The challenge to reduce crude protein contents of wheat-based broiler diets

The challenge to reduce crude protein (CP) contents of wheat-based broiler diets is both justified and formidable because the performance of broiler chickens offered reduced-CP, wheat-based diets is usually compromised. Moreover, broiler chickens offered wheat-based diets do not accommodate CP reductions as well as do those offered maize-based diets; this appears to stem from the higher protein concentrations and more rapid starch digestion rates of wheat. The higher protein concentrations of wheat than maize result in elevated inclusion levels of non-bound (synthetic, crystalline) amino acids (NBAA). This may be an impediment, because non-bound and protein-bound amino acids are not bioequivalent and intestinal uptakes of NBAA are more rapid than their protein-bound counterparts. This leads to post-enteral amino acid imbalances and the deamination of surplus amino acids, which generates ammonia (NH3). Because NH3 is inherently detrimental, it must be detoxified and eliminated as uric acid, which attracts metabolic costs. Moreover, inadequate NH3 detoxification may seriously compromise broiler growth performance. Also, consideration is given to some intrinsic wheat factors, including soluble non-starch polysaccharides, amylase–trypsin inhibitors and gluten, that may hold relevance. Several strategies are proposed that may enhance the performance of birds offered reduced-CP, wheat-based diets, including capping dietary starch:protein ratios, blending wheat with sorghum, whole-grain feeding in association with phytase, dietary inclusions of L-carnitine and the use of protected or slow-release amino acids. In future research, it should prove instructive to compare different wheats with a wide range of protein contents that, importantly, have been fully characterised for relevant parameters, to ascertain the most appropriate properties. The successful development and adoption of reduced-CP, wheat-based diets would be an enormous advantage for the Australian chicken-meat industry as it would diminish the huge dependence on imported, expensive soybean meal

Effects of phytase inclusions in diets containing ground wheat or 12.5% whole wheat (pre- and post-pellet) and phytase and protease additions, individually and in combination, to diets containing 12.5% pre-pellet whole wheat on the performance of broiler chickens

Each of eight dietary treatments was offered to seven replicates (six birds per cage) of male Ross 308 chicks from 7 to 28 days post-hatch. The diets contained 741 g/kg wheat incorporated as ground (3.2 mm hammer-mill screen) wheat or 125 g/kg whole wheat included in diets, either pre- or post-pelleting. In Experiment 1 of the study, ground grain, pre-pellet and post-pellet whole grain diets were offered with and without phytase as a 3 × 2 factorial array of treatments. The effects of dietary treatments on gizzard and pancreas weights, bone mineralisation, excreta dry matter, growth performance, nutrient utilisation, digestibility coefficients and disappearance rates of starch and protein (N) in four small intestinal segments were determined. Post-pellet whole grain addition significantly increased gizzard weight by 12.5% (18.17 versus 16.15 g/kg;

The interactions of exogenous phytase with whole grain feeding and effects of barley as the whole grain component in broiler diets based on wheat, sorghum and wheat-sorghum blends

The objectives of this experiment were two-fold; the first was to evaluate exogenous phytase in either conventional or whole grain diets as a 2 × 2 factorial treatment array. Wheat-sorghum blended rations containing 12.5% ground or whole barley were offered without and with 1000 FTU/kg exogenous phytase. The second objective was to evaluate barley as the whole grain component in diets based on wheat, sorghum and equal wheat-sorghum blends as a 3 × 2 factorial treatment array. Rations based on wheat, sorghum and wheat-sorghum blends were offered as an intact pellet containing 12.5% ground barley or offered as a mix of 12.5% whole barley and a pelleted concentrate. Each of the dietary treatments was offered to 7 replicates (6 birds per cage) of male Ross 308 chicks from 7 to 28 days post-hatch. Treatment effects on growth performance, gizzard and pancreas weights, gizzard pH, bone mineralisation, nutrient utilisation, digestibility coefficients of starch and protein (N) and starch:protein disappearance rate ratios in four small intestinal segments (proximal and distal jejunum, proximal and distal ileum), excreta dry matter and incidence of dilated proventriculi were determined. In the 2 × 2 analysis there was a significant (

In Vivo RNA Interference Screens Identify Regulators of Antiviral CD4+ and CD8+ T Cell Differentiation

