Pötsissä tapahtuvan rehuvalkuaisen hajoavuuden määrittäminen nailonpussi-menetelmällä

The investigation included experiments in which factors affecting the reliability of the nylon bag method were studied. The possibility of applying the feed protein degradabilities to practical feeding conditions was also examined. In the experiments concerning reliability, such factors as bag porosity, sample weight, sample treatment, washing procedure, diets, and differences between animals and incubation days were studied. The feed protein degradabilities were also determined by using as incubation periods the ruminal retention times for particulate matter of different feeds, evaluated as a function of DM intake/100 kg liveweight in different diets. A nylon bag, with a pore size of 40 µm and internal dimensions of 6 X 12 cm was selected for the degradability determinations. The sample weight used in incubations was 57 —60  mg DM/cm2. In the determination of feed protein degradability, when sheep are used as experimental animals, it is recommended that for routine determinations only one animal be used, analyzing the contents of two bags for each incubation period during two successive days. A control sample of which degradability is determined in advance in many sheep, should be used in all incubations in order to control the digestive processes in the rumen of the experimental sheep. The actual degradabilities analyzed by the bag method are applicable in practise, if they are determined using animals at similar feeding levels and on diets similar to those prevailing under the conditions in which the degradabilities are going to be used.Nailonpussi-menetelmässä tutkittavaa rehua inkuboidaan eläimen pötsissä erikoisvalmisteisissa pusseissa. Pussit valmistetaan kankaasta, jota pötsimikrobit eivät pysty hajottamaan (esim. keinokuitukangas) ja jonka huokoskoko mahdollistaa mikrobien vapaan liikkumisen pussin sisään. Rehun sulavuus pötsissä lasketaan erotuksena, joka saadaan vähentämällä pussiin pannusta rehumäärästä inkubaation jälkeen pussissa ollut rehumäärä. Ennen tarvittavia määrityksiä pussi rehujäännöksineen pestään inkubaation jälkeen juoksevalla vedellä, jotta pussiin tullut pötsin sisältö saataisiin poistetuksi pussista. Rehun sulavuus lasketaan rehun ja rehujäännöksen kuiva-ainemäärän erotuksen perusteella. Raakavalkuaisen hajoavuusmäärityksessä erotuslaskelmia varten rehun ja rehujäännöksen raakavalkuaispitoisuus analysoidaan myös prosentteina rehun ja rehujäännöksen kuiva-aineesta. Tässä tutkimuksessa selvitettiin tekijöitä, jotka vaikuttavat nailonpussi-menetelmällä rehuvalkuaisen hajoavuudelle saatujen tulosten luotettavuuteen rajoituksia, joiden mukaan rehuvalkuaisen hajoavuudelle saatuja tuloksia voidaan soveltaa käytännössä vaihteleviin ruokintaolosuhteisiin Tutkimuksessa selvitettiin pussikankaan huokoskoon, näytteenkoon ja näytteen esikäsittelyn vaikutusta nailonpussi-menetelmällä rehunkuiva-aineen, orgaanisen aineen ja raakavalkuaisen hajoavuusasteelle saatuihin tuloksiin. Lisäksi tarkasteltiin yksittäisten pussien, koe-eläinten ja inkubointipäivien merkitystä vaihtelu lähteinä rehujen kuiva-aineen ja raakavalkuaisen hajoavuusmäärityksissä. Eriruokinnoista tarkasteltiin korsirehu: väkirehu -suhteen sekä säilörehun tai heinän eri kasvuasteiden vaikutusta rehujen hajoavuuteen pötsissä. Kaikki tutkimukset suoritettiin pötsifistelöidyillä lampailla ja inkuboitavina rehuina käytettiin pääasiassa heinää, kauranolkea, säilörehua, ohraa, soijarouhetta ja rypsirouhetta. Laboratorio (in vitro)- ja eläinkokeiden(in vivo) perusteella pussin materiaaliksi valittiin 40 µm:n polyesterkangas (PES 40/27, Franz Eckert Cie, West Germany),jonka huokoset olivat samansuuruisia eivätkä pötsin käymistapahtumat vaikuttaneet kankaan rakenteeseen. Inkuboitavan rehunäytteen suuruudeksi suhteessa kankaan pinta-alaan valittiin 57—60 mg näytteen kuiva-ainetta/cm2, kun nailonpussin sisämitat inkubaation aikana olivat 6 X 12 cm. Inkubointia varten tuoreet (ei kuivattu vakuumissa) näytteet heinästä, oljesta, viljaväkirehusta sekä rouheesta esikäsiteltiin jauhamalla näyte 1.5 mm:n Ø seulan läpi. Säilörehu silputtiin saksilla siten, että näytteen partikkelikoko oli alle 0.5cm. Koe-eläinten väliset erot olivat suurempia kuin inkubointipäivien väliset erot määritettäessä rehujen hajoavuutta pötsissä. Rehun sulavuus tietyllä aikavälillä voidaan määrittää riittävällä varmuudella inkuboimalla yhdellä lampaalla kahtena peräkkäisenä päivänä rehusta kaksi rinnakkaisnäytettä (pussia)/inkubaatioaika. Käytetyissä aineistoissa vaihtelukertoimet kuiva-aineen ja raakavalkuaisen hajoavuustuloksille olivat tällöin vastaavasti 0.6—5.5 ja 1.3—3.0 %. Säilörehu- ja heinäruokinnalla eri kasvuasteiden välillä todettiin tilastollisestimerkitseviä eroja soija- ja rypsirouheen kuiva-aineen ja raakavalkuaisen pötsihajoavuudessa. Väkirehun osuuden lisääminen 60—70 prosenttiin rehuannoksen kuiva-aineessa vähensi ennen kaikkea rypsirouheen raakavalkuaisen hajoamista pötsissä, kun vertailuruokinnoissa väkirehun osuus vaihteli 0—40 prosenttiin kuiva-aineessa. Tulosten perusteella rehun raakavalkuaisen hajoavuus pötsissä tulisi määrittää aina niissä ruokintaolosuhteissa, joihin tuloksia sovelletaan käytännössä. Rehuannoksen koostumuksen lisäksi ruokinnan voimakkuus vaikuttaa rehujen sulavuuteen pötsissä siten, että ruokintatason (kg ka/100 elopaino-kg) noustessa rehun viipymisaika pötsissä lyhenee mikä vähentää rehun kuiva-aineen ja raakavalkuaisen hajoamista pötsissä. Ruokinnan voimakkuus voidaan ottaa huomioon laskemalla inkubaatioajan pituus seuraavasti (X = kg ka/100 elopaino-kg, y = inkubaatioaika, d): (1) säilörehu ja heinä, vain korsirehua ruokinnassa y = -1.861 log X 4+ 1.60 (2) säilörehu ja heinä, ruokinnassa korsirehua ja väkirehua y = -1.574log X + 2.53 (3) väkirehu, ruokinta kuten kohdassa (2) y1 = —0.374 log X + 0.64 (korsirehu : väkirehu = 70:30 kuiva-aineen perusteella laskettuna) y2= —0.437 log X + 0.62 (korsirehu : väkirehu = 50:50 kuiva-aineen perusteella laskettuna

