This paper was carried out on the morphological character of the test and epididymis of three types of yak bull age 6,12,18,24 months old (1/2 wild yak, cross 1/2 wild yak and domestic yak). The results showed that th...This paper was carried out on the morphological character of the test and epididymis of three types of yak bull age 6,12,18,24 months old (1/2 wild yak, cross 1/2 wild yak and domestic yak). The results showed that the weight and size of testes and epidiymis was increased with the age which was hardly affected by imbalance of food supply during the cold and warm seasons. The development were similar for three kinds of yak at the same age(P＞0.05).展开更多
Primers based upon the mitochondrial genome sequences of Bos taurus were used to amplify and sequence the complete mitochondrial D-loop region of Jiulong yak(Poephagus grunniens).The results showed that the length of ...Primers based upon the mitochondrial genome sequences of Bos taurus were used to amplify and sequence the complete mitochondrial D-loop region of Jiulong yak(Poephagus grunniens).The results showed that the length of D-loop was 893 bp,with 87.4%homology to the Bos taurus D-loop sequence;there were 17 bp deletion.Using Ovis aries as an outgroup,the phylogeny of representative species of Bovinae(P.grunniens,P.mutus,Bos taurus,Bos indicus,Bison bison,Bison bonasus,and Bubalus bubalis)was analyzed.Among Bovinae,the sequence divergence between P.grunniens,P.mutus and American bison(Bison bison)was 6.2%-6.8%,which was less than that of Bos taurus and Bos indicus within Bos(10.0%-11.3%).Phylogenetic analysis found that P.grunniens,P.mutus and Bison bison clustered first of all,indicating there was higher genetic comparability among them than to that of Bos.Combining data from paleontology,morphology,and molecular biology,the present analysis supports the argument that Poephagus grunniens and Poephagus mutus should be classified as a distinct genus in Bovinae,that is Poephagus.展开更多
The testicular tissue of three types of yak bull (1/2 wild yak,cross 1/2 wild yak and domestic yak) were studied quantitatively at 6,12,18 and 24 months old. The results showed that the average values changed from bre...The testicular tissue of three types of yak bull (1/2 wild yak,cross 1/2 wild yak and domestic yak) were studied quantitatively at 6,12,18 and 24 months old. The results showed that the average values changed from breed to breed at the same age. But there were no significant difference. The volume density and the height of seminiferous tubule and epithelium increased with the age and testicular weight. The capacity rate of the testicular seminiferous tubule in three types were 78.71% ,75.78% and 78.58% respectively, which nearly reached the level of mature bull.展开更多
On the Datong Yak Breeding Farm of Qinghai Province(Datong farm), the scientists of the Lanzhou Institute of Animal Science and Veterinary Pharmaceutics of Chinese Academy of Agricultural Sciences, in collaboration wi...On the Datong Yak Breeding Farm of Qinghai Province(Datong farm), the scientists of the Lanzhou Institute of Animal Science and Veterinary Pharmaceutics of Chinese Academy of Agricultural Sciences, in collaboration with others,explored the possibility to cross wild yak bulls with domestic yak cows in the past 20years and a new yak breed, the Datong yak, has been developed.展开更多
Some blood physiological indices were determined in wild yak,Datong yak(the crossbreeds of the wild and domestic yak)and Tianzhu Black yak in a year. The red blood cell amount(RBC)and packed cell volume (PCV)of the wi...Some blood physiological indices were determined in wild yak,Datong yak(the crossbreeds of the wild and domestic yak)and Tianzhu Black yak in a year. The red blood cell amount(RBC)and packed cell volume (PCV)of the wild yak and Datong yak were similar but differed largely from that of the Tianzhu Black yak. RBC of the wild yak and Datong yak were larger than that of the Tianzhu Black yak and their RBC varied seasonally.The results indicated that wild yak and Datong yak could effectively adapt to changes in environment by adjusting their physiological indices.展开更多
At present, the yak population reached to 1.1 million in Gannan prefecture. Yak is dominant livestock in Gannan,and is the main source of herdsman income. In recent years, the population of Gannan yak continuously inc...At present, the yak population reached to 1.1 million in Gannan prefecture. Yak is dominant livestock in Gannan,and is the main source of herdsman income. In recent years, the population of Gannan yak continuously increased, but the performances such as body weight, dressing percentage and reproductivity are dropping.In order to improve quality, performance and economic benefits of yak production,it is very urgent to strengthen yak selective breeding.展开更多
