Characteristics of sows' milk and piglet nutrient utilization during a 28-d lactation period.

The present study aimed to characterize the performance of suckling piglets from high prolific sows and investigate the impact of milk composition on piglet growth during a 4-wk lactation period. Piglet performance included weight gain (WG), milk intake, nutrients and energy in milk, and piglet energy metabolism in weeks 1 to 4 of lactation. Data from six previous experiments were used with a total of 2,047 piglets and 604 milk samples collected from 151 sows. Piglet body weight linearly increased (P < 0.001) as lactation progressed, with the piglet WG being low in week 1 (132 g/d) and relatively constant from weeks 2 to 4 (248 g/d; P < 0.001). The metabolizable energy (ME) intake of the piglets increased (P < 0.001) from weeks 1 to 3; however, with lower values in week 4 than for week 3. The heat energy production and energy required for maintenance (MEm) linearly increased (P < 0.001) from weeks 1 to 4. In addition, the retained energy and ME to MEm ratio only increased from weeks 1 to 2 (P < 0.001) and then declined through week 4. Pearson correlation coefficients were used to examine the relations between the milk nutrient composition and the WG in weeks 1 to 4. The results showed that WG was negatively correlated with the milk protein concentration at all stages of lactation (P < 0.001). In contrast, the WG was positively correlated with milk fat and lactose concentrations in weeks 2 and 4, respectively (P < 0.001). In conclusion, the stage of lactation influenced WG, milk intake, nutrients in milk, energy in milk, and the energy metabolism of the suckling piglets. Moreover, maximizing milk protein concentration does not optimize piglet growth.

The manuscript reviews the results of six experiments with high-performing lactating sows. Different variables in sow's milk, which influence the performance of suckling piglets during lactation, have been examined.

Impact of dietary fat levels and fatty acid composition on milk fat synthesis in sows at peak lactation.

BACKGROUND: Dietary fat is important for energy provision and immune function of lactating sows and their progeny. However, knowledge on the impact of fat on mammary transcription of lipogenic genes, de novo fat synthesis, and milk fatty acid (FA) output is sparse in sows. This study aimed to evaluate impacts of dietary fat levels and FA composition on these traits in sows. Forty second-parity sows (Danish Landrace × Yorkshire) were assigned to 1 of 5 dietary treatments from d 108 of gestation until weaning (d 28 of lactation): low-fat control diet (3% added animal fat); or 1 of 4 high-fat diets with 8% added fat: coconut oil (CO), fish oil (FO), sunflower oil (SO), or 4% octanoic acid plus 4% FO (OFO). Three approaches were taken to estimate de novo milk fat synthesis from glucose and body fat. RESULTS: Daily intake of FA was lowest in low-fat sows within fat levels (P < 0.01) and in OFO and FO sows within high-fat diets (P < 0.01). Daily milk outputs of fat, FA, energy, and FA-derived carbon reflected to a large extent the intake of those. On average, estimates for de novo fat synthesis were 82 or 194 g/d from glucose according to method 1 or 2 and 255 g de novo + mobilized FA/d according to method 3. The low-fat diet increased mammary FAS expression (P < 0.05) and de novo fat synthesis (method 1; P = 0.13) within fat levels. The OFO diet increased de novo fat synthesis (method 1; P < 0.05) and numerically upregulated mammary FAS expression compared to the other high-fat diets. Across diets, a daily intake of 440 g digestible FA minimized milk fat originating from glucose and mobilized body fat. CONCLUSIONS: Sows fed diets with low-fat or octanoic acid, through upregulating FAS expression, increased mammary de novo fat synthesis whereas the milk FA output remained low in sows fed the low-fat diet or high-fat OFO or FO diets, indicating that dietary FA intake, dietary fat level, and body fat mobilization in concert determine de novo fat synthesis, amount and profiles of FA in milk.

Dynamics of fatty acid and non-volatile polar metabolite profiles in colostrum and milk depending on the lactation stage and parity number of sows.

The objective of this study was to investigate the impact of lactation stage and parity number on fatty acid and non-volatile polar metabolite profiles in sow colostrum and milk using a metabolomics approach. A total number of 63 colostrum, transient and mature milk were collected from primiparous and multiparous Landrace × Yorkshire crossbred sows. Macrochemical, fatty acid and non-volatile polar metabolite compositions of samples were analyzed using infrared spectrometry, gas chromatography coupled with mass-spectrometry and proton nuclear magnetic resonance spectroscopy, respectively. Univariate and multivariate statistical analysis demonstrated significant impacts of lactation stage and parity number on colostrum and milk compositions. Chemometric analysis revealed significant influences of sow parity on the distinction in fatty acid profiles of mature milk while the distinction in non-volatile polar metabolite profiles was more evident in colostrum. Alterations in the concentration of linoleic (C18:2n6), lignoceric (C24:0), behenic (C22:0), caprylic (C8:0) and myristoleic (C14:1) acid together with those of creatine, creatinine phosphate, glutamate and glycolate were statistically suggested to be mainly affected by sow parity number. Variations in the concentration of these compounds reflected the physiological function of sow mammary gland influenced. This information could be applied for feed and feeding strategies in lactating sows and improving lactating performances.

