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Effects of the level of early productivity on the lifespan of ewes in contrasting flock environments
《Animal : an international journal of animal bioscience》2016,10(12):2034-2042
Selection for high levels of prolificacy has allowed substantial improvements in the production efficiency of New Zealand (NZ) sheep farms, but the consequences on ewe lifetime performance are mostly unknown. In this study, the relationship between the level of prolificacy early in ewes’ productive lives and their probability to survive later (i.e. stayability) was evaluated in two contrasting NZ flock environments. Records were obtained from 6605 ewes from four ram breeder flocks representing either a moderate (n=2) or a highly variable (n=2) nutritional environment. All ewes lambed for the first time at 2 years of age and were mated the following year. The number of lambs born during the first 2 years of productive life (NLB2–3) was used as a measure of early prolificacy. Effects of NLB2–3 on stayability to 4, 5, 6, 7 and 8 years old were analysed using logistic regression. Curvilinear effects (logit-transformed) were detected (P<0.05) until stayability to 6 years and to 8 years old in the highly variable and the moderate environment, respectively. The NLB2–3 that resulted in maximum expected stayability to various ages was 3.9 to 4.2, and 4.5 to 4.7 lambs in the highly variable and in the moderate flock environments, respectively. In addition, ewe stayability was reduced when the proportion of the litter that survived from birth to weaning (i.e. ewe rearing ability) was submaximal during the early productive life. High prolific ewes had a low rearing ability whatever the environment whereas the rearing ability of lowly prolific ewes was apparently more sensitive to the nutritional environment. The poor maternal performance of ewes with low levels of NLB2–3 led to a premature culling by breeders whereas the high early reproductive effort associated with high levels of NLB2–3 seemed to be at the cost of ewes’ survival, even in the moderate flock environment. In conclusion, the flock environment influenced the level of early prolificacy beyond which ewe longevity was reduced. It is suggested that further selection for high and early prolificacy in NZ flocks is likely to impair ewes’ lifetime productivity. 相似文献
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Five popular but iron-inefficient cultivars were crossed with three efficient genotypes and both parents and F1s were evaluated for iron-efficiency in potted calcareous and noncalcareous soil. The iron-efficient genotypes were dark green or green in both noncalcareous and calcareous soils whereas inefficient types were light green to yellow in calcareous soil. The chlorophyll and active iron (Fe2+) concentration of leaves was less in iron-efficient genotypes compared to efficient types in calcareous soil and reduction of both the parameters from noncalcareous to calcareous soil was considerably high in iron-inefficient lines. There was significant correlation between visual scores, chlorophyll and active iron content. There were no differences among F1s for iron chlorosis and they were all iron-inefficient. The frequency of iron-inefficient plants was higher than the efficient plants in all F2 populations. But most of the productive plants came from iron-efficient segregants indicating strong association between iron-efficiency and productivity. Based on the results selection for iron-efficiency in early generations and extensive evaluation for productivity in advanced generations is suggested for developing varieties for cultivation in calcareous soils. 相似文献
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A. Vuillemin D. Ariztegui G. Nobbe C. J. Schubert the Pasado Science Team 《Geomicrobiology journal》2014,31(4):285-298
Methanogenic populations were investigated in subsaline Laguna Potrok Aike sediments, southern Argentina. Microbial density and activity were assessed via cell count and in situ ATP detection for the last ~11K years. Methanogen phylogenetics highlighted species stratification throughout depth, whereas CO2 reduction was the major pathway leading to methane production. Organic substrates, characterized using pore water analysis, bulk organic fractions and saturated fatty acids, showed a clear link between sediment colonization and initial organic sources. Concentrations and δ13C compositions of methane and fatty acids provided final evidence of a microbial imprint on Holocene organic proxies in the most colonized intervals. 相似文献
