scholarly journals Selection under assortative mating in mice

1968 ◽  
Vol 11 (2) ◽  
pp. 171-178 ◽  
Author(s):  
T. M. Sutherland ◽  
Patricia E. Biondini ◽  
L. H. Haverland

1. Approximately 25000 mice have been produced over twelve generations of selection in nine lines. The experimental design involved a 3 × 3 factorial arrangement of direction of selection with mating system. The primary character measured was 6-week body weight.2. Consistently high phenotypic correlations between mates have been achieved, positive in the assortative lines, negative in the disassortative lines. Correlations were low and inconsistent in direction in the random-bred lines. These correlations have had very little, if any, effect in redistributing the genetic variance as estimated from the variance component analysis; the expected higher variances in the assortative lines and expected lower variances in the disassortative lines have not appeared, thus leaving heritability unaffected.3. Selection differentials likewise show no consistent advantage for the assortative lines, so that the progress from selection has been virtually identical in all three mating systems in each direction.4. Assortment of mates, either positively or negatively, for characters of even moderate heritability appears to have little influence on the outcome of selection. On the other hand, selection has been singularly effective in modifying the mean 6-week weight, with progress markedly greater in the downward direction; indeed it appears that the lower limit, may already have been approximately attained.5. Environmental effects operating in the various generations have affected all lines in remarkably consistent fashion.

1989 ◽  
Vol 40 (2) ◽  
pp. 433 ◽  
Author(s):  
SI Mortimer ◽  
KD Atkins

Wool production traits were measured on Merino hogget ewes in an unselected multiple-bloodline flock over a 7-year period at Trangie Agricultural Research Centre, N.S.W. The traits measured were greasy fleece weight (GFW), skirted fleece weight (SKFW), yield (Y), clean fleece weight (CFW), fibre diameter (FD), body weight (BWT) and staple length (SL). These measurements were used to examine genetic differences between and within flocks of Merino sheep, and to estimate heritability of and genetic and phenotypic correlations among these traits. Significant strain, flock within strain and flock effects were present for all traits. Interactions between these effects and year were non-significant. Within-flock genetic variance was always larger than between-flock within strain genetic variance for each trait. The influence of environmental effects on these traits was also examined. The environmental effects of birth-rearing type, age at observation and age of dam together accounted for about 7-10% of the total within-flock variation in fleece weights and body weight.After adjusting for significant environmental effects, paternal half-sib heritability estimates were 0.29 �. 0.06 for GFW, 0.22 � 0.05 for SKFW, 0.35 � 0.05 for Y, 0.30 �0.06 for CFW, 0.48 �0.07 for FD, 0.34 �. 0.06 for BWT and 0.44 �0.07 for SL. Estimates for genetic and phenotypic correlations were in agreement with published estimates except for the genetic correlation between CFW and FD (0.40 �. 0.11), and the genetic correlations involving BWT, which were essentially zero. The implications of the results of this study for the genetic improvement of Merino sheep for wool production are discussed.


1960 ◽  
Vol 11 (1) ◽  
pp. 75 ◽  
Author(s):  
M Wodzicka

The monthly wool growth of three groups of rams was studied at Beltsville, Maryland. Group I received natural daylight (at 38° 53' N.) and was shorn monthly. Group II had a 7:17 hours of daylight to hours of darkness rhythm and was shorn every 6 months, once in winter and once in summer. Group III received natural daylight and was likewise shorn every 6 months. The rams of all groups produced more wool in summer than in winter. This difference was significant (P<0.001). The mean body weight and food intake were both greater in the winter months, which indicated that the seasonal rhythm of wool growth was not a consequence of poorer feeding in winter. The rams which were shorn monthly (group I) grew considerably more wool than the other two groups, but the difference was not statistically significant. The short-day treatment of group II did not increase the annual wool production nor decrease the seasonal rhythm of wool growth. The balance of evidence from this and other experiments indicates that temperature rather than light controls the seasonal rhythm of wool growth.


