Browsing by study line "Animal Science"

Immunodeficiency in neonatal piglet is one of the major causes of pre-weaning mortality. Colostrum supply cytokines to newborn piglets, which play an important role in formation of their immune mechanism. This study aims to identify the relationship between sow’s blood and colostrum cytokines, and effect of resin acid-enriched composition (RAC) in sow’s blood and colostrum cytokines concentration. RAC is a plant extract of coniferous tree, and it is composed of resin acids and fatty acids which exert immunomodulatory function. Two experiments were conducted in two different farms where RAC was supplemented in the diet of late gestation sows, starting from one week before of expected farrowing date till farrowing. Multiplex immunoassay was used to determine the interferon alpha (IFN-α), interferon gamma (IFN-ɣ), interleukin 1 (IL-1), interleukin 10 (IL-10), interleukin 4 (IL-4), interleukin 6 (IL-6), interleukin 8 (IL-8), tumor necrosis factor alpha (TNF-α) and interleukin 12p40 (IL-12p40) cytokines concentration in blood and colostrum of sow collected within 2 hours of the birth of first piglets. There were significant (p < 0.05) positive correlations between sow’s blood and colostrum cytokines concentration. RAC-fed sows had significantly (p < 0.05) higher level of IL-1 and showed positive tendency (p = 0.1) to increase TNF-α cytokine level in blood. Colostrum level of IFN- ɣ, IL-1 and IL-12p40 had also positive tendency (p = 0.1) to rise in RAC supplemented sow. On this basis, it is proposed that application of RAC in late gestation sow diet enhance the cytokine production in sow’s blood, and blood cytokines levels are positively correlated with colostrum cytokines.

The feeding behavior of beef cattle is complex and varies depending on different factors such as the nutritive value of the feed, the individual and the environment. By optimizing and improving the feed efficiency, the economics of the production increases. Knowledge of feed intake and feeding behavior can be used to optimize the production and the health and well-being of the animals. The aim of this study was to determine how the cut of grass silage affects the feeding behaviour of bulls and thereby how to optimize the use of silage for animal growth. Simmental bulls got three different silage cuts. The first cut was taken on 25th June (ES1), the second cut on 11th August (ES2) and the third cut on 3rd October (ES3). The feeding was given as total mixed ration (TMR) ad libitum. Each TMR group had 15 bulls (TES1, TES2, TES3). Each TMR group had a diet based on grass silage (550 g/kg DM), the only difference being if the silage was of the first, second or third cut. That way the nutritive value differed among the TMR. Individual information about duration, when, and how much the bulls ate was recorded by the Growsafesystem. The average for the bulls in the feeding groups was calculated based on the individual data. This Master´s thesis researched feed intake, feeding frequency, time for head down, time for feed intake and feed intake rate during one month when the body weight of the bulls was on average 546 kg in the beginning and 607 kg at the end of the study. The dry matter for the three cuts was 201 g/kg for ES1, 298 g/kg for ES2 and 354 g/kg for ES3. D-value was 719, 685 and 739 g/kg DM, respectively. The bulls that ate ES3 had higher dry matter intake (12,1 kg DM/d) and eating rate (94,9 g DM/min) than the two other groups. The bulls that ate ES1 and ES2 had the same feed utilization, which was better than the feed utuilization of the bulls that were given ES3. Feeding frequency was about 15 times per day for all groups. The second cut had the lowest digestibility and the bulls eating the second cut had the longest feed intake time. The bulls that ate the third cut had the highest dry matter intake, but the lowest feed utilization. The study indicates that the D-value of the grass silage used in TMR has a clear impact on dry matter intake of the TMR and eating time and eating rate of the animal.

