The Enhanced Milk Yield Effect of Early Lactation Increased Milking Frequency and Bovine Somatotropin Is Additive and Not Synergistic.

Dairy farm profitability depends on milk yield, so the dairy industry manages cows to improve their productivity. Both bovine somatotropin (bST) and early lactation increased milking frequency (IMF) and milk yield (MY) in dairy cows. The objective of this study was to evaluate the effects of mid-lactation bST administration on milk production in established lactation when combined with the milk yield carry-over effect from early lactation IMF.

Heat Stress Increases Mammary Epithelial Cells and Reduces Viable Immune Cells in Milk of Dairy Cows.

Somatic cells normally found in milk are generally either immune cells such as lymphocytes, monocytes and granulocytes, or mammary epithelial cells. The number and composition of somatic cells in milk can be influenced by a variety of factors, including infection and temperature-humidity index. The objective of this study was to determine the specific effects of heat stress on the cellular composition of the somatic cell population in milk.

Thirty-Two Weeks of Oral Supplementation with LinPro™ Increases Hoof Growth in Healthy Mares.

LinPro™ (LP) is a commercial dietary supplement marketed to increase hoof growth and quality. Ten mature (5-15 years) non-pregnant Quarter Horse mares without existing hoof quality issues were used to test the hypothesis that 32 weeks of daily supplementation with 113 g of LP would increase hoof growth rates as compared to non-supplemented controls. Hooves were trimmed at the start of the study and every 8 weeks thereafter.

The inhibitory effect of trans-10,cis-12 conjugated linoleic acid on sterol regulatory element binding protein-1 activation in bovine mammary epithelial cells involved reduced proteasomal degradation of insulin-induced gene-1.

Trans-10,cis-12 conjugated linoleic acid (t10,c12 CLA) is well recognized as a key CLA isomer responsible for the reduction in milk fat synthesis that leads to milk fat depression in dairy cows. Sterol regulatory element binding protein-1 (SREBP1) is a key transcription factor in bovine mammary gland coordinating transcription of the genes for fatty acid synthesis. SREBP1 activation requires the removal of insulin-induced gene-1 (Insig1) that serves as a repressor of SREBP1 in the endoplasmic reticulum (ER).

Esterification of essential and non-essential fatty acids into distinct lipid classes in ruminant and non-ruminant tissues.

Extensive microbial biohydrogenation of polyunsaturated fatty acids (PUFA) in the rumen reduces the essential fatty acids (EFA) available for absorption in ruminant animals, but there is no published documentation of ruminants developing EFA deficiency. In ruminants, most circulating PUFA are found in the phospholipid (PL) and cholesteryl ester lipid classes that have slow turn-over compared to other lipid classes. The objective of this experiment was to measure fatty acid esterification patterns of the non-EFA palmitic (16:0) and oleic acid (18:1), and the EFA linoleic (18:2) and linolenic acid (18:3) in small intestine, liver, and muscle tissue of cows and pigs to identify tissues participating in sequestration of these FA in less metabolically active lipid classes in ruminants.

Challenges in enriching milk fat with polyunsaturated fatty acids.

Milk fatty acid composition is determined by several factors including diet. The milk fatty acid profile of dairy cows is low in polyunsaturated fatty acids, especially those of the n-3 series. Efforts to change and influence fatty acid profile with longer chain polyunsaturated fatty acids have proven challenging.

Relationship between stearoyl-CoA desaturase 1 gene expression, relative protein abundance, and its fatty acid products in bovine tissues.

Stearoyl-CoA desaturase 1 (SCD1) greatly contributes to the unsaturated fatty acids present in milk and meat of cattle. The SCD1 enzyme introduces a double bond into certain saturated fatty acyl-CoAs producing monounsaturated fatty acids (MUFA). The SCD1 enzyme also has been shown to be active in the bovine mammary gland converting t11 18:1 (vaccenic acid) to c9 t11 conjugated linoleic acid (CLA).

Acute effects of rotavirus and malnutrition on intestinal barrier function in neonatal piglets.

Aim: To investigate the effect of protein-energy malnutrition on intestinal barrier function during rotavirus enteritis in a piglet model.

