A semi-quantitative RT-PCR method to measure the in vivo effect of dietary conjugated linoleic acid on porcine muscle PPAR gene expression

Conjugated linoleic acid (CLA) can activate (in vitro) the nuclear transcription factors known as the peroxisome proliferators activated receptors (PPAR). CLA was fed at 11 g CLA/kg of feed for 45d to castrated male pigs (barrows) to better understand long term effects of PPAR activation in vivo. The barrows fed CLA had lean muscle increased by 3.5% and overall fat reduced by 9.2% but intramuscular fat (IMF %) was increased by 14% (P < 0.05). To measure the effect of long term feeding of CLA on porcine muscle gene expression, a semi-quantitative RT-PCR method was developed using cDNA normalized against the housekeeping genes cyclophilin and β-actin. This method does not require radioactivity or expensive PCR instruments with real-time fluorescent detection. PPARγ and the PPAR responsive gene AFABP but not PPARα were significantly increased (P < 0.05) in the CLA fed pig’s muscle. PPARα and PPARγ were also quantitatively tested for large differences in gene expression by western blot analysis but no significant difference was detected at this level. Although large differences in gene expression of the PPAR transcriptional factors could not be confirmed by western blotting techniques. The increased expression of AFABP gene, which is responsive to PPAR transcriptional factors, confirmed that dietary CLA can induce a detectable increase in basal PPAR transcriptional activity in the live animal

Phosphorus characterization in feces from broiler chicks fed low-phytate barley diets

The inclusion of low phytate grains in poultry diets can reduce the phosphorus (P) content of poultry feces, but their influence on fecal P composition is not well established. To assess this, 100 male broiler chicks (21 days old) were fed dietary treatments based on either a wild-type barley or one of three low phytate mutant barleys with 59, 62 and 99% reductions in phytate P, compared with the normal barley diet. The birds were housed in raised-floor battery cages with mesh grate floors above fecal collection trays with five birds per pen and five pens per treatment. The birds were fed for 9 days and feces were collected twice a day during the last 2 days of the experiment. Total P concentrations were 14-24% lower in feces from birds fed low phytate barley diets compared with those fed the normal barley diet. Phosphorus digestibility increased (P < 0.05) as phytate in the barley diet decreased. Phosphate was the major P fraction in the feces (69-75% extracted P) regardless of the type of barley fed. Phytate constituted only 3-12% of the P in the feces, indicating its hydrolysis in the bird. Overall, these results suggest that feeding low-phytate barley diets can reduce P concentrations in poultry feces without causing significant changes in P composition