We investigated whether combining human chorionic gonadotropin (hCG) with ketoprofen after timed artificial insemination (TAI) improves pregnancy rates and explored the underlying mechanisms through serum metabolomics and in vitro endometrial cell analysis. Dairy cows (n = 710) were allocated to three groups: hCG + ketoprofen (1500 IU hCG on day 7 and ketoprofen at 3 mg/kg on days 15-16 of TAI; n = 249), hCG only (1500 IU hCG on day 7 of TAI; n = 246), or control (n = 215). After adjusting for parity, days in milk, body condition score, and milk yield using multivariable logistic regression, the overall treatment effect was significant (χ² = 7.24, df = 2, P = 0.027). The hCG + ketoprofen group had a higher pregnancy rate than the control (adjusted OR = 1.63; 95% CI: 1.12-2.37; P = 0.028, Tukey-adjusted). However, the hCG-only group did not differ significantly from the control group (adjusted OR = 1.15; 95% CI: 0.79-1.68; P = 0.756, Tukey-adjusted). Serum metabolomic profiling by liquid chromatography-mass spectrometry (LC-MS) identified 17 significantly differential metabolites between hCG + ketoprofen and hCG only groups, with KEGG pathway enrichment revealing unsaturated fatty acid biosynthesis as the most prominently altered pathway. In lipopolysaccharide (LPS) challenged bovine endometrial epithelial cells (BEECs), ketoprofen significantly enhanced cell viability (0.5998 ± 0.0043 vs. 0.4498 ± 0.0037; p < 0.0001), reduced reactive oxygen species (ROS) accumulation, and suppressed PGF2α secretion by 36% (29.2 ± 2.77 vs. 45.6 ± 5.36 pg/mL; p < 0.0001). Additionally, ketoprofen downregulated the expression of key prostaglandin synthesis and steroidogenesis genes, including PTGS2, PLA2G4A, PTGFR, VEGFA, STAR, and CYP11A1. These findings suggest that hCG + ketoprofen treatment may enhance pregnancy rates through potentially complementary mechanisms, though these proposed mechanisms remain hypothetical and require in vivo confirmation.

Zearalenone (ZEA) is a common contaminant in crops and animal feed. However, research on the effects of ZEA on animal mammary tissue is relatively limited. Sulforaphane (SFN) is a naturally active compound mainly derived from cruciferous vegetables (such as broccoli), with significant antioxidant and cytoprotective effects. The purpose of this study is the effect of SFN on ZEA-induced toxicity in bovine mammary epithelial cells (MAC-T). By treating MAC-T cells with different concentrations of ZEA and SFN for 24 h, the results showed that different concentrations of ZEA (10, 20, 40, 60, 80, or 100 μM) could inhibit MAC-T cell viability. Treatment with SFN at concentrations of 1, 2.5, and 5 μM had no significant effect on cell viability. The results of combined treatment with 10 μM ZEA and 1, 2.5, or 5 μM SFN showed that SFN could significantly reverse the decrease in cell viability caused by ZEA; reduce the increase in lactate dehydrogenase (LDH) release, reactive oxygen species (ROS), and malondialdehyde (MDA) content induced by ZEA; and increase the levels of glutathione (GSH), superoxide dismutase (SOD), and mitochondrial membrane potential that were decreased by ZEA. SFN can significantly inhibit the upregulation of interleukin 6 (IL-6), tumor necrosis factor alpha (TNF-α), and interleukin 1 beta (IL-1β) induced by ZEA exposure and markedly reverse the increase in cell apoptosis rate caused by ZEA. Compared with the control group, the expression of genes nuclear factor erythroid 2–related factor 2 (Nrf2), heme oxygenase 1 (HO-1), NAD(P)H:quinone oxidoreductase 1 (NQO1), glutamate-cysteine ligase modifier subunit (GCLM), and glutathione peroxidase 1 (GPX1) was significantly reduced in the ZEA group, while the addition of SFN effectively increased the expression levels of these genes. Corresponding protein detection results were consistent with the trends in gene expression. This study demonstrated that SFN alleviates ZEA-induced damage to MAC-T cells by activating the Nrf2 pathway, providing a theoretical basis for the subsequent application of SFN in dairy farming to prevent and control breast health risks related to mycotoxins.