The observation of body height and weight of 10 captured wild yak shows the body height and weight of the wild yak at three and four months old were similar with that of domestic yak. At their 24 months old, the body ...The observation of body height and weight of 10 captured wild yak shows the body height and weight of the wild yak at three and four months old were similar with that of domestic yak. At their 24 months old, the body height and weight were higher by 26.9 % and 62.5 % than that of the domestic ones. The results indicate that, once adapted to the half-shed and half-grazing conditions, the tamed Kunlun type of wild yak with superior genetics would grow and develop faster than the domestic yak at elder ages.展开更多
This paper reports results of a study conducted to investigate the concentrations of seven mineral elements in yak blood, forage and water resources around the Qinghai Lake in Qinghai Province in different seasons. Me...This paper reports results of a study conducted to investigate the concentrations of seven mineral elements in yak blood, forage and water resources around the Qinghai Lake in Qinghai Province in different seasons. Meanwhile, the nutritional compositions of the forage were also surveyed. The results suggest that the mineral elements and the forage nutrients change in a seasonal pattern. In yak blood,the sodium(Na)concentration varies from 0.291 to 0.034 mg/mL,and this is lower than the normal value. In the forage,the ratio calcium(Ca)to phosphorus(P)is 4.06～7.47:1 and potassium(K)to Na 30～27:1. These results indicate that the nutrition of the yak in the area is deficient in Na but high in K. For the withered forage sampled in February,the protein content is only 31.14% of the total protein in the forage growing at puerile stage in June. The severe loss of protein by 68. 9% and decrease of effective nutrients in the wintered forage are considered to be the reasons resulting in the poor condition of yak in winter and spring seasons.展开更多
The ITRM of liver, one of the important indexes of tissue respiratory metabolism in yak, is higher than other tissues. The relationship of ITRM and time belongs to the equation y = aebt. The ITRM of each tissue in rec...The ITRM of liver, one of the important indexes of tissue respiratory metabolism in yak, is higher than other tissues. The relationship of ITRM and time belongs to the equation y = aebt. The ITRM of each tissue in reciprocal yaks were significant(P＜0.05) lower than that of the domestic yaks which showed that the adaptability to hypoxia of the reciprocal yaks were more powerful than the domestic yaks.展开更多
Production of hair and undercoat, type of yak hair fibre, strength, stretched length and ultrastructure of the hair fibre were determined and observed for WY, DY and its offspring in this study. The results showed tha...Production of hair and undercoat, type of yak hair fibre, strength, stretched length and ultrastructure of the hair fibre were determined and observed for WY, DY and its offspring in this study. The results showed that hair yield of the 1/2 WY raised by 19.73% and the undercoat by 14% (P＜0. 01)more than that of the DY. Its strength improved 8. 31% (P＞0.05) more than that of the DY. The stretched length and the ultrastructure of hair fibre were resemblance in the WY and DY.展开更多
Concentrations of growth hormone (GH), insulin, thyroxin(T4 ) and 3,3 ' 5 '-tri-iodothyronine (T3)in blood samples of growing yak during different seasons were determined by radio-immunoassay.Changes in bodywe...Concentrations of growth hormone (GH), insulin, thyroxin(T4 ) and 3,3 ' 5 '-tri-iodothyronine (T3)in blood samples of growing yak during different seasons were determined by radio-immunoassay.Changes in bodyweight of the growing yak and compositions of grass were also measured. The seasonal changes in hormones were significant (at least P＜0.05). In the same season, variation in hormonal concentration was affected by the growth stage of the animal. The bodyweight gains varied in different seasons, with significant increase from May to September and decrease from January to May. Correlation analysis indicated that T4 had a significant positive correlation with bodyweight of the growing yak(r= 0.323,P＜0.05) ,but other hormones did not have significant correlations with bodyweight. The results show that annual cycle of weight loss and gain is attributable to the seasonal changes in feed supply and that the seasonal changes in the concentrations of the assayed hormones were indirectly dependent on grass growth.展开更多
12 cattle microsatellite DNA markers were used for establishing the paternity of 4 Datong Yak calves.The results indicated that paternity can be assigned by use of exclusion method directely when the mother is clearly...12 cattle microsatellite DNA markers were used for establishing the paternity of 4 Datong Yak calves.The results indicated that paternity can be assigned by use of exclusion method directely when the mother is clearly known and data of all likely sires were obtained. The more the alleles of a locus possessed, the more effectively the paternity can be assigned. Not only the microsatellite DNA marker is a promising tool in establishment of yak detail pedigrees, but also can provide us information of reproductive efficiency of the bull(s) based on the numbers of calves it produced in the herd, which will be useful in speeding up the processes of yak genetics improvement.展开更多
