Stepwise Reduction of Dietary Phosphorus in Diets for Piglets and Fattening Pigs of Different Genetic Origin Housed under Various Station Environments-A Ringtest.

The reduction of emissions of nutrients from livestock is one of the main topics in areas with intensive animal husbandry. In order to minimize the loss of nutrients into the environment, it is common practice to feed animals as close as possible to metabolic demands. For phosphorus (P), there are various studies for swine and poultry, which showed that a reduction of dietary P levels is possible, if a sufficient level of phytase is added to the diet. The supplementation of a sufficient dosage of phytase to plant-based diets leads to an increase in digestible phosphorus (dP) upon the hydrolisation of phytate (InsP6) to P and lower inositol-phosphates. However, most of these studies were conducted under standardized experimental conditions. In terms of transfer to practical conditions with varying housing, management and genetics, there are concerns that have led to speculation by farmers and veterinarians whether the reduction of dietary P could negatively affect bone health and therefore animal welfare. In order to test whether a reduction of dietary P according to the recommendations for dP of the German Society of Nutrition Physiology (GfE) affects bone mineralization and growth performance, a ringtest was conducted where piglets and fattening pigs were fed at four experimental stations with three centrally produced diets from the same batches. The diets contained three different levels of P and were designed to reflect practical diets. The P level decreased from diet one to three, respectively. Diets one and two were calculated to contain P levels, which are typically fed under practical conditions in Germany. The third diet was optimized to fulfill the requirements of dP by the GfE. The animals were fed in two phases as post-weaning piglets (8-15 kg and 15-28 kg BW) followed by a three-phase fattening regime (28-60 kg, 60-90 kg and 90-120 kg BW). Individual body weight and feed consumption (pen basis or individually, depending on the experimental station) were recorded for every feeding phase. At the end of the experiment, animals were slaughtered. At one experimental station, additional blood serum, metatarsi of the left leg and kidney tissue were sampled to analyze serum P concentration, expression of P transporters in the kidney and bone traits. In two experimental stations, femur and vertebra were sampled, and bone ash was determined. Overall, animal performance and all other traits analyzed did not differ between the treatment with the highest and the treatment with the lowest dietary P concentration. The results demonstrate that it is possible to decrease dietary P according to the recommendations for dP of the GfE, without impairing the animals' performance or mineral homeostasis and health. A reduction of total P by reducing mineral P to the levels of the present study require the supplementation of phytase to achieve sufficient concentrations of dP.

(13)C discrimination between diet, faeces, milk and milk components.

Stable isotope analysis is a fundamental tool in food origin and authenticity testing. Its use in livestock production requires knowledge of isotope discrimination between product and diet. Here, we report (13)C discrimination ((13)Δ) for milk, milk components (fat, casein and lactose) and faeces in eight lactating dairy cows, which grazed pasture or were fed fresh pasture herbage in the stall. Cows were supplemented with grain maize at 1.72 kg d(-1) (dry matter). Feed components were collected daily, and faeces, milk fat, casein, lactose and whole milk 4 times per week during an 8-week-long sampling period. Carbon isotope composition (δ(13)C) of each sample was analysed. δ(13)C was lowest in milk fat (-29.8‰) and highest in casein (-26.4‰). Compared to the diet, whole milk was depleted in (13)C ((13)Δ = 0.4‰) due to a strong (13)C-depletion of fat ((13)Δ = 2.2‰), which was not fully compensated by the (13)C-enrichment of casein ((13)Δ = -1.1‰) and lactose ((13)Δ = -0.7‰). Faeces were also depleted in (13)C ((13)Δ =1.7‰). Influences of feeding environment (stall vs. pasture) and herbage quality were minor (<0.4‰). A review of literature data shows large variation between studies. We consider that the present results are superior, as they are based on a much larger data set regarding the number of cows and milkings (total n = 256) with greater detail in analyses of diet and milk products. Also, the study covered both stall- and pasture-feeding scenarios in realistic settings with long periods of equilibration. This is the first comprehensive analysis of (13)C discrimination between diet and all main milk components (as well as faeces). Thus, the results will improve the use of stable isotope analyses in regard to authenticity testing and proof of origin.

Protection from diabetes development by single-chain antibody-mediated delivery of a NF-κB inhibitor specifically to ß-cells in vivo.

Recently, we reported the generation of single-chain antibodies (SCAs) highly specific for rodent and human ß-cells. Our current report describes the generation of a fusion protein of one of these SCAs (SCA B1) with a NF-κB essential modifier (NEMO)-binding domain (NBD) peptide, thereby creating a selective inhibitor of NF-κB activation in ß-cells. The SCA B1-NBD fusion protein was cloned in the pIRES-EGFP, expressed in bacteria, and purified by metal affinity chromatography; the newly generated complex was then administered intravenously to rodents and evaluated for its ability to protect ß-cells against cytokines in vitro and diabetogenic agents in vivo. First, it was shown clearly that our SCA B1-NBD fusion protein binds highly selective to CD rat ß-cells in vivo. Second, we observed that SCA B1-mediated in vivo delivery of the NBD peptide completely blocked IL-1ß + IFNγ- and TNFα + IFNγ-mediated induction of NF-κB as well as islet dysfunction in culture. Finally, repeated intravenous injection of SCA B1-NBD prior to multiple low-dose administration of streptozotocin in CD mice not only induced a striking resistance to diabetes development but also preserved ß-cell mass. In conclusion, our data show for the first time that a SCA B1-NBD fusion peptide reliably protects ß-cells against cytokines in vitro and allows protection from diabetes development in CD mice in vivo.