Generation of double knockout cattle via CRISPR-Cas9 ribonucleoprotein(RNP)electroporation

Background Genome editing has been considered as powerful tool in agricultural fields.However,genome editing progress in cattle has not been fast as in other mammal species,for some disadvantages including long gestational periods,single pregnancy,and high raising cost.Furthermore,technically demanding methods such as microinjection and somatic cell nuclear transfer(SCNT)are needed for gene editing in cattle.In this point of view,electroporation in embryos has been risen as an alternative.Results First,editing efficiency of our electroporation methods were tested for embryos.Presence of mutation on embryo was confirmed by T7E1 assay.With first combination,mutation rates for MSTN and PRNP were 57.6%±13.7%and 54.6%±13.5%,respectively.In case of MSTN/BLG,mutation rates were 83.9%±23.6%for MSTN,84.5%±18.0%for BLG.Afterwards,the double-KO embryos were transferred to surrogates and mutation rate was identified in resultant calves by targeted deep sequencing.Thirteen recipients were transferred for MSTN/PRNP,4 calves were delivered,and one calf underwent an induction for double KO.Ten surrogates were given double-KO embryos for MSTN/BLG,and four of the six calves that were born had mutations in both genes.Conclusions These data demonstrated that production of genome edited cattle via electroporation of RNP could be effectively applied.Finally,MSTN and PRNP from beef cattle and MSTN and BLG from dairy cattle have been born and they will be valuable resources for future precision breeding.

Diet and monensin influence the temporal dynamics of the rumen microbiome in stocker and finishing cattle

Background Stocker cattle diet and management influence beef cattle performance during the finishing stage,but knowledge of the dynamics of the rumen microbiome associated with the host are lacking.A longitudinal study was conducted to determine how the feeding strategy from the stocker to the finishing stages of production affects the temporal dynamics of rumen microbiota.During the stocker phase,either dry hay or wheat pasture were provided,and three levels of monensin were administrated.All calves were then transported to a feedlot and received similar finishing diets with or without monensin.Rumen microbial samples were collected on d 0,28,85 during the stocker stage(S0,S28 and S85)and d 0,14,28,56,30 d before slaughter and the end of the trial during the finishing stage(F0,F14,F28,F56,Pre-Ba,and Final).The V4 region of the bacterial 16S rRNA gene of 263 rumen samples was sequenced.Results Higher alpha diversity,including the number of observed bacterial features and the Shannon index,was observed in the stocker phase compared to the finishing phase.The bacterial amplicon sequence variants(ASVs)differentiating different sampling time points were identified.Dietary treatments during the stocker stage temporally impact the dynamics of rumen microbiota.For example,shared bacteria,including Bacteroidales(ASV19)and Streptococcus infantarius(ASV94),were significantly higher in hay rumen on S28,S85,and F0,while Bacteroidaceae(ASV11)and Limivicinus(ASV15)were more abundant in wheat.Monensin affected rumen microbial composition at a specific time.Transportation to feedlot significantly influenced microbiome structure and diversity in hay-fed calves.Bacterial taxa associated with body weight were classified,and core microbiotas interacted with each other during the trial.Conclusions In summary,the temporal dynamics of the rumen microbiome in cattle at the stocker and finishing stage are influenced by multiple factors of the feeding strategy.Diet at the stocker phase may temporarily affect the microbial composition during this stage.Modulating the rumen microbiome in the steers at the stocker stage affects the microbial interactions and performance in the finishing stage.

Comparison of methods for deriving phenotypes from incomplete observation data with an application to age at puberty in dairy cattle