The results of 439 times of calving interval(CI) from 161 yak cows showed that the average CI is 459(se=131)d. The CI with 3 to 6 calving numbers is 25～48 d shorter than that of 1 to 2 and above 7 calving numbers. Al...The results of 439 times of calving interval(CI) from 161 yak cows showed that the average CI is 459(se=131)d. The CI with 3 to 6 calving numbers is 25～48 d shorter than that of 1 to 2 and above 7 calving numbers. Although slaughtering a great number of calves during the late September and early October do bring about relatively higher calving rate that is mos yak cowst can give 3,4,5 and 6calves during 4,5,6 and 7 years old respectively. This makes major calving months shift from April or May to June.展开更多
Testicular tissue was studied in domesticated yak and in wild yak × domesticated yak(F1 and F2)bulls at 6,12,18 and 24 months of age by stereology for quautitative histology and by comparative studies on the lact...Testicular tissue was studied in domesticated yak and in wild yak × domesticated yak(F1 and F2)bulls at 6,12,18 and 24 months of age by stereology for quautitative histology and by comparative studies on the lactate dehydrogenase(LDH)isoenzyme spectrum, LDH activity and the percentage content of LDH isoenzymes in testes. The results indicated that all three types of yak were similar in both the characteristics of ultrastructure of testicular tissue and the degree of germ cell development. The process of spermatogenesis was initiated and sperm were produced for the first time at the age of 12months in all three yak types. All yak types exhibited similar age-related, increases in weight of testes,volume density of both the seminiferous tubules and seminiferous epithelium and height of seminiferous epithelium but all these indexes were slightly affected by season. The number of LDH isoenzyme bands after electrophoresis varied with age as follows: four bands were present at 6 months of age, five bands at 12 and 18 months and six bands at 24 months of age. The sixth band was LDH -x ,which appeared between the LDH4 and LDH5 band. These results indicated that yak bulls reach sexual maturity at 24months of age and that puberty is not affected by infusion of wild strains.展开更多
We have adopted PAGE method to isolate lactic dehydrogenase(LDH)and α-amylase(α-Am)from wild yak's serum and measure the physical-chemical properties of the two components respectively. The results showed that t...We have adopted PAGE method to isolate lactic dehydrogenase(LDH)and α-amylase(α-Am)from wild yak's serum and measure the physical-chemical properties of the two components respectively. The results showed that the yak LDH isozyme distributed into five bands. The sequence according to their activity reads as LDH1 ＞ LDH2＞ LDH3 ＞ LDH4 ＞ LDH5. The subunit B is relatively occupied a dominant position. It got a wide operating pH range, high thermal stability,well denature resistance and a fairly large adaptability threshold on the physical-chemical change of surrounding environment. α-Am isozyme distributed into seven bands and also got a wide operating pH range. α-Am isozyme is high sensitivity to environmental temperature.展开更多
To compare the quality of yak meat with that of other livestock, the growth and development of yak from birth to 48-month old were measured, slaughter tests of 6-, 24-, 48-month old were made. It can improve meat perf...To compare the quality of yak meat with that of other livestock, the growth and development of yak from birth to 48-month old were measured, slaughter tests of 6-, 24-, 48-month old were made. It can improve meat performance on yak to crossbreed with beef cattle or wild yak, to improve traditional feeding and management, etc.展开更多
Selecting 6 heads of new yak strains(the offspring of reciprocal cross of F1 produced by wild yak male mated with domestic yak female)and 6 domestic yaks at 3 and 12 age in months respectively at Datong Yak Farm of Qi...Selecting 6 heads of new yak strains(the offspring of reciprocal cross of F1 produced by wild yak male mated with domestic yak female)and 6 domestic yaks at 3 and 12 age in months respectively at Datong Yak Farm of Qinghai Province. This paper was studied for the morphological characteristics of the skin and hair coat of yak and their adaptability to the cold living environment in Qinghai-Tibetan plateau. The results indicated that it should be of vital importance marker for the morphological characteristics of the skin and hair coat with two type of yaks at 3 and 12 age in months and their regulations of growth and development to adapt to the cold living environment in Qinghai-Tibetan plateau,The main morphological indexes of the skin and hair coat of the rearing new yak strain were higher than those of the domestic yaks at the same age in months, or speak precisely, the new yak strain was more powerful adaptable to the alpine cold living environment than that of the domestic yaks. The resvlts above provided scientific basis for the native strain breeding of yak and the new yak strain rearing.展开更多
