Fertility-associated antigen on Nelore bull sperm and reproductive outcomes following first-service fixed-time AI of Nelore cows and heifers

The objective was to determine whether the presence of fertility-associated antigen (FAA) on sperm collected from Nelore (Bos indicus) bulls can be used to assess potential fertility of sperm for use at first-service fixed-time AI (TAI). Six Nelore bulls were selected based on FAA status (FAA-negative: N = 3; FAA-positive: N = 3) and the ability to produce neat semen with ≥ 70% morphologically normal sperm and 60% estimated progressive motility before cryopreservation. In Experiment 1, suckled multiparous Nelore cows (N = 835) were evaluated for body condition score (BCS) and received an intravaginal progesterone device (CIDR) and 2.0 mg of estradiol benzoate (Day 0). On Day 9 the CIDR was removed, 12.5 mg of PGF_2α and 0.5 mg of estradiol cypionate were administered, and calves were removed for 48 h. All cows received TAI on Day 11 (48 h after CIDR removal). Pregnancy per TAI (P/TAI) was not different between FAA-positive and FAA-negative bulls (41.5% vs. 39.3%, respectively). There was an effect of AI technician on P/TAI (36.0% vs. 43.9%; P < 0.05) and BCS tended to affect P/TAI (P = 0.09), as cows with BCS ≥ 2.75 were 1.4 times more likely to become pregnant compared with cows with BCS < 2.75. In Experiment 2, nulliparous Nelore heifers (N = 617) were evaluated for BCS and received a CIDR and estradiol benzoate (2.0 mg) on Day 0. On Day 7, all heifers received PGF_2α (12.5 mg). On Day 9, CIDR inserts were removed and all heifers received estradiol cypionate (0.6 mg) and 200 IU eCG. All heifers received TAI on Day 11 (48 h after CIDR removal). Pregnancy/TAI was different (P = 0.04) between FAA-positive and FAA-negative bulls (33.7% vs. 40.7%, respectively). Presence of FAA on sperm was unsuccessful in assessing the potential fertility of sperm for use in TAI.     

Effect of progesterone concentrations,follicle diameter,timing of artificial insemination,and ovulatory stimulus on pregnancy rate to synchronized artificial insemination in postpubertal Nellore heifers

Two experiments were designed to evaluate the effects of treatments with low versus high serum progesterone (P₄) concentrations on factors associated with pregnancy success in postpubertal Nellore heifers submitted to either conventional or fixed timed artificial insemination (FTAI). Heifers were synchronized with a new controlled internal drug release device (CIDR; 1.9 g of P₄ [CIDR1]) or a CIDR previously used for 18 days (CIDR3) plus 2 mg of estradiol (E₂) benzoate on Day 0 and 12.5 mg of prostaglandin F2α on Day 7. In experiment 1 (n = 723), CIDR were removed on Day 7 or 9 and heifers were inseminated after estrus detection. In experiment 2 (n = 1083), CIDR were all removed on Day 9 and FTAI was performed either 48 hours later in heifers that received E₂ cypionate (ECP) on Day 9 (0.5 mg; E48) or 54 or 72 hours later in conjunction with administration of GnRH (100 μg; G54 or G72). Synchronization with CIDR1 resulted in greater serum P₄ concentrations and smaller follicle diameters on Days 7 and 9 in both experiments. In experiment 1, treatment with CIDR for 9 days decreased the interval from CIDR removal to estrus (Day 7, 3.76 ± 0.08 days vs. Day 9, 2.90 ± 0.07; P < 0.01) and improved conception (Day 7, 57.1% vs. Day 9, 65.8%; P = 0.05) and pregnancy rates (Day 7, 37.6% vs. Day 9, 45.3%; P = 0.04). In experiment 2, treatment with ECP improved (P < 0.01) the proportion of heifers in estrus (E48, 40.9%^a; G54, 17.1%^c; and G72, 32.0%^b), but the pregnancy rate was not affected (P = 0.64) by treatments (E48, 38.8%; G54, 35.5%; G72, 37.5%). Synchronization with CIDR3 increased follicle diameter at FTAI (CIDR1, 11.07 ± 0.10 vs. CIDR3, 11.61 ± 0.10 mm; P < 0.01), ovulation rate (CIDR1, 82.8% vs. CIDR3, 88.0%; P < 0.01) and did not affect conception (CIDR1, 42.2 vs. CIDR3, 45.1%; P = 0.38) or pregnancy rates (CIDR1, 34.7 vs. CIDR3, 39.4%; P = 0.11). In conclusion, length of treatment with P₄ affected the fertility of heifers bred based on estrus detection. When the heifers were submitted to FTAI protocol, follicle diameter at FTAI (≤10.7 mm, 23.6%; 10.8–15.7 mm, 51.5%; ≥15.8 mm, 30.0%; P < 0.01) was the main factor that affected conception and pregnancy rates.     