Intramuscular fat (IMF) content in beef cattle is a critical determinant of beef meat quality, as it positively influences juiciness, tenderness, and palatability. In China, the crossbreeding of Wagyu and Angus is a prevalent method for achieving a better marbling level. However, the molecular mechanisms governing IMF regulation in these crossbreeds remain poorly understood. To elucidate the mechanism of IMF deposition in these crossbred cattle, we conducted a comparative transcriptomic analysis of longissimus dorsi muscles and livers from cattle with divergent IMF content. RNA-seq revealed 940 and 429 differentially expressed genes (DEGs) in the liver and muscle, respectively, with 60 genes co-differentially expressed (co-DEGs) in both tissues. Functional enrichment highlighted lipid metabolism pathways including fatty acid β-oxidation, PPAR signaling, and glycerolipid metabolism. A total of eleven genes including ACAA2, ACADL, ACOX2, CPT1B, CPT2, LPL, SLC27A1, ACAT1, GK, ACOX3, and ACSM5, were screened as key candidate genes for IMF deposition. A “liver–muscle” regulatory network of IMF deposition was built to illustrate the tissues’ interaction. The reliability of the transcriptomic data was verified by quantitative reverse real-time PCR (qRT-PCR). Our findings provide novel molecular markers for increasing the IMF content and accelerating the genetic improvement of beef quality traits in crossbred cattle.

To investigate the regulatory mechanisms underlying milk production traits, transcriptional sequencing (RNA-seq) and metabolomic analysis with liquid chromatography-MS were implemented in blood and serum samples from 25 lactating Holstein cows across multiple lactation stages. We identified 16,147, 15,859, and 16,010 expressed genes (fragments per kilobase million >1) and 160, 332, and 142 differentially expressed genes (DEG) during early, peak, and late lactation, respectively; the DEG were significantly enriched in adipocytokine, PPAR, and cAMP signaling and influenced cholesterol, vitamin B6, and fat metabolism; 9 candidate genes were identified by comparing QTLs related to milk production, reproduction, and disease resistance traits. Additionally, 303 metabolites in 22 categories were detected, in which 19, 22, and 32 metabolites displayed differential abundance in the early versus peak, early versus late, and peak versus late comparison groups, respectively. Such differentially abundant metabolites (DAM) were associated with fatty acid biosynthesis of unsaturated fatty acids; valine, leucine, and isoleucine; and degradation. Pearson correlation analysis between DEG and DAM identified significant associations (|r value| >0.6; P-value <0.05); all DEG-DAM pairs were visualized in a 9-quadrant plot. Six fatty acids-caprylic acid, heptadecanoic acid, methyl hexadecanoic acid, oleic acid, palmitic acid, and stearic acid-showed significant associations with DEG across all pairwise comparisons. Subsequently, overlapping regions between DEG and QTLs were identified, revealing 21 DEG that co-localized with milk production-related QTLs.

Genomic imprinting is an epigenetic regulation in mammals in which a small subset of genes is monoallelically expressed dependent on their parental origin. A large imprinted domain, SGCE/PEG10 locus, is located on human chromosome 7q21s and mouse proximal chromosome 6. However, genomic imprinting of bovine SGCE/PEG10 cluster has not been systematically studied. In this study, we investigated allele expression of 14 genes of the SGCE/PEG10 locus in bovine somatic tissues and term placenta using a single nucleotide polymorphism (SNP)-based sequencing method. In addition to SGCE and PEG10, two conserved paternally expressed genes in human and mice, five other genes (TFPI2, GNG11, ASB4, PON1, and PON3) were paternally expressed. Three genes, BET1, COL1A2, and CASD1, exhibited tissue-specific monoallelic expression. CALCR showed monoallelic expression in tissues but biallelic expression in the placenta. Three genes, GNGT1, PPP1R9A, and PON2, showed biallelic expression in cattle. Five differentially methylated regions (DMRs) were found to be associated with the allelic expression of TFPI2, COL1A2, SGCE/PEG10, PON3, and ASB4 genes, respectively. The SGCE/PEG10 DMR is a maternally hypermethylated germline DMR, but TFPI2, COL1A2, PON3, and ASB4 DMRs are secondary DMRs. In summary, we identified five novel bovine imprinted genes (GNG11, BET1, COL1A2, CASD1, and PON1) and four secondary DMRs at the SGCE/PEG10 locus.

