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.

Sequence Variations in the Bovine IGF-I and IGFBP3 Genes and Their Association with Growth and Development Traits in Chinese Beef Cattle

The objective of this study was to determine the genotype effects of the bovine insulin-like growth factor Ⅰ （IGF-Ⅰ） and its binding protein 3 （IGFBP3） genes on growth and development traits in beef cows, including 130 Chinese Simmental, 42 Nanyang, and 47 Luxi Yellow cattle. Sequence variations in the bovine IGF-Ⅰ and IGFBP3 genes were investigated by single strand conformation polymorphism （SSCP）. SSCPs were detected in 6 fragments, which is the 5＇-flanking region, the 2nd exon, the 5th exon, and the 5th intron of the IGF-1 gene, and the 2nd exon, the 3rd exon of the 1GFBP3 gene. Two polymorphisms, an A-to-G transition in the 2rid exon of the IGF-Ⅰ gene and a T-to-C transition in the 2rid exon of IGFBP3 gene were detected in 3 breeds. The allele frequencies of 2 polymorphisms were 0.0411 （A）, 0.9589 （B）, and 0.7237 （A）, 0.2763 （B）, respectively. These 2 loci were analyzed to associate with body weight, height at withers, body length, heart girth, rump width, and beef production index （BPI） at 0, 6, 12, 24, and 36-month old. The IGFBP3 locus was shown to be associated with rump width, heart girth at 24-month and 36-month. Animals with BB genotype had higher rump width （24.86 ± 0.47） cm at 24-month and （27.50 ± 0.63） em at 36-month. The heart girth was highest for the individuals with BB genotype （171.33 ± 1.84） cm and higher than those with AB genotype （166.68 ± 1.13） cm （P〈 0.05） at 36-month.

Effects of marker density and minor allele frequency on genomic prediction for growth traits in Chinese Simmental beef cattle

Genomic selection has been demonstrated as a powerful technology to revolutionize animal breeding. However, marker density and minor allele frequency can affect the predictive ability of genomic estimated breeding values （GEBVs）. To investigate the impact of marker density and minor allele frequency on predictive ability, we estimated GEBVs by constructing the different subsets of single nucleotide polymorphisms （SNPs） based on varying markers densities and minor allele frequency （MAF） for average daily gain （ADG）, live weight （LW） and carcass weight （CW） in 1 059 Chinese Simmental beef cattle. Two strategies were proposed for SNP selection to construct different marker densities： 1） select evenly-spaced SNPs （Strategy 1 ）, and 2） select SNPs with large effects estimated from BayesB （Strategy 2）. Furthermore, predictive ability was assessed in terms of the correlation between predicted genomic values and corrected phenotypes from 10-fold cross-validation. Predictive ability for ADG, LW and CW using autosomal SNPs were 0.13＋0.002, 0.21＋0.003 and 0.25＋0.003, respectively. In our study, the predictive ability increased dramatically as more SNPs were included in analysis until 200K for Strategy 1. Under Strategy 2, we found the predictive ability slightly increased when marker densities increased from 5K to 20K, which indicated the predictive ability of 20K （3% of 770K） SNPs with large effects was equal to the predictive ability of using all SNPs. For different MAF bins, we obtained the highest predictive ability for three traits with MAF bin 0.01-0.1. Our result suggested that designing a low-density chip by selecting low frequency markers with large SNP effects sizes should be helpful for commercial application in Chinese Simmental cattle.

Distribution of Selenium and Mercury in Heilongjiang Province and Its Effect on Body of Beef Cattle

