Supplementation of sows with L-carnitine during pregnancy and lactation improves growth of the piglets during the suckling period through increased milk production

Rumen-protected l-carnitine supplementation during mating period altered metabolic status and reproductive performance of ewes

Current study hypothesized that dietary l-carnitine (LC) inclusion during the mating period ameliorates both metabolic status and reproductive performance of ewes. Seventy Baluchi ewes (52 ± 4.2 kg of bodyweight and 18 ± 6 months old of age) were enrolled in this study. Animals were randomly allocated into two dietary treatments, control (only basal diet) or basal diet plus supplementation with a rumen-protected LC (Carneon 20 Rumin-pro; 20% LC; Kaesler Nutrition GmbH) at the rate of 10 g/head/day from 21 days before until 35 days after introducing rams to the ewes (MP). Feed intake was monitored by subtracting the ort from feed offered. Blood sample collection was conducted on Days -10, +10 and +20 relative to MP. Pregnancy was confirmed on Day 30 post-MP. Feed intake of the ewes in the LC group was higher than the control (p < 0.05). LC supplementation increased the cholesterol concentration in the ewes (p < 0.05). Blood urea concentration of animals in the LC group was significantly lower than the control (p < 0.05). The mRNA expression of toll-like receptor 4 was evidently lower in animals supplemented with LC than the control (p < 0.05). Both lambing and fecundity rates in the LC group tended to be higher compared with the control. LC supplementation showed potential to alter certain metabolites in the ewes. A tendency for higher lambing rate may partly be driven by dams efficient energy partitioning to support foetal growth and maintaining pregnancy.

Impact of dietary supplementation of l-Arginine, l-Glutamine, and the combination of both on nursing performance of multiparous sows

Dietary supplementation with arginine (Arg) or glutamine (Gln) has been considered as an option to improve nursing performance in reproductive sows. This study investigated whether a low-level supplementation of Arg or Gln or a blend of both could modify milk nutrients and improve piglets' growth beyond weaning. Seventy-two multiparous sows were assigned to four groups: one group fed a control diet, three treatment groups fed the control diet supplemented with either 0.35% Arg, 0.35% Gln, or both, from day 108 of gestation until weaning at day 26 of lactation. Immediately after birth, the litters were cross fostered to 13 piglets and monitored until 2 wk after weaning. Sows body condition and litter growth were assessed. Colostrum and milk samples were collected for nutrient analyses. Plasma concentrations of insulin-like growth factor 1 (IGF-1) around weaning were determined in sows and two representative piglets per litter. Supplementing Gln or the combination of Arg and Gln had no effect on the parameters studied. Arg supplementation increased weaning weight, while decreasing the variation of piglet weights 2 wk after weaning. There was no correlation with plasma IGF-1 since the hormone was not altered in sows or piglets. The colostral concentration of fat tended to increase in the Arg-group, whereas protein, lactose, energy, and polyamine concentrations remained unaffected. Milk samples obtained on day 12 and 25 of lactation were not influenced by dietary treatment. The data indicate that there might be a window of opportunity, explicitly at the onset of lactation, for dietary intervention by maternal dietary Arg supplementation.

In vitro transdifferentiated signatures of goat preadipocytes into mammary epithelial cells revealed by DNA methylation and transcriptome profiling

During mammary development, the transdifferentiation of mammary preadipocytes is one of the important sources for lactating mammary epithelial cells (MECs). However, there is limited knowledge about the mechanisms of dynamic regulation of transcriptome and genome-wide DNA methylation in the preadipocyte transdifferentiation process. Here, to gain more insight into these mechanisms, preadipocytes were isolated from adipose tissues from around the goat mammary gland (GM-preadipocytes). The GM-preadipocytes were cultured on Matrigel in conditioned media made from goat MECs to induce GM-preadipocyte-to-MEC transdifferentiation. The transdifferentiated GM-preadipocytes showed high abundance of keratin 18, which is a marker protein of MECs, and formed mammary acinar-like structures after 8 days of induction. Then, we performed transcriptome and DNA methylome profiling of the GM-preadipocytes and transdifferentiated GM-preadipocytes, respectively, and the differentially expressed genes and differentially methylated genes that play underlying roles in the process of transdifferentiation were obtained. Subsequently, we identified the candidate transcription factors in regulating the GM-preadipocyte-to-MEC transdifferentiation by transcription factor-binding motif enrichment analysis of differentially expressed genes and differentially methylated genes. Meanwhile, the secretory proteome of GM-preadipocytes cultured in conditioned media was also detected. By integrating the transcriptome, DNA methylome, and proteome, three candidate genes, four proteins, and several epigenetic regulatory axes were further identified, which are involved in regulation of the cell cycle, cell polarity establishment, cell adhesion, cell reprogramming, and adipocyte plasticity. These findings provide novel insights into the molecular mechanism of preadipocyte transdifferentiation and mammary development.

Lycopene improves maternal reproductive performance by modulating milk composition and placental antioxidative and immune status

Placental health and milk quality are important for maternal reproductive performance during pregnancy and lactation. Lycopene plays an important role in antioxidation, anti-inflammation and regulating lipid metabolism. The goal of the present study was to investigate the effects of dietary lycopene supplementation in the pig model on reproductive performance, placental health and milk composition during maternal gestation and lactation. In the present study, the litter size of live piglets was increased and the litter size of dead piglets was decreased by lycopene supplementation of the diet of sows. The litter weight at birth and weaning were increased in the lycopene group. Through placental proteomics, we enriched differentially expressed proteins (DEPs), gene ontology (GO) terms, and Kyoto encyclopedia of proteins and genomes (KEGG) pathways involved in immunity, anti-inflammation, antioxidants, and lipid metabolism and transport. Furthermore, in terms of placental health, we analyzed the levels of related enzymes, metabolites and mRNA expression in the placenta. Lycopene was shown to reduce mRNA expression and the levels of placental inflammatory factors, increase the content of immunoglobulin, improve the antioxidant capacity, and improve lipid metabolism and lipid transport in the placenta. In terms of sow milk composition, lycopene increased the levels of immunoglobulins in colostrum and lactose in colostrum and milk. Overall, the results of the present study demonstrate that dietary lycopene supplementation of sows during gestation and lactation improves the reproductive performance to a certain extent; this may be due to lycopene improving the placental health and milk composition of sows.

