scholarly journals Consequences of genetic change in farm animals on food intake and feeding behaviour

2001 ◽  
Vol 60 (1) ◽  
pp. 115-125 ◽  
Author(s):  
Gerry Emmans ◽  
Ilias Kyriazakis
Keyword(s):  
Growth Rate ◽  
Food Intake ◽  
Feeding Behaviour ◽  
Genetic Change ◽  
Farm Animals ◽  
The Past ◽  
Environmental Decisions ◽  
Selection For ◽  
The Cost ◽  
Over Time

Selection in commercial populations on aspects of output, such as for growth rate in poultry, against fatness and for growth rate in pigs, and for milk yield in cows, has had very large effects on such outputs over the past 50 years. Partly because of the cost of recording intake, there has been little or no selection for food intake or feeding behaviour. In order to predict the effects of such past, and future, selection on intake it is necessary to have some suitable theoretical framework. Intake needs to be predicted in order to make rational feeding and environmental decisions. The idea that an animal will eat ‘to meet its requirements’ has proved useful and continues to be fruitful. An important part of the idea is that the animal (genotype) can be described in a way that is sufficient for the accurate prediction of its outputs over time. Such descriptions can be combined with a set of nutritional constants to calculate requirements. There appears to have been no change in the nutritional constants under selection for output. Under such selection it is simplest to assume that changes in intake follow from the changes in output rates, so that intake changes become entirely predictable. It is suggested that other ways that have been proposed for predicting intake cannot be successful in predicting the effects of selection. Feeding behaviour is seen as being the means that the animal uses to attain its intake rather than being the means by which that intake can be predicted. Thus, the organisation of feeding behaviour can be used to predict neither intake nor the effects of selection on it.

Intensive selection for growth in broilers has not altered normal feeding behaviour

2009 ◽  
Vol 2009 ◽  
pp. 199-199
Author(s):  
J A Howie ◽  
B J Tolkamp ◽  
S Avendano ◽  
I Kyriazakis
Keyword(s):  
Growth Rate ◽  
Food Intake ◽  
Feeding Behaviour ◽  
Genetic Selection ◽  
Control Mechanisms ◽  
High Resource ◽  
Welfare Issue ◽  
Normal Feeding ◽  
Selection For ◽  
Intake Control

Selection for increased growth rate in livestock may be accompanied by increases in requirements for energy and nutrients. It has been suggested that intensively selected broilers have altered food intake control mechanisms and could be constantly hungry, due to their high resource demands (Bokkers et al. 2004), which would be a major welfare issue. Such alterations in food intake control mechanisms as a side-effect of genetic selection would lead to changes in the feeding behaviour of birds, such as the clustering of visits into meals and the probability of birds starting a new meal in relation to the time since the last meal. The aim of this study was to test whether broilers intensively selected for growth showed any alteration in the structure of their feeding behaviour that would indicate a change in the underlying hunger and satiety control mechanisms.

Responses in gilt post-farrowing traits and pre-weaning piglet growth to divergent selection for components of efficient lean growth rate

1996 ◽  
Vol 1996 ◽  
pp. 17-17
Author(s):  
J. C. Kerr ◽  
N. D. Cameron
Keyword(s):  
Growth Rate ◽  
Food Intake ◽  
Fixed Time ◽  
Divergent Selection ◽  
Large White ◽  
Lean Growth ◽  
Fixed Weight ◽  
Ad Libitum ◽  
Selection For ◽  
Piglet Growth

Responses in sow traits at farrowing and during lactation and in pre-weaning piglet growth rate were determined in a population of Large White pigs, after seven generations of divergent selection for components of efficient lean growth rate. Information on the factors influencing preweaning piglet growth rate is required for a comprehensive evaluation of alternative selection strategies.There were four selection groups: daily food intake (DFI), lean food conversion (LFC), lean growth rate (LGA) on ad-libitum feeding and lean growth rate on scale feeding (LGS). There were 242 gilts in the study, with 20 gilts in the high, low and control lines of each selection group. Pigs in the ad-libitum selection groups were performance tested over a fixed weight range of 30 to 85 kg. Pigs fed on scale feeding were performance tested for a fixed time period of 84 days from 30 kg with food intake equal to 0.75 g/g of daily ad-libitum food intake. Matings were unsupervised and took place in outside paddocks.

