No abstract

The objectives of this study were to examine the effects of dietary gamma-linolenic acid-enriched oil extracted from fungi on rat body composition and on the various enzyme activities relating to fat metabolism in the liver. The oil contained 25.3 g gamma-linolenic acid/100 g fatty acids. The levels of gamma-linolenic acid-enriched oil in the diets were 0, 1.5 and 4%, to give 0, 2.88 and 7.68 g gamma-linolenic acid/kg diet. The control diet contained 8% soybean oil. The rats were given free access to these diets for 4 wk. Body weight gain was less in the gamma-linolenic acid oil-fed groups than in the control group, although food intake was similar among the three groups. Absolute and relative carcass fat weights were significantly lower in the gamma-linolenic acid oil-fed groups than in the control group. Carcass protein and water contents were not different among the three groups, although values were slightly greater than controls in gamma-linolenic acid-fed groups when expressed relative to body weight. Plasma total cholesterol and free fatty acid concentrations generally were lower in the gamma-linolenic acid oil-fed groups than in the control group. In the liver, there were no significant differences in activities of malic enzyme and citrate cleavage enzyme among the three groups. However, the activities of carnitine palmitoyl-transferase and peroxisomal beta-oxidation were significantly higher in the gamma-linolenic acid oil-fed groups than in the control group. These results clearly demonstrate that dietary gamma-linolenic acid oil reduces body fat content and facilitates fatty acid beta-oxidation in the liver.

The influence of dietary lysine on hepatic insulin-like growth factor-I (IGF-I) gene expression and plasma IGF-I level was investigated. Two male 6-wk-old pigs from each of six litters were used. Each littermate was assigned to one of two diets, control or low lysine (LL), that were isoenergetic and similar in protein content and provided 14.3 MJ digestible energy/kg for both diets, 185 g protein/kg for the control diet and 180 g protein/kg for the LL diet. The control diet contained all essential amino acids in the recommended amounts, including 11.5 g lysine/kg. The LL diet was similar but contained only 7 g lysine/kg. Pigs were pair-fed these diets for 3 wk. Growth rates and feed efficiencies of pigs fed the LL diet were significantly lower than those of pigs fed the control diet (P < 0.01). Plasma IGF-I levels in pigs fed the LL diet were 52% lower than in those fed the control diet (P < 0.01), and the LL group also had lower plasma IGF-binding protein-3 (IGFBP3) levels (P < 0.05). Despite the strikingly lower plasma IGF-I in pigs fed the LL diet, hepatic IGF-I mRNA abundance did not differ between the two treatment groups. We conclude that the reduction in plasma IGF-I caused by reduced dietary lysine may have been due in part to suppression of post-transcriptional events in IGF-I expression. The lower plasma IGFBP3 in pigs fed the LL diet suggests that increased clearance rates of circulating IGF-I may have been involved in this response.

No abstract

Livestock production is indicated to be one of the major emitters of greenhouse gases (GHG), particularly methane (CH 4 ) and nitrous oxide (N 2 O), around the globe, and the reduction of these emissions is an important goal. GHG emissions as well as other environmental impacts of two pig (Sus scrofa domesticus) farming systems, one using conventional diets (CNV) and the other using low-protein diets supplemented with crystalline amino acids (LOW), were therefore evaluated by comparative life cycle assessment (LCA) focusing on manure management and by cradle-to-farm gate LCA. The functional unit was defined as one marketed pig. For the comparative LCA of manure management, the CH 4 and N 2 O emissions from manure management of CNV were set as a baseline, and the system boundary of LOW included the CH 4 and N 2 O emissions from manure management, and changes in the GHG emissions from feed production including amino acid manufacturing, feed transport, and the materials and energy consumed in manure management. For the cradle-to-farm gate LCA of pig farming, the evaluated system included the processes of feed production including amino acid manufacturing for LOW, feed transport, animal housing including the biological activity of the animal, and manure management. The results of the comparative LCA showed that the GHG emissions from manure management of LOW were 20% less than those of CNV, and the GHG reduction rate of LOW compared to CNV was even greater in the case of a stricter target of effluent nitrogen content. The results of cradle-to-farm gate LCA showed that LOW had lower GHG emissions, acidification potential, eutrophication potential and overall environmental impact, and slightly larger energy consumption, than CNV. The sensitivity analysis showed that LOW still had less GHG emissions than CNV, even in the least preferable case assuming a 40% lower reduction rate of nitrogen excretion.