Genetic parameters for within-litter variation in piglet birth weight and change in within-litter variation during suckling

The objective of this study was to ascertain whether maternal additive genetic variance exists for within-litter variation in birth weight and for change in within-litter variation in piglet weight during suckling. A further objective was to estimate maternal genetic correlations of these two traits with mortality, birth weight, growth, and number of piglets born alive. Data were obtained from L?vsta research station, Swedish University of Agricultural Sciences, and included 22,521 piglets born in 2,003 litters by 1,074 Swedish Yorkshire sows. No cross fostering was used in the herd. The following seven traits were analysed in a multivariate animal (sow) model: number of piglets born alive, within-litter SD in birth weight, within-litter SD in piglet weight at 3 wk of age, mean weight at birth, mean weight at 3 wk of age, proportion of stillborn piglets, and proportion of dead piglets during suckling. Maternal genetic variance for the change in within-litter SD in piglet weight during suckling was assessed from the estimated additive genetic covariance components by conditioning on within-litter SD in birth weight. Similarly, mean growth of piglets during suckling was assessed from the additive genetic covariance components by conditioning on mean weight at birth. The heritability for within-litter SD in birth weight was 0.08 and 0.06 for within-litter SD in piglet weight at 3 wk. The genetic correlation between these two traits was 0.71. Little maternal genetic variance was found for the change in within-litter SD in piglet weight during suckling, and opportunity for genetic improvement of this trait by selective breeding seems limited. The genetic correlation of within-litter SD in birth weight with proportion of dead piglets during suckling was 0.25 and of within-litter SD in birth weight with mean growth of piglets was -0.31. The maternal genetic variance and heritability found for within-litter SD in birth weight indicates that genetic improvement of this trait by selective breeding is possible. In addition, selection for sows' capacity to give birth to homogeneous litters may be advantageous for piglet survival, piglet growth, and litter homogeneity at weaning.     

Between-breed variability of stillbirth and its relationship with sow and piglet characteristics

Litter characteristics at birth were recorded in 4 genetic types of sows with differing maternal abilities. Eighty-two litters from F(1) Duroc x Large White sows, 651 litters from Large White sows, 63 litters from Meishan sows, and 173 litters from Laconie sows were considered. Statistical models included random effects of sow, litter, or both; fixed effects of sow genetic type, parity, birth assistance, and piglet sex, as well as gestation length, farrowing duration, piglet birth weight, and litter size as linear covariates. The quadratic components of the last 2 factors were also considered. For statistical analyses, GLM were first considered, assuming a binomial distribution of stillbirth. Hierarchical models were also fitted to the data to take into account correlations among piglets from the same litter. Model selection was performed based on deviance and deviance information criterion. Finally, standard and robust generalized estimating equations (GEE) procedures were applied to quantify the importance of each effect on a piglet's probability of stillbirth. The 5 most important factors involved were, in decreasing order (contribution of each effect to variance reduction): difference between piglet birth weight and the litter mean (2.36%), individual birth weight (2.25%), piglet sex (1.01%), farrowing duration (0.99%), and sow genetic type (0.94%). Probability of stillbirth was greater for lighter piglets, for male piglets, and for piglets from small or very large litters. Probability of stillbirth increased with sow parity number and with farrowing duration. Piglets born from Meishan sows had a lower risk of stillbirth (P < 0.0001) and were little affected by the sources of variation mentioned above compared with the 3 other sow genetic types. Standard and robust GEE approaches gave similar results despite some disequilibrium in the data set structure highlighted with the robust GEE approach.     