Background Many phenotypes in animal breeding are derived from incomplete measures,especially if they are challenging or expensive to measure precisely.Examples include time-dependent traits such as reproductive status,or lifespan.Incomplete measures for these traits result in phenotypes that are subject to left-,interval-and rightcensoring,where phenotypes are only known to fall below an upper bound,between a lower and upper bound,or above a lower bound respectively.Here we compare three methods for deriving phenotypes from incomplete data using age at first elevation(>1 ng/mL)in blood plasma progesterone(AGEP4),which generally coincides with onset of puberty,as an example trait.Methods We produced AGEP4 phenotypes from three blood samples collected at about 30-day intervals from approximately 5,000 Holstein–Friesian or Holstein–Friesian×Jersey cross-bred dairy heifers managed in 54 seasonal-calving,pasture-based herds in New Zealand.We used these actual data to simulate 7 different visit scenarios,increasing the extent of censoring by disregarding data from one or two of the three visits.Three methods for deriving phenotypes from these data were explored:1)ordinal categorical variables which were analysed using categorical threshold analysis;2)continuous variables,with a penalty of 31 d assigned to right-censored phenotypes;and 3)continuous variables,sampled from within a lower and upper bound using a data augmentation approach.Results Credibility intervals for heritability estimations overlapped across all methods and visit scenarios,but estimated heritabilities tended to be higher when left censoring was reduced.For sires with at least 5 daughters,the correlations between estimated breeding values(EBVs)from our three-visit scenario and each reduced data scenario varied by method,ranging from 0.65 to 0.95.The estimated breed effects also varied by method,but breed differences were smaller as phenotype censoring increased.Conclusion Our results indicate that using some methods,phenotypes derived from one observation per offspring for a time-dependent trait such as AGEP4 may provide comparable sire rankings to three observations per offspring.This has implications for the design of large-scale phenotyping initiatives where animal breeders aim to estimate variance parameters and estimated breeding values(EBVs)for phenotypes that are challenging to measure or prohibitively expensive.

Analysis on the Impact of Cattle Fattening Technology on Farmer Households in Atabae Timor-Leste

Agriculture is one of the priority sectors in Timor-Leste. Introducing new agriculture technology is crucial to enhance agricultural production. Practicing cattle fattening can increase beef cattle body weight and generate income to the beef cattle farmers. As farmers face problems including agricultural production decline, lack of forages and information and weather unfavourable. The study’s purpose was to examine the impact of adoption of cattle fattening technology on farmer households in Atabae administrative post, Bobonaro municipality in Timor-Leste. There were 200 beef cattle farmers households where randomly selected in four villages in Atabae. It consisted of 65 farmers practicing cattle fattening and 135 farmers non-practicing cattle fattening. Face to face interviews used structured questionnaire. Statistical analysis such as t-test and descriptive analysis were used to examine impact adoption of cattle fattening technology by farmers and factor constraints of cattle production and the solutions of it. The results indicated the average value of cattle and profit were significant different from zero and it is associated with practicing of cattle fattening. The average of labour used on cattle activities, the average of cattle sold, and total cost spent on cattle were not significant different from zero. The percentage of farmers said that factors constraints cattle production were shortage of water and forage (53%) and spend time on culture ceremony and lack of capital (33%). The number of farmers said that they collected water from river, feed cattle with sago and forage (55.3%) and cultivated forage (23.4%). This finding contributes information to the farmers, traders, and Timorese government to continue implementing cattle fattening activities as it enhances farmers’ income and developing cattle production.

Cattle Production and Lumpy Skin Disease of Smallholder Farmers in Svay Rieng Province

The cattle production in Romeas Haek district,Svay Rieng province,was developed remarkably,since there were some households raising cattle in large number,more than 20 heads.The grazing method of cattle was tethering and free grassing in the commune grass,since the natural grass and rice straw were the main source of cattle feed,however some of them supplemented their cattle with crop-byproducts,planting grass or concentrated feed.For the majority,BCS(Body Condition Scoring)of the cattle in those areas was 3 accounting for 52%-73.33%,but it was found the thin cattle has low BCS of 2 accounting for 11.11%to 40.00%and also fat cattle has BCS of 4 up to 27.78%.However,the average BCS varied with village which ranged from 2.68 to 3.17,but is not different in term of commune and sex of cattle.Besides facing with shortage of feed,the experience with diseases was also another concern,since 85.71%to 95.83%of the households faced this problem last year.Among the clinical signs found,lumpy skin was 100%,i.e.no one escaped from this problem,thus making them aware of vaccinating their cattle against some diseases such as FMD(Foot and Mouth Disease),HS(Hemorrhagic Septicemia)and LSD(Lumpy Skin Disease),but mostly vaccination was used against FMD.Because the LSD has occurred in these areas since 2020,then the seroprevalence was found in high positive up to 72.62%by Enzyme-Linked Immunosorbent Assay(ELISA)test.This positive rate was also varying by villages,ranging from 53.3%to 94.44%.But there was no association between positive cattle with commune,BCS,sex and age of cattle.In conclusion,the cattle production in Romeas Haek district,Svay Rieng province had developed markedly,however the shortage of feed and disease occurrence are the main challenges for farmer cattle producers,especially LSD outbreak last year.However,most of the farmers have been aware of the benefit of vaccination and had vaccinated their cattle against those main disease,such as FMD,HS and LSD.