The nylon bag technique in the determination of ruminal feed protein degradation

The investigation included experiments in which factors affecting the reliability of the nylon bag method were studied. The possibility of applying the feed protein degradabilities to practical feeding conditions was also examined. In the experiments concerning reliability, such factors as bag porosity, sample weight, sample treatment, washing procedure, diets, and differences between animals and incubation days were studied. The feed protein degradabilities were also determined by using as incubation periods the ruminal retention times for particulate matter of different feeds, evaluated as a function of DM intake/100 kg liveweight in different diets. A nylon bag, with a pore size of 40 µm and internal dimensions of 6 X 12 cm was selected for the degradability determinations. The sample weight used in incubations was 57 —60  mg DM/cm2. In the determination of feed protein degradability, when sheep are used as experimental animals, it is recommended that for routine determinations only one animal be used, analyzing the contents of two bags for each incubation period during two successive days. A control sample of which degradability is determined in advance in many sheep, should be used in all incubations in order to control the digestive processes in the rumen of the experimental sheep. The actual degradabilities analyzed by the bag method are applicable in practise, if they are determined using animals at similar feeding levels and on diets similar to those prevailing under the conditions in which the degradabilities are going to be used

Effect of formaldehyde-treated urea on rumen fermentation, ration digestibility and nitrogen utilization