Review: Physiology and nutrition of late gestating and transition sows.

The physiology during late gestation and the transition period to lactation changes dramatically in the sow, especially during the latter period. Understanding the physiological processes and how they change dynamically as the sow approaches farrowing, nest building, giving birth to piglets, and producing colostrum is important because these processes greatly affect sow productivity. Glucose originating from assimilated starch accounts for the majority of dietary energy, and around farrowing, various organs and peripheral tissues compete for plasma glucose, which may become depleted. Indeed, physical activity increases shortly prior to farrowing, leading to glucose use by muscles. Approximately ½ to 1 d later, glucose is also needed for uterine contractions to expel the piglets and for the mammary gland to produce lactose and fat for colostrum. At farrowing, the sow appears to prioritize glucose to the mammary gland above the uterus, whereby insufficient dietary energy may compromise the farrowing process. At this time, energy metabolism in the uterus shifts dramatically from relying mainly on the oxidation of glucogenic energy substrates (primarily glucose) to ketogenic energy supplied from triglycerides. The rapid growth of mammary tissue occurs in the last third of gestation, and it accelerates as the sow approaches farrowing. In the last 1 to 2 wk prepartum, some fat may be produced in the mammary glands and stored to be secreted in either colostrum or transient milk. During the first 6 h after the onset of farrowing, the uptake of glucose and lactate by the mammary glands roughly doubles. Lactate is supplying approximately 15% of the glucogenic carbon taken up by the mammary glands and originates from the strong uterine contractions. Thereafter, the mammary uptake of glucose and lactate declines, which suggests that the amount of colostrum secreted starts to decrease at that time. Optimal nutrition of sows during late gestation and the transition period should focus on mammary development, farrowing performance, and colostrum production. The birth weight of piglets seems to be only slightly responsive to maternal nutrition in gilts; on the other hand, sows will counterbalance insufficient feed or nutrient intake by increasing mobilization of their body reserves. Ensuring sufficient energy to sows around farrowing is crucial and may be achieved via adequate feed supply, at least three daily meals, high dietary fiber content, and extra supplementation of energy.

The transition period is a short period of the reproductive cycle spanning from 7­10 d prepartum to 3­5 d postpartum in sows. Nonetheless, it is highly important for the productivity of sows because it is when the majority of piglet deaths occur. Most piglets die either during the birth process or within the first days postpartum, and mammary development, fetal growth, farrowing process, and colostrum production have profound impacts on piglet survival and growth. Nutrition during this critical period can greatly affect these physiological processes, and the most effective feeding strategy needs to be elaborated. Around farrowing, the sow may suffer from inadequate energy from assimilated starch, and liver glycogen seems not to be able to supply sufficient glucose to meet the demand for nest building, uterine contractions, and colostrum production. The sow seems to prioritize glucose for the mammary gland above the uterus but may suffer from depletion due to nest building. The insufficient energy status of the sow compromises the farrowing process and prolongs the duration, thereby increasing the need for farrowing assistance and stillbirths. Nutritional strategies to alleviate these challenges include adequate feed supply, number of daily meals, dietary fiber content, and extra supplementation of energy to sows around farrowing.

The Impact of Enhancing Diet Quality or Dietary Supplementation of Flavor and Multi-Enzymes on Primiparous Lactating Sows.

This study was aimed to explore how a high-quality diet or a flavor plus multi-enzyme diet affects the feed intake, nutrient digestibility and antioxidation capacity of lactating sows and the growth of their progeny. Thirty primiparous sows were randomly assigned to three treatments from d 2 of lactation until weaning (d 21): control (CON), with a basal diet; high quality (HQ), with 200 kcal/kg higher net energy than CON; or the CON diet supplemented with 500 mg/kg flavor and 100 mg/kg multi-enzymes (F + E). Sows fed with the HQ or F + E diets improved piglets' live weight (p < 0.05) and average daily weight gain (p < 0.10), litter weight gain (p < 0.10) and piglet growth to milk yield ratio (p < 0.10). Compared with CON, the HQ and F + E groups increased the digestibility of ether extract, ash, neutral detergent fiber, crude fiber and phosphorus (p < 0.10), and the HQ group also increased dry matter, gross energy, crude protein, acid detergent fiber and energy intake (p < 0.05). Compared with CON, the F + E group decreased serum urea nitrogen and aspartate aminotransferase (p < 0.05) and enhanced superoxide dismutase, catalase and glutathione peroxidase, but it decreased malondialdehyde in milk supernatant (p < 0.05).

