Nutrition-induced ketosis alters metabolic and signaling gene networks in liver of periparturient dairy cows.

Dairy cows are highly susceptible after parturition to developing liver lipidosis and ketosis, which are costly diseases to farmers. A bovine microarray platform consisting of 13,257-annotated oligonucleotides was used to study hepatic gene networks underlying nutrition-induced ketosis. On day 5 postpartum, 14 Holstein cows were randomly assigned to ketosis-induction (n = 7) or control (n = 7) groups. Cows in the ketosis-induction group were fed at 50% of day 4 intake until they developed signs of clinical ketosis, and cows in the control group were fed ad libitum throughout the treatment period. Liver was biopsied at 10-14 (ketosis) or 14 days postpartum (controls). Feed restriction increased blood concentrations of nonesterified fatty acids and beta-hydroxybutyrate, but decreased glucose. Liver triacylglycerol concentration also increased. A total of 2,415 genes were altered by ketosis (false discovery rate = 0.05). Ingenuity Pathway Analysis revealed downregulation of genes associated with oxidative phosphorylation, protein ubiquitination, and ubiquinone biosynthesis with ketosis. Other molecular adaptations included upregulation of genes and nuclear receptors associated with cytokine signaling, fatty acid uptake/transport, and fatty acid oxidation. Genes downregulated during ketosis included several associated with cholesterol metabolism, growth hormone signaling, proton transport, and fatty acid desaturation. Feed restriction and ketosis resulted in previously unrecognized alterations in gene network expression underlying key cellular functions and discrete metabolic events. These responses might help explain well-documented physiological adaptations to reduced feed intake in early postpartum cows and, thus, provide molecular targets that might be useful in prevention and treatment of liver lipidosis and ketosis.     

Lipogenesis at the suckling-weaning transition in liver and brown adipose tissue of the rat

The responses of rat hepatic and brown adipose tissue in vivo lipogenesis to premature (15 days) and normal (21 days) weaning have been correlated to changes in the activities of acetyl-CoA carboxylase and two NADPH-producing enzymes, malic enzyme and glucose-6-phosphate dehydrogenase. Both tissues show an induction of lipogenesis in response to weaning. In the liver, lipogenic flux is closely linked to the activity of acetyl-CoA carboxylase, but not necessarily that of malic enzyme or glucose-6-phosphate dehydrogenase, whereas no such dissociation between enzyme activity and flux rate occurs in brown adipose tissue. Thyroid hormones, implicated in many physiological changes around weaning, do not seem to play a primary role in the adaptation of lipogenesis to the dietary change at this time, although a permissive role in both tissues is possible.     

Steroid profiles of brown adipose tissue

In brown adipose tissue of alp-marmot (Marmota marmota), badger (Meles meles) and Wistar rats steroids of C21- and C19-type are identified and quantified. The detection of 3 alpha-hydroxy-5 alpha-pregnan-20-one, 3 alpha-hydroxy-5 beta-pregnan-20-one, 3 alpha,21-dihydroxy-5 alpha-pregnan-20-one, 3 alpha,21-dihydroxy-5 beta-pregnan-20-one and 3 beta,21-dihydroxy-5 alpha-pregnan-20-one is of special interest since sleep-inducing properties have been described with these steroids.     

Metabolic profiles and progesterone cycles in first lactation dairy cows

This study investigated the ovarian function, metabolic profiles and fertility in first lactation Holstein-Friesian dairy cows (mean 305 day milk yield: 7417+/-191kg, n=37). Reproductive profiles obtained from milk progesterone analysis were categorized into normal (n=17) and four abnormal profiles (delayed ovulation, DOV1, n=9; DOV2, n=2; persistent corpus luteum, PCL1, n=6; PCL2, n=4; 1: immediately post-calving, 2: subsequent cycles). Fifty-five percent of cows had abnormal profiles with half of these being categorized as DOV1. Fertility of DOV1 and DOV2 cows was reduced whereas PCL1 and PCL2 cows had similar reproductive competence to normal profile cows. DOV1 animals had higher milk energy values, lower energy balances, lower dry matter intakes (DMI) and greater body weight and body condition score (BCS) losses post-calving than normal profile animals. DOV1 animals also had lower insulin-like growth factor-I (IGF-I) and higher betahydroxybutyrate (BHB) concentrations and tended to have the lower insulin and glucose concentrations in the pre-service period than normal profile cows. All PCL animals had vulval discharges postpartum. Despite this, the DMI, body weight and BCS changes, IGF-I concentrations and fertility of PCL1 animals was similar to normal profile cows. In conclusion, the high prevalence of delayed ovulation post-calving (DOV1) in primiparous high yielding cows lasted long enough (71+/-8.3 days) to have a detrimental impact on fertility and was associated with significant physiological changes. This study did not establish any detrimental effects of PCL profiles on fertility or production parameters.     