After domestication of wild yak and utilization of its frozen semen was successful in 1983, frozen semen of wild yak was used to improve domestic yak and local yellow cattle by artificial insemination(AI). Hybrid vigo...After domestication of wild yak and utilization of its frozen semen was successful in 1983, frozen semen of wild yak was used to improve domestic yak and local yellow cattle by artificial insemination(AI). Hybrid vigor of their F1 was obvious, i. e. , productive performance of F1 was significantly increased. Their offspring did not only have significant heterosis in performance but also can rejuvenate effectively their adaptability and survival, and can use alpine grassland more efficiently. This resulted in significant social and economic benefits.Compared with dairy cattle, beef cattle and yellow cattle, AI of yak was more difficult. Using AI to improve yak performance was difficult and significant in yak production areas of our country. It is necessary to invest more technique and fund to extend AI.展开更多
Since the time that yaks were domesticated, due to the special social, natural and economic conditions ,and yaks own biological and economic characteristics, the Yak Production System has been formed, which is differe...Since the time that yaks were domesticated, due to the special social, natural and economic conditions ,and yaks own biological and economic characteristics, the Yak Production System has been formed, which is different from other livestock production systems. The system has the characteristics of unique breed, herding perennially on grassland and a variety of products. It is a low-efficiency system with the low-cost,low-production,long-cycle and slowfunction. Based on the experiments and research,exercising the measure of stopping milking and mainly producing beef,it's the redisposition of resources and the combination of multi-superiority. By the scientific management, the superiority of grass growing in warm season, the dominant position of total nutrition of mother milk, the superiority of calves developing in early days and the genetic preponderance of new breeds of yak are perfectly integrated. It also got the economic, biological and ecological benefits.展开更多
文摘This paper was carried out on the morphological character of the test and epididymis of three types of yak bull age 6,12,18,24 months old (1/2 wild yak, cross 1/2 wild yak and domestic yak). The results showed that the weight and size of testes and epidiymis was increased with the age which was hardly affected by imbalance of food supply during the cold and warm seasons. The development were similar for three kinds of yak at the same age(P＞0.05).
文摘Primers based upon the mitochondrial genome sequences of Bos taurus were used to amplify and sequence the complete mitochondrial D-loop region of Jiulong yak(Poephagus grunniens).The results showed that the length of D-loop was 893 bp,with 87.4%homology to the Bos taurus D-loop sequence;there were 17 bp deletion.Using Ovis aries as an outgroup,the phylogeny of representative species of Bovinae(P.grunniens,P.mutus,Bos taurus,Bos indicus,Bison bison,Bison bonasus,and Bubalus bubalis)was analyzed.Among Bovinae,the sequence divergence between P.grunniens,P.mutus and American bison(Bison bison)was 6.2%-6.8%,which was less than that of Bos taurus and Bos indicus within Bos(10.0%-11.3%).Phylogenetic analysis found that P.grunniens,P.mutus and Bison bison clustered first of all,indicating there was higher genetic comparability among them than to that of Bos.Combining data from paleontology,morphology,and molecular biology,the present analysis supports the argument that Poephagus grunniens and Poephagus mutus should be classified as a distinct genus in Bovinae,that is Poephagus.
文摘The testicular tissue of three types of yak bull (1/2 wild yak,cross 1/2 wild yak and domestic yak) were studied quantitatively at 6,12,18 and 24 months old. The results showed that the average values changed from breed to breed at the same age. But there were no significant difference. The volume density and the height of seminiferous tubule and epithelium increased with the age and testicular weight. The capacity rate of the testicular seminiferous tubule in three types were 78.71% ,75.78% and 78.58% respectively, which nearly reached the level of mature bull.
文摘On the Datong Yak Breeding Farm of Qinghai Province(Datong farm), the scientists of the Lanzhou Institute of Animal Science and Veterinary Pharmaceutics of Chinese Academy of Agricultural Sciences, in collaboration with others,explored the possibility to cross wild yak bulls with domestic yak cows in the past 20years and a new yak breed, the Datong yak, has been developed.
文摘Some blood physiological indices were determined in wild yak,Datong yak(the crossbreeds of the wild and domestic yak)and Tianzhu Black yak in a year. The red blood cell amount(RBC)and packed cell volume (PCV)of the wild yak and Datong yak were similar but differed largely from that of the Tianzhu Black yak. RBC of the wild yak and Datong yak were larger than that of the Tianzhu Black yak and their RBC varied seasonally.The results indicated that wild yak and Datong yak could effectively adapt to changes in environment by adjusting their physiological indices.
