Passive immunization in neonatal piglets in natural rearing--effects of birth order, birth weight, litter size and parity

603 neonatal piglets (German Landrace) were investigated for passive immunization affected by birth order, birth weight, litter size and parity. Concentrations of immunoglobulins in the blood serum of piglets on the first day of life served as measure for passive immunization. Blood samples were drawn at 12, 18 and 24 hours post partum. Quantitative measurements of immunoglobulin classes were carried out by radial immunodiffusion. There was a significant effect of birth order, because of the rapid changes in colostrum composition between onset of birth and the last piglet of each litter. The effect of birth weight was only partly significant and different for the immunoglobulin classes. There was no significant effect of litter size on passive immunization. Parity had a significant positive effect on IgG- and IgA-concentrations in sow's colostrum with litter two to six, parity 1 and 2 lead to highest IgM concentrations in the blood serum of piglets.     

Production traits of litters in 2 crossbred Duroc pig lines

Genetics of different pig lines affects litter size, birth weight, and neonatal losses. Low birth weight has long been associated with neonatal losses, but piglet body mass index is reported to show stronger correlation with stillbirth. The aim of this study was to investigate differences in litter size, number of stillborn piglets, piglet BW gain, and body mass index between 2 different Duroc crossbred lines. Landrace × Yorkshire sows in 2 farms (n = 89) were divided into 2 groups on each farm. One group of sows on each farm was inseminated with semen from Landrace × Duroc boars (boar group LD, n = 48), and the other was inseminated with semen from purebred Duroc boars (boar group DD, n = 41). Piglets were monitored from birth to weaning at the age of 5 wk. Litter size in boar group LD was larger than in boar group DD (P = 0.03). Number of stillborn piglets in boar group LD tended to be greater than in boar group DD (P = 0.07). Piglets in boar group DD had a greater BW at birth (P = 0.02) and at 3 wk (P = 0.01) than those in boar group LD. Body mass index from birth to weaning was greater in piglets in boar group DD vs. LD (P < 0.01), and both BW and body mass index of liveborn piglets at birth for both groups combined showed a positive correlation with survival at weaning (P < 0.01). In conclusion, breeding for larger litter size in boar group DD may be one approach to increase the number of vigorous piglets in production, but the inverse relationship between litter size and birth weight was more pronounced for this group than for boar group LD (P = 0.03). Further studies of the impact of litter size on BW gain are necessary before a final conclusion can be reached.     

Isoimmune thrombocytopenic purpura in piglets

SUMMARY A haemorrhagic diathesis due to isoimmune thrombocytopenia occurred in the fourth litter of a Landrace sow. Maternal antibodies, absorbed by piglets from the colostrum, were incompatible with platelet antigens inherited from the sire. The severity of haemorrhage varied between piglets although all were thrombocytopenic. Two deaths occurred, one at 24 h and the other at 3 weeks of age. The surviving 11 piglets were clinically and haematologically normal at 16 weeks of age.     

Postnatal behavioral and physiological responses of piglets from gilts housed individually or in groups during gestation

Gestational housing of sows remains a controversial issue that may affect the well-being of both sows and piglets. Therefore, 2 types of gestational housing were used to evaluate the stress imposed on pregnant gilts by each system and the effects on the offspring by comparing production, physiology, and behavioral measures of the piglets. Forty-eight Landrace x Yorkshire gilts were randomly assigned to groups (G) of 4 per pen (n = 8 pens; 3.9 m x 2.4 m) or to individual stalls (S; n = 16 stalls; 2.21 m x 0.61 m). Gilts were moved into individual farrowing crates 5 d before the expected farrowing date. Piglets were weighed at birth, d 14, and d 35. Two barrows from each litter were weaned at d 14 (early weaning) and housed together in pens. Maintenance behaviors (head in feeder, drinking, lying, eating mash) were videotaped and observed for the first 3 d after weaning using a 10-min interval scan sampling. Belly nosing and play/fight interactions were recorded from video observations for 3 d postweaning. An isolation test (30-min duration) was performed on one piglet from each pen of barrows on d 35. Time spent lying, the number of jumps against test box walls, and grunts and squeals were recorded in real time. Salivary cortisol was collected at 30-min intervals from baseline, and 0, 30, 60, and 90 min posttest. Jugular blood was collected from 2 barrows from each litter on d 1, 7, 14, 17, 21, and 28. Plasma TNF-alpha was analyzed by ELISA, and haptoglobin, alpha1-acid glycoprotein, and immunoglobulin G were analyzed by radial immunodiffusion. More piglets from the S treatment needed to be fed a liquid feed at weaning and drank more frequently on d 2 postweaning (P < 0.05). Additionally, by d 35 piglets from S gilts had a lighter BW (10.3 kg) than G piglets (12.8 kg; P < 0.01). Piglets from S gilts also grunted more during the 30-min isolation test (number of grunts = 356) than G piglets (number of grunts = 138; P < 0.01). Salivary cortisol and immune measures were not different. These data show some behavioral and production differences between piglets from individually stalled gilts and group-housed gilts. Therefore, there may be production advantages to housing first parity gilts in groups.     

