Hyperinsulinaemia, supplemental protein and branched-chain amino acids when combined can increase milk protein yield in lactating sows

Characterization of simplified nonapeptides with broad-spectrum antimicrobial activities as potential food preservatives, and their antibacterial mechanism

Antimicrobial peptides (AMPs) have attracted attention in the field of food preservatives due to their favorable biosafety and potential antimicrobial activity. However, high synthetic cost, systemic toxicity, a narrow antimicrobial spectrum, and poor antimicrobial activity become the main bottlenecks for their practical applications. To address these questions, a set of derived nonapeptides were designed based on a previously discovered ultra-short peptide sequence template (RXRXRXRXL-NH₂) and screened to identify an optimal peptide-based food preservative with excellent antimicrobial properties. Among these nonapeptides, the designed peptides 3IW (RIRIRIRWL-NH₂) and W2IW (RWRIRIRWL-NH₂) presented a membrane-disruptive and reactive oxygen species (ROS) accumulation mechanism to execute potent and rapid broad-spectrum antimicrobial activity without observed cytotoxicity. Moreover, they exhibited favorable antimicrobial stability regardless of high ionic strength, heat, and excessive acid-base conditions, retaining potent antimicrobial effects for chicken meat preservation. Collectively, their ultra-short sequence length and potent broad-spectrum antimicrobial capacity may be beneficial for the further development of green and safe peptide-based food preservatives.

Dietary supplementation with branched-chain amino acids enhances milk production by lactating sows and the growth of suckling piglets

Background

Under current dietary regimens, milk production by lactating sows is insufficient to sustain the maximal growth of their piglets. As precursors of glutamate and glutamine as well as substrates and activators of protein synthesis, branched-chain amino acids (BCAAs) have great potential for enhancing milk production by sows.

Methods

Thirty multiparous sows were assigned randomly into one of three groups: control (a corn- and soybean meal-based diet), the basal diet + 1.535% BCAAs; and the basal diet + 3.07% BCAAs. The ratio (g/g) among the supplemental L-isoleucine, L-leucine and L-valine was 1.00:2.56:1.23. Diets were made isonitrogenous by the addition of appropriate amounts of L-alanine. Lactating sows had free access to drinking water and their respective diets. The number of live-born piglets was standardized to 9 per sow at d 0 of lactation (the day of parturition). On d 3, 15 and 29 of lactation, body weights and milk consumption of piglets were measured, and blood samples were obtained from sows and piglets 2 h and 1 h after feeding and nursing, respectively.

Results

Feed intake did not differ among the three groups of sows. Concentrations of asparagine, glutamate, glutamine, citrulline, arginine, proline,  BCAAs, and many other amino acids  were greater (P < 0.05) in the plasma of BCAA-supplemented sows and their piglets than those in the control group. Compared with the control, dietary supplementation with 1.535% and 3.07% BCAAs increased (P < 0.05) concentrations of free and protein-bound BCAAs, glutamate plus glutamine, aspartate plus asparagine, and many other amino acids in milk; milk production by 14% and 21%, respectively; daily weight gains of piglets by 19% and 28%, respectively, while reducing preweaning mortality rates by 50% and 70%, respectively.

Conclusion

Dietary supplementation with up to 3.07% BCAAs enhanced milk production by lactating sows, and the growth and survival of their piglets.

Pregnancy and Cancer: Cellular Biology and Mechanisms Affecting the Placenta

Cancer during pregnancy is rarely studied due to its low incidence (1:1000). However, as a result of different sociocultural and economic changes, women are postponing pregnancy, so the number of pregnant women with cancer has been increasing in recent years. The importance of studying cancer during pregnancy is not only based on maternal and foetal prognosis, but also on the evolutionary mechanisms of the cell biology of trophoblasts and neoplastic cells, which point out similarities between and suggest new fields for the study of cancer. Moreover, the magnitude of how cancer factors can affect trophoblastic cells, and vice versa, in altering the foetus's nutrition and health is still a subject to be understood. In this context, the objective of this narrative review was to show that some researchers point out the importance of supplementing branched-chain amino acids, especially leucine, in experimental models of pregnancy associated with women with cancer. A leucine-rich diet may be an interesting strategy to preserve physiological placenta metabolism for protecting the mother and foetus from the harmful effects of cancer during pregnancy.

