Lamb survival in relation to lambing and neonatal behaviour in medium wool Merino lines divergently selected for multiple rearing ability

1998 ◽  
Vol 38 (8) ◽  
pp. 801 ◽  
Author(s):  
S. W. P. Cloete ◽  
A. J. Scholtz
Keyword(s):  
Least Squares ◽  
Birth Rate ◽  
Time Lapse ◽  
Multiple Birth ◽  
Base Population ◽  
Merino Sheep ◽  
Litter Weight ◽  
Least Squares Adjustment ◽  
Selection For ◽  
Lamb Survival

Summary. Two lines of Merino sheep were divergently selected from the same base population since 1986 on maternal ranking values for multiple rearing ability. In the high (H) line, ewe and ram progeny were preferably descended from ewes that reared >1 lamb per joining. In the low (L) line, replacements were the progeny of ewes that reared <1 lamb per joining. Data on lamb mortality, lambing and neonatal behaviour as well as lamb production were obtained from these lines over 5 years (1993–97). Lamb survival was improved (P<0.01) in the H line, mainly as a result of the improved survival of multiples. It was evident that the survival of lambs was not compromised by selection for ewe multiple rearing ability, despite the fact that higher mortality levels are expected with an increase in multiple birth rate. No line difference was found for the time lapse from birth to first standing for >10 s, but H line lambs were quicker (P<0.01) to progress from standing to suckling than L line contemporaries (28 v. 38 min respectively). This line difference remained after adjustment for better co-operation of H line ewes with the first suckling attempts of their progeny. Ewes in the H line tended (P = 0.18) to remain longer on or near their birth sites than L line contemporaries (403 v. 362 min respectively). They also tended to be less (P = 0.07) likely to desert their lambs than L line ewes (12/424 = 0.028 v. 14/230 = 0.061 respectively). After least-squares adjustment for their heavier (P<0.01) litter weight, H line ewes experienced shorter (P<0.05) births than their L line contemporaries (46 v. 57 min respectively). Fewer (P<0.05) H line lambs died during or shortly after parturition (respective proportions of 22/890 = 0.025 and 25/441 = 0.057), while maiden H line ewes were less (P<0.05) likely to be assisted at lambing than L line contemporaries (4/107 = 0.037 v. 8/61 = 0.131 respectively). With regard to overall lamb production, it was found that the number of lambs weaned per ewe present at lambing in the H line was improved (P<0.05) in all years relative to that observed in the L line, the differences ranging from 25% in 1993 to 47% in 1997. Lamb weaning weight was correspondingly improved (P<0.05) in H line lambs, the differences ranging from 8% in 1994 to 22% in 1996. Fairly high levels of production could thus be attained with predominantly pasture-fed ewes selected for multiple rearing ability.

scholarly journals Effects of ewe live weight and age on reproductive performance, lamb growth, and survival in Central Anatolian Merino sheep

2015 ◽  
Vol 58 (2) ◽  
pp. 451-459 ◽  
Author(s):  
A. H. Aktaş ◽  
Ş. Dursun ◽  
Ş. Doğan ◽  
Z. Kiyma ◽  
U. Demirci ◽  
...  
Keyword(s):  
Growth Rate ◽  
Reproductive Performance ◽  
Birth Rate ◽  
Live Weight ◽  
Fertility Rate ◽  
Multiple Birth ◽  
Growth And Survival ◽  
Merino Sheep ◽  
Lamb Growth ◽  
Selection Of

<p><strong>Abstract.</strong> The aim of this study was to evaluate the effects of premating ewe weight and age on ewe reproductive performance, lamb growth and survival in Central Anatolian Merino (CAM) sheep. <br><br> The trial included 4935 ewes and 5548 lambs from 23 breeder flocks in Eskişehir Province. The live weights (LWs) and ages of the ewes were recorded 1 week before the mating season. The number of lambs born, fertility rate, multiple birth rate (MBR), and lamb survival rate (SR) at days 75 and 120 were determined. The effects of the LW and age of the ewe were found to be important for the reproductive performance of ewes and for the lamb's growth rate (<i>P</i> < 0.05–0.001). Ewe MBRs and the birth weight (BW) and LW of the lambs at days 75 and 120 increased proportionally with the increase in LW in ewes prior to mating. The fertility rate and MBR were lower (<i>P</i> < 0.05–0.001) in 1.5-year-old ewes than in older ewes. However, lambs' SR at days 75 and 120 were not affected by the premating LW and age of the ewe. In summary, a better reproductive performance and lamb growth rate in CAM flocks may be achieved by the selection of breeding ewes from ewes weighing more than 60 kg.</p>