The aim of this study was to study the distribution of Selenium （Se） and Mercury （Hg） in feed and drinking water in Heilongjiang Province and the effect on body of beef cattle. The experiment selected four areas of Qiqihar, Harbin, Jixi and Hegang Cities in Heilongjiang Province. In each area, a pasture was selected. Five beef cattle from each ranch were collected. At the same time, blood, liver, muscle, kidney, urine and faece of the cattle were collected, as well as drinking water, feed and formula feed from the ranch. The contents of Se and Hg in the collected samples were detected by inductively coupled plasma mass spectrometry. The results showed that the contents of Se in liver, kidney, urine and blood of beef cattle were increased with the increase of Se contents in drinking water, while the contents of Se in muscle tissue and manure were decreased. When the contents of Se in feed increased, the contents of them in muscle, manure and liver of beef cattle were increased frst and then decreased, while the contents of Se in kidney, urine and blood were decreased frst and then increased. When Hg contents in drinking water were increased, the contents of them in beef cattle tissue, blood and manure were increased frst and then decreased, and the contents of Se in urine were increased frst and them decreased. And when Hg contents in feed increased, the contents of Se and Me were also increased. In conclusion, Se and Hg contents in these areas were within the safety standards, meanwhile, the contents of Se and Hg in body tissues of beef cattle were affected to varying degrees by the contents of selenium and mercury in feed.

Rumen Degradation Characteristics of Six Types of Common Roughage in Khorchin Beef Cattle in Tongliao City

[Objective] The paper was to study the degradation characteristics of different types of roughage in Khorchin beef cattle. [Method] The nylon bag method was used to determine the rumen degradability of six types of roughage： dry matter （DM）, crude protein （CP）, neutral detergent fiber （NDF） and acid detergent fiber （ADF）. [Result] Among the six types of roughage, alfalfa hay had the highest effective degradability of DM and CP in rumen; followed by alfalfa block, corn silage, leymus chinensis and corn stover, and the effective degradability of rice straw was lowest. In terms of effective degradability of NDF and ADF, alfalfa hay was the most effective, while leymus chinensis was the least effective. [Conclusion] Considering degradation characteristics of six types of roughage in Khorchin beef cattle, alfalfa hay possesses the highest nutritional value, while rice straw has the lowest value.

Effects of Different Compound Trace Element Premixed Materials on Beef Cattle Production Performance and Anti-oxidation Capacity

In this study,the effects of two types of premixed materials with different combinations of trace elements on the production performance and antioxidant capacity of simmental beef cattle were examined.Fifteen healthy simmental beef cattle of similar weight(approximately 330 kg),the same age(12 months),without castration,and a good physique were divided into three groups,with five beef cattle in each group.Food of Group Ⅰ beef cattle was supplemented with a commercially marketed 5% compound trace element premixture for fine beef cattle.Food of Group Ⅱ beef cattle was supplemented with a 5% compound microelement premixture for beef cattle that was designed to address local nutrient deficiencies and surpluses.In the blank control group,the beef cattle were not fed a premixture.The pretest period was 15 days,and the test period was divided into prefattening(45 days)and postfattening(45 days)stages.Body weight and body size indices were recorded at 1,2 and 3 months,and blood samples were collected regularly.In Group Ⅰ,the daily weight gain increased significantly by 15.7% compared with that of the control group.The largest daily weight gain was in Group Ⅱ,which increased by 31.6% compared with that in the control.During the test period of 90 days,the body size indices of the three different groups increased in different months,with significant increases in the indices for both test groups compared with those of the control.In Group Ⅰ,the activity of CP,the total activity of SOD and Cu-Zn-SOD increased significantly(p<0.05)compared with those in the control group,with a highly significant increase observed in GSH-PX activity(p<0.01).In Group Ⅱ,the increases in the activity of CP and the total activity of SOD and Cu-Zn-SOD were highly significant compared with those in the control group(p<0.01).In addition,a significant increase was observed in GSH-PX activity(p<0.05).Based on pretest results,the concentrations of Cu,Zn,Mo,Mn,Se and Co in the blood of experimental beef cattle were lower than those of the normal range.After feeding for 90 days,the concentrations of Cu,Zn,Mo,Mn,Se and Co in the blood of Groups Ⅰ and Ⅱ were significantly higher than those in the control group(p<0.05).The concentrations of elements in the blood of Group Ⅱ were close to the appropriate levels.Thus,the effects of the specifically designed compound microelement premixture on the prevention of nutrient imbalances and control of beef cattle nutrition metabolism and the production of fattened beef cattle were significant.

