The association between faecal host DNA or faecal calprotectin and feed efficiency in pigs fed yeast-enriched protein concentrate

Gut cell losses contribute to overall feed efficiency due to the energy requirement for cell replenishment. Intestinal epithelial cells are sloughed into the intestinal lumen as digesta passes through the gastrointestinal tract, where cells are degraded by endonucleases. This leads to fragmented DNA being present in faeces, which may be an indicator of gut cell loss. Therefore, measuring host faecal DNA content could have potential as a non-invasive marker of gut cell loss and result in a novel technique for the assessment of how different feed ingredients impact upon gut health. Faecal calprotectin (CALP) is a marker of intestinal inflammation. This was a pilot study designed to test a methodology for extracting and quantifying DNA from pig faeces, and to assess whether any differences in host faecal DNA and CALP could be detected. An additional aim was to determine whether any differences in the above measures were related to the pig performance response to dietary yeast-enriched protein concentrate (YPC). Newly weaned (∼26.5 days of age) Large White × Landrace × Pietrain piglets (8.37 kg ±1.10, n = 180) were assigned to one of four treatment groups (nine replicates of five pigs), differing in dietary YPC content: 0% (control), 2.5%, 5% and 7.5% (w/w). Pooled faecal samples were collected on days 14 and 28 of the 36-day trial. Deoxyribonucleic acid was extracted and quantitative PCR was used to assess DNA composition. Pig genomic DNA was detected using primers specific for the pig cytochrome b (CYTB) gene, and bacterial DNA was detected using universal 16S primers. A pig CALP ELISA was used to assess gut inflammation. Dietary YPC significantly reduced feed conversion ratio (FCR) from weaning to day 14 (P0.05). Faecal CALP levels were significantly higher at day 14 compared with day 28, but there was no effect of YPC inclusion and no relationship with FCR. In conclusion, YPC reduced faecal CYTB DNA content and this correlated positively with FCR, but was unrelated to gut inflammation, suggesting that it could be a non-invasive marker of gut cell loss. However, further validation experiments by an independent method are required to verify the origin of pig faecal CYTB DNA as being from sloughed intestinal epithelial cells

Advances in research on the prenatal development of skeletal muscle in animals in relation to the quality of muscle-based food. I. Regulation of myogenesis and environmental impact

Skeletal muscle development in vertebrates – also termed myogenesis – is a highly integrated process. Evidence to date indicates that the processes are very similar across mammals, poultry and fish, although the timings of the various steps differ considerably. Myogenesis is regulated by the myogenic regulatory factors and consists of two to three distinct phases when different fibre populations appear. The critical times when myogenesis is prone to hormonal or environmental influences depend largely on the developmental stage. One of the main mechanisms for both genetic and environmental effects on muscle fibre development is via the direct action of the growth hormone–insulin-like growth factor (GH–IGF) axis. In mammals and poultry, postnatal growth and function of muscles relate mainly to the hypertrophy of the fibres formed during myogenesis and to their fibre-type composition in terms of metabolic and contractile properties, whereas in fish hyperplasia still plays a major role. Candidate genes that are important in skeletal muscle development, for instance, encode for IGFs and IGF-binding proteins, myosin heavy chain isoforms, troponin T, myosin light chain and others have been identified. In mammals, nutritional supply in utero affects myogenesis and the GH–IGF axis may have an indirect action through the partitioning of nutrients towards the gravid uterus. Impaired myogenesis resulting in low skeletal myofibre numbers is considered one of the main reasons for negative long-term consequences of intrauterine growth retardation. Severe undernutrition in utero due to natural variation in litter or twin-bearing species or insufficient maternal nutrient supply may impair myogenesis and adversely affect carcass quality later in terms of reduced lean and increased fat deposition in the progeny. On the other hand, increases in maternal feed intake above standard requirement seem to have no beneficial effects on the growth of the progeny with myogenesis not or only slightly affected. Initial studies on low and high maternal protein feeding are published. Although there are only a few studies, first results also reveal an influence of nutrition on skeletal muscle development in fish and poultry. Finally, environmental temperature has been identified as a critical factor for growth and development of skeletal muscle in both fish and poultry.COST action 92

Advances in research on the prenatal development of skeletal muscle in animals

Selective breeding is an effective tool to improve livestock. Several selection experiments have been conducted to study direct selection responses as well as correlated responses in traits of skeletal muscle growth and function. Moreover, comparisons of domestic with wild-type species and of extreme breeds provide information on the genetic background of the skeletal muscle phenotype. Structural muscular components that differed with increasing distance in lean growth or meat quality in mammals were found to be myofibre number, myofibre size, proportions of fibre types as well as the numbers and proportions of secondary and primary fibres. Furthermore, markers of satellite cell proliferation, metabolic enzyme activities, glycogen and fat contents, the expression of myosin heavy chain isoforms, of activated AMPKa and other proteins in skeletal muscle tissue and circulating IGF1 and IGF-binding proteins have been identified to be involved in selection responses observed in pigs, cattle and/or chicken. The use of molecular methods for selective breeding of fish has only recently been adopted in aquaculture and studies of the genetic basis of growth and flesh quality traits are scarce. Some of the molecular markers of muscle structure/metabolism in livestock have also been identified in fish, but so far no studies have linked them with selection response. Genome scans have been applied to identify genomic regions exhibiting quantitative trait loci that control traits of interest, for example, muscle structure and meat quality in pigs and growth rate in chicken. As another approach, polymorphisms in candidate genes reveal the relationship between genetic variation and target traits. Thus, in large-scale studies with pigs’ associations of polymorphisms in the HMGA2, CA3, EPOR, NME1 and TTN genes with traits of carcass and meat quality were detected. Other studies revealed the significance of mutations in the IGF2 and RYR1 genes for carcass lean and muscle fibre traits in pigs. Mutations in the myostatin (MSTN) gene in fish were also examined. Advances in research of the genetic and environmental control of traits related to meat quality and growth have been made by the application of holistic ‘omics’ techniques that studied the whole muscle-specific genome, transcriptome and proteome in relation to muscle and meat traits, the development of new methods for muscle fibre typing and the adaptation of biophysical measures to develop parameters of muscle fibre traits as well as the application of in vitro studies. Finally, future research priorities in the field are defined.COST action 92