Polyunsaturated fatty acids (PUFA) play a role in regulating the body's response to inflammation. Most grains fed to horses are high in linoleic acid (LA), a pro-inflammatory n6 PUFA, compared with α-linolenic acid (ALA), an anti-inflammatory n3 PUFA. Recent interest in hemp (Cannabis sativa) seed oil (HSO) as a PUFA source has arisen due to its unique fatty acid (FA) profile, which includes γ-linolenic acid (GLA), an n6 PUFA with anti-inflammatory properties. Dietary GLA is rapidly converted to dihomo-γ-linolenic acid (DGLA), a precursor to anti-inflammatory eicosanoids. Manipulating dietary FA may lead to alterations in tissue FA profiles in the horse which could promote a reduced inflammatory response. Thus, our objective was to determine if oral supplementation of HSO for 28 d would cause detectable changes in FA composition in synovial fluid (SF) and skeletal muscle (MUS). Six Thoroughbred geldings (11 ± 3.2 yrs, 568 ± 26 kg BW) were used in a crossover experiment with 2 consecutive 63d periods. Horses were offered a control (CON) basal diet of hay and concentrate or the basal diet with the addition of 166 mL HSO delivering 5g GLA. Diets were designed to be isocaloric. Over 7d, HSO was introduced gradually, maintained for another 28d, and then removed and horses resumed basal diets for an additional 28d. Horses were weighed, and body condition score (BCS) assessed weekly. MUS and SF samples werecollected on d0, d35, and d63 of each period. MUS biopsies were taken from the middle gluteus muscle at a depth of 8cm. SF was collected from the left carpus joint. FA were extracted from MUS and SF and analyzed by GC. Individual FA are represented as g of FA per 100g of total fatty acids. Data were analyzed using Proc MIXED in SAS (v.15.1 SAS Institute Inc., Cary, NC). No changes in BW or BCS were observed throughout the study. In SF, GLA was detected after 28d of HSO supplementation (0.32 ± 0.06g/100g) but not at any other time point. On d 28, horses supplemented with HSO also had greater SF DGLA (0.31 ± 0.04g/100g) than CON (0.19 ± 0.04g/100g; P = 0.04). MUS ALA tended (P = 0.07) to be greater in horses fed CON compared with HSO. No other differences were observed for FA in MUS or SF. These results indicate that 28d of HSO supplementation can modify FA profiles in equine skeletal muscle and synovial fluid. This could potentially influence inflammation signaling molecules and subsequently the inflammatory response, however, longer studies with more horses are needed to determine peak incorporation and the effects of varying quantities of HSO in the diet.

The aim of the present study was to compare the effects of post-ruminally infused fat supplements, varying in fatty acid (FA) chain length, on animal performance, metabolism and milk FA. Eleven multiparous Holstein dairy cows were used in a replicated incomplete 3 × 3 Latin square design with 7-d periods, separated by 7-d washouts. Treatments were administered as abomasal infusions of enrichments providing 280 g/d of FA: (1) palmitic acid (98·4 % 16 : 0; PA), (2) caprylic and capric acids (56·2 % 8 : 0, 43·8 % 10 : 0; medium-chain TAG (MCT)) and (3) stearic acid (99·0 % 18 : 0; SA). Relative to PA, SA decreased the efficiency of fat-corrected milk production, which was associated with a tendency for higher DM intake and lower FA absorption with SA, whereas MCT was not different from PA for these variables. Milk fat concentration and yield were increased by PA relative to SA, but only fat yield tended to be greater relative to MCT. Relative to PA, MCT increased milk fat concentration of FA < 16 C, whereas SA increased FA > 16 C. Expression of mammary stearoyl-coA desaturase 1 was lower with SA than with PA. Relative to PA, liver expression of adenosine monophosphate-activated protein kinase-1 and pyruvate kinase was increased with MCT, whereas expression of these genes tended to be increased by SA. The mechanism of increased fat secretion with PA does not seem to be related to a modulation of the expression of lipogenesis-related genes, but rather to increased substrate availability as reflected by milk FA profile.

Commercial hoof supplements commonly contain biotin, minerals such as copper and zinc, and essential fatty acids, such as α-linolenic acid (ALA). Biotin, when supplemented at 5–20 mg daily, increases hoof hardness and hoof growth; however, these effects have not been tested in horses with normal hoof quality, a population that commonly receives them. The objective of this research was to test the efficacy of a commercially-available dietary supplement (LinPro, Foxden Equine, Stuarts Draft, VA) to enhance hoof growth rates in healthy, unshod horses for 6 months (5 treatment [LP]; 5 control [CN]). Secondary objectives were to determine vitamin, mineral, and fatty acid compositions of feed, hoof samples, and plasma following supplementation. The supplement provided 302 mg ALA, 25 mg biotin, 203 mg copper, and 585 mg zinc. Hooves were trimmed at the start of the study and every 8 weeks thereafter. A horizontal line was inscribed on the left front foot and used to measure growth. At the end of the study, hoof clippings and plasma were sampled. Feed was sampled every 8 weeks, composited, and used to determine total intake of biotin, copper, zinc, and ALA. Mares on LP consumed greater levels of biotin, zinc, and copper (P<0.001) but not ALA (P>0.7), and had greater (P=0.032) average hoof growth than CN mares (1.7 ± 0.07 vs 1.4 ± 0.05 cm per 8 week period). Hoof clippings from LP and CN mares contained similar (P>0.5) quantities of ALA, zinc, and copper. Plasma biotin concentration was greater (P<0.001) in LP than CN mares, while other metabolites were not different (P>0.05). Although primarily designed for horses with poor hoof quality, consuming the tested supplement for 6 months increased hoof growth rates in horses with normal hoof quality, which may in part be due to increased biotin intake.