Harnessing male germline epigenomics for the genetic improvement in cattle

Sperm is essential for successful artificial insemination in dairy cattle,and its quality can be influenced by both epi-genetic modification and epigenetic inheritance.The bovine germline differentiation is characterized by epigenetic reprogramming,while intergenerational and transgenerational epigenetic inheritance can influence the offspring’s development through the transmission of epigenetic features to the offspring via the germline.Therefore,the selec-tion of bulls with superior sperm quality for the production and fertility traits requires a better understanding of the epigenetic mechanism and more accurate identifications of epigenetic biomarkers.We have comprehensively reviewed the current progress in the studies of bovine sperm epigenome in terms of both resources and biological discovery in order to provide perspectives on how to harness this valuable information for genetic improvement in the cattle breeding industry.

The eQTL colocalization and transcriptome‑wide association study identify potentially causal genes responsible for economic traits in Simmental beef cattle

Background A detailed understanding of genetic variants that affect beef merit helps maximize the efficiency of breeding for improved production merit in beef cattle.To prioritize the putative variants and genes,we ran a com-prehensive genome-wide association studies(GWAS)analysis for 21 agronomic traits using imputed whole-genome variants in Simmental beef cattle.Then,we applied expression quantitative trait loci(eQTL)mapping between the genotype variants and transcriptome of three tissues(longissimus dorsi muscle,backfat,and liver)in 120 cattle.Results We identified 1,580 association signals for 21 beef agronomic traits using GWAS.We then illuminated 854,498 cis-eQTLs for 6,017 genes and 46,970 trans-eQTLs for 1,903 genes in three tissues and built a synergistic network by integrating transcriptomics with agronomic traits.These cis-eQTLs were preferentially close to the transcription start site and enriched in functional regulatory regions.We observed an average of 43.5%improvement in cis-eQTL discovery using multi-tissue eQTL mapping.Fine-mapping analysis revealed that 111,192,and 194 variants were most likely to be causative to regulate gene expression in backfat,liver,and muscle,respectively.The transcriptome-wide association studies identified 722 genes significantly associated with 11 agronomic traits.Via the colocalization and Mendelian randomization analyses,we found that eQTLs of several genes were associated with the GWAS signals of agronomic traits in three tissues,which included genes,such as NADSYN1,NDUFS3,LTF and KIFC2 in liver,GRAMD1C,TMTC2 and ZNF613 in backfat,as well as TIGAR,NDUFS3 and L3HYPDH in muscle that could serve as the candidate genes for economic traits.Conclusions The extensive atlas of GWAS,eQTL,fine-mapping,and transcriptome-wide association studies aid in the suggestion of potentially functional variants and genes in cattle agronomic traits and will be an invaluable source for genomics and breeding in beef cattle.

Investigating Prevalence of Bovine Tuberculosis in Cattle in an Agro-Pastoral Community in Awdal Region, Somaliland

Awdal region is the most northwesterly province of Somaliland. The region is one of the agro-pastoral livelihood zones in Somaliland, where farming and agricultural production are the predominant livelihood sources. IGAD (Intergovernmental Authority on Development) Sheikh Technical University of Science (ISTUS) worked to study the prevalence of Bovine Tuberculosis (TB) among cattle in Awdal region of Somaliland. The aim was to inform public health and Veterinary experts on having one-health approach to infectious diseases among humans and animals. The serum that was stored at -20?C was transported to IGAD Sheikh Technical University of Science (ISTUS) for further analysis using BOVIGAM serological test (Sandwich ELISA). The results indicate that Bovine Tuberculosis is highly prevalent in the study area (10.1%). The high prevalence recorded in the current study could be due to the consumption of raw milk and lack of proper control strategies in place to control the transmission of the disease between animals, between animals and wildlife and between animals and humans. Hence, an awareness creation campaign should be created on bTB transmission and its public health significance to cattle owners, milk and meat consumers and people who are in close proximity to cattle. In addition, testing and eradication programme should be implemented where applicable.