The improvement of parturition duration by high intake of dietary fibre in late gestation is associated with gut microbiota and metabolome in sows.

Prolonged parturition duration has been widely demonstrated to be a risk factor for incidence of stillbirth. This study evaluated the supply of dietary fibre on the parturition duration, gut microbiota and metabolome using sows as a model. A total of 40 Yorkshire sows were randomly given diet containing normal level of dietary fibre (NDF, 17·5 % dietary fibre) or high level of dietary fibre (HDF, 33·5 % dietary fibre). Faecal microbiota profiled with 16S rRNA amplicon sequencing, SCFA and metabolome in the faeces and plasma around parturition were compared between the dietary groups. Correlation analysis was conducted to further explore the potential associations between specific bacterial taxa and metabolites. Results showed that HDF diet significantly improved the parturition process as presented by the shorter parturition duration. HDF diet increased the abundance of the phyla Bacteroidetes and Synergistetes and multiple genera. Except for butyrate, SCFA levels in the faeces and plasma of sows at parturition were elevated in HDF group. The abundances of fifteen and twelve metabolites in the faeces and plasma, respectively, markedly differ between HDF and NDF sows. These metabolites are involved in energy metabolism and bacterial metabolism. Correlation analysis also showed associations between specific bacteria taxa and metabolites. Collectively, our study indicates that the improvement of parturition duration by high fibre intake in late gestation is associated with gut microbiota, production of SCFA and other metabolites, potentially serving for energy metabolism.

Effects of dairy and plant protein on growth and growth biomarkers in a piglet model.

The increasing world population with improved living conditions has increased the demand for food protein. This has intensified the search for sustainable alternative plant-derived high-quality protein sources for human nutrition. To study the effect of plant and milk proteins on growth in weaned pigs as a model for humans, 96 weaned pigs were divided into 48 pens and fed one of 4 different diets for 3 weeks. The dietary protein originated from either 50% rice + 50% 00-rapeseed protein (RICE + RAPE), 50% milk protein (MPC) + 50% 00-rapeseed protein (MPC + RAPE), 50% milk + 50% rice protein (MPC + RICE), or 100% MPC, and were supplemented with crystalline amino acids to meet the amino acid requirements. Weekly feed intake and body weights were recorded and after 3 weeks, a blood sample was taken 1 hour after a fixed meal, while organ weights were measured, and liver- and muscle tissue, and bone samples were collected at euthanasia. All pigs had a high daily gain and a low feed-to-gain ratio (F : G, feed intake per kg weight gain), but feed intake and daily gain was lowest and F : G highest in the RICE + RAPE diet. Metacarpal bones were longer and heavier in MPC + RICE and MPC fed pigs compared to pigs fed diet RICE + RAPE (P < 0.05), and intermediate in MPC + RAPE fed pigs, with no differences in bone thickness (P > 0.05). Plasma levels of all essential amino acids except Cys and Lys decreased markedly when fed a diet containing only plant protein. The differences were not associated with differences in plasma insulin or IGF-1, nor in the abundance of mRNA related to growth in liver and longissimus dorsi muscle. In conclusion, the growth of piglets fed a combination of milk and rice protein did not differ from the pure dairy-based diet, whereas the pure plant-based diet consisting of rice and rapeseed protein led to reduced growth. This was most likely caused by a lower feed intake and a lower than expected amino acid digestibility of the 00-rapeseed protein. There were no indications that the milk protein, beyond a favourable amino acid composition and high digestibility, specifically stimulated growth factors or other biomarkers of growth via the IGF-1 and insulin signalling pathways.

The differences in energy metabolism and redox status between sows with short and long farrowing duration.

Farrowing duration is a crucial factor affecting survival of piglets and health of sows, and is highly correlated with the incidence of stillbirth. The present study assessed the metabolic characteristics of sows with short farrowing duration (SFD) or long farrowing duration (LFD). A total of 20 Yorkshire sows were screened from 60 sows and were retrospectively allocated into SFD (211 min on average, n = 10) or LFD (388 min on average, n = 10) group. Parameters associated with energy metabolism and redox status were characterised. Results showed that sows at farrowing had decreased plasma concentrations of glucose, triglyceride, acetate, butyrate and total short-chain fatty acids (P < 0.05), but increased concentrations of lactic acid and propionate (P < 0.05), when compared with sows on day 107 of gestation. The SFD sows had shorter time from last meal until the onset of farrowing (P < 0.05) and tended to have less stillbirths (P = 0.08) and lower stillbirth rate (P = 0.07). For the blood metabolites, SFD sows at farrowing had higher concentration of plasma glucose (P < 0.05), but lower concentration of lactic acid (P < 0.05) than LFD sows. Besides, SFD sows tended to have higher plasma malondialdehyde concentration (P = 0.06) than LFD sows. Correlation analysis showed that farrowing duration was negatively correlated with plasma glucose concentration at onset of farrowing. In conclusion, our study strongly suggests that glucose is a key metabolite for energy metabolism of the uterus during farrowing. The farrowing process could be closely related to uterine energy expenditure, and sows with shorter farrowing duration could be resulting from the shorter time from last meal until the onset of farrowing, associated with a greater proportion of energy from glucose.

