Low Birth Weight Piglets Research Articles

Effects of bovine colostrum on performance, survival, and immunoglobulin status of suckling piglets during the first days of life

Supplementation of bovine colostrum (BC) has shown to improve growth performance, intestinal development, and immune response in early-weaned pigs. Little is known about whether BC may have similar effects in neonatal piglets. In the present study, the effect of BC supplementation on mortality, growth performance, and blood parameters (plasma proteins and white blood count) of suckling piglets in the first 10 days of life was investigated under practical conditions with special emphasis on low birth weight piglets. In total, 258 newborn piglets from 30 multiparous sows in a commercial breeding unit were randomly assigned to two different treatment groups. Piglets received either 1 ml of BC orally on days 1–3 of life (group BC, n = 128) or 1 ml of saline (0.9%) (control (CON) group; n = 130). Body weight was measured on days 1, 4, and 10 of life. Blood was collected on days 1 and 4 from 60 piglets per group. No differences in mortality, body weight, and average daily weight gain were observed between treatment groups in days 1–10. However, compared to CON, particularly in low birth weight piglets the administration of BC supported (P < 0.01) their survival. Group BC exhibited lower plasma total protein (P = 0.03) and beta-globulin (P = 0.02) concentrations compared to group CON. In conclusion, BC improved low and normal birth weight piglets’ survival during their first 10 days of life. Further research is needed to clarify whether the survival rate is related to earlier gut closure indicated by lower plasma protein levels, which might be beneficial due to a lower uptake of potential antigenic substances.

Effect of different management techniques to enhance colostrum intake on piglets’ growth and mortality

AbstractAn experiment was conducted to study the effect four different management techniques to enhance colostrum intake had on piglet and litter performance. Treatments were performed on piglets born weighing 1.30 kg or less (SP) within 6 h of birth: control group (CON); split-nursing of the litter for 2 h allowing only the SP piglets free access to teats (SPLIT); oral supplementation with 15 ml of sow colostrum to the SP piglets of the litter (COL); and oral supplementation with 3 ml of an energy product (Calostrene®) to the SP piglets of the litter (EN). Thirty-nine primiparous sows (Large White × Landrace) and their litters (507 piglets) and 100 multiparous sows and their litters (1,375 piglets) were used. Litters were fixed at 12 piglets. Piglets were weighed through lactation. Mortality was recorded. For primiparous sows, oral supplementation with COL enhanced SP piglets bodyweight (BW) at day 1 compared to CON, SPLIT, and EN. However, no differences on BW were observed at day 18 nor on litter total pre-weaning mortality. Nonetheless, lower SP piglets’ mortality rate was found in CON and EN compared to SPLIT and COL groups in primiparous sows. For multiparous sows, no differences among treatments were observed for SP piglets BW at day 1 or at day 18. Primiparous sows’ SP piglets had higher BW at day 1 than multiparous sows’ SP piglets. Colostrum supplementation of low birth weight piglets improved early weight gain in piglets born from primiparous sows, probably by enhancing their colostrum intake, but it did not affect piglets’ weaning BW or pre-weaning mortality.

Birthweight has no influence on chemical body composition and muscle energy stores in suckling piglets

Economic losses in pig production are highly due to neonatal mortality and poor postnatal growth performances predominantly of low birthweight piglets. To explore underlying mechanisms, we describe in this paper the effects of age and birthweight on body composition and muscle energy stores. Different parameters were assessed in pairs of low birthweight (LBW, n = 32) and normal birthweight (NBW, n = 32) piglets, at Day 0 (n = 16), Day 3 (n = 16), Day 10 (n = 16) and Day 28 (n = 16) of age. In total six piglets (three LBW and three NBW) per age group were killed for chemical total body composition analysis. The M. semimembranosus of 10 additional piglets (five LBW and five NBW) per age group were sampled for the analysis of muscle lipid and glycogen contents. Fore none of the tested parameters differences related to birthweight were observed (P > 0.05). With increasing age, dry matter, fat and protein percentages increased in both LBW and NBW piglets (P < 0.01). Body ash content remained constant during growth (P > 0.05). Muscle glycogen contents decreased with increasing age for both types of piglets (P < 0.05), whereas no age effects could be observed for muscle lipid deposition (P > 0.05). In conclusion, the age of the suckling piglet has a major impact on its body composition and muscle energy stores but its birthweight unexpectedly has no influence.

