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Characterisation and cryopreservation of semen from indigenous Namaqua Afrikaner sheep breed, in comparison with Dorper and Dohne Merino breedsLetsoalo, Phutiane Thomas January 2017 (has links)
The aim of this study was to characterise and cryopreserve semen of the indigenous Namaqua Afrikaner breed, and to compare it to that of Dorper and Dohne Merino sheep, whose semen is commercially frozen on a large scale. The study was conducted between January and August 2015. September 2013-born Namaqua Afrikaner (12), Dohne Merino (12) and Dorper (9) rams were used in the study. The rams were kept under kraal conditions with adequate shade, and they received a high protein, high energy diet. Originally it was envisaged to collect semen samples using the artificial vagina (AV) method, which proved to be problematic with the Namaqua Afrikaner rams. Semen samples were subsequently collected twice a week by either AV (Dohne Merino and Dorper) or electro-ejaculation (EE; all three breeds). Macroscopic sperm traits were assessed and sperm concentration determined immediately after collection. Each semen sample was diluted with Triladyl® (1:3) and subsequently frozen in liquid nitrogen vapour in straws. Frozen straws were thawed and evaluated at 7, 30 and 90 days after cryopreservation. A droplet (0.5 ml) from each thawed sample was assessed microscopically for post-thaw motility and percentage live sperm..
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'n Studie van dorperskaapboerdery in die dorperlandgebiedAckermann, Jacobus Johannes 12 1900 (has links)
Thesis (MScAgric) -- Stellenbosch University, 1993. / ENGLISH ABSTRACT: A model of interdependents that makes provision for the particular needs of dorper
sheep farming and is based on the relationship between the main groups of
behaviour determined variables, was constructed. This model served as a basis for
an interview schedule whereby personal interviews were held with 130 randomly
drawn dorper farmers in the summer rainfall area of the Dorperland. Various
independent and mediatory variables were examined and in certain cases it was
quantified. Thus certain relationships between the needs, aspirations and
endeavours of the respondents and their particular personal and environmental
factors were determined. The determination of the independent and mediatory
variables provide the extension officer with important background information
whereby the application/non-application of certain practices as well as the
efficiency of practice application are put into perspective. In this respect the
findings of this survey serve as an important reference point by which specified
extension actions could be evaluated in the future. The effectiveness of practice
application is determined on the basis of 5- and 10-point scales as well as a description of what is actually done. In doing this the existence of certain definite
differences between the perceptions of the respondent~ concerning the efficiency
of praxis application and the assessment of the interviewers, baled on •
description of what is actually done, was found. Practice accepta1Ce, •
manifested in efficiency is measured on the basis of particular effectivity stMcWds.
Thus relationships between the efficiency standards and certain personal, socioeconomical,
socia-psychological and biological-technical variables wet"d
determined. / AFRIKAANSE OPSOMMING: 'n Model van interafhanklikes wat voorsiening maak vir die eiesoortige behoeftes
van dorperskaapboerdery en gebaseer is op die verwantskap tussen die
hoofgroepe van gedragsbepalende veranderlikes, is gekonstrueer. Hierdie model
het as basis gedien vir 'n onderhoudskedule aan die hand waarvan persoonlike
onderhoude met 130 ewekansig gelote dorperboere in die somerreenvalgebied
van Dorperland gevoer is. Verskeie onafhanklike en bemiddelende veranderlikes is
ondersoek en in sekere gevalle is dit gekwantifiseer. Sodoende is verwantskappe
tussen die behoeftes, aspirasies en strewes van die respondente en bepaaIde
persoonlike- en omgewingsfaktore van sodanige respondente bepaal. Die
bepaling van die onafhanklike- en bemiddelende veranderlikes bied die voorligter
belangrike agtergrondinligting op grond waarvan die toepassing/nie-toepassing
van bepaalde praktyke asook die doeltreffendheid van praktyktoepassing in
perspektief geplaas word. Die mate waartoe sekere praktyke wat met
dorperskaapboerdery verband hou toegepas word. is ook bepaal. In hierdie verband dien die bevindinge van hierdie ondersoek as belangrike verwysingspunte
aan die hand waarvan bepaalde voorIigtingsaksies in die toekoms geevalueer kan
word. Die doeltreffendheid van praktyktoepassing is aan die hand van 5- en 10puntskale.
asook 'n omskrywing van wat werklik gedoen word, bepaaI. Sodoende
is die bestaan van sekere duidelike verskille tussen die persepsies van die
respondente wat betref die doeltreffendheid van praktyktoepassing en die aansIag
van opnemers, gebaseer op 'n beskrywing van wat werklik gedoen word, bevind.
