Many studies have been conducted to improve economically important livestock traits such as feed efficiency and muscle growth. Genome editing technologies represent a major advancement for both basic research and agronomic biotechnology development. The clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 technical platform is a powerful tool used to engineer specific targeted loci. However, the potential occurrence of off‐target effects, including the cleavage of unintended targets, limits the practical applications of Cas9‐mediated genome editing. In this study, to minimize the off‐target effects of this technology, we utilized D10A‐Cas9 nickase to generate myostatin‐knockout (MSTN KO) chickens via primordial germ cells. D10A‐Cas9 nickase (Cas9n)‐mediated MSTN KO chickens exhibited significantly larger skeletal muscles in the breast and leg. Degrees of skeletal muscle hypertrophy and hyperplasia induced by myostatin deletion differed by sex and muscle type. The abdominal fat deposition was dramatically lower in MSTN KO chickens than in wild‐type chickens. Our results demonstrate that the D10A‐Cas9 technical platform can facilitate precise and efficient targeted genome engineering and may broaden the range of applications for genome‐edited chickens in practical industrialization and as animal models of human diseases.

Chicken as a food source is one of the most widespread domestic animals, and it has been used extensively as a research model. The clustered regularly interspaced short palindromic repeats (CRISPR)‐CRISPR‐associated protein 9 (Cas9) system is the most efficient and reliable tool for precise genome‐targeted modification and has generated considerable excitement for industrial applications, as well as biologic science. Unlike in mammals, germline‐transmittable primordial germ cells (PGCs) in chicken were used as an alternative strategy for the production of genetically altered chickens. Here, by combining the CRISPR‐Cas9 platform and germ cell‐mediated germline transmission, we generated G ₀ /G ₁ switch gene 2 ( G0S2 )knockout (KO)chickens, and G0S2 null KO chickens showed a dramatic reduction of abdominal fat deposition without affecting other economic traits. Additionally, G0S2 null KO chickens had altered fatty acid compositions in their blood and abdominal fat compared with wild‐type chickens under normal dietary conditions. The global mRNA sequencing data showed that G0S2 disruption in chickens would activate the adipose tissue‐specific peroxisomal oxidation pathway, and enoyl‐coenzyme A (CoA), hydratase/3‐hydroxyacyl CoA dehydrogenase might be a target molecule in metabolic homeostasis in the chicken adipose tissue. Our results demonstrate that the CRISPR‐Cas9 system with chicken PGCs can facilitate the production of specific genome‐edited chickens for practical applications, as well as basic research.—Park, T. S., Park, J., Lee, J. H., Park, J.‐W., Park, B.‐C., Disruption of G0/G1 switch gene 2 (G0S2) reduced abdominal fat deposition and altered fatty acid composition in chicken. FASEB J. 33, 1188–1198 (2019). www.fasebj.org

Low-pathogenicity avian influenza H9N2 remains an endemic disease worldwide despite continuous vaccination, indicating the need for an improved vaccine strategy. Bacillus subtilis (B. subtilis), a gram-positive and endospore-forming bacterium, is a non-pathogenic species that has been used in probiotic formulations for both animals and humans. The objective of the present study was to elucidate the effect of B. subtilis spores as adjuvants in chickens administered inactivated avian influenza virus H9N2. Herein, the adjuvanticity of B. subtilis spores in chickens was demonstrated by enhancement of H9N2 virus-specific IgG responses. B. subtilis spores enhanced the proportion of B cells and the innate cell population in splenocytes from chickens administered both inactivated H9N2 and B. subtilis spores (Spore + H9N2). Furthermore, the H9N2 and spore administration induced significantly increased expression of the pro-inflammatory cytokines IL-1β and IL-6 compared to that in the H9N2 only group. Additionally, total splenocytes from chickens immunized with inactivated H9N2 in the presence or absence of B. subtilis spores were re-stimulated with inactivated H9N2. The subsequent results showed that the extent of antigen-specific CD4⁺ and CD8⁺ T cell proliferation was higher in the Spore + H9N2 group than in the group administered only H9N2. Taken together, these data demonstrate that B. subtilis spores, as adjuvants, enhance not only H9N2 virus-specific IgG but also CD4⁺ and CD8⁺ T cell responses, with an increase in pro-inflammatory cytokine production. This approach to vaccination with inactivated H9N2 together with a B. subtilis spore adjuvant in chickens produces a significant effect on antigen-specific antibody and T cell responses against avian influenza virus.