Kivennäis- ja hivenaineet ovat lypsylehmälle välttämättömiä elintoimintojen ja tuotannon ylläpitoon. Härkäpavun siementä voidaan käyttää valkuaisen lähteenä ja koko kasvustoa säilörehuna, mutta niiden hivenainekoostumusta ei tunneta yhtä hyvin kuin rypsirouheen ja nurmisäilörehun. Tutkimuksessa verrattiin lypsylehmän kivennäis- ja hivenaineiden saantia ja sulavuutta härkäpapusäilörehusta ja härkäpavun siemenestä nurmisäilörehuun ja rypsirouheeseen. Tutkielmassa tarkasteltiin kahta koetta, jotka oli tehty Viikin opetus- ja tutkimustilalla vuosina 2014 ja 2015. Molemmissa kokeissa oli 8 Ayrshire-rotuista lypsylehmää. Kokeet toteutettiin kaksinkertaisina 4x4 latinalaisina neliöinä, joissa oli neljä ruokintaa neljänä kolmen viikon jaksona. Koeasetelmat olivat 2x2 faktoriaalisia. Ensimmäisessä kokeessa faktoreina olivat säilörehun kasvilaji (nurmi tai 1:1 nurmi+härkäpapu-kevätvehnä) ja väkirehun raakavalkuaispitoisuus (175 tai 200 g/kg ka). Toisessa kokeessa faktoreina olivat valkuaistäydennys eri lähteistä (rypsirouhe tai härkäpapu), sekä näiden osittainen korvaaminen Spirulina platensis mikrolevällä. Kokeen 2 koeruokinnat olivat isonitrogeenisiä valkuaisrehujen suhteen. Kokeessa 2 kaikissa koeruokinnoissa oli sama pitoisuus kaupallista kivennäisrehua ja kokeessa 1 kivennäislisä oli täysrehuissa. Härkäpapusäilörehuseos sisälsi enemmän kivennäisaineita, mutta vähemmän hivenaineita kuin nurmisäilörehu. Härkäpavun siemen sisälsi 70 % enemmän kuparia kuin rypsirouhe. Härkäpapusäilörehuseos lisäsi eri kivennäisaineiden saantia 1-6 %, mutta vähensi hivenaineiden, kuten raudan ja mangaanin saantia 5-7 % verrattuna nurmisäilörehuun. Härkäpavun siemen lisäsi kuparin saantia 9 %, mutta pienensi magnesiumin, rikin, raudan, mangaanin ja seleenin saanteja 2-14 % verrattuna rypsirouheeseen. Härkäpavun lisääminen ruokintaan kokoviljasäilörehuna tai kokonaisena siemenenä ei vaikuttanut kivennäis- tai hivenaineiden sulavuuteen. Härkäpapusäilörehu tai härkäpavun siemen eivät eronneet merkittävästi nurmirehusta tai rypsistä hivenaineiden lähteinä. Härkäpapu ei sisältänyt mitään kivennäis- tai hivenainetta haitallisen suurta tai hälyttävän pientä määrää.

Maissinviljelyn yleistymiseen 2000-luvun aikana Suomessa ovat vaikuttaneet uudet lajikkeet, joilla on nopeampi kehitysrytmi ja parempi kylmänsietokyky. Ilmaston lämmetessä viljelyn odotetaan kasvavan entisestään. Nautakarjan rehuksi viljeltäessä rehumaissin etuna verrattuna nurmisäilörehuun on kertakorjuulla saatava suuri kuiva-ainesato ja suuri energiapitoisuus. Tässä maisterintutkielmassa selvitettiin korjuuajankohdan ja lajikkeen vaikutusta rehumaissin sokeri- ja tärkkelyspitoisuuteen sekä in vitro -sulavuuteen. Aineisto kerättiin Helsingin yliopiston Viikin tutkimustilalla kasvukauden 2019 aikana tehdystä kenttäkokeesta. Osaruutukokeessa pääruututekijänä oli korjuuajankohta (101, 123 ja 144 vrk) ja osaruututekijänä lajike (P7326, P7034, MAS 10.A, MAS 08.F). Lisäksi tutkittiin lämpösumman vaikutusta sulamattoman neutraalidetergenttikuidun (iNDF) pitoisuuteen käyttäen aineistona Viikissä kolmena peräkkäisenä kasvukautena (2017-2019) tehtyjen ruutukokeiden tuloksia. Maissirehun sokeripitoisuus pieneni ja tärkkelyspitoisuus suureni myöhempinä korjuuajankohtina. Ravintoarvo oli suurin korjattaessa rehu 144 vrk kylvöstä. Rehun sulavuus oli suurimmillaan 123 vrk kylvöstä, mutta sulavuus ei laskenut tilastollisesti merkitsevästi korjattaessa rehu 144 vrk kylvöstä. Lajikkeista MAS 08.F sisälsi eniten sokeria ja vähiten tärkkelystä, joten sen ruokinnallinen laatu oli heikoin. MAS 10.A:n sokerin ja tärkkelyksen yhteispitoisuus oli suurin ja sulavuus muita lajikkeita parempi. Lajikkeiden koostumuksen muutokset eivät vastanneet aiempien tutkimusten tuloksia, joissa aikaisemmat lajikkeet sisälsivät enemmän tärkkelystä kuin myöhäisemmät lajikkeet. Lämpösumman kasvaessa rehun iNDF-pitoisuus lisääntyi. Kun lämpösumman kertymä laskettiin käyttämällä rajana +10 °C keskilämpötilaa iNDF-pitoisuus kuiva-aineessa kasvoi astetta kohden kaksi kertaa enemmän kuin laskettaessa lämpösumman kertymä käyttämällä rajana +5 °C keskilämpötilaa. Etelä-Suomen olosuhteissa on siis mahdollista korjata laadukas rehumaissisato nautakarjalle. Riittävän pitkä kasvuaika mahdollistaa tärkkelyksen kertymisen tähkään, mikä kompensoi kasvin ikääntyessä tapahtuvaa kuidun sulavuuden heikentymistä.

