Etiology of lipid-related metabolic disorders in periparturient dairy cows

Food intake regulation in late pregnancy and early lactation

The dip in food intake, which starts in late pregnancy and continues into early lactation, has traditionally been interpreted as a depression in intake due to physical constraints. However, the rôle of physical constraints on intake has been overemphasized, particularly in early lactation. There is mounting evidence that the presence and mobilization of body reserves in early lactation play an important rôle in regulating intake at this time.

Conceptually, the dip in intake in early lactation observed when cows have access to non-limiting foods can be accounted for by assuming that the cow has a desired level of body reserves. When the cow is not compromised, the changes with time in body reserves and the dip in intake represent the normal case and provide the basis against which to assess true depressions in intake which may occur when the cow is compromised by limiting nutrition or environment.

The regulation of body reserves and intake in the periparturient cow is orchestrated through nervous and hormonal signals. Likely factors that are involved in intake regulation are reproductive hormones, neuropeptides, adrenergic signals, insulin and insulin resistance and leptin. Furthermore, oxidation of NEFA in the liver may result in feedback signals that reduce intake. The relative importance of these is discussed. A better understanding of the physiological signals involved in intake regulation and their interrelations with body weight regulation may provide important indicators of the degree of compromise that periparturient cows may experience.

Supplementation of glycerol or fructose via drinking water to grazing lambs on tissue glycogen level and lipogenesis

Lambs ( = 18; 40.1 ± 7.4 kg BW) were used to assess supplementation of glycerol or fructose via drinking water on growth, tissue glycogen levels, postmortem glycolysis, and lipogenesis. Lambs were blocked by BW and allocated to alfalfa paddocks (2 lambs/paddock and 3 paddocks/treatment). Each paddock within a block was assigned randomly to drinking water treatments for 30 d: 1) control (CON), 2) 120 g fructose/L of drinking water (FRU), or 3) 120 g glycerol/L of drinking water (GLY). Lambs grazed alfalfa with free access to water treatments for 28 d and then were fasted in indoor pens for a final 2 d with access to only water treatments. Data were analyzed using the MIXED procedure of SAS with water treatment and time (when appropriate) in the model. During the 28-d grazing period, ADG was greater ( < 0.05) for GLY than for CON or FRU. During the 2-d fasting period, BW shrink was lower ( < 0.05) for GLY compared with CON or FRU. Hot carcass weight was greater ( < 0.05) for GLY than for FRU. The interaction for glycogen content × postmortem time was significant ( = 0.003) in LM and semitendinosus (ST) muscles. Glycogen content in the LM was greater ( < 0.05) for GLY at 2 and 3 h and for FRU at 1 h postmortem compared with CON. Glycogen content in ST did not differ between treatments ( > 0.05). Liver glycogen content was over 14-fold greater ( < 0.05) for GLY compared with FRU or CON. Liver free glucose was greater ( < 0.05) for GLY than for CON, whereas liver lipid content was higher ( < 0.05) for CON than for GLY. Supplementation with GLY increased ( < 0.05) odd-chain fatty acids in LM, subcutaneous fat (SQ), and the liver. Stearic acid (C18:0) concentrations were reduced in LM ( = 0.064) and subcutaneous adipose tissue (SQ; = 0.018), whereas oleic acid (C18:1 -9) concentration tended to be increased ( = 0.066) in SQ with FRU and GLY. Linolenic acid (C18:3 -3) was reduced ( = 0.031) and all long-chain -3 fatty acid (eicosapentaenoic acid, docosapentaenoic acid, and docosahexaenoic acid) concentrations were increased ( < 0.05) with FRU and GLY compared with CON. Glycerol supplementation upregulated ( < 0.05) stearoyl-CoA desaturate () and fatty acid synthase () mRNA by over 40-fold in the SQ and 5-fold in the liver. Glycerol supplementation also upregulated ( < 0.05) glucose transporters and glycogen branching enzyme in the liver. Overall, glycerol supplementation improved growth, reduced BW shrink during fasting, increased glycogen content in muscle and the liver, and stimulated de novo lipogenesis.

Essential role of methyl donors in animal productivity

Dietary requirements for the methyl donors, choline, betaine and folate, in livestock species are poorly defined and have not been included in diet formulation software or simulation models for animals. A deficiency of methyl donors may promote an inflammatory state, which is significant for the livestock industry because chronic low-grade inflammation is widespread among livestock under commercial conditions. Furthermore, recent evidence showing that methyl donors activate adenosine monophosphate-activated protein kinase, an anti-inflammatory master switch, indicates that dietary methyl-donor supplementation could be used to prevent or ameliorate chronic inflammation and its sequelae in livestock, which include fatty liver disease in dairy cows, fatty liver and kidney syndrome in broilers, fatty liver haemorrhagic syndrome in layers, gut ulcers in pigs, liver abscesses in feedlot cattle, enteritis in poultry and susceptibility to heat stress in all species. Because of the complexity of interactions among methyl donors, a modelling approach inclusive of a supporting research effort will be required to harness the potential of methyl-donor supplementation in livestock production.

Relative bioavailability of carnitine delivered by ruminal or abomasal infusion or by encapsulation in dairy cattle