scholarly journals Establishment of Geodetic Network in Nigeria

2019 ◽  
pp. 197-221
Author(s):  
Ikharo I. Blessing ◽  
Matthew N. Ono ◽  
Olaniyi Saheed S.
Keyword(s):  
Best Practices ◽  
Data Acquisition ◽  
Least Squares ◽  
Historical Development ◽  
Geodetic Network ◽  
Software Selection ◽  
Least Squares Adjustment ◽  
Selection For ◽  
Acquisition Method

This paper focus on the establishment of Geodetic Network in Nigeria which serve as the framework and basis for every spatially referenced system in the country. It explains the historical development of Nigeria geodetic network, its mode of establishment, data acquisition method, computation and adjustment principles. The use recent positioning satellites (GNSS) and its several methods were discussed with the Least Squares Adjustment techniques. Literatures on best practices were reviewed to identify gaps that need to be covered so as to have an accurate and efficient geodetic network in the Nigeria. The research is basically on principles and methodology on the establishment of Geodetic Network in Nigeria and silent on hardware and software selection for its establishment.

Selection for economic characters in Australian Merino sheep.

1954 ◽  
Vol 5 (2) ◽  
pp. 305 ◽  
Author(s):  
FHW Morley
Keyword(s):  
Body Weight ◽  
Least Squares ◽  
Expected Value ◽  
Merino Sheep ◽  
Random Deviation ◽  
Selection For ◽  
Australian Merino ◽  
Coefficient Of Inbreeding ◽  
Staple Length

The effect of inbreeding and parent-offspring regressions for some economic characters of Merino sheep were estimated by a least-squares procedure. The model was: Yi = a + b1X1i + b2X2i + ei ,where Yi and X1i represent the phenotype and coefficient of inbreeding of the ith sheep, X2i the phenotype of the dam of that sheep, and ei the random deviation of Y, from its expected value. Increased coefficients of inbreeding were accompanied by highly significant decreases in greasy and clean fleece weights, body weight, and fold score. No significant association was observed between inbreeding and yield, staple length, crimps per inch, or birthcoat grading. Increased inbreeding was associated with decreased survival. Significant correlations between X1 and X2 were demonstrated for fleece weights, staple length, body weight, and crimps per inch. The implications of these correlations are discussed. The parent-offspring regressions were all highly significant. Estimates of heritability were high for all characters studied. The importance of these findings on the effectiveness of selection for flock improvement is considered.

Influence of divergent selection for reproduction on the occurrence of breech strike in mature Merino ewes

2010 ◽  
Vol 50 (3) ◽  
pp. 203 ◽  
Author(s):  
A. J. Scholtz ◽  
S. W. P. Cloete ◽  
J. B. van Wyk ◽  
A. C. M. Kruger ◽  
T. C. de K. van der Linde
Keyword(s):  
Preliminary Analysis ◽  
Divergent Selection ◽  
Base Population ◽  
Breeding Values ◽  
Merino Sheep ◽  
High Line ◽  
Animal Number ◽  
Selection For

Divergent selection resulted in Merino lines that differ markedly for reproduction. These lines were selected from the same base population from 1986 to 2009. Selection was initially based on maternal ranking values for reproduction in both ewe and ram progeny. The maternal ranking scores were augmented by breeding values from a single-trait repeatability model since 2003. The site and severity of flystrike were recorded for mature breeding ewes in the flock from 2007 to 2009. The following details were captured: animal number, site of the strike (body or breech) and the severity of the strike (1 = mild to 5 = severe). Breech strikes amounted to 92.1% of all strikes and this trend was consistent across years. High-line ewes were less likely (P < 0.05) than low-line ewes to be suffering from breech strike. Ewes that suffered from breech strike during a reference year were more likely to be struck again during subsequent years, when compared with contemporaries not affected by breech strike in the reference year. When breech strike and body strike were assessed in a joint preliminary analysis, it seemed that body strike was generally more severe when diagnosed than breech strike. It was concluded that Merino sheep selected for improved reproduction for >20 years were less likely to be affected by breech strike than contemporaries selected for low reproduction.