L-carnitine increases cell proliferation and amino acid transporter expression via the activation of insulin-like growth factor I signaling pathway in rat trophoblast cells

Early embryo implantation and development is primarily determined by the homeostasis between cellular apoptosis and proliferation as well as placental nutrient transporters. Recent studies showed that L-carnitine enhances female reproductive performance. However, the potential function of L-carnitine on placenta is largely unknown. In our study, primary rat trophoblast cells were separated and cultured for 12 hr in medium containing various concentrations of L-carnitine (0, 1, 10, and 50 mM). Placenta trophoblast cells treated with 50 mM L-carnitine increased the proportion of cells in S phase of the cell cycle (p < .05). In addition, live cell percentage was increased when treated with either 10 mM or 50 mM L-carnitine, which was accompanied with decreased necrotic cells, late apoptotic cells, and early apoptotic cells (p < .05). Compared with the control treatment, the mRNA expression of insulin-like growth factor I (IGF-1) and insulin-like growth factor I receptor (IGF-1R) was higher in rat placenta trophoblasts treated with either 10 mM or 50 mM L-carnitine (p < .05). Similarly, sodium-dependent neutral amino acid transporter (SNAT)-1 and SNAT2 were up-regulated in both mRNA and protein levels when trophoblast cells were treated with 50 mM L-carnitine (p < .05). Inhibiting downstream targets (Akt or ERK signaling pathways) of IGF-1 signaling pathway partially blocked the effect the L-carnitine-induced increase in protein abundances of SNAT1 and SNAT2. Collectively, our data showed protective role of L-carnitine on placenta trophoblast cells through the involvement of IGF-1 signaling pathway.

Effect of dietary L-carnitine supplementation to sows during gestation and/or lactation on sow productivity, muscle maturation and lifetime growth in progeny from large litters

Genetic selection for increased sow prolificacy has resulted in decreased mean piglet birth-weight. This study aimed to investigate the effect of L-carnitine (CAR) supplementation to sows during gestation and/or lactation on sow productivity, semitendinosus muscle (STM) maturity, and lifetime growth in progeny. Sixty-four sows were randomly assigned to one of four dietary treatments at breeding until weaning; CONTROL (0mg CAR/d), GEST (125mg CAR/d during gestation), LACT (250mg CAR/d during lactation), and BOTH (125mg CAR/d during gestation & 250mg CAR/d during lactation). The total number of piglets born per litter was greater for sows supplemented with CAR during gestation (17.3 v 15.8 ± 0.52; P<0.05). Piglet birth-weight (total and live) was unaffected by sow treatment (P>0.05). Total myofibre number (P=0.08) and the expression level of selected myosin heavy chain genes in the STM (P<0.05) was greater in piglets of sows supplemented with CAR during gestation. Pigs from sows supplemented with CAR during gestation had lighter carcasses at slaughter than pigs from non-supplemented sows during gestation (83.8 v 86.7 ± 0.86kg; P<0.05). In conclusion, CAR supplementation during gestation increased litter size at birth without compromising piglet birth-weight. Results also showed that the STM of piglets born to sows supplemented with CAR during gestation was more developed at birth. However, carcass weight at slaughter was reduced in progeny of sows supplemented with CAR during gestation. The CAR supplementation strategy applied during gestation in this study could be utilized by commercial pork producers to increase sow litter size and improve offspring muscle development.

Effect of l-carnitine supplementation and sugar beet pulp inclusion in gilt gestation diets on gilt live weight, lactation feed intake, and offspring growth from birth to slaughter1

This study evaluated the effects of l-carnitine (CAR) and sugar beet pulp (SBP) inclusion in gilt gestation diets on gilt live weight, cortisol concentration, lactation feed intake, and lifetime growth of progeny. Eighty-four pregnant gilts (Large White × Landrace) were randomly assigned to a treatment at day 38 of gestation until parturition; Control (0% SBP, 0 g CAR), CAR (0.125 g/d CAR), SBP (40% SBP), and SBP plus CAR (40% SBP, 0.125 g/d CAR). Gilts were weighed and back-fat depth was recorded on day 38, day 90, and day 108 of gestation and at weaning. Gilt saliva samples were collected pre-farrowing and fecal consistency was scored from entry to the farrowing room until day 5 post-partum. The number of piglets born (total, live, and stillborn) and individual birth weight was recorded. Piglet blood glucose concentration was measured 24 h post-partum and pigs were weighed on day 1, day 6, day 14, day 26, day 76, day 110, and day 147 of life. Carcass data were collected at slaughter. There was no interaction between CAR and SBP for any variable measured. The SBP-fed gilts were heavier on day 90 and day 108 of gestation (P < 0.05) and lost more weight during lactation (P < 0.05) than control gilts. They also had a greater fecal consistency score (P < 0.01). Total farrowing duration, piglet birth interval, and lactation feed intakes were similar between treatments (P > 0.05). The number of piglets born (total, live, and stillborn) and piglet birth weight was likewise similar between treatments (P > 0.05). Piglets from CAR-fed gilts had lower blood glucose concentrations (P < 0.01), while piglets from SBP-fed gilts had greater blood glucose concentrations (P < 0.01). Piglets from CAR gilts had a lower average daily gain between day 1 and day 6 (P < 0.05) and day 14 and day 26 post-partum (P < 0.05) compared to piglets from control gilts. However, CAR gilts weaned a greater number of pigs (P = 0.07). Live weight and carcass weight at slaughter were heavier for pigs from CAR gilts (P < 0.05) and from SBP gilts (P < 0.05). Pigs from CAR gilts (P < 0.01) and SBP gilts (P < 0.05) had increased carcass muscle depth. In conclusion, no benefit was found from the combined feeding of CAR and SBP. Fed separately, CAR increased the live weight, carcass weight, and muscle depth of progeny at slaughter. Feeding a high SBP diet increased fecal consistency in gilts pre-farrowing and increased live weight and carcass muscle depth of progeny.

l-carnitine and fat type in the maternal diet during gestation and lactation modify the fatty acid composition and expression of lipid metabolism-related genes in piglets

This study examined the influence of adding different amounts of maternal dietary l-carnitine and two fat types on fatty acid (FA) composition and the expression of lipid metabolism-related genes in piglets. The experiment was designed as a 2 × 2 factorial with two fat types (3.5% soyabean oil, SO, and 3.5% fish oil, FO) and two levels of l-carnitine (0 and 100 mg/kg) added to the sows' diets. A higher proportion of n-3 polyunsaturated fatty acids (PUFA) and a lower ratio of n-6/n-3 PUFA in sow milk and piglet tissues were observed in the FO groups than in the SO groups. Adding l-carnitine increased the proportion of C16:1 in sow milk and decreased n-3 PUFA in piglet subcutaneous fat. Hepatic peroxisome proliferator-activated receptor α (PPAR-α) was more abundantly expressed in piglets from the FO groups than from the SO groups (p < 0.05), whereas stearoyl-CoA-desaturase (SCD), sterol regulatory element binding protein-1 (SREBP1) and ∆6-desaturase (D6D) genes were less expressed in the FO groups compared with piglets from the SO groups. The expression of fatty acid synthase (FAS) genes was decreased in the SO groups with l-carnitine compared to that of the other dietary treatments. No differences among dietary treatments were observed with regard to the expression of acetyl-CoA carboxylase (ACC). In conclusion, FO and l-carnitine supplementation in sows affect FA composition and hepatic gene expression in piglets.

