Influence of sow dietary fatty acid composition on the behaviour of the piglets

Polyunsaturated fatty acids (PUFA) are essential for the development of the nervous system in animals, and increased concentration of n−3 PUFA in maternal diet improves the cognitive development of mammalian foetuses. In this study the effect of maternal diet fatty acid composition in pigs on the development of the central nervous system, monitored as behaviour of piglets, was investigated using three behavioural tests: recognition of the mother's faeces, back test, and hidden door test.Twenty-seven multiparous Yorkshire sows were split into four groups and fed diets with different content of fat and PUFA throughout pregnancy and lactation. LF (n = 6) was fed a standard diet, HFS (n = 4) a high fat and low PUFA diet, HFO (n = 7) a high n−6 PUFA diet, and HFL (n = 10) a high n−3 PUFA diet.Three behavioural tests were performed on 5–7 randomly chosen piglets per litter (n = 167). Recognition of the mother's faeces was tested in a maze two days after birth. Back test was performed twice (2–4 d and 4 w) and a hidden door test was performed at 4 w. In addition, the brain content of docosahexaenoic acid (22:6 n−3, DHA) of the newborn piglets was determined in treatment groups. Data from the tests were analysed with linear mixed models for each of the tests.Piglets from HFL treatment had significantly higher content of DHA (P < 0.001) and the ratio of n−6/n−3 PUFA was significantly lower in brain tissue (P < 0.001), compared to piglets from the other treatments. In parity 3, means for recognition for mother's faeces were for diets LF, HFS, HFO and HFL; 22.2, 37.0, 26.4 and 18.0%, respectively (P < 0.05), but no other significant effect of diet was found. Piglets in HFS treatment had the shortest latency to make escape attempts and HFO piglets the longest latency in the back test (P = 0.030). No significant effect of sow diet was found on piglet performance in the hidden door test, but intermediate piglets weighing 1410–1619 g had a lower probability of success in hidden door test than piglets weighing < 1410 g (P = 0.028), and ≥ 1875 g (P = 0.027), respectively.It was found that sow diet influenced the DHA content in the piglet brains, but there was no clear effect of sow diet on piglet behaviour. In order to draw any conclusions about possible enhancements of the behavioural development of the piglet more studies need to be performed.     

The effect of different concentrations of linseed oil or fish oil in the maternal diet on the fatty acid composition and oxidative status of sows and piglets

N‐3 polyunsaturated fatty acids (PUFA) are essential for foetal development. Hence, including n‐3 PUFA in the sow diet can be beneficial for reproduction. Both the amount and form (precursor fatty acids vs. long chain PUFA) of supplementation are important in this respect. Furthermore, including n‐3 PUFA in the diet can have negative effects, such as decreased arachidonic acid (ARA) concentration and increased oxidative stress. This study aimed to compare the efficacy to increase eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) concentrations in the piglet, when different concentrations of linseed oil (LO, source of precursor α‐linolenic acid) or fish oil (FO, source of EPA and DHA) were included in the maternal diet. Sows were fed a palm oil diet or a diet including 0.5% or 2% LO or FO from day 45 of gestation until weaning. Linoleic acid (LA) was kept constant in the diets to prevent a decrease in ARA, and all diets were supplemented with α‐tocopherol acetate (150 mg/kg) and organic selenium (0.4 mg/kg) to prevent oxidative stress. Feeding 0.5% LO or 0.5% FO to the sows resulted in comparable EPA concentrations in the 5‐day old piglet liver, but both diets resulted in lower EPA concentrations than when 2% LO was fed. The highest EPA concentration was obtained when 2% FO was fed. The DHA level in the piglet liver could only be increased when FO, but not LO, was fed to the sows. The 2% FO diet had no advantage over the 0.5% FO diet to increase DHA in the piglet. Despite the constant LA concentration in the sow diet, a decrease in ARA could not be avoided when LO or FO were included in the diet. Feeding 2% FO to the sows increased the malondialdehyde concentration (marker for lipid peroxidation) in sow plasma, but not in piglets.     

