Sheep - Breeding and genetics
Livestock health - Pregnancy toxaemia and hypocalcaemia
This DPI&F Note describes pregnancy toxaemia and hypocalcaemia, two metabolic diseases of ewes in late pregnancy. Pregnancy toxaemia is caused by a dietary deficiency of energy. Hypocalcaemia is caused by a calcium deficiency in the bloodstream.
Sheep breeding - Desire, ability and stamina of rams
This DPI&F Note discusses desire (libido), mating ability and stamina (serving capacity) of rams.
Sheep breeding - Ewe reproductive tract
This DPI&F Note describes the basic anatomy of the ewe's reproductive tract.
Sheep breeding - General ram management
Rams are a capital investment for any commercial or stud breeding enterprise and deserve special consideration. This DPI&F Note describes the factors to consider to ensure rams are in top working order.
Sheep breeding - Joining length
The joining period should be long enough to allow all ewes to become pregnant, but short enough to allow other management practices to be carried out on time. This DPI&F Note discusses the implications of various joining lengths.
Sheep breeding - Joining maiden ewes
This DPI&F Note discusses the factors to be considered when joining maiden ewes, including bodyweight, mothering ability, wool production and future lamb numbers.
Sheep breeding - Joining management to increase pregnancy rates
Poor ram and ewe management leading up to and during joining can substantially reduce pregnancy rates. This DPI&F Note describes some factors to optimise pregnancy rates.
Sheep breeding - Joining percentages
Young healthy rams joined under ideal conditions are capable of successfully serving large numbers of ewes. This DPI&F Note discusses the factors that influence joining percentages and suggests some optimum joining percentages.
Sheep breeding - Managing ovine brucellosis to maximise ram fertility
This DPI&F Note discusses the effect of ovine brucellosis on fertility and how it can be managed.
Sheep breeding - Net reproduction rate
This DPI&F Note discusses net reproduction rate, which is the number of ewe offspring reaching joining age and produced by each ewe during her lifetime in the breeding flock.
Sheep breeding - Oestrus, ovulation, fertilisation and embryo mortality
This DPI&F Note discusses oestrus, oestrous cycles, breeding season, ovulation, fertilisation, hormonal interactions and embryo mortality.
Sheep breeding - Ram culling and replacement policy
This DPI&F Note discusses culling rams on age, and reproductive and physical abnormalities. It also describes some of the important factos to consider when replacing rams to avoid temporary infertility of rams.
Sheep breeding - Ram health and well being
Rams require special treatment to ensure they are capable of successfully serving a large number of ewes. This DPI&F Note discusses the general management of rams including nutrition, shearing, and horn and hoof care.
Sheep breeding - Ram reproductive tract
The basic anatomy of the ram's reproductive tract is described in this DPI&F Note.
Sheep breeding - Sperm production in rams
Viable sperm production takes 49 days so rams need to be well looked after during the two month period leading up to joining. This DPI&F Note discusses sperm production and factors that influence it.
Sheep breeding - The economics of getting your ram management right
This DPI&F Note discusses ram cost per lamb produced for high conception, high lambing and low conception, low lambing scenarios and the returns under each of these scenarios.
Sheep breeding - The ram effect
The ram effect is where non-cycling ewes are stimulated to ovulate by the sudden introduction of rams or teasers. This page discusses how the ram effect works and some factors that influence it.
Sheep breeding - The ram paddock
One of the most effective ways of looking after rams is to provide a suitable ram paddock. This DPI&F Note discusses the features of a ram paddock that will minimise stress and subsequent fertility problems.
Sheep breeding - The role of genetics and the environment when replacing rams
This DPI&F Note discusses the genotype and phenotype of a sheep and the influence of the environment with regard to purchasing replacement rams.
Sheep breeding - Time of joining
Time of joining should be determined by seasonal rainfall probabilities. The objective being to lamb at a time of year when there is a high probability of good quality feed being available. This DPI&F Note discusses autumn and spring/summer joinings.
Sheep breeding - Unsound udders cause lamb loss
Udder damage in ewes can result in less milk produced, lower lamb survival and slower growth in surviving lambs. This DPI&F Note discusses causes of udder damage and how to reduce its incidence.
Sheep breeding - Use of ram sale measurements
This DPI&F Note explains some of the measurements used to describe sale rams. The most useful information to improve your current flock productivity is highlighted.
Sheep breeding - Wet and drying
This DPI&F Note discusses wet and drying, a technique used to identify ewes that have lambed, ewes that have lambed and lost, and ewes that are dry.
Sheep breeding - What to do when you get your replacement rams home
This DPI&F Note discusses important factors to consider when you return home with replacement rams. These include physical examinations, nutrition, diseases and parasites.
Sheep breeding and genetics
A quick link to a collection of up-to-date information on sheep breeding and genetics.
Sheep genetics - Genetic correlations in Merino sheep
This DPI&F Note describes genetic correlations. Genetic correlations occur when selecting for a particular character in a ram results in changes in other characters in the progeny. These characters are controlled by the same or linked genes.
Sheep genetics - Heritabilities for production characters in Merino sheep
When sheep are selected for breeding their better performance should be inherited by their offspring. This DPI&F Note describes heritability which estimates how much of the parents' superiority is, on average, passed onto their progeny.
Sheep genetics - Progeny testing of rams in Queensland
The most important decision that commercial sheep breeders must make is where to purchase their annual draft of rams. This DPI&F Note describes progeny testing of rams, which is a procedure for comparing ram sources.
Sheep genetics - Repeatability of production characters in Merino sheep
This DPI&F Note describes repeatability, which provides a measure of how reliable a current measurement of a character is as a prediction of future measurements of the same character.
Sheep genetics - Role of objective measurement
Commercial breeders should source rams from a stud using an objective selection program. This DPI&F Note discusses objective and visual selection in the stud and what it means for commercial breeders, plus some of the influences on objective measurements.
Sheep genetics - Selection of Merino sheep resistant to body strike
This DPI&F Note describes how susceptibility to body strike is a heritable trait in sheep that can be selected against to minimise blowfly strike.
Sheep genetics - Which grade of ram to choose?
Studs offer different grades of rams for sale. The higher the grade, the higher the price, which should equate with higher progeny performance. This DPI&F Note discusses how rams should be graded, genetic gain and lag and how much to pay for rams.
Sheep genetics - Which stud to choose?
This DPI&F Note discusses the role of studs in genetic improvement, breeding objectives, how to compare studs and how the stud selects its rams.