Two studies were designed to evaluate the relative bioavailability of l-carnitine delivered by different methods in dairy cattle. In experiment 1, 4 Holstein heifers were used in a split-plot design to compare ruminally or abomasally infused l-carnitine. The study included 2 main-plot periods, with infusion routes allocated in a crossover design. Within main-plot periods, each of 3 subplot periods consisted of 4-d infusions separated with 4-d rest periods. Subplot treatments were infusion of 1, 3, and 6 g of l-carnitine/d in conjunction with 6 g/d of arabinogalactan given in consideration of eventual product manufacturing. Doses increased within a period to minimize carryover risk. Treatments were solubilized in 4 L of water and delivered in two 10-h infusions daily. Blood was collected before the start of infusion period and on d 4 of each infusion period to obtain baseline and treatment l-carnitine concentrations. There was a dose × route interaction and route effect for increases in plasma carnitine above baseline, with increases above baseline being greater across all dose levels when infused abomasally compared with ruminally. Results demonstrated superior relative bioavailability of l-carnitine when ruminal exposure was physically bypassed. In experiment 2, 56 lactating Holstein cows (143 ± 72 d in milk) were used in 2 cohorts in randomized complete block designs (blocked by parity and milk production) to evaluate 2 rumen-protected products compared with crystalline l-carnitine. Treatments were (1) control, (2) 3 g/d of crystalline l-carnitine (crystalline), (3) 6 g/d of crystalline, (4) 5 g/d of 40COAT (40% coating, 60% l-carnitine), (5) 10 g/d of 40COAT, (6) 7.5 g/d of 60COAT (60% coating, 40% l-carnitine), and (7) 15 g/d of 60COAT. Treatments were top-dressed to diets twice daily. Each cohort used 14-d and included a 6-d baseline measurement period with the final 2 d used for data and sample collection, and an 8-d treatment period with the final 2 d used for data and sample collection. Plasma, urine, and milk samples were analyzed for l-carnitine. Crystalline and 40COAT linearly increased plasma l-carnitine, and 60COAT tended to linearly increase plasma l-carnitine. Total excretion (milk + urine) of l-carnitine averaged 1.52 ± 0.04 g/d in controls, increased linearly with crystalline and 40COAT, and increased quadratically with 60COAT. Crystalline increased plasma l-carnitine and l-carnitine excretion more than 40COAT and 60COAT. In conclusion, preventing ruminal degradation of l-carnitine increased delivery of bioavailable carnitine to cattle, but effective ruminal protection and postruminal bioavailability is challenging.

Assessment of the innate immune response in the periparturient cow

The transition period is the most critical phase in the life of high yielding dairy cows. Within a few weeks, cows are submitted to many challenges (physiological, nutritional, psychological, management) that require prompt and effective adaptive responses. The immune system is involved in this process, and many changes of the cow's immune system components have been observed around calving. Cows are considered to be immunosuppressed in late lactation, and available data suggest that the immune system is dysregulated around parturition. Significant attention has been focused on modification of cellular functions (e.g. the reduction of phagocytosis and diapedesis), but growing interest concerns the components of the innate immune system, which often exhibits increased responses such as susceptibility to inflammatory events and the related acute phase response (APR). Systemic inflammation plays a significant role in early lactation, affects many liver functions and has been associated with the impairment of cow performance (i.e. reduced feed intake, milk yield, fertility, welfare). The assessment of variations in immune-metabolic indices offers opportunities to predict the onset of the health troubles and to anticipate the proper therapies needed to guarantee health, good welfare and fertility in the following lactation. The frequency of diseases (metabolic and infectious) before calving is rare, but several clues suggest that various metabolic and immune variations can begin during the dry period. Interesting preliminary results encourage this perspective and possible candidates are suggested.

Considering choline as methionine precursor, lipoproteins transporter, hepatic promoter and antioxidant agent in dairy cows

During the transition period, fatty liver syndrome may be caused in cows undergo negative energy balance, ketosis or hypocalcemia, retained placenta or mastitis problems. During the transition stage, movement of non-esterified fatty acids (NEFA) increases into blood which declines the hepatic metabolism or reproduction and consequently, lactation performance of dairy cows deteriorates. Most of studies documented that, choline is an essential nutrient which plays a key role to decrease fatty liver, NEFA proportion, improve synthesis of phosphatidylcholine, maintain lactation or physiological function and work as anti-oxidant in the transition period of dairy cows. Also, it has a role in the regulation of homocysteine absorption through betaine metabolite which significantly improves plasma α-tocopherol and interaction among choline, methionine and vitamin E. Many studies reported that, supplementation of rumen protected form of choline during transition time is a sustainable method as rumen protected choline (RPC) perform diverse functions like, increase glucose level or energy balance, fertility or milk production, methyl group metabolism, or signaling of cell methionine expansion or methylation reactions, neurotransmitter synthesis or betaine methylation, increase transport of lipids or lipoproteins efficiency and reduce NEFA or triacylglycerol, clinical or sub clinical mastitis and general morbidity in the transition dairy cows. The purpose of this review is that to elucidate the choline importance and functions in the transition period of dairy cows and deal all morbidity during transition or lactation period. Furthermore, further work is needed to conduct more studies on RPC requirements in dairy cows ration under different feeding conditions and also to elucidate the genetic and molecular mechanisms of choline in ruminants industry.

Metabolic and immunological changes in transition dairy cows: A review

Smooth transition from pregnancy to lactation is important for high productive and reproductive performance during later postpartum period in dairy animals. On the other hand, the poor transition often leads to huge economic loss to dairy farmers due to compromised production and reproduction. Therefore, understanding the causes and consequence of metabolic changes during the transition period is very important for postpartum health management. In this review, metabolic changes with reference to negative energy balance in transition cow and its effect on health and reproduction during the later postpartum period in dairy animals are discussed besides the role of metabolic inflammation in postpartum performance in dairy animals.

Effects of niacin supplementation on the insulin resistance in Holstein cows during early lactation

Insulin resistance in early lactation includes low glucose concentration, low insulin release and responsiveness and high lipolysis. Niacin is important antilipolytic agent and leads to increase glucose and insulin concentration. The objectives of this study were to determine the influence of niacin on the insulin resistance in cows during early lactation using the difference of value and regression analysis between blood non-esterified fatty acid (NEFA), glucose and insulin concentrations, revised quantitative insulin sensitivity check index and glucose-to-insulin ratio. Niacin supplementation led to a decrease of NEFA concentration and an increase of glucose and insulin concentrations during the first three weeks after calving. Cows in the niacin group which were more resistant to insulin showed higher concentrations of non-esterified fatty acid in comparison with more sensitive cows from the same group, but still lower than the control. The regression analyses suggest the following characteristics of cows supplemented with niacin in comparison with the control group: the insulin response to glucose was more intense; the antilipolytic effect of insulin was lower; insulin efficiency expressed as glucose-to-insulin ratio increase with a decrease in NEFA. The metabolic changes due to niacin supplementation showed a dual influence on the insulin resistance in dairy cows during early lactation: decreased NEFA concentrations led to a decrease in the insulin resistance (due to an increase in insulin efficiency and insulin sensitivity index), but increased concentrations of insulin and glucose possibly caused an increase in the insulin resistance in dairy cows (due to lower insulin sensitivity index and possibly lower antilipolytic effects of insulin).