Consequences of variation in feeding behaviour for the probability of cows starting a meal as estimated from pooled data

2003 ◽  
Vol 2003 ◽  
pp. 7-7
Author(s):  
M. P. Yeates ◽  
B. J. Tolkamp ◽  
I. Kyriazakis
Keyword(s):  
Food Intake ◽  
Recent Work ◽  
Feeding Behaviour ◽  
Biological Significance ◽  
Simulation Models ◽  
Farm Animals ◽  
Short Term ◽  
Pooled Data ◽  
Intake Regulation ◽  
Insight Into

The analysis of short-term feeding behaviour may give insights into how food intake is regulated in farm animals. Food intake is often recorded in terms of feeding events, e.g. visits to feeders, which can be clustered into meals. This enables calculation of the probability of cows starting a meal in relation to time since the last meal, which is thought to give insight into intake regulation. Starting probabilities are often calculated after data have been pooled, e.g. across day and night or across individuals. Recent work suggested that such pooling might have strongly affected previously published conclusions. We therefore constructed simulation models to investigate how such pooling affects interpretation of feeding behaviour and consequently the biological significance attached to results.

scholarly journals Selection for plasmid post–segregational killing depends on multiple infection: evidence for the selection of more virulent parasites through parasite–level competition

2005 ◽  
Vol 272 (1561) ◽  
pp. 403-410 ◽  
Author(s):  
T. F. Cooper ◽  
J. A. Heinemann
Keyword(s):  
Growth Rate ◽  
Growth Rates ◽  
Multiple Infection ◽  
Virulence Determinant ◽  
New Hosts ◽  
Parasite Reproduction ◽  
Selection For ◽  
The Cost ◽  
Selection Of

Is the virulence of parasites an outcome of optimized infection? Virulence has often been considered an inevitable consequence of parasite reproduction when the cost incurred by the parasite in reducing the fitness of its current host is offset by increased infection of new hosts. More recent models have focused on how competition occurring between parasites during co–infection might effect selection of virulence. For example, if co–infection was common, parasites with higher intrinsic growth rates might be selected, even at the expense of being optimally adapted to infect new hosts. If growth rate is positively correlated with virulence, then competition would select increased virulence. We tested these models using a plasmid–encoded virulence determinant. The virulence determinant did not contribute to the plasmid's reproduction within or between hosts. Despite this, virulent plasmids were more successful than avirulent derivatives during selection in an environment allowing within–host competition. To explain these findings we propose and test a model in which virulent parasites are selected by reducing the reproduction of competitors.

The nutritional choices of farm animals: to eat or what to eat?

1997 ◽  
Vol 20 ◽  
pp. 55-65 ◽  
Author(s):  
I. Kyriazakis
Keyword(s):  
Food Intake ◽  
Animal Welfare ◽  
Goal Orientation ◽  
Feeding Behaviour ◽  
Internal State ◽  
Genetic Selection ◽  
Farm Animals ◽  
Large Magnitude ◽  
Short Term ◽  
Term Change

AbstractIrrespective of whether farm animals are given access to a single homogeneous food or to two or more heterogeneous foods as a choice, their feeding behaviour raises one of two questions (i) how much to eat, and (ii) what to eat? Despite frequent comment to the contrary, their feeding behaviour appears to be goal-orientated rather than random or purposeless. I therefore consider first the goals of farm animals in relation to their feeding behaviour. In general it is accepted that the overall biological framework in which all animals are trying to maximize fitness’ also applies to farm animals. However, some modification is called for in order to account for those situations in which intensive genetic selection has led to relatively ‘unfit’ reproducing animals and for those cases where animals are given access to foods which have not figured in their evolutionOn the basis that feeding behaviour is goal orientated, I then consider whether farm animals achieve their goals by monitoring their behaviour in the short or longer term. The conclusion drawn is that while short-term feeding behaviour may be a device to exploit the feeding environment effectively, it is largely unrelated to short-term fluctuations in an animal’s internal state. By contrast, longer-term feeding behaviour is very closely related to longer-term change in internal state, implying the maintenance of close control over feeding behaviour in terms of food intake and diet selection. All animals, including farm animals, are considered to be creatures of habit which maintain habitual feeding behaviour until a change is provoked by a significant alteration in their internal state. Such an alteration requires to be of significantly large magnitude and to be unlike the usual short-term, systematic fluctuations which occur over a day in the profiles of metabolites or hormones. Based on this premise, I contend that the mechanisms by which these disturbances are perceived by the animal will be general rather than specific. The notion that animals can fully achieve their goals by monitoring their feeding behaviour is obviously applicable in situations where they are given appropriate nutritional choices. Where animals are given inadequate or inappropriate choices, as is predominantly the case with farm animals, their feeding behaviour is designed to bring them as close as possible to their goals. Finally I consider the relevance of nutritional choices to farm animals by addressing the possibility of exploiting the goal orientation of feeding behaviour. I conclude that greater recognition of the goal-orientated nature of farm animals’ feeding behaviour can bring benefits in three areas: (i) improved biological understanding of animals’ goals; (ii) improved animal welfare; and (iii) improved animal performance.

scholarly journals R v Hall and the changing perceptions of the crime of bigamy

Legal Studies ◽  
2019 ◽  
Vol 39 (1) ◽  
pp. 1-17
Author(s):  
Rebecca Probert
Keyword(s):  
Nineteenth Century ◽  
The Past ◽  
The Future ◽  
The Law ◽  
The Cost ◽  
Over Time

