Birth Weight Pigs Research Articles

Prematurity Attenuates Skeletal Muscle Anabolism of Neonatal Pigs Independently of Birth Weight

ObjectivesPremature infants are at risk for postnatal growth failure that reduces lifelong lean mass. We have shown previously that preterm birth blunts the feeding-induced activation of the mechanistic target of rapamycin (mTOR) signaling pathway, translation initiation, and protein synthesis in skeletal muscle of neonatal pigs. Considering that body weight can vary widely at birth, we sought to separate the effect of prematurity from birth weight on the anabolic response to feeding. MethodsPigs were delivered by cesarean section at preterm (103 d) or term (112 d) gestation and fed parenterally for 4 d. On day 4, pigs were fasted for 4 h and were either fasted one additional hour or fed by oral gavage, yielding four groups: 1) preterm fasted (PT-FAST); 2) preterm fed (PT-FED); 3) term fasted (T-FAST); and 4) term fed (T-FED). All pigs were injected with a flooding dose of L-[4-3H]Phe to determine fractional protein synthesis rates and euthanized 60 min after feeding or the additional fast. Pigs were stratified by birth weight such that the highest birth weight preterm pigs were compared with the lowest birth weight term pigs (n = 10–13 per group). ResultsDespite similar birth weight in preterm and term pigs (1035 vs 993 ± 54 g, P > 0.10), relative weight gain of preterm was 33% lower than term pigs (22.0 vs. 32.9 ± 1.6 g·kg–1·d–1, P < 0.001). Longissimus dorsi (LD), gastrocnemius, and diaphragm protein synthesis rates were not different between PT-FAST and T-FAST groups. Gastrocnemius protein synthesis was 18% lower in PT-FED than T-FED group (P < 0.01), but protein synthesis was not different between PT-FED and T-FED groups in LD and diaphragm muscles. The abundance of the active eIF4E·eIF4G complex and phosphorylation of 4E-BP1 and S6K1, readouts of mTOR activation and translation initiation signaling, were increased after feeding in all muscles (P < 0.001). Translation initiation signaling was lower in LD and gastrocnemius muscles in PT-FED than T-FED groups (P < 0.05) but was not different in diaphragm muscle (P > 0.10). ConclusionsThese findings imply that prematurity, independent of birth weight, blunts mTOR activation and protein synthesis after feeding. The blunted anabolic response to feeding likely underpins postnatal growth failure often observed in infants born preterm. Funding SourcesNIH and USDA.

PSVI-15 Impact of Solubility of Dietary Fiber Fed During the Pre-Farrow Period on Sow and Litter Performance in Lactation

Abstract This study evaluated the impact of level and solubility of dietary fiber on sow and litter performance when fed during the pre-farrowing period. Sows (n = 82) were assigned by BW to a 2×2 factorial arrangement plus a control treatment (regular lactation diet; 11.30% TDF) with the following factors: 1) High soluble dietary fiber (SDF; 6.0%) and insoluble dietary fiber (IDF; 31.10%); low soluble dietary fiber levels (SDF; 4.2%) and insoluble dietary fiber levels (IDF 28.30%) and 2) supplementation level of a fiber top-dress added to the lactation feed (0.45 vs 0.90 kg). The top-dress supplements were formulated to meet target fiber levels using sugar beet pulp and wheat middlings. Sows were transferred into the farrowing house at approximately 113 (±1d) d of gestation and experimental treatments were implemented from placement until parturition. Fiber solubility and top-dress level had no effects on sow BW during the pre-farrowing period and lactation (P &amp;gt; 0.05). Lactation length was unaffected by treatments (P = 0.57). Piglet birth weight (P = 0.35), stillborn pigs (P = 0.76), and number of pigs born below 0.90 kg (P=0.89) did not differ between treatments. Wean weight of piglets was not different between treatments (P = 0.84) but, insoluble fiber increased (P = 0.04) the number of small weaned pigs (less than 3.6 kg BW) irrespective of supplementation level (2.23 vs 1.10, and 0.37, for insoluble fiber, control, and soluble fiber, respectively). Results suggests that short-term supplementation of fiber immediately prior to farrowing and fiber solubility was not an effective strategy to improve sow performance during lactation.

