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1.
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Albatrosses exhibit extremely low reproductive rates, each pair brooding only one egg and subsequent chick at a time. Furthermore, in several of the species, the majority of successful pairs breed only once every second year (termed 'biennial' breeding). Thus, on average, these latter species have an annual fecundity of about half an offspring per year, while other albatrosses produce an egg and chick every year. Using our 40-year bank of demographic data, we compared 12 species of albatrosses according to these two breeding strategies to examine potential causes of biennial breeding. Biennial breeding could be due to physiological constraints, larger animals breeding more slowly, or ecological constraints, more distant pelagic feeding trips being energetically costly, or both. We tested these hypotheses by looking for predicted associations between the duration of the rearing period, the distance to the oceanic feeding zone and breeding frequency. We also looked for associations of these variables with other life-history traits. Body size had a strong influence on the duration of the rearing period, but not on the distance that birds travelled to the feeding zone. Both the duration of the rearing period and distance to the feeding zone appeared to have direct influences on breeding frequency, as revealed by a path analysis, and thus both hypotheses to explain biennial breeding were supported. Finally, breeding frequency exhibited a strong trade-off with adult survival and age at maturity, indicating that slower breeders live through more breeding seasons, perhaps mitigating their lower annual reproductive output.  相似文献   

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Non-linear models were analysed to describe both the biological and commercial growth curves of the Segureña sheep, one of the most important Spanish breeds. We evaluated Brody, von Bertalanffy, Verhulst, logistic and Gompertz models, using historical data from the National Association of Segureña Sheep Breeders (ANCOS). These records were collected between 2000 and 2013, from a total of 129 610 weight observations ranging from birth to adulthood. The aim of this research was to establish the mathematical behaviour of body development throughout this breed’s commercial life (birth to slaughter) and biological life (birth to adulthood); comparison between both slopes gives important information regarding the best time for slaughter, informs dietary advice according to animals’ needs, permits economical predictions of productions and, by using the curve parameters as selection criteria, enables improvements in growth characteristics of the breed. Models were fitted according to the non-linear regression procedure of statistical package SPSS version19. Model parameters were estimated using the Levenberg–Marquardt algorithm. Candidate models were compared using the determinative coefficient, mean square error, number of iterations, Akaike information coefficient and biological coherence of the estimated parameters. The von Bertalanffy and logistic models were found to be best suited to the biological and commercial growth curves, respectively, for both sexes. The Brody equation was found to be unsuitable for studying the commercial growth curve. Differences between the parameters in both sexes indicate a strong impact of sexual dimorphism on growth. This can emphasize the value of the highest growth rate for females, indicating that they reach maturity earlier.  相似文献   

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RAPD analyses have been used to determine the genetic diversity and the population structure of the endangered Blanca Cacere?a bovine breed. Genetic variability was evaluated on the basis of 1048 loci produced by 71 primers. RAPD produced a number of polymorphic loci (30.44%), and it has been proved to be a useful method for evaluating polymorphisms in this breed. The dendrograms based on simililarity indexes and on Nei's genetic distances between 60 animals and the value of genetic differentiation among subpopulations (F(ST)) showed a clear population substructure defined by herds and a scarce genetic flow among herds. Analysis of molecular variance (AMOVA) showed that 32.4% of the total variance was due to differences among herds and confirmed the clustering found. The results of the present study allow us to plan more adequate mating in order to maintain the genetic diversity and to improve the efficiency of conservation for the Blanca Cacere?a bovine breed.  相似文献   

7.
The effects of the 1 29 translocation upon male fertility were studied by analysis of the results of 1 350 385 first artificial inseminations with the semen of Blonde d'Aquitaine or Coopelso-93 bulls (n=220). A binomial logit model was designed, taking into account the translocation of sire, breed of sire, breed of dam, year, AI center, and all interactions between translocation, and breed of sire, and breed of dam. Male fertility was not affected by the 1 29 translocation, and the nonreturn rates at 60 to 90 days of Blonde d'Aquitaine females inseminated with the semen of carrier bulls (135 632 first AI) or noncarrier bulls (585 949 first AI) were 74.88% and 74.75%, respectively.  相似文献   

