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Selection of Abstracts
taken from the EAAP restricted site |
DOWNLOADABLE FILE
The following abstracts are taken
from the restricted site of EAAP available at:
http://www.eaap.org/content/researchers_database.htm
Animal health and
management – Cattle
Gasser, C. L. Behlke E. J., Grum D.
E., Day M. L. (2006) “Effect of timing of feeding a high-concentrate
diet on growth and attainment of puberty in early-weaned heifers”.
Journal of Animal Science, (84), 11 pp 3118-3122.
KEYWORDS: early weaning, heifer,
phase feeding, puberty.
SUMMARY: Precocious puberty (<300 d
of age) can be successfully induced in a majority of heifers with
early weaning and continuous feeding of a high-concentrate diet. The
objective of this experiment was to determine the relative effects
of timing of feeding a high-concentrate diet on age at puberty in
early-weaned heifers. Sixty crossbred Angus and Simmental heifer
calves were weaned at 112±2 d of age and 155±3 kg of BW and were fed
a receiving diet for 2 weeks. Heifers were blocked by age and BW,
and assigned randomly to receive a high-concentrate (60% corn; H) or
control (30% corn; C) diet during phase 1 (mean age 126 to 196 d)
and H or C during phase 2 (mean age 196 to 402 d), resulting in four
treatments (HH, n = 15; HC, n = 15; CH, n = 15; and CC, n = 15).
Blood samples were collected weekly beginning at a mean age of 175 d
and assayed for progesterone concentration to determine age at
puberty. After 56 d on the experimental diets, BW of heifers fed the
H diet during phase 1 were greater (P < 0.05) than those of heifers
fed the C diet (mean age of 182 d; treatment x mean age, P < 0.01).
After 70 d on the new diets (mean age of 266 d), heifers fed the H
diet during phase 2 reached heavier BW (P < 0.05) than heifers fed
the C diet, when compared within phase 1 diet groups (HH > HC; CH >
CC). Body weights in HC and CH treatments differed from a mean age
of 169 through 238 d, after which BW did not differ between these
treatments. The ADG over the entire experimental period was greatest
for the HH treatment (1.2±0.04 kg/d; P < 0.05), followed by the HC
and CH treatments (1.0±0.03 and 1.0±0.02 kg/d, respectively), which
were not different, and the CC treatment gained the least (0.7±0.04
kg/d; P < 0.05). Precocious puberty occurred in 67, 47, 47, and 20%
of heifers in the HH, HC, CH, and CC treatments, respectively (HH >
CC; P < 0.05). Mean age at puberty for the HH and HC treatments
(271±17 and 283±17 d of age, respectively) was earlier (P < 0.05)
than for the CC treatment (331±11 d of age). Age at puberty in the
CH treatment (304±13 d of age) was intermediate to and not different
from the other treatments. Heifers fed the H diet during phase 1
attained puberty earlier (P < 0.05) than heifers fed the C diet
during phase 1. In conclusion, increasing dietary energy intake in
early-weaned heifers, through feeding a high-concentrate diet from
126 to 196 d of age, decreased age at puberty regardless of the diet
fed after 196 d of age.
Animal health and
management – Wild animals
Haydon D.T., Randall D.A., Matthews
L., Knobel D.L., Tallents L.A., Gravenor M.B., Williams S.D.,
Pollinger J.P., Cleaveland S., Woolhouse M.E.J., Sillero-Zubiri C.,
Marino J., Macdonald D.W., Laurenson M.K. (2006) “Low-coverage
vaccination strategies for the conservation of endangered species”.
Nature 443(7112):692-5.
KEYWORDS: vaccine, epidemics,
population, dynamics, disease, management
SUMMARY: The conventional objective
of vaccination programmes is to eliminate infection by reducing the
reproduction number of an infectious agent to less than one, which
generally requires vaccination of the majority of individuals. In
endangered wildlife population, the intervention required to deliver
such coverage can be undesirable and impractical. However,
endangered populations are increasingly threatened by outbreaks of
infectious diseases for which effective vaccines exist. As an
alternative, wildlife epidemiologists could adopt a vaccination
strategy that protects a population from the consequences of only
the largest outbreaks of diseases. In the Ethiopian wolf, the world
rarest canid, which persists in small subpopulations threatened by
repeated outbreaks of rabies introduced by domestic dogs provides a
successful example of this strategy. On the basis of data from past
outbreaks, an approach is proposed that controls the spread of
disease through habitat corridors between subpopulations and that
requires only low vaccination coverage. This approach reduces the
extent of rabies outbreaks and should significantly enhance the
long-term persistence of the population. The study shows that
vaccination used to enhance metapopulation persistence through
elimination of the largest outbreaks of disease requires lower
coverage than the conventional objective of reducing the
reproduction number of an infectious agent to less than one.
