Spelling suggestions: "subject:"dairy cattle -- hutrition"" "subject:"dairy cattle -- elutrition""
1 |
The effects of feed area design on the social behaviour of dairy cattleRioja-Lang, Fiona C. January 2009 (has links)
The overall objective of this thesis was to assess the effect of feed area design including feeding space availability, barrier type and stocking density, on the feeding behaviour of dairy cows. Feed intake in dairy cows is directly related to milk production, thus a good food supply is extremely important to the modern, high producing dairy cow. Intake is critical for improving milk production, health, body condition and the welfare of the animals. Feeding designs can have a major effect on behaviour and feed intake, therefore it is an important consideration when housing cattle and other livestock. The effect of altering the amount of space allowance available at the feed-face highlighted a significant effect on feeding patterns. As the space allowance increased the number of feeding bouts also increased (P<0.001) and length of bouts decreased (P<0.05). However, when provided with extra space at the feed-face, cows did not increase their feed intake as hypothesised, possibly as a result of the differences between individual animals being masked by an overall group effect. The number of aggressive interactions decreased as the space allowance increased (P<0.001) and furthermore, the number of times individuals were displaced from the feeding area also decreased as the space allowance increased (P<0.05). Subsequently, preference tests were used as a behavioural tool to determine how individual cows perceive their feeding environment with specific emphasis on understanding what difficulties low ranking animals face at the feed-face. Subordinate cows showed a significant preference for feeding alone rather than next to a dominant when they were offered high quality feed on both sides of a Y-maze test (P<0.001). When “asked” to trade-off between feed quality and proximity to a dominant cow, subordinate cows chose to feed alone on low quality food. A follow-on experiment using the same methodology was undertaken and aimed to identify the space allowances at which cows would not trade-off food quality. Four different space allowances were tested. At the two smaller space allowances, cows preferred to feed alone and for the two larger space allowances, cows had no significant preferences. The feed barrier has been shown to have a major effect on feeding and social behaviour of group housed dairy cows. A barrier design that provides some sort of separation between cows has also been shown to reduce competition. The aim of the final study was to determine if a feed barrier which obscured the cows’ visual field whilst feeding would increase vigilance behaviour and alter normal feeding behaviour, particularly for subordinates. Two different types of feed barrier were tested at four different stocking densities. The average daily feeding time was higher when cows were fed using a conventional headlock system compared to an electronic feeding system (P<0.05). All groups of cows displayed vigilance scans, however, neither type of barrier, feed space allowance, or dominance rank had an effect on the frequency of scans. These results indicate that neither feeder design nor stocking rate affect vigilance in dairy cows, at least over the treatment conditions assessed in the current study. The results of this research illustrate that to achieve the maximum levels of feeding behaviour and a reduction of aggressive behaviour, the cows’ environment must be such that it provides sufficient space and feed barrier design which will allow normal social behaviour. Over-stocking at the feed-face should be avoided to reduce competition. Future research should consider the long term effects of over stocking and competition on dry matter intake (DMI), milk production and health.
|
2 |
The role of dietary cation-anion difference (DCAD) on the blood buffering capacity and the susceptibility of dairy cattle to induced ketoacidosis /Fletcher, John D. January 2000 (has links)
Two experiments were conducted to investigate the effects of metabolic acid-base balance on feed intake and susceptibility of dairy heifers to ketoacidosis. Animals were fed two dietary cation-anion difference diets [dietary cation-anion difference is defined as mEq (Na++K+)-(Cl -+S2-) kg-1 dietary dry matter], a high dietary cation-anion difference (positive) and a low dietary cation-anion difference (negative). The heifers fed the positive dietary cation-anion difference had significantly higher blood pH, blood bicarbonate and dry matter intake than heifers fed the negative dietary cation-anion difference. There was an initial decrease in dry matter intake by the heifers fed the negative dietary cation-anion difference. However this difference was not significant by the end of the two week period. It is unclear whether the reduced dry matter intake in the heifers fed the negative dietary cation-anion difference is the result of metabolic-acidosis caused by the anionic salts, poor palatability of the anionic salts or a combination of both. Heifers were induced into a nervous ketosis by feeding 1,3-butanediol. There was no difference in the incidence of ketosis between animals fed positive and negative dietary cation-anion difference. Animals fed the positive diet tended to be more susceptible to anorexia.
|
3 |
The role of dietary cation-anion difference (DCAD) on the blood buffering capacity and the susceptibility of dairy cattle to induced ketoacidosis /Fletcher, John D. January 2000 (has links)
No description available.
|
4 |
Effects of nutrition on the conjugated linoleic acid content of milkLiebenberg, Lindie 03 1900 (has links)
Thesis (MScAgric (Animal Sciences)--University of Stellenbosch, 2007. / The objective of this investigation was to determine the effect of supplemented conjugated
linoleic acid (CLA) on milk production and milk composition of lactating dairy cows in
production systems commonly used in South Africa.
In the first of three trials, samples of 24 bulk tanks were collected to get an impression of the
CLA status of milk in the Western Cape Province, South Africa. Six samples were each
collected from Jersey and Holstein herds in total mixed ration (TMR)-based systems. Another
six samples were each collected from Jersey and Holstein herds on pasture-based systems.
An additional three samples were also collected from co-op silos. One of these came from a
mixed herd on TMR, one from a Jersey herd on TMR and the third sample from a mixed herd
on pasture. The CLA levels of the milk were within the range reported in literature, albeit on
the low side. The mean CLA level in milk fat of cows from pasture and TMR-based systems
were 10.5 and 5.45 mg/g of fatty acids, respectively. This is in agreement with trends
reported in the literature with cows on pasture having higher levels of CLA in their milk than
cows on TMR’s. In this study, breed had no effect on the CLA level in milk fat.
|
5 |
The effect of sugar, starch and pectin as microbial energy sources on in vitro forage fermenation kineticsMalan, Marcia 03 1900 (has links)
Thesis (MScAgric) -- Stellenbosch University, 2009. / ENGLISH ABSTRACT: Ruminants have a compound stomach system that enables them to utilize forages more efficiently than
monogastric animals. However, forages alone do not contain sufficient nutrients to meet the requirements of
high producing dairy cows. Forages are high in fibre and their nutrient availability depends on the degree of
cell wall degradability. Improvements in forage fermentation would increase energy intake and subsequently
milk production and performance by dairy cows. It is therefore important to find ways to improve forage
degradation and utilization in the rumen.