8.
Urban areas expand worldwide, transforming landscapes and creating new challenging habitats. Some bird species, mainly omnivorous feeding on human waste and cavity nesters, commonly breed in these habitats and are, therefore, regarded as urban‐adapted. Although urban areas may provide new nesting sites and abundant human waste, the low breeding success found in some of these species suggests that the poor protein content in human waste might limit breeding parameters. We investigated whether the breeding success of a cavity nester and omnivorous species commonly breeding in urban areas, the Western Jackdaw (Corvus monedula), depended on the availability of good‐quality non‐urban food. We approached the objective by combining a literature review and experiments in the field. With the literature review, we compared jackdaw populations in different habitats across Europe and found that clutch size and number of fledglings per pair decreased with distance to non‐urban foraging grounds, even after controlling for the effect of colony size, latitude, and climate. In two experiments, we tested whether the breeding success of urban pairs could be increased by supplementing high‐quality food, first only during egg formation and second also until chick fledging. Food supplementation during egg formation led to larger eggs and higher hatching success than in urban control nests, but this did not result in higher chick survival. However, when food supplementation was prolonged until fledging in the second experiment, we observed a significant increase of nestling survival. These findings highlight that research and management actions should not only focus on species displaced by urbanization, but also on “urban‐adapted” species, as they might be suffering from a mismatch between availability of nesting sites in buildings and adequate non‐urban food resources. In these cases, nest sites should be provided in or close to adequate food resources.  相似文献   

9.
Two traditional sausage products (“salsiccia” and “salame”) processed from the raw meat of the Black Sicilian swine “Suino Nero dei Nebrodi” were microbiologically investigated during the manufacturing and ripening stages. Both products were dominated by lactic acid bacteria (LAB), especially rod-shaped types. The concentration of enterococci was consistent in salame. Coagulase-negative cocci increased slower than LAB. Yeasts showed an increasing trend during the ripening of both products. Enterobacteriaceae were counted at a constant level of about 105 CFU/g in both products, while pseudomonads diminished during ripening. Coagulase-positive staphylococci, Listeria monocytogenes and Salmonella spp. were not detected at the end of the ripening process. Characterisation of LAB at the strain and species level revealed that Lactococcus lactis was found only in the meat mixture, while Lactobacillus sakei and various enterococci persisted during the monitoring period. Some LAB strains isolated from sausages were also identified on the surface of the factory equipment. Two strains (Lactobacillus sakei SS106A and Enterococcus faecalis SS91) were characterised by their anti-Listeria properties due to bacteriocin-like inhibitory substance production. A multiple strain starter composed of Lactobacillus sakei and enterococci has been proposed to maintain the typical characteristics of the two fermented meat products microbiologically investigated in this study.  相似文献   

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  • 1.1. Fifteen populations of 10 horse breeds ranging from 110 to 2232 individuals yielded 61 phenotypes of electrophoretic variants at six blood loci.
  • 2.2. The numbers of different hemotypes varied from 79 to 239, and the ratios of number of individuals to number of hemotypes varied from 1.38 to 9.34.
  • 3.3. The genetic structure of the pooled mixed breed population comprising 11,393 individuals disclosed features similar to those of the least diversified component breeds.
  • 4.4. The mean ratio of n individuals to n hemotypes was 11.33.
  • 5.5. This figure represents a first direct attempt to estimate the individual genetic diversity in horses.
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12.
The dynamics of sperm DNA fragmentation (sDF) and sperm viability were analyzed in frozen-thawed sperm samples of Equus asinus (Zamorano-Leonés), a breed at risk of extinction. Sperm DNA fragmentation was assessed using an adaptation of the sperm chromatin dispersion test developed for stallions in five different frozen samples. Sperm were thawed and incubated at different temperatures (37 degrees C, 25 degrees C, and 4 degrees C) and sDF was assessed at different times and compared. The mean sDF after thawing at the beginning of the experiment was 18.20+/-14.77% and did not differ significantly from the results of a neutral comet assay (22.0+/-19.34%). The tendency in the sDF of all donkeys indicated that sperm DNA is more sensitive to breakage when incubated at 37 degrees C than when incubated at 25 degrees C or 4 degrees C. Interestingly, the tendency was not the same when different animals were compared, and differences in sDF dynamics were established among individuals. sDF correlated negatively with sperm viability in some individuals but not in others. From a conservation perspective, sDF analysis may offer a new way to assess sperm quality in endangered breeds in order to identify and select the best semen samples for artificial reproduction purposes. In particular, we recommend for artificial insemination the use of semen samples with a slow increase in sDF with time after thawing.  相似文献   