The ability of Merino ewes and lambs to reunite after separation, as affected by divergent selection for ewe multiple rearing capacity

2005 ◽  
Vol 45 (9) ◽  
pp. 1131 ◽  
Author(s):  
S. W. P. Cloete ◽  
A. J. Scholtz ◽  
J. J. E. Cloete ◽  
J. B. van Wyk
Keyword(s):  
Divergent Selection ◽  
Base Population ◽  
High Line ◽  
Behavioural Patterns ◽  
Selection For ◽  
Lamb Survival ◽  
Clear Line

Lambs and ewes from 2 Merino lines that had been selected divergently from the same base population for (High line) or against (Low line) multiple rearing success, were assessed for their ability to reunite after temporary separation. Selection in the lines began in 1986, and data for this study were obtained from 1998 to 2002. Postnatal lamb mortality for lambs born during 1998–2002 were generally lower (P<0.05) in high line lambs than in low line contemporaries. When tethered 20 m away from their dams at 1 day of age, lambs in the High line tended (P<0.10) to be more likely to bleat and tug on the tethering rope than Low line contemporaries. Dams of lambs in the high line were quicker (P<0.05) to reunite with a tethered lamb than low line ewes. They were also quicker (P<0.05) to establish contact with the full litter after separation of multiples. In an experiment conducted in pens at an age of 3 days, no line difference was found for the ability of ewes to reunite with their lambs or litters when confronted by a choice of 3. When lambs were assessed in the same way, 89% was able to reunite with their dams within 5 min, with no evident line difference (P>0.05). When released from the pens, the dams of 95% of single lambs returned for their lambs, the proportion tending (P<0.10) to be higher in the High line than in the Low line. The dams of multiple lambs returned for 73% of the lambs tested, with no clear line difference. Lambs in the High line were more (P<0.01) likely to follow next to the front legs or midside of their dams than Low line lambs. Line differences in some behavioural patterns in favour of the High line are considered to be conducive to lamb survival when compared with Low line performance.

ESTIMASI NILAI HERITABILITAS BOBOT IKAN MAS VARIETAS PUNTEN DALAM PROGRAM SELEKSI INDIVIDU

2016 ◽  
Vol 11 (3) ◽  
pp. 217
Author(s):  
Estu Nugroho ◽  
Budi Setyono ◽  
Mochammad Su’eb ◽  
Tri Heru Prihadi
Keyword(s):  
Body Weight ◽  
Selection Response ◽  
Base Population ◽  
Breeding Programs ◽  
Male And Female ◽  
Body Weight Trait ◽  
Population Selection ◽  
Selection For ◽  
Weight Trait ◽  
Selection Of

Program pemuliaan ikan mas varietas Punten dilakukan dengan seleksi individu terhadap karakter bobot ikan. Pembentukan populasi dasar untuk kegiatan seleksi dilakukan dengan memijahkan secara massal induk ikan mas yang terdiri atas 20 induk betina dan 21 induk jantan yang dikoleksi dari daerah Punten, Kepanjen (delapan betina dan enam jantan), Kediri (tujuh betina dan 12 jantan), Sragen (27 betina dan 10 jantan), dan Blitar (15 betina dan 11 jantan). Larva umur 10 hari dipelihara selama empat bulan. Selanjutnya dilakukan penjarangan sebesar 50% dan benih dipelihara selama 14 bulan untuk dilakukan seleksi dengan panduan hasil sampling 250 ekor individu setiap populasi. Seleksi terhadap calon induk dilakukan saat umur 18 bulan pada populasi jantan dan betina secara terpisah dengan memilih berdasarkan 10% bobot ikan yang terbaik. Calon induk yang terseleksi kemudian dipelihara hingga matang gonad, kemudian dipilih sebanyak 150 pasang dan dipijahkan secara massal. Didapatkan respons positif dari hasil seleksi berdasarkan bobot ikan, yaitu 49,89 g atau 3,66% (populasi ikan jantan) dan 168,47 g atau 11,43% (populasi ikan betina). Nilai heritabilitas untuk bobot ikan adalah 0,238 (jantan) dan 0,505 (betina).Punten carp breeding programs were carried out by individual selection for body weight trait. The base population for selection activities were conducted by mass breeding of parent consisted of 20 female and 21 male collected from area Punten, eight female and six male (Kepanjen), seven female and 12 male (Kediri), 27 female and 10 male (Sragen), 15 female and 11 male (Blitar). Larvae 10 days old reared for four moths. Then after spacing out 50% of total harvest, the offspring reared for 14 months for selection activity based on the sampling of 250 individual each population. Selection of broodstock candidates performed since 18 months age on male and female populations separately by selecting based on 10% of fish with best body weight. Candidates selected broodstocks were then maintained until mature. In oder to produce the next generation 150 pairs were sets and held for mass spawning. The results revealed that selection response were positive, 49.89 g (3.66%) for male and 168.47 (11.43%) for female. Heritability for body weight is 0.238 (male) and 0.505 (female).