Very low birth weight piglets show improved cognitive performance in the spatial cognitive holeboard task.

Low birth weight (LBW) is common in humans and has been found to cause lasting cognitive and developmental deficits later in life. It is thought that the primary cause is intra-uterine growth restriction (IUGR) due to a shortage of oxygen and supply of nutrients to the fetus. Pigs appear to be a good model animal to investigate long-term cognitive effects of LBW, as LBW is common in commercially farmed breeds of pigs. Moreover, pigs are developmentally similar to humans and can be trained to perform complex tasks. In this study, we trained ten very low birth weight (vLBW) piglets and their ten normal birth weight (NBW) siblings in a spatial cognitive holeboard task in order to investigate long-term cognitive effects of LBW. In this task, four out of sixteen holes contain a hidden food reward, which allows measuring working memory (WM) (short-term memory) and reference memory (RM) (long-term memory) in parallel. Piglets were trained for 46–54 trials during the acquisition phase, followed by a 20-trial reversal phase in which a different set of four holes was baited. Both groups acquired the task and improved their performance over time. A mixed model repeated measures ANOVA revealed that vLBW piglets showed better RM performance than NBW piglets in both the acquisition and reversal phase. Additionally, WM scores in the vLBW were less disrupted than in the NBW animals when switched to the reversal phase. These findings are contrary to findings in humans. Moreover, vLBW pigs had lower hair cortisol concentrations (HCCs) than NBW pigs in flank hair at 12 weeks of age. These results could indicate that restricted intra-uterine growth causes compensatory mechanisms to arise in early development that result in beneficial effects for vLBW piglets, increasing their low survival chances in early-life competition.

Healthy birth weight results in higher vitamin A storage in neonate piglets administered high-dose supplements

A proposed intervention for newborn infants in countries with suspected vitamin A (VA) deficiency is to administer 50,000 IU retinyl palmitate at birth to reduce mortality risk. However, no studies have investigated birth weight effects. In this study, low birth weight (LBW; <1 kg, n = 18) and healthy birth weight (HBW) piglets (>1.5 kg, n = 18) from VA-depleted sows were dosed with 25,000 or 50,000 IU retinyl palmitate (26.2 or 52.4 µmol retinol equivalents) at birth to compare VA reserves. Blood was collected at varying times (n = 3-5/time/dose), and piglets were killed at 12 or 24 h for blood, liver, kidneys, spleen, lungs, adrenal gland, and intestinal contents. HBW piglets had significantly higher birth, death, and organ weights than LBW (P < 0.0001 for all). HBW and LBW piglets, which received VA, had higher liver and kidney VA concentrations (0.18 ± 0.09, 0.24 ± 0.10 µmol/g liver and 13.4 ± 4.1, 14.2 ± 4.5 nmol/g kidney, respectively) than controls (n = 10) (0.051 ± 0.01 µmol/g liver and 1.01 ± 0.43 nmol/g kidney) (P = 0.0061 and < 0.0001, respectively). Total liver (9.75 ± 5.16 µmol) and kidney retinol (204 ± 79.1 nmol) were higher in HBW than LBW piglets (P < 0.0001). Extrahepatic tissues, except lung, had higher VA concentration than controls (P < 0.0001). Serum retinol and ester concentrations were higher in treated than control piglets (P = 0.0028, P < 0.0001, respectively), and significantly changed during the times sampled (P = 0.022, P = 0.011, respectively). Peak serum retinyl ester concentrations, which occurred at 3 h, were higher in piglets that received 50,000 IU (4.2 ± 4.4 µmol/L) than 25,000 IU (2.7 ± 2.3 µmol/L) (P = 0.031). Regardless of dose amount, HBW piglets stored more supplemental VA than LBW piglets when administered at birth.

Decision-making under risk and ambiguity in low-birth-weight pigs.