Animal nutrition -
Cattle
Vasconcelos J. T., Greene L. W., Cole
N. A., Brown M. S., McCollum F. T., Tedeschi L. O. (2006) “Effects
of phase feeding of protein on performance, blood urea nitrogen
concentration, manure nitrogen:phosphorus ratio, and carcass
characteristics of feedlot catte”. Journal of Animal Science, (84),
11 pp 3032-3038.
KEYWORDS: environment, feedlot,
nitrogen, phase feeding, phosphorus
SUMMARY: Two experiments with a
randomized complete block design were conducted to determine the
effects of phase feeding of CP on performance, blood urea nitrogen (BUN),
manure N:P ratio, and carcass characteristics of steers fed in a
feedlot. In Exp. 1, 45 crossbred steers (initial BW = 423±3.3 kg)
were individually fed a diet formulated to contain 13.0% CP (DM
basis) for 62 d. On d 63, the dietary CP was maintained at 13.0% or
formulated to contain 11.5 or 10.0% CP until slaughter. Actual CP
values were 12.8, 11.8, and 9.9%, respectively. Reducing the CP
concentration of the diet did not affect ADG of steers from d 62 to
109 (P = 0.54) or over the 109-d feeding period (1.45, 1.50, and
1.49 kg/d for 13.0, 11.5, and 10.0% CP, respectively; P = 0.85). No
differences (P > 0.12) among treatments were detected for BUN
concentrations on d 0, 62, or 109. Gain:feed, DMI, and carcass
characteristics did not differ among treatments (P>0.10). In Exp. 2,
two trials were conducted using 184 (initial BW=406±2.6 kg) and
162 (initial BW=342±1.9 kg) crossbred steers. Data from the two
trials were pooled for statistical analysis, and trial effect was
added to the statistical model. Steers were fed a diet formulated to
contain 13.0% CP until reaching approximately 477 kg. When the
average BW of the pen was 477 kg, diets were maintained at 13.0% CP
or reduced to contain 11.5 or 10.0% CP. Actual CP values were 12.4,
11.5, and 9.3% CP for treatments 13.0, 11.5, and 10.0% CP,
respectively. Reducing the CP content of the diet did not affect ADG
after the diet changed (P=0.16) or throughout the finishing period
(P=0.14). Immediately before slaughter, steers fed the 13.0% CP diet
had greater (P < 0.001) BUN concentrations than steers fed the 11.5
and 10.0% CP diets. Carcasses from cattle fed the 11.5% CP diet had
greater (P = 0.02) fat thickness than the 13.0 and 10.0% CP
treatments, whereas carcasses from cattle fed 13.0% CP had greater
(P=0.004) marbling scores than steers fed the 11.5 or 10.0% CP diets.
Other carcass characteristics, DMI, and G:F did not differ (P >
0.10) among treatments. The N:P ratio was increased with the 10.0%
CP diet (P=0.02) compared with the 11.5 or 13.5% CP treatments;
however, manure composition did not differ (P>0.10) among treatments.
These results indicate that reduced CP concentration during the
finishing period does not affect feedlot performance but can improve
the N and P relationship in the manure.
Animal nutrition -
Cattle
Suárez B. J., Van Reenen C. G.,
Beldman G., van Delen J., Dijkstra J., Gerrits W. J. J. (2006)
“Effects of Supplementing Concentrates Differing in Carbohydrate
Composition in Veal Calf Diets: I. Animal Performance and Rumen
Fermentation Characteristics”. Journal of Dairy Science (89), 11 pp
89: 4365-4375.
KEYWORDS: veal calf, concentrate feed
composition, rumen fermentation, enzyme activity.
SUMMARY: The aim of this experiment
was to examine the effects of concentrates in feed, differing in
carbohydrate source, on the growth performance and rumen
fermentation characteristics of veal calves. For this purpose, 160
Holstein Friesian x Dutch Friesian crossbred male calves were used
in a complete randomized block design with a 5x2 factorial
arrangement. Dietary treatments consisted of 1) milk replacer
control, 2) pectin-based concentrate, 3) neutral detergent
fiber-based concentrate, 4) starch-based concentrate, and 5) mixed
concentrate (equal amounts of concentrates of treatments 2, 3, and
4). Concentrate diets were provided as pellets in addition to a
commercial milk replacer. Calves were euthanized either at the end
of 8 or 12 weeks of age. The overall dry matter intake of the
concentrate diets varied between 0.37 and 0.52 kg/d. Among the
concentrate diets, the dry matter intake was lower in the starch
diet (0.37 kg/d of dry matter) and differed between the NDF and
pectin diets. The average daily gain for all the dietary treatments
varied between 0.70 and 0.78 kg/d. The mixed- and NDF-fed calves had
an increased average daily gain (0.78 and 0.77 kg/d, respectively)
compared with the starch- and pectin-fed calves (0.70 and 0.71 kg/d,
respectively). Rumen fermentation in the calves fed concentrates was
characterized by a low pH (4.9 to 5.2), volatile fatty acid
concentrations between 100 and 121 mmol/L, and high concentrations
of reducing sugars (33 to 66 g/kg of dry matter). The volatile fatty
acid concentrations of calves fed concentrates were higher than
those of the control calves. All concentrate treatments showed a low
acetate-to-propionate ratio in rumen fluid (between 1.3 and 1.9).