Influence of dietary fat source on sow and litter performance,colostrum and milk fatty acid profile in late gestation and lactation

The objective of this study was to investigate the effects of dietary supplementation with various fat sources (3.8–3.9% of diet) during late pregnancy and lactation on the reproductive performance, fatty acids profile in colostrum, milk and serum of sow progeny. A total of 80 multiparous sows were randomly fed a control (adding no oil), palm oil (PO), fish oil (FO) or soybean oil (SO) supplemented diet from 90 days of pregnancy to weaning. Supplementation of FO increased litter size of weak piglets, compared with the control‐fed sows (P < 0.05). Dietary FO and SO supplementation, enhanced the weaning survival rate, litter weaning weight, litter weight gain and fat content in milk (P < 0.05). The highest immunoglobulin (Ig)G and IgM levels in colostrum and milk were observed in the FO group (P < 0.05). Meanwhile, the highest concentration of C22:5 (n‐3) and C22:6 (n‐3) in colostrum, milk and piglet serum was observed in the FO group (P < 0.05). Taken together, dietary inclusion of FO or SO improved growth performance of nursing piglets by increasing milk fat output, and FO consumption by sows might benefit the piglets via increasing n‐3 polyunsaturated fatty acid availability and immunoglobulins (IgG and IgM) secretion.     

Effects of dietary Forsythia suspensa extract supplementation to lactating sows and nursery pigs on post-weaning performance,antioxidant capacity,nutrient digestibility,immunoglobulins, and intestinal health

The aim of this study was to determine the effect of dietary Forsythia suspensa extract (FSE) supplementation to lactating sows and nursery pigs on post-weaning performance, antioxidant capacity, immunoglobulins, and intestinal health. Based on backfat, body weight (BW), and parity, 24 gestating sows (Landrace × Yorkshire) with average parity of 3.38 ± 0.61 and BW of 234 ± 6.81 kg were allotted into two dietary treatments (control vs. 100 mg/kg FSE) with 12 sows per treatment from day 107 of gestation to day 21 of lactation. After weaning, based on the initial BW and source litter, 192 nursery pigs (Duroc × [Landrace × Yorkshire], average BW of 6.98 ± 0.32 kg, weaned at day 21) were allotted into four dietary treatments with eight replicate pens per treatment, six pigs per pen for a 4-wk study. The treatments included the following: 1) CC (sows and their piglets both fed control diet); 2) CF (sows fed control diet and their piglets fed FSE diet [containing 100 mg/kg FSE]); 3) FC (sows fed FSE diet and their piglets fed control diet); and 4) FF (sows and their piglets both fed FSE diet). The MIXED procedures of SAS for a split-plot arrangement with sow diet as the whole plot and nursery diet as split plot were used to analyze the data. After weaning, piglets from FSE-fed sows had improved (P < 0.05) average daily gain and feed efficiency, and lower (P < 0.05) diarrhea rate in overall (day 1 to 28) compared with those from sows fed control diet. Piglets from FSE-fed sows also had higher (P < 0.05) contents of immunoglobulin G (IgG), growth hormone, superoxide dismutase (SOD), total antioxidant capacity in serum, villus height in ileum, and villus height to crypt depth ratio in jejunum, as well as lower (P < 0.05) content of malondialdehyde (MDA) in serum and crypt depth in ileum compared with those from sows fed control diet. Piglets fed FSE during nursery had increased (P < 0.05) concentrations of IgG, SOD, and catalase, and decreased (P < 0.05) MDA and tumor nuclear factor-α levels in serum compared with those fed control diet during nursery. Piglets from FC group had increased (P < 0.05) protein expression of occludin in jejunal mucosa and relative abundance of Lactobacillus on genus level in colon compared with those from CC group. In conclusion, for the performance and intestinal health, diets supplemented with FSE during lactation phase seemed more efficient to alleviate weaning stress than the nursery phase. In terms of the antioxidant status and immunoglobulins, FSE supplemented in both phases were efficient for nursery pigs.     

Potassium diformate in the diet of reproducing sows: Effect on performance of sows and litters

The effects of adding potassium diformate (K-diformate) to diets for primiparous and multiparous sows (Dutch × Scandinavian Landrace) (n = 156) were evaluated with respect to performance of sows and their litters, apparent total tract digestibility (TD) of nutrients, milk composition, and microbiota of sows' feces. Treatments comprised a basal diet and a basal diet containing 0.8 or 1.2% K-diformate. The experiment lasted from mating, through gestation and lactation until the next mating. Sows were fed restrictively according to a commercial feeding regime during the gestation period, and had free access to feed from d 10 post-farrowing. The addition of K-diformate to diets increased backfat thickness (P = 0.03) of sows during gestation. No effects on average daily feed intake or body weight gain were seen. Piglets born to sows receiving K-diformate tended to have increased individual (P = 0.05) and litter (P = 0.08) birth weight, tended to have increased average daily gain (ADG) (P = 0.07) and to be heavier at weaning (P < 0.05). Birth weights, ADG, and weaning weights were similar for piglets born from sows fed 0.8 and 1.2% K-diformate. There was no effect of K-diformate on the number of pigs born alive, number of stillborns or mortality rates of piglets. Adding 1.2% K-diformate to diets increased TD of ash by 4.9% (P = 0.001) and crude fat by 3.4% (P = 0.08), and calculated NE-content by 2.3% (P = 0.02). Sows fed K-diformate tended (P = 0.09) to show an increased milk fat content on d 12 post-farrowing. In conclusion, adding K-diformate to diets for sows had a positive effect on sows' backfat thickness in gestation and on growth performance of piglets.     

