Cattle Breeding

The Ural catchment is rich in natural resources. The Sarmat tribes were already associated with husbandry and cattle breeding and they developed copper mines and melted iron ore. For thousands of years, various caravans passed through the Ural area. In 1640, at the mouth of the Ural, the town Guriev was founded as a commercial fishery. During that period dense forests fringed the rivers. In 1734 the Verhneuralsky pier was constructed in the upper Ural, from which boats and timber were floated downstream to Orenburg. Clear cutting and timber floating changed the morphology of the river. Further development of the Ural catchment was linked to rapid human occupation. Forest clear-cutting, claiming of land, and irrigation have modified the hydrological regime of the river. As a consequence, the Ural River bed started to gradually aggrade.

In the 20th century the construction of artificial water bodies and abstraction of water for industrial and public demands modified the seasonal flow regime. Today, seven reservoirs exist in the Ural catchment. Along the main Ural are the reservoirs Verhneuralskoe, Magnitogorskoe and Iriklinsky. The Aktyubinskoe reservoir is on the Ilek, the Verhne–Kumakskoe along the Bolshoy Kumak, the Kargalinskoye at Djaksy along the Kargala, and the Chernovskoye is on the Chernaya River. Water abstraction and surface retention lead to a 1.2–1.3 km3 reduction in the total annual flow. During dry years, annual flow reduction can be up to 2.2 km3 and, except during the spring flood, little water reaches the Caspian Sea during a dry year.

The Ural increasingly suffers from heavy pollution (in particular the Ilek), from siltation in the delta, and from water abstraction for industry and agriculture. Important industries include blackening and colours metallurgy, mining (leading to high metal concentrations of Fe, Cu and Zn), natural gas exploitation, large-scale crop production, and livestock-breeding. Large collective farming operations have historically contributed substantial loads of fertilizers and pesticides to the Ural. However, the near-natural flow regime in the middle and lower river limits human exploitation of vast floodplains, thereby creating landscapes of high conservation value. The floodplains along the lower river in Kazakhstan, as well as the northern shore areas of the Caspian Sea, have already been declared as protected zones.

Embryo Transfer
The feasibility of embryo transfer was demonstrated in 1890 in rabbits, but application to cattle breeding came much later, with the first calf born in 1951. In the 1960s and 1970s, nonsurgical methods were introduced for recovery and transfer of uterine-stage embryos, and cryopreservation of embryos followed soon after. Better understanding of follicular dynamics in cattle (1980s) permitted refinement of ovarian superstimulation programs.

In its simplest form, embryo transfer depends on induction of multiple ovulations by providing sufficient exogenous FSH to rescue subordinate follicles in a follicular cohort from atresia. Multiple follicles become functionally dominant and ovulate. The donor cow is then inseminated and fertilized embryos recovered from the uterus at 6 or 7 days after estrus. (In cattle, the zygote completes tubal transit in about 4 days.) These embryos are identified under a stereoscopic microscope, evaluated based on stage of development and morphology, and transferred to synchronous recipients.

At first, embryo transfer was simply used to multiply offspring from genetically valuable females. In dairy cattle, systematic use of ovarian superstimulation and embryo transfer in multiple ovulation and embryo transfer (MOET) herds also allowed generation of large full-sib or half-sib cohorts from young donors, permitting genetic evaluation of sisters rather than daughters of potential AI sires, thus generating reliable breeding values in much less time. This formed the basis of more rapid genetic progress and shorter generation intervals. Mastery of embryo transfer techniques is also important for establishing pregnancies in recipients using embryos created by in vitro embryo production methods or by cloning (somatic cell nuclear transfer).

There is some risk of disease transmission involving embryos, but health standards and embryo-handling procedures have been developed to allow safe commerce in embryos, domestically and internationally. Indeed, embryos can be transported internationally with less risk of disease or injury than transport of mature animals, and much more cheaply. Additionally, resulting calves are born to (recipient) dams with native immunity appropriate for their location and prosper more readily than adult animals translocated to a new environment. There is, however, an obvious imperative to ensure that recipient females are screened for, and clear of, vertically transmissible infectious diseases both at the time of transfer and throughout pregnancy. Biosecurity programs for recipient herds become just as important as the status of the genetically superior donor animals for all forms of assisted reproduction.

Embryo transfer has also been used to increase reproductive performance in some circumstances. For example, high-producing mature cows tend to have lower pregnancy rates when inseminated than when receiving donated embryos, suggesting that their own oocyte quality is reduced. This is especially marked during periods of heat stress, when use of donated embryos can reduce the detrimental impact of heat stress on normal fertility.

In vitro techniques can also be applied to oocytes recovered as part of a terminal procedure from donors with catastrophic injury or acute terminal illness. The number of viable oocytes may be increased if there is time for superstimulation, although ethical concerns must be addressed before undertaking exogenous hormone administration because of the added time delay. In the event of illness being the causative reason rather than catastrophic injury, there will most likely be a negative impact on oocyte viability and subsequent pregnancy numbers. Fever and conditions that give rise to severe systemic inflammation, as well as neoplasia (especially multicentric lymphosarcoma), appear to be associated with very poor results when terminal oocyte harvest is attempted.