Among the concentrates, the NDF diet had the highest (55.5%) and
starch the lowest (45.5%) molar proportions of acetate. Calves fed
the mixed, pectin, and starch diets had significantly higher molar
proportions of butyrate (13.1 to 15.8%) than the NDF- and
control-fed groups (9.9 and 9.6%, respectively). Calves fed the
control diet had a higher lactate concentration (21 mmol/L) than the
concentrate-fed calves (between 5 and 11 mmol/L). With the exception
of the NDF diet, polysaccharide-degrading enzyme activities in the
rumen contents generally showed an adaptation of the microorganisms
to the carbohydrate source in the diet. The mixed diet exhibited the
least variation in rumen polysaccharide-degrading enzyme activities
among the enzymes systems tested. Results indicated that the
carbohydrate source can influence intake, growth rate, and rumen
fermentation in young veal calves.
Rural development
- Aquaculture
Liti D., Cherop L., Munguti J; &Chhorn
L.(2005).Growth and economic performance of Nile tilapia (O.niloticus
L.) fed in two formulated diets and two locally available feeds in
fertilized ponds” Aquaculture Research (36),pp: 746-752
KEYWORDS: Aquaculture, tilapia,
O.niloticus
SUMMARY: In the group of tilapias,
Nile tilapia O.niloticus is the most farmed in Africa sub-Saharan.
eighther for subsistence and commercial purposes(the culture
practices are generally semi intensive). In this care, according to
the authors, for semi intensive production of O. niloticus in Kenya
– two isonitrogenous (24°/°) protein diets were formulated and
evaluated for production of O.niloticus in fertilized ponds. One
diet contain vitamin and minerals premix (CW).Growth of fish fed on
the formulated feeds was compared with groups of fish fed on
commercial pig pellets (PP) and wheat bran(WB). The authors
concluded that there was significant differences in mean weights,
growth rates, and feed conversion ratios between the formulated and
the other diets even though no significant differences were observed
between (CV), (CW) and also between (PP) and (WB). As a conclusion,
the results obtained suggest that vitamins and mineral premix may
not be necessary in diets for semi intensive production of
O.niloticus .
Immunology and
endocrinology - Aquaculture
Palstra A.P., Cohen E.G.H.,
niemantverdriet P.R.W., Ginneken Van V.J.T., Thillar van den
G.E.E.J.M. (2005).”Artificial maturation and reproduction of
European silver eel: Development of oocytes during final maturation”.
Aquaculture(249), pp: 533 – 547
KEYWORDS: Endocrinology, silver eel,
fertilisation
SUMMARY: Low fertility and hatching
rates are found in European eel and other commercial species notably
marine fish species. The moment of stimulation of final maturation
and ovulation is mainly based on weight increase related to the
hybridation response of the oocyte which in European eel is
irregular. In contrast with the Japanese eel (Anguilla japonica)
where reproduction became successful, the European eel show wide
individual variability and much slower responses to hormonal
stimulation. In this study, the oocyte development of wild European
silver eel was studied during final maturation. Ovulation was
induced between 10 and 24H after DHP injection with most females (8
out of 14) in a quiet narrow range of 13H 14.5H after DHP injection.
Authors described seven developmental stages based on six parameters:
transparency, position and visibility of the nucleus, diameter of
the oocyte, diameter and number of oil droplets. Together these
parameters describe unidirectional changes from immature to overripe
eggs.
Meat science –
Cattle, pigs
Ramirez CA, Patel M, Blok K (2006)
“How much energy to process one pound of meat? A comparison of
energy use and specific energy consumption in the meat industry of
four European countries”, Energy 31 (12): 2047-2063
KEYWORDS: energy efficiency; meat
sector; specific energy consumption
SUMMARY: In this paper, we have used
energy and physical production data to develop energy efficiency
indicators for the meat industry of four European countries for the
last 15 years. Our results show a significant increase in the energy
use per tonne of product in all countries (between 14% and 48%). In
order to understand the drivers behind the trends, factors such as
the share of frozen products, the share of cut-up products and
increasing food hygiene measures are being analysed. We find that
strong hygiene regulations can explain between one and two-thirds of
the increase while the role of increasing shares of frozen and cut
fresh meat is found to be of no significance.