Effects of dietary resveratrol supplementation during gestation and lactation of sows on milk composition of sows and fat metabolism of sucking piglets

The purpose of this article was to investigate the effects of dietary resveratrol supplementation during gestation and lactation of sows on the milk composition of sows and the fat metabolism of sucking piglets. Forty sows were allotted to two experimental treatment groups that included the following: (a) control sows (CON treatment, n = 20) fed with a corn–soybean meal control diet and (b) treatment sows (RES treatment, n = 20) fed with a control diet with addition of 300 mg/kg resveratrol. The results showed that the content of lactose in the colostrum was increased (p < 0.05) and the content of fat in 21‐day milk was increased (p < 0.05) by dietary resveratrol supplementation. In the RES treatment group, the concentrations of high‐density lipoprotein‐cholesterol (HDL‐C), low‐density lipoprotein‐cholesterol (LDL‐C), lipase activity and insulin (INS) in plasma of sucking piglets were increased (p < 0.05). In the adipose tissue, the enzyme activities of hormone‐sensitive lipase (HSL), acetyl‐CoA carboxylase (ACC) and lipoprotein lipase (LPL) increased significantly by RES treatment (p < 0.05), and the mRNA levels of acetyl coenzyme A‐alpha (ACCα), LPL, fatty acid transport protein (FATP1) and CCAAT–enhancer‐binding protein gene (C/EBPα) were higher in the RES treatment group (p < 0.05). In conclusion, resveratrol supplementation on gestational and lactating sows improved the content of lactose in the colostrum and the content of fat in milk at day 21 of lactation. In addition, resveratrol supplementation on sows increased HDL and LDL in the plasma of piglets. In piglet adipose tissue, the enzyme activity and mRNA level related to lipolysis, fatty acid uptake from circulating triacylglycerols and lipogenesis are partially improved by resveratrol supplementation on sows. These aspects affect fat metabolism in piglets.     

Lactation efficiency as a result of body composition dynamics and feed intake in sows

Through genetic selection and improvement of environment, litter size of sows increases. Increased energy requirement during lactation, increases the risk of excessive mobilization from body stores, with detrimental effects on reproductive performance. Feed intake capacity tends to decrease due to selection towards leaner pigs with a lower feed conversion ratio. However, to facilitate sows to wean large litters extra feed intake, or even better, a higher feed efficiency during lactation would be favourable. The objective of the present study was to describe the dynamics of body composition of sows and piglets during lactation, and to relate these traits to a newly introduced trait called “lactation efficiency”. Energy metabolism of lactating sows was described, based on on-farm observations of weight and backfat of sows before parturition and at weaning, weight of piglets at birth and at weaning and feed intake of sows during lactation. “Lactation efficiency” was defined as energy efficiency of sows, and calculated for individual sows at two different farms. The average lactation efficiency was 68% and 65% for both farms; meaning that 68 and 65% of the metabolisable energy through feed intake or mobilization from body stores, above maintenance of the sow (input), was used for piglet growth and piglet maintenance (output). The association between lactation efficiency and other reproductive traits was studied by estimating the correlations within farms. Sows with a higher lactation efficiency showed lower feed intake (r = − 0.27 and r = − 0.35 for both farms respectively) and smaller fat losses (r = − 0.34 and r = − 0.29, respectively). The energy output of efficient sows was slightly higher (r = 0.23 and r = 0.30). The more efficient sows were the better mothers, as mortality of their piglets was lower (r = − 0.12 and r = − 0.16), piglet growth rate was higher (r = 0.16 and r = 0.23), and at weaning their litters were less variable (r = − 0.08; only available at one farm). Results were remarkably similar for the two farms, despite different feeding strategies. Extra input, by means of feed intake or mobilization from body stores generated extra output by means of litter weight at weaning. This experiment demonstrated that an accurate recording of energy metabolism and relevant reproduction traits with little intervention is possible on commercial farms.     

