This study aimed to identify risk factors affecting PBW, high CV_PBW 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% CV_PBW 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 CV_PBW 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 CV_PBW 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.

Large litter sizes have resulted in more piglets being exposed to intrauterine growth restriction (IUGR). Growth restriction during fetal life is linked with lower growth efficiency and increased susceptibility to infections in postnatal life and IUGR may associate with an altered innate immune system. We investigated the haematological, thromboelastography and plasma biochemical profiles of IUGR and normal piglets as well as cytokine responses in peripheral blood mononuclear cells stimulated with lipopolysaccharide (LPS) at 24 days of age. Piglets were classified at birth based on their head morphology as either IUGR or normal. The present study showed a modulation of the immune function of IUGR pigs, characterized by an increase in neutrophil percentage and fibrinogen levels but a decrease in CD4+ T-cells. A lower level of LPS-induced IL-1β production was evident in IUGR pigs, suggesting immunological hypo-responsiveness. Furthermore, higher levels of reticulocytes, MCV and MCH and lower levels of erythrocytes in IUGR pigs suggest altered bone marrow hematopoiesis. All together, the results suggest a moderate suppression of the immune response of IUGR piglets, which may have implications for resistance to pathogen challenges in the post-weaning period. Serum metabolites and blood clotting profile did not differ between IUGR and normal piglets.

Intrauterine growth-restricted (IUGR) piglets have lower survival rates and are more likely to have empty stomachs 24 h after birth than normal piglets. Although hypoglycemia may result from low colostrum intake per se, it is not known if slow gastric emptying may be an additional risk factor for poor immunization and glucose absorption in IUGR piglets. It is estimated that IUGR piglets consume less colostrum per kilogram BW than normal-weight piglets within the first 24 h, which could be due to a slower gastric emptying rate and a compromised energy metabolism. Therefore, we hypothesized that the gastric emptying rate and blood glucose would be lower in IUGR piglets. We investigated gastric emptying rates in normal and IUGR piglets and blood glucose and rectal temperatures at birth and after 15, 30, 60, and 120 min. In addition, blood parameters relevant for metabolism were studied. Forty-eight piglets (24 normal and 24 IUGR) were classified at birth as either normal or IUGR on the basis of head morphology. Piglets were removed from the sow at birth before suckling, and birth weight was recorded. Pooled porcine colostrum was tube-fed to all piglets at 12 mL/kg BW as soon as possible after birth (t = 0 min). The piglets were randomly allocated to be euthanized at 15, 30, 60, and 120 min (all groups, n = 6) after bolus feeding, and the weights of the stomach and its residuals were recorded. There was no difference in gastric emptying rates between normal and IUGR piglets (P = 0.129); however, gastric DM residuals tended to by greater in IUGR piglets than normal piglets (P = 0.085). Overall, IUGR piglets had lower rectal temperatures (36.2°C ± 0.2°C vs. 37.5°C ± 0.2°C; P < 0.001) and plasma glucose levels (2.8 ± 0.2 vs. 4.1 ± 0.2 mmol; P < 0.001) than normal piglets. Interactions between piglet classification and time were observed in plasma values for NEFA, D-3-hydroxybutyrate, albumin, aspartate, and alanine amino transferase, with greater levels in normal piglets at 15 min (P < 0.05) and 30 min for bile acid (P < 0.05) compared to IUGR piglets. In conclusion, the gastric emptying rates between normal and IUGR piglets were similar, but gastric DM residuals tended to be greater in IUGR piglets. Differences were observed in blood values and rectal temperatures, with lower values in IUGR piglets. Therefore, it is likely that factors like hypothermia and possibly reduced metabolic function are more important during the first hours after birth than gastric retention per se.

Intrauterine growth-restricted piglets (IUGR) have a lower rectal temperature, whole-blood glucose, and lower glycogen storages at birth than normal piglets, giving them less energy to maintain body temperature and compete at the udder. The present paper investigated the effects of giving an energy supplementation three times after birth on rectal temperature, glucose levels, and growth until weaning in an on-farm trial. Eighty-eight newborn piglets were classified as IUGR (based on head morphology), placed under a heating lamp for one hour and allocated to one of four treatments—warmed water (WATER), glucose injection (GLUC), colostrum bolus (COLOS; porcine colostrum), and colostrum bolus and glucose injection (GLUC + COLOS)—before being placed at a nursing sow. Weight differences were found at day 21, with GLUC and GLUC + COLOS groups being the heaviest. Piglets in GLUC + COLOS had higher glucose levels at t = 3, 6, and 9 h compared to the other treatments (p = 0.027), but from t = 24 h and onwards, no difference was observed. For rectal temperature, no differences were observed. Collectively, these findings suggest that glucose injections at birth (i.e., as an energy source), one hour’s exposure to warmth and the placement of piglets with a nurse sow to reduce competition, enhance the growth of IUGR piglets.

The aim of this study was to investigate the effect of two dietary treatments (liquid creep feed (LCF) and dry creep feed (DCF)) offered during the suckling period on feed disappearance, number of eaters, and intestinal enzymatic development at weaning in an on-farm study with 347 piglets. Piglets were allocated to either the DCF or LCF treatment from day 10 to day 24 postpartum for 9 h a day. Red ferric oxide (1%) was added to the diet to categorize piglets into eating categories (good eaters, moderate eaters, or non-eaters) via faecal swabs. At weaning, 40 piglets were sampled for intestinal enzymatic development. The LCF treatment increased the dry matter disappearance from day 10–18 (p < 0.001). The percentage of good eaters, moderate eaters and non-eaters did not differ between treatments (p > 0.05). The DCF pigs displayed greater average daily gain (ADG) pre-weaning (p = 0.024), and a greater body weight (BW) at day 61 (p < 0.001). The activity of lactase, maltase and sucrase in the proximal part of the small intestine were greatest (p < 0.001) in the DCF pigs.