Effects of feed form and particle size on growth performance, nutrient digestibility, carcass characteristics, and gastric health in growing-finishing pigs.

OBJECTIVE: This study was conducted to evaluate the effects of feed processing and particle size on growth performance, nutrient digestibility, carcass characteristics, and gastric health in growing-finishing pigs. METHODS: A total of 360 growing pigs (22.64±0.014 kg initial body weight [BW]) were allocated to 1 of 6 treatments with 6 replicates by BW and sex, and 10 pigs were housed in one pen in a randomized complete block design. The BW and feed intake were recorded to calculate growth performance. For the digestibility trial, a total of 24 barrows with an initial BW of 33.65±0.372 kg were split into 6 treatments with a completely randomized design. Dietary treatments were designed by a 2×3 factorial arrangement of treatments based on two main factors, particle size (600, 750, 900 µm) and feed form (mash and pellet) of diet. Experimental diets were formulated to contain the requirements of the NRC (2012). RESULTS: The BW and average daily gain were not changed by dietary treatments, and the feed intake of finishing pigs (wks 6 to 12) was increased when the pigs were fed a mash diet (p<0.05). For the overall period, the feed efficiency of pigs was improved with the pellet diet (p<0.01) and reduced particle size (p<0.05). The pellet diet had effects on increasing crude fat digestibility (p<0.01) relative to a mash diet, but there was no considerable change in dry matter and crude protein digestibilities by dietary treatments. In the evaluation of gastric health, a trend for an increased incidence of keratinization in the esophageal region was observed as particle size decreased (p = 0.07). CONCLUSION: Feed efficiency could be improved by pellet diet and reduced particle size. Nutrient digestibility, carcass characteristics, and gastric health were not affected by feed form, and particle size ranged from 600 to 900 µm.

Effects of Copra Meal Inclusion Level in Growing-Finishing Pig Diets Containing ß-Mannanase on Growth Performance, Apparent Total Tract Digestibility, Blood Urea Nitrogen Concentrations and Pork Quality.

This experiment was conducted to evaluate the effects of copra meal (CM) inclusion level on the growth performance, apparent total tract digestibility (ATTD), blood urea nitrogen (BUN) concentrations, and pork quality of growing-finishing pigs fed diets containing ß-mannanase. Eighty crossbred pigs with average body weight (BW) of 27.22 ± 0.09 kg were allotted to five dietary treatments with four pigs per pen and four replicates per treatment based on sex and BW. The dietary treatments were: (1) NC: negative control, corn-soybean meal (SBM) based basal diet, (2) PC: positive control, basal diet + 0.10% ß-mannanase (800 IU/ kg diet), (3) CM6: PC diet with 6% CM inclusion, (4) CM12: PC diet with 12% CM inclusion, and (5) CM18: PC diet with 18% CM inclusion in a three-phase feeding program (growing: 0-6 weeks, finishing I: 7-9 weeks, and finishing II: 10-12 weeks). The quadratic responses were observed in the BW at six weeks (p < 0.05), ADG in the growing phase (0-6 weeks; p < 0.05), and ADFI in the finishing phase with a tendency (7-12 weeks; p = 0.06) as the inclusion level of CM increased. However, the BW at 12 weeks (linear, p < 0.05 and quadratic, p = 0.06), the overall ADG (0-12 weeks; linear and quadratic, p < 0.05), and the G:F ratio in the finishing (7-12 weeks; linear, p < 0.05) and overall (0-12 weeks; linear, p < 0.05) phases decreased with increasing levels of CM in the diets. The ATTD of crude protein (linear, p < 0.05), crude fiber (linear, p < 0.05), and ash (linear, p < 0.05) decreased linearly as the inclusion level of CM increased. The BUN concentrations increased linearly with increasing levels of CM in the diets at 12 weeks of the experiment (p < 0.05). As the inclusion level of CM increased, TBARS value at d 3 post-mortem (linear, p = 0.07) tended to increase, whereas initial loin pH at 1 h post-mortem decreased (linear and quadratic, p < 0.05) with no difference in ultimate loin pH at 24 h post-mortem. These results indicated that CM inclusion up to 12% in the growing-finishing pig diets with ß-mannanase did not affect growth performance, nutrient utilization, and pork quality whereas 18% CM inclusion to the diets could negatively impact nutrient digestibility, BUN concentrations, and thereby growth performance.

Effects of dietary vitamin levels on physiological responses, blood profiles, and reproductive performance in gestating sows.