Residual feed intake (RFI) is a measurement method used in animals to determine feed efficiency. Improving feed efficiency has been found to be more cost-effective than maximizing daily gain. Determining the feed efficiency is laborious as the measurement periods are long and expensive. The problem is the limited capacity of the measuring devices in relation to the number of animals, because the animals daily dry matter intake (DMI), average daily gain (ADG) and metabolic body weight (MMBW) must be measured over a sufficiently long continuous period. The aim of the study was to optimize the measurement of residual feed intake to reduce workload. In this case, the costs of measurement would be lower, and the utilization rate of measuring equipment would be improved. The study sought a critical limit on the amount of data required. Measurements were removed from the data until it was found that the reliability of the results was affected. The hypothesis was that the fewer measurements and the shorter the measurement period, the greater the risk of error in the results. The study material included 105 dairy bulls and the experiment lasted 56 days. DMI was measured for each animal and the animals were weighed once a week during the experiment, a total of nine times (double weighings at the beginning, middle and end of the measurement period). The growth curves were used to calculate the ADG and MMBW of the animals. In addition, the area of the area of the cross-section of the longissimus muscle (M.longissimus dorsi) and the thickness of the back fat of each bull were measured with an ultrasound device at the end of the experiment. RFI was calculated for seven different measurement periods. The original 56-day period was shortened to seven days at a time until the period was 28 days. Ultrasound measurements were added to the 56-day measurement period model only. In addition, the number of weighing was reduced from nine to five and three times from the original 56-day model. The addition of ultrasound measurements weakened the statistical model compared to the initial 56-day measurement period. The animal RFI results changed the most in the 28-day and 35-day models. The reliability of the results decreased the least in the 49-day and five-weighing models. The ADG and MMBW averages remained almost the same in the models until 35 days. The shorter the measurement period, the more the DMI values changed. Based on the results, shortening length of the RFI measurement period to 42 days had no market effect on the results. A 42-day measurement period is enough for DMI, but a longer measurement period is recommended for ADG. Three weighings did not change the ADG as much as the 49-day measurement period and was more reliable than the 42-day measurement period. Adding longissimus muscle and back fat to the RFI model did not improve the reliability of the model and thus did not provide added value. Based on this study, ultrasonic measurements are not required to determine RFI, and the workload can also be reduced by shortening the measurement period or reducing weighing times.