Prevalence and fuoroquinolone resistance of Campylobacter spp.isolated from beef cattle in Japan

Beef is a source of human Campylobacter infections.Antimicrobial treatment is needed when patients are immuno‑compromised or have other comorbidities.Therefore,we investigated the prevalence and antimicrobial resistance of Campylobacter spp.in beef cattle in Japan.Rectal swab samples were collected from 164 beef cattle at an abattoir between March 2021 and August 2021,and Campylobacter spp.were isolated from 94(57.3%)cattle.C.jejuni and C.coli were isolated from 68 and 26 cattle,respectively.For Campylobacter jejuni,the resistant rates against ampicillin,tetracycline and ciprofoxacin were 20.6,75.0 and 64.7%,respectively.For C.coli,the resistant rates against ampicil‑lin,tetracycline and ciprofoxacin were 53.8,76.9 and 88.5%,respectively.No Campylobacter isolates were resistant to erythromycin.By multilocus sequence typing,C.jejuni and C.coli isolates were classifed into 22 and 2 sequence types(STs).The top three STs of C.jejuni were ST806(12 isolates),ST21(nine isolates),and ST459(eight isolates).The most frequent ST of C.coli was ST1068(23 isolates).The results suggest that Campylobacter spp.are prevalent in the gastrointestinal tract of beef cattle slaughtered at abattoirs.Furthermore,the administration of erythromycin is efec‑tive against human campylobacteriosis caused by beef consumption.Monitoring the prevalence and antimicrobial resistance of Campylobacter spp.in beef cattle could be useful for managing the risk of human campylobacteriosis.

Effects of Plant Oil Mixture on Production Performance,Carcass and Beef Quality in Beef Cattle

[Objective] To study the effects of plant oil mixture on production performance, carcass and beef quality in beef cattle. [Method] Single-factor randomized blocks design was used. Sixteen healthy Yanbian yellow bulls having close body weight were selected and randomly divided into four groups, four cattle per group. Been oil, safflower oil and sunflower oil were mixed respectively at a volume ratio of 11：5：4. The oil blend was added to the daily diets of beef cattle respectively at a proportion of 4%, 5% and 6%. The effects of the plant oil mixture on production performance, carcass and beef quality were investigated. [ Result.] Compared with the control cattle, the experimental cattle had significantly lower feed intake （P 〈 0.05）, non-significantly higher efficiency of feed utilization, and significantly lower digestibility of crude fiber and calcium （P 〈 0.05）. With the increasing level of plant oil, the digestibility of dry matter showed a decreasing trend. The digestibility of dry matter was significantly lower in the cattle fed on the plant oil mixture at a level of 6% than in the control （ P 〈 0.05）. The plant oil mixture had no effect on the digestibility of crude protein, ether extract, crude ash, nitrogen-free extract and phosphorus. With the increasing level of plant oil, the serum content of high-density lipoprotein showed an increasing trend. The serum content of high-density lipoprotein was significantly higher in the cattle fed on the plant oil mixture at a level of 6% than in the control （ P 〈 0.05）. With the increasing level of plant oil, the content of total cholesterol showed an increasing trend, whereas the content of low-density lipoprotein showed a decreasing trend. Moreover, other indicators did not change significantly. The experimental cattle had larger eye muscle area and better beef quality than the control group. The content of crude protein and ether extract in beef increased with the increasing level of plant oil. [ Conclusion] The plant oil mixture added to the daily feed decreases intake and digestibility of crude fiber and calcium but has no remarkable effect on production performance of beef cattle. The addition also increases eye muscle area and improves beef quality, thereby improving quality of carcass and beef. The proportion of the plant oil mixture should be added at a proportion lower than 5%.

Comparative Advantages and Specialized Production of Beef Cattle Industry in Yanbian Region

[Objective] To provide theoretical guidance for development of beef cattle industry in Yanbian region. [Method] Aggregated compara- tive advantage index and concentration factor were used to compare beef industry in Yanbian region and Jilin Province. [ Result] Beef cattle industry in Yanbian region had aggregated comparative advantages, and its concentration factor tended to rise year by year. [ Conclusion] The beef cattle industry in Yanbian region has obvious comparative advantages and development potential.