The influence of suckling interval on milk production of sows

The objective of this study was to determine whether sow milk yield per gland could be increased by reducing the interval between suckles (suckling interval). Eighteen sows were allocated at their first farrowing to three treatments comprising litter sizes of 6 or 12 piglets or a cross-suckling treatment that was imposed to increase suckling frequency. The cross-suckled treatment comprised two groups of six piglets each. Each suckling group was allowed to suckle the sow during 30-min intervals each day between d 6 and d 28 of lactation. The suckling interval was shorter (P < .05) for cross-suckled sows than for sows suckling single litters of 6 or 12 piglets during early lactation (d 10 to 14) and late lactation (d 24 to 28). Average piglet growth rate between birth and 28 d of age was greatest (P < .05) for piglets in the single litters of six and lowest for piglets in the cross-suckled treatments. Single litters of 12 piglets had the highest (P < .05) litter growth rates, followed by the cross-suckled litters and then the single litters of six piglets. The concentration of lactose and fat in milk from sows remained relatively stable, although milk from the cross-suckled sows contained more protein in early lactation (P < .05). Milk yield of sows was not significantly increased (P > .05) by the cross-suckle treatment, although during early lactation, milk yield tended to be greater from sows in the cross-suckle treatment than from sows suckling single litters of six (8,920 g/d vs 7,819 g/d, P < .1). The concentration of DNA and total RNA and the RNA:DNA ratio in mammary glands was unaffected by treatment (P > .05). Sows with single litters of 12 piglets had the greatest total DNA in their udders (P < .05). However, individual gland weights were heavier (P < .05) in cross-suckled sows than in sows with single litters of 6 or 12 piglets. Increased suckling frequency seemed to play a role in increased mammary gland weight and milk production during lactation.     

五指山猪的泌乳性能及泌乳行为

为了研究五指山小型猪的泌乳性能及泌乳行为,试验测定了8头初产五指山母猪初乳(≤3d)常规成分含量、泌乳行为及第3、13、24和35d的泌乳量。结果表明:①五指山猪初乳(≤3d)中的脂肪、蛋白、乳糖和总固形物的含量分别为(6.64±0.56)%、(15.25±1.27)%、(1.99±0.15)%、(27.46±1.25)%。②随产后日龄的增加,母猪泌乳次数和泌乳持续时间逐渐减少,表现为泌乳次数第35日龄比第3和13日龄均少5.14次/d(P<0.05),且下午(12:00￣20:00)比晚上(20:00￣04:00)多1.46次(P<0.05);泌乳持续时间第24日龄显著短于第3日龄(P<0.05);日龄与日泌乳时段对泌乳次数和泌乳持续时间无显著交互作用(P>0.05)。③母猪分娩后0～35d的全期泌乳量和日平均泌乳量分别为31528.59g和900.82g,且第35日龄泌乳量显著高于第3和第24日龄泌乳量(P<0.05);日龄与日泌乳时段对泌乳量无显著交互作用(P>0.05);35d哺乳期内每窝仔猪每克初生体重日耗乳量0.94g,若以普通肉用型猪每窝每克初生体重日耗乳量0.50￣0.99g为参考值,则说明五指山母猪泌乳量充足。本试验结果表明,五指山母猪分泌的初乳干物质含量高、乳糖含量低,分娩后(35d泌乳期内)泌乳量能充分满足仔猪的维持和生长需要。     

母乳能量水平对仔猪生长的影响及其分子机理

母体是仔猪胚胎期和初生时唯一的营养来源,也是哺乳期主要的营养源。妊娠期和泌乳期母体的营养和体况不仅影响繁殖性能和泌乳性能而且直接决定仔猪的生长。妊娠期添加纤维日粮能升高母猪血液VFA浓度,特别是乙酸浓度,它可以直接合成乳脂,提高乳汁能量。在妊娠后期和哺乳期调整母猪饲料组成可以改善产奶量和乳成分,从而影响仔猪生长性能。本文从仔猪的生理特点、日粮养分尤其是纤维和脂肪对母猪泌乳、繁殖性能和仔猪生长的影响以及调控仔猪生长的分子机理等方面进行了综述。     

Potential effect of two Bacillus probiotic strains on performance and fecal microbiota of breeding sows and their piglets

