Low Birth Weight Pigs Research Articles

Effect of sex and milk replacer with or without supplemental carnitine and arginine on growth characteristics, carcass, and meat quality of artificially reared low-birth weight pigs.

This study compared milk replacer either remaining unsupplemented (CON) or supplemented with 0.5g L-carnitine plus 16.7g L-arginine/kg (CarArg) and fed to 48 low-birth weight (L-BtW) artificially reared piglets (24 per group) from days 7 to 28 of age. Eight farrowing series were needed to complete the study. On day 28, the lightest piglets were slaughtered, and the heaviest pigs were weaned. The heaviest pigs were weaned on day 28 and offered free access to a starter (weaning to 25kg body weight [BW]), grower (25 to 60kg BW), and finisher diet (60 to 96kg BW on day 170 of age). After euthanization on days 28 and 170, blood was sampled for assessment of serum metabolite and hormone concentrations, and the semitendinosus muscle (STM) was weighed, and later subjected to enzyme activity analysis and assessment of myofiber characteristics. In the 170-d-old pigs carcass and meat quality traits were assessed. Growth data were analyzed accordingtoatwo-way analysis of variance (ANOVA), with dietary treatment and farrowing series as fixed effects, while remaining data were analyzed with dietary treatment, sex, their interaction, and farrowing series as main factors. Dietary treatments affected (P ≤ 0.049) muscle enzyme activity at both day 28, with greater citrate synthase (CS) and LDH activities and lower HAD:CS ratio in STM light portion, and lower LDH:CS ratio in STM dark portion, and 170 of age with lower HAD:CS ratio. In the starter period, CarArg pigs had greater average daily gain (P = 0.021) and average daily feed intake (P = 0.010). At slaughter, these pigs had lower (P = 0.013) glucose and greater (P = 0.022) urea serum concentrations. However, supplementing the milk replacer with carnitine and arginine had no long-term effects on growth performance, carcass composition, and meat quality of L-BtW pigs. In addition, muscle morphology and myofiber-related properties remained unaffected by the supplementation.

Muscle Fiber, Connective Tissue and Meat Quality Characteristics of Pork from Low Birth Weight Pigs as Affected by Diet-Induced Increased Fat Absorption and Preferential Muscle Marbling.

This study investigated how birth weight differences in piglets affected carcass and muscle fiber properties as well as meat quality at slaughter. Within litters, piglets were grouped according to their birth weight as either normal (NBW; 1.62-1.73 kg) or low (LBW; 1.18-1.29 kg). At 5 weeks of age, NBW piglets were randomly transitioned to control (C) or isocaloric high fat diets derived from non-dairy (HF), while LBW piglets were randomly transitioned to high fat diets derived from non-dairy (HF) or dairy sources (HFHD). Piglets were reared in individual pens under standardized housing and feeding conditions. Live weight was recorded weekly, and pigs were slaughtered at 12 weeks of age. Hot carcass weights, dressing percentages, lean meat yield, and primal cut proportions were determined. The m. longissimus thoracis was collected from the right side of the carcass for measurement of physical and chemical properties of meat and muscle fiber characteristics. Results indicated that LBW pigs compensated for their live weight compared to NBW pigs at 6 weeks of age. The mean muscle fiber diameter of LBW-HFHD group is significantly higher than NBW-C and NBW-HF group, and the type I muscle fiber diameter is significantly higher than NBW-C group. Dairy fat inclusion in LBW pig diet reduced carcass back fat thickness. This increased the calculated lean meat yield to be comparable to that of NBW pigs fed a commercial diet. Incorporating dairy-sourced high-fat into LBW pigs' diets appears to be an effective strategy for producing carcasses equivalent to NBW pigs.

105 Awardee Talk: Timing of Dietary Zinc Supplementation During Gestation did not Affect Trace Element Concentrations in Sows and Their Piglets

Abstract Gestating sows (n = 267) were used to determine if timing of high dietary zinc supplementation in a commercial setting would reduce pre-weaning mortality of pigs and influence maternal and piglet copper (Cu), iron (Fe), and zinc (Zn) concentrations. Sows from three consecutive weekly farrowing groups were assigned randomly within parity to one of three dietary treatments consisting of: 1) Control: a corn-soybean meal diet containing 125 ppm supplemental Zn supplied by zinc hydroxychloride; 2) Breed-to-Farrow (B-to-F): as Control + 141 ppm supplemental Zn as ZnSO4 (266 ppm total supplemental Zn) fed from 5 days after breeding to farrowing; and 3) Day 110-to-Farrow (D110-to-F): as the Control diet fed from breeding to farrowing + 2,715 ppm supplemental Zn as ZnSO4 (2,840 ppm total supplemental Zn) starting on day 110 of gestation until farrowing. A subset of ten sows per treatment (n = 30; average parity = 3) were selected to assess Cu, Fe, and Zn concentrations of serum, colostrum, and milk. Sera were isolated from blood collections at allotment and the day before respective farrowing date of each sow. Colostrum was collected the day of farrowing and milk on day 2 of lactation. At farrowing, two average and two low birth weight pigs from each sow (n = 122) were selected for collections of serum and tail samples at days 1 and 2 of age, respectively. The statistical model included fixed effects of treatment, farrowing group, and the random effect of their interaction. The piglet model was similar but included the random term of pig nested within sow. There were no differences in concentrations of Cu, Fe, and Zn in sow serum, milk, or colostrum attributable to dietary treatment. Piglet serum concentrations of Cu, Fe, and Zn were unaffected by feeding gestating sows high levels of supplemental zinc at any time (Table). Low birth weight pigs born to sows fed the Control diet tended (P = 0.082) to have increased concentrations of Cu in tails compared with pigs born to sows fed high zinc. In conclusion, timing of dietary zinc supplementation to gestating sows had minimal influence on concentrations of important trace elements in sows and their offspring.