Effects of dietary soluble or insoluble fiber intake in late gestation on litter performance, milk composition, immune function, and redox status of sows around parturition.

The objective of this study was to investigate the effects of dietary soluble fiber (SF) or insoluble fiber (ISF) intake in late gestation on litter performance, milk composition, immune function, and redox status of sows around parturition. A total of 60 Yorkshire sows were randomly assigned into three dietary treatments: normal level of dietary fiber (CON, 16.16% dietary fiber with 1.78% soluble fiber and 14.38% insoluble fiber), high insoluble fiber (ISF, 30.12% dietary fiber with 2.97% soluble fiber and 27.15% insoluble fiber), and high soluble fiber (SF, 30.15% dietary fiber with 4.57% soluble fiber and 25.58% insoluble fiber). Digestible energy and crude protein intake were comparable among treatments via adjusting feed intake from day 90 of gestation to parturition. After parturition, all sows were fed the same lactation diet. Results showed that litter performance of sows was not markedly affected by maternal fiber intake. However, sows fed ISF or SF diet had increased concentration of plasma mmunoglobulin G at day 107 (P < 0.05) and parturition (P < 0.01), and the SF diet had a tendency to increase fat content in both colostrum and milk relative to the CON diet. Furthermore, sows fed ISF diet had increased glutathione peroxidase activity (P < 0.05) at day 107, but decreased the plasma level of malondialdehyde at parturition (P < 0.05). High maternal SF intake tended to decrease the number of weaned piglets due to the increased preweaning mortality, as compared with sows fed the ISF diet. In conclusion, high fiber intake in late gestation may improve immune function and redox status, but differentially influenced the milk composition and preweaning mortality.

Dietary fibre and protein do not synergistically influence insulin, metabolic or inflammatory biomarkers in young obese Göttingen minipigs.

The effects of dietary fibre (DF) and protein on insulin response, lipidaemia and inflammatory biomarkers were studied in a model experiment with juvenile obese Göttingen minipigs. After 20 weeks feeding on a high-fat fructose-rich low-DF diet, forty-three 30-week-old minipigs (31·3 (sem 4·0) kg body weight) were allocated to low- or high-DF and -protein diets for 8 weeks in a 2 × 2 factorial design. High DF contents decreased (P = 0·006) while high protein increased (P < 0·001) the daily gain. High protein contents increased fasting plasma concentrations of glucose (P = 0·008), NEFA (P = 0·015), ghrelin (P = 0·008) and non-fasting LDL:HDL ratios (P = 0·015). High DF increased ghrelin (P = 0·036) and C-peptide levels (P = 0·011) in the non-fasting state. High protein increased the gene expression of fructose-bisphosphatase 1 in liver tissue (P = 0·043), whereas DF decreased fatty acid synthase expression in adipose tissue (P = 0·035). Interactions between DF and protein level were observed in the expression of leptin receptor in adipose tissue (P = 0·031) and of PPARγ in muscle (P = 0·018) and adipose tissue (P = 0·004). In conclusion, high DF intake reduced weight gain and had potential benefit on ß-cell secretory function, but without effect on the lipid profile in this young obese model. High dietary protein by supplementing with whey protein did not improve insulin sensitivity or lipidaemia, and combining high DF with high protein did not alleviate the risk of metabolic abnormalities.

Feeding sows during the transition period-is a gestation diet, a simple transition diet, or a lactation diet the best choice?

