Das Determinationsproblem

The Application of Microbiological Methods to the Study of Nutrition

“…It is the power the rumen bacteria have of producing lower fatty acids by fermentation of carbohydrates, including cellulose. This process occurs also to a small extent in the stomach of the horse, owing to inefficient mixing of food (Mangold, 1929). The production of lower fatty acids by rumen micro-organisms is no new discovery (Mangold, 1929)' but only as a result of recent work at Cambridge (McAnally and Phillipson, 1944;Elsden, 1945) has the quantitative importance of the production of fatty acids in the rumen been fully realized.…”

“…This process occurs also to a small extent in the stomach of the horse, owing to inefficient mixing of food (Mangold, 1929). The production of lower fatty acids by rumen micro-organisms is no new discovery (Mangold, 1929)' but only as a result of recent work at Cambridge (McAnally and Phillipson, 1944;Elsden, 1945) has the quantitative importance of the production of fatty acids in the rumen been fully realized. Further, Phillipson and McAnally (1942) have made the important discovery that organic acids produced in the rumen are directly absorbed through its walls into the portal circulation.…”

“…Birds generally do not make use of cellulose, presumably because a heavy gut would be incompatible with flight. According to Mangold (1929), the bird relies more on mechanical than on chemical means to disrupt the cell walls of plant tissues. He regards the crop mainly as a storage organ necessitated by the bottleneck at the gizzard.…”

“…After maceration in the crop the food is mixed with pepsin and hydrochloric acid in the proventriculus before being efficiently ground in the gizzard. Nevertheless, some breakdown of cellulose does occur in the hen, and experiments described by Mangold (1929) show that the site of such breakdown is the paired caeca which in many birds are long, if not capacious, organs. Generally speaking, the more vegetarian the diet, the longer and more complicated are the caeca and the larger the large intestine.…”

“…Further indirect evidence of cellulose digestion was adduced by Roeseler (1929), who showed that caecal faeces contained much less crude fibre than non-caecal ones. Mangold (1929) quotes many estimates of the hen's power to digest cellulose. They vary widely and there is no point in quoting them, because important items, such as the percentage of cellulose in the whole diet and the duration of the period of feeding, are not given and, on analogy with the ruminant, both these factors would considerably affect a symbiotic microflora.…”