Low birth weight (LBW) in humans is a risk factor for later cognitive, behavioural and emotional problems. In pigs, LBW is associated with higher mortality, but little is known about consequences for surviving piglets. Alteration in hypothalamic-pituitary-adrenal axis function in LBW pigs suggests altered emotionality, but no behavioural indicators have been studied. Decision-making under uncertain conditions, e.g., risk or ambiguity, is susceptible to emotional influences and may provide a means of assessing long-term effects of LBW in piglets. We tested LBW (N=8) and normal-birth-weight (NBW; N=8) male pigs in two decision-making tasks. For decision-making under risk, we developed a simple two-choice probabilistic task, the Pig Gambling Task (PGT), where an 'advantageous' option offered small but frequent rewards and a 'disadvantageous' option offered large but infrequent rewards. The advantageous option offered greater overall gain. For decision-making under ambiguity, we used a Judgement Bias Task (JBT) where pigs were trained to make an active response to 'positive' and 'negative' tone cues (signalling large and small rewards, respectively). Responses to ambiguous tone cues were rated as more or less optimistic. LBW pigs chose the advantageous option more often in later blocks of the PGT, and were scored as less optimistic in the JBT, than NBW pigs. Our findings demonstrate that LBW pigs have developed different behavioural strategies with respect to decision-making. We propose that this is guided by changes in emotionality in LBW piglets, and we provide behavioural evidence of increased negative affect in LBW piglets.

A high-protein formula increases colonic peptide transporter 1 activity during neonatal life in low-birth-weight piglets and disturbs barrier function later in life.

Dietary peptides are absorbed along the intestine through peptide transporter 1 (PepT-1) which is highly responsive to dietary protein level. PepT-1 is also involved in gut homeostasis, both initiating and resolving inflammation. Low-birth-weight (LBW) neonates are routinely fed a high-protein (HP) formula to enhance growth. However, the influence of this nutritional practice on PepT-1 activity is unknown. Intestinal PepT-1 activity was compared in normal-birth-weight (NBW) and LBW piglets. The effect of HP v. normal-protein (NP) formula feeding on PepT-1 activity and gut homeostasis in LBW piglets was evaluated, during the neonatal period and in adulthood. Flux of cephalexin (CFX) across the tissue mounted in Ussing chambers was used as an indicator of PepT-1 activity. CFX flux was greater in the ileum, but not jejunum or colon, of LBW than NBW piglets during the neonatal period. When LBW piglets were formula-fed, the HP formula increased colonic CFX during the 1st week of life. Later in life, intestinal CFX fluxes and barrier function were similar whether LBW pigs had been fed NP or HP formula. However, colonic permeability of HP- but not NP-fed pigs increased when luminal pH was brought to 6·0. The formyl peptide N-formyl methionyl-leucyl-phenylalanine conferred colonic barrier protection in HP-fed piglets. Heat shock protein 27 levels in the colonic mucosa of HP-fed LBW pigs correlated with the magnitude of response to the acidic challenge. In conclusion, feeding a HP formula enhanced colonic PepT-1 activity in LBW pig neonates and increased sensitivity of the colon to luminal stress in adulthood.

Behaviour and growth performance of low-birth-weight piglets cross-fostered in multiparous sows with piglets of higher birth weights

The aim of the study was to evaluate the behaviour, pre-weaning survival rate and growth performance of low birth weight (BW) piglets cross-fostered with piglets of higher weights. Piglets were transferred to 60 foster sows, and divided in three groups (G; n=20): G1- 12 low BW piglets (0.80 - 1.25kg); G2- six low BW piglets and six intermediate BW piglets (1.40 - 1.60kg), and G3- six low BW piglets and six high BW piglets (&gt;1.70kg). For the analysis, groups G2 and G3 were subdivided in LG2 (six G2 light piglets); IG2 (six G2 intermediate piglets), LG3 (six G3 light piglets), and HG3 (six G3 heavy piglets). Behavioural observations were carried out on days 1, 2, 4 and 6 (visual direct observation) and on days 3 and 5 (video recording) after birth. The percentage of missed nursings was higher in LG3 piglets than in LG1, IG2 and HG3 piglets, on days 1 and 2. On day 4, light piglets (LG1, LG2 and LG3) missed more nursings than IG2 and HG3 piglets. On day 3, video recording showed a higher percentage of missed nursings in LG1, LG2, and LG3 piglets as compared to HG3 piglets. On day 1, the number of fights during nursing was higher in IG2 than in LG1 and LG3 piglets. Also on day 1, number of fights and percentage of piglets engaged in fights, during 15min after nursing, were higher in LG1, LG3 and HG3 than in LG2 piglets. More playful behaviours were observed on day 2 in IG2 and HG3 piglets compared to LG1, LG2 and LG3 piglets. Light piglets (LG1, LG2, and LG3) presented similar body weight on days 4, 8, 12 and 16 after birth, regardless of being mixed with piglets of higher weights or not; however, the survival rate until day 16 was most compromised in LG3 piglets compared to the other groups. Despite the lack of influence of littermates' weight on the growth of low BW piglets, their survival rate indicates that they should not be mixed with high BW piglets.