The effect of long-term administration of two Bacillus strains was tested on 98 breeding sows and their litters allotted into three treatments: a control group (CON); supplemented with 5 × 10⁸ cfu/kg B. subtilis − 541 (BSU); or with 5 × 10⁸ cfu/kg B. amyloliquefaciens − 516 (BAM). Reproductive and performance variables were recorded over three cycles with 56 dams remaining through the third lactation. Blood and fecal samples were taken longitudinally from 12 sows per treatment on days 8 and 21 of the third lactation and milk samples were taken on day 21. Feces from one piglet per litter was sampled on days 21 and 33 and jejunal gene expression was assessed in two piglets on day 21. Changes in fecal microbiota were assessed by 16S rRNA gene sequencing (Illumina MiSeq) and gene expression by Open-Array technology. Metabolomic responses were analyzed in milk by NMR and Ig-G and Ig-A specific antibodies were determined by ELISA. No significant differences were observed on feed intake, body weight, or fat mobilization of the sows. However, a significant increase in the total number of piglets born was observed in supplemented sows. Although the increase was seen from the first cycle with BAM, improvements were not seen with BSU until the third cycle. BAM also increased the number of born-alive and weaned piglets. NMR analysis showed an impact of BAM on milk composition. No differences were found in milk or blood immunoglobulins. A different structure of the fecal microbiota was found in supplemented sows, with changes across phylum, family, and genus. These changes were greater at day 8, suggesting a relevant role of probiotics establishing a new intestinal balance after labor. Shifts in the microbiota were also seen in the piglets, with a clearer impact post-weaning than in suckling. In this regard, correlations between microbial groups of sows and piglets showed a higher link with weaned (d33) than with suckling pigs (d21), reinforcing the idea of an early maternal carry-over. No changes due to treatment in jejunal gene expression were detected; however, piglet size had a clear impact on different genes. In summary, the addition of both probiotics, and particularly Bacillus amyloliquefaciens, demonstrated potential benefits on the prolificacy of sows. Daily feeding of Bacillus amyloliquefaciens resulted in an increase in the number of weaned piglets. The high correlations between the compositions of the microbiota of sows and their piglets are evidence of maternal imprinting, with effects lasting beyond weaning.     

Comparisons of blood biochemical parameters,digestive enzyme activities and volatile fatty acid profile between Meishan and Yorkshire piglets

This study was conducted to compare physiological characteristics between Meishan and Yorkshire piglets in their early lives. Six healthy purebred Meishan sows and Yorkshire sows with close farrowing dates were used in this research. The piglets sucked their respective sow's milk for 14 days, then they were slaughtered to collect samples of blood, pancreas, contents of stomach, jejunum, cecum, colon as well as feces for analysis of blood biochemical parameters, digestive enzymes, and volatile fatty acid(VFA). The results showed that Yorkshire piglets had higher concentrations of high-density lipoprotein cholesterol(HDL-C) and total cholesterol(TC)(P 0.05). Gastric lipase activity was higher in Meishan piglets but Yorkshire piglets had higher lactase activity(P 0.05). The total VFA together with acetate and propionate in cecum and colon were higher in Meishan piglets than in Yorkshire piglets(P 0.05),but acetate in jejunum and ratio of acetate to propionate in colon were lower in Meishan piglets than in Yorkshire piglets(P 0.05). In conclusion, in early suckling period, significant differences exist in host metabolism and intestinal microbial metabolism between Meishan and Yorkshire piglets.     