Three experiments were carried out to study whether a gestation diet, a simple transition diet, or a lactation diet is the best choice in late gestation and when sows preferably should be transferred to a high crude protein (CP) lactation diet. In experiment 1, 35 sows were fed either a gestation diet (12.1% CP), a lactation diet (15.9% CP), or a 50/50 mix (simple transition diet; 14.0% CP) from 6 d before parturition until parturition, to study the impact on farrowing and colostrum performance. In experiment 2, 90 sows were studied from 6 d before parturition until weaning at day 24 and they were fed one of five strategies: a gestation diet until day 3 or day 10 of lactation (strategy 1 and 2) and then lactation diet; a simple transition diet until day 3 or day 10 (strategy 3 and 4) and then lactation diet; or a lactation diet throughout the study (strategy 5). In experiment 3, 124 sows were fed strategy 1 or 5. Sows were weighed and back fat (BF) scanned when entering the farrowing unit and at day 2, 10, 17, and 24. Piglets were weighed at birth and after 24 h, and colostrum production was studied (experiment 1). Litter weight at day 2, 10, 17, and 24 was recorded, milk and blood samples were collected weekly and sow fat and protein mobilization, and balances of energy, N, and Lys were calculated from day 3 to 10 of lactation (experiment 2). Total- and live born piglets, and frequencies of stillbirth and piglet diarrhea were recorded (experiment 3). Feeding sows a gestation diet, a simple transition diet, or a lactation diet showed no evidence of effects on colostrum production or farrowing process (experiments 1 and 3) or lactation performance (experiments 2 and 3). Compared to previous studies, sows had a poor milk yield. Plasma urea was elevated (P < 0.001) indicating CP oversupply prior to parturition in sows fed the lactation diet as compared with the two other diets. According to calculated balances, all dietary strategies supplied insufficient amounts of N and Lys from day 3 to 10, indicating that the best choice is to feed sows with a high CP lactation diet from parturition and onwards. Primiparous sows had a higher plasma insulin concentration (P < 0.01), lower colostrum yield (P < 0.01), and higher frequency of piglet diarrhea (P < 0.001) than multiparous sows. In conclusion, in our conditions (high CP in gestation diet; poor milk yield; restricted feeding in early lactation), sow performance was not compromised by the dietary strategies, but results indicate that primiparous and multiparous sows should be fed differently.

Net absorption and liver metabolism of amino acids and heat production of portal-drained viscera and liver in multiparous sows during transition and lactation.

BACKGROUND: Determination of nutrient requirements in the late gestating and lactating sows is essential to optimize sow productivity. The objectives of the present study were to quantify amino acid (AA) fluxes and heat production across portal-drained viscera (PDV) and liver in multiparous sows during transition and lactation. METHODS: Eight second parity sows were fitted with indwelling catheters in the femoral artery and in the mesenteric, portal and hepatic veins. Eight hourly sets of blood samples were taken starting 0.5 h before feeding at - 10, - 3, + 3, and + 17 d in milk (DIM). Blood gases, plasma metabolites and apparent total tract digestibility (ATTD) of nutrients were measured. RESULTS: Feed intake, the ATTD of DM, energy, nitrogen, fat and crude fiber changed with DIM (P < 0.001). Except for Glu, O2, and urea, all net portal fluxes were positive, and all were affected by DIM (P < 0.05) and by sampling time (P < 0.01). Compared with pre partum levels, net portal uptake of AA was 3-63% lower at + 3 DIM but 40-100% higher at + 17 DIM. Net portal fluxes of AA peaked at 1.5 to 2.5 h after feeding except for Glu, and they were positively correlated with changes in sow feed intake across DIM. The net portal recovery was low for Met (49%), Thr (54%), and His (54%) and high for the remaining essential AA (63-69%) and none of them differed across DIM. Net hepatic uptake (i.e. hepatic oxidation) of Lys, Thr, Ile, Leu and Phe peaked at 0.5 to 2.5 h after feeding, whereas uptake of Trp, Val, and His was constant, while that of Met was close to zero. CONCLUSION: The net portal recovery was substantially lower for Met, Thr, and His than the remaining essential AA. Hepatic AA oxidation peaks 0.5 to 2.5 h after feeding. The heat production in PDV and liver was approximately two-fold higher at peak lactation compared to other stages. The study suggests that lysine was the limiting AA in peak lactation but not in early lactation.

Net Absorption and Metabolism of ß-Hydroxy- ß-Methyl Butyrate during Late Gestation in a Pig Model.

The leucine metabolite, ß-hydroxy-ß-methyl butyrate (HMB), is widely used in human nutrition and animal production as a nutritional supplement. Although the HMB usage during late gestation has been demonstrated to have a positive effect on fetal development, knowledge on net absorption and metabolism of HMB and impact of HMB on branched chain amino acids (BCAAs) metabolism is lacking. To address this, we conducted a study using pigs during the perinatal period as a model organism. Eight-second parity sows were fitted with indwelling catheters in the femoral artery and in the portal, hepatic, femoral, and mesenteric veins. Eight hourly sets of blood samples were taken starting 30 min before the morning meal on day -10 and day -3 relative to parturition. Four control (CON) sows were fed a standard lactation diet from day -15 and throughout the experiment, and 4 HMB sows were fed the control diet supplemented with 15 mg Ca(HMB)2/kg body weight mixed in one third of the morning meal from day -10 until parturition. Blood gases, plasma metabolites, milk compositions, and apparent total tract digestibility of nutrients were measured. Arterial plasma concentrations of HMB (p < 0.001), Cys (p < 0.001), and Lys (p < 0.10) were increased in HMB supplemented sows, while arterial plasma triglycerides concentration was decreased (p < 0.05). The net portal recovery of Ala and Asp were increased in HMB sows (p < 0.05). Sows fed HMB had increased hepatic vein flow and net hepatic fluxes of Met, Asn, and Gln (p < 0.05). In contrast, the femoral extraction rates of Ala and Ser were decreased by dietary HMB supplementation (p < 0.05). Dietary HMB treatment and sampling time relative to feeding had an interaction on arterial concentrations, net portal fluxes, and femoral extraction rates of BCAAs. The net portal recovery of HMB was 88%, while 14% of supplemented HMB was excreted through urine and 4% through feces. Moreover, the gastrointestinal tract metabolized 8% while the liver metabolized 12%. Finally, 26% of the daily intake of HMB was secreted via colostrum at the day of farrowing. This study demonstrated that dietary HMB supplementation increased net uptake of amino acids and increased fatty acid oxidation through improving blood flow and insulin sensitivity during the late gestation. Most importantly, oral HMB administration could maintain a stable postprandial absorption and altered metabolism in BCAAs. Net portal flux of HMB at 5.5 to 6.5 h after feeding approached zero, indicating that HMB ideally should be administrated two or three times, daily.