Iodine deficiency is a global health problem that causes physical and mental development disorders in humans. School-age children, pregnant women and consumers of organic food are particularly vulnerable to iodine deficiency. The popularity of organic products is growing, and attention should be paid to the iodine content of organic milk, as the iodine content of organic milk is usually lower than in conventionally produced milk. The aim of this study was to increase the iodine content of organic milk by adding two different species of seaweed, Ascophyllum nodosum and Laminaria digitata, to dairy cow diets, and thus create a sustainable mineral feeding strategy for dairy cows in organic production. The aim was to study the effect of dietary seaweed addition to iodine content of milk together with rapeseed cake or pea, as rapeseed cake is known to contain goitrogenic compounds that reduce iodine transfer to milk. The experiment was conducted at the Viikki Research Farm from 31 March to 25 June 2020. The experiment included 12 lactating Ayrshire cows and the experimental design was a cyclic changeover study. The factors studied were the effects of dietary protein source (rapeseed cake or pea) and the species A. nodosum or L. digitata on the intake of mineral and trace elements on dairy cows and on the mineral content of milk. In particular, effects on milk iodine were studied. The experiment had three 17-day trial periods and there was an 18-day wash-out period between the periods, when no seaweed was fed in order to minimize the carry-over effects between periods. The samples were collected on the last four days of the periods. Experiment included six dietary treatments in which protein feed was isonitrogenously either rapeseed cake or pea and diets were supplemented with seaweed. The dietary treatments were: rapeseed control K-R (no seaweed), pea control K-H (no seaweed), which were supplemented with 56,9 g dry matter (DM)/d A. nodosum i.e. seaweed 1 (M1- R, M1-H) and 7,8 g DM/d L. digitata i.e. seaweed 2 (M2-R, M2-H). The target iodine content of control diets was 1 mg/kg DM and seaweed diets 4 mg/kg DM. Finnish iodine recommendation for feeds that do not contain goitrogenic compounds is 1 mg/kg DM. Cows had ad libitum access to partial mixed ration that contained grass silage, barley and protein feed. In addition, concentrate was given to cows 1,8 kg/d and contained minerals (300 g/d), molassed sugar beet pulp, molasses and also seaweed in seaweed diets. The forage to concentrate ratio was 65:35. Mineral used in diets was approved for organic production and contained iodine 60 mg/kg DM. Dietary treatments did not affect DM intake. Compared to rapeseed diets, pea diets had a 0,15 kg/d lower crude protein intake, 0,24 kg/d lower crude fat intake and 49,7 µg/d lower iodine intake. Iodine intake increased on average by 63,4 µg when seaweed was added to the diet and the effect was greater when adding L. digitata compared to A. nodosum. Also, milk yield was lower with pea diets than with rapeseed diets. The iodine content of milk was higher with pea diets than with rapeseed diets (324 vs. 117 µg/l). Moreover, the addition of seaweed increased the iodine content of milk (on average +226 µg/l). Based on the results, iodine intake was lower with pea diets than with rapeseed diets, as expected, due to the higher iodine concentration of rapeseed cake. Both seaweeds increased the iodine content of milk, but the transfer of iodine to milk was higher with pea-based diets compared to rapeseed-based diets, due to goitrogenic compounds in the rapeseed cake.

Härkäpavun (Vicia faba) viljely ja käyttö rehuna lisää tilan valkuaisomavaraisuutta. Biologisen typensidonnan ansiosta härkäpapu sitoo ilmakehän typpeä maaperään ja, sitä kautta sillä on hyvä esikasviarvo viljelykierrossa. Se on kiinnostava vaihtoehto nautojen ruokintaan suuren biomassantuottopotentiaalin ja suuren raakavalkuaispitoisuuden ansiosta. Härkäpavun puutteita märehtijöiden rehukäytössä ovat valkuaisen suuri pötsihajoavuus ja valkuaisen niukka metioniinipitoisuus. Tämän tutkimuksen tavoitteena oli selvittää nurmisäilörehun osittaista korvaamista härkäpapusäilörehulla, ja sen vaikutuksia maitotuotokseen, maitorauhasen aminohappoaineenvaihduntaan sekä rehuvalkuaisen hyväksikäyttöön. Lisäksi tutkittiin voiko pötsisuojattu metioniinilisä parantaa härkäpapuvalkuaisen hyväksikäyttöä maidontuotannossa. Tutkimus toteutettiin toistettuna 4 x 4 latinalaisena neliönä Helsingin yliopiston Viikin opetus- ja tutkimustilan navetassa 28.9.