271 Impact of Amount and Solubility of Dietary Fiber Fed During Late Gestation and During the Pre-Farrowing Period on Sow and Litter Performance in Lactation

Abstract This study evaluated the impact of level and solubility of total dietary fiber (TDF) on sow and litter performance when fed during late gestation and early pre-farrowing. Sows (n = 241) were assigned by body condition to a 2×2 factorial arrangement plus a control treatment (with no supplement) with the following factors: 1) Amount of a fiber supplement (0.45 or 0.90 kg), and 2) Fiber solubility (high soluble dietary fiber (SDF) of 9.63% with 25.25% insoluble dietary fiber (IDF) or high IDF of 30.73% with 4.18% SDF). Fiber supplements were formulated using sugar beet pulp and soybean hulls and were provided in addition to a common gestation (12.0% TDF) and lactation diet (11.3% TDF) from day 99 (± 1 d) of gestation until parturition. Total number of pigs born, and piglet birth weight were not impacted by treatment. Number of stillborn pigs was reduced by 0.45 kg IDF supplement (P = 0.03), but it increased ( P= 0.008) the number of low-birth weight pigs (< 1 kg) compared with control, 0.90 kg IDF, and 0.45 and 0.90 kg SDF supplement (1.31a vs. 0.50b, 0.33b, 0.47b, and 0.40b, respectively). Treatment did not affect number of pigs weaned and pig weaning weight. Number of small-weaned pigs (< 3.6 kg) was least (P < 0.001) with 0.90 kg IDF, and 0.45 kg SDF compared with control, 0.45 kg IDF and 0.90 kg SDF (0.53c and 1.00bc vs 3.31a, 3.27a, and 2.00ab, respectively). Weaning to estrus interval was reduced (P = 0.003) by 0.90 kg IDF and 0.45 and 0.90 kg SDF compared with control and 0.45 kg IDF (5.00b, 4.77b, and 5.22ab vs. 6.51a, and 6.59a days, respectively). Results suggest that composition of fiber is important, and that fiber provided as a supplement to the standard feed may be a practical strategy to improve sow performance during the late gestation and the pre-farrowing period.

Branched-chain amino acid supplementation does not enhance lean tissue accretion in low birth weight neonatal pigs, despite lower Sestrin2 expression in skeletal muscle.

Postnatal muscle growth is impaired in low birth weight (L) neonatal pigs. Leucine supplementation has been established as a dietary intervention to enhance muscle growth in growing animals. The aim of this study was to investigate the efficacy of supplementing L neonatal pig formulas with branched-chain amino acids (B) to enhance the rate of protein accretion. Twenty-four 3-day old pigs were divided into two groups low (L) and normal birth weight (N) based on weight at birth. Pigs were assigned to a control (C) or 1% branched-chain amino acids (B) formulas, and fed at 250mL·kg body weight -1·d-1 for 28 d. Body weight of pigs in the L group was less than those in the N group (P < 0.01). However, fractional body weight was greater for L pigs compared with their N siblings from day 24 to 28 of feeding regardless of formula (P < 0.01). In addition, feed efficiency (P < 0.0001) and efficiently of protein accretion (P < 0.0001) were greater for L than N pigs regardless of supplementation. Pigs fed the B formula had greater plasma leucine, isoleucine, and valine concentrations compared with those fed the C formula (P < 0.05). Longissimus dorsi Sestrin2 protein expression was less for pigs in the L group compared with those in the N group (P < 0.01), but did not result in a corresponding increase in translation initiation signaling. Longissimus dorsi mRNAexpression of BCAT2 was less for LB pigs compared with those in the LC group, and was intermediate for NC and NB pigs (P < 0.05). Hepatic mRNA expression of BCKDHA was greater for pigs in the L compared with those in the N groups (P < 0.05). However, plasma branched-chain keto-acid concentration was reduced for C compared with those in the B group (P < 0.05). These data suggest that branched-chain amino acid supplementation does not improve lean tissue accretion of low and normal birth weight pigs, despite a reduction in Sestrin2 expression in skeletal muscle of low birth weight pigs. The modest improvement in fractional growth rate of low birth weight pigs compared with their normal birth weight siblings was likely due to a more efficient dietary protein utilization.

Review: Nutritional regulation of muscle growth in neonatal swine.