Disturbed bovine mitochondrial lipid metabolism: a review

In mammals, excess energy is stored primarily as triglycerides, which are mobilized when energy demands arise and cannot be covered by feed intake. This review mainly focuses on the role of long chain fatty acids in disturbed energy metabolism of the bovine species. Long chain fatty acids regulate energy metabolism as ligands of peroxisome proliferator-activated receptors. Carnitine acts as a carrier of fatty acyl groups as long-chain acyl-CoA derivatives do not penetrate the mitochondrial inner membrane. There are two different types of disorders in lipid metabolism which can occur in cattle, namely the hypoglycaemic-hypoinsulinaemic and the hyperglycaemic-hyperinsulinaemic type with the latter not always associated with ketosis. There is general agreement that fatty acid β-oxidation capability is limited in the liver of (ketotic) cows. In accord, supplemental L-carnitine decreased liver lipid accumulation in periparturient Holstein cows. Of note, around parturition concurrent oxidation of fatty acids in skeletal muscle is highly activated. Also peroxisomal β-oxidation in liver of dairy cows may be part of the hepatic adaptations to a negative energy balance (NEB) to break down fatty acids. An elevated blood concentration of nonesterified fatty acids is one of the indicators of NEB in cattle among others like increased β-hydroxy butyrate concentration, and decreased concentrations of glucose, insulin, and insulin-like growth factor-I. Assuming that liver carnitine concentrations might limit hepatic fatty acid oxidation capacity in dairy cows, further study of the role of acyl-CoA dehydrogenases and/or riboflavin in bovine ketosis is warranted.

Proteomics and metabolomics characterizing the pathophysiology of adaptive reactions to the metabolic challenges during the transition from late pregnancy to early lactation in dairy cows

The transition from late pregnancy to early lactation is a critical period in a dairy cow's life due to the rapidly increasing drain of nutrients from the maternal organism towards the foetus and into colostrum and milk. In order to cope with the challenges of parturition and lactation, comprehensive adaptive reactions comprising the endocrine and the immune system need to be accomplished. There is high variation in this coping ability and both metabolic and infectious diseases, summarized as "production diseases", such as hypocalcaemia (milk fever), fatty liver syndrome, laminitis and ketosis, may occur and impact welfare, productive lifespan and economic outcomes. Proteomics and metabolomics have emerged as valuable techniques to characterize proteins and metabolite assets from tissue and biological fluids, such as milk, blood and urine. In this review we provide an overview on metabolic status and physiological changes during the transition period and the related production diseases in dairy cows, and summarize the state of art on proteomics and metabolomics of biological fluids and tissues involved in metabolic stress during the peripartum period. We also provide a current and prospective view of the application of the recent achievements generated by omics for biomarker discovery and their potential in diagnosis.

BIOLOGICAL SIGNIFICANCE

For high-yielding dairy cows there are several "occupational diseases" that occur mainly during the metabolic challenges related to the transition from pregnancy to lactation. Such diseases and their sequelae form a major concern for dairy production, and often lead to early culling of animals. Beside the economical perspective, metabolic stress may severely influence animal welfare. There is a multitude of studies about the metabolic backgrounds of such so called production diseases like ketosis, fatty liver, or hypocalcaemia, although the investigations aiming to assess the complexity of the pathophysiological reactions are largely focused on gene expression, i.e. transcriptomics. For extending the knowledge towards the proteome and the metabolome, the respective technologies are of increasing importance and can provide an overall view of how dairy cows react to metabolic stress, which is needed for an in-depth understanding of the molecular mechanisms of the related diseases. We herein review the current findings from studies applying proteomics and metabolomics to transition-related diseases, including fatty liver, ketosis, endometritis, hypocalcaemia and laminitis. For each disease, a brief overview of the up to date knowledge about its pathogenesis is provided, followed by an insight into the most recent achievements on the proteome and metabolome of tissues and biological fluids, such as blood serum and urine, highlighting potential biomarkers. We believe that this review would help readers to be become more familiar with the recent progresses of molecular background of transition-related diseases thus encouraging research in this field.

Expression of hepatic genes related to energy metabolism during the transition period of Holstein and F1 Holstein-Gir cows

The aim of this study was to investigate the expression of genes encoding enzymes and other factors involved with carbohydrate and lipid metabolism in the liver of 2 genetic groups of dairy cows during the transition period. We analyzed the expression of glucose-6-phosphatase (G6PC), cytosolic phosphoenolpyruvate carboxykinase (PEPCK-C), methylmalonyl-CoA mutase (MUT), β-hydroxybutyrate dehydrogenase-2 (BDH2), acetyl-CoA carboxylase (ACC), carnitine palmitoyltransferase-2 (CPT2), 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR), glucose transporter-2 (SLC2A2), and the transcription factor peroxisome proliferator-activated receptor α (PPARA). Blood concentrations of glucose, nonesterified fatty acids, and β-hydroxybutyrate were also determined. Liver biopsies and blood samples were taken at d 15 prepartum and at d 6, 21, 36, 51, and 66 postpartum from Holsteins (n = 6) and F₁ Holstein-Gir (n = 6) cows. Cows were kept under the same prepartum and postpartum management conditions. The results showed that the expression of G6PC, PEPCK-C, BDH2, ACC, CPT2, HMGCR, SLC2A2, and PPARA genes did not differ between genetic groups. Except for PEPCK-C, no interaction between genetic groups and the experimental period was observed. Within both groups of cows, G6PC and PEPCK-C gene expression decreased when comparing prepartum gene expression with 21 and 36 DIM, and increased in d 51 postpartum. MUT mRNA levels differed between the 2 genetic groups and displayed a significant increase after d 36 postpartum, whereas mRNA levels of HMGCR tended to increase when comparing d 21 and 36 to d 51 postpartum. Glucose concentrations also differed between genetic groups, being significantly higher in the plasma of F₁ Holstein-Gir cows than in Holstein cows, but no differences were found within each group during the analysis period. β-Hydroxybutyrate and nonesterified fatty acid concentrations did not differ between genetic groups, but displayed increased levels from prepartum to d 6 and 21 postpartum. Our results indicated that expression in the liver of genes involved with glucose and fatty acid metabolism were similar in both groups of cows and significant differences were observed between the 2 groups in the expression of MUT, a gene involved in propionate metabolism.