13.
Several hypotheses aim to explain the evolution of helping behavior,but conclusive experimental support for evaluating the relativeimportance of individual hypotheses is still lacking. We reporton two field experiments conducted to test the "territory inheritance"and "pay-to-stay" hypotheses in the cooperatively breeding cichlidfish Neolamprologus pulcher The territory inheritance hypothesiswas tested by removing one parent, which created breeding vacancies.In 39% of cases, same-sex helpers took over the breeding spot;in 44% of cases helpers continued helping new breeders, and17% were evicted by new breeders. Helpers that were closelysize matched to the removed breeder had a better chance of gainingthe breeding spot Male helpers tended to continue helping aftera takeover more often than females.The pay-to-stay hypothesiswas tested-by temporarily removing helpers. Whereas breedersdid not respond aggressively to removals, other group membersattacked the removed helpers on their return, and 29% were eventuallyevicted. The returning helpers assisted more by increasing theirrate of territory maintenance and defense and visiting the broodchamber more frequently Size and sex of removed helpers didnot explain the observed aggressive reactions of other groupmembers. Thus, our results support both hypotheses: N. pulcherneeds to pay with help to be allowed to remain protected inthe family group, and there they may inherit the natal territory.N. pulcher helpers gain direct benefits from helping behavior.  相似文献   

14.
Typical Near East mitochondrial haplotypes of the T2 lineage were found in one cattle metacarpus sample from the Roman period and in two present-day Evolène cattle in Switzerland. Sequences from eight additional Evolène and four Raetian Grey aligned to the European haplotype T3. Analysis of nucleotide diversity within the mitochondrial D-loop of both studied Swiss cattle breeds revealed high haplotype diversity and similar diversity to a European cattle reference group. Mitochondrial T3 haplotypes radiated star-like from two similarly frequent haplotypes, possibly indicating two different expansion routes. The breed structure of Evolène cattle can be explained either by an introduction of diverse female lineages from the domestication centre or by later admixture. The introduction of the Near East lineage to Switzerland must have happened during the Roman time or earlier.  相似文献   

15.
White Terns Gygis alba breed throughout the year on Aride Island but show a marked preference to nest during the northwest monsoon (November–March), when interspecific competition and also marine productivity are considered to be lower. In this study we investigated and compared breeding and foraging parameters of White Terns between the northwest and southeast (May–September) monsoons to assess whether interspecific competition affected foraging activity and explained the timing of breeding of White Terns. Goatfish (Mullidae) dominated the diet of White Terns and no significant differences were found in diet composition between the northwest and southeast monsoons. Similar diets and patterns of food provisioning of White Terns between the two monsoons do not support the hypothesis of strong exploitation competition during the southeast monsoon. On the other hand, foraging behaviour and frequency of capture attempts of White Terns differed between the two monsoons. The percentages of multi‐species flocks with White Terns and of large flocks with more than 25 noddies Anous and terns Onychoprion were significantly higher during the southeast monsoon. Moreover, capture attempt frequencies of White Terns foraging in multi‐species flocks were lower than those of solitary individuals, and both solitary and flocking White Terns had significantly lower capture attempt frequencies during the southeast monsoon in comparison with the northwest monsoon. These results suggest that interference competition depresses foraging activity of flock‐foraging White Terns, particularly during the southeast monsoon, which could potentially explain why White Terns breed preferentially during the northwest monsoon. However, and despite avoiding interference competition, White Terns nesting during the northwest monsoon did not show higher breeding success than those nesting during the southeast monsoon. Other hypotheses that might explain the preference of White Terns for breeding during the northwest monsoon, such as avoidance of agonistic interactions with Lesser Noddies Anous tenuirostris at nest sites, should also be investigated.  相似文献   

