Thesis (MScAgric)--Stellenbosch University, 2001. / ENGLISH ABSTRACT: The goat is a significant domestic animal throughout the world today. With an estimated world goat
population of 590 million goats in 1991 (FAO, 1991 as citied by Haenlein, 1996) it is impossible to
consider the goat as insignificant. The need for milk, and it seems particularly goat’s milk, is obvious
if one considers the increase in dairy goat populations over the past 20 years. Across the globe the
dairy goat population has increased by 52% while in developing and developed countries, there has
been an increase of 56% and 17%, respectively (Haenlein, 2000).
The goat dairy industry in South Africa is still very underdeveloped, yet it holds tremendous potential
for the entrepreneur willing to take the risk and do the job correctly. With the present South African
financial situation the opportunities that exist for exporting value added products to countries with
stronger currencies is a market with extraordinary potential. In New Zealand, the national herd
consists of approximately 16000 dairy goats and 90% of the milk produced is turned to powdered milk
and then exported to the East, a valuable source of foreign currency. In South Africa, the same
potential exists and with some vision and hard work the dairy goat industry can make a valuable
contribution to generating foreign currency.
Research into the protein requirements and particularly protein degradability requirements of dairy
goats is scarce, yet in recent years there has been an increased interest in the effect of protein
supplementation to lactating animals (Mishra & Rai, 1996). In the work of Mishra & Rai (1996) there
were benefits obtained from the use of different rumen degradable proteins for lactating dairy goat
does. The does on the highly degradable protein diet had a better feed intake while the does on the
low degradable protein diet gave a higher milk production. Other research on this field of study has
also delivered positive results with more than one species of lactating animal that had increased
levels of UDP in the diet (Robinson et al., 1991 and Christensen et al., 1993).
Loerch et al. (1995) suggested that improved production by making use of rumen undegradable
proteins would have no effect if crude protein were not a limiting factor in production. Pailan & Kaur
(1995) and Mishra & Rai (1996) did research on lowered CP levels with increased UDP levels in
lactating dairy does. They used of three diets, with the one having a 20% lower CP value but an increased level of UDP (40-45% of total CP). From this work it was concluded that a decreased CP
level and an increased level of UDP is able to sustain production when compared with diets with a
higher CP value.
The current study consists of two trials. In the first trial the effect of weaning age and dietary protein
degradability on the growth of Saanen kids was investigated. In the second trial the effect of dietary
protein degradability on the production of lactating Saanen does was investigated.
Fifty-eight Saanen kids were divided into groups to determine the effect of weaning age (42 vs. 70
days) on animal performance. Within the weaning day treatments, the kids were again divided into
two dietary treatments. One group received a low UDP creep diet (LC) and the other a high UDP
creep diet (HC). The two creep diets were formulated with rumen degradable: undegradable protein
(RDP : UDP) ratios of 70:30 and 60: 40, referred to as LC and HC, respectively. However, the results
from the degradability trial indicated no difference in RDP: UDP ratios for the low and high creep
(72:28 and 73:27 respectively) diets. At 15.66 ± 3.09 kg the kids were taken off the creep diet and
put on the growth diet. At this transition, the kids in each of the 4 established treatments were again
randomly divided into two dietary treatments, a high or a low UDP growth diet, resulting in a total of
eight treatments for the trial. The two growth diets were formulated with RDP: UDP ratios of 70:30
and 60:40, referred to as low growth (LG) and high growth (HG) respectively. Results from the
degradability trial indicated RDP: UDP ratios for the LG and HG of 73:27 and 68:32 respectively. The
growth trial was conducted over 140 days and feed intake, bodyweight change and feed conversion
efficiency were compared for each of the 8 treatments.
From the trial with the Saanen kids it was concluded that weaning dairy goat kids at 42 days of age
when feed intake was 240 g/day resulted in similar growth rates when compared with weaning at 70
days. The two creep diets did not differ in RDP: UDP ratios and thus no conclusion can be made
regarding the influence of the creep diets on the growth of Saanen kids from 20 to 80 days of age.