Despite advances in the nutritional support of low birth weight and early-weaned piglets, most experience reduced extrauterine growth performance. To further optimize nutritional support and develop targeted intervention strategies, the mechanisms that regulate the anabolic response to nutrition must be fully understood. Knowledge gained in these studies represents a valuable intersection of agriculture and biomedical research, as low birth weight and early-weaned piglets face many of the same morbidities as preterm and low birth weight infants, including extrauterine growth faltering and reduced lean growth. While the reasons for poor growth performance are multifaceted, recent studies have increased our understanding of the role of nutrition in the regulation of skeletal muscle growth in the piglet. The purpose of this review is to summarize the published literature surrounding advances in the current understanding of the anabolic signaling that occurs after a meal and how this response is developmentally regulated in the neonatal pig. It will focus on the regulation of protein synthesis, and especially the upstream and downstream effectors surrounding the master protein kinase, mechanistic target of rapamycin complex 1 (mTORC1) that controls translation initiation. It also will examine the regulatory pathways associated with the postprandial anabolic agents, insulin and specific amino acids, that are upstream of mTORC1 and lead to its activation. Lastly, the integration of upstream signaling cascades by mTORC1 leading to the activation of translation initiation factors that regulate protein synthesis will be discussed. This review concludes that anabolic signaling cascades are stimulated by both insulin and amino acids, especially leucine, through separate pathways upstream of mTORC1, and that these stimulatory pathways result in mTORC1 activation and subsequent activation of downstream effectors that regulate translation initiation Additionally, it is concluded that this anabolic response is unique to the skeletal muscle of the neonate, resulting from increased sensitivity to the rise in both insulin and amino acid after a meal. However, this response is dampened in skeletal muscle of the low birth weight pig, indicative of anabolic resistance. Elucidation of the pathways and regulatory mechanisms surrounding protein synthesis and lean growth allow for the development of potential targeted therapeutics and intervention strategies both in livestock production and neonatal care.

Low birth weight and reduced postnatal nutrition lead to cardiac dysfunction in piglets.

Heart disease is the leading cause of death in humans and evidence suggests early life growth-restriction increases heart disease risk in adulthood. Therefore, this study sought to investigate the effects of low birth weight (LBW) and postnatal restricted nutrition (RN) on cardiac function in neonatal pigs. We hypothesized that LBW and RN would reduce cardiac function in pigs but this effect would be reversed with refeeding. To investigate this hypothesis, pigs born weighing <1.5 kg were assigned LBW, and pigs born >1.5 kg were assigned normal birth weight (NBW). Half the LBW and NBW pigs underwent ~25% total nutrient restriction via intermittent suckling (assigned RN) for the first 4 wk post-farrowing. The other half of piglets were allowed unrestricted suckling access to the sow (assigned NN). At 28 d of age (weaning), pigs were weaned and provided ad libitum access to a standard diet. Echocardiographic, vascular ultrasound, and blood pressure (BP) measurements were performed on day 28 and again on day 56 to assess cardiovascular structure and function. A full factorial three-way ANOVA (NN vs. RN, LBW vs. NBW, male vs. female) was performed. Key findings include reduced diastolic BP (P = 0.0401) and passive ventricular filling (P = 0.0062) in RN pigs at 28 d but this was reversed after refeeding. LBW piglets have reduced cardiac output index (P = 0.0037) and diastolic and systolic wall thickness (P = 0.0293 and P = 0.0472) at 56 d. Therefore, cardiac dysfunction from RN is recovered with adequate refeeding while LBW programs irreversible cardiac dysfunction despite proper refeeding in neonatal pigs.

Serum metabolomic characterization in pigs in relation to birth weight category and neonatal nutrition.

The objective of this study was to characterize developmental differences in low birth weight (LBW) and normal birth weight (NBW) piglets with or without pre-weaning nutrient restriction using serum metabolomic profile analysis. At farrowing, 112 piglets were identified as LBW (1.22 ± 0.28 kg) or NBW (1.70 ± 0.27 kg) and were randomly assigned to receive normal nutrition (NN) or restricted nutrition (RN) (6 h/day no suckling) from days 2 to 28 post farrow (n = 8 pigs/group). On day 28, piglets were weaned onto a common diet. Fasted blood samples were obtained on days 28 and 56 (n = 8 pigs/group) and were analyzed using quantitative metabolomics via a combination of direct injection mass spectrometry with a reverse-phase LC-MS/MS custom assay. Data were normalized using logarithmic transformation and auto-scaling. Partial least squares discriminant analysis (PLS-DA) was carried out to further explore the differential metabolites among the groups (metaboanalyst.ca) with an integrated enrichment and pathway topography analysis. On day 28, LBW piglets had lower levels of essential amino acids as well as reduced metabolites associated with fatty acid oxidation, glycolysis, and the tri-carboxylic acid (TCA) cycle compared to the NBW group. The overall reduction of metabolites associated with energy production and regulation suggests that LBW vs. NBW are in an energy-survival state. On day 56, LBW pigs had increased utilization of fatty acids and resultant ketone production, evident by increased carnitines, acetoacetate, β-hydroxybutyrate, and glycerol compared to NBW pigs. In addition, compared to the NBW pigs LBW pigs had a consistent decrease in serum glucose and lactate as well as reduced TCA cycle metabolites: pyruvate, succinate, citrate, and α-ketoglutaric acid similar to day 28. Low reliance on glycolysis and the TCA cycle and higher glycerol production in the LBW pigs may indicate impairments in glucose tolerance at 56 d. In summary, LBW piglets appear to have more metabolic alterations in early life, which is not resolved with adequate nutrition or refeeding and may elucidate physiological and metabolic mechanisms of poor growth and life performance compared to NBW pigs later in life.