The role of lactose in weanling pig nutrition: a literature and meta-analysis review

Lactose plays a crucial role in the growth performance of pigs at weaning because it is a palatable and easily digestible energy source that eases the transition from milk to solid feed. However, the digestibility of lactose declines after weaning due to a reduction in endogenous lactase activity in piglets. As a result, some lactose may be fermented in the gastrointestinal tract of pigs. Fermentation of lactose by intestinal microbiota yields lactic acid and volatile fatty acids, which may positively regulate the intestinal environment and microbiome, resulting in improved gastrointestinal health of weanling pigs. We hypothesize that the prebiotic effect of lactose may play a larger role in weanling pig nutrition as the global feed industry strives to reduce antibiotic usage and pharmacological levels of zinc oxide and supra-nutritional levels of copper. Evidence presented in this review indicates that high dietary lactose improves growth performance of piglets, as well as the growth of beneficial bacteria, particularly Lactobacillus, with the positive effects being more pronounced in the first 2 weeks after weaning. However, the risk of post-weaning diarrhea may increase as pigs get older due to reduced lactase activity, high dietary lactose concentrations, and larger feed intakes, all of which may lead to excessive lactose fermentation in the intestine of the pig. Therefore, dietary lactose levels exert different effects on growth performance and gastrointestinal physiological functions in different feeding phases of weanling pigs. However, no formal recommendation of lactose for weanling pigs has been reported. A meta-analysis approach was used to determine that diets fed to swine should include 20%, 15%, and 0 lactose from d 0–7, d 7–14, and d 14–35 post-weaning, respectively. However, sustainable swine production demands that economics must also be taken into account as lactose and lactose containing ingredients are expensive. Therefore, alternatives to lactose, so called “lactose equivalents” have also been studied in an effort to decrease feed cost while maintaining piglet performance with lower dietary lactose inclusions. In summary, the present review investigated dose-response effects of dietary lactose supplementation to exert positive responses and begin to elucidate its mechanisms of action in post-weaning pig diets. The results may help to replace some or all lactose in the diet of weanling pigs, while improving production economics given the high cost of lactose and availability in some swine production markets.

Insulin potentiates essential amino acids effects on mechanistic target of rapamycin complex 1 signaling in MAC-T cells

Different models of lactation offer conflicting evidence as to whether insulin signaling is required for AA to stimulate mechanistic target of rapamycin complex 1 (mTORC1) activity. We hypothesized that insulin potentiates essential AA stimulation of mTORC1 activity in the MAC-T mammary epithelial cell line. Here, our objective was to assess mTORC1 signaling activity in response to insulin and individual or grouped essential AA. Insulin and essential AA concentrations in the treatment medium ranged from normo- to supraphysiological, with insulin at 0, 1, 10, or 100 nmol/L and essential AA at approximately 0, 0.01, 0.05, 0.1, 1, or 3× reference plasma levels. Effects and interaction of insulin and total essential AA were tested in a 3 × 5 factorial design (n = 3 replicates/treatment); insulin and the individual AA Leu, Met, Ile, and Arg were likewise tested in 3 × 4 factorials (n = 4). As the remaining individual AA His, Lys, Phe, Thr, Trp, and Val were expected to not affect mTORC1, these were tested only at the highest insulin level, 100 nmol/L (n = 4). For all of these, linear and quadratic effects of total and individual AA were evaluated. Essential AA were subsequently grouped by their positive (Leu, Met, Ile, Arg, and Thr; TOR-AA) or absent-to-negative effects (His, Lys, Phe, Trp, and Val; NTOR-AA), and tested for interaction in a 2 × 2 factorial design (n = 4), with each AA at its respective 1× plasma level, and insulin held at 100 nmol/L. All experiments consisted of 1 h treatment incubation, followed by Western blotting of cell lysates to measure phosphorylation and abundance of the mTORC1 pathway proteins Akt (Ser473); ribosomal protein S6 kinase p70 (S6K1, Thr389); eukaryotic translation initiation factor 4E-binding protein 1 (4E-BP1, Ser65); and ribosomal protein S6 (S6, Ser240/244). The Akt phosphorylation was overall increased by insulin, with a possible negative interaction with both total essential AA and the individual AA Leu. Total essential AA also increased S6K1 and 4E-BP1 phosphorylation in an insulin-dependent manner. The individual AA Leu, Met, Ile, and Arg increased S6K1 phosphorylation in an insulin-dependent manner. Similarly, Met and Arg increased 4E-BP1 phosphorylation in an insulin-dependent manner. Histidine, Lys, Trp, and Val did not affect S6K1 phosphorylation. However, S6K1 phosphorylation was linearly increased by Thr and quadratically decreased by Phe. Relative to the phosphorylation of S6K1 when cells were incubated with no essential AA, the NTOR-AA group had no effect, whereas the TOR-AA increased phosphorylation to the same degree observed with all 10 essential AA. Overall, we have found that insulin is required for essential AA to stimulate mTORC1 activity in MAC-T cells. In addition, the AA responsible for the bulk of mTORC1 activation in MAC-T are limited to Leu, Met, Ile, Arg, and Thr.