SummaryClassical genetic approaches to examine the requirements of genes for T cell differentiation during infection are time consuming. Here we developed a pooled approach to screen 30–100+ genes individually in separate antigen-specific T cells during infection using short hairpin RNAs in a microRNA context (shRNAmir). Independent screens using T cell receptor (TCR)-transgenic CD4+ and CD8+ T cells responding to lymphocytic choriomeningitis virus (LCMV) identified multiple genes that regulated development of follicular helper (Tfh) and T helper 1 (Th1) cells, and short-lived effector and memory precursor cytotoxic T lymphocytes (CTLs). Both screens revealed roles for the positive transcription elongation factor (P-TEFb) component Cyclin T1 (Ccnt1). Inhibiting expression of Cyclin T1, or its catalytic partner Cdk9, impaired development of Th1 cells and protective short-lived effector CTL and enhanced Tfh cell and memory precursor CTL formation in vivo. This pooled shRNA screening approach should have utility in numerous immunological studies

Effects of reducing dietary crude protein and whole grain feeding on performance and amino acid metabolism in broiler chickens offered wheat-based diets

A total of 336 off-sex, male Ross 308 chicks were offered seven dietary treatments from 7 to 35 days post-hatch; each treatment was offered to eight replicate cages with six birds per cage. Three wheat-based diets were formulated to declining crude protein (CP) levels of 215, 190 and 165 g/kg but with a constant energy density (12.70 MJ/kg), electrolyte balance (250 mEq/kg) and digestible lysine level (11.00 g/kg). In a 2 × 3 factorial arrangement birds were offered either 215 or 165 g/kg CP diets to which 0%, 12.5% and 25.0% whole gain was incorporated post-pelleting. In addition, a ground grain, 190 g/kg CP diet served as a seventh treatment. The assessed parameters included growth performance, relative gizzard, pancreas and abdominal fat-pad weights, nutrient utilisation, concentrations of free amino acid in portal (anterior mesenteric vein) and systemic (brachial vein) plasma and apparent jejunal and ileal amino acid digestibility coefficients and disappearance rates. The CP reduction from 215 to 165 g/kg compromised FCR by 5.99% (1.576 versus 1.487; P

Extending daily feed access intervals does not influence lysine HCl utilization but enhances amino acid digestibilities in broiler chickens

Off-sex, male Ross 308 chickens were offered maize-soy diets without and with 3.5 g/kg lysine monohydrochloride (HCl), which contained 10.0 or 12.8 g/kg digestible lysine, from 7 to 28 D post-hatch. Birds were permitted access to diets at intervals of 12, 16, and 20 h/day. Lysine HCl improved weight gain (1,465 vs. 1,417 g/bird; P 0.35) between lysine HCl and feed access intervals for parameters of growth performance were not observed, it was concluded that feed access intervals do not influence lysine utilization. The implications of these findings are discussed

Gene-Centric Meta-Analysis of Lipid Traits in African, East Asian and Hispanic Populations

Meta-analyses of European populations has successfully identified genetic variants in over 100 loci associated with lipid levels, but our knowledge in other ethnicities remains limited. To address this, we performed dense genotyping of ∼2,000 candidate genes in 7,657 African Americans, 1,315 Hispanics and 841 East Asians, using the IBC array, a custom ∼50,000 SNP genotyping array. Meta-analyses confirmed 16 lipid loci previously established in European populations at genome-wide significance level, and found multiple independent association signals within these lipid loci. Initial discovery and in silico follow-up in 7,000 additional African American samples, confirmed two novel loci: rs5030359 within ICAM1 is associated with total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) $(p = 8.8×10^{−7} and p = 1.5×10^{−6}$ respectively) and a nonsense mutation rs3211938 within CD36 is associated with high-density lipoprotein cholesterol (HDL-C) levels $(p = 13.5×10^{−12})$. The rs3211938-G allele, which is nearly absent in European and Asian populations, has been previously found to be associated with CD36 deficiency and shows a signature of selection in Africans and African Americans. Finally, we have evaluated the effect of SNPs established in European populations on lipid levels in multi-ethnic populations and show that most known lipid association signals span across ethnicities. However, differences between populations, especially differences in allele frequency, can be leveraged to identify novel signals, as shown by the discovery of ICAM1 and CD36 in the current report

A Novel Role for Dbx1-Derived Cajal-Retzius Cells in Early Regionalization of the Cerebral Cortical Neuroepithelium

Patterning of the cerebral cortex during embryogenesis depends not only on passive diffusion of morphogens but also on signal delivery by Cajal-Retzius neurons that migrate over long distances