Effects of energy intake and body weight on physical and chemical body composition in growing entire male pigs

Two experiments were conducted to determine independent effects of BW and DE intake on body composition and the partitioning of retained body energy between lipid and protein in pigs with high lean tissue growth potentials and when energy intake limited whole-body protein deposition. In a preliminary N-balance experiment involving 20 entire male pigs at either 30 or 100 kg BW, it was established that whole-body protein deposition increased linearly (P < 0.05) with DE intake at both BW. These results indicate that DE intake controlled whole-body protein deposition and that these pigs did not achieve their maximum whole-body protein deposition when fed semi-ad libitum. In the main serial slaughter experiment, 56 pigs, with a BW of 15 kg, were assigned to one of four DE intake schemes and slaughtered at 40, 65, 90, or 115 kg BW. Within DE intake schemes, DE intake was increased linearly (P < 0.05) with BW, allowing for an assessment of effects of DE intake and slaughter BW on chemical and physical body composition (carcass, viscera, blood). Between 15 and 90 kg BW, average DE intake of 16.1, 20.9, 25.2, and 28.8 MJ/d supported average BW gains of 502, 731, 899, and 951 g/d, respectively. The proportion of whole-body protein present in the carcass increased with BW and decreased with DE intake (P < 0.05), whereas the distribution of whole-body lipid between carcass and viscera was not influenced by BW and DE intake. A mathematical relationship was developed to determine the relationship between DE intake at slaughter (MJ/d) and chemical body composition in these pigs: whole-body lipid-to-protein ratio = 1.236 - 0.056 x (DE intake) + 0.0013 x (DE intake)2, r2 = 0.71. The data suggests that absolute DE intake alone was an adequate predictor of chemical body composition in this population of entire male pigs over the BW and DE intake ranges that were evaluated, simplifying the characterization of this aspect of nutrition partitioning for growth in different pig populations.     

Efficiency of utilizing ileal digestible lysine and threonine for whole body protein deposition in growing pigs is reduced when dietary casein is replaced by wheat shorts

To determine the effect of dietary inclusion level of wheat shorts (WS; a high nonstarch poly-saccharide-containing feed ingredient) and casein (CS; a control) on the efficiency of utilizing ileal digestible Lys (kLys) and Thr (kThr) for whole body protein deposition (PD) in the growing pig, 2 separate N-balance studies were conducted with either Lys or Thr as first-limiting AA in cornstarch-based diets. For the Lys study, a basal diet (L-basal) was formulated to contain 0.24 g of standardized ileal digestible (SID) Lys per MJ of DE, to which 0.095 or 0.19 g of SID Lys per MJ of DE were added using either CS (L-CS2 or L-CS3, respectively) or WS (L-WS2 or L-WS3, respectively). A sixth diet was evaluated that was similar to L-CS3 but to which 6% pectin (L-pectin) was added as a source of soluble nonstarch polysaccharides. For the Thr study, the basal diet (T-basal) was formulated to contain 0.14 g of SID Thr per MJ of DE, to which 0.055 or 0.11 g of SID Thr per MJ of DE were added from CS (T-CS2 or T-CS3, respectively) or from WS (T-WS2 and T-WS3, respectively). A sixth diet was evaluated that was similar to T-CS3 but to which 6% pectin was added (T-pectin). Increasing SID Lys intake from CS did not influence kLys for PD (P > 0.10), whereas increasing SID Lys intake from WS reduced kLys for PD (P = 0.001; 89 vs. 79%). Inclusion of 6% pectin had no effect on kLys for PD (P > 0.10). Increasing SID Thr intake from CS also did not influence kThr for PD (P > 0.10), whereas kThr for PD was reduced at the greatest dietary inclusion level of WS (P < 0.001; 90 vs. 77%). Pectin inclusion had no effect on kThr for PD (P > 0.10). The inefficiency of utilizing ileal digestible Lys intake for PD may be attributed to nonreactive Lys in WS. The negative impact of including high levels of WS in the diet of pigs on kThr seems to be associated with fiber content of WS; it was not related to increased endogenous ileal AA losses at the distal ileum. The impact of dietary AA source on the use of ileal digestible Lys and Thr for PD, or other body functions, is substantial and should be considered in the formulation of pig diets. Further research is warranted to elucidate the mechanisms contributing to substantial dietary effects on Thr use for PD.     

