Intrauterine growth restriction in piglets modulates postnatal immune function and hepatic transcriptional responses independently of energy intake

Introduction: Insufficient prenatal nutrition can affect fetal development and lead to intrauterine growth restriction (IUGR). The aim of this study was to investigate hepatic transcriptional responses and innate immune function in piglets suffering from IUGR compared to normal-sized piglets at 3 days of age and explore whether the provision of an energy-rich supplement at birth could modulate these parameters. Methods: A total of 68 piglets were included in the study. Peripheral blood mononuclear cells were harvested for LPS stimulation, and organs were harvested post-mortem to quantify relative weights. Liver tissue was utilized for RNA sequencing coupled with gene-set enrichment analysis. Results: IUGR resulted in increased expression of genes such as PDK4 and substantial alterations in transcriptional pathways related to metabolic activity (e.g., citric acid and Krebs cycles), but these changes were equivalent in piglets given an energy-rich supplement or not. Transcriptomic analysis and serum biochemistry suggested altered glucose metabolism and a shift toward oxidation of fatty acids. IUGR piglets also exhibited suppression of genes related to innate immune function (e.g., CXCL12) and pathways related to cell proliferation (e.g., WNT and PDGF signaling). Moreover, they produced less IL-1β in response to LPS stimulation and had lower levels of blood eosinophils than normal-sized piglets. Discussion: Taken together, our results indicate that IUGR results in early-life alterations in metabolism and immunity that may not be easily restored by the provision of exogenous energy supplementation.

An increased weaning age and liquid feed enhances weight gain compared to piglets fed dry feed pre-weaning

Increasing age and providing liquid creep feed could potentially increase the solid feed intake in pre-weaning piglets, which may in turn promote gut maturation and post-weaning feed intake, possibly lessening the severity of the growth-check associated with the suckling-to-weaning transition. Therefore, this study aimed to investigate if feeding dry- versus liquid creep feed (DF vs. LF) and weaning in week 4 or 5 (4W or 5W) could accelerate maturational changes to the small intestines of pre-weaning piglets by increasing digestive and absorptive capacity. In a 2 × 2 factorial study the effect of weaning age (WA) and feeding strategy (FS) on weaning weight, pre-weaning accumulated gain (AG), and average daily gain was measured for 12 923 piglets. A subpopulation of 15 piglets from each treatment group (4WDF, 4WLF, 5WDF and 5WLF; n = 60) were sacrificed to assess the effects of WA and FS on weight of digestive organs, activity of maltase, lactase and sucrase, and gene expression level of sodium-glucose linked transporter 1 (SGLT-1), glucose transporter 2 (GLUT2) and peptide transporter 1 (PepT1) in the proximal part of the small intestine (SI). No interactions were found but average weaning weight was affected by WA (P < 0.001) and FS (P < 0.001), where 5W were heavier than 4W and LF were heavier than DF. Correspondingly, the average daily gain (ADG) was affected by both WA (P = 0.003) and FS (P < 0.001). Only WA affected the relative weight of the digestive organs, where stomach weight, weight of SI and colon weight were heavier in 5W piglets compared to 4W. Lactase activity tended to decrease with age (P = 0.061), but there was no difference in the activity of maltase or sucrase between any of the treatment groups. Similarly, there was no differences in gene expression level of SGLT1, GLUT2 or PepT1 between neither the two ages nor feeding strategies. In conclusion, both WA and FS affect weaning weight and weight gain of piglets in the pre-weaning period.

A reduced CP level without medicinal zinc oxide does not alter the intestinal morphology in weaned pigs 24 days post-weaning

The use of medicinal zinc oxide (ZnO) to prevent diarrhoea post-weaning will be banned in the EU from 2022. Therefore, new alternatives are needed to avoid an increase in diarrhoea and higher antibiotic use. A low dietary CP level has shown to lower the frequency of diarrhoea in pigs, due to lower microbial protein fermentation in the colon as well as improved conditions in the small intestine after weaning. The objective of this study was to examine the effect of decreased CP levels post-weaning as an alternative to medicinal ZnO on gut morphology and histopathology. Five hundred and sixty pigs were randomly assigned into one of six groups receiving a two-phase diet from 5.5 to 15 kg: positive control group (PC) with medicinal ZnO and standard levels of protein (19.1-18.4% CP), negative control group (NC) without medicinal ZnO and standard levels of protein (19.1-18.4% CP). The remaining four low protein groups were a low-standard (LS) CP level (16.6-18.4% CP), a low-low (LL) CP level (16.6-16.2% CP), a very low-high (VLH) CP level (14-19.3% CP) and a very low-medium (VLM) CP level (14-17.4% CP). Individual BW was recorded at day 0, 10 and 24 post-weaning, and all antibiotic treatments were recorded. Tissue samples from the small intestine (mid-jejunum) for morphological and histopathologic analysis, organ weights, blood and urine samples were collected at day 10 and 24 post-weaning from a total of 90 sacrificed weaners. The results demonstrated no differences in intestinal morphology between groups, but the histopathology showed a damaged brush border score in VLM and VLH pigs . In addition, a lower blood urea nitrogen in VLM pigs at 24 days was found. The LL and VLM pigs had a significantly decreased average daily gain in the overall trial period compared to PC and NC pigs. Conclusively, intestinal brush border was damaged by the very low protein diet at 24 days post-weaning, but intestinal morphology was unaffected by dietary strategy.

