Dietary supplementation with lysine (protein) in late pregnancy does not enhance mammary development in multiparous sows.

This project was conducted to determine if providing standardized ileal digestible (SID) Lys at 40% above estimated requirements (NRC, 2012), with the concomitant increased protein intake, from days 90 to 110 of gestation stimulates mammary development in multiparous sows. From day 90 of gestation, Yorkshire × Landrace multiparous sows (parities 2 and 3) were fed 2.6 kg/d of either a conventional diet (CTL, control, n = 17) providing 14.8 g/d of SID Lys or a diet providing 20.8 g/d of SID Lys via additional soybean meal (HILYS, n = 16). The diets were isoenergetic. Concentrations of IGF-1, glucose, free fatty acids (FFA), urea, and amino acids (AA) were measured in jugular blood samples obtained on days 90 and 110 of gestation. Sows were necropsied on day 110 ±â€…1 of gestation to obtain mammary glands for compositional and histological analyses. Backfat or BW changes of sows during late gestation were unaffected by treatment (P > 0.10), as was the case for fetal BW (P > 0.10). None of the variables measured in mammary tissue were altered by supplementary Lys (P > 0.10). Circulating IGF-1, glucose, and FFA did not differ (P > 0.10) between HILYS and CTL sows on day 110 of gestation, whereas concentrations of urea were greater (P < 0.01) in HILYS versus CTL gilts. Concentrations of Ile and Thr in plasma were also greater (P < 0.05), and those of Glu were lower (P < 0.01) in HILYS than CTL sows. These results demonstrate that feeding Lys (via protein) above current NRC recommendations during late gestation does not improve mammary development of multiparous sows. Hence, the use of a two-phase feeding strategy to provide more Lys (protein) to multiparous sows during this period is not necessary.

Results indicate that there is no advantage in terms of mammary development to feeding late-pregnant multiparous sows with 40% more lysine (via protein) than current recommendations (NRC, 2012). From days 90 to 110 of gestation, multiparous sows (parities 2 and 3) were fed 2.6 kg/d of either a conventional diet providing 14.8 g/d of standardized ileal digestible (SID) lysine or a diet providing 20.8 g/d of SID lysine via the inclusion of additional soybean meal. Diets were isoenergetic. Feeding supplementary SID lysine had no effect on mammary development at the end of gestation. Contrary to our previous report for gilts, mammary gland development is not improved by providing more lysine to multiparous sows in late gestation. Such information is crucial for developing the best feeding strategies to maximize milk yield. The use of a two-phase feeding strategy to provide more lysine (protein) as of day 90 of gestation is not necessary in multiparous sows.

Comparative efficacy of a novel Bacillus subtilis-based probiotic and pharmacological zinc oxide on growth performance and gut responses in nursery pigs.

In this study, we assessed the efficacy of a novel Bacillus subtilis probiotic in improving growth performance and gut responses in comparison to pharmacological zinc oxide (ZnO) in nursery pigs. A total of 96 piglets were randomly assigned to four groups: Negative control (NC), Positive control (PC, 3000 mg Zn /kg feed), B.subtilis low dose (BS9-L, 2 × 107 CFU/pig) and B.subtilis high dose (BS9-H, 2 × 109 CFU/pig). Growth performance, diarrhea rate, gut mucosal gene expression and fecal microbial populations were evaluated. B.subtilis administration did not improve piglet bodyweight. BS9-L showed (P < 0.05) higher average daily gain (ADG) in Period 2 (D14-D28). BS9 groups had (P < 0.001) lower feed conversion ratio (FCR) in Period 2 (D14-D28) and overall. Like the ZnO-group, BS9 groups had lower (P < 0.01) diarrhea rate. A significant reduction (P < 0.05) in fecal E. coli, total coliforms, and an increase in lactic acid bacteria and Bacillus spp. in BS9 groups was observed. BS9 group had reduced (P < 0.05) mRNA levels of intestinal IL-8 and higher levels of MUC-1 and occludin and TJP-1 compared to negative control. These findings suggest that probiotic BS9, may promote growth performance, and ameliorate various indicators of intestinal health in piglets. Hence, it may serve as a prospective alternative to ZnO growth promoter in commercial swine production.