Maternal behaviour and performance in first-parity outdoor sows

When sows and their litters are kept outdoors, much of the responsibility for the litter is shifted from the herdsman to the sow compared to when the sows are kept indoors. Therefore, the maternal ability, including maternal behaviour, is believed to be important in outdoor piglet production. The aim of this study was to describe maternal traits in conventionally bred first-parity sows kept outdoors. Nursing behaviour, sow activity, sow body reserves, litter size and piglet growth were studied in 40 first-parity sows during a seven week long lactation. The sows were kept in groups outdoors. Sow activity (lying down or active) and nursing behaviour (nursing frequency, nursing duration and nursing terminator) were recorded on videotapes at four days post partum (pp) and directly observed at four and six weeks pp. Cross suckling was observed at four and six weeks pp. Sows were weighed and measured for backfat depth five days before farrowing, two weeks pp and at weaning seven weeks pp. Piglets were weighed at four days pp, at two weeks pp and at weaning. We concluded that sow nursing behaviour and activity are individual characteristics repeatable within sows' late lactation. Less active sows are more available for suckling. Light and thin sows have an earlier and more progressed weaning process than heavier, fatter sows. A significant positive relation was found between sow appetite in early lactation and piglet growth until weaning. Sow nursing behaviour is not important for piglet growth when sows and piglets are held in groups, piglets have access to sow feed and piglets are weaned as late as at seven weeks of age.     

The influence of additional fat in the diet of sows before and after parturition on piglet viability and performance

Two hundred and six mature sows were used to evaluate the effect of adding a total of 3 kg of fat to sow diets for an average of eight days before and seven days after parturition on piglet viability and performance.The addition of fat to the diet of sows had no effect on the percentage of piglets born alive, individual piglet birth weight, weight of the piglet at three weeks of age or the weaning to service interval in the sows. However, there was a significant increase in piglet survival (3.4%) between treated and control sows. Birth weight had a marked effect on piglet survival but there was no indication of a greater effect of added fat in the sows' diet on the survival of smaller piglets. A number of piglets were cross-fostered but fostering had no effect on piglet mortality. A comparison of the mortality of piglets born from sows receiving added fat and reared on controls and vice versa indicated that the major benefits of additional fat in the sow diet were effected in utero rather than via an increase in the quality of the sows' milk.     

Performance of lactating sows in response to the dietary valine supply

In order to determine the requirement of lactating sows for valine (Val) the effects of graded Val supplementations on feed intake, milk yield and changes of body weight of sows and piglets were examined using 54 multiparous sows over a total of 72 lactations (35 days). The sows were randomly assigned to six treatments (1-6). Each group received the same basic diet, covering the requirements of energy and nutrients except Val (4.5 g native Val, i.e. 3.5 g apparent ileal digestible Val). Adding crystalline l-Val dietary Val concentrations of 5.5, 6.5, 8.5, 10.5 and 14.5 g/kg, respectively, were realized. Feed intake of the sows was determined daily, body weight was determined on day 110 of gestation and day 1, 22 and 35 of lactation. The piglets were weighed on day 1, 21 and 35. The intake of piglet feed, which was offered from day 21, was determined at day 35 for each litter. Milk yield was determined using the weigh-suckle-weigh-method at day 13, 14, 20 and 21, fat and protein contents were analysed in hand-milked samples with infrared spectroscopy. Feed intake (kg/day) of the sows during lactation averaged 2.9, 4.3, 4.6, 4.6, 4.9 and 5.1 for treatments 1-6, respectively. For treatments 1 and 2 body weight losses of the sows during lactation were higher (1207 and 805 g/day, respectively) and milk production was lower (7076 and 8686 g/day, respectively), compared with the average of treatments 3-6 (625 g/day body weight loss; 9263 g milk/day). Daily weight gain of the piglets was also lower (146 and 171 g/day vs. 200 g/day) leading to lower weaning weights of 6.6 and 7.5 vs. 8.5 kg. As a consistent growth depression of the piglets in Val deficiency must be assumed, at least 6.5 g Val corresponding to 5.5 g apparent ileal digestible Val per kg lactation feed must be recommended.     

