Journal of Animal Science and Biotechnology最新文献

Background: Fast-growing broilers are poorly adapted to heat. Adjusting feed composition may mitigate heat stress (HS) effects in temperate climates, while maintaining performance and health during cooler days.

Methods: One thousand nine hundred and twenty Ross 308 male broilers were housed in 64 pens in 4 climate-controlled rooms, 2 under cyclical HS (d 28-43; 32 ± 2 °C; 60%-70% RH; 09:30-15:30) and 2 under thermoneutral (TN) conditions. In the finisher phase, broilers were allocated to 4 dietary treatments, analyzed values are given except for metabolizable energy (ME): low crude protein (CP) and control fat (LowCP-ConF; 17.0% CP, 5.9% crude fat (CF), 2,925 kcal/kg ME), low CP and high fat (LowCP-HighF; 17.2% CP, 7.9% CF, 3,019 kcal/kg ME), control CP and high fat (ConCP-HighF; 18.1% CP, 8.0% CF, 2,992 kcal/kg ME) and a basal control (ConCP-ConF; 18.7% CP, 6.3% CF, 2,913 kcal/kg ME). LowCP diets contained control levels of digestible amino acids.

Results: During the finisher phase, compared to control CP levels, LowCP increased average daily feed intake (ADFI) (+ 2.15%; P = 0.020) and affected average daily gain (ADG) and feed conversion ratio (FCR) negatively under TN (-3.77% and +6.49%; P = 0.003 and P < 0.001, respectively), but not during HS. Compared to control CF, HighF decreased ADFI during TN and HS (-3.16% and -3.17%; P < 0.001 and P = 0.022) and reduced ADG in TN groups (-3.17%; P = 0.010), but not during HS. Mortality was higher in broilers receiving HighF during HS (P = 0.040). Slaughter weights were unaffected. LowCP decreased plasma uric acid and lactate dehydrogenase levels during TN, but increased plasma glucose during HS. LowCP increased breast meat redness (a*) during TN and HS (P < 0.05). HighF decreased fat (-1.68%; P = 0.017), but increased protein levels (+1.53%; P < 0.001) in breast meat of HS-broilers.

Conclusion: LowCP and HighF impaired performance under TN but not under HS. HighF increased mortality under HS, yet improved breast meat composition. These findings highlight the challenge of designing an optimal diet for both conditions and underscore the need to better understand amino acid needs and energy-to-protein ratios during HS.

Background: As a unique livestock adapted to the harsh environment, grazing yaks frequently suffer from malnutrition and even death because of the lower yield and quality of forage in the Qinghai-Tibet Plateau during the cold season. Certain stress conditions, such as environmental changes, disease, and malnutrition, can lead to a decrease in glutamine (Gln) synthesis, which fails to cover the physiological needs of the organism. Supplementation with exogenous Gln can promote nutrient digestion and improve rumen fermentation in ruminant animals under malnutrition. However, whether Gln could alleviate the barrier function injury induced by malnutrition and its mechanism is still unclear.

Methods: In the in vivo experiments, 24 healthy yaks (31 months, 265.35 ± 25.81 kg) were randomly divided into 3 groups, namely control group (Con, free access to the basal diet), feed restriction group (FR, 50% level of ad libitum feed intake), and feed restriction + Gln group (FR + Gln, 50% level of ad libitum feed intake from d 1 to 30, 50% level of ad libitum feed intake + 1% Gln from d 31 to 60). In the in vitro experiments, the yak rumen epithelial cells (YRECs) were divided into 4 groups: Con group (complete medium), Gln group (complete medium + 10 mmol/L Gln), Gln deficiency group (Gln-D, Gln-free medium), and Gln deficiency + Gln group (Gln-D + Gln, Gln-free medium + 10 mmol/L Gln).