Effects of Dietary Supplementation of β‐hydroxy‐β‐methylbutyrate on Sow Performance and mRNA Expression of Myogenic Markers in Skeletal Muscle of Neonatal Piglets

The effects of dietary β‐hydroxy‐β‐methylbutyrate (HMB) supplementation during gestation on reproductive performance of sows and the mRNA expression of myogenic markers in skeletal muscle of neonatal pigs were determined. At day 35 of gestation, a total of 20 sows (Landrace × Yorkshire, at third parity) were randomly assigned to two groups, with each group receiving either a basal diet or the same diet supplemented with 4 g/day β‐hydroxy‐β‐methylbutyrate calcium (HMB‐Ca) until parturition. At parturition, the total and live litter size were not markedly different between treatments, however, the sows fed HMB diet had a decreased rate of stillborn piglets compared with the sows fed the control (CON) diets (p < 0.05). In addition, piglets from the sows fed HMB diet tended to have an increased birth weight (p = 0.08), and a reduced rate of low birth weight piglets (p = 0.05) compared with piglets from the CON sows. Nevertheless, lower feed intake during lactation was observed in the sows fed the HMB diet compared with those on the CON diet (p < 0.01). The relative weights of the longissimus dorsi (LD) and semitendinosus (ST) muscle were higher (p < 0.05) in neonatal pigs from the HMB than the CON sows. Furthermore, maternal HMB treatment increased the mRNA levels of the myogenic genes, including muscle regulatory factor‐4 (MRF4, p < 0.05), myogenic differentiation factor (MyoD) and insulin‐like growth factor‐1 (IGF‐1, p < 0.01). In conclusion, dietary HMB supplementation to sows at 4 g/day from day 35 of gestation to term significantly improves pregnancy outcomes and increases the expression of myogenic genes in skeletal muscle of neonatal piglets, but reduces feed intake of sows during lactation.     

Effects of intermittent suckling on the performance and digestive efficiency of Iberian piglets weaned at 35 days of age

During two consecutive replicates Iberian sows (n = 20) were subjected either to a conventional lactation (C) or intermittent suckling (IS). Piglets in the C treatment had free access to the dam. Piglets on IS treatment were separated from the sow during 6 h on days 29 and 30, 8 h on days 31 and 32, and 10 h on days 33 and 34. Litters on both treatments were weaned at 35 days of age and offered a starter diet until day 60 of age. The apparent digestibility (ApD) of nutrients and gross energy (GE) of the post-weaning diet was measured using Cr₂O₃ as external indigestible marker. Litters on IS tended to increase solid feed intake during the milk restriction (125 ± 12 vs. 70 ± 19 g piglet^− 1 day^− 1; P = 0.08). Feed intake was improved by IS during the second week post-weaning (676 ± 17 vs. 497 ± 12 g piglet^− 1 day^− 1, P < 0.01), but differences were totally offset after the 7th week of age. Differences in average growth rate of litters on C and IS treatments did not attain statistical significance during the period of restriction and in the first week post-weaning. Litters on IS showed increased growth rate during the second week post-weaning (422 ± 31 vs. 289 ± 33 g piglet^− 1 day^− 1; P = 0.01), but slower daily gains from the 3rd week post-weaning to 60 day of age than litters on C treatment (371 ± 14 vs. 432 ± 15 g piglet^− 1 day^− 1; P < 0.05). Nevertheless, neither at weaning nor at 60 days of age average body weight of piglets differed between treatments (7.71 ± 0.31 vs. 7.94 ± 0.30 kg for C and IS, at 35 days of age, 15.62 ± 0.65 vs. 16.20 ± 0.62 kg, at day 60). The apparent digestibility of nutrients of the starter diet offered after weaning remained unaffected by the treatment, except for a trend for higher ApD of GE for the piglets on IS treatment (P = 0.08). ApD for CP and GE was 78.1 ± 0.6 and 78.8 ± 0.3%, respectively. No significant differences in the proportions of total viscera and gastrointestinal tract to empty body weight (EBW) were observed between C and IS piglets at weaning and 60 d of age. In conclusion, the increase in feed intake observed prior and early after weaning as a consequence of intermittent suckling during the last week of 35 d lactation had no effect on nutrient digestibility measured at two weeks after weaning and failed on improving Iberian piglet performance.     