Sex bias in utero alters ovarian reserve but not uterine capacity in female offspring†.

Environmental stressors to which a fetus is exposed affect a range of physiological functions in postnatal offspring. We aimed to determine the in utero effect of steroid hormones on the reproductive potential of female offspring using a porcine model. Reproductive tracts of pigs from female-biased (>65% female, n = 15), non-biased (45-54.9% female, n = 15), and male-biased litters (<35% females, n = 9) were collected at slaughter (95-115kg). Ovaries and uterine horns were processed for H&E or immunohistochemistry. Variability of data within groups was analyzed with a Levene's test, while data were analyzed using mixed linear models in R. In the ovarian reserve, there was a significant birth weight by sex ratio interaction (P = 0.015), with low birth weight pigs from male-biased litters having higher numbers of primordial follicles with opposite trends seen in pigs from female-biased litters. Sex bias held no effect on endometrial gland development. A lower birth weight decreased the proportion of glands found in the endometrium (P = 0.045) and was more variable in both male-biased and female-biased litters (P = 0.026). The variability of primordial follicles from male-biased litters was greater than non- and female-biased litters (P = 0.014). Similarly, endometrial stromal nuclei had a greater range in male- and female-biased litters than non-biased litters (P = 0.028). A crucial finding was the greater variability in primordial follicles in the ovaries from females derived from male-biased litters and stromal cell count in the endometrium of females from male- and female-biased litters. This could be inflating the variability of reproductive success seen in females from male-biased litters.

268 Effect of Functional Amino Acid Supplementation in low and Normal Birth Weight Pigs on Performance and Immune Status During Subsequent Salmonella Challenge

Abstract Functional amino acid (FAA) supplementation improves growth performance and immune status of weaned pigs. The objective was to determine the effects of birth weight and FAA supplementation in the post-weaning period on the response of pigs to a subsequent Salmonella (ST) challenge. Thirty-two low (1.09±0.11 kg; LBW) and normal birth weight (1.58±0.11 kg; NBW) pigs were assigned to a nursery feeding program for 4 wk in a 2 × 2 factorial with factors of birth weight category (LBW vs. NBW) and basal (FAA–) or supplemented FAA profile (FAA+; Thr, Met, and Trp at 120% of requirements). Pigs were then placed onto a grower diet and, after a 7-d adaptation period, were inoculated with ST (2.2 × 109 CFU/mL) and monitored for 7 d post-inoculation. Growth performance, rectal temperature, gut health, ST fecal shedding and translocation, and blood parameters were measured pre- and post-inoculation. Inoculation with ST increased rectal temperature (39.7 vs. 38.9±0.5 oC) and overall rectal temperature was higher in LBW compared with NBW pigs (39.6 vs. 39.0±0.5 oC; P&amp;lt; 0.05). Salmonella shedding (1.8 vs. 2.3±0.1 score) and translocation to spleen (1.3 vs. 2.5±0.1 score) were less in NBW-FAA+ than NBW-FAA- pigs (P&amp;lt; 0.05). Post-inoculation weight gain was greater in NBW-FAA+ compared with the other groups (0.57 vs. 0.45±0.03 kg/d; P&amp;lt; 0.05). Post-inoculation haptoglobin (d 4; 1.0 vs. 0.7±0.1 g/L) and colonic myeloperoxidase (d 7; 4.3 vs. 2.5±0.6 µU/mL) were greater in LBW-FAA- pigs compared with the other groups (P&amp;lt; 0.05). On d 4 post-inoculation, plasma superoxide dismutase was less in LBW- FAA+ than in LBW-FAA- (60.5 vs. 93.3±7.7 mU/mL; P&amp;lt; 0.05). Reduced:oxidized glutathione at d 7 post-inoculation was greater in NBW compared with LBW pigs (2.5 vs. 1.7±0.3; P&amp;lt; 0.05). In conclusion, negative effects of Salmonella infection are ameliorated with supplementation of FAA to a greater extent in NBW than in LBW pigs.

Functional amino acid supplementation postweaning mitigates the response of normal birth weight more than for low birth weight pigs to a subsequent Salmonella challenge