Factors associated with suckling piglet average daily gain

Low piglet weight at weaning implies a loss of income for the farmer and might influence the welfare of the affected animals negatively. The objective of our cohort study was to identify risk factors in the farrowing section associated with average daily weight gain (ADG) of piglets from birth to weaning. The study was done in 3 Danish farrow-to-finish herds and included 581 sows, 277 pens, 814 farrowings, and 8241 piglets. The data were analysed with a linear mixed model where the response was ADG, and sow and litter were random effects. Piglet treatments for arthritis (-38 g per day), diarrhoea (-8 g per day) and other infections (-21 g per day) were the major infectious contributors to lower ADG. Forelimb-skin abrasions on a piglet (-5 g per day), weak pasterns of sows on concrete slats (-34 g per day), suckling a sow with poor milking 3 weeks after farrowing (-14 g per day), low birth weight (-8.4 g per day per 100 g), male compared to female (-4 g per day) also were associated with lower ADG in the suckling period.     

Utilization of milk amino acids by the suckling Iberian piglet

Sixteen pure-bred Iberian (IB) sows were used in two trials to determine the efficiency of utilization of milk protein and amino acid (AA) for growth in suckling piglets. It was hypothesized that there may be one or more strongly limiting essential AA (EAA) responsible for the slow rate of growth of the IB piglet. This AA will show the highest fractional retention. Daily milk yield and composition were determined weekly over a 34-day lactation period. Within each litter, one piglet at birth and four piglets on d 35 of life were slaughtered. The protein content of the IB sow milk was similar to that reported for conventional breeds. However, branched-chain AA, Thr, Pro, Asp and Ala were in concentrations somewhat below the range of literature values and Arg and Met, substantially above it. Milk intake per piglet tended to be greater in Trial 2 (832 vs. 893 g/day respectively; p = 0.066). However, the IB piglets grew at 168 ± 3.3 g/day, irrespective of the trial. The whole-body protein of piglets at weaning and the protein deposited in their body during the lactating period showed very close AA pattern. Among EAA, His and Arg show the highest fractional retentions (g AA retained/g AA ingested) in whole-body tissues (1.019 ± 0.025 and 0.913 ± 0.017 respectively) and also the highest body to milk ratios (1.50 and 1.41 respectively). Gly and Ala presented, among non essential AA, the highest efficiencies of utilization for tissue deposition (1.803 ± 0.057 and 1.375 ± 0.026 respectively) and body to milk ratios (2.75 and 2.12 respectively). These results suggest that the low efficiency of utilization of milk protein and the low rate of gain of the IB suckling piglet can be explained by a marked shortage in His supply, in addition to the suboptimal milk provision of Arg, Gly and Ala.     

Effects of oral doses of corn oil and other factors on preweaning survival and growth of piglets

Piglets were provided supplemental energy as oral doses of corn oil to find whether such treatment might improve survival or weight gains. A total of 1,840 piglets from 182 litters was used. Piglets were allotted to dosed and control treatments within litter on the basis of body weight. Dosed piglets received a total of 8 ml of corn oil in four doses during the first 48 h postpartum. The survival rate to weaning was high and not affected (P greater than .10) by the corn oil doses. Deaths of piglets low in birth weight were delayed by the fat doses, suggesting some utilization. The fat doses did not affect piglet weight gain. Factors affecting preweaning survival and growth of piglets were also evaluated using data from the same piglets. Specific factors investigated were sex, parity of dam, birth weight, litter size and the mean and standard deviation of piglet birth weights within litters. Male piglets were heavier at birth than females, but there was no sex effect on weight at 7 d or at weaning. Small males were less likely to survive to 3 d than were small females. Litters from primiparous sows were smaller at birth and weaning, but had lower percentages of stillbirths and of preweaning deaths than did those from multiparous sows. Piglets from primiparous sows were more uniform in birth weight. Piglets that were heavier at birth grew faster and were more likely to survive. Litter size affected growth but not survival of piglets. A heavier average birth weight in the litter reduced slightly the growth rate of individual piglets. An increase in variability of piglet birth weight within a litter was associated with an increase of the percentages of stillbirths and of preweaning mortality. A few litters accounted for a major portion of the mortality. Much of the variation in piglet mortality and growth was not explained by factors considered.     