The use of different non-fibre carbohydrate (NFC) sources has different effects on animal performance.
Supplementing forage based diets with energy sources containing sugar, starch or pectin results in variation
in performance measurements such as milk yield, milk composition and dry matter intake (DMI).
This thesis reports on two studies in which the effect of energy supplementation on forage fermentation and
digestion parameters was investigated. In the first study an in vitro gas production protocol was used to
determine the effect of sugar (molasses), starch (maize meal) and pectin (citrus pulp) on total gas production
and rate of gas production of different forages. The forage substrates included wheat straw (WS), oat hay,
(OH) lucerne hay (LUC), ryegrass (RYE) and kikuyu grass (KIK). The three energy sources, as well as a
control (no energy source) were incubated in vitro with each of the above mentioned forages. Rumen fluid
was collected from two lactating Holstein cows receiving a diet consisting of oat hay, lucerne, wheat straw
and a concentrate mix. Forages alone (0.25 g DM) and/or together (0.125 g DM) with either molasses
(0.1412 g DM), citrus pulp (0.1425 g DM) or maize meal (0.125 g DM) were weighed into glass vials and
incubated for 72 hours. The weights of the energy sources were calculated on an energy equivalent basis.
Blank vials, that contained no substrates, were included to correct for gas production from rumen fluid alone. The substrates were incubated in 40 ml buffered medium, 2 ml of reducing solution and 10 ml rumen fluid.
Gas pressure was recorded automatically every five minutes using a pressure transducer system and the
method based on the Reading Pressure Technique (Mauricio et al., 1999). Gas pressure was converted to
gas volume using a predetermined regression equation. In the first gas production trial, the gas production
included gas produced by the energy sources, while in the second gas production trial, the energy source
gas production was deducted from the total gas production to determine the effect of energy source on gas
production of respective forage substrates per se. Data were fitted to two non-linear models adapted from
Ørskov and McDonald (1979). Significant forage x energy interactions were observed for the non-linear
parameter gas production (b) in Model 1 and for b and lag phase (L) in Model 2 in both trials. In the first gas
production trial, the higher fermentability of the energy sources supplemented to forage substrates,
increased b (Model 1 & 2) of the LUC and WS. The gas production rate was affected in different ways for
different forages, with the most noticeable effect on WS when it was supplemented with energy sources. All
the energy sources increased c of WS irrespective of the model used. Energy sources had no effect on the
L of LUC, OH or RYE, but decreased the L of WS and KIK. In the second trial, maize meal had no effect on
b for any of the forages (Model 1 & 2), while molasses (Model 1 & 2) decreased b for all forage substrates,
and citrus pulp (Model 1 & 2) decreased b of OH and RYE, to lower values than those of the control
treatments. Gas production rate was not affected by molasses for any of the forage substrates, while citrus
pulp (Model 1 & 2) increased c of OH and maize meal increased c of OH and KIK. Lag phase was only
affected by energy sources in WS and KIK, where all the energy sources had lower L values than the control
treatment. It was concluded that forage fermentability is affected differently by different energy sources.
These observations may have important implications, in practice, on rumen health and milk production, and
the data obtained can potentially be used as guidelines in feed formulations. In the second study, in vitro digestibility trials were undertaken to determine the effect of sugar (molasses
and sucrose), starch (maize meal and maize starch) and pectin (citrus pulp and citrus pectin) on neutral
detergent fibre (NDF) and dry matter (DM) degradability of forages. Forage substrates used included wheat
straw, oat hay, lucerne hay, ryegrass and kikuyu grass. Rumen fluid was collected from two lactating
Holstein cows receiving a diet consisting of oat hay, wheat straw and a concentrate mix. In vitro
degradability was done with an ANKOM Daisy II incubator and forage substrates were incubated with or
without the respective energy sources for 24, 48 and 72 hours. The substrates were incubated in 1076 ml
buffered medium, 54 ml of reducing solution and 270 ml rumen fluid. The residues were washed, dried and
analyzed for NDF. In the study with the applied energy sources (molasses, maize meal and citrus pulp)
there were a forage x energy source interactions. Supplementation with the applied energy sources all
improved dry matter degradability (DMD) of forages (24 and 72 hours), when compared to the control
treatment, except for RYE supplemented with maize meal and citrus pulp at 24 hours. Molasses seemed to
have had the biggest effect on DMD in all forage substrates. Supplementation with maize meal had no effect
on neutral detergent fibre degradability (NDFD) of any forage substrate, except for an improvement in NDFD
of LUC at 72 hours. Molasses improved NDFD of LUC at 24h, but had no effect on the other forage
substrates. Citrus pulp improved NDFD of OH (72 hours), as well as LUC and WS (24 and 72 hours). It is
postulated that the NDF of the energy sources was more digestible than that of the respective forages, and
that the improved NDFD values could be ascribed to the contribution of the energy source NDFD. Overall,
pasture grasses had a higher NDFD than the hays and straw, and appear to be more readily fermentable by rumen microbes than the low quality hays and straw explaining the higher NDFD. In the study involving the
purified energy sources (sucrose, maize starch and citrus pectin), forage x energy source interactions were
observed. In general, supplementation with these energy sources improved DMD at 24 and 72 hours except
for RYE and KIK (72 hours). Pasture grasses (RYE and KIK) had a higher NDFD than LUC, OH and WS. At
72 hours, NDFD was 37.1% for LUC, 42.5% for OH and 40.3% for WS, compared to 70.5% for KIK and
64.9% for RYE. A possible explanation is that KIK and RYE samples came from freshly cut material,
harvested after a 28d re-growth period. In general, sucrose (24 and 72 hours) and citrus pectin (72 hours)
had no effect on NDFD of forage substrates. However, supplementing oat hay (24 hours) with starch and
citrus pectin, and wheat straw (24 and 72 hours) with starch lowered NDFD, when compared to the control
treatment. It is hypothesized that microbes fermented the easily fermentable energy sources first, before
attacking forage NDF. The study suggested that forage NDFD values are not fixed, and may be altered by
type of energy supplementation. / AFRIKAANSE OPSOMMING: Die meervoudige maagsisteem van herkouers stel hulle in staat om ruvoer meer effektief te benut as
enkelmaagdiere. Ruvoere alleen bevat egter nie genoeg voedingstowwe om die behoeftes van hoogproduserende
melkbeeste te bevredig nie. Ruvoere is ryk aan vesel en hul voedingstofbeskikbaarheid word
bepaal deur die graad van selwand degradeerbaarheid. ‘n Verhoging in ruvoerfermentasie sal energieinname
verhoog en gevolglik ook melkproduksie en prestasie. Dit is dus belangrik om maniere te vind om
ruvoerdegradeerbaarheid en -verbruik in die rumen te verbeter.
