Corrigendum - Response to selection in Australian Merino sheep. I. Selection for high clean wool weight, with a ceiling on fibre diameter and degree of skin wrinkle. Response in wool and body characteristics

1968 ◽  
Vol 19 (1) ◽  
pp. 79
Author(s):  
HN Turner ◽  
CHS Dolling ◽  
JF Kennedy
Keyword(s):  
Fibre Diameter ◽  
The Other ◽  
Correlated Response ◽  
Mass Selection ◽  
Skin Area ◽  
Response To Selection ◽  
High Degree ◽  
Second Period ◽  
Final Selection ◽  
Staple Length

Direct and correlated responses are reported for two groups of sheep selected for high clean wool weight. The work covers two periods. In the first (1950–59), both groups had selection against high average fibre diameter and high degree of skin wrinkle, but in one group (S) the performance of the ram's half-sibs was considered as well as his own, while in the other (MS) mass selection was practiced for rams. For ewes, mass selection was practiced in both groups. In the second period (1961–64), mass selection was used for both sexes in both groups, with selection against high diameter and degree of wrinkle in one group (S), and against low crimp frequency and high degree of wrinkle in the other (MS). In both periods response to selection was assessed by comparison with a random control group. In the first period, response in clean wool weight was similar in S and MS, both for rams measured at 10–11 months, when a preliminary selection on them was carried out, and for ewes measured at 15–16 months, when final selection was made for both sexes. The annual rates of increase in clean wool weight for S and MS were 2.1 and 1.8% for rams and 2.4 and 2.7% for ewes, the lower rate in rams being due to the fact that response at 10–11 months is a correlated response to the final selection at 15–16 months. As the rates of increase in the two groups are similar, it can be concluded that examination of half-sibs is not worth while; this would in fact have been predicted from the high heritability estimates for clean wool weight. There were negligible trends in fibre diameter and wrinkle score, indicating that counter-selection has been effective in preventing an increase in these characteristics. Fibre number per unit skin area made the greatest contribution to the increases in clean wool weight, the annual rates of increase for S and MS being 2.0 and 2.2% for rams and 2.0 and I .8% for ewes. Greasy wool weight, percentage clean yield, body weight, and staple length also showed increases with increasing clean wool weight in both selected groups. In spite of the fact that fibre diameter did not increase, crimp number per unit of staple length decreased in both groups. This is a further confirmation of the strong negative genetic correlation between clean wool weight and crimp number, and of the lack of a strong association between crimp number and fibre diameter. In the second period, no further response was observed. It is impossible to say at this stage whether a selection plateau has been reached or whether drought conditions interfered with response.

Response to selection in Australian Merino sheep. I. Selection for high clean wool weight, with a ceiling on fibre diameter and degree of skin wrinkle. Response in wool and body characteristics

1968 ◽  
Vol 19 (1) ◽  
pp. 79
Author(s):  
HN Turner ◽  
CHS Dolling ◽  
JF Kennedy
Keyword(s):  
Fibre Diameter ◽  
The Other ◽  
Correlated Response ◽  
Mass Selection ◽  
Skin Area ◽  
Response To Selection ◽  
High Degree ◽  
Second Period ◽  
Final Selection ◽  
Staple Length

Direct and correlated responses are reported for two groups of sheep selected for high clean wool weight. The work covers two periods. In the first (1950–59), both groups had selection against high average fibre diameter and high degree of skin wrinkle, but in one group (S) the performance of the ram's half-sibs was considered as well as his own, while in the other (MS) mass selection was practiced for rams. For ewes, mass selection was practiced in both groups. In the second period (1961–64), mass selection was used for both sexes in both groups, with selection against high diameter and degree of wrinkle in one group (S), and against low crimp frequency and high degree of wrinkle in the other (MS). In both periods response to selection was assessed by comparison with a random control group. In the first period, response in clean wool weight was similar in S and MS, both for rams measured at 10–11 months, when a preliminary selection on them was carried out, and for ewes measured at 15–16 months, when final selection was made for both sexes. The annual rates of increase in clean wool weight for S and MS were 2.1 and 1.8% for rams and 2.4 and 2.7% for ewes, the lower rate in rams being due to the fact that response at 10–11 months is a correlated response to the final selection at 15–16 months. As the rates of increase in the two groups are similar, it can be concluded that examination of half-sibs is not worth while; this would in fact have been predicted from the high heritability estimates for clean wool weight. There were negligible trends in fibre diameter and wrinkle score, indicating that counter-selection has been effective in preventing an increase in these characteristics. Fibre number per unit skin area made the greatest contribution to the increases in clean wool weight, the annual rates of increase for S and MS being 2.0 and 2.2% for rams and 2.0 and I .8% for ewes. Greasy wool weight, percentage clean yield, body weight, and staple length also showed increases with increasing clean wool weight in both selected groups. In spite of the fact that fibre diameter did not increase, crimp number per unit of staple length decreased in both groups. This is a further confirmation of the strong negative genetic correlation between clean wool weight and crimp number, and of the lack of a strong association between crimp number and fibre diameter. In the second period, no further response was observed. It is impossible to say at this stage whether a selection plateau has been reached or whether drought conditions interfered with response.