True ileal amino acid digestibility and endogenous ileal amino acid losses in growing pigs fed wheat shorts- or casein-based diets

Use of dietary AA in growing pigs reflects digestion and use of digested AA for various body functions. Before evaluating dietary effects on use of digestible AA intake for body protein deposition, a digestibility study was conducted to investigate true ileal AA digestibility and endogenous ileal AA losses in growing pigs fed graded levels of wheat shorts (WS) or casein (CS; control). A casein-based basal diet (basal) was formulated to contain 0.27 g of standardized ileal digestible (SID) Lys per MJ of DE, to which extra Lys was added from WS (WS2, +0.10 g of SID Lys per MJ of DE; WS3, +0.20 g of SID Lys per MJ of DE) or casein (CS3, +0.20 g of SID Lys per MJ of DE). A fifth diet was formulated to be similar in CP level and source as CS3 but in which 6% pectin, a source of soluble non-starch polysaccharides (NSP), was included at the expense of cornstarch (CS3 + pectin). Five Yorkshire barrows (17.5 +/- 1.5 kg of BW) were fitted with a T-cannula at the distal ileum and randomly assigned to 1 of the 5 experimental diets in a 5 x 5 Latin Square design. Apparent ileal digestibility (AID), true ileal digestibility (TID), and endogenous ileal protein losses (EPL) were determined using the homoarginine method. Diet CS level did not influence (P > or = 0.10) TID of most essential AA or EPL (10.4 g/kg of DM intake). Including pectin in the diet did not influence TID of AA (P > or = 0.10) but increased EPL (15.6 g/kg of DM intake; P > or = 0.01). Inclusion of WS in the diet reduced TID of most essential AA (P < 0.01). The TID values for most essential AA, however, were the same (P > or = 0.10) for both dietary WS levels, except for Lys and Met, which were further reduced at the greatest dietary WS level. Increased EPL (P < 0.01) was only observed for WS3 (16 g/kg of DMI). We concluded that (1) the effects of dietary protein source on AID of AA can be attributed both to reduced TID of AA and increased EPL, (2) the impact of dietary WS level on TID of AA and EPL does not seem to be linear, (3) soluble NSP from pectin or WS exerts a greater effect on EPL than insoluble NSP, and (4) because of the metabolic cost associated with EPL and the impacts of feed composition on microbial fermentation in the gut lumen, the effects of feed ingredients on the use of ileal digestible AA for protein deposition should be investigated further.     

A paramagnetic bonding mechanism for diatomics in strong magnetic fields

Elementary chemistry distinguishes two kinds of strong bonds between atoms in molecules: the covalent bond, where bonding arises from valence electron pairs shared between neighboring atoms, and the ionic bond, where transfer of electrons from one atom to another leads to Coulombic attraction between the resulting ions. We present a third, distinct bonding mechanism: perpendicular paramagnetic bonding, generated by the stabilization of antibonding orbitals in their perpendicular orientation relative to an external magnetic field. In strong fields such as those present in the atmospheres of white dwarfs (on the order of 10(5) teslas) and other stellar objects, our calculations suggest that this mechanism underlies the strong bonding of H(2) in the (3)Σ(u)(+)(1σ(g)1σ(u)*) triplet state and of He(2) in the (1)Σ(g)(+)(1σ(g)(2)1σ(u)(*2)) singlet state, as well as their preferred perpendicular orientation in the external field.     

Upfront denileukin diftitox as in vivo regulatory T-cell depletion in order to enhance vaccination effects in a canine allogeneic hematopoietic stem cell transplantation model