Linoleic acid, α-linolenic acid and enterolactone affect lipid oxidation and expression of lipid metabolism and antioxidant-related genes in hepatic tissue of dairy cows

Although beneficial effects have been attributed to PUFA supplementation in high-yielding dairy cows, diets rich in PUFA may also increase oxidative stress in tissues such as the liver. To fully exploit the health benefits of PUFA, we believe that the addition of natural antioxidants could help in preventing oxidative damage. Using an in vitro precision-cut liver slices (PCLS) tissue culture system, we investigated the effects of different linoleic acid (LA, n-6):α-linolenic acid (ALA, n-3) ratios (LA:ALA ratio of 4, LA:ALA ratio of 15 and LA:ALA ratio of 25) in the presence or absence of the antioxidant enterolactone (ENL) on (1) the mRNA abundance of genes with key roles in hepatic lipid metabolism, oxidative stress response and inflammatory processes, (2) oxidative damages to lipids and proteins and (3) superoxide dismutase activity in early-lactating dairy cows. The addition of LA and ALA to PCLS culture media increased oxidative damage to lipids as suggested by higher concentrations of thiobarbituric acid reactive substances and increased the expression of nuclear factor erythroid 2-related factor 2 target genes. The addition of ENL was effective in preventing lipid peroxidation caused by LA and ALA. Transcript abundance of sterol regulatory element-binding transcription factor 1 and its lipogenic target genes acetyl-CoA carboxylase α, fatty acid synthase (FASN) and stearoyl-CoA desaturase (SCD) was decreased with LA and ALA, whereas ENL decreased FASN and SCD gene expression. Our results show that addition of LA and ALA to PCLS culture media lowers hepatic lipogenic gene expression and increases oxidative damages to lipids. On the other hand, addition of ENL prevents oxidative damages provoked by these PUFA.

Insulin signalling and glucose transport in the ovary and ovarian function during the ovarian cycle

Data derived principally from peripheral tissues (fat, muscle and liver) show that insulin signals via diverse interconnecting intracellular pathways and that some of the major intersecting points (known as critical nodes) are the IRSs (insulin receptor substrates), PI3K (phosphoinositide kinase)/Akt and MAPK (mitogen-activated protein kinase). Most of these insulin pathways are probably also active in the ovary and their ability to interact with each other and also with follicle-stimulating hormone (FSH) and luteinizing hormone (LH) signalling pathways enables insulin to exert direct modulating influences on ovarian function. The present paper reviews the intracellular actions of insulin and the uptake of glucose by ovarian tissues (granulosa, theca and oocyte) during the oestrous/menstrual cycle of some rodent, primate and ruminant species. Insulin signals through diverse pathways and these are discussed with specific reference to follicular cell types (granulosa, theca and oocyte). The signalling pathways for FSH in granulosa cells and LH in granulosa and theca cells are summarized. The roles of glucose and of insulin-mediated uptake of glucose in folliculogenesis are discussed. It is suggested that glucose in addition to its well-established role of providing energy for cellular function may also have insulin-mediated signalling functions in ovarian cells, involving AMPK (AMP-dependent protein kinase) and/or hexosamine. Potential interactions of insulin signalling with FSH or LH signalling at critical nodes are identified and the available evidence for such interactions in ovarian cells is discussed. Finally the action of the insulin-sensitizing drugs metformin and the thiazolidinedione rosiglitazone on follicular cells is reviewed.

Thyroid Hormones, Insulin, Body Fat, and Blood Biochemistry Indices in Dairy Cows During the Reproduction/Production Cycle

This study investigated the changes in: thyroid hormones, amount of subcutaneous fat, and selected indices of blood biochemistry in dairy cows in relation to the reproduction/production cycle. The blood samples were collected both ante- and post-partum every two weeks. When evaluating the mean values of the investigated indices, the major changes were recorded in dairy cows 3 to 14 days after calving. During this period, we observed a significant decrease in the mean serum levels of T3 (P < 0.05), T4 (P < 0.01), and triglycerides (P < 0.01). An opposite trend was observed with a significant increase after calving in the: mean serum levels of β-hydroxybutyrate (P < 0.05), urea (P < 0.01), and mean AST activities (P < 0.05). A significant increase over the normal range was recorded in the average levels of non-esterified fatty acids (P < 0.01) and total bilirubin (P < 0.01). From the next sampling (28 days after calving) onwards we recorded a significant increase in the blood serum levels of cholesterol (P < 0.01), total lipids (P < 0.01), total protein (P < 0.01), as well as a significant decrease in the insulin levels (P < 0.05) and a reduced layer of subcutaneous fat (P < 0.01). The blood serum iodine concentration showed only slight significant changes (P < 0.05) during the observation. Blood serum levels of glucose did not show any significant changes during the whole observation period. Within the whole observation period we found a negative correlation between T3 levels and the layer of subcutaneous fat (r = −0.2606; P < 0.05). This correlation was much more marked in cows 3 to 14 days after calving (r = −0.5077; P < 0.05), which may indicate a possible relationships between the thyroid status, body condition, and post partum negative energy balance.

Choline and methionine differentially alter methyl carbon metabolism in bovine neonatal hepatocytes

