Genetic Forces Influence our Breeding Programmes
There are two significant genetic forces that are involved in the breeding of our production animals that are not generally recognised by stud breeders and their commercial clients.
The first and most dominant factor, is that all living species are “programmed for survival” in the environment which is their natural habitat. Genetic diversity enabled them to evolve and survive in the harsh reality of climatic extremes, diseases, parasites and their predators.
The second, and less dominant genetic factor, is the influence and direction of the breeding programme over the past 10 to 20 generations.
Now let us first study in more details the dominant genetic forces which ensured the survival of our farmed animals in their natural environment before man’s intervention.
To survive, they had to adapt to seasonal changes and environmental conditions. Their immune systems had to evolve to protect them from diseases and parasites. Predators were a constant threat so they had to develop to evade detection - camouflage – the ability to fight and the agility to escape. All these genes that produced these survival traits are the dominant survival genes.
Cattle grew horns to fight off predators, and had a lethal kick. Their udders were small which did not impede speed and agility. Their new born were most vulnerable to predators so they removed the evidence of a recent birth by consuming the afterbirth. They also developed the ability to hide their calves in secluded spots, and they only produced enough offspring to ensure the survival of their species.
Sheep, being smaller, had more predators and produced a few twins to maintain numbers. They developed multi coloured coats in varying shades of black, grey, brown with some white to match the arid hills and mountains of their habitat in North Africa, Southern Europe, Asia and North America. This camouflage ensured that they were difficult to detect by their mainly short sighted predators. Their coats, made up of two fibres were shed every spring. Hair, the long primary fibre shed the water and protected the secondary shorter fibre, wool, which insulated sheep from cold and excessive heat. This in turn conserved energy. They were light boned, light bodies, carried no excessive muscle or fat which ensured mobility and agility in their mainly rocky habitat. Horns were grown to deter small predators. Sheep were browsers rather than grazers so developed pointed noses with narrow jaws and long narrow teeth. Again to remove evidence of a recent birth, they would sometimes consume the afterbirth (I once found a ewe that had died choking on her afterbirth). All these are the dominant survival which have evolved over huge periods of time.
All these survival traits became redundant when man emerged from the hunter/gatherer era and established communities and started farming. Fleeces were clipped, spun and woven into fabrics. Hair and coloured fibre became undesirable so man, without any knowledge of genetics, learned that by selecting for white wool (which could be dyed with natural dyes) and against hair, progress could be made.
In New Zealand in the early 1900’s the Romney breed started to emerge as the dominant breed and by the 1940’s comprised about 80% of the national flock. These early breeders, who tend to be underestimated by modern sheep breeders and academics, recognised that the dominant survival genes had a negative impact on wool quality (black fibre and hair) and that light bone and narrow jaws affected constitution. Over this period, wool was king and large numbers of weathers were farmed for producing quality wool. As a consequence fertility was not considered important or selected for. So, these early breeders bred heavy boned sheep with barrel chests and big gut capacity. They found that the narrow teeth set in narrow jaws, suitable for browsing, became “gappy” and tended to fall out. So strong, wide jaws with wide teeth were bred for. In these early days, little fertiliser was applied so the demand was for structurally sound, strong constitutioned sheep to be bred. They also selected for thick skinned animals (as judged by the thickness of the ear), as they knew that thick skinned lambs had a better survival rate. They knew that darkness about the face, and particularly dark ears were indicators of the presence of the black fibre gene.
With the advent of the National Recording Scheme in 1967 (which I joined) the forerunner of today’s SIL Programme, selection processes have changed. Out with the old and in with the new. Many academics, most of whom had never bred sheep, dismissed the selection criteria of early breeders as fad that had no relevance in breeding productive sheep. The theory promoted at that time was that “if a so called fault (be it varying structural faults, or faulty jaws, feet, black fibre or hair) – did not affect productivity then they should be ignored”. Many ram breeders and ram breeding groups accept this theory and applied it by only breeding for production traits and in some cases FE tolerance. In many cases, physical faults including black fibre, were ignored. However, like many theories, this particular one failed in practice. Why? Because many faults do not show up immediately in the production figures. Take foot faults as an example. Generally, foot problems are less apparent in young sheep when production data is accessed and a ranking is made. Similarly with black fibre. There is no way this fault can affect productivity traits, yet black fibre in a wool clip will drop the price significantly. In some exotic breeds, black fibre is quite prevalent.