Methods: Newborn piglets were allotted at day 4 of age to the following treatments: (1) full-strength formula (FSF)/noninfected; (2) FSF/rotavirus infected; (3) half-strength formula (HSF)/noninfected; or (4) HSF/rotavirus infected. After one day of adjustment to the feeding rates, pigs were infected with rotavirus and acute effects on growth and diarrhea were monitored for 3 d and jejunal samples were collected for Ussing-chamber analyses.

Dietary long-chain PUFA enhance acute repair of ischemia-injured intestine of suckling pigs.

Infant formula companies have been fortifying formulas with long-chain PUFA for 10 y. Long-chain PUFA are precursors of prostanoids, which stimulate recovery of intestinal barrier function. Supplementation of milk with PUFA increases the content of arachidonic acid (ARA) in enterocyte membranes; however, the effect of this enrichment on intestinal repair is not known.

Regulation of the bovine SCD5 promoter by EGR2 and SREBP1.

In rodents, the transcription factors early growth response 2 (EGR2) and sterol regulatory element binding protein 1a (SREBP1a) regulate transcription of the stearoyl-CoA desaturase 2 (SCD2) gene during peripheral nerve myelination, which may be important for synthesis of the lipid component of myelin. Most non-rodent genomes do not contain the SCD2 gene, but rather express SCD5 in brain and nervous tissues. In this paper, we asked whether bovine SCD5 is regulated in a similar manner to rodent SCD2.

Probiotic bacteria produce conjugated linoleic acid locally in the gut that targets macrophage PPAR γ to suppress colitis.

Background: Inflammatory bowel disease (IBD) therapies are modestly successful and associated with significant side effects. Thus, the investigation of novel approaches to prevent colitis is important. Probiotic bacteria can produce immunoregulatory metabolites in vitro such as conjugated linoleic acid (CLA), a polyunsaturated fatty acid with potent anti-inflammatory effects.

A Potential Role for Pro-Inflammatory Cytokines in the Development of Insulin Resistance in Horses.

Understanding the mechanisms involved in the development of insulin resistance in horses should enable development of effective treatment and prevention strategies. Current knowledge of these mechanisms is based upon research in obese humans and rodents, in which there is evidence that the increased production of pro-inflammatory cytokines by adipose tissue negatively influences insulin signaling in insulin-responsive tissues. In horses, plasma concentrations of the cytokine, tumor necrosis factor-α, have been positively correlated with body fatness and insulin resistance, leading to the hypothesis that inflammation may reduce insulin sensitivity in horses.

Effects of the insulin sensitizing drug, pioglitazone, and lipopolysaccharide administration on markers of systemic inflammation and clinical parameters in horses.

Equine metabolic syndrome (EMS) is a condition of obese horses characterized by insulin resistance, systemic inflammation, and an increased risk of laminitis. The pathogenesis of EMS is thought, in part, to be due to inflammatory proteins produced by adipose tissue. Reducing inflammation may decrease the incidence of laminitis in horses with EMS.

Effects of acute hyperinsulinemia on inflammatory proteins in horses.

Laminitis is a painful, inflammatory disease of the equine hoof that often results in euthanasia. Elevated plasma insulin concentrations are a predictive factor for laminitis, and in previously healthy horses and ponies, laminitis was induced by infusion of insulin. Thus, we chose to determine if an infusion of insulin would increase plasma concentrations of inflammatory cytokines and cytokine mRNA abundance in subcutaneous adipose tissue, skeletal muscle, and white blood cells.

Dietary arachidonate differentially alters desaturase-elongase pathway flux and gene expression in liver and intestine of suckling pigs.

Because dietary arachidonate (ARA) and its eicosanoid derivatives are major regulators of intestinal homeostasis and repair following injury, we evaluated the effects of dietary ARA on desaturation and elongation of (13)C-18:2(n-6) and mRNA abundance of Δ-6-desaturase (FADS2), elongase (ELOVL5), and Δ-5-desaturase (FADS1) in liver and intestine. Day-old pigs (n = 96) were fed milk-based formula containing 0, 0.5, 2.

Dietary conjugated linoleic acid alters long chain polyunsaturated fatty acid metabolism in brain and liver of neonatal pigs.

Effects of dietary conjugated linoleic acid (CLA, 1% mixed isomers) on n-6 long-chain polyunsaturated fatty acid (LCPUFA) oxidation and biosynthesis were investigated in liver and brain tissues of neonatal piglets. Fatty acid β-oxidation was measured in tissue homogenates using [1-(14)C]linoleic acid (LA) and -arachidonic acid (ARA) substrates, while fatty acid desaturation and elongation were traced using [U-(13)C]LA and GC-MS. Dietary CLA had no effect on fatty acid β-oxidation, but significantly decreased n-6 LCPUFA biosynthesis by inhibition of LA elongation and desaturation.