Genomic imprinting is an epigenetic regulation mechanism in mammals resulting in the parentally dependent monoallelic expression of genes. Imprinting disorders in humans are associated with several congenital syndromes and cancers and remain the focus of many medical studies. Cattle is a better model organism for investigating human embryo development than mice. Imprinted genes usually cluster on chromosomes and are regulated by different methylation regions (DMRs) located in imprinting control regions that control gene expression in cis. There is an imprinted locus on human chromosome 16q24.1 associated with congenital lethal developmental lung disease in newborns. However, genomic imprinting on bovine chromosome 18, which is homologous with human chromosome 16 has not been systematically studied. The aim of this study was to analyze the allelic expressions of eight genes (CDH13, ATP2C2, TLDC1, COTL1, CRISPLD2, ZDHHC7, KIAA0513, and GSE1) on bovine chromosome 18 and to search the DMRs associated gene allelic expression. Three transcript variants of the ZDHHC7 gene (X1, X2, and X5) showed maternal imprinting in bovine placentas. In addition, the monoallelic expression of X2 and X5 was tissue-specific. Five transcripts of the KIAA0513 gene showed tissue- and isoform-specific monoallelic expression. The CDH13, ATP2C2, and TLDC1 genes exhibited tissue-specific imprinting, however, COTL1, CRISLPLD2, and GSE1 escaped imprinting. Four DMRs, established after fertilization, were found in this region. Two DMRs were located between the ZDHHC7 and KIAA0513 genes, and two were in exon 1 of the CDH13 and ATP2C2 genes, respectively. The results from this study support future studies on the molecular mechanism to regulate the imprinting of candidate genes on bovine chromosome 18.

Carbohydrate is the most common macronutrient consumed across all phases of the diet and acts as a potential regulator in modulating the gut microbiota in animals. However, the influences of dietary non-fibrous carbohydrate (NFC) to neutral detergent fiber (NDF) in different ratios on gut microbiota, metabolites, intestinal immunity, and growth performance have not been fully explored. A total of 135 healthy weaned rabbits (45.1 ± 0.7 d of age) with an average body weight of 1.08 ± 0.07 kg were randomly divided into five groups. Under the same other nutrient levels, rabbits were fed diets with NFC/NDF ratios of 0.7 (T1), 1.0 (T2), 1.3 (T3), 1.6 (T4), and 1.9 (T5). During the 28-day experiment, T3 rabbits showed the highest final body weight and the lowest feed-to-weight ratio than T5 rabbits (P < 0.05) but no significant difference with T1 or T2 rabbits. The expression of cecal pro-inflammatory factors IL-1β and TNF-α was increased in the T4 and T5 than in those of other groups (P < 0.05). Conversely, the tight junction proteins (ZO-1, Claudin-1, and Occludin) were decreased to varying degrees in the T4 and T5 groups. The pH value in the cecal digesta of T5 rabbits was lower than that of T1, T2, and T3 (P < 0.05), while the concentration of volatile fatty acids and propionate was higher than those of T1, T2, and T3 rabbits (P < 0.05). In terms of gut microbiota, at the phylum level, the relative burden of Firmicutes and Actinobacteria in T2 rabbits was the highest (P < 0.05), and the relative burden of Proteobacteria in T5 rabbits was higher than that of other groups (P < 0.05). At the genus level, the relative burden of Ruminococcus was higher in T2 and T3 rabbits than that of other groups, and T5 rabbits have the lowest relative burden of Ruminococcus. Combination analysis showed that cecal metabolites were positively associated with fermentation-related phenotypes and the burden of Firmicutes (P < 0.05). In conclusion, different dietary NFC/NDF ratios can affect the intestinal immune response and growth performance of rabbits, and there was a positive effect when dietary NFC/NDF = 1.0–1.3.

