Within-litter Variation Research Articles

Effects of parity, season of birth, and sex on within-litter variation and pre-weaning performance of F1 Large White × Landrace pigs.

A piglet's pre-weaning performance significantly influences both animal welfare and profitability in pig production. Understanding piglet pre-weaning performance influencing factors is key to enhancing animal welfare, reducing losses, and boosting profitability. The study aimed to evaluate the impact of parity, season of birth, and sex on within-litter variation and pre-weaning performance of F1 Large White × Landrace pigs. Information regarding total litter size, number of born alive, number of stillbirths, piglet weight at birth, mortality, and count of weaned F1 Large White × Landrace piglets was acquired from the farm database (April 2022-February 2023). 2602 females and 2882 males, a total of 5484 piglets were utilized, with records from 360 sows. The coefficient of variation (CV) of birth weights among piglets within a litter was calculated. The general linear model analysis in MiniTab 17 was used to evaluate the data, with Fisher's least significant difference test (p < 0.05) used for mean separation and Pearson's moment correlation coefficient calculated to assess relationships between survival rates, mortality rates, litter size, birth weight, and birth weight CV. Parity had a statistically significant impact on litter size, birth weight, and survival rate (p < 0.05). The sow's parity did not significantly (p > 0.05) impact the number of piglets born alive or weaned. Multiparous sows had a significantly larger litter size (p < 0.05) than primiparous sows at birth. The litter weights for parities 2, 4, and 5 did not significantly differ (p > 0.05), with averages of 20.95, 20.74, and 20.03 kg, respectively. About 91.29% was the highest survival rate recorded in parity 2 (p < 0.05). The 1st week of life recorded an 8.02% mortality rate. The mortality rate in parity 3-5 group was significantly (p < 0.05) higher (11.90%) in week 1 than in the other groups (parity 1: 6.79%, parity 2: 5.74%, parity 3-5: 8.54 and 9.21%). The litter sizes in autumn (17.34) and spring (17.72) were significantly larger (p < 0.05) than those in summer (16.47) and winter (16.83). In autumn and spring, the survival rate (83.15 and 85.84%, respectively) was significantly lower (p < 0.05) compared to summer (88.40%) and winter (89.07%). In all seasons, the litter weights did not significantly differ (p > 0.05). The birth weight CV was significantly (p < 0.05) lower during summer (20.11%) than during spring (22.43%), autumn (23.71%), and winter (21.69%). The season of birth had no significant effect (p > 0.05) on the number of live piglets. Males (1.34 kg) were heavier (p < 0.05) than females (1.30 kg) at birth. Notably, the birth weight CV was similar between males (22.43%) and females (22.52%). Litter size was positively correlated with average litter weight (rp = 0.576, p < 0.001), birth weight CV (rp = 0.244, p < 0.001), and mortality rate (rp = 0.378, p < 0.001). An insignificant relationship was observed between average litter weight and birth weight CV (rp = -0.028, p > 0.05) and survival rate (rp = -0.032, p > 0.05). In F1 Large White × Landrace pigs, birth uniformity among piglets declines as litter size grows larger. In parity 3-5, multiparous sows yield litters with reduced uniformity. With an increase in litter size, uniformity among piglets at birth worsens. A larger litter size and greater piglet birth weight variation are linked to a higher pre-weaning mortality rate. Producers need a balanced selection approach to boost litter size and must cull aging sows carefully to introduce younger, more productive females.

Effects of Bacillus subtilis supplementation on reproductive parameters during late gestation in multiparous sows.

Probiotics are used at different stages of gestation to promote reproductive performance in sows. This study investigated the effect of Bacillus subtilis QST 713 supplementation during late gestation in multiparous sows on different reproductive parameters. On day 85 of gestation, 115 multiparous healthy Landrace Yorkshire sows were randomly assigned to two groups with equal parity numbers. The control group (58 sows) was fed with basal diets, and the probiotic group (57 sows) was fed with basal diets +1010 colony-forming unit (CFU) B. subtilis QST 713 from day 85 to parturition. Back fat thickness on days 85 and 110, number of total born, number of born alive, stillbirth and mummy rates, individual birth weight, litter birth weight, within-litter variation of piglet birth weight, and postpartum vaginal discharge duration were recorded and compared between the two groups. The number of total born, number born alive, back fat thickness of sows before farrowing, litter weight, within-litter variation of piglet birth weight, and postpartum vaginal discharge duration were similar in both groups (p > 0.05). Dietary supplementation with B. subtilis QST 713 decreased the stillbirth rate (3.96 vs. 6.39%, p = 0.046) and born dead rate (5.12 vs. 8.57%, p = 0.035) and increased the birth weight of piglets (1552.78 vs. 1506.15 g, p = 0.049). Daily supplementation with 1010 CFU of B. subtilis QST 713 during late gestation in multiparous sows could increase reproductive performance by increasing birth weight and decreasing stillbirth rate.