Praktykaanvaarding, saos dit manifesteer in doeltreffendheid. is aan die hand van
bepaalde doeltreffendheidsmaatstawwe gemeet. Sodoende is verwantskappe
tussen die doeltreffendheidsmaatstawwe en sekere persoonlike, sosio-ekonomiese,
sosio-psigologiese en biologies-tegniese bepaal.
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Avaliação dos níveis de energia na dieta de cordeiros terminados em confinamento / Evaluation of Energy Levels in Diet of feedlot lambsSilva, Barbara Cristina Dantas da 24 August 2013 (has links)
The aim of this study was to evaluate the performance, feeding behavior, and carcass yields of Santa Inês lambs (SI) and ½ Dorper x Santa Inês (SI x D) feedlot and fed diets containing three levels of power (2.50, 2.79 and 3.03 Mcal / kg DM). We used 30 lambs, 15 of each genotype, with an average age of 120 days, in a completely randomized design in a 2 x 3 factorial design with 5 replications. Diets were isonitrogenous, containing
14% crude protein. The energy density of the diet affect the intake of dry matter and nutrients (P <0.05). Increased energy levels of diets improved weight gain, feed conversion
and carcass hot and cold the animals studied as increased energy levels up. There was a positive effect (P <0.05) of the energy levels of the diets for the times when eating, ruminating and idling (h / day), intake and efficiency of rumination (kg DM / h). There was no effect (P <0.05) the energy level of the diets on intake and efficiency of rumination (NDF kg / h). With the increase of the energy levels of the diets had a positive influence on performance, feeding behavior, and carcass yield of feedlot lambs. / O objetivo deste estudo foi avaliar o desempenho, o comportamento ingestivo e os rendimentos de carcaça de cordeiros Santa Inês (SI) e ½ Santa Inês x Dorper (SI x D)
terminados em confinamento e alimentados com dietas contendo três níveis de energia (2,50, 2,79 e 3,03 Mcal EM/kg MS). Foram utilizados 30 cordeiros inteiros, 15 de cada
genótipo, com idade média de 120 dias, em um delineamento inteiramente casualizado, num esquema fatorial 3 x 2, com 5 repetições. As dietas foram isoprotéicas, contendo 14%
de proteína bruta. A densidade energética das dietas influenciou o consumo de matéria seca e nutrientes (P<0,05). O aumento dos níveis de energia das dietas melhoraram o ganho de
peso, a conversão alimentar e os rendimentos de carcaça quente e fria dos animais estudados conforme aumentavam-se os níveis energéticos. Houve efeito positivo (P<0,05)
dos níveis de energia das dietas para os tempos em ingestão, ruminação e ócio (h/dia), eficiência de ingestão e de ruminação (kg MS/h). Não houve efeito (P<0,05) do nível energético das dietas sobre eficiência de ingestão e de ruminação (kg FDN/h). Com o aumento dos níveis de energia das dietas houve influência positiva sobre o desempenho, comportamento ingestivo e rendimento de carcaça de cordeiros terminados em
confinamento.
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POST WEANING SUPPLEMENTATION OF APRIL-BORN POLYPAY AND WHITE DORPER LAMBS GRAZING ALFALFA/ORCHARDGRASS PASTUREWood, Lauren N. 01 January 2016 (has links)
The effect of post-weaning supplementation of April-born Polypay and White Dorper lambs grazing alfalfa/orchardgrass pasture during two grazing seasons from June to September was studied. One hundred seventy Polypay and 133 White Dorper lambs were randomly allotted to supplemented (2% BW daily) and unsupplemented groups. It was discovered that Polypay lambs weighed more than White Dorpers at wearning, when the grazing season began, and at the end of the 80 (Year 1) and 85 (Year 2) grazing season (P < 0.01). Polypay lambs gained faster (P < 0.01) than White Dorpers. Supplemented lambs gained faster (P < 0.01) than unsupplemented and Polypays had a greater response to supplementation (P < 0.01) than White Dorpers. Polypays had higher (P < 0.01) fecal egg counts, an indicator of Haemonchus contortus infestation. Supplementation did not have any consistent effect on reducing Haemonchus contortus infestation. Differences in forage characteristics of Polypay and White Dorper lambs did appear. Differences in alfalfa and orchardgrass dry matter, neutral detergent fiber, acid detergent fiber, and crude protein availability were measured by subtracting enter from exit availabilities. The largest decrease of alfalfa components from exit to enter was found with unsupplemented Polypays. No consistent effect was found for orchardgrass components.
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'n Beoordeling van prestasie-evalueringsprosedures van Dorperramme onder ekstensiewe bestuurstoestandeVon Schauroth, Erich Dieter Friedrich 03 1900 (has links)
Thesis (MScAgric)--University of Stellenbosch, 2007. / ENGLISH ABSTRACT: AN ASSESSMENT OF PERFORMANCE EVALUATION PROCEDURES OF DORPER
RAMS UNDER EXTENSIVE MANAGEMENT CONDITIONS.