文摘At present, the yak population reached to 1.1 million in Gannan prefecture. Yak is dominant livestock in Gannan,and is the main source of herdsman income. In recent years, the population of Gannan yak continuously increased, but the performances such as body weight, dressing percentage and reproductivity are dropping.In order to improve quality, performance and economic benefits of yak production,it is very urgent to strengthen yak selective breeding.
文摘The observation of body height and weight of 10 captured wild yak shows the body height and weight of the wild yak at three and four months old were similar with that of domestic yak. At their 24 months old, the body height and weight were higher by 26.9 % and 62.5 % than that of the domestic ones. The results indicate that, once adapted to the half-shed and half-grazing conditions, the tamed Kunlun type of wild yak with superior genetics would grow and develop faster than the domestic yak at elder ages.
文摘This paper reports results of a study conducted to investigate the concentrations of seven mineral elements in yak blood, forage and water resources around the Qinghai Lake in Qinghai Province in different seasons. Meanwhile, the nutritional compositions of the forage were also surveyed. The results suggest that the mineral elements and the forage nutrients change in a seasonal pattern. In yak blood,the sodium(Na)concentration varies from 0.291 to 0.034 mg/mL,and this is lower than the normal value. In the forage,the ratio calcium(Ca)to phosphorus(P)is 4.06～7.47:1 and potassium(K)to Na 30～27:1. These results indicate that the nutrition of the yak in the area is deficient in Na but high in K. For the withered forage sampled in February,the protein content is only 31.14% of the total protein in the forage growing at puerile stage in June. The severe loss of protein by 68. 9% and decrease of effective nutrients in the wintered forage are considered to be the reasons resulting in the poor condition of yak in winter and spring seasons.
文摘The ITRM of liver, one of the important indexes of tissue respiratory metabolism in yak, is higher than other tissues. The relationship of ITRM and time belongs to the equation y = aebt. The ITRM of each tissue in reciprocal yaks were significant(P＜0.05) lower than that of the domestic yaks which showed that the adaptability to hypoxia of the reciprocal yaks were more powerful than the domestic yaks.
文摘Production of hair and undercoat, type of yak hair fibre, strength, stretched length and ultrastructure of the hair fibre were determined and observed for WY, DY and its offspring in this study. The results showed that hair yield of the 1/2 WY raised by 19.73% and the undercoat by 14% (P＜0. 01)more than that of the DY. Its strength improved 8. 31% (P＞0.05) more than that of the DY. The stretched length and the ultrastructure of hair fibre were resemblance in the WY and DY.
文摘Concentrations of growth hormone (GH), insulin, thyroxin(T4 ) and 3,3 ' 5 '-tri-iodothyronine (T3)in blood samples of growing yak during different seasons were determined by radio-immunoassay.Changes in bodyweight of the growing yak and compositions of grass were also measured. The seasonal changes in hormones were significant (at least P＜0.05). In the same season, variation in hormonal concentration was affected by the growth stage of the animal. The bodyweight gains varied in different seasons, with significant increase from May to September and decrease from January to May. Correlation analysis indicated that T4 had a significant positive correlation with bodyweight of the growing yak(r= 0.323,P＜0.05) ,but other hormones did not have significant correlations with bodyweight. The results show that annual cycle of weight loss and gain is attributable to the seasonal changes in feed supply and that the seasonal changes in the concentrations of the assayed hormones were indirectly dependent on grass growth.
文摘12 cattle microsatellite DNA markers were used for establishing the paternity of 4 Datong Yak calves.The results indicated that paternity can be assigned by use of exclusion method directely when the mother is clearly known and data of all likely sires were obtained. The more the alleles of a locus possessed, the more effectively the paternity can be assigned. Not only the microsatellite DNA marker is a promising tool in establishment of yak detail pedigrees, but also can provide us information of reproductive efficiency of the bull(s) based on the numbers of calves it produced in the herd, which will be useful in speeding up the processes of yak genetics improvement.
文摘The results of 439 times of calving interval(CI) from 161 yak cows showed that the average CI is 459(se=131)d. The CI with 3 to 6 calving numbers is 25～48 d shorter than that of 1 to 2 and above 7 calving numbers. Although slaughtering a great number of calves during the late September and early October do bring about relatively higher calving rate that is mos yak cowst can give 3,4,5 and 6calves during 4,5,6 and 7 years old respectively. This makes major calving months shift from April or May to June.