试验旨在分析燕麦青贮替代日粮中燕麦干草和羊草对奶牛生产性能和血清生化指标的影响.选取平均胎次、体重、产奶量差异均不显著的荷斯坦泌乳奶牛32头,随机分为4组,每组8个重复,每个重复1头奶牛.对照组奶牛饲喂基础日粮,试验组分别使用等干物质含量的燕麦青贮替代基础日粮中的100％燕麦干草(Ⅰ组)、50％燕麦干草(Ⅱ组)和100％羊草(Ⅲ组).预试期14d,正式试验期35 d.结果显示,燕麦青贮的干物质(DM)、酸性洗涤纤维(ADF)、中性洗涤纤维(NDF)含量均低于燕麦干草和羊草(P＜0.05),Ca含量显著高于燕麦干草和羊草(P＜0.05).与对照组相比,Ⅰ组、Ⅱ组奶牛的乳脂率显著提高(P＜0.05),Ⅱ组乳脂量显著提高(P＜0.05),试验Ⅱ组、Ⅲ组的乳蛋白率显著提高(P＜0.05).试验Ⅱ组奶牛的养殖利润高于其他组.研究表明,使用燕麦青贮替代燕麦干草和羊草对奶牛生产性能和机体健康无不良影响,且使用燕麦青贮替代50％燕麦干草可提高奶牛的产奶量和乳品质,经济效益较好.

[Objective] This study aimed to estimate the genetic parameters of body weight and body size for Simmental beef cattle in Hebei province and to provide a reference for breeding programs. [Method] This study was based on the body weight and size records of 266 Simmental beef cattle in Hebei Tianhe Beef Cattle Breeding Limited Company from 2015 to 2021, which included body weight, body height, hip cross height, body length, chest girth, abdomen circumference, and cannon circumference. [Result] Genetic parameters of body weight and size traits were estimated using AI-REML and EM algorithm of DMU software combined with animal models. The results showed that the heritability estimates of body weight and body size traits were 0.41, 0.41, 0.45, 0.45, 0.48, 0.31, and 0.66, respectively. The genetic correlations between body weight and body size traits ranged from 0.20（body height） to 0.79（chest girth）, and the phenotypic correlations ranged from 0.14（hip cross height） to 0.23（chest girth）. The genetic correlations between body size traits ranged from-0.70（abdomen circumference and cannon circumference） to 0.92（body height and hip cross height）, and the phenotypic correlations ranged from-0.10（abdomen circumference and cannon circumference） to 0.94（body height and hip cross height）. [Conclusion] Body weight and body size traits were high heritability traits, and a strong positive genetic correlation was between body weight and body size traits, except for the cannon circumference. Strengthening the selection and breeding of these traits would help to improve the growth and development performance of Simmental beef cattle.

本试验采用体外发酵法评价不同粗饲料分级指数(GI)燕麦干草的饲用价值,为其在奶牛生产应用中提供理论依据.选取3种不同GI的燕麦干草分为3组,试验1组、试验2组和试验3组GI值分别为4.26、10.98、11.60 MJ/d,体外发酵24 h.结果表明:(1)试验2组和试验3组干物质、粗蛋白质和中性洗涤纤维降解率显著高于试验1组(P<0.01),其中干物质降解率比试验1组分别高50.95％、55.37％;中性洗涤纤维降解率分别高54.41％、50.47％.(2)试验2组和试验3组氨态氮、乙酸、丙酸、丁酸、戊酸和TVFA高于试验1组(P<0.05),其中TVFA比试验1组分别高13.39％和11.05％.(3)各组优势菌门由拟杆菌门(Bacteroidota)和厚壁菌门(Firmicutes)组成,两者占整个菌群89％以上,其中厚壁菌门相对丰度具有差异显著趋势(P=0.07);各组优势菌属组成相同,各组中未分类理研菌科(Un-classified_f_Rikenellaceae)、未知属-绒毛杆菌科(Norank_f_Muribaculaceae)、纤维杆菌属(Fibrobacter)具有显著性差异(P<0.05),其中试验2组和试验3组纤维杆菌属比试验1组分别低51.36％和55.45％.综合结果,不同GI等级燕麦干草对奶牛营养物质降解率和瘤胃发酵特性具有明显影响,且GI等级越高,其营养价值就越好.