AbstractIn 1845, the conviction of Thomas Hall for bigamy was reported as an example of the unequal way in which the law operated, with great play being made of the steps that Hall could have taken to free himself from his first wife by a divorce, were it not for the cost involved. Since then, virtually every account of nineteenth-century bigamy or divorce has included some version of the judge's apparently ‘brilliantly sarcastic’ speech.But what the judge was reported as saying at the time differs in a number of crucial particulars from what later commentators have reported him as saying. Later accounts have played up the misconduct of the first wife, inflated the cost of obtaining a divorce, and exaggerated the poverty and lowly status of Hall, while playing down the sentence he received and ignoring his deception of his second wife.This paper traces the evolution of the account over time, and identifies the timing of the various changes that were made. It illustrates how history is used – by politicians, reformers, and scholars – to support both a particular view of the past and to bolster claims as to how the law should change for the future.

Selection for components of efficient lean growth rate in pigs 4. Genetic and phenotypic parameter estimates and correlated responses in performance test traits with ad-libitum feeding

1994 ◽  
Vol 59 (2) ◽  
pp. 281-291 ◽  
Author(s):  
N. D. Cameron ◽  
M. K. Curran
Keyword(s):  
Growth Rate ◽  
Food Intake ◽  
Performance Test ◽  
Food Conversion ◽  
Daily Food Intake ◽  
Lean Growth ◽  
Daily Food ◽  
Genetic And Phenotypic Correlations ◽  
Selection For ◽  
Ad Libitum Feeding

AbstractGenetic and phenotypic parameters and correlated responses in performance test traits were estimated for populations of Large White (LW) and British Landrace (LR) pigs tested in Edinburgh and Wye respectively, to four generations of divergent selection for lean growth rate (LGA), lean food conversion (LFC) and daily food intake (DFI) with ad-libitum feeding.There were differences between the two populations in genetic parameters, as LW heritabilities for growth rate, daily food intake and backfat depths were higher and the correlation between growth rate and backfat was positive for LW, but negative for LR. However, heritabilities, genetic and phenotypic correlations were generally comparable between selection groups, within each population. Genetic and phenotypic correlations indicated that animals with high daily food intakes were faster growing, had positive residual food intakes (RFI), were fatter with higher food conversion ratios. RFI was highly correlated with daily food intake and food conversion ratio, but phenotypically independent of growth rate and backfat, as expected.Selection for LGA, in LW and LR populations, increased growth rate (54 and 101 g/day), but reduced backfat (−3·9 and −2·0 mm), food conversion ratio (−0·23 and −0·25) and total food intake (−11·8 and −12·6 kg). There was no change in daily food intake in LW pigs (−19 g/day), but daily food intake increased in the LR pigs (69 g/day). With selection for LFC in LW and LR populations, there was no response in groivth rate (9 and 9 g/day), but backfat (−4·1 and −2·1 mm), total (−6·6 and −11·8 kg) and daily food intake (−90 and −172 g) were reduced, as animals had lower food conversion ratios (−0·13 and −0·22). LW and LR pigs selected for DFI ate more food in total (6·8 and 5·9 kg) and on a daily basis (314 and 230 g), grew faster (94 and 51 g/day) and had higher food conversion ratios (0·12 and 0·13). Backfat was increased in LW pigs (3·7 mm), but not in the LR population.In general, efficiency of lean growth was improved by increasing groivth rate, with little change in daily food intake from selection for LGA, but was primarily due to reduced daily food intake with selection on LFC.

scholarly journals The problem of predicting food intake during the period of adaptation to a new food: a model

2003 ◽  
Vol 89 (3) ◽  
pp. 383-399 ◽  
Author(s):  
Emma C. Whittemore ◽  
Gerry C. Emmans ◽  
Ilias Kyriazakis
Keyword(s):  
Growth Rate ◽  
Food Intake ◽  
Time Course ◽  
Live Weight ◽  
Growth Function ◽  
Rate Of Change ◽  
Published Data ◽  
Potential Growth ◽  
Dry Food ◽  
Over Time

