31 research outputs found
The economic effects of an oestrus synchronisation protocol using prostaglandin and reproductive tract scoring in beef heifers in South Africa
In this study 272 beef heifers were studied from just prior to their first breeding season (15 October 2003), through their second breeding season and until just after they had weaned their first calves in March 2005. The study consisted of two main parts: in the first part, heifers were randomly allocated to either a synchronised TEST group or an unsynchronised CONTROL group. The TEST group received artificial insemination (AI) for 6 days followed by prostaglandin F2ĂĄ (PGF) treatment on day 6 (PGF/6) and further AI for a total of 50 days, which was followed after a 6 day break by a 42 day bull breeding season. The CONTROL group were bred for the same period without PGF treatment. Synchronisation resulted in a reduction in days to first insemination (P < 0.01) and days to calving (P = 0.04). No significant difference could be demonstrated in pregnancy rate to the 50 day AI season (60.0% vs. 51.8%, TEST and CONTROL groups respectively, P = 0.18), final pregnancy rate (82.2% vs. 83.2%, P = 0.87) or pregnancy rate to the subsequent breeding season (96.0% vs. 95.0%, P = 1.00). A significant increase in mean weaning mass of the calves due to synchronisation could not be demonstrated (207.0 kg vs. 201.4 kg, TEST and CONTROL groups respectively, P = 0.32). However, data from this study were used to calculate the benefit:cost ratio, and a value of 2.8 was reached, representing the return on investment for the synchronisation protocol under these circumstances. It was concluded from this study that a PGF/6 protocol may lead to a change in the total mass of calves weaned by changing days to calving and thus weaning mass, birth mass of calves, weaning rate and/or the ratio of male:female calves born. It was further concluded that a practical way to predict the cost effectiveness of an oestrus synchronisation protocol is to determine the ratio between the total cost of the programme and the price of weaner calves per kg live mass. This ratio represents the minimum increase in mean weaning mass that has to be achieved for the programme to be cost effective if no increase in weaning rate is achieved. In the second part of this study, reproductive tract scoring (RTS) was performed on the same group of heifers one day before the onset of their first breeding season. The effect of RTS on several reproduction and production outcomes was tested, and the association of RTS with the outcomes was compared to the associations of other input variables such as mass, age, body condition score (BCS) and Kleiber ratio using multiple or univariable linear or logistic regression. RTS was associated with pregnancy rate to the 50 day AI season (P < 0.01), days to calving (r = 0.28, P < 0.01), calf weaning mass (r = 0.22, P < 0.01) and pregnancy rate to the subsequent breeding season (P < 0.01). These associations were mostly independent of associations with mass, age and BCS before the onset of the first breeding season. RTS was a better predictor of fertility than was Kleiber ratio, and similar in its prediction of calf weaning mass. It was concluded from this study that RTS is a unique predictor of heifer fertility, compares well with (but is independent of) other traits used as a predictor of production outcomes and is likely to be a good predictor of life production of the cow.Dissertation (MSc (Veterinary Sciences))--University of Pretoria, 2006.Production Animal Studiesunrestricte
Best of the best of the 2018 Onderstepoort Feedlot Challenge
The Onderstepoort Feedlot Challenge (OPFLC) is a group based Action Learning Project (ALP) within the Bachelor of Veterinary Science (BVSc) programme of the University of Pretoria (UP) (1-3). Initiated in 2007, the OPFLC maintains its original aims to stimulate interest in production animals through exciting practical exposure; to promote student wellbeing through physical activity and play; to
apply âsoftâ skills such as leadership, communication, business and management skills; and to develop a culture of teamwork, self-learning and critical scientific reasoning amongst future veterinarians(4-7). The OPFLC uses real cattle, real facilities, real resources, and real problems encountered in a
typical feedlot, within a simulated commercial environment. The competition between the participating student groups involves running the most economical and ethically acceptable feedlot from auction to abattoir, and demonstrating evidence of learning (7). Progress is monitored and feedback given continually and students are guided to make evidence based decisions in their daily feedlot management. Small changes are made to the detail of the OPFLC every year to keep it innovative. The educational success and validity of ALPs in veterinary education have been reported over the past decade and resulted in similar ALPs established within the veterinary curriculum of UP as well
as at other institutions (8-12). Part of the ALP includes an assignment in which each student has to report, based on the individual task assigned, what s/he has learnt during the ALP. Students are encouraged to interpret their own data against existing knowledge to support their findings scientifically. Students are assessed in two phases (first for feedback then for grading) using a predetermined scoring rubric through UPâs online learning management system, ClickUP (BlackboardÂź). This document represents the best of the eight
OPFLC assignments submitted for each topic in 2018, and serves as an example for future students and to acknowledge excellence.Includes bibliographical referencesThe 2018 Onderstepoort Feedlot Challenge was supported financially and through other means by: Zoetis, Vleissentraal Bosveld, Sparta beef, Tongaat, Hulett, Afgri, Fepro and SA Premixab201
The effect of preconditioning on production and antibiotic use in a South African beef feedlot
CONTEXT : There is pressure on production veterinarians to reduce the use of antibiotics in intensive beef production systems.