Variations in Reproductive Hormones during Estrus Cycle in Local Beef Cattle from Jilin of China

[ Objective] To provide a theoretical basis for improving reproductive efficiency of domestic beef cattle in Jilin of China. [ Method] China Red Steppe cattle, Yanbian yellow cattle and Simmental cattle in Jilin Province were used for detection. The levels of progesterone （P4）, estradiol （ E2 ）, follicle-stimulating hormone （FSH） and luteinizing hormone （LH） in serum and urine during estrus cycle were determined. [ Result] The levels of P4 and E2 were significantly different between pregnant cattle and non-pregnant cattle on Day 21 post estrus （ P 〈 0.01 ）. The level of LH on estrus day was significantly different from that on the other days of estrus cycle （ P 〈 0.05）. [ Conclusion] It is feasible to detect P4 level for diagnosis of estrus and eady pregnancy in beef cattle.

Determination of Breeding Target and Marginal Benefit Calculation of New Type of Shuxuan Beef Cattle

[Objectives]To make targeted breeding of new type of Shuxuan beef cattle,study and determine the breeding target traits of new type of Shuxuan beef cattle.[Methods]The difference method was used to calculate the marginal benefit of each target trait,and the economic weight of the corresponding breeding target trait was obtained.[Results]The marginal benefits of weaning weight,fattening daily gain,18-month weight,carcass quality,dressing percentage,pure meat percentage,age at first calving,calving interval and stay group time were 35.86,13.76,13.05,421.96,375.55,22.58,-4.45,-27.53,and 1555.24,respectively.The relative economic weight ratio of growth traits,carcass traits,and reproductive traits was close to 4∶1∶5.Through marginal benefit analysis,the economic benefits obtained by improving carcass quality,dressing percentage and stay group time were significantly higher than other traits.[Conclusions]It is expected to provide a theoretic basis for establishing the target trait selection indicators for the new type of Shuxuan beef cattle.

Effects of Different Wind Speeds behind Windbreak Wall of Fattening Cattle Farm on Farm Environment and Performance of Beef Cattle in Zhangye District

[Objective]The paper was to study the wind-reducing effect of windbreak wall at different sheltering distances and the effects of wind speed on cattle performance.[Method]The 40 cattle with insignificant difference in initial weight were randomly distributed in four selected stalls,and were divided into two groups according to the distance between stalls and windbreak wall to measure their daily gain.According to the actual conditions and weather conditions of fattening cattle farm,the wind speed,temperature and other environmental indexes of measuring point and heat production of beef cattle were carried out field measurement and analysis.[Result]The windbreak wall in fattening cattle farm reduced the wind speed by 40%-70%within a horizontal distance of 10 times of the wall height at a height of 1.2 m.The best sheltered area behind windbreak wall was 2-4 times of the height of windbreak wall.Within the distance of 6 times of the wall height,the wind speed reduction effect was obvious and the maximum reduction rate reached 70%.With an external WCI of-15.61 and average beef cattle weight of 480 kg,the WCI of fattening cattle farm equipped with windbreak wall reached-9.00,and the heat loss reduced by each cow was 3.31 MJ/h.Meantime,due to the difference in distance from windbreak wall,the daily gain difference of beef cattle was 0.15 kg/head day,but the difference was not significant(P>0.05).