Response to selection in Australian Merino sheep. III. Single character selection for high and low values of wool weight and its components

1970 ◽  
Vol 21 (6) ◽  
pp. 955 ◽  
Author(s):  
HN Turner ◽  
MG Brooker ◽  
CHS Dolling
Keyword(s):  
Body Weight ◽  
Unit Area ◽  
Genetic Correlations ◽  
Fibre Diameter ◽  
Initial Response ◽  
Skin Area ◽  
Correlated Responses ◽  
Fibre Number ◽  
Selection For ◽  
Staple Length

Direct and correlated responses are reported for 10 traits in eight pairs of lines under selection for high and low values of single characteristics : clean wool weight per head, clean wool weight per unit skin area (measured only in the groups under selection for it), body weight, wrinkle score, fibre number per unit skin area (adjusted for body weight), fibre diameter, staple length, and percentage clean yield. All groups showed overall divergence in the character under selection, though response was not always symmetrical, and in two cases (long staple and low fibre number) there was no continuing response after the initial response to extreme selection of the base parents. In all except one case, whenever previous estimates of genetic correlation were at the level of 0.2 or higher, correlated responses were in the predicted direction, though not always symmetrical in magnitude. The exception was a previously reported negative correlation between fibre number and staple length, which was not exhibited under selection for either character. Where two characters of a pair were under selection, reciprocal responses agreed in sign; magnitude will be examined in a later paper. Wool per unit area was shown to have a greater influence on clean wool weight than that of surface area, with staple length on this occasion being the most important component of wool per unit area. Reasons for an apparent decrease in the relative importance of fibre number are discussed. Three other points of importance in sheep breeding are again emphasized by these results : 1. Crimp in several pairs of groups was a poor indicator of fibre diameter. 2. Increases in clean wool weight were associated with falls in crimp number, even though fibre diameter actually became finer; diameter, not crimp, should therefore be used as a guide to wool quality. 3. The absence of genetic correlations DL and NL indicates that selection can be for high N (fibre number) with high L (staple length) and low D (fibre diameter) -in other words, a desirable fleece -with no impeding genetic correlations.

A comparison of the production of F1 and F2 Border Leicester × Merino ewes

1964 ◽  
Vol 4 (12) ◽  
pp. 80 ◽  
Author(s):  
WA Pattie ◽  
MD Smith
Keyword(s):  
Body Weight ◽  
Density Ratio ◽  
Fibre Diameter ◽  
The Other ◽  
Multiple Births ◽  
Significant Drop ◽  
Major Genes ◽  
Horn Growth ◽  
Production Characteristics ◽  
Staple Length

A comparison has been made of the production characteristics of 255 F1 and 288 F2 Border Leicester x Merino ewes. These sheep comprised a total drop of ewes born in a breed establishment trial in March-April 1960. There were no significant differences between the means of each group of ewes for the following characters : 18 month body weight, mutton score, fleece and breech score, yield, staple length, crimps per inch, fibre diameter, follicle density, ratio of primary to total follicles, and wool colour and character. The F1 ewes had significantly heavier greasy and clean fleece weights and showed significant though only slightly greater face cover scores. There was no significant increase in the variation of any character studied, in the F2 ewes. It is considered that these results are reasonable when the nature of inheritance of production characters, and their susceptibility to environment are considered. On the other hand the variance of horn growth, which is controlled by a few major genes, increased considerably in the F2 ewes. There was a large (40 per cent) and significant drop in fertility in the F2 ewes brought about by a drop in the number of wet ewes and multiple births, and an increase in lamb losses. The significance of these findings in relation to crossbreeding and breed establishment is discussed.

Heritability, correlated response, and indirect selection involving spectral reflectance indices and grain yield in wheat

2007 ◽  
Vol 58 (5) ◽  
pp. 432 ◽  
Author(s):  
M. A. Babar ◽  
M. van Ginkel ◽  
M. P. Reynolds ◽  
B. Prasad ◽  
A. R. Klatt
Keyword(s):  
Grain Yield ◽  
Spectral Reflectance ◽  
Genetic Correlations ◽  
Grain Filling ◽  
Indirect Selection ◽  
The Other ◽  
Correlated Response ◽  
Response To Selection ◽  
Selection For ◽  
Reflectance Indices

