Relation of Production of Dairy Cows to the Nutrients Fed

Headley, F. B.

doi:10.2527/jas1945.44367x

Cited by 2 publications

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“…The increase in milk yield due to increases in starch equivalent, was, of course, much less than would be the case if the mean level of starch equivalent input had been lower. This is in agreement with other workers (Jensen et al (7), Headley (8)). The significant response in solids-not-fat percentage agreed with the work of Riddet, Campbell, McDowall & Cox(i4) and Rowland(i5).…”

Section: The Effects Of Starch Equivalent On Milk Yield and Milk Qualitysupporting

confidence: 94%

“…A further consideration to be remembered when using the results arises from the wellknown fact that biological production usually follows the law of diminishing returns (Jensen, Klein, Eauchenstein, Woodward & Smith(7); Headley (8)). This means that curvilinear regression is necessary to provide the best fit of any input and output relationship.…”

Section: Resultsmentioning

confidence: 99%

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475. Studies on variations in the solids-not-fat content of milk: V. Variations due to winter feeding practice

Bailey

1952

Journal of Dairy Research

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During the twelve years from 1935 to 1946 the type of foods given to sixty-one Dairy Shorthorn first calvers during the months of February and March changed so that the dry-matter intake of the cows rose and the dietary fat fell, but there was little change in the Protein and Starch equivalent they received.Milk yield varied directly with the amount of fat and starch equivalent in the diet and inversely with the dry matter.The solids-not-fat percentage of milk varied directly with the amount of starch equivalent, and inversely with the dry matter content, of the diet.The milk-fat percentage was not influenced by the foods given.It was shown that the fall in the level of solids-not-fat in the milk was largely due to the increase in the dry matter intake of the cows.

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Section: The Effects Of Starch Equivalent On Milk Yield and Milk Qualitysupporting

confidence: 94%

Section: Resultsmentioning

confidence: 99%

475. Studies on variations in the solids-not-fat content of milk: V. Variations due to winter feeding practice

Bailey

1952

Journal of Dairy Research

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“…The basal standard of rationing greatly affects results obtained from this type of experiment, and the biological optimum is not generally the economic optimum (17,18). In this connexion it should be noted that the law of diminishing returns (17,18,19) applies to the feeding of animals for milk production, and that the results of feeding experiments will depend on whether the animals are fed to capacity (as Blaxter's evidently were) or are more strictly rationed either by man or, in the case of most sheep, by the nature of their environment. Blaxter & French (20) tried the effect of feeding bulky foods at varying intervals during the day with a view to increasing the yield of milk from them.…”

Section: Nutrition General Consideeations and Feeding Standardsmentioning

confidence: 99%

Section A. Physiology of dairy cattle

Owen

1947

Journal of Dairy Research

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THE UTILIZATION OF NON-PEOTEIN NITROGEN Urea, if fed in a suitable mixture and in the presence of readily available carbohydrate, such as starch, can replace part of the protein in the rations of ruminants, for both growth and milk production (33). This is true even when the protein replaced is of high nutritive value. Nonruminants cannot use urea in this way(34,35,36,37,38). It appears from recent work (39,40) that non-protein nitrogen is utilized by ruminants'because the rumen abounds with iodophilic bacteria. In the presence of added urea and added available carbohydrate the multiplication of these iodophilic bacteria leads to the synthesis in their bodies of considerable amounts of 'bacterial starch' and, of course, of protein. Ammonia derived preferably from intraruminal hydrolysis of urea can serve as a source of nitrogen for these bacteria. The source of carbohydrate seems to be of a more specific nature. Thus in vitro starch and various sugars, such as maltose and galactose, may provide for the energy requirements of the iodophile bacteria of the rumen(39). When, however, instead of receiving sugar or starch the bacteria are supplied with glycerol, multiplication does not occur and protein synthesis is replaced by proteolysis. It may well be that, while hexoses or more complex carbohydrates are available either for synthesis of bacterial protoplasm or for breakdown into fatty acids (41, 42, 43,44,45,46), glycerol is only available for the latter process. Pearson & Smith (39) are of the opinion that analyses of materials abstracted through rumen fistulas may often be"subject to large and relatively uncontrollable errors of sampling, as, indeed, McElroy & 6oss(46) admit. Pearson & Smith (39) have therefore preferred to incubate rumen contents in vitro using the microscopic appearance of the bacterial flora and the pH. of such incubated material as criteria of normality. They found that under certain easily reproducible conditions the chemical and bacteriological nature of such material is still comparable with normal rumen contents after 3-4 hi. of incubation in vitro. Using this method of incubation they have shown that urea added to rumen contents is rapidly hydrolysed to ammonia. They have also shown (39) that hydrolysis and synthesis of protein can both occur in the rumen, synthesis of protein being favoured by the addition of urea and a readily available carbohydrate. Smith & Baker (40) investigated the correlation between bacterial multiplication and protein and polysaccharide synthesis in the rumen. Counts of Protozoa, and of each of several morphologically distinct types of bacteria, were recorded both before and after incubation. The volume of zoogloea was also determined. All these, except the Protozoa, increased on incubation, the contribution made by Amylococcus chains being greatest. When material consisting mainly of Amylococcus chains was isolated by centrifugation of material freshly removed from the rumen, it was found to be capable of a twelvefold increase by reproduction when incubated in...

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Relation of Production of Dairy Cows to the Nutrients Fed

Cited by 2 publications

References 0 publications

475. Studies on variations in the solids-not-fat content of milk: V. Variations due to winter feeding practice

475. Studies on variations in the solids-not-fat content of milk: V. Variations due to winter feeding practice

Section A. Physiology of dairy cattle

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