Impact of vitamin A supplementation in low birth weight piglets similar to healthy weight piglets (645.17)

Current vitamin A supplementation methods for infants in vitamin A‐deficient populations have no specific dosing recommendations regarding birth weight. A proposed intervention is to administer 50,000 IU retinyl palmitate to newborn infants to reduce mortality risk. To investigate birth weight effects, low birth weight (LBW) piglets (1.5 kg) from vitamin A‐depleted sows were dosed with either 25,000 or 50,000 IU retinyl palmitate at birth to compare liver vitamin A reserves and overall vitamin A status. Blood collection occurred at varying time points after dose and piglets were killed at 12 and 24 h for organ and serum collection. Serum, liver, kidneys, spleen, lungs, adrenals, and intestinal contents were collected and analyzed for vitamin A using HPLC methods. Both healthy weight and LBW piglets had significantly higher liver and kidney vitamin A concentrations than control piglets that received no dose (P = 0.0061 and &lt;0.0001, respectively), but no significant differences between dose, weight, or time groups existed. However, total liver and kidney retinol was higher in healthy weight piglets (P &lt; 0.0001). Vitamin A concentration in lung, spleen, and adrenal glands did not differ between any treated and control piglets. Serum retinol significantly increased with time for all treated piglets, regardless of birth weight (P = 0.005), but dose and weight had no effect on serum retinol concentration. In conclusion, healthy weight piglets stored more of the supplemental doses than LBW piglets.Grant Funding Source: Supported by the Nutrition Unit at the World Health Organization.

Mechanistic studies in swine to evaluate newborn infant vitamin A dosing strategies (260.1)

Clinically, infant care is challenging especially in resource‐poor developing countries where small‐for‐gestational‐age is common and in any country when an infant is born prematurely. Several components comprise perinatal mortality of infants. Children suffering from vitamin A deficiency have a greater risk of irreversible blindness and dying from infectious diseases. Supplementation programs are an approach to address this issue. Studies have found little or no improvement in infant vitamin A status after supplementing with 25,000 IU vitamin A. Based on WHO’s recommendations, children ages 6 ‐ 11 mo receive 100,000 IU vitamin A and those 12 ‐ 59 mo receive 200,000 IU vitamin A every 4 to 6 mo. Multi‐centered and randomized trials of infant supplementation programs have shown inconsistent results. Infant supplementation itself has been debated due to the higher incidence of bulging fontanelle in vitamin A‐dosed infants. Therefore, a series of studies were performed in a swine model to evaluate infant dosing regimens. Newborn piglets from vitamin A‐depleted sows received a placebo, 25,000, 50,000, or 200,000 IU vitamin A supplements at birth. Tissues were collected and analyzed. The degree of vitamin A deficiency did not seem to affect the response to treatment. High doses may be quickly catabolized to maintain balance. Lung and spleen require chylomicron vitamin A to maintain concentrations, which was confirmed with a tracer study using α‐retinol. The tracer study also showed quick uptake in the adrenal gland. Low birth weight piglets took up less vitamin A. Food sources of vitamin A performed better than supplementation at improving vitamin A status of offspring.Grant Funding Source: Supported by the Nutrition Unit at the World Health Organization.