Die gebruik van verskillende nie-vesel koolhidraat (NFC) bronne het verskillende uitwerkings op die prestasie
van diere. Energie-aanvullings soos suiker, stysel en pektien tot ruvoer-gebasseerde diëte, beïnvloed
prestasiemaatstawwe soos melkproduksie, melksamestelling en droëmateriaalinname (DMI) op verskillende
maniere.
Hierdie tesis lewer verslag oor twee studies waar die invloed van energie-aanvullings op ruvoerfermentasie
en verteringsmaatstawwe ondersoek is. In die eerste studie is ‘n in vitro gasproduksieprotokol gebruik om
die invloed van suiker (melasse), stysel (mieliemeel) en pektien (sitruspulp) op totale gasproduksie (b) en
tempo van gasproduksie (c) van verskillende ruvoersubstrate te bepaal. Ruvoersubstrate wat gebruik is,
was koringstrooi (WS), hawerhooi (OH), lusernhooi (LUC), raaigras (RYE) en kikuyugras (KIK). Die drie
energiebronne, sowel as ‘n kontrole (geen energiebron), is in vitro geïnkubeer saam met elk van die
genoemde ruvoere. Rumenvloeistof is verkry van twee lakterende Holsteinkoeie, wat ‘n dieet ontvang het
bestaande uit hawerhooi, koringstrooi en ‘n kragvoermengsel. Ruvoere is alleen en/of in kombinasie met
melasse (0.1412 g DM), sitruspulp (0.1425 g DM) of mieliemeel (0.125 g DM) in glasbottels afgeweeg en vir
72 uur geïnkubeer. Die massas van die energiebronne is op ‘n energie-ekwivalente basis bereken. Leë
bottels wat geen substraat bevat het nie, is ingesluit om te korrigeer vir gasproduksie afkomstig vanaf
rumenvloeistof alleen. Substrate is in 40 ml van ‘n buffermedium, 2 ml reduserende oplossing en 10ml
rumenvloeistof geïnkubeer. Gasdruk is elke vyf minute outomaties aangeteken deur gebruik te maak van ‘n
drukmetersisteem en die metode is gebasseer op die Reading gasdruktegniek. Gasdruk is omgeskakel na gasvolume deur gebruik te maak van ‘n voorafbepaalde regressievergelyking. In die eerste proef het totale
gasproduksie die gas wat deur die onderskeie energiebronne geproduseer is, ingesluit. In die tweede proef
is gasproduksie afkomstig van die energiebronne afgetrek van totale gasproduksie, om sodoende die invloed
van die energiebronne per se op die gasproduksie van die onderskeie ruvoersubstrate, te bepaal. Data is
met behulp van twee nie-liniëre modelle gepas. Betekenisvolle ruvoer x energie-interaksies is in albei
proewe waargeneem vir die nie-liniëre parameter b (gasproduksie) in Model 1, en vir b en L (sloerfase) in
Model 2. In die eerste proef het die energiebronne se hoë fermentasie gelei to ‘n verhoging in b (Model 1 &
2) van LUC en WS. Energie-aanvullings het die c-waarde van die onderskeie ruvoere verskillend beïnvloed,
met WS wat die mees opvallende effek gehad het. Al die energiebronne het die c-waarde van WS verhoog,
ongeag watter model gebruik is. Energiebronne het geen invloed op die L-waarde van LUC, OH of RYE
gehad nie, maar het wel die L-waarde van WS en KIK verlaag. In die tweede proef het mieliemeel geen
invloed op die b-waarde van enige van die ruvoere gehad nie (Model 1 & 2), terwyl melasse (Model 1 & 2)
die b-waarde van alle ruvoere verlaag het, en sitruspulp (Model 1 & 2) OH en RYE se b waardes verlaag het
tot laer as die kontroles. Melasse het geen invloed op die c-waarde van die onderskeie ruvoersubstrate
gehad nie, terwyl sitruspulp (Model 1 & 2) die c-waarde van OH, en mieliemeel die c-waarde van OH en KIK,
verhoog het. Energiebronne het slegs ‘n invloed op die sloerfase in WS en KIK gehad, waar dit L verlaag
het tot laer waardes as dié van die kontroles. Daar is gevind dat ruvoer-fermenteerbaarheid verskillend
beïnvloed word deur verskillende energiebronne. Bogenoemde resultate kan in die praktyk betekenisvolle
invloede hê op rumengesondheid en melkproduksie en die data wat verkry is, kan potensieël gebruik word
as riglyne in voerformulerings. In die tweede studie is in vitro verteerbaarheidsproewe gedoen om die effek van suiker (molasse en
sukrose), stysel (mieliemeel en mieliestysel) en pektien (sitruspulp en sitrus-pektien) op neutraalonoplosbare
vesel (NDF) en droë materiaal (DM) degradeerbaarheid van ruvoere, te bepaal.
Ruvoersubstrate wat gebruik is, was WS, OH, LUC, RYE en KIK. Rumen vloeistof is verkry van twee
lakterende Holstein koeie, wat ‘n dieet ontvang het bestaande uit hawerhooi, koringstrooi en ‘n konsentraat
mengsel. Die in vitro degradeerbaarheidsproef is gedoen met ‘n ANKOM Daisy II inkubator.