122 Timing of Dietary Zinc Additions During Gestation for Improved Piglet Survival

Abstract Gestating sows (n = 267) were used to determine if timing of feeding elevated dietary zinc in a commercial setting would reduce pre-weaning mortality of piglets. Sows from 3 consecutive weekly farrowing groups were assigned randomly within parity to 1 of 3 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 d after breeding to farrowing; and 3) Day 110-to-Farrow (D110-to-F): as Control diet fed from breeding to farrowing + 2,715 ppm supplemental Zn as ZnSO4 (2,840 ppm total supplemental Zn) starting on d 110 of gestation until farrowing. The statistical model considered fixed effects of treatment, farrowing group, and the random effect of their interaction. Dietary treatments did not influence number of total pigs born or pigs weaned per litter (Table). No differences were observed for any piglet growth criteria evaluated across treatments (P &amp;gt; 0.05). For B-to-F sows, there was an increase in percent of pigs born alive compared with Control and D110-to-F sows (P = 0.002). Percentage of stillborn pigs tended to decrease for sows assigned to the B-to-F treatment (P = 0.052) compared with Control or D110-to-F sows. Feeding elevated zinc throughout gestation increased (P = 0.015) percentage of low-birth-weight pigs born alive compared with Control sows. Mortality of low-birth-weight piglets did not differ among treatments (P = 0.592). However, a trend for decreasing post-natal mortality (P = 0.065) of normal birth weight pigs was observed for pigs born to sows fed elevated zinc. The incidence of low-birth-weight pigs was higher (P &amp;lt; 0.001) for sows fed the D110-to-F treatment compared with Control sows. Overall, feeding elevated zinc to sows throughout gestation increased the proportion of pigs born alive and marginally increased survival of normal birth weight pigs.

Does weight matter? Exploring links between birth weight, growth and pig-directed manipulative behaviour in growing-finishing pigs

Damaging behaviour, especially tail and ear biting, are common problems in modern pig production. It has been suggested that a low birth weight could predispose pigs to become tail biters. Further, previous studies have shown somewhat contradictory links between growth rate and damaging behaviours, as well as resulting lesions. The aim of this study was to investigate, under practical farm conditions, if birth weight and growth of pigs are related to the risk for damaging behaviours and their outcomes, namely tail and ear lesions. A total of 386 pigs were followed from birth until the end of finishing period on four commercial farm pairs (piglet-producing and finishing farms). Based on birth weight, pigs were categorised as Small and Others, and pigs were weighed around weaning and in the growing and finishing units. At the two latter phases, they were scored for lesions and observed for pig- and environment-directed manipulative behaviour (PMB and EMB, respectively). PMB was not more common in Small than in Other pigs. However, PMB in the growing unit was positively associated with growth rate during suckling and growing periods (p = 0.04 and 0.05, respectively) and EMB was reduced in pigs with high growth rate (p = 0.02) in the finishing unit. Additionally, ear lesions in the growing unit were related to high growth rate in both the suckling (p = 0.03) and the growing period (p < 0.01). The current study shows no evidence that low birth weight predisposes to become a performer of damaging behaviours. Instead, a high growth rate in the suckling and growing period increased the risk for a high level of pig-directed manipulation as well as for becoming a victim of damaging behaviour in the growing unit. We suggest that this could be a consequence of increased feeding motivation in fast-growing pigs: they might experience more competition for feed, and consequently a higher level of stress, which predisposes to damaging behaviour.

Estimation of Genetic Parameters for Birth Weight, within Litter Variation of Birth Weight and Litter Size in Landrace and Yorkshire Pigs

Estimation of Genetic Parameters for Birth Weight, within Litter Variation of Birth Weight and Litter Size in Landrace and Yorkshire Pigs

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).

In Utero Fetal Weight in Pigs Is Regulated by microRNAs and Their Target Genes.

