Genetic evaluation of adult ewe bodyweight and condition: relationship with lamb growth, reproduction, carcass and wool production

2017 ◽  
Vol 57 (1) ◽  
pp. 20 ◽  
Author(s):  
S. F. Walkom ◽  
D. J. Brown
Keyword(s):  
Genetic Variation ◽  
Body Condition ◽  
Current Practice ◽  
Genetic Relationships ◽  
Physiological Status ◽  
Production Cycle ◽  
Production Traits ◽  
Wool Production ◽  
The Impact ◽  
Lamb Growth

This paper reports on genetic variation in the growth, wool production, carcass, reproduction and the bodyweight and body condition of ewes managed in the Information Nucleus Flock (INF), with a focus on evaluating the potential value of including adult ewe bodyweight and condition change traits in the Australian national sheep genetic evaluations provided by Sheep Genetics. Data were collected over a 7-year period (2007–2013) at eight research sites across southern Australia. Approximately 13 700 ewes were weighed and condition scored with ewes on average mated four times during the study. Adult ewe weight and body condition were recorded across the production cycle and the impact of the physiological status and change in status of the ewe on the genetic relationships with lamb growth, carcass and wool production traits was evaluated. Strong genetic correlations between measurements across the production cycle for adult ewe bodyweight and condition, low heritability of change traits, along with weak genetic relationships between change traits and key production traits suggest that in production systems where nutritional challenges can be managed, change traits provide no improvement to the current practice of using static bodyweight and condition records. The genetic variation in weight and body condition and their genetic relationships with production traits were highly consistent across ages and the production cycle. As a result, the current practice by Sheep Genetics to treat adult weight as a single trait with repeat records is most likely sufficient. However, the inclusion of body condition within the Sheep Genetics evaluation has potential to assist in improving maternal performance, and the feed costs associated with maintaining ewe body condition.

Season and reproductive status rather than genetic factors influence change in ewe weight and fat over time. 4. Genetic relationships of ewe weight and fat score with fleece, reproduction and milk traits

2016 ◽  
Vol 56 (4) ◽  
pp. 708 ◽  
Author(s):  
S. F. Walkom ◽  
F. D. Brien ◽  
M. L. Hebart ◽  
N. M. Fogarty ◽  
S. Hatcher ◽  
...  
Keyword(s):  
Milk Production ◽  
Milk Fat ◽  
Genetic Relationships ◽  
Fibre Diameter ◽  
Reproductive Traits ◽  
Production Cycle ◽  
Production Traits ◽  
Milk Production Traits ◽  
Milk Traits ◽  
Fat Score

The profitability of a sheep enterprise is greatly influenced by the ability of the ewe to produce a lamb annually. This paper examines the between- and within-breed association between the liveweight and fat score of the adult ewe and key fleece, reproduction and milk production traits. The study analysed the performance of 2846 first-cross Merino and Corriedale ewes from the maternal central progeny test (MCPT) over their first three production cycles. Breed (9 sire breeds) and within-breed (91 sires) correlations were calculated from bivariate correlations of adult liveweight and fat score with fleece, reproduction and milk production traits. The mean liveweight and fatness of the breeds were low to moderately negatively correlated with greasy fleece weight (–0.55 and –0.25, respectively) and moderate to strongly positively correlated with fibre diameter (0.88 and 0.41, respectively). However, the within-breed correlations were generally low to negligible. The genetic relationships between ewe fat score and reproductive traits at the breed and within-breed level was generally low to negligible and, in some cases, negative under production conditions where the ewes were well managed and averaged a fat score of 3.5 pre-joining and became too fat across the production cycle. Strong breed correlations between ewe fat score and milk fat concentration (0.88) suggest that selection of fatter sire breeds will lead to increased fat in their progenies’ milk, which was associated with larger lambs. The potential advantages of selecting for more fat to improve the maternal performance of the ewe seem to be limited in enterprises where the production system can easily be adjusted to restrict the influence of temporary and long-term feed deficiencies, as was achieved within the MCPT research flocks.