J. Anim. Sci. Vol. 87, E-Suppl. 2/J. Dairy Sci. Vol. 92, E-Suppl. 1 (P ≤ 0.1) P3 activity (1.87 vs. 0.34 arbitrary units for stearic vs. control, respectively). Activity of P2 was not altered (P ≥ 0.05) by any treatments and there was no response to glucocorticoids or unsaturated fatty acids for any of the promoters tested. Stearic acid suppresses the activity of bovine PC promoter 1 but enhances the activity of promoter 3 creating a net increase in promoter activity. These data demonstrate the role of fatty acids in regulating PC expression. The specificity of response for PC promoter function to stearic acid in the current data suggests a physiological role for elevated stearic acid concentrations previously observed in transition cows at calving.

We previously reported the requirement of interferon-gamma (IFN-gamma) expression by cells other than T and natural killer (NK) cells in the brain, in addition to T cells, for prevention of toxoplasmic encephalitis following infection with Toxoplasma gondii. In the present study, we analysed the identity of the IFN-gamma-producing non-T, non-NK cells in the brain using infected athymic nude and SCID mice that lack T cells but express IFN-gamma in their brains. Intracellular staining for IFN-gamma followed by flow cytometry revealed that approximately 45-60% of the cells expressing IFN-gamma in their brains were positive for CD11b or F4/80 on their surfaces. Smaller portions of the cells were positive for pan-NK marker. Further smaller portions were positive for CD11c, and these cells were less than 5% of the IFN-gamma-expressing cells in brains of infected SCID mice. In addition to IFN-gamma proteins, large amounts of mRNA for IFN-gamma were detected in CD11b+ cells purified from brains of infected mice, but it was not the case in the cells obtained from uninfected animals. In infected SCID mice depleted of NK cells by treatment with anti-asialo-GM1 antibody, cells expressing IFN-gamma in their brains were all positive for CD11b, and the IFN-gamma-producing cells were detected in both CD45low and CD45high populations. These results suggest that CD11b+ CD45low microglia and CD11b+ CD45high blood-derived macrophages are the major non-T, non-NK cells which express IFN-gamma in the brain of mice infected with T. gondii.

It is believed, but not proven, that the immunomodulatory effects of DES may vary with the dose and/or gender. To address these critical gaps in the literature, diethylstilbestrol (DES) was administered to female and male CD-1 mice as four subcutaneous injections for 1 week at 0, 5, 15, and 30 μg/kg bw doses, and immunological and reproductive effects examined a day after the last injection. Female thymuses were significantly larger than their male counterparts. Short-term administration of DES to female or male mice neither induced thymic atrophy nor altered the relative percentages of thymic subsets. Nevertheless, DES treatment of female or male mice induced a dose-related apoptosis of CD4+8+, CD4+8− and CD4−8+ subsets as analyzed by 7-amino-actinomycin D (7-AAD). Immature CD4−8− subset of thymocytes from females was also affected by high dose DES. The pattern of mitogen-induced proliferation of splenic lymphocytes varied with the dose of hormone and the gender. In females, splenic lymphocytes from low dose DES (5 μg/kg bw)-treated mice exhibited an increased proliferative response to Con-A, LPS or PMA/ionomycin compared with controls. Similar cultures from mice treated with higher doses of DES (15 or 30 μg/kg bw) did not manifest an increased proliferative response, but rather showed a trend for suppressed proliferation, especially in response to Con-A. In males, DES had minimal effects with the exception of increased proliferative response to Con-A in splenocytes from medium-dose-DES-treated mice. The changes in mitogen-induced proliferation in DES-treated female mice were not mirrored by similar changes in the relative numbers of CD90+ or CD45R+ cells, or in ratios of anti-apoptotic Bcl-2 to apoptotic Bax proteins. Con-A-activated splenocytes from DES-treated mice, particularly from females, had a decreased ability to secrete interferon-γ compared with controls. Taken together, these findings suggest that short-term exposure to DES has differential immunological effects depending upon the dose of hormone and sex.

Estrogens have been shown to markedly modulate the immune system. One mechanism by which estrogens could modulate the immune system is by regulating cytokines, an aspect not well-studied thus far. To address this issue, normal C57BL/6 orchiectomized mice were given estrogen and its effects on selected cytokines, interferon-gamma (IFN-gamma), interleukin 2 (IL-2) and IL-4 in lymphocytes from a developmental organ (thymus) and a mature lymphoid organ (spleen) examined. Estrogen significantly increased IFN-gamma and IL-2 mRNA in concanavalin-A (Con-A) activated thymocytes, splenic lymphocytes, and in enriched splenic T cells. Estrogen had no marked effect on IL-4 mRNA. While estrogen increased IFN-gamma mRNA in Con-A activated unseparated splenic lymphocytes and enriched splenic T cells, a numerical increase in IFN-gamma was noticed only in the supernatants of Con-A activated unseparated splenic lymphocytes, but not in enriched splenic T cells. This suggests that for optimal secretion of IFN-gamma in estrogen-treated mice, co-stimulatory signals from antigen presenting cells are needed. Gender differences in IFN-gamma and IL-2 mRNA were also evident. Con-A activated splenic lymphocytes from gonadal-intact, untreated female had a pattern of numerical increase in IFN-gamma mRNA, and IFN-gamma and IL-2 protein levels compared to their male counterparts. Taken together, our data suggests that estrogens regulate the expression of cytokines, which could account in part, for the gender differences in immune capabilities.