Molecular evidence and phylogenetic delineation of spotted fever group Rickettsia species in Amblyomma ticks from cattle in Gauteng and Limpopo Provinces,South Africa

Objective:To determine the prevalence of tick-borne pathogens with a particular focus on Rickettsia spp.in ticks collected from cattle in Gauteng and Limpopo Provinces,South Africa.Methods:A total of 200 ticks were collected from cattle within the Madala livestock,Pretoria,Gauteng Province and in Mankweng Township,Polokwane,Limpopo Province in 2019.The ticks were morphologically identified and processed individually for a total genomic DNA extraction.Specific primers targetting ompA,ompB,and the 17KDa genes were used for a molecular screening and delineation of Rickettsia from the extracted genetic materials using polymerase chain reaction(PCR)technique.PCR amplicons of positive samples were sequenced bidirectionally using the Sanger sequencing method.Sequences generated were processed and analysed using appropriate bioinformatics software.Results:The ticks were morphologically identified as Amblyomma spp.PCR profiling of the genomic DNA samples revealed the presence of the Rickettsia pathogen in 42(21%)of the ticks collected from both Provinces.Out of the genes profiled,14(7%)were positive for 17KDa,42(21%)for ompA and 32(16%)were positive for ompB genes respectively.The nucleotide blast of the sequenced genomes showed high similarity,as high as 100% with other reference Rickettsia(R.)africae in the GenBank.The phylogenetic analysis of the sequences further validated them as R.africae with their characteristic clustering pattern with related reference sequences.Conclusions:There is an abundance of R.africae in Amblyomma ticks collected from cattle in the study areas.This has serious public health implications as individuals who accidentally get infested with the ticks could acquire R.africae.Hence,adequate precautions in terms of sensitization of farmers about the risk and mass mobilization drive to control the vectors in the areas are highly recommended to safeguard public health.

Dynamic chromatin architectures provide insights into the genetics of cattle myogenesis

Background Sharply increased beef consumption is propelling the genetic improvement projects of beef cattle in China.Three-dimensional genome structure is confirmed to be an important layer of transcription regulation.Although genome-wide interaction data of several livestock species have already been produced,the genome structure states and its regulatory rules in cattle muscle are still limited.Results Here we present the first 3D genome data in Longissimus dorsi muscle of fetal and adult cattle(Bos taurus).We showed that compartments,topologically associating domains(TADs),and loop undergo re-organization and the structure dynamics were consistent with transcriptomic divergence during muscle development.Furthermore,we annotated cis-regulatory elements in cattle genome during myogenesis and demonstrated the enrichments of promoter and enhancer in selection sweeps.We further validated the regulatory function of one HMGA2 intronic enhancer near a strong sweep region on primary bovine myoblast proliferation.Conclusions Our data provide key insights of the regulatory function of high order chromatin structure and cattle myogenic biology,which will benefit the progress of genetic improvement of beef cattle.

Signatures of positive selection for local adaptation of African native cattle populations:A review

Cattle are central to the lives and diverse cultures of African people.It has played a crucial role in providing valuable protein for billions of households and sources of income and employment for producers and other actors in the livestock value chains.The long-term natural selection of African cattle typically signals signatures in the genome,contributes to high genetic differentiations across breeds.This has enabled them to develop unique adaptive traits to cope with inadequate feed supply,high temperatures,high internal and external parasites,and diseases.However,these unique cattle genetic resources are threatened by indiscriminate cross-breeding,breed replacements with exotic cosmopolitan breeds,and climate change pressures.Although there are no functional genomics studies,recent advancements in genotyping and sequencing technologies have identified and annotated limited functional genes and causal variants associated with unique adaptive and economical traits of African cattle populations.These genome-wide variants serve as candidates for breed improvement and support conservation efforts for endangered cattle breeds against future climate changes.Therefore,this review plans to collate comprehensive information on the identified selection footprints to support genomic studies in African cattle to confirm the validity of the results and provide a framework for further genetic association and QTL fine mapping studies.