A genetic analysis of wool and lamb production traits in Scottish Blackface Sheep

2002 ◽  
Vol 2002 ◽  
pp. 21-21
Author(s):  
A. Murphy ◽  
J. Conington
Keyword(s):  
Genetic Relationships ◽  
Carcass Traits ◽  
Direct Selection ◽  
Meat Production ◽  
Production Traits ◽  
Selection For ◽  
Wool Quality ◽  
Sheep Production ◽  
The Uk ◽  
The Impact

Scottish Blackface sheep have a multi-purpose role in the UK to produce breeding females and lambs for meat consumption. Over the last fifty years, wool has accounted for a very low proportion of economical return from hill sheep production in the UK. In recent years, the ratio of the value of lamb meat to wool clip has altered, with wool becoming relatively more important in particular for hill breeds. The consequence of direct selection for improved carcass traits in these breeds on wool quality is unknown. With other sheep breeds such as Merino, selection for improved wool traits has largely been undertaken with little regard to the impact on meat production. The objectives of this study are to quantify wool quality traits and examine genetic relationships between wool quality and carcass traits in Scottish Blackface sheep.

Genetic and phenotypic parameters for reproduction, production and bodyweight traits in Australian fine-wool Merino sheep

2018 ◽  
Vol 58 (2) ◽  
pp. 207 ◽  
Author(s):  
S. Dominik ◽  
A. A. Swan
Keyword(s):  
Genetic Relationships ◽  
Genetic Correlations ◽  
Fibre Diameter ◽  
Careful Consideration ◽  
Production Traits ◽  
Merino Sheep ◽  
Wool Production ◽  
Phenotypic Correlations ◽  
Reproduction Traits ◽  
Definition Of

The present study estimated phenotypic and genetic relationships between wool production, reproduction and bodyweight traits in Australian fine-wool Merino sheep. The data for the study originated from the CSIRO Fine Wool Project, Armidale, Australia. Data on wool characteristics, measured at ~10 and 22 months of age, bodyweight and several reproduction traits across consecutive lambing opportunities were analysed. The genetic correlations were moderately negative between fibre diameter measured as yearling and adult, and lamb survival (rg = –0.34 ± 0.15 and rg = –0.28 ± 0.14 respectively) and total number of lambs weaned (rg = –0.32 ± 0.21 and rg = –0.40 ± 0.21 respectively). The genetic correlations of yearling and adult greasy and clean fleece weights with number of lambs weaned and fecundity showed moderately to highly negative relationships and a moderately negative correlation with the number of fetuses at pregnancy scanning. Phenotypic correlations between reproduction and wool production traits were estimated to be zero, with the exception of bodyweight showing low to moderate positive phenotypic correlations with total number of lambs born and weaned. Genetic variances were generally low for the reproduction traits and resulted in low heritability estimates (from h2 = 0.03 ± 0.01 to h2 = 0.12 ± 0.13), with the exception of total number of lambs born (h2 = 0.25 ± 0.03). The study indicated that parameter estimation and trait definition of lifetime reproduction records require careful consideration and more work in this area is required.

Impact of liveweight, fat and muscle sire breeding values on ewe reproduction is minimal but variable across Australian grazing systems

2017 ◽  
Vol 57 (9) ◽  
pp. 1952 ◽  
Author(s):  
S. F. Walkom ◽  
D. J. Brown
Keyword(s):  
Body Condition ◽  
Reproductive Performance ◽  
Breeding Value ◽  
Production Cycle ◽  
Eye Muscle ◽  
Breeding Values ◽  
Reproduction Traits ◽  
Reproductive Rates ◽  
Supplementary Feed ◽  
The Impact