Colostrum yield and litter performance in multiparous sows subjected to farrowing induction

The consumption of colostrum at a low level can compromise the survival and growth of piglets. Therefore, this study aimed to evaluate the effect of farrowing induction on colostrum yield, IgG concentration and the survival and performance of piglets until the weaning. Sows of parity 3 to 7 were assigned into two groups: Control (n = 48), sows with spontaneous farrowing; and induction (n = 48), sows induced to farrow on day 114 of gestation with a PGF₂ analogue. Colostrum and blood samples were collected from the sows, at farrowing and 24 hr later. Blood samples from the piglets were collected at 24 hr after birth. The performance of the piglets was evaluated in a subsample of 28 litters from each group. All piglets were weighed at 7, 14 and 20 days of age. The farrowing length, the number of piglets born alive, stillborn piglets, weight at birth, litter weight at birth and colostrum yield were not significantly affected (p > .05) by farrowing induction. There was no difference between the groups (p > .05) in the percentage of sows with obstetric interventions. Serum IgG concentration, in both sows and piglets, and colostrum IgG concentration were similar between the groups (p > .05). Furthermore, survival rate, piglet weight and litter weight at 7, 14 and 20 days of age were also similar between the groups (p > .05). Therefore, it can be concluded that the farrowing induction performed on day 114 of gestation does not affect the colostrum yield, the IgG concentration in colostrum and serum of piglets, and the litter performance until the weaning.     

Pig colostrum and milk composition:comparisons between Chinese Meishan and US breeds

The composition of colostrum and milk from Chinese Meishan and American Yorkshire gills was characterized at farrowing (d 0), 24 h after farrowing (d 1), and on d 7 and 21 of lactation. Lactose concentrations were lower for Meishan vs. Yorkshire gills on d 0, 1, and 7, but not on d 21. Fat concentrations were higher for Meishan than for Yorkshire gilts at each sampling time, particularly on d 1 and 7. Total protein concentrations were similar on d 0 and 1, but lower for Meishan than for Yorkshire gilts on d 7 and 21. Milk proteins from Meishan gilts, Yorkshire gilts, and crossbred sows (Yorkshire × Hampshire × Landrace) were compared by polyacrylamide gel electrophoresis. Differences in size or relative proportion of caseins and the major whey proteins were not observed. Several high molecular weight whey proteins and a minor casein band were observed to segregate among breeds. These protein differences among breeds may be valuable markers in studies on lactating Mei-shan × Yorkshire crossbred animals. Results of this study suggest that colostrum and milk composition should not be a major limiting factor in survival and growth of piglets born to Meishan × Yorkshire crossbred gilts.     

Influence of supplementary iron in late pregnancy on the performance of sows and litters

On eight farms alternate sows and gilts within three weeks of their expected farrowing date were injected intramuscularly in the neck with 8 ml of an iron (gleptoferron) preparation containing 200 mg iron/ml, or kept as uninjected controls. Data from 513 iron-injected and 488 control animals were used in the analysis of results. Small, but not statistically significant, improvements were observed in the numbers of piglets born alive and dead/litter, the birth weights and weaning weights at three weeks, the numbers of piglets fostered on and off/litter, piglet mortality, the number weaned/litter and the weaning to service interval. The condition scores of the iron-injected sows were marginally below those of the controls at weaning, but their condition scores at farrowing had also been slightly below those of the controls. A summation of these trends would suggest an overall benefit of approximately 0.45 pigs/sow/year in favour of the iron-injected sows.     

