Cattle Breeding

30/08/2022

Crossbreeding for more profit with tropically adapted Bos ta**us
The Northern Territory Department of Primary Industry and Fisheries (DPIF) is researching whether crossbreeding with Senepol bulls is a viable way for north Australian cattle producers with Brahman herds to produce animals that will perform well under harsh northern conditions and be suited to the South East Asian live export market and the Australian domestic market. In this webinar Tim Schatz, Principal Pastoral Production Officer (DPIF), discusses the results of the research program to date and compares the:
pre and post weaning growth of Brahmans and F1 Senepol x Brahmans in the Top End of the Northern Territory
performance of the Brahman and F1 Senepol x Brahman steers in feedlots in Queensland and Indonesia
results of meat quality testing from Brahman and F1 Senepol x Brahman steers.

30/08/2022

Performance testing
Performance test is a measure of the phenotypic value of the individual candidates for selection. Since the phenotypic value is determined by both genetic and environmental influences, the performance test is an estimate, not a measure of the genetic value. The occurrence of this estimate depends upon the heritability of the trait i.e. on the degree to which the genetic value is modified by the environmental influences.
Advantages
Among simple procedures, the performance test is the most accurate.
Environmental influences can be minimised by testing candidates for selection in the same pen or in similar environmental conditions.
The measure is direct, not on a relative basis.
All candidates for selection can be tested in contrast to progeny testing where only a parent can be tested.
Generation intervals are usually short.
Testing can usually be done on the farm under normal management conditions.
Disadvantages
Accuracy become low when heretability is low.
Phenotypes are not available for one s*xor in s*x limited traits such as milk yield.
Traits which are not expressed until maturity may become expensive or difficult to manage by performance tests since most selection decisions must be made before maturity.
Performance tests should be the backbone of most selection programmes. Although much publicity has been given to other selection methods, it remains a fact that most of the progress in livestock improvement to date has been due to selection on the individual's own phenotype i.e. performance test.
B. Pedegree selection
A pedegree is a record of an individual's ancestors including its parents. This information is valuable because each individual possesses a sample half of the genes from each parent. If we can precisely know an individual's phenotype, little is gained by considering pedegree in selection. Pedegree considerations are useful when we do not have sufficient accurate records of production of the individual. Also, it is useful in the early selection when the traits in question might not have expressed themselves. It is also useful for selection of males when the traits selected for are expressed only by the female such as milk production in dairy cattle.
Advantages
It provides information when performance tests are not available for the candidates.
It provides information to supplement performance test information.
It allows selection to be completed at a young age. Pedegree records may be used to select animals for performance or progeny testing in multi-stage selection scheme.
It allows selection of bulls can be selected on the milk records of their female relatives.
Disadvantages
Accuracy, relative to alternative selection procedures is usually low.
Too much emphasis on relatives, especially remote relatives, greatly reduces genetic progress.
Progeny of favoured parents are often environmentally favoured.
Relatives often make records under quite different environments, thus introducing non random bases into the selection system.
C. Progeny testing
In this method we evaluate the breeding value by a study of the expression of the trait in its offsprings. Individuality tells us what an animal seems to be, his pedegree tells us what he ought to be, but the performance of his progeny tells us what he is.
Progency testing is, of course, a two-stage selection system because some preliminary selection determines which animals first produce progeny followed by further culling of these which produce poor progeny.
Advantages of progney testing
a. High accuracy when many progeny are obtained.
Disadvantages progney testing
a. Long generation interval.
b. Requires high reproductive rate.
c. Low selection intensity.
D. Show ring selection
Selection on the basis of show ring performance has had considerable value in the past. Essentially this selection has been directed towards bringing the conformation of the animal to some ideal conformation.
This improvement has been based on two goals:
(i) improvement conformation, and
(ii) correlated response.
Improvement of conformation has economic value because a part of the sale price is determined by the conformation of the individual. The ideal type was chosen so that, in the opinion of the judges, the animal possessing this conformation was most likely to be a profitable producer. In other words, the judges were attempting to stress traits of conformation which are corrected with productive ability.
With the advent of record keeping it was found that direct selection for performance traits resulted in much faster progress than selection through correlated conformation traits. Also, when subjected to intensive study, many of the correlations between performance and show ring were found to be of non-genetic origin.
If the correlations are of genetic origin, direct selection for performance should improve conformation as well as the reverse situation. The show ring has been a good forum for discussion of what constitutes ideal type and good management and has produced dramatic changes in the conformation of some species.
This has resulted primarily from education of the breeders, however, for most animals which are presented in the ring are good and selection differential among these animals is usually so small as to produce little change.
Advantages of show ring selection
1. It enables breeders to exchange ideas and experience.
2. It allows comparisons among superior animals both within and between breeds.
3. It allows new breeders to make contact with established breeders.
Disadvantages of show ring selection
1. Emphasis is usually placed on traits of little economic importance.
2. Clever fitting and showmanship can mask defects of various kinds.
3. Differences between exhibited animals are usually small.
4. Conformation and production traits usually have low genetic correlations.

