The effect of free and protected oils on the digestion of dietary carbohydrates between the mouth and duodenum of sheep

Abstract

1. Sheep fitted with rumen and re-entrant duodenal cannulas were given diets of approximately 200 g hay and 400 g concentrate mixture alone, or supplemented daily with 40 g linseed or coconut oils free or protected with formaldehyde-casein in a 5 x 5 Latin-square arrangement. Chromic oxide paper was given as a marker at feeding time and passage to the duodenum of neutral-detergent fibre (NDF) and different sugars were estimated from the values for c0nstituent:marker at the duodenum. Contributions of microbial carbohydrates to these flows were estimated from amounts of RNA present.2. The carbohydrate composition of mixed rumen bacteria from sheep rumen digesta were similar regardless of diet. Of the sugars entering the duodenum all the rhamnose and ribose and 0.51,0.24 and 0.35 of the mannose, galactose and starch-glucose respectively, were contributed by the microbes. Virtually all the arabinose, xylose and cellulose-glucose were contributed by the diet.3. For sheep receiving the basal ration, coefficients of digestibility between mouth and duodenum, corrected where necessary for microbial contribution, were 095,0.66,0.67,0.62,0.45 and 0.51 for starch-glucose, mannose, arabinose, galactose, xylose and cellulose-glucose respectively. Corresponding values when free-oil-supplemented diets were given were 0.95,035,0.38,0.55,0.01 and -0.02 respectively. Values for diets supplemented with linseed oil or coconut oil did not differ significantly. Addition of protected oils to the basal feed also resulted in depressed digestibilities of dietary structural sugars but to a far lesser extent than those observed with the free oils.4. Apparent digestibility of NDF was altered in the same direction as those of the main structural sugars, averaging 0.50,O. 17 and 0.29 in animals receiving the basal, free-oil-supplemented or protected-oil-supplemented diets respectively. The reasons for the difference between NDF and discrete carbohydrate analytical totals are discussed.

Methane suppression by coconut oil and associated effects on nutrient and energy balance in sheep

“…However, in the present study the daily average intake of myristic acid was lower (6 and 9 g using 3.5 and 7% coconut oil, respectively) than in the study of Steele and Moore (1968). In the study of McAllan et al (1983), 40 g d -1 coconut oil fed to sheep almost completely inhibited the ruminal digestion of both hemicellulose and cellulose. When supplementing 40 g coconut oil per sheep per day, found a 76% reduction in digestion of NDF in the forestomach and about 30% reduction in total tract.…”

Efeito da suplementação de lipídios sobre a digestibilidade e os parâmetros da fermentação ruminal em cabras leiteiras

“…Os métodos de proteção da gordura incluem a encapsulação por proteína tratada com formaldeído (McAllan et al, 1983), a hidrogenação das gorduras e a produção de sabões de cálcio (Jenkins & Palmquist, 1982). Os sabões de cálcio são degradados no rúmen em pequena proporção e, após hidrólise no abomaso, seus ácidos graxos podem ser absorvidos, reduzindo os efeitos negativos sobre a fermentação ruminal (Gonzalez et al, 1998).…”

Effect of fish oil and monensin on milk composition in dairy cows

“…Since the former theory would require a general inhibition of fibre digestibility to be observed, the study of McAllan et al (1983), in which ruminal digestion coefficients of different structural sugars were not affected equally by dietary oils, favours the idea of direct bactericidal effects. The adsorption of fatty acids to gram-positive bacterial cells uncouples respiration (Galbraith and Miller 1973b) and causes lysis (Galbraith and Miller 1973a), unsaturated fatty acids being more detrimental than their saturated counterparts (Galbraith et al 1971;Maczulak et al 1981).…”

“…Added fat in a dairy ration has previously been shown to significantly reduce milk fat percentage (Nicholson and Sutton 1971;Brumby et al 1972;Storry et al 1974) and, although a decrease in milk protein percentage often accompanies the feeding of dietary lipid, protein yields are frequently improved (Sutton 1989;Coppock and Wilks 1991;DePeters and Cant 1992). Fish oil is a locally available fat supplement and is an excellent source of the n-3 fatty acids, eicosapentaenoic acid (EPA; C 20:5 (n-3) and docosahexaenoic acid (DHA; C 22:6 (n-3) .…”