So far in this course we have dealt entirely with the evolution of characters that are controlled by simple Mendelian inheritance at a single locus. There are notes on the course website about gametic disequilibrium and how allele frequencies change at two loci simultaneously, but we didn’t discuss them. In every example we’ve considered we’ve imagined that we could understand something about evolution by examining the evolution of a single gene. That’s the domain of classical population genetics. For the next few weeks we’re going to be exploring a field that’s actually older than classical population genetics, although the approach we’ll be taking to it involves the use of population genetic machinery. If you know a little about the history of evolutionary biology, you may know that after the rediscovery of Mendel’s work in 1900 there was a heated debate between the “biometricians” (e.g., Galton and Pearson) and the “Mendelians” (e.g., de Vries, Correns, Bateson, and Morgan). Biometricians asserted that the really important variation in evolution didn’t follow Mendelian rules. Height, weight, skin color, and similar traits seemed to

Human biochemical genetics

Manifestations of copper excess.

Variation in the Activities of Glutathione Peroxidase and Superoxide Dismutase and in the Concentration of Copper in the Blood in Various Breed Crosses of Sheep

INTRODUCTION .. . . . . . . . . . . . ...... . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . .. . . ........ . . . . . . . .. . . . . . . . . . . . 122 THIOMOLYBDATES: NUTRITIONAL DOUBTS AND CERTAINTIES .... 123 Qualitative Evidence for Thiomolybdate Formation in vivo . .. ..... . . . . . . . . . . . . .. . . . . . . . . 123 Qualitative Evidence for Thiomolybdate Inhibition of Copper Absorption ... . . . . . . . . . 123 Qualitative Evidence for Absorption of Thiomolybdates ......... . . . . . . . . . . . . . . . . . . . . . . . . . 124 Quantitative Evidence for Thiomolybdate Excretion in Feces... . . . . . . . . . 124 Systemic Effects of Thiomolybdates . . . . . . . . . . . . . . . . . . . . . . . . . 125 Conclusions on Physiological Importance of Thiomolybdates... .... . . . . . . . . . . . . . . . . . . . . . 129 NUTRITIONAL VARIABLES AFFECTING THE RUMEN INTERACTION . . ... . . . ... 130 Sulphur....... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130 Molybdenum 131 Copper . ... 131 Undigested Organic Matter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131 Sulphide-Trapping Agents ..... 131 Copper-Trapping Agents .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132 Post-RuminaIInteractions 132

The interactions between copper, molybdenum, and sulphur in ruminant nutrition.

Nutrient requirements of all livestock are based on the size of the animal, how active the animal is, the body growth rate, and/or the animal’s level of milk production and fat content in milk produced. Maintenance requirements are for low levels of activity as when being fed in a dry lot situation. When animals are on pasture activity increases and these the requirements may be as much as 25% higher due to this increased activity.

Nutrient Requirements of Sheep

A reappraisal of the calcium and phosphorus requirements of sheep and cattle

Changes in Cu concentration in the livers of adult Scottish Blackface (B), Welsh Mountain (W) and B × W ewes fed diets containing 4, 9, 17 and 29 mg Cu/kg D.M. were measured over a 28-week period. Measurement continued during two further periods of 18 weeks when first all sheep were fed the diet containing 4 mg Cu/kg D.M. and finally, when 4 mg Mo/kg D.M. was added to this diet.During the first period the increase on all diets was least in B ewes and, apart from the 4 mg Cu/kg D.M. diet, greatest in W ewes; this difference increased as the Cu in the diet increased. The rate of increase for all ewes diminished towards the end of the period. All breed types retained proportionately less Cu in their livers as the Cu in the diet increased; at one extreme B ewes fed 17 or 29 mg Cu/kg D.M. retained equal amounts.When during the second period all sheep were fed the 4 mg Cu/kg D.M. diet the Cu concentration in their livers decreased, the rate of decrease being greatest for ewes whose mean concentration in the liver was highest, but at similar concentrations the decrease was greater in B than W ewes. During the final period the decrease was faster and was again associated with the mean Cu concentration, but the decrease was not significantly affected by breed.Throughout the trial, W ewes had the highest concentration of Cu in their plasma, whilst B ewes and ewes fed the 4 mg Cu/kg D.M. diet throughout had the lowest concentrations both in plasma and in their kidneys at slaughter.The results show that breeds differ in their ability to retain Cu from the diet in their livers. The magnitude of these differences depends on the intake of Cu and Mo from the diet and is affected by the concentration of Cu in the liver. Breed differences in the absorption and endogenous loss of Cu are suggested.