Effect of interval from induction of puberty to initiation of a timed AI protocol on pregnancy rate in Nellore heifers

Prepubertal Bos indicus heifers (n = 774) were submitted to an E₂/P₄-based timed artificial insemination (TAI) protocol at three different intervals after induction of their pubertal ovulation by insertion of an intravaginal progesterone (P₄) device for 12 days. Heifers were randomly assigned to start the TAI protocol at 10 (group 10; n = 253), 12 (group 12; n = 265), or 14 (group 14; n = 256) days after the P₄ device was removed. The TAI protocol consisted of the following: insertion of intravaginal device containing P₄ (Controlled internal drug release [CIDR]; previously used twice for 9 days each) + estradiol benzoate (2 mg) on Day 0, CIDR withdrawal + estradiol cypionate (0.5 mg) and PGF2α (12.5 mg) on Day 9, and TAI on Day 11. A subgroup of heifers (n = 472) was evaluated by ultrasound on Days 9 and 11 to evaluate the ovaries and to determine P₄ concentrations on Day 9. On Day 9, more (P < 0.05) CLs were present, and follicular diameter was smaller (P < 0.05) for group 10 than for groups 12 and 14 (38.4%, 29.3%, and 23.3% with CL and 9.4 ± 0.1, 9.9 ± 0.1, and 9.8 ± 0.1 mm diameter, respectively), but P₄ concentrations did not differ (P > 0.1) between treatments (2.4 ± 0.06 ng/mL). Follicular diameter at TAI (11.08 ± 0.09 mm) and ovulation rate (88.4%) did not differ between treatments (P > 0.1). However, conception and pregnancy rates for all heifers were greater (P < 0.05) in group 12 (50.4% and 45.5%, respectively) than in group 10 (38.2% and 33.7%, respectively), with group 14 intermediate to other treatments (45.6% and 40.6%, respectively). The final pregnancy rate did not differ between treatments (80.9%). In conclusion, a 12-day interval from the end of the puberty induction protocol to the start of the TAI protocol resulted in greater conception and pregnancy rates in prepubertal Nellore heifers.     

Validation of Self-Reported Information on Dental Caries in a Birth Cohort at 18 Years of Age

Objective

Estimate the prevalence of dental caries based on clinical examinations and self-reports and compare differences in the prevalence and effect measures between the two methods among 18-year-olds belonging to a 1993 birth cohort in the city of Pelotas, Brazil.

Method

Data on self-reported caries, socio-demographic aspects and oral health behaviour were collected using a questionnaire administered to adolescents aged 18 years (n = 4041). Clinical caries was evaluated (n = 1014) by a dentist who had undergone training and calibration exercises. Prevalence rates of clinical and self-reported caries, sensitivity, specificity, positive and negative predictive values, absolute and relative bias, and inflation factors were calculated. Prevalence ratios of dental caries were estimated for each risk factor.

Results

The prevalence of clinical and self-reported caries (DMFT>1) was 66.5% (95%CI: 63.6%–69.3%) and 60.3% (95%CI: 58.8%–61.8%), respectively. Self-reports underestimated the prevalence of dental caries by 9.3% in comparison to clinical evaluations. The analysis of the validity of self-reports regarding the DMFT index indicated high sensitivity (81.8%; 95%CI: 78.7%–84.7%) and specificity (78.1%; 95%CI: 73.3%–82.4%) in relation to the gold standard (clinical evaluation). Both the clinical and self-reported evaluations were associated with gender, schooling and self-rated oral health. Clinical dental caries was associated with visits to the dentist in the previous year. Self-reported dental caries was associated with daily tooth brushing frequency.

Conclusions

Based on the present findings, self-reported information on dental caries using the DMFT index requires further studies prior to its use in the analysis of risk factors, but is valid for population-based health surveys with the aim of planning and monitoring oral health actions directed at adolescents.     