1967 ◽  
Vol 7 (24) ◽  
pp. 7 ◽  
Author(s):  
P McInnes ◽  
TJ Grainger ◽  
MD Smith

Data are presented on the recovery and reproductive performance of 2 1/2-year-old maiden Merino ewes after a prolonged period of undernutrition. The 217 sheep had been hand-fed on a submaintenance ration in pen feeding trials at Glenfield, New South Wales. During the seven months of the trials they had lost 6 kg (28 to 22 kg) body weight. They were transported to Condobolin in south-western New South Wales, divided into two treatment groups and run on good quality pastures. One group was joined immediately (May 1959) and again ten months later, and the other group was mated after six months at Condobolin (in October 1959) and again 12 months later. The ewes recovered rapidly. The mean weight of both groups had reached 30 kg within six weeks and 40 kg within six months. In the first year 73 of the 100 May-mated ewes bore lambs, but only 38 of these lambs were weaned. Ewes bearing lambs had a higher body weight at the start of joining and gained more during joining than the barren ewes. At the other three joinings (October 1959, May 1960, October 1960) lambing percentage was from 86-89 and weaning percentage from 62-69-both normal for the district. The proportion of twin lambs (3-6 per cent) was low. Wool weight in 1959 was not affected by time of mating or by pregnancy.


Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 5437-5437
Author(s):  
Jian Ouyang ◽  
Longdian Chen ◽  
Bing Chen ◽  
Jingyan Xu ◽  
Cuiping Li ◽  
...  

Abstract Nowadays it is widely used as glucocorticoids, ortho-oxybenzoic acid, immunosuppressive agents and biological agents for Crohn’s Disease. But all these agents can only control the symptoms rather than curing the diseases. About 70% patients need surgery in the course. 5 patents of Crohn’s Diseases have received AHSCT in our department since 2004. These patients, including 3 male and 2 female, with a mean age of 32 (range, 23~46), were final confirmed by enteroscope and histology. The mean CDAI of these patients was 213 points (range, 170~256), and the mean interval between invasion and transplantation was 63 months (range, 27~132 months). All the patients had mild or severe diarrhea and abdominal pain, one of them have a 6cm×7cm lump touchable in the abdominal region, while one of them complicated with vesicorectal fistula. These patients were mainly treated with glucocorticoids, SASP, cyclophosphamide (CTX), et al, which didn’t control the condition. Mobilization program was CTX 2g/m2 for 2 days and G-CSF 5~10 μg/kg/d on the 5th day of medication. Leukapheresis was initiated when WBC>5.0×109/L. The collections of CD34+ cells from two cases were over 4×106/kg, and ClinMACs cell separation system was used to purify the CD34+ cells and to deplete T cells. Two collections of CD34+ cells were 1.3×106/kg and 2.8×106/kg, respectively, and then were kept in −80°. And the other case failed in the collection, and then was treated with bone marrow transplantation. The conditioning programs were MC (CTX 60mg/kg -2, -1d;melphalan 140mg/m2 -2d) for one case, and CTX 50mg/kg×4d for the other 4 cases. 2 of the 3 patients without in vitro purification of CD34+ cells to deplete T cells were treated with rabbit antithymocyte globulin 5 mg/kg on day-2 and day -1 for T cell depletion. The mean CD34+ cells infused was 1.4×106/kg(range, 1.3×106/kg~2.8×106/kg). Neutrophile granulocyteand>0.5×109/L occurred at day +10~+12, while platelet>2.0×109/L occurred at day +9~+11. Fever occurred in all patients in the granulocytopenia phase, and lasted from 1 to 3 weeks. One of the patients complicated with ESBL+ ichoremia, and was cured with antibiotics. After the transplantation, 2 patients were treated with prednisone 10mg/d as maintenance therapy, and the other 3 stopped using antidiarrheal and glucocorticoids. 4 patients got free of abdominal pain and diarrhea in the following 2~3 months, and the other did in 1 year. The average body weight of the patients increased 11.2 kg (range, 3~20kg) 3 months after transplantation. The mean follow-up was 16 months. 2 patients have been maintaining remission until now. The lump in the abdomen of one of these 2 patient decreased from 6×7cm to 5×5cm, which was resected 19 months after transplantation. And this patient is still in remission now. 3 patients relapsed after 4~8 months of remission. One of them relapsed 5months after transplantation and died complicated with peritonitis in 7 months. One patient relapsed in 8 months with abdominal discomfort, mild diarrhea, and decreasing of body weight. The other complicated with rectovesical fistula showed closure of syrinx by barium enema, and suffered abdominal discomfort, mild diarrhea, and decreasing of body weight too 4 months after transplantation, then relapsed with rectovesical fistula 8 months after transplantation. HSCT for Crohn’s disease is safe and effective. However, it has a comparative higher relapse rate.


