

Dynamic Frequency Support and DC Voltage Regulation Approach for VSC-MTDC Systems

When an additional frequency control is implemented in the voltage source converter-based multi-terminal high voltage direct current(VSC-MTDC)system,the DC grid is capable of responding to a frequency disturbance in the AC system.However,the original additional frequency control may cause the DC voltage to exceed the limit when providing power for a severe frequency disturbance,threatening the security of the DC system.A novel dynamic additional frequency control strategy for the VSC-MTDC system is developed based on the relationship between the DC voltage and the frequency droop coefficient.A dynamic frequency droop coefficient is designed to adaptively adjust the support power of the DC grid,balancing the frequency regulation of the disturbed AC system and the voltage stability of the DC grid.A DC voltage recovery method based on multi-converter cooperation is proposed to cope with the DC voltage deviation caused by the additional frequency control.Simulations validate the advantages and satisfactory performance of the proposed method during power disturbances with different severities and for the process of DC voltage recovery.

Optimizing feeding regimen of replacement gilts to improve their reproductive performance and retention rate of their first 2 parities

The effects of age,body weight(BW),and backfat thickness(BF)of replacement gilts at first estrus and first mating on their subsequent reproductive performance and retention of their first 2 parities as sows was evaluated.A total of 3,025 Danish replacement gilts were categorized by farm(allocated to 4 farms),cross combination,age,BW and BF at first estrus and first mating,estrous cycle number at first mating,and flush feeding before first mating.The result shows that all the factors mentioned above were significantly associated with reproductive performance and retention rates of the first 2 parities.Farm 3 had more piglets born alive per litter(BA)(P<0.05).Farms 3 and 4 had more healthy piglets per litter(HP)(P<0.05).Farm 4 had the most piglets weaned per litter(PW)(P<0.05).Landrace×Landrace×Yorkshire(L×L×Y)replacement gilts had the most total piglets born per litter(TB),BA,HP,PW and a higher retention rate of the 2 parities than Landrace×Yorkshire(L×Y)replacement gilts(P<0.05).In addition,flush feeding before first mating had the most TB,BA,HP,PW,and a higher retention rate of the 2 parities than no flush feeding(P<0.05).Because the effects of replacement gilts rearing parameters on reproductive performance traits differed,we used 100 replacement gilts as a unit and the total number of weaned piglets from the first 2 parities as a new index.Replacement gilts undergoing their first estrus between 180 and 210 d of age at 115 to 124.9 kg BW and 14 to 15 mm BF had significantly higher reproductive indexes for their first 2 parities per 100 replacement gilts.Replacement gilts that mated between 210 and 230 d of age at 140 to 149.9 kg BW and 15 to 16 mm BF had optimal reproductive indexes.These results provide a new insight into the complex relationships among these reproductive performance traits and may help guide successful management of replacement gilts as a pivotal starting point for future fertility and longevity of rearing herds.