Choline supplementation regulates gut microbiome diversity, gut epithelial activity, and the cytokine gene expression in gilts.

Choline is an essential nutrient that is necessary for both fetal development and maintenance of neural function, while its effect on female ovarian development is largely unexplored. Our previous study demonstrated that choline supplementation promotes ovarian follicular development and ovulation, although its underlying mechanism was unclear. To uncover the potential regulation pathway, eighteen female Yorkshire × Landrace gilts were fed with either standard commercial diet (Control group, n = 9) or choline supplemented diet (Choline group, additional 500 mg/kg of control diet, n = 9) from day 90 of age to day 186. At day 186, feces samples were analyzed for effects on the gut microbiome using 16S ribosomal RNA gene V3-V4 region sequencing with Illumina MiSeq, serum samples were analyzed for trimethylamine (TMA) and trimethylamine-N-oxide (TMAO) using HILIC method, and jejunum tissues were analyzed for immune related gene expression using qRT-PCR. Our results show that choline supplementation did not alter the circulating level of TMA and TMAO (P > 0.05), but rather increased gut microbiome alpha diversity (P < 0.05). Beta diversity analysis results showed that the choline diet mainly increased the abundance of Firmicutes, Proteobacteria, and Actinobacteria, but decreased the abundance of Bacteroidetes, Spirochaetes, and Euryarchaeota at the phyla level. Meta-genomic analysis revealed that choline supplementation activated pathways in the gut microbiota associated with steroid hormone biosynthesis and degradation of infertility-causing environmental pollutants (bisphenol, xylene, and dioxins). To further verify the effect of choline on intestinal activity, a porcine intestine cell line (IPEC-J2) was treated with serial concentrations of choline chloride in vitro. Our data demonstrated that choline promoted the proliferation of IPEC-J2 while inhibiting the apoptotic activity. qRT-PCR results showed that choline significantly increased the expression level of Bcl2 in both IPEC-J2 cells and jejunum tissues. The expression of IL-22, a cytokine that has been shown to impact ovarian function, was increased by choline treatment in vitro. Our findings reveal the beneficial effect of choline supplementation on enhancing the gut microbiome composition and intestinal epithelial activity, and offer insights into how these changes may have contributed to the ovarian development-promoting effect we reported in our previous study.

Dietary supplementation with lysine (protein) stimulates mammary development in late pregnant gilts.

The goal of this project was to determine if standardized ileal digestible (SID) lysine provided at 40% above estimated requirements, with the concomitant increase in protein intake, from days 90 to 110 of gestation would stimulate mammary development in gilts. From day 90 of gestation, Yorkshire × Landrace gilts were fed 2.65 kg of either a conventional diet (CTL, control, n = 19) providing 18.6 g/d of SID Lys or a diet providing 26.0 g/d of SID Lys via additional soybean meal (HILYS, n = 19). Both diets were isoenergetic. Jugular blood samples obtained on days 90 and 110 of gestation were used to measure concentrations of insulin-like growth factor-1 (IGF-1), metabolites, and amino acids (AA). Gilts were necropsied on day 110 ± 1 of gestation to obtain mammary glands for compositional analyses, immunohistochemistry, and analysis of mRNA abundance for AA transporters and markers of cell proliferation and differentiation. The HILYS gilts gained more body weight (P < 0.01) during the experimental period compared with CTL gilts, and had greater fetal weights (1.29 vs. 1.21 ± 0.03 kg, P < 0.05). There was no difference in circulating IGF-1, glucose, or albumin (P > 0.10) between HILYS and CTL gilts on day 110 of gestation, whereas concentrations of urea and free fatty acids were greater (P < 0.01), and those of Trp and Ala were lower (P < 0.05), in HILYS than CTL gilts. The provision of lysine at 40% above estimated requirements increased total mammary parenchymal mass by 44%, as well as total parenchymal fat, protein, DNA, and RNA (P < 0.01). The mRNA abundance of ACACA was greater (P < 0.05) in HILYS than CTL gilts, while only the AA transporter SLC6A14 tended (P < 0.10) to be greater. Results demonstrate that providing dietary Lys above current National Research Council recommendations in late gestation increases mammary development in gilts. Results also indicate that Lys may have been limiting for protein retention. These data suggest that the use of a two-phase feeding strategy during gestation, whereby dietary Lys is increased from day 90, could benefit potential sow milk yield in the subsequent lactation.