Lactational performance of first-parity transgenic gilts expressing bovine alpha-lactalbumin in their milk

The goal of this study was to determine whether the presence of the bovine alpha-lactalbumin transgene in first-lactation gilts enhances lactational performance and litter growth. Transgenic and sibling nontransgenic gilts were bred to nontransgenic boars. Litters were standardized to 10 piglets within 24 h of farrowing. Milk production was measured by the weigh-suckle-weigh method on d 3, 6, 9, and 12 of lactation. Bovine alpha-lactalbumin was present in the colostrum and milk of transgenic gilts throughout lactation. The expression of the transgene was associated with alterations in composition of mammary secretions, especially in early lactation. Lactose concentrations were greater (P < 0.05) in mammary secretions of transgenic gilts during the first 12 h postpartum compared with controls. In contrast, total solids concentration in mammary secretions from transgenic gilts were lower (P < 0.05) relative to controls during the first 6 h postpartum. Transgenic gilts produced more milk than controls on d 3, 6, and 9 of lactation (P < 0.01). By d 12, differences in milk production between transgenic and control sows were no longer different. Lactose intake by transgenic-reared litters was greater than lactose intake by control-reared litters on d 6 of lactation (P < 0.05). Total solids intake was significantly greater (P < 0.05) by transgenic-reared litters on d 3 and 6 compared to control-reared litters. The day x genotype interaction on litter weight gain after birth was highly significant (P = 0.011), with transgenic-reared litters gaining weight at a greater rate than control-reared piglets. Expression of the transgene was associated with increased milk production in lactating gilts and increased growth of transgenic-reared piglets. Increased lactose synthesis in response to the presence of the transgene may result in increased milk production in early lactation, leading to increased milk component intake by transgenic litters, and ultimately to increased growth of litters reared by first-parity transgenic gilts.     

Effects of the Ratio of n-6:n-3 Polyunsaturated Fatty Acids in the Maternal Diet on Immunoglobulins, Fatty Acid Composition, and Performance of Lactating Sows and Suckling Piglets under Conditions of Low Maternal Energy Intake

This experiment was conducted to investigate the effects of different ratios of n-6:n-3 polyunsaturated fatty acids (PUFA) in sow diets on the performance of lactating sows and their piglets at low digestible energy intakes.Twenty-one pregnant Landrace sows were assigned to one of three diets from day 108 of gestation until weaning (26 to 29 d),containing n-6∶n-3 PUFA ratios of 3∶1,8∶1 and 11∶1.The effects on sow and litter production traits and on sow body condition were examined.There were no differences among treatments in daily feed intakes or in changes in sow weight and back-fat levels during lactation.Litter size,litter weight at birth and weaning and litter average daily weight gain were also unaffected by treatment.As expected,large differences were observed in n-6 and n-3 fatty acids in the colostrum and plasma of sows and piglets (P ＜ 0.01 ).The ratio of n-6∶n-3 PUFA the diet was positively correlated with those in colostrum,sow plasma and piglet plasma ( R2 =0.55,0.80 and 0.80,respectively).Sow plasma insulin and IGF-I levels at weaning were unaffected by the treatments.Plasma leptin ( P ＜ 0.05) concentrations were increased in sows fed the diet with a n-6∶ n-3 ratio of 8∶1.Immunoglobulin concentrations in colostrum were not altered by dietary treatment.Plasma IgG concentrations at d 14 were highest in piglets from sows fed the 8∶1 ratio of n-6∶n-3.Furthermore,this group had the highest IgA concentrations at day 21 of lactation compared with the other two groups ( P ＜ 0.05 ).In summary,our study demonstrated that at low digestible energy levels,altering the ratio of n-6∶n-3 PUFA in the diets for lactating sows affected immune components and the fatty acid composition of lactating sows and their piglets.Further studies are needed to examine whether higher levels of fat supplementation than those used in the present study ( 1.5％ ) can successfully enhance performance.     