The objectives of this study were to assess the potential of using spectral reflectance indices (SRIs) as an indirect selection tool for grain yield in wheat under irrigated conditions. This paper demonstrates the genetic correlation between grain yield and SRIs, heritability and expected response to selection for grain yield and SRIs, correlated response to selection for grain yield estimated from SRIs, and efficiency of indirect selection for grain yield using SRIs in different spring wheat populations. Four field experiments, GHIST (15 CIMMYT globally adapted genotypes), RLs1 (25 random F3-derived families), RLs2 (36 random F3-derived families), and RLs3 (64 random F5-derived families) were conducted under irrigated conditions at the CIMMYT research station in north-west Mexico in 3 different years. Spectral reflectance was measured at 3 growth stages (booting, heading, and grain filling) and 7 SRIs were calculated using average values of spectral reflectance at heading and grain filling. Five previously developed SRIs (PRI, WI, RNDVI, GNDVI, SR), and 2 newly calculated SRIs (NWI-1 and NWI-2) were evaluated in the experiments. In general, the within- and between-year genetic correlations between grain yield and SRIs were significant. Three NIR-based indices (WI, NWI-1, and NWI-2) showed higher genetic correlations (0.73–0.92) with grain yield than the other indices (0.35–0.67), and these observations were consistent in all populations. Broad-sense heritability estimates for all indices were in general moderate to high (0.60–0.80), and higher than grain yield (0.45–0.70). The realised heritability for the 3 NIR-based indices was higher than for the other indices and for grain yield itself. Expected response to selection for all indices was moderate to high (0.54–0.85). The correlated response for grain yield estimated from the 3 NIR-based indices (0.59–0.64) was much higher than the correlated response for grain yield estimated from the other indices (0.31–0.46), and the efficiency of indirect selection for these 3 NIR-based indices was 90–96% of the efficiency of direct selection for grain yield. These results demonstrate the potential for using the 3 NIR-based SRI tools in breeding programs for selecting for increased genetic gains for yield.

The effects of anthelmintic treatment and season on the quantity and quality of wool grown by Merino sheep

1983 ◽  
Vol 34 (5) ◽  
pp. 557 ◽  
Author(s):  
NJ Barton ◽  
CJ Brimblecombe
Keyword(s):  
Fibre Diameter ◽  
Summer Season ◽  
The Other ◽  
Anthelmintic Treatment ◽  
Merino Sheep ◽  
Wool Production ◽  
Wool Growth ◽  
Effect On Yield ◽  
Staple Length

Groups of 30 Merino weaner sheep were grazed in East Gippsland, Vic., and subjected to one of four anthelmintic programs during the 12-month period from December 1977. They were treated with thiabendazole either weekly (W), nine times (H), three times (L) or once (S). These programs resulted in marked differences in the degree of parasitism between the groups. Over the 12 months, parasites had no significant effect on yield, staple length or crimp frequency. However, compared with the wool from sheep treated weekly, greasy wool production was depressed by 13, 22 and 20% respectively in sheep given nine, three or one anthelmintic dose. Fibre diameter was also reduced. Dyebands were used to delineate wool grown during summer, autumn, winter and spring. Where parasite burdens were minimized (W group), wool growth, fibre diameter and rate of staple growth increased each season throughout the year. There was little increase in these characters in the other three groups until the spring, and wool growth and fibre diameter were significantly less than that of the W sheep in all but the initial summer season. Wool growth:fibre volume ratios indicated that sheep continued to initiate new fibres at least until the end of summer, when they were 9 months old. The subsequent depression in the wool growth of sheep dosed at less than weekly intervals provides further evidence of the deleterious effects parasites may have on the production of young sheep, even where anthelmintic is administered fairly frequently.

scholarly journals Linear heritability estimates

1961 ◽  
Vol 2 (3) ◽  
pp. 439-448 ◽  
Author(s):  
Hans Abplanalp
Keyword(s):  
Genetic Correlation ◽  
The Other ◽  
Correlated Response ◽  
Response To Selection ◽  
Population Mean ◽  
Straight Line ◽  
The Mean ◽  
Heritability Estimates ◽  
Selection Of ◽  
Prospective Parents

A method for obtaining linear estimates of heritability and genetic correlation is given. It is based, essentially, on selecting, from a pedigreed population, prospective parents for which estimates of average genotype and phenotype values are obtained; a regression of genotype on phenotype value is then determined from a straight line fitted through points representing the population mean genotype and phenotype on one hand and the mean genotype and phenotype of selected parents on the other.The method permits an evaluation of asymmetry in response for a trait selected in both directions, as well as asymmetry in correlated response to selection of two different traits, with data from a single pedigreed population.