Basic mechanisms of the regulation of L-carnitine status in monogastrics and efficacy of L-carnitine as a feed additive in pigs and poultry

A great number of studies have investigated the potential of L-carnitine as feed additive to improve performance of different monogastric and ruminant livestock species, with, however, discrepant outcomes. In order to understand the reasons for these discrepant outcomes, it is important to consider the determinants of L-carnitine status and how L-carnitine status is regulated in the animal's body. While it is a long-known fact that L-carnitine is endogenously biosynthesized in certain tissues, it was only recently recognized that critical determinants of L-carnitine status, such as intestinal L-carnitine absorption, tissue L-carnitine uptake, endogenous L-carnitine synthesis and renal L-carnitine reabsorption, are regulated by specific nutrient sensing nuclear receptors. This review aims to give a more in-depth understanding of the basic mechanisms of the regulation of L-carnitine status in monogastrics taking into account the most recent evidence on nutrient sensing nuclear receptors and evaluates the efficacy of L-carnitine as feed additive in monogastric livestock by providing an up-to-date overview about studies with L-carnitine supplementation in pigs and poultry.

Effects of l-carnitine in the distillers dried grains with solubles diet of sows on reproductive performance and antioxidant status of sows and their offspring

Distillers dried grains with solubles (DDGS) are highly susceptible to lipid oxidation because DDGS contain about 10% crude fat, which is largely composed of polyunsaturated fatty acids. l-carnitine serves an important function in fatty acids β-oxidation, and also has antioxidant properties. The objective of this study was to examine the effects of l-carnitine in the DDGS diet of gestating and lactating sows on reproductive performance, milk composition and antioxidant status of sows and their offspring. One hundred and twenty sows (Landrace×Large white, mean parity 4.2, initial BW 230 kg) were randomly allotted to 1 of 4 dietary treatments (n=30 sows/treatment). Treatments were arranged as a 2×2 factorial with two levels of dietary DDGS (0 v. 250 g/kg in gestating diets and 400 g/kg in lactating diets) and two levels of dietary l-carnitine (0 v. 100 mg/kg in gestating diets and 0 v. 200 mg/kg in lactating diets). Distillers dried grains with solubles had no significant effect on litter size but significantly reduced the birth weights and weaning weights of piglets (P0.05). Supplementing the diets with l-carnitine had no significant effect of total litter size (P&gt;0.05) but increased the number of piglets born alive and piglets weaned, birth weight and weaning weight of piglets and litter weight at birth and weaning (P&lt;0.05). l-carnitine supplementation also increased the concentration of l-carnitine in milk and l-carnitine status of piglets (P&lt;0.05). The antioxidant enzyme activities of new born and weaning piglets were increased (P&lt;0.05) by maternal dietary l-carnitine but this did not extend to finishing pigs. In conclusion, including DDGS in the sows diet could induce oxidative stress, which may be associated with the reduced individual birth and weaning weight of piglets. Dietary l-carnitine supplementation improved the antioxidant and l-carnitine status of sows, which may be associated with the improved reproduction and piglet performance and the antioxidant status of piglets at birth and weaning. There were no interactions between DDGS and l-carnitine.

Evaluation of three different patterns of feed intake during early lactation in lactating sows

Forty-five multiparous sows (Landrace × Yorkshire; parity: 3.58 ± 1.30) were used to determine the effects of three patterns of feed intake during early lactation on the performance of lactating sows. Experimental treatments were as follows: IFI-1.4, the amount of feed increased by 1.4 kg per day for the first 5 days post-farrowing, followed by ad libitum feeding until weaning; IFI-1.0, the amount of feed increased by 1.0 kg per day for the first 7 days post-farrowing, followed by ad libitum feeding until weaning; IFI-0.7, the amount of feed increased by 0.7 kg per day for the first 10 days post-farrowing, followed by ad libitum feeding until weaning. The number of live piglets at birth/litter in three dietary treatments was 11.50, 10.07, and 10.85, respectively. Sows in the IFI-1.4 treatment had lower backfat loss during lactation, greater daily feed intake during days 1-6, 7-12, and 1-24 compared with those in the IFI-0.7 treatment (p < .05). The litter weaning weight, litter weight gain, and average litter daily gain in the IFI-1.4 treatment were greater compared with those in the IFI-0.7 treatment (p < .05). In conclusion, the results indicated that the IFI-1.4 feed intake pattern allowed lactating sows and their litters to obtain optimal performance.

Transfer of β-hydroxy-β-methylbutyrate from sows to their offspring and its impact on muscle fiber type transformation and performance in pigs

Background

Previous studies suggested that supplementation of lactating sows with β-hydroxy-β-methylbutyrate (HMB) could improve the performance of weaning pigs, but there were little information in the muscle fiber type transformation of the offspring and the subsequent performance in pigs from weaning through finishing in response to maternal HMB consumption. The purpose of this study was to determine the effect of supplementing lactating sows with HMB on skeletal muscle fiber type transformation and growth of the offspring during d 28 and 180 after birth. A total of 20 sows according to their body weight were divided into the control (CON, n = 10) or HMB groups (HMB, n = 10). Sows in the HMB group were supplemented with β-hydroxy-β-methylbutyrate calcium (HMB-Ca) 2 g /kg feed during d 1 to 27 of lactation. After weaning, 48 mixed sex piglets were blocked by sow treatment and fed standard diets for post-weaning, growing, finishing periods. Growth performance was recorded during d 28 to 180 after birth. Pigs were slaughtered on d 28 (n = 6/treatment) and 180 (n = 6/treatment) postnatal, and the longissimus dorsi (LD) was collected, respectively.

Results

The HMB-fed sows during lactation showed increased HMB concentration (P < 0.05) in milk and LD of weaning piglets (P < 0.05). In addition, offsprings in HMB group had a higher finishing BW and lean percentage than did pigs in CON group (P < 0.05), meanwhile, compared with pigs from sows fed the CON diet, pigs from sows fed HMB diet showed higher type II muscle fiber cross-sectional area (CSA), elevated myosin heavy chain (MyHC) IIb and Sox6 mRNA, and fast-MyHC protein levels in LD (P < 0.05).

Conclusions

HMB supplemented to sow diets throughout lactation increases the levels of HMB in maternal milk and skeletal muscle of pigs during d 28 after birth and promotes subsequent performance of pigs between d 28 and 180 of age by enhancing glycolytic muscle fiber transformation.