Impact of milk and nutrient intake of piglets and sow milk composition on piglet growth and body composition at weaning.

The main objective of this study was to evaluate the impact of milk intake, milk composition, and nutrient intake on piglet growth in lactation and body composition at weaning. To evaluate the body composition of piglets, data from one experiment (44 Danish Landrace × Yorkshire × Duroc piglets) were used to develop prediction equations for body pools of fat, protein, ash, and water based on live weight and deuterium dilution space (exp. 1). Furthermore, a total of 294 piglets (Danish Landrace × Yorkshire × Duroc) from 21 sows of second parity were included in a second experiment (exp. 2). In exp. 2, piglet live weight was recorded on days 3, 10, 17, and 25 of lactation. On the same days, the milk intake and body composition were measured, using the deuterium oxide (D2O) dilution technique. Piglet weight gain was highly positively correlated with the intake of milk and the intake of milk constituents each week and on an overall basis having r values ranging from 0.65 to 0.93 (P < 0.001). When evaluating regressions for piglet growth, the milk intake in combination with the milk protein concentration explained 85% and 87% of the total variation in piglet gain in the second and third week of lactation, respectively, whereas milk intake was the only predictor of piglet gain in the first week of lactation explaining 81% of the variation. Fat, protein, and energy retention rates were all highly positively correlated with the daily intake of milk and intake of milk nutrients with r values ranging from 0.76 to 0.94 (P < 0.001). Piglet gain and retention rates were rather weakly correlated with the milk composition with r values ranging from 0.01 to 0.50 (being either negative or positive). Curvilinear response curves were fitted for live weight gain and body fat content at weaning in response to milk protein concentration, showing that live weight gain was slightly greater and body fat content was slightly lower at 4.9% milk protein, but it should be emphasized that the quadratic effects did not reach significance. Body fat content at weaning was positively related with the intake of milk (R2 = 0.44, P < 0.001) and milk fat (R2 = 0.46, P < 0.01). In conclusion, milk intake had a major impact on the piglet growth rate, and milk fat intake greatly influenced the body fat percentage at weaning, whereas milk composition per se only played a minor role for these traits.

Metabolomic Profiling Reveals the Difference on Reproductive Performance between High and Low Lactational Weight Loss Sows.

Sows suffering excess weight loss during lactation may delay weaning to estrus interval (WEI) and have a detrimental effect on subsequent reproductive performance, however, the underlying mechanism is not completely clear. Therefore, the goal of this study was to investigate physiological profiles manifested in plasma originating from high (HWL) and low lactational weight loss (LWL) sows. The plasma biochemical parameters, hormones, antioxidant parameters, and milk compositions were assessed. Furthermore, plasma metabolites were analyzed using ultrahigh-performance liquid chromatography/time-of-flight mass spectrometry in positive and negative ion modes. Results showed that HWL sows had a lower feed intake and higher lactational weight loss and prolonged WEI, but had similar litter performance and milk composition compared to LWL sows. These changes were associated with lower plasma insulin-like growth factor 1 and higher fibroblast growth factor 21 levels in the HWL sows. Moreover, HWL led to a severe oxidative stress and metabolic damage, as accompanied by excessive protein breakdown and lipids mobilization at weaning. Metabolomic analysis revealed differences in 46 compounds between HWL and LWL sows, and the identified compounds were enriched in metabolic pathways related to amino acids metabolism, fatty acids oxidation metabolism, bile acids biosynthesis, and nucleoside metabolism. These results provide the evidence for physiological mechanism in sows with excessive lactational weight loss that delayed the WEI. Metabolomic data provides essential information and gives rise to potential targets for the development of nutritional intervention strategies.

Effects of increased energy and amino acid intake in late gestation on reproductive performance, milk composition, metabolic, and redox status of sows1.

