Evaluation of sheep genetic resources in North America: Lamb productivity of purebred, crossbred and synthetic populations

2008 ◽  
Vol 88 (3) ◽  
pp. 391-398 ◽  
Author(s):  
J. N. B. Shrestha ◽  
W. J. Boylan ◽  
W. E. Rempel
Keyword(s):  
North America ◽  
Genetic Resources ◽  
Key Words ◽  
North American ◽  
Reciprocal Crosses ◽  
Key Words Growth ◽  
Genetic Types ◽  
Synthetic Populations ◽  
Breed Crosses

Lamb weights and daily gains from divergent genetic types of established purebreds, e.g., Dorset (D), Lincoln (L), Rambouillet (Ra), Suffolk (Su) and Targhee (T), and fecund-type breeds, e.g., Finnsheep (F) and Romanov (Ro), their reciprocal crosses and Suffolk sired specific cross Su(F × Ro) were evaluated. Also evaluated were lambs of the Outaouais (O) and Rideau (R) Arcott breeds and their reciprocal crosses, in addition to Synthetic I (½ F, ½ L), Synthetic II (½ D, ½ Ra) and Synthetic III (¼ F, ¼ L, ¼ D, ¼ Ra) populations. The established purebreds produced heavier lambs at birth and weaning, Arcott breed crosses gained weight more rapidly resulting in heavier lambs at 140 d, and fecund-type breeds produced lighter lambs (P < 0.05). In general, daily gains and lamb weights of all genetic types were similar, except that fecund-type breeds produced significantly lighter lambs. Lamb weights of T were most at birth, and Su at weaning and 140 d, while F lambs weighed the least (P < 0.05). Within established purebreds, Su weighed the most and D weighed the least, while L, Ra and T lambs were intermediate. Daily gains including weaning and 140-d weights of F and R cross lambs benefited from 7–9% heterosis, while the Arcott breed cross lambs not only benefited from 5–8% heterosis, but were comparable with Su lambs. At the same time, lamb performance of Su(F × Ro) was similar to the average of their parental breeds. Lambs of synthetic populations relative to the average of their respective parental breeds weighed 8–24% more at 140 d, suggesting heterosis retention. Key words: Growth, North American breeds, Finnsheep, Romanov, Arcotts, synthetic populations

Evaluation of sheep genetic resources in North America: Ewe productivity of purebred, crossbred and synthetic populations

2008 ◽  
Vol 88 (3) ◽  
pp. 399-408 ◽  
Author(s):  
J. N. B. Shrestha ◽  
W. J. Boylan ◽  
W. E. Rempel
Keyword(s):  
Genetic Variation ◽  
North America ◽  
Genetic Resources ◽  
Reproductive Performance ◽  
Poor Performance ◽  
Reciprocal Crosses ◽  
Genetic Types ◽  
Synthetic Populations ◽  
Lamb Survival ◽  
Fleece Weight

Ewe productivity from divergent genetic types of established purebreds e.g., Dorset (D), Lincoln (L), Rambouillet (Ra), Suffolk (Su) and Targhee (T); fecund-type breeds e.g., Finnsheep (F) and Romanov (Ro) breeds, and their reciprocal crosses; the Outaouais (O) and Rideau (R) Arcott breeds and their reciprocal crosses; and Synthetic I (½ F, ½ L), Synthetic II (½ D, ½ Ra) and Synthetic III (¼ F, ¼ L, ¼ D, ¼ Ra) populations were evaluated. Prolificacy, fecundity, ewe weight, grease fleece weight, wool grade, lamb survival and total lamb weights at birth, 30 d and 140 d per ewe lambing were considered jointly as a measure of ewe productivity. In general, fecund-type breed cross and Arcott breed cross were highest in productivity, the fecund-type breed, Arcott breed and synthetic populations were intermediate, in contrast the established breeds was lowest. Regardless of significantly heavier ewe and grease fleece weights, and superior wool grade of the established breeds, their poor performance can be attributed to lower prolificacy, fecundity and total lamb weights (P < 0.05). Within established breeds, the D, L, Ra and T breeds were comparable in productivity to the Su breed, but lower than the F breed (P < 0.05). The Ro breed surpassed the F breed because of significantly higher prolificacy and fecundity, and heavier ewe weight and total lamb weights, while grease fleece weight and wool grade were inconsistent. The F and Ro breeds were comparable to the Su breed despite significantly higher prolificacy and fecundity, in contrast to lighter ewe and grease fleece weights, lower wool grade, lamb survival, similar total lamb weights. Although the R breed produced significantly heavier grease fleece weight and total lamb weights than the O breed, both breeds were similar to the Su breed despite their significantly higher prolificacy and fecundity, in contrast to similar ewe weight, wool grade, lamb survival and total lamb weights, and lighter grease fleece weight. The O and R breeds were more productive than the F breed as a result of significantly heavier ewe weight, superior wool grade, higher lamb survival and heavier total lamb weights, despite their similar prolificacy, fecundity and grease fleece weight. Synthetic I and Synthetic III with Finnsheep lineage surpassed Synthetic II in productivity as a result of significantly higher prolificacy and fecundity, and heavier total lamb weights, despite similar ewe and grease fleece weights and inconsistent wool grade and lamb survival. At the same time, Synthetic I and Synthetic III were not only similar to the Su breed, but surpassed the F breed, whereas Synthetic II was similar to the Su breed and lower than the F breed. Finally, systematic crossbreeding and composite population of complementary fecund-type and established breeds achieved increased productivity from additive genetic variation and heterosis. Key words: Reproductive performance, ewe and grease fleece weights, total lamb weights, Arcotts, Finnsheep, Romanov, synthetic populations, established breeds