Hejinlai Beef Cattle Processing Co.Ltd

The Hejinlai Beef Cattle ProcessingCo. Ltd is a key enterprise of theAnhui Hejinlai Beef Cattle Group, thelargest enterprise using foreign loans in LingbiCounty and also a key project of the StateCommission of Planning and the Ministry ofAgriculture. Its headquarters are situated at thefoot of Phoenix Mountain, five km northwestof Lingbi County Town. It has convenienttraffic, very near to the Lingfang Highwayand the wharf of Xinbian River, 60km to theGuanyin International Airport, 50km to theTianjin-Pukou Railway and 30km to theNo.104 State Highway. It occupies an

Zhangjiakou Beef Cattle

Zhangjiakou city is in a vast area and enjoys rich resources of grass for animals. The city has unique and favorable conditions

Feasibility of feeding cadmium accumulator maize(Zea mays L.)to beef cattle:Discovering a strategy for eliminating phytoremediation residues

Eco-friendly and efficient strategies for eliminating cadmium (Cd) phytoremediation plant residues are needed. The present study investigated the feasibility of feeding Cd accumulator maize to beef cattle. In total, 20 cattle at 6 months of age were selected and randomly allocated into two groups fed with 85.82%(fresh basis) Cd accumulator maize (CAM) or normal maize (control [Con]) silage diets for 107 d. Feeding CAM did not affect the body weight (P=0.24), while it decreased feed intake and increased feed efficiency of beef cattle (P <0.01). Feeding CAM increased serum concentrations of immunoglobulin A and G, complement 3 and 4, blood urea nitrogen, and low-density lipoprotein cholesterol, decreased serum concentrations of interleukin-6 and lipopolysaccharide (P <0.05), and caused wider lumens in the renal tubules. The Cd residue in meat was 7μg/kg beyond the restriction for human food. In the muscle, the unsaturated fatty acids (t11C18:1 and C20:4), Lys, Arg, Pro, and Cys were decreased, while the saturated fatty acids (C10:0, C12:0, and C17:0) and Leu were increased (P <0.05). Therefore, at the current feeding level, phytoremediation maize increased the feed efficiency of beef cattle, but did present risks to cattle health and production safety, and decreased the meat nutrition and flavor. Further research must be performed to determine whether a lower proper dose of phytoremediation maize and an appropriate feeding period may be possible to ensure no risk to cattle health and the supply of safe meat for humans.

Feed profile analysis of oil palm‐integrated beef cattle farming systems by metabolic energy budgeting and implications for beef production and pastoral system design

Background:Oil palm is a tropical crop with worldwide plantings approaching 20 million ha and large areas in Indonesia,Malaysia and Thailand.The plantations are readily managed as silvopastoral systems incorporating cattle grazing(Oil Palm Silvopastoral System for Cattle,OPSC)but there is a need for analytical tools and data to understand system herbage supply and feed conversion efficiency(FCE).Methods:Metabolic energy budgeting was used to estimate herbage harvested by cattle in three OPSC subsystems,9 and 12 years after oil palm establishment,and FCE of the subsystems was determined.Understorey herbage was also analysed for nutritive value,botanical composition and herbage accumulation within one grazing‐regrowth cycle.Results:The herbage‐harvested estimate was 2.0−2.4 t dry matter(DM)ha^(-1) year^(-1) for 9 year old subsystems and 1.4-1.7 tDMha^(-1) year^(-1) for a 12 year old subsystem.Herbage metabolisable energy(ME)was 8.3−8.5 MJ kg^(-1) DM and crude protein(CP)was 15%-16%DM.FCE values for subsystems ranged from 32 to 94 kg DM kg^(-1) liveweight‐gain.Conclusions:Herbage DM yield is declining,while herbage ME is marginal but CP is adequate.FCE is suboptimal but can be optimised by defining the trajectory of declining herbage production with canopy closure as plantations age and matching stocking rate to herbage supply using a comparativestocking‐rate‐type statistic.

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.

The Blue Water Footprint of Extensive Beef Production on Semi-Arid Rangeland over a Full Production Cycle in South Africa

Water plays a critical role in beef cattle production. Current methods used to estimate the blue water footprint of beef cattle are largely based on generic values that do not make provision for different production systems within different regions. Total production cycle measurements should therefore be considered to accurately assess the blue water footprint of beef cattle grazing natural rangeland. The aim of the study was to measure water intake of extensive Bonsmara cattle grazing Marikana Thornveld over a full production cycle at the ARC-Roodeplaat Research Station. Measurements commenced at weaning (June 2017) and continued until the heifers weaned their first calves at approximately 210 days of age (July 2019). Water consumption differed between 21.4 litre per animal per day when the heifers were still growing to 54.3 litres during lactation, relating to between 6.7% and 12.0% of live weight. The blue water footprint over the total production cycle was calculated to be 27,147 litres.