Dietary ractopamine supplementation during the first lactation affects milk composition, piglet growth and sow reproductive performance

Excessive mobilization of body reserves during lactation delays the return to reproductive function in weaned primiparous sows. This study tested the hypothesis that supplementing the lactation diets of first-parity sows with ractopamine hydrochloride would reduce maternal weight loss and improve subsequent reproductive performance. Gestating gilts were allocated to one of two treatment groups (n=30 sows/treatment), with one group fed a standard lactation diet (2.5g/Mcal LYS: DE) throughout lactation (CTRL), whereas the treatment group received the standard lactation diet supplemented with 10mg/kg ractopamine hydrochloride (RAC) from d 1 to 13 of lactation and 20mg/kg RAC from d 14 of lactation until artificial insemination (AI). Weaning occurred on d 21 of lactation, with AI occurring at the first post-weaning estrus. Compared to CTRL, RAC supplementation decreased (P<0.05) liveweight loss between d 13 and 20 of lactation (4.3±0.90 versus 1.3±0.96kg), and tended to increase (P=0.06) the number of second litter piglets born alive (9.5±0.52 versus 8.1±0.74). Treatment (RAC versus CTRL) reduced milk protein levels on d 13 and 20 of lactation (P<0.05), and piglet weight gain between d 13 and 20 of lactation (260±0.01 versus 310±0.01g/day, P<0.01). In conclusion, it is evident that dietary RAC altered milk composition and stimulated conservation of maternal body reserves during the third week of lactation, resulting in a beneficial effect on subsequent reproductive performance.

Effects ofl-carnitine and/or maize distillers dried grains with solubles in diets of gestating and lactating sows on the intestinal barrier functions of their offspring

The objective of this study was to investigate the effects ofl-carnitine and/or maize distillers dried grains with solubles (DDGS) in diets of gestating and lactating sows on the intestinal barrier functions of their offspring. The experiment was designed as a 2×2 factorial with two dietary treatments (soyabean mealv.DDGS) and twol-carnitine levels (0v.100 mg/kg in gestating diets and 0v.200 mg/kg in lactating diets). Sows (Landrace×Large White) with an average parity of 4·2 with similar body weight were randomly assigned to four groups of thirty each. Dietary supplementation withl-carnitine increased the total superoxide dismutase activity but decreased the concentration of malondialdehyde of the jejunal mucosa in newborn piglets and weaning piglets on day 21. Dietary supplementation withl-carnitine decreased the concentrations of IL-1β, IL-12 and TNF-αin the jejunal mucosa of newborn piglets and decreased the concentrations of IL-6 and TNF-αin the jejunal mucosa of weaning piglets on day 21. There was an interaction between dietary treatment andl-carnitine on the bacterial numbers of total eubacteria in the digesta of caecum in weaning piglets on day 21. Bacterial numbers of total eubacteria in weaning piglets on day 21 were significantly increased byl-carnitine only in soyabean meal diet, but there was no significant effect ofl-carnitine in DDGS-based diet. Dietary supplementation withl-carnitine increased the bacterial numbers ofLactobacillusspp. and bifidobacteria spp. in the digesta of caecum in weaning piglets on day 21. Dietary supplementation withl-carnitine in sows affected the expression of tight junction proteins (claudin 1, zonula occludens-1 (ZO-1) and occludin) in the jejunal mucosa of their offspring by increasing the expression of ZO-1 mRNA in the jejunal mucosa of newborn piglets, and by increasing the expression of ZO-1 and occludin mRNA in the jejunal mucosa of weaning piglets on day 21. In conclusion, dietary supplementation withl-carnitine in gestating and lactating sows had positive effects on intestinal barrier functions of newborn piglets and weaning piglets on day 21, but it did not have effects on intestinal barrier functions of growing–finishing pigs in the filial generation. There were no effects of dietary treatment of sows on intestinal barrier functions in their offspring.

Effects of Dietary Supplementation of Oregano Essential Oil to Sows on Oxidative Stress Status, Lactation Feed Intake of Sows, and Piglet Performance

Fifty-four multiparous large white sows were used to determine the effects of supplementing oregano essential oil (OEO) to the gestation and lactation diets on oxidative stress status, lactation feed intake, and their piglet performance. Two groups were fed diets with (OEO; n = 28) or without (Control; n = 26) supplemental 15 mg/kg OEO during gestation and lactation. The serum levels of reactive oxygen species (ROS) (P < 0.05), 8-hydroxy-deoxyguanosine (8-OHdG) (P < 0.05), and thiobarbituric acid reactive substances (TBARS) (P < 0.05) were higher during gestation (days 90 and 109) and lactation (days 1 and 3) than in early gestation (day 10). Compared with the control group, the OEO diet significantly reduced sows' serum concentrations of 8-OHdG (P < 0.05) and TBARS (P < 0.01) on day 1 of lactation. The OEO diet increased the sows' counts of faecal lactobacillus (P < 0.001) while reducing Escherichia coli (P < 0.001) and Enterococcus (P < 0.001). In the third week of lactation the treatment tended to increase sow's feed intake (P = 0.07), which resulted in higher average daily gain (P < 0.01) of piglets. Our results demonstrated that there is an increased systemic oxidative stress during late gestation and early lactation of sows. The OEO supplementation to sows' diet improved performance of their piglets, which may be attributed to the reduced oxidative stress.

Effect of feeding liquid milk supplement on litter performances and on sow back-fat thickness change during the suckling period

Abstract. The aim of the present study was to investigate the effect of liquid milk supplement on litter performance (weight development of the piglets, weaning weight and mortality) and on sow back-fat thickness change during the suckling period. Data were collected from 150 litters, with the weight of a total of 1709 piglets measured at birth, at 14 days of age and at weaning (28 days), respectively. Sow (n = 150) back-fat depth was measured the day before farrowing, 14 days after farrowing and at weaning. In the control group (n = 363), the piglets were suckled and got pre-starter feed from day 10. In the four experimental groups (MS1; MS2; MS2 and MS4; n = 1346), the piglets received additional milk replacer in various concentrations from the 10th day of life. While there were no significant differences in birth weight between the control and experimental groups, we did find significant differences between the 14-day weights and weaning weights. The milk supplement significantly reduced mortality compared to the control (11.6 vs. 4.9; 5.9, 8.9; 8.3 %). However, there were no statistically significant differences between litter homogeneity data, based on the CV% of piglet weight. Three experimental groups (MS1, MS2 and MS4) were more homogenous compared to the control group at weaning (25.3 vs. 20.9; 20.3; 20.3 CV%). Based on the examination of sow back-fat thickness reduction, there were significant differences between the control (C) and MS3 groups (7.61 vs. 5.57 mm reduction, P < 0.05) during the suckling period. These results demonstrate the advantage of milk replacer on weaning weight. Litter homogeneity, piglet mortality and back-fat thickness of the sows were affected by providing milk replacer to the piglets during the suckling period.

