Digestive Tract Of Ruminants Research Articles

Measurement of feed intake of grazing sheep: I. Rate of passage of inert reference materials through the ruminant digestive tract

Experiments are described which give some basic information on the rate and pattern of marker excretion by sheep on pastures ranging in digestibility from 70 to 80% and on hay of barely 50% digestibility.The faeces output of individual sheep varied from 100 g. to more than 400 g. daily, and the estimated feed intake from below 400 to over 1,900 g. daily.Despite these wide ranges a typical pattern for the passage of single doses of markers was quite consistently repeated in the trials on pastures:1. Markers first appeared in the faeces 5–8 hr. after dosing.2. Concentrations rose rapidly to peak values about 10–18 hr. after dosing.3. Concentrations fell thereafter by about 50% each 6–10 hr. until 60–70 hr. after dosing when marker content could no longer reliably be determined by the methods used.Factors affecting the basic pattern1. The overall quality of the feed was of prime importance, in that peak concentrations occurred progressively later on poorer pastures and on hay.2. For any given feed a high level of (estimated) feed intake was often associated with earlier appearance of marker in the faeces, an earlier peak of concentration, and slightly faster fall in marker concentration.3. There was evidence that the time of administration might slightly affect rate of passage, presumably through its relation to grazing periods, for doses given at or near times of greatest feed intake were passed rather more rapidly.4. It did not appear that there was any considerable retention of either marker within the tract beyond 72–96 hr. after dosing.

Studies on the Composition of Lignin Isolated from Orchard Grass Hay Cut at Four Stages of Maturity and from the Corresponding Feces

Lignin has been reported by a number of workers to be indigestible (7, 9, 13, 14, 16, 17, 20, 39). Other reports indicate that varying amounts of lignin may be digested or broken down in the ruminant digestive tract (4, 8, 10, 11, 18, 22, 23, 28). Since the chemical structure of lignin has not been established, it is not feasible to isolate or determine a product of uniform composition from different materials. Certain characteristics of crude lignin preparations vary considerably, depending upon the material from which it is isolated and the method used for its isolation. Extensive studies have been made of the characteristics of lignin isolated from various woods, but only limited studies have been reported on lignin prepared from forage plants important in animal feeding. Phillips et al. (34) found 4.34 per cent nitrogen in the lignin obtained from oat plants 7 days old, which decreased to 1.26 per cent nitrogen in the lignin from plants 84 days old. Bondi and Meyer (4) reported from 1.18 to 1.63 per cent nitrogen in the lignin from four grass species and from 2.92 to 3.36 per cent nitrogen in the lignin from four legumes. The lignin isolated from the corresponding feces had slightly higher nitrogen contents. They also showed that the lignin nitrogen was resistant to hydrolysis by strong acid (5 h r H2S04), by weak acid (0.5 N HC1), and by pepsin added to the weak acid. These results led these investigators to conclude that the nitrogen in crude lignin preparations was not present as protein nitrogen. Furthermore, the digestive enzymes of the ruminant did not reduce the nitrogen content of the lignin. Norman and Jenkins (26) believed that protein degradation products following the treatment of plant material with strong acid resulted in high lignin yields rather than protein per se. Paloheimo (27), Waksman and Stevens (41), Phillips (29), and DeMan and DeHeus (12) have corrected crude lignin values by deducting the nitrogen content multiplied by the factor 6.25. Phillips (30) later felt that, because there was not a constant relation between the amount of protein added to samples for the determination of lignin and the size of the error involved, the apparent lignin values should not be corrected but the per cent of nitrogen in the lignin should be reported. Thomas and Armstrong (40) found amino acids in the hydrolysates from crude lignin and proposed that the factor 6.25 for converting lignin nitrogen to protein was valid. DeMan and DcHeus (12) found the tyz'osine and the tryptophane nitrogen in the lignin isolated from Lolium perenne was in agree-