Pollen morphology and taxonomy in North American Labiatae

1992 ◽  
Vol 70 (5) ◽  
pp. 975-995 ◽  
Author(s):  
Marie Claude G. Trudel ◽  
J. K. Morton
Keyword(s):  
North America ◽  
Key Words ◽  
North American ◽  
Pollen Morphology ◽  
Taxonomic Character ◽  
The North ◽  
Primary Basis ◽  
Sem Studies

Pollen morphology is described and illustrated based on SEM studies of 118 species of Labiatae (Lamiaceae) native to North America. These include representatives of all the 36 native genera. Pollen in this family is subspheroidal and either tricolpate (subfamily Lamioideae) or hexacolpate (subfamily Nepetoideae). In most of the genera and species, the tectum is conspicuously perforated with or without a supratectal reticulum. A key to facilitate identification of the pollen of the North American Labiatae is provided. The value of pollen as a taxonomic character in this family is discussed. Pollen provides the primary basis for recognition of subfamilies in the Labiatae, but at the tribal level only the Ajugeae has distinctive pollen. Several genera, notably Collinsonia, Salvia, Teucrium, and Trichostema, have pollen that is very different from other genera in this study. At the infrageneric level pollen provides valuable taxonomic characters in several genera, notably Hyptis, Monardella, Salvia, Stachys, Teucrium, and Trichostema. Key words: Labiatae, Lamiaceae, pollen, SEM, North America.

scholarly journals Philosophy of Education in North America: Where has it been? Where is it going?

2008 ◽  
Vol 8 ◽  
Author(s):  
James Scott Johnston
Keyword(s):  
North America ◽  
Key Words ◽  
North American ◽  
Philosophy Of Education ◽  
Educational Practice ◽  
The North ◽  
Educational Theories

This paper examines the question of philosophy of education’s direction through an examination of its historical self-understandings. The North American, and particularly, U.S. context is highlighted. The thesis is that philosophy of education must reconstruct itself through attention to its past self-understandings, but most importantly, through acceptance of projects, issues, and topics that are relevant to it, and not simply to philosophy or educational practice. Some consequences of this thesis are presented at the end of the paper. Key words: philosophy of education; Dewey's influence; educational theories; historical self-understanding; pragmatism

Biogeographic relationships between the macrofungi of temperate eastern Asia and eastern North America

1997 ◽  
Vol 75 (12) ◽  
pp. 2108-2116 ◽  
Author(s):  
Qiuxin Wu ◽  
Gregory M. Mueller
Keyword(s):  
North America ◽  
Key Words ◽  
North American ◽  
Field Work ◽  
Disjunct Distribution ◽  
Eastern North America ◽  
Western North America ◽  
Eastern Asia ◽  
Key Words Biogeography