This study was performed to evaluate the effects of dietary vitamin levels on physiological responses, blood profiles, and reproductive performance in gestating sows. A total of 52 F1 multiparous sows (Yorkshire × Landrace) with an average body weight of 223.5 ± 31.7 kg, an average parity of 6.4 ± 2.7, and an average backfat thickness of 18.5 ± 4.9 mm were divided into four treatment groups considering body weight, backfat thickness, and parity in a completely randomized design with 13 replicates. The treatments were 100% (V1), 300% (V3), 600% (V6) and 900% (V9) of the National Research Council (NRC) Nutrient Requirements of Swine. The gestation diet was formulated based on corn-soybean meal (SBM) and contained 3,265 kcal of metabolizable energy (ME)/kg and 12.00% crude protein. During the lactation period, all sows were fed the same commercial lactation diet. There was no significant difference in body weight of gestating sows. However backfat thickness tended to increase when higher levels of vitamins were provided to gestating sows (p < 0.10). When high levels of dietary vitamins were provided, the body weight change of lactating sows increased (p < 0.01). When sows were fed higher levels of vitamins, the feed intake of lactating sows tended to decrease (p = 0.06). There were no treatment differences in the number of total born, born alive, stillbirth piglets, or the body weight of piglets according to different dietary vitamin level. As dietary vitamin level increased, the serum concentration of 25(OH)D3 in sows at 90 days of gestation linearly increased (p < 0.01). Furthermore, the serum vitamin E level of gestating sows was linearly increased with increasing dietary vitamin level (p < 0.05). The current NRC vitamin requirements are sufficient for gestating sows and higher levels of vitamins in the gestation diet did not show any beneficial effects for gestating and lactating sows.

Effects of dietary energy and crude protein levels on growth performance, blood profiles, and carcass traits in growing-finishing pigs.

This experiment was conducted to evaluate the effect of dietary energy and crude protein (CP) levels on growth performance, blood profiles, and carcass traits in growing-finishing pigs. A total of 180 crossbred pigs ([Yorkshire × Landrace] × Duroc) with an average body weight of 30.96 ± 3.068 kg were used for a 12-week feeding trial. Experimental pigs were allotted to a 2 × 3 factorial arrangement using a randomized complete block (RCB) design. The first factor was two levels of dietary metabolizable energy (ME) density (13.40 MJ/kg or 13.82 MJ/kg), and the second factor was three dietary CP levels based on subdivision of growing-finishing phases (high: 18%/16.3%/16.3%/13.2% middle: 17%/15.3%/15.3%/12.2% and low: 16%/14.3%/14.3%/11.2%). Average daily gain (ADG) and gain-feed ratio (G:F ratio) decreased as dietary CP level was decreased linearly (linear, p < 0.05; p < 0.05, respectively) in the early growing period, and G:F ration also decreased as dietary CP level was decreased linearly (linearly, p < 0.05) over the whole growing phase. Over the entire experimental period, G:F ratio decreased as dietary ME level decreased (p = 0.01). Blood urea nitrogen (BUN) concentration was increased as dietary energy level decreased in growing period (p < 0.01). During finishing period, total protein concentration was decreased by lower dietary energy level (p < 0.05). In this study, there were no significant differences in proximate factors, physiochemical properties, muscle TBARS assay results, pH changes, or color of pork by dietary treatments. However, saturated fatty acid (SFA) increased (p < 0.01) and polyunsaturated fatty acid (PUFA) decreased (p < 0.05) when ME was decreased by 0.42 MJ/kg in growing-finishing pig diets. In addition, monounsaturated fatty acid (MUFA) tended to increase when CP level was decreased in growing-finishing pig diets (p = 0.06). A growing-finishing diet of 13.82 MJ/kg diet of ME with the high CP level can improve growth performance and show better fatty acids composition of pork.

Erratum to: Evaluation of barley to replace milk by-product in weaning pig's diet.

[This corrects the article DOI: 10.5187/jast.2019.61.2.77.].

Evaluation of barley to replace milk by-product in weaning pig's diet.