scholarly journals Using Least-Squares Residuals to Assess the Stochasticity of Measurements—Example: Terrestrial Laser Scanner and Surface Modeling

2021 ◽  
Vol 5 (1) ◽  
pp. 59
Author(s):  
Gaël Kermarrec ◽  
Niklas Schild ◽  
Jan Hartmann
Keyword(s):  
Least Squares ◽  
Laser Scanner ◽  
Real Data ◽  
Point Clouds ◽  
Statistical Testing ◽  
Normal Vector ◽  
Engineering Structures ◽  
3D Point Clouds ◽  
Least Squares Adjustment ◽  
Correlation Parameters

Terrestrial laser scanners (TLS) capture a large number of 3D points rapidly, with high precision and spatial resolution. These scanners are used for applications as diverse as modeling architectural or engineering structures, but also high-resolution mapping of terrain. The noise of the observations cannot be assumed to be strictly corresponding to white noise: besides being heteroscedastic, correlations between observations are likely to appear due to the high scanning rate. Unfortunately, if the variance can sometimes be modeled based on physical or empirical considerations, the latter are more often neglected. Trustworthy knowledge is, however, mandatory to avoid the overestimation of the precision of the point cloud and, potentially, the non-detection of deformation between scans recorded at different epochs using statistical testing strategies. The TLS point clouds can be approximated with parametric surfaces, such as planes, using the Gauss–Helmert model, or the newly introduced T-splines surfaces. In both cases, the goal is to minimize the squared distance between the observations and the approximated surfaces in order to estimate parameters, such as normal vector or control points. In this contribution, we will show how the residuals of the surface approximation can be used to derive the correlation structure of the noise of the observations. We will estimate the correlation parameters using the Whittle maximum likelihood and use comparable simulations and real data to validate our methodology. Using the least-squares adjustment as a “filter of the geometry” paves the way for the determination of a correlation model for many sensors recording 3D point clouds.

scholarly journals Polygenic and single gene responses to selection for resistance to diazinon in Lucilia cuprina.

Genetics ◽  
1992 ◽  
Vol 130 (3) ◽  
pp. 613-620 ◽  
Author(s):  
J A McKenzie ◽  
A G Parker ◽  
J L Yen
Keyword(s):  
Resistant Strain ◽  
Single Gene ◽  
Natural Populations ◽  
Susceptible Strain ◽  
Selection Line ◽  
Base Population ◽  
Gene Response ◽  
Biochemical Profiles ◽  
Resistant Strains ◽  
Selection For

Abstract Following mutagenesis with ethyl methanesulfonate, selection in a susceptible strain with a concentration of the insecticide diazinon (0.0004%, w/v) above that required to kill 100% of the susceptible strain, the LC100 of that strain, resulted in a single gene response. The resultant four mutant resistant strains have equivalent physiological, genetical and biochemical profiles to a diazinon-resistant strain derived from a natural population and homozygous for the Rop-1 allele. Modification of the microsomal esterase E3 is responsible for resistance in each case. The Rop-1 locus maps approximately 4.4 map units proximal to bu on chromosome IV. Selection within the susceptible distribution, at a concentration of diazinon [0.0001% (w/v)] less than the LC100, resulted in a similar phenotypic response irrespective of whether the base population had been mutagenized. The responses were polygenically based, unique to each selection line and independent of Rop-1. The relevance of the results to selection for insecticide resistance in laboratory and natural populations is discussed.

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