1981 ◽  
Vol 32 (4) ◽  
pp. 641 ◽  
Author(s):  
IP Gregory ◽  
RW Ponzoni

During the years 1953-67 one flock of South Australian Merinos was selected on clean fleece weight (the Index flock) and another on the basis of visual appraisal (the Visual flock). A large number of qualitative and quantitative traits were recorded. Linear regressions of differences between flock means on time were estimated for each trait; not many of the regressions were significant. However, greasy and clean fleece weights of Index animals increased significantly faster than those of Visual animals, and body weights of Visual animals increased significantly faster than those of Index animals. Realized selection differentials were estimated for all traits. There were significant selection differentials for greasy and clean fleece weights and yield in the Index flock, and for body weight and greasy fleece weight in the Visual flock. The response to selection was estimated for all traits by using two methods; regression of the trait on an individual's generation number, and comparison of the deviation from the overall mean of the mean of the progeny of a 3+-year-old sire with the deviation of the progeny of the same sire as a 2+-year-old. The estimate of genetic change in body weight was higher and genetic changes in clean and greasy fleece weights lower in Index animals, which was in contrast with an earlier result. However, when the least-squares means of these traits were compared, it was concluded that the Index flock did, in fact, achieve significantly greater responses in greasy and clean fleece weights and a significantly lower response in body weight than the Visual flock. It was therefore considered that, in these particular experiments, both methods of estimating genetic change had serious limitations.


HortScience ◽  
2004 ◽  
Vol 39 (4) ◽  
pp. 881A-881
Author(s):  
Zhanyong Sun* ◽  
Richard L. Lower ◽  
Jack E. Staub

The incorporation of genes for parthenocarpy (production of fruit without fertilization) has potential for increasing yield in pickling cucumber (Cucumis sativus L.). The inheritance of parthenocarpy in cucumber is not well understood, and thus a genetic analysis was performed on F3 cross-progeny resulting from a mating between the processing cucumber inbred line 2A (P1, gynoecious, parthenocarpic, indeterminate, normal leaf) and Gy8 (P2, gynoecious, non-parthenocarpic, indeterminate, normal leaf). A variance component analysis was performed to fruit yield data collected at two locations (designated E-block and G-block) at Hancock, WI in 2000. The relative importance of additive genetic variance compared to dominance genetic variance changed across environments. The additive genetic variance was 0.5 and 4.3 times of dominance genetic variance in E-block and G-block, respectively. The estimated environmental variance accounted for ≈90% of the total phenotypic variance on an individual plant basis in both locations. Narrow-sense heritability estimated on an individual plant basis ranged from 0.04 (E-block) to 0.12 (G-block). Broad-sense heritability estimated on an individual plant basis ranged from 0.12 (E-block) to 0.15 (G-block). The minimum number of effective factors controlling parthenocarpy was estimated to range between 5 (G-block) to 13 (E-block). These results suggest that the response to direct selection of individual plants for improving parthenocarpy character will likely be slow and difficult. Experiment procedures that minimize the effect of environment on the expression of parthenocarpy will likely maximize the likelihood of gain from selection.