The two growth diets did in fact differ from one another, in terms of RDP: UDP however, protein
degradability had no influence on the performance of the Saanen kids from 80 to 140 days of age.
Twenty-one lactating Saanen does were randomly assigned to one of three experimental diets. The
treatments had two RDP: UDP ratios and two crude protein (CP) levels. Treatments were formulated
to be 1) RDP: UDP = 70:30, CP = 20 % 2) RDP: UDP = 62:38, CP = 20% and 3) RDP: UDP = 62:38,
CP = 18.3%. In the production trial the does were milked for 120 days, during which milk yield, milk
composition, bodyweight change, feed intake and feed conversion efficiency were compared between
the treatments. In the digestibility and nitrogen metabolism trial, 18 does varying from 84 to 110 days in lactation, were used to compare the experimental diets. Furthermore, the experimental diets were
compared in a degradability and rate of passage trial using cannulated Dohne merino wethers.
Results from the degradability trial indicated that the low UDP, low protein high UDP and high UDP
diets had RDP: UDP ratios of 82:18, 78:22 and 79:21 respectively, and that the dietary protein
degradability did not differ significantly between diets. Results from the production trial indicated that
there was a significant difference in feed intake, dry matter (DM) intake and bodyweight. The does on
the low UDP diet had significantly higher feed intakes and DM intakes and were significantly heavier
at the end of the trial period. As the diets didn’t differ in protein degradability other factors must have
influenced the intakes between diets. Palatability may have influenced feed and DM intake, as the
low protein high UDP and high UDP diets both contained higher levels of fishmeal. No significant
differences in milk production, milk composition or milk production efficiency were observed. Besides
the fact that the diets did not differ in effective protein degradability, large variations in milk production
between animals and low numbers of animals per treatment limited the ability to measure a difference
between the treatments. Results from the digestibility trial varied between diets with the low UDP diet
having a significantly lower digestibility overall than the other two diets. Reasons for the difference in
digestibility could be due to the difference in rate of passage (low UDP = 0.064/hour versus the 0.044-
0.045/hour of the low protein and high UDP diets respectively) and the high ADF value of the low
UDP diet. Because no difference in effective protein degradability existed between the diets it is not
possible to make an accurate conclusion on whether or not the dietary protein degradability had an
influence on production parameters tested in this trial. / AFRIKAANSE OPSOMMING: Huidiglik is die bok ‘n belangrike gedomestikeerde dier dwarsoor die wereld. Aangesien die
wereldwye bokpopulasie in 1991 op 590 miljoen geraam is (FAO, soos aangehaal deur Haenlein,
1996), is dit onmoontlik om die bok as onbelangrik te beskou. Die behoefte aan melk, en dan veral
bokmelk, is duidelik as mens die toename in bokpopulasies oor die afgelope 20 jaar in ag neem.
Wereldwyd het die melkbokpopulasie met 52% toegeneem, terwyl dit in ontwikkelende en
ontwikkelde lande met 56% en 17% onderskeidelik, toegeneem het (Haenlein, 2000).
Ten spyte van die feit dat die bokmelk-industrie in Suid-Afrika nog baie onderontwikkel is, is daar
geweldige potensiaal vir die entrepeneur wat bereid is om ‘n risiko te loop en die taak korrek aan te
pak. Binne die huidige Suid-Afrikaanse finansiele situasie bestaan daar veral geleenthede om
waardetoegevoegde produkte na lande waarvan die wisselkoers sterker is, uit te voer. In Nieu
Zeeland is die nasionale kudde ongeveer 16000 melkbokke en 90% van die geproduseerde melk
word verwerk na poeiermelk en uitgevoer na die Ooste. In Suid-Afrika bestaan dieselfde potensiaal
en met die korrekte visie en harde werk kan die melkbok-industrie ‘n belangrike bydra lewer om
buitelandse valuta te verdien.
