Genetic size-scaling rules in animal growth

Taylor, C. S.

doi:10.1017/s0003356100023941

Cited by 112 publications

(61 citation statements)

References 6 publications

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“…Although all these models recognize the need for genetically driven trajectories (either explicitly or implicitly), they do not invoke (physiological state dependent) genetic expression, but instead use time as the driver to generate the homeorhetic trajectories. This may seem like a detail, but studies of growth have shown that relating trajectories to measures of physiological state, for example, degree of maturity, greatly extends the ability of models to accommodate genotype differences (Taylor, 1980;Emmans and Kyriazakis, 2001;Doeschl-Wilson et al, 2007).…”

Section: Introductionmentioning

confidence: 99%

“…The notion of teleonomic trajectories is not new; it is implicit in the idea of potential curves of, for example, growth or lactation, as these imply a genetically driven performance goal. Models that seek to describe potential growth have a long history (see Taylor, 1980;Emmans, 1997), and lactation models explicitly aimed at describing potential have also been proposed (Friggens et al, 1999). Interestingly, the model of Friggens et al (1999) based on a heuristic view of milk production turns out to be the same as the model of Dijkstra et al (1997) derived from a mechanistic view.…”

Section: Introductionmentioning

confidence: 99%

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Advances in predicting nutrient partitioning in the dairy cow: recognizing the central role of genotype and its expression through time

Friggens

Brun-Lafleur

Faverdin

et al. 2013

Animal

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In recent years, it has become increasingly clear that understanding nutrient partitioning is central to a much broader range of issues than just being able to predict productive outputs. The extent to which nutrients are partitioned to other functions such as health and reproduction is clearly important, as are the efficiency consequences of nutrient partitioning. Further, with increasing environmental variability, there is a greater need to be able to predict the ability of an animal to respond to the nutritional limitations that arise from the environment in which it is placed. How the animal partitions its nutrients when resources are limited, or imbalanced, is a major component of its ability to cope, that is, its robustness. There is mounting evidence that reliance on body reserves is increased and that robustness of dairy cows is reduced by selection for increased milk production. A key element for predicting the partition of nutrients in this wider context is to incorporate the priorities of the animal, that is, an explicit recognition of the role of both the cow's genotype (genetic make-up), and the expression of this genotype through time on nutrient partitioning. Accordingly, there has been a growing recognition of the need to incorporate in nutritional models these innate driving forces that alter nutrient partitioning according to physiological state, the genetically driven trajectories. This paper summarizes some of the work carried out to extend nutritional models to incorporate these trajectories, the genetic effects on them, as well as how these factors affect the homeostatic capacity of the animal. At present, there are models capable of predicting the partition of nutrients throughout lactation for cows of differing milk production potentials. Information concerning genotype and stage of lactation effects on homeostatic capacity has not yet been explicitly included in metabolic models that predict nutrient partition, although recent results suggest that this is achievable. These developments have greatly extended the generality of nutrient partitioning models with respect to the type of animal and its physiological state. However, these models remain very largely focussed on predicting partition between productive outputs and body reserves and, for the most part, remain research models, although substantial progress has been made towards developing models that can be applied in the field. The challenge of linking prediction of nutrient partitioning to its consequences on health, reproduction and longevity, although widely recognized, is only now beginning to be addressed. This is an important perspective for future work on nutrient partitioning.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Advances in predicting nutrient partitioning in the dairy cow: recognizing the central role of genotype and its expression through time

Friggens

Brun-Lafleur

Faverdin

et al. 2013

Animal

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“…Intake of different sheep breeds at a BW may vary with mature BW, called A. Taylor (1980) proposed 2 genetic size-scaling rules. The first was to treat all time variables, such as daily feed intake, as proportional to A 0.73 .…”

Section: Introductionmentioning

confidence: 99%

Feed intake of sheep as affected by body weight, breed, sex, and feed composition1

Lewis

Emmans

2010

Journal of Animal Science

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ABSTRACT:The hypotheses tested were that genetic size-scaling for mature BW (A, kg) would reduce variation in intake between kinds of sheep and that quadratic polynomials on u = BW/A with zero intercept would provide good descriptions of the relationship between scaled intake (SI, g/A 0.73 d) and degree of maturity in BW (u) across feeds of differing quality. Both sexes of Suffolk sheep from 2 experimental lines (n = 225) and from 3 breed types (Suffolk, Scottish Blackface, and their cross; n = 149) were recorded weekly for ad libitum feed intake and BW; recording of intake was from weaning through, in some cases, near maturity. Six diets of different quality were fed ad libitum. The relationship between intake and BW on a given feed varied considerably between kinds of sheep. Much, but not all, of that variation was removed by genetic size-scaling. In males, the maximum value of SI was greater than in females (P = 0.07) and was greater in Suffolk than in Scottish Blackface, with the cross intermediate (P = 0.025); there was no difference between the 2 Suffolk lines used (P = 0.106). The quadratic polynomial model, through the origin, was compared with a split-line (spline) regression for describing how SI varied with u. For the spline model, the intercept was not different from zero in any case (P > 0.05). The values of u at which SI achieved its maximum value (u* and SI*) were calculated. Both models fit the data well; the quadratic was preferred because it predicted that SI* would be achieved within the range of the long-run data, as was observed. On a high quality feed, for the spline regression, u* varied little around 0.434 (SD = 0.020) for the 10 different kinds of sheep used. For the quadratic, the mean value of 0.643 (SD = 0.066) was more variable, but there were no consistent effects of kind of sheep. The values of u* and SI* estimated using the quadratic model varied among the 6 feeds: 0.643 and 78.5 on high quality; 0.760 and 79.6 on medium protein content; 0.859 and 73.3 on low protein content; 0.756 and 112 on a low energy content feed; 0.937 and 107 on ryegrass; and 1 (forced, as the fitted value of 1.11 was infeasible) and 135 on Lucerne. The value of u* tended to increase as feed digestibility decreased. We conclude that genetic size-scaling of intake is useful and that a quadratic polynomial with zero intercept provides a good description of the relationship between SI and u for different kinds of sheep on feeds of different quality. Up to u ≅ 0.45, intake was directly proportional to BW.

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“…Because of the differeqt gmwth rates 40% and 500/0). For a detailed comparison between hybrid groups, the effect of genetic size scaling (Taylor, 1980) may be an interesting aspect for further study.…”

Section: Resultsmentioning

confidence: 99%

Comparison of Meat Production Potential of Hybrids fromBos grunniens(Yak) and SixBos taurusBreeds: A Deterministic Simulation Model for Economic Evaluation

Wang

Vandepitte

1994

Journal of Applied Animal Research

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Genetic size-scaling rules in animal growth

Cited by 112 publications

References 6 publications

Advances in predicting nutrient partitioning in the dairy cow: recognizing the central role of genotype and its expression through time

Advances in predicting nutrient partitioning in the dairy cow: recognizing the central role of genotype and its expression through time

Feed intake of sheep as affected by body weight, breed, sex, and feed composition1

Comparison of Meat Production Potential of Hybrids fromBos grunniens(Yak) and SixBos taurusBreeds: A Deterministic Simulation Model for Economic Evaluation

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