Facteurs biologiques responsables des variations observées dans la précision des méthodes de routine utilisées pour le dosage de la matière grasse du lait (Milko-Tester, Infra-Red-Milk Analyser et Gerber)

Grappin, R.; Jeunet, R.; Rigogne, R.

doi:10.1051/lait:1972515-51618

Cited by 8 publications

(9 citation statements)

References 2 publications

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“…However, Grappin & Jeunet (1972) did not establish any effect on IR analyses due to stage of lactation. This might be due to confounding with season andlor feeding.…”

Section: Discussionmentioning

confidence: 62%

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Studies on Milk Analyses of Individual Cow Milk Samples

Sjaunja

1984

Acta Agriculturae Scandinavica

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Studies on, milk analyses of individual cow milk samples. 11. Factors affecting milk analyses by infrared technique under laboratory conditions. Acta Agric Scand 34: [260][261][262][263][264][265][266][267][268][269][270][271][272] 1983.Differences between infrared (hlilko-Scan 103) and reference methods (Gerber and Kjeldahl) in fat and protein determinations were studied in. individual cows of four breeds over a 7-month period. The overall accuracy of fat and protein determinations, expressed as the standard deviation (coefficient of variation) of the difference between the methods, was 0.1 1 percentage units (C.V.=2.3 56) and 0.05 percentage units (C.V.= I .5 %), respectively. Fat analyses were significantly influenced by the biological factors breed, cow, stage of lactation and somatic cell count, and protein analyses by breed and COW. The factors studied accounted for about 50% of the total variation in analysis differences. The indirect 1R principle for fat determination and its sensitivity to variations in fat composition and fat ' globule size explained the influence on the IR method of the biological factors tested. The non-correspondence between the 1R method and the reference method as regards protein \ i t s not only an instrumental effect, but was largely explained by the indirect analysis principle of the Kjeldahl method. Stage of lactation had the most pronounced effect on fat analyses with the IR method. Analyses of Jersey milkfat had the lowest accuracy of the breeds studied. The accuracy achieved (inherent accuracy of the apparatus) \bas found to be sufiicient for milk recording of individual c o w , but the need to investigate all relevant factors in a routine analysis system is emphasized. Key uwrds: biologicnl factors. routitre otralysis.

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“…However, Grappin & Jeunet (1972) did not establish any effect on IR analyses due to stage of lactation. This might be due to confounding with season andlor feeding.…”

Section: Discussionmentioning

confidence: 62%

“…Fatty acid composition can vary due to a variety of factors such as feed, breed, stage of lactation, season, mastitis, etc. The influence of some of these effects has been described by Shields (1973, Grappin & Jeunet (1972 Stirdies on ridk aiiaIjses of iridiwidira/ cow milk sariiples. I1 261…”

Section: Introductionmentioning

confidence: 96%

Studies on Milk Analyses of Individual Cow Milk Samples

Sjaunja

1984

Acta Agriculturae Scandinavica

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“…On constate qu'il y a un accroissement net des résultats MS 300 et IRMA et, inversement, une nette diminution des résultats MTA au fur et à mesure de l'augmentation de n». De l'analyse des résultats ressortent deux conclusions pratiques importantes déjà formulées dans une étude précédente (Grappin et Jeunet, 1972) : a) Les dosages de la matière grasse du lait avec le MS 300 comme avec l'IRMA et le MTA sont influencés par tous les facteurs biologiques modifiant la composition du lait en acides gras. Parmi ces facteurs, on peut citer essentiellement:…”

Section: Discussionunclassified

“…L'individu et le troupeau, dont l'influence ne peut pas être éliminée. Ainsi que nous l'avons déjà montré, il existe au niveau de l'indice de réfraction de la matière grasse un « effet animal }}et un ({effet troupeau )}significatifs (Grappin et Jeunet, 1972) qui peuvent entraîner dans certains cas des différences MS 300 -RG systémati-ques. Par conséquent, le MS 300 peut donner des résultats de matière grasse qui sont soit surestimés soit sous-estimés par rapport au RG, dans le calcul de la lactation d'un animal (lait individuel) ou de la livraison annuelle de lait d'un producteur (lait de troupeau).…”

Section: Discussionunclassified

Essais de l'appareil Milko-Scan 300 utilisé pour le dosage en série de la matière grasse et des protéines du lait

Grappin

Jeunet

1976

Lait

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“…NPN was determined according to (Rowland, 1938), and CA according to (Marier & Boulet, 1960). FP and SCC were analyzed with the automatic Cryoscope (Advanced, USA), and the Fossomatic (A/S N. Foss Electric, Denmark), respectively.…”

Section: Methodsmentioning

confidence: 99%