The biological basis of Maintenance and its relevance to assessing Responses to nutrients

Milligan, L. P.; Summers, Mark A.

doi:10.1079/pns19860053

Cited by 60 publications

(29 citation statements)

References 28 publications

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“…There may be variation between individuals as well as between breeds in the efficiency with which nutrients (food energy) are used for maintenance processes (Taylor et al 1986b). Ion transport is a major contributor to maintenance energy costs (Milligan & Summers, 1986) and has been found, in duodenal mucosa, to be enhanced in lactation in cows, although this may be as much the result of altered food consumption as a direct reflection of changed physiological state (McBride & Milligan, 1984). Genetic variations in ion transport costs have been identified as a result of selection for growth in sheep, but analogous differences in lactation have yet to be sought or identified.…”

Section: Animal Variationmentioning

confidence: 99%

Sources of variability in lactational performance

Oldham

Friggens

1989

Proc. Nutr. Soc.

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Variation in lactational performance comes about as a result of variation in the nature of the animal, its environment, or with time. Table 1 lists a variety of sources of variability, classified under broad headings of variation with the animal (species, breed and individual), with time and with various aspects of the environment. The list is probably not comprehensive, but even so, it contains more issues than can be dealt with in depth here. So we have chosen to select for comment a few issues in which we have a particular interest and which are likely to interest members of this Society.An important feature in any consideration of lactational performance must be to note that 'lactational performance' has many dimensions. There are elements of milk secretion, change in maternal state, the growth and well-being of offspring and, in species which display lactational oestrus, the initiation of a subsequent cycle of reproduction. Each of these elements of lactational performance varies depending on species, environment and time, but not usually independently of each other. So, for example, animals which are thin at parturition might adjust both the amount of food they choose to eat and their rate of milk secretion in relation to the extent and state of their body tissue reserves. There may also be metabolic adjustments which alter the likelihood of renewed conception. It is the concerted set of events which represents lactational performance. The orchestration of the various elements of overall performance is subject to a variety of controls which deal both with tactical (homeostasis) and strategic (homeorhetic) aspects of metabolism (Bauman & Cume, 1980).A thorough appraisal of variability in lactational performance requires knowledge of each of the different contributing elements. Unfortunately, many reports of lactation concentrate only on the milk secretory process and tend to ignore other, associated, changes. We have tried here to recognize and emphasize the multi-dimensional aspect of lactational performance, and to emphasize the important interactions between the nature of the animal and its environment in determining temporal changes in overall lactational performance.A number of important issues are dealt with superficially or not at all. In addition to papers in this symposium, the following are useful reference sources which deal with variability in lactational performance in relation to evolutionary strategies, the thermal Table 1. Sources of variability in lactational performance classifid according to animal, environment and time

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Section: Animal Variationmentioning

confidence: 99%

Sources of variability in lactational performance

Oldham

Friggens

1989

Proc. Nutr. Soc.

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“…McBride 1988) and whole-body energetics (Milligan and Summers 1986). Swaminathan et al (1989) found that Na+, K+ Arpase activity accounted for 39% of wholebody 02 consumption in the guinea pig.…”

mentioning

confidence: 99%

Quantification of in vitro and in vivo energy metabolism of the gastrointestinal tract of fed or fasted sheep

Kelly¹,

Southorn²,

Kelly³

et al. 1993

Can. J. Anim. Sci.

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“…The support metabolism is the increase in energetic expenses caused by the intensification of the processes of digestion, circulation, secretion, maintenance of the concentration gradients, muscular tonus and tissue renewal that occurs on levels above the energetic equilibrium (Milligan & Summers, 1986). Hence, the less the amount of metabolizable energy used for the maintenance metabolism and support metabolism, the higher the energy availability for body mass gain (energy retention in the body).…”

Section: Resultsmentioning

confidence: 99%

Energetic efficiency of protein and body fat retention in crossbred Bos indicus and Bos Taurus × Bos indicus raised under tropical conditions

et al. 2009

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-The efficiency of fat and protein retention by Bos indicus and its cross-breds was estimated from data obtained in the literature to verify possible differences between these animals and Bos taurus. After estimating the efficiencies, a correction factor was used to discount the metabolizable energy fraction that was spent in the maintenance and support metabolism processes. The efficiencies were then estimated again, assuming that all the remaining energy would correspond to the metabolizable energy available for body mass retention. The correction value used was considered satisfactory to discount energetic losses for maintenance and support. The efficiency values of partial body fat and protein retention in Bos indicus and its cross-bred were very similar to values reported by other authors who researched Bos taurus exclusively.Key Words: beef-cattle, bioenergetics, mathematical models Eficiência energética de retenção de proteína e gordura corporal em zebuínos e mestiços Europeu × Zebu mantidos em clima tropical RESUMO -A eficiência com que animais zebuínos e seus cruzamentos transformam a energia metabolizável consumida em gordura e proteína corporal foi estimada a partir de informações obtidas na literatura no intuito de verificar se existem diferenças entre esses animais e os de raças europeias. Após a estimativa das eficiências, usou-se uma correção para descontar a porção da energia metabolizável gasta na manutenção da massa corporal e no metabolismo de suporte.Posteriormente à aplicação da correção, as eficiências foram estimadas novamente, partindo-se do pressuposto de que o montante de energia restante corresponderia à energia metabolizável utilizada para acúmulo de massa corporal. O valor de correção utilizado foi considerado suficiente para descontar as perdas energéticas para mantença e suporte. Os valores de eficiência de retenção parcial de gordura e proteína corporal em animais zebuínos e mestiços Europeu × Zebu são muito próximos dos encontrados por outros autores em pesquisas com animais exclusivamente europeus.Palavras-chave: bioenergética, bovinos de corte, modelos matemáticos

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The biological basis of Maintenance and its relevance to assessing Responses to nutrients

Cited by 60 publications

References 28 publications

Sources of variability in lactational performance

Sources of variability in lactational performance

Quantification of in vitro and in vivo energy metabolism of the gastrointestinal tract of fed or fasted sheep

Energetic efficiency of protein and body fat retention in crossbred Bos indicus and Bos Taurus × Bos indicus raised under tropical conditions

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