-20.12.2019. Kokeessa oli 8 ayrshire -rotuista lypsylehmää. Tutkimuksessa oli faktoriaalinen 2 x 2 koeasetelma, jonka tutkittavina tekijöinä olivat säilörehun kasvilaji ja härkäpapuvalkuaisen täydennys pötsisuojatulla metioniinilla. Koeruokinnat pohjautuivat 1. sadon timotei-nurminatasäilörehuun (Phleum pratense ja Schedonorus pratensis, Nurmi, D-arvo 664 g/kg ka) ja seokseen, jossa 2/3 timotei-nurminatasäilörehun kuiva-aineesta korvattiin härkäpapusäilörehulla (HP, D-arvo 593 g/kg ka). Väkirehun osuus koeseosrehujen kuiva-aineesta oli 40 % ja se koostui ohrasta, kaurasta, härkäpavusta sekä kivennäisestä. Seosrehuruokinta oli vapaata. Ohutsuolesta imeytyvän metioniinilisän määrä oli koeruokinnoissa 0 tai 20 g/vrk. Metioniini annettiin yhdessä melassileikkeen (1 kg/vrk) kanssa lypsyjen yhteydessä. Kuiva-aineen syönti lisääntyi HP-ruokinnassa verrattuna Nurmi-ruokintaan. Pötsisuojattu metioniini ei vaikuttanut kuiva-aineen syöntiin. Pötsisuojattu metioniinilisä vähensi maitotuotosta Nurmi-ruokinnassa lähes 2 kg/vrk, mutta HP-ruokinnassa maitotuotos pysyi samana. Metioniinilisän vaikutuksesta maidon laktoosipitoisuus väheni ja valkuaispitoisuus (sekä suuntaa-antavasti rasvapitoisuus) lisääntyi säilörehun kasvilajista riippumatta. Energiakorjattu maitotuotos lisääntyikin HP-ruokinnassa metioniinilisän vaikutuksesta, mutta väheni Nurmi-ruokinnassa. Maidon ureapitoisuus oli HP-ruokinnoissa suurempi kuin Nurmi-ruokinnoissa. Metioniinilisä tehosti rehutypen hyväksikäyttöä maitovalkuaiseksi HP-ruokinnassa ja heikensi sitä Nurmi-ruokinnassa. Valtimoplasman glukoosipitoisuus väheni Nurmi-ruokinnassa ja lisääntyi HP-ruokinnassa metioniinilisän myötä. Metioniinilisä lisäsi rikkipitoisten aminohappojen (Met, Cys) ja tauriinin pitoisuutta plasmassa. Rikkipitoisten aminohappojen pitoisuus oli suurempi Nurmi-ruokinnoissa verrattuna HP-ruokintoihin. Tutkimuksen perusteella osa nurmisäilörehusta voidaan korvata härkäpapusäilörehulla ilman, että maitotuotos heikkenee. Metioniinilisä oli tarpeeton Nurmi-ruokinnassa ja aiheutti negatiivisia tuotosvasteita. Metioniinilisällä voi kuitenkin olla positiivisia vaikutuksia maidon koostumukseen ja rehuvalkuaisen hyväksikäyttöön ruokinnassa, joka sisältää härkäpapua sekä säilörehuna että valkuaisrehuna.

The objective was to evaluate how different silage additives can manipulate the ensiling process and the profile of bacterial communities of grass silages under varying management conditions. Silages were made from mixed timothy (Phleum pratense) and meadow fescue (Festuca pratensis) grass to laboratory scale silos using two compaction levels. The tightly compacted grass was also contaminated with soil and dairy cow faeces. Four additive treatments were used including control without additive (CONT), formic acid based additive (FA), homofermentative strains of lactic acid bacteria (LAB) and salt based additive (SALT). Tight compaction resulted on average in lower pH and ethanol concentration in silages than loose compaction mostly caused by changes in CONT silages. Soil contamination clearly affected CONT and SALT silages by stimulating extensive fermentation and thus decreasing pH and amount of residual water-soluble carbohydrates (WSC) compared to non-contaminated silages. In all conditions, FA restricted fermentation resulting in silages with high WSC and reduced total fermentation products concentration. Soil contamination improved aerobic stability of silages compared to non-contaminated ones because of higher acetic acid concentration in contaminated silages. Abundance of selected 16 bacteria in raw material was low, with Sphingomonas and Stenotrophomonas genera being the most abundant. After fermentation both Lactobacillaceae family and as part of it Lactobacillus genus were dominant with Sphingomonas genus in most of the silages. FA decreased the abundance of Lactobacillaceae family whereas LAB increased it. Soil contamination reduced the amount of other Lactobacillaceae family but boosted the growth of Lactobacillus genus. Lactobacillus presented negative correlations with Mycoplana, Devosia and Sphingomonas. Five bacteria were connected to desirable fermentation pattern and they all were part of same phylum Firmicute. All other selected bacteria had negative correlation with low pH and amount of lactic and total fermentation acids in silage. Use of additives improved fermentation quality of silages ensiled under different management conditions. Different types of additives resulted in varied bacterial profiles. Results confirmed the importance of tight compaction and good hygiene for stable fermentation. Strong correlations between bacterial communities and fermentation quality parameters provided clear insight of the role of the most abundant populations on the fermentation process of grass silage.