Effect of the valine-to-lysine ratio on the performance of sows and piglets in a hot, humid environment

To determine the effect of the valine-to-lysine (Val: Lys) ratio on the performance of sows and piglets in a hot, humid environment, eleven Large White × Landrace sows (parity 2 or 3) were selected and randomly assigned to 3 groups. The diets contained total dietary Val: Lys ratios of 0.72, 0.87, or 1.01:1. Sows were fed from d 29 prepartum to d 21 postpartum in a hot, humid environment (temperature: 22-31 ℃, relative humidity: 69-96%). The results showed that dietary valine improved the average daily feed intake (ADFI) of the sows in wk3 of the lactation and the average daily gain (ADG) of the piglets from day 7-14 after farrowing. Dietary valine increased the concentrations of lactose in colostrum and immunoglobulin M (IgM) in piglet serum. Additionally, dietary valine affected metabolite and metabolic hormone concentrations. The increase in the ratio of dietary Val: Lys decreased the blood urea nitrogen and increased serum glucose in the sows and increased serum albumin in the piglets. In addition, increasing dietary Val: Lys increased the serum concentration of estradiol-17β in the sows. In conclusion, in a hot, humid environment, dietary valine could improve the performance of sows and piglets by increasing colostrum lactose and serum immunoglobulin concentration in piglets and by influencing serum glucose in sows.

Role of Maternal Dietary Protein and Amino Acids on Fetal Programming, Early Neonatal Development, and Lactation in Swine

Simple Summary

Dietary protein is an important nutrient source for sows, necessary for not only growth and production, but also other physiological functions. Protein limitations in maternal diets have the potential to impair fetal myogenesis, while excess maternal dietary protein appears to only have minor effects on early fetal muscle formation. Effects of maternal protein deficiency on increased fat deposition in porcine neonates is inconsistent with gene expressions in the neonates. Sufficient maternal dietary protein can enhance porcine milk protein and fat concentration. Understanding the function of protein and amino acids in sows and the effects on their offspring can provide rational approaches for the regulation of piglet growth and further improvements in meat quality in the future.

Abstract

Maternal nutrition plays a vital role in fetal development, early development of neonates, and lactation and regulates the lifetime productivity of offspring. During pregnancy, maternal nutrition alters expression of the fetal genome and the development of tissues and organs via fetal programming. After parturition, maternal nutrition continues to regulate growth and development of piglets through maternal milk, which contains carbohydrates, lipids, proteins and oligosaccharides. Thus, deficiencies in maternal nutrition are detrimental to development of piglets, which can lead to inefficient growth and decreased carcass merit. Protein is an important nutritional component for sows, which not only functions in muscle development, but also plays a vital role in embryonic and neonatal development and lactation. Although effects of maternal undernutrition on neonatal development have been widely studied in sows, the function of different maternal dietary protein levels on fetal development, neonatal growth and lactation performance of sows is largely unknown. Determination of the effects and underlying mechanisms of maternal dietary protein levels on development of piglets is vital to the pork industry. Therefore, we summarized recent reports regarding mechanisms of effects of maternal protein levels on regulation of conceptus growth and early postnatal development though uterine fetal programming and lactation in swine.