Previous work has shown that dietary supplementation with key functional amino acids (FAA) improves growth performance and immune status of disease-challenged normal birth weight (NBW) pigs. It is not known whether FAA supplementation attenuates the effects of a subsequent disease challenge or whether this response is similar in low birth weight (LBW) pigs. The objective was to determine the effects of birth weight and FAA supplementation during the postweaning period in Salmonella-challenged pigs. Thirty-two LBW (1.08 ± 0.11 kg) and NBW (1.58 ± 0.11 kg) pigs were assigned to a nursery feeding program at weaning (25 d) for 31 days in a 2 × 2 factorial arrangement. Factors were birth weight category (LBW vs. NBW) and basal (FAA–) or supplemented FAA profile (FAA+; Thr, Met, and Trp at 120% of requirements). At d 31, pigs were placed onto a common grower diet and, after a 7-d adaptation period, were inoculated with Salmonella Typhimurium (ST; 2.2 × 109 colony-forming units/mL) and monitored for 7-d postinoculation. Growth performance, rectal temperature, fecal score, indicators of gut health, ST shedding score in feces, intestinal ST colonization and translocation, and blood parameters of acute-phase response and antioxidant balance were measured pre- and postinoculation. Inoculation with ST increased temperature and fecal score, and the overall rectal temperature was higher in LBW compared to NBW pigs (P < 0.05). Postinoculation (d 7), reduced:oxidized glutathione was increased in NBW compared to LBW pigs (P < 0.05). Salmonella shedding and translocation to spleen were lower in NBW-FAA+ compared to NBW-FAA− pigs (P < 0.05). Postinoculation average daily gain was higher in NBW-FAA+ (P < 0.05) compared to the other groups. Postinoculation haptoglobin, superoxide dismutase, and colonic myeloperoxidase were increased in LBW-FAA− pigs (P < 0.05). Ileal alkaline phosphatase was decreased in LBW compared to NBW (P < 0.05). Overall, FAA supplementation represents a potential strategy to mitigate the effect of enteric disease challenge in NBW, but not LBW pigs.

High Vaccenic Acid Content in Beef Fat Attenuates High Fat and High Carbohydrate Western Diet Induced Changes in Lipid Metabolism and Gut Microbiota in Pigs.

High-fat diets (HFD) have been shown to induce substantial shifts in intestinal microbial community composition and activity which are associated with adverse metabolic outcomes. Furthermore, changes in microbial composition are affected by fatty acid composition; saturated, monounsaturated (MUFA), and industrial trans fats (iTFA) adversely affect microbial diversity while polyunsaturated fats (PUFA) have been shown to have neutral effects. The effects of naturally occurring trans fats on gut microbial composition are unknown. Vaccenic acid (VA) is the most abundant naturally occurring trans fat (abundant in meat and dairy), can be elevated by altering a cow’s diet, and has been shown to have hypolipidemic effects. The aim of this study was to determine how variations of VA content in beef fat affect gut microbial composition, insulin resistance, and lipid metabolism in pigs. Low birth weight (LBW) and control pigs were fed a control or high-fat, high-carbohydrate (HFHC) diet supplemented with beef fat containing either high or low VA levels for 7 weeks. An adapted modified oral glucose tolerance test and fat challenge test were performed at 9 weeks of age following implantation of jugular catheters. Impacts on microbial composition were assessed using 16S rRNA gene amplicon sequencing. The HFHC diet containing beef fat rich in VA had a mild insulin sensitizing effect (p < 0.05, slope of curve), increased plasma HDL cholesterol (p < 0.05, +28%), reduced postprandial plasma TG (p < 0.05), and showed protection from HFHC-induced changes to gut microbial composition in LBW pigs as compared to HFHC diet containing standard beef fat. This is the first study to show effects of natural trans fats on gut dysbiosis; further studies are needed to elucidate mechanisms.

510 Late-Breaking: Dietary Glycine Supplementation During Growing and Finishing Phases Increases Tissue Concentrations of Total Creatine and Gene Expression of Creatine-synthetic Enzymes in Low-birthweight Pigs

Abstract Dietary glycine is required for maximum growth and development in animals by stimulating muscle protein synthesis and as a component of creatine. Creatine is synthesized from glycine, arginine, and S-adenosylmethionine by arginine:glycine amidinotransferase (AGAT) and guanidinoacetate N-methyltransferase (GAMT). Sufficient creatine synthesis for growth requires adequate substrate supply. However, swine diets are deficient in glycine. Additionally, intrauterine growth restricted (IUGR) pigs have reduced glycine synthesis. This results in decreased creatine synthesis and lower total creatine content in tissues, leading to reduced cellular energy metabolism and diminished muscle protein accretion. This study was designed to test the hypothesis that dietary glycine supplementation in corn-and-soybean-meal-based diets would improve overall growth and skeletal muscle accretion in post-weaning IUGR pigs by increasing the expression of creatine-synthetic enzymes and tissue concentrations of total creatine. Fourteen IUGR pigs (birthweight = 0.98±0.03 kg, mean±SEM) and 20 normal birthweight pigs (birthweight = 1.44±0.02 kg, mean±SEM) were obtained at weaning for this study. Pigs from each birthweight group were randomly assigned to 1% glycine + 0.19% corn starch treatment group or 1.19% alanine group (isonitrogenous control) for the study (21 d to 188 d of age); tissues were collected at d 188. Data were analyzed by using 2-way ANOVA and the Duncan multiple comparison test. Glycine-supplemented IUGR pigs had greater tissue concentrations of creatine, creatinine, and creatine phosphate than control IUGR in all tissues measured (P&amp;lt; 0.05). Control IUGR pigs showed diminished activity and mRNA expression of creatine-synthetic enzymes (P &amp;lt; 0.05); this was mitigated by glycine supplementation as glycine supplemented IUGR pigs showed normal levels of enzyme activity and mRNA expression. Overall, results of this study indicate dietary glycine supplementation to IUGR pigs between weaning and market weight effectively restores creatine-synthetic enzyme activities and increase tissue concentrations of total creatine, leading to increased lean tissue growth. (Supported by USDA-NIFA)

Birth Weight and Nutrient Restriction Affect Jejunal Enzyme Activity and Gene Markers for Nutrient Transport and Intestinal Function in Piglets.

