The objectives of this study were to determine: (1) the effect of wheat dried distillers grain with solubles (DDGS) inclusion, and (2) dietary feed enzyme (FE; Econase XT) supplementation in a finishing diet containing wheat DDGS on fatty acid profile of the pars costalis diaphragmatis muscle of beef cattle. A total of 160 crossbred yearling steers with initial BW of 495±38 kg were blocked by BW and randomized into 16 pens (10 head/pen). The pens were randomly assigned to one of the four treatments: (1) control (CON; 10% barley silage and 90% barley grain-based concentrate, dry matter (DM) basis); (2) diet containing 30% wheat DDGS in place of barley grain without FE (WDG); (3) WDG diet supplemented with low FE (WDGL; 1 ml FE/kg DM); and (4) WDG diet supplemented with high FE (2 ml FE/kg DM). The pars costalis diaphragmatis muscle samples were collected from cattle at slaughter at the end of the finishing period (120 days) with a targeted live weight of 650 kg. No differences in organic matter intake, final BW and average daily gain were observed among treatments. However, steers fed WDG had greater (P<0.01) feed conversion ratio than those fed CON, and increasing FE application in wheat DDGS-based diets tended (P<0.10) to linearly decrease feed conversion ratio. In assessing the effects of including WDG diets without FE, concentration of total polyunsaturated fatty acids (PUFA) in muscle tended to be greater (P<0.10) for steers fed WDG than steers fed CON. In addition, inclusion of wheat DDGS into the diet increased (P<0.05) concentration of CLA and vaccenic acid (VA) in muscle and also resulted in a higher (P<0.05) ratio of n-6/n-3 PUFA compared with that from steers fed CON diet. Increasing FE application in wheat DDGS-based diets did not modify the concentrations of individual or total fatty acids. These results suggest that inclusion of wheat DDGS in finishing diets may improve fatty acid profile of beef muscle which could benefit human health.

The value of added feed enzymes (FE) in promoting growth and efficiency of nutrient utilisation is well recognised in single-stomached animal production. However, the effects of FE on the microbiome of the gastrointestinal tract (GIT) are largely unrecognised. A critical role in host nutrition, health, performance and quality of the products produced is played by the intestinal microbiota. FE can make an impact on GIT microbial ecology by reducing undigested substrates and anti-nutritive factors and producing oligosaccharides in situ from dietary NSP with potential prebiotic effects. Investigations with molecular microbiology techniques have demonstrated FE-mediated responses on energy utilisation in broiler chickens that were associated with certain clusters of GIT bacteria. Furthermore, investigations using specific enteric pathogen challenge models have demonstrated the efficacy of FE in modulating gut health. Because FE probably change the substrate characteristics along the GIT, subsequent microbiota responses will vary according to the populations present at the time of administration and their reaction to such changes. Therefore, the microbiota responses to FE administration, rather than being absolute, are a continuum or a population of responses. However, recognition that FE can make an impact on the gut microbiota and thus gut health will probably stimulate development of FE capable of modulating gut microbiota to the benefit of host health under specific production conditions. The present review brings to light opportunities and challenges for the role of major FE (carbohydrases and phytase) on the gut health of poultry and swine species with a specific focus on the impact on GIT microbiota.

Rice bran constitutes about 10% of brown rice and is used as an animal feed. There are 40–45 million tonnes of rice bran produced annually, mainly in the Far East and South-east Asia. In these areas hull adulteration can occur, reducing the quality of the bran. This can now be detected by a simple colormetric method. Rancidity is a major problem due to the high oil content of the bran. Rapid hydrolysis of the oil is followed by oxidation with the changes being accelerated in warm, humid conditions. The effects on nutritive value and acceptability are unclear. An analysis of Australian produced rice bran (on a dry matter basis) gives a mean crude protein concentration of 150 g/kg, ether extract of 220 g/kg and neutral detergent fibre of 220 g/kg. The amino acid profile is generally superior to that of cereal grains. Digestibility of the oil is much less in young chickens than in adult birds resulting in a 28–35% lower metabolizable energy (ME) depending on cultivar. Equations for predicting the ME of rice bran for birds at different ages, and chemical components from rice hull content of rice bran are given. Digestibility of amino acids in rice bran is also lower for young chickens than adult birds. Inclusion of rice bran in chicken diets in excess of 20% frequently depresses growth, but higher levels can be tolerated by ducklings. Results with ducklings suggest that the composition of the basal diet to some extent influences the response of birds when rice bran is included in the diet. The inclusion of animal protein elicits an improved performance compared with that of an all-vegetable based diet. Defatted rice bran (DFRB) gives the same performance as full fat bran when equalized for ME. Laying birds can tolerate high levels of rice bran. Although some reports indicate successful inclusion of well above 600 g/kg, a practical upper limit of 450 g/kg seems to be accepted. Defatted rice bran at 250 g/kg diet resulted in leg problems, increased mortality and reduced egg output. Shell grit alleviated the problem. So far, attempts to improve the nutritive value of rice bran through addition of feed enzymes have had limited success. Feed phytase has been successful in releasing phosphorus from phytate in rice bran which is present at up to 50 g/kg dry matter. Improving the nutritional value of rice bran by heat treatment is probably not economical, although extrusion cooking will stabilize the oil before extraction and is used to stabilize rice bran for human food. Feed enzymes may be effective when a suitable combination is found.