16.
Caprine-like Generalized Hypoplasia Syndrome (or SHGC) is a new hereditary disorder described in the Montbéliarde breed. We report here the characterization of this new disease, based on the visual examination of animals affected by SHGC, and on physiological and biochemical studies undertaken on samples of both SHGC and normal animals. Biological samples for more than 150 affected calves and their parents have been collected over the past 4 years within the framework of the Bovine Genetic Disease Observatory. First, pedigree analyses showed that the mode of inheritance is most probably autosomal recessive. Then, a genome scan with 113 animals and 140 microsatellite markers revealed a single locus within a 35-cM region on bovine chromosome 13. Genotypes of 261 animals for 18 new microsatellite markers from the region confirmed the localization of the disorder to a 6-cM interval. Finally, based on the analysis of haplotypes in 463 Montbéliarde sires, we estimated the frequency of the SHGC mutated allele in the population and could propose a strategy for the systematic eradication of this disorder in the near future.  相似文献   

17.
Crossbreeding of Holstein-Friesian dairy cows with both early maturing (e.g. Aberdeen Angus (AA)) and late maturing (e.g. Belgian Blue (BB)) beef breeds is commonly practised. In Ireland, genetic merit for growth rate of beef sires is expressed as expected progeny difference for carcass weight (EPD(CWT)). The objective of this study was to compare the progeny of Holstein-Friesian cows, sired by AA and BB bulls of low (L) and high (H) EPD(CWT) for performance and carcass traits. A total of 118 spring-born male progeny from 20 (9 AA and 11 BB) sires (8 L and 12 H) were managed together from shortly after birth to about 19 months of age. They were then assigned to one of two mean slaughter weights (560 kg (light) or 620 kg (heavy)). Following slaughter, carcasses were graded for conformation class and fat class, the 6th to 10th ribs joint was dissected as an indicator of carcass composition, and samples of subcutaneous fat and musculus longissimus were subjected to Hunterlab colour measurements. A sample of m. longissimus was also chemically analysed. Slaughter and carcass weights per day of age for AAL, AAH, BBL and BBH were 747, 789, 790 and 805 (s.e. 10.5) g, and 385, 411, 427 and 443 (s.e. 4.4) g, respectively. Corresponding carcass weight, kill-out proportion, carcass conformation class (scale 1 to 5) and carcass fat class (scale 1 to 5) values were 289, 312, 320 and 333 (s.e. 4.0) kg, 516, 522, 542 and 553 (s.e. 3.5) g/kg, 2.5, 2.4, 3.0 and 3.1 (s.e. 0.10), and 3.4, 3.5, 2.9 and 2.8 (s.e. 0.11). There were few breed type × genetic merit interactions. Delaying slaughter date increased slaughter weight, carcass weight and all measures of fatness. It also reduced the proportion of carcass weight in the hind quarter and the proportions of bone and muscle in the ribs joint. None of these effects accompanied the increase in carcass weight due to higher EPD(CWT). It is concluded that BB have superior production traits to AA. Selection of sires for higher EPD(CWT) increases growth rate, kill-out proportion and carcass weight of progeny with little effect on carcass or muscle traits. The extra carcass weight due to higher EPD(CWT) is more valuable commercially than a comparable carcass weight increment from a delay in slaughter date because it comprises a higher proportion of muscle.  相似文献   