COMPARISON OF FOUR METHODS OF SELECTION FOR RESISTANCE TO LEPTOSPHAERULINA BRIOSIANA IN ALFALFA

1979 ◽  
Vol 21 (2) ◽  
pp. 179-186 ◽  
Author(s):  
R. R. Hill Jr. ◽  
K. T. Leath
Keyword(s):  
Selection Method ◽  
The Other ◽  
Correlated Response ◽  
Response To Selection ◽  
Selection Methods ◽  
Family Selection ◽  
Colletotrichum Trifolii ◽  
Family Types ◽  
Medicago Sativa L ◽  
Selection For

Three cycles of selection for resistance to Leptosphaerulina briosiana (Poll.) Graham &Luttrell were conducted in two alfalfa (Medicago sativa, L.) germplasm pools, MSA and MSB. Each germplasm pool was used to compare four methods of selection: phenotypic recurrent, half-sib family, full-sib family, and alternating generations of selfed family and half-sib family. Response to selection for resistance to L. briosiana was greater in MSA than in MSB. Differences between selection methods were not significant. Selection for resistance to L. briosiana generally increased resistance to Stemphylium botryosum Wallr., but the magnitude of the correlated response varied with germplasm pool and selection method. The initial selfed families in both germplasm pools were significantly less resistant to Colletotrichum trifolii Bain than the other family types. Resistance to C. trifolii increased with selfed family selection for resistance to L. briosiana in MSA but not in MSB.

Efficiency of conversion of food to wool. I. Correlated response to selection for high and low clean wool weight

1960 ◽  
Vol 11 (5) ◽  
pp. 836 ◽  
Author(s):  
CHS Dolling ◽  
RW Moore
Keyword(s):  
The Other ◽  
Correlated Response ◽  
Response To Selection ◽  
Merino Sheep ◽  
Wool Production ◽  
The Family ◽  
Selection For ◽  
The Difference ◽  
Selection Of

The offspring of two families of medium Peppin Merino sheep, one family being selected for high and the other for low clean wool weight per head at 15-16 months of age under grazing conditions, have also been shown to differ significantly in the ratio of wool production to food eaten in pens, on a ration slightly above maintenance. These ratios were in the proportion 108 : 100, and the difference between the families can be taken as reflecting closely a difference in net efficiency of conversion of food to wool. It may be concluded that selection for high clean wool weight per head under grazing conditions had also resulted in the selection of more efficient animals. Clean wool production per head in the two families was in the ratio 110 : 100 in the pens, compared with 124 : 100 under grazing. The difference under grazing probably results from both the higher efficiency of the family selected for high clean wool weight and a higher grazing intake by this family.

Lamb birthcoat relationship to the adult fleece in Merino, coarse wool Barki and Merino × Barki sheep crosses

1982 ◽  
Vol 99 (1) ◽  
pp. 131-138
Author(s):  
R. A. Guirgis
Keyword(s):  
Fibre Type ◽  
Fibre Diameter ◽  
The Other ◽  
Fleece Weight ◽  
Selection Of ◽  
Staple Length

SUMMARYThe present study was carried out on adult fleeces, of Merino, coarse wool Barki and five of their crosses, of known birthcoats. The adult fleece traits studied were clean fleece weight, mean fibre diameter and its variability and mean staple length and its variability.Birthcoat-adult fleece relationship was dependent on the breed studied. In Barki, plateau array in the birthcoat developed to adult fleeces with higher values of mean fibre diameter and its variability, mean staple length and clean fleece weight than those with saddle array. In ⅝ Merino there was a gradient in staple length, running from plateau, via saddle, to ravine, with higher values of the coarser arrays. Differences occurred in variability of fibre diameter between plateau and saddle arrays in ⅜ and ⅝ Merino and between saddle and ravine in ½, ⅝ and ¾ Merino.Differences occurred where birthcoats, with plateau array with precipice, in the curly-tip group, grew into adult fleeces with longer mean staple than those with transition in Barki sheep. In the other breed groups differences observed in saddle array, with different features, precipice or transition, at the birthcoat level, did not contribute differences in their adult fleeces.Selection of Barki lambs with plateau fibre type array in their birthcoats would result in higher clean adult fleece weights that have coarser fibre diameter, with higher variability, and longer staple than those with saddle array. Within saddle array, selection of those with reduced SK% would develop into adult fleeces with higher clean fleece weight and those with reduced CT% would grow into adult fleeces with finer diameter.Selection of lambs that have birthcoat ravine array in f, ⅜, ½, ⅝ and ¾ Merino would reduce the within-staple variability in their adult fleece fibre diameter.

Correlated response to selection for litter size in pigs: II. Carcass, meat, and fat quality traits

2002 ◽  
Vol 80 (10) ◽  
pp. 2566 ◽  
Author(s):  
J. Estany ◽  
D. Villalba ◽  
M. Tor ◽  
D. Cubiló ◽  
J. L. Noguera
Keyword(s):  
Litter Size ◽  
Correlated Response ◽  
Quality Traits ◽  
Response To Selection ◽  
Fat Quality ◽  
Selection For
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