Effect of feeding sows a combination of extra vitamin B2, vitamin B6, vitamin B12, and folic acid during the first 45 days of gestation on piglet birthweight

The objective of this study was to test whether a high inclusion rate of dietary vitamin B2, B6, B12, and folic acid during the first 45 d of gestation could decrease within-litter variation in piglet birth weight and increase the average birth weight of the litter. Two hundred forty-one multiparous sows (Landrace x Yorkshire) were allotted to either a control or a B vitamin diet from mating to d 45 of gestation. The experimental unit was the sow or the litter. Sows in the control group were fed a standard gestation diet complying with Danish recommendations: 5.11, 3.07, 0.02, and 1.53 mg/kg for vitamin B2, B6, B12, and folic acid, respectively. Sows fed the B vitamin diet were fed the same standard gestation diet including an extra premix providing 232, 210, 1000, and 668 % extra vitamin B2, B6, B12, and folic acid, respectively. From d 46 until farrowing, all sows were fed the standard diet. The backfat thickness of sows was measured at farrowing and weaning in the previous cycle and at d 14, 45, and 112 of gestation. From a subsample of 10 second parity sows per treatment, blood samples were taken using jugular venipuncture into 10 mL EDTA tubes at weaning and d 14, 45, and 112 of gestation. The plasma was analyzed for the concentration of homocysteine. At farrowing, the number of live and stillborn piglets were recorded, and for a subsample of 71 (control) and 66 (B vitamin) sows, the weight, crown-rump length and abdominal circumference of individual piglets in the litters were measured. The plasma concentration of homocysteine at weaning and during gestation was unaffected by dietary treatments. For the overall treatments, there was no difference in live born (Control: 19.5; B vitamin: 19.9) and stillborn (Control: 1.5; B vitamin: 1.6) piglets between treatments. The average birth weight of live born (Control: 1,270 g; B vitamin: 1,245 g) and stillborn (Control: 992 g; B vitamin: 870 g) piglets and the within-litter variation in birth weight (Control: 294 g; B vitamin: 307 g) were unaffected by dietary treatment. The abdominal circumference (Control: 23.3 cm; B vitamin: 22.7 cm) and the crown-rump length (Control: 31.6 cm; B vitamin: 31.0 cm) were greater for piglets born to sows fed the control diet compared to sows fed the B vitamin diet (P < 0.05). In conclusion, there was no positive effect of supplementing surplus B vitamins above recommended inclusion rates to sows in early gestation on piglet birth weight.

The effect of dietary omega-3 fatty acid supplementation on fetal growth, piglet birth weight and plasma fatty acid concentrations, using docosahexaenoic acid in early gestation in sows

The objective of the study was to test the effect of the omega-3 fatty acid docosahexaenoic acid (DHA) on fetal and placental development as well as the birth weight of piglets. A total of 238 multiparous sows were allocated to either a control diet group or a DHA diet group with an omega-6 to omega-3 ratio of 9.8 and 2.4, respectively, from mating to day 43 of gestation. A blood sample was collected and back fat thickness was measured prior to mating, on days 14, 42 and 112 of gestation. On day 43 of gestation, 14 sows were slaughtered and measurements of fetuses and placentas were taken. Piglets in some litters were weighed individually at farrowing. Dietary treatment did not affect fetal characteristics and back fat thickness (P > 0.05). Dietary treatment increased the plasma concentrations of total omega-3 fatty acids in sows (P < 0.05). Sows fed the DHA diet had a shorter gestation length compared to the control sows (P < 0.05), but the number of born piglets was not affected (P > 0.05). The average piglet birth weight and the within-litter variation in birthweight were unaffected by dietary DHA (P > 0.05), however, sows fed DHA diet had fewer piglets under 800 g at birth compared to control sows (P < 0.05). In conclusion, addition of DHA decreased the dietary ratio of omega-6 to omega-3 fatty acids, increased plasma n-3 fatty acid concentrations in sows and decreased the number of piglets weighing under 800 g at birth.

Effect of increasing dietary methionine-to-lysine ratio during early gestation on fetal development and piglet birth weight

It was hypothesized that increasing dietary methionine (Met) for sows in early gestation would have a positive effect on fetal and placental growth and development, thereby also increasing the birth weight of piglets. The objective of the study was to investigate the effect of increasing the total dietary methionine-to-lysine ratio (Met:Lys) from 0.29 (Control diet) to 0.41 (Met diet) from mating to day 50 of gestation. A total of 349 multiparous sows were allocated to either the Control or Met diet group. The sows’ backfat thickness was measured pre-farrowing, post-farrowing, and at weaning in the previous cycle and on days 14, 50 and 112 of gestation in the current cycle. On day 50, three Control and six Met sows were slaughtered. In 116 litters, piglets were weighed and measured individually at farrowing. The dietary treatment did not affect the sows’ backfat thickness before or during gestation (P > 0.05). The number of liveborn and stillborn piglets at farrowing were similar in both groups (P > 0.05) and no differences in average piglet birth weight, total litter weight at birth or within-litter variation in birth weight (P > 0.05) were observed. In conclusion, increasing the dietary Met:Lys ratio for sows in early gestation had no effect on piglet birth weight.

