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.

Genetic parameters for terminal sires estimated using data of progeny from Border Leicester × Merino ewes

1995 ◽  
Vol 46 (4) ◽  
pp. 703
Author(s):  
PA Kenney ◽  
ME Goddard ◽  
LP Thatcher
Keyword(s):  
Genetic Parameters ◽  
Selection Index ◽  
Genetic Correlations ◽  
Subcutaneous Fat ◽  
Muscle Area ◽  
Eye Muscle ◽  
Bone Length ◽  
Selection For ◽  
Using Data ◽  
Omental Fat

Three and a half thousand lambs from Border Leicester x Merino ewes mated to 133 sires from five Poll Dorset, one White Suffolk, one Siromt, two Meridale and four Merino studs were slaughtered, their carcasses halved and one side divided into six primals. Subcutaneous fat was dissected from all six primals, and bone from only the three rear primals. There were four slaughter groups: average slaughter weights of 30 and 35 kg for ewes and 35 and 45 kg for cryptorchids. Heritabilities and phenotypic and genetic correlations for all traits measured (>50) are published in an appendix. Where comparisons were available, estimates were similar to those for purebred animals. Genetic parameters for various assessments of fat were similar except for channel and omental fat. The GR fat depth was the best predictor for total subcutaneous fat, cannon bone length for total bone, and eye muscle area for total soft tissue. Carcass weight and GR appear to be the most important measurements for use in selection for breeding of sires for the prime lamb industry. Slaughter weight and fat depth at the C site could be used as suitable alternatives on live animals. Production of lean meat is not likely to be increased greatly by including measurements other than liveweight and GR in a selection index. Of the other measurements bone length and eye muscle measurements showed most promise.

Can we breed Merino sheep with softer, whiter, more photostable wool?

2010 ◽  
Vol 50 (12) ◽  
pp. 1089 ◽  
Author(s):  
S. Hatcher ◽  
P. I. Hynd ◽  
K. J. Thornberry ◽  
S. Gabb
Keyword(s):  
Genetic Parameters ◽  
Selection Index ◽  
Genetic Correlations ◽  
Genetic Selection ◽  
Phenotypic Selection ◽  
Quality Traits ◽  
Current Generation ◽  
Merino Sheep ◽  
Initial Cohort ◽  
Selection For

Genetic parameters (heritability, phenotypic and genetic correlations) were estimated for a range of visual and measured wool traits recorded from the 2008 shearing of the initial cohort of Merino progeny born into the Sheep CRC’s Information Nucleus Flock. The aim of this initial analysis was to determine the feasibility of selectively breeding Merino sheep for softer, whiter, more photostable wool and to quantify the likely impact on other wool production and quality traits. The estimates of heritability were high for handle and clean colour (0.86 and 0.70, respectively) and moderate for photostability (0.18), with some evidence of maternal effects for both handle and photostability. The phenotypic correlations between handle and clean colour and between handle and photostability were close to zero, indicating that achieving the ‘triple’ objective of softer, whiter, more photostable wool in the current generation through phenotypic selection alone would be difficult. There was evidence of an antagonistic relationship between handle and photostability (–0.36), such that genetic selection for softer wool will produce less photostable wool that will yellow on exposure to UV irradiation. However genetic selection for whiter wool is complementary to photostability and will result in whiter wool that is less likely to yellow. Genetic selection to improve handle, colour and photostability can be achieved with few detrimental effects on other visual and measured wool traits, particularly if they are included in an appropriate selection index.

Selection for cow lifetime pregnancy rate using bull and heifer growth and reproductive traits in composite cattle

2000 ◽  
Vol 80 (3) ◽  
pp. 507-510 ◽  
Author(s):  
P. B. Mwansa ◽  
R. A. Kemp ◽  
D. H. Crews Jr ◽  
J. P. Kastelic ◽  
D. R. C. Bailey ◽  
...  
Keyword(s):  
Birth Weight ◽  
Key Words ◽  
Pregnancy Rate ◽  
Growth Traits ◽  
Genetic Correlations ◽  
Reproductive Traits ◽  
Genetic Change ◽  
Direct Selection ◽  
Scrotal Circumference ◽  
Selection For