1994 ◽  
Vol 119 (3) ◽  
pp. 620-623 ◽  
Author(s):  
P.G. Thompson ◽  
John C. Schneider ◽  
Boyett Graves

Narrow-sense heritability for component traits of freedom from weevil injury and yield of sweetpotato were estimated by parent-offspring regression and variance component analysis. Heritability estimates by variance component analysis based on half-sib families for percent and number of uninjured roots were 0.25 and 0.83, respectively. Individual plant heritability estimates for uninjured root percent and number were 0.03 and 0.13, respectively. Heritability estimates by parent-offspring regression for uninjured root percent and number were 0.35 and 0.52, respectively. Genetic variance was mostly additive for all traits except stem diameter. Genetic correlations between total root number, uninjured root number, and percent uninjured roots ranged from 0.66 to 0.87, indicating that selection for uninjured root number should most effectively increase uninjured root number and percent, as well as total root numbers. Predicted gains in uninjured root percent and number were 8.8% and 0.87 in the progeny derived from intermating the highest four out of 19 families for uninjured root number. The 0.87 gain in uninjured root number equals a 24% increase in one breeding cycle.


1963 ◽  
Vol 14 (6) ◽  
pp. 882 ◽  
Author(s):  
NM Tulloh

A comparative growth study was made of Hereford, Aberdeen Angus, and beef Shorthorn cattle reared and kept together throughout their lives on irrigated perennial pastures at the Metropolitan Farm, Werribee, Vic. Records of body weight as a function of age were obtained on 404 Hereford, 172 Aberdeen Angus, and 127 Shorthorn cattle, representing cattle born in 1955, 1957, 1958, 1959, and 1960. At birth, male calves were significantly heavier than females, and Hereford calves were significantly heavier than Shorthorn and Aberdeen Angus calves, the birth weights of Shorthorn and Aberdeen Angus calves being similar. Up to the age of 5 years, the younger and lighter 2-year-old cows produced lighter calves than cows which were both older and heavier. At weaning age (9.5 months) steers were significantly heavier than heifers. Herefords were significantly heavier than Aberdeen Angus in two years out of three; and in one year out of three, Herefords were significantly heavier than Shorthorns. Shorthorns were significantly heavier than Aberdeen Angus in one year out of three. When the steers were finally weighed off grass at the mean age of either 20 months (1958, 1959, and 1960 cattle) or 25 months (1957 cattle), Herefords were significantly heavier than Aberdeen Angus in four successive years, and in one year out of four the Herefords were significantly heavier than Shorthorns. In three years out of four, Shorthorns were significantly heavier than Aberdeen Angus. Breed differences between the mean weights of breeding cows were not significant and, up to the age of 5 years, as breeding cows grew older they became heavier. Body weight growth curves indicated that the cattle experienced a severe check in growth during the winter months (June, July, August). At other times of the year, growth rates were satisfactory. Cattle born in some years grew better than cattle born in others. This was thought to be due partly to differences between years in the quality and quantity of pasture available, even though the pastures were irrigated. Average absolute and average relative growth rates were calculated for the 1957 and 1958 steers before and after weaning. Breed differences in absolute growth rates before weaning were not statistically significant, but after weaning, rates were significantly the highest for Herefords in both years. The breed differences in average relative growth rates were in the same direction as those for absolute growth rates. However, the pre-weaning relative growth rate of Shorthorns was significantly higher than those of the other breeds among the 1957 steers. When due allowance was made for the smaller size of Aberdeen Angus steers at birth and at weaning, the relative growth rates of this breed were less than those of the other breeds. Absolute and relative growth rates were higher for all breeds before weaning than afterwards. This was mainly a reflexion of low post-weaning growth rates during the winter months. Rank correlation coefficients between birth weight and weight at subsequent ages were low and variable in different breeds and in different seasons. However, coefficients calculated between subsequent ages, beginning at weaning age, were generally highly significant. The breed and sex differences presented in this paper have been compared with the limited data from the literature and, in general, the results are similar.


