A review of the genetic and epigenetic factors affecting lamb survival

2014 ◽  
Vol 54 (6) ◽  
pp. 667 ◽  
Author(s):  
F. D. Brien ◽  
S. W. P. Cloete ◽  
N. M. Fogarty ◽  
J. C. Greeff ◽  
M. L. Hebart ◽  
...  
Keyword(s):  
Direct Selection ◽  
Reproductive Efficiency ◽  
Maternal Behaviour ◽  
Sufficient Information ◽  
Management Options ◽  
Factors Affecting ◽  
Selection Strategies ◽  
Australian Sheep ◽  
Lamb Survival ◽  
Genetic Evaluations

Poor lamb survival pre-weaning is a major source of reproductive inefficiency in Australian sheep flocks. While nutrition and management options have been extensively researched and promoted to improve lamb survival, the present review focuses on the prospects for obtaining genetic gain and helps identify selection strategies for boosting such gains to improve overall reproductive efficiency in the Australian sheep industry. Estimated heritability for lamb survival using linear model analysis is low, although use of threshold models suggests that heritability could be higher, which, if true, could help explain the substantial genetic gains obtained in long-term selection experiments. Epigenetic mechanisms may hinder selection and quantitative trait-loci identification through confounding and/or masking genetic variances and co-variances. With sufficient information, these effects could be considered in genetic evaluations by identifying those components that are amenable to selection. Regarding indirect selection, finding effective criteria for improving lamb survival has proved elusive. Most measures of maternal behaviour, temperament and lambing difficulty researched are poorly correlated genetically with lamb survival. Of lamb behaviours and thermo-genic indicators studied, latency to bleat following handling by humans is moderately genetically correlated with lamb survival, as is neonatal rectal temperature. Industry application remains to be adequately explored for the more promising of these measures. Finally, in lieu of direct selection for lamb survival, there is merit in selecting for multiple-rearing ability or its equivalent, possibly with additional selection criteria for lamb survival and reproductive efficiency.

Lamb survival in Australian flocks: a review

2014 ◽  
Vol 54 (6) ◽  
pp. 656 ◽  
Author(s):  
G. N. Hinch ◽  
F. Brien
Keyword(s):  
Cold Resistance ◽  
Reproductive Efficiency ◽  
Maternal Behaviour ◽  
The Subject ◽  
Selection For ◽  
Lamb Survival

Lamb survival is known to be a key component of reproductive efficiency in sheep flocks. It has been the subject of a large number of studies over the decades and this review provides an update and insights into the latest understanding of the extent and variability of lamb losses across Australia. The pattern of causes of lamb losses, including dystocia, starvation/exposure, mismothering and predation, are examined. Likewise the importance of birthweight in contributing to such losses is discussed as are strategies for improving lamb survival. The strategies examined include improved ewe nutrition, shelter provision and selection for cold resistance and improved maternal behaviour.

Genetics of maternal behaviour in Scottish Blackface sheep under field conditions: factors affecting maternal behaviour scores and their influence on lamb live weights and survival

2000 ◽  
Vol 2000 ◽  
pp. 65-65
Author(s):  
N. R. Lambe ◽  
J. Conington ◽  
S. C. Bishop ◽  
A. Waterhouse ◽  
G. Simm
Keyword(s):  
Field Conditions ◽  
Flight Distance ◽  
Maternal Behaviour ◽  
Average Weight ◽  
Point Scale ◽  
Factors Affecting ◽  
Lamb Survival ◽  
Behaviour Score ◽  
First Time

Behavioural studies of sheep have shown that poor maternal behaviour by the ewe immediately postparturition can lead to reduced lamb survival and ewe production (O'Connor et al., 1985). Under field conditions, behaviour may be quantified by the maternal behaviour score (MBS) - a six-point scale assessing ewe flight distance when lambs(s) are handled for the first time, within 24 hours of birth (adapted from O'Connor et al., 1985). Greater scores are awarded to ewes remaining closer to their lamb(s). The objectives of this study were (1) to investigate the factors affecting MBS in Scottish Blackface ewes; (2) to determine if MBS affects the average weight of lambs reared or the number of lambs dying before weaning; (3) to estimate genetic and phenotypic parameters for MBS and correlations between MBS and lamb performance.