During 1988 to 2000, Dorper rams (n=2565) maintained on the Kalahari Experimental
Farm during performance test periods of approximately 180 days, were subjected to
evaluation according to specific body measurements and breed standards. The
respective body measurements included live weight, shoulder height, body length, body
width, scrotal circumference and average daily weight gain (ADG). The measurements
were recorded at the beginning and end of each evaluation period. The rams were
evaluated visually by breed inspectors and classified according to breed standards.
Live weight recorded at the beginning of evaluation periods, was moderate to high, and
positively correlated with most of the body measurements recorded in the study. The
exception was ADG, which was negatively correlated (-0.25) with live weight. Live
weight recorded at the end of evaluation periods was moderately and positively
correlated with scrotal circumference (0.57), and highly correlated with body width
(0.76). Average daily weight gain was high and positively correlated with live weight
(0.63) recorded at the end of the evaluation periods.
Large variations within test periods, that could be attributed to age differences and
variation between the respective groups of rams, necessitated correction of the data for
the effect of year/season. The rams were divided into above- and below average
groups according to their weight at the beginning of the test period. Analysis of the
growth patterns of rams during the study period, using the adjusted end data, indicated
that 75% of the rams remained in their respective groups. This finding supports the
above-mentioned positive correlation of 0.58 that was reported for live weight at the
beginning and end of evaluation periods. Body measurements recorded at the
beginning of the evaluation periods were in most cases moderately to high and
positively correlated (P<0.0001) with measurements recorded at the end of the
evaluation periods. The exception was ADG, which was low and negatively correlated
with the respective body measurements that were recorded at the beginning of
evaluation periods. After each body measurement was quantified by the sum of squares, it became evident
that year/season had the greatest influence on the body measurements recorded at the
end of an evaluation period. Year/season influenced live weight, body width, shoulder
height, scrotal circumference and ADG, with the largest effect on live weight and the
least influence on ADG (R2 = 31.62). After correction for year/season, the contribution
of the respective measurements to live weight recorded at the end of evaluation periods
were still in the same order. After a step-wise procedure for adjusted live weight at the
end of evaluation periods was performed, it was found that body width contributed the
most to live weight. Average daily gain made the third largest contribution, i.e. with
respect to body width (largest) and body length (second largest), to corrected live
weight recorded at the end of evaluation periods. The high correlations reported
between the respective body measurements necessitated the analysis of the data for
multi-colinearity to determine whether the partial contribution of the respective body
measurements would differ from the initial values. The partial contribution of the
respective body measurements, however, was not affected by the analysis.
Regression analysis indicated that the respective body measurements and weights
recorded at the beginning of evaluation periods decreased significantly (P<0.0001) over
the entire period (1988-2000). The largest annual decreases were reported for ADG (-
2.5%) and body width (-1.1%), respectively. The decreases in ADG and body width are
indications that Dorper sheep decreased in size during the period of this study. The
value of visual appraisal methods therefore need to be seriously considered to
determine whether this is a valuable management tool to assess the production
performance of Dorper rams under extensive conditions.
The influence of corrected body measurements and ADG, i.e. after selection by breed
inspectors and according to breed standards, was plotted on scatter plots. The plots
indicated that the breed inspectors selected larger and heavier rams throughout. It is
however, still the case in the Dorper industry that rams that perform below average are
sometimes classified and used as stud breeding material. Body width and shoulder
height were the body measurements that received the highest and lowest approval as
visual selection criteria, respectively. A possible reason for this is that the tendency of a
smaller Dorper sheep can be attributed to the decreasing shoulder height, as the latter
is an indication of body frame size. Visual appraisal should therefore be used in
conjunction with scientific methods. Optimum size for the Dorper should be established. / AFRIKAANSE OPSOMMING: ‘N BEOORDELING VAN PRESTASIE-EVALUERINGSPROSEDURES VAN
DORPERRAMME ONDER EKSTENSIEWE BESTUURSTOESTANDE
Dorperramme (n=2565) is vanaf 1988 tot 2000 te Kalahari Proefplaas in
prestasietoetstydperke van ongeveer 180 dae onder ekstensiewe toestande volgens
sekere liggaamsparameters en rasstandaarde geëvalueer. Die onderskeie
liggaamsmates het lewende gewig, skouerhoogte, liggaamsbreedte, liggaamslengte,
skrotumomtrek en gemiddelde daaglikse toename (GDT) ingesluit. Die parameters is
aan die begin en einde van elke toetsperiode gemeet. Die ramme is visueel deur
rasinspekteurs geëvalueer en volgens rasstandaarde geklassifiseer.
