Skin folds and Merino breeding. 1. The net reproductive rates of flocks selected for and against skin fold

1964 ◽  
Vol 4 (15) ◽  
pp. 376 ◽  
Author(s):  
RB Dun
Keyword(s):  
Vital Statistics ◽  
Reproductive Rate ◽  
Relative Importance ◽  
Differential Survival ◽  
Net Reproductive Rate ◽  
Skin Fold ◽  
Single Character ◽  
Selection For ◽  
The Difference ◽  
Reproductive Rates

Single character selection flocks-Folds Plus (selection for high fold score) and Folds Minus (selection for low fold score)-were established at Trangie in 1951 from a Peppin Merino flock. The Trangie environment over the period 1951 to 1960 has been described relative to the management of these experimental flocks. An analysis of the vital statistics for the first nine joinings showed a net reproductive rate (the number of 19 month old replacement ewes produced by a ewe in her lifetime) for Folds Plus of 1.248 compared with 2.270 for Folds Minus. This resulted from the Folds Minus flock having a higher percentage of ewes wet and twins mothered, from it having lower mortality rates of young sheep between birth and mothering, between mothering and weaning, and between weaning and 19 months, as well as from it having lower death and casting rates of mature ewes. An analysis of the relative importance of each component of net reproductive rate (N) in contributing to the difference between the Folds flocks (percentage deviation technique) showed :- 1. Twenty eight per cent of the difference could be ascribed to wet ewes (W) and nine per cent to twinning (M) a total of 37 per cent from lambs born per ewe mated (L). 2. Differential survival rate of lambs between birth and 19 months (S) contributed 36 per cent, made up of 17 per cent birth to mothering (Sm), 11 per cent mothering to weaning (Sw), and 8 per cent weaning to 19 months (Sj). 3. The remaining 27 per cent was contributed by the annual wastage of breeding ewes as this affected the number of times a ewe is joined in her lifetime (J). This component was further divided into 16 per cent from death rate (D) and 11 per cent from casting rate (C).

Skin folds and Merino breeding. 2. The relative influence of the ram and the ewe on fertility and perinatal lamb mortality in flocks selected for and against skin fold

1965 ◽  
Vol 5 (18) ◽  
pp. 236 ◽  
Author(s):  
RB Dun ◽  
BA Hamilton
Keyword(s):  
Birth Weight ◽  
Genetic Correlation ◽  
Reproductive Performance ◽  
Maternal Effect ◽  
Reproductive Rate ◽  
Independent Data ◽  
Net Reproductive Rate ◽  
Skin Fold ◽  
Cent Mortality ◽  
The Difference

Reciprocal matings were carried out between the Trangie Folds Plus and Folds Minus selection Aocks in March 1961 and 1962. Folds Minus rams were more fertile than Folds Plus rams as shown by ewes lambing per insemination (72 per cent versus 48 per cent, P&0.01) and by incidence of twinning per ewe lambing (57 per cent versus 34 per cent, P<0.05). Folds Plus and Folds Minus ewes showed a similar reproductive performance if mated to the same rams. 236 There was a 17 per cent mortality in single lambs born to Folds Plus ewes compared with 4 per cent (P<0.05) for single lambs born to Folds Minus ewes. This increased mortality was caused by dystocia in association with relative oversize of the lamb. A positive genetic correlation of 0.32 � 0.21 between fold score and corrected birth weight was calculated using independent data. The mortality of twin lambs born to Folds Minus ewes was higher than for Folds Plus ewes (18 per cent versus 11 per cent). There was a maternal effect on the birth weight of twins, which were relatively much heavier from Folds Plus ewes. Approximately 80 per cent of the difference in net reproductive rate between the Folds Minus and Folds Plus flocks was explained on the basis of infertility of Folds Plus rams and excessively heavy birth weights of Folds Plus lambs.

Skin folds and Merino breeding. 8. Fertility of individual rams in flocks selected for high and low skin fold

1969 ◽  
Vol 9 (37) ◽  
pp. 147 ◽  
Author(s):  
BJ McGuirk
Keyword(s):  
Artificial Insemination ◽  
Agricultural Research ◽  
New South ◽  
New South Wales ◽  
Research Station ◽  
South Wales ◽  
Skin Fold ◽  
Single Character ◽  
Lower Fertility ◽  
Selection For

Single character selection flocks-Folds Plus (selection for high fold score) and Folds Minus (selection for low fold score) were established in 1951 from a Peppin Merino flock at Trangie Agricultural Research Station, New South Wales. For the period 1951 to 1966, 25 per cent of rams selected for the Folds Plus flock were rejected following semen examination before joining, compared to only three per cent of Folds Minus rams (P<0.05). The fertility of individual rams in the two flocks has been estimated from the lambing performance of the ewes to which they were mated in the period 1951 to 1963. Averaged over the twelve joinings, a higher proportion of ewes mated to Folds Minus rams lambed following both artificial insemination (53 v. 45 per cent) and paddock joinings (57 v. 47 per cent). The lower fertility of the Folds Plus rams was not due to a higher proportion of completely infertile rams.