Metabolic reconstructions identify plant 3-methylglutaconyl-CoA hydratase that is crucial for branched-chain amino acid catabolism in mitochondria

The proteinogenic branched-chain amino acids (BCAAs) leucine, isoleucine and valine are essential nutrients for mammals. In plants, BCAAs double as alternative energy sources when carbohydrates become limiting, the catabolism of BCAAs providing electrons to the respiratory chain and intermediates to the tricarboxylic acid cycle. Yet, the actual architecture of the degradation pathways of BCAAs is not well understood. In this study, gene network modeling in Arabidopsis and rice, and plant-prokaryote comparative genomics detected candidates for 3-methylglutaconyl-CoA hydratase (4.2.1.18), one of the missing plant enzymes of leucine catabolism. Alignments of these protein candidates sampled from various spermatophytes revealed non-homologous N-terminal extensions that are lacking in their bacterial counterparts, and green fluorescent protein-fusion experiments demonstrated that the Arabidopsis protein, product of gene At4g16800, is targeted to mitochondria. Recombinant At4g16800 catalyzed the dehydration of 3-hydroxymethylglutaryl-CoA into 3-methylglutaconyl-CoA, and displayed kinetic features similar to those of its prokaryotic homolog. When at4g16800 knockout plants were subjected to dark-induced carbon starvation, their rosette leaves displayed accelerated senescence as compared with control plants, and this phenotype was paralleled by a marked increase in the accumulation of free and total leucine, isoleucine and valine. The seeds of the at4g16800 mutant showed a similar accumulation of free BCAAs. These data suggest that 3-methylglutaconyl-CoA hydratase is not solely involved in the degradation of leucine, but is also a significant contributor to that of isoleucine and valine. Furthermore, evidence is shown that unlike the situation observed in Trypanosomatidae, leucine catabolism does not contribute to the formation of the terpenoid precursor mevalonate.

Novel metabolic and physiological functions of branched chain amino acids: a review

It is widely known that branched chain amino acids (BCAA) are not only elementary components for building muscle tissue but also participate in increasing protein synthesis in animals and humans. BCAA (isoleucine, leucine and valine) regulate many key signaling pathways, the most classic of which is the activation of the mTOR signaling pathway. This signaling pathway connects many diverse physiological and metabolic roles. Recent years have witnessed many striking developments in determining the novel functions of BCAA including: (1) Insufficient or excessive levels of BCAA in the diet enhances lipolysis. (2) BCAA, especially isoleucine, play a major role in enhancing glucose consumption and utilization by up-regulating intestinal and muscular glucose transporters. (3) Supplementation of leucine in the diet enhances meat quality in finishing pigs. (4) BCAA are beneficial for mammary health, milk quality and embryo growth. (5) BCAA enhance intestinal development, intestinal amino acid transportation and mucin production. (6) BCAA participate in up-regulating innate and adaptive immune responses. In addition, abnormally elevated BCAA levels in the blood (decreased BCAA catabolism) are a good biomarker for the early detection of obesity, diabetes and other metabolic diseases. This review will provide some insights into these novel metabolic and physiological functions of BCAA.

The effect of increasing the dietary valine-to-lysine ratio on sow metabolism, milk production, and litter growth

