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Abstract
The genetic relationships among carrier, fat, protein, and lactose will allow genetic alteration in any direction desired, although some changes would be much easier than others. Genetic parameters may vary somewhat between different populations, thus affecting the rates of different directions of change. In general, however, selection for an alteration in the fat:protein ratio would proceed rapidly, principally through alteration of fat concentration. Genetic alteration of composition is likely only if economic incentives for such change exist. Economic values, and therefore selection pressure, should be applied to amounts of components rather than concentrations. Recent developments in the theory of deriving economic weights for animal breeding indicate that selection indexes need to be reassessed. Although optimum breeding goals will vary somewhat, in most circumstances fat and protein yields and concentrations and the fat:protein ratio are likely to increase due to genetic selection. Only in the unlikely situation that fat has a very small or negative economic weight are other changes indicated. Lactose concentrations are unlikely to change much in any situation. Genetic variation in the composition of fat and protein, while of biological interest, is unlikely to be of more than minor importance in genetic improvement.
References
Banks, W., and D. D. Mnir. 1984. Milk utilization and manipulation of composition in the future. Page 17 in Milk compositional quality and its importance in future markets. Occas. Publ. 9, Br. Soc. Anim. Prod. M. E. Castle and R. G. Gunn, ed. Edinburgh, UK.
- Alteration of milk composition using molecular genetics.J. Dairy Sci. 1989; 72: 2826
Centre for Agricultural Strategy. 1985. Strategy for the UK dairy industry. Ctr. Agric. Strategy Rep. 4, Reading Univ., Reading. Engl.
- Pharmaceuticals from transgenic livestock.Trends Biotechnol. 1987; 5: 20
- Genetic parameters of milk yield and composition and their relationships with alternative breeding goals.J. Dairy Sci. 1987; 70: 1258
- Options and prospects for genetically altering milk composition.Anim. Breed. Abstr. 1987; 55: 231
Gibson, J.P. 1989.Selection on the major components of milk. Alternative methods of deriving economic weights. J. Dairy Sci. 72:(in press).
Gibson, J. P. 1989. The effect of pricing systems, economic weights and population parameters on economic response to selection on milk components. J. Dairy Sci. 72:(in press).
- The effect of milk protein genotypes on the cheese-making properties of milk and on the yield of cheese.in: Proc. 4th Conf, Aust. Assoc. Anim. Breeding Genet1984: 136
- The genetic basis for constructing selection indexes.Genetics. 1943; 28: 476
- Why alter milk composition?.J. Dairy Sci. 1989; 72: 2790
- Heritability of milk yield and composition at different levels and variability of production.Anim. Prod. 1983; 36: 59
- The composition of milk.in: Lactation. Vol. 3. Academic Press, London, UK1974: 3-6
- Lactational performance of various mammalian species.J. Dairy Sci. 1986; 69: 869
- Genetic engineering of caseins.Food Technol. 1985; (Oct. 1985): 89
- Reducing fat in milk and dairy products by breeding.J. Dairy Sci. 1982; 65: 443
- Effects of milk protein loci on first lactation production in dairy cattle.J. Dairy Sci. 1986; 69: 704
- Reliable phenotypic and genetic parameters in dairy cattle.in: Proc. 1st. Wld. Congr, Genet. Appl. Livest. Prod., Madrid 11974: 541
- Relationships between milk protein polymorphisms and cheese yielding capacity.J. Dairy Sci. 1986; 69: 1193
- Effects of milk protein genetic variants on milk yield and composition.J. Dairy Res. 1984; 51: 531
- Association of genetic variants of casein and milk serum proteins with milk, fat and protein production by dairy cattle.J. Dairy Sci. 1984; 67: 835
- Variation in milk protein concentrations associated with genetic polymorphism and environmental factors.J. Dairy Sci. 1987; 70: 563
- Effects of genetic variants of κ-casein and β-lactoglobulin on cheescmaking.J. Dairy Res. 1985; 52: 429
- The effects of changes in economic weights on the efficiency of index selection.J. Anim. Sci. 1983; 56: 1057
- On the derivation of economic weights in livestock improvement.Anim. Prod. 1986; 43: 545
- A discriminant function for plant selection.Ann. Eugenics. 1936; 7: 240
- Genetic differences in milk production in relation to mature body weight.Proc. Brit. Soc. Anim. Prod. 1973; 2: 15
- Altering milk composition through feeding.J. Dairy Sci. 1989; 72: 2801
- Consequences of a restriction of the herd milk production for the selection on milk, fat and protein.in: Krauβlich H. Lutterbach A. Adapting EEC cattle breeding programmes to market realities. Commiss. Eur. Commun, Brussels1985: 211-220
- The effect of errors in the economic weights on the accuracy of selection indexes.Ann. Genet. Sel. Anim. 1977; 8: 87
Wilcox, C. J., S. M. Gaunt, and B. R. Farthing. 1971. Genetic interrelationships of milk composition and yield. Sou. Coop. Ser. Bull. 155, Univ. Florida, Gainesville.
- Selection indices for quadratic models of total merit.Biometrics. 1968; 24: 937
- Production, consumption and pricing of milk and its components.J. Dairy Sci. 1986; 69: 272
Article info
Publication history
Accepted:
March 3,
1989
Received:
August 16,
1988
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© 1989 American Dairy Science Association. Published by Elsevier Inc.
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