The supplementation level of barley was limited because of high contents of fiber in monogastric animals. Barley contained high soluble fiber, thus it could prevent to diarrhea of weaning pigs. Moreover, as the barley break down by enzymes, free sugars come out from the barley, which could be used as an energy source in weaning pigs and replace milk by-products in weaning pig's diet. Therefore, present study was conducted to investigate the influence of barley to replace milk by-product in weaning pig's diet on growth performance, blood profile, nutrient digestibility, diarrhea incidence, and economic analysis in weaning pigs. A total of 112 crossbred ([York-shire × Landrace] × Duroc, weaned at 28 days of age) piglets were allotted to 4 treatments in a randomized complete block (RCB) design. Each treatment has 7 replications with 4 pigs per pen. Pigs were fed each treatment diet which containing different levels of barley (0%, 10%, 20%, and 30%) at the expense of whey powder and lactose. Three phase feeding programs were used for 6 weeks of growth trial (phase 1: 0-2 weeks; phase 2: 3-4 weeks; phase 3: 5-6 weeks). During 0-2 week, body weight (BW), average daily gain (ADG) and G:F ratio were decreased as barley level increased in the diet (linear response, p < 0.01). In blood profile, blood urea nitrogen was decreased as the barley level increased in the diet (linear, p < 0.01). However, no significant differences were observed in blood glucose level. In nutrient digestibility, crude fat digestibility was linearly increased as barley increased (linear, p < 0.01). The incidence of diarrhea was improved as increasing barley contents in all phases (linear, p < 0.01). These results demonstrated that supplementation of barley to replace milk by-product influenced negatively on growth performance during 0-2 week. However, the incidence of diarrhea and later growth performance from 3 week postweaning were improved as dietary barley level increased.

Effects of dietary energy and protein levels on reproductive performance in gestating sows and growth of their progeny.

This experiment was conducted to evaluate the effect of dietary energy and crude protein (CP) levels on reproductive performance, litter performance, milk quality, and blood profiles in gestating sows. A total of 59 multiparous sows (Yorkshire × Landrace) with similar body weights (BW), backfat thickness (BF), and parity were assigned to one of six treatments with 9 or 10 sows per treatment using a 2 × 3 factorial arrangement and completely randomized design. The first factor was two levels of dietary metabolizable energy (ME) density (13.40 or 13.82 MJ/kg) and the second factor was three dietary protein levels based from 35 day in gestating phases (10.5%, 12%, and 13.5%). Backfat thickness change in lactating sows decreased linearly as CP level increased (p = 0.03). Increased energy level in the gestating sow diet tended to increase the total number of piglets born (p = 0.07), but piglet weight decreased (p = 0.02). Dietary CP level had a negative effect on colostrum quality. Casein, protein, total solid, and solids-not-fat concentrations decreased linearly and lactose level increased linearly as CP level in the gestating sow diet increased (casein%: p = 0.03; protein%: p = 0.04; lactose%: p = 0.06; total solids: p = 0.03; solid-not-fat: p = 0.03, respectively). However, improving ME by 0.42 MJ/kg had no significant effect on the chemical composition of sow colostrum. There were no significant differences in blood glucose concentration in gestating sows when sows were fed different levels of energy during gestation, but blood glucose increased at 21 day of lactation when energy increased by 0.42 MJ/kg (p = 0.04). Blood urea nitrogen concentration increased linearly when dietary CP levels increased at 110 day in gestation, 24-hours postpartum, and 21 days of lactation (linear, p < 0.05, p < 0.05, and p < 0.05, respectively), and it also increased when dietary energy increased at 110 days of gestation and 24-hours postpartum (p < 0.01, and p < 0.01, respectively). A gestating sow diet containing 13.82 MJ/kg ME and 10.5% CP can improve reproductive performance, litter performance, and colostrum quality.

Effects of dietary energy and crude protein levels on growth performance, blood profiles, and nutrient digestibility in weaning pigs.

OBJECTIVE: This experiment was conducted to investigate the effect of reducing dietary metabolic energy (ME) and crude protein (CP) levels on growth performance, blood profiles, and nutrient digestibility in weaning pigs. METHODS: A total of 240 crossbred pigs (Duroc×[Landrace×Yorkshire]) with an average body weight of 8.67±1.13 kg were used for a 6-week feeding trial. Experimental pigs were allotted to a 2×3 factorial arrangement using a randomized complete block design. The first factor was two levels of dietary ME density (low ME level, 13.40 MJ/kg or high ME level, 13.82 MJ/kg) and the second factor was three dietary CP levels based on subdivision of early and late weaning phases (low CP level, 19.7%/16.9%; middle CP level, 21.7%/18.9%; or high CP level, 23.7%/20.9%). RESULTS: Over the entire experimental period, there were no significant difference in body weight among groups, but a decrease in diet energy level was associated with an increase in average daily feed intake (p = 0.02) and decrease in gain-feed ratio (G:F) ratio (p<0.01). Decreased CP levels in the diet were associated with a linear increase in average daily gain (p< 0.05) and quadratic increase in G:F ratio (p<0.05). In the early weaning period, blood urea nitrogen concentration tended to increase when ME in the diet decreased and decrease when CP level in the diet decreased (p = 0.09, p<0.01, respectively). Total protein concentration tended to increase when CP level was reduced (p = 0.08). In the late weaning period, blood urea nitrogen concentration decreased linearly as CP level decreased (p<0.01). The CP and crude fat digestibility decreased when ME was decreased by 0.42 MJ/kg (p = 0.05, p = 0.01, respectively). The CP digestibility increased linearly as CP level decreased (p = 0.01). CONCLUSION: A weaning pig diet containing high ME level (13.82 MJ/kg) and low CP level (19.7%/16.9%) can improve pig growth performance and nutrient digestibility.