The study comprises two experiments in which young Finn-sheep were used as test animals. The experimental rations consisted of equal parts of NaOH-treated wheat (Exp. 1) or barley (Exp. 2) straw and a concentrate mixture of barley-molassed beet pulp (Exp. 1) or barley-oats-molassed beet pulp (Exp.2). Feeding was performed twice a day. In addition 20 grams of urea/animal/day was mixed into the concentrates just before feeding. The urea was treated with the following percentages of formaldehyde, on a weight basis: 0 (F0), 1.0 (F1.0), 3.0(F3.0) and 5.0(F5.0) in Exp. 1 and 0, 1.0 and 1.5(F1.5) in Exp. 2. The digestibility of the total ration decreased, when F3.0 and F5.0 urea was used, but the decrease was significant (P< 0.05) only when the apparent digestibility of crude protein was compared between the F0 and F5.0 diets. The amount of rumen bacteria was decreased (P< 0.05) and the amount of protozoa increased (P< 0.01) by formaldehyde treatment levels above F1.0 and F3.0, respectively. The concentration of the total VFA in the rumen tended to decrease with treatment levels higher than F3.0. No significant differences were found in the composition of the VFA. When treated urea was used, the excretion of nitrogen in the faeces increased but its excretion in the urine decreased. The percentage retention of the nitrogen ingested by the animals on diets F0, F1.0, F3.0, and F5.0 in Exp. 1 was 15.0, 10.8, 13.2 and 12.2 and on diets F0, F1.0 and F1.5 in Exp. 2 it was 20.5, 20.2 and 21.2, respectively

Formaldehyde content of milk: 2.Cows fed on grass silage preserved with formaldehyde-containing additive and on formaldehyde-treated urea

In two different experiments silages prepared with formaldehyde-containing additives were fed to cows with and without formaldehyde-treated urea, and formaldehyde was determined on both the silage and the milk. The silage additive contained 20 % HCHO and 30 % 80-% acetic acid and it was used at the rate of 5 l/ton raw material. The treatment levels of urea were 1.4-1.5 g HCHO/100 g urea. Twenty-two Friesian cows were used in Experiment 1 and 20 Ayrshire cows in Experiment 2. In Both experiments they were divided into two groups, one of which had silage as the only source of formaldehyde and the other both silage and HCHO-treated urea. Exp. 1 lasted 18 weeks and Exp. 2 13 weeks. The average daily milk yield in Exp. 1 was 14.2kg and in Exp. 2 it was 22.8kg FCM. When the experiments started at least 4monthshadelapsed from the preparation of the silages. In Exp. 1 the silage contained on average 13.0 mg HCHO/kg (10-16 mg/kg, n = 5) and in Exp. 2 it contained 64 mg HCHO/kg (45-90 mg/kg, n = 8). Judged by the fermentation criteria both silages were of good quality, but according to organoleptic tests the quality of the silage was better in Exp. 1 than in Exp. 2. In Exp. 1 the cows received HCHO from the silage at the average rate of 0.13 g/day and one group also received 2.01 g HCHO/day from the treated urea (altogether 2.14 g/day). Formaldehyde was found in the milk of four cows on the latter diet but in only one milk sample from three of them and in two samples from one. The HCHO content of these samples was 0.2-0.3 mg/l. In Exp.2 the cows in the two groups received HCHO from the silage at the average rates of 1.47g and 1.58g/day. In addition those in the latter group received 1.29g HCHO from the HCHO-urea (altogether 2.87g/day).The average formaldehyde content of the milk in the former group was 0.3mg/1(0-0.7mg/l) and in the HCHO-urea group 0.6mg/l(0.3-1.0mg/l). When the only source of formaldehyde was silage, there was a highly significant positive correlation between the HCHO content of the diet and that of milk, but when the cows received formaldehyde from both silage and HCHO-urea, the correlation was not significant. It thus appears that formaldehyde is transferred more easily to milk from silage than from HCHO treated urea

Untreated and formaldehyde-treated urea as nitrogen sources for lactating dairy cows

An experiment was performed with 22 Friesian cows, using a double reversal design with two treatments and one similar sequence for the two groups. The lengths of the standardization period, adaptation periods, test period and post-test period were 4, 1, 8 and 4 weeks, respectively. During the standardization and post-test periods the cows received pre-wilted grass silage ad libitum and a small amount of field-dried baled hay. In the test period hay was given ad libitum and the amount of grass silage was restricted. A concentrate mixture (barley, oats, minerals) was given daily to each cow at the rate of 0.3 kg/kg 4 % milk. During the standardization and post-test periods the mixture contained one percent of untreated urea and during the test period 2.5 % of untreated or treated urea. The urea had been treated with 1.5 % formaldehyde on a weight basis. The concentrate mixture was fed individually to each cow, but group feeding was used for the roughage. Among the cows producing more than 15 kg of 4 % milk a day, those receiving formaldehyde-treated urea had a significantly (P< 0.01) higher milk yield, and the fat content of their milk was significantly (P< 0.05) lower than the group receiving untreated urea. Among the cows producing less than 15kg of 4 % milk/day, the group given treated urea had a significantly (

Effect of the crude protein level on the utilization of untreated and formaldehyde-treated urea in vitro

