470. The distribution of fat-globule size in sow's milk: I. The effect of sampling at intervals throughout milking

Whittlestone, W. G.

doi:10.1017/s0022029900006361

Cited by 23 publications

(9 citation statements)

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“…Significant differences between teats in the fat content of milk have been observed by Smith (1952) (1966). Though in the sow, in contrast to the cow, there is no systematic change in fat content throughout a milking (Whittlestone, 1952;Jylling & Sarensen, 1960), there is erratic variation (Perrin, 1954) and this will tend to mask differences between teats. The present results do not permit individual teat comparisons, but they confirm the greater variability for fat than for protein or lactose contents.…”

Section: Discussionmentioning

confidence: 99%

Intravenous infusion of glucose and insulin in relation to milk secretion in the sow

Reynolds

Rook

1977

Br J Nutr

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I . A comparison was made of the composition of milk from front and rear teats in four sows.There were small and not significant differences in fat, protein and lactose contents, and in the fatty-acid composition of the milk fat with the exception of the 18 :3 acid where the difference was also small but significant.2. The effects of intravenous infusions of glucose and insulin in lactating sows on milk secretion and blood composition were investigated in two sows.3. Intravenous infusion of glucose had no effect on blood plasma glucose concentration but increased the yields of lactose, protein and water.4. Intravenous infusion of insulin depressed plasma glucose concentration and the yields of lactose and water. The yield of protein was unaffected.5 . It is concluded that differences between the non-ruminant (the sow) and the ruminant in the responses in milk secretion to glucose infusion may be related to differences in the sensitivity to insulin of mammary tissue.

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Section: Discussionmentioning

confidence: 99%

Intravenous infusion of glucose and insulin in relation to milk secretion in the sow

Reynolds

Rook

1977

Br J Nutr

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“…In contrast with the cow, the sow shows no trend in the fat content of her milk throughout milking, nor is there any definite change in the fat globule distribution (4). Microscopic examination shows that the globules in sow's milk are somewhat smaller than those of cow's milk, and do not appear to cluster.…”

mentioning

confidence: 81%

“…It is evident that no marked change in fat globule size distribution occurs in cow's milk as it is being withdrawn. This is perhaps not surprising as no clear trends are shown in sow's milk, despite its containing a wide range of fat globule sizes (4). (2) has stated: 'The conclusion may be drawn that the rate of fat secretion, in proportion to the secretion of milk serum, is very little changed by variations in the degree of udder evacuation.…”

Section: The Creaming Rate Of Warm Cow's Milkmentioning

confidence: 99%

507. Variations in the fat content of milk throughout the milking process

Whittlestone¹

1953

Journal of Dairy Research

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It is well known that the fat content of cow's milk increases as the cow is being milked. CrowtherO) showed that this effect is reduced as the period between what is now known to be let-down, and actual milking is increased. Johansson (2) has described the effect in detail and has measured the influence of a number of factors on this change in composition. He has shown that the rise in fat percentage is greatest in cows giving a large yield of milk, or milked after comparatively long intervals. Incomplete milking, or 'super milking' with the aid of Pitocin, were shown to have little effect on the average fat percentage measured over a period of several days. These experiments suggest that abnormally high or abnormally low intramammary pressures do not preferentially decrease fat secretion, any pressure effect apparently acting on both fat and serum in the same way. The writer has found (3) that the distribution of fat globule sizes does not usually change greatly throughout the milking of the cow.In contrast with the cow, the sow shows no trend in the fat content of her milk throughout milking, nor is there any definite change in the fat globule distribution (4). Microscopic examination shows that the globules in sow's milk are somewhat smaller than those of cow's milk, and do not appear to cluster. Sow's colostrum is different in this respect, in that the globules cluster and, unlike sow's normal milk, the colostrum creams readily.Because of the differences between sow's and cow's milk, the writer has undertaken an examination of current theories explaining the trends in composition of cow's milk, and has modified one of the theories in an attempt to explain all of the facts. The following section is a brief review of theories at present in circulation.The creaming theory. This theory (5,6) suggests that the richness of cow's strippings is due to the cream being drawn last. If creaming in the udder could occur, it would certainly explain the effects observed, just as the non-creaming properties of sow's milk would explain the lack of a trend in the fat content of the latter. Two basic facts, however, make the theory untenable:(1) Most of the cow's milk is held in the alveoli prior to let-down. The diameter of the filled alveoli is of the order of 40-80 units (7, 8) so that any creaming which occurs, does so within a small volume. When the alveoli contract at let-down, the contents of the many alveoli will be mixed so that creaming effects will be largely eliminated, except perhaps for the small number of alveoli which empty via a ductule leaving the bottom of the lumen.(2) By milking a goat on its back after massaging tbe udder, Games (9) showed that the fat trend is still maintained, while Crowther(i) showed that the tendency for the fat

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“…the cow, the fat content of the milk increases as milking proceeds, the final ' strippings ' being particularly rich in fat (see Johansson, Korkman & Nelson, 1952), whereas in the sow there is no significant change in the fat content during milking (see Whittlestone, 1952). Preliminary analyses of serial milk samples collected from five rabbits showed no significant trends in milk composition nor were there significant variations in the composition of milk obtained from different mam¬ mary glands in the same rabbit.…”

Section: Milk Yieldsmentioning

confidence: 99%

Variations in the Yield and Composition of the Milk During Lactation in the Rabbit and the Galactopoietic Effect of Prolactin

Cowie¹

1969

Journal of Endocrinology

101

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The daily milk yields and the concentrations of fat, protein and lactose in the milk were studied throughout lactation in New Zealand White (NZW) and Dutch rabbits. The highest daily milk yields, 270 g. in the NZW and 140 g. in the Dutch rabbits, occurred at the end of the third week of lactation; on a body weight basis the yields were similar being 61\m=.\0and 62\m=.\3 g. milk/kg. body weight for the NZW and Dutch rabbits respectively. Over a 6-week period the total milk yields were 6940 g. for the NZW and 3820 g.for the Dutch rabbits.In both breeds considerable changes occurred in the composition of the milk after the third week of lactation. During the first 3 weeks the concentrations of fat, protein and lactose were approximately 15\p=n-\17, 11 and 1\ m=. \ 8\ p=n-\ 2\ m=. \ 0 g./100 ml. milk respectively, but during the fourth to the sixth week the values for fat and protein increased to 25\p=n-\30 and 18\p=n-\20 g./100 ml. respectively, while lactose declined to 0\m=.\5 g./100 ml. or less.Sheep prolactin (25 i.u. injected s.c. twice daily for 2 days) in late lactation was galactopoietic, augmenting both the daily milk yield and the concentration of lactose in the milk.From days 9 to 31 of lactation the NZW litters gained 0\m=.\45g. body weight/g. of milk consumed, the Dutch litters gained 0\m=.\38 g./g. of milk. This difference in weight increment was highly significant (P < 0\m=.\001) and was apparently due not to a higher calorie content of the milk of the NZW does but to a greater efficiency of milk utilization by the NZW litters.

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470. The distribution of fat-globule size in sow's milk: I. The effect of sampling at intervals throughout milking

Cited by 23 publications

References 1 publication

Intravenous infusion of glucose and insulin in relation to milk secretion in the sow

Intravenous infusion of glucose and insulin in relation to milk secretion in the sow

507. Variations in the fat content of milk throughout the milking process

Variations in the Yield and Composition of the Milk During Lactation in the Rabbit and the Galactopoietic Effect of Prolactin

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