Animal Biotechnology最新文献

Mastitis, an inflammation of the bovine mammary gland, reduces dairy productivity and poses significant health risks to Ethiopian dairy cattle. This study aimed to identify genomic regions associated with milk somatic cell score (SCS) and estimate its genetic parameters. The dataset included 1647 phenotypic cows, 6964 genotyped animals, and 39,976 single nucleotide polymorphism (SNP) markers. A single-step genome-wide association study (ssGWAS) was conducted, accounting for fixed effects of parity, genomic breed composition, altitude, and lactation stage, and random effects of herd-year-calving-season and permanent environment. Genetic variance using 20 adjacent SNPs sliding windows explaining ≥1% of the total genetic variance were used for candidate genes and quantitative trait loci (QTL) identifications. The estimated heritability of SCS was 0.11 ± 0.06. Genomic regions on BTA 15, 19, and 26 were identified associated with SCS, encompassing 116 genes, including MPP7, MPP8, MMP13, BIRC2, BIRC3, BTRC, SRSF1, and MPO, which are involved in immunity, inflammation, apoptosis, antimicrobial defense, and tissue remodeling. Gene enrichment analysis revealed that the genes are involved collagen catabolic process and IL-17 signaling pathway. These findings provide insights into genomic regions that could be targeted in genomic selection to improve mastitis resistance in Ethiopian dairy cattle.

This study aimed to 1) Establish relationships between feed conversion efficiency (FCE; live weight gain/intake) and several biomarkers in pigs using blood and hair samples, and 2) Investigate the relative FCE performance of pigs from maternal vs. terminal genetic lines fed high vs. low energy diets. 80 male pigs (Large White x Landrace) were fed for 56 days. The terminal genetic line and pigs fed the high energy diet had 5% and 15% higher FCE than the maternal genetic line and pigs fed the low energy diet, respectively. Blood nitrogen isotopic fractionation (Δ¹⁵N; animal δ¹⁵N - feed δ¹⁵N) explained 34% more variation of FCE, compared with the blood insulin‑like growth factor‑1 (IGF‑1). The turnover rate of δ¹⁵N in plasma was faster than δ¹⁵N in blood, suggesting that blood and plasma δ¹⁵N can predict long‑term versus short‑term FCE changes. Pigs fed the high energy diets showed 13% higher live weight gain, 16% greater high standard carcass weight, and 38% higher carcass backfat than those on low‑energy diets. In conclusion, Δ¹⁵N is a more effective FCE biomarker for pigs compared to IGF‑1. Hair samples were less predictive of FCE than blood‑derived biomarkers, suggesting further refinement in the methodology of harvesting hair samples.

This research focused on assessing the molecular prevalence of Bovine Leukemia Virus (BLV) in different cattle farms throughout Khyber Pakhtunkhwa and characterizing the dominant BLV genotypes by analyzing partial sequences of the gp51 gene. A total of 1,250 blood samples were collected from cattle of both sexes, various age groups (<1 year, 1-3 years, 3-5 years, and >5 years), and different breeds (Friesian, Jersey, Sahiwal, Achai, and crossbred) from multiple cattle farms. Of the 1,250 samples tested, BLV was detected in 136 (10.88%) using nested PCR. Risk factor analysis revealed a significantly higher prevalence of BLV in exotic breeds and older cattle. To confirm the findings and genotype the BLV isolates, four PCR-positive samples were sequenced. Phylogenetic analysis identified the isolates as belonging to genotype I, closely related to GI BLV isolates from Japan. Furthermore, the isolates in this study formed a tightly clustered group, suggesting a common origin from an earlier virus introduced into the host population in the study area.

The efficacy of microbial fermented feeds (FF) is highly dependent on microbial composition, underscoring the need for locally sourced, cost-effective formulations to advance sustainable livestock production. In this study, bacteria from corn silage (CSB) were screened for the preparation of solid-state fermented feed (SFF). In addition, for the purpose of comparison, purchased marketed fermentation bacteria (PMB) for SFF were also tested using the same methodology. Anaerobic fermentation was carried out by adding 5% CSB, PMB, and saline to conventional feeds at 37 °C, respectively. Then 10 g of fermentation samples was collected on days 0, 3, and 5, respectively. The composition and diversity of the microbial community were subsequently analyzed using high-throughput sequencing. The pH, titratable acidity (TA), and nutrient index of the feeds before and after fermentation were determined. High-throughput sequencing results showed that the dominant genera of CSB were Weissella, Pseudomonas, and Bacteroidetes, whereas the dominant genera of PMB were Bacteroidetes, Bacillus, Pseudomonas, and Enterococcus. The dominant genera in unfermented feeds (CK) were Chlorophyta, Mitochondria, and Pseudomonas. In addition, the dominant genera in SFF supplemented with CSB and PMB were Weissella and Bacteroidetes, respectively. Compared with CK, pH of SFF supplemented with CSB and PMB decreased gradually, and TA increased significantly and then decreased gradually during fermentation. Similarly, Crude fiber content was higher than CK in both CSB and PMB, while crude fat content was lower than CK for all of them. The study illustrates that CSB can be used to ferment porcine solid feeds and that CSB solid feed microorganisms may promote intestinal absorption of complex polysaccharides in pigs, which lays a certain theoretical foundation for the application of CSB to SFF.