Effect of supplementing sows' feed with alpha-tocopherol acetate and vitamin C on transfer of alpha-tocopherol to piglet tissues, colostrum, and milk: aspects of immune status of piglets

The aim of this study was to investigate the effects of dietary supplementation of sows with alpha-tocopherol acetate (ATA) and vitamin C on deposition of alpha-tocopherol (AT) in piglet lymphoid organs, such as bone marrow, thymus, and spleen at birth and at weaning, as well as on indicators of immune response in piglets. Sows were given the following treatment diets: control, vitamin C 10 g/day, ATA 500 mg/kg feed, and combined vitamins (ATA 500+Vit-C 10). Supplementation with vitamins started at the beginning of pregnancy and lasted until weaning at 21+/-3 days of age. AT was determined in colostrum, milk, piglet plasma (cord blood) and tissues at birth and on day 21. Immunoglobulins were measured in piglet plasma, milk, and colostrum. Lymphocyte proliferation in response to PHA and ConA was determined in sow and piglet blood. ATA supplementation resulted in a significant increase (P<0.001) in the AT content of colostrum, milk, piglet plasma, liver, thymus, bone marrow, and spleen at weaning. The AT content of colostrum and milk significantly (P<0.001) influenced the AT content of piglet plasma and tissues at weaning (day 21). Total Ig and IgG concentrations in piglet plasma were significantly increased in piglets given the combined vitamin treatment. No effect of AT supplementation was observed on IgG and IgA in colostrum and milk. In sows, vitamin C given alone significantly increased lymphocyte response to ConA and PHA; whereas, in piglets, there was no significant effect of treatments on lymphocyte response to PHA and ConA.     

母猪饲粮添加β-羟基-β-甲基丁酸对母猪繁殖性能及仔猪生长性能和免疫功能的影响

本试验旨在研究母猪饲粮添加β-羟基-β-甲基丁酸(HMB)对母猪繁殖性能及仔猪生长性能和免疫功能的影响。选取20头3～6胎次、妊娠74 d的"长×大"母猪,随机分成2组,每组10个重复,每个重复1头母猪,对照组饲喂基础饲粮,试验组在对照组基础饲粮中添加2 000 mg/kg HMB。试验从母猪妊娠第74天开始,至仔猪21日龄断奶结束。结果表明:与对照组相比,试验组仔猪初生个体重显著提高14.1%(P<0.05),仔猪7、21日龄窝重分别显著提高16.6%、11.7%(P<0.05),仔猪初生至7日龄、初生至21日龄窝增重分别显著提高28.3%和12.5%(P<0.05);与对照组相比,试验组母猪在妊娠第98天和分娩当天血清免疫球蛋白G(IgG)含量分别提高35.3%(P<0.01)、13.0%(P>0.05),免疫球蛋白M(IgM)含量分别提高34.7%(P<0.05)、12.6%(P>0.05);与对照组相比,试验组母猪初乳中IgG含量显著提高19.0%(P<0.05),分娩后第14天常乳中IgM含量显著提高21.4%(P<0.05);与对照组相比,试验组仔猪7日龄血浆IgG、IgM含量分别显著提高11.4%和40.1%(P<0.05)。上述结果提示,母猪妊娠后期及哺乳期饲粮中连续添加2 000 mg/kg HMB,可显著提高仔猪初生重和哺乳期增重,改善母猪及仔猪免疫功能。     

Intermittent suckling: effects on piglet and sow performance before and after weaning