With the development of high-throughput sequencing, RNA sequencing has been widely used in the identification of candidate genes for complex traits in livestock, and the functional genes and mutations with large genetic effects on milk production traits can provide molecular information for marker-assisted selection to increase the selection accuracy and accelerate genetic gain in dairy cattle. Our previous study on the liver transcriptome of Holstein cows found that acyl-CoA dehydrogenase (ACADVL) and interferon regulatory factor 6 (IRF6) are differentially expressed between dry and peak lactation periods, as well as that they are involved in lipid metabolism and the proliferation and differentiation of mammary epithelial cells. Thus, the two genes were considered candidates for milk traits. Hence, this study further collected 1186 Holstein cows from 110 sire families to investigate their genetic associations with milk yield and composition traits. By resequencing the entire exons and 2000 bp of the 5′ and 3′ flanking regions of the two genes, we identified eight SNPs in ACADVL and eight SNPs in IRF6. Subsequent single-locus association analyses showed that the eight SNPs in ACADVL were all significantly associated with milk fat yield, fat percentage, and protein yield (p values ≤ 0.0001–0.0414), and the eight SNPs in IRF6 were associated with milk, fat, and protein yields in the first or second lactation (p values ≤ 0.0001–0.0467). Using Haploview 4.2, one haplotype block with eight of the SNPs in ACADVL (D’ = 0.99–1.00) and two haplotype blocks in IRF6 with three of the SNPs in each were observed (D’ = 0.98–1.00). Similarly, the haplotype combinations of ACADVL were significantly associated with milk yield, fat percentage, fat yield, and protein yield in the two lactations (p values ≤ 0.0001–0.0125), and those of IRF6 were associated with five milk traits (p values ≤ 0.0001–0.0263). Furthermore, with the JASPAR software, it was predicted that the SNPs 19:g.26933503T>C in ACADVL and 16:g.73501985G>A in IRF6 changed the transcription factor binding sites of ZEB1, PLAGL2, and RHOXF1, implying their impacts on the expressions of the corresponding genes. Our findings demonstrated that the ACADVL and IRF6 genes have significant genetic effects on milk yield and composition traits, and the valuable SNPs might be used as genetic markers for genomic selection programs in dairy cattle.

试验旨在研究青贮处理对3个燕麦品种(H44号、张莜13号、坝莜3号)瘤胃降解特性的影响,筛选出饲用价值较优的燕麦品种,为燕麦的生产利用提供参考.试验选用3只装有永久性瘤胃瘘管的荷斯坦阉牛,采用尼龙袋法对燕麦青贮前和青贮后的营养成分及瘤胃降解率进行评定.结果显示:①青贮前,燕麦坝莜3号的CP、EE含量显著高于H44号和张莜13号(P<0.05),木质素(ADL)、酸性洗涤不溶蛋白(ADIP)的含量显著低于H44号和张莜13号(P<0.05).青贮处理后,与同品种燕麦草相比,3种燕麦青贮的粗蛋白(CP)、脂肪(EE)、粗灰分(Ash)、可溶性蛋白(SCP)含量显著提高(P<0.05),而干物质(DM)、NDF、ADL、中性洗涤不溶蛋白(NDIP)、ADIP、淀粉(Starch)的含量显著降低(P<0.05).坝莜3号青贮的CP、SCP显著高于H44号青贮(P<0.05),ADL、ADIP含量显著低于H44号青贮和张莜13号青贮(P<0.05).②瘤胃降解试验表明:青贮前坝莜3号CP、酸性洗涤纤维(ADF)有效降解率显著高于H44号和张莜13号(P<0.05),3种燕麦草的NDF有效降解率差异不显著(P>0.05).与同品种燕麦草相比,3种燕麦青贮DM、CP、NDF、ADF的快速降解部分显著提高(P<0.05),慢速降解部分显著降低(P<0.05);3种燕麦青贮的DM、CP、NDF、ADF的有效降解率均显著高于同品种的燕麦草(P<0.05).坝莜3号青贮DM和CP的有效降解率显著高于H44号青贮和张莜13号青贮(P<0.05).综合各种指标:青贮能更好地保存燕麦草的营养成分,提高了燕麦草的消化率,其中坝莜3号青贮的营养成分和瘤胃降解率最优.