Impaired skeletal muscle growth in utero can result in reduced birth weight and poor carcass quality in pigs. Recently, we showed the role of microRNAs (miRNAs) and their target genes in prenatal skeletal muscle development and pathogenesis of intrauterine growth restriction (IUGR). In this study, we performed an integrative miRNA-mRNA transcriptomic analysis in longissimus dorsi muscle (LDM) of pig fetuses at 63 days post conception (dpc) to identify miRNAs and genes correlated to fetal weight. We found 13 miRNAs in LDM significantly correlated to fetal weight, including miR-140, miR-186, miR-101, miR-15, miR-24, miR-29, miR-449, miR-27, miR-142, miR-99, miR-181, miR-199, and miR-210. The expression of these miRNAs decreased with an increase in fetal weight. We also identified 1315 genes significantly correlated to fetal weight at 63 dpc, of which 135 genes were negatively correlated as well as identified as potential targets of the above-listed 13 miRNAs. These miRNAs and their target genes enriched pathways and biological processes important for fetal growth, development, and metabolism. These results indicate that the transcriptomic profile of skeletal muscle can be used to predict fetal weight, and miRNAs correlated to fetal weight can serve as potential biomarkers of prenatal fetal health and growth.

Identifying SNPs associated with birth weight and days to 100 kg traits in Yorkshire pigs based on genotyping-by-sequencing

Birth weight (BW) and days to 100 kg (D100) are important economic traits that are both affected by polygenes. However, the genetic architecture of these quantitative traits is still elusive. Genotyping-by-sequencing (GBS) data containing a large number of single nucleotide polymorphisms (SNPs) have become a powerful tool in genomic analysis. To better understand their complex genetic structure, a total of 600 Yorkshire pigs were sequenced using GBS technology. After quality control, 279 787 SNPs were generated for subsequent genome-wide association study (GWAS). A total of 30 genome-wide SNPs (P<1.79E–07) were identified for D100. Furthermore, a total of 22 and 2 suggestive SNPs (P<3.57E–06) were detected for D100 and BW, respectively. Of these, one locus located on SSC12 (position: 46 226 512 bp) were evaluated to affect both BW and D100 in Yorkshire pigs, indicating the pleiotropism in different traits. Considering the function of candidate genes, two genes, NSRP1 and DOCK7, were suggested as the most promising candidate genes involved in growth traits. Thus, use of GBS is able to identify novel variants and potential candidate genes for BW and D100, and provide an opportunity for improving pig growth traits using genomic selection in pigs.

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.

Comparison Of The Indigenous And Exotic Pure And Crossbred Sows In Southern Nigeria: Relationship Between Dam And Litter Performance

The study embraced the evaluation of reproductive efficiency of pure and crossbred exotic and indigenous sows of Nigeria. Characters studied were litter size at birth and weaning, survival at weaning, average pig weight, litter weights at 3,5 and 8 weeks of age and weight loss of the dams during lactation. Highly significant breed and seasonal effects were recorded in almost all traits studied on litter and piglet performance and the efficiency of milk utilization. No seasonal effect was reported for litter size, milk ingested per piglet and weight lost by the sow. Seasonal factors accounted for 0.43% of variation in litter size but 60.9% of litter weight. Breed differences accounted for 25.7% of birth weight and 59.8% of milk utilization efficiency and the sow age contributed 5.3% of pig birth weight and 36.0% of litter size variation. Pooled estimate indicated average pig birth weight of 1.14kg in the indigenous pigs and 1.54kg for the reciprocal Large White x Landrace piglets; average weaning weights ranged from 4.39 to 9.91kg and preweaning gain from 3.38 to 8.25kg respectively. Litter size at birth also varied from 5.2 in the landrace to 8.4 in the Duroc Large White cross with 4.6 and 7kg weights of pigs weaned respectively.

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.