Results: In the in vivo experiments, FR significantly decreased the ruminal concentrations of acetate, propionate, butyrate, iso-butyrate, and total volatile fatty acid (VFA) (P < 0.05). FR also reduced the mRNA expression of NHE1, Na⁺/K⁺-ATPase, and Ca²⁺/Mg²⁺-ATPase, and the concentrations of lactate, histone acetyltransferase (p300), histone deacetylase (HDAC), as well as the histone lysine lactylation level compared to Con group, while Gln supplementation alleviated them (P < 0.05). In the in vitro experiments, Gln alleviated the Gln-D-induced down-regulation of NHE1, Na⁺/K⁺-ATPase, and Ca²⁺/Mg²⁺-ATPase mRNA expressions and reduction of lactate, p300, HDAC concentrations, and histone lysine lactylation level (P < 0.05). Besides, p300 inhibitor abrogated Gln repair of barrier function damage in YRECs (P < 0.05).

Conclusions: Overall, our results revealed the potential mechanism of Gln supplementation to repair malnutrition-induced damage of rumen epithelial barrier function in yaks, which might be related to histone lysine lactylation. However, because we do not have a control group receiving glutamine alone, we cannot determine the impact of Gln on the rumen epithelial function of normal yaks.

Background: Heat stress (HS) is posing as a tremendous threat to the swine industry, due to the thermos-sensitive gonads of boars. Testes are immune-privileged organs in which spermatogenesis needs to remain undisturbed, whereas immune cells are thermo-sensitive, especially macrophages, which are the most abundant testicular immune cells. Our study aimed to unveil the underlying immune responses and assess their consequences on the semen quality of boars under HS. The results will aid in addressing environmental temperature-related seasonal infertility and in selecting the best boar for use in artificial insemination.

Methods: The 3-week experiment assigned 26 8-week-old Rongchang male pigs into thermal neutral pair-feed (TN-PF) and HS groups. During the last 2 weeks, which served as the HS period, the HS group was subjected to 14-day 35 ± 1 °C, while the TN-PF group was kept at 26 ± 1 °C. Pig gonad tissues were sampled at the end of HS period for assessments and measurements.

Results: Our findings confirmed HS-related reactions such as elevated respiration rate (P < 0.05) and elevated heat shock protein 60 (HSP60; P < 0.05) and heat shock protein 90 (HSP90; P < 0.05) expression levels. Sperm motility (P = 0.06) and progressive sperms (P = 0.08) were decreased under HS as was a significant reduction in average straight-line velocity (VSL; P < 0.05). Additionally, total abnormality levels increased (P < 0.05). Fibrosis, caspase-3 expression, and accumulations of tumor necrosis factor-α (TNF-α; P < 0.05) and interleukin-1β (IL-1β; P < 0.05), along with an elevated macrophage composition (P < 0.05) characterized the orchitis under HS. Single cell RNA sequencing (scRNA-seq) revealed fluctuations in engulfing and inflammatory signals in testicular macrophages (TMs). In particular, the complement cascade was promoted by CD163⁺ macrophages, resulting in membrane attack complex (C5b-9) assembly (P < 0.05). Linear regressions further revealed a negative correlation between C5b-9 and sperm motility (P < 0.05), as well as near-negative correlations between the C5b-9 and both progressive motility (P = 0.08) and VSL (P = 0.06).

Conclusions: Our findings highlighted the relationship between HS, the onset of orchitis, and the activation of the complement system, all of which decreased the boar semen quality.

Background: Hypoxia is a pervasive challenge in aquaculture that poses a significant threat to aquatic organisms. Since fish cannot synthesize vitamin A endogenously, it must be supplied through diet, and it plays a vital role in supporting fish stress resistance. This study aimed to investigate the protective effects of VA on the gills of adult grass carp (Ctenopharyngodon idella) against hypoxia and to elucidate the underlying mechanisms.