Fetal and placental development in early gestation of hyper-prolific sows

Modern hyper-prolific sows produce large litters with a high within-litter variation in birth weight and an increased number of low-birth-weight piglets per litter with higher mortality rates and lower growth rates compared to heavier littermates. This study aimed to describe fetal development in hyper-prolific sows, to characterize differences between large and small fetuses, and to determine when within-litter variation in fetal weight can be detected. Forty-seven multiparous sows were blood-sampled and slaughtered at day 28, 33, 45, 50, and 56 of gestation. Number of fetuses were counted, fetal body and organ weights were measured, and the intrauterine positioning was recorded. Length, width, and area of each placenta was measured and the fetus weight/placental weight ratio was calculated. The umbilical cords of the smallest, medium and the largest fetus of each litter were sampled for histological analysis. In total measurements were obtained for 1161 fetuses. The results revealed no difference in fetal survival between the gestational days (P > 0.05). Intrauterine positioning near the cervix significantly reduced fetal weight at day 56 (P < 0.05). Total litter weight and average fetal weight increased with gestational age and individual fetal weight was negatively affected by litter size from day 33 and onwards (P < 0.05). The coefficient of variation for within-litter variation in fetal weight was higher at day 28 compared to the other gestational days (P < 0.05). Relative brain- and heart weights decreased from day 28–56 (P < 0.001). Small fetuses had relatively heavier brains and hearts at day 45, 50 and 56 (P < 0.001). Size of placenta, fetus weight/placental weight ratio and length of umbilical cord increased with gestational age (P < 0.001). There was a positive correlation between size of placenta and weight of individual fetus (P < 0.001), the weight of the fetus was positively correlated with umbilical cord length (P < 0.001) and the umbilical cross-sectional area was correlated to fetal weight at day 56 (P < 0.01). Individual fetal weight was positively correlated to the fetus weight/placental weight ratio (P < 0.001). In conclusion, fetal growth was affected by litter size, placental weight, and -area, and umbilical cord length. Lightweight fetuses were characterized by having placentas with lower weight and area and shorter umbilical cords. Lastly, within-litter variation in fetal weight was detectable at day 28, and the coefficient of variance remained stable from day 33–56.

Mechanisms regulating the initiation of porcine conceptus elongation.

Significant increases in litter size within commercial swine production over the past decades have led to increases in preweaning piglet mortality due to increase within-litter birthweight variation, typically due to mortality of the smallest littermate piglets. Therefore, identifying mechanisms to reduce variation in placental development and subsequent fetal growth are critical to normalizing birthweight variation and improving piglet survivability in high-producing commercial pigs. A major contributing factor to induction of within-litter variation occurs during the peri-implantation period as the pig blastocyst elongates from spherical to filamentous morphology in a short period of time and rapidly begins superficial implantation. During this period, there is significant within-litter variation in the timing and extent of elongation among littermates. As a result, delays and deficiencies in conceptus elongation not only contribute directly to early embryonic mortality, but also influence subsequent within-litter birthweight variation. This study will highlight key aspects of conceptus elongation and provide some recent evidence pertaining to specific mechanisms from -omics studies (i.e., metabolomics of the uterine environment and transcriptomics of the conceptus) that may specifically regulate the initiation of conceptus elongation to identify potential factors to reduce within-litter variation and improve piglet survivability.

P25. Increasing the dietary methionine-to-lysine ratio in early gestation of sows did not affect piglet birth weight and within-litter variation

P25. Increasing the dietary methionine-to-lysine ratio in early gestation of sows did not affect piglet birth weight and within-litter variation

Effects of Dietary Choline Levels During Pregnancy on Reproductive Performance, Plasma Metabolome and Gut Microbiota of Sows.