Genetic correlations of lifetime pregnancy rate with bull and heifer growth and reproductive traits in a beef composite population were estimated. Yearling scrotal circumference had an unfavorable genetic correlation (rg = −0.25) while yearling tonometer score was favorably related (rg = 0.22) to lifetime pregnancy rate. Heifer pregnancy rate, birth weight, weaning weight, yearling weight and age at puberty in heifers had significant genetic correlations (rg = 0.97, 0.58, 0.57, 0.33 and −0.21, respectively) with lifetime pregnancy rate. Lifetime pregnancy rate may be successfully predicted by easy-to-measure heifer growth traits. Using indices including scrotal and heifer growth traits, annual genetic change in lifetime pregnancy rate may be increased 3.1 times compared with direct selection. Key words: Scrotal circumference, tonometer, pregnancy, reproduction, puberty

scholarly journals Selection for placental efficiency in swine

2004 ◽  
Author(s):  
◽  
Henry Mesa Echeverri
Keyword(s):  
Selection Index ◽  
Genetic Selection ◽  
Reproductive Traits ◽  
Placental Weight ◽  
High Survival ◽  
Genetic Trend ◽  
Crown Rump Length ◽  
Placental Function ◽  
Selection For ◽  
Placental Efficiency

With the overall goal of increasing profitability by increasing litter size, two lines of pigs were divergently selected for four generations on an index of reproductive traits (n = 193 litters). The selection index (SI) included total born (TB), birth weight (BW) and placental weight (PW) and was designed to increase (H line) or decrease (L line) BW:PW (placental efficiency; PE). (Co)variance components were estimated for direct and maternal additive effects by using an animal model with MTDFREML procedures. Breeding values were estimated (EBV) for individual BW (n = 2,111), PW (n = 2,006), PE (n = 1,677), and SI (n = 1,677). Direct heritability estimates were 0.03, 0.25, 0.18, 0.11 and 0.08 for BW, PW, PE, SI, and TB, respectively. Genetic divergence was 20.7 g, 0.24, 0.11, and 0.07 pigs per generation for PW, PE, SI, and TB, respectively (P less 0.01), but not significant for BW. Thus, PW and PE are susceptible to change by genetic selection; however, the genetic trend for TB unexpectedly was positive in the L line The phase two objective was to evaluate correlated responses in conceptus development and placental function in these lines. Sows were remated within line to produce 50 generation-four litters for evaluation at d 30, 50, 70, 90, and 110 of gestation.Fetal weight did not differ between lines from d 30 to 90, but was lower in H than L at d 110 (P = 0.02). Crown-rump length did not differ between lines from d 30 to 70, but was longer in H than L at d 90 (P = 0.09) and shorter at d 110 (P = 0.04). PW did not differ between lines from d 30 to 90, but was lower in H than L at d 110 (P less than 0.01). PE did not differ between lines at any gestational age. These results suggest that in western breeds, a reduction in placental weight through selection is not accompanied by physiological changes to improve placental function and may result in decreased prenatal survival. The farrowing data were used in phase three to determine factors influencing survival at farrowing (FS) and weaning (WS). These traits were considered traits of the piglet and scored 1 for piglets alive at those time points or 0 if dead. Estimates of direct heritability were 0.16 and 0.18 and of maternal heritability were 0.14 and 0.10 for FS and WS, respectively. Logistic regressions indicated BW, PW, their interaction, and TB can be used as predictors FS and WS. In the presence of BW, PE does not improve the prediction of survival. These results suggest possible selection for increased FS and WS. A piglet's BW, PW, its litter average BW, and the individual's deviation from that average can be used to produce piglets with high survival probability.

scholarly journals 12 Genetic and phenotypic parameters for Aleutian disease tests and their correlations with growth and pelt quality traits in American mink

2020 ◽  
Vol 98 (Supplement_4) ◽  
pp. 17-18
Author(s):  
Guoyu Hu ◽  
Duy Ngoc Do ◽  
Janine Gray ◽  
Karim Karimi ◽  
Younes Miar
Keyword(s):  
Fixed Effects ◽  
American Mink ◽  
Genetic Correlations ◽  
Direct Selection ◽  
Enzyme Linked Immunosorbent Assay ◽  
Quality Traits ◽  
Genetically Improved ◽  
Significant Heritability ◽  
Improvement Programs ◽  
Selection For