Animal nutrition,
Extensive systems, Meat science - Pigs
Tikk M, Tikk K, Torngren MA, Meinert
L, Aaslyng MD, Karlsson AH, Andersen HJ (2006) “Development of
inosine monophosphate and its degradation products during aging of
pork of different qualities in relation to basic taste and
retronasal flavor perception”. The meat Journal of Agricultural and
Food Chemistry 54 (20): 7769-7777
KEYWORDS: pork; meat quality; flavor;
IMP; brothy; hypoxanthine; bitterness; beef; 5'-monophosphate;
storage; ribose; loin
SUMMARY: Inosine monophosphate (IMP)
and its degradation products, ribose and hypoxanthine, are all
considered to be important constituents in meat flavor formation and
development. The present study explored the fate of IMP during the
aging of two qualities of pork (pH>5.7 and pH<5.6-5.5) and the
potential relationship between IMP, hypoxanthine, and sensory
attributes of pork registered both as retronasal and basic taste
responses in whole meat, meat juice, and the remaining meat residue.
During aging the concentration of IMP decreased with a simultaneous
increase in the concentrations of inosine, hypoxanthine, and ribose.
The rates at which IMP was degraded to inosine and inosine to
hypoxanthine during aging were found to be in agreement with the
known rate constants of the dephosphorylation of IMP and the
hydrolysis of inosine, respectively. Moreover, high-pH pork resulted
in a significantly higher concentration of hypoxanthine throughout
storage compared with low-pH pork due to an initially higher
concentration of IMP in high-pH meat. The sensory analysis showed
increasing intensity in bitterness and saltiness of pork as a
function of aging, with the intensity being most pronounced in the
meat juice. The increasing bitterness of the pork as a function of
aging coincided with the higher content of hypoxanthine in these
samples, thereby suggesting that degradation of IMP to hypoxanthine
might influence pork flavor. In contrast, IMP was associated with
nonaged meat and the sensory attributes meaty and brothy.
Animal nutrition,
Extensive systems, Feeds and feed technology - Cattle
Theodorou MK, Kingston-Smith AH,
Winters AL, Lee MRF, Minchin FR, Morris P, MacRae J (2006)
“Polyphenols and their influence on gut function and health in
ruminants: a review” Environmental Chemistry Letters 4 (3): 121-126
KEYWORDS: rumen; ruminant; livestock;
microbiology; anaerobic; proteolysis; polyphenol oxidase; polyphenol;
water soluble carbohydrate; red clover; dairy cows; digestion; plant;
proteolysis; herbage; protein; forage; sheep
SUMMARY: Polyphenols in plants can
protect proteins from degradation and improve the efficiency of
conversion of plant protein into animal protein (meat and milk), but
can this be achieved in a way that is environmentally sustainable,
profitable to the livestock farmer and is it consistent with
aspirations for improved livestock nutrition, health, welfare and
product quality? Given that grazed and conserved forage is the
bedrock of sustainable ruminant production, this paper attempts to
consider what challenges are ahead in terms of enhancing productive
efficiency, reducing the polluting footprint of livestock
agriculture and alleviating the endemic parasitism that occurs with
grazing animals.
Animal agriculture
– Cattle
Nielsen H.M., Christensen L.G.,
Odegard J. (2006) “A method to define breeding goals for sustainable
dairy cattle production”. J. Dairy Sci. 89 (9):3615-25.
KEYWORDS: breeding objective; desired
gain index; sustainability
SUMMARY: The objective of this study
was to present a method to define breeding goals for sustainable
dairy cattle production by adding non-market values to market
economic values for functional traits in the breeding goal. A
non-market value can represent the value of improved animal welfare
or societal influences for animal production. The non-market value
for mastitis resistance, conception rate, and stillbirth were
derived, based on how much farmers or breeding companies were
willing to lose in selection response for milk yield to improve
functional traits. The desired response for milk yield corresponding
to a given percent loss was obtained using desired gain indices. By
allowing a 5% loss in the selection response for milk yield, the
non-market value was found to be 40.4€ for mastitis resistance,
16.1€ for conception rate, and -9.7€ for stillbirth. The non-market
value increased proportionally with increasing loss in the selection
response for milk yield, but the selection response was lower for
conception rate than for mastitis resistance because of differences
in market economic value and heritability. To increase the response
for conception rate, the non-market value was also derived for two
situations, in which the desired responses for milk yield, mastitis
resistance, and conception rate were specified. The method can be
used to define breeding goals for sustainable production and to
increase the response for traits that are at critically low levels.