Ruvoersubstrate is geïnkubeer met of sonder die onderskeie energiebronne vir 24, 48 en 72 uur. Die
substrate is geïnkubeer in 1076 ml buffer medium, 54 ml reduserende oplossing en 270 ml rumen vloeistof.
Residue is gewas, gedroog en geanaliseer vir NDF. In die proef met toegepaste energiebronne (molasse,
mieliemeel en sitruspulp), was daar ruvoer x energiebron interaksies. Toegepaste energiebron aanvullings
het almal DMD van ruvoersubstrate (24 en 72 uur) verbeter, uitsluitend vir RYE wat aangevul is met
mieliemeel (24 uur) en sitruspulp (24 uur). Van al die ruvoersubstrate het molasse die grootste effek gehad
op DMD. Mieliemeel aanvullings het geen effek gehad op neutraal-onoplosbare vesel degradeerbaarheid
(NDFD) van ruvoersubstrate nie, behalwe vir ‘n verbetering in NDFD van LUC by 72 uur. Molasse het NDFD
van lucern by 24 uur verbeter, maar geen effek gehad op ander ruvoersubstrate nie. Sitruspulp het NDFD
van OH (72 uur), asook LUC en WS (24 & 72 uur) verbeter. Daar word beweer dat die NDF van
energiebronne meer verteerbaar is as die van ruvoersubstrate, en dat die verbetering in NDFD waardes
toegeskryf kan word aan die bydraes van energiebronne se NDFD. Weidingsgrasse (RYE & KIK) het oor die
algemeen ‘n hoër NDFD as hooie en strooi gehad. Rumen mikrobes blyk ook om dié grasse vinniger te
verteer as lae kwaliteit hooie en strooi, wat gevolglik die hoër NDFD verduidelik. In die proef met suiwer
energiebronne (sukrose, mieliestysel en sitrus-pektien) is ruvoer x energiebron interaksies waargeneem. Energiebronaanvullings het DMD by 24 en 72 uur verbeter, buiten vir RYE en KIK (72 uur). Weidingsgrasse
het hoër NDFD as LUC, OH en WS. By 72 uur was die NDFD van LUC 37.1%, OH 42.5%, WS 40.3%, in
vergelyking met 70.5% vir KIK en 64.9% vir RYE. ‘n Moontlike verklaring vir die hoër NDFD van KIK en
RYE, is omdat dit vars gesnyde material is, geoes na slegs 28 dae hergroei. Oor die algemeen het sukrose
(24 & 72 uur) en sitrus-pektien (72 uur) geen effek gehad op NDFD van ruvoersubstrate nie, terwyl stysel en
pektien aanvullings tot OH (24 uur), en stysel aanvullings tot WS (24 & 72 uur) NDFD verlaag het. Daar
word hipotetieseer dat mikrobes eers die vinnig fermenteerbare energiebronne fermenteer, voordat hulle
ruvoer NDF aanval. Hierdie studie beweer dat ruvoer NDFD waardes nie vas is nie, en dat dié waardes
beïnvloed mag word deur energiebron aanvullings.
|
6 |
Breed differences in ruminal digestibility of forages in dairy cows receiving high concentrate dietsRetief, Nicky 11 1900 (has links)
Thesis (MScAgric)--University of Stellenbosch, 2000. / ENGLISH ABSTRACT: Statistical analysis was conducted on data from two Elsenburg herds, containing 105 Jersey
and 232 Holstein cows. The data was examined for external factors which may affect milk
yield and milk composition. The data consisted of 337 first lactation records, taken over a 20
year time period. Breed of cow had an effect on milk yield, butterfat and protein production,
as did the year in which the cows were born and the age of the heifer at first calving. There
was a significant interaction between the breed and year of birth. There are other external
factors, which are difficult to quantify, which may have an effect on production. In the
following trials, eight ruminally cannulated dairy cows (four Jerseys and four Holsteins) were
used to determine the effect of breed on forage digestibility in the rumen. All cows received a
high concentrate mixed ration, with supplementary wheat straw. An in situ rumen
degradability trial was conducted with three different forages, viz. lucerne, wheat straw and
NaOH-treated wheat straw. The bags were incubated in the rumen for time intervals of 2,4,
8, 12, 16,20,24, 36,48, 72 and 96 hours and samples were analysed for dry matter (DM) and
neutral-detergent fibre (NDF). Higher rumen degradability values (P<0.01) ofDM and NDF
were observed in Jerseys for all three forages. Differences were more apparent for wheat
straw and treated wheat straw than for lucerne. The rate of passage of digesta from the rumen
was measured in both breeds by a chromium mordanted wheat straw marker. The Holsteins
manifested a higher rate of passage (P<0.05) than the Jerseys, while daily feed intakes were also higher (P<O.Ol) for the Holsteins than for the Jerseys. Daily feed intake, expressed as
percentage of body weight was, however, slightly higher for the Jerseys than for the
Holsteins. The pH value of the rumen fluid was measured at 0, 4, 8, 10 and 12 hours postfeeding.
The only significant difference (P<O.OI)in pH between the breeds was at 4 hours
post-feeding, when the ruminal pH dropped more rapidly in the Holsteins than in the Jerseys.
The pH in the Holsteins dropped below 6.2, which may have inhibited fibrolytic microbe
activity in the rumen, resulting in a lower effective degradability of forages. Total volatile
fatty acids were higher in Holsteins from four to 10 hours after feeding, but no differences
were observed in acetic acid:propionic acid ratios. It was concluded that Jerseys appear to
utilize forages more efficiently than Holsteins and that the differences are more apparent in
low quality forages than in high quality forages. / AFRIKAANSE OPSOMMING: Statistiese analises is op data van twee kuddes te Elsenburg uitgevoer, bestaande uit 105
Jersey- en 232 Holsteinkoeie. Die data is ondersoek vir eksterne faktore wat melkproduksie
en melksamestelling kan beinvloed. Die data het uit 337 eerste-laktasierekords bestaan, wat
oor 'n periode van 20 jaar ingesamel is. Ras van die koei, sowel as die jaar van geboorte en
ouderdom met eerste kalwing het 'n invloed op melkproduksie, bottervet- en proteienopbrengs
gehad. 'n Betekenisvolle interaksie is tussen ras en jaar van geboorte waargeneem.