An experiment was conducted to study effects of intermittent suckling on creep feed intake and weight gain of litters. Loss of weight and backfat during lactation, as well as reproductive performance, were also measured. Batches of multiparous sows (Parity 1 to 12, 4.1 on average) were either suckled intermittently (IS, eight batches; n = 50) or continuously (control, eight batches; n = 62). Litters were weaned at 27 +/- 2 d of age, on average. Litter size (11.1 +/- 0.2 piglets, on average) was standardized within a batch within 3 d of birth. All litters had free access to creep feed and water from 1 wk of age onward. In the IS group, litters were separated from the sow for a period of 12 h/d (0930 to 2130), starting 11 d before weaning. Rectal ultrasonography was applied at d 3 after weaning to check the ovaries for follicle development or presence of corpora lutea. Creep feed intake by the litters during lactation was higher in IS litters than in control litters (686 +/- 57 vs. 314 +/- 42 g/piglet, P < 0.01). The distribution of creep feed intake shifted from a skewed one, with a majority of litters consuming less than 250 g/piglet in control litters, to a normal distribution, with an average creep feed intake of 500 to 750 g/piglet in IS litters. During the 7 d after weaning, creep feed intake in IS litters was also higher (281 +/- 15 vs. 204 +/- 9 g-piglet(-1) x d(-1), P < 0.01). The ADG of piglets during lactation was negatively affected by IS, resulting in lower weight at weaning (7,229 +/- 140 vs. 7,893 +/- 145 g/piglet, P < 0.05). During the 7 d after weaning, however, ADG was higher in IS litters (255 +/- 10 vs. 177 +/- 8 g-piglet-1 x d(-1), P < 0.01), and 7 d after weaning, the weights of the litters were similar (9,011 +/- 167 vs. 9,132 +/- 164 g/ piglet, P = 0.81). The IS litters that consumed little or no feed during lactation had an ADG after lactation that was higher than in control litters, with comparable creep feed intake during lactation: 204 vs. 136 g/d. Body weight loss by the sows during lactation was lower in IS sows (-10 +/- 2 vs. -16 +/- 1 kg, P < 0.05). A higher percentage of IS sows ovulated during lactation (22 vs. 3%, P < 0.01), and weaning-to-ovulation interval (excluding sows with lactational ovulation) was shorter in IS sows (4.7 +/- 0.2 vs. 5.3 +/- 0.2 d, P < 0.05). We conclude that IS increased creep feed intake during lactation, and that IS increased ADG after weaning, despite lower weaning weights. Ovulation during lactation was induced in 22% of the IS sows.     

Maternal-neonatal immunoregulation in swine. II. Influence of multiparity on de novo immunoglobulin synthesis by piglets

In the first-litter sows lower serum levels were found for all three Ig classes as compared to multiparous sows. The same was true for IgA in lacteal secretions and in piglet serum during the first days of life, while no differences were found for IgG levels. In contrast to these findings, IgM levels were found to be higher in lacteal secretions of first-litter sows and in piglet serum during the first days of life as compared to their counterparts. From three weeks after birth Igs found in piglet serum mainly originate from de novo synthesis. In this period piglets of first litter sows showed a higher IgA level up to the 6th week of life and higher IgG and IgM levels up to the end of the investigation period. Results are discussed in terms of maternal-neonatal immune regulation, focussing on the apparent suppressive role of maternally-derived IgG on total de novo Ig synthesis by suckling piglets.     

Effect of ginseng polysaccharides on the immunity and growth of piglets by dietary supplementation during late pregnancy and lactating sows