When defining breeding goals for sustainable production, breeding
organizations should predict the selection response based on market
economic value and add non-market value for traits with unacceptable
selection.
Animal behaviour
and welfare – General
Spinka M. (2006) “How important is
natural behaviour in animal farming systems?”. Applied Animal
Behaviour Science 100 (1-2): 117-128.
KEYWORDS: welfare; natural behaviour;
housing; motivation; emotions
SUMMARY: It is often assumed and
demanded that for a good welfare, farm animals should be given “the
freedom to express their natural behaviour”. This demand is
problematic for at least two reasons. First, natural behaviour is
difficult to delineate because of its variability and flexibility.
Second, some behavioural patterns that are clearly natural are in
fact detrimental to animal welfare. These include emergency
behaviours such as flight reactions that bring the animal into a
state of stress without achieving the goal for which the behaviour
had evolved and damaging behaviours such as rank-related or
illness-related aggression during which animals inflict injuries or
deprive their penmates of resources. Nevertheless, when these
reservations are taken into account, opening possibilities for
natural behaviour may be useful as guidance for improving the
existing husbandry systems. Specifically, providing the farm
environment with the key features towards which the behaviour was
originally adapted brings three classes of benefits. First, it is
often more efficient to allow animals to satisfy their own needs and
achieve their goals than to address these needs and goals through
technical means. Second, a large class of natural behaviours is
associated with positive affective experience, and thus their
performance directly enhances animal welfare. Third, the performance
of natural behaviour in its richness and complexity often brings
long-term benefits for the animal, such as improved proficiency in
coping with social and physical challenges. Thus, while the freedom
to perform the whole repertoire of natural behaviour is not per se
crucial for farm animal welfare, the opportunity to perform natural
behaviour may be an effective way to improve their welfare in
practice immediately, and a promising basis for the future design of
husbandry systems.
Animal genetic
resources - Sheep
J. R. S. Meadows, O. Hanotte, C.
Drögemuller, J. Calvo, R. Godfrey, D. Coltman, J. F. Maddox, N.
Marzanov, J. Kantanen, J. W. Kijas (2006) “Globally dispersed Y
chromosomal haplotypes in wild and domestic sheep.” Animal Genetics,
37, 444-453.
KEYWORDS: breed diversity, haplotype,
sheep, Y chromosome.
SUMMARY: the authors present the
first analysis of both domestic and wild sheep using genetic markers
residing on the ovine Y chromosome. Analysis of a single nucleotide
polymorphism (oY1) in the SRY promoter region revealed that allele
A-oY1 was present in all wild bighorn sheep (Ovis canadensis), two
subspecies of thinhorn sheep (Ovis dalli), European Mouflon (Ovis
musimon) and the Barbary (Ammontragis lervia). Sequence analysis of
a second locus, microsatellite SRYM18, revealed a compound repeat
array displaying fixed differences, which identified bighorn and
thinhorn sheep as distinct from the European Mouflon and domestic
animals. Combined genotypic data identified 11 male-specific
haplotypes that represented at least two separate lineages. The
remaining haplotypes each displayed more restricted and informative
distributions. For example, H5 was likely founded following the
domestication of European breeds and was used to trace the recent
transportation of animals to both the Caribbean and Australia.
Animal genetic
resources - Cattle
European Cattle Genetic Diversity
Consortium (2006) “Marker-assisted conservation of European cattle
breeds: an evaluation.” Animal genetics, 37, 475–481.
KEYWORDS: cattle, conservation,
genetic diversity, kinship, microsatellite, Weitzman.
SUMMARY: in this work two methods
have been developed for the assessment of conservation priorities on
the basis of molecular markers. According to the Weitzman approach,
contributions to genetic diversity are derived from genetic
distances between populations. Alternatively, diversity within and
across populations is optimized by minimizing marker-estimated
kinships. The authors have applied, for the first time, both methods
to a comprehensive data set of 69 European cattle breeds, including
all cosmopolitan breeds and several local breeds, for which
genotypes of 30 microsatellite markers in 25–50 animals per breed
have been obtained. Weitzman-derived diversities were confounded by
genetic drift in isolated populations, which dominates the genetic
distances but does not necessarily increase the conservation value
of a breed. Marker-estimated kinships across populations were less
disturbed by genetic drift than the Weitzman diversities and
assigned high conservation values to Mediterranean breeds, which
indeed have genetic histories that differ from the non-endangered
breeds.
Animal genetic
resources – Wild animals
Reuter B.A., Bertouille E., and Voyel
P. (2005).”The diet of Alpine mouse Apodemus alpicola in the Swiss
Alp”. Mamm.biol.(70), pp: 147-149
KEYWORDS: Diet, Apodemus alpicola,
Swiss Alp
SUMMARY: It is commonly known that
the faecal analysis contribute to determine the diet of wild animals.
