***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Arginine is a common substrate for the synthesis of nitric oxide and polyamines that are crucial for placental angiogenesis and growth in mammals . This study was conducted to test the hypothesis that dietary l-arginine supplementation may improve reproductive performance of pregnant gilts . Fifty-two pregnant gilts with body weight ( BW ) of 166.3 + /- 1.8 kg were housed individually in gestation crates . At d 30 of gestation , gilts were assigned r and omly to corn-soybean-based diets supplemented with 1.0 % L-arginine-HCl or 1.7 % L-alanine ( isonitrogenous control ) . Both diets contained 13.0 MJ metabolizable energy/kg and 12.2 % crude protein and were fed to gilts at 1 kg twice daily during gestation . Backfat thickness and BW were measured and blood sample s were obtained on 30 , 70 , 90 , and 110 d of gestation . At d 110 of gestation , gilts were transferred to individual farrowing crates . The numbers of total piglets born and born alive , as well as birth weights of piglets , were recorded immediately after farrowing . Throughout the gestation , BW or backfat thickness of gilts did not differ between treatment groups . Plasma urea concentrations were lower in arginine-supplemented than in control gilts at d 90 ( P < 0.010 ) and d 110 ( P < 0.001 ) of gestation . Compared with the control group , arginine supplementation increased the number of pigs born alive by 22 % ( 11.40 vs. 9.37 , P = 0.032 ) and live litter birth weight of piglets by 24 % ( 16.38 vs. 13.19 kg , P = 0.016 ) . This exciting finding provides the first evidence for a marked increase of live-born piglets by 2 per litter through nutritional intervention in gilts The effects of l-arginine on porcine foetal development and myogenesis were determined . Twenty Swiss Large White gilts were r and omly allocated to either the control ( C ) or l-arginine treatment ( A ) . In addition to the st and ard gestation diet , A-sows received 26 g l-arginine daily from days 14 to 28 of gestation . At day 75 of pregnancy , sows were sacrificed and the number and weight of foetuses were recorded . From each litter , the lightest , heaviest and the ones with an average foetal weight ( FtW ) were selected . Primary ( P ) , secondary ( S ) and total myofiber number as well as S/P ratio were determined in the semitendinosus ( ST ) and rhomboideus ( RH ) muscles . In A-sows , the number of viable foetuses ( 13.0 v. 9.3 ) and total FtW ( 4925 v. 3729 g ) was greater ( P ⩽ 0.04 ) than in C-sows . Compared to C-sow foetuses , the ST of A-sow foetuses had 7 % more ( 17 699 v. 16 477 ; P = 0.04 ) P myofibers and the S/P ratio in both muscles was lower ( ST = 20.3 v. 21.5 ; RH = 24.1 v. 27.1 ; P ⩽ 0.07 ) . Regardless of the maternal diet , the S myofiber number and the S/P ratio in both muscles were greater ( P ⩽ 0.01 ) in foetuses with a high FtW compared to low FtW. These data suggest that l-arginine supplemented to gilts during early gestation enhanced foetal survival and in the ST positively affected the primary phase of myofiber formation Placental vascular formation and blood flow are crucial for fetal survival , growth and development , and arginine regulates vascular development and function . This study determined the effects of dietary arginine or N-carbamylglutamate ( NCG ) supplementation during late gestation of sows on the microRNAs , vascular endothelial growth factor A ( VEGFA ) and endothelial nitric oxide synthase ( eNOS ) expression in umbilical vein . Twenty-seven l and race × large white sows at day ( d ) 90 of gestation were assigned r and omly to three groups and fed the following diets : a control diet and the control diet supplemented with 1.0 % l-arginine or 0.10 % NCG .  Umbilical vein of fetuses  with body weight around 2.0 kg ( oversized ) , 1.5 kg ( normal ) and 0.6 kg ( intrauterine growth restriction , IUGR ) were obtained immediately after farrowing for miR-15b , miR-16 , miR-221 , miR-222 , VEGFA and eNOS real-time PCR analysis . Compared with the control diets , dietary Arg or NCG supplementation enhanced the reproductive performance of sows , significantly increased ( P < 0.05 ) plasma arginine and decreased plasma VEGF and eNOS ( P < 0.05 ) . The miR-15b expression in the umbilical vein was higher ( P < 0.05 ) in the NCG-supplemented group than in the control group . There was a trend in that the miR-222 expression in the umbilical vein of the oversized fetuses was higher ( 0.05 < P < 0.1 ) than in the normal and IUGR fetuses . The expression of eNOS in both Arg-supplemented and NCG-supplemented group were lower ( P < 0.05 ) than in the control group . The expression of VEGFA was higher ( P < 0.05 ) in the NCG-supplemented group than in the Arg-supplemented and the control group . Meanwhile , the expression of VEGFA of the oversized fetuses was higher ( P < 0.05 ) than the normal and IUGR fetuses . In conclusion , this study demonstrated that dietary Arg or NCG supplementation may affect microRNAs ( miR-15b , miR-222 ) targeting VEGFA and eNOS gene expressions in umbilical vein , so as to regulate the function and volume of the umbilical vein , provide more nutrients and oxygen from the maternal to the fetus tissue for fetal development and survival , and enhance the reproductive performance of sows Suboptimal embryonic/fetal survival and growth remains a significant problem in mammals . Using a swine model , we tested the hypothesis that dietary l-arginine supplementation during gestation may improve pregnancy outcomes through enhancing placental growth and modulating hormonal secretions . Gestating pigs ( Yorkshire × L and race , n = 108 ) were assigned r and omly into two groups based on parity and body weight , representing dietary supplementation with 1.0 % l-arginine – HCl or 1.7 % l-alanine ( isonitrogenous control ) between days 22 and 114 of gestation . Blood sample s were obtained from the ear vein on days 22 , 40 , 70 and 90 of gestation . On days 40 , 70 and 90 of gestation , concentrations of estradiol in plasma were higher ( P < 0.05 ) in arginine-supplemented than in control sows . Moreover , arginine supplementation increased ( P < 0.05 ) the concentrations of arginine , proline and ornithine in plasma , but concentrations of urea or progesterone in plasma did not differ between the two groups of sows . Compared with the control , arginine supplementation increased ( P < 0.05 ) the total number of piglets by 1.31 per litter , the number of live-born piglets by 1.10 per litter , the litter birth weight for all piglets by 1.36 kg , and the litter birth weight for live-born piglets by 1.70 kg . Furthermore , arginine supplementation enhanced ( P < 0.05 ) placental weight by 16.2 % . The weaning-to-estrus interval of sows was not affected by arginine supplementation during gestation . These results indicate that dietary arginine supplementation beneficially enhances placental growth and the reproductive performance of sows The present study characterised gene expression associated with embryonic muscle development and placental vascularisation during early gestation in the pig and examined effects of Progenos supplementation in early pregnancy . Tissues were collected from commercial multiparous sows ( n = 48 ) from Days 16 to 49 of gestation . In the placenta , qPCR revealed that vascular endothelial growth factor ( VEGFA ) expression did not change from Day 17 to 49 of gestation ; however , KDR receptor and angiopoietin-1 and -2 expression were differentially regulated , with periods of high expression corresponding to two critical phases of angiogenesis in the pig . In the embryo , the pattern of myogenesis-related gene expression was consistent with available literature . A commercially available nutritional supplement Progenos ( 20 g day⁻¹ L-arginine ) added to the diet of sows from either Day 15 to 29 ( P15 - 29 ; n = 33 ) , Day 30 to 44 ( n = 29 ) or from Day 15 to 44 ( n = 76 ) of gestation tended to increase ( P = 0.058 ) embryonic growth rate compared with non-supplemented controls ( n = 79 ) and angiogenin expression was higher ( P = 0.028 ) at Day 30 of gestation in placentae from sows on the P15 - 29 Progenos treatment . These results are consistent with proposed beneficial effects of l-arginine on early embryonic development and placental vascularisation A 2 x 2 factorial arrangement of treatments in a r and omized block design was used to determine the effects of dietary Arg supplementation during gestation and lactation on the lactation performance of 38 first-parity sows . At 30 d of gestation , pregnant gilts were allotted based on BW to 1 of 2 diets supplemented with 1 % L-Arg . HCl or 1.7 % L-Ala ( isonitrogenous control ) . After farrowing , sows were further allotted based on BW within previous gestation treatment groups to 1 of 2 lactation diets supplemented with 1 % L-Arg . HCl or 1.7 % L-Ala ( isonitrogenous control ) . All gestation diets contained 3.1 Mcal/kg and 12.2 % CP ( as is ) and were fed 2 kg/d in 2 equally sized meals , whereas all lactation diets contained 3.2 Mcal/kg and 18.6 % CP ( as is ) and were fed ad libitum . Litter size was st and ardized to 10 piglets by cross-fostering within 24 h postfarrowing . On a weekly basis , BW and backfat ( BF ) thickness of sows , as well as piglet BW were measured , and blood and milk sample s were obtained from the sows . Number of days from weaning to estrus and ADFI were also recorded . There were no differences in BW , BF thickness , ADFI , or days until return to estrus among treatment groups . There was no effect of the gestation diet or a gestation x lactation diet interaction on any parameter measured . On d 7 of lactation , plasma concentrations of Arg and insulin in sows , as well as concentrations of most AA in milk , were greater ( P < 0.05 ) in response to Arg supplementation during lactation compared with the control . Weight gain of piglets from sows fed the Arg-supplemented diet during lactation was greater between d 0 and 7 ( P < 0.01 ) and between d 0 and 21 ( P < 0.05 ) of lactation compared with piglets from sows fed the control diet . Collectively , results from this study indicate the potential beneficial effects of dietary Arg supplementation in improving the lactation performance of first-parity sows Preweaning piglet mortality is largely attributed to the incidence of low birth weight and birth weight variation within the litter . Therefore , developing strategies to increase within-litter uniformity of piglet birth weight is important . This study investigated the effects of different feeding strategies based on specific nutrient supplies in sow diet on the within-litter variation of piglet birth weight ( BW0 ) .  Four batches of highly prolific crossbred L and race × Large White sows were used . Three dietary treatments were compared : supplies of dextrose during the week before insemination ( 190 g/d ) and of L-arginine ( 25.5 g/d ) from d 77 of pregnancy until term ( DEXA , n = 26 ) ; a dietary supplementation of L-arginine only ( 25.5 g/d ) , from d 77 of pregnancy until term ( ARGI , n = 24 ) ; and no supplementation to a st and ard gestation diet ( CTL ; n = 23 ) . Total born piglets ( TB ) , i.e. , piglets born alive ( BA ) and stillborn piglets , were numbered and weighed at birth and at weaning . Data were analyzed by ANOVA using the MIXED procedure in a model that included dietary treatment ( ARGI , DEXA , and CTL ) , initial parity ( 1 , 2 and 3 , 4 , and more 
    Output:
    
It is concluded that supplementing dietary arginine in gestating sows can benefit embryo survival and foetal development .