Effects of different creep feed types on pre-weaning and post-weaning performance and gut development.

OBJECTIVE: This experiment was carried out to determine the effects of different creep feed types on suckling performance and further adjustments to solid feed after weaning. METHODS: A total of 24 multiparous sows and their litters were allotted to one of three treatment groups: i) provided highly digestible creep feed (Creep), ii) provided a pig weaning diet (Weaner), and iii) provided sow feed (Sow) as creep feed until weaning. After weaning, a total of 96 piglets were selected for evaluation of post-weaning performance. RESULTS: For pre-weaning performance, the Creep treatment led to a significantly higher feed intake from 14 to 28 d (p<0.05) and higher body weight gain from 21 to 28 d than piglets that were provided other diets. However, after weaning, the Weaner treatment yielded a significantly higher feed intake and average daily gain than other treatments from 0 to 14 d after weaning (p<0.05); Creep treatment tended to generate lower villus heights in the duodenum than the other treatments (p = 0.07). CONCLUSION: Highly digestible creep feed improved pre-weaning performance, but feed familiarity and grain-based creep feed improved post-weaning performance.

Effects of cashew nut testa levels as an alternative to wheat bran in gestating sow diets.

OBJECTIVE: This study was conducted to evaluate the effects of dietary cashew nut testa (CNT) as an alternative feed ingredient to wheat bran on reproductive performance, litter performance, milk composition, and blood profiles of gestating sows. METHODS: Forth multiparous sows (Yorkshire×Landrace) were fed experimental diets starting at 35 days of pregnancy and an initial average body weight (BW) of 211.53±8.86 kg. Each sow was assigned to a treatment based on BW, backfat thickness (BF) and parity with 10 sows per treatment. Treatments were as follows: i) corn-soybean meal based diet with 6% of wheat bran (C0); ii) basal diet with 2% of CNT and 4% of wheat bran (C2); iii) basal diet with 4% of CNT and 2% of wheat bran (C4); and iv) basal diet with 6% of CNT (C6). RESULTS: There were no statistically significant differences in BW and BF of gestating sows throughout the experimental period. However, changes in BF (p = 0.09) and the daily feed intake of sows (p = 0.09) tended to linearly increase during the lactation period. The weaning to estrus interval (WEI) showed a quadratic response to CNT treatment (p = 0.02), and the C2 diet showed the shortest WEI. Litter birth weight (p = 0.04) and piglet birth weight (p = 0.06) were linearly decreased with increase in CNT. Furthermore, there had no significant differences in piglet weight and litter weight in 21 day. Insulin concentration at day 70 of gestation was linearly reduced with increasing CNT level in diets (p = 0.03). CONCLUSION: When 6% CNT replaced wheat bran in gestating sow diets, there were no negative effects on sow performance, but litter birth weight and piglet birth weight were decreased when CNT level increased in gestating sow diets.

Vitamin D-metabolic enzymes and related molecules: Expression at the maternal-conceptus interface and the role of vitamin D in endometrial gene expression in pigs.