According to the authors, the investigation concerns the diet of
Alpine mousse A. apicola in the field for the first time. This
species consumes mainly insects in spring, fruit and seeds of some
vegetables (dicotyledones) in summer and autumn. As signalled in
literature this species is endemic in the Alps, often been found in
sympathy with two other species A.sylvaticus (Linnaeus, 1758) and A.
flavicollis (Melchiou, 1834), even though the model studied (A.
apicola) was originally considered as a high subspecies of A.
flavicollis (Heinrich, 1951, 1952) and later described as a new
species using morphological criteria, and subsequently confirmed
with biochemical tools. The diet of A. alpicola is rich in contrast
with comparison to the two congeneric species, with a big difference
between spring and autumn. However, the absence of the seeds
suggests a terrestrial behaviour of the species.
Molecular genetics
- Poultry
Raman M. Das, Nick J. Van Hateren,
Gareth R. Howell, Elizabeth R. Farrell, Fiona K. Bangs, Victoria C.
Porteous, Elizabeth M. Manning, Michael J. McGrew, Kyoji Ohyama,
Melanie A. Sacco, Pam A. Halley, Helen M. Sang, Kate G. Storey,
Marysia Placzek, Cheryll Tickle, Venugopal K. Nair, Stuart A. Wilson
(2006) “A robust system for RNA interference in the chicken using a
modified microRNA operon.” Developmental Biology, 294, 554–563.
KEYWORDS: chicken, embryo, RNA,
interference, microRNA, RNAi, siRNA.
SUMMARY: RNA interference (RNAi)
provides an effective method to silence gene expression and
investigate gene function. However, RNAi tools for the chicken
embryo have largely been adapted from vectors designed for mammalian
cells. The authors present plasmid and retroviral RNAi vectors
specifically designed for optimal gene silencing in chicken cells.
The vectors use a chicken U6 promoter to express RNAs modelled on
microRNA30, which are embedded within chicken microRNA operon
sequences to ensure optimal Drosha and Dicer processing of
transcripts. The chicken U6 promoter works significantly better than
promoters of mammalian origin and in combination with a microRNA
operon expression cassette (MOEC), achieves up to 90% silencing of
target genes. By using a MOEC, we show that it is also possible to
simultaneously silence two genes with a single vector. The vectors
express either RFP or GFP markers, allowing simple in vivo tracking
of vector delivery. The efficiency and ease of use of this RNAi
system paves the way for large-scale genetic screens in the chicken
embryo.
Growth and
development, Molecular genetics - Poultry
Winner, D.G., Ealy, A. D., Hannon,
K., Johnson, S. E. 2006. “Ectopic insulin-like growth factor I
expression in avian skeletal muscle prevents expression of CMD4, a
novel inhibitor of differentiation”. Domestic Animal Endocrin. 31:
342-326.
KEYWORDS: IGF-I; Myogenesis; Chick
embryo; Gene expression
SUMMARY: Embryonic chick skeletal
muscle undergoes profound hypertrophy in response to ectopic IGF-I
resulting in two- to three-fold increase in total muscle mass. IGF-I
likely causes several changes in gene expression profiles to elicit
the robust effect. To identify genes differentially affected by
IGF-I, total RNA was isolated from the hindlimbs of chick embryos
infected with RCAS or RCAS-IGF-I and used in a subtractive library
screen. CMD4 was identified as a novel, avian-specific gene
expressed in muscle. In situ mRNA analysis reveals that the gene
product is expressed in multiple tissues including skeletal muscle.
Ectopic expression of IGF-I within the hindlimb results in a
reduction in CMD4 mRNA to levels below conventional detection
limits. A chimeric CMD4-yellow fluorescent protein (CMD4-YFP)
demonstrates an indiscriminant localization pattern throughout the
cytoplasm and nucleus of myoblasts. By contrast to control C2C12
myoblasts, a stable muscle cell line that expresses CMD4-YFP
(C2C12-CMD4-YFP) is unable to form the large multinucleated cells
characteristic of mature myofibers. The differentiation defective
myoblasts do not express myosin heavy chain but the relative amounts
of myogenin, desmin and troponin proteins do not differ from
controls. The transcriptional activity of the myogenic regulatory
factors (MRFs) remains unchanged by CMD4 expression. We report the
identification of an IGF-I inhibited gene present in skeletal muscle.
While the mechanism of CMD4-mediated inhibition of muscle
development remains elusive, we propose that loss of CMD4 gene
expression may be required for optimal muscle hypertrophy in the
chick embryo.
Growth and
development – Sheep and goats
Smith, L. B., Dally, M. R., Sainz, R.