Ander moeilik kwantifiseerbare faktore mag ook 'n invloed op melkproduksie he. In
daaropvolgende proewe is agt rumen-gekannuleerde melkkoeie (vier Jerseys en vier
Holsteins) gebruik om die invloed van ras op ruvoerverteerbaarheid in die rumen te bepaal.
Al die koeie het 'n hoe-kragvoerdieet ontvang, aangevul met koringstrooi. 'n In situ
rumendegradeerbaarheidstudie is met drie verskillende ruvoere, naamlik lusernhooi,
koringstrooi en NaOH-behandelde koringstrooi uitgevoer. Die ruvoere is vir tye van 2, 4, 8,
12, 16, 20, 24, 36, 48, 72 en 96 ure in die rumen geinkubeer en monsters is ontleed vir
droemateriaal (DM) en neutraal-bestande vesel (NDF). Hoer rumen-degradeerbaarheidswaardes
(P<O.Ol) van DM en NDF is in Jerseys waargeneem as in Holsteins vir al drie
ruvoere. Verskille was meer opvallend vir koringstrooi en NaOH-behandelde koringstrooi as
vir lusem. Uitvloeitempo van digesta uit die rumen is in beide rasse met behulp van
chroomgemerkte koringstrooi bepaal. Hoer uitvloeitempo's is in die Holsteins waargeneem
as in die Jerseys, terwyl daaglikse voerinnames ook hoer was (P<O.05) by die Holsteins as by die Jerseys. Daaglikse voerinname, uitgedruk as persentasie van liggaamsmassa, was egter
effens hoer (P<O.OI)by die Jerseys as by die Holsteins. Die pH van die rumenvloeistof is op
0, 4, 8, 10 en 12 ure na voeding gemeet. Die enigste betekenisvolle verskil (P<O.OI)in pH
tussen die rasse het op 4 ure na voeding voorgekom toe die pH van die rumeninhoud vinniger
in die Holsteins as in die Jerseys gedaal het. Die pH in die Holsteins het onder 6.2 gedaal,
wat moontlik fibrolitiese mikrobe-aktiwiteit in die rumen kon inhibeer, met 'n gevolglike
daling in effektiewe degradeerbaarheid van die ruvoere. Vanaf 10 ure na voeding was die
totale vlugtige vetsuurkonsentrasies hoer in die Holsteins, maar geen verskille in
asynsuur:propionsuurverhoudings is waargeneem nie. Die gevolgtrekking is gemaak dat
Jerseys skynbaar meer doeltreffend is om ruvoere te benut as Holsteins en dat die verskil
tussen rasse meer opvallend is vir lae kwaliteit ruvoere as vir hoe kwaliteit ruvoere.
|
7 |
Studies on the nutritive value of lucerne for dairy cowsDu Toit, Francois (Francois Johannes) 12 1900 (has links)
Thesis (MScAgric)--University of Stellenbosch, 2001. / ENGLISH ABSTRACT: An experiment was conducted to determine whether the quality of lucerne hay could be
improved by artificial drying in a forced air bulk dryer (FABD) in comparison to lucerne
hay produced by natural drying in the field. Lucerne fields were divided into four blocks
of equal size and blocks were randomly assigned to each of the two treatments (natural or
artificial drying). Lucerne was harvested at an early to mid flowering stage on six
occasions. In two blocks, cut lucerne was left in the field to dry. Material in the
remaining two blocks were left in the field for an initial drying period of no longer than
24 hours, after which it was transferred to a FABD. Samples oflucerne were taken at the
time of harvest and then at regular intervals (on average 0, 4, 8,22,26,29,47,50,53, 56,
58,69, 72, 76 and 80 hours after cutting) in the field and in the FABD until the material
was dry enough for baling (ca. 15-18% moisture). Collected lucerne samples were dried
in a forced draught oven until constant mass to determine moisture content. The rate of
moisture loss was compared. Samples of the lucerne hay in the field and in the FABD
were taken after baling to determine forage quality by means of chemical analysis.
Samples were analysed for crude protein (CP), total digestible nutrients (TDN), digestible
organic matter (DOM), acid detergent fibre (ADF) and neutral detergent fibre (NDF)
content. Good weather conditions for natural drying during the trial period resulted in
lucerne hay of similar chemical composition. Naturally dried lucerne hay had CP, ADF
and NDF contents of 17.3, 41.2 and 48.0%, respectively, while values for artificially
dried lucerne were 17.6, 40.6 and 47.3%. It was concluded that artificial drying of
lucerne does probably not produce lucerne of a better quality than field drying under
good weather conditions.
In the following trials eight ruminally cannulated cows (four Jerseys and four Holsteins)
were used to compare protein and fibre degradability of lucerne harvested at different stages of maturity (ie. 4, 5 and 6 weeks' regrowth), and of different lucerne products (ie.
lucerne hay, lucerne leaves and 8% leaves added to hay), dried in a forced air bulk dryer.
All cows received a total mixed lactation diet for the duration of the trial period. The first
in situ rumen degradability trial was conducted with lucerne harvested at three stages of
maturity namely after 4,5 and 6 weeks' regrowth. Bags were incubated in the rumen for
time intervals of 0, 2, 4, 8, 16, 24, 48 and 72 hours. Samples were analysed for dry matter
(DM), crude protein (CP) and neutral-detergent fibre (NDF) content.
The effective DM, protein and NDF degradabilities of lucerne hay did not differ (P>0.05)
between Holstein and Jersey cows. In Holsteins, DM degradability values calculated at
an outflow rate of 0.05/h for lucerne harvested after 4, 5 and 6 weeks' regrowth were
63.1, 57.1 and 55.0%, respectively. Values of 64.6, 58.6 and 55.7% were obtained in
Jerseys. CP degradability values for lucerne harvested after 4, 5 and 6 weeks' regrowth
were 81.7, 77.2 and 77.6% in Holsteins and 81.3, 78.2 and 79.4% in Jerseys. NDF
degradability values for lucerne harvested after 4, 5 and 6 weeks' regrowth were 35.8,
45.5 and 23.2% respectively in Holsteins and 35.1, 45.9 and 24.8% in Jerseys.