Intersections in hepatic methyl group metabolism pathways highlights potential competition or compensation of methyl donors. The objective of this experiment was to examine the expression of genes related to methyl group transfer and lipid metabolism in response to increasing concentrations of choline chloride (CC) and DL-methionine (DLM) in primary neonatal hepatocytes that were or were not exposed to fatty acids (FA). Primary hepatocytes isolated from 4 neonatal Holstein calves were maintained as monolayer cultures for 24 h before treatment with CC (61, 128, 2028, and 4528 μmol/L) and DLM (16, 30, 100, 300 μmol/L), with or without a 1 mmol/L FA cocktail in a factorial arrangement. After 24 h of treatment, media was collected for quantification of reactive oxygen species (ROS) and very low-density lipoprotein (VLDL), and cell lysates were collected for quantification of gene expression. No interactions were detected between CC, DLM, or FA. Both CC and DLM decreased the expression of methionine adenosyltransferase 1A (MAT1A). Increasing CC did not alter betaine-homocysteine S-methyltranferase (BHMT) but did increase 5-methyltetrahydrofolate-homocysteine methyltransferase (MTR) and methylenetetrahydrofolate reductase (MTHFR) expression. Increasing DLM decreased expression of BHMT and MTR, but did not affect MTHFR. Expression of both phosphatidylethanolamine N-methyltransferase (PEMT) and microsomal triglyceride transfer protein (MTTP) were decreased by increasing CC and DLM, while carnitine palmitoyltransferase 1A (CPT1A) was unaffected by either. Treatment with FA decreased the expression of MAT1A, MTR, MTHFR and tended to decrease PEMT but did not affect BHMT and MTTP. Treatment with FA increased CPT1A expression. Increasing CC increased secretion of VLDL and decreased the accumulation of ROS in media. Within neonatal bovine hepatocytes, choline and methionine differentially regulate methyl carbon pathways and suggest that choline may play a critical role in donating methyl groups to support methionine regeneration. Stimulating VLDL export and decreasing ROS accumulation suggests that increasing CC is hepato-protective.

Niacin feeding to fresh dairy cows: immediate effects on health and milk production

Early lactation dairy cows are frequently in negative energy balance and susceptible to ketosis, fatty liver and metritis. Because of its anti-lipolytic properties, the B-vitamin niacin could reduce negative energy balance by reducing non-esterified fatty acids for ketogenesis, thereby reducing hyperketonemia. We determined effects of feeding ruminally protected niacin (RPNi) on lipolysis during the fresh period using blood non-esterified fatty acids concentrations as a ketosis indicator, blood β-hydroxybutyrate concentrations as an indicator of lipid mobilisation, as well as dry matter (DM) intake, milk and milk component yields, in 906 multi-parity Holstein cows from ~14 days before calving through the immediate fresh period. Prior to calving, cows were co-mingled in one pen and fed the same total mixed ration without RPNi. Between 24 and 36 h postpartum, cows were assigned to fresh pens and fed the same fresh cow total mixed ration, except for RPNi at 0, 3.5, 7 or 14 g niacin/cow.day. During the close-up and fresh periods, cows were sampled for tail vein blood. Milk yield and composition was measured twice at a 140-days interval in the fresh pens postpartum. The 3.5 g/day RPNi feeding tended to decrease ketosis prevalence (% of cows with β-hydroxybutyrate ≥ 1.44 mg/dL) from 36% to 20% (P = 0.06) and also tended (P = 0.07) to increase DM intake from 19.3 to 21.5 kg DM/day versus Control. The RPNi effect tended to increase with duration of RPNi feeding, with no effects at 7 ± 3.9 days in milk, but milk (P = 0.10), milk fat (P = 0.11) and milk energy (P = 0.07) yields tending to be higher at 21 ± 3.9 days in milk. Conversely, 14 g/day RPNi had no effect on ketosis prevalence or DM intake. However, milk (P = 0.10), milk fat (P = 0.11) and milk energy (P = 0.07) yields tended to decrease versus Control. Overall, low level RPNi feeding was judged to improve health and production in fresh cows, but higher feeding levels had clear negative impacts.

Lactational challenges in transition dairy cows

Lactation evolved to be the core functional system of providing maternal care in mammalian species. The mammary gland provides an ideally composed nutrient source for the newborn. In addition, colostrum provides passive immunisation after birth, and each suckling process supports the establishment and maintenance of a close mother–offspring bonding. The importance of lactation for the survival of the offspring is represented by a high metabolic priority of the mammary gland within the organism of the lactating animal. Therefore, animal breeding for high milk production has been quite successful, and modern breeding methods have allowed an enormous increase in the performance within only few generations of cows. Mainly in early lactation, most of the available nutrients are directed to the mammary gland, both those from feed, and those mobilised from body tissue. Therefore, milk production can be maintained at a high level despite a negative energy balance. However, the high metabolic load and mobilisation of body tissue requires adequate endocrine and metabolic regulation, which can be successful or less successful in individual animals, i.e. the dairy cow population consists of both metabolically robust and metabolically vulnerable dairy cows. While robust animals adapt adequately, vulnerable cows show often high plasma concentrations of non-esterified fatty acids and β-hydroxybutyrate, and are prone to various production-related diseases. In pasture- or forage-based feeding systems, an additional challenge is a limited availability of nutrients for milk production. Forage feeding without complementary concentrate leads to enormous metabolic disorders in high-yielding cows, but is tolerated in dairy cows with a moderate genetic-performance level.

Altered plasma lipidome profile of dairy cows with fatty liver disease

Fatty liver disease is a common health problem of dairy cows occurring during the transition from pregnancy to lactation. It is a direct response to fat mobilization due to negative energy balance. Accumulation of lipids in the liver occurs if the uptake of non-esterified fatty acids by the liver exceeds the capacity of lipid oxidation or secretion by the liver. Currently, the diagnosis of fatty liver disease requires confirmation through biopsies to determine the hepatic lipid content. In view of this lack of a practical diagnostic tool, we compared the plasma lipidome of diseased dairy cows using liquid chromatography coupled to quadrupole time-of-flight mass spectrometry. Multivariate data analysis yielded 20 m/z values that were able to distinguish between dairy cows with no hepatic lipidosis and those exhibiting different stages of the disease. Based on the chromatography retention time and m/z ratios, we identified phosphatidylcholines with reduced plasma abundances in cows with fatty liver disease. The abundances of different bile acids tended to be increased. In addition, we detected two metabolites related to inflammation, resolvin E1 and palmitoyl-ethanolamine (PEA), which need to be further investigated in cattle. These results indicate that the measurement of specific representatives of phosphatidylcholines in plasma may provide a novel diagnostic biomarker of fatty liver disease in dairy cows.