Methods: Six experimental diets with graded VA levels (375, 862, 1,614, 2,099, 2,786, and 3,118 IU/kg) were fed to grass carp (initial weight: 726 ± 1.2 g) for 60 d. After the trial, 24 fish per treatment were selected, divided equally into normoxic and hypoxic groups, fasted for 24 h, and then subjected to a 96-h acute hypoxic challenge.

Results: The results demonstrated that VA supplementation mitigated hypoxia-induced damage in gill tissue, as evidenced by histological examination. Furthermore, VA alleviated oxidative stress, as indicated by reduced levels of lactate (LD), lactate dehydrogenase (LDH), reactive oxygen species (ROS), protein carbonyl (PC), and malondialdehyde (MDA). Further investigations indicated that VA alleviated mitochondrial stress, potentially through suppressing the canonical UPR^mt axis while activating both the UPR^mt sirtuin axis and the UPR^IMS/Erα axis. VA also modulated mitochondrial mass via multiple mechanisms, including the promotion of mitochondrial biogenesis, maintenance of dynamics by stimulating fusion and reducing fission, and inhibition of mitophagy. The suppression of mitophagy likely involved downregulating both the Pink1/Parkin-dependent pathway and the Hif1a-Bnip3 pathway. Taken together, these adaptations suggested an essential role for VA in preserving mitochondrial homeostasis. Based on the quadratic regression analysis of ROS and MDA levels from the hypoxic group, the estimated VA requirements for adult grass carp were 2,013 and 2,056 IU/kg diet, respectively.

Conclusions: In summary, this study provided the first evidence that VA conferred protective effects against hypoxia-induced gill damage in grass carp.

Background: Understanding the genetic basis of male reproduction in mammals remains challenging. Commercial pig populations offer a unique model for studying fertility, as semen traits are routinely recorded using high-throughput systems.

Results: In a large-scale GWAS of 15 semen traits based on 286,314 ejaculates collected from 2,954 boars of a purebred pig line, we identified 10 QTL, including four loci with recessive deleterious alleles. Several lead SNPs affected multiple semen traits. For example, a SNP on SSC6 was significantly associated with distal cytoplasmic droplets and with effects on tail abnormalities and sperm motility in a follow up analysis. The allele frequencies of some loci were different in older boar's, most likely due to culling based on poor semen quality. Using WGS, we identified six missense variants in high linkage disequilibrium (LD) with lead SNPs in genes related to sperm production (e.g., MEIOB, CFAP74 and UBE2B). Remarkably, the frequency of some alleles with predicted deleterious effects on semen traits increased between 2013 and 2019.

Conclusions: Our results highlight loci with major effects on semen quality, some of which are linked to functional variants in key genes involved in spermatogenesis. The information from this study can be used to select against deleterious alleles affecting semen characteristics in pigs and provides valuable insight into the genetics of mammalian male fertility.

Background: The cellular basis of testicular development and spermatogenesis for the extreme sperm density in chickens (100-fold higher than mammals) remains poorly defined. A comprehensive understanding of the molecular characteristics driving poultry testicular development is crucial for explaining this enhanced spermatogenic capacity.

Results: Here, we first established a single-cell transcriptome profile of chicken testes from hatching to maturity, identifying the dynamic transcriptional characteristics of germ cell fate transition and exploring the developmental characteristics of Sertoli cells and Leydig cells. Multi-species comparisons revealed a higher proportion of germ cells and the unique adaptations of Sertoli cells in chicken testes. Most importantly, our results demonstrated that Sertoli cells dominated in somatic composition of mature chicken testes, and proliferating Sertoli cells persisted in chicken testes even after sexual maturity, while no proliferating Sertoli cells in mammals. We also found a richer interaction network between chicken testicular cells, especially the specific activation of Sertoli cell interaction signals, such as TGF-β, BMP, EGF, and activin. These adaptations of Sertoli cells may support the spermatogenic superiority in chickens. Additionally, our results indicated that cAMP responsive element binding protein 5 (CREB5) played a crucial role in maintaining the maturation and function of chicken Sertoli cells, and circadian rhythm promoted testosterone secretion and the development of Leydig cells.