Prevalence of Tick Infestations and Tick-Borne Diseases in Cattle in Cameroon

Ticks induce huge production and economic losses in the livestock industry and create serious environmental, animal and human health problems. The study was carried out to characterize tick species and determine the prevalence of tick infestation and tick-borne diseases in cattle in Cameroon. Tick and blood samples were collected from a total of 742 animals and analyzed to determine the type of tick and haemoparasites using standard procedures. Overall, four tick species namely Amblyomma variegatum (75.09%), Rhipicephalus microplus (19.43%), Rhipicephalus decoloratus (0.88%) and Hyalomma marginatum (0.18%) and six blood disease agents including Anapalasma marginale (11.29%), Ehrlichia ruminantium (3.52%), Babesia bovis (1.32%), Babesia major (0.44%), Anaplasma phagocytophilum (0.29%) and Dermatophilus congolensis (3.37%). Various co-infections were recorded and the predominant associations were Amblyomma variegatum-Rhipicephalus microplus (4.06%) and Amblyomma variegatum-Hyalomma marginatum (0.36%);Anaplasma-Ehrlichia (12%), Anaplasma-Dematophylus (8%), Babesia-Anaplasma-Ehrlichia (14%) and Babesia-Anaplasma-Ehrlichia-Dermato-phylus (5%). Breed, sex, age and locality significantly influenced the rate of tick infestation while locality, breed and age significantly influenced the detection of blood disease agents in the study.

Co‑infection of fasciolosis and hydatidosis and their financial loss in cattle slaughtered at Wolaita Sodo municipal abattoir,southern Ethiopia

Fasciolosis and hydatidosis are the world’s most common zoonotic major parasitic ailments of domesticated animals with financial and public health implications.A cross-sectional study was conducted on 384 randomly selected cattle slaughtered at Wolaita Sodo municipal abattoir to estimate the prevalence and associated risk factors for co-infection of hydatidosis and fasciolosis using the ante-and postmortem examination techniques.Of the 384 examined cattle,4.17%were found to harbor co-infections of hydatidosis and fasciolosis.Similarly,the prevalence of concurrent fasciolosis and hydatidosis infections was 76.56%and 23.44%in local and crossbred animals,respectively.The current study took into account risk factors such as age,breed,origin,and body condition score;however,there is a statistically insignificant association between the risk factors and the prevalence of concurrent fasciolosis and hydatidosis infection.In this study,overall fasciolosis was recorded at a rate of 9.38%,with the highest prevalence of F.hepatica at 8.59%,followed by unidentified flukes at 4.17%and F.gigantica at 0.78%.Likewise,the single prevalence of hydatidosis was recorded at 10.94%.Of the 142 examined cysts,the liver alone harbors 54 cysts,and the lung alone harbors 88 cysts,with a total of 43 calcified,21 sterile,56 viable,9 nonviable,and 13 mixed cysts.The predicted yearly financial loss from organ condemnation was 15,436,142.00 ETB Birr.This study demonstrated that hydatidosis and fasciolosis are two relatively widespread parasite diseases of cattle in Ethiopia,causing significant economic loss attributable to organ rejection and indirect weight loss.Thus,awareness of the impact of the disease on the community could disrupt the parasite’s life cycle,and its economic significance was forwarded to other points.

Socio-Economic and Technical Characteristics of Beef Cattle Breeding in Ndé Division, West Region of Cameroon

Insight is here provided into the socio-economic and technical characteristics of cattle production in the Ndé Division (West Cameroon region). Using a semi-structured questionnaire, information on the activity was assessed following onsite visits and interviewing breeders. Through a random sampling scheme, 110 breeders in the four subdivisions of the Ndé Division were shadowed. The majority (98.18%) of breeders were men aged 20 to 40 and married (91.82%). They belong to the Mbororo ethnic group, having cumulated more than 10 years in the activity. Most respondents (50.91%) did not attend school and earn their living mainly from livestock (78.18%). Cattle were raised for sale and to feed the breeder’s family (77.27%). The main mode of acquisition of animals was through inheritance (81.82%). The cattle breeds were mostly made up of white Fulani (70%), living in private farms using a combination of stake and barbed wires (67.27%) as fences. The combination of natural fodder and cooking salt was used by most breeders (59.09%) as a daily ration. Reproduction was by natural mating (97.07%). Parasites (internal and external) and foot-and-mouth disease were the main diseases reported by the majority of farmers. Self-treatment (50%) was the main prophylactic measure taken by farmers in case of disease symptoms. Cattle herders faced several challenges, such as insufficient pasture (67.27%), agro-pastoral conflicts (76.36%) and diseases (90.91%). Cattle breeding was rather a widespread activity with no particular restriction.