Results indicate that the current National Research Council recommendations for dietary lysine during late pregnancy in pigs, the period when most mammary gland development takes place, are underestimated. From days 90 to 110 of gestation, gilts were fed 2.65 kg of either a conventional diet providing 18.6 g/d of standardized ileal digestible (SID) lysine, or a diet providing 26.0 g/d of SID lysine via the inclusion of additional soybean meal. Diets were isoenergetic. Feeding 26.0 g/d of SID lysine increased the mass of mammary parenchymal tissue (where milk is synthesized) by 44%. Findings suggest that a greater mammary uptake of lysine in supplemented sows supported enhanced accretion of mammary parenchyma. Such information is most pertinent in the actual context where milk yield of hyperprolific sows must be maximized to sustain optimal growth of all their piglets. Furthermore, these data indicate that the use of a two-phase feeding strategy during gestation, whereby dietary lysine is increased from day 90, could benefit potential sow milk yield in the subsequent lactation.

Choline supplementation influences ovarian follicular development.

BACKGROUND: Female infertility is a health issue for both humans and animals and despite developments in medical interventions, there are still some conditions that cannot be treated successfully. It is important to explore other potential therapies or remedies that could improve reproductive health. Choline is an over-the-counter supplement and essential nutrient that has many health benefits. It has been suggested to be beneficial in various aspects of fertility, including fetal development and endocrine disorders like polycystic ovarian syndrome (PCOS). However, choline's impact on ovarian function has not been explored. METHODS: To study the effects of choline on ovarian development, 36 female Yorkshire × Landrace pigs were fed the following four supplemented diets between 90 and 186 days of age: (1) Control (corn and soybean meal-based diet that met estimated nutrient requirements, n = 9); (2) Choline (additional 500 mg choline per 1 kg of control diet, n = 8); (3) Omega-3 (additional 5556 mg Omega-3 per 1 kg control diet by introducing fish oil); (4) Choline + Omega-3 (500 mg choline + 5556 mg Omega-3 per 1 kg control diet). Pigs fed the choline-supplemented diet were compared to the control group and those fed diets supplemented with Omega-3 as fertility-promoting agent. RESULTS: It was found that the number of corpus luteum per ovary in the Choline (16.25 ± 2.88), Omega-3 (10.78 ± 1.71) and Choline + Omega-3 (14.89 ± 2.97) groups were all higher in comparison to that of the control group (5.56 ± 1.72, p < 0.05). The percentage of antral follicles in the Choline + Omega-3 group were higher compared to the control group (p < 0.05). To elucidate the potential molecular mechanism of choline on these improved ovarian phenotypes, the expression of a group of genes that are involved in ovarian development, including cytochrome P450 family 11 subfamily A member 1 (CYP11A1), follicle stimulating hormone receptor (FHSR) and luteinizing hormone receptor (LHR), was analyzed using RT-qPCR. The expression of both LHR and CYP11A1 was significantly upregulated in the choline-supplemented group (p < 0.05), while there are no differences in FSHR expression among all the groups. Additionally, the expression of miR-21, -378, -574, previously found to be important in ovarian function, were examined. Our data showed that miR-574 was upregulated in the Choline group while miR-378 was upregulated in the Choline + Omega-3 group in comparison to the control group (p < 0.05). Further, serum metabolite analysis showed that 1-(5Z, 8Z, 11Z, 14Z, 17Z-eicosapentaenoyl)-sn-glycero-3-phosphocholine, a form of phosphatidylcholine metabolite, was significantly increased in all the treatment groups (p < 0.05), while testosterone was significantly increased in both Omega-3 and Choline + Omega-3 groups (p < 0.05) and tended to be reduced in the choline-supplemented group (p = 0.08) compared to the control group. CONCLUSIONS: Our study demonstrated choline's influence on ovarian function in vivo, and offered insights into the mechanisms behind its positive effect on ovarian development phenotype.