Over a number of years, I have heard it stated that there are links between black fibre and FE tolerance and that in breeding for this trait, the incidence of black fibre would increase. This assumption is incorrect. It is however, a convenient excuse for using sires that were highly tolerant to FE which also carried the black gene. The black fibre and horn genes would be amongst the most powerful of the survival genes. Like many weeds, they will dominate given any opportunity and once established are virtually impossible to eliminate. The ram pictured carrying this horn gene is a good example of this particular survival gene. There is no way any Romney ram like this would have been used since the breed arrived in New Zealand in the 1860’s. Yet, by using such a ram, horns could become the norm in several generations. Likewise, it took man several thousand years to breed white wool and eliminate hair from the fleece. However, black and coloured sheep breeders have bred sheep with fleeces of all shades of brown, grey and black in just a few generations, which again illustrates the dominance of the survival genes. All farmers, and particularly stud breeders, need to recognise that these dominant survival genes, although not apparent, are waiting in the wings for an opportunity to once again have a dominant role centre stage.
The second genetic factor influencing our breeding programmes is less dominant. The breeding programmes adopted the by the stud breeders over the past 10 or more generations will determine the performance over the next several generations and the flocks and herds of their clients. All sires from a particular flock or herd, regardless of whether they are top or bottom ranking animals in production of physical traits, will tend to leave progeny with the same strengths and weaknesses of their parent flock or herd. It is possible – or perhaps probable – that a low ranking sire from a top flock could be a better option than a top sire from a poor performing flock. This principle applies across all production and physical traits, and across all species.
Every flock or herd in the country – including my own – will have its strengths and weaknesses. It is easier to understand figures because they appear to be absolute, but in a farming environment, these figures can be compromised by environmental and health issues. It is much more difficult to access physical strengths and weaknesses, and balance one against the other. Quite honestly, I question whether some stud breeders have the skills to make these judgements, and hence serious faults are missed or ignored. Breeding is all about building on the strengths and eliminating weaknesses and the skill of the stud breeder to make the correct decisions.
Gordon Levet
October 2016
The first and most dominant factor, is that all living species are “programmed for survival” in the environment which is their natural habitat. Genetic diversity enabled them to evolve and survive in the harsh reality of climatic extremes, diseases, parasites and their predators.
The second, and less dominant genetic factor, is the influence and direction of the breeding programme over the past 10 to 20 generations.
Now let us first study in more details the dominant genetic forces which ensured the survival of our farmed animals in their natural environment before man’s intervention.
To survive, they had to adapt to seasonal changes and environmental conditions. Their immune systems had to evolve to protect them from diseases and parasites. Predators were a constant threat so they had to develop to evade detection - camouflage – the ability to fight and the agility to escape. All these genes that produced these survival traits are the dominant survival genes.
Cattle grew horns to fight off predators, and had a lethal kick. Their udders were small which did not impede speed and agility. Their new born were most vulnerable to predators so they removed the evidence of a recent birth by consuming the afterbirth. They also developed the ability to hide their calves in secluded spots, and they only produced enough offspring to ensure the survival of their species.
Sheep, being smaller, had more predators and produced a few twins to maintain numbers. They developed multi coloured coats in varying shades of black, grey, brown with some white to match the arid hills and mountains of their habitat in North Africa, Southern Europe, Asia and North America. This camouflage ensured that they were difficult to detect by their mainly short sighted predators. Their coats, made up of two fibres were shed every spring. Hair, the long primary fibre shed the water and protected the secondary shorter fibre, wool, which insulated sheep from cold and excessive heat. This in turn conserved energy. They were light boned, light bodies, carried no excessive muscle or fat which ensured mobility and agility in their mainly rocky habitat. Horns were grown to deter small predators. Sheep were browsers rather than grazers so developed pointed noses with narrow jaws and long narrow teeth. Again to remove evidence of a recent birth, they would sometimes consume the afterbirth (I once found a ewe that had died choking on her afterbirth). All these are the dominant survival which have evolved over huge periods of time.