Abstract Aleutian disease brings tremendous financial losses to the mink industry. The ineffective immunoprophylaxis, medication, and culling strategies have urged the mink industry to select mink with low quantitative enzyme-linked immunosorbent assay (qELISA) score or negative counterimmunoelectrophoresis (CIEP) test result. However, little is known about the heritabilities of qELISA and CEIP as well as their relationships with growth and pelt quality traits. The traits, including qELISA, CIEP, body length at harvest (HLEN), the size of dried pelt (SIZE), the overall quality of dried pelt (QUA), and the nap length of dried pelt (NAP), were measured on 1,683 American mink from the Canadian Center for Fur Animal Research (Nova Scotia, Canada) and Millbank Fur Farm (Ontario, Canada). Significance (P < 0.05) of fixed effects (sex, farm, age, and color) and random effects (common litter, permanent environment, and dam) were determined by univariate analyses, while genetic and phenotypic parameters for all traits were estimated under bivariate analyses using ASREML 4.1. Estimated heritabilities (±SE) were 0.41±0.07 for qELISA, 0.06±0.06 for CIEP, 0.39±0.06 for HLEN, 0.46±0.07 for SIZE, 0.25±0.06 for QUA, and 0.46±0.08 for NAP. The qELISA showed non-significant (P > 0.05) genetic correlations with HLEN (0.05±0.13) and dried pelt traits (0.02±0.18 with SIZE, -0.21±0.20 with QUA, and -0.13±0.16 with NAP). The CIEP only showed a significant (P < 0.05) negative genetic correlation with SIZE (-0.85±0.33). The moderate-to-high heritabilities of qELISA, HLEN, SIZE, QUA, and NAP indicated that these traits can be genetically improved through a genetic/genomic selection. The low and non-significant heritability of CIEP indicated the ineffectiveness of direct selection for this trait. The estimated genetic parameters for qELISA suggested that selection for lower qELISA scores may not interfere with the selection of pelt size and quality in the genetic improvement programs of American mink.

Performance of Hereford and crossbred Hereford cattle in the subtropics of New South Wales: genetic analyses of pre-weaning performance of first-cross calves

1980 ◽  
Vol 31 (2) ◽  
pp. 417 ◽  
Author(s):  
R Barlow ◽  
GH O'Neill
Keyword(s):  
Birth Weight ◽  
Genetic Correlations ◽  
Environmental Variation ◽  
Direct Selection ◽  
Gestation Length ◽  
Strongly Correlated ◽  
Weaning Weight ◽  
Selection For ◽  
Sire Breed ◽  
Size At Birth

First-cross calves of Simmental (S), Friesian (F), and Brahman (B) sires were compared with straight-bred calves of Hereford (H) sires over 5 years at Grafton, N.S.W. There was a total of 775 calves sired by 205 bulls with complete records of performance from conception to weaning. Analyses were conducted to determine sire breed and sire breed x environment effects, and to provide paternal half-sib estimates of heritabilities and genetic and phenotypic correlations. Various models were used to ascertain the sensitivity of genetic parameters to the removal of different sources of variation. Among females, S x H were heaviest at birth, while among males, B x H were heaviest. The regression coefficient of birth weight on gestation length was significantly greater for B x H calves than for other crosses. All crosses grew significantly faster to weaning and were significantly heavier at weaning than H x H calves. However, there were a number of significant interactions between sire breed and environmental variables for measures of pre-weaning growth. S x H and F x H calves appeared most sensitive to environmental variation, while B x H appeared least sensitive. The significance of this is discussed. Estimates of heritability for most traits were high. Values derived by using simple models were: gestation length, 0.68; birth weight, 0.56; average daily gain (ADG) to weaning, 0.47; weaning weight, 0.54; eyelid pigmentation, 0.50. Heritabilities of birth weight and ADG during the early pre-weaning period appeared most sensitive to the amount of environmental variation removed in the model. Gestation length was positively correlated with size at birth but negatively correlated with growth to weaning. There were large positive genetic correlations among various measures of size at birth, and among various measures of growth to weaning. When compared with ADG to weaning, weaning weight was more strongly correlated with birth weight, but less strongly correlated with gestation length. The results also indicated that selection for gain over a fixed time period, immediately prior to weaning, would be as efficient as direct selection for total ADG to weaning.

Quantitative genetic studies on wool yellowing in Corriedale sheep. II. Clean wool colour and wool production traits: genetic parameter estimates and economic returns

2000 ◽  
Vol 51 (2) ◽  
pp. 191
Author(s):  
M. V. Benavides ◽  
A. P. Maher
Keyword(s):  
Selection Criteria ◽  
Selection Index ◽  
Genetic Parameter ◽  
Genetic Correlations ◽  
Fibre Diameter ◽  
Economic Losses ◽  
Direct Selection ◽  
Parameter Estimates ◽  
Selection Indices ◽  
Visual Colour