Impact of arginine supplementation on serum prolactin and mRNA abundance of amino acid transporter genes in mammary tissue of lactating sows.

This study was conducted to test the hypothesis that supplemental dietary Arg to late-pregnant and lactating sows increases serum prolactin concentrations and mRNA abundance of SLC7A1, SLC7A2, and SLC6A14 in mammary parenchymal tissue. From day 108 of gestation and until day 21 of lactation, sows were fed a diet either supplemented with 0.10 g of l-Arg/kg body weight (BW) per day (n = 10, ARG) or 0.34 g of l-Glu/kg BW per day (n = 10, control). Litters were standardized to 10 piglets on day 1 of lactation and piglets were weighed on days 1, 7, 14, and 21 of lactation. Sow BW was recorded on day 108 of gestation and days 1, 10, and 21 of lactation. Lactation sow feed intake was recorded daily. Mammary parenchymal tissue was biopsied on day 5 of lactation to measure mRNA abundance SLC7A1, SLC7A2, and SLC6A14. On days 4 and 18 of lactation, blood samples were collected from sows at 2, 4, and 6 hr postfeeding to measure serum prolactin concentrations. Milk samples were collected on days 4, 10, and 18 of lactation to measure fat, lactose, urea N, and true protein concentrations. Sow BW, backfat, and feed intake over all sampling days did not differ between treatments. Piglet BW on d 1 tended to be greater for the ARG treatment than the control treatment (P = 0.12). Sow milk yield and composition (fat, protein, lactose, and urea N) and mammary mRNA abundance of candidate genes did not differ between the ARG and the control group. Compared to controls, serum prolactin concentrations tended to be greater (P = 0.08) in ARG sows on day 4 of lactation, and did not differ on day 18. Current findings show a potential beneficial effect of dietary supplementation with Arg to late-pregnant multiparous sows on BW of their piglets on day 1. Dietary Arg supplementation at a rate of 0.10 g/kg BW during late pregnancy and lactation tended to increase serum prolactin concentrations with no increase in mammary transcript abundance of SLC7A1, SLC7A2, and SLC6A14 in early lactation.

The effect of reduced dietary glycine and serine and supplemental threonine on growth performance, protein deposition in carcass and viscera, and skin collagen abundance of nursery pigs fed low crude protein diets.