A model is described which aims to predict intake immediately following a change from one food to another that is higher in bulk content; it deals with the transition from one ‘equilibrium’ intake to another. The system considered is an immature pig fedad libitumon a single homogeneous food, which is balanced for nutrients and contains no toxins so that the first limiting resource is always energy. It is assumed that an animal has a desired rate of food intake (DFI) which is that needed to meet the energy requirements for protein and lipid deposition and for maintenance. DFI may not be achieved if a bulk constraint to intake exists. Where a bulk constraint operates intake is calculated as constrained food intake (CFI) where CFI=Cwhc/WHC k/ (where WHC is the water-holding capacity of the food (kg wate/g dry food) and Cwhcis the animal's capacity for WHC (unit/g live weight per d)). Where intake is not constrained it is assumed that genetic potential will be achieved. Potential growth rate is described by the Gompertz growth function. Where intake is constrained, growth will be less than the potential. Constrained growth rate is predicted as (d/t)con=(EI−Em)/egk/ where W is pig weight (kg), EI is energy intake (M/), Emis the energy required for maintenance (M/) and egis the energy required for unit gain (M/g). The value of egdepends on weight and the fattening characteristics of the pig. Actual growth is predicted to be the lesser of potential and constrained growth. To deal with adaptation it is assumed that the time taken to reach equilibrium depends on the difference in WHC values between the previous and current food and that the capacity to consume food bulk is related to the WHC of the current food. It is proposed that the capacity for WHC on the first day on a new food will be equal to the current capacity for WHC on the last day of the previous food. Thus Cwhc=(FI×WHC)/W /g, where FI is food intake (k/). Thereafter Cwhcwill gradually increase over time to a maximum of 0·27 /g. The rate of change in Cwhcis made to be the same for all pigs and all foods. The increase in capacity over time is assumed to be linear at the rate of 0·01 unit/. The model was tested using published data. Qualitatively the predictions of the model were in close agreement with the relevant observed data in at least some cases. It is concluded that the underlying theoretical assumptions of the model are reasonable. However, the model fails to predict initial intake when changed to foods high in wheat-bran content and fails to predict the intake of a non-limiting food where compensatory increases in intake and gain occur. The model could be adapted to overcome the first failure by taking into account the time course of digestive efficiency following a change in food. To deal with the second would require a sufficient understanding of the time course of compensatory growth.

Responses in gilt post-farrowing traits and pre-weaning piglet growth to divergent selection for components of efficient lean growth rate

1996 ◽  
Vol 63 (3) ◽  
pp. 523-531 ◽  
Author(s):  
J. C. Kerr ◽  
N. D. Cameron
Keyword(s):  
Growth Rate ◽  
Food Intake ◽  
Live Weight ◽  
Divergent Selection ◽  
Selection Strategy ◽  
Body Lipid ◽  
Large White ◽  
Lean Growth ◽  
Selection For ◽  
Piglet Growth

AbstractResponses in gilt live weight, backfat depth and food intake during lactation and in pre-weaning piglet growth rate were examined after seven generations of divergent selection for daily food intake (DFI), lean food conversion (LFC) or lean growth rate (LGA) on ad-libitum feeding or lean growth on restricted feeding (LGS). There were 252 Large White gilts in the study. Selection for low DFI resulted in gilts with less backfat (25·7 v. 30·7 (s.e.d. 2·21) mm) at farrowing and a substantially lowerfood intake (129 v. 146 (s.e.d. 5) kg) during lactation, but similar reductions in live weight (42 (s.e.d. 6) kg) and backfat depth (8·4 (s.e.d. 1·7) mm) than with selection for high DFI. Therefore, the lower piglet growth (167 v. 295 (s.e.d. 11) g/day) with selection for low DFI compared with selection for high DFI was primarily due to lower food intake of the gilts, as energy for milk production from food was reduced. In contrast, selection for high LFC resulted in relatively smaller changes in live weight (37 v. 48 (s.e.d. 5) kg) and backfat depth (7·6 v. 8·9 (s.e.d. 1·3) mm) than selection for low LFC, which combined with a lower food intake (132 v. 148 (s.e.d. 4) kg) during lactation, resulted in lower piglet growth (181 v. 200 (s.e.d. 11) g/day). The higher food intake of high LGA gilts (137 v. 121 (s.e.d. 4) kg) compensated for the relatively lower reductions in live weight (41 v. 46 (s.e.d. 5) kg) and backfat depth (5·5 v. 6·7 (s.e.d. 1·3) mm) during lactation compared with the low LGA line, such that piglet growth was similar (195 v. 289 (s.e.d. 11) g/day) in the two selection lines. In the high and low LGS selection lines, piglet growth was similar (195 v. 186 (s.e.d. 11) g/day) as was gilt food intake (125 v. 227 (s.e.d. 5) kg) and the changes in live weight (39 v. 41 (s.e.d. 6) kg) and backfat depth (8·1 v. 7·7 (s.e.d. 2·2) mm) during lactation. An examination of the daily energy used in litter gain and the energy available from gilt food intake and mobilization of body lipid indicated that one equation to predict the amount of body lipid mobilized during lactation was not appropriate for different genotypes. Responses in gilt food intake and the changes in live weight and backfat during lactation were selection strategy dependent. However, in general, the selection strategies which reduced gilt voluntary food intake during lactation or resulted in lower live weight and backfat depth at farrowing were detrimental to piglet growth rate.

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