The potential for improvement of clean wool colour (CWC) in Corriedale sheep via selection was examined. The heritability, and phenotypic and genetic correlations, of CWC, brightness (Y), greasy (GFW) and clean (CFW) fleece weights , yield percentage (Yield), mean fibre diameter (MFD), and visual colour score were estimated from 440 progeny of 19 sires of a Corriedale flock using restricted maximum likelihood (REML) procedures with average information algorithm (AIREML). The heritability of CWC was estimated at 0.27±0.13. Clean wool colour showed strong positive genetic correlations with CFW and MFD. Visual colour score and CWC were also positively genetically correlated. As expected, direct selection criteria against MFD, CWC, or visual colour score would reduce CWC; however, direct selection against MFD would improve clean wool colour with negligible reductions on CFW, thus resulting in small economic gains. Several selection indices were calculated having either CFW, MFD, and CWC or CFW and MFD as selection criteria. The b-values of an unrestricted index were estimated at I1 = + 1.15 CFW + 0.13 MFD + 0.43 CWC, with positive correlated responses for all 3 breeding objective traits (CFW, MFD, and CWC). A second index, where CFW was restricted to nil genetic change, was estimated at: I2 = + 0.14 CFW − 0.02 MFD + 0.01 CWC. This index was expected to cause a negligible genetic gain for CWC (−0.04 Y–Z units/head.year). To avoid economic losses with the reduction on CFW, a third selection index was calculated where CWC was restricted to nil change. The index was estimated at I3 = +0.61 CFW − 0.07 MFD + 0.02 CWC with expected increases in CFW and decreases in MFD. Selection indices with (a) CFW and MFD (I4) and (b) CFW, MFD, and visual colour score (I5) as selection criteria would increase CFW, MFD, and CWC at the same rates observed in I1.

Usefulness of some components of the lactation curve for selection in Murrah buffaloes

1983 ◽  
Vol 36 (2) ◽  
pp. 277-283
Author(s):  
J. S. Cheema ◽  
S. B. Basu
Keyword(s):  
Milk Yield ◽  
Genetic Correlations ◽  
Indirect Selection ◽  
Direct Selection ◽  
Single Factor ◽  
Daily Production ◽  
Murrah Buffaloes ◽  
Lactation Curve ◽  
Selection For ◽  
Initial Peak

ABSTRACTThe study was based on 1156 lactation records of 545 Murrah buffaloes. Initial milk yield, peak yield, ascending phase milk yield and days to attain peak daily production, the means of which were 26·7 kg, 10·3 kg, 407 kg and 58·9 days respectively, were all affected by period, season and parity of calving. Heifers recorded the least initial milk yield and peak yield and took the longest time to reach peak production. Peak yield was the most important single factor (R2 = 0·41) in causing variation in 43-week milk yield. The heritability estimates for initial, peak and ascending phase milk yields and days to attain peak yield were 0·35, 0·51, 0·27 and 0·13 respectively, whilst that for 43-week milk yield was 0·18. Peak yield had the highest phenotypic (rP = 0·64) and genetic correlations (ra = 0·68 ± 0·19) with the 43-week milk yield. Other genetic correlations with the 43-week milk yield were low and non-significant. The results indicated that indirect selection for peak yield would be more effective than direct selection for improving the 43-week milk yield in buffaloes.

Selection for cellulose content, specific gravity, and volume in young Populusdeltoides clones

1985 ◽  
Vol 15 (2) ◽  
pp. 393-396 ◽  
Author(s):  
James R. Olson ◽  
Charles J. Jourdain ◽  
Randall J. Rousseau
Keyword(s):  
Specific Gravity ◽  
Mississippi River ◽  
Selection Index ◽  
Genetic Correlations ◽  
Wood Properties ◽  
Cellulose Content ◽  
Eastern Cottonwood ◽  
Growing Seasons ◽  
Lower Mississippi River ◽  
Selection For

Seventy-five eastern Cottonwood (Populusdeltoides Bartr.) clones, selected from tests representing the top one-third of clones tested throughout the Lower Mississippi River Valley, were analyzed for alpha cellulose content, specific gravity, and volume after three growing seasons. All traits were found to differ significantly among clones. Mean clonal alpha cellulose content ranged from 48.2 to 55.8% of oven-dry, extractive-free wood with an average of 51.1%. Specific gravity averaged 0.33, with clones ranging from 0.27 to 0.39. Specific gravity was highly inherited, while alpha cellulose content was found to be moderately heritable. Negative genetic correlations between volume and both wood properties indicate that using a selection index to simultaneously improve all three traits is currently not possible. Two other selection methods were discussed. These selections showed substantial gain differentials in volume, but either a small loss or improvement in specific gravity and alpha cellulose content. This indicates that at age 3 years only volume should be considered in a selection program.

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