Cattle breeding has become much more effective in recent decades thanks to the development of reproductive biotechnologies and genetic testing. In 1970s it was discovered that embryo transfer techniques make it possible to produce plenty of offspring from top quality females which intensified dairy cattle breeding. Nowadays, there is two embryo transfer techniques in use, MOET and OPU-IVP. A genomic selection has also made genetic improvement of cattle populations more intense than before. Genomic selection is a method that utilizes single nucleotide polymorphisms that appear in individual genome. Today both the embryo transfer techniques and genomic selection are essential elements of cattle breeding all over the world. Genomic selection has typically been carried out on newborn calves. During the recent years, selection has been increasingly carried out and studied on embryo level. Embryo genomic selection always starts with a biopsy taking. After this, sample needs to be genotyped and the results needs to be analysed. Biopsy size has effect on quality of the genotyping outcomes. When the biopsy size grows, quality and reliability of the results will get higher. The aim of this study was to determine if there was any difference in genotyping success between embryos and newborn calves and is it possible to predict embryo-calf genotype similarities via embryo call rate. Material included SNP-genotyping results from a total of 214 embryo and 13 corresponding calves. R programming language was used to statistically analyse the results. Embryo call rates, SNP call rates and embryo-calf genotype similarities were determined from the data. Embryos and their corresponding calves had high similarity with their genotypes, 91,7 % on average. This supports the hypothesis that embryo and their corresponding calves will not have major differences in their genotyping results. Embryo call rates were also in high levels (on average 90,3 %) as was found also in the previous studies. Hence, results from this study confirmed the hypothesis that genotyping of the embryos is a reliable and successful method. There was no clear relationship between embryo call rates and embryo-calf genotype similarities; embryo-calf pair with weakest genotype similarity results, had good embryo and calf call rates. On the other hand, embryo call rates of the two following pairs that got the second and third worst results were clearly below average. In the cases with overall weakest embryo-calf genotype similarities, it was not possible to improve it by eliminating the worst embryo genotypes. Reliable genotyping of embryos enables prediction of genomic breeding values for embryos. Instead of making decision on embryo purchase according to breeding values of the parents of the embryo, purchaser can select embryos according to their own breeding value. Thereby, in the future, embryo genomic selection is likely to become more common than today.

Including feed efficiency in a selection index and its estimation on farms cannot be done by dry matter intake, because it’s not possible to measure dry matter intake on farms. It could be possible to evaluate dry matter intake by using rumination time as an indicator trait. Many farms already have devices to observe rumination. To be a useful candidate trait in selective breeding, rumination time needs to be heritable. The aim of this study was to evaluate genetic parameters of daily rumination time in first three lactations in Finnish Ayrshire. The data was received from FABA co-op and it contained production-, insemination-, calving- and herd data as well as pedigree data of Finnish Ayrshire cows. In addition, rumination data collected by Heatime and SenseHub equipments, were included in the study with the permission of SCR Engineers Ltd. The data was edited into the form to be processed and examined with RStudio, pedigree data was processed with RelaX2 and variance components for daily rumination time and daily milk production were computed by REML method with DMU. Tables and graphs were made in their final form with Excel spreadsheet software. Two separate materials were made from the data: the data of first-time calved cows and the data of 1 to 3 times calved cows. The data was studied as two-trait repeatability model in which observations of rumination time were from all lactation stages. The heritability of rumination time was 0,14 (SE 0,05) for primiparous cows and 0,19 (SE 0,02) for cows having 1 to 3 lactations. The genetic correlation between rumination time and milk production was 0,05 (SE 0,21) for primiparous cows and 0,31 (SE 0,06) for cows having 1 to 3 lactations. Daily rumination time is a heritable trait and hence it can be used as a direct or indicator trait in selective breeding. Further studies of the genetic correlations between rumination time and dry matter intake should be done to evaluate the usability of rumination time as an indicator of dry matter intake.