Short term voluntary overfeeding disrupts brain insulin control of adipose tissue lipolysis

Insulin controls fatty acid (FA) release from white adipose tissue (WAT) through direct effects on adipocytes and indirectly through hypothalamic signaling by reducing sympathetic nervous system outflow to WAT. Uncontrolled FA release from WAT promotes lipotoxicity, which is characterized by inflammation and insulin resistance that leads to and worsens type 2 diabetes. Here we tested whether early diet-induced insulin resistance impairs the ability of hypothalamic insulin to regulate WAT lipolysis and thus contributes to adipose tissue dysfunction. To this end we fed male Sprague-Dawley rats a 10% lard diet (high fat diet (HFD)) for 3 consecutive days, which is known to induce systemic insulin resistance. Rats were studied by euglycemic pancreatic clamps and concomitant infusion of either insulin or vehicle into the mediobasal hypothalamus. Short term HFD feeding led to a 37% increase in caloric intake and elevated base-line free FAs and insulin levels compared with rats fed regular chow. Overfeeding did not impair insulin signaling in WAT, but it abolished the ability of mediobasal hypothalamus insulin to suppress WAT lipolysis and hepatic glucose production as assessed by glycerol and glucose flux. HFD feeding also increased hypothalamic levels of the endocannabinoid 2-arachidonoylglycerol after only 3 days. In summary, overfeeding impairs hypothalamic insulin action, which may contribute to unrestrained lipolysis seen in human obesity and type 2 diabetes.     

Lipid synthesis by co-cultures of mammary,liver, and adipose tissue explants from sometribove (recombinant methionyl bovine somatotropin)-treated dairy cows

Summary Bovine somatotropin was given to six lactating (230 day) cows (40 mg/day × 5-days) and excipient was given to six control cows. Mammary, liver, and adipose explants from somatotrophin and control cows were co-cultured at 37° C for 24 h with 0.5 μCi [¹⁴C]acetate/ml media with or without 0.5 μg/ml somatotrophin. Tissue lipids were extracted with chloroform/methanol and separated by thin layer chromatography. In vivo somatotrophin increased milk production 2.4 kg/day compared to a 0.9 kg/day decrease by controls. Mammary tissue from somatotrophin cows incorporated more [¹⁴C]acetate into total lipids (4417 vs. 3016 dpm/mg tissue) than controls. Adding somatotrophin to explant cultures from somatotrophin cows further increased incorporation into total lipids (4839 vs. 3994 dpm/mg tissue). In contrast, adipose tissue from somatotrophin cows incorporated less [¹⁴C]acetate into total lipids than controls (1524 vs. 2581 dpm/mg tissue). Serum IGF-I concentration correlated well (r=0.69) with milk output differences between Days 1 and 5 of treatment. Media IGF-I concentration correlated well (r=0.61) with the difference in total lipid synthesis between the in vitro control and somatotrophin groups. Results support the concept that somatotrophin increases milk production by partitioning nutrients away from adipose toward mammary tissue.     

