Rumen protected methionine has been used in an effort to improve the amino acid composition of metabolisable protein since the early 1960’s. The positive response in dairy cows in terms of milk protein composition and milk production, especially during early lactation has been well documented. Rumen protected methionine supplementation contributes to improving the protein efficiency of the dairy cow which improves the overall productivity of the dairy enterprise. Recently a locally developed liquid rumen protected methionine prototype became available. In our study this product was evaluated through a series of experiments in conjunction with two standard, well known methionnine sources, Smartamine ™ M and unprotected DL-methionine that provided a reference to the relative bioavailability of the liquid rumen protected methionine. In the first of the two studies the effect of methionine supplementation on milk yield, milk composition as well as milk protein composition was evaluated through the milk composition technique. The ability of the liquid rumen protected methionine to elevate blood plasma methionine levels was also evaluated through the blood plasma technique after oral dosing and post ruminal infusion of methionine. The liquid rumen protected methionine prototype induced no response in either milk yield or milk composition. Results suggested that the prototype is either not adequately protected against rumen degradation or it is not available for absorption in the small intestine. The inability of the liquid rumen protected methionine prototype to elevate blood plasma methionine after post ruminal infusion further proved that the product is not available for absorption at this site either. In the event that the product’s mode of action or method of protection caused it not to be detected as pure methionine in the blood, an effect on milk yield would have been expected which was not the case. This product proved to have a very low or no bioavailability in comparison to the well researched and proven Smartamine ™ M. / Dissertation (MSc(Agric))--University of Pretoria, 2012. / Animal and Wildlife Sciences / unrestricted

Six nonlactating Holstein cows fitted with rumen and duodenal cannula were used to determine the efficacy of pH sensitive fatty acid polymer encapsulation as a means protecting amino acids from rumen fermentation and as a post-ruminal amino acid delivery system. The cows were arranged in a 2 x 2 factorial in a latin square design. Treatments were 1) the basal ration, and 2) basal ration plus rumen-protected lysine, methionine, and threonine at 10 g each per day. Rumen parameters measured were pH, ammonia, volatile fatty acids, protozoa, liquid, and dry matter rate of passage, total viable bacteria, and viable cellulolytic bacteria. Duodenal parameters measured were crude protein, ammonia, and amino acid concentrations. Total tract apparent digestibility of nutrients was measured. In addition, rumen degradation of the three amino acid products was measured by loss from nylon bags, in the rumen. Loss of product from nylon bags suggested the lysine and threonine products had no significant rumen protection, but that the methionine product had > 50% protection at 12 h in the rumen. None of the rumen parameters measured differed (P>.05) due to treatment. Duodenal crude protein and ammonia concentrations did not differ due to treatment. Duodenal amino acid concentrations were numerically higher for the amino acid supplemented treatment, but the differences were nonsignificant and thought to be confounded by failure of the lysine and threonine products. Total tract apparent nutrient digestibility was not affected by treatment. A second experiment was conducted using 40 post-parturient Holstein cows, and different rumen-protected amino acid products from the first trial. Cows were nesteMwby treatment (control vs rumen-protected methionine 46 g and lysine 22 g) and parity (primiparous vs multiparous). Dry matter intake and milk production were monitored daily, body weight weekly, and milk composition bi-weekly. Total tract apparent nutrient digestibility was measured during the last week of the 10-week trial. There was no significant (P<.05) effect of supplemental rumen-protected lysine and methionine among primiparous animals. Multiparous animals receiving supplemental amino acids had lower dry matter intakes and yield of milk components than control animals.

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To better understand the facets of nutrient utilization, a series of in vivo and in vitro studies were undertaken to elucidate the effect of supplementation on utilization of moderate-quality bermudagrass hay and to identify mechanisms to evaluate the role of rumen bacterial populations on feedstuff utilization. A digestion trial was conducted using 6 ruminally cannulated steers receiving bermudagrass hay supplemented with soybean hulls (HULLS), cracked corn (CORN), or soybean hulls and cracked corn (MIX; 75% and 25%, respectively) in a 3x3 Latin Rectangle arrangement. Additionally, ruminal fluid was continuously cultured using the BioFlo® 110 fermentation system to evaluate the in vitro fermentive parameters of ground moderate-quality bermudagrass hay either alone (HAY; 20 g DM L-1 d-1) or supplemented (7 g DM L-1 d-1) with corn (CORN), soybean hulls (SBH), or both (25:75; MIX) in a randomized complete block. Genomic DNA from continuous culture as well as from pure bacterial culture samples were sought to differentially enumerate select bacterial strains via real-time PCR using specie-specific DNA primers. The information is to be used for elucidating responses in ruminal digestibility of varying feed-types. Finally, as an alternative to PCR, bioluminescence of transformed Escherichia coli was evaluated by measuring extent of photonic emission with and without antibiotic selection over time. Evaluations were also made of photonic emission by E. coli grown in ruminal fluid with and without additional feed particles. Data seem to indicate that replacing a portion of corn with soybean hulls may successfully improved fiber digestion and improved ruminal N-utilization. Real-time PCR shows potential for evaluating ruminal bacteria where as biophotonics may need further modification before meaningful in situ evaluations of live ruminants can be employed.

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The present report describes a procedure developed for tracing C¹⁴ labeled glucose in rumen material in vitro. Twenty-five ml. samples of rumen fluid were incubated with uniformly labeled glucose for 1 1/2 hours in a closed system. The distribution of activity in both unfermented control samples and fermented samples was determined among protein and particulate material, ether extractable substances, amino acids and peptides, sugars and other neutral molecules, carbon dioxide, and methane. Samples were counted as barium carbonate following wet oxidation. Subsamples of the control and fermented samples indicated 80 to 85% recovery of C¹⁴. In these preliminary trials, additional losses were encountered among some individual fractions. Data indicated differences between fermentative activity of the two samples from different animals. In Trial I, 29% of 14 the fermented glucose C¹⁴ was recovered in the protein-particulate fraction, 15.6% in the carbon dioxide, and 10.5% in the ether extract. In Trial II, the ether extractable fraction contained 23.5% of the activity, 14.5% was recovered in the protein-particulate fraction, and 14.3% in the carbon dioxide. / M.S.

Dried rumen microblota were isolated from fistulated steers. Proximate analyses were conducted and the amino acid composition and B-vitamin content were determined. Protein quality tests were carried out using the Bender-Miller method. The data obtained from the investigation indicated that the protein quality of dried rumen microbiota is comparable with that of dried defatted egg, dried milk, fish meal and meat meal, but it is better than that of a soy protein and wheat gluten. No amino acid deficiency appeared in the feeding trials even though the amino acid composition showed that the dried rumen microbiota might be deficient in sulfur-containing amino acids. / Master of Science