Vitamin D is a secosteroid hormone with many varied functions including regulation of blood calcium levels, cell proliferation, immunity, and reproduction in mammals. Vitamin D is activated by 25-hydroxylase (CYP2R1) and 1-alpha-hydroxylase (CYP27B1) and is degraded by 24-hydroxylase (CYP24A1). Vitamin D is transported by vitamin D-binding protein (group-specific component, GC) through the bloodstream and regulates cellular actions by binding to vitamin D receptor (VDR). In this study, we determined the expression and regulation of vitamin D-related molecules and the role of vitamin D at the maternal-conceptus interface in pigs. Vitamin D-metabolizing enzymes CYP2R1, CYP27B1, and CYP24A1, vitamin D binding protein GC, and vitamin D receptor VDR were expressed in the endometrium in a pregnancy stage-specific manner as well as in conceptus and chorioallantoic tissues during pregnancy. VDR protein was localized to endometrial and trophoblastic cells. Concentrations of calcitriol, the active form of vitamin D, in the endometrial tissues were higher during early pregnancy than in mid- to late pregnancy, while plasma concentrations of calcitriol were highest during late pregnancy. Furthermore, calcitriol affected the expression of several genes related to conceptus implantation, vitamin D metabolism, calcium ion regulation, PG metabolism, and calcium-binding proteins in endometrial tissue explants. These results show that CYP2R1, CYP27B1, CYP24A1, GC, and VDR were expressed at the maternal-conceptus interface, endometrial calcitriol levels were regulated during pregnancy, and calcitriol modulated the expression of endometrial genes, suggesting that calcitriol may play an important role in the establishment and maintenance of pregnancy by regulating endometrial function in pigs.

Various levels of rapeseed meal in weaning pig diets from weaning to finishing periods.

OBJECTIVE: This experiment was conducted to investigate the influence of rapeseed meal (RSM) supplementation in weaning pig diet on growth performance, blood profile, carcass characteristics and economic analysis on weaning to finishing pigs. METHODS: A total of 120 cross bred ([Yorkshire×Landrace]×Duroc) weaning pigs were allotted to 5 treatments in a randomized complete block design. Each treatment had 4 replications with 6 pigs per pen. Five different levels of RSM (0%, 2%, 4%, 6%, and 8%) were used as dietary treatments. RESULTS: Overall, no treatment showed significant differences in growth performance with increased dietary RSM levels. The concentration of blood urea nitrogen (BUN) decreased as dietary RSM levels increased in 6 weeks (linear response, p<0.01). Total cholesterol, high density lipoprotein cholesterol, low density lipoprotein cholesterol, triiodothyronine, and thyroxine showed no significant differences, neither were there any significant differences in the immune response (IgG and IgA). As the dietary RSM levels of weaning pig diet were increased, no differences were found among dietary treatments upon performing proximate analyses of the pork after finishing. The influence of RSM supplementation on nutrient digestibility and nitrogen retention were not affected by dietary RSM levels either. With increased dietary RSM levels in the weaning pig diet, no differences among dietary treatments were found after performing proximate analyses of the pork's physiochemical properties. In addition, there were no significant differences observed in pork colors, pH levels, and economic benefits. CONCLUSION: Consequently, this experiment demonstrated that weaning pig's diet containing RSM influenced BUN concentration, but there were no detrimental effects on the growth performance of weaning pigs with up to 8% RSM in the diet.

Effects of wheat supplementation levels on growth performance, blood profiles, nutrient digestibility, and pork quality in growing-finishing pigs.

OBJECTIVE: This study was conducted to evaluate various wheat supplementation levels on growth performance, blood profiles, nutrient digestibility, and pork quality in growing-finishing pigs. METHODS: A total of 120 growing pigs ([Yorkshire×Landrace]×Duroc), with an average 27.75± 1.319 kg body weight, were used in growth trial. Pigs were allotted into each treatment by body weight and sex in 4 replicates with 6 pigs per pen in a randomized complete block design. Four-phase feeding programs were used in this experiment. The treatments included the following: i) corn-soybean meal (SBM) - based diet (CON), ii) corn-SBM - based diet+15% of wheat (W15), iii) corn-SBM - based diet+30% of wheat (W30), iv) corn-SBM - based diet+45% of wheat (W45), and 5) corn-SBM-based diet+60% of wheat (W60). RESULTS: There was no significant difference in growth performance among the dietary treatments. However, the gain-to-feed (G:F) ratio tended to increase (quadratic, p<0.08) when the pigs were fed a higher wheat diet during the finishing period. The digestibility of crude ash and fat tended to decrease as the wheat supplementation level increased (p<0.08). The proximate analysis of the longissimus muscle was not affected by the dietary level of wheat. The crude ash content in pork was decreased linearly as the wheat supplementation level increased (p = 0.05). There was no significant difference in the pH level, shear force, water holding capacity, and cooking loss of the pork. In pork and fat, L*, a*, and b* values were not significantly different among dietary treatments. CONCLUSION: Wheat can be supplemented up to 60% in a growing-finishing pig without detrimental effects on growth and pork quality. The G:F ratio tended to improve in the finishing period by wheat inclusion.