Bionomics of Cheyletus eruditus (Schrank) (Acarina: Cheyletidae), a predator of Lepidoglyphus destructor (Schrank) (Acarina: Glycyphagidae), at three constant temperatures

1991 ◽  
Vol 69 (9) ◽  
pp. 2321-2325 ◽  
Author(s):  
Philip S. Barker
Keyword(s):  
Adult Mortality ◽  
Predatory Mite ◽  
Reproductive Rate ◽  
Net Reproductive Rate ◽  
First Instar ◽  
Total Female ◽  
Reproductive Rates ◽  
Successive Generations ◽  
Cheyletus Eruditus ◽  
Cryptolestes Turcicus

The duration and mortality of immature stages of the predatory mite Cheyletus eruditus (Schrank) were examined at 14, 18.5, 22, and 25 °C and 76% RH. Life tables and schedules of female eggs laid by each female per day were made from records of daily oviposition and adult mortality. The net reproductive rate (ratio of total female births in two successive generations) of C. eruditus varies from 40.7 at 18.5 °C to 74.4 at 25 °C and brackets the net reproductive rates of the prey Lepidoglyphus destructor (Schrank). Mean generation time and finite rates of increase (multiplication per female each day) varied from 52.2 days and 1.073 at 18.5 °C to 24.2 days and 1.194 at 25 °C. Maximum longevity was 107, 67, and 56 days at 18.5, 22, and 25 °C, respectively. Cheyletus eruditus also consumed first-instar larvae of the rusty grain beetle, Cryptolestes ferrugineus (Stephens), and first- and second-instar larvae of the flour mill beetle, Cryptolestes turcicus (Grouvelle).

Reproductive performance of ewe lambs: genetic correlation with weaning weight and subsequent reproductive performance

1976 ◽  
Vol 16 (80) ◽  
pp. 321 ◽  
Author(s):  
R Barlow ◽  
CJ Hodges
Keyword(s):  
Genetic Correlation ◽  
Reproductive Performance ◽  
Agricultural Research ◽  
Reproductive Rate ◽  
Research Station ◽  
Weaning Weight ◽  
Net Reproductive Rate ◽  
Ewe Lambs ◽  
Ewe Lamb ◽  
Selection For

The reproductive performance of Merino ewe lambs was examined in flocks with different selection histories for growth to weaning and net reproductive rate. These ewes were drawn from selection flocks maintained at the Agricultural Research Station, Trangie. There was evidence of a positive genetic correlation between weaning weight and reproductive performance of ewe lambs. Selection for weaning weight had a significant effect on the percentage of ewes lambing (P < 0.05). This appeared to be a function of a higher level of fertility (P <0.05) and a higher proportion of ewes mating (n.s.). The proportion of ewes apparently in oestrus during a 39 day teasing period, prior to joining, was significantly influenced by selection for weaning weight (P < 0.05). Simultaneous selection for increased net reproductive rate, weaning weight and clean fleece weight did not result in higher ewe lamb performance than that achieved by selection for increased weaning weight alone. No conclusion could be drawn from these data about the correlation between net reproductive rate and reproductive performance of ewe lambs.

The performance of the Border Leicester in Australia

2021 ◽  
Vol 61 (1) ◽  
pp. 1
Author(s):  
S. A. Barwick ◽  
D. J. Brown ◽  
B. R. Cullis ◽  
A. K. Bell ◽  
T. J. May ◽  
...  
Keyword(s):  
Evaluation System ◽  
New South ◽  
New South Wales ◽  
Reproductive Rate ◽  
Multiple Births ◽  
Net Reproductive Rate ◽  
Average Performance ◽  
Genetic Base ◽  
South Wales ◽  
Selection For