273 Impact of either high energy or high SID Lys:ME on Parity 1 performance in lactation

Abstract Primiparous sows may have difficulty consuming sufficient feed during lactation to account for energy lost in milk production, development, and body maintenance. Addition of higher energy and/or higher standardized ileal digestible (SID) Lys may improve gilt and litter performance. One hundred seventy-two primiparous DNA F1 females were randomly allotted within breeding/farrowing group, previous treatment, and entry weight at farrowing to one of four dietary treatments. Treatments were arranged in a 2 x 2 factorial with energy (3186 and 3332 kcal/kg ME) and SID lysine (1.15 and 1.30%). Sows were weighed upon entry and exit of the farrowing room. Feed disappearance was calculated as the total amount of feed provided to the sow during lactation. A post-farrow weight model was utilized to assess true weight loss in lactation. Litters were standardized within 24 h of birth, and individual pig birth and weaning weights were recorded. The wean to estrus interval was also measured. Data were analyzed as a randomized complete block design with the fixed effect of treatment and the random effect of replicate. Addition of high energy and/or high lysine did not impact (P &amp;gt; 0.10) piglet wean weight or sow average daily feed intake. High energy diets reduced (P &amp;lt; 0.05) sow weight loss post-farrow by 15.5% from 8.75 to 7.39 kg. High SID lysine diets reduced (P &amp;lt; 0.05) number of sows not expressing estrus by day 9 post-wean from 13.0 to 7.7% of sows eligible for insemination. The high SID lysine diets targeted 70 g/d and led to an increase (P &amp;lt; 0.05) of 10.3% of sows displaying estrus on day 4 and 5. These data show that higher levels of SID lysine to target 70 g/d in lactation can improve wean to estrus interval, and potentially decrease non-productive sow days.

88 Benefits of increasing amino acid intake in late gestation in prolific sows

Abstract Most sows are fed a constant energy and amino acid supply throughout gestation, in line with the recommendations of most authorities and swine genetic companies. These recommendations for sow feeding have seen little change in decades, despite the many ways that sows have changed dramatically in reproductive performance. Beginning in about the year 2000, sow litter size has steadily increased as a result of genetic selection. With this increase in litter number has been a steady decline in birth weight, and the resulting negative effects of lower birthweight on subsequent piglet performance. Many experiments using so-called ‘bump’ feeding, or increased energy intake in late gestation, have been conducted in attempts to arrest this decline in birthweight and piglet performance. Generally, these experiments have shown little to no improvement in birthweight and often have negative effects on sow feed intake during gestation. These experiments have ignored the fact that the energy:amino acid ratios (lysine, threonine, isoleucine, tryptophan) in late gestation are different than during early and mid-gestation. In recent research in Australia we hypothesised that rapidly increasing essential amino acid levels in late gestation would increase birth weight and potentially improve subsequent reproductive performance. Three hundred and thirty-four multiparous PIC sows (average parity 3.6, average LW 261 kg) were housed in a dynamic gestation pen after mating and randomly assigned to one of two diet regimes. Two 13.5 MJ/kg DE gestation diets were formulated and created by blending in an ESF. The Control diet contained 0.48 g SID lysine per MJ DE and SID threonine, methionine+ cysteine, isoleucine and tryptophan at 68%, 65%, 58% and18% of SID lysine and offered at 2.2kg/day from d 28 to d 110. Sow were then moved to the farrowing house and placed on a lactation diet at 3.5kg/d. The Treatment diet contained 0.55 g SID lysine/MJ DE and SID threonine, methionine+cysteine, isoleucine and tryptophan at 78%, 65%, 60% and 20% of SID lysine and offered at 2.1kg/d from d 28 to d 85 and then increased to 2.4 kg/d to d 110 d. Increasing essential amino acid levels in late gestation increased gestational weight gain (5.6 kg, P=0.004), increased total litter birth weight (1.25 kg, P=0.003), and increased the birthweight of liveborn pigs from 1.286 to 1.329 kg, (P=0.04). There was no significant effect on the total number born or born alive. Piglet performance is not available because this commercial farm practices cross-fostering. Effects of continuation of this feeding regime in the same sows during subsequent parities is currently being evaluated.

100 President Oral Presentation Pick: Prematurity Blunts Protein Synthesis in Skeletal Muscle of Neonatal Pigs Independently of Birth Weight