Australian sheep producers have the potential to improve reproductive rates through optimising ewe body condition across the production cycle. Managing ewe body condition can become costly when supplementary feeding is required due to poor pasture growth or rainfall and by using appropriate genetics, producers can theoretically reduce the flock’s dependency on supplementary feed and improve reproductive rates. Reproductive records from the Information Nucleus Flock and Sheep Genetics Merino and maternal breed datasets were analysed to examine the influence of sire breeding values for liveweight (post-weaning, yearling and adult assessments), fat and eye muscle depths (post-weaning and yearling assessments) and number of lambs weaned on reproductive performance (fertility, litter size and number of lambs born) across a variety of production environments. To determine the impact of environmental conditions on the relationship between weight, ultrasound body composition, and reproduction traits the daughters’ adjusted reproductive performances were regressed on the sire’s breeding value across flocks, within flocks and within flock × year. Irrespective of age at assessment, sire breeding values for liveweight, fat and eye muscle depths had very little association with the reproductive performance of their daughters, on average. The regressions of reproduction on weight, and fat and eye muscle depth traits varied across flocks from unfavourable to favourable estimates. The very small overall impact of weight, and fat and eye muscle depth traits, on average suggests that using sire breeding values for number of lambs weaned, which had a large impact on reproduction, will provide the most viable method to genetically improve reproductive performance within the production system in question.

The impact of rabbits on a grazing system in eastern New South Wales. 2. Sheep production

2002 ◽  
Vol 42 (7) ◽  
pp. 917 ◽  
Author(s):  
P. J. S. Fleming ◽  
J. D. Croft ◽  
H. I. Nicol
Keyword(s):  
Body Condition ◽  
Synergistic Effects ◽  
Fibre Diameter ◽  
The Body ◽  
Stocking Rate ◽  
Economic Implications ◽  
Wool Production ◽  
Sheep Production ◽  
Short Term Experiment ◽  
The Impact

Much research, time and money have been invested in the control of rabbits in Australia, yet the relationship between rabbit density and livestock production losses has not been quantified. We experimentally investigated the variations in sheep production parameters caused by 4 densities of rabbits, 0, 24, 48 and 72 rabbits/ha. Medium to strong wool merino wethers were run at a constant stocking rate in replicated plots with rabbits at 4� different densities. Sheep liveweight and body condition and wool production variables were measured over 3�years. Low to medium densities of rabbits were not found to reduce liveweights of wethers, whereas wethers run with the high density of rabbits were significantly lighter. The presence of rabbits reduced the body condition of sympatric sheep with the lowest body condition recorded at the high rabbit density. Mean greasy fleece weights, wool yields and clean-fleece weights were significantly different between densities of rabbits. Wethers run with the high rabbit density grew less wool than the wethers run with the other 3 densities of rabbits. The cumulative gross return per ha from wool production was highest for the medium rabbit density and lowest at high rabbit density. At the conclusion of this short-term experiment, the presence of some rabbits enhanced returns from wool production because of lower fibre diameter and comparable clean-fleece weights of fleeces grown at low and medium rabbit densities. These production characteristics might have been caused by synergistic effects on pasture growth or a sheep stocking rate that was too conservative for the prevailing seasonal conditions. At high rabbit density, competition for pasture between rabbits and sheep overrode possible synergistic and understocking effects. The economic implications of the presence of rabbits on merino sheep production are discussed.

Efficiency of feed utilisation by livestock — Implications and benefits of genetic improvement

2005 ◽  
Vol 85 (3) ◽  
pp. 281-290 ◽  
Author(s):  
P. F. Arthur ◽  
R. M. Herd
Keyword(s):  
Genetic Variation ◽  
Feed Intake ◽  
Environmental Sustainability ◽  
Feed Efficiency ◽  
Genetic Improvement ◽  
Genetic Relationships ◽  
Selection Strategy ◽  
Production Cycle ◽  
Two Stage ◽  
Feed Utilisation