Pediatric Minor Head Trauma: Factors Affecting the Anxiety of Parents

2021 ◽  
pp. 000992282110096
Author(s):  
Hasan Aldinc ◽  
Cem Gun ◽  
Serpil Yaylaci ◽  
Erol Barbur
Keyword(s):  
Computed Tomography ◽  
Head Trauma ◽  
Pediatric Patients ◽  
Positive Impact ◽  
Cranial Computed Tomography ◽  
Sufficient Information ◽  
Minor Head Trauma ◽  
Computed Tomography Imaging ◽  
Factors Affecting ◽  
X Ray

Managing the anxiety of the parents of pediatric patients with head trauma is challenging. This study aimed to examine the factors that affect anxiety levels of parents whose children were admitted to the emergency department with minor head trauma. In this prospective study, the parents of 663 consecutive pediatric patients were invited to answer a questionnaire. Parents of 600 children participated in the study. The parents who believed they were provided sufficient information and who were satisfied with the service received had significantly more improvement in anxiety-related questions. Cranial X-ray assessment had a significantly positive impact on the anxiety of the parents, whereas cranial computed tomography and neurosurgery consultation did not. In assessing pediatric minor head trauma, cranial computed tomography imaging and neurosurgery consultation should not be expected to relieve the anxiety of the parents. However, adequately informing them and providing satisfaction are the factors that could lead to improvement.

scholarly journals Selection strategies in agronomic characters in progenies F3:4 of transgenic soy RR

2021 ◽  
Vol 45 ◽  
Author(s):  
Anna Regina Tiago Carneiro ◽  
Osvaldo Toshiyuki Hamawaki ◽  
Ana Paula Oliveira Nogueira ◽  
Arthur Felipe Eustáquio e Silva ◽  
Raphael Lemes Hamawaki ◽  
...  
Keyword(s):  
Agronomic Traits ◽  
Indirect Selection ◽  
Direct Selection ◽  
Selection Strategies ◽  
Aggregate Information ◽  
Genetic Potential ◽  
Superior Genotypes ◽  
Selection Indexes ◽  
Total Gain ◽  
Selection Of

ABSTRACT The selection indexes aggregate information to multiple characters and, with this, they are able to carry out the selection of a set of variables simultaneously. The objective was to verify the genetic potential of agronomic traits and to select soybean F3:4 progenies based on different selection strategies. 123 progenies and the parents were sown in randomized blocks with two replications. The gains of direct selection by the indexes, the sum of “ranks” and the genotype-ideotype were lower for all characters when compared to the gains of direct and indirect selection. The rank sum index stood out for achieving the highest total gain with 37.11%. The index of the genotype-ideotype obtained a lower gain (-0.48%) for the character number of days for flowering compared to the sum index of “ranks” (-0.54%) and reached a negative gain for the attribute insertion height of the first pod with -1.82%. The genetic potential of the F3:4 population is high and allows different selection strategies to be applied to reach superior genotypes. The progenies UFU 72, UFU 116, UFU 86, UFU 45, UFU 117, UFU 56, UFU 5, UFU 106, UFU 6, UFU 4, UFU 73, UFU 101, UFU 96, UFU 90, UFU 123, UFU 116, UFU 88, UFU 65, UFU 70, UFU 3, UFU 69 and UFU 37 were selected by both selection indexes. The UFU 72, UFU 90, UFU 88 and UFU 69 progenies are agronomically superior both in direct and indirect selection, as in Mulamba and Mock (1978) sum of “ranks” selections and genotype-ideotype.

Opportunities for genetic improvement of lamb survival

2010 ◽  
Vol 50 (12) ◽  
pp. 1017 ◽  
Author(s):  
F. D. Brien ◽  
M. L. Hebart ◽  
D. H. Smith ◽  
J. E. Hocking Edwards ◽  
J. C. Greeff ◽  
...  
Keyword(s):  
Rectal Temperature ◽  
Selection Index ◽  
Genetic Correlations ◽  
Direct Selection ◽  
Reproduction Rate ◽  
Crown Rump Length ◽  
Selection For ◽  
Lamb Survival ◽  
Net Reproduction ◽  
Birth Time