Utilization of untreated urea (F0) and urea treated with 1.5 % formaldehyde(F1.5) was tested in vitro on incubation substrates with different levels of crude protein: 9, 10, 11, 12, 13, 14, 15 and 16 % of the substrate dry matter. The content of crude protein was adjusted by addition of urea, the lowest level (9 %) being that of the substrate without urea. The incubation time was five hours. When F0 urea was used microbial protein synthesis, determined by tungstic acid-sulphuric acid precipitation, reached its maximum at the crude protein level of 11 %. When F1.5 urea was added, the synthesis increased up to the level of 15 % crude protein. At the levels of 13-15% crude protein, the synthesis was significantly (P< 0.05) higher with F1.5 urea than with F0 urea. In the bacterial mass obtained by ultracentrifugation the content of methionine was significantly higher (P< 0.01) when treated urea was used. With untreated urea, the proportion of lysine was significantly higher (P< 0.05). Addition of urea did not affect the amino acid composition of the bacterial mass but increased the yield of microbial protein during incubation

Factors affecting in sacco degradation of dry matter and crude protein in grass silage

The degradability of dry matter and crude protein was studied in 96 grass silages, which were collected from practical farms in different parts of Finland. The degradabilities were determined by the nylonbag technique in sheep on a grass silage and hay (50 : 50 on DM basis) -based diet. Among chemical components the N-free extracts increased, and the crude fibre decreased the dry matter degradation in the rumen. The correlation between the end-products from silage fermentation and the dry matter degradability was generally negative. The level of the crude protein degradability was significantly increased when the crude protein content in the silage DM was increased. The amount of NO3 in the silage DM had a similar effect. The rate of crude protein degradation was regulated mainly by the proteolysis in the silage, e.g. the amounts of NH, and especially watersoluble N in the total N of silage. Crude fibre tended to protect crude protein against ruminal digestion

Effect of nitrogen fertilization on the protein quality of timothy grass and silage

Timothy grass given N fertilizer at the rates of 40, 80 and 120 kg N/ha was preserved in 3 glass-fibre silos of 0.4 m3. The crude protein content of DM in the grass increased with the increase of N fertilization as follows: N40 14.8 %, N80 18.4 % and N120 22.1 %, but the proportion of true protein in crude protein decreased: N40 82 %, N80 78 % and N120 76 %. The proportion of watersoluble N in the total N in the grass was: N40 27 %, N80 30 % and N120 33 %. The higher was the N fertilization level, the more rapidly was the protein of the grass degraded in the rumen. The amino acid profile of the protein was similar at all the N fertilization levels. The quality of all the silages was good. The NH3-N fraction of total N was 2.8—3.9 % and the proportion of water-soluble N in total N was 51—55 %, In silage the decrease during ensiling in the proportion of true protein in crude protein and the increase in the proportion of water-soluble N in total N were smaller than in the other silages. The rumen degradability of protein during the first two hours was also lowest in this silage

Effects of feed fat on the composition and technological properties of milk and milk fat

The aim of the study was to establish how the addition of rapeseed oil to a processed feed mixture affects the milk produced on commercial dairy farms as well as the composition and quality of the products made from that milk. In this study, replacing grain with processed feed mixture to which 2 or 4 % rapeseed oil had been added was not found to affect milk yield or composition to any considerable extent. As a result of the test feedings, the amounts of myristic and palmitic acid in the milk fat decreased and those of stearic and unsaturated fatty acids increased. This change in fatty acid composition can be viewed as nutritionally desirable, and it also had a good effect on the consistency of butter. During the second test period (4 % rapeseed oil) the cutting firmness figures of the butter were lowest, and in sensory evaluations the butter was also found to have the best consistency. The test feeding had a slight beneficial effect on the composition of milk protein. The amount of casein nitrogen grew and that of NPN fell. However, the test feeding was not found to affect the quality of the market milk, cream, cheese or milk powder

The effect of inoculants and cellulase on the fermentation and microbiological composition of grass silage: I Biochemical changes in the silages

The effect of the inoculation and the adding of the cellulase enzyme on the fermentation of sugar-rich, direct cut grass were studied. The control silages were made by using AIV II solution and no additives. The silages were prepared from the first cut on a farm scale in the summer of 1985. Generally all four silages were organoleptically good. The results showed only minor differences in the fermentation between untreated and inoculated or enzyme silages. The quality of fermentation, however, was improved in inoculated and enzyme silages. The quality further improved by using the AIV II solution. This was supported by the changes in the pH, ammonia, buffering capacity, redox potential, temperature and finally by a better digestibility of organic matter