Effect of different soybean meal type on ileal digestibility of amino acid in weaning pigs.

An experiment was conducted to evaluate apparent (AID) and standardized (SID) ileal digestibilities of crude protein (CP) and amino acids (AA) with 6 soybean products in weaning pigs. A total of 14 weaning barrows with an initial body weight of 6.54 ± 0.34 kg were fitted with T-cannula at the distal ileum and allotted to 7 diets containing various soybean products. The soybean products used in the experiment were conventional soybean meal (CSBM), SBM fermented by Aspergillus oryzae GB-107 (FSBMA), SBM fermented by Bacillus subtilis PP6 (FSBMB), UV sterilized SBM fermented by Bacillus subtilis PP6 (UVFSBMB), SBM containing Bacillus subtilis PP6 (PSBM), and soy protein concentrate (SPC). Six corn-based diets were used and each of soybean products was added. All diets contained 5.0 g/kg of chromic oxide as an indigestible indicator and an N-free diet was used to measure basal endogenous losses of CP and AAs. Ileal CP digestibility did not differ by different soybean products. However, SIDs of Ile, Phe and Val were improved in pigs fed the FSBMB, UVFSBMB and SPC diets and the pigs fed the FSBMA diet showed higher SIDs of Phe and Val compared with those fed the CSBM diet (P < 0.05). The FSBMB diet had higher SIDs in most AAs compared with the FSBMA diet (P < 0.05), and higher SIDs of Lys, Ala, Pro, Ser, and Tyr compared with PSBM diet (P < 0.05). However, there was no response of UV-sterilization on the FSBMB in the SIDs of AAs. These results suggest that SIDs of AAs could be improved by the supplementation of fermented soybean products in the diet for weaning pigs but fermentation with Bacillus subtilis is more efficient in improving ileal AA digestibility than that with Aspergillus oryzae. Furthermore, probiotics supplementation in the CSBM and UV-sterilization of the FSBMB had no effects on chemical composition and ileal AA digestibility.

Genome-wide DNA Methylation Profiles of Small Intestine and Liver in Fast-growing and Slow-growing Weaning Piglets.

Although growth rate is one of the main economic traits of concern in pig production, there is limited knowledge on its epigenetic regulation, such as DNA methylation. In this study, we conducted methyl-CpG binding domain protein-enriched genome sequencing (MBD-seq) to compare genome-wide DNA methylation profile of small intestine and liver tissue between fast- and slow-growing weaning piglets. The genome-wide methylation pattern between the two different growing groups showed similar proportion of CpG (regions of DNA where a cytosine nucleotide occurs next to a guanine nucleotide in the linear sequence) coverage, genomic regions, and gene regions. Differentially methylated regions and genes were also identified for downstream analysis. In canonical pathway analysis using differentially methylated genes, pathways (triacylglycerol pathway, some cell cycle related pathways, and insulin receptor signaling pathway) expected to be related to growth rate were enriched in the two organ tissues. Differentially methylated genes were also organized in gene networks related to the cellular development, growth, and carbohydrate metabolism. Even though further study is required, the result of this study may contribute to the understanding of epigenetic regulation in pig growth.

Among γ-secretase substrates Notch1 alone is sufficient to block neurogenesis but does not confer self-renewal properties to neural stem cells.

Notch signaling pathway enhances neural stem cell characters and regulates cell fate decisions during neural development. Interestingly, besides Notch, other γ-secretase substrates such as APP, LRP2, and ErbB4 have also proven to have biological functions in neural development. We designed a unique experimental setting, combining gain-of- (expression of Notch intracellular domain, NICD) and loss-of-function (γ-secretase inhibition) methods, and were able to examine the function of Notch alone by excluding the activity of other γ-secretase substrates. Here, we show that the frequency and size of neurospheres generated from embryonic neural stem cells (NSCs) significantly decreased by 62.7% and 37.2%, respectively, in the presence of γ-secretase inhibitor even when NICD was expressed. Under the condition of differentiation, however, the γ-secretase inhibitor treatment did not influence the promotion of astrogenesis at the expense of neurogenesis by NICD. These results indicate that other γ-secretase substrate(s) along with Notch are important in the maintenance of the stemness of NSCs, but that Notch alone can sufficiently inhibit neurogenesis without the action of the other γ-secretase substrates during differentiation.