Data on lamb survival and associated traits involving records from 15 192 lambs, 6308 dams and 284 sires from the Sheep CRC’s Information Nucleus were studied. Lamb survival to 3 days of age and to weaning was 85 and 80%, respectively, and heritability (±s.e.) was 0.014 ± 0.010 and 0.010 ± 0.010, respectively. Of the 14 traits recorded at birth, time taken for the lamb to bleat, rectal temperature and crown–rump length had the highest genetic correlations with lamb survival to weaning (–0.43 ± 0.32, 0.56 ± 0.33 and –0.38 ± 0.36, respectively). Under selection for a multi-trait objective including net reproduction rate (but not lamb survival), survival was predicted to decline genetically by 0.25 lambs weaned per 100 lambs born.year, although this was reversed to a gain of 0.20 lambs weaned per 100 lambs born.year by including the trait in the breeding objective and using 50 half-sib and 50 progeny records per selection candidate. Accuracy of selection for lamb survival was improved to 0.735 with a selection index of lamb survival to weaning, lamb ease, birth coat score, time taken to bleat, rectal temperature and crown–rump length, with the addition of 50 half-sibs and 50 progeny records per candidate. Our results suggest that unless actively incorporated into breeding objectives, lamb survival may genetically decline; however, gains are possible with direct selection using half-sib and progeny records. The addition of indirect selection criteria for lamb survival can further improve accuracy, up to 93.4%, but requires further investigation.

Genetic parameters for lamb autopsy traits

2014 ◽  
Vol 54 (6) ◽  
pp. 736 ◽  
Author(s):  
D. J. Brown ◽  
R. M. Jones ◽  
G. N. Hinch
Keyword(s):  
Genetic Correlations ◽  
Selection Criterion ◽  
Research Centre ◽  
Cooperative Research ◽  
Crown Rump Length ◽  
Australian Sheep ◽  
Lamb Survival ◽  
Fleece Weight ◽  
Indicator Traits ◽  
Overall Mortality

Heritabilities and genetic correlations were estimated between individual and composite autopsy traits for lambs autopsied in the Australian Sheep Cooperative Research Centre information nucleus flocks between 2008 and 2011 (n = 3224). Correlations were also estimated between autopsy categories and the production parameters Yearling greasy-fleece weight and Yearling weight, and the potential survival indicator traits: Lamb ease, Thorax circumference and Crown–rump length. All autopsy trait heritability estimates were low (range 0.01–0.04). For all traits, a higher proportion of the variance was partitioned into the maternal permanent environment than the direct effects (range 0.01–0.12), suggesting that selection based on lamb autopsy results would impart little advantage over the lamb survival trait itself in improving lamb survival. Genetic correlations between Lamb ease and all autopsy traits were positive, indicating that birth trauma is related to all causes of lamb deaths and that Lamb ease may be a useful selection criterion in seedstock flocks to reduce overall mortality. There were also positive genetic correlations between Thorax circumference after adjusting for birthweight and two classes of dystocia, as well as a positive correlation between Thorax circumference and incidences of Starvation mismothering, implying that Thorax circumference may be a useful indirect field measurement to reduce death from these causes. Of concern were the antagonistic genetic correlations estimated between Yearling greasy-fleece weight and a composite trait of All Dystocia classes plus Starvation mismothering (0.27 ± 0.15), implying that selection for increased fleece weight could be having a detrimental effect on overall lamb survival.

scholarly journals Maternal melatonin implants improve twin Merino lamb survival

2020 ◽  
Vol 98 (11) ◽  
Author(s):  
Tom Flinn ◽  
Jessica R Gunn ◽  
Karen L Kind ◽  
Alyce M Swinbourne ◽  
Alice C Weaver ◽  
...  
Keyword(s):  
Rectal Temperature ◽  
Small Sample Size ◽  
Small Sample ◽  
Umbilical Blood ◽  
Practical Strategy ◽  
Australian Sheep ◽  
Lamb Survival ◽  
Placental Efficiency ◽  
Underlying Mechanisms ◽  
Mixed Age