Thirty five barrows (initial body weight [BW]: 15.1 ± 1.0 kg) were used to determine the effect of partially replacing Gly + Ser with Thr in reduced crude protein (CP) diets on growth performance, protein deposition in carcass and viscera, and skin collagen abundance during the late nursery phase to 25 kg BW. Pigs were individually fed one of five iso-nitrogenous diets (n = 7) for 21 d. The basal diet met estimated essential amino acids (AA) requirements by using all essential AA plus Gly and Ser in free form (CON; 12.1% CP; as-fed, analyzed contents). The remaining four diets were formulated by reducing total Gly and Ser concentrations to 60% or 20% of the CON diet. The N removed with Gly and Ser was replaced with either crystalline Thr or Glu. Total analyzed Thr made up either 1.59% (T1; 12.5% CP) or 2.34% (T2; 12.2% CP) of the Thr-supplemented diets, and total analyzed Glu made up either 3.47% (G1; 12.7% CP) or 4.64% (G2; 12.9% CP) of the Glu-supplemented diets. Pigs were slaughtered on day 21 to determine body composition and skin collagen abundance via bright field microscopy. Overall, average daily gain (ADG) and G:F and final carcass weights were greater for pigs fed diets supplemented with Glu (G1 + G2) vs. those fed diets supplemented with Thr (T1 + T2; P < 0.05, P = 0.060, and P = 0.050 for ADG, G:F, and final carcass weight, respectively); intermediate values were observed for CON. Nitrogen retention in carcass plus viscera and the AA profile of deposited protein in the carcass were not influenced by dietary treatment. Pigs fed the T2 and G2 diets had greater retention of Thr (vs. CON and G2) and Glu (vs. CON and T2) in the viscera protein, respectively (P < 0.05). The apparent utilization efficiency of standardized ileal digestible Thr for protein deposition in carcass plus viscera was less for pigs fed T2 (15.1%) vs. those fed CON (56.7%) or G2 (58.6% ± 2.9%) diets (P < 0.001). Only pigs fed T1 had skin collagen abundance not different from CON; pigs fed G1, G2, and T2 had reduced skin collagen abundance compared with CON and T1 (P < 0.01). Using Glu as an N source when Gly and Ser were reduced to 60% and 20% of CON in reduced CP diets maintained ADG for pigs between 15 and 25 kg BW, whereas supplying Thr as a N source reduced ADG and carcass weight. When dietary Gly and Ser were supplied at 60% of CON, only Thr supplementation rescued skin collagen abundance. Therefore, supplemental Thr at excess levels is not sufficient to replace N from Gly and Ser in reduced CP diets fed to late nursery pigs, despite supporting skin collagen abundance as a secondary indicator of Gly status.

The effect of supplementing glycine and serine to a low crude protein diet on growth and skin collagen abundance of nursery pigs1.

A total of 96 newly weaned barrows (initial body weight [BW]: 6.3 ± 0.5 kg) were used to determine the effect of a low crude protein (CP) diet supplemented with Gly and Ser on growth and skin collagen abundance. Barrows were assigned to one of three experimental diets in a three-phase feeding program fed for 35 days (n = 8; pen was the experimental unit): 1) corn-soybean meal diet (CON; 20.3% to 23.1% CP; as-fed, analyzed contents); 2) low CP diet (14.8% to 21.4% CP) supplemented with Gly and Ser (G + S) to the same concentrations as CON; 3) low CP diet supplemented with Glu to maintain the same CP concentration as the G + S diet (GLU; 15.0% to 22.1% CP). On days 21 and 35, eight pigs per treatment were euthanized for the determination of physical and chemical body composition and skin collagen abundance. Pigs fed the CON diet had greater overall ADG and final BW compared to pigs fed GLU and G + S (P < 0.01). Over the entire 35-day experimental period, ADFI was not influenced by dietary treatment but G:F tended to be greater for pigs fed CON than G + S (P = 0.084), while intermediate values were observed for GLU. Carcass weights on days 21 and 35 were greater for pigs fed CON than G + S or GLU (P < 0.01). Viscera weights on day 21 were greater for CON than G + S and GLU (P < 0.05) and on day 35 were greater for CON than G + S (P < 0.05) with intermediate values observed for GLU. The N intake (g/d) between days 0 and 35 was greater for CON than G + S or GLU (P < 0.05) and N retention in combined carcass and viscera was greater for CON than G + S (P < 0.01) with intermediate values observed for GLU. No treatment effects were observed for efficiency of N utilization. Between days 0 and 21 however, the efficiency of using dietary N for N retention in carcass and viscera tended to be less for pigs fed CON vs. GLU (73.8% vs. 91.6%), while intermediate values were observed for G + S (84.3%; P = 0.095). Pigs fed CON and G + S diets had greater skin collagen abundance than pigs fed GLU on days 21 and 35 (P < 0.01). Supplementing low CP diets with Glu or with Gly and Ser at the levels used in the current study did not maintain ADG or combined carcass and viscera N retention and only the G + S diet supported skin collagen abundance not different from pigs fed CON. The importance of meeting essential AA requirements for growth are well accepted, but supplementing specific NEAA may be needed when feeding reduced CP diets to newly weaned pigs to support secondary indicators of AA status, such as skin collagen abundance.