Metabolic profiles of cow's blood; a review

The term 'metabolic profile' refers to the analysis of blood biochemical parameters that are useful to assess and prevent metabolic and nutritional disorders in dairy herds. In the higher standards of milk production, the priority in modern breeding is keeping dairy cows in high lactation and healthy. The proper analysis, as well as control. of their feeding and metabolic status is immensely important for the health condition of the herd. The disproportion between the genetically determined ability for milk production and the limitations in improving the energy value of the ration may be the cause of metabolic disorders. Negative energy balance has a major impact on the body's hormonal balance and organ functions and mostly appears during transition periods: from 3 to 2 weeks prepartum until 2-3 weeks postpartum. The term 'transition' is used to underscore the important physiological, metabolic and nutritional changes occurring in this time. The manner in which these changes occur and how they are diagnosed and detected are extremely important, as they are closely related to clinical and subclinical postpartum diseases, lactation and reproductive performance - factors that significantly shape the profitability of production. Therefore the priority for intensive milk production is prevention of metabolic diseases and other disorders. It is the intent of this review to synthesize and summarize the information currently available on metabolic status and physiological changes in the cow's body that occur during lactation, as well as to discuss the interpretation of the results, which will be a useful diagnostic tool in nutritional evaluations of the dairy herd. © 2016 Society of Chemical Industry.

Comparative effects of corn-based diet and phase-fed cassava-based diet on growth rate, carcass characteristics and lipid profile of meat-type ducks

Objective

This experiment was conducted to evaluate the effects of a corn- or cassava- based diet on the production of meat-type ducks.

Methods

Four hundred day-old ducks were used in this experiment. They were divided into five groups with each group replicated eight times. The ducks fed the corn-based diets served as the control group. The four other groups comprised different treatments, with each one given the cassava-based diet based on phase-feeding. Three treatments were fed the cassava-based diet from 16, 28, and 35 d; respectively up to 42 d of age and the other group was fed the cassava-based diet from 1 to 42 d of age.

Results

The results indicated that ducks on either the corn- or cassava-based diets were similar in growth during 1 to 9 d of age. However, toward 35 to 42 d, the cassava-diet produced a higher weight gain (p<0.05). The cassava-based diet was better than the corn-based diet at increasing the outer and inner breast weights at 28, 35, or 42 d (p<0.05). In contrast, the corn-based diet was better at increasing abdominal fat (p<0.05). The two diets did not differ in their effects on the serum triglyceride, cholesterol, high-density lipoprotein-cholesterol, low-density lipoprotein-cholesterol, very-low-density lipoprotein-cholesterol, and liver cholesterol. The corn-based diet, however, caused a highly significantly greater level of liver triglyceride (p<0.01).

Conclusion

The results of this study suggest that both the cassava- and corn- based diets are similar in their effect on meat-type ducks during the starter stage but toward the finisher stage, the cassava-based diet has a better influence on weight gain and carcass characteristics.

Equine metabolic syndrome impairs adipose stem cells osteogenic differentiation by predominance of autophagy over selective mitophagy

Adipose‐derived mesenchymal stem cells (ASC) hold great promise in the treatment of many disorders including musculoskeletal system, cardiovascular and/or endocrine diseases. However, the cytophysiological condition of cells, used for engraftment seems to be fundamental factor that might determine the effectiveness of clinical therapy. In this study we investigated growth kinetics, senescence, accumulation of oxidative stress factors, mitochondrial biogenesis, autophagy and osteogenic differentiation potential of ASC isolated from horses suffered from equine metabolic syndrome (EMS). We demonstrated that EMS condition impairs multipotency/pluripotency in ASCs causes accumulation of reactive oxygen species and mitochondria deterioration. We found that, cytochrome c is released from mitochondria to the cytoplasm suggesting activation of intrinsic apoptotic pathway in those cells. Moreover, we observed up‐regulation of p21 and decreased ratio of Bcl‐2/BAX. Deteriorations in mitochondria structure caused alternations in osteogenic differentiation of ASC_EMS resulting in their decreased proliferation rate and reduced expression of osteogenic markers BMP‐2 and collagen type I. During osteogenic differentiation of ASC_EMS, we observed autophagic turnover as probably, an alternative way to generate adenosine triphosphate and amino acids required to increased protein synthesis during differentiation. Downregulation of PGC1α, PARKIN and PDK4 in differentiated ASC_EMS confirmed impairments in mitochondrial biogenesis and function. Hence, application of ASC_EMS into endocrinological or ortophedical practice requires further investigation and analysis in the context of safeness of their application.

Milk yield, milk composition, and hepatic lipid metabolism in transition dairy cows fed flaxseed or linola

The response of transition dairy cows to dietary supplementation with fat sources of various fatty acid profiles could affect hepatic fat metabolism differently. Twenty-eight Holstein cows were blocked for similar calving date 4wk before expected parturition to compare the effects of feeding sources of n-3 and n-6 fatty acids on milk production and composition, plasma metabolites, and liver parameters. Cows within each block were assigned to 1 of 3 isonitrogenous and isoenergetic diets: control with a source of calcium salts of palm oil (MEG; 1.1 and 2.6% of the dry matter in prepartum and postpartum diets, respectively); n-3 fatty acids supplied as whole flaxseed (WFL; 4.8 and 7.7% of the dry matter in prepartum and postpartum diets, respectively); and n-6 fatty acids supplied as whole linola (WLO; 4.8 and 7.7% of the dry matter in prepartum and postpartum diets, respectively). Diets were fed until wk 14 of lactation. Contrasts of WFL versus WLO and polyunsaturated fatty acids versus MEG were compared. Cows fed polyunsaturated fatty acids increased dry matter intake over time at a greater extent than those fed MEG, which resulted in enhanced energy balance. Cows fed MEG produced more milk compared with those fed polyunsaturated fatty acids, and there was no difference between those fed WFL and WLO. We found no effect on body condition score and body weight. Plasma concentrations of glucose, fatty acids, and BHB were similar among diets. There was no effect of diet on concentration of glycogen and activities of superoxide dismutase and glutathione peroxidase in the liver. We observed higher concentrations of hepatic lipids and triacylglycerol in cows fed MEG compared with those fed polyunsaturated fatty acids, and no difference between WFL and WLO. Hepatic catalase activity tended to be higher on wk 4 after calving for cows supplemented with WFL compared with those fed WLO. Feeding linoleic and linolenic acids as unprotected oilseeds increased dry matter intake over time at a greater extent for cows fed MEG, improved the energy status, and lowered hepatic lipids and triacylglycerol contents, which may contribute to enhance the health status of transition dairy cows.