试验旨在研究青贮处理对两种甜高粱营养成分及瘤胃降解率的影响.选取3头装有永久性瘤胃瘘管的荷斯坦阉牛,采用尼龙袋法对甜高粱青贮前和青贮后的营养成分及瘤胃降解特率进行评定.结果 表明,青贮前,巨能甜高粱的粗蛋白(CP)含量显著高于大龙甜高粱(P＜0.05),非蛋白氮(NPN)、中性洗涤纤维(NDF)、酸性洗涤纤维(ADF)含量显著低于大龙甜高粱(P＜0.05).青贮后,两种甜高粱青贮的CP、NPN、粗脂肪(EE)含量均显著提高(P＜0.05),NDF含量显著降低(P＜0.05).青贮前,巨能甜高粱的干物质(DM)和CP的快速降解部分显著高于大龙甜高粱(P＜0.05),ADF的快速降解部分显著低于大龙甜高粱(P＜0.05);巨能甜高粱的CP慢速降解部分显著高于大龙甜高粱(P＜0.05),DM和ADF的慢速降解部分的降解速率显著低于大龙甜高粱(P＜0.05).青贮后,两种甜高粱的DM、CP、NDF和ADF的快速降解部分和有效降解率显著提高(P＜0.05).研究表明,巨能甜高粱具有较好的营养价值和瘤胃降解特性,制作成青贮饲料在反刍动物体内具有更高的消化率,是比较适合饲喂反刍动物的优质饲草品种.

This study aimed to (1) estimate the prevalence of cow-level high somatic cell count (SCC) in Chinese dairy herds and (2) identify potential factors associated with cow- and herd-level SCC variables. The monthly data on dairy herd improvement were collected from a total of 131 dairy herds in 11 provinces in China in 2019. Mixed models were constructed using the cow composite milk SCC and the variance of cow SCC as dependent variables separately and parity, seasons, days in milk (DIM), herd size, and farm types (family-owned vs. company-owned) as fixed effects, accounting for the nested random herd and cow effect. We used negative binomial regression using herd-level SCC-related variables, namely, monthly proportion of high SCC, monthly proportion of new high SCC, monthly proportion of chronic high SCC, and monthly proportion of new chronic high SCC as dependent variables separately against seasons, herd size, and farm types with the random herd effect. The overall average prevalence of high SCCs for each month per farm was 0.26 (2.5–97.5% quantile: 0–0.56). Company-owned farms performed better in herd SCC management. Seasons were significantly associated with all the aforementioned variables, and summer and autumn were the seasons associated with worse outcomes in herd SCCs. This study is the first to assess high SCC in a large number of Chinese dairy herds, which is useful for farms to tailor the on-farm mastitis control programs in China.

肢蹄病是肉牛一种常见且多发病,给肉牛养殖场带来很大影响.近年来,随着肉牛产业的规模化发展,肢蹄病的防治工作也越来越重要.本文根据我市某肉牛场肢蹄病发病情况进行了发病原因分析,提出了相应的防控方法,为同行提供参考.

本文介绍了肉牛遗传疾病的种类、表现和遗传基础,对骡蹄症、骨硬化症、蜘蛛腿综合征、侏儒症、歪尾综合征、肌肉增生和红细胞生成性卟啉症等7种肉牛遗传病进行了概述.对我国肉牛遗传病的了解和研究具有重要意义.

本试验旨在利用尼龙袋法比较不同品种全株玉米青贮前后瘤胃降解特性的差异.试验采用2×3双因素试验设计,选择玉米7367号、玉米7377号、玉米7387号3个全株玉米品种为研究对象,采用尼龙袋法比较3种全株玉米青贮前和青贮后的营养成分和瘤胃降解特性,旨在探讨适合河北省种植的全株玉米青贮品种.结果表明:1)青贮前玉米7377的粗蛋白(CP)和非蛋白氮(NPN)含量显著高于玉米7367和玉米7387(P<0.05);玉米7677和玉米7377的中性洗涤纤维(NDF)含量显著低于玉米7387(P<0.05);玉米7677的酸性洗涤纤维(ADF)含量显著低于玉米7377和玉米7387(P<0.05).与青贮前同品种全株玉米相比,3种全株玉米青贮后的CP、粗脂肪(EE)、粗灰分(Ash)、钙(Ca)、磷(P)、NPN含量显著提高(P<0.05),NDF含量显著下降.玉米7367青贮的CP和NPN含量显著高于玉米7377青贮和7387青贮(P<0.05);玉米7677青贮和7377青贮的NDF和ADF含量显著低于玉米7387青贮(P<0.05).2)不同品种全株玉米青贮前的DM、CP、NDF、ADF瘤胃降解率有显著差异,玉米7367的干物质(DM)和NDF有效降解率显著高于玉米7377和玉米7387(P<0.05);玉米7377的CP有效降解率显著高于玉米7367和玉米7387(P<0.05).青贮处理能显著提高3种全株玉米DM、CP、NDF和ADF的快速降解部分(P<0.05),降低其慢速降解部分(P<0.05),显著提高其有效降解率(P<0.05).玉米7367青贮的DM、CP、NDF、ADF有效降解率显著高于玉米7377和玉米7387(P<0.05).综合表明青贮处理能很好地保存3种全株玉米的营养成分,显著提高DM、CP、NDF和ADF的瘤胃降解率;玉米7367青贮前和青贮后的营养成分和瘤胃降解率显著高于玉米7377和玉米7387,在本试验中是比较适合河北省种植的全株玉米青贮品种.