Simple SummaryBirth weight and nutrient utilization are thought to have significant effects on intestinal development in neonatal pigs. The present study evaluated the impact of low and normal birth weight with and without nutrient restriction during the neonatal period on jejunal development. The results observed suggest that during the first 28 d of life, birth weight had greater effects on intestinal development than nutrient level, however, at d 56, the nutrient level was a significant contributor to intestinal function and enzyme activity compared to birth weight. Taken together, both birth weight and nutrient restriction have effects on intestinal development, but may have a greater impact in early life (d 28).Significant variation in the birth weight of piglets has arisen due to increased sow prolificacy. Intestinal development and function may be affected by birth weight. Low birth weight (LBW) pigs may also have reduced feed intake, leading to further impairment of intestinal development. The objective of this study was to examine the intestinal development pattern of LBW and normal birth weight (NBW) piglets with normal nutrition (NN) or restricted nutrition (RN) in the pre-weaning period. Jejunal intestinal samples were analyzed for target gene expression and enzyme activity at d 28 (weaning) and d 56 (post-weaning). At d 28, excitatory amino acid transporter (EAAC1) and sodium-dependent neutral amino acid transporter (B0AT1) were downregulated in LBW compared to NBW pigs (p < 0.05). On d 56, B0AT1 and ASCT2 (glutamine transporter) were downregulated in RN compared to NN pigs (p < 0.05), regardless of birth weight. Peptide transporter 1 (PepT1) expression was downregulated in LBW compared to NBW pigs at 28 d (p < 0.05), with no effects of treatments at 56 d. Sodium-glucose transporter-1 (SGLT1) was upregulated in NBW-NN compared to LBW-NN pigs (p < 0.05) at 28 d. Alkaline phosphatase (ALP) was upregulated in LBW-RN at d 28. At d 56, claudin-3 (CLDN-3) and Zonular occludin-1 (ZO-1) were upregulated in NN compared to RN pigs (p < 0.05). There were no treatment effects on ALP, maltase, or sucrase activity at 28 d. However, at 56 d, ALP was upregulated in NBW-NN pigs while sucrase activity was upregulated in NN pigs (p < 0.05). The results demonstrate differences in jejunal gene expression associated with birth weight, with reduced gene expression of amino acid transporters (PepT1, EAAC1, B0AT1) in LBW compared to NBW pigs (p < 0.05). While neonatal nutrient restriction had minimal effects at 28 d and d 56 for tight junction protein transcript abundance, neutral amino acid transporter abundance was upregulated in NN pigs compared to RN piglets (p < 0.05).

Low birth weight female piglets show altered intestinal development, gene expression, and epigenetic changes at key developmental loci.

Intestinal development is compromised in low birth weight (LBW) pigs, negatively impacting their growth, health, and resilience. We investigated the molecular mechanisms of the altered intestinal maturation observed in neonatal and juvenile LBW female piglets by comparing the changes in intestinal morphology, gene expression, and methylation in LBW versus normal birth weight (NBW) female piglets. A total of 16 LBW/NBW sibling pairs were sacrificed at 0hours, 8hours, 10days, and 8weeks of age. The gastrointestinal tract was weighed, measured, and the small intestine was sampled for histomorphology, gene expression, and methylation analyses. Impaired intestinal development, with shorter villi and shallower crypts, was observed in LBW female piglets. The expression of intestinal development markers (ALPI and OLFM) rapidly peaked after birth in NBW but not in LBW female piglets. The lower expression of genes involved in nutrient digestion (ANPEP and SI) and barrier function (OCLN and CLDN4) in LBW, together with their delayed development of intestinal villi and crypts could help to explain the compromised health and growth potential of LBW female piglets. The changes in methylation observed in LBW in key regulators of intestinal development (OLFM4 and FZD5) suggest long-term effects of BW on intestinal gene expression, development, and function. Accordingly, experimental demethylation induced in IPEC-J2 cells led to increased expression of intestinal genes (MGA, DPP4, and GLUT2). Overall, we have identified the alterations in transcription or epigenetic marking at a number of genes critical to intestinal development, which may contribute to both the short- and long-term failure of LBW female piglets to thrive.