There are many reports that dietary supplementation with plant polysaccharides in pigs might promote their growth, but little is known about the maternal effect of ginseng polysaccharides (GPS) on piglets’ growth by dietary supplementation to pregnant and lactating sows. In the current study, the effects of dietary supplementation with GPS on the immunity of sows and growth of their piglets were investigated. Results showed no significant difference among the four groups in the total number of piglets, live piglets, weak piglets and birth weight of piglets, indicating the GPS‐treatment has no adverse effect on reproduction. Furthermore, the weaning weight of the GPS‐treated groups was higher than that of control group (P < 0.05); among them, the addition of 200 mg/kg dose has the best effect. Interestingly, GPS increased the total immunoglobulin G concentration in milk and serum of sows (P < 0.05). The concentrations of interleukin (IL)‐2, IL‐6, tumor necrosis factor (TNF)‐α, and interferon‐γ in milk and serum of sows were also increased in the experimental groups relative to the control (P < 0.05). Meanwhile, maternal supplementation of GPS significantly increased IL‐2 and TNF‐α concentration in the piglets’ serum of the experimental groups relative to control (P < 0.05). GPS (200 mg/kg) significantly increased the glutathione peroxidase activity in milk and serum (P < 0.05), while the concentrations of malondialdehyde were significantly reduced (P < 0.05). The present results indicated that GPS supplementation during late pregnancy and lactation improved immunity‐related bio‐molecular levels in sow serum and milk, which may be further beneficial to piglet health and growth through biological transmission effects.     

Energy balance of lactating primiparous sows as affected by feeding level and dietary energy source

The effects of feeding level and major dietary energy source used during lactation on sow milk composition, piglet body composition, and energy balance of sows were determined. During a 21-d lactation, 48 primiparous sows were fed either a Fat-rich (134.9 g/kg fat; 196.8 g/kg carbohydrate) or a Starch-rich (33.2 g/kg fat; 380.9 g/kg carbohydrate) diet at either a High (44 MJ NE/d; 1,050 g protein/d) or a Low (33 MJ NE/d; 790 g protein/d) feeding level. Within each feeding level, the two diets were fed to provide an isocaloric and isonitrogenous intake. At the Low feeding level, no differences in milk production, milk composition, or piglet body composition were found as a result of feeding the two dietary energy sources. However, at the High feeding level, sows fed the Fat-rich diet produced higher milk fat (8.4 vs 6.9%) and milk energy (5.38 vs 4.77 kJ/g) concentrations and a higher piglet body fat concentration (152.1 vs 135.4 g/kg) than sows fed the Starch-rich diet. At the Low feeding level, the energy balance (d 6 to d 20) of the sows was similar when fed either the Fat- or the Starch-rich diet (-558 and -515 kJ x BW(-.75) x d(-1)), but at the High feeding level, the energy balance was more negative in sows fed the Fat than those fed the Starch-rich diet (-544 vs -372 kJ x BW(-.75) x d(-1)). This suggests that at the High feeding level, dietary energy in the form of fat is preferentially used for milk fat synthesis, resulting in growth and in fatter piglets. Alternatively, at the High feeding level, Starch as the major energy source is used only for growth of the piglets, as confirmed by protein deposition, and also results in a less-negative energy balance for the sows. From this experiment, it can be concluded that effects of substituting cornstarch for fat in the diet of lactating sows on milk composition, piglet body composition, and energy balance of the sows are dependent on feeding level.     

Analysis of birth weight variability in pigs with respect to liveborn and total born offspring

Reduction in the variability of piglet birth weight within litter and increased piglet survival are key objective in schemes aiming to improve sow prolificacy. In previous studies, variation in birth weight was described by the sample standard deviation of birth weights within one litter, and the genetic impact has been proved. In this study, we additionally considered the sex effect on piglet's birth weight and on its variability. The sample variance of birth weights per litter separated by sex was assigned as a trait of the sow. Different transformations of the trait were fitted by linear and generalized linear mixed models. Based on 1111 litters from Landrace sows, the estimates of heritability for the different measures ranged from 11 to 12%. We analysed the influence of including birth weight of stillborn piglets on the variability of birth weight within litter. With omitted stillborns, the heritability was estimated approximately 2% higher than that in investigations of all born piglets, and the impact of sex on birth weight variability was increased. Because the proportion of intrapartum deaths is rather high, it is recommended to consider the total number of piglets born per litter when analysing birth weight variation.