Studies on Monozygous Cattle Twins

Hansson, A.; Claesson, Olof; Brännäng, E.

doi:10.1080/00015125409439935

Cited by 5 publications

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“…Our results confirm earlier evidence (Hansson et al 1954) that a period of incomplete removal of milk from the udder or an extended milking interval results not only in a temporary loss of secretory ability but also in characteristic changes in the composition of the secreted milk. The concentrations of lactose and potassium are depressed whereas the concentrations of sodium, chloride, casein and whey proteins are increased.…”

Section: Discussionsupporting

confidence: 92%

“…Where changes in the fat content are detected there is usually an increase (Bailey et al 1955;Elliott et al 1960) but Bailey, Clough, Dodd, Foot & Rowland (1953) observed a decrease in fat content when the incomplete milking continued for 6 weeks. There are, however, characteristic changes with length of milking interval in the concentrations of other milk constituents, more particularly a decrease in lactose content and an increase in chloride and, to a lesser extent, in protein contents, and these effects persist for some time after the resumption of normal milking (Hansson, Dassat & Claesson, 1954). Garrison & Turner (1936) have suggested that an increase in pressure within the udder as milk accumulates impairs the activity of the secretory cells: the rate of excretion of milk from the alveolar cells is reduced, the permeability of the cells to certain constituents of the blood, including chloride, is increased and, to maintain osmotic equilibrium of milk with blood, lactose synthesis is depressed.…”

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confidence: 99%

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The effect of incomplete milking or of an extended milking interval on the yield and composition of cow's milk

Wheelock¹,

Rook²,

Dodd³

1965

Journal of Dairy Research

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SXTMMAKY. The effect of incomplete milking or of an extended milking interval on the yield and composition of cow's milk has been investigated. At the 1st milking after either treatment, the yield of milk was augmented by a carry-over of milk but at the 2nd milking the yield was invariably depressed and then increased until the original yield, or slightly less, was recovered within 5 days. The concentration of lactose and potassium decreased and of sodium, chloride, whey proteins and casein increased during the period of the treatment, and on the resumption of normal milking the original composition was rapidly recovered. The changes in the composition of fat were less clearly denned because of residual milk effects but over the period of the treatment and the succeeding 6 milkings the effect was invariably to increase fat percentage. The differing effects on composition resulted in a more marked effect on the yields of lactose, potassium and casein than on those of sodium, chloride or the whey proteins throughout the treatment and recovery periods. When milk was removed in portions after an extended milking interval there were decreases in the concentrations of lactose and potassium and increases in those of sodium and chloride throughout normal milking. When the residual milk was obtained after an injection of oxytocin the composition of the portions of milk resembled that of the first portions of milk removed from the udder. The possible effects of the treatments on the secretory cells and the permeability of the udder tissue are discussed.

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Section: Discussionsupporting

confidence: 92%

mentioning

confidence: 99%

The effect of incomplete milking or of an extended milking interval on the yield and composition of cow's milk

Wheelock¹,

Rook²,

Dodd³

1965

Journal of Dairy Research

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“…The level of milk lactose is not affected by variations in the dietary intake of protein (Holmes et al, 1956;Logan et al, 1959;Holmes, Arnold & Provan, 1960;Rook & Line, 1961). It does not appear to be affected by reducing dietary energy intake to 75 per cent of Woodman's (1957) feeding standards or by energy intake in excess of these standards (Roadhouse & Henderson, 1930;Rook, 1953;Hansson, Claesson & Brannang, 1954;Holmes, Reid, MacLusky, Waite & Watson, 1957;Rook & Line, 1961). Variations in milk SNF content, concurrent with seasons or fluctuations in temperature and humidity appear to arise due to variations in the quality and quantity of ingested food rather than to any specific season or weather effect (see Rook, 1961a;Mac-Donald & Bell, 1958;Ragsdale, Thompson, Worstell & Brody, 1953).…”

Section: Feeding Effectsmentioning

confidence: 99%

Factors Affecting the Solids‐not‐fat Content of the Milk of Herds

Walsh

1968

Int J of Dairy Tech

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“…The decrease in milk yield is accompanied by a decrease in the content of solids-notfat (SNF) and an increase in the content of fat. Information on the effect of extended intervals on the rate of secretion of other constituents of milk is limited, but Hansson, Dassat & Claesson (1954) have observed a decrease in the lactose content and an increase in the chloride content at the end of intervals of 18 h or more. The effects of a milking interval of 60 h and of incomplete removal of milk from the udder on milk secretion ha\«s previously been investigated (Wheelock, Rook & Dodd, 1965 a).…”

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The effect of varying the interval between milkings on milk secretion

Wheelock¹,

Rook²,

Dodd³

et al. 1966

Journal of Dairy Research

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The effect of 6-, 12-, 18-, 24-, 30-and 36-h milking intervals on milk secretion has been investigated. The effect of the previous milking intervals was eliminated by interposing a recovery period consisting of 12-h milking intervals between the experimental intervals. Bias due to the carry-over of residual milk was reduced by removing the residual milk at the end of each milking, after an injection of oxytocin.The rate of secretion of milk and of the individual constituents decreased curvilinearly, with duration of the interval, but the degree of curvilinearity differed between constituents. The rates of decrease were in the following increasing order: sodium, chloride, fat, whey proteins, casein N, water, non-protein N, lactose and potassium. The effects of the treatments persisted for some time after the end of the experimental intervals, but the original rates of secretion were regained by the end of the recovery period. The differing effects on the secretion of individual constituents resulted in increases in the concentrations of sodium, chloride and whey proteins in the milk and decreases in those of lactose and potassium.The earliest work on the rate of secretion of milk was carried out by Ragsdale, Turner & Brody (1924), who concluded that there was a progressive decline in the rate of milk secretion with increase in the length of milking interval, and that there was an even more marked effect on the secretion of fat. In the interpretation of the results the authors assumed that the milk obtained at a milking was that which had been secreted in the previous interval. Johansson (1940) demonstrated, however, that there is a considerable carry-over of milk and of fat from one milking interval to the next. He found that the carry-over of residual fat was in direct proportion to the amount of milk in the udder before milking. This was confirmed by Bailey, Clough & Dodd (1955), and Turner (1953, 1955 showed that it was true also for residual milk. In the type of experiment devised by Ragsdale et al. (1924) the carryover would therefore bias the results so that the quantity of milk removed from the udder after short intervals would be greater than that secreted during the interval and, conversely, after a long milking interval the quantity removed would be less than the amount secreted. The effects would be even more marked for fat than for milk yield.• Present address: Department of Agriculture, The University, Leeds.

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Studies on Monozygous Cattle Twins

Cited by 5 publications

References 0 publications

The effect of incomplete milking or of an extended milking interval on the yield and composition of cow's milk

The effect of incomplete milking or of an extended milking interval on the yield and composition of cow's milk

Factors Affecting the Solids‐not‐fat Content of the Milk of Herds

The effect of varying the interval between milkings on milk secretion

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