Performance and risk factors associated with first antibiotic treatment in two herds, raising pigs without antibiotics

Background

Antibiotic (AB) consumption in production animals has a high awareness among politicians and consumers due to the risk of selection for AB resistance among potentially zoonotic bacteria. However, AB treatment of animals is at times necessary to treat diseases and ensure the wellbeing of the animals we take into our care. Raised without antibiotics (RWA) is a concept where pigs are individually ear-tagged for tracking, and if pigs are AB treated, they lose their RWA status. At slaughter, the farmer receives an additional price for non-AB treated pigs. The objective of this study was to identify risk factors for AB treatment and to investigate growth performance of pigs in two Danish RWA herds.

Results

A total of 518 pigs in herd A and 436 pigs in herd B, were individually ear-tagged and subjected to weekly investigations of AB treatment status from birth to 12 weeks of age. Bodyweight was recorded at birth, 2, 4 and 12 weeks of age. The results showed, that at 12 weeks of age, 82 of 518 liveborn pigs were AB treated in herd A and 31 of 436 liveborn pigs were AB treated in herd B. Individual pigs that required AB treatment had a reduced average daily gain from day 0 to 28 in both herds (herd A, P <  0.001; herd B, P = 0.062) and from day 0 to 84 in herd A (P <  0.001). Additionally, significant risk factors for AB treatment were identified as a low bodyweight in herd A, whereas barrows and litters with less than 19 piglets were the main risk factors in herd B.

Conclusion

The results suggests that in order to reduce AB treatments particular attention should be addressed to smaller pigs and barrows in RWA herds. In these two Danish RWA herds from this study it was possible for 64 and 68% pigs to reach 12 weeks of life without any AB treatments.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40813-021-00198-y.

Low protein diets without medicinal zinc oxide for weaned pigs reduced diarrhea treatments and average daily gain

The use of medicinal zinc oxide (ZnO) in post-weaning diets must be phased out in the European Union by 2022, resulting in urgent needs for alternative strategies to prevent diarrhea in pigs. The objective of this study was to test the effect of four different dietary protein strategies with different amino acid profiles on diarrhea frequency and pig performance as alternative diet plans when medicinal ZnO was will be excluded from the diet. A total of 6 800 Duroc x (Danish Landrace x Yorkshire) pigs, weaned around 28 days of age, were randomly assigned by sex and size to six dietary treatments. The treatments were; standard CP levels (191, 184, 184 g/kg CP) and allocated 2 500 ppm ZnO in phase 1 (PC = positive control), standard CP levels (191, 184, 184 g/kg CP) and no added ZnO in phase 1 (NC = negative control), CP levels of 166, 184, 184 g/kg (LSS = low-standard-standard), CP levels of 166, 162, 192 g/kg (LLH = low-low-high), CP levels of 140, 193, 192 g/kg (VHH = very low-high-high), and lastly 140, 174, 192 g/kg CP levels (VMH = very low-medium-high). The pigs entered the trial at ~7 kg BW and exited at ~30 kg BW. As expected, the PC treatment resulted in 42% fewer diarrhea pen treatments in the total trial period compared to the NC group (P < 0.05), whereas both PC and LLH had fewer diarrhea treatment days per pig compared to NC pigs (P < 0.05). Additionally, at the point of treatment, the NC pens had 33% fecal floor samples positive for pathogens, compared to 80% samples positive for pathogens in the PC pens. This suggests that ZnO has a particular positive effect on non-infectious diarrhea without bacterial involvement. A reduction in dietary CP levels in phase 1 led to a reduced average daily gain (ADG) in LLH and VMH pigs and a poorer feed conversion ratio (FCR) in VHH pigs during the overall study period compared to the NC pigs (P < 0.05). Conclusively, a diet with low CP levels from weaning to about 15 kg BW had a reducing effect on diarrhea, but decreased ADG without affecting the FCR.