本试验旨在探究高精料肥育模式下奶公犊的生长规律及该模式下的生产效益.试验选用300头日龄为210±2.07d、体重为243±17.01kg的荷斯坦牛公犊进行试验,综合月龄和体重指标进行肥育阶段划分,分为肥育前期(7～9月龄)、饲料过渡期(10～11月龄)、肥育后期(12～18月龄),通过提高日粮精料比例,逐阶段提高日粮能量浓度,试验期共360d.结果 表明:肥育前期,牛群个体平均增重为70kg,其中7～8月龄平均日增重在1.4kg以上;饲料过渡期日增重为1.43kg,较9月龄日增重(1.00kg)有明显提升;肥育后期12月龄与13月龄日增重分别为1.46kg和1.6kg,在该饲养阶段内群体达到最高增重水平,随后日增重呈波动式下降趋势;17月龄以后平均日增重降到1kg以下,且随着肥育月龄增大,肥育期间耗料增重比呈上升趋势.经济效益方面,高精料肥育奶公犊模式全期毛利润与年均利润率比传统外购架子牛肥育模式分别高1311元/头和23个百分点.由此可见,奶公犊高精料肥育模式可以在我国大、中型奶公犊肥育场推广使用.

由于腺相关病毒载体(adeno-associated viral vector,AAV)本身的侵染不具有神经元特异性,其在神经系统相关研究中会存在侵染范围不符合试验要求的情况,因此本试验拟研究不同滴度和注射方式对病毒侵染范围的影响.结果显示,在注射较高滴度的AAV2-CMV-EGFP(1.3×101 mg/L)3周后,其侵染范围可由延髄中缝苍白核(raphe pallidus nucleus,RPa)区域延伸至下丘脑室旁核(paraventricular nucleus,PVN)区域;较低滴度(1.3 × 108 mg/L)结合压力注射的方式可以在一定程度上限制AAV的侵染范围,并且载体携带的EGFP荧光基团在637 nm波段不具有明显的假阳性信号.

试验旨在研究不同微生物组合制成的复合添加剂对全株玉米青贮发酵品质、营养价值及有氧稳定性的影响.试验分4个处理,即对照组(空白对照)、XL组(添加植物乳杆菌≥1×1011 CFU/g,布氏乳杆菌≥1×109 CFU/g,屎肠球菌≥1×109 CFU/g)、BL组(植物乳杆菌≥3×108 CFU/g,戊糖片球菌≥1×109 CFU/g)、HY组(枯草芽孢杆菌≥6×109 CFU/g、产脘假丝酵母≥3×109 CFU/g、嗜酸乳杆菌≥1×109 CFU/g),每组3个重复,蜡熟期全株玉米青贮60 d后,进行全株玉米青贮发酵品质、营养成分及有氧稳定性测定.结果表明:微生物添加剂能不同程度地促进青贮发酵系统中乳酸和总酸生成,改善玉米青贮感官品质和发酵品质,其中HY组玉米青贮在感官品质和发酵品质均呈最佳;XL、BL、HY组玉米青贮的相对饲料价值提高(P<0.05),HY组降低了玉米青贮中中性洗涤纤维(NDF)、酸性洗涤纤维(ADF)、粗蛋白质和粗脂肪含量(P<0.05),而淀粉含量增加(P<0.05),相对饲料价值在各组中最高(P<0.05),XL组与BL组全株玉米青贮的营养成分含量无显著差异,但综合各项营养指标,XL组青贮玉米的相对饲料价值优于BL组(P<0.05);与对照组相比,XL组玉米青贮的有氧稳定性降低(P<0.05),有氧稳定时长比其他组短25～33 h(P<0.05),BL、HY微生物组合对玉米青贮的有氧稳定性无显著影响.综上所述,HY微生物组合在全株玉米青贮中使用效果最佳.