This study explored the effects of dietary supplementation with a probiotic blend of Lactococcus lactis subsp. lactis and Bacillus velezensis on the performance and health of growing rabbits. Ninety-six rabbits were allocated into three groups and fed for eight weeks on diets containing either no probiotic (control), a low-dose probiotic (1 ml/kg of each probiotic strain), or a high-dose probiotic (2 ml/kg of each probiotic strain). Probiotic inclusion, particularly at the higher level, significantly enhanced final body weight, feed conversion ratio, and overall performance. Improvements were also noted in carcass characteristics, with greater yields in both forequarters and hindquarters. Blood biochemical analysis revealed elevated antioxidant enzyme activity and immunoglobulin levels, alongside reductions in lipid fractions and better liver and kidney function indicators. Meat quality also benefited, as shown by lower pH, reduced water holding capacity and cooking loss, and more favorable color metrics. Microbial analysis of cecal and feed samples indicated a notable increase in beneficial bacteria and a decline in pathogenic species in the probiotic-treated groups. These findings suggest that combined probiotic supplementation is a promising strategy for enhancing growth performance, meat quality, and gut health in rabbit production systems to produce a good final meat product.

This study aimed to investigate the expression profiles of the myogenic regulatory genes MYOD1, MYOG, MYF5, MYF6, and MSTN in longissimus dorsi muscle, as well as the correlation of the expression levels of these genes with carcass characteristics and growth performance in the Kivircik and Hungarian Merino sheep breeds. The expression levels of the MYF5, MYF6, and MYOG genes were found to be significantly correlated with the rib proportion, the expression level of the MYOG gene was identified as being the main determinant of variations in the rib proportion in the Kivircik lambs. The regression analysis results revealed that the expression levels of the MYF5 and MSTN genes played an essential role in determining the cold carcass dressing percentage in Hungarian Merino lambs. Further, as a result of the regression analysis, the model including the expression level of the MYF6 gene demonstrated that this gene could be responsible for 36.4% of the differences observed in cold carcass weight. In conclusion, the findings of this study suggest that the expression levels of the MYF5, MYF6, and MYOG genes were associated with various carcass traits, particularly in the Kivircik breed, and these genes hold potential as markers for enhancing breed productivity.

Cold ambient temperatures decrease semen quality. However, the effects of dietary energy sources on semen quality under cold stress conditions remain unclear. In the present study, purebred Yorkshire boars (572 days old) were fed diets supplemented with either fat (FAT), amino acid complex (AA), or dietary fiber beet pulp (BP) during the winter. The experiment was conducted for 84 days. Results showed that BP supplementation increased semen volume, sperm count, plasma immunoglobulin M level and the relative abundance of fecal norank_f_Erysipelotrichaceae (positively correlated with sperm viability), while decreasing the levels of interleukin-1β and lipopolysaccharide-binding protein (p < 0.05). AA supplementation increased sperm density, progressive motility, and sperm velocity during weeks 7-12 (p < 0.05), while no significant effect was observed during weeks 1-6. The relative abundance of fecal Lachnospiraceae_UCG-006 (positively correlated with sperm velocity) also was increased in the AA group. FAT supplementation had a minor effect on sperm progressive motility and average curvilinear velocity, which may be related to the increased relative abundance of fecal T2WK15B57 (negatively correlated with semen quality). In summary, daily supplementation with BP and AA improves sperm quality under cold stress conditions, likely through improvements in inflammation, immunity and intestinal microflora.

Kalmyk cattle are an important meat breed in Kazakhstan, valued for their strong physique, genetic stability, and adaptability. In this study, we investigated the mRNA expression of ELOVL fatty acid elongase 6 (ELOVL6) and CREB-regulated transcription coactivator 2 (CRTC2) across multiple tissues, and further examined their genetic variations and associations with growth and carcass traits in 200 Kalmyk cattle. Expression analysis showed that CRTC2 was most highly expressed in the heart and liver, whereas ELOVL6 was predominantly expressed in the spleen and large intestine, highlighting their tissue-specific expression patterns. In addition, we identified a polymorphic SNP (g.16511290A > G) in the 3'UTR of ELOVL6, with three genotypes (AA, AG, GG) and the G allele being dominant (0.520). Polymorphism information content (PIC) analysis indicated high genetic diversity at this locus. Importantly, this SNP was significantly associated with live weight and body oblique length (p < 0.05), and individuals carrying heterozygous AG genotype showed higher body weight and length. Collectively, these findings suggest that g.16511290A > G within ELOVL6 may serve as useful molecular markers for body measurements and meat traits, providing valuable resources for marker-assisted selection in beef cattle breeding programs.