Management strategies to improve the performance of low birth weight pigs to weaning and their long-term consequences1,2

Performance of pigs from birth to slaughter is a result of a complex interaction of factors, with the early stages of a pig's life likely to affect lifetime performance. During the preweaning stage, piglets are reliant on the sow for nutrition, and sibling competition is likely to affect growth, in particular for low birth weight (LBiW) piglets. The objective of the experiment was to determine the effect of litter composition (littermate weight) and milk supplementation during lactation on the performance of LBiW pigs to weaning and the long-term consequences of treatment to slaughter. The experiment was a 2 × 2 factorial with littermate weight (normal or LBiW) and provision of supplementary milk from d 1 to 28 (yes or no) as factors. A total of 265 piglets were selected within 24 h of birth and cross-fostered to create 2 litter types (LOW = LBiW pigs [≤ 1.25 kg] only and MX = both LBiW and normal birth weight pigs [1.6 to 2.0 kg]); half of the litters within a type were supplemented with milk and the other half were not. The behavior of litters given milk was recorded to identify milk consumption patterns. Piglets were weaned at d 28 and kept in their litters until d 70 and then subsequently housed in mixed groups until slaughter. No difference was observed at any stage in the ADG of pigs given access to supplementary milk or not (P > 0.05) nor was there any significant interaction between milk provision and litter composition (P > 0.05). However, LOW litters drank significantly more supplementary milk than MX litters (P < 0.001). There was a significant effect of litter type on ADG from d 14 to 28, with LBiW pigs in LOW litters performing better than those in MX litters (0.252 versus 0.217 kg/d; P < 0.05). At weaning, LBiW piglets in LOW litters weighed over 500 g more than those in MX litters (P < 0.05). In MX litters there was a significant interaction between birth weight and supplementary milk on the CV of BW from d 14 to slaughter (P < 0.05). In conclusion, grouping LBiW piglets with similar sized littermates preweaning can improve preweaning performance by reducing competition from heavier littermates; however, this advantage does not persist after weaning. Although supplementary milk does not improve LBiW pig performance before or after weaning, it affects their drinking behavior and can reduce the variation in the BW of LBiW piglets in mixed litters to slaughter.

Effect of birth weight and colostrum intake on mortality and performance of piglets after cross-fostering in sows of different parities

The objective of this study was to evaluate the effect of colostrum intake on mortality and growth performance of piglets until 42 days of age, taking into account the birth weight, and parity order of sows. Colostrum intake from birth to 24h after birth was estimated in 300 piglets each from primiparous and multiparous sows. The piglets were cross-fostered in 25 primiparous and 25 multiparous sows at 25.9±0.09h after farrowing. The concentration of serum immunoglobulin G (IgG) was determined in the sows after the end of farrowing and in the piglets before cross-fostering (24h after farrowing), at 10 and 20 days of age. For high birth weight piglets (HBW – >1.3–1.7kg) the probability of death was low regardless of their colostrum intake. Intermediate birth weight (IBW – >1.2–1.3kg) and low birth weight (LBW – 1.1–1.2kg) piglets had the same probability of death compared to HBW piglets, when colostrum intake reached 200 and 250g, respectively. The probability of low performance (<9.5kg) was lower in HBW than in LBW and IBW piglets, regardless of colostrum intake. HBW piglets had higher weight at 14, 20, 28 and 42 days of age (P<0.05) than LBW piglets, and higher weight than IBW piglets at 28 and 42 days. Colostrum intake >250g increased (P<0.05) the weight of piglets at 28 and 42 days of age, regardless of their birth weight. Piglets from primiparous biological dams consumed less colostrum (P<0.003) than piglets from multiparous dams, but their serum IgG concentrations at 24h after birth and their performance were similar (P>0.05). Piglets suckled by primiparous foster sows showed lower weight (P<0.05) at 20, 28 and 42 days than piglets suckled by multiparous sows. Piglets that died before 42 days of age had lower (P<0.05) birth weight, colostrum intake and serum IgG at 24h after birth compared to surviving piglets, and lower values were also observed in piglets with low performance compared to high (>9.5kg) performance piglets. There were no differences in serum IgG concentrations at 10 and 20 days of age (P>0.05) between high and low performance piglets. In conclusion, both colostrum intake and birth weight are important for survival and growth of suckling piglets. LBW and IBW piglets are more dependent on colostrum intake than HBW piglets to assure higher survival and better development up to 42 days of age. Piglets suckled by multiparous sows have better development than those suckled by primiparous sows.

