Nitrogen Metabolism in Lambs Fed Lipid-Coated Protein

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Abstract
Linseed meal was coated with corn oil, lard or coconut oil and fed to 20 crossbred lambs in a digestion and nitrogen balance trial. The control diet was supplemented with normal linseed meal. The effectiveness of coating the protein in linseed meal was studied in relation to reducing ruminal degradation of protein and incresing nitrogen retention in lambs. Lipid coating increased the ether extract composition and the gross energy content of the treated diets. Energy digestibilities were similar with normal linseed meal, corn oil- and lard-coated linseed meal diets. Therefore, treatment of linseed meal with corn oil or lard increased energy availability to the animal by 5 and 14%, respectively, over the normal linseed meal diet. The average ruminal ammonia level across all collection times for lamb consuming coconut oil-coated linseed meal was 2.7 mg/100 ml, which was significantly lower (P<.05) than all other treatment means. Ruminal ammonia concentrations for corn oil- and lard-coated linseed meal diets (7.3 mg/100 ml and 9.0 mg/100 ml, respectively) were lower (P<.05) than for the normal linseed meal diet (15.6 mg/100 ml), but higher than the coconut oil-coated meal diet. Plasma urea and blood ammonia levels differed little among treatments. Digestibilities of dry matter and cellulose were lowest when coconut oil-coated linseed meal was fed. Nitrogen digestibility was lowest (P<.05) for the coconut oil treatment, while nitrogen retained was the lowest of the three treated diets indicating that coconut oil treatment of linseed meal reduced post-ruminal degradation. Nitrogen retained was significantly higher for the corn oil treatment than for the normal linseed meal diet. Molar percentages of plasma essential amino acids, except isoleucine, leucine and threonine tended to increase progressively from feeding the normal, corn oil-, lard- and coconut oil-coated meals. Tyrosine and cystine levels increased similarly. Conversely, nonessential amino acids decreased in the same manner except for glycine. Copyright © 1977. American Society of Animal Science . Copyright 1977 by American Society of Animal Science.