Die lewende gewig van die ramme wat aan die begin van die toetsperiodes aangeteken
is, was matig tot hoog en positief met meeste van die liggaamsparameters
gekorreleerd. Die uitsondering was GDT, waar ʼn negatiewe korrelasie (-0.25) gevind is.
Die lewende gewig van die ramme aan die einde van die toetsperiodes was matig en
positief met beide skrotumomtrek (0.57) en die hoogste met liggaamsbreedte (0.76)
gekorreleerd. Gemiddelde daaglikse toename was hoog en positief (0.63) met lewende
gewig aan die einde van die toetsperiode gekorreleerd.
Groot variasie binne toetsperiodes, wat aan ouderdomsverskille en variasie tussen
toetsgroepe toegeskryf kan word, het genoodsaak dat die data vir die effek van
jaar/seisoen gekorrigeer word. Ramme is volgens begingewig in bo- en
ondergemiddelde groepe gerangskik. Groeipatrone van die ramme is met
gekorrigeerde einddata ondersoek en gevind dat 75% van ramme gedurende die
toetsperiode in hul onderskeie groepe gebly het. Hierdie bevinding verleen steun aan
die positiewe korrelasie van 0.58 wat vir lewende gewig aan die begin en einde van
toetsperiodes hierbo gevind is. Die liggaamsmates wat aan die begin en einde van die
toetsperiodes gemeet is, was in die meeste gevalle matig tot hoog en positief (P <
0.0001) met mekaar gekorreleerd. Die uitsondering was GDT, wat laag en negatief
met liggaamsmates, wat aan die begin van toetsperiodes aangeteken is, gekorreleerd
was. Die seisoenseffek het die grootste bydrae tot lewende gewig aan die einde van die
toetsperiodes gemaak, d.i. nadat elke meting deur die somme van kwadrate
gekwantifiseer is. Dit is gevolg deur liggaamsbreedte, -lengte, skouerhoogte,
skrotumomtrek en GDT (R² = 31.62%). Nadat daar vir jaarseisoen gekorrigeer is, was
die bydrae van die onderskeie parameters tot lewende gewig aan die einde van
toetsperiodes nog in dieselfde volgorde. Nadat ʼn stapsgewyse prosedure vir
gekorrigeerde lewende gewig aan die einde van toetsperiodes gedoen is, is gevind dat
liggaamsbreedte die grootste bydrae tot lewende gewig aan die einde van toetsperiodes
gemaak het. Gemiddelde daaglikse toename het die derde grootste bydrae, d.i. na
liggaamsbreedte en –lengte tot gekorrigeerde lewende gewig aan die einde van
toetsperiodes gemaak. Vanweë die hoë korrelasies wat tussen die onderskeie
liggaamsmates gevind was, is daar ook vir multi-kollineariteit getoets om vas te stel of
die parsiële bydraes van die onderskeie liggaamsmetings verander. Dit het egter
onveranderd gebly.
Regressie-analises het getoon dat liggaamsmates geneem aan die begin en einde van
die toetsperiodes betekenisvol (P<0.0001) oor die hele tydperk (1988 – 2000)
afgeneem het. Die grootste jaarlikse afnames was vir GDT (-2,5%) en
liggaamsbreedte (-1,1%) bereken. Die negatiewe waardes wat verkry is, toon dat die
Dorper oor tyd kleiner word. Die toepaslikheid van die visuele seleksiemetodes moet
dus ernstig bevraagteken word.
Die invloed van gekorrigeerde liggaamsmates en GDT op seleksie volgens
rasstandaarde wat deur die rasinspekteurs gedoen is, is toe op puntediagramme
aangetoon. Dit het getoon dat die rasinspekteurs deurentyd groter en swaarder ramme
vir stoetseleksie selekteer. Daar is egter steeds ramme wat ondergemiddeld presteer
en wat aan die Dorperbedryf as stoetramme beskikbaar gestel word. Liggaamsbreedte
was die liggaamsmate wat die hoogste voorkeur van rasinspekteurs gekry het. Die
liggaamsmate wat die minste deur die rasinspekteurs in ag geneem is, was dié van
skouerhoogte. ʼn Moontlike verklaring vir laasgenoemde is dat die tendens van die
kleinerwordende Dorper hieraan gekoppel kan word, omdat skouerhoogte 'n aanduiding
van raamgrootte is. Visuele beoordeling behoort in samewerking met wetenskaplike
metodes gebruik te word om sodoende ʼn optimum grootte vir die Dorper daar te stel.