Analysis of Investigation on Ebian Spotted Cattle and Suggestions

Ebian spotted cattle has the ability to adapt to the local natural ecological environment,and is one of the excellent local cattle breeds in Sichuan.Ebian spotted cattle is a breed of cattle for both service and meat use and formed through long-term natural selection and artificial selection.Because of the weak development and utilization of this breed,the economic benefits of excellent breeds have not been fully brought into play,and farmers'enthusiasm in breeding is poor,so that the number of Ebian spotted cattle has reduced year by year.In order to strengthen the protection,development and utilization of Ebian spotted cattle as a local excellent breed,combined with the third national survey of livestock and poultry genetic resources in 2021,Ebian spotted cattle was investigated,and a comprehensive,scientific and objective analysis of its population numbers was conducted.Besides,reasonable suggestions were put forward.

MED4 gene positively affects preadipocyte differentiation in Chinese red steppe cattle

Background:The regulatory genes related to lipid metabolism affect the intramuscular fat(IMF)content and improve meat quality traits.Mediator Complex Subunit 4(MED4),a vitamin D receptor protein,affects vitamin D,livestock growth,carcass traits,and triglyceride deposition.However,the physiological function of the MED4 gene on bovine adipocyte differentiation remains unknown.Methods:This study explored the function of the MED4 gene in preadipocyte differentiation in Chinese Red Steppe cattle.The overexpression plasmid and the interference sequences of the MED4 gene were constructed to detect the effects of the MED4 gene on adipogenesis and biomakers using quantitative polymerase chain reaction and western blotting.Results:The MED4 gene had significantly high expression during preadipocyte differentiation(p<0.05).Overexpression of the MED4 gene increased the expression of the PPARγgene,a preadipocyte differentiation biomarker,improved cellular lipid droplets and triglycerides accumulation,and positively accelerated adipocyte maturation(p<0.05).Interference of the MED4 gene can negatively regulate preadipocyte differentiation.Conclusion:This study showed that the MED4 gene may affect the preadipocyte differentiation and adipogenesis in Chinese Red Steppe cattle by regulating the PPARγgene.

Effects of Maize Silage Harvest Stage on Growth Performance and Economic Benefits of Beef Cattle

[Objectives]This study aimed to investigate the effects of whole-crop maize silage harvested at different stages on growth and economic benefits of beef cattle.[Methods]A total of 30 Simmental crossbred cattle weighing about 378 kg were randomly divided into three groups,respectively fed for 70 days with whole-crop maize silage harvested at milk stage(GroupⅠ),dough stage(GroupⅡ)and physiological maturity stage(GroupⅢ).Moreover,the cattle in all groups were given the same concentrate diet.[Results]There were significant differences in dry matter,crude protein and neutral detergent fiber between whole-crop maize silages harvested at different stages(P<0.05).The dry matter in GroupⅡandⅢwas significantly higher than that in GroupⅠ(P<0.05).The crude protein content peaked in GroupⅡ,up to 6.37%,which was significantly higher than that in GroupⅠ(by 12.74%,P<0.05)and GroupⅢ(by 9.26%,P<0.05).Starch content significantly increased with the postponing of maize harvest(P<0.05).The content of neutral detergent fiber in Group I was significantly higher than that in GroupⅡ(P<0.05)and GroupⅢ(P<0.05).The average daily weight gain in GroupⅡwas 8.53%higher than that in GroupⅠ(P<0.05)and 3.70%higher than that in GroupⅢ(P>0.05).The dry matter intake in GroupⅡwas significantly higher than that in GroupⅠ(P<0.05)and GroupⅢ(P<0.05).There was no significant difference in feed/gain ratio between the groups(P>0.05).The economic benefit in GroupⅡwas the highest,up to 9.99 yuan/day per capita.,followed by that in GroupⅢ,9.79 yuan/day per capita,and that in GroupⅠwas the lowest,only 8.03 yuan/day per capita.[Conclusions]The whole-crop maize silage harvested at dough stage has the best quality and produces the highest economic returns for beef cattle.