The effect of birth weight and age at tail docking and ear notching on the behavioral and physiological responses of piglets1

Selection for high prolificacy has resulted in litters comprising a large number of low-birth-weight (LBW) piglets. Given their presence in over 75% of litters and increased mortality rate, it is clear that a greater understanding of LBW piglet management is required for both animal welfare and productivity. In this study, we compared the effects of tail docking and ear notching LBW and average-birth-weight (ABW) piglets at 1 or 3 d of age on suckling, behavior, passive transfer of immunoglobulins, and growth. Six piglets per litter from 20 litters (n = 120 piglets) were used in a 2 × 2 complete block design. Piglets were weighed at birth and designated as LBW (0.6 to 1.0 kg) or ABW (≥ 1.2 kg) and "processed" (tail docked and ear notched) at either 1 or 3 d of age. Vocalizations were recorded during the procedures. The acute behavioral responses were observed for 10 min after the procedure. Piglets were observed for 6 h after birth and after the procedure to determine their presence at nursing bouts. On d 5, blood samples were collected to determine concentrations of serum immunoglobulins (IgA and IgG) and IGF-I. Piglet weights were recorded at birth and on d 5, 14, and 21. During the procedures, LBW piglets produced fewer (P = 0.03) calls than ABW piglets. Piglets from either birth weight category produced a similar number (calls/s; P = 0.29) of high-frequency calls (≥ 1,000 Hz), which are indicative of pain and distress, although the average frequency (Hz) of these calls was greatest (P = 0.05) for ABW piglets processed on d 3. Immediately following the procedures, LBW piglets spent more (P = 0.005) time dog-sitting and less (P = 0.005) time lying than ABW piglets. When observed with the sow, LBW males spent more (P = 0.001) time alone and had the lowest (P = 0.007) attendance at nursing bouts compared with LBW females and all ABW piglets. Concentrations of serum IgA (P = 0.06) and IgG (P = 0.04) and plasma IGF-I (P = 0.003) were lower for LBW than ABW piglets regardless of age of processing although the magnitude of these differences was likely not of biological significance. Average-birth-weight piglets may be less reactive to the acute effects of the procedures on d 1 than on d 3. Given the decreased likelihood of a LBW piglet surviving to weaning (P = 0.001), delaying processing until 3 d of age for LBW piglets may eliminate unnecessary procedures.

Birth weight alters the response to postnatal high-fat diet-induced changes in meat quality traits and skeletal muscle proteome of pigs

Low birth weight (LBW) exerts persistent effects on the growth and development of offspring. The present study was conducted to test the hypothesis that LBW alters the response of pigs to high-fat (HF) diet-induced changes in meat quality and skeletal muscle proteome. Normal-birth weight (NBW) and LBW piglets were fed a control diet or a HF diet from weaning to slaughter at 110kg body weight. Most of the meat quality traits were influenced by LBW. Meat quality analysis revealed that LBW piglets had a greater ability to deposit intramuscular lipids than their heavier littermates when fed a HF diet. Increased shear force, lower pH45 min and drip loss were observed in the skeletal muscle of LBW piglets compared with NBW piglets. Proteomic analysis revealed forty-six differentially expressed proteins in the skeletal muscle of LBW and NBW piglets fed the control diet or HF diet. These proteins play a central role in cell structure and motility, glucose and energy metabolism, lipid metabolism, and cellular apoptosis, as well as stress response. Of particular interest is the finding that LBW altered the response to HF diet-induced changes in the expression of proteins related to stress response (heat shock protein) and glucose and energy metabolism (pyruvate kinase, phosphoglycerate mutase, enolase and triosephosphate isomerase). Taken together, our findings revealed that the HF diet-induced changes in the expression of glucose and energy metabolism-related proteins varied between NBW and LBW piglets, which provides a possible mechanism to explain higher intramuscular fat store in LBW pigs when fed a HF diet.