PSIV-7 Effect of dietary tryptophan supplementation on growth, energy balance and blood metabolites in milk-fed low birth weight pigs

Abstract Low birth weight (LBW) is associated with reduced postnatal growth efficiency, glucose intolerance and type II diabetes mellitus in adulthood. Using a piglet model of LBW, the objective of this study was to investigate the effect of supplemental Trp on growth, energy balance and blood metabolites in LBW pigs. LBW (&amp;lt; 1.0 Kg) and normal birth weight (NBW; &amp;gt; 1.0 Kg) pigs were selected from twelve sows (parity=2–4, litter size=14–18; three LBW and one NBW piglets/sow) and randomly assigned to 4 milk-replacer based treatments (n=7–8; 7 days old) including: 1) NBW with 0% L-Trp (NBW-T0), 2) LBW with 0% L-Trp (LBW-T0), 3) LBW with 0.4% L-Trp (LBW-T0.4), and 4) LBW with 0.8% L-Trp (LBW-T0.8) for 3 weeks. Diets were provided 4–5 times/day and the voluntary intake was measured for each feeding throughout the study. Growth parameters, heat production and body weight were recorded biweekly. After an overnight fast at week 3, pigs were allowed to consume their respective diets for 1 hour and blood samples were collected at baseline (0), 60 and 120 min after the meal test. The data were analyzed using univariate GLM with Dunnett’s post-hoc test (SPSS®). No significant differences were observed on growth parameters (i.e. body weight, heart girth, wither height and body length), growth performance (i.e. average daily gain, average daily feed intake, gain:feed, gain:protein) and heat production when LBW-T0 was compared with LBW-T0.4 and LBW-T0.8. The plasma triglycerides for pigs fed LBW T0.4 and T0.8 was lower compared to that offered LBW-T0, but total cholesterol did not differ across groups. Pigs in LBW-T0.8 group had lower blood glucose than those fed LBW-T0 at 60 min after the meal challenge. In conclusion, Trp supplementation did not affect the growth and energy balance, but reduced the blood glucose and triglycerides concentration in LBW pigs.

21 Effects of supplementing late gestation sow diets with zinc on pre-weaning mortality of pigs under commercial rearing conditions

Abstract The objective of this experiment was to determine pre-weaning survival of pigs when sows were supplemented with 3 dietary levels of Zn in late gestation. Gilts and sows (n = 339) were assigned to one of three dietary treatments based on parity. Treatments were: 1) Control – corn-soybean meal-based diet containing 125 ppm supplemental Zn as ZnSO4 (75 ppm Zn) and AvailaZn™ (50 ppm Zn, CON); 2) Intermediate – as Control + 240 ppm supplemental Zn as ZnSO4 (INT); and 3) High – as Control + 470 ppm supplemental Zn as ZnSO4 (HI). Final supplemental Zn concentrations of diets were: 1) CON – 125 ppm; 2) INT – 365 ppm; and 3) HI – 595 ppm. Sows received dietary treatments from about d 85 of gestation until farrowing. Individual piglet birth weights were recorded within 12 h of parturition and all instances of piglet mortality were recorded. The statistical model considered fixed effects of diet and random effects of parity. Chi-square analysis was used to determine diet effects on piglet mortality. There were no differences in total pigs born, born alive, or weaned per litter. However, piglets from sows fed the INT diet had heavier (P &amp;lt; 0.05) birth weights (1.42 kg) than those fed CON (1.38 kg). Furthermore, incidence of low birth weight pigs was less (P &amp;lt; 0.05) for sows consuming INT compared with sows fed CON and HI (Table 1). Overall piglet mortality tended to decrease (P &amp;lt; 0.10) as dietary Zn increased. Furthermore, mortality of low birth weight pigs decreased (P &amp;lt; 0.05) as dietary Zn increased. Overall, effects of supplemental dietary Zn at 365 and 595 ppm in late gestation improved pre-weaning survival of low birth weight piglets and reduced overall pre-weaning mortality of piglets.

Associations among individual gilt birth weight, litter birth weight phenotype, and the efficiency of replacement gilt production.

Selection for larger litter size has increased the number of low individual birth weight (BWi) pigs and produced sows with a repeatable low average litter birth weight phenotype (BWP). Using an average of 3.6 litters records per sow, BWP was established in 644 nucleus-multiplication sows producing replacement gilts in a large commercial operation and classified as low (L-BWP, <1.18 kg, n = 85), medium (M-BWP, ≥1.18 to ≤1.35 kg, n = 250), or high (H-BWP, >1.35 kg, n = 309) on the basis of a BWi of 1.18 kg below which there was a high risk of early mortality and the average BWi (1.35 kg) for the population. In subsequent litters, potential replacement gilts born to these sows (n = 7,341) received a unique identification tag that allowed the impact of BWi, BWP, and their interactions on the efficiency of replacement gilt production to be evaluated. Negative effects of BWi on mortality until day 4 after birth were confirmed (P < 0.05) and cumulative losses to weaning, to day 70 of age, and to final pre-selection at 165 d of age were affected (P ≤ 0.05) by the interaction between BWP and BWi. Among the 2,035 gilts for which records for selection efficiency and production to fourth parity were available, a lower BWi decreased the probability of gilts reaching pubertal estrus (P < 0.05) after 21 and 28 d of boar stimulation starting at 180 d of age, with no effect of BWP. Overall, neither BWi, BWP, nor their interaction affected age at puberty. After breeding, only the main effect of BWP affected productivity and retention in the sow herd. In parities 1 and 2, percent stillborn was higher in litters born to gilts from H-BWP compared with L-BWP dams (P < 0.05), and in parity 2, total born and born alive were lower in sows derived from H-BWP compared with other BWPs. There were no differences in retention based on BWP classes until parity 2, after which retention tended (P ≤ 0.09) to be lower in sows derived from H-BWP compared with L-BWP dams. These results provide evidence that sow BWP is an important factor in the overall efficiency of replacement gilt management. This study also confirms that effective gilt selection and pre-breeding management protocols support excellent sow lifetime productivity and mitigate the risk of a high BWP in the litter of origin affecting retention in the breeding herd.