Analysis of the effective DM, protein and NDF degradabilities across breeds indicated
differences between lucerne harvested after 4, 5 and 6 weeks' regrowth. Rumen
degradability of DM and protein was the highest for lucerne harvested after 4 weeks'
regrowth. DM degradability values oflucerne harvested after 4,5 and 6 weeks' regrowth
calculated at a flow rate of 0.05/h were 63.9, 57.9, 55.4%, respectively, while protein
degradability values were 81.5, 77.7 and 78.5%. The lowest ruminal NDF degradability
values were found for lucerne harvested after 6 weeks' regrowth. Values for NDF
degradability calculated at a flow rate of 0.05/h for lucerne harvested after 4, 5 and 6
weeks' regrowth were 35.5, 45.7 and 23.7%, respectively. These results indicated that
lucerne quality decreased in terms of DM, protein and NDF degradability as the plants
mature.
The second in situ rumen degradability trial was conducted with three different lucerne
components dried in a forced air bulk dryer, namely lucerne hay, lucerne leaves and
lucerne hay + 8% leaves. The procedure followed was the same as in the first in situ trial. Dacron bags, containing samples of the lucerne components were incubated in the rumen
for time intervals of 0, 2, 4, 8, 16,24,48 and 72 hours. Samples were also analysed for
DM, CP and NDF content and compared both between breeds and across breeds.
DM and protein degradability values (rate and effective degradability) of the artificially
dried lucerne hay were higher in Jerseys than in Holsteins. DM degradability values
calculated for Holsteins at a flow rate of 0.05/h for lucerne hay, lucerne leaves and
lucerne hay + 8% leaves were 57.6, 66.5 and 61.4%, respectively, while protein
degradability values of 76.9, 75.5 and 77.9% were obtained. DM degradability values
calculated for Jerseys were 62.9, 69.1 and 61.7%, respectively, while protein
degradability values of 82.4, 77.6 and 78.5% were obtained.
Analysis of the mean disappearance values across breeds indicated that protein
degradability of lucerne hay in the rumen was higher than that of lucerne leaves. Protein
degradability values calculated at a flow rate of 0.05/h for lucerne hay and lucerne leaves
were 80.1 and 76.5% respectively. The NDF degradability of lucerne hay was, however,
lower than what it was for lucerne leaves (24.6 vs. 29.7%). / AFRIKAANSE OPSOMMING: Studies omtrent die voedingswaarde van lusern vir
melkkoeie. 'n Eksperiment is uitgevoer om te bepaal of die kwaliteit van lusernhooi verbeter kan
word deur gebruik te maak van kunsmatige droging in plaas van die tradisionele
landdroging. Lusernlande is in vier blokke verdeel en blokke is ewekansig aan elk van
die twee behandelings (kunsmatige en landdroging) toegeken. Gesnyde materiaal in twee
van die blokke is op die land gelaat vir die duur van die drogingsproses. Die materiaal in
die oorblywende twee blokke is op die land gelaat vir 'n aanvanklike drogingsperiode
van maksimum 24 uur, waarna dit in 'n massa-droogoond geplaas is. Lusernmonsters is
net na sny op die land geneem en daarna met gereelde (gemiddeld 4,8,22,26,29,47,50,
53, 56, 58, 69, 72, 76 en 80 uur na sny) intervalle op die land en in die droër totdat die
materiaal droog genoeg was om te baal. Lusernmonsters is in 'n droogoond gedroog
totdat 'n konstante massa bereik is vir die bepaling van die voginhoud van die materiaal.
Die tempo van vogverlies van die materiaal in die massadroër en op die land is bepaal.
Monsters van die lusernhooi wat op die land en in die oond gedroog is, is na baal geneem
en die chemiese samestelling van die lusernhooi is bepaal. Monsters is ontleed vir
ruprotein- (RP), totale verteerbare voedingstof- (TVV), verteerbare organiese materiaal-
(VOM), suur bestande vesel (SBV) en neutraal bestande vesel (NBV)-inhoud.
Weersomstandighede was ideaal vir natuurlike droging van lusern en dit het aanleiding
gegee daartoe dat die chemiese samestelling van die kunsmatig- en natuurlik gedroogde
lusernhooi nie veel verskil het nie. Die RP, ADF en NDF inhoud van natuurlik
gedroogde lusernhooi was 17.3,41.2 en 48.0% terwyl waardes van 17.6,40.6 en 47.3%
vir kunsmatig gedroogde lusernhooi verkry is. Daar is bevind dat die kunsmatige droging
van lusern nie 'n hoër kwaliteit hooi lewer as wat verkry kan word tydens landdroging
wanneer weersomstandighede gunstig is nie. Hierna is twee degradeerbaarheidstudies gedoen. Agt koeie (vier Holsteins en vier
Jerseys) met rumenkannulas, is gebruik om die proteïen- en veseldegradeerbaarheid van
verskillende lusernkomponente te vergelyk. Lusern op verskillende groeistadia gesny,
asook verskillende lusernprodukte wat kunsmatig gedroog is, is vergelyk. Al die koeie
het gedurende die proeftydperk 'n hoë-konsentraat laktasierantsoen ontvang.
Die eerste in situ degradeerbaarheidstudie is gedoen met lusern wat na 4-, 5- en 6 weke
hergroei gesny is. Sakkies met lusernmonsters is in die rumen geplaas vir 0, 2, 4, 8, 16,
24,48 en 72 uur onderskeidelik. Monsters is na inkubasie in die rumen vir die DM-, RPen
NBV -inhoud daarvan ontleed.
Daar is bevind dat die DM-, proteïen en NBV degradeerbaarhede van lusernhooi nie
verskil het (P.0>05) tussen Holstein- en Jerseykoeie nie. DM degradeerbaarhede wat by
'n deurvloeitempo van 0.05/h in Holsteinkoeie bereken is vir lusern wat na 4-,5- en 6
weke hergroei gesny is, was onderskeidelik 63.1, 57.1 en 55.0%. Die waardes wat vir
Jerseys bereken is, was onderskeidelik 64.6,58.6 en 55.7%. Vir lusern wat na 4-,5- en 6
weke hergroei gesny is, was RP degradeerbaarhede 81.7, 77.2 en 77.6%, onderskeidelik,
vir Holsteinkoeie en 81.3, 78.2 en 79.4%, onderskeidelik, vir Jerseys. NDFdegradeerbaarhede
vir lusern wat na 4-,5- en 6 weke hergroei gesny is, was 35.8,45.5 en
23.2%, onderskeidelik, vir Holsteins en 35.1, 45.9 en 24.8%, onderskeidelik, vir Jerseys.