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Feedlot performance and essential amino acid growth requirements of Dorper lambsJurgens, Andre Hendrik 12 1900 (has links)
Thesis (MScAgric)--University of Stellenbosch, 2002. / ENGLISH ABSTRACT: The Dorper is numerically the second most abundent of all the sheep breeds in
South Africa. It is the most numerous sheep breed in the dry arid areas of South
Africa which make out a very big portion of the natural grazing in South Africa. In this
study the feedlot performance was specifically investigated since so little research
has been done in this regard. In the first study (Chapter 1), the production efficiency,
body components and commercial yield of 13 Dorper and 12 Merino lambs were
investigated. A pelleted diet was fed ad lib and the water intake per day was
measured. Lambs were slaughtered at 30kg and at 40kg live weight and cut up
according to the South African commercial cuts. The weights of the organs, head,
feet, skin and carcass were also recorded. Results from the first study showed that
Dorpers had a lower (P<0.05) water efficiency (285.97 mVkgO75/day) than the
Merinos (240.07 mVkg075/day), but had a higher (P<0.05) nitrogen retention. The
head, feet, skin, heart, lungs, kidneys and diaphragm of Merino lambs were heavier
(P<0.05). Merinos had heavier (P<0.05) breast and shank and thick rib (only at
40kg live weight) cuts. But the Dorper had a significantly heavier hindquarter
(buttock and loin) which is the high-priced cut of any carcass. It seems that the
Dorper will do well under feedlot conditions, and would possibly make a better
commercial meat producer than the Merino under all circumstances.
In the second study (Chapter 2), the free-ranging Dorper on natural grazing were
compared with 7 Dorper lambs in the feedlot study. The essential amino acids in the
duodenal contents were compared. The free-ranging Dorpers were randomly slaughtered at 40 kg live weight and a duodenal sample was collected. The feedlot
Dorpers were also slaughtered at 40 kg live weight and a duodenal sample was
taken. The second study indicated no significant differences between the EAA
composition of the duodenal samples, whether protein quantity was taken into
account (gAA/100g crude protein (CP)) or not (expressed as % of lysine). The
chemical scores indicated that the two most limiting amino acids in the duodenal
digesta for whole empty body growth were: arginine and histidine. Excess levels of
amino acids tend to be present in all three duodenal digesta samples (isoleucine,
leucine, lusine, methionine, phenylalaline, threonine and valine). The whole empty
body EAA composition (g AA/100 g crude protein) was as follows 7.10 arginine; 2.40
histidine; 3.31 isoleucine; 7.22 leucine; 6.61 lysine; 1.62 methionine; 3.91
phenylalanine; 3.77 threonine and 4.85 valine. The composition can serve as an
example of the ideal EAA requirements for whole empty body growth between 30
and 40 kg live weight of Dorper ram lambs. The duodenal amino acid concentrations
of the free-ranging Dorper compared well with those of the feedlot Dorpers which
suggests that the microbial organisms have a big influence on the amino acid
concentration which reaches the intestines. / AFRIKAANSE OPSOMMING: Die voerkraal prestasie en essentiele aminosuur behoeftes van
groeiende Dorper lammers: The Dorper is getalgewys die tweede mees talryke skaapras in Suid-Afrika. Dit is die
mees talryke skaapras wat in die drce woestynagtige gebiede van Suid-Afrika
aangetref word. Die gebiede beslaan die grootste oppervlakte van Suid-Afrika se
natuurlike weiveld. In die studie is voerkraal prestasie van die Dorper nagevors,
spesifiek omdat daar so min navorsing op hierdie gebied gedoen is. In die eerste
studie (Hoofstuk 1) is die produksie doeltreffendheid, liggaams komponente en
kornrnersiele produksie van 13 Dorper- en 12 Merino lammers ondersoek. 'n
Verpilde rantsoen is ad lib gevoer en die water inname per dag is ook gekontroleer.