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SANDRINE LADEVÈZE 《Zoological Journal of the Linnean Society》2007,150(1):85-115
Metatherian petrosal bones were recovered from the early Late Palaeocene Itaboraí, Brazil, and are formally described. A cladistic analysis of the distribution of 56 petrosal and basicranial characters among extant and fossil metatherians was conducted, resulting in seven parsimonious trees. Relationships among metatherian ingroup taxa are congruent with current understanding of metatherian phylogeny. Metatheria is diagnosed by eight petrosal synapomorphies: stapedial artery absent in adults; reduced, intramural prootic canal; extrabullar internal carotid artery; inferior petrosal sinus between petrosal, basisphenoid, and basioccipital; cava supracochleare and epiptericum completely separated; reduction of the lateral flange; reduction of the anterior lamina; separation of the jugular foramen from the opening for the inferior petrosal sinus. The Palaeocene taxa Mayulestes , Pucadelphy s, and Andinodelphys from Tiupampa, and Petrosal Type II from Itaboraí are the sister groups of all other South American and Australian metatherians. This analysis confirms previous results showing the South American 'monito del monte' Dromiciops nested within the Australasian radiation. Within this australidelphian clade, Dromiciops is closely related to the dasyurids. The South American Caenolestes appears more closely related to the Australidelphia than to the South American didelphids. The Petrosal Types I, III, IV and V from Itaboraí are the stem taxa of the clade Australidelphia plus Caenolestes . The significant synapomorphies supporting this relationship are: enlargement of the fossa subarcuata that produces a bulbous ventral aspect of the mastoid and loss of post-temporal canal. Journal compilation © 2007 The Linnean Society of London, Zoological Journal of the Linnean Society , 2007, 150 , 85–115. No claim to original French government works. 相似文献
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Inhibited growth of common enteropathogenic bacteria in lactic-fermented cereal gruels 总被引:5,自引:0,他引:5
U. Svanberg E. Sjögren W. Lorri A. -M. Svennerholm B. Kaijser 《World journal of microbiology & biotechnology》1992,8(6):601-606
A natural lactic fermentation of mixtures of water and whole flour of either maize or high-tannin sorghum was obtained either before or after cooking to a weaning gruel: The preparations had a final pH of about 3.8 (range 3.67 to 4.00) and a ratio of lactic acid to acetic acid of 91 (w/w). The growth of added (about 107 c.f.u./g gruel) Gram-negative intestinal pathogenic bacteria, enterotoxigenicEscherichia coli, Campylobacter jejuni, Shigella flexneri andSalmonella typhimurium, was strongly inhibited in the sour gruels, and the effect could primarily be explained by the low pH caused by the formation of lactic and acetic acids during the fermentation process. Of the added Gram-positive bacteria,Bacillus cereus andStaphylococcus aureus showed similar inhibited growth up to 7h after inoculation in the sour gruels. The strain ofStaphylococcus, however, showed only a continued reduction in growth in the fermented gruel samples, which had a viable lactic bacteria culture indicating the presence of a bacteriocin. This implies that a low pH (< 4.0) alone is not sufficient to sustain the inhibition of the growth ofStaphylococcus aureus. The survival studies were carried out at optimal temperatures for each respective enteropathogen. 相似文献
10.
After an observed estrus, 250 dairy heifers were injected once with 25 mg of PGF(2alpha) either on cycle days 5 through 7 (E), 8 through 11 (M) or 12 through 15 (L). For five days after the PGF(2alpha) injection, heifers were inseminated at about 12 h after estrus was first observed. Observed estrual response rates were 43.0%, 83.6% and 100% for E, M and L, respectively. Average time from PGF(2alpha) to observation of estrus for E, M and L was 59, 70 and 72 h. Conception rates for heifers responding to PGF(2alpha) were 56.8%, 62.1% and 78.3% for E, M and L, respectively. Based on blood samples drawn at the time of PGF(2alpha) injection, progesterone concentration was significantly correlated with response rate but not with conception rate. When compared with M and L, E had a significantly lower response rate and conception rate as well as a shorter period between injection of PGF(2alpha) and observation of estrus. 相似文献