Chronic Allopurinol Treatment during the Last Trimester of Pregnancy in Sows: Effects on Low and Normal Birth Weight Offspring

Low-birth-weight (LBW) children are born with several risk factors for disease, morbidity and neonatal mortality, even if carried to term. Placental insufficiency leading to hypoxemia and reduced nutritional supply is the main cause for LBW. Brain damage and poor neurological outcome can be the consequence. LBW after being carried to term gives better chances for survival, but these children are still at risk for poor health and the development of cognitive impairments. Preventive therapies are not yet available. We studied the risk/efficacy of chronic prenatal treatment with the anti-oxidative drug allopurinol, as putative preventive treatment in piglets. LBW piglets served as a natural model for LBW. A cognitive holeboard test was applied to study the learning and memory abilities of these allopurinol treated piglets after weaning. Preliminary analysis of the plasma concentrations in sows and their piglets suggested that a daily dose of 15 mg.kg−1 resulted in effective plasma concentration of allopurinol in piglets. No adverse effects of chronic allopurinol treatment were found on farrowing, birth weight, open field behavior, learning abilities, relative brain, hippocampus and spleen weights. LBW piglets showed increased anxiety levels in an open field test, but cognitive performance was not affected by allopurinol treatment. LBW animals treated with allopurinol showed the largest postnatal compensatory body weight gain. In contrast to a previous study, no differences in learning abilities were found between LBW and normal-birth-weight piglets. This discrepancy might be attributable to experimental differences. Our results indicate that chronic prenatal allopurinol treatment during the third trimester of pregnancy is safe, as no adverse side effects were observed. Compensatory weight gain of treated piglets is a positive indication for the chronic prenatal use of allopurinol in these animals. Further studies are needed to assess the possible preventive effects of allopurinol on brain functions in LBW piglets.

Effects of birth weight and maternal dietary fat source on the fatty acid profile of piglet tissue

This study aimed to investigate the effects and possible interactions of birth weight and n-3 polyunsaturated fatty acid (PUFA) supplementation of the maternal diet on the fatty acid status of different tissues of newborn piglets. These effects are of interest as both parameters have been associated with pre-weaning mortality. Sows were fed a palm oil diet or a diet containing 1% linseed, echium or fish oil from day 73 of gestation. As fish oil becomes a scarce resource, linseed and echium oil were supplemented as sustainable alternatives, adding precursor fatty acids for DHA to the diet. At birth, the lightest and heaviest male piglet per litter were killed and samples from liver, brain and muscle were taken for fatty acid analysis. Piglets that died pre-weaning had lower birth weights than piglets surviving lactation (1.27±0.04 v. 1.55±0.02 kg; P<0.001), but no effect of diet on mortality was found. Lower DHA concentrations were observed in the brain of the lighter piglets compared with their heavier littermates (9.46±0.05 v. 9.63±0.04 g DHA/100 g fatty acids; P=0.008), suggesting that the higher incidence of pre-weaning mortality in low birth weight piglets may be related to their lower brain DHA status. Adding n-3 PUFA to the sow diet could not significantly reduce this difference in DHA status, although numerically the difference in the brain DHA concentration between the piglet weight groups was smaller when fish oil was included in the sow diet. Independent of birth weight, echium or linseed oil in the sow diet increased the DHA concentration of the piglet tissues to the same extent, but the concentrations were not as high as when fish oil was fed.

Fatty acid profile, oxidative stability of pork lipids and meat quality indicators are not affected by birth weight

The aim of this study was to investigate whether fatty acid (FA) profile, oxidative stability of lipids and other meat quality traits differed between high (HW: 1.8 to 2.2 kg) and low (LW: 0.8 to 1.2 kg) birth weight piglets. Forty new-born male pigs (n=20 HW, n=20 LW) were reared in separate pens until the finishing period, when they were slaughtered at 150 days of age, and pH and temperature were measured in the carcass. Afterwards, the Longissimus dorsi muscle was excised from the carcass, and samples were collected for subsequent meat quality analyses (thaw loss, cooking loss, shear force, chemical analysis and sensory analysis for tenderness). Birth weight had minor impacts on meat quality traits, which were limited to higher shear force in the LW group (P<0.01). Chemical components (moisture, protein, fat, ash), cholesterol levels and lipid oxidation (thiobarbituric acid-reactive substances) were not affected by birth weight (P>0.05). FA profile and the amount of saturated, monounsaturated and polyunsaturated fatty acids were similar, but HW pigs had higher atherogenic index than their LW counterparts (P<0.01). Notwithstanding the higher shear force presented by the lower birth weight pigs, in the sensory test, the panelists did not detect any differences in the tenderness of pork from HW and LW animals. Therefore, our results suggest that low birth weight has minimal impact on meat quality.

