The applications of conventional culture-dependent assays to quantify bacteria populations are limited by their dependence on the inconsistent success of the different culture-steps involved. In addition, some bacteria can be pathogenic or a source of endotoxins and pose a health risk to the researchers. Bacterial quantification based on the real-time PCR method can overcome the above-mentioned problems. However, the quantification of bacteria using this approach is commonly expressed as absolute quantities even though the composition of samples (like those of digesta) can vary widely; thus, the final results may be affected if the samples are not properly homogenized, especially when multiple samples are to be pooled together before DNA extraction. The objective of this study was to determine the correlation coefficients between four different methods of expressing the output data of real-time PCR-based bacterial quantification. The four methods were: (i) the common absolute method expressed as the cell number of specific bacteria per gram of digesta; (ii) the Livak and Schmittgen, ΔΔCt method; (iii) the Pfaffl equation; and (iv) a simple relative method based on the ratio of cell number of specific bacteria to the total bacterial cells. Because of the effect on total bacteria population in the results obtained using ΔCt-based methods (ΔΔCt and Pfaffl), these methods lack the acceptable consistency to be used as valid and reliable methods in real-time PCR-based bacterial quantification studies. On the other hand, because of the variable compositions of digesta samples, a simple ratio of cell number of specific bacteria to the corresponding total bacterial cells of the same sample can be a more accurate method to quantify the population.

Effects of grape pomace and vitamin E on performance, antioxidant status, immune response, gut morphology and histopathological responses in broiler chickens

An experiment was conducted on broiler chickens to study the effects of different dietary fats (Conjugated linoleic acid (CLA), fish oil, soybean oil, or their mixtures, as well as palm oil, as a more saturated fat), with a as fed dose of 7% for single fat and 3.5 + 3.5% for the mixtures, on Peroxisome Proliferator-Activated Receptors (PPARs) gene expression and its relation with body fat deposits. The CLA used in this experiment was CLA LUTA60 which contained 60% CLA, so 7% and 3.5% dietary inclusions of CLA LUTA60 were equal to 4.2% and 2.1% CLA, respectively. Higher abdominal fat pad was found in broiler chickens fed with a diet containing palm oil compared to chickens in the other experimental groups (P ≤ 0.05). The diets containing CLA resulted in an increased fat deposition in the liver of broiler chickens (P ≤ 0.05). The only exception was related to the birds fed with diets containing palm oil or fish oil + soybean oil, where contents of liver fat were compared to the CLA + fish oil treatment. PPARγ gene in adipose tissue of chickens fed with palm oil diet was up-regulated compared to other treatments (P ≤ 0.001), whereas no significant differences were found in adipose PPARγ gene expression between chickens fed with diets containing CLA, fish oil, soybean oil or the mixture of these fats. On the other hand, the PPARα gene expression in liver tissue was up-regulated in response to the dietary fish oil inclusion and the differences were also significant for both fish oil and CLA + fish oil diets compared to the diets with palm oil, soybean oil or CLA as the only oil source (P ≤ 0.001). In conclusion, the results of present study showed that there was a relationship between the adipose PPARγ gene up-regulation and abdominal fat pad deposition for birds fed with palm oil diet, while no deference was detected in n-3 and n-6 fatty acids, as well as CLA on PPARγ down regulation in comparison to a more saturated fat. When used on its own, fish oil was found to be a more effective fat in up-regulating hepatic PPARα gene expression and this effect was related to a less fat deposition in liver tissue. A negative correlation coefficient (−0.3) between PPARα relative gene expression and liver tissue fat content confirm the anti-lipogenic effect of PPARα, however, the change in these parameters was not completely parallel.

This experiment was carried out to assess the following hypothesis: feeding broiler to fine insoluble fibre in the diet will result in improved gut morphology and enhanced performance. In this experiment, 200 broiler chickens in 20 pen cages with wood shaving-lined floors were exposed to five treatment groups with four pens/treatment: control diet, diets contained 0.75 or 1.5% barley hulls or diets contained 0.75 or 1.5% rice hulls in a completely randomised design with five treatment, four replicate and 20 chicks each. Type of fibre influenced the performance and digestive traits of broilers with effects varying in accordance with the level of fibre. Rice hulls inclusion consistently improved growth performance and crude protein (CP) digestibility in broilers regardless of dietary inclusion level (p < 0.05). However, barley hulls at 1.5% level improved crypt depth: villous height (VH) ratio and feed conversion ratio had an opposite effect on VH (p < 0.05). The beneficial effects of hulls were more obvious with the 1.5% dietary inclusion level than the 0.75% level. The useful effects of rice hulls inclusion on broiler efficiency was mainly because of its effect on CP digestibility while barley hulls at 1.5% level positively changed jejunum morphology. The data suggest that broilers may have a nominal requirement for insoluble fibre, however, the source and dietary inclusion rate of fibre might be important factors to satisfy dietary fibre requirements in birds.

The relationships between metabolic pathways, nutrients and genes are the basis of the majority of current studies on poultry. The rapid advance of biochemical and molecular tools has now made it possible to understand the molecular base of important phenotypic characteristics. Fats are the main storage source of energy in animal body with important role in cell membrane structure, gene regulation and precursors of important regulatory metabolites. From a functional point of view, it has been suggested that dietary fats change liver fatty acid synthesis and other lipogenic enzymes by regulating mRNA synthesis. Nuclear hormone receptors are defined as ligand-activated transcription factors which directly and indirectly regulate a number of genes involved in lipid metabolism and inflammatory signalling. The peroxisome proliferator-activated receptors (PPARs) are members of the nuclear hormone receptor superfamily of transcription factors. PPARs are involved in cellular differentiation, insulin sensitisation, cancer, atherosclerosis and several metabolic diseases. Three distinct PPAR genes have been recognised as α, δ and γ. The most important metabolic effect of PPARγ is its role in adipogenesis. PPARγ is a central gene regulator in adipose tissue and stimulate the expression of several genes involved in adipogenesis. Based upon examples taken from chicken lipid metabolism, it is possible to draw lessons from the study of PPARγ functions in order to approach the study of gene expression PPARγ functions regulatory pathways interactions.