Supplementation with l-carnitine downregulates genes of the ubiquitin proteasome system in the skeletal muscle and liver of piglets

Supplementation of carnitine has been shown to improve performance characteristics such as protein accretion in growing pigs. The molecular mechanisms underlying this phenomenon are largely unknown. Based on recent results from DNA microchip analysis, we hypothesized that carnitine supplementation leads to a downregulation of genes of the ubiquitin proteasome system (UPS). The UPS is the most important system for protein breakdown in tissues, which in turn could be an explanation for increased protein accretion. To test this hypothesis, we fed sixteen male, four-week-old piglets either a control diet or the same diet supplemented with carnitine and determined the expression of several genes involved in the UPS in the liver and skeletal muscle. To further determine whether the effects of carnitine on the expression of genes of the UPS are mediated directly or indirectly, we also investigated the effect of carnitine on the expression of genes of the UPS in cultured C2C12 myotubes and HepG2 liver cells. In the liver of piglets fed the carnitine-supplemented diet, the relative mRNA levels of atrogin-1, E214k and Psma1 were lower than in those of the control piglets (P < 0.05). In skeletal muscle, the relative mRNA levels of atrogin-1, MuRF1, E214k, Psma1 and ubiquitin were lower in piglets fed the carnitine-supplemented diet than that in control piglets (P < 0.05). Incubating C2C12 myotubes and HepG2 liver cells with increasing concentrations of carnitine had no effect on basal and/or hydrocortisone-stimulated mRNA levels of genes of the UPS. In conclusion, this study shows that dietary carnitine decreases the transcript levels of several genes involved in the UPS in skeletal muscle and liver of piglets, whereas carnitine has no effect on the transcript levels of these genes in cultivated HepG2 liver cells and C2C12 myotubes. These data suggest that the inhibitory effect of carnitine on the expression of genes of the UPS is mediated indirectly, probably via modulating the release of inhibitors of the UPS such as IGF-1. The inhibitory effect of carnitine on the expression of genes of the UPS might explain, at least partially, the increased protein accretion in piglets supplemented with carnitine.

Non-infectious factors associated with stillbirth in pigs: a review

The main objective of this review is to provide current information regarding non-infectious risk factors associated with stillborn piglets. These factors can be roughly categorized as genetic, maternal, piglet and environmental factors, but also interactions exist between several factors. An understanding of this multifactorial problem should help practitioners and farmers implementing a more effective farrowing management to obtain a high reproductive efficiency. From the papers studied in this review, it can be concluded that litter size, parity, sow's body condition and farrowing supervision/birth assistance seems to be the most relevant risk factors associated with stillborn piglets.

An overview of molecular and cellular mechanisms associated with porcine pregnancy success or failure

Prenatal mortality remains one of the major constraints for the commercial pig industry in North America. Twenty to thirty per cent of the conceptuses are lost early in gestation and an additional 10-15% is lost by mid-to-late gestation. Research over the last two decades has provided critical insights into how uterine capacity, placental efficiency, genetics, environment, nutrition and immune mechanisms impact successful conceptus growth; however, the exact cause and effect relationship in the context of foetal loss has yet to be determined. Similar to other mammalian species such as the human, mouse, rat, and primates, immune cell enrichment occurs at the porcine maternal-foetal interface during the window of conceptus attachment. However, unlike other species, immune cells are solely recruited by conceptus-derived signals. As pigs have epitheliochorial placentae where maternal and foetal tissue layers are separate, it provides an ideal model to study immune cell interactions with foetal trophoblasts. Our research is focused on the immune-angiogenesis axis during porcine pregnancy. It is well established that immune cells are recruited to the maternal-foetal interface, but their pregnancy specific functions and how the local milieu affects angiogenesis and inflammation at the site of foetal arrest remain unknown. Through a better understanding of how immune cells modulate crosstalk between the conceptus and the mother, it might be possible to therapeutically target immune cells and/or their products to reduce foetal loss. In this review, we provide evidence from the literature and from our own work into the immunological factors associated with porcine foetal loss.

Influence of dietary supplementation with (L)-carnitine on metabolic rate, fatty acid oxidation, body condition, and weight loss in overweight cats

OBJECTIVE

To investigate the influence of dietary supplementation with l-carnitine on metabolic rate, fatty acid oxidation, weight loss, and lean body mass (LBM) in overweight cats undergoing rapid weight reduction.

ANIMALS

32 healthy adult neutered colony-housed cats.

PROCEDURES

Cats fattened through unrestricted ingestion of an energy-dense diet for 6 months were randomly assigned to 4 groups and fed a weight reduction diet supplemented with 0 (control), 50, 100, or 150 μg of carnitine/g of diet (unrestricted for 1 month, then restricted). Measurements included resting energy expenditure, respiratory quotient, daily energy expenditure, LBM, and fatty acid oxidation. Following weight loss, cats were allowed unrestricted feeding of the energy-dense diet to investigate weight gain after test diet cessation.

RESULTS

Median weekly weight loss in all groups was ≥ 1.3%, with no difference among groups in overall or cumulative percentage weight loss. During restricted feeding, the resting energy expenditure-to-LBM ratio was significantly higher in cats that received l-carnitine than in those that received the control diet. Respiratory quotient was significantly lower in each cat that received l-carnitine on day 42, compared with the value before the diet began, and in all cats that received l-carnitine, compared with the control group throughout restricted feeding. A significant increase in palmitate flux rate in cats fed the diet with 150 μg of carnitine/g relative to the flux rate in the control group on day 42 corresponded to significantly increased stoichiometric fat oxidation in the l-carnitine diet group (> 62% vs 14% for the control group). Weight gain (as high as 28%) was evident within 35 days after unrestricted feeding was reintroduced.

CONCLUSIONS AND CLINICAL RELEVANCE

Dietary l-carnitine supplementation appeared to have a metabolic effect in overweight cats undergoing rapid weight loss that facilitated fatty acid oxidation.

Global transcriptional profiling in porcine mammary glands from late pregnancy to peak lactation

Sow milk yield and quality is crucial for the survival and growth of piglets. To understand the molecular mechanisms of lactogenesis and lactation, mammary tissue samples were taken from six sows at -17(±2), 1 and 17(±2) days relative to parturition. Mammary tissues from two sows in the same stage were used to extract RNA, which were subsequently pooled in equal amounts. Nine pooled samples were hybridized to porcine Affymetrix GeneChips. Totally 1,524 genes were detected as significantly differentially expressed over the time course tested (p<0.01, q<0.01, fold change≥2 or ≤-2), including 709 upregulated and 575 downregulated genes identified at peak lactation compared to late pregnancy. Gene ontology analysis revealed that most of the upregulated genes were involved in transport, biosynthetic processes, and homeostasis, whereas most of the downregulated genes were involved in intracellular signaling cascades, cell cycle, and DNA replication. Furthermore, we identified 64 differentially expressed genes of the solute carrier families. Taken together, our microarray analysis provides insights into previously uncharacterized changes in transcriptome between late pregnancy and peak lactation in the porcine mammary gland. The solute carrier genes and other differentially expressed genes identified in this study will guide further characterization of their function to enhance milk yield and piglet growth.