Precursors for liver gluconeogenesis in periparturient dairy cows

The review is based on a compiled data set from studies quantifying liver release of glucose concomitant with uptake of amino acids (AA) and other glucogenic precursors in periparturient dairy cows. It has become dogma that AAs are significant contributors to liver gluconeogenesis in early lactation, presumably accounting for the observed lack of glucogenic precursors to balance estimated glucose need. Until recently, there has been paucity in quantitative data on liver nutrient metabolism in the periparturient period. Propionate is the quantitatively most important glucogenic precursor throughout the periparturient period. However, the immediate post partum increment in liver release of glucose is not followed by an equivalent increment in propionate uptake, because of the lower rate of increment in feed intake compared with the rate of increment in requirements for milk synthesis. The quantitative data on liver metabolism of AA do not support the hypothesis that the rapid post partum increase in net liver release of glucose is supported by increased utilisation of AA for gluconeogenesis. Only alanine is likely to contribute to liver release of glucose through its role in the inter-organ transfer of nitrogen from catabolised AA. AAs seem to be prioritised for anabolic purposes, indicating the relevance of investigating effects of supplying additional protein to post partum dairy cows. Combining data from quantitative and qualitative experimental techniques on L-lactate metabolism point to the conclusion that the quantitatively most important adaptation of metabolism to support the increased glucose demand in the immediate post partum period is endogenous recycling of glucogenic carbon through lactate. This is mediated by a dual site of adaptation of metabolism in the liver and in the peripheral tissues, where the liver affinity for L-lactate is increased and glucose metabolism in peripheral tissues is shifted towards L-lactate formation over complete oxidation.     

Paternal high-fat diet alters triglyceride metabolism-related gene expression in liver and white adipose tissue of male mouse offspring

Obesity is a major public health problem, and its prevalence is progressively increasing worldwide. In addition, accumulating evidence suggests that diverse nutritional and metabolic disturbances including obesity can be transmitted from parents to offspring via transgenerational epigenetic inheritance. The previous reports have shown that paternal obesity has profound impacts on the development and metabolic health of their progeny. However, little information is available concerning the effects of paternal high-fat diet (HFD) exposure on triglyceride metabolism in the offspring. Therefore, we investigated the effects of paternal HFD on triglyceride metabolism and related gene expression in male mouse offspring. We found that paternal HFD exposure significantly increased the body weight, liver and epididymal white adipose tissue (eWAT) weights, and liver triglyceride content in male offspring, despite consuming control diet. In addition, paternal HFD exposure had induced changes in the mRNA expression of genes involved in lipid and triglyceride metabolism in the liver and eWAT. These findings indicate transgenerational inheritance from the paternal metabolic disturbance of triglyceride and support the effects of paternal lifestyle choices on offspring development and health later in life.     

Implications of interscapular brown adipose tissue removal and sucrose overfeeding on the sympatho-adrenal activity and metabolic responses

1. The influence of sucrose overfeeding on the sympatho-adrenal (SA) and metabolic responses was studied in sham-operated (SHAM) rats and in those with interscapular brown adipose tissue (IBAT) removed. 2. Sucrose feeding significantly increased the SA activity, mobilized the free fatty acids (FFA), but did not change glucose homeostasis in sham-operated rats. 3. IBAT removal in control rats fed a stock diet modified the SA activity whereas the levels of both blood glucose and serum FFA were unchanged. 4. However, sucrose in rats void of IBAT potentiated the activity of sympathetic nervous system only and prevented the FFA rise, which is seen in sham-operated sucrose fed rats indicating that the enhanced level of serum FFA in these animals principally originated from the IBAT.     

Embryo yield and plasma progesterone profiles in superovulated dairy cows and heifers.