AIMS : The present study investigated whether preconditioning â the process whereby weaned calves destined for the feedlot are prepared over a period of time â reduced antibiotic treatment events, and improved health and production of calves in a South African feedlot.
METHODS : Preconditioned calves (n = 301) and control calves (n = 332) were sourced from the same origin on two occasions, and arrived at the feedlot on the same day. Bovine respiratory disease (BRD) was defined as the âpullingâ of clinically sick calves from feedlot pens, followed by the standard protocol for treatment of BRD (including antibiotic treatment). Outcome variables related to health were BRD overall incidence (pulling), BRD re-pulling and lung lesion scores. Production outcome variables measured were carcass weight, carcass average daily gain (ADG) and days on feed (DOF). Initial carcass weight was estimated from shrunk liveweight in order to estimate the effect of preconditioning on carcass gain, the most economically relevant outcome. Statistical analyses were done using multiple linear, logistic and Cox regression. Predictor variables were preconditioning vs control, gender, starting weight, DOF, pulling for BRD and carcass ADG.
KEY RESULTS : A lower proportion of preconditioned calves were pulled and a lower proportion of pulled calves were re-pulled for BRD compared with control calves (8 vs 17% and 8 vs 16%, respectively, P < 0.01). A higher proportion of preconditioned calves compared with control calves were market ready at 90 DOF (89 vs 67%, P < 0.01). In the multivariable models preconditioning was associated with a 200 g/d increase in carcass growth rate (P < 0.01) and with a 17.7 kg increase in overall carcass gain (P < 0.01) after adjusting for gender and DOF.
CONCLUSIONS : Preconditioning reduced the incidence and severity of BRD and feedlot standing time and improved production of calves in South African feedlots.
IMPLICATIONS : Preconditioning has the potential to add value to the beef feedlot by reducing the formation of antimicrobial resistance while improving the profitability of the feedlot.Red Meat Research and Development South Africa (RMRD-SA)http://www.publish.csiro.au/anhj2021Production Animal Studie
Fatal congenital anaplasmosis associated with bovine viral diarrhoea virus (BVDV) infection in a crossbred calf
Clinical disease resulting from the vertical transmission of Anaplasma marginale has only
been reported on 5 occasions despite studies demonstrating successful in utero transmission.
During the reported experimental induction of congenital anaplasmosis in calves, the
outcome was variable but mostly led to inapparent or mild infection. There are previous
case reports of fatal congenital anaplasmosis following natural infection. The clinical findings
in a 2-day-old calf presented to the Onderstepoort Veterinary Academic Hospital with
clinical signs of congenital anaplasmosis, which was unresponsive to treatment, are described.