Genetic improvement strategies in the past have concentrated on traits associated with outputs. Traits that directly affect input costs, such as those related to the efficiency of feed utilisation, have only recently started to receive some attention. This paper examines the current state of knowledge, benefits and challenges associated with genetic improvement of feed utilisation by livestock. Current information indicates the existence of genetic variation in feed efficiency and moderate heritability for most feed efficiency traits in all livestock species. However, there is a paucity of information on the genetic relationships among feed efficiency traits and other traits at different phases of the production cycle. The challenge is to develop breeding programs that exploit genetic variation in efficiency of feed utilisation to improve whole production system efficiency. The cost of recording feed intake (used to compute feed efficiency traits) is high, making it uneconomical, in some species, to measure feed intake in all potential seedstock animals. However, where a two-stage selection approach has been adopted, the inclusion of feed efficiency traits in genetic improvement schemes has yielded substantial additional benefits over and above the benefits from existing schemes that do not include feed efficiency traits. Under a two-stage selection strategy all potential seedstock animals are first evaluated for the production traits of interest, after which strategically selected individuals undergo feed efficiency testing. Where physiological or genetic markers for feed efficiency exist, such information is included in the first stage selection decision. There is theoretical evidence that selection for some feed efficiency traits, such as residual feed intake, will have additional benefit of reducing greenhouse emissions by livestock and improving environmental sustainability. The challenge is to generate the necessary empirical data to support this assertion. Key words: Feed efficiency, genetics, physiology, economic benefit, environmental sustainability

Season and reproductive status rather than genetics factors influence change in ewe weight and fat over time. 3. Analysis of Merino ewes

2014 ◽  
Vol 54 (6) ◽  
pp. 821 ◽  
Author(s):  
S. F. Walkom ◽  
F. D. Brien ◽  
M. L. Hebart ◽  
S. I. Mortimer ◽  
W. S. Pitchford
Keyword(s):  
Genetic Variation ◽  
Body Condition ◽  
Production Systems ◽  
Genetic Effect ◽  
Additive Genetic Effect ◽  
Production Cycle ◽  
Production Cycles ◽  
Australian Sheep ◽  
Sheep Production ◽  
Stocking Rates

The profitability of southern Australian sheep production systems depends on the optimisation of stocking rates by meeting the nutritional demands of the breeding ewe while effectively utilising grown pasture. The aim of the study was to evaluate the genetic variation in liveweight and body condition of Merino ewes across their breeding life within a wool-based enterprise. The results were consistent with findings in crossbred ewes and showed that the genetic component of weight and body condition remained constant across the production cycle and age. The overall additive genetic effect accounted for 92% of the genetic variation in weight of Merino ewes bred across five production cycles. A genetic correlation of 0.85 suggested that ewes that were superior at maintaining their condition when rearing a single lamb would maintain this superiority when rearing multiple lambs. To improve weight and condition of Merino ewes during the ‘tough’ times, when nutrient requirements are not met by the pasture, selection can be made at any time and this will result in increased genetic condition at all times.

The genetic relationship between interval to commencement of luteal activity postpartum and UK national fertility proofs for dairy cattle

2003 ◽  
Vol 2003 ◽  
pp. 54-54
Author(s):  
M.D. Royal ◽  
E. Wall ◽  
A.P.F. Flint
Keyword(s):  
Genetic Variation ◽  
Genetic Relationships ◽  
Economic Importance ◽  
Calving Interval ◽  
Production Traits ◽  
Similar Magnitude ◽  
Fertility Index ◽  
Condition Score ◽  
Fertility Traits ◽  
Coefficient Of Genetic Variation

The coefficient of genetic variation of fertility traits is of a similar magnitude to that present in production traits, however traditional measurements of fertility have low heritability (h2 < 0.05), and recording is often poor, hindering the identification of genetically superior animals. The effect of sire on daughter fertility has been examined as part of a DEFRA LINK project to produce an UK fertility index. The project is investigating the use of six currently recorded traits to calculate sire genetic merit for fertility: calving interval (CI), interval to first service (DIMFIR), nonreturn rate 56 (NR56), number of services per conception (CINSOBS), milk yield and condition score (Wall et al., 2002). An alternative way to measure fertility is to use endocrine measurements such as interval to commencement of luteal activity postpartum (CLA). This parameter is less influenced by management decisions and has a moderate heritability (0.16; Royal et al., 2002a.) and is measurable early in lactation. Although information on the genetic relationships between CLA and other traits of economic importance have been reported previously (Royal et al., 2002a.; Royal et al, 2002b.) further information would be useful in order to assess the usefulness of incorporating CLA into a future UK breeding programme. The objective of these analyses was therefore to obtain information on the genetic correlation (rA) between lnCLA and the emerging UK national fertility proofs.