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0021859600033608

The long-term accumulation and depletion of copper in the liver of different breeds of sheep fed diets of differing copper content

Lambs, 9 weeks of age, the offspring of sires of the Scottish Blackface, East Friesland, Finnish Landrace, Suffolk and Texel breeds mated to Scottish Blackface females, as a common maternal breed, were given diets containing 12 or 20 mg copper per kg dry matter for 13 weeks. Concentrations of liver copper and of copper and aspartate amino-transferase in the plasma were measured regularly, and the concentrations of copper in the kidney, mandible and cheek muscle were also measured terminally. Livers were examined for histological symptoms of copper toxicity.Wide breed variation was apparent in liver copper concentration after 6 weeks and in plasma aspartate aminotransferase concentration after 9 weeks. At slaughter, total liver copper and kidney copper concentration showed significant breed variation. For all traits, the Texel-cross lambs had the highest concentrations, followed by the Suffolk crosses, and the Blackface had the lowest. The proportion of ingested copper retained in the liver of the Texel-cross lambs was twice that of the Blackface lambs (0·137 v. 0·056), with the other breed crosses intermediate.There was a significant difference between diets for liver, kidney and mandible copper concentrations, plasma aspartate amino-transferase concentration, and for total liver copper but not for cheek muscle. Both diets produced elevated plasma aspartate amino-transferase concentration and histological symptoms of copper toxicity in the livers of some lambs.The results show large breed differences in the susceptibility to copper poisoning, some breeds being at risk when given diets containing 12mg copper per kg dry matter for long periods. There was no suggestion that breeds differed in resistance to poisoning other than through different retentions of copper consumed

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0003356100000969

The effect of breed of sire on the accumulation of copper in lambs, with particular reference to copper toxicity.

SUMMARY The effect of ratios of calcium to phosphorus in the diet (varying from 0·6 to 3·6) on the absorption and excretion of P was investigated with four sets of 9-month-old chimaera-derived triplets. A pelleted cereal-based diet supplemented to contain 1·5, 3·1 or 6·2 g P/kg D.M. and 3·4 or 5·4 g Ca/kg D.M. was used in a factorial design. The additional Ca in the diet reduced the efficiency of absorption of the P supplements in the diet by 0·18 ± 0·04. The efficiencies of absorption of total P were very similar within but markedly different between (P < 0·001) sets of triplets, the mean values being 0·62, 0·74, 0·82 and 0·84. The fractional absorption of inorganic P alone showed the same ranking and the mean values were 0·47, 0·67, 0·85 and 0·92. These differences between triplets support the view that the individual differences in P metabolism have a genetic basis. The mean absorbability of P in the basic diet (0·77) and in the P supplements (0·73) were similar. The pattern of excretion of absorbed P between the faecal and urinary route of excretion varied between the sets of triplets; as P intake increased, the additional absorbed P was excreted in faeces by one set, in urine by another and in faeces and urine by two sets. The relative importance of the faecal route was dependent upon the fractional absorption of P secreted into the gut.

The effect of dietary intake of calcium and phosphorus on the absorption and excretion of phosphorus in chimaera-derived sheep

Evidence was sought for genetic differences in the absorption or systemic use of copper by comparing responses in plasma Cu concentration to oral and intravenous Cu repletion. Lambs of the North Ronaldsay (Orkney), Scottish Blackface and Welsh Mountain breeds and crosses of these with the North Ronaldsay were used.In two oral repletion phases average Cu intakes/kg live weight were 0·87 and 0·63 mg/week and similar for all breed groups. Plasma Cu concentrations of Scottish Blackface lambs showed little or no increase while those of North Ronaldsay lambs increased rapidly, and those of Welsh Mountain lambs increased moderately. The plasma Cu concentrations of the cross-breds increased more rapidly in the first than in the second phase; their rate of change lay between the pure breeds but was closer to that of the North Ronaldsay in the first phase.The rates of increase in plasma Cu concentration during intravenous repletion were relatively uniform for the different breeds and crosses except the Blackface which showed a lower rate. It was concluded that the large differences between groups in response to oral Cu repletion were largely attributable to differences in the efficiency of Cu absorption.

Breed differences in copper-metabolism in sheep

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