Subsequent post mortem diagnostic tests revealed that this calf was co-infected with
bovine viral diarrhoea virus (BVDV). It is postulated that immunosuppression resulting
from BVDV infection predisposed to severe, fatal anaplasmosis in this calf.Department of Production Animal
Studies of the Faculty of Veterinary Science,
University of Pretoria.http://www.journals.co.za/ej/ejour_savet.htm
The impact of practical experience on theoretical knowledge at different cognitive levels
Although theoretical training of veterinary students is uncomplicated even for larger groups,
practical training remains a challenge. Much has been said about the value of practical training
in curriculum design. Yet, the impact of practical training on theoretical knowledge needs
further research. A cohort of 89 students with very limited clinical practical experience
completed an assessment at the end of their theoretical training in small ruminants. The scores
obtained by the students were compared with those obtained by a group of 35 veterinarians
who volunteered to participate in the study. In addition to comparing the scores between
students and practitioners, the cognitive level of each of the questions was considered. Overall,
veterinarians achieved higher test scores than did the students. The veterinarians outperformed
the students in all cognitive levels except for âapplyingâ type questions where there was no
difference. Different levels of experience, namely young veterinarians (n = 11), established
veterinarians (n = 13) and veterinarians approaching retirement (n = 11), were evaluated
against the revised Bloomâs cognitive levels. When modelling congress attendance frequency,
yearsâ experience, proportion of time spent with ruminants and revised Bloomâs levels,
congress attendance was not a significant variable, and thus, only the other three variables
remained. This investigation found that practical experience has a positive effect on theoretical
knowledge. The type of practical experience and where such practical experience is included
in a curriculum need further research. Working for a number of years in a specific discipline
will provide the best support for theoretical knowledge.The University of Pretoria, Vice Chancellorâs Granthttp://www.jsava.co.zaam2020Production Animal StudiesStatistic
Initial blood urea nitrogen concentration predicts subsequent blood urea nitrogen concentration in beef cows
This study was performed to determine whether beef cows
have an inherent ability to maintain their relative blood
urea nitrogen (BUN) concentration when cattle are exposed
to varying levels of dietary nitrogen supplementation. Ten
Hereford and 11 Nguni cows, aged between 2 and 16 years,
were utilised in two crossover designs. In the first design,
cows were exposed to diets containing normal and high
crude protein (CP) levels. At the end of the first crossover
design, cows received a normal diet for one week before
commencement of the second design. In the second
crossover design, cows were fed diets containing normal
and low CP levels. Blood urea nitrogen concentration was
measured 17-21 times (mean = 20) during the study. A linear
mixed-effects model was used to assess whether baseline BUN concentration (measured one week before onset of the
study) was predictive of subsequent BUN concentration in
individual cows. The model was also used to assess whether
any of the measured variables were predictive of subsequent
BUN concentrations. Baseline BUN concentration was a
significant predictor of subsequent BUN concentration
in individual cows (P = 0.004). Other variables that were
significantly associated with subsequent BUN concentration
were breed (P = 0.033), the diet that the cows received before
the current treatment (P < 0.001), treatment (P < 0.001) and
the week during which sampling was performed (P < 0.001).
Beef cattle appear to have an inherent ability to maintain their
relative BUN concentration within herds despite changes in
levels of dietary nitrogen supplementation.Poster presented at the University of Pretoria, Faculty of Veterinary Science Faculty Day, August 25, 2016, Pretoria, South Africa.ab201
Curricular renewal at the southern tip of Africa : the â2016â veterinary curriculum at the University of Pretoria
Four years after the institution of a new curriculum at the University of Pretoria's Faculty of Veterinary Science, a second major curricular renewal was initiated as a result of several pressing drivers, many of which were unique to the national and institutional context. During the project, South African higher education was disrupted by student protests prompted by financial pressures on students, the overt colonial structure of higher education, and the need to accelerate transformation of the sector. A structured curricular renewal process was followed, including the laying down of the principles, the structuring the macro-curriculum as a story, the design of a meso- and micro-curriculum, and the mapping of the curriculum to Day One outcomes. The resulting program is a 6-year bachelor's degree with a blend of discipline and species modules, with the first cohort graduating in 2016. There is a strong focus on skills embodied in a 62-week experiential component, managed using a unique custom-designed online platform for booking placements, documenting exposure, assessing competency, and providing feedback to students. The experiential training includes a large elective component. Several causes of loss of impetus during the process are discussed and proposals are made for avoiding these. The value of accreditation as a driver and a source of inputs is evident. The process has succeeded in producing a significantly reshaped curriculum that has been well received by external stakeholders.http://jvme.utpjournals.press/loi/jvme2018-09-06hj2017Production Animal Studie
A new application of pelvis area data as culling tool to aid in the management of dystocia in heifers