Intrauterine growth-restricted piglets defined by their head shape have impaired survival and growth during the suckling period

Increased litter sizes in modern pig breeds have led to a significant number of pigs being born undersised and/or exposed to different degrees of intrauterine growth restriction (IUGR). The aim of this study was to examine the effect of piglet head shape as an identification method on performance indices. Data included all piglets from 203 litters, in total 3402 crossbred piglets. Piglets were classified at birth based on their head morphology (normal, mild IUGR and IUGR) and weighed at birth, Day 14 and at weaning (mean ± s.d.: 25.5 ± 1.23 days). The relative weight of the brain (to bodyweight) was greater in the mild IUGR (4.2%) and in the IUGR piglets (5.5%) compared with the normal piglets (2.8%) (P &lt; 0.001). Weaning weight of the mild IUGR and IUGR piglets was reduced by 1.3 kg and 1.8 kg, respectively, compared with the normal piglets (P &lt; 0.001). The average daily gain of the normal piglets (228 g/day) was higher than the mild IUGR (195 g/day) and IUGR piglets (181 g/day) (P &lt; 0.001). The fractional growth rate (weight gained per day per starting weight) was, however, highest in the IUGR piglets followed by the mild IUGR and the normal piglets (P &lt; 0.001) indicating the potential for catch up growth. Mild IUGR that were liveborn had twice as high a risk of dying before weaning than normal piglets; whereas liveborn IUGR piglets had a 4.7 times greater risk of dying pre-weaning. The present study showed that piglets born with a ‘dolphin-like’ head shape have an impaired growth and increased risk of dying in the suckling period.

Supplementing newborn intrauterine growth restricted piglets with a bolus of porcine colostrum raises rectal temperatures one degree Celsius

Hyperprolific sows have increased litter sizes but also result in more piglets that have been exposed to intrauterine growth restriction (IUGR). These IUGR piglets are likely to have a low rectal temperature and lower blood glucose levels compared with normal piglets at birth. Therefore, we hypothesized that a colostrum bolus at birth and/or heat from an external source would have a positive effect on blood glucose levels, rectal temperatures, and growth up to 8 h postpartum. In addition, liver glycogen and blood values at 8 h were investigated. Eighty-four piglets were classified at birth (time = 0) as IUGR based on their head morphology and randomly allocated to 1 of 4 treatments ( = 21) in a 2 × 2 factorial arrangement: 1) with or without a porcine colostrum bolus (12 mL/kg BW at birth) and 2) with sow or isolated from sow with external heat. Piglets were removed from the sow before they had suckled and were numbered and dried, and initial whole-blood glucose, rectal temperature, and BW were recorded. Piglets in the 2 treatments isolated from sow were placed under a heating lamp (150 W) with a temperature range of 35 to 39°C. Rectal temperatures, glucose, and BW were measured again at 1, 2, 4, 6, and 8 h after birth, and a final plasma sample and organs (liver and brain) were removed at 8 h. There was a time × colostrum bolus interaction ( = 0.026) and a time × sow interaction ( < 0.001) for whole-blood glucose. The piglets that were given a bolus had greater glucose levels after 1 h postpartum (time = 1 h) than piglets without a bolus at birth, but from time = 2 h and onward, there was no difference ( > 0.05). There was a time × colostrum bolus interaction ( < 0.001) and a time × sow interaction ( < 0.001) on rectal temperatures. One hour after birth, the piglets with a bolus had a greater rectal temperature compared with piglets without a bolus (37.5 vs. 36.6°C; < 0.001) and the piglets that had been isolated from the sow had a greater rectal temperature compared with the 2 treatments with sows (37.8 vs. 36.3°C; < 0.001). Four hours after birth, rectal temperature was not affected by treatments. In conclusion, both heat and a colostrum bolus increased rectal temperature by 1°C an hour after birth. However, after 4 h, no differences were found between the treatments. Interventions to help IUGR piglets postpartum most likely need to be frequent to have any effect on whole-blood glucose, rectal temperatures, and BW over the first 8 h.

Intrauterine growth-restricted piglets have similar gastric emptying rates but lower rectal temperatures and altered blood values when compared with normal-weight piglets at birth

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, = 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 ( = 0.129); however, gastric DM residuals tended to by greater in IUGR piglets than normal piglets ( = 0.085). Overall, IUGR piglets had lower rectal temperatures (36.2°C ± 0.2°C vs. 37.5°C ± 0.2°C; < 0.001) and plasma glucose levels (2.8 ± 0.2 vs. 4.1 ± 0.2 mmol; < 0.001) than normal piglets. Interactions between piglet classification and time were observed in plasma values for NEFA, -3-hydroxybutyrate, albumin, aspartate, and alanine amino transferase, with greater levels in normal piglets at 15 min ( < 0.05) and 30 min for bile acid ( < 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.