Photoprotection But Not N-acetylcysteine Improves Intestinal Blood Flow and Oxidation Status in Parenterally Fed Piglets.

OBJECTIVES: The purpose of the present study was to determine if protecting parenteral nutrition solutions from ambient light and supplementing with N-acetylcysteine (NAC) improves mesenteric blood flow, gut morphology, and oxidative status of parenterally fed neonates. METHODS: Neonatal Yucatan miniature piglets (n = 23, 7-11 days old) were surgically fitted with central venous catheters and an ultrasonic blood flow probe around the superior mesenteric artery. Piglets were fed continuously for 7 days either light-protected (LP) or light-exposed (LE) complete parenteral nutrition that was enriched with either NAC or alanine (ALA). RESULTS: There were no differences in body weight or overall gut morphology among groups after 7 days. Plasma concentrations of NAC were greater and total homocysteine lower in NAC- versus ALA-supplemented pigs on day 7 (N-acetylcysteine: 94 vs 7 µmol/L; P < 0.001; homocysteine: 14 versus 21 µmol/L; P < 0.005); plasma total glutathione was not affected. Hepatic lipid peroxidation was reduced by 25% in piglets that received LP parenteral nutrition (P < 0.05). The mesenteric artery blood flow decreased in all pigs between days 2 and 6 (P < 0.001) because of parenteral feeding. Photoprotection alone (LP-ALA) attenuated the decrease in mesenteric blood flow to 66% of baseline on day 6 compared with LE-ALA (37%; P < 0.05) and LP-NAC pigs (43%; P = 0.062); LE-NAC piglets had intermediate reductions in blood flow (55%). CONCLUSIONS: Photoprotection of parenteral nutrition solutions is a simple, effective method to attenuate decline in blood flow to the gut and hepatic lipid peroxidation, which are both commonly associated with parenteral feeding.

The effects of a temporary lysine restriction in newly weaned pigs on growth performance and body composition1.

A serial slaughter study was conducted to determine the effects of a temporary Lys restriction immediately following weaning on growth performance and body composition. One hundred forty-four Yorkshire × Landrace × Duroc pigs (initial BW: 6.9 ± 0.2 kg) were randomly allocated to one of three dietary treatments (six pens per treatment with eight pigs per pen; four barrows and four gilts). For a 3-wk restriction period, pigs were fed diets that were 110% (Control) of the estimated required standardized ileal digestible (SID) Lys for nursery pigs or 20% (Lys20) or 40% (Lys40) below the estimated required SID Lys. Thereafter, all pigs were fed a common grower diet containing 120% of the estimated required SID Lys for 6 wk (recovery period). During the restriction period, ADG and G:F decreased with decreasing dietary Lys concentration (linear; P < 0.01). At the end of the restriction period, BW and whole-body protein concentrations decreased (linear; P < 0.01) and carcass lipid concentrations increased (linear; P < 0.01) with decreasing dietary Lys concentration. During the first 3 wk of the recovery period, ADG and G:F increased (linear; P < 0.05 and P < 0.01, respectively) and whole-body protein concentration at week 3 of the recovery period decreased (linear; P < 0.01) with decreasing dietary Lys concentration. There were no dietary treatment differences in whole-body lipid concentration after 3 wk of the recovery period. During the second half of the recovery period (weeks 7 through 9), there were no differences in ADG or G:F; after week 6, there were no differences in final BW (50.3 ± 0.5 kg) or whole-body protein (16.9 ± 0.2%) or lipid (14.9 ± 0.7%) concentrations. In conclusion, newly weaned pigs previously fed a Lys-limiting diet for 3 wk immediately after weaning achieved full compensatory growth with no differences in BW or body composition after a 6-wk recovery period. Reducing dietary Lys concentration early after weaning is a potential means to reduce the cost of (early) nursery diets without impacting overall growth and carcass composition.