'n Vergelyking van die DM-, proteïen- en NBV-degradeerbaarhede wat gedoen is met die
saamgevoegde data van al die diere, het daarop gedui dat verskille bestaan tussen die
lusern wat na 4-, 5- en 6 weke hergroei gesny is. Die lusern wat na 4 weke hergroei
gesny is, het die hoogste DM- en proteïendegradeerbaarheid in die rumen getoon. DMdegradeerbaarhede
wat bereken is teen 'n deurvloei tempo van 0.05/h vir lusern wat na 4,
5- en 6 weke hergroei gesny is, was onderskeidelik 63.9,57.9 en 55.4% en proteindegradeerbaarhede
was 81.5, 77.5 en 78.5%. Lusern wat na 6 weke hergroei gesny is het
die laagste NDF-degradeerbaarheid gehad. Waardes wat bereken is teen 'n
deurvloeitempo van 0.05/h vir lusern wat na 4-,5- en 6 weke hergroei gesny is, was
onderskeidelik 35.5, 45.7 en 23.7%. Hierdie resultate dui daarop dat die kwaliteit van lusern afneem in terme van DM-, protein- en NBV-degradeerbaarhede namate die plante
meer volwasse raak.
Die tweede rumendegradeerbaarheidstudie is gedoen met 3 lusernprodukte wat in 'n
massadroër gedroog is nl. lusernhooi, lusernblare en lusernhooi waarby 8% lusernblare
gevoeg is. Dieselfde proefprosedure as tydens die eerste degradeerbaarheidstudie is
gevolg. Sakkies met lusernmonsters, is in die rumen geplaas vir 0, 2, 4, 8, 16, 24, 48 en
72 uur. Monsters is ontleed vir DM-, proteïen- en NBV inhoud.
Daar is gevind dat die proteïen degradeerbaarheid (tempo en effektiewe
degradeerbaarheid) van kunsmatig gedroogde lusernhooi, hoër was by Jerseys as by
Holsteins. DM degradeerbaarhede wat in Holsteinkoeie teen 'n deurvloeitempo van
0.05/h bereken is vir lusernhooi, lusernblare en lusernhooi + 8% blare, was 57.6, 66.5 en
61.4%, onderskeidelik, terwyl proteïen degradeerbaarhede 76.9, 75.5 en 77.9%,
onderskeidelik, was. Vir Jerseys is DM-degradeerbaarhede van 62.9,69.1 en 61.7%,
onderskeidlik, bereken terwyl proteïendegradeerbaarhede 82.4, 77.6 en 78.5% was.
Gemiddelde verdwyningswaardes, wat bereken is deur data van al die diere saam te
gebruik, dui daarop dat die proteïen degradeerbaarheid van lusernhooi in die rumen hoër
was as in die geval van lusernblare. Die proteïen degradeerbaarhede wat bereken is teen
'n deurvloeitempo van 0.05/h, was 80.1 en 76.5%, onderskeidelik, vir lusernhooi en
lusernblare. Die NBV -degradeerbaarheid van lusernhooi was egter laer as vir lusernblare
(24.6 vs. 29.7%).
|
8 |
The effect of oat silage replacement with wheat straw in dairy cow diets on animal performance, rumen fermentation and adequacy of CPM dairy model predictionsSwiegers, Johannes Pieter 12 1900 (has links)
Thesis (PhDAgric (Animal Sciences))--Stellenbosch University, 2011. / ENGLISH ABSTRACT: A series of experiments were conducted to determine the effect of the replacement of oat
silage by wheat straw in low forage diets for high producing dairy cows. In the first trial, 28
multiparous Holsteins were randomly assigned to two dietary treatments, namely silage and
straw after completing a covariate period coinciding with the first 40 days of lactation and
remained on these diets for the remainder of experimental period from 41 to 252 days. In
order to evaluate the effect of substitution during different stages of lactation, the
experimental period was divided into four phases. Diets were formulated to support similar
levels of milk for both treatment groups and for all phases. The substitution of oat silage by
wheat straw had a negative effect on dry matter intake, milk production and composition, as
well as on feed and nitrogen efficiency, but had no effect on body weight and body condition.
A rumen fermentation trial was also done, where six multiparous cannulated cows were
randomly allocated in a changeover design to the same dietary treatments used in the
animal performance trial. Despite a relatively low peNDF content and high NFC content of
the diets, the mean rumen pH and time spent below pH 5.8 indicated that cows were actually
not subjected to subclinical rumen acidosis, probably due to effective chewing activity.
Forage source had no significant effect on rumen fermentation end products or mean daily
rumen pH. However, the time spent below pH 5.8 was significantly lower for cows in the
silage treatment than for those in the straw treatment, which could be related to a longer
chewing time and more effective chewing activity that was observed on the straw treatment.