Dose-response effect of fish oil substitution in parturition feed on erythrocyte membrane characteristics and sow performance

The present study aimed to investigate whether n-3 polyunsaturated fatty acids (PUFA) incorporate into erythrocyte membranes of peripartal sows in a dose-responsive manner and whether the altered fatty acid profile affects the cell membrane characteristics. At day 109 of gestation (day 0), 51 sows were divided into five treatment groups. Each group received a diet with a different ratio of fish oil to pork lard for nine consecutive days. Blood samples were taken at day 0 and 10 days later. The fatty acid profile of erythrocytes was determined, as well as the osmotic fragility and oxidative stability of erythrocytes. Thiobarbituric acid reactive substances (TBARS) and ferric reducing ability of plasma (FRAP) were determined in plasma samples. Finally, reproductive and performance parameters of both sows and piglets were recorded until weaning. Supplementation of fish oil during the peripartal period changed the fatty acid profile of erythrocyte membranes in a dose-responsive manner. Although the n-3 PUFA content of erythrocyte membranes increased with increasing amounts of fish oil in the diet, no significant effect on erythrocyte osmotic fragility could be recorded. In contrast, oxidative stability of erythrocytes decreased linearly with increasing amounts of fish oil in the diet. Similarly, both TBARS and FRAP linearly increased with increasing percentages of fish oil in the diet. Neither piglet nor sow performance was influenced by dietary treatments, except for a decrease of both piglet survival and weaning weight with increasing quantities of fish oil supplemented. It is concluded that changes in dietary lipid sources can affect the membrane's fatty acid profile within days, and mainly influences oxidative stability of the cells.     

Gut ecology, feed digestion and performance in weaned piglets fed liquid diets

Gut environment and microflora, digestibility, and performance were studied in weaned piglets in Central Vietnam fed a dry control diet (CO), a naturally fermented liquid diet (FE), and a liquid diet with inclusion of rice distiller's residue (RDR). Digesta samples were collected at the start (day 0) and at the end of experiment (day 42). Diet FE had a lower pH than diet RDR, contained more organic acids, had the lowest counts of E. coli and total coliforms (P < 0.05), and the highest counts of lactic acid bacteria (LAB) (P < 0.05). Piglets fed diets FE and RDR had lower pH (P < 0.05), and higher concentrations of organic acids in the stomach, ileum and mid-colon (P < 0.05) than piglets fed diet CO. Counts of LAB in stomach and ileum were higher in animals fed diets FE and RDR than CO (P < 0.05), while the number of E. coli and total coliforms along the gastrointestinal tract was reduced. The ileal digestibility of crude protein and organic matter was improved in piglets fed diet RDR (P < 0.05) compared with piglets fed diet CO. Piglets fed diet RDR had a higher weight gain (P < 0.05) and a better feed utilization (P < 0.05) than piglets fed the other diets. The present findings support the contention that fermented diets and/or fermented feedstuffs can be used for dietary manipulation to improve gut health and animal performance.     

Live yeast supplementation during late gestation and lactation affects reproductive performance,colostrum and milk composition,blood biochemical and immunological parameters of sows

This study was conducted to evaluate the effects of dietary live yeast (LY) supplementation during late gestation and lactation on reproductive performance, colostrum and milk composition, blood biochemical and immunological parameters of sows. A total of 40 multiparous sows were randomly fed either the control (CON) diet or the CON diet supplemented with LY at 1 g/kg from d 90 of gestation to weaning. Results showed that the number of stillborn piglets and low BW piglets were significantly decreased in the LY-supplemented sows compared with sows in the CON group (P < 0.05). Moreover, the concentrations of protein, lactose and solids-not-fat were increased in the colostrum of LY-supplemented sows (P < 0.05). Interestingly, the plasma activities of aspartate aminotransferase (AST), alkaline phosphatase (ALP), gamma-glutamyl transpeptidase (γ-GGT) at d 1 of lactation and alanine aminotransferase (ALT) at weaning day were decreased by feeding LY diet (P < 0.05). Meanwhile, sows fed LY diet had higher plasma concentration of immunoglobulin G compared with sows fed CON diet at d 1 of lactation (P < 0.05). In conclusion, LY supplementation in maternal diets decreased the number of stillborn piglets and low BW piglets, improved colostrum quality and health status of sows.     