This study investigated the effects of dietary choline levels during gestation on reproductive performance of sows. In addition, the plasma metabolome and gut microbiota of sows was studied. A total of 260 multiparous sows were allocated to five dietary treatment groups with increasing choline concentrations (1,050, 1,450, 1,850, 2,250, and 2,650 mg/kg) in a randomized complete block design. The sows were fed experimental diets from breeding until farrowing and a common lactating diet during lactation. The results showed that the backfat (BF) gain of sows during gestation, individual birth weight for total piglets born, piglets born alive, average piglet weight at weaning increased linearly (P < 0.05), whereas the within-litter birth weight variation coefficient (CV) of piglets born alive and suckling piglet mortality decreased linearly (P < 0.05) as dietary choline level increased. A quadratic effect of dietary choline level was observed for the average daily feed intake (ADFI) of sows during lactation (P < 0.05). ADFI was maximized when the dietary choline concentration reached 1,910 mg/kg. Plasma H2O2 concentration at day 30 of gestation in the 1,050 mg/kg group was greater than that in the 1,850 and 2,650 mg/kg groups (P < 0.05). Plasma metabolomics identified 46 metabolites among the three groups. Specifically, plasma concentrations of trimethylamine-N-oxide (TMAO), dopamine, and L-proline increased while 1-methylhistidine concentration decreased as dietary choline levels increased. In addition, bacterial observed species and richness (Chao 1 and ACE) at day 110 of gestation decreased as dietary choline levels increased (P < 0.05). For the gut microbiota composition, the enhanced dietary choline level decreased the abundance of phylum Proteobacteria (P < 0.05) and increased the abundance of phylum Actinobacteria (P < 0.05) at day 30 of gestation. Compared with the 1,050 mg/kg group, the abundance of genus Terrisporobacter was less in the 1,850 mg/kg group, and genera Bacillus and Cellulomonas were greater in the 2,650 mg/kg group. In summary, increasing dietary choline levels improved the birth weight, uniformity of neonatal piglets and litter performance during lactation. This may be associated with better antioxidant capability, metabolic status, and gut microbiota of sows during gestation.

Identifying Risk Factors for Low Piglet Birth Weight, High Within-Litter Variation and Occurrence of Intrauterine Growth-Restricted Piglets in Hyperprolific Sows

Simple SummaryPiglet mortality is an ongoing concern for pig production worldwide. Piglets that have a low piglet birth weight (PBW), suffer from intrauterine growth restriction (IUGR) or are born from litters with a high within-litter variation in PBW (CVPBW) have an increased risk of dying before weaning. IUGR piglets, CVPBW and a low PBW might be connected by the same risk factors, and in order to optimize fetal development in the litter, these risk factors should be identified. Free-access stall feeding, floor feeding and electronic sow feeding systems are commonly used feeding systems for gestating sows in Denmark. These systems differ in several points, including in sow competition at feeding. The nutritional status of the sow is important for fetal development, and so the feeding method during gestation is also expected to affect such development. Of the risk factors identified in this study, increasing litter size was considered the most critical. Only small differences were found between the feeding systems and these differed amongst groups. The results should inspire further investigation of those risk factors to clarify causes of the observed effects and what drives individual herd differences.This study aimed to identify risk factors affecting PBW, high CVPBW and the occurrence of IUGR piglets in 12 commercial Danish herds with hyperprolific sows using free-access stalls, floor or electronic sow feeding systems in the gestation unit. The following factors were investigated: the duration of previous lactation, the length of the interval from weaning to insemination, the length of gestation, litter size, parity, sow backfat thickness in late gestation and the type of feeding system in the gestation unit. The study included newborn piglets from 452 litters with the following production indicator averages: 21.3 piglets/L, 1235 g PBW, 22.9% CVPBW and 10.9% and 11.8% within-litter occurrence of severe and mild IUGR piglets, respectively. Increasing length of weaning-to-insemination interval decreased PBW by 25.8 g/day. For 2nd to 9th parity sows, each additional piglet in the litter increased CVPBW by 0.38%, the occurrence of severe IUGR piglets by 0.68% and mild IUGR piglets by 0.50%. Sows of 5th parity and older had a 1.39% higher CVPBW and 49.1 g lighter piglets compared with sows of 2nd to 4th parity. PBW was lower in one ESF herd, suggesting complex interactions that need to be further elucidated. The main critical risk factor observed was litter size.

Effect of litter birth weight standardization before first suckling on colostrum intake, passive immunization, pre-weaning survival, and growth of the piglets