The objective of this study was to determine the effects of increased AA and energy intake during late gestation on reproductive performance, milk composition, and metabolic and redox status of sows. A total of 118 Yorkshire sows (third through sixth parity) were randomly assigned to dietary treatments from day 90 of gestation until farrowing. Dietary treatments consisted of combinations of 2 standardized ileal digestible (SID) AA levels [14.7 or 20.6 g/d SID Lys, SID Lys and other AA met or exceeded the NRC (2012) recommendations] and 2 energy levels (28.24 or 33.78 MJ/d intake of NE) in a 2 × 2 factorial design. After parturition, all sows were fed a standard lactation diet. Blood samples were collected and analyzed for parameters on metabolism, redox status, and amino acid profile. The data were analyzed using the generalized linear mixed models to reveal the impact of dietary levels of energy, AA, and their interaction. Sows with increased intake of AA had greater BW gain (P < 0.01) during late gestation. Furthermore, the BW loss during lactation was increased in sows with increasing intake of energy (P < 0.05) or AA (P < 0.05). Sows fed high energy had higher total litter birth weights (20.2 kg vs. 18.4 kg, P < 0.05) and shorter duration of farrowing (261 min vs. 215 min, P < 0.05), compared with those fed low energy, which likely was due to higher (P < 0.05) plasma glucose and lower (P < 0.05) plasma lactate prior to parturition. High AA intake in late gestation increased the ADG of piglets during the following lactation (P < 0.05), and increased the concentrations of plasma urea, and the following AA: Lys, Met, Thr, Val, Ile, Leu, Phe, Asp, Ser, and Arg at farrowing (P < 0.05). In conclusion, the increased intake of energy increased total litter weight of newborns and shortened the farrowing duration, which likely was due to improved energy status at farrowing. Furthermore, sows with increased intake of AA led to higher growth rate of piglets during the following lactation, accompanying with the increasing levels of plasma urea and amino acids. Therefore, the higher energy intake in late gestation appeared to improve litter weight and farrowing duration, while higher AA intake may have positive effect on piglets performance in lactation.

Mammary metabolism and colostrogenesis in sows during late gestation and the colostral period.

The aims of this study were to investigate 1) the effect of high dietary fiber (DF; 19.3% to 21.7%) supplemented to late gestating sows on mammary uptake and metabolism of energy substrates as well as colostrum production and 2) the ontogeny of colostral fat and lactose synthesis using mammary carbon balance, and colostral protein using IgG as a biomarker. Sows were fed either a control diet (CON) consisting of a standard gestation diet (14.6% DF) until day 108 of gestation and a transition diet (16.8% DF) from day 109 of gestation until farrowing or a high DF treatment where part of the daily ration was replaced with a high DF supplement (FIB). The FIB sows received 19.3% and 21.7% DF in the last 2 wk prior to farrowing. Sows were surgically implanted with permanent indwelling catheters at day 75 ± 2 of gestation and blood samples were collected at 6 different time points in late gestation and at 11 different time points within 24 h after the onset of farrowing. Colostrum samples were collected at 0, 12, and 24 h after the onset of farrowing. Arterial concentration of acetate (P = 0.05) and colostral fat content (P = 0.009) were greater in FIB sows compared with CON sows. Plasma IgG dropped from day -10 relative to farrowing (P < 0.001), suggesting an uptake by the mammary glands. Mammary plasma flow (P = 0.007) and net mammary uptake of glucose (P = 0.04) increased during farrowing while dietary treatment had no effect on net mammary uptake of other energy substrates during late gestation and farrowing. The net mammary uptake of carbon from glucogenic precursors did not equate to the sum of carbons secreted in colostral lactose and released as CO2, indicating that carbons from ketogenic precursors were likely used for colostral fat and for oxidation. Mammary nonprotein carbon uptake matched the mammary output, indicating that the majority of colostral fat and lactose were produced after the onset of farrowing. In conclusion, high DF included in the diet for late gestating sows increased colostral fat content by 49% but this substantial dietary response could not be explained by the increased carbon uptake from short chain fatty acids during the colostral period. The nonprotein carbon balance of mammary glands during farrowing suggests that the majority of colostral fat and lactose were produced after the onset of farrowing, whereas the drop in plasma IgG in late gestation suggests that the mammary glands take up this colostral component prior to farrowing.

Effect of dietary protein intake on energy utilization and feed efficiency of lactating sows.