Effect of controlled alterations in maternal dietary retinol on foetal and neonatal retinol status and pregnancy outcome in pigs

The objective of this experiment was to examine the effects of feeding a vitamin A deficient diet (VAF) to pigs at different times on day 100 of foetal and days 0, 1 and 2 of neonatal development. Three treatments included a control (n = 12), VAF for 100 days before mating and during the first month of pregnancy (n = 13; VAF–control), and VAF during the oestrous cycle before mating and throughout pregnancy (n = 13; control–VAF). On day 100 of pregnancy, maternal liver and plasma retinol concentrations were reduced in both groups of gilts fed a vitamin A free diet compared to controls (P < 0.001 and P < 0.01, respectively). Day 100 foetal liver retinol concentrations were not affected by dietary treatment, whereas foetal plasma concentrations were higher in foetuses carried by gilts fed the VAF–control diet (P < 0.05). Piglets born to mothers fed the control–VAF, but not the VAF–control diet had consistently lower hepatic and plasma liver retinol concentrations (P < 0.05). Moderate reductions in maternal vitamin A at either stage of pregnancy did not affect pregnancy rate, litter size, progesterone secretion or the allometric relationships between foetal or neonatal organ and total body size. Reduced vitamin A during conception and early pregnancy, but not during later pregnancy, was associated with increased within-litter uniformity in birth weight (P < 0.05) and a tendency for fewer low birth weight piglets, but this needs to be confirmed in a greater number of sows. The mechanism underlying this effect is not known, but appears to not involve an alteration in progesterone production.     

Indicators of piglet survival in an outdoor farrowing system

Pre-weaning piglet mortality continues to be a major welfare and economic concern. In outdoor farrowing systems, there is a particular need to broaden breeding goals by incorporating selection for piglet survival to improve both productivity and welfare. This study aimed to identify behavioural and physiological survival indicators that are influential in outdoor systems and that could provide additional information for use when selecting for piglet survival. Data were collected from 511 piglets from Large White × Landrace × Duroc sows and Generalised Linear Mixed Models determined which indicators were most important for piglet survival in an outdoor system. With respect to prenatal mortality (surviving vs. stillborn piglets) high ponderal index (P < 0.001) or body mass index (P < 0.001) in conjunction with being born earlier in the farrowing birth order (P < 0.001) were the most important survival indicators. Birth weight (P < 0.001) and rectal temperature 1 h after birth (P = 0.032) were the most significant postnatal survival indicators. However survival indicators identified as important in indoor, conventional farrowing crates, such as landmark behaviours (latency to reach the udder, a teat and to suckle colostrum), were not influential in this system. These results highlight the importance of studying potential indicators of survival in alternative farrowing systems to the farrowing crate.     

Effect of dietary fish oil on the expression of genes involved in lipid metabolism in liver and skeletal muscle of lactating sows

This study investigated the hypothesis that dietary supplementation of fish oil as a source of n‐3 polyunsaturated fatty acids (PUFA) influences the expression of target genes of sterol regulatory element‐binding proteins (SREBP)‐1 and (SREBP)‐2 involved in triacylglycerol (TAG) synthesis and fatty acid and cholesterol metabolism in the liver, and moreover activates the expression of target genes of peroxisome proliferation‐activated receptor (PPAR)‐α involved in TAG and fatty acid catabolism in liver and skeletal muscle. Twenty lactating sows were fed a control diet or a fish oil diet with either 50 g of a mixture of palm oil and soya bean oil (4:1, w/w) or fish oil per kg. The diet of the fish oil group contained 19.1 g of n‐3 PUFA (mainly 20:5 n‐3 and 22:6 n‐3) per 100 g of total fatty acids, while the diet of the control group contained 2.4 g of n‐3 PUFA (mainly 18:3 n‐3) per 100 g of total fatty acids. The fish oil group had reduced relative mRNA concentrations of various target genes of SREBP‐1 involved in fatty acid and TAG synthesis in comparison with the control group (p < 0.05). Relative mRNA concentrations of target genes of PPARα involved in fatty acid catabolism in both liver and muscle, and mRNA concentrations of target genes of SREBP‐2 involved in cholesterol synthesis and uptake were not influenced by fish oil supplementation. Concentrations of cholesterol and TAG in plasma, fat content of milk and weight gains of litters during the suckling period were not different between the two groups of sows. In conclusion, this study suggests that fish oil has only minor effects on hepatic lipid metabolism, which are non‐critical with respect to milk production in sows.     