All these survival traits became redundant when man emerged from the hunter/gatherer era and established communities and started farming. Fleeces were clipped, spun and woven into fabrics. Hair and coloured fibre became undesirable so man, without any knowledge of genetics, learned that by selecting for white wool (which could be dyed with natural dyes) and against hair, progress could be made.
In New Zealand in the early 1900’s the Romney breed started to emerge as the dominant breed and by the 1940’s comprised about 80% of the national flock. These early breeders, who tend to be underestimated by modern sheep breeders and academics, recognised that the dominant survival genes had a negative impact on wool quality (black fibre and hair) and that light bone and narrow jaws affected constitution. Over this period, wool was king and large numbers of weathers were farmed for producing quality wool. As a consequence fertility was not considered important or selected for. So, these early breeders bred heavy boned sheep with barrel chests and big gut capacity. They found that the narrow teeth set in narrow jaws, suitable for browsing, became “gappy” and tended to fall out. So strong, wide jaws with wide teeth were bred for. In these early days, little fertiliser was applied so the demand was for structurally sound, strong constitutioned sheep to be bred. They also selected for thick skinned animals (as judged by the thickness of the ear), as they knew that thick skinned lambs had a better survival rate. They knew that darkness about the face, and particularly dark ears were indicators of the presence of the black fibre gene.
With the advent of the National Recording Scheme in 1967 (which I joined) the forerunner of today’s SIL Programme, selection processes have changed. Out with the old and in with the new. Many academics, most of whom had never bred sheep, dismissed the selection criteria of early breeders as fad that had no relevance in breeding productive sheep. The theory promoted at that time was that “if a so called fault (be it varying structural faults, or faulty jaws, feet, black fibre or hair) – did not affect productivity then they should be ignored”. Many ram breeders and ram breeding groups accept this theory and applied it by only breeding for production traits and in some cases FE tolerance. In many cases, physical faults including black fibre, were ignored. However, like many theories, this particular one failed in practice. Why? Because many faults do not show up immediately in the production figures. Take foot faults as an example. Generally, foot problems are less apparent in young sheep when production data is accessed and a ranking is made. Similarly with black fibre. There is no way this fault can affect productivity traits, yet black fibre in a wool clip will drop the price significantly. In some exotic breeds, black fibre is quite prevalent.
Over a number of years, I have heard it stated that there are links between black fibre and FE tolerance and that in breeding for this trait, the incidence of black fibre would increase. This assumption is incorrect. It is however, a convenient excuse for using sires that were highly tolerant to FE which also carried the black gene. The black fibre and horn genes would be amongst the most powerful of the survival genes. Like many weeds, they will dominate given any opportunity and once established are virtually impossible to eliminate. The ram pictured carrying this horn gene is a good example of this particular survival gene. There is no way any Romney ram like this would have been used since the breed arrived in New Zealand in the 1860’s. Yet, by using such a ram, horns could become the norm in several generations. Likewise, it took man several thousand years to breed white wool and eliminate hair from the fleece. However, black and coloured sheep breeders have bred sheep with fleeces of all shades of brown, grey and black in just a few generations, which again illustrates the dominance of the survival genes. All farmers, and particularly stud breeders, need to recognise that these dominant survival genes, although not apparent, are waiting in the wings for an opportunity to once again have a dominant role centre stage.
The second genetic factor influencing our breeding programmes is less dominant. The breeding programmes adopted the by the stud breeders over the past 10 or more generations will determine the performance over the next several generations and the flocks and herds of their clients. All sires from a particular flock or herd, regardless of whether they are top or bottom ranking animals in production of physical traits, will tend to leave progeny with the same strengths and weaknesses of their parent flock or herd. It is possible – or perhaps probable – that a low ranking sire from a top flock could be a better option than a top sire from a poor performing flock. This principle applies across all production and physical traits, and across all species.
Every flock or herd in the country – including my own – will have its strengths and weaknesses. It is easier to understand figures because they appear to be absolute, but in a farming environment, these figures can be compromised by environmental and health issues. It is much more difficult to access physical strengths and weaknesses, and balance one against the other. Quite honestly, I question whether some stud breeders have the skills to make these judgements, and hence serious faults are missed or ignored. Breeding is all about building on the strengths and eliminating weaknesses and the skill of the stud breeder to make the correct decisions.
Gordon Levet
October 2016