With the rapid development of the domestic dairy industry, the number of imported cows is increasing. The breeding problems faced by these imported dairy cows are not only related to the individual production capacity of dairy cows, but also related to the genetic quality of their offspring, which has become one of the key factors affecting the overall economic benefits of the cattle. This article describes how to choose imported frozen semen from imported dairy farms and some problems in its use. It is hoped that the managers and technicians in the production line can have certain value.
1. Formulation of liquid nitrogen container matching plan
The matching program is at the heart of the entire herd breeding. The choice of semen must be based on the selection plan. With the acceleration of the global breeding process, people no longer only consider production traits, and the assessment of body appearance, combining ability, herd life, and somatic traits has been added to the work schedule. More experts recommend using bull records from different countries to rate bulls; this enhances the scientific nature of the work. In order to avoid the problem of inbreeding of cows around the world, increase the excellent genes of the herd and maintain its diversity, the following factors are worth considering for domestically produced dairy farms:
1.1 Selection criteria For dairy cows imported from different regions, the exporting countries have different emphasis in the breeding process. According to statistics from the Ministry of Agriculture, cows imported from China are mainly based in the United States, Canada, Australia and New Zealand. The selection of Canadian dairy cows, while paying attention to production performance, strives to perfect the body shape. The selection of American dairy cows highlights the production capacity and does not demand perfection. The selection criteria of the two have their own advantages, although the body shape is closely related to the production performance. However, the strict requirements on the body shape will make the individuals with high productivity not get the attention they deserve; and the pursuit of high productivity and relaxation The size requirements may affect the uniformity of the herd and the overall productivity, and may result in undifferentiated differentiation. In addition, for individuals, males should be complementary in size and individual size.
1.2 The selection of individuals in the original exporting country refers to the system spectrum, and selects the ideal individual among the qualified bulls. Avoid the occurrence of inbreeding, avoid excessive mating between individuals, and reduce possible harmful mutations or mutations. According to the performance of the individual's domestic production capacity, make corresponding adjustments. Considering the appearance and production capacity of the offspring, considering the physiological conditions of the individual, the organic combination of the two will maximize the benefits.
1.3 The actual situation of the pastures The development of a reasonable matching plan should consider the geographical location of the pasture, the climate, and the production capacity of the dairy cows in the region. In the hot and rainy areas of the South, the individual yield is relatively low, and the milk fat rate may become the main target for selection. The dry area in the north is an ideal place for dairy cows to grow, and it can provide comprehensive and high requirements for various production and body size indicators. However, do not pursue a production model that is too idealistic. The selection plan should be formulated with both long-term and short-term benefits in mind.
2. Selection of imported semen from liquid nitrogen container
The latest and recent years of North American dairy cows' annual identification results and domestic import standards, combined with their pedigree selection of bulls. In 1983, the International Organization for Standardization (ISO) issued the International Standard for Animal Artificial Insemination - Bulls Frozen Semen. The standard states that a bull must be a purebred species registered by the Livestock Breeding Association (Live Breeding Agency) or other competent authority. In special cases, hybrid bull semen can also be sold according to the requirements of the importing country, but the identification of the family and descendants of the bulls must be clear. In addition, the pedigree must be reliable and must be confirmed by blood group analysis. It also requires specific infectious diseases that are not regulated by the exporting country. In fact, the international trade in cattle frozen semen is subject to bilateral quarantine provisions in addition to supervision and inspection in accordance with international standards. Questions to be aware of:
2.1 The genetic quality of semen should consider three aspects: 1 bull productivity; 2 herd production performance heritability; 3 bulls combined with other cows. This should be assessed on the basis of information provided by the exporting country.
2.2 The quality of imported semen 1 meets the conventional national standards (exporting countries and Chinese standards). In exporting countries, the semen rate should not be less than 60%. Each dose of semen contains at least 10 million live spermatozoa, of which 30% of the sperms are in direct advancement. In fact, the international trade in cattle frozen semen is subject to bilateral quarantine provisions in addition to supervision and inspection in accordance with international standards. China's national standards stipulate that the sperm activity after thawing is ≥30%, the abnormal sperm rate is ≤20%, the acrosome complete sperm rate is 40%, and the bacterial flora per dose is ≤1000. Detailed tests include the activity of frozen sperm, viability, percentage of grade A sperm, percentage of grade B sperm, percentage of grade C sperm, percentage of grade D sperm, curve velocity, linear velocity, average movement angle, average path velocity, yaw amplitude, 15 indicators such as whipping frequency, swinging, linearity and forward direction can be tested according to their own requirements. 2 No specific diseases. These diseases include vesicular stomatitis, viral diarrhea/mucosal disease, deer epidemic hemorrhagic disease, bovine nodular rash, bovine spongiform encephalopathy and recessive lethal genes, and detailed quarantine methods for various diseases. Animals raised in artificial insemination centers shall not be infected with foot-and-mouth disease, tuberculosis, paratuberculosis, brucellosis, trichomoniasis, vibriosis, leptospirosis, leukemia, infectious vaginitis, viral rhinotracheitis or insemination Other diseases that are spread by semen during the period. 3 Pay attention to the collection of its use, and investigate the effect of its use through certain methods. For example, the proportion of males and females in their descendants is a problem that seriously affects the efficiency of cattle farms. Exceeding the normal sex ratio is a bad news for non-breeding farms. Through this kind of investigation, you can get first-hand information to adjust the matching plan.