Cows on the straw treatment sorted less against the medium sized particles, which was not
expected, since straw inclusion is normally associated with a higher degree of sorting. In a
third experiment, the effect of the replacement of silage by wheat straw was evaluated in
terms of pre and postpartum animal performance. Dry cow diets were formulated with the
objective to restrict intake, thus preventing cows from consuming metabolizable energy in
excess of their requirements. Both treatments were successful in controlling intake and the replacement of oat silage by wheat straw in dry cow diets had no apprent effect on
postpartum animal performance. Using the data from the lactation experiment, the adequacy
of the CPM Dairy model to predict animal performance from low forage diets was also
evaluated. The model was highly accurate in predicting adjusted milk production of cows
consuming oat silage as basal forage, with a mean bias of only 0.05 kg milk/d, but it overpredicted
milk production of cows receiving diets with wheat straw as the sole forage source,
with a mean bias overprediction of 2.3 kg milk per day during the corresponding period of
positive energy balance. Overprediction of energy balance from straw was confirmed in the
dry cow experiment where a statistical analysis of the residuals between predicted and
actual body condition score change indicated an overprediction on the straw treatment. / AFRIKAANSE OPSOMMING: Die invloed van die vervanging van hawerkuilvoer deur koringstrooi in diëte vir
hoogproduserende melkkoeie is in ‘n reeks proewe nagegaan. In die eerste proef is 28
volwasse Holsteinkoeie ewekansig aan ‘n kuilvoer- of strooigebaseerde behandeling
toegeken na die voltooiing van ‘n kovariaatperiode van 40 dae. Ten einde die invloed van
die behandeling tydens verskillende stadia van laktasie te evalueer, is die proefperiode in
vier fases verdeel. Diëte is geformuleer om vergelykbare melkproduksies vir beide
behandelings tydens al die fases te ondersteun. Vervanging van hawerkuilvoer deur
koringstrooi het ‘n negatiewe invloed op droëmateriaalinname, melkproduksie, melksamestelling,
voeromset en stikstofbenutting gehad, maar geen invloed op ligaamsmassa- en
kondisieverandering nie. In ‘n rumenfermentasieproef is ses volwasse, gekannuleerde
Holsteinkoeie in ‘n omswaai-ontwerp aan twee diëte, soortgelyk aan dié wat tydens die
laktasieproef gebruik is, in toegewys. Ten spyte van ‘n relatief lae peNDF-inhoud en ‘n
relatief hoë NFC-inhoud van die diëte was daar, te oordeel aan die gemiddelde rumen pH
en tyd waartydens die rumen pH onder 5.8 was, geen aanduiding van subkliniese rumenasidose
nie, waarskynlik as gevolg van ‘n langer kou-tyd en meer doeltreffende kouaktiwiteit.
Ruvoerbron het skynbaar ook geen invloed op rumenfermentasie-eindprodukte en
gemiddelde rumen pH gehad nie. Die periode waartydens rumen pH laer as 5.8 was, was
egter korter vir koeie in die kuilvoerbehandeling as vir dié in die strooibehandeling. Dit kan
waarskynlik aan meer doeltreffende herkou-aktiwiteit toegeskryf word. Aangesien strooiinsluiting
in herkouerdiëte normaalweg met ‘n groter mate van voerseleksie geassosieer
word, was die kleiner mate van seleksie teen mediumgrootte partikels met die
strooibehandeling verrassend. In ‘n derde proef is die invloed van van die vervanging van
kuilvoer met koringstrooi in terme van pre- en postpartum diereprestasie ondersoek.
Droëkoeidiëte is geformuleer met die doel om inname te beperk en koeie sodoende te verhoed om meer metaboliseerbare energie in te neem as wat hulle benodig. Albei
behandelings was doeltreffend om inname te beheer en die vervanging van hawerkuilvoer
met koringstrooi het geen invloed op postpartum diereprestasie gehad nie. Deur van die
data van die laktasieproef gebruik te maak, is die toereikendheid van die CPM Dairy model
om diereprestasie vanaf lae ruvoerdiëte te voorspel, ook bepaal. Die model was hoogs
akkuraat in die voorspelling van melkproduksie in die geval van die kuilvoerbehandeling,
maar dit het melkroduksie met 2.3 kg/dag oorskat in die geval van die koringstrooibehandeling.
Hierdie oorberaming van energiebalans is tydens die droëkoeiproef bevestig.
|
9 |
Endocrine changes associated with the effect of nutrition on the timing of reconception and puberty in dairy cattleLuna, Gonzalo 26 February 2007 (has links)
Please read the abstract in the section 00front of this document / Dissertation (MSc (Agric))--University of Pretoria, 2007. / Animal and Wildlife Sciences / unrestricted
|
10 |
Effects of live yeast, monensin and concentrate level in dairy cattle diets on gas and volatile fatty acids productionMokatse, Brenda 14 September 2015 (has links)
Two meta-analysis of effects of yeast culture and monensin in lactating dairy cows were first performed. Secondly, two experiments were performed to evaluate the effects of live yeast (LY) or monensin (M) or both (LY+M) on gas production and fermentation by rumen micro-organisms in vitro in low (40 %) and high (60 %) concentrate diets of dairy cows. Rumen contents were collected from one cannulated lactating Holstein cow. Gas production was measured from 0 to 48 h of incubation. Volatile fatty acids and ammonia nitrogen concentrations were measured after 48 h. Meta-analysis of monensin indicated decrease dry matter intake (DMI) and increasing milk yield, consequently improving feed efficiency. Meta-analysis of yeast culture did not show improved performance. These results highlighted the importance of the meta-analysis as a useful tool that can be employed to both summarize effects across studies and to investigate factors explaining potential heterogeneity of response. The batch fermentation showed that in high concentrate diet, M significantly increased ammonia nitrogen, decreased acetate, but tended to increase propionate concentration (7.9, 63.2, 18.6 vs. 6.3, 66.8, 14.2 mmol/l; respectively). Addition of LY increased acetate concentration (64.2 vs 66.8 mmol/l). Supplementation with M, LY and LY+M reduced total gas production by 37.1, 22.5 and 26.9 %, respectively, compared to control at 48 h. In low concentrate diet, M and LY+M decreased and increased acetate (60.1 and 69.7 vs. 7.1 mmol/l; respectively). Adding LY and LY+M produced 8.6 % less gas, and M treatment 3.4 % more gas than the control. Overall, at 48 h, high concentrate resulted in less gas than low concentrate diets. High concentrate diets showed increased ammonia (7.9 and 6.4 vs. 5.21 and 4.7 mmol/l) decreased acetate (63.0 and 63.2 vs. 67.0 and 69.7 mmol/l) with a tendency to increased propionate (18.6 and 18.9 vs. 14.6 and 14.1 mmol/l) compared to low concentrate in M and LY+M treated diets. These results indicate that the effects of M and LY on rumen fermentation are substrate dependent, the high-concentrate diet showing the greatest response / Agriculture / M. Sc. (Agriculture)
|
Page generated in 0.0817 seconds