The rate of passage of food in the digestive tract of ruminants

Kirjallisuudessa tavataan lukuisasti mainintoja, jotka ilmoittavat pitkäkö aika kuluu tietyn aterian alkamisesta syödyn rehun ensimmäisten sulamattomien osasten erittymiseen sonnassa, sekä kauanko kestää ennen kuin viimeisetkin osaset ovat poistuneet ruoansulatuskanavasta. Tällaiset tiedot antavat kuitenkin vain kovin puutteellisen kuvan ravinnon tähteiden kulkunopeudesta ruoansulatuskanavassa. Eräät tutkijat, esim. Poijärvi ja Balch ovat esittäneet ns. erityskäyriä tai niitä vastaavia lukusarjoja. Tämän tiedonannon kirjoittajat ovat kehittäneet laskutavan, jolla voidaan erityskäyrien perusteella arvioida sulamattoman rehupisteen keskimääräinen viipymisaika ruoansulatuskanavassa. Omat tutkimuksemme ovat suoritetut teuraiksi määrätyillä ruoansulatuksellisesti terveillä lehmillä, joita on 10 viimeisen elinpäivän ajan ruokittu määräaikaisesti määräsuuruisilla heinäannoksilla. Teurastuksen yhteydessä suoritetuilla ruoansulatuskanavan sisällykseen kohdistetuilla tutkimuksilla on hankittu tietoja, joiden avulla on sitten voitu laskea rehun kuiva-ainepisteen keskimääräinen viipymisaika pötsissä sekä ligninipisteen (mikä edustaa rehun sulamatonta osaa) viipymisaika pötsissä ja ruoansulatuskanavassa kokonaisuudessaan. Myös on laskettu typpi- ja ligninivapaan kuiva-ainepisteen keskimääräinen viipymisaika pötsissä. Esimerkkinä on tiedonannossamme esitetty tulokset neljän koelehmän kohdalta taulukossa 2. Ensimmäisessä numerosarakkeessa ilmoitetaan lehmien päivittäin syömä kuiva-ainemäärä (kg), toisessa kuiva-ainepisteen keskim. viipymisaika pötsissä (vrk), kolmannessa ligninipisteen keskim. viipymisaika pötsissä, neljännessä typpi- ja ligninivapaan kuiva-ainepisteen keskim. viipymisaika pötsissä ja viidennessä ligninipisteen keskimääräinen viipymisaika ruoansulatuskanavassa. Vertauksen vuoksi esitetään taulukossa 3 eräitä laskelmia, jotka kirjoittajat ovat suorittaneet Poijärven pässeillä suorittamien kokeiden antamien tulosten perusteella: Toisessa sarakkeessa esitetään pässien päivittäinen ruokinta (hay = heinä, wheat bran = vehnän lese), kolmannessa johtoaineena käytetyn rehuun sekoitetun kromioksiidin keskimääräinen viipymisaika (vrk) ruoansulatuskanavassa. Balchin suorittamien kokeiden perusteella on suoritettu samankaltaisia laskelmia. Yhdistetyn heinä-väkirehuannoksen sulamattomien tähteiden keskim. viipymisajaksi saatiin 2.2 vrk. ja sulamattomien väkirehutähteiden 1.5 vrk.

Built-Up Floor Litter a Source of Dietary Factors Essential for Hatchability of Chicken Eggs

EXPERIMENTAL evidence has been accumulating during the past 30 years to establish the fact that essential dietary factors are synthesized in the digestive tract of ruminants. A review of this literature was made by Hammond (1942). Only recently, however, have the fundamental principles with reference to the synthesis of vitamins and vitamin-like factors within the digestive tract or after the contents are voided been applied to chickens.Lamoreux and Schumacher (1940) found feces from laying hens contained no more riboflavin at time of defecation than was present in the feed from which they were produced. An approximate increase, however, of 100 percent in the riboflavin content of the feces occurred when they were held at room temperature for 24 hours and a 300 percent or more increase when they were held for 1 week. Schumacher and Heuser (1940) attempted to determine what factor might be responsible for the increased riboflavin .

Rumen Digestion Studies: II. Studies in the Chemistry of Rumen Digestion

Studies of the chemical changes in the rumen suggest the following salient features regarding the fate of roughage in the ruminant digestive tract: During the first 6 hours after feeding the predominant phenomenon was the rapid digestion of proteins and carbohydrates. Decomposition of cellulose began during this period but was not extensive. The predominant phenomenon during the second 6 hours was the rapid disintegration of cellulose. Digestion of proteins and carbohydrates in this period paralleled the digestion of cellulose. Although small amounts of lignin may be attacked in the rumen, functionally the rumen is not a factor in lignin digestion. Rumen digestion was observed to come to a standstill within 12 hours after feeding. Prolonging the digestion periods to 24 hours did not increase rumen digestion coefficients. Lignin apparently protects plant fragments from further action by rumen microflora. Average rumen digestion coefficients for 8 trials at 12–14 hours after feeding were: dry matter 48.4, protein 59.6, nitrogen-free extract 65.2, crude fiber 27.2, cellulose 43.4, other carbohydrates 83.0 and lignin 3.1%. After plant fragments pass from the rumen variable amounts of lignin may be digested, thereby exposing varying amounts of cellulose and protein to further digestion. Fecal digestion was observed to be quite variable even though rumen digestion of the same lots of hay was very constant. The caecum plays only a supplementary role in the disintegration of roughage within the ruminant organism. An average of 11.6% of the cellulose and possibly 9.5% protein was observed to be digested in the caecum. The production of fatty acids in the rumen was demonstrated. Maximum increases, after the increase due to digestion was eliminated, were 54.9% on an alfalfa hay ration and 281.7% on a beet pulp ration. The rapid dissipation of fatty acids from the rumen together with the marked increases noted suggests that fatty acids may make a highly significant contribution to the nutrition of the ruminant either as an intermediate or end product of digestion.

Cow Manure as a Source of Certain Vitamins for Growing Chickens

THEILER, Green, and Viljoen (1915) were the first to suggest that what was then known as vitamin B might be synthesized by the flora in the digestive tract of cattle. Scheunert and Schieblich (1923) were able to show that B. vulgatus, an organism found in the digestive tract of ruminants, synthesizes vitamin B. Bechdel, Honeywell, Dutcher, and Knutsen (1928) demonstrated that the synthesis of vitamin B took place in the rumen. More recently McElroy and Goss have made quantitative studies of the riboflavin and vitamin K (1940a), pyridoxine (1940b), thiamin (1941a), and pantothenic acid (1941b) synthesized in the rumen of sheep and cows fed diets of low vitamin content. Hunt, Kick, Burroughs, Bethke, Schalk, and Gerlaugh (1941) found that thiamin and riboflavin were synthesized in the rumens of steers fed corn, alfalfa hay, and a protein supplement. Wegner, Booth, Elvehjem, and Hart (1941) investigated the synthesis of thiamin, riboflavin, pyridoxine, .