Eastern North America and temperate eastern Asia reportedly share a relatively high number of taxa of macrofungi (mushrooms and relatives), including a number of taxa that have putative eastern North America – temperate eastern Asia disjunct distributions. These reports have been used to imply an affinity between the mycota (fungal equivalent of flora and fauna) of the two regions. To date, however, this affinity has not been examined in detail. A comparison of north temperate macrofungal mycotas was undertaken to examine the similarity between these regions. We used two methods in this study: (i) direct comparison of taxon lists and (ii) calculation of the Simpson Coefficient of similarity from lists of selected taxa. These analyses were based on field work, herbarium records, and published taxonomic treatments for Amanita, Lactarius, Ramaria, and Boletaceae. Results of these analyses document that taxonomic similarity between eastern North America and temperate eastern Asia mycotas can be quite high. In all cases, the calculated similarity values for eastern North America – temperate eastern Asia comparisons are higher than those between either region of North America and Europe or between western North America and eastern Asia. Furthermore, the eastern North American and temperate eastern Asian disjunct distributions of macrofungi are usually limited to the level of species or lower. Key words: biogeography, China, disjunct distribution, macrofungi, North America, Simpson Coefficient.

Evaluation of sheep genetic resources in North America: Milk production and composition of purebred, crossbred and synthetic populations

2008 ◽  
Vol 88 (4) ◽  
pp. 569-576 ◽  
Author(s):  
J. N. B. Shrestha ◽  
W. J. Boylan ◽  
W. E. Rempel
Keyword(s):  
North America ◽  
Milk Production ◽  
Milk Yield ◽  
Sheep Breeds ◽  
Lactation Length ◽  
Genetic Types ◽  
Middle East Countries ◽  
Synthetic Populations ◽  
Sheep Production ◽  
Daily Milk Yield

Purebreds, crossbreds and synthetic populations of sheep in North America of divergent genetic types produced 47–103 litres of milk for 121–144 d, consistent with "non dairy-type" breeds; however, this was substantially less than the 200–330 kg of milk per lactation characteristic of "dairy" type breeds in Europe and the Middle East countries. Among established breeds, the Suffolk (Su) breed produced significantly more total and daily milk yield, respectively, for a longer lactation (79 litres and 589 mL for 139 d), followed by the Rambouillet (Ra), Targhee (T) and Dorset (D) breeds (60–62 litres and 422–542 mL for 120–132 d), while the Lincoln (L) breed produced significantly less (48 litres and 285 mL for 128 d). Among fecund-type breeds and their crosses, Finnsheep (F) and Romanov (Ro) breeds produced significantly less (50–55 litres and 425–463 mL, for 122–129 d), while Ro × F produced significantly more milk (91 litres and 744 mL for 126 d), followed by F × Ro (60 litres and 505 mL for 128 d). Among other crossbreds, F × Ra produced significantly more milk (66 litres and 434 mL for 136 d) followed by L × Ra, L × D, F × L, F × Ra (49–60 litres and 296–385 mL for 123–136 d), while Ra × D produced significantly less (47 litres and 245 mL for 121 d). Among multiple breed composite populations, the Outaouais (O) and Rideau (R) Arcott breeds and their crosses had the highest milk production, e.g., R and R × O produced significantly more milk (95–103 litres and 754–820 mL for 131–144 d) than O and O × R (74–80 litres and 621–693 mL for 124–142 d). Concurrently, Synthetic I (½ F, ½ L) produced significantly less (58 litres and 494 mL for 134 d), while Synthetic III (¼ F, ¼ L, ¼ D, ¼ Ra) produced significantly more milk (91 litres and 673 mL, P > 0.05, for 130 d), and Synthetic II (½ D, ½ Ra) was intermediate (74.8 litres and 621 mL for 129 d); however, lactation length was consistent. Sheep breeds in North America exhibited diversity that was substantial for milk yield, but negligible for lactation length, as well as fat, protein, lactose and solid-not-fat content. Lack of inherent potential for milk production continues to be a serious constraint towards development of commercial dairy sheep industry. In the absence of "dairy-type" breeds, superior milk production in the Rideau Arcott breed (with East Friesian lineage) and their crosses demonstrates considerable promise for further improvement, thus increasing the efficiency of sheep production. Key words: Milk yield and composition, sheep breeds, synthetic sheep, Arcott breeds

Studies in the lichen genus Ochrolechia. 2. Corticolous species of North America

1991 ◽  
Vol 69 (4) ◽  
pp. 733-772 ◽  
Author(s):  
Irwin M. Brodo
Keyword(s):  
North America ◽  
Key Words ◽  
North American ◽  
Distribution Maps ◽  
The North ◽  
Group 5 ◽  
Crustose Lichens ◽  
First Time