Denileukin Diftitox (ONTAK^®, DAB₃₈₉ IL-2) is a recombinant DNA-derived fusion protein depleting cells that express high-affinity IL-2 receptor. Important cell targets are CD4⁺CD25⁺Foxp3⁺ regulatory T cells (T_reg). Elimination of immunosuppressive T_reg by Denileukin Diftitox may provide a way to modulate immune tolerance following stem cell transplantation. Here, we combined T_reg depletion with a vaccination approach to induce donor-specific immune reactions. To investigate this approach we chose the mixed chimerism canine stem cell transplantation model which represents a high state of tolerance between two hematopoietic systems. The aim was therefore to induce a graft versus hematopoiesis effect thereby converting mixed to full donor chimerism. Dog leukocyte antigen identical siblings that had developed a stable mixed chimerism after non-myeloablative stem cell transplantation received a single dose of Denileukin Diftitox (18 μg/kg, i.v.) followed by several cell-lysate vaccinations. Host peripheral blood mononuclear cell lysates combined with CpG-ODN, and Montanide^® ISA 51 were locally applied. In vitro studies demonstrated that canine T_reg are a target of Denileukin Diftitox. The suppression of T-cell proliferation by T_reg was abolished by addition of Denileukin Diftitox (10 nM). An increase of proliferation of median 300% (range: 200%–425%) was observed. No change in donor chimerism was observed after administration of Denileukin Diftitox and vaccination. This study highlights that application of Denileukin Diftitox resulted in a depletion of T_reg followed by an increase of immune response in vitro. This effect could not be confirmed in vivo even if the immune system was stimulated by vaccinations.     

Efficiency of spatio-temporal vaccination regimes in wildlife populations under different viral constraints

ABSTRACT: Classical Swine Fever (CSF) is considered an endemic disease in European wild boar populations. In view of the high economic impact of the introduction of the virus into domestic pig units, huge efforts are invested in the preventive control of CSF in wild boar populations. Recent European Community guidelines favour oral mass vaccination against CSF in wild boar populations. The guidelines are explicit on the temporal structure of the vaccination protocol, but little is known about the efficacy of different spatial application schemes, or how they relate to outbreak dynamics.We use a spatially explicit, individual-based wild boar model that represents the ecology of the hosts and the epidemiology of CSF, both on a regional scale and on the level of individual course of infection. We simulate adaptive spatial vaccination schemes accounting for the acute spread of an outbreak while using the temporal vaccination protocol proposed in the Community guidelines.Vaccination was found to be beneficial in a wide range of scenarios. We show that the short-term proactive component of a vaccination strategy is not only as decisive as short-term continuity, but also that it can outcompete alternative practices while being practically feasible. Furthermore, we show that under certain virus-host conditions vaccination might actually contribute to disease persistence in local populations.     

Comparative evaluation of live marker vaccine candidates "CP7_E2alf" and "flc11" along with C-strain "Riems" after oral vaccination

Due to the tremendous socio-economic impact of classical swine fever (CSF) outbreaks, emergency vaccination scenarios are continuously under discussion. Unfortunately, all currently available vaccines show restrictions either in terms of marker capacities or immunogenicity. Recent research efforts were therefore directed at the design of new modified live marker vaccines. Among the most promising candidates the chimeric pestiviruses "CP7_E2alf" and "flc11" were identified. Within an international research project, these candidates were comparatively tested in challenge experiments after a single oral vaccination. Challenge infection was carried out with highly virulent CSF virus strain "Koslov", 14 or 21 days post vaccination (dpv), respectively. Safety, efficacy, and marker potential were addressed. All assessments were done in comparison with the conventional "gold standard" C-strain "Riems" vaccine. In addition to the challenge trials, multiple vaccinations with both candidates were performed to further assess their marker vaccine potential. All vaccines were safe and yielded full protection upon challenge 21 days post vaccination. Neither serological nor virological investigations showed major differences among the three vaccines. Whereas CP7_E2alf also provided clinical protection upon challenge at 14 days post vaccination, only 50% of animals vaccinated with flc11, and 83% vaccinated with C-strain "Riems" survived challenge at this time point. No marked differences were seen in protected animals. Despite the fact that all multiple-vaccinated animals stayed sero-negative in the accompanying marker test, the discriminatory assay remains a weak point due to delayed or inexistent detection of some of the vaccinated and subsequently infected animals. Nevertheless, the potential as live marker vaccines could be confirmed for both vaccine candidates. Future efforts will therefore be directed at the licensing of "Cp7_E2alf" as the first live marker vaccine for CSF.     

现代新型农业种植模式与推广

随着社会经济的快速发展,我国农业进入转型升级的关键时期,面临着更多的机遇和挑战,唯有加快推动农业发展方式的转变,提升农业质量、效益和竞争力,才能夯实农业发展的根基,确保农民收入的稳定增加。通过对我国传统农业向现代化新型农业转型过程中存在问题的深入分析,探索适合我国国情的现代新型农业模式和农业科技服务体系的构建,并在此基础上预测现代新型农业的发展趋势和推广策略,坚持走优质、高效和绿色的农业生态道路,推动农业的可持续发展。