Alhoewel navorsing aangaande die proteien-degradeerbaarheidsbehoeftes van melkbokke skaars is,
bestaan daar die afgelope paar jaar ‘n toenemende belangstelling in die effek van proteien
supplementering aan lakterende diere (Mishra & Rai, 1996). In die werk van Mishra & Rai (1996) is
die voordele om verskillende rumen degraderende proteTenvlakke in lakterende melkbokke te
gebruik, aangetoon. Ooie op ‘n hoogs degradeerbare prote'fen-dieet het beter voerinnames getoon,
terwyl die ooie op ’n laag degradeerbare prote'fen-dieet hoer melkproduksies gelewer het. Navorsing
van hierdie aard op ander lakterende spesies het ook positiewe resultate met ‘n toename in
verbyvloeiprote'ien in die dieet gelewer (Robinson et al., 1991 en Christensen et al., 1993).
Loerch et al. (1995) het voorgestel dat ‘n verbeterde produksie, deur gebruik te maak van
verbyvloeiprote'fn, geen effek sal he as ruprote'fen (RP) nie ‘n beperkende faktor i.t.v produksie is nie.
Beide Pailan & Kaur (1995) & Mishra en Rai (1996) het navorsing gedoen op die invloed van verlaagde RP-vlakke en verhoogde nie-degradeerbare protein (NDP) vlakke in die diete van
lakterende melkooie. Daar is gebruik gemaak van drie diete, waarvan die een dieet ‘n 20% laer RPinhoud,
maar ‘n verhoodge NDP-vlak (40-45% van totale RP) gehad het. Vanuit hierdie werk is die
gevolgtrekking gemaak dat ‘n verlaging in RP-vlak en ‘n verhoging in NDP-vlak dieselfde produksie
kan onderhou, soos met ‘n hoer RP-inhoud.
Die huidige navorsing bestaan uit twee proewe. In die eerste proef is die effek van speenouderdom
en dieet-prote'fen-degradeerbaardheid op die groei van Saanen-lammers ondersoek. In die tweede
proef is die effek van dieet-proteien-degradeerbaardheid op die produksie van lakteerende Saanen
melkbokke ondersoek.
Agt-en-vyftig Saanen-lammers is verdeel in twee speenouderdom-behandelings, nl. ‘n 42 dae (42) en
‘n 70 dae (70) speenouderdom. Binne hierdie speenouderdom-behandelings is die lammers verder
verdeel in twee dieet-behandelings. Die een groep het ‘n lae NDP kruiprantsoen (LK) en die ander ‘n
hoe NDP kruiprantsoen (HK) ontvang. Die twee kruiprantsoene was geformuleer om rumen
degradeerbare proteien (RDP): NDP verhoudings van 70:30 (LK) en 60:40 (HK) te bevat, maar die
resultate van die degradeerbaarheidsproef het aangetoon RDP: NDP verhoudings van 77:23 (LK) en
78:22 (HK). Die lammers is vanaf die kruipdieet oorgeplaas op ‘n groeidieet by ‘n gemiddelde
lewende massa van 15.99±3.09 kg. Tydens hierdie oorplasing is die lammers van die vier bestaande
behandelings verdeel in ‘n verdere twee dieetbehandelings, nl. ‘n hoe of ‘n lae NDP groei-dieet (LG
en HG onderskeidelik), met die gevolg dat ‘n totaal van agt behandelings in hierdie proef bestaan het.
Die twee groeidiete is geformuleer met RDP: NDP verhoudings van 70: 30 (LG) en 60: 40 (HG)
onderskeidelik, maar die resultate van die degradeerbaarheidsproef het aangetoon RDP: NDP
verhoudings van 78:22 (LG) en 72:28 (HG). Die groeiproef is uitgevoer oor 140 dae en voerinname,
verandering in liggaamsgewig en voeromsettingsdoeltreffendheid (VOD) is vergelyk tussen die agt
behandelings.