Carnitine and carnitine orotate affect the expression of the prolactin-releasing peptide gene

Carnitine is involved in fatty acid metabolism in mammals and is widely used as a nutritional supplement; carnitine orotate is a more absorbable form of carnitine. We investigated the effects of carnitine and carnitine orotate on mouse prolactin-releasing peptide (PrRP) mRNA expression. Twenty-four female mice were randomly divided into four groups of six; control mice were orally drenched with physiological saline solution (250 mg/kg body weight) and treatment mice were orally drenched with carnitine (250 mg/kg) or carnitine orotate (250 or 750 mg/kg), once a day, for 20 days from parturition. The carnitine or carnitine orotate was dissolved in saline solution before administration. The hypothalamus, pituitary and ovary were sampled on day 21 after parturition, and PrRP mRNA levels in these tissues were measured by semi-quantitative PCR, with glyceraldehyde 3-phosphate dehydrogenase as a control. Expression of PrRP in mice treated with carnitine and carnitine orotate was significantly increased in the ovary and significantly reduced in the pituitary gland. Compared with the control, hypothalamus PrRP mRNA increased significantly in the carnitine and low-dose carnitine orotate groups and decreased significantly in the high-dose carnitine orotate group. We conclude that carnitine and carnitine orotate regulate expression of PrRP in the pituitary gland and ovaries.

Role of carnitine in the regulation of glucose homeostasis and insulin sensitivity: evidence from in vivo and in vitro studies with carnitine supplementation and carnitine deficiency

BACKGROUND

Although carnitine is best known for its role in the import of long-chain fatty acids (acyl groups) into the mitochondrial matrix for subsequent β-oxidation, carnitine is also necessary for the efflux of acyl groups out of the mitochondria. Since intracellular accumulation of acyl-CoA derivatives has been implicated in the development of insulin resistance, carnitine supplementation has gained attention as a tool for the treatment of insulin resistance. More recent studies even point toward a causative role for carnitine insufficiency in developing insulin resistance during states of chronic metabolic stress, such as obesity, which can be reversed by carnitine supplementation.

METHODS

The present review provides an overview about data from both animal and human studies reporting effects of either carnitine supplementation or carnitine deficiency on parameters of glucose homeostasis and insulin sensitivity in order to establish the less well-recognized role of carnitine in regulating glucose homeostasis.

RESULTS

Carnitine supplementation studies in both humans and animals demonstrate an improvement of glucose tolerance, in particular during insulin-resistant states. In contrast, less consistent results are available from animal studies investigating the association between carnitine deficiency and glucose intolerance. The majority of studies dealing with this question could either find no association or even reported that carnitine deficiency lowers blood glucose and improves insulin sensitivity.

CONCLUSIONS

In view of the abovementioned beneficial effect of carnitine supplementation on glucose tolerance during insulin-resistant states, carnitine supplementation might be an effective tool for improvement of glucose utilization in obese type 2 diabetic patients. However, further studies are necessary to explain the conflicting observations from studies dealing with carnitine deficiency.

Restricted feed intake in lactating primiparous sows. I. Effects on sow metabolic state and subsequent reproductive performance

The effects of feed restriction (60% of anticipated feed intake; Restrict; n = 60) during the last week of a 21-day lactation in primiparous sows compared with feeding at 90% of anticipated feed intake (Control; n = 60) on sow metabolic state, litter growth and sow reproductive performance after weaning were compared. Metabolisable energy (ME) derived from feed was lower, ME derived from body tissues was higher and litter growth rate was reduced (all P < 0.05) in Restrict sows during the last week of lactation. Treatment did not affect weaning-to-oestrus interval, pregnancy rate, ovulation rate, embryonic survival or the number of live embryos (P > 0.05) at Day 30 of gestation: However, embryo weight was greater (P < 0.05) in Control than in Restrict sows (1.55 ± 0.04 vs 1.44 ± 0.04 g, respectively). These data suggest the biology of the commercial sow has changed and reproductive performance of contemporary primiparous sows is increasingly resistant to the negative effects of lactational catabolism. Overall, catabolism negatively affected litter weaning weight and embryonic development of the next litter, but the extent to which individual sows used tissue mobilisation to support these litter outcomes was highly variable.

Influence of l-carnitine on metabolism and performance of sows

In recent years, l-carnitine has been used increasingly as a supplement in livestock animals. The present review gives an overview of the effects of dietary l-carnitine supplementation on the reproductive performance of sows. Results concerning the effect of l-carnitine supplementation during pregnancy on litter sizes are controversial. There are some studies reporting an increased number of piglets born alive per litter, while others could not find such an effect. In contrast, most studies performed show consistently that l-carnitine supplementation to a sow diet low in native carnitine during gestation increases piglet and litter weights at birth and enhances growth of litters during the suckling period. Biochemical mechanisms underlying the favourable effect of carnitine on intra-uterine growth have not been fully elucidated. There is, however, some evidence that carnitine influences the insulin-like growth factor-axis in sows and leads to greater placentae, which in turn improves intra-uterine nutrition, and stimulates oxidation of glucose in the fetuses. These effects may, at least in part, be responsible for higher birth weights of piglets. The stimulating effect of carnitine on growth of the litters might be due to an improved suckling behaviour of piglets born to l-carnitine-supplemented sows, causing the sows' milk production to rise. In conclusion, recent studies have clearly shown that dietary l-carnitine supplementation increases the reproductive performance of sows. These findings suggest that endogenous de novo synthesis of carnitine is insufficient to meet the metabolic requirement of sows during gestation.

Maternal dietary L-carnitine supplementation influences fetal carnitine status and stimulates carnitine palmitoyltransferase and pyruvate dehydrogenase complex activities in swine

Effects of increasing maternal L-carnitine on carnitine status and energy metabolism in the fetus were evaluated by feeding pregnant swine a corn-soybean-based diet containing either 0 or 50 mg/kg added L-carnitine (n = 10/treatment) during the first 70 d of gestation. Carnitine, carnitine palmitoyltransferase (CPT), and pyruvate dehydrogenase complex (PDHC) activities were analyzed in tissues collected from fetuses on d 55 and 70. Maternal L-carnitine supplementation increased both fetal free and long-chain carnitine concentrations by 45% in liver and free carnitine by 31% in heart tissues but did not affect kidney tissue. Elevations in free and acylcarnitines increased with gestational age from 55 to 70 d in liver but not in heart and kidney. The increased carnitine concentrations resulted in a 45% increase in PDHC activity in heart and liver on d 70 of gestation but did not affect kidney and liver on d 55 of gestation. The increases in carnitine concentrations were accompanied by a 70% increase in hepatic CPT activity in 70-d-old fetuses, but activities in heart and kidney were unaffected. The Michaelis constant (K(m)) of CPT for carnitine in fetal tissues was not influenced by carnitine supplementation (P > 0.1). Notably, the concentrations of carnitine measured on d 70 were only 25-40% of the K(m) values in liver, 60-70% in heart, and 30-40% in kidney (P < 0.001). We conclude that carnitine ingestion during pregnancy increases fetal carnitine concentrations and stimulates heart PDHC and liver CPT activity without altering carnitine K(m).

