Browsing by Author "Vermaak, Jacobus Vermaak"

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    Die aanwending van die CPM dairy model in formulering van voerrantsoene in 'n melkkudde
    (Stellenbosch : Stellenbosch University, 2005-04) Vermaak, Jacobus Vermaak; Cruywagen, C. W.; Stellenbosch University. Faculty of Agrisciences. Dept. of Animal Sciences.
    ENGLISH ABSTRACT: CPM Dairy was developed to maintain amino acid balance. because the correct amino acid relationship has an influence on milk production and milk composition (Schwab e/ af. 1992, Rulquin e/ af. 1993). Rulquin e/ af. (1993) found that an increase in lysine and methionine concentration in the diet had no meaningful effect on milk production and milkfat production. However, milk protein production is described as a function of lysine and methionine concentration. In order to balance the amino acid relationships, the CNCPS model has been adopted, using the following guidelines: I. a dairy cow feed characteristic scheme, described by Van Soest e/ af. (1991) and Sniffen e/ aI. (1992), II. a model for rumen fermentation and bacterial growth in the dairy cow, described by Russel e/ af. (1992), Ill. feed val ues for dairy cow feeds, described by Sniffen e/ af. (1992). IV. a set of formulas describing the feeding needs of dairy cows under different circumstances, assembled by Fox e/ af. (1992). Bateman e/ af. (2001) studied the accuracy of formulation models according to crude protein (CP) and amino acid (AA)-flow to the duodenum in lactating dairy cow diets. CPM Dairy does not calculate direct flow of CP to the duodenum, but the following adjustment was made: the change-over of metabolizable protein (MP) to CP is done by increasing bacterial protein from 60% to 100% of bacterial-CP. Intestinal digestion of fraction B3-protein is increased from 80% to 100%, whereas fraction C-protein is increased from 0 to 100% to change feed-MP to feed-CP. CP from feed and microbes are summed to indicate total CP-flow to the duodenum. AA-flow, as calculated by CPM Dairy, is used without adjustments. A rise in MUN-Ievels are typical to spring and summer months. which can be ascribed to high soluble protein and low soluble carbohydrates in grasses and legumes. This gives rise to an excess N-uptake in the bloodstream. Grass silage, when fed as primary feeding source. has the same reaction. Blood-urea-nitrogen (BUN) is the amount of urea-N found in the blood of the cow. MUN is the fraction ofN in the milk in the form of urea. MUN is normally 85% the concentration of BUN. Studies show that an increase in BUN/MUN levels leads to a negative effect on the reproductive ability of the cow. An increase in BUN-levels leads to an increase in urea in the reproductive tract of the animal. Urea passes between the blood plasma and the reproductive tract. It is therefore obvious that a high BUN-concentration leads to high levels of urea in the reproductive tract. In order to eradicate this problem. the use of deodorise in the supplemental feed of the lactating dairy cow \vas recommended. Deodorise is a natural product manufactured by Alltech. The product is derived from the Yuccha Schidigera plant. Two glycocomponents (CI and C II) of this plant binds gasses such as N1-I3. (Alltech information sheet) During .June to August 2002 data were collected regarding the effect of deodorise on lactating dairy cows. No meaningful difference between the two groups in this experiment was found.