Effects of newly isolated Lactobacillus plantarum on the fermentation and chemical composition of fresh rice straw silage was evaluated in this study. Lactic acid bacteria (LAB) from good crop silage were screened by growing them in MRS broth and a minimal medium with low carbohydrate content. Selected LAB (LAB 1821) were Gram-positive, rods, catalase negative, and were identified to be Lactobacillus plantarum based on their biochemical characteristics and a 16S rRNA analysis. Fresh rice straw was ensiled with two isolated LAB (1821 and 1841), two commercial inoculants (HM/F and P1132) and no additive as a control. After 2 months of storage at ambient temperature, rice straw silages treated with additives were well-preserved, the pH values and butyric and acetic acid contents were lower, and the lactic acid content and lactic/acetic acid ratio were higher than those in the control (p0.05) effect on acid detergent fiber or neutral detergent fiber contents. Crude protein (CP) content and in vitro DM digestibility (IVDMD) increased after inoculation of LAB 1821 (p<0.05). LAB 1821 increased the CP, IVDMD, lactic acid content and ratio of lactic acid to acetic acid in rice straw silage and decreased the pH, acetic acid, NH3-N, and butyric acid contents. Therefore, adding LAB 1821 improved the fermentation quality and feed value of rice straw silage.

The present review was aimed to assess the feasibility of increasing the slaughter weight (SW) of finishing pigs. Growth performance, including ADG, ADFI and gain:feed, does not change significantly with increasing SW between 110 and $135{\pm}5kg$ in lean-genotype pigs, whereas in non-lean pigs, ADG and gain:feed decrease with increasing SW within the similar range of BW. Backfat thickness (BFT) and marbling of the carcass, which are greater in barrows than in gilts, increase with the increase of SW. The SW could be increased by using a low-energy diet and thereby reducing the rate of fat deposition per weight gain. The yield of the belly increases with the increase of SW, which may be economically significant in Korea. However, yields of some other primal cuts do not change so much as to affect the carcass value. The redness and fat content of the muscle increase slightly with the increase of SW whereas moisture content is minimally influenced by SW. Muscular protein content rarely changes, but sometimes increases slightly, with increasing SW. Other physicochemical characteristics, including lightness, pH, drip loss, and cooking loss of the muscle, are barely influenced by SW. Marbling of fresh loin and ham increases with increasing SW. Sensory characteristics of fresh loin, ham, and belly, including color, aroma, off-flavor, drip, and acceptability, are not influenced significantly by SW. The eating quality of cooked pork also has almost no relation to SW. In conclusion, it is thought that the current SW for moderately lean barrows and gilts can be raised up to 125 and 135 kg, respectively, with BFT at these weights predicted to be approximately 24 mm near the last rib, without compromising the meat quality.

The present study was conducted to investigate the effects of a lipid-coated zinc oxide (ZnO) supplement Shield Zn (SZ) at the sub-pharmacological concentration on intestinal morphology and gene expression in weanling pigs, with an aim to gain insights into the mechanism of actions for SZ. Forty 22-day-old weanling pigs were fed a nursery diet supplemented with 100 or 2,500 mg Zn/kg with uncoated ZnO (negative control [NC] or positive control [PC], respectively), 100, 200, or 400 mg Zn/kg with SZ for 14 days and their intestinal tissues were taken for histological and molecular biological examinations. The villus height (VH) and crypt depth (CD) of the intestinal mucosa were measured microscopically following preparation of the tissue specimen; expression of the genes associated with growth and immune function was determined using the real-time quantitative polymerase chain reaction. There was no difference in daily gain, gain:feed, and diarrhea score between the SZ group and either of NC and PC. The VH and VH:CD ratio were less for the SZ group vs NC in the jejunum and duodenum, respectively (p<0.05). The jejunal mucosal mRNA levels of insulin-like growth factor (IGF-I) and interleukin (IL)-10 regressed and tended to regress (p = 0.053) on the SZ concentration with a positive coefficient, respectively, whereas the IL-6 mRNA level regressed on the SZ concentration with a negative coefficient. The mRNA levels of IGF-I, zonula occludens protein-1, tumor necrosis factor-α, IL-6, and IL-10 did not differ between the SZ group and either of NC and PC; the occludin and transforming growth factor-β1 mRNA levels were lower for the SZ group than for PC. The present results are interpreted to suggest that dietary ZnO provided by SZ may play a role in intestinal mucosal growth and immune function by modulating the expression of IGF-I, IL-6, and IL-10 genes.