Proteomic analysis of endogenous conjugated linoleic acid biosynthesis in lactating rats and mouse mammary gland epithelia cells (HC11).

This study was conducted to investigate the amount of CLA synthesized endogenously by rat mammary tissues in response to TVA (a precursor for cis-9, trans-11 CLA endogenous synthesis) treatment as well as the differences in the protein expression of genes encoding the biosynthesis of CLA in rat mammary tissue and mouse mammary gland epithelia cells (HC11). Treatment with TVA resulted in improved CLA productivity. Furthermore, 2-DE revealed two spots in samples of mammary tissues and one spot in samples of mammary gland epithelia cells (HC11) that were consistently altered in the TVA treatment groups when compared with the control group (non-fatty acid). The mRNA expression patterns of three of the proteins (PDI, PRDX2, LAMR1), as measured by real-time PCR, were similar to the pattern of protein abundance. In addition, the expression of SCD mRNA in the mammary tissue of rats and HC11 cell treated with TVA was higher than in the control group. Our results suggest that the identified proteins may be related to CLA biosynthesis in mammary tissue.

Effects of starch and protein sources on starch disappearance in the gastrointestinal tract of Hanwoo (Korean native) steers.

Hanwoo (Korean native) steers (274.8 +/- 4.6 kg) with ruminal and duodenal cannulae were used in a 4 x 4 Latin square design experiment to examine the effects of dietary treatments on starch disappearance in the gastrointestinal tract. Dietary treatments consisted of concentrate that were based on ground corn with soybean meal (C-SBM), ground corn with corn gluten meal (C-CGM), ground barley with soybean meal (B-SBM) and ground barley with corn gluten meal (B-CGM). Although the intakes of starch and protein for steers fed experimental diets were different, it did not change ruminal pH and total volatile fatty acid concentrations. Average duodenal CP flow and quantity of CP apparently digested post-ruminally was higher (P = 0.001) for CGM-based diets than SBM-based diets. There were increases in quantity (P < 0.001) and percentage (P < 0.001) of corn starch digested post-ruminally compared to barley starch. Synchronized diets showed higher percentages (P = 0.03) of starch apparently digested post-ruminally than asynchronization. Hanwoo steers fed a corn-based diet with a large quantity of starch reaching the duodenum and fed C-CGM supplying great amounts of protein to the small intestine may have contributed to increased post-ruminal starch digestion.

Variations in conjugated linoleic acid (CLA) content of processed cheese by lactation time, feeding regimen, and ripening.

Dairy products are major sources of conjugated linoleic acid (CLA); thus, an increase in CLA content can improve the quality value of dairy products. The objective of this work was to determine the effects of lactation time, feeding regimen, and ripening period on the level of CLA in processed cheese. CLA content in milk varied with the period of lactation; high in spring (April and May, about 6.8 mg CLA/g fat) and relatively low in mid summer and winter (about 4.3 mg CLA/g fat). The effects of dietary regimen and ripening period were determined in milk, which was obtained from March to May. After aging for 4 months, the cheese made from milk obtained from cows fed on pasture contained relatively higher levels of CLA compared to cheese made from milk obtained from cows fed indoors (8.12 mg CLA/g fat vs 6.76 mg CLA/g fat), but there was no difference in 7 month-aged cheeses. In both pasture and indoor feeding, 7 month-aged cheeses showed higher CLA content than 4 month-aged cheeses. The contents of stearic acid (C18:0) and linolenic acid (C18:3) were significantly higher in cheese from pasture fed cows compared to those in cows fed indoors. These findings should be helpful for the efficient production of functional dairy products with high CLA contents.