Effects of dietary leucine supplementation and immune system stimulation on plasma AA concentrations and tissue protein synthesis in starter pigs.

Immune system stimulation (ISS) adversely affects protein and AA metabolism and reduces productivity in pigs. Leucine (Leu) has a regulatory role in skeletal muscle protein turnover, which may be affected by ISS. The objective of this study was to evaluate the effects of ISS and dietary Leu supplementation on the protein fractional synthesis rate (FSR) of various tissues in pigs. Yorkshire barrows were surgically fitted with jugular vein catheters and assigned to one of three dietary treatments: (i) CON, 1.36% standardized ileal digestible (SID) Leu; (ii) LEU-M, 2.04% SID Leu; and (iii) LEU-H, 2.72% SID Leu. The diets were formulated to contain all essential AA 10% above estimated requirements for maximum whole-body protein deposition for this BW range. At the start of the 36-h challenge period (initial BW = 14.5 ± 0.8 kg), ISS was induced in pigs with lipopolysaccharide (ISS+; n = 7, 8, and 7 for CON, LEU-M, and LEU-H pigs, respectively); a subset of CON pigs was injected with sterile saline (ISS-; n = 6). During challenge period, pigs were fed every 4 h and feed intake of ISS- pigs was kept equal to ISS+ pigs. At the end of the challenge period, FSR of liver, plasma, gastrocnemius, and LD proteins were determined with a flooding dose of l-[ring-2H5]phenylalanine (40 mol%). All essential AA, most nonessential AA, and plasma urea-N peaked at 12 h and declined to baseline levels at 36 h after ISS was induced in ISS+ pigs (P < 0.05), whereas plasma AA and urea-N concentrations were constant in ISS- pigs. At 36 h, dietary Leu supplementation resulted in a linear decline in plasma isoleucine, valine, glutamine, and urea nitrogen concentrations (P < 0.05), whereas plasma Leu concentration was unaffected. Liver protein FSR was increased in ISS+ pigs (P < 0.05), whereas plasma and skeletal muscle protein FSR was not affected by ISS. Dietary Leu supplementation tended to diminish liver protein FSR (linear reduction; P = 0.052) and increase gastrocnemius protein FSR (linear increase; P = 0.085) in ISS+ pigs. Leucine supplementation above estimated requirements may support repartitioning of AA from visceral to peripheral protein deposition during ISS.

Effect of reducing the ratio of omega-6-to-omega-3 fatty acids in diets of low protein quality on nursery pig growth performance and immune response.