Reproductive performance of "nurse sows" in Danish piggeries

The use of nurse sows in Danish piggeries is common practice because of large litter sizes; however, the effect of being selected as a nurse sow on subsequent reproductive performance is unknown. Therefore, the aim of this study was to quantify a nurse sow's reproductive performance in the subsequent litter. Nurse sows were defined as sows weaning their own litter at least 18 days postpartum and thereafter nursing another litter (nurse litter) before service. Data (2012-2013) from 20 piggeries with more than 14.5 live born piglets per litter and a stable distribution of sows among parities over time were selected. Records from 79,864 litters were obtained and analyzed using mixed linear and logistic regression models. The average lactation lengths were 40.3 days for nurse sows and 27.8 days for non-nurse (normal) sows. Nurse sows weaned on average 12.4 piglets and subsequently 11.5 nurse piglets, whereas non-nurse weaned 11.7 piglets in their single weaning. There was no difference in re-service rate between nurse and non-nurse sows in the subsequent reproductive cycle. Subsequent litter size in the next reproductive cycle was higher for nurse sows than that for non-nurse sows (18.69 vs. 18.11 total born piglets; P < 0.001). Nurse sows were of a slightly lower parity than non-nurse sows (3.12 vs. 3.27, P < 0.001), and nurse sows had an increased weaning to estrus interval compared to non-nurse sows (4.23 vs. 4.19 days, P < 0.001). The results indicate that nurse sows were selected among sows nursing large litters and could therefore suggest that these sows represent the best percentile of sows in a given piggery. In conclusion, this survey indicated no negative effects of being selected as a nurse sow on the subsequent reproductive performance. On the contrary, nurse sows gave birth to more piglets compared to non-nurse sows in their subsequent litter.

Intrauterine growth restricted piglets defined by their head shape ingest insufficient amounts of colostrum

The increasing litter sizes of modern pig breeds have led to a significant number of piglets that are born undersized ("small" piglets) and some have been exposed to different degrees of intrauterine growth restriction (IUGR). The aim of this study was to investigate the physiology and capability to ingest colostrum of these small piglets, suffering from various degrees of IUGR, to see if their IUGR score could be a useful tool for easy identification of piglets in need of intervention in the colostrum period. Piglets were classified at birth based on head morphology. Piglets were classified either "normal," "mildly IUGR" (m-IUGR), or "severe IUGR" (s-IUGR), based on head morphology. Blood samples were collected at birth and at 24 h, and colostrum intake during two 12-h periods and blood metabolites at 0 and 24 h were measured. At 24 h, piglets weighing <900 g at birth and the median piglet in birth order were sacrificed, and organ weights and hepatic glycogen were measured. Overall, there was an influence of the piglets' classification on most characteristics, with normal piglets having a greater colostrum intake between 0 and 12 h (P < 0.001) and between 12 and 24 h (P < 0.05), and higher birth weight, crown rump length, body mass index, and ponderal index (P < 0.001), and a tendency toward a higher vitality score (P < 0.069) than s-IUGR piglets. There was a time × IUGR interaction, with plasma glucose levels being lowered (P < 0.001) and lactate levels elevated (P < 0.001) in s-IUGR piglets at 24 h compared with normal and m-IUGR piglets. Some differences were found in electrolytes; sodium plasma concentrations were greatest for normal piglets (P < 0.05) and highest at 0 h (P < 0.05). At 24 h of age, s-IUGR piglets had a higher heart (P < 0.001) and brain percentage (P < 0.001), and a lower liver percentage (P < 0.001) relative to body weight, compared with normal piglets. In addition, s-IUGR piglets had less hepatic glycogen than m-IUGR piglets and normal piglets. The present study showed that the physiology of piglets in the colostrum period was affected by IUGR status at birth and their intermediary metabolism was altered due to different colostrum intakes. Furthermore, it was demonstrated that the head shape of newborn piglets is a good selection criteria for identifying piglets that need oral supplementation during the neonatal stage.

Relationship between behavioural reactivity and feed efficiency in housed sheep

In this study we test the hypothesis that selecting sheep for a low behavioural reactivity to stressful situations will improve their metabolic efficiency, and thereby feed efficiency, during a controlled trial in an animal house. Twenty-four Merino wethers were used, 12 each from lines selected for high (HBR) and low (LBR) behavioural reactivity to stressful stimuli (human presence and social isolation). The sheep were habituated to the experimental procedures for 10 days, followed by 45 days during which voluntary feed intake was measured so that total daily energy intake was quantified. The sheep were weighed twice weekly before daily feeding. Feed efficiency was determined by measuring net feed intake, average daily weight gain and body condition score. Our hypothesis was not supported by the results of this study. There was no difference between LBR and HBR sheep in average daily weight gain or body condition score. The net feed intake of HBR sheep was lower than that of LBR sheep (P = 0.02), indicating that under the conditions of our experiment, HBR sheep were actually more feed efficient than LBR sheep. This study was carried out on sheep with steady intakes and in familiar surroundings. It is possible that LBR sheep may be more efficient than HBR sheep in more stressful situations.