A study was conducted to investigate the effect of increasing the dietary valine-to-lysine ratio (Val:Lys) for lactating sows weaning more than 12 piglets. Five hundred fifty-eight sows (parity 1 to 4) were allotted to 6 dietary treatments from 2 d postpartum, when litters were standardized to 14 piglets. Diets were analyzed to have a total dietary Val:Lys of 0.84, 0.86, 0.88, 0.90, 0.95, or 0.99:1. On all 558 sows, BW, back fat thickness (BF), and litter weight were registered at d 108 of gestation and d 2 and 25 (weaning) postpartum. On a subsample of 72 sows, additional measurements were made: sow BW and BF were measured on d 17 and litter weight was measured on d 10 and 17, and blood and urine samples were collected weekly. The litter size at weaning was not affected by the dietary Val:Lys ( = 0.23) and, on average, the sows weaned 13.0 ± 1.1 piglets. Average daily gain of the litter (2.93 ± 0.53 kg/d; = 0.84), litter weight at weaning ( = 0.67), the average milk yield (11.3 ± 1.4 kg/d; = 0.49), and milk contents of fat ( = 0.57), protein ( = 0.18), and lactose ( = 0.20) were not affected by the dietary Val:Lys. Increasing the dietary Val:Lys increased the milk concentration of Val ( < 0.05) and Ile ( < 0.01). The change in sow BW and BF were similar for all sows from d 2 to 17, d 17 to 25, and d 2 to 25 ( > 0.05). During lactation, sows, on average, had a BW and back fat loss of 22.1 ± 12.7 kg and 2.9 ± 1.7 mm, respectively. Plasma concentrations of glucose ( = 0.26), lactate ( = 0.95), urea N ( = 0.84), NEFA ( = 0.24), and creatinine ( = 0.42); urine concentration of creatinine ( = 0.57); and concentrations of AA in whole blood ( > 0.05) were not affected by the dietary Val:Lys. In conclusion, there was no effect of increasing the total dietary Val:Lys above 0.84:1 on sow metabolism and litter performance during lactation.

Invited review: An evaluation of the likely effects of individualized feeding of concentrate supplements to pasture-based dairy cows

In pasture-based dairy systems, supplementary feeds are used to increase dry matter intake and milk production. Historically, supplementation involved the provision of the same amount of feed (usually a grain-based concentrate feed) to each cow in the herd during milking (i.e., flat-rate feeding). The increasing availability of computerized feeding and milk monitoring technology in milking parlors, however, has led to increased interest in the potential benefits of feeding individual cows (i.e., individualized or differential feeding) different amounts and types of supplements according to one or more parameters (e.g., breeding value for milk yield, current milk yield, days in milk, body condition score, reproduction status, parity). In this review, we consider the likely benefits of individualized supplementary feeding strategies for pasture-based dairy cows fed supplements in the bail during milking. A unique feature of our review compared with earlier publications is the focus on individualized feeding strategies under practical grazing management. Previous reviews focused primarily on research undertaken in situations where cows were offered ad libitum forage, whereas we consider the likely benefits of individualized supplementary feeding strategies under rotational grazing management, wherein pasture is often restricted to all or part of a herd. The review provides compelling evidence that between-cow differences in response to concentrate supplements support the concept of individualized supplementary feeding.

Dairy proteins and the regulation of satiety and obesity

Over the past decade there has been growing scientific evidence and public acceptance of the role that dietary protein plays in regulation of satiety, feed intake and obesity-related disorders. Dietary protein appears to suppress food intake and delay the return of hunger more than fats or carbohydrates in a manner not due to energy content alone. Also, high-protein diets support the maintenance of muscle mass when subjects reduce their energy intake, ensuring primarily adipose tissue loss. Some protein sources, particularly dairy, contain specific peptides or proteins that may elicit direct effects on satiety. The major proteins present in milk include β-lactalbumin, α-lactoglobulin, immunoglobulins, bovine serum albumin, and the various caseins. In addition, processed whey contains glycomacropeptide, which stimulates pancreatic and gastrointestinal secretion of hormones involved in satiety to a greater extent than whey alone. In the context of the literature, we show that a glycomacropeptide-rich whey protein isolate decreases feed intake and weight gain to a greater extent than a soy protein isolate in obese pigs. Also, insulin sensitivity is improved in pigs consuming high-protein diets, with these effects being independent of protein source. While, high-protein diets may decrease calcium balance and bone strength, it appears that these effects are attenuated by dairy proteins and dairy sources of calcium. These findings suggest that high-protein diets, and in particular those that contain whey proteins, may reduce hunger and food intake, thereby reducing fat deposition and improving insulin sensitivity.