The objective of the current study was to quantify loss of energy in feces, urine, heat, and milk, to evaluate feed efficiency and to evaluate optimal ratio of dietary CP to energy for lactating sows fed increasing dietary CP. A total of 72 sows were included in the experiment from day 2 after parturition until weaning at day 28. Sows were allocated to 6 dietary treatments formulated to be isocaloric (9.8 MJ NE/kg) and increasing standardized ileal digestible (SID) CP (11.8, 12.8, 13.4, 14.0, 14.7, and 15.6% SID CP). Sows were weighed and back fat scanned within 2 d after farrowing, at days 18 ± 3 and 28 ± 3. Litters were standardized to 14 piglets within 2 d after farrowing and weighed at day 1 or 2 and at days 11, 18, and 28 (within ± 3 d). Feed intake (feed supply minus residue) was registered, and milk, urine, and fecal samples were collected at days 4, 11, and 18 (within ± 3 d). Sow milk yield was estimated from litter gain and litter size, and sow heat production was calculated factorially. On days 4 and 18 (±3 d), sows were enriched with D2O (deuterated water) to estimate body protein and fat pool size. Overall, sow BW loss, back fat loss, fat and protein mobilization, litter size, and piglet performance were not affected by diets, except for sows fed treatment 5, which had lower ADFI and lower milk production, and a tendency to lower piglet ADG compared with the remaining treatment groups (P < 0.01, P = 0.03, P =0.08, respectively). Relative to GE intake, the energy excreted in urine increased from 3.3% to 5.3% (P < 0.001), whereas energy lost as heat increased numerically from 54.5% to 59.0% with increasing dietary CP. The feed efficiency as evaluated by NE corrected for body mobilization peaked when sows were fed at their requirement (treatment 2; 12.8% SID CP; P = 0.01), whereas the feed efficiency was 1% lower for treatment 1, whereas it was 3% to 6% lower for treatments 3 through 6. In conclusion, energy loss in urine and likely also energy lost as heat increase if the dietary protein to energy ratio is unbalanced, and evaluating feed efficiency of lactating sows by correcting for body mobilization seems to be a promising approach to improve sow feeding in the future.

Hormonal and metabolic indicators before and after farrowing in sows affected with postpartum dysgalactia syndrome.

BACKGROUND: Postpartum dysgalactia syndrome (PDS) in sows is difficult to diagnose and the pathogenesis is obscure. Hormonal changes related to the disease are often difficult to distinguish from those found in the normal transition period from gestation to lactation. The study aimed to investigate metabolic and hormonal changes related to PDS with the goal of identifying potential biomarkers in sows suffering from PDS (PDS+). Selected biomarkers were examined by comparing 38 PDS+ sows with 38 PDS negative (PDS-) sows. The sows were sampled every 24 h from 60 h ante partum (a.p.) to 36 h post partum (p.p.). RESULTS: Compared to the baseline (60 to 36 h a.p.), cortisol in serum and saliva and fasting blood glucose concentrations increased in PDS+ as well as PDS- sows. C-peptide decreased relative to the baseline in PDS+ sows, and prolactin and 8-epi prostaglandin F2 alpha (8-epi-PGF2α) decreased in PDS- sows. Concentrations of cortisol in serum and saliva, salivary chromogranin A (CgA), fasting blood glucose, C-peptide, and 8-epi-PGF2α differed significantly between PDS+ and PDS- sows, with levels of cortisol in serum and saliva, salivary CgA, and 8-epi-PGF2α in serum being different in the two groups already before parturition. Concentrations of salivary CgA were significantly lower in PDS- sows than in PDS+ sows during the entire study period. CONCLUSIONS: The results suggest that salivary CgA, cortisol and serum 8-epi-PGF2α may potentially serve as early diagnostic indicators for PDS. The consistently higher salivary CgA concentration in PDS+ sows compared to PDS- sows may indicate that homeostatic disturbances are present between 36 to 60 h before parturition in sows developing PDS. The higher serum and saliva cortisol concentration in PDS+ sows compared to PDS- sows could reflect an early sign of inflammation or stress. The significantly lower C-peptide in PDS+ sows compared to PDS- sows may reflect a lower food intake. Our results contribute to the understanding of the pathogenesis of PDS, and the homeostatic disturbances detected before parturition warrants further investigation. The diagnostic potential of the markers identified in this study should be investigated further in a larger population of sows.

Impact of Diet-Modulated Butyrate Production on Intestinal Barrier Function and Inflammation.

A major challenge in affluent societies is the increase in disorders related to gut and metabolic health. Chronic over nutrition by unhealthy foods high in energy, fat, and sugar, and low in dietary fibre is a key environmental factor responsible for this development, which may cause local and systemic inflammation. A low intake of dietary fibre is a limiting factor for maintaining a viable and diverse microbiota and production of short-chain fatty acids in the gut. A suppressed production of butyrate is crucial, as this short-chain fatty acid (SCFA) can play a key role not only in colonic health and function but also at the systemic level. At both sites, the mode of action is through mediation of signalling pathways involving nuclear NF-κB and inhibition of histone deacetylase. The intake and composition of dietary fibre modulate production of butyrate in the large intestine. While butyrate production is easily adjustable it is more variable how it influences gut barrier function and inflammatory markers in the gut and periphery. The effect of butyrate seems generally to be more consistent and positive on inflammatory markers related to the gut than on inflammatory markers in the peripheral tissue. This discrepancy may be explained by differences in butyrate concentrations in the gut compared with the much lower concentration at more remote sites.