Date of Award:

1993

Document Type:

Dissertation

Degree Name:

Doctor of Philosophy (PhD)

Department:

Animal, Dairy, and Veterinary Sciences

Advisor/Chair:

Michael J. Arambel

Abstract

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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