D., Rodriguez, K. L., Oberbauer, A. M. 2006. “Enhanced skeletal
growth of sheep heterozygous for an inactivated fibroblast growth
factor receptor 3”. J. Anim Sci. 84: 2942-2949.
Keywords: Inactivated fibroblast
growth factor receptor 3, longissimus muscle area, sheep, skeletal
growth, spider lamb syndrome
SUMMARY: Normal fibroblast growth
factor receptor 3 (FGFR3) acts as a negative bone growth regulator
by restricting chondrocyte proliferation and endochondral bone
elongation. In sheep, a heritable mutation that inactivates FGFR3
produces skeletal overgrowth when homozygous, this condition is
commonly referred to as spider lamb syndrome (SLS). We hypothesized
that sheep heterozygous for the inactivated FGFR3 mutation
(FGFR3SLS/+) would exhibit enhanced long bone growth and greater
frame size; additionally, the isolated effects of increased bone
growth would translate into greater BW and larger LM area relative
to normal lambs at slaughtering. The current study investigated bone
length and LM area of FGFR3SLS/+ sheep at maturity and during growth.
At maturity, FGFR3SLS/+ ewes exhibited a larger frame size and
longer bones than normal FGFR3+/+ ewes (P<0.05). Similarly,
FGFR3SLS/+ lambs had greater frame sizes than normal FGFR3+/+ lambs,
as indicated by increased metacarpal III length and height at
withers (P<0.05). The FGFR3SLS/+ lambs took longer than the normal
FGFR3+/+ lambs to reach the 60-kg common BW slaughtering end point
(P<0.05). The FGFR3SLS/+ lambs showed no difference in BW, ADG, or
LM area at any age compared with normal FGFR3+/+ lambs (P>0.2). A
similar LM area produced in the context of a greater frame size and
skeletal length produces a greater muscle volume, thereby
potentially increasing meat yield. The results of this study suggest
that FGFR3SLS/+ animals exhibit a relaxation of the normal
inhibition of chondrocyte proliferation, resulting in an increase in
the overall frame size. The sheep industry could utilize the
naturally occurring genetic mutation in FGFR3 to potentially
increase meat yields with enhanced skeletal growth as an alternative
to exogenous growth promotants.
Growth and
development – Pigs
Sensky, P. L., Jewell, K. K., Ryan,
K. J. P., Parr, T., Bardsley, R. G., Buttery P. J. 2006. “Effect of
anabolic agents on calpastatin promoters in porcine skeletal muscle
and their responsiveness to cyclic adenosine monophosphate-and
calcium-related stimuli”.J. Anim Sci. 84:2973-2982.
Key words: Calpastatin, Calpastatin
expression, Growth promoter, Pig, Skeletal muscle
SUMMARY: The calpain proteinases and
their specific inhibitor calpastatin have been proposed to influence
both the rates of myofibrillar protein turnover in vivo and meat
tenderization postmortem. Elevated calpastatin concentrations in
particular are associated with certain forms of hypertrophic growth
and meat toughness. In the 5’region of the porcine calpastatin gene,
there are three calpastatin promoters upstream of exons 1xa, 1xb,
and 1u, respectively, each of which contain transcription
factor-binding motifs, suggesting sensitivity to a variety of
growth-promoting stimuli. This study examined the effect of the
ß-adrenergic agonist clenbuterol and of porcine ST (pST) treatment
on calpastatin promoter usage in porcine LM in vivo, using real-time
PCR and also the responsiveness of transfected calpastatin promoter
sequences to cyclic adenosine monophosphate (cAMP) and calcium
(Ca2+)-related stimuli in reporter gene systems in cell studies. The
effect of clenbuterol and pST on potential signaling pathways in
vivo was also assessed by monitoring protein phosphatase 2B (calcineurin),
NFATc3, calpain 3, IkBa, and NFkB by quantitative immunoblotting.
Total calpastatin mRNA was increased by 52% (P<0.05) after treatment
with clenbuterol for one day and reduced by 35% (P<0.01) after pST
treatment for seven days. Whereas clenbuterol had no significant
differential effects on individual mRNA transcripts (types 1 to 3)
derived from the three upstream promoters, pST significantly reduced
all of these by 51, 39, and 40% (P<0.001, 0.05, and 0.05),
respectively. Promoter activity was increased in rat L6G8 cells
transfected with a construct derived from exon 1u after treatment
with dibutyryl cAMP (68%, P<0.05) or forskolin (43%, P<0.05),
whereas 1xa activity was reduced by both of these agents (47 and
33%, respectively, P<0.05). Treatment of cells with the calcium
ionophore calcimycin reduced the activity of the 1u promoter by 40%
(P<0.01), with no effect on the other promoter constructs.