Aims We examine the average performance of Border Leicester (BL) flocks that are part of LAMBPLAN, Australia’s sheep performance recording and genetic evaluation system. We also summarise outcomes from the New South Wales Department of Primary Industry’s research on BL improvement, and discuss the performance required for the BL to continue to be a pivotal part of the Australian prime lamb industry. Key results Modest gains have been recorded in the BL in growth since 2000 and faecal egg counts have reduced, suggesting improved worm resistance. The net reproductive rate has slightly improved, while inbreeding continues to increase. In work conducted by the New South Wales Department of Primary Industries, an improved BL flock, encompassing selection for multiple births and a broadening of the breed’s genetic base, had advantages over purebred BLs in many aspects of performance, including a 19.3% advantage in the net reproductive rate. Advantages in fertility were ~5%, litter size ~7% and lamb rearing ability ~5%. BL improved × Merino and (BL improved × BL) × Merino crossbred ewes also had advantages over traditional BL × Merino ewes in their joining performance when joined to Dorset rams. Conclusions Selection in the BL needs to emphasise traits in a manner consistent with their importance to commercial lamb production. Implications Embracing this selection and broadening the BL’s genetic base will assist the BL to maintain its place in the Australian lamb industry.

Effects of vertebrate and invertebrate predators on the life history of Daphnia similis and Moina macrocopa (Crustacea: Cladocera)

2018 ◽  
Vol 54 ◽  
pp. 25 ◽  
Author(s):  
Jayme Magalhães Santangelo ◽  
Bruno Nascimento Soares ◽  
Thecia Paes ◽  
Paulina Maia-Barbosa ◽  
Ralph Tollrian ◽  
...  
Keyword(s):  
Life History ◽  
Reproductive Rate ◽  
Tropical Lakes ◽  
Net Reproductive Rate ◽  
Moina Macrocopa ◽  
Lake Ecosystems ◽  
Daphnia Similis ◽  
Invertebrate Predators ◽  
History Of ◽  
Reproductive Rates

Cladocerans serve as prey for several aquatic predators like fish and Chaoborus larvae. However, because different predators consume different sized prey, cladocerans may display differing life-history responses depending on predator type. Although most studies use the genus Daphnia to evaluate phenotypic plasticity in cladocerans, other genera might also respond to predator infochemicals. In this study, we compared life-history responses of Daphnia similis and Moina macrocopa to infochemicals released by a vertebrate (fish) and an invertebrate (Chaoborus) predator. As expected, some life-history parameters were altered depending on the type of predator. Overall, fish infochemicals increased the size at primipara, clutch size, net reproductive rate and longevity in both cladocerans. We argue that increased body lengths in the presence of fish promote bigger clutch sizes. Conversely, responses to Chaoborus were weaker, affecting only the net reproductive rates and longevity. Non-daphniid cladocerans may display similar responses to Daphnia when exposed to predators. However, as Daphnia is usually underrepresented in tropical lakes, studying other genera might offer new insights into predator-prey relationships and food webs in lake ecosystems.

Bionomics of Glycyphagus domesticus (de Geer) (Acarina: Glycyphagidae), a pest of stored grain

1968 ◽  
Vol 46 (1) ◽  
pp. 89-92 ◽  
Author(s):  
Philip S. Barker
Keyword(s):  
Life History ◽  
Relative Humidity ◽  
Rapid Development ◽  
Reproductive Rate ◽  
Optimum Temperature ◽  
Tyrophagus Putrescentiae ◽  
Stored Grain ◽  
Net Reproductive Rate ◽  
Different Temperatures ◽  
Reproductive Rates

The life history and reproductive rates of Glycyphagus domesticus (de Geer) were examined at different temperatures and two humidities. Most rapid development of the eggs occurred at 24.4 °C; the optimum temperature for the post-embryonic stages was 22.2 °C. A higher percentage of hypopi were formed at 70 to 75% than at 95 to 100% relative humidity. G. domesticus has a net reproductive rate of over 20, which was intermediate between those of Tyrophagus putrescentiae (Schrank) and Aëroglyphus robustus (Banks).

scholarly journals Comparative demography of the exotic Harmonia axyridis with other aphidophagous coccinellids reared on artificial diet

2014 ◽  
Vol 49 (1) ◽  
pp. 1-10 ◽  
Author(s):  
Julianne Milléo ◽  
Francisco Sales Fernandes ◽  
Wesley Augusto Conde Godoy
Keyword(s):  
Life Table ◽  
Harmonia Axyridis ◽  
Reproductive Rate ◽  
The Other ◽  
Adult Longevity ◽  
Net Reproductive Rate ◽  
Anagasta Kuehniella ◽  
Survival Percentage ◽  
Comparative Demography ◽  
Biological Aspects