Die lammers is geslag op 30 en 40 kg lewende gewig en die karkasse is daarna
opgesny volgens die Suid-Afrikaanse kornmersiele karkassnitte. Die resultate van
die eerste studie het getoon dat Dorpers 'n laer water potentiaal (P<0.05) (285 97
mflkgO 75/dag) as die Merinos (240.07 mVkg075/dag) het. Dorper lammers het ook 'n
hoer (P<0.05) stikstof retensie. Die kop, vel, pote, hart, longe, niere en diafragma
van Merino lammers was swaarder (P<0.05). Merinos se brisket en dikrib snitte
weeg ook swaarder (P<0.05). Die Dorper het 'n beduidende swaarder agterkwart
(len de en boud) gehad, wat die duurste snit is van enige karkas. Die Dorper het baie
goed gedoen in die voerkraal toestande en sal waarskynlik onder aile omstandighede
'n hcer vleisproduksie op die Merino lewer. In die tweede studie (Hoofstuk 2), is die vryweiende Dopers op natuurlike weiding
vergelyk met die Dorpers in 'n voerkraal. Die twee groepe Dorpers se essensiele
aminosuur samestelling in hul dunderms is bepaal en vergelyk om te bepaal of daar
enige tekorte teenwoordig is. Die Dorpers in die veld en in die voerkraal is op 40 kg
lewende gewig geslag en monsters van die dunderm inhoud is gekollekteer. Die
monsters is ontleed om te bepaal of daar enige betekenisvolle verskille in die
essensiele aminosure van die dunderm inhoud tussen die veld Dorpers en voerkraal
Dorpers was. Die tweede studie het geen betekenisvolle verskille getoon tussen die
dunderm monsters se essensiele aminosure, of die hoeveelheid proteien (gAA/100g)
in aanmerking geneem is of nie (uitgedruk as % lisien). Die chemiese telling dui aan
dat die twee mees beperkende aminosure in die dunderm inhoud vir lee liggaam
groei arginien en histidien was. Oormaat vlakke van aminosure kom voor in al drie
dunderm inhoud monsters (isoleusien, leusien, lisien, metionien, femielalanien,
treonien en valien). Die totale lee liggaam essensiele aminosuursamestelling (g
aminosuur/100g ruprotein) was soos volg: 7.10 arginien; 2.40 histidien; 3.31
isoleusien; 7.22 leusien; 6.61 lisien; 1.62 metionien; 3.91 fenielalanien; 3.77 treonien
en 4.85 valien. Hierdie aminosuursamestelling kan as 'n aanduiding dien vir die
ideale aminosuurbehoeftes van Dorper ram lammers vir totale lee liggaamsgroei
vanaf 30 tot 40 kg lewende massa. Die dunderm aminosuur konsentrasie van die
Dorper in die veld stem goed ooreen met die van die voerkraal Dorper. Dit toon
waarskynlik dat die mikrobe organismes in die rumen In groot invloed het op die
aminosuur samestelling wat die dunderm bereik.
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The influence of the composition of mixed Karoo vegetation on the grazing habits of Merino and Dorper wethersRoux, Francis Augustus January 1994 (has links)
The primary objective of this research project was to determine whether area-selective grazing, by Dorper and Merino wethers, took place in small grazing camps as governed by differences in vegetal cover. The main research techniques employed were the descending-point method for the determination of botanical composition, sub-division of the camps into gridblocks to trace sheep movement in relation to vegetation patterning, fistulated animals to determine diet selection, the electronic theodolite for micro-topography, and few minor techniques. The result have shown that area- patch- and species selective grazing are prevalent in small grazing camps under "normal" stocking densities, and that different breeds of stock (Merino and Dorper sheep) have different grazing patterns and diet selection . Climax and sub-climax areas were those primarily select ed for grazing. There is little or no correlation between botanical composition and diet selected as per fistula ted animal. The average distances travelled by Dorpers and Merinos was 2 km / day and 3.1 km/day respectively. Plant phenology did not have a detectable influence in the choice of diet.
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Evaluation of the small ruminant nutrition system model using growth data of South African mutton merino and dorper lambsLinsky, Anta January 2013 (has links)
The aim of this study was to evaluate the Small Ruminant Nutrition System (SRNS) model’s
performance predictions for lambs under South African conditions using growth and body composition
data of early- (Dorper) and late-maturing (South African Mutton Merino), indigenous sheep breeds. The
Cornell Net Carbohydrate and Protein System (CNCPS) biological model has consistently been
modified to include recent information. This has led to the development of the SRNS model, but up to
now the SRNS model has only been validated with European sheep breeds under European
conditions.
Thirty two Dorper, 16 male and 16 female lambs, and 36 South African Mutton Merino, 18 male and 18
female lambs, were fed a grower diet for the experimental period of 60 days. Three groups of lambs of
each breed were slaughtered as the lambs reached pre-determined target weights. The first group of
24 animals (slaughter group 1) was slaughtered at the onset of the experiment at a live weight of 20 kg.
With the second group (slaughter group 2) the South African Mutton Merinos were slaughtered at an
average weight of 35 kg and the Dorpers at an average weight of 30 kg. The last group (slaughter
group 3) had an average weight of 50 kg for the South African Mutton Merinos and 40 kg for the Dorpers at slaughter. Using the data from this trial, predictions of the average daily gain (ADG), feed intake (DMI), empty
body gain and the composition of the empty body gain were used to evaluate the model. The animals
were divided into three slaughter groups, based on growth stage, for the determination of body
composition data. Energy value of gain (EVG), fat and protein content on a shrunk and empty body
weight basis were compared with the corresponding values predicted by the SRNS. Growth
composition of the lambs was determined by dividing them into two growth periods. Average daily gain
and DMI were evaluated in the experiment, and results compared to the mean ADG and DMI
predictions obtained from the SNRS model.