Cyclosporin A had no effect on any promoter construct. The only
signaling pathway component to be significantly altered by the in
vivo treatments was calcineurin, which was decreased by 24% (P <
0.05) in clenbuterol-treated animals. In conclusion, two types of
growth promoter in pigs had contrasting effects on calpastatin
expression in LM. Transfected calpastatin promoters were
differentially sensitive to cAMP- and Ca2+-related stimuli, in
agreement with the proposed mode of action of the two growth
promoters.
Genetics, breeding
and selection - Cattle
J.A. MacArthur Clark, M. Potter, E.
Harding. 2006. “The welfare implications of animal breeding and
breeding technologies in commercial agriculture”. Livestock Science,
103 (3): 270-281
KEYWORDS: Welfare, Breeding
technologies, Ethics, Genetic modification, Cloning
SUMMARY: On the one hand the
commercial applications in agriculture of new breeding technologies,
as well as conventional breeding strategies, have the potential to
influence animal welfare in both positive and negative ways. For
example, the sexing of cattle semen might be used to reduce the
number of unwanted male dairy calves provided that the technique had
not been shown to produce adverse effects. On the other hand,
inappropriate use of some breeding technologies may create new
problems, or exacerbate welfare problems that may already have
arisen within conventional livestock breeding. It is the impact of
any breeding technology or strategy that is important to welfare,
whether it is the quality of life of the offspring that is
compromised, or whether it is the application of the technology
itself that causes pain, distress or lasting harm to the subject
animal. The aim of this paper is to provide clear and practical
advice on the establishment of an appropriate framework within which
developments in animal breeding and breeding technologies, and the
outcome of such processes, may be considered, monitored and, where
necessary, regulated. It builds on recommendations recently made by
the FAWC to UK Government, and considers the wider public interest
in these technologies. Finally, the response from stakeholders is
considered in attempting to ensure that such controls do not render
production systems non-competitive in a global livestock industry.
Genetics, breeding
and selection - Pigs
S.P. Turner, I.M.S. White, S.
Brotherstone, M.J. Farnworth, P.W. Knap, P. Penny, M. Mendl, A.B.
Lawrence. 2006. “Heritability of post-mixing aggressiveness in
grower-stage pigs and its relationship with production traits”.
Animal Science, 82 (5): 615-620
KEYWORDS: aggression, heritability,
lesions, pigs, selection
SUMMARY: Mixing of commercial pigs
frequently leads to intense aggression. Considerable phenotypic
variation exists between individuals and selection against
aggressiveness may offer a long-term reduction in aggression without
incurring additional costs to the primary producer. The genetic
contribution to aggressiveness was quantified in this study using
the number of skin lesions as an indicator of involvement in
aggression. A sample of 1132 pigs were mixed at an average weight of
27.9 (s.d. 4.6) kg into 96 pens on a commercial sire line nucleus
unit. Post-mixing aggressiveness of pigs was assessed using the
lesion score (LS) approach. Growth rate, between 27.9 and 91.9 kg,
and backfat depth at 91.9kg were recorded for a subsample of 658
pigs. With a pedigree file of 1947 animals, a heritability of 0.22
was estimated for the LS trait. No significant genetic or phenotypic
correlations were found between LS and growth rate or backfat depth,
but standard errors of estimates were large. The response to
selection, when all selection pressure was placed on the LS trait,
was a 25% reduction in LS per generation. It is therefore
technically possible to select for a reduced LS without
substantially inhibiting genetic progress in growth rate or backfat
depth through antagonistic genetic relationships.
Genetics, breeding
and selection - Poultry
A. VIGNAL, B. BESBES. 2006. “The
chicken genome sequence and its utility for breeding”. INRA
Productions Animales, 19: 109-118
KEYWORDS: chicken genome sequence,
utility for breeding
SUMMARY: In December 2004, the first
version of the chicken genome sequence was published three years
only after the human one. This work is the result of more than ten
years of research in the field of chicken genomics, started by the
realisation of the first genetic maps, followed by that of BAC clone
libraries, cytogenetic maps including the microchromosomes,
radiation hybrid maps and the production of EST. Indeed, all the
mapping data available help in the assembly of the final sequence.
Of course, similar to the first version of the human sequence
assembly, the chicken one is not perfect and improvements, in
particular for the microchromosomes, will be necessary. Also, the
task of annotating the genome will have to be pursued. However, the
fact of having the genome sequence of an increasing number of
vertebrate animals will enable to refine our knowledge through
comparative studies. The availability of the chicken genome sequence
will enable replacing much of the molecular biology work that was
necessary for the determination of the structure, function and
polymorphism of genes by performing in silico analyses. This should
accelerate the development of molecular markers usable for the
selection of phenotypes of interest in livestock production systems.
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