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.

Effects of Quebracho Tannins on Growth Performance and Blood Routine of Simmental Fattening Cattle

[Objectives]The effects of condensed quebracho tannins on the production performance and blood routine indices of Simmental fattening cattle were investigated experimentally.[Methods]Twenty four Simmental fattening cattle were selected and randomly divided into two treatment groups according to their body weight,with 12 animals in each group.The diet of the control group consisted of beef cattle concentrate supplement+silage+hay,and the diet of the experimental group consisted of beef cattle concentrate supplement+silage+hay+tannins,and the experimental period was 30 d.[Results]Compared with the control group,the addition of tannins[30 g/(cattle·d)]to the diet of beef cattle increased the daily weight gain of Simmental beef cattle by 24.68%(P<0.01),while the feed conversion ratio decreased by 2.57%(P>0.05).The gross profit per cattle increased by 973.63 yuan,and the economic benefit increased by 114.78%.Platelets were higher in the experimental group than in the control group(P<0.01);hemoglobin was lower in the experimental group than in the control group(P<0.01);leukocytes,neutrophils,monocytes and lymphocytes were lower in the experimental group than in the control group(P<0.01);and erythrocytes were lower in the experimental group than in the control group(P<0.05).[Conclusions]This study provides a theoretical basis for the rational utilization of quebracho tannins.

Effect of Fruit-flavored Agent and Green Pigment on Production Performance of Simmental Cows

[Objective] The paper was to increase utilization rate of roughage to solve current shortage of forage and improve production performance of Simmental cow.[Method] Fruit-flavored agent and green pigment were added in roughage of Simmental cow respectively,and their effects on feed intake,milk production and milk quality of Simmental cow were studied.[Result] After adding fruit-flavored agent and green pigment,the feed intakes of Simmental cow were increased by 30.69% and 12.27%,while the milk productions were increased by 1.74 and 2.25 kg,respectively,and the differences were all significant（P 〈 0.05）.[Conclusion]Adding 0.3% and 0.1% fruit-flavored agent and green pigment in roughage of Simmental cow could significantly improve feed intake and milk production,which can also delay the decline of milk production during late lactation stage and improve milk quality.

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.

Study on Reproductive Performance of Improved Hybrid from Chinese Holstein Cattle

In order to overcome the problems such as decline in adaptability, low fertility and few utilization years due to continuously increasing coefficient of inbreeding of Chinese Holstein cattle, three dairy-beef dual-purpose cattle varieties （purebred Simmental, Montbeliard and Fleckvieh） were introduced as the male parents to be hybridized with Chinese Holstein cattle, so as to study the improvement effect in the reproduction performance and milk production performance of the hybrid cattle. The results showed that the first-filial generation of Montbeliard had a very significant difference in gestation period from Chinese Holstein cattle （ P 〈0.01）. The parity of Fleckvieh s first-filial generation had a very significant effect on 305 d milk yield （ P 〈0.01）; and for the first-filial generation of Montbeliard, mating times and open days significantly affected 305 d milk yield （ P 〈0.05）, and its total milk yield had a significant difference from Chinese Holstein cattle （ P 〈0.05）. Comprehensively, the reproduction traits of Montbeliard s first-filial generation are better than other two varieties.