Effects of L‐citrulline supplementation on heat stress physiology,lactation performance and subsequent reproductive performance of sows in summer

Lactating sows are susceptible to heat stress (HS). Part of the thermoregulatory response to HS is to increase peripheral blood flow, which is mediated in part by the vasodilator, nitric oxide (NO). Therefore, the aim of this experiment was to determine the effect of supplementation of L‐citrulline, a NO precursor, on symptoms of HS, lactation performance and subsequent reproductive performance of sows in summer. A total of 221 summer farrowing mixed parity sows were fed either a control diet or supplemented with 1% L‐citrulline upon entry to the farrowing house (6 ± 1.8 days for mean ± standard deviation [SD] before farrowing) until weaning (26 ± 1.5 days). The average daily minimum and maximum temperature in the farrowing house was 21.0 ± 1.88 and 29.2 ± 3.82°C (mean ± SD). Rectal temperature, respiration rate, and plasma and urinary nitrite and nitrate (NOx) of sows were measured on the 19th day post‐farrowing. Supplemental L‐citrulline in the diet did not affect the number of piglets born alive, feed intake of sows, body weight or backfat thickness of sows at weaning, or litter weight gain. L‐citrulline tended to reduce piglet pre‐weaning mortality rate from 18.6% to 15.6% (p = 0.058). L‐citrulline reduced the respiration rate of sows compared to the control diet at 17:00 hr (Time × Diet, p < 0.001); however, rectal temperature was not affected. L‐citrulline tended to increase urinary NOx concentrations (127 vs. 224 µM, p = 0.057) but not plasma NOx concentrations. L‐citrulline did not affect farrowing rate or number of piglets born alive in the subsequent parity. In conclusion, L‐citrulline supplementation reduced respiration rate of lactating sows and reduced piglet pre‐weaning mortality rate in summer. Whether the effects were due to a NO‐dependent mechanism requires further validation.     

Effects of dietary ratio of n-6 to n-3 polyunsaturated fatty acids on immunoglobulins,cytokines, fatty acid composition,and performance of lactating sows and suckling piglets

This experiment was conducted to investigate the effects of dietary ratios of n-6:n-3 polyunsaturated fatty acids (PUFA) on the performance of lactating sows and their piglets. Thirty pregnant Landrace sows were assigned to one of three treatments from d 108 of gestation until weaning (26–29 d) and were fed diets containing different ratios of n-6:n-3 PUFA including 3:1, 9:1 and 13:1. The effects on sow and litter production traits were examined together with an assessment of sow body condition. No differences were detected among the treatments for the daily feed intake of sows or changes in sow weight and back-fat levels during lactation (P > 0.05). Litter size at d 14 and d 21 were tended to increase in 3:1 treatment compared with 9:1 and 13:1 treatments (P < 0.10). Litter weight gain (1.77 kg/d) from d 0 to d 14 was tended to increase in 9:1 groups compared with the other two treatments (P < 0.10). A significant difference was observed for the content of α -linolenic acid, total n-3 PUFA, and the ratio of n-6:n-3 PUFA in the colostrum, milk, and piglets plasma (P < 0.01). The effects of different ratios of n-6:n-3 PUFA in sow diets on colostrum, milk, and piglet plasma immunoglobulin concentrations are studied. No difference was observed among treatments in the concentrations of IgM, and IgA in colostrum (P > 0.05). A great significant difference for IgG concentration was observed among 3 group in colostrum. A great significant difference for IgA, and IgM (P < 0.01) concentrations in piglet plasma at d14 and a significant difference for IgG(P < 0.05) was observed at d14. Furthermore, at d 21 of lactation, piglet plasma IgG and IgA concentration were greater in 3:1 compared with 13:1 group (P < 0.01).In summary, the current study demonstrated that altering the ratio of n-6:n-3 PUFA in lactating sow diet had an effect on the immune component including immunoglobulin and cytokines, and it tended to increase the litter average daily gain and improve the immune status of piglets when dietary ratio of n-6:n-3 PUFA was 9:1.     