Conclusion: Our study revealed that the sustained proliferative capacity of Sertoli cells, their enriched signaling network, and the regulatory roles of CREB5 and circadian rhythms collectively represented unique testicular adaptations in chickens. These findings may hold extraordinary significance in understanding the molecular characteristics of poultry testicular development, and provide a plausible framework for explaining enhanced spermatogenesis in poultry.

Zinc, an essential trace element, plays a pivotal role in maintaining animal health and physiological functions. This review comprehensively examines zinc metabolism-including absorption dynamics across species (poultry, ruminants, and non-ruminants), transport mechanisms, storage in tissues, e.g., the liver, and excretion pathways-and its multifaceted effects on animal health. Zinc critically regulates aspects of growth and development, particularly bone formation, as its deficiency induces skeletal deformities in young animals. It modulates immune function through zinc finger proteins, influencing immune organ integrity, lymphocyte proliferation, and cytokine expression. Reproductive performance is significantly affected by zinc, with its deficiency causing impaired spermatogenesis; delayed sexual maturity in males; and reduced litter size, embryonic survival, and placental function in females. At the molecular level, zinc regulates the activity of enzymes (e.g., SOD), signaling pathways (MAPK, NF-κB), and transcription factors (MTF-1, Sp1) to maintain homeostasis. Both zinc deficiency (due to dietary insufficiency, malabsorption, or physiological stress) and zinc excess (from environmental pollution or feed oversupplementation) adversely affect health, disrupting mineral balance, enzyme function, and gut microbiota. In animal production, inorganic (zinc oxide, zinc sulfate) and organic (zinc methionine) sources of zinc increase growth, immunity, and productivity, although sustainable strategies are needed to mitigate environmental risks. Future research should focus on novel zinc formulations, precision nutrition, and interactions with gut microbiota to optimize livestock health and sustainable husbandry.

Background: Weaning-induced diarrhoea and growth retardation in piglets are associated with impaired intestinal barrier function and decreased levels of colonic short-chain fatty acids (SCFAs). Although SCFA supplementation has been proposed to mitigate these issues, the efficacy and optimal dosage of sodium isobutyrate remain unclear.

Results: We investigated the effects of sodium isobutyrate supplementation (500, 1,000, 2,000, and 4,000 mg/kg diet) on weaned piglets (Duroc × Landrace × Yorkshire, 28 d of age; n = 8). After a 28-d feeding trial, supplementation at 500-2,000 mg/kg significantly improved average daily gain and feed efficiency and reduced diarrhoea frequency, with maximal benefits observed at 1,000 mg/kg (P < 0.0001). Additionally, 500-1,000 mg/kg sodium isobutyrate supplementation increased the apparent digestibility of crude protein, organic matter, and crude fibre (P < 0.05). Serum biochemical parameters were unaffected, although secretory immunoglobulin A (SIgA) levels significantly increased upon supplementation with 500-1,000 mg/kg (P < 0.05). 16S rRNA gene sequencing indicated that sodium isobutyrate increased the abundance of beneficial colonic microbiota. The 1,000 mg/kg group presented the most pronounced effect, with a significant increase of the relative abundance of Prevotella and the greatest improvement in SCFA concentrations (P < 0.05). Metabolomics revealed elevated levels of colonic indole-3-lactic acid and 3-hydroxybutyrate upon supplementation with 1,000 mg/kg (P < 0.05). Transcriptomic analyses indicated activation of protein digestion and absorption pathways, and PI3K-Akt signalling, marked by TSG-6 upregulation and the suppression of ISG15 and DDIT4 expression (P < 0.05). Supplementation with 1,000 mg/kg was associated with improved intestinal barrier-related markers, including reduced serum D-lactate, diamine oxidase, and lipopolysaccharide levels, increased tight junction protein expression; activation of G protein-coupled receptors; and inhibition of TLR4/MyD88/NF-κB signalling (P < 0.05), suggesting enhanced barrier function.