Within-litter variation in birth weight is a relevant factor in pig production. This study aimed at comparing pre-weaning mortality, colostrum intake (CI), passive immunization, and growth of piglets from litters of uniform (UN) or heterogeneous (HET) birth weights. The study included 52 multiparous sows (Large White × Landrace) and their litters. Two types of litters were constituted based on birth weight, namely: UN or HET, the control group, using piglets from two to three sows farrowing approximately at the same time. At birth, piglets were weighed, identified, and placed in a box under an IR lamp. At the end of farrowing, piglets were re-weighed and allotted to groups UN or HET (12 per litter) with average weights of 1394 and 1390 g, respectively, and allowed to suckle (time 0). They were re-weighed 24 h later to estimate CI and sows' colostrum yield. At time 0, the average intra-litter CV (%) in weight of experimental litters were 9.3 ± 0.8 (SEM) and 27.8 ± 0.7 in groups UN and HET, respectively (P < 0.001). At 2 days of age, blood samples were taken from the piglets of 11 litters five UN and six HET) and serum Immunoglobulin G (IgG) contents were determined. Mean CI/piglet/litter was similar in both groups, that is, 415 ± 13 in UN and 395 ± 13 g in HET (P = 0.28), but was less variable in UN litters (CV = 22.4 ± 2 vs 36.0 ± 2%, P < 0.001). The IgG levels at 2 days of age were higher in piglets from UN litters (22.5 ± 0.8 vs 18.4 ± 0.7 g/l; P < 0.001) but the CV of IgG levels was not different between litter type (P= 0.46). Mortality up to 21 days of age was lower in UN litters (6.4 vs 11.9%, P = 0.03). The BW at 21 days was not different between litter type (P = 0.25) but it was less variable among piglets from UN litters (CV: 17.1 ± 1.3 vs 25.7 ± 1.3%; P = 0.01). Results reveal that CI is less variable and mortality is lower in piglets from litters of UN birth weight. The results infer that genetic improvement to decrease variation in birth weight within-litter could have a positive effect on homogeneous CI and thus contribute to reducing piglet mortality.

Effect of rearing cross-fostered piglets in litters of either uniform or mixed birth weights on preweaning growth and mortality.

Cross-fostering is a practice commonly used in the swine industry to equalize litter sizes, however, there is limited understanding of the optimum cross-fostering methods that will maximize piglet preweaning growth and survival. This study evaluated the effects of within-litter variation in birth weight after cross-fostering on piglet preweaning mortality (PWM) and weaning weight (WW) using litters of 15 piglets. A hierarchical incomplete block design was used (blocking factors: day of farrowing and sow parity, body condition score, and number of functional teats) with a 3 × 2 factorial arrangement of treatments: 1) Birth Weight Category (BWC): Light (<1.0 kg), Medium (1.0 to 1.5 kg), or Heavy (1.5 to 2.0 kg); 2) Litter Composition: UNIFORM (all 15 piglets in each litter of the same BWC), or MIXED (five piglets in each litter from each BWC, i.e., five Light, five Medium, and five Heavy piglets). At 24 h after birth, piglets were weighed and randomly allotted to litter composition treatments from within BWC. The experimental unit was five piglets of the same BWC; there were three experimental units within each Litter Composition treatment litter. There were 17 blocks, each of six litters (one UNIFORM litter of each BWC; three MIXED litters) and 51 replicates (three replicates per block of six litters) for a total of 102 cross-fostered litters and 1,530 piglets. Piglets were weaned at 19.7 ± 0.46 d of age; WW and PWM were measured. PROC GLIMMIX and MIXED of SAS were used to analyze PWM and WW, respectively. Models included BWC, Litter Composition, the interaction, and replicate within the block. There were BWC by Litter Composition treatment interactions (P ≤ 0.05) for PWM and WW. Preweaning mortality was greater (P ≤ 0.05) for Light piglets in MIXED than UNIFORM litters. In contrast, for Heavy piglets, PWM was greater (P ≤ 0.05) and WW was lower (P ≤ 0.05) in UNIFORM than MIXED litters. Medium piglets had similar (P > 0.05) PWM and WW in UNIFORM and MIXED litters. The results of this study, which involved large litter sizes typical of current commercial production, suggested that for piglet survival to weaning, using cross-fostering to form litters of piglets of similar birth weight was beneficial for light piglets, detrimental for heavy piglets, and neutral for medium piglets.

84 Effect of rearing cross-fostered piglets in litters of either uniform or mixed birth weights on pre-weaning performance

Abstract There is limited understanding of optimum cross-fostering methods to use to maximize piglet performance. This study evaluated effects of within-litter birth weight variation after cross-fostering on pre-weaning piglet removals (PR; morbidity and mortality) and ADG. A hierarchical incomplete block design was used (blocking factors day of farrowing and sow parity and structure) with a 3x2 factorial arrangement of treatments: 1) Birth Weight Category (BWC): Light (&amp;lt; 1.0 kg), Medium (1.0-1.5 kg), or Heavy (1.5-2.0 kg); 2) Litter Composition (LC): Uniform (piglets of the same BWC), and Mixed (equal numbers of piglets from each BWC). Piglets were weighed 24 h after birth and allotted to form litters of 15 cross-fostered piglets. The experimental unit was 5 piglets of the same BWC (3 experimental units per litter). A total of 102 litters were allotted to 17 blocks of 6 litters (1 Uniform litter of each BWC; 3 Mixed litters) with 51 replicates (3 replicates/block of 6 litters). Weaning weights and PR were measured. PROC GLIMMIX and MIXED of SAS were used to analyze PR and other data, respectively. Models included BWC, LC, the interaction, and replicate within block. There were treatment interactions (P &amp;lt; 0.05) for all measures except birth weight. There was no effect (P &amp;gt; 0.05) of LC on weaning weight or ADG for Light or Medium piglets; Heavy piglets had greater (P &amp;lt; 0.05) weaning weight and ADG in Mixed than in Uniform litters. PR were greater (P &amp;lt; 0.05) for Light piglets in Mixed than in Uniform litters, and for Heavy piglets in Uniform than in Mixed litters. PR for Medium piglets were similar (P &amp;gt; 0.05) across LC treatments. In conclusion, rearing cross-fostered piglets in Uniform litters reduced PR for Light piglets, but increased PR and reduced ADG of Heavy piglets, with no effect for Medium piglets.