Impact of feeding low and average birthweight pigs on a weight basis post-weaning on growth performance and body composition

This study aimed to investigate the effectiveness of employing a targeted nutritional regime until slaughter to maintain performance in animals recording high weaning weights. Low birthweight (Low BW; <1 kg) and average birthweight (Av BW; 1.3kg-1.7 kg) pigs were reared on sows exhibiting a high lactation feed intake and, as a result, weaning weights were 7.9 kg and 8.9 kg respectively. Pens containing either Low BW or Av BW animals were then offered either a ‘standard’ (STAND) or ‘feed-to-weight’ (FTW) regime from weaning until slaughter. The STAND regime was reflective of commercial production, where diet transitions were implemented after pre-determined feed levels or time intervals had been reached. In contrast, diet transitions in the FTW regime were carried out when target pen average weights of 12 kg, 18 kg, 22 kg, 45 kg and 75 kg respectively were met. Animal growth, feeding performance and body composition were monitored from weaning until slaughter. As expected, Av BW pigs were heavier than Low BW animals throughout (P<0.001), recording a superior average daily gain (ADG) (P<0.01) and average daily feed intake (ADFI) (P<0.001) at each stage of growth. This resulted in Av BW animals recording a greater carcass weight (P<0.001) and kill-out percentage (P<0.01). DEXA scan analysis showed Low BW animals to exhibit a greater percentage fat (P<0.001) and lower percentage lean (P<0.01) content at week 4 and 10 of age, however birthweight had no effect on these parameters at week 21 (P>0.05). Feeding regime did not affect age or weight at diet transition for Av BW animals for most transitions (P>0.05). However Low BW animals offered the FTW regime were significantly older and heavier than those offered the STAND regime at each transition (P<0.05). The FTW regime increased animal ADG and ADFI compared to STAND pigs from weeks 4 to 10 of age (P<0.05), whilst providing a greater average daily intake of energy and lysine from week 4 to 10 (P<0.05) and week 10 to 17 (P<0.05). This facilitated a greater liveweight in FTW animals from 7 weeks of age through to slaughter (P<0.05). Feeding regime had no effect on kill-out percentage or back-fat depth (P>0.05). Furthermore, DEXA scan results showed total or percentage lean and fat did not differ for FTW or STAND pigs at 10 or 21 weeks of age (P>0.05). In conclusion, feeding Low BW animals on a ‘feed to weight’ basis improved nutrient intake and animal liveweight, likely due to a greater time allowance for digestive development between diet transitions. As such, this approach should be considered for commercial adoption.

What is the current significance of low birthweight pigs on commercial farms in Northern Ireland in terms of impaired growth and mortality?

There is little modern data addressing the differential lifetime growth of commercially reared low and average birthweight pigs born into large litters (>14 piglets). As such, the main aim of this study was to quantify the lifetime growth and mortality rate of low and average birthweight pigs on commercial farms in Northern Ireland. It was also aimed to analyze the level, stage and cause of mortality within each birthweight category. A total of 328 low birthweight (low BW; <1 kg) and 292 average birthweight (Av BW; 1.3 to 1.7 kg) pigs were individually identified across four commercial farms and one research farm. Animal growth and mortality were monitored on an individual basis from birth until slaughter age. Av BW pigs were heavier than low BW pigs throughout the trial (P < 0.001), with a weight advantage of 1.16 kg at weaning increasing to over 9 kg at slaughter age. Av BW pigs recorded a superior average daily gain (ADG) to low BW pigs throughout the trial (P < 0.05), with the greatest difference recorded immediately postweaning between weeks 4 and 8 and weeks 8 and 12 when a 77 and 85 g/d difference was recorded, respectively. AV BW pigs which were cross-fostered were significantly lighter than those remaining with their birth mother at weaning (0.9 kg), week 8 (1.7 kg), and week 12 (3.1 kg) (P < 0.05, respectively). The variance of weight was significantly greater for the AV BW pig population than the low BW pig population at week 4 (P < 0.001) and 8 (P < 0.05). Preweaning mortality of low BW pigs was over three times greater than that of Av BW pigs (21% vs. 6%; P < 0.001), with low BW deaths occurring earlier (9.2 d vs. 15.4 d; P < 0.001) and at a lighter weight (1.2 vs. 2.4 kg; P < 0.001) than Av BW pigs. There was a clear association between birthweight and cause of preweaning death (P < 0.05), with starvation (49%) and overlying (28%) accounting for the majority of low BW mortalities. Birthweight had no effect on rate, age, or weight of postweaning mortalities (P > 0.05). The alimentary tract (27%) and respiratory tract (27%) were the most commonly implicated body systems following postmortem examination of postweaning deaths. In conclusion, this study quantified the inferior weight, growth rate, and mortality of low BW pigs, identifying the lactation and immediate postweaning periods as having the greatest potential in reducing this birthweight associated growth differential.