Rumen-protected choline: A significance effect on dairy cattle nutrition

Choline is a vitamin-like substance it has multi-function in animal production, reproduction, and health. The transition period is most crucial stage in lactation cycle of dairy cows due to its association with negative hormonal and energy balances. Unfortunately, unprotected choline easily degrades in the rumen; therefore, choline added to the diet in a rumen-protected form. The use of rumen-protected choline (RPC) is a preventive measurement for the fatty liver syndrome and ketosis; may improve milk production as well as milk composition and reproduction parameters. This review summarizes the effectiveness of RPC on animal production, health, and reproduction.

Changes in milk performance and hepatic metabolism in mid-lactating dairy goats after being fed a high concentrate diet for 10 weeks

Feeding a high concentrate (HC) diet is a widely used strategy for supporting high milk yields, yet it may cause certain metabolic disorders. This study aimed to investigate the changes in milk production and hepatic metabolism in goats fed different proportions of concentrate in the diet for 10 weeks. In total, 12 mid-lactating goats were randomly assigned to an HC diet (65% concentrate of dry matter, n=6) or a low concentrate (LC) diet (35% concentrate of dry matter, n=6). Compared with LC, HC goats produced greater amounts of volatile fatty acids and produced more milk and milk lactose, fat and protein (P<0.01). HC goats showed a greater concentration of ATP, NAD, plasma non-esterified fatty acids and hepatic triglycerides than LC goats (P<0.05). Real-time PCR results showed that messenger RNA (mRNA) expression of gluconeogenic genes, namely, glucose-6-phosphatase, pyruvate carboxylase and phosphoenolpyruvate carboxykinase were significantly up-regulated and accompanied greater gluconeogenic enzyme activities in the liver of HC goats. Moreover, the expression of hepatic lipogenic genes including sterol regulatory element-binding protein 1c, fatty acid synthase and diacylglycerol acyltransferase mRNA was also up-regulated by the HC diet (P<0.05). HC goats had greater hepatic phosphorylation of AMP-activated protein kinase than LC (P<0.05). Furthermore, histone-3-lysine-27-acetylation contributed to this elevation of gluconeogenic gene expression. These results indicate that lactating goats fed an HC diet for 10 weeks produced more milk, which was associated with up-regulated gene expression and enzyme activities involved in hepatic gluconeogenesis and lipogenesis.

Insulin-dependent glucose metabolism in dairy cows with variable fat mobilization around calving

Dairy cows undergo significant metabolic and endocrine changes during the transition from pregnancy to lactation, and impaired insulin action influences nutrient partitioning toward the fetus and the mammary gland. Because impaired insulin action during transition is thought to be related to elevated body condition and body fat mobilization, we hypothesized that over-conditioned cows with excessive body fat mobilization around calving may have impaired insulin metabolism compared with cows with low fat mobilization. Nineteen dairy cows were grouped according to their average concentration of total liver fat (LFC) after calving in low [LLFC; LFC <24% total fat/dry matter (DM); n=9] and high (HLFC; LFC >24.4% total fat/DM; n=10) fat-mobilizing cows. Blood samples were taken from wk 7 antepartum (ap) to wk 5 postpartum (pp) to determine plasma concentrations of glucose, insulin, glucagon, and adiponectin. We applied euglycemic-hyperinsulinemic (EGHIC) and hyperglycemic clamps (HGC) in wk 5 ap and wk 3 pp to measure insulin responsiveness in peripheral tissue and pancreatic insulin secretion during the transition period. Before and during the pp EGHIC, [(13)C6] glucose was infused to determine the rate of glucose appearance (GlucRa) and glucose oxidation (GOx). Body condition, back fat thickness, and energy-corrected milk were greater, but energy balance was lower in HLFC than in LLFC. Plasma concentrations of glucose, insulin, glucagon, and adiponectin decreased at calving, and this was followed by an immediate increase of glucagon and adiponectin after calving. Insulin concentrations ap were higher in HLFC than in LLFC cows, but the EGHIC indicated no differences in peripheral insulin responsiveness among cows ap and pp. However, GlucRa and GOx:GlucRa during the pp EGHIC were greater in HLFC than in LLFC cows. During HGC, pancreatic insulin secretion was lower, but the glucose infusion rate was higher pp than ap in both groups. Plasma concentrations of nonesterified fatty acids decreased during HGC and EGHIC, but in both clamps, pp nonesterified fatty acid concentrations did not reach the ap levels. The study demonstrated a minor influence of different degrees of body fat mobilization on insulin metabolism in cows during the transition period. The distinct decrease in the glucose-dependent release of insulin pp is the most striking finding that explains the impaired insulin action after calving, but does not explain differences in body fat mobilization between HLFC and LLFC cows.

The role of rumen-protected choline in hepatic function and performance of transition dairy cows

High-producing dairy cows enter a period of negative energy balance during the first weeks of lactation. Energy intake is usually sufficient to cover the increase in energy requirements for fetal growth during the period before calving, but meeting the demand for energy is often difficult during the early stages of lactation. A catabolic state predominates during the transition period, leading to the mobilisation of energy reserves (NEFA and amino acids) that are utilised mainly by the liver and muscle. Increased uptake of mobilised NEFA by the liver, combined with the limited capacity of hepatocytes to either oxidise fatty acids for energy or to incorporate esterified fatty acids into VLDL results in fatty liver syndrome and ketosis. This metabolic disturbance can affect the general health, and it causes economic losses. Different nutritional strategies have been used to restrict negative effects associated with the energy challenge in transition cows. The provision of choline in the form of rumen-protected choline (RPC) can potentially improve liver function by increasing VLDL exportation from the liver. RPC increases gene expression of microsomal TAG transfer protein and APOB100 that are required for VLDL synthesis and secretion. Studies with RPC have looked at gene expression, metabolic hormones, metabolite profiles, milk production and postpartum reproduction. A reduction in liver fat and enhanced milk production has been observed with RPC supplementation. However, the effects of RPC on health and reproduction are equivocal, which could reflect the lack of sufficient dose–response studies.