Artificial rearing of piglets: Effects on small intestinal morphology and digestion capacity

The use of hyper-prolific sows results in large litters but also leads to an increasing number of supernumerary and underprivileged (e.g. low birth weight (LBW)) piglets. The effects of artificial rearing on the growth, small intestinal morphology and digestion capacity of these piglets remain unclear. Therefore, the aim of this study was to assess the effect of sow-feeding versus formula-feeding on piglets' structural and functional gut maturation. To this purpose, pairs of LBW and normal birth weight (NBW) piglets (n=40) were allocated to four treatment groups. Groups 1 and 2 contained piglets that suckled until either d 10 or 28 of age, respectively. Groups 3 and 4 contained animals that suckled until 3d of age and were then formula-fed until either d 10 or 28. During d 3–10, formula-fed piglets showed reduced average daily gain (ADG; −112gd−1) and lactase activities (−4.50Ug−1 tissue) compared to suckling piglets (P<0.01). In contrast, animals that were formula-fed until d 28 had a comparable ADG compared to sow-fed pigs. In addition, formula-fed piglets had a greater absorptive area (P<0.01; +59.1μm2), maltase and sucrase activities (P<0.05; +0.97 and +0.23Ug−1 tissue) and deeper crypts (P<0.03; +42.5μm) compared to suckling piglets. In general, the differences between LBW and NBW piglets were scarce. These results suggest that the combination of ad libitum access to formulated milk and an increased capacity to absorb nutrients makes artificial rearing a good alternative to raise supernumerary and/or LBW piglets.

Long-term effects of prenatal allopurinol treatment on brain plasticity markers in low and normal birth weight piglets

In this study, we investigated the effect of antenatal allopurinol (ALLO) treatment on levels and expression of plasticity markers in the dorsal hippocampus of low (LBW) and normal (NBW) birth weight piglets. ALLO treatment given daily in the last trimester to pregnant sows had a protective effect on neuronal plasticity markers in their piglets. ALLO increases protein levels of BDNF and the postsynaptic marker PSD95 in LBW and NBW piglets. ALLO treatment increases the pCREB/CREB ratio in LBW piglets to a similar level as that found in untreated NBW piglets. In conclusion, antioxidant treatment administered in the last trimester might be a promising treatment for LBW neonates.

Growth and small intestine histomorphology of low and normal birth weight piglets during the early suckling period

The present study compared growth performance and small intestinal histomorphological changes between low birth weight (LBW) and normal birth weight (NBW) piglets at day 0 and day 7 postpartum. The LBW and NBW piglets (Large White×Landrace×Duroc) from five multiparous crossbred sows were used. At birth, all piglets were weighed and classified into LBW (0.8–1.0kg) or NBW (1.4–1.6kg) piglets. At days 0 and 7 postpartum, one LBW and one NBW piglets per sow were randomly selected and euthanized for sample collection. The results showed that at day 7, the average daily gain and percentage change of body weight from day 0 of LBW piglets were not different from NBW piglets; however, their body weights were still lower than those of NBW piglets (P<0.01). The organ weights including small intestine, large intestine, liver, spleen and kidney as normalized per 100g of body weight showed no difference between LBW and NBW piglets at the same day; but they increased with age (P<0.05). The histomorphological changes of small intestine revealed that the villus height and crypt depth were not different between groups at the same day; but they increased with age (P<0.01). In terms of the enterocyte turnover rate as determined by the ratio of villus height to crypt depth, at day 7, the LBW piglets had a higher ratio of villus height to crypt depth with significant effect at the duodenum (P<0.05). Additionally, the proliferative marker index (Ki-67) was also greater in LBW than NBW piglets at day 7 with significant effect at the ileum (P<0.05). These results indicated that the LBW piglets grew at the same rate as NBW piglets with undisturbed organ developments as evidenced by the similar average daily gain, percentage change of body weight and normalized organ weights. Furthermore, the difference in enterocyte proliferation and turnover rate of the small intestine indicated a difference in small intestine development and function between LBW and NBW piglets. These data suggest that the LBW piglets were not only different from their NBW littermates in the body weight but also in small intestinal histomorphology.