This study was conducted to compare the superovulatory (SOV) response of dairy cows (n=172) and heifers (n=172), with two SOV treatments started at the mid-luteal-phase of the estrus cycle. Donors were randomly treated either with equine chorionic gonadotrophin (eCG) plus neutra-eCG serum (eCG+N group, n=167) or follicle stimulating gonadotrophin (FSH-P group, n=177).No significant differences were observed among groups in the percentage of superovulatory responsive donors (SR donors; corpora lutea (CL) >/=2), the mean number of total ova, fertilized ova and viable embryos recovered. Cows yielded significantly less total ova and less fertilized ova (P<0.05) and tended to yield less viable embryos (P<0.06) than heifers.Plasma progesterone (P4) concentrations (n=135 donors) on the day of PGF(2alpha) (PGF) injection and on the day of SOV estrus were significantly higher (P<0.01) in eCG+N than in FSH-P donors and, the increase between those 2 days was also significantly higher (P<0.05) in group eCG+N than in group FSH-P, suggesting a higher luteotrophic effect of eCG than FSH-P. SR donors had P4 levels significantly higher (P<0.001) than non-SR donors only on day 5 after the SOV estrus and on the day of embryo recovery. Plasma P4 concentrations at 5 days after the SOV estrus and at embryo recovery correlated significantly (r=0.76, P<0.001).Heifers had significantly higher P4 levels than cows at gonadotrophin injection (P<0.01), PGF injection (P<0.001), 5 days (P<0.01) and 7 days (P<0.001) after the SOV estrus. At day 7 after the SOV estrus, P4 concentrations per ova recovered were significantly higher in heifers than in cows (P<0.01). The increase of plasma P4 per ova recovered, between days 5 and 7 after the SOV estrus, was significantly (P<0.01) higher in heifers than in cows. Also, the increase of plasma P4 between injections of gonadotrophin and PGF was significantly higher (P<0.05) in heifers than in cows.These results suggest that heifers have higher plasma P4 concentrations at diestrus (either before or after the SOV treatment) and this is associated with a higher embryo yield and quality, as compared to lactating cows. These higher plasma P4 concentrations reflect not only differences in ovulation rate as well as the competence of the corpus luteum, which is potentialized by gonadotrophin stimulation.     

Comparative analysis of gene expression profiles in ruminal tissue from Holstein dairy cows fed high or low concentrate diets

Cattle are often fed high concentrate (HC) diets to increase productivity, although HC diets cause changes in ruminal environment such as pH reduction. Despite those well-documented changes in cattle fed HC diets, there is currently a paucity of data describing the molecular events regulating the ruminal environment. Our objective was to gain an understanding of which genes are differentially expressed in ruminal tissue from Holstein cows fed a HC comparing to low concentrate (LC) diet using microarray analysis using a bovine 24 k microarray. A total of 5,200 differentially expressed genes (DEG) were detected for cows fed HC relative to LC. The DEG were firstly annotated with gene ontology (GO) and Kyoto encyclopedia of Genes and Genomes (KEGG), indicating that the DEG were associated with catalytic activity and MAPK pathway, respectively. Further characterization using GeneCodis identified patterns of interrelated annotations for the DEG to elucidate the relationships among annotation groups revealed that a cAMP-dependent protein kinase A catalytic subunit beta (PRKACB), may be associated with ruminal tissue maintenance. The results contributed to understanding of the regulatory mechanisms at the mRNA level for Holstein cows fed at different concentrate ratio diets.     

Soybean oil and linseed oil supplementation affect profiles of ruminal microorganisms in dairy cows

The objective of this study was to evaluate changes in ruminal microorganisms and fermentation parameters due to dietary supplementation of soybean and linseed oil alone or in combination. Four dietary treatments were tested in a Latin square designed experiment using four primiparous rumen-cannulated dairy cows. Treatments were control (C, 60 : 40 forage to concentrate) or C with 4% soybean oil (S), 4% linseed oil (L) or 2% soybean oil plus 2% linseed oil (SL) in a 4 × 4 Latin square with four periods of 21 days. Forage and concentrate mixtures were fed at 0800 and 2000 h daily. Ruminal fluid was collected every 2 h over a 12-h period on day 19 of each experimental period and pH was measured immediately. Samples were prepared for analyses of concentrations of volatile fatty acids (VFA) by GLC and ammonia. Counts of total and individual bacterial groups (cellulolytic, proteolytic, amylolytic bacteria and total viable bacteria) were performed using the roll-tube technique, and protozoa counts were measured via microscopy in ruminal fluid collected at 0, 4 and 8 h after the morning feeding. Content of ruminal digesta was obtained via the rumen cannula before the morning feeding and used immediately for DNA extraction and quantity of specific bacterial species was obtained using real- time PCR. Ruminal pH did not differ but total VFA (110 v. 105 mmol/l) were lower (P < 0.05) with oil supplementation compared with C. Concentration of ruminal NH3-N (4.4 v. 5.6 mmol/l) was greater (P < 0.05) due to oil compared with C. Compared with C, oil supplementation resulted in lower (P < 0.05) cellulolytic bacteria (3.25 × 108 v. 4.66 × 108 colony-forming units (CFU)/ml) and protozoa (9.04 × 104 v. 12.92 × 104 cell/ml) colony counts. Proteolytic bacteria (7.01 × 108 v. 6.08 × 108 CFU/ml) counts, however, were greater in response to oil compared with C (P < 0.05). Among oil treatments, the amount of Butyrivibrio fibrisolvens, Fibrobacter succinogenes and Ruminococcus flavefaciens in ruminal fluid was substantially lower (P < 0.05) when L was included. Compared to C, the amount of Ruminococcus albus decreased by an average of 40% regardless of oil level or type. Overall, the results indicate that some ruminal microorganisms, except proteolytic bacteria, are highly susceptible to dietary unsaturated fatty acids supplementation, particularly when linolenic acid rich oils were fed. Dietary oil effects on ruminal fermentation parameters seemed associated with the profile of ruminal microorganisms.     

