Nutrient metabolism and utilization in the mammary gland

Knight, Christopher H.; Beever, D. E.

doi:10.1016/0301-6226(94)90164-3

Cited by 17 publications

(14 citation statements)

References 47 publications

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“…These results agree with studies by other authors (Knight et al, 1994;Gabai, 2003) showing that in spite of IGF-1 levels being associated with growth hormone concentrations, they do not necessarily reflect milk production levels. The results of this study indicate that under the experimental conditions, environmental adaptability mechanisms did not induce changes in IGF-1 serum levels.…”

Section: Resultssupporting

confidence: 81%

Genomic study of the mammary gland in bovines acclimated to a tropical environment

Wetzel-Gastal¹,

Feitor

Harten³

et al. 2016

SA J. An. Sci.

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This study aims at examining the expression of genes on the mammary gland, corresponding to various levels of adaptation or acclimatization to environmental stress. The authors utilized 18 cows from three genetic groups, Holstein Brazil (HB), Gyr (GG) and Gyrolando (GH ), all in the same stage of lactation, and subjected them to the same management conditions. Venous and arterial blood were collected to determine the hormonal profile and blood chemistry. Mammary gland tissue was used for transcriptomic studies. Prolactin and GH plasmatic concentrations were higher in Holstein animals. There were no differences in IGF-1 concentrations among the experimental groups. T 3 concentrations were similar among the Holstein and Gyr groups. From the 4608 transcripts in the BLO-Bovine EST (Michigan State University, US) databank that were used in this experiment, 105 differentially expressed genes were identified in at least one of the groups. Among these, the authors highlighted 14 genes that were related to the structure of the mammary gland (CRDGF, CD97, GH, endoglin, LTF, INPP, PTP), to response to thermal stress (Crh_11, v-Fos, Cdc37) and to milk protein (RPL35, κ-casein, β-casein, α-s2-casein). Eight of these were validated through real-time polymerase chain reaction. The HB animals, in comparison with the GH and Gyr groups, presented up-regulated genes associated with epithelium cellular differentiation and proliferation, milk productivity and decreased heat stress tolerance. Gyr animals presented up-regulated transcripts associated with cellular defence, apoptosis processes and increased tolerance to heat stress. The GH group showed intermediary results compared with the other two groups. ______________________________________________________________________________________

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Section: Resultssupporting

confidence: 81%

Genomic study of the mammary gland in bovines acclimated to a tropical environment

Wetzel-Gastal¹,

Feitor

Harten³

et al. 2016

SA J. An. Sci.

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“…It Correlations between essential amino acid extraction ratios appeared in the first plan of the principal component analysis (fig 11a). This was less obvious in the second plan (fig 11 b) (Baumrucker, 1985;Knight et al, 1994).…”

Section: Comparison Between Different Tissuesmentioning

confidence: 87%

Quantitative aspects of blood and amino acid flows in cattle

Lescoat

Sauvant²,

Danfær³

1996

Reprod. Nutr. Dev.

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Summary -A quantitative literature review was undertaken on the amino acid fluxes in ruminants and the factors which influence them. Two aspects were considered: blood flow and amino acid uptake by tissues. The statistical relationships indicated that blood flow was influenced by feed intake, metabolizable energy and milk production. The rates of amino acid uptake and release by tissues and organs varied greatly between compartments and between amino acids. The net rates of appearance were the result of a combination of inter-and intratissue phenomena. Simulated balances between supply and requirements revealed the limiting role of certain amino acids, depending on milk production level and growth rate. In conclusion, this approach underlined the technical difficulties involved in obtaining this type of data, and also revealed a lack of data in certains areas. Nevertheless, the observations in this review supported the implementation of the feed units used at the present time, notably for the addition of amino acids.

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“…Secondly, the amino acid uptake fractional rate, which was constant, influences the quantity taken by the mammary glands. However, as expected from the &dquo;pull&dquo; hypothesis (Knight et al, 1994) Figure 5). The goal is to find the closest flux or variable influenced by the tested parameter.…”

Section: Building Of the Model Diagrammentioning

confidence: 74%

“…This flux equation was consequently a straight utilization of the measurements made on the animals. However, the «pull» hypothesis, which assumes an active influence of the mammary gland metabolism on the flux (Knight et al, 1994) was also taken into account by a variable fractional uptake ratio, depending on the milk production level. Therefore this parameterization was a mix between a mechanistic approach and available measurements.…”

Section: Building Of the Model Diagrammentioning

confidence: 99%

“…As an example, this subsystem could influence the amino acid uptake by the mammary glands according to the «pull» hypothesis. This assumption states that this is the activity of the mammary gland metabolism which determines the quantity of amino acid taken up by this organ (Knight et al, 1994 A third parameterization to include the hypotheses in differential equations has been used for the lactating cow model. An example can be given by the amino acid uptake in the mammary glands which has been commonly measured by arteriovenous difference technique (Lescoat and Sauvant, 1994).…”

Section: Building Of the Model Diagrammentioning

confidence: 99%

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