Effects of Maternal Supplementation with Rare Earth Elements during Late Gestation and Lactation on Performances, Health, and Fecal Microbiota of the Sows and Their Offspring.

Simple SummaryThe immunological and metabolic status of breeding sows directly affect the overall productivity of porcine operations. Especially, maternal health status during the transition from gestation to lactation are important in maintaining health and growth of the suckling piglets. Rare earth elements (REEs) have been considered as a promising natural feed additive and been reported to exert their activity locally within the gastrointestinal tract, including effects on the bacterial microflora and on nutrient utilization. The present study was conducted to explore the effects of dietary maternal REE supplementation during late gestation and lactation on sows and their offspring. After the experiment, we found that maternal REE addition enhanced antioxidant activity and immunity of sows and their suckling piglets. At the same time, REE supplementation during perinatal period improved the reproductivity of the sows as well as the growth of their offspring. Besides, maternal REEs supply altered the intestinal microbiota community and composition of sows as well as their offspring, and Spearman correlation analysis shows that fecal bacteria are associated with the antioxidase, inflammatory factors of the sows and offspring as well as average daily gain of the suckling piglets. In addition, our results suggested that REE supplementation during both gestation and lactation are more beneficial to sows and their offspring than supplementation during only late gestation. This paper holds promise in providing efficient feeding strategies in swine production.The study was conducted to investigate the effects of maternal supplementation with rare earth elements (REEs) on sows and their offspring. During late gestation, 120 multiparous sows were divided randomly into the control group (Basal diet) and REE-G group (Basal diet supplemented with 200 mg REE/kg). After delivery, REE-G group was further divided into two groups: REE-L- (Change to basal diet during lactation) and REE-L+ group (REE diet all the time). Our results showed that maternal REE supplementation improved the antioxidant and immunity of sows and piglets. Additionally, REE supply during late gestation significantly decreased the coefficient of within-litter variation (CV) in birth weight and increased the weaning weights and the average daily gain (ADG) of piglets. During lactation, the insulin-like growth factor-1 (IGF-1) levels in piglets of REE-L+ group were higher, while no difference between REE-L- and the control group. More beneficial bacteria (Christensenellaceae and Ruminococcaceae) were found in the REE-L+ group while some opportunistic pathogens (Proteobacteria and Campylobacter) were relatively suppressed. Fecal microbiota showed correlation with antioxidase, inflammatory factors, and average daily gain (ADG). Collectively, our findings indicated that REEs added in both gestation and lactation was more conducive to establish a healthier status for sows and their offspring.

56 Observations on pre-weaning piglet mortality

Abstract Pre-weaning piglet mortality (PWM) is a substantial economic loss and a welfare concern. It is not a new issue; however, there is evidence that levels are increasing in US herds. Genetic improvements in prolificacy have been accompanied with lower average piglet birth weights, increased within-litter variation in birth weight, and an increasing proportion of low birth weight piglets. Low birth weight is a major pre-disposing factor for PWM. In a survey involving over 11,000 piglets (average birth weight 1.44 ± 0.390 kg), PWM for piglets weighing 1.5 kg was 44, 15, and 8%, respectively. However, the percentage of total mortality from these 3 weight groupings was 35, 42, and 23%, respectively. This suggests that efforts to reduce PWM should mainly focus on lightest 50% of piglets in a population. The major causes and timing of PWM have not changed over time. Crushing and starvation are predominant; the majority of losses occur in the first few days after birth. A substantial proportion of dead piglets have empty stomachs. Pre-weaning mortality is multifactorial in origin; reducing levels requires attention to all factors, starting with farrowing accommodation design and basic facility hygiene programs. Minimizing piglet body temperature decline after birth, and encouraging early colostrum and milk intake are critical. Strategies to reduce competition between piglets for access to the udder and/or supplementary feeding programs are important. Cross-fostering is central to maximizing piglet survival; however, there is a dearth of research-based information to use to design the optimum strategy. The potential influence of gestation nutrition on PWM requires clarification. Pre-weaning mortality is strongly influenced by the people managing the farrowing facilities; developing approaches for early identification of at risk pigs would have benefit. Ultimately, minimizing PWM requires systems-based approaches involving all components from genetic selection for survival through to facility and animal management practices.

