No abstract

The isotopic characteristics of municipal landfill leachate and gases (carbon dioxide and methane) are unique relative to the aqueous and gaseous media in most other natural geologic environments. The δ13C of the CO2 in landfills is significantly enriched in 13C, with values as high as +20 ‰ reported. The δ13C and δD values of the methane fall within a range of values representative of microbial methane produced primarily by the acetate‐fermentation process. The δD of landfill leachate is strongly enriched in deuterium, by approximately 30 ‰ to nearly 60 ‰ relative to local average precipitation values. This deuterium enrichment is undoubtedly due to the extensive production of microbial methane within the limited reservoir of a landfill. The concentration of the radiogenic isotopes, 14C and 3H, are significantly elevated in both landfill leachate and methane. The 14C values range between approximately 120 and 170 pMC and can be explained by the input of organic material that was affected by the increased 14C content of atmospheric CO2 caused by atmospheric testing of nuclear devices. The tritium measured in leachate, however, is often too high to be explained by previous atmospheric levels and must come from material buried within the landfill. The unique isotopic characteristics observed in landfill leachates and gases provide a very useful technique for confirming whether contamination is from a municipal landfill or some other local source.

The objectives of this study were as follows: 1) to establish whether feeding a source of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) to ewes during late gestation changes the fatty acid profile of colostrum, milk, ewe adipose tissue, and plasma and subsequently lamb plasma and red blood cells (RBC), and 2) to investigate the effects of EPA and DHA on mRNA expression in ewe adipose tissue. Eighty-four gestating ewes (28 pens, three per pen) were blocked by lambing day and assigned to a diet with an addition of fat at 0.39% of the DM during the last 50 d of gestation using Ca salts of a palm fatty acid distillate (PFAD) high in palmitic and oleic acids or EPA + DHA. Blood samples were taken from ewes on days 20, 1 (parturition), and 30 and from lambs on days 1 and 30 for plasma fatty acid analysis. Fatty analysis of lamb RBC was performed on day 1. Colostrum samples were taken at lambing and milk samples on day 30 for fatty acid analysis. Subcutaneous adipose tissue biopsies were taken from one ewe per pen on day 20 for fatty acid analysis and gene expression analysis of 27 genes. Treatment × day interactions (P < 0.10) were observed for several isomers of C18:1, with concentrations that were greater in plasma of EPA + DHA ewes on day 20, but were not different on day 1 or 30. Plasma concentrations of EPA tended to be greater (P = 0.07), whereas DHA was greater (P < 0.001) in EPA + DHA ewes compared with PFAD ewes. There was no difference in EPA or DHA in adipose tissue with EPA + DHA vs. PFAD supplementation (P > 0.10). Concentrations of fatty acids with 6 to 10 carbons were significantly increased (P < 0.05) in colostrum and milk of EPA + DHA ewes. There was a treatment × day interaction with EPA + DHA ewes yielding greater EPA (P = 0.03) and DHA (P = 0.04) concentrations than PFAD in colostrum, but not in milk. Treatment × day interactions (P < 0.05) were observed for several C18:1 isomers with concentrations that were greater in EPA + DHA ewe colostrum, but were not different between treatments in milk. In lamb plasma and RBC, EPA and DHA were not different between treatments (P > 0.10). The expression of fatty acid synthase and leptin was significantly increased (P < 0.05), whereas the expression of diacylglycerol acyltransferase 2 tended to be increased (P = 0.08) by supplementation of EPA + DHA vs. PFAD. These results suggest that supplementation with EPA and DHA to ewes during late gestation alters the fatty acid profile of plasma, colostrum, and milk and may increase lipogenesis.

Fatty acids are involved in the regulation of many physiological pathways, including those involved in gene expression and energy metabolism. Through effects on these pathways, fatty acids may have lifelong impacts on offspring development and metabolism via maternal supplementation. Therefore, our objective was to investigate the impact of supplementing a source of omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) during late gestation on productive and metabolic responses of ewes and their offspring. Eighty-four gestating ewes (28 pens) were blocked and randomly assigned to a diet with 0.39% added fat during the last 50 d of gestation (d -0). The fat sources were Ca salts of a palmitic fatty acid distillate (PFAD) or EPA + DHA. After lambing (d 1), all ewes and lambs were placed on the same pasture. The ewes were weighed and BCS was measured on d -50, -20, 30, and 60 (weaning) of the experiment. Blood samples were taken from the ewes on d -50, -20, 1 (lambing), 30, and 60. Milk yield and composition were measured at 30 d postpartum. Lambs were weighed and bled at d 1, 30, and 60, and ADG was calculated. All plasma samples were analyzed for glucose and NEFA. Ghrelin, prostaglandin E metabolites (PGEM), and the prostaglandin D2 metabolite 11β-PGF2α were measured in d -20 ewe samples. Insulin and adropin were measured in lamb samples at d 60. There was no difference on ewe BW (P = 0.48) or BCS (P = 0.55), or plasma concentrations of glucose (P = 0.57), NEFA (P = 0.44), ghrelin (P = 0.36), PGEM (P = 0.32), and 11β-PGF2α (P = 0.86) between ewes supplemented with PFAD or EPA + DHA. Neither milk yield nor its composition was different (P > 0.10) among treatments. Lambs born from ewes supplemented with PFAD or EPA + DHA did not have different BW (P = 0.22), ADG (P = 0.21) or plasma NEFA (P = 0.52), glucose (P = 0.50), insulin (P = 0.59), and adropin (P = 0.72) concentrations. These results suggest that supplementation of EPA and DHA during late gestation did not affect ewe metabolic profile or milk production. Lamb performance and metabolism through weaning were not affected by maternal supplementation with an enriched source of EPA and DHA.