文摘Testicular tissue was studied in domesticated yak and in wild yak × domesticated yak(F1 and F2)bulls at 6,12,18 and 24 months of age by stereology for quautitative histology and by comparative studies on the lactate dehydrogenase(LDH)isoenzyme spectrum, LDH activity and the percentage content of LDH isoenzymes in testes. The results indicated that all three types of yak were similar in both the characteristics of ultrastructure of testicular tissue and the degree of germ cell development. The process of spermatogenesis was initiated and sperm were produced for the first time at the age of 12months in all three yak types. All yak types exhibited similar age-related, increases in weight of testes,volume density of both the seminiferous tubules and seminiferous epithelium and height of seminiferous epithelium but all these indexes were slightly affected by season. The number of LDH isoenzyme bands after electrophoresis varied with age as follows: four bands were present at 6 months of age, five bands at 12 and 18 months and six bands at 24 months of age. The sixth band was LDH -x ,which appeared between the LDH4 and LDH5 band. These results indicated that yak bulls reach sexual maturity at 24months of age and that puberty is not affected by infusion of wild strains.
文摘We have adopted PAGE method to isolate lactic dehydrogenase(LDH)and α-amylase(α-Am)from wild yak's serum and measure the physical-chemical properties of the two components respectively. The results showed that the yak LDH isozyme distributed into five bands. The sequence according to their activity reads as LDH1 ＞ LDH2＞ LDH3 ＞ LDH4 ＞ LDH5. The subunit B is relatively occupied a dominant position. It got a wide operating pH range, high thermal stability,well denature resistance and a fairly large adaptability threshold on the physical-chemical change of surrounding environment. α-Am isozyme distributed into seven bands and also got a wide operating pH range. α-Am isozyme is high sensitivity to environmental temperature.
文摘To compare the quality of yak meat with that of other livestock, the growth and development of yak from birth to 48-month old were measured, slaughter tests of 6-, 24-, 48-month old were made. It can improve meat performance on yak to crossbreed with beef cattle or wild yak, to improve traditional feeding and management, etc.
文摘Selecting 6 heads of new yak strains(the offspring of reciprocal cross of F1 produced by wild yak male mated with domestic yak female)and 6 domestic yaks at 3 and 12 age in months respectively at Datong Yak Farm of Qinghai Province. This paper was studied for the morphological characteristics of the skin and hair coat of yak and their adaptability to the cold living environment in Qinghai-Tibetan plateau. The results indicated that it should be of vital importance marker for the morphological characteristics of the skin and hair coat with two type of yaks at 3 and 12 age in months and their regulations of growth and development to adapt to the cold living environment in Qinghai-Tibetan plateau,The main morphological indexes of the skin and hair coat of the rearing new yak strain were higher than those of the domestic yaks at the same age in months, or speak precisely, the new yak strain was more powerful adaptable to the alpine cold living environment than that of the domestic yaks. The resvlts above provided scientific basis for the native strain breeding of yak and the new yak strain rearing.
文摘After domestication of wild yak and utilization of its frozen semen was successful in 1983, frozen semen of wild yak was used to improve domestic yak and local yellow cattle by artificial insemination(AI). Hybrid vigor of their F1 was obvious, i. e. , productive performance of F1 was significantly increased. Their offspring did not only have significant heterosis in performance but also can rejuvenate effectively their adaptability and survival, and can use alpine grassland more efficiently. This resulted in significant social and economic benefits.Compared with dairy cattle, beef cattle and yellow cattle, AI of yak was more difficult. Using AI to improve yak performance was difficult and significant in yak production areas of our country. It is necessary to invest more technique and fund to extend AI.
文摘Since the time that yaks were domesticated, due to the special social, natural and economic conditions ,and yaks own biological and economic characteristics, the Yak Production System has been formed, which is different from other livestock production systems. The system has the characteristics of unique breed, herding perennially on grassland and a variety of products. It is a low-efficiency system with the low-cost,low-production,long-cycle and slowfunction. Based on the experiments and research,exercising the measure of stopping milking and mainly producing beef,it's the redisposition of resources and the combination of multi-superiority. By the scientific management, the superiority of grass growing in warm season, the dominant position of total nutrition of mother milk, the superiority of calves developing in early days and the genetic preponderance of new breeds of yak are perfectly integrated. It also got the economic, biological and ecological benefits.