30/08/2022

Some of the management suggestions which will tend to improve breeding efficiency of cattle are listed below.
Keep accurate breeding records of dates of heat, service and parturition. Use records in predicting the dates of heat and observe the females carefully for heat.
Breed cows during near the end of mid heat or heat period.
Have females with abnormal discharges examined and treated by veterinarian.
Call a veterinarian to examine females not settled after three services.
Get the females checked for pregnancy at 45 days to 60 days after breeding.
Buy replacements only from healthy herds and test them before putting them in your herd.
Have the females give birth in isolation, preferably in a parturition room and clean up and sterilize the area once parturition is over.
Follow a programme of disease prevention, test and vaccination for diseases affecting reproduction and vaccinate the animals against such diseases.
Practice a general sanitation programme.
Supply adequate nutrition.
Employ the correct technique.
Provide suitable shelter management.
Detect silent or weak heat, by using a teaser bull.

30/08/2022

The factors which influence the breeding efficiency of cattle are as follows:
1. Number of ova
The first limitation on the breeding efficiency of fertility of an animal is the number of functional ova released during each cycle of ovulation. Ovulation is the process of shedding of o**m from the Graffian follicle. In the case of cow, usually a single o**m is capable of undergoing fertilization only for a period of 5-10 hours. Therefore, the time of mating insemination in relation to ovulation is important for effective fertilization.
2. Percentage of fertilization
The second limitation is fertilization of ova. Failure to be fertilized may result from several causes. The s***matozoa may be few or low in vitality. The service may be either too early or too late. so that the s***ms and eggs do not meet at the right moment, to result in fertilization.
3. Embryonic death
From the time of fertilization till birth, embryonic mortality may occur due to a variety of reasons. Hormone deficiency or imbalance may cause failure of implantation of fertilized ova which die subsequently. Death may occur as a result of lethal genes for which the embryos are homozygous. Other causes may be accidents in development, over-crowding in the uterus, insufficient nutrition or infections in tile uterus.
4. Age of first pregnancy
Breeding efficiency may be lowered seriously by increasing the age of first breeding. Females bred at a lower age are likely to appear stunted during the first lactation, but their mature size is affected little by their having been bred early.
5. Frequency of pregnancy
The breeding efficiency can be greatly enhanced by lowering the interval between successive pregnancies. The wise general policy is to breed for the first time at an early age and to rebreed at almost the earliest opportunity after each pregnancy. In this way the lifetime efficiency is increased. Cows can be rebred in 9-12 weeks after parturition.
6. Longevity
The length of life of the parent is an important part of breeding efficiency, because the return over feed cost is greater in increased length of life. Also, it affects the possibility of improving the breed. The longer the life of the parents, the smaller the percentage of cows needed for replacement every year.

30/08/2022

Reproduction is an important consideration in the economics of cattle production. In the absence of regular breeding and calving at the appropriate time, cattle rearing will not be profitable. A healthy calf each year is the usual goal. This is possible only by increasing the reproductive efficiency of the animals.
Successful reproduction encompasses the ability to mate, the capacity to conceive and to nourish the embryo and deliver the viable young ones at the end of a normal gestation period. In fact, interruption in this chain of events leads to failure of the cow either to conceive or the embryo to die or to have a premature delivery of the foetus.
The reproductive efficiency is a complex phenomenon controlled by both genetic and non-genetic factors, the non- genetic factors being climate, nutrition, and level of management. The reproductive efficiency varies not only between species and breeds but also among the animals within the same breed. Even the best feeding and management can not coax performance beyond the genetic limit of an inferior animal. Improving the genetic merits of livestock populations is important at all levels of management. A sound breeding programme is a necessary part of the total animal production system.

03/02/2022

25/11/2021

25/11/2021

Use of Sex-Sorted S***m
Production of offspring of the desired s*x using s*x-sorted semen has become an established reliable technique in the dairy cattle breeding industry over the last two decades, where the major application is use of X-sorted semen on virgin heifers selected to produce the next generation of replacement animals. Although evolution of the technology has resulted in improved success, pregnancy rates are still somewhat lower than those achieved with conventional semen. Some of the reduction in pregnancy rate may be due to the lower concentration of s***m per dose (typically 2–4 million vs. 15–20 million in conventional, unsorted, semen straws). In superovulated cows, the use of s*x-sorted semen results in impaired fertilization rates and compromised yields of transferable embryos. Reduced fertilization with s*x-sorted semen may be due to low doses of s***m, an abnormal uterine environment due to supraphysiological concentrations of progesterone or atypical s***m transport in superovulated cows, damage to s***m during s*x sorting, or some combination of these factors. Thus, more research is required to optimize the yield of transferable embryos from s*x-sorted semen in superovulated donors.