1967 ◽  
Vol 7 (26) ◽  
pp. 206 ◽  
Author(s):  
MC Franklin ◽  
P McInnes ◽  
PK Briggs

Merino wethers of 30 months of age were hand-fed in pens on low-(chaffed wheaten straw), medium-(84 per cent chaffed wheaten straw; 16 per cent chopped lucerne hay), and high-protein roughage (chopped wheaten hay, or 67.5 per cent chaffed wheaten straw : 32.5 per cent chopped lucerne hay) alone, or supplemented with wheat grain at daily or twice-weekly intervals. The experimental period was 26 weeks and emphasis was placed on the number of survivors, changes in body weight, and mean daily roughage intake. Data were also collected on wool production. No sheep survived on the low-protein roughage (LPR-2.7 per cent crude protein (CP) ). Seven out of 16 sheep in the medium-protein roughage group (MPR-5.2 per cent CP) survived for 26 weeks ; six of these, however, died in the following four weeks. All sheep survived on the two high-protein roughage diets (HPR(1) and HPR(2)-7.6 per cent CP). The wheat supplement increased the number of survivors in the LPR and MPR groups. There was no difference between results from the daily and twice-weekly supplemented groups. Mean daily roughage intake of the unsupplemented sheep increased at each level of protein in the roughage. Mean intake of chaffed wheat straw when fed alone was 220 g per sheep per day. The intake of the same straw when fed with chopped lucerne hay increased by 120 g per sheep per day in the group fed MPR, and by 344 g in the group fed HPR(1). The wheat supplement did not increase intake within any roughage group. Roughage intake was significantly decreased on the HPR(2) diet when a wheat supplement was given. Sheep fed HPR(2) grew more clean wool than sheep in the other unsupplemented groups. Differences between mean clean wool weights of daily and twice-weekly supplemented groups within each roughage group were not significant, but differences between the mean pooled wool weights of each supplemented roughage group were significant.


2013 ◽  
Vol 31 ◽  
pp. 23-26
Author(s):  
Jesmin Ahktar ◽  
Abdus Salam Bhuiyan

An experiment on the induced breeding of the endangered fish, Labeo calbasu (Hamilton-Buchanam) was conducted in the Fish Seed Multiplication Farm,Rajshahi to know the efficacy of two inducing agents (PG and DoM+SGnRH). Three breeding trials of each inducing agent were performed. A total of 24 females weighing from 1.5 kg to 2 kg were given an initial and a resolving dose of 1.5 mg and 6 mg PG extract per kg body weight respectively as treatment-1. On the other hand, a total of 24 females weighing from 1.5 kg to 2 kg were given a single dose of 12 mg DoM + SGnRH/kg as treatment-2. In case of treatment-1, 12 males weighing from 1.5 kg to 1.95 kg were administered a single dose of 1.5 mg PG/kg body weight during resolving dose of female. In treatment-2, 12 males weighing from 1.5 kg to 1.8 kg were administered 3 mg DoM+SGnRH /kg body weight during initial dose of females. In treatment-1, the time interval between initial and resolving dose was 5 hours and ovulation occurred in all the injected females within 6 hours after resolving dose. Ovulation occurred within 6 to 8 hours after the injection of inducing agents for treatment-2. The mean rates of ovulation, fertilization and hatching were 100%, 77.36% and 74.5% respectively in treatment-1. On the contrary, the mean rates of ovulation, fertilization and hatching were 83.33%, 63.83% and 59.66% in treatment-2. Hatchery produced fry were reared in nursery pond for 40 days. In nursery pond. Flour, oil cake and wheat bran were applied as nursery feeds. Both the inducing agents were effective in respect of overall breeding performance. But the best results were obtained with PG although in case of DoM+SGnRH complete breeding takes place within short time with less labour and cost than that of PG.DOI: http://dx.doi.org/10.3329/ujzru.v31i0.15376Univ. j. zool. Rajshahi Univ. Vol. 31, 2012 pp. 23-26


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