De novo fatty acid synthesis and NADPH generation in equine adipose and liver tissue.

The lipogenic capacities of equine liver and adipose tissue explants were investigated in vitro. Preference for glucose or acetate as the primary carbon source for de novo fatty acid synthesis was determined using (14)C labeled substrates. Additional aims included determining the relative contribution of NADPH generating pathways to reducing equivalent generation and comparing the lipogenic activity of two adipose depots, mesenteric and subcutaneous harvested from the crest region of the neck.

Activation of AMP-activated protein kinase (AMPK) inhibits fatty acid synthesis in bovine mammary epithelial cells.

Activation of AMP-activated protein kinase (AMPK), a heterotrimeric energy-sensing protein, decreases lipid synthesis in liver tissue of various species; however, little is known about the role of AMPK in the regulation of fatty acid synthesis in bovine mammary epithelial cells. Here we report the presence of AMPK mRNA in MAC-T bovine mammary epithelial cells and mammary gland. Treatment of MAC-T with an AMPK activator dramatically decreased de novo fatty acid synthesis by inactivating acetyl-CoA carboxylase-alpha.

Enrichment of intestinal mucosal phospholipids with arachidonic and eicosapentaenoic acids fed to suckling piglets is dose and time dependent.

Infant formula companies began fortifying formulas with long-chain PUFA in 2002, including arachidonic acid (ARA) at approximately 0.5% of total fatty acids. The primary objective of this study was to determine the time-specific effects of feeding formula enriched with supra-physiologic ARA on fatty acid composition of intestinal mucosal phospholipids.

Comparison of pig, sheep and chicken SCD5 homologs: Evidence for an early gene duplication event.

Stearoyl-CoA desaturase (SCD) catalyzes the desaturation of saturated fatty acyl-CoA substrates at the delta-9 position. Multiple SCD isoforms are well characterized in rodents, especially in mice, where four isoforms have been described. In humans and cows, two SCD isoforms have been described: SCD1, which is a homolog of murine SCD1, and SCD5, which appears to be a distinct SCD gene rather than an ortholog of any of the four murine isoforms.

Conjugated linoleic acid reduces body fat accretion and lipogenic gene expression in neonatal pigs fed low- or high-fat formulas.

Childhood obesity is an increasing problem and may predispose children to adult obesity. Weight gain during infancy has been linked to excessive weight later in life. Conjugated linoleic acids (CLA) have been shown to reduce fat gain and body fat mass in animal models and in humans.

Arginine activates intestinal p70(S6k) and protein synthesis in piglet rotavirus enteritis.

We previously showed that phosphorylation of p70 S6 kinase (p70(S6k)) in the intestine is increased during viral enteritis. In this study, we hypothesized that during rotavirus infection, oral Arg, which stimulates p70(S6k) activation, will further stimulate intestinal protein synthesis and mucosal recovery, whereas the p70(S6k) inhibitor rapamycin (Rapa) will inhibit mucosal recovery. Newborn piglets were fed a standard milk replacer diet supplemented with Arg (0.

Effect of animal plasma proteins on intestinal damage and recovery of neonatal pigs infected with rotavirus.

Rotaviruses infect and elicit diarrhea in neonates of most mammalian species and cause 800,000 infant deaths a year. We used neonatal piglets to study the effects of dietary animal plasma proteins on intestinal health following rotavirus infection. Plasma protein contains a diverse mixture of functional components with biological activity and improves the health of animals challenged with other diarrhea-causing pathogens.

Identification and characterization of a novel bovine stearoyl-CoA desaturase isoform with homology to human SCD5.

Stearoyl-CoA desaturase (SCD) is an enzyme responsible for the production of cis-9, trans-11 conjugated linoleic acid in ruminant fats, and for the synthesis of palmitoleoyl-CoA and oleoyl-CoA. To date, only one SCD isoform has been described in ruminant species, although multiple isoforms have been found in many other mammalian species. In this paper, we describe for the first time a second SCD isoform in cattle, which appears to be an ortholog of human SCD5 rather than a homolog of bovine SCD1 or any of the described murine SCD isoforms.