25/11/2021

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.

25/11/2021

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.

25/11/2021

Spread Between Countries (Breach of Biosecurity)
A quantitative risk assessment model to determine the annual risk of importing brucellosis-infected breeding cattle into Great Britain from Northern Ireland and the Republic of Ireland, which are not brucellosis free, was developed. Predictions estimated that brucellosis could be imported from Northern Ireland every 2.63 years and from the Republic of Ireland every 3.23 years. Following this assessment, the Department of Environment, Food, and Rural Affairs introduced postcalving testing for all imported breeding cattle. Under this system, all imported animals are issued a passport that records their age and pregnancy status. This information enables identification of animals that require testing and provides an additional safeguard in maintaining official brucellosis status.

25/11/2021

This article is written on the premise that selection decisions in dairy cattle breeding should improve net returns across the lifetime of the dairy cow. Selection to improve a single trait will not accomplish this objective, although some traits will advance the effort more than others. At a minimum, production, longevity, fertility, and health traits contribute to the lifetime economic merit of commercial dairy cows. A properly weighted combination of these and other traits of economic importance that maximizes economic gain should guide selection decisions. Dr. LN Hazel of Iowa State University, in a landmark paper published in 1943, proposed a method to accomplish this task. His approach required that breeders define a selection objective or ‘aggregate genotype’ that was to be improved through selection on traits for which performance information was available.

The aggregate genotype or breeding objective, then, is the target gene complex to be improved through selection. As traits in that complex can be expected to have different relative values, the Hazel approach combines important traits using the relative economic values of each trait. The selection index used to improve the aggregate genotype consists of phenotypic or genetic information on traits that are part of or genetically correlated with traits in the aggregate genotype. Choices of traits to include in the index are based on availability of phenotypes, costs of collecting data, genetic correlations between traits, age of expression, and so on. Genetic correlations between traits in the index and the aggregate genotype are combined with economic values to determine a final set of selection index weights. These weights are applied to genetic evaluations of the different traits on individual animals to create a single number or ‘selection index’ that is used to rank animals for selection. A straightforward explanation of this process is provided in Chapter 14 of Understanding Animal Breeding (see Further Reading).

Dr. Hazel’s approach has guided the development of many useful selection indexes, but implementation of the procedure involves some challenges. One of the major difficulties is to define the appropriate aggregate genotype. That genotype will not be the same for all breeders, particularly when marketing conditions change. One aggregate genotype may not be appropriate for all environments under which animals perform. Another problem is determining the economic values of traits in that genotype at the time when offspring produced would generate income. Genetic correlations between various traits are required. Genetic correlations have been challenging to estimate and tend to change between pairs of traits as gene frequencies change. Finally, the economic values need to be linear – perhaps ‘constant’ is the more descriptive term – across the range of genetic values for traits in the breeding objective. Despite limitations, selection indexes created with reasonably strict adherence to theoretical requirements have been very successful in improving the economic utility of many livestock species including dairy cattle.

25/11/2021

Now that cryopreservation of s***m is an accepted adjunct for cattle breeding, methods adapted for human s***m have overcome certain instances of infertility (Ravina and Schneider, 1974; Barkay et al., 1974; Silben, 1972), and other medical applications of cryopreservation are under consideration. Techniques for storage of hemopoietic stem cells of the mouse at −196°C (Leibo et al., 1970), and other studies with marrow have established the background for the autologous reconstitution of human hemopoiesis (Kurnick and Montano, 1958; Adamson and Storb, 1972; Thomas and Ferrebee, 1962; Malinin et al., 1970; Lewis, 1974). Stored cells from dog blood have been shown to retain most of their ability to form agar colonies in vitro and to repopulate the marrow and lymph nodes (Fliedner et al., 1973; Debelak-Fehir et al., 1975). Considerable data are now available about protective additives and optimal rates of freezing and thawing, which must be tailored to the cell type. Of interest for allogeneic hemopoietic transplantation is the finding that the number of immunocompetent cells might be selectively reduced by appropriate techniques (Mazur and Leibo, 1973; Farrant et al., 1972). In two reported patients who had failure of lymphopoietic restoration after otherwise successful marrow repopulation from preserved cells, it seems likely, however, that the explanation was a deficiency of donor marrow lymphoid cells capable of proliferation, rather than an effect of the method of cryopreservation (Buckner et al., 1975).