Abstract High preweaning mortality rates cost the Australian sheep industry an estimated $540 million annually in lost production, with losses significantly greater in twin (≥30%) compared with singleton lambs (≥10%). Previous intensive studies demonstrated that supplementing pregnant ewes with melatonin reduces adverse effects of fetal growth restriction and perinatal hypoxia on the neonatal brain via increased umbilical blood flow, placental efficiency, and antioxidant actions. The current study examined the effects of supplementing ewes with melatonin on the survival of twin Merino lambs under extensive grazing conditions. Pregnant mixed age ewes were implanted with 1 (M1, n = 50) or 2 (M2, n = 53) slow-release melatonin implants (18 mg, Regulin) at gestational days 70 to 90. Control ewes received no supplementation (CTL, n = 54). Ewes were monitored twice daily throughout the lambing period. Lamb survival, weight, and rectal temperature were recorded on the day of birth. Lamb blood samples were taken the following day for serum immunoglobulin G (IgG) analysis. Lamb survival and weight were recorded again at marking (30.6 ± 0.6 d postpartum) and weaning (70.7 ± 0.6 d postpartum). Lamb survival was increased in both melatonin treatments to 3 d postpartum (M1 = 98.0%; M2 = 95.3%; CTL = 83.3%; each P < 0.01), and this improvement was maintained to weaning (M1 = 94.0%; M2 = 92.5%; CTL = 79.6%; each P < 0.01). Melatonin did not affect lamb birthweight, rectal temperature, or growth rate. However, the rates of parturition-related death (dystocia, stillbirth, and birth injury) were greater in CTL lambs than M1 (P = 0.009) and M2 (P = 0.035). This suggests that improved survival is primarily due to melatonin-induced neuroprotection, although further studies are required to clarify the underlying mechanisms. These data provide evidence that supplementing pregnant twin-bearing Merino ewes with melatonin may be a practical strategy to reduce neonatal mortality and improve weaning rates in extensively managed sheep flocks. Although the present data are promising, this study is limited by small sample size and requires further replication.

Maternal behaviour in Border Leicester, Glen Vale (Border Leicester derived) and Merino sheep

1990 ◽  
Vol 30 (1) ◽  
pp. 27 ◽  
Author(s):  
G Alexander ◽  
D Stevens ◽  
LR Bradley ◽  
SA Barwick
Keyword(s):  
Maternal Care ◽  
Maternal Behaviour ◽  
Selection Program ◽  
Merino Sheep ◽  
Lamb Survival

Ewe and lamb behaviour in traditional Border Leicesters, Glen Vale Border Leicesters of the NSW Agriculture and Fisheries, Glen Vale x Border Leicester crosses and medium-fine-wool Merinos, all running in paddocks of 3-4.5 ha, were compared in spring 1983 at Glen Innes, N.S.W. Twenty-eight aspects of behaviour with a known or reputed influence on lamb survival, especially of multiples, were examined in undisturbed and contrived situations. The Glen Vales and their crosses were superior to the Border Leicesters and Merinos in behaviour and lamb survival, particularly behaviour concerned with the ability of ewes to keep their lambs together. The study indicates that contrived twin-care tests could form the basis of a selection program to improve maternal care and survival of multiples.

scholarly journals Management Options and Factors Affecting Control of a Common Waterhemp (Amaranthus rudis) Biotype Resistant to Protoporphyrinogen Oxidase-Inhibiting Herbicides

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Dana B. Harder ◽  
Kelly A. Nelson ◽  
Reid J. Smeda
Keyword(s):  
Herbicide Resistance ◽  
Herbicide Application ◽  
Management Options ◽  
Protoporphyrinogen Oxidase ◽  
Factors Affecting ◽  
Common Waterhemp ◽  
Control Options ◽  
Amaranthus Rudis ◽  
Repeated Use ◽  
Herbicide Activity

Repeated use of protox-inhibiting herbicides has resulted in a common waterhemp (Amaranthus rudisSauer) biotype that survived lactofen applied up to 10 times the labeled rate. Field and greenhouse research evaluated control options for this biotype of common waterhemp. In the field, PRE applications of flumioxazin at 72 g ai ha−1, sulfentrazone at 240 g ai ha−1, and isoxaflutole at 70 g ai ha−1controlled common waterhemp >90% up to 6 weeks after treatment. POST applications of fomesafen at 330 g ai ha−1, lactofen at 220 g ai ha−1, and acifluorfen at 420 g ai ha−1resulted in <60% visual control of common waterhemp, but differences were detected among herbicides. In the greenhouse, glyphosate was the only herbicide that controlled protox resistant waterhemp. The majority of herbicide activity from POST flumioxazin, fomesafen, acifluorfen, and lactofen was from foliar placement, but control was less than 40% regardless of placement. Control of common waterhemp seeded at weekly intervals after herbicide treatment with flumioxazin, fomesafen, sulfentrazone, atrazine, and isoxaflutole exceeded 85% at 0 weeks after herbicide application (WAHA), while control with isoxaflutole was greater than 60% 6 WAHA. PRE and POST options for protox-resistant common waterhemp are available to manage herbicide resistance.

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