A restricted maximum likelihood analysis applied to an animal model showed no significant differences (P > 0.05) in pH value of the longissimus dorsi measured at 24 h post-mortem (pH24) between high and low lines of Large White pigs selected over 4 years for post-weaning growth rate on restricted feeding. Genetic and phenotypic correlations between pH24 and production and carcass traits were estimated using all performance testing records combined with the pH24 measurements (5.05–7.02) on slaughtered animals. The estimate of heritability for pH24 was moderate (0.29 ± 0.18). Genetic correlations between pH24 and production or carcass composition traits, except for ultrasonic backfat (UBF), were not significantly different from zero. UBF had a moderate, positive genetic correlation with pH24 (0.24 ± 0.33). These estimates of genetic correlations affirmed that selection for increased growth rate on restricted feeding is likely to result in limited changes in pH24 and pork quality since the selection does not put a high emphasis on reduced fatness. 相似文献
This investigation aims to classify, describe and evaluate the sustainability of dairy goat production systems (GPS) in South Spain Sierra de Cadiz. The research took place throughout 25 goat farms during the 2001–2002 campaigns, with the method posed by Masera et al. (1999) [Masera, O., Astier, M., S., López-Ridaura. 1999. Sustentabilidad y manejo de recursos naturales. El marco de evaluación MESMIS (Sustainability and natural resource management. The MESMIS evaluation framework). Mundi-Prensa, S.A., Gira, IE-UNAM, México. 109 pp.] and adapted to animal production systems, as the guideline and framework to evaluate sustainability.
The principal component, namely energy input from grazing (eigenvalue 1.329) which comprises the indicators total area per goat (factorial value 0.664) together with net energy obtained from grazing (factorial value 0.903) allowed to differentiate significantly between semi extensive (SES), semi intensive (SIS) and intensive (IS) goat production systems.
Intensification of the GPS tends to be inefficient, especially in terms of net margin per litre of milk produced (p < 0.05). A higher degree of adaptability of IS (64.8%) derives from a higher investment on new production strategies. Likewise, higher self-management capacity of SES (60.9%) fosters standards of productivity (76.0%) and stability (42.9%). The SIS presented the highest equity values (67.8%).
On the whole, sustainability of GPS tends to decrease as the degree of intensification increases: SES = 57.3%; SIS = 55.7% and IS = 53.1%. The reduction of the dependency on external input alongside with the optimization of natural resources management would surely improve the standard of sustainability. 相似文献
The entire genome of bacteriophage OP1, lytic for Xanthomonas oryzae pv. oryzae causing bacterial leaf blight of rice, and the partial genomes of related phages were sequenced and analyzed. The OP1 genome comprises double-stranded, 4785-bp long DNA with 51.1% G + C content. Fifty-nine open reading frames (ORFs) were detected.
ORF25 had similarity with the tail fiber gene of phages, whose product is related to host specificity. The ORF25 regions were
amplified from four host-range mutants (OP1h, OP1hC, OP1h2, and OP1h2C) by polymerase chain reaction, and their deduced amino acid sequences were compared. Three mutants (OP1hC, OP1h2, OP1h2C) had duplications of a small domain in the N-terminal portion, although there were slight differences in the position of the duplicated sequences. One mutant OP1h had substituted amino acids in the duplication region. New mutants isolated in the laboratory (OP1hC and OP1h2C from OP1 and OP1h2) acquired the ability to lyse strain N5874 belonging to phagovar (lysotype) C. However, they rapidly lost this lytic ability
when incubated with other phagovars. This loss was always accompanied by a loss of the characteristic repeats, suggesting
that the host range of OP1-related phages changed mainly through duplication and deletion of a small domain in ORF25.
The nucleotide sequence data reported are available in the DDBJ/EMBL/GenBank databases under the accession numbers AP008979,
AB214312 to AB214316 相似文献