Although from physical principles and studies of other kinds of cells no loss of viability is expected during storage at −196°C other than the freeze-thaw losses (Clark and Klein, 1966; Stulberg et al., 1962; Kite, 1962), cryopreserved marrow aspirated from 15 leukemic children in remission (Ragab et al., 1974) was reported to have a statistically significant drop in viability with storage for 8 weeks. We are not convinced that the reported deterioration with storage will be confirmed: the CFU-c assays in those marrow aspirates were lower than for normal children, perhaps because of previous chemotherapy, and the early freeze-thaw losses were unusually variable and often large. Some of the variability was attributed to differences in colony-stimulating activity in the assays. In contrast, with another method the short-term preservation of CFU-c from normal human blood and marrow have recently been reported to yield better than 96% survival, including freeze-thaw losses (Debelak-Fehir et al., 1975).

Certainly, a pilot project to evaluate the feasibility of banking precursor cells would call for continuing evaluation to confirm the postulated reliability of long-term preservation. It would also require an assay method that would be reproducible over many years and be relevant to the intended use of the cryopreserved cells.

25/11/2021

The use of antimicrobials is frequent in cattle breeding, mainly for the prevention and treatment of respiratory diseases, which can lead to the early cattle mortality. As a result, genes resistant to several compounds are frequently detected, i.e., bla genes (e.g., blaCTX-M, tet, cfr). These ARGs are often related to antimicrobials used in the production of beef cattle. Similarly, birds are considered the main reservoirs and carriers of several ARGs-carrying bacteria (e.g., blaCTM-X, bla-SHV, blaTEM) related to antimicrobials routinely administered in poultry. E. coli, for example, is one of the most widespread microorganisms in broiler chickens and is described as the bacterium that most hosts resistance genes. Birds are also major carriers of human resistant Salmonella spp., which presents a high frequency of zoonotic transmission.

In turn, pork is the most consumed type of meat worldwide. Thus, to meet market demands, the use of antimicrobials such as AGPs and those used for prophylactic and therapeutic purposes is common in this production system. However, this has been described as responsible for the emergence of ARGs such as mcr-1, often found in pigs and directly associated to mcr-1 identified in humans.

Fish production is one of the fastest growing production activities worldwide, mainly as fish is a lower cost protein source when compared to other types of meat. As a result, the use of antimicrobials and, consequently, ARGs emergence, has increased. In addition to the routine use of antimicrobials, several aquatic organism production systems are integrated with swine and poultry production activities, which intensifies the ARGs problem in fish.

Milk is an important source of nutrients for humans from childhood to adulthood, essential for proper organism development and, therefore, one of the most consumed animal products worldwide. Various dairy products can be produced from this matrix, such as cheese and yogurt, among others. Thus, the indiscriminate use of antimicrobials in dairy production leads to the emergence of bacterial genes resistant to these substances that can affect not only milk, but the entire dairy industry. As a result, bacteria with ARGs are transferred by milk and perpetuated and disseminated through its derivatives, increasing the chances of consumers acquiring such resistance strains, culminating in severe public health problems.

Another important animal derivative are eggs. As observed in meat and milk production, antimicrobials are administered to laying hens in order to enhance production. Therefore, eggs can also carry bacteria with resistance genes due to the indiscriminate use of these compounds, becoming an important source of resistant bacteria to humans, as they are one of the most consumed animal products worldwide.

In this review, some of the main matrices and their importance in the propagation of bacterial resistance genes through the food chain were addressed. It is clear that products of animal origin play an essential role in the transmission of resistance genes to humans, mainly due to the inappropriate use of antimicrobials in livestock and aquaculture. This is alarming, considering that this problem affects not only animals but also humans. In addition, the consumption of rare and raw meat in different populations contributes to the spread of bacteria with ARGs present in these foods. Thus, it is important to search for alternatives to further reduce antimicrobial use in animal production, in addition to raising population awareness concerning the risks of eating uncooked food.

25/11/2021

Optimal selection decisions in dairy cattle breeding should be determined by genetic and economic factors that affect net returns across the lifetime of the dairy cow. At a minimum, production, fertility and health traits are involved. The combination of those traits that maximizes economic gain from selection should guide selection decisions. Dr L. N. Hazel of Iowa State University, in a landmark paper published in 1943, proposed a method to accomplish this task. His approach required that breeders define a group of traits or aggregate genotype to be improved. The economic value, positive or negative, of each of the traits in the aggregate was used to weight each of the traits for its contribution to total economic merit. Finally, phenotypic or genetic information on the same traits, some of the same traits plus some other traits, or on entirely different traits would be combined into a ‘selection index’ that increased total economic merit at the fastest possible rate. The selection index, properly calculated, has the property of maximum correlation between the traits in the index and total economic merit for traits in the aggregate genotype.

Dr Hazel's approach has guided the development of many useful selection indices, but it has some limitations. One of the major difficulties is defining an appropriate aggregate genotype. Another problem is determining the economic values of traits in that genotype, actually predicted forward to the time when offspring produced would generate income. Finally, the economic values need to be linear – perhaps ‘constant’ is the more descriptive term – across the range of genetic values for traits in the breeding objective.