Department of Animal Sciences

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Browsing Department of Animal Sciences by browse.metadata.advisor "Brand, Tersius Swanepoel"

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    Manipulation of the rumen environment to increase rumen undegradable protein fraction of feedstuffs
    (Stellenbosch : Stellenbosch University, 2024-03) Van Rensburg, Waldo; Brand, Tersius Swanepoel; Van Zyl, Johan Hendrik Combrink; Stellenbosch University. Faculty of AgriSciences. Dept. of Animal Science.
    ENGLISH ABSTRACT: The digestive tract of ruminants follows the order of rumen, reticulum, omasum and abomasum, where at least 50 % or more of the total digestion of feed intake occurs. Digestion of protein is a broad spectrum explained by the nitrogen metabolism pathways of any ruminant; dietary protein consumed by a ruminant can split into rumen-degradable and undegradable protein. The rumen itself produces protein for use, in the form of ammonia nitrogen, endogenous nitrogen and microbial protein. Thus, when rumen degradable protein is found to be in excess, the protein will be lost through urine, as urea will be metabolized in the liver. The loss of protein or nitrogen due to excess ammonia can thus be an extreme expenditure and methods to minimize the loss and the cost of feeding protein are greatly researched. These losses whether it be for maintenance or production purposes in ruminants can be compensated or overcome if methods are used to increase the undegradable proteins. Meaning one can reduce the feeding of protein to improve production without diminishing the protein needs of the animal. Methods of protecting feedstuff have shown results to increase rumen undegradable proteins (RUP) for example encapsulation, extrusion, or formaldehyde treatment of feeds. These methods of protecting proteins or increasing the availability thereof still have to be modified into the diet itself, thus extra cost put in processing the feed to achieve this increased availability of RUP. The aim of this study will be to manipulate the rumen fermentation, ruminal pH and/or microbes to provide potentially improved protein availability for use to the animal, without the modification of the feed. The inclusion of tannins (Farmatan D®- 0 %, 0.25 %, 0.5 %, 0.75 %, 1 %), lipids (plant oil extracts- 0 %, 1.25, 2.5 %, 3.75 %, 5 %) and sodium bicarbonate (sodium bicarbonate- 0 %, 0.75 %, 1.5 %, 2.25 %, 3.0 %) were incorporated into the diet for five cannulated sheep, each receiving its own inclusion. Tannins in the past were only to be seen as detrimental to the animal, but with further studies have shown it involves the type of tannins used namely condensed tannins that has this effect. The other type of tannins, which are hydrolysable, have been shown to decrease urinary nitrogen loss and have abilities to manipulate the rumen and bind to microbial protein that can lead to greater availability of protein for use. The inclusion of lipids, especially higher inclusion thereof has led to fibre coating in the rumen, which resulted in a manipulation of the rumen itself, potentially increasing the RUP. Lastly the inclusion of the sodium bicarbonate was incorporated into the diet, with emphasis on a high grain diet to decrease the pH of the rumen to gain greater results when used. The inclusion of sodium bicarbonate increased the pH with the increasing inclusions in the diet. The high grain fed diet with each respective inclusion, was used to determine (using in vitro) the potential protein degradation and fractional rate of digestion due to the manipulation of the rumen. The optimum inclusion for tannins, lipids and sodium bicarbonate were determined, after each in vitro study was completed. This study will be especially beneficial for further research of the tannins used and determining the RUP available after in vitro trials. The inclusion of all three these supplementations to the diet manipulated did not show desired results in the manipulation of the rumen degradation. Even with the maximum inclusion of Farmatan D® and lipids in the diet, as theorized could lead to great protein availability, did not occur. Whereas the maximum inclusion of sodium bicarbonate did not have optimum availability of proteins, and did not show any significant results. This was determined by using in vitro methods for protein degradation and fractional rate of digestion for all the respective inclusion levels of the three supplementations, did not lead to rumen degradation.