Peripartal feeding strategy with different n-6:n-3 ratios in sows: effects on sows' performance, inflammatory and periparturient metabolic parameters

The present study aimed to investigate the effects of two lactation sow feeds, differing in n-6:n-3 ratio, given to sows before parturition on body condition and feed intake, periparturient metabolism (leptin, insulin, triiodothyronine (T3) and thyroxine (T4)), inflammatory parameters (TNFα, IL-6, serum amyloid A (SAA)) and on piglet performance (birth weight, survivability). The feed contained either a low (supplemented with fish oil; f groups) or high (supplemented with sunflower-seed oil; s groups) n-6:n-3 ratio and was administered from 8 d (f8, s8) or 3 d (f3, s3) before parturition until weaning. The level of inclusion of the oil sources was 2 %. Seventy-two sows were randomly allocated 8 d before expected farrowing into four groups: f3, f8, s3, s8. Type of feed had a significant influence on the sows' feed intake during the first 2 d of lactation (s < f), leptin on days 4, 3 and 2 before parturition (f < s), insulin on day 1 after parturition (f < s), T4 on the day before parturition (s < f) and rectal temperature on the day after parturition (f < s). Onset of administration of the feed (3 v. 8 d) had significant effects on leptin on day 2 before parturition (8 < 3), insulin on day 4 before parturition (3 < 8), T3 on day 4 before parturition and on the day after parturition (3 < 8), SAA on day 3 after parturition (8 < 3) and piglet weight during the first days postpartum (3 < 8). In conclusion, under the present conditions, a lactation feed low in n-6:n-3 ratio administered from 8 d before farrowing ensures improved feed intake during the first days postpartum and was associated with a better metabolic change and inflammatory profile in sows in the periparturient period.

Selected parameters in urine as indicators of milk production in lactating sows: A pilot study

Although insufficient milk production in lactating sows may cause tremendous economic losses, reliable methods for estimating milk production in sows under field conditions are not available. This study aimed to investigate whether urine parameters could be used to predict milk production in sows. The milk production of 18 sows was determined during early and mid-lactation. Morning (a.m.) and afternoon (p.m.) urinary levels of potassium (K), sodium (Na), calcium (Ca), magnesium (Mg), lactose and creatinine were analysed. The absolute concentrations, the ratios relative to creatinine, and the fractional excretions of all elements in urine were not significantly associated with milk production. The p.m./a.m. ratios of K, Na and Ca concentrations in urine (K(R), Na(R), and Ca(R)) were significant predictors for milk production, but only during mid-lactation. The total variation in milk production (r(2) value) explained by K(R), Na(R), Ca(R) amounted to 72%, 55%, 42%, respectively. Analysis of minerals and especially K in the a.m. and p.m. urine of sows during mid-lactation provided an acceptable indication of milk production. Further research is necessary to investigate whether the present results can be used to estimate milk production in hypogalactic sows under field conditions.

Influence of dietary L-carnitine and chromium picolinate on blood hormones and metabolites of gestating sows fed one meal per day1,2

Gestating sows (n = 44; parity = 2.0; BW = 208 kg) were used to determine the effects of dietary L-carnitine and Cr picolinate (CrP) on daily blood hormone and metabolite profiles. Diets were formulated as a 2 x 2 factorial with L-carnitine (0 or 50 ppm) and CrP (0 or 200 ppb) and were fed from breeding through gestation, lactation, and 28 d into the subsequent gestation, at which time blood collection occurred. Sows were fed 1 meal per day during gestation (2.04 kg from breeding until d 100 and 2.95 kg from d 100 until farrowing) and ad libitum during lactation. Sows were fitted with indwelling venous catheters, and blood (plasma) was collected at feeding, then once every 15 min for the first 3 h after feeding, and at 6, 9, 15, 20, and 24 h after feeding. Postfeeding and overall insulin and connecting peptide of insulin (c-peptide) was decreased for sows fed diets with CrP or L-carnitine and was greatest for sows fed the control diet; however, sows fed both L-carnitine and CrP had an intermediate response (L-carnitine x CrP, P < 0.01). Postfeeding glucose peak was decreased (P < 0.05) in sows fed diets with L-carnitine, CrP, or both, vs. the control, and mean glucose concentration was decreased (P < 0.01) for sows fed diets with CrP. L-Carnitine decreased (P < 0.04) the NEFA concentration. Sows fed diets with CrP exhibited increased (P < 0.03) postfeeding and overall NEFA and greater (P < 0.02) fasting and overall glycerol. Overall plasma urea N was lowest for sows fed the diet with L-carnitine; however, diets containing CrP had intermediate responses compared with the control (L-carnitine x CrP, P < 0.005). Sows fed diets with L-carnitine had greater (P < 0.008) IGF-I from 3 to 24 h after feeding and tended to exhibit greater (P < 0.06) overall IGFBP-3. Sows fed the diets with CrP had greater (P < 0.05) IGFBP-3 from 2 to 20 h after feeding. No differences were observed for glucagon or triacylglycerol (P > 0.10). The changes in metabolites and metabolic hormones indicate that both L-carnitine and CrP influence energy metabolism of gestating sows; however, their effects on blood hormones and metabolites differ. Thus, the improvement in energy status from adding both L-carnitine and CrP may have an additive effect on reproductive performance of sows.

Growth characteristics, blood metabolites, and insulin-like growth factor system components in maternal tissues of gilts fed L-carnitine through day seventy of gestation1,2

A total of 59 gilts (BW = 137.7 kg) from 3 breeding groups were used to assess the effects of feeding l-carnitine during gestation on gilt growth characteristics, blood metabolites, and uterine and chorioallantoic expression of IGF axis components at d 40, 55, and 70 of gestation. Experimental treatments were arranged in a 2 x 3 factorial, with main effects of added l-carnitine (0 or 50 ppm) and day after initial breeding (d 40, 55, or 70 of gestation). All gilts received a constant feed allowance of 1.75 kg/d and a top-dress containing 0 or 50 ppm of l-carnitine beginning on the first day of breeding through the assigned day of gestation. No dietary treatment differences were observed for gilt BW, backfat, or estimated protein or fat mass at any day of gestation. No differences were observed in circulating total and free carnitine at breeding, but concentrations increased (P < 0.01) as day of gestation increased for gilts fed diets containing l-carnitine compared with those fed the control diet. Maternal IGF-I concentration decreased (P < 0.01) from d 0 to 70 for all gilts, with no differences between treatments. Insulin-like growth factor binding protein-3 mRNA (P = 0.05) and IGFBP-5 mRNA (P = 0.01) increased in the endometrium of gilts supplemented with l-carnitine. These data demonstrate that l-carnitine supplementation and day of gestation alter the expression of the IGF axis by changing the expression of IGFBP at the fetal-maternal interface in swine. These changes in the IGF axis at the fetal maternal interface may aid in determining the reasons for the effects of l-carnitine on reproductive traits.