Two different equations were compared to estimate EVG and two sets of coefficients were also
compared for the EVG. Five different equations were compared to estimate the efficiency of conversion
of metabolisable energy (ME) to net energy (NE) for gain, kg. The correction factor to adjust for the
increase in the size of the visceral organs as nutrient intake increases and the coefficient for the effect
of gender on maintenance requirements were tested for relevance of use in the SRNS. Overall, based
on these evaluations it appears that the original SRNS model gave the best predictions when compared
to any of the modifications tested.
With regards to ADG the model over-predicts the requirements of the lambs in the early growth stage
and under-predicts the requirements of the lambs in the later growth stage. The DMI predictions that
were made using the original SRNS were accurate. The evaluation of the SNRS predictions in relation
to the composition of gain indicated that this model over-predicted both the fat and the protein content
of gain. The predictions were accurate, however the precision was low. The low precision was probably
due to the lack of variation in the measured range of fat and protein content of gain.
Before field application further studies and adjustments to the SRNS model is required, especially with
regard to predictions on the fat and protein content of gain and over or under predictions of ADG during
different growth stages of Dorper and South African Mutton Merino lambs. / Dissertation (MSc)--University of Pretoria, 2013. / gm2014 / Animal and Wildlife Sciences / unrestricted
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Vergelyking van bestuurspraktyke van dorperboere in 1990 teenoor dorperboere in 2004Van Niekerk, E. M. 12 1900 (has links)
Thesis (MPhil (Agricultural Economics))--University of Stellenbosch, 2005. / The Dorper Sheep species are exclusively bred for the dry arid conditions of
some parts of South Africa. This species adapts easily and a prime lamb with
great characteristics can be produced. There are two very important controlable
factors regarding Dorper sheep farming namely herd management and
cultivation. Herd management involves feeding, mating, mating methods and the
handling of animals and their products. A few good objectives of herd
management are the short breeding interval, low deaths and high performance
rating. Genetic improvement can be achieved by using good rams, the selection
of ewe-lambs as forthcoming breeding ewes, culling of uneconomic producers
and the application of good breeding practices to improve meat production and
reproduction. In this study a comparison is made between the management
practices (herd management and cultivation) of Dorper farmers in 1990 and the
management practices of Dorper farmers in 2004. For this aim the research of
J.J. Ackermann (1990) was used. In 2004 questionnaires were send to Dorper
farmers throughout South-Africa to get more information about their management
practices. The conclusion of the study was that there was an increase in tertiary
qualification of Dorper farmers from 1990 to 2004 and that more farmers used
modern practices instead of the old traditional methods.
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The effect of agricultural production system on the meat quality of Dorper lambsClaasen, Claasen 03 1900 (has links)
Thesis (MScAgric)--Stellenbosch University, 2008. / ENGLISH ABSTRACT: The aim of this study was to investigate the effect of South African production system (feedlot {FL-} or free-range {FR-}) and gender (ewes, rams or castrates) on growth and carcass characteristics of Dorper sheep.
Male lambs (castrates and rams) grew twice as fast as ewes (P<0.05) under FL-conditions while much smaller differences were observed between gender groups in FR-lambs. FL-lambs produced heavier carcasses (P=0.0003) with higher dressing percentages (P<0.05) and greater carcass fatness levels (P<0.052) than FR- lambs.
No differences attributable to production system were found on meat tenderness (as indicated by Warner Bratzler shear force strength) and on the intramuscular lipid concentration. In contrast, sensory evaluation results suggested that meat from FL-lambs was juicier and more tender than meat from FR-lambs. The sensory panel could not distinguish between FL and FR meat as far as the attributes of aroma and flavour were concerned.
Cholesterol results indicated that for intermuscular fat, higher cholesterol levels were observed for FL-lambs than for FR-lambs. The level of palmitic acid (C16:0) was significantly higher (P=0.0375) in the Longissimus dorsi (LD) muscles of FL-lambs.