Ochrolechia, a widespread genus of crustose lichens, includes 19 species growing on bark in North America. These corticolous species and several non-North American taxa are treated in this paper. Six species and one variety are described as new: O. antillarum, O. gowardii, O. montana, O. juvenalis, O. pseudopallescens, O. subisidiata, and O. trochophora var. pruinirosella. Two species are reduced to synonymy (O. californica Vers, and O. sorediosa Howard); six species are excluded from the North American flora (O. alboflavescens (Wulf.) Zahlbr., O. apiculata Vers., O. pallescens (L.) Massal., O. parella (L.) Massal., O. rhamni-purshianae Senft, O. subviridis (Höeg) Erichsen, and O. turneri (Sm.) Hasselrot). Several synonymies mentioned in the literature are confirmed (O. trochophora (Vainio) Oshio including O. rosella (Tuck.) Vers. and O. orientalis Vainio; O. androgyna (Hoffm.) Arn. including O. pergranulosa (Räs.) Vers, and O. mahluensis Räs.; and O. yasudae Vainio including O. tuckermanii Vers, and O. pennsylvanica Vers.). A key for the determination of all the species treated is presented together with distribution maps and a summary of the chemistry of the group. 5-O-Methylhiascic and 4,5-di-O-methylhiascic acids are reported from Ochrolechia for the first time. Key words: Ochrolechia, Ascomycotina, Pertusariaceae.

Key and synopsis of North American Hordeum species

1990 ◽  
Vol 68 (11) ◽  
pp. 2433-2442 ◽  
Author(s):  
Bernard R. Baum ◽  
L. Grant Bailey
Keyword(s):  
North America ◽  
Key Words ◽  
North American ◽  
Identification Key ◽  
Key To Species ◽  
Hordeum Species

A key to the species of Hordeum in North America is provided. Accompanying the key to Hordeum are accounts of species with the correct name, pertinent synonyms, common names, citations of major works, and notes on taxonomy, habitats, distribution, and variation. Photographs of inflorescences and illustrations of triads of spikelets are provided to facilitate identification. Key words: Hordeum, key to species, North America.

Limited taxonomic value of palea intercostal characteristics in North American Festuca (Poaceae)

1993 ◽  
Vol 71 (12) ◽  
pp. 1651-1659 ◽  
Author(s):  
L. L. Consaul ◽  
S. G. Aiken
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
North America ◽  
Key Words ◽  
North American ◽  
Apical Region ◽  
Key To Species ◽  
Species Groups ◽  
Epidermal Features ◽  
Scanning Electron

Morphology of the intercostal palea region of 34 Festuca species found in North America was investigated using scanning electron microscopy. Palea epidermal features are most diverse in the palea apical region and fully developed in florets approaching anthesis. The intercostal region has long cells 3–15 times longer than wide, with walls that vary from slightly to prominently thickened, and from almost straight to strongly undulate. This variation was observed among paleas collected from different locations and sometimes even on a single palea. The distribution of short cells, almost square in outline, among the long cells varied with species from solitary to paired and from abundant to sparse. Four forms of trichomes were recorded: papillae, hook trichomes, prickle hairs, and macrohairs, with one form usually predominating per species. Silicon was detected in some short cells and commonly in the tips of trichomes. A key to species groups is presented. Key words: scanning electron microscopy, palea, trichomes, silicon, epidermal features, Festuca.

Artificial Hybrids Between Amur Pike, Esox reicherti, and North American Esocids

1977 ◽  
Vol 34 (12) ◽  
pp. 2338-2343 ◽  
Author(s):  
E. J. Crossman ◽  
James W. Meade
Keyword(s):  
North America ◽  
Key Words ◽  
North American ◽  
Inverse Relationship ◽  
Maximum Size ◽  
Parent Species ◽  
Esox Masquinongy ◽  
The Family ◽  
The Difference ◽  
Potential Maximum

Artificial hybrids between Esox reicherti, the only species in the family Esocidae that does not occur naturally in North America, and North American esocids were developed. Five of a possible 10 crosses are described in detail. Three crosses failed (those involving the males of E. niger and E. americanus) for reasons other than methodology, the cross involving females of E. americanus americanus was not made, and a fifth cross involving the male of E. masquinongy was successful but no data are included. Interspecies fertility was suprisingly high, and an inverse relationship existed between survival of crosses and the difference in potential maximum size of parent species. At least one cross was fertile, and an F2 generation and backcrosses were developed. Key words: artificial hybrids. Esocidae, Esox reicherti, Esox masquinongy, Esox lucius, Esox niger, Esox americanus

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