Limited and excess dietary protein during gestation affects growth and compositional traits in gilts and impairs offspring fetal growth

The aim of this study was to investigate whether dietary protein intake during gestation less than or greater than recommendations affects gilts growth and body composition, gestation outcome, and colostrum composition. German Landrace gilts were fed gestation diets (13.7 MJ of ME/kg) containing a low (n = 18; LP, 6.5% CP), an adequate (n = 20; AP, 12.1%), or a high (n = 16; HP, 30%) protein content corresponding to a protein:carbohydrate ratio of 1:10.4, 1:5, and 1:1.3, respectively, from mating until farrowing. Gilts were inseminated by semen of pure German Landrace boars and induced to farrow at 114 d postcoitum (dpc; Exp. 1). Energy and protein intake during gestation were 33.3, 34.4, and 35.8 MJ of ME/d (P < 0.001) and 160, 328, and 768 g/d, respectively, in LP, AP, and HP gilts (P < 0.001). From insemination to 109 dpc, BW gain was least in LP (42.1 kg), intermediate in HP (63.1 kg), and greatest in AP gilts (68.3 kg), whereas increase of backfat thickness was least in gilts fed the HP diet compared with LP and AP diets (3.8, 5.1, 5.0 mm; P = 0.01). Litter size, % stillborn piglets, and mummies were unaffected (P > 0.28) by the gestation diet. Total litter weight tended to be less in the offspring of LP and HP gilts (14.67, 13.77 vs. 15.96 kg; P = 0.07), and the percentage of male piglets was greater in litters of HP gilts (59.4%; P < 0.01). In piglets originating from LP and HP gilts, individual birth weight was less (1.20, 1.21 vs. 1.40 kg; P = 0.001) and birth weight/crown-rump length ratio was reduced (45.3, 46.4 vs. 50.7 g/cm; P = 0.003). Colostrum fat (7.8, 7.4 vs. 8.1%) and lactose concentrations (2.2, 2.1 vs. 2.6%) tended to be reduced in LP and HP gilts (P = 0.10). In Exp. 2, 28 gilts (LP, 10; AP, 9; HP, 9) were treated as in Exp. 1 but slaughtered at 64 dpc. At 64 dpc, LP gilts were 7% lighter than AP gilts (P = 0.03), whereas HP gilts were similar to AP gilts. Body composition was markedly altered in response to LP and HP feeding with less lean (P < 0.01) and greater fat content (P = 0.02 to 0.04) in LP and less fat content (P = 0.02 to 0.04) in HP gilts. Fetal litter weight and number, and embryonic survival at 64 dpc were not affected by the diets. These results indicated that gestation diets containing protein at 50 and 250% of recommendations and differing in protein:carbohydrate ratio led to marked changes in protein and fat metabolism in gilts resulting in fetal growth retardation of 15%, which mainly occurred during the second half of gestation.     

Within-herd Use of Boar Semen at 5°C, with a Note on Electronic Monitoring of Oestrus

A system was designed to allow a small swine farm in a northern latitude to use its own boars for artificial insemination (AI) conveniently. Semen was collected twice weekly for 3 day use (days 0, 1 and 2), extended in an egg yolk extender and stored at 5°C. Farm personnel were trained to manage the entire AI programme. For simplicity all semen collected was used for insemination. In the first test 47 gilts and 15 sows were inseminated with semen from four boars. One boar was subfertile with a farrowing rate of 36%. The averages for the other boars ranged from 71 to 100%. Then semen was collected from seven boars and all was used to inseminate 70 gilts and 55 sows with 3 × 10⁹ or more sperm. Overall 63% farrowed an average of 10.1 piglets per litter. Litter size for sows was 1.5 piglets larger than for gilts. There was no difference in farrowing rate when more than 3 × 10⁹ sperm were inseminated. The feasibility of initiating a complete AI programme within a small herd using herd boars was established. However, selection of the boars, use of only high quality semen, and experience with detecting oestrus was required to increase the farrowing rate. The use of various agents to protect sperm against cold shock below 15°C is worthy of further investigation. A new type of electronic probe, which measures the conductivity of cervical mucus, could be helpful if a boar is not available for conventional detection of oestrus.     

Exposure of sero-positive gilts to swine influenza virus may cause a few stillbirths per litter

Six pregnant gilts were purchased from a high health herd and were found to be serologically positive for swine influenza virus (SIV) subtype H3N2. Three of the gilts, at 80 to 82 days of gestation, were experimentally exposed a second time to the same SIV subtype--H3N2. No clinical signs resulted from the second exposure to SIV and hemagglutination-inhibition (HI) titers for SIV at 4 weeks postexposure were unchanged suggesting that the gilts had not been reinfected. However, the second exposure to SIV affected the number of pigs born alive. Each of the 3 litters from the twice exposed gilts suffered 2 or 3 stillborn piglets per litter. In contrast the 3 matched, sero-positive gilts that were not exposed to SIV (controls) had no stillborn piglets. These differences were statistically significant using a t-test for unequal variances (P = 0.0086). Sera from 2 of the stillborn piglets were negative for HI antibodies and there was no indication from the pigs born alive that the H3N2 virus had crossed the placenta.     