Vitamin A administration at birth promotes calf growth and intramuscular fat development in Angus beef cattle

Background: Marbling, or intramuscular fat, is an important factor contributing to the palatability of beef. Vitamin A, through its active metabolite, retinoic acid, promotes the formation of new fat cells(adipogenesis). As intramuscular adipogenesis is active during the neonatal stage, we hypothesized that vitamin A administration during the neonatal stage would enhance intramuscular adipogenesis and marbling.Methods: Angus steer calves(n = 30), in a completely randomized design, were randomly allotted to three treatment groups at birth, receiving 0, 150,000, or 300,000 IU of vitamin A at both birth and one month of age.A biopsy of the biceps femoris muscle was collected at two months of age. After weaning at 210 d of age, steers were fed a backgrounding diet in a feedlot until 308 d of age, when they were transitioned to a high concentrate finishing diet and implanted with trenbolone/estradiol/tylosin mixture. Steers were harvested at an average of 438 d of age. All diets were formulated to meet nutrient requirements.Results: Weaning weight and weight during the backgrounding phase were linearly increased(P < 0.05) by vitamin A level, though no difference in body weight was observed at harvest. Intramuscular fat of steers at 308 d of age, measured by ultrasound, quadratically increased(P < 0.05) with vitamin A level from 4.0±0.26 % to 4.9±0.26 %.Similarly, carcass marbling score in the ribeye quadratically increased(P < 0.05).Conclusion: Administration of vitamin A at birth increased weaning weight and enhanced marbling fat development.Thus, vitamin A administration provides a practical method for increasing marbling and early growth of beef cattle.

The Study on the Effects of Chinese Herbal Mixtures on Growth,Activity of Post-Ruminal Digestive Enzymes and Serum Antioxidant Status of Beef Cattle

Sixteen Limousin×Luxi crossbred beef cattle [（199.4±8.67） kg] were used to evaluate the effects of Chinese herbal mixtures （CHM） on growth, activities of post-ruminal digestive enzymes and serum antioxidant status of beef cattle. Treatments were control （no CHM supplementation） and three formulations of CHM （CHM-A, CHM-B and CHM-C） that were arranged as completely randomized design. The calves were fed in indoor individual feeding barn with total mixed ration for 90 d. The CHM-A, CHM-B, and CHM-C was incorporated into the diet at the level of 20 g kg-1 DM （dry matter） of concentrate. The cattle were weighted at the beginning, at the end and every 15 d between to determine growth rate. Blood sample was taken every 30 d to analyze activities of total superoxide dismutase （T-SOD） and glutathione peroxidase （GSH-PX） and concentration of malondialdehyde （MDA）. The cattle were slaughtered at the end of experiment and chymus samples from various section of the post-ruminal digestive tract were collected to analyze enzymes activities. All cattle had similar average daily gain, but cattle supplemented with CHM-A tended faster growth （P=0.08） compared to the control and other CHM treatments. Supplementation of CHM did not affect pH of chymus in any section of the post-ruminal digestive tract. Activities of pepsin, trypsin, chymotrypsin, and lipase in chymus samples were enhanced （P0.05） to various extents by supplementation of CHM-A, CHM-B, and CHM-C depending on the enzymes and the site of the digestive tract. Amylase activity was increased only by CHM-A and CHM-C from chymus sample collected at the ileum. Supplementation of CHM-A and CHM-B reduced （P0.05） concentration of MDA, but did not affect GSH-PX activity in the serum of cattle throughout the entire experimental period. Cattle supplemented with CHM-B also had higher （P0.05） T-SOD activity in the serum at day 30 and 60 as compared with the control and the other two CHM treatments. Chinese herbal mixtures supplemented at the levels of 20 g kg-1 DM of concentrate increased post-ruminal digestive enzymes activity and enhanced serum antioxidant status. Inclusion of CHM-A and CHM-B in the diet may be favourable for ruminant production.

Development of genome engineering technologies in cattle: from random to specific

The production of transgenic farm animals(e.g., cattle) via genome engineering for the gain or loss of gene functions is an important undertaking. In the initial stages of genome engineering, DNA micro-injection into one-cell stage embryos(zygotes) followed by embryo transfer into a recipient was performed because of the ease of the procedure.However, as this approach resulted in severe mosaicism and has a low efficiency, it is not typically employed in the cattle as priority, unlike in mice. To overcome the above issue with micro-injection in cattle, somatic cell nuclear transfer(SCNT) was introduced and successfully used to produce cloned livestock. The application of SCNT for the production of transgenic livestock represents a significant advancement, but its development speed is relatively slow because of abnormal reprogramming and low gene targeting efficiency. Recent genome editing technologies(e.g.,ZFN, TALEN, and CRISPR-Cas9) have been rapidly adapted for applications in cattle and great results have been achieved in several fields such as disease models and bioreactors. In the future, genome engineering technologies wil accelerate our understanding of genetic traits in bovine and wil be readily adapted for bio-medical applications in cattle.