Beta-hydroxy-beta-methylbutyrate (HMB) Supplementation to Mouse Dams in Gestation Does Not Affect Fetal Weight Variation of Offspring or Placental Development (P09-003-19)

ObjectivesThe objective of this study was to determine if supplementing mouse dam diets with β-hydroxy-β-methylbutyrate (HMB) calcium salt throughout gestation would improve pup fetal weight uniformity and placental development. MethodsData were collected from 27 genetically identical mouse dams and their offspring. Dams were assigned to one of 4 dietary treatments: Control (CON; n = 7), Low HMB (LHMB; 3.5 mg/g diet; n = 6), High HMB (HHMB; 35 mg/g diet; n = 7), and low HMB pulse dose (PUL; 3.5 mg/g diet; n = 7) from days 6 to 10 of gestation. All dams were fed a swine lactation derived corn-soy diet with HMB supplementation only during gestation. Dams were euthanized on day 18 of gestation. ResultsDietary treatment did not affect total number of pups per litter, but fetal weight was greater (P < 0.05) for pups from PUL dams (1.05 ± 0.02 g) than LHMB (0.94 ± 0.02 g) or HHMB (0.95 ± 0.02 g) dams. Within-litter variation (standard deviation and coefficient of variation) and range of fetal weights was not different among treatments. Differences between the median fetal weight within litter and weight of the lowest weight fetal pup in each litter were similar among treatments. Supplementation with HMB did not influence weight of placentae or area of the placental labyrinth. Placental efficiency, measured as fetal weight/placental weight, was less (P < 0.05) for LHMB dams compared to CON dams. ConclusionsIn conclusion, dietary supplementation of HMB for pregnant mice had no effect on fetal weight variation within litter. Supplementing diets with β-hydroxy-β-methylbutyrate had no effect on placental weight or labyrinth area but reduced placental efficiency in dams fed LHMB. Funding SourcesThis research has been supported and funded by BioMatrix International, Princeton, MN.

Follicular development of sows at weaning in relation to estimated breeding value for within-litter variation in piglet birth weight

In this study we aimed to identify possible causes of within-litter variation in piglet birth weight (birth weight variation) by studying follicular development of sows at weaning in relation to their estimated breeding value (EBV) for birth weight variation. In total, 29 multiparous sows (parity 3 to 5) were selected on their EBV for birth weight variation (SD in grams; High-EBV: 15.8±1.6, N=14 and Low-EBV: −24.7±1.5, N=15). The two groups of sows had similar litter sizes (15.7 v. 16.9). Within 24 h after parturition, piglets were cross-fostered to ensure 13 suckling piglets per sow. Sows weaned 12.8±1.0 and 12.7±1.0 piglets, respectively, at days 26.1±0.2 of lactation. Blood and ovaries were collected within 2 h after weaning. The right ovary was immediately frozen to assess average follicle size and percentage healthy follicles of the 15 largest follicles. The left ovary was used to assess the percentage morphologically healthy cumulus-oocyte complexes (COCs) of the 15 largest follicles. To assess the metabolic state of the sows, body condition and the circulating metabolic markers insulin, IGF1, non-esterified fatty acid, creatinine, leptin, urea and fibroblast growth factor 21 were analysed at weaning. No significant differences were found in any of the measured follicular or metabolic parameters between High-EBV and Low-EBV. A higher weight loss during lactation was related to a lower percentage healthy COCs (β= −0.65, P=0.02). Serum creatinine, a marker for protein breakdown, was negatively related to average follicle size (β= −0.60, P=0.05). Backfat loss during lactation was related to a higher backfat thickness at parturition and to a higher average follicle size (β=0.36, P<0.001) at weaning. In conclusion, we hypothesise that modern hybrid sows with more backfat at the start of lactation are able to mobilise more energy from backfat during lactation and could thereby spare protein reserves to support follicular development.

L-arginine supplementation in sow diet during late gestation decrease stillborn piglet, increase piglet birth weight and increase immunoglobulin G concentration in colostrum