Uit die lammerproef is die gevolgtrekking gemaak dat boklammers wat op 42 dae gespeen is,
wanneer voerinname 240g/dag is, soortgelyke resultate i.t.v. groeitempo lewer as lammers wat op 70
dae gespeen is. Die twee kruiprantsoene het nie van mekaar in RDP: NDP verskil nie en dus kan
geen gevolgtrekking gemaak word omtrentdie invloed van dieet-protel'en-degradeerbaarheid op die
groei van Saanen boklammers van 20 tot 80 dae ouderdom. Die twee groei diete het van mekaar
verskil in RDP: NDP maar dieet-proteien-degradeerbaardheid het geen invloed op die groei van die
Saanen boklammers van 80 tot 140 dae ouderdom gehad nie.
Een-en-twintig lakterende Saanen-ooie is ewekansig in drie groepe. Die behandelings het twee RDP:
NDP-verhoudings en twee ruprotei'en (RP) -peile ingesluit. Behandelings was 1) RDP: NDP = 70:30, RP = 20% 2) RDP: NDP = 62:38, RP = 20% en 3) RDP: NDP = 62:38, RP = 18.3%. Tydens hierdie
produksieproef is die ooie vir 120 dae gemelk en die melkopbrengs, melksamestelling, verandering in
liggaamsgewig, voerinname en VOD bepaal en vergelyk tussen behandelings. In die verterings- en
stikstofmetabolismeproef is 18 ooie gebruik om die diete te vergelyk. Verder is die diete ook vergelyk
in ‘n degraderings- en deurvloeitempoproef met gekannuleerde Dohne merino hamels.
Dieet-proteien-degradeerbaardheid waardes verkry uit die degradeerbaarheidsproef het aangedui dat
die bepaalde RDP: NDP verhoudings was 82:18, 78:22 en 79:21 vir die lae NDP, lae prote'fen hoe
NDP en hoe NDP diete, en dat daar geen verskil in dieet-prote'fen-degradeerbaardheid was tussen
die drie rantsoene. Resultate van die produksieproef dui daarop dat daar verskille in voerinname,
droematerialinname, en liggaamsgewig tussen die drie rantsoene was. Die ooie op die laer NDP
rantsoen het ‘n hoe voer en DM inname gehad en was swaarder na 120 dae in die proef as die ooie
in die ander twee behandelings. Redes vir hierdie verskille is nie as gevolg van dieet-proteiendegradeerbaarheid
nie. Die smaaklikheid kon dalk ‘n rol gespeel het omdat dat die twee hoe NDP
rantsoene hoer vlakke van vismeel gehad het. Daar was geen verskil in melkproduksie,
melksamestelling en melkproduksiedoeltreffenheid tussen die drie behandelings. Resultate van die
verteringsproef het tussen die laer NDP-rantsoen en die ander twee rantsoene gevarieer. Die rede
vir die verskil in verteerbaarheid mag wees a.g.v. verskillende deurvloeitempo’s (laer NDP =
0.064/uur teenoor 0.044 - 0.045/uur vir die laeproteien en hoe-proteienrantsoene) en die ADF
waarde wat van die lae NDP rantsoen verskil het van die ander twee rantsoene. Omdat die resultate
van die degradeerbaarheidsproef aangedui het dat daar geen verskil in dieet-proteiendegradeerbaardheid
was nie is dit nie moontlik om ‘n gevolgtrekking te maak random die invloed van
dieet-proteien-degradeerbaardheid op die produksie van lakterende Saanen melkbokke nie.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/52516 |
| Date | 12 1900 |
| Creators | Thornton, John |
| Contributors | Ferreira, A. V., Stellenbosch University. Faculty of Agrisciences. Dept. of Animal Sciences. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | English |
| Type | Thesis |
| Format | xiv, 60 p. : ill. |
| Rights | Stellenbosch University |
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