Pivalate lowers litter sizes and weights in female rats independent of its effect on carnitine status

The present study investigated whether treatment of female rats with pivalate affects their reproductive function. Therefore, two experiments with female rats were performed. The first experiment included two groups of rats which received drinking water without (control) or with 20 mmol pivalate/L. The second experiment included a control group (which received drinking water without pivalate and a diet without added carnitine) and four groups which received drinking water with 20 mmol/L pivalate and diets without or with 1, 3 or 5 g added carnitine/kg, respectively. In both experiments, rats treated with pivalate had a lower number of pups born alive and, as a consequence of this, lower litter weights than control rats (p<0.05); pup weights were not altered by pivalate treatment. Supplementation of dietary carnitine in Experiment 2 increased plasma and tissue carnitine concentration even in excess of those in control rats but did not restore normal litter sizes. This study shows for the first time that pivalate affects the reproductive function in female rats independent of its effect on the carnitine status.

Consequences of birth weight for postnatal growth performance and carcass quality in pigs as related to myogenesis

In polytocous species such as the pig there is intralitter variation in birth weight and skeletal muscle fiber number. It is commonly recognized that low birth weight in piglets correlates with decreased survival and lower postnatal growth rates. In the majority of low birth weight piglets low numbers of muscle fibers differentiate during prenatal myogenesis, for genetic or maternal reasons, and those low birth weight piglets with reduced fiber numbers are unable to exhibit postnatal catch-up growth. Pigs of low birth weight show the lowest growth performance and the lowest lean percentage at slaughter. In addition, they tend to develop extremely large muscle fibers (giant fibers) and poor meat quality, which results in part from the inverse correlation between fiber number and fiber size. Prenatal growth and myogenesis are under the control of various genetic and environmental factors, which can be targeted for growth manipulation. Genetic selection is considered a suitable tool to improve fetal growth and myogenesis. Prenatal development is mainly dependent on a close interrelation between nutritional supply/use and regulation by hormones and growth factors. In particular, the maternal somatotropic axis plays a significant role in the control of myogenesis. Thus, treatment of sows with GH until mid-gestation was able to increase birth weight and the number of muscle fibers in the small littermates of the progeny that are disadvantaged by insufficient nutrient supply. Growth hormone treatment was associated with increased nutrient availability to the embryos and changes in regulatory proteins of the GH-IGF axis. Interactions between maternal nutrition and the somatotropic axis in determining prenatal growth and myogenesis are worthy of further investigation.

Effect of l-Carnitine Infusion and Feed Restriction on Carnitine Status in Lactating Holstein Cows

Previously we determined that abomasal infusion of L-carnitine increased in vitro hepatic fatty acid oxidation, decreased liver lipid accumulation, and supported higher fat-corrected milk yield in feed-restricted lactating cows. The objectives of this study were to examine the effects of supplemental L-carnitine and amount of feed intake on free carnitine and carnitine ester concentrations in liver, muscle, milk, and plasma of lactating dairy cows. Eight lactating Holstein cows (132 +/- 36 d in milk) were used in a replicated 4 x 4 Latin square design with 14-d periods to test factorial combinations of water or L-carnitine infusion (20 g/d; d 5 to 14) and ad libitum or restricted (50% of previous 5-d intake; d 10 to 14) dry matter intake. Plasma was obtained 3 times daily on d 4, 8, and 12; milk samples were collected on d 8, 9, 13, and 14. Liver and muscle were biopsied on d 14 of each period. Free carnitine, short-chain acylcarnitine, and long-chain acylcarnitine concentrations were determined using a radioenzymatic assay coupled with ion exchange chromatography. Abomasal L-carnitine infusion increased total carnitine in plasma on d 8 and d 12. All liver carnitine fractions were increased by carnitine infusion. Feed restriction elevated concentrations of free carnitine, long-chain acylcarnitine, and total carnitine in liver tissue from carnitine-infused cows but not in those infused with water. In muscle, acid-soluble carnitine, long-chain acylcarnitine, and total carnitine concentrations were increased by carnitine infusion and feed restriction without significant interaction. Feed restriction increased free carnitine concentrations in muscle from water-infused cows but not in carnitine-infused cows. Carnitine infusion increased the concentration of each milk carnitine fraction as well as milk carnitine output on d 8 to 9. On d 13 to 14, all carnitine fractions except short-chain acylcarnitine were increased in milk from water-infused, feed-restricted cows, whereas all fractions were increased in carnitine-infused, feed-restricted cows. Carnitine infusion increased total carnitine in plasma, liver, muscle, and milk during feed restriction, whereas feed restriction alone increased carnitine concentrations in muscle and milk but not in liver. Liver carnitine concentrations might limit hepatic fatty acid oxidation capacity in dairy cows during the periparturient period; therefore, supplemental L-carnitine might decrease liver lipid accumulation in periparturient cows.

Effects of L-carnitine supplementation in pregnant sows on plasma concentrations of insulin-like growth factors, various hormones and metabolites and chorion characteristics

Previous studies have shown that supplementation of sow diets with L-carnitine increases the body weight of piglets at birth. This study was conducted to elucidate the reasons for this phenomenon. Three experiments with 24 (experiment 1), 40 (experiment 2) and 12 (experiment 3) sows were conducted. In all three experiments, sows were allotted to two groups which had free access to a nutritionally adequate diet. Sows of one group were supplemented with 125 mg L-carnitine/day during pregnancy; sows of the other group (control group) did not receive L-carnitine. In experiment 1, plasma samples were collected at day 95 of pregnancy, in experiment 2 plasma samples were collected at days 80 and 100 of pregnancy. In experiment 3, chorions of the sows were collected at parturition. L-carnitine-treated sows had higher plasma concentrations of total L-carnitine than control sows (p < 0.05). The number of piglets born and weights of litter and individual piglets at birth were not different between both groups in all three experiments. L-carnitine-treated sows had higher plasma concentrations of insulin-like growth factor-I (IGF-I) on day 80 of pregnancy (experiment 2, p < 0.05) and on day 95 (experiment 1, p < 0.10), and a higher plasma concentration of IGF-II on day 80 (experiment 2, p < 0.05) than control sows. Moreover, sows supplemented with L-carnitine had heavier chorions (+22%, p =0.10) with greater amounts of protein (+45%, p < 0.05) and DNA (+38%, p < 0.10) and a higher protein concentration of glucose transporter-1 (+62%, p < 0.05). Plasma concentrations of 17beta-oestradiol, progesterone and thyroid hormones as well as concentrations of urea and total free amino acids were not different between both groups of sows. Plasma concentrations of non-esterified fatty acids, ketone bodies, triacylglycerols and cholesterol were also largely indifferent between both groups of sows. In conclusion, this study shows that L-carnitine has less influence on lipid metabolism and utilization of nitrogen in pregnant sows but increases their plasma concentrations of IGFs. This in turn may enhance development of the placentae and the intrauterine nutrition of the fetuses. This may be the reason for increased birth weights observed in recent studies in sows supplemented with L-carnitine.