Local and systemic cytokine responses during larval penetration in cattle experimentally infested with Hypoderma lineatum (Diptera: Oestridae)

Local and systemic cytokine responses were studied in 3 groups of cattle, with 4 animals each, experimentally infested with Hypoderma lineatum (De Villers) first instars (L1). The first group was undergoing a primary infestation (G-1), the second group was undergoing a secondary infestation (G-2) and the third group was infested for their third consecutive year (G-3). Cattle were infested with 25 L1 deposited on the skin. Blood and skin samples were taken at 0, 6, 12, 48, 96 and 144 h post-infestation (h.p.i.). Interleukin 10 (IL-10), IL-4 and interferon gamma (IFN-γ) production was studied by immunohistochemistry and sandwich ELISAs. IL-4⁺ cells showed a significant increase at 6 h.p.i. in both reinfested groups (G-2 and G-3) when compared with G-1. In all groups the number of IL-4⁺ cells decreased significantly at 48 h.p.i. IL-10⁺ cells increased in G-1 at 6 and 48 h.p.i., whereas in both reinfested groups increased at 12 h.p.i. with a peak at 48 h.p.i. IFN-γ⁺ cells showed a significant increment at 6 h.p.i. in all groups, followed by a rapid descent at 12 (G-1 and G-2) and 48 h.p.i. (G-3). Penetration of the skin by H. lineatum did not have any significant effect on IFN-γ serum concentrations and, except for IL-10 there were no correlation between local production and serum concentrations of cytokines. The increase of both Th1 (IFN-γ) and Th2-type cytokines (IL-4 and IL-10) indicates that bovine T-cell response during the first phases of the infestation by H. lineatum is apparently a Th0 response.     

Leptin in sow: Influence on the resumption of cycle activity after weaning and on the piglet gain

In sows, a strong relationship exists between body condition and reproductive efficiency and milk yield. Leptin may act as a metabolic gate which permits the activation of reproductive axis: in the sow, serum concentration of leptin was positively correlated with adiposity at farrowing. An interesting aspect useful to clarify the biology of leptin, was the discovery that the placenta expresses the ob gene, the ob receptor gene and it is a site of leptin production, suggesting a possible role of the hormone in fetal growth; after birth, the placenta functions were taken over from milk, especially to the delivery of maternal hormones and growth factors to the neonate. The exact role of maternal leptin in the physiology of neonatal piglets remains to be determined. Our aim was to evaluate if maternal leptin levels at the beginning of lactation and at weaning could predict the resumption of cycle activity and/or the piglet gain. Thirty-eight Large White × Landrace pregnant sows (16 nulliparous and 22 pluriparous) were used. Blood samples were taken from sows and piglets at d 5 and d 21 after farrowing; in the same days, milk samples were taken after oxytocin injection by means of complete manual milking of all mammary glands of one side. On the basis of the blood leptin at d 5, sows were divided into 3 groups (Low: < 2.3 ng/ml; Medium: 2.3 to 2.6 ng/ml; High: > 2.6 ng/ml). Our results show a correlation at d 5 between backfat thickness and blood leptin (r = 0.342; P < 0.05). The resumption of the cyclic activity was faster in sows with a leptin level at d 5 greater than 2.3 ng/ml (P < 0.01). Milk composition at d 5 and 21 was not affected by parity and leptin. Piglet ADG was significantly (P < 0.05) influenced by sow leptin groups (0.180 kg day^− 1 for piglets from Low group and 0.224 for High group). Piglets weaned by High group sows have shown a greater blood leptin content at weaning (P < 0.01) than other groups. In conclusion we have found a significant correlation between leptin and productive and reproductive performances of pigs. This paper underlines the pleiotropic actions exerted by leptin in the productive sow.     

In vitro effect of vitamin E on lectin-stimulated porcine peripheral blood mononuclear cells

In order to analyze the effect of vitamin E on Th1 and Th2 cytokine production, porcine peripheral blood mononuclear cells (PBMC) were isolated from healthy pigs (n = 8) and cultured with either 0, 10, 50, or 100 μM of vitamin E (α-tocopherol). PBMC were stimulated with PHA for either, 24 h to determine: (a) the concentration of tocopherol incorporated into the cell membrane, (b) cytokine production and (c) Th1 and Th2 regulators gene expression; or 72 h to determine the proliferation of PBMC. Vitamin E was incorporated into the PBMC in a dose dependent manner, giving as a result a high proliferation of cells irrespective of the dose of vitamin E used. Regarding cytokine production, vitamin E consistently decreases the mRNA expression and the percentage of cells producing IL-10. Vitamin E did not influence the production of IFN-γ but the lowest level of vitamin E (10 μM) was sufficient to maximally increase the proportion of cells producing IL-2, to diminish IL-4, and discreetly increase the mRNA expression of TBX21 vs. GATA3. In conclusion, our results revealed that vitamin E is able to suppress IL-10 production and to influence the production of IL-2, IL-4, and maybe TBX21. Vitamin E clearly has immunomodulatory effects, though further work in vivo to determine the physiological nature of these effects is warranted.