Litter Size and Vagina–cervix Catheter Penetration Length in Gilts

As in other species, the reproductive tract in pigs increases in size with age and body weight, and the development of the reproductive tract depends on a balance between development of the pituitary–ovarian axis and the influence of metabolic hormones. Two experiments were conducted in prepubertal Duroc gilts, 150–180 days of age, to determine whether litter size is related to vaginal–cervix catheter penetration length during insemination. In experiment 1, oestrus was induced in 452 gilts with a combined dose of 400 IU Pregnant Mare Serum Gonadotrophine (PMSG) + 200 IU human chorionic gonadotropin (hCG). The gilts were classified into three catheter penetration length groups: Ih, ≤ 21 cm; IIh, > 21 and < 28 cm; IIIh, > 28 cm. The litter size was lowest in group Ih (7.35 ± 0.15) compared with groups IIh (7.81 ± 0.12; p < 0.05) and IIIh (10.0 ± 0.36; p < 0.001). In experiment 2, first oestrus was induced in 162 gilts by boar exposure. The gilts were classified into three catheter penetration length groups at insemination during their second oestrus: In, ≤ 24 cm; IIn, > 24 and < 26 cm; IIIn, > 26 cm. As in experiment 1, the litter size was lowest in the group with the shortest catheter penetration length (8.32 ± 0.19). The litter size was not different among gilts of groups IIn and IIIn (8.84 ± 0.35 and 9.56 ± 0.46, respectively), but litter size was lower (p < 0.05) in group In than in group IIn. Based on the combined data from both experiments, the correlation between the catheter penetration length and total number of piglets born was expressed as: y=5.346 ± 0.104x; r=0.361 (p < 0.05). Fertility rate was not different among the groups of gilts induced into oestrus by hormone treatment or inseminated in the second oestrus; however, the total fertility rate of boar‐exposed gilts was higher (p < 0.0001) than PMSG/hCG treated animals. Thus, it is possible to conclude that litter size at first farrowing is associated with vaginal–cervix catheter penetration length during insemination of the gilt.     

Effect of vaccinating sows and their piglets on the development of Glässer's disease induced by a virulent strain of Haemophilus parasuis serovar 5

Ten pregnant gilts were divided into two groups of five and one group was vaccinated at 80 and 95 days of pregnancy with a commercial bacterin containing Haemophilus parasuis serovars 2, 3 and 5. Half the piglets born to each group of gilts were vaccinated at seven and 21 days of age with the same bacterin, and one week after they were weaned at five weeks, all the piglets were inoculated intratracheally with 10(6) colony-forming units of Hparasuis serovar 5. At slaughter, a significantly smaller percentage of the lungs of the pigs born to the vaccinated gilts was affected by pneumonic lesions, and significantly fewer of them had arthritic joint changes. The average daily liveweight gain of the pigs born to the vaccinated gilts was significantly greater than that of those born to the unvaccinated gilts, but the vaccination of the piglets had no effect. There was no significant difference between the feed conversion ratios of the four groups of piglets, and none between the average times they took to reach slaughter weight. The pigs born to the vaccinated gilts had higher ELISA titres to Hparasuis than those born to the unvaccinated gilts.     

Influence of long-term vaccination of a breeding herd of pigs against PCV2 on reproductive parameters