scholarly journals Evaluation of growth, wool production and reproduction traits of Muzaffarnagari sheeps

2019 ◽  
Vol 34 (01) ◽  
Author(s):  
Gopal Dass ◽  
M. S. Dige ◽  
P. K. Rout
Keyword(s):  
Least Squares ◽  
Growth Traits ◽  
The Body ◽  
Growth Stages ◽  
Production Traits ◽  
Replacement Rate ◽  
Wool Production ◽  
Body Weights ◽  
Reproduction Traits ◽  
The Impact

Muzaffarnagari, the heaviest breed among 43 Indian sheep breeds, is originally distributed in and around Muzaffarnagar district of western Uttar Pradesh and also in some parts of Rajasthan, Haryana and Delhi states. Muzaffarnagari is a mutton type breed because the wool production is low and wool quality is very course, not suitable for carpet manufacture. To study the impact of various factors on production and reproduction traits, the data on 1080 Muzaffarnagari lambs born under Network Project on Sheep Improvement during years 2011-15 at ICAR-Central Institute for Research on Goats, Makhdoom, Farah, Mathura (UP) were recorded for growth traits i.e. body weights at birth, 3, 6, 9 and 12 month age, wool production traits viz. greasy fleece yields of lambs in first and second six monthly clips and reproduction traits viz. tupping, lambing on available basis, lambing on bred basis, twinning and replacement rate of ewes. The overall least squares means for body weights at birth, 3, 6, 9 and 12 months age were 3.55±0.02, 16.02±0.12, 24.46±0.18, 29.18±0.19 and 33.52±0.19 kg, respectively and average daily gains (ADGs) during 0–3, 3-6, 6-12 and 3-12 months age groups were 138.56±1.27, 92.18±1.22, 63.87±0.64 and 50.89±0.86g, respectively. The overall least squares means for lambs 1st and 2nd six monthly clips 533.23±5.47 and 544.43±5.94g, respectively. The effect of sex, year of lambing, parity and type of birth of lambs had highly significant (P 0.01) influence on all growth and wool production traits except non significant effect of year on birth weight, parity on 3-6, 6-12 and 3-12 months ADG, type of birth on 3-6 month ADG, sex on lambs first clip and type of bith on lambs second clip. On comparison, male lambs were found superior than female lambs for all body weights and fleece yields. During year 2013, all the body weights and greasy fleece yields were recorded to be highest. Parity of ewes did not show any definite trend for growth traits while type of birth indicated that lambs born as single gained heavier weights at all growth stages and produced heavier clips than multiple born lambs. Tupping, lambing on available basis, lambing on bred basis, twinning and replacement rate ranges from 86.9-100.0, 74.3-91.0, 83.2-92.5, 10.9-20.3 and 24.5-33.2%, respectively. This study revealed that 0-3 month lambs growth is very crucial which needs proper management, feeding and health care and selection of breeding rams based on their six month body weight was effective for genetic improvement of Muzaffarnagari sheep for growth and reproduction traits.

Translating Principles of Speech Science to Clinical Practice: Current and Future Trends in Craniofacial Disorders

2008 ◽  
Vol 18 (1) ◽  
pp. 31-40 ◽  
Author(s):  
David J. Zajac
Keyword(s):  
Clinical Practice ◽  
Speech Intelligibility ◽  
Current Practice ◽  
Computer Assisted ◽  
Behavioral Management ◽  
Single Word ◽  
Future Directions ◽  
Speech Science ◽  
The Impact ◽  
Opinion Article

Abstract The purpose of this opinion article is to review the impact of the principles and technology of speech science on clinical practice in the area of craniofacial disorders. Current practice relative to (a) speech aerodynamic assessment, (b) computer-assisted single-word speech intelligibility testing, and (c) behavioral management of hypernasal resonance are reviewed. Future directions and/or refinement of each area are also identified. It is suggested that both challenging and rewarding times are in store for clinical researchers in craniofacial disorders.

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