Effect of postpartum propylene glycol allocation to over-conditioned Holstein cows on concentrations of milk metabolites

The objective of the study was to investigate the effect of propylene glycol (PG) allocation on concentrations of milk metabolites with potential use as indicators of glucogenic status in high yielding postpartum dairy cows. At time of calving, nine ruminally cannulated Holstein cows were randomly assigned to ruminal dosing of 500 g/d tap water (CON, n = 4) or 500 g/d PG (PPG, n = 5). The PG was given with the morning feeding week 1-4 postpartum (treatment period) and cows were further followed during week 5-8 postpartum (follow-up period). All cows were fed the same postpartum diet. Milk samples were obtained at each milking (3 times/d) in the treatment period, and at morning milking during the follow-up period. Weekly blood samples were obtained from -4 to +8 weeks relative to calving and daily blood samples from -7 until +7 d relative to calving. The main effect of PG allocation was an increased glucogenic status, e.g. visualised by a prompt marked increase in blood fructosamine. During the treatment period, milk concentration of free glucose tended to be greater, whereas milk concentrations of isocitrate and BHBA were lower for PPG compared with CON. It is proposed that the ratio between free glucose and isocitrate in milk may be a potential biomarker for glucogenic status in the vulnerable early postpartum period. We will pursue this issue in the future.

Serum paraoxonase 1 (PON1) activity and lipid metabolism parameters changes in different production cycle periods of Holstein-Friesian, Polish Red and Norwegian breeds

We investigated the measurement of paraoxonase 1 (PON1), as a potential marker of redox state changes in dairy cows, its involvement in lipid metabolism and compared it with superoxide dismutase (SOD) activity changes. We also evaluated lipid metabolism parameters associated with dairy production. PON1 paraoxonase and arylesterase acitvities, SOD activity, beta-hydroxybutyrate (BHB), uric acid (UA), high density lipoprotein (HDL), low density lipoprotein (LDL), cholesterol and triglyceride concentrations were measured in Holstein-Friesian, Polish Red and Norwegian breeds serum in two production cycles. Our data showed a significant postpartum depletion in PON1 activity and lipoprotein and lipid products concentrations, with elevated BHB values. However, there were no significant changes in SOD activity and uric acid concentrations in Holstein-Friesian and Polish Red breeds after calving. At lactation peak there was a significant SOD activity decrease correlated with standardized PON1 activity depletion in all examined breeds. The results suggest that PON1 might be a better parameter for minimal redox state changes in serum, shortly after labour in the examined breeds.

Minor milk constituents are affected by protein concentration and forage digestibility in the feed ration

The present study was conducted in order to investigate if selected minor milk components would be indicative for the nutritional situation of the cow. Forty-eight dairy cows were offered a high digestible ration vs. a lower digestible ration combined with 2 protein levels in a 4 × 4 Latin square design. Milk glucose, glucose-6-phosphate, cholesterol, triacylglycerides (TAG), uric acid and β-hydroxybutyrate (BHBA) were measured and correlated mutually and towards other milking parameters (yield, h since last milking, days in milk (DIM), urea, etc). The variation range of the suggested variables were broad, a fact that may support their utilisation as predictive parameters. The content of milk metabolites was significantly affected by the change in rations as milk glucose, glucose-6-phosphate, uric acid, and the ratio cholesterol: triacylglycerides increased with higher energy intake while BHBA and TAG decreased. The content of some of the milk metabolites changed during 24 h day/night periods: BHBA, cholesterol, uric acid and TAG increased whereas free glucose decreased in the night period. Certain associations between milk metabolites and calculated energy parameters like ECM, body condition score (BCS), and body weight gain were found, however, these associations were to some extent explained by an interaction with DIM, just as changes in milk metabolites during a 24 h period seems to interfere. It is concluded that the practical use of the suggested milk variables should be based on more than one metabolite and that stage of lactation and possibly time of the day where the milk is collected should be incorporated in predictive models.

BHBA influences bovine hepatic lipid metabolism via AMPK signaling pathway

β-hydroxybutyric acid (BHBA), an important metabolite in β-oxidation, is involved in the development of ketosis in dairy cows. It is known that AMP-activated protein kinase (AMPK) signaling pathway plays an important role in the regulation of lipid metabolism in hepatocytes. In the present study, bovine hepatocytes were treated with BHBA at variable concontrations and Compound C (Cpd C, an AMPK inhibitor) to investigate the effects of BHBA on the AMPK signaling pathway. The results showed that when the concentration of BHBA reached 1.2 mM, the AMPK signaling pathway was activated and the expression of sterol regulatory element binding protein-1c (SREBP-1c) as well as its target genes were significantly decreased. And these decreases were blocked by Cpd C. The binding activity and nucleus translocation of SREBP-1c showed a similar trend. The expression of peroxisome proliferator activated receptor-α (PPARα), carbohydrates response element binding protein (ChREBP) and their target genes were significantly increased while they were negatively suppressed by the Cpd C. The content of triglyceride (TG) had no obviously change in the BHBA and Cpd C-treated groups. These results indicate that BHBA can activate AMPK signaling pathway and regulate lipid synthesis and lipid oxidation genes of AMPK but showed no effect on TG in bovine hepatocytes.

Association of rumen fill score and energy status during the close-up dry period with conception at first artificial insemination in dairy cows

Recent studies have shown significant associations between prepartum energy status and postpartum fertility in dairy cows; therefore, the assessment of energy status by blood metabolites and metabolic hormones and suitable improvement of management during the prepartum period may enhance reproductive performance. Rumen fill score (RFS) is associated with feed intake; however, it is unknown whether RFS is also related to blood parameters. Therefore, this study investigated the relationship between RFS and energy status during the prepartum period, and their associations with conception at first artificial insemination (AI) after parturition. In 42 multiparous Holstein cows, RFS assessment and blood sampling were carried out twice a week during 3 weeks of the peripartum period. Ovarian cycles until AI were evaluated by measuring milk progesterone levels. Before calving, positive correlations were observed between RFS and total cholesterol, and RFS did not change in pregnant cows at first AI after parturition, whereas in non-pregnant cows, RFS decreased gradually as the calving day approached. After calving, non-pregnant cows showed lower energy status compared with pregnant cows, and some non-pregnant cows showed anovulation and cessation of estrous cycle. In conclusion, RFS during the close-up dry period is related to real-time energy status, and is associated with postpartum energy status and conception at first AI in dairy cows. © 2016 Japanese Society of Animal Science.