Although fetomaternal disproportion is
the major cause of dystocia in heifers, pelvis area (PA)
is not recommended as a culling tool due to its relatively
low importance and genetic correlation with calf birth
weight (BWT), the most important factor associated
with dystocia. The objective of this observational study
of 484 limited bred yearling beef heifers was to compare
the effects of different methods of adjustment of PA data
for culling to select against dystocia. Multivariable analyses
were used to determine predictors of PA, calf BWT,
and dystocia. Hypothetical culling rates of 10 and 20%
were then applied after ranking heifers by each of the
following: unadjusted PA, PA adjusted to 365 d of age by
subtracting 0.27 cm2 per day of age difference between
each heiferâs age and 365 d (APA), PA:prebreeding
BW ratio (PA:BW), PA adjusted to the median BW of
the group using the regression coefficient of PA on BW
within age group (BWPA), and PA similarly adjusted to
the median lean BW (LBWPA). Dam parity, sire, prebreeding
age, prebreeding BW, and prebreeding BCS
were associated with PA whereas dam parity, sire, own BWT, PA, AI bull, and calf gender were associated with
calf BWT (P < 0.05). Dam parity, calf BWT, and either
BWPA or LBWPA were the only independent predictors
of dystocia (P < 0.05). Adjusting PA to BW or lean BW
(LBW) improved the sensitivity and specificity to predict
dystocia. After hypothetical culling by PA, retained
heifers were heavier and had a higher calving rate and
calves tended to be heavier at birth compared to culled
heifers, but dystocia rates were not different. Culling by
APA resulted in similar effects, except that dystocia rate
tended to be lower in retained heifers. Culling by PA:BW
resulted in lower dystocia rate in retained than in culled
heifers, but retained heifers had lower prebreeding BW
than culls. Culling by BWPA and LBWPA resulted in
lower proportions with dystocia and a tendency towards
higher calving rates in the retained heifers, without affecting
the prebreeding BW or calf BWT. It is concluded that
pelvimetry is a useful culling tool to aid in the management
of dystocia in yearling heifers and that adjustment
of PA to median BW or LBW within age group improves
its accuracy and avoids the undesirable side effects.http://www.animal-science.org/hb201
Pre-breeding blood urea nitrogen concentration and reproductive performance of Bonsmara heifers within different management systems
This study investigated the association between
pre-breeding blood urea nitrogen (BUN) concentration and
reproductive performance of beef heifers within different
management systems in South Africa. Bonsmara heifers (n=
369) from five herds with different estimated levels of nitrogen
intake during the month prior to the commencement of the
breeding season were sampled in November and December
2010 to determine BUN concentrations. Body mass, age,
body condition score (BCS) and reproductive tract score
(RTS) were recorded at study enrolment. Trans-rectal ultrasound
and/or palpation was performed 4â8 weeks after a 3-
month breeding season to estimate the stage of pregnancy.
Days to pregnancy (DTP) was defined as the number of days
from the start of the breeding season until the estimated
conception date. Logistic regression and Cox proportional
hazards survival analysis were performed to estimate the
association of pre-breeding BUN concentration with subsequent
pregnancy and DTP, respectively. After stratifying for
herd and adjusting for age, heifers with relatively higher prebreeding
BUN concentration took longer to become pregnant
when compared to those with relatively lower BUN concentration
(P=0.011). In the herd with the highest estimated
nitrogen intake (n=143), heifers with relatively higher BUN
were less likely to become pregnant (P=0.013) and if they did,
it was only later during the breeding season (P=0.017), after
adjusting for body mass. These associations were not present
in the herd (n=106) with the lowest estimated nitrogen intake
(P>0.500). It is concluded that Bonsmara heifers with relatively
higher pre-breeding BUN concentration, might be at a
disadvantage because of this negative impact on reproductive performance, particularly when the production system includes
high levels of nitrogen intake.Faculty of
Veterinary Science, University of Pretoriahttp://link.springer.com/journal/112502015-08-31hb201
Seminal transmission of lumpy skin disease virus in heifers
It is known that lumpy skin disease virus (LSDV) can be shed in bull semen following infection
and that artificial insemination (AI) poses a biosecurity risk. It is however not known whether
the use of LSDV infected semen in AI poses a biosecurity risk. The aims of the current study
were to investigate whether LSDV, transmitted through semen, can infect cows and embryos..
Two controlled trials were performed simultaneously. Eleven (11) young beef heifers, naĂŻve to
LSDV, were synchronized using an OvSynch protocol and inseminated with fresh semen
spiked with a field strain of LSDV on day 0. Six (6) of the heifers were superovulated on Day 1
using PMSG, and embryos were flushed from these heifers on Day 6. Blood and serum
samples were collected from Day 4 until Day 27 to determine the presence of LSDV by PCR
and virus isolation, and the presence of antibodies against LSDV by SNT.
The first clinical signs of LSD were noticed on Day 10, followed by severe generalized LSD in
3 heifers, and mild LSD in 2 more heifers. Two heifers were humanely euthanized due to
severe unresponsive stranguria. LSDV was detected by PCR, virus isolation or electron
microscopy in blood, embryos and organs of experimentally infected animals, and 8 heifers
had seroconverted by Day 27. Two control animals were not affected.
This is the first report of experimental seminal transmission of LSDV in cattle.NRF. Project number FA 200704250000.http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1865-16822015-10-31hb201