A total of 240 newly weaned pigs (5.25 ± 0.15 kg BW) were used to determine the dietary omega-6-to-omega-3 (ω-6:ω-3) fatty acid ratio that optimized growth performance and immune responses when fed corn and soybean meal (SBM)-based diets with low protein quality. Pigs were randomly assigned to 1 of 5 dietary treatments (n = 6 pens per treatment; day 0 of study): [1] positive control (High; included animal proteins and 5% corn oil), [2] negative control (Low0; corn- and SBM-based and 5% corn oil), or 1 of 3 Low diets with increasing supplementation of fish oil to replace corn oil: [3] 1.25% (Low1.25), [4] 2.5% (Low2.5), [5] 5% (Low5) to achieve 5:1, 3:1, and 1:1 ω-6:ω-3 ratios, respectively. Pigs were fed dietary treatments in 2 phases for 7 and 14 d, respectively, followed by a common phase III diet for 21 d. On day 6 and 20, 12 pigs per treatment were immune sensitized with 0.5 mg ovalbumin (OVA) and 0.5 mg Quil A adjuvant in 1 mL saline. The dermal hypersensitivity response (DHR) was evaluated on day 40 in these same pigs, using intradermal injection of OVA; changes in skin-fold thickness were measured. On day 21, 4 pigs per pen were immune challenged with LPS (30 µg Escherichia coli LPS per kg BW) or saline (n = 12); rectal temperature was monitored over 3 h. During phase I only, ADG, ADFI, and G:F were greater for pigs fed the High diet vs. those fed the Low diet (P < 0.05), and increased with increasing fish oil supplementation up to 2.5% (Low2.5), but decreased for pigs fed the Low5 diet (quadratic; P < 0.05, P = 0.086, and P < 0.05 for ADG, ADFI, and G:F, respectively). On day 21, LPS increased rectal temperature (vs. saline at 1-, 2-, and 3-h post-challenge; P < 0.001); fish oil supplementation reduced rectal temperature 2-h post-challenge in the Low-fed pigs (linear; P < 0.05). On day 22, serum haptoglobin was greatest for pigs fed Low0 and decreased with increasing fish oil supplementation (linear; P < 0.05). Immunization with OVA induced a serum anti-OVA IgG response, which was reduced on day 34 among pigs fed Low diets with increasing fish oil supplementation (linear; P = 0.050). On day 40, and 6 h after intradermal injection of OVA, the DHR was least for pigs fed the Low2.5 diet (P < 0.05). Inclusion of 2.5% fish oil (3:1, ω-6:ω-3) optimized growth performance during the early nursery phase when pigs were most sensitive to diets with low protein quality; the ideal ω-6-to-ω-3 fatty acid ratio may differ when using immune responses as the major outcome.

Whole-body nitrogen utilization and tissue protein and casein synthesis in lactating primiparous sows fed low- and high-protein diets.

Twenty-eight lactating Yorkshire and Yorkshire × Landrace primiparous sows were used to test the hypothesis that feeding a diet with reduced CP concentration and supplemented with crystalline AA (CAA) does not decrease milk protein yield and litter growth but improves apparent N utilization for milk protein production. Sows were assigned to 1 of 2 dietary treatments: 1) control (CON; 16.2% CP; analyzed content) or 2) low CP with CAA to meet estimated requirements of limiting AA (LCP; 12.7% CP) over a 17-d lactation period. A N balance was conducted for each sow between days 13 and 17 of lactation. On day 17, a 12-h primed continuous infusion of l-[ring-2H5]-Phe was conducted on 12 sows (n = 6) with serial blood and milk sampling to determine plasma AA concentrations and Phe enrichment, and milk casein synthesis, respectively. Thereafter, sows were sacrificed and tissues were collected to determine tissue protein fractional synthesis rates (FSR). Litter growth rate and milk composition did not differ. Sows fed the LCP diet had reduced N intake (122.7 vs. 153.2 g/d; P < 0.001) and maternal N retention (13.5 vs. 24.6 g/d; P < 0.05) and greater apparent efficiency of using dietary N intake for milk production (85.1% vs. 67.5%; P < 0.001). On day 17 of lactation, all plasma essential AA concentrations exhibited a quartic relationship over time relative to consumption of a meal, where peaks occurred at approximately 1- and 4-h postprandial (P < 0.05). Protein FSR in liver, LM, gastrocnemius muscle, mammary gland, and in milk caseins did not differ between treatments. Feeding primiparous sows with a diet containing 12.7% CP and supplemented with CAA to meet the limiting AA requirements did not reduce milk protein yield or piglet growth rate and increased the apparent utilization of dietary N, Arg, Leu, Phe+Tyr, and Trp for milk protein production. The improved apparent utilization of N and AA appears to be related exclusively to a reduction in N and AA intake.