Abstract Postnatal growth failure reduces lean mass accretion and increases adiposity. Previously we showed that preterm birth impairs the feeding-induced stimulation of mechanistic target of rapamycin (mTOR), translation initiation, and protein synthesis in skeletal muscle of neonatal pigs. Considering that pig body weight can vary widely at birth, we wished to differentiate the effect of prematurity versus BW on these responses. Pigs delivered by caesarean section at preterm (103 d) or term (112 d) gestation were fed parenterally for 4 d. On day 4, all pigs were fasted for 4 h and were either fasted one additional hour or fed an elemental meal by oral gavage, yielding four treatment groups: preterm fasted, preterm fed, term fasted, and term fed. A flooding dose of L-[4-3H]Phe was injected into pigs 30 min after feeding (30 min before euthanasia). Preterm and term pigs were stratified according to birth weight such that preterm pigs with the highest birth weight were compared to term pigs with the lowest birth weight (n = 10–13 per group). Despite similar birth weight of pigs in these two subgroups, relative body weight gain of preterm pigs was 33% lower than term pigs (22.0 vs. 32.9 ± 1.6 g·kg-1·d-1, P &amp;lt; 0.001). Gastrocnemius protein synthesis increased after feeding in both preterm and term pigs, but the increase was 18% lower in preterm than in term pigs pigs (Table 1). Feeding-induced AKT phosphorylation and mTOR-dependent 4EBP1 and S6K1 phosphorylation mirrored the pattern in protein synthesis. These results suggest that prematurity (rather than low birth weight, which is frequently associated with preterm birth) perturbs mTOR activation and protein synthesis after feeding. However, it is unclear whether an inadequate response to feeding also underpins poor growth in intrauterine growth restricted piglets. Research was supported by NIH and USDA.

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.

278 Feeding a whole-cell inactivated Pichia guilliermondi yeast to gestating and lactating sows over two consecutive parities

Abstract A total of 535 sows and their progeny (PIC 359×1050) were used to determine the effect of feeding gestating and lactating sows a proprietary strain of Pichia guilliermondi as a whole-cell inactivated yeast product (WCY; CitriStim, ADM Animal Nutrition, Quincy, IL) on sow and litter performance in a commercial production system. Within 24 hours of breeding, sows were allotted to 1 of 2 dietary treatments. Parity distribution was equalized across treatments. Sows were fed either a basal gestation control (CON) diet or CON fortified with 0.1% (0.91 kg/ton) of the WCY at the expense of corn throughout gestation. Sow dietary treatments were also maintained through lactation. Of the 535 sows that completed the initial reproductive cycle (cycle 1), 358 sows were maintained on dietary treatment and followed through a second gestation and lactation (cycle 2). The direction and magnitude of the differences in total born and born alive pigs in cycle 1 and cycle 2 was similar between treatments. Supplementing sows with WCY in cycle 1 increased the number of total born pigs by 0.59 pigs/litter (P=0.038) and tended to increase the number of pigs born alive by 0.52 pigs/litter (P=0.064) compared to CON fed sows. For cycle 2, the total number of born and born alive pigs numerically increased by 0.44 pigs/litter (P=0.180) and 0.43 pigs/litter (P=0.179) respectively for sows fed WCY. The distribution of pig birth weights was not different between treatments in cycle 1 (P=0.536) nor cycle 2 (P=0.256). Also, the litter growth rate on a weight gain per pig per day basis was not different between treatments in cycle 1 (P=0.103) nor cycle 2 (P=0.379). In conclusion, feeding gestating and lactating sows a proprietary strain of Pichia guilliermondi as a whole-cell inactivated yeast product significantly increased the number of total born pigs during cycle 1.

Effects of sire line, birth weight and sex on growth performance and carcass traits of crossbred pigs under standardized environmental conditions.

A variety of available terminal sire lines makes the choice of terminal sire line complex for the pig producer. Higher birth weights are important for subsequent growth performance and selection for this trait is also necessary in sire lines. The aim was to investigate the effect of sire line, birth weight and gender on growth performance, carcass traits and meat quality. In total 3844 crossbred pigs from Camborough Pig Improvement Company (PIC) dams matched with either a Synthetic (A) or Piétrain (B) sire line were used. Pigs from line A grew faster (), showed higher feed intake () and reached a higher final body weight (), but they had a similar efficiency (). Leaner carcasses and heavier primal cuts () were observed in pigs from line B. Carcasses from pigs sired by line A had higher meat quality (). Males had a higher growth rate () but had a poorer feed efficiency (). Heavier birth weight pigs and females had leaner, higher value carcasses with heavier primal cuts () compared to middle and low birth weight females or males. Sire line by sex interactions was significant for growth () and carcass traits (). Interaction between sire line and birth weight classes were only detected for loin depth (). Line A is preferable if the numbers of fatting pigs per fattening place and year should be improved, and line B is an option to increase leanness and carcass primal cuts.

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.