For intramuscular fat from the Biceps femoris (BF) muscle, g-linolenic acid (C18:3n-6) was higher (P<0.0001) in FL- lambs. Results for intramuscular BF further indicated that ram lambs had the highest (P=0.0019) palmitic acid (C16:0) and sum of TUFA (P=0.0014), castrates had the highest (P=0.0260) α-linolenic acid (C18:3n-3) and g-linolenic acid (C18:3n-6), while ewe lambs had the highest (P=0.0014) SFA concentrations. Linoleic acid (C18:2n-6c) was significantly higher (P=0.0067) in the subcutaneous fat of FL-lambs while FR-lambs had more linolenic acid (C18:3n-3). For the kidney fat, FR-feeding increased (P < 0.05) stearic (C18:0), linolelaidic (C18:2n-6t), α-linolenic (C18:3n-3) and homo-g-linolenic acid (C20:3n-6) percentages. Conversely, linoleic acid (C18:2n-6c) was increased (P=0.0372) by FL-feeding. For the intermuscular fat, FR-lambs had higher linolenic acid (C18:3n-3) and SFA (P=0.0113 and P=0.0341) compared to FL-lambs. On the other hand, the sum of TUFA for the intermuscular fat was higher (P=0.0341) in FL-lambs compared to FR-lambs.
Results from the study imply that the consumer may not necessarily be able to discern between meat from FR- or FL-lambs, although they may possibly discriminate against the increase in visible fatness of FL-lambs. No clear advantage of production system in terms of human health could be demonstrated as far as the proximate chemical composition and the fatty acid composition of the meat was concerned. The faster growth and the associated shorter production cycle of FL-lambs could be an advantage under certain production systems. However, it needs to be weighed against the cost of concentrate feeding and the preference consumers are likely to develop for lamb produced in natural environments. / AFRIKAANSE OPSOMMING: Die doel van die studie was om Suid Afrikaanse produksiestelsel (voerkraal {VK-} of veld {VD}) en geslag (ooie, hamels of ramme) op die groeivermoë en karkaseienskappe van die Dorperskape te bepaal.
Manlike lammers (ramme and hamels) het twee keer vinniger (P<0.05) as ooilammers onder VK-toestande gegroei, terwyl kleiner verskille tussen geslagsgroepe by VD-diere waargeneem is. VK-lammers het swaarder karkasse (P=0.0003), hoër uitslagpersentasies (P<0.05) en meer karkas vet (P<0.052) as VD -lammers vertoon.
Geen verskille as gevolg van produksiestelsel is op die sagtheid van vleis (soos aangedui deur Warner-Bratzler skeurkragwaardes) en die binnespierse vetinhoud gevind nie. Daarenteen het sensoriese analises aangedui dat vleis van VK-lammers sappiger en sagter as vleis van VD- lammers was. Die sensoriese paneel kon nie verskille aangaande die aroma en geur van vleis tussen VK- en VD-vleis onderskei nie.
Cholesterolvlakke was hoër vir VK-lammers as by VD-lammers. Die vlak van palmitiese suur (C16:0) was hoër (P=0.0375) in die Longissimus dorsi (LD) spier van VK-lammers.
Vir binnespierse vet van die Biceps femoris (BF) spier was g-linoleniese suur (C18:3n-6) hoër (P<0.0001) in VK-lammers. Resultate vir binnespierse vet van die BF spier het verder bewys dat ramlammers die hoogste (P=0.0019) palmitiese suur (C16:0) and totale onversadigde vetsure (P = 0.0014) getoon het, hamels die hoogste (P=0.0260) α-linoleniese suur (C18:3n-3) en g-linolenese suur (C18:3n-6) getoon het terwyl ooilammers die hoogste (P=0.0014) versadigde vetsuurvlakke getoon het. Linoliese suur (C18:2n-6c) was hoër (P=0.0067) in die onderhuidse vet van VK-lammers terwyl VD-lammers meer linoliese suur (C18:3n-3) gehad het. Resultate vir niervet het getoon dat VD-voeding die persentasies van steariese (C18:0), linoleladiese (C18:2n-6t), α-linoleniese (C18:3n-3) and homo-g-linoleniese suur (C20:3n-6) verhoog (P<0.05) het relatief tot VK-voeding. Linoliese suur (C18:2n-6c) is deur VK-voeding verhoog (P=0.0372). Vir intermuskulêre vet het VD-lammers hoër linoleniese suur (C18:3n-3) en versadigde vetsure (P=0.0113 en P=0.0341) as VK-lammers gehad. Die totale onversadigde vetsure vir tussenspiere vet was hoër (P=0.0341) in VK-lammers in vergelyking met VD-lammers.
Resultate van hierdie studie dui daarop dat verbruikers nie noodwendig tussen vleis van VD- en VK-lammers sal onderskei nie, alhoewel hulle dalk teen die sigbaar vetter vleis van VK-lammers kan diskrimineer. Geen definitiewe voordeel in terme van menslike gesondheid kon op grond van die chemiese samestelling van die vleis bevestig word nie. Vinniger groei van VK-lammers, en die korter produksiesiklus wat daarmee verband hou, mag onder sekere produksie stelsels ʼn voordeel wees. Die voordeel moet teen die hoër koste van VK-voeding en die voorkeur van verbruikers vir lam produksie in natuurlike omgewing opgeweeg word.
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