The fetal growth is rapid during the last trimester of gestation in sows and hence sow nutrition during this period is important for fetal growth and development. During the last decade, studies reported that l-arginine HCl supplementation during gestation increased sow and piglet performances. However, clinical studies concerning the association between l-arginine HCL supplementation and some neonatal piglet characteristics as well as colostrum and milk yield of sow are still lacking. The present study aims to determine the effect of l-arginine HCl supplementation in sow diet during late gestation on piglet characteristics at birth, colostrum consumption (CC), concentration of immunoglobulin G (IgG) in colostrum, milk yield, average daily gain at d 7 and 21 and piglet mortality at d 7 and 21 of life. In total, 166 sows were allocated into four groups, i.e., CON (n = 66), ARG-0.5 (n = 42), ARG-1.0 (n = 41) and ALA (n = 17). The sows in each group were fed with a conventional gestation diet (CON) or the same diet supplemented with 0.5% l-arginine HCl (ARG-0.5), 1.0% l-arginine HCl (ARG-1.0) or 1.7% l-alanine (ALA, isonitrogenous with ARG-1.0). The feeding protocol was carried out from 85 days of gestation until farrowing. The proportion of live-born piglets, piglet birth weight (BWB), within-litter variation of BWB, proportion of piglets with BWB above 1.35 kg, proportion of growth-restricted piglets (defined as BWB below 1.0 kg), blood oxygen saturation (SatO2) and heart rate were determined in 2292 newborn piglets from 166 litters. Colostrum consumption of each individual piglets and the colostral concentration of IgG was determined. The milk yield between d 0–7 and 7–21 and relative backfat loss were estimated in each individual sow. The piglet mortality and body weight was determined at d 7 and 21 of life. On average, the number of piglet born alive per litter was 12.4. The proportion of stillborn piglets, piglets with BWB above 1.35 kg and growth-restricted piglets were 6.9%, 62.7% and 14.0%, respectively. Piglet preweaning mortality at d 7 and 21 were 8.5% and 12.4%, respectively. Compared to the ALA group, ARG-0.5 increased the proportion of live-born piglets per litter (+9.8%, P < 0.001), reduced stillborn (−8.3%, P < 0.001) and tended to increase the proportion of piglets with BWB above 1.35 kg (+6.4%, P = 0.08). Compared to the CON group, ARG-0.5 increased BWB (+7.0%, P < 0.001), increased SatO2 (+3%, P < 0.001) and reduced heart rate (−20%, P < 0.001) and tended to reduce the relative backfat loss (−4.4%, P = 0.06). No difference between ARG-1.0 and ARG-0.5 was observed among these traits. Other traits including within-litter variation of BWB, growth-restricted piglets, average daily gain, piglets preweaning mortality and CC and milk yield were not affected by treatment (P > 0.05). The colostral concentration of IgG at 1 h after onset of farrowing in ARG-1.0 sows (116 mg/ml) was higher than CON, ARG-0.5 and ALA sows (85, 74 and 78 mg/ml, respectively; P < 0.05). In conclusions, dietary l-arginine HCl supplementation in late gestating sows favourably increased proportion of live-born piglets, BWB, SatO2 and IgG concentration in the sow colostrum.

Individual differences in early body mass affect thermogenic performance and sibling interactions in litter huddles of the house mouse

We asked whether within-litter differences in early body mass are associated with differences in house mouse pups' thermogenic performance and whether such variation predicts individual differences in competitive interactions for thermally more advantageous positions in the huddle. We explored pups' thermogenic performance in isolation by measuring changes in (maximal) peripheral body temperatures during a 5-min thermal challenge using infrared thermography. Changes in peripheral body temperature were significantly explained by individual differences in body mass within a litter; relatively lighter individuals showed an overall quicker temperature decrease leading to lower body temperatures toward the end of the thermal challenge compared to heavier littermates. Within the litter huddle, relatively lighter pups with a lower thermogenic performance showed consistently more rooting and climbing behavior, apparently to reach the thermally advantageous center of the huddle. This suggests that within-litter variation in starting body mass affects the pups' thermal and behavioral responses to environmental challenges.

Maternal L-glutamine supplementation during late gestation alleviates intrauterine growth restriction-induced intestinal dysfunction in piglets.

Maternal dietary supplementation with L-glutamine (Gln) has been considered as an option to improve fetal growth and to prevent the occurrence of intrauterine growth restriction (IUGR). This study investigated whether maternal Gln supplementation could improve fetal growth as well as the intestinal development during late pregnancy. Sixty pregnant Landrace × Large White multiparous sows were assigned to two groups, either the group fed the control diet or the group with the diet supplemented with 1% Gln from d 85 of gestation until farrowing. One normal body weight piglet and one IUGR piglet were obtained from six litters in each group. Reproductive performance, plasma concentrations of free amino acids and related metabolites as well as piglet growth and tissue indexes were determined. Maternal Gln supplementation during late gestation increased the average birth weight, while decreasing the within-litter variation of newborn piglets. The concentrations of Gln in plasma were lower in IUGR piglets than in normal piglets. Glutamine supplementation enhanced Gln concentrations in maternal and piglet plasma and the piglet jejunum, compared with the Control group. Supplementing Gln suppressed intestinal miR-29a levels, and increased the abundance of extracellular matrix (ECM) and tight junction (TJ) proteins, resulting in increased intestinal weight and improved morphologies of the piglets. Collectively, Gln supplementation to the sow's diet increased fetal growth, decreased the within-litter variation of newborn piglets, and alleviated the IUGR-induced intestinal impairment. These findings suggest the possibility of maternal glutamine supplementation in the prevention and treatment of IUGR in animal production and human medicine.