The objective of this work was to compare biological aspects and life table parameters of the coccinellids Harmonia axyridis, Cycloneda sanguineaand Hippodamia convergens. Insects were fed eggs of Anagasta kuehniella, and reared at 24.5±1ºC, 70±10% relative humidity, with a 12 hour photophase. Hippodamia convergenstook about 1.6 day to complete development, longer than H. axyridis, and 2.4 day longer than C. sanguinea.At immature stages, H. axyridisexhibited the highest survival percentage (49.2%), in comparison to the other coccinellids. For mean adult longevity, H. convergenswas deficient, in comparison with the other species. Mean period of pre oviposition was the longest in C. sanguinea; the longest oviposition time occurred for H. axyridis; and the post oviposition period was similar between the coccinellids. Considering the reproductive parameters, H. axyridisshowed the best performance in all aspects. For life table, the values of H. convergenswere higher than, although close, to those of H. axyridis. Nevertheless, the high net reproductive rate of H. axyridis showed this species potential to increase population size. The biological characteristics of the exotic H. axyridis favors its invasion and establishment in Brazil, corroborating results noticed in other countries.

scholarly journals Contributions of source population and incubation temperature to phenotypic variation of hatchling Chinese skinks

2020 ◽  
Author(s):  
Hong-Liang Lu ◽  
Yan-Fu Qu ◽  
Hong Li ◽  
Xiang Ji
Keyword(s):  
Body Mass ◽  
Phenotypic Variation ◽  
Incubation Temperature ◽  
Tail Length ◽  
Population Variation ◽  
Phenotypic Traits ◽  
Source Population ◽  
Relative Importance ◽  
The Difference ◽  
Hatchling Size

Abstract Phenotypic plasticity and local adaptation are viewed as the main factors that result in between-population variation in phenotypic traits, but contributions of these factors to phenotypic variation vary between traits and between species and have only been explored in a few species of reptiles. Here, we incubated eggs of the Chinese skink (Plestiodon chinensis) from 7 geographically separated populations in Southeast China at 3 constant temperatures (24, 28, and 32 °C) to evaluate the combined effects of clutch origin, source population, and incubation temperature on hatchling traits. The relative importance of these factors varied between traits. Nearly all examined hatchling traits, including body mass, snout–vent length (SVL), tail length, head size, limb length, tympanum diameter, and locomotor speed, varied among populations and were affected by incubation temperature. Measures for hatchling size (body mass and SVL) varied considerably among clutches. Source population explained much of the variation in hatchling body mass, whereas incubation temperature explained much of the variation in other examined traits. Our results indicate that between-population variation in hatchling traits of P. chinensis likely reflects the difference in natural incubation conditions and genetic divergence.

scholarly journals Effects of Delayed Mating on the Reproductive Performance of Henosepilachna vigintioctopunctata (F.) (Coleoptera: Coccinellidae)

Insects ◽  
2021 ◽  
Vol 12 (7) ◽  
pp. 629
Author(s):  
Ya-Ling Wang ◽  
Qi-Nian Jin ◽  
Xiang-Ping Wang
Keyword(s):  
Life Table ◽  
Mating Success ◽  
Doubling Time ◽  
Reproductive Rate ◽  
Oviposition Period ◽  
Population Doubling ◽  
Life Table Parameters ◽  
Effective Measure ◽  
Net Reproductive Rate ◽  
Henosepilachna Vigintioctopunctata

Henosepilachna vigintioctopunctata (F.) is a serious pest of numerous solanaceous crops in many Asian countries. The purpose of this study was to clarify the effects of delayed mating on mating success, fecundity, fertility, pre-oviposition period, oviposition period, adult longevity, and population life table parameters (including net reproductive rate, intrinsic and finite rates of increase, doubling time, and mean generation time) of H. vigintioctopunctata. Beginning three days after emergence for both sexes, mating was delayed an additional 0, 2, 4, 6, or 8 days. We compared the data when mating was delayed for males only with the data when mating was similarly delayed for females only. Reproductive and life table parameters were calculated from the two data sets and compared. The results showed that the preoviposition and oviposition period of adults was significantly reduced by delayed mating, while the preoviposition period was not significantly different in adults mated at older ages. The mating success rate, fecundity, and proportion of hatching eggs decreased with increasing mating age. Longevity was not affected by the age at mating. Mating delay also affected the life table parameters of H. vigintioctopunctata, with a similar trend observed in the net reproductive rate and intrinsic and finite rates of increase, all of which decreased gradually as the number of delay days increased. The population doubling time increased with increases in mating age. The results also showed that delayed mating was an effective measure to consider in controlling H. vigintioctopunctata. It is hoped that our data will provide a scientific basis and contribute technical guidance for forecasting and integrated management of this pest.

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