Identific tion of quantitative trait loci and associated candidate genes for pregnancy success in Angus–Brahman crossbred heifers

Background In beef cattle, more than 50% of the energy input to produce a unit of beef is consumed by the female that produced the calf. Development of genomic tools to identify females with high genetic merit for reproductive function could increase the profitability and sustainability of beef production.Results Genome-wide association studies(GWAS) were performed using a single-step genomic best linear unbiased prediction approach on pregnancy outcome traits from a population of Angus–Brahman crossbred heifers. Furthermore, a validation GWAS was performed using data from another farm. Heifers were genotyped with the Bovine GGP F250 array that contains 221,077 SNPs. In the discovery population, heifers were bred in winter breeding seasons involving a single round of timed artificial insemination(AI) followed by natural mating for 3 months. Two phenotypes were analyzed: pregnancy outcome to first-service AI(PAI;n = 1,481) and pregnancy status at the end of the breeding season(PEBS;n = 1,725). The heritability was estimated as 0.149 and 0.122 for PAI and PEBS, respectively. In the PAI model, one quantitative trait locus(QTL), located between 52.3 and 52.5 Mb on BTA7, explained about 3% of the genetic variation, in a region containing a cluster of γ-protocadherin genes and SLC25A2. Other QTLs explaining between 0.5% and 1% of the genetic variation were found on BTA12 and 25. In the PEBS model, a large QTL on BTA7 was synonymous with the QTL for PAI, with minor QTLs located on BTA5, 9, 10, 11, 19, and 20. The validation population for pregnancy status at the end of the breeding season were Angus–Brahman crossbred heifers bred by natural mating. In concordance with the discovery population, the large QTL on BTA7 and QTLs on BTA10 and 12 were identified.Conclusions In summary, QTLs and candidate SNPs identified were associated with pregnancy outcomes in beef heifers, including a large QTL associated with a group of protocadherin genes. Confirmation of these associations with larger populations could lead to the development of genomic predictions of reproductive function in beef cattle. Moreover, additional research is warranted to study the function of candidate genes associated with QTLs.

Expression analysis,single nucleotide polymorphisms within SIRT4 and SIRT7 genes and their association with body size and meat quality traits in Qinchuan cattle

Silent information regulator 2 （Sir2） proteins, or sirtuins, are nicotine adenine dinucleotide （NAD）-dependent deacetylases that connect metabolism with longevity in lower organisms. In mammals, there are seven Sir2 homologs, namely, silent information regulators （SIRT1-7）. SIRT4 and SIRT7 genes play a crucial role in regulating lipid metabolism, cellular growth and metabolism. This suggests that they are potential candidate genes for affecting body size and meat quality traits in animals. Hence, this study aimed to detect genetic variations of both SIRT4 and SIRT7 bovine genes in Qinchuan cattle, and to evaluate the effect of these variations on economically important body size and meat quality traits. Expression analysis using quantitative real-time PCR （qPCR） indicated that SIRT4 and SIRT7 were broadly expressed in all thirteen studied tissues. The expression of SIRT4 was higher in liver, muscle, and in subcutaneous fat tissue. In the case of SIRT7, the expression was higher in lung, abomasum, and subcutaneous fat. Using DNAsequencing, a total of three single nucleotide polymorphisms （SNPs） were identified within SIRT4 and SIRT7 genes in 468 Qinchuan cattle. These included one novel SNP within 3＇ untranslated regions （UTR） of SIRT4 （SNP1： g. 13915A〉G） and two novel synonymous substitutions in SIRT7 （SNP2： g.3587C〉T and SNP3： g.3793T〉C）. Statistical analyses indicated that all three SNPs could significantly influence some body size and meat quality traits in Qinchuan cattle. These novel findings will provide a background for application of bovine SIRT4 and SIRT7 genes in the selection program of Chinese cattle.