18.
Many local livestock breeds in developing countries are being replaced by exotic breeds, leading to a loss of genetic resources. In southern Mali, for the past two decades, a trend towards increasing crossbreeding between the trypanotolerant N’Dama cattle and the trypano-susceptible Fulani Zebu cattle has been taking place. A survey with 160 farmers owning a cattle herd was carried out in southern Mali to investigate their production objectives, as well as trait and breed preferences and correlated socio-economic determinants in order to understand farmers’ breeding decisions and to identify comparative advantages of three breed groups (N’Dama, Fulani Zebu and crossbreds) raised in the study area. Data were analyzed using an exploded logit model. The reasons for raising cattle, as well as trait and breed preferences reflected the multiple objectives of the farmers. Draught power and savings were the most important production objectives. Productive traits were ranked highest; farmers reported large body size as the most preferred trait, followed by fertility, draught ability and milk yield. Crossbreds were the favored breed group. Breed preferences were mainly explained by ‘resistance to disease’ for N’Dama cattle and ‘high market price’ for Fulani Zebu and crossbred cattle. Production objectives, trait and breed preferences were mainly influenced by farmer group (local farmers and settled transhumants). Local farmers put comparatively more emphasis on livestock functions linked to crop production such as draught power. They had a higher preference for traction ability as a selection trait and preferred N’Dama over Fulani Zebu cattle. Settled transhumants emphasized milk yield as a selection trait and preferred Fulani Zebu over N’Dama. The results indicate that the trend towards more crossbreeding will continue putting the N’Dama breed under high risk of genetic dilution in southern Mali. The N’Dama cattle remain a valuable breed due to their adaptive traits such as disease and drought tolerance and their good traction ability, fulfilling the diverse objectives of local farmers. Crossbreeding was found to be a promising breeding strategy, which might contribute to the maintenance of the local breed, provided that breeding schemes are thoroughly planned and organized.  相似文献   

19.
Coat colours and patterns are highly variable in cats and are determined mainly by several genes with Mendelian inheritance. A 2‐bp deletion in agouti signalling protein (ASIP) is associated with melanism in domestic cats. Bengal cats are hybrids between domestic cats and Asian leopard cats (Prionailurus bengalensis), and the charcoal coat colouration/pattern in Bengals presents as a possible incomplete melanism. The complete coding region of ASIP was directly sequenced in Asian leopard, domestic and Bengal cats. Twenty‐seven variants were identified between domestic and leopard cats and were investigated in Bengals and Savannahs, a hybrid with servals (Leptailurus serval). The leopard cat ASIP haplotype was distinguished from domestic cat by four synonymous and four non‐synonymous exonic SNPs, as well as 19 intronic variants, including a 42‐bp deletion in intron 4. Fifty‐six of 64 reported charcoal cats were compound heterozygotes at ASIP, with leopard cat agouti (APbe) and domestic cat non‐agouti (a) haplotypes. Twenty‐four Bengals had an additional unique haplotype (A2) for exon 2 that was not identified in leopard cats, servals or jungle cats (Felis chaus). The compound heterozygote state suggests the leopard cat allele, in combination with the recessive non‐agouti allele, influences Bengal markings, producing a darker, yet not completely melanistic coat. This is the first validation of a leopard cat allele segregating in the Bengal breed and likely affecting their overall pelage phenotype. Genetic testing services need to be aware of the possible segregation of wild felid alleles in all assays performed on hybrid cats.  相似文献   

20.
The aim of this work was to sequence the promoter region of β-lactoglobulin (BLG) gene in four sheep breeds, in order to identify polymorphisms, infer and analyze haplotypes, and phylogenetic relationship among the Valle del Belice breed and the other three breeds considered as ancestors. Sequencing analysis and alignment of the obtained sequences showed the presence of 36 single nucleotide polymorphisms (SNPs) and one deletion. A total of 22 haplotypes found in “best” reconstruction were inferred considering the 37 polymorphic sites identified. Haplotypes were used for the reconstruction of a phylogenetic tree using the Neighbor-Joining algorithm. The number of polymorphisms identified showed high variability within breeds. Analysis of genetic diversity indexes showed that the Sarda breed presented the lowest nucleotide diversity, whereas the Comisana breed presented the highest one. Comparing the nucleotide diversity among breeds, the highest value was obtained between Valle del Belice and Pinzirita breeds, whereas the lowest one was between Valle del Belice and Sarda breeds. Considering that polymorphisms in the promoter region of BLG gene could have a functional role associated with milk composition, the lowest value of nucleotide diversity between Valle del Belice and Sarda breeds may be related to a higher similarity of milk composition of these two breeds compared to the others. Further analyses will be conducted in order to evaluate the possible correlation between the genetic diversity indexes and the BLG content in milk of our breeds.  相似文献   

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