Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 13, 2011
Publication Date: February 1, 2012
Citation: Weber, T.E., Kerr, B.J. 2012. Metabolic effects of dietary sugar beet pulp or wheat bran in growing female pigs. Journal of Animal Science. 90:523-532. Interpretive Summary: With increasing global demand for traditional feedstuffs, there is interest in using byproducts from the food and biofuels industries as dietary ingredients for swine. Sugar beet pulp and wheat bran are byproducts that are relatively high in fiber and were used in the current study to determine the impact of increasing the dietary level of fiber on growth performance and indices of energy metabolism. This experiment demonstrated that growing pigs can tolerate 12.5% of dietary sugar beet pulp or wheat bran without any negative effects on growth performance and that changes in the expression of certain genes and metabolites are involved in the adaptive response to dietary fiber. This information is important for scientists at universities, feed companies, and swine production facilities in that it demonstrates the pig's capacity to utilize dietary fiber from byproducts and candidate genes that may regulate the response to dietary fiber.
Technical Abstract: An experiment was conducted to determine the effects of feeding a moderate level of two different fiber sources on energy metabolites, mitochondrial biogenesis in intestine, liver and muscle, and the expression of some genes that regulate energy metabolism in intestine, liver, muscle, and adipose tissue. Female pigs (n = 36; BW 15.0 ± 0.7 kg) were fed diets containing no added fiber, 12.5% sugar beet pulp (SBP) or 12.5% wheat bran (WB) for 24 d. Blood samples were collected on d 7 and d 24 for cholesterol, glucose, NEFA, and triglycerides analysis. At completion of the experiment, ileum, colon, subcutaneous adipose, and LM samples were obtained from a subset (n = 6) pigs fed each diet for analysis of tissue mitochondrial DNA (mtDNA) content and mRNA levels by quantitative real-time PCR. Glycogen and triglyceride content of liver and LM were determined, and colon content VFA were also determined. The addition of SBP or WB to the diet had no effect on ADG, ADFI or G:F. Serum NEFA and triglycerides were increased (P < 0.05) in pigs fed SBP compared to pigs fed the control diet or WB on d 7, and NEFA remained increased (P < 0.05) on d 24 in pigs fed SBP. Dietary fiber had no effect on glycogen and triglyceride content of liver or LM, but colonic acetate levels were increased (P < 0.05) in pigs fed either SBP or WB. Pigs fed WB had an increased (P < 0.05) mtDNA content in ileum tissue and increased (P < 0.05) citrate synthase (CS) mRNA in colon tissue. In the liver, feeding either SBP or WB led to a decrease (P < 0.05) in mtDNA content, while in the LM feeding WB decreased (P < 0.05) mtDNA levels, and feeding either SBP or WB decreased (P < 0.05) expression levels of CS mRNA. Quantitative RT-PCR revealed that feeding WB increased (P < 0.05) proliferating cell nuclear antigen (PCNA) mRNA levels in ileum and colon. Feeding WB increased (P< 0.05) mRNA levels of a regulator of mitochondrial biogenesis, PPAR coactivator 1 alpha, in ileum tissue and increased (P < 0.05) mRNA levels of another mediator of mitochondrial biogensis, sirtuin 1, in colon tissue. Colonic mRNA expression level of fasting-induced adipose factor was increased (P < 0.05) in pigs fed either SBP or WB, and adipose triglyceride lipase mRNA level was increased (P < 0.05) in adipose tissue of pigs fed SBP. These data suggest that increasing dietary fiber can increase the capacity of the intestine for oxidative metabolism and induce a repartitioning of energy metabolites depending on fiber source.