3. Approval of the import procedure for liquid nitrogen containers and formulation of procurement plans
3.1 Approval of import procedures The importation plan must first be reported to the provincial animal husbandry administrative department for approval, and then approved by the Ministry of Agriculture, the Ministry of Foreign Trade may review the import.
3.2 Procurement plan development Under normal circumstances, the procurement of frozen semen should take into account short-term demand, long-term reserves and production turnover. The demand is calculated based on the number of basic cows in the pasture. At the same time, large-scale pastures should take into account special circumstances, such as trade freezes, special diseases, etc., and the necessary purchases within the scope of the planned funds.
4. Transportation and storage of liquid nitrogen container semen
4.1 Transportation common sense Storage equipment for imported frozen semen Liquid nitrogen tanks are generally supplied by the exporting country. During the transportation process, the amount of liquid nitrogen in the tank should be checked, not less than one third of the total capacity. In addition, care should be taken to protect the outer casing of the liquid nitrogen tank from mechanical pressure and impact. Also prevent the liquid nitrogen tank from tilting. Care should be taken to protect the markings on the bucket when adding liquid nitrogen or inspection to avoid confusion. It is best to have a special person to take charge of the transportation process.
4.2 Storage Precautions First, the liquid nitrogen tank used must not have quality problems. For example, if the service life is exceeded, the domestically produced liquid nitrogen tanks generally have a service life of 5 years, and domestic production generally has no life prediction. It is best not to use for years beyond. At the same time, attention should be paid to the occurrence of special conditions, such as corrosion of the inner tank and reduction of the vacuum. The inner tank made of special aluminum alloy is easily corroded due to low purity of liquid nitrogen and impurities. Therefore, when selecting liquid nitrogen, liquid nitrogen with a purity of 99.8% should be selected, and industrial waste liquid nitrogen should not be used. Then, the inner tank is cleaned once a year to eliminate the accumulation of moisture and dirt. During the storage process, the administrator should pay attention to the condensation on the outside of the container, or freeze into a white state, which is usually a poor vacuum performance. If the container is subjected to technical testing, there is an increase in liquid nitrogen consumption, which is a symbol of deterioration of the degree of vacuum. The maintenance measures should be vacuum evacuation to ensure that the frozen semen is well preserved.
5, the performance of the production performance of the descendants of liquid nitrogen containers
Getting a descendant with excellent performance is a common goal pursued by all dairy reformers and ranchers. It is closely related to the economic benefits of dairy production. The excellent descendant cows can produce large quantities of high quality milk for direct sale every day. The individual itself has a high market price and can further improve this excellent production performance. Inherited to future generations.
Accurate determination of the performance of the descendants requires a comprehensive record of the offspring. Such as the bull's daughter's cattle number, date of birth, father number, mother number, coat color, birth weight, dystocia and genetic diseases. Then, the body size and body weight of the 2, 6, 9, 12, 15 and 18 months old and the first child of the bull were measured. After the test of the bull's daughter, the calving date, the father's number, the first lactation's lactation rate, the milk fat percentage, and the appearance score were recorded. At the same time, the cattle number, calving date, parent number and first lactation monthly milk production and milk fat percentage of other bulls of the same age were recorded as reference group. After the results are determined according to the above method, the excellent imported bull frozen semen can be selected.
In short, the selection and use of frozen liquid semen from imported liquid nitrogen container is affected and restricted by multiple factors. We should have a cautious and scientific attitude on this issue, which will bring considerable profits to the whole production.
Antimicrobial Central Venous Catheter
Central Venous Catheter,CVC,central venous catheter set,central venous catheter double lumen,central venous catheter kit
Anesthesia Medical Co., Ltd. , https://www.jssinoanesthesias.com