Conclusions: In conclusion, dietary supplementation with 1,000 mg/kg sodium isobutyrate was associated with improved intestinal morphology, reduced serum permeability, increased expression of tight junction proteins, and enhanced immune function in weaned piglets, suggesting enhanced colonic barrier function and providing dosage guidance and mechanistic insights for future applications.

Background: Our previous study demonstrated that dietary supplementation of Bacillus subtilis enhanced growth performance and intestinal integrity in weaned pigs challenged with enterotoxigenic Escherichia coli (ETEC). Therefore, this study aimed to explore the impact of Bacillus subtilis on gut health and its role in modulating host-microbe interactions in post-weaning pigs.

Results: ETEC infection disrupted key metabolic pathways in distal colon, including glutathione, beta-alanine, and pyrimidine metabolism, indicating increased oxidative stress, impaired nucleotide balance, and amino acid catabolic stress. Bacillus subtilis supplementation induced distinct metabolomic and microbiome profiles in colon digesta of weaned pigs challenged with ETEC. Bacillus subtilis-treated pigs under ETEC challenge exhibited significant enrichment in amino acid- and energy-related pathways such as arginine biosynthesis, phenylalanine metabolism, pantothenate and CoA biosynthesis. ETEC infection induced microbial dysbiosis in the distal colon, resulting in decrease (P < 0.05) in abundance of Streptococcaceae and Enterobacteriaceae compared to healthy controls. Bacillus subtilis supplementation mitigated the ETEC-induced disruptions by increasing the relative abundance of beneficial bacterial families, including Lachnospiraceae and Bacteroidaceae.

Conclusion: Supplementation of Bacillus subtilis improves intestinal health and resilience against ETEC challenge by mitigating infection-induced metabolic disruptions and gut dysbiosis in weaned pigs.

Background: Fatty liver syndrome is a prevalent metabolic disorder in transition dairy cows, characterized by excessive hepatic lipid accumulation that impairs liver function and leads to systemic metabolic disturbances. Docosahexaenoic acid (DHA), a prominent n-3 polyunsaturated fatty acid (PUFA), not only exhibits anti-inflammatory and anti-oxidative properties, but also holds potential in ameliorating lipid metabolism. This study integrated in vitro bovine primary hepatocyte models and in vivo dairy cow trials to investigate the regulatory effects of DHA on hepatic lipid deposition.

Results: In vitro, 40 μmol/L DHA significantly reduced triglyceride (TAG) accumulation in steatotic hepatocytes by downregulating genes involved in fatty acid transport (FABP-1, CD36) and lipogenesis (DGAT2, FAS, SREBP-1C), while upregulating markers of lipolysis (CGI-58, ATGL) and fatty acid oxidation (ACADL, CPT1A, CPT2). Transmission electron microscopy (TEM) confirmed DHA-mediated restoration of mitochondrial ultrastructure and enhanced lipid droplet (LD)-mitochondria interactions. In vivo, dietary rumen-protected DHA (180 g/d) supplementation reduced hepatic lipid deposition, improved liver function (evidenced by decreased total bilirubin and alanine aminotransferase), reduced oxidative stress and inflammation (suppressed malondialdehyde, glutathione peroxidase, and lipopolysaccharide), coincided with relieving insulin resistance (reduced insulin and glucose, as well increased adiponectin) in dairy cows with fatty liver. These improvements may be attributed to increased expression of TOMM20 and MtCo-1, promoting mitochondrial biogenesis and β-oxidation, along with an elevated plasma n-3/n-6 ratio.

Conclusions: Collectively, these findings suggest that DHA supplementation represents a promising nutritional strategy for preventing spontaneous fatty liver in transition dairy cows by enhancing hepatic lipid clearance and restoring metabolic homeostasis.