The objective of the study was to evaluate an efficacy of sows vaccination protocols in the herd with serious problems affecting efficacy of reproduction. The study was performed in a large pig herd with about 1200 sows. Before vaccination against PCV2, farrowing rate in this farm was about 65%. Sows, boar and replacement gilts were immunized using Circovac vaccine (Merial, France) according to producer's recommendations. Parameters of production were analyzed since 2007 until 2010 in selected batches of sows inseminated at the same weeks of the year (17th, 18th, 19th and 20th) to eliminate seasonal variability. In total, 940 sows were subjected to the study. No significant changes in management during these years were introduced. The applied protocol of sow herd long-term vaccination proved to be very efficient. All measured production parameters: reproduction rate, number of piglets born alive, birth weight of piglets and number of piglets weaned per a litter improved after implementation of immunization program. Moreover, further improvement was observed with vaccination in the following reproduction cycles. The most spectacular effect of vaccination regarded average farrowing rate that increased from 64.76% in control group to 86.93% after basic vaccination. Two years after implementation of vaccination program this parameter reached 93.6%. Number of piglets weaned per sow per a litter improved from 10.31 to 11.74 after one year of vaccination and remained relatively stable through the following year. Simultaneously, the percentage of newborn piglets with birth weight < 1 kg decreased significantly (p < 0.05). To summarize, vaccination against PCV2 influenced positively the insemination rate, number of piglets born alive and weaned per litter as well as birth body weight and percentage of piglets weighing < 1 kg.     

The effect of duration of boar exposure on the frequency of gilts reaching first estrus

One-hundred crossbred gilts were used in an experiment that was designed to examine the effects of duration of boar exposure on the proportion of gilts reaching first estrus. Two replicates (summer and fall) of 50 gilts each were randomly assigned, within litter, to one of the following treatments: 1) 30 min of daily boar exposure, 2) 15 min of daily boar exposure, 3) 5 min of daily boar exposure, 4) continuous fence-line boar exposure, plus walked to a neutral pen and exposed to a different boar for 10 to 15 min daily, or 5) continuous fence-line boar exposure. Boar exposure lasted for 30 d. The percentage of gilts exhibiting first estrus by 210 d of age ranged from a high of 65.0 for treatment 4 to a low of 10.0 for treatment 5. Treatments 1, 3 and 4 were greater than treatment 5 (P less than .05), but not different from treatment 2. There were no differences in average age at first estrus. Treatment means for days to puberty after boar exposure were not different (P greater than .05). However, a significant treatment X season interaction occurred. This interaction appears to suggest seasonal trends. These results indicate that treatments 1 and 4 (30 min daily and continuous fence-line boar exposure plus 10 to 15 min, respectively) were the most effective methods tested for the induction of first estrus.     

Effects of vitamin A and beta-carotene on reproductive performance in gilts

The effects of vitamin A and beta-carotene on various reproductive parameters were examined in 108 crossbred gilts. Gilts were fed a diet free of vitamin A and beta-carotene for 5 wk, then assigned to one of eight treatments. Statistical comparisons were performed on three sub-groupings of these treatments as follows: (1) DEFICIENT (received 2,100 IU of vitamin A X head-1 X d-1, (2) FED (received dietary supplementation of 0, 2,100 or 12,300 IU vitamin A and (or) 0, 32.6 or 65.2 mg beta-carotene X head-1 X d-1) or (3) INJECTED (received injection supplementation of 0 or 12,300 IU vitamin A and 32.6 mg beta-carotene X head-1 X d-1, administered once weekly). Gilts remained on treatment through weaning of litters at 21 d postpartum. Plasma vitamin A and beta-carotene levels were greatly elevated in INJECTED gilts. Concentrations of these compounds in plasma were similar between DEFICIENT and FED gilts. There was no treatment difference in number of corpora lutea/gilt. Embryonic mortality was lowest (P less than .01 to .02) in INJECTED gilts (14 +/- 3%) compared with DEFICIENT (29 +/- 5%) or FED (25 +/- 3%) gilts. Baby pig mortality averaged 6 +/- 1% and was not different among treatments. INJECTED gilts had more (P less than .05 to .01) piglets/litter at birth and at weaning (9.5 +/- .3 and 9.0 +/- .3 piglets/litter, respectively) than DEFICIENT (7.9 +/- .5 and 7.6 +/- .5 piglets/litter) or FED gilts (8.7 +/- .3 and 8.1 +/- .3 piglets/litter).(ABSTRACT TRUNCATED AT 250 WORDS)     

Increased litter survival rates,reduced clinical illness and better lactogenic immunity against TGEV in gilts that were primed as neonates with porcine respiratory coronavirus (PRCV)