Variability of ovarian structures and plasma progesterone profiles in dairy cows with ovarian cysts

Weekly reproductive health examinations were performed on 46 multiparous Holstein cows from 14 to 100 d post partum. Sixteen cows developed 19 nonsimultaneous ovarian cysts, with a mean day of first detection at 34.3 +/- 4.5 d post partum and a mean duration of 31.0 +/- 4.3 d after first detection. Coccygeal blood was collected three times weekly, and plasma progesterone concentrations were determined by radioimmunoassay. Cysts were diagnosed by palpation per rectum or by ultrasonography and classified as follicular or luteal cysts; the cows were not treated. Cows with a mean plasma progesterone concentration of < 1 ng/ml from the first day of detection (Day 1) of a cyst until Day 10 were classified as having a follicular cyst, and those with a mean plasma progesterone concentration of >/= 1 ng/ml from Day 1 to Day 10 were classified as having a luteal cyst. According to this classification, 58% of the cysts were follicular and 42% were luteal. There was an overall 47% agreement between classification by palpation and by ultrasonography on Day 1 with progesterone concentration during Days 1 to 10 after detection of the cyst. Detailed graphs of progesterone concentrations and area of largest follicles or cysts and corpora lutea demonstrate the variability of ovarian structures and progesterone profiles in cystic cows. Detection of a cyst at any one time accompanied by simultaneous measurement of progesterone can lead to different diagnoses of cyst type depending on the method of classification, the presence and age of luteinized tissue in the cyst and undetected corpora lutea.     

Pyruvate dehydrogenase activities and rates of lipogenesis during the fed-to-starved transition in liver and brown adipose tissue of the rat.

The percentages of pyruvate dehydrogenase complex (PDH) in the active form (PDHa) in two lipogenic tissues (liver and brown adipose tissue) in the fed state were 12.0% and 13.4% respectively. After acute (0.5 h) insulin treatment, PDHa activities had increased by 77% in liver and by 234% in brown fat. Significant decreases in PDHa activities were observed in both tissues by 5 h after the removal of food. The patterns of decline in PDHa activities in the two lipogenic tissues were similar in that the major decreases in activities were observed within the first 7 h of starvation. The significant decreases in PDHa activities observed after starvation for 6 h were accompanied by decreased rates of lipogenesis. Hepatic and brown-fat PDHa activities after acute (30 min) exposure to exogenous insulin were less in 6 h-starved than in fed rats, but the absolute increases in PDHa activities over the 30 min exposure period were similar in fed and 6 h-starved rats. Increases in PDHa activities were paralleled by increases in lipid synthesis in both tissues. Re-activation of PDH in response to insulin treatment or chow re-feeding after 48 h starvation occurred more rapidly in brown adipose tissue than in liver. The results are discussed in relation to the importance of the activity of the PDH complex as a determinant of the total rate of lipogenesis during the fed-to-starved transition and after insulin challenge or re-feeding.