Establishing immunological memory in female piglets at a young age with PRCV was effective in inducing a secondary immune response to a limiting dose of virulent TGEV given orally 13-18 days prior to farrowing. Subsequently, because of passive antibody transfer, the offspring of these primed gilts were more efficient in surviving a lethal TGEV challenge. An average survival rate of 89% occurred in 6 litters of piglets from primed gilts that were boosted with 2.8 x 10(6) plaque forming units (PFU) of TGEV whereas 76% of the piglets survived in three litters that suckled primed gilts boosted with 3.0 x 10(5)PFU of TGEV. Non-primed gilts given identical pre-farrowing doses of TGEV had litter survival rates of 63 and 55%, respectively. Moreover, both groups of litters from primed gilts suffered less clinical illness (as measured by the extent of weight loss post-challenge) than control litters. Priming of the piglets as neonates and boosting the pregnant gilts produced an anamnestic systemic immune response and correspondingly higher milk titers in the primed gilts compared to control animals. Thus, priming piglets with PRCV was beneficial in providing resistance to TGEV and could be incorporated into a vaccine strategy that yields better protection against TGEV.     

Four-year study of lameness in piglets at a research station

Lameness in piglets up to nine weeks old was studied in a research station herd for four years; 9411 piglets were born alive, of which 9.8 per cent were treated for lameness. In litters born to gilts, 9.9 per cent of the piglets were treated for lameness, in litters born to sows of parity 3, 11.4 per cent of the piglets were treated, but in litters born to sows of parity 4 to 7 the proportion of piglets treated for lameness decreased to about 8 per cent. Around 75 per cent of all cases were observed in piglets less than three weeks old; the incidence risk of lameness decreased from 2.7 per cent during the first week of life to 0.3 per cent after weaning. The average weight of affected piglets was reduced by approximately 8 per cent at nine weeks of age. There was no overall association between lameness and sex or birth weight within sex. The mortality among lame gilts was higher at all ages than among healthy gilts, but among barrows a higher mortality was observed only during the late suckling period. Litters with 12 or more piglets had a higher incidence of lameness. Clinical signs of disease in the sow and whether the piglets were given an intramuscular injection of 200 mg of iron on their second, third or fourth day of life had no effect on the incidence of lameness.     

Contributions of the maternal uterine environment and piglet genotype on weaning survivability potential: I. Development of neonatal piglets after reciprocal embryo transfers between Meishan and White crossbred gilts

In commercial pigs, the greatest susceptibility for pre-weaning mortality occurs in low birth-weight piglets. Despite their overall decreased birth weight, Meishan (MS) piglets have decreased pre-weaning mortality rates compared with contemporary Western breeds. The objective of the current study was to determine the contributions of the maternal uterine environment, piglet genotype, and their interaction on the development of neonatal piglets pertaining to pre-weaning survivability using reciprocal embryo transfer between MS and White crossbred (WC) pigs. Twenty-five successful pregnancies were produced from 2 farrowing seasons, generating litters of maternal uterine environment (MUE) by piglet genotype (PigG) combinations; MS × MS (n = 4 litters), MS × WC (n = 7 litters), WC × MS (n = 7 litters), and WC × WC (n = 7 litters). At approximately 24 h of age (Day 1), piglets (n = 173) were weighed and a blood sample was taken. Hematocrit, hemoglobin, glucose, plasma urea nitrogen, albumin, NEFA, lactate, and cortisol were measured in all blood samples. Representative piglets (n = 46) from each litter were harvested and body measurements (i.e., organ weights, tissue glycogen content, and body composition) were determined. Piglet data were analyzed by ANOVA using MIXED model procedures. Both MUE (P < 0.001) and PigG (P < 0.01) affected piglet BW, illustrating that piglets gestated in WC gilts were heavier than piglets gestated in MS gilts, and WC piglets were heavier than MS piglets. Serum albumin concentrations were increased (P < 0.05) in MS piglets compared with WC piglets, indicating greater liver maturity. Significant MUE × PigG interactions were observed for hematocrit and hemoglobin, in which the greatest concentrations were observed in MS piglets gestated in MS and WC gilts, and the lowest concentrations were observed in WC piglets gestated in WC gilts, demonstrating increased oxygen-carrying capability. The percentage of fat and nitrogen, as well as the GE of the body, were greater (P < 0.05) in MS piglets, indicating greater energy stores. Liver, bicep femoris, and LM glycogen concentrations were greater (P < 0.01) in WC piglets compared with MS piglets, demonstrating increased glycogen catabolism in MS piglets. This study demonstrated limited interactions between the maternal uterine environment and piglet genotype on weaning survivability potential, suggesting that the MS piglet is a viable model for pre-weaning survivability.