Physiological and production response of dairy goats bred in a tropical climate

The aim of this work was to determine the adaptability of Saanen and ½Saanen?×?½Anglo-Nubian (½S½AN) goats bred in tropical climates. The study included 30 goats, 15 Saanen and 15 ½S½AN. The data was collected during the rainy and dry seasons. During the whole experimental period, the environment variables were recorded, as well as rectal temperature (RT), superficial temperature (ST), respiratory rate (RR) and heart rate (HR) and milk production (MP). The adaptability coefficient (AC) was calculated for both genotypes. The averages were evaluated by ANOVA at 5 % probability. There was a genotype and period of year effect, as well as the interaction genotype?×?period of year. Pearson's simple correlation analysis was then carried out between milk production and physiological and environment variables. There was a statistical difference (p?p?p?相似文献   

Chromosomal location and distribution of As51 satellite DNA in five species of the genus Astyanax (Teleostei, Characidae, Incertae sedis)

Constitutive heterochromatin makes up a substantial portion of the genome of eukaryotes and is composed mainly of satellite DNA repeating sequences in tandem. Some satellite DNAs may have been derived from transposable elements. These repetitive sequences represent a highly dynamic component of rapid evolution in genomes. Among the genus Astyanax , the As51 satellite DNA is found in species that have large distal heterochromatic blocks, which may be considered as derived from a transposable DNA element. In the present study, As51 satellite DNA was mapped through in situ fluorescent hybridization in the chromosomes of five species of the genus. The possible roles of this type of saltatory DNA type in the genome of the species are discussed, along with its use for the phylogenetic grouping of the genus Astyanax , together with other shared chromosomal characters. However, the number of As51 clusters is presented as a homoplastic characteristic, thereby indicating evident genomic diversification of species with this type of DNA.     

Long-term persistence of midsized to large-bodied mammals in Amazonian landscapes under varying contexts of forest cover

Both forest fragmentation and overhunting have profound effects on the structure of large-vertebrate assemblages in neotropical forests. However, the long-term value of habitat fragments for forest mammals remains poorly understood and few regional scale studies have replicated sampling across spatially independent landscapes. Here, we assess the species occupancy and abundance of midsized to large-bodied mammals within three neighbouring Amazonian forest landscapes varying widely in extent of forest cover. One of these consisted of forest fragments surrounded by semi-natural scrub savannahs that had been occupied by paleoindian populations for at least 7,000 years, whereas forest cover in the other two landscapes was either variegated or continuous. Data on species occurrence and abundance from diurnal and nocturnal line-transect surveys and local interviews in each landscape were used to examine the effects of forest cover and hunting pressure on mammal persistence within forest patches. The extent of forest cover was a key determinant of species persistence across the three landscapes, but populations of large-bodied species were either reduced or driven to local extinction by hunting even in the most forested and least fragmented landscape. Many game and non-game species persisted in forest isolates, even though, individually, these were likely too small to support viable populations. This study indicates that even small, long-term forest fragments may retain significant conservation value if they can be managed within the context of enhanced connectivity across wider fragmented landscapes.     

Interspecific primate associations in Amazonian flooded and unflooded forests

Stable associations between two or more primate species are a prominent feature of neotropical forest vertebrate communities and many studies have addressed their prevalence, and their costs and benefits. However, little is known about the influence of different habitat types on the frequency, seasonality, and composition of mixed-species groups in Amazonian forest primates. Here we examine the features of interspecific primate groups in a large mosaic of flooded (várzea and igapó) and unflooded (terra firme) forest in central Amazonia. In total, 12 primate species occurred in the study area, nine of which were observed in mixed-species associations. Primates were more than twice as likely to form associations in várzea forest than in terra firme forest. Squirrel monkeys were most frequently found in mixed-species groups in all forest types, most commonly in association with brown capuchins. Another frequent member of interspecific associations was the buffy saki, which often formed mixed-species groups with tamarins or brown capuchins. There was no seasonality in the frequency of associations in terra firme forest whereas associations in várzea forest were twice as frequent during the late-dry and early-wet seasons than in the late-wet and early-dry seasons. Interspecific primate associations were common in all forest types, but the degrees to which different species associate varied between these environments. We suggest that the temporal variation of várzea forest associations is connected with seasonal changes in habitat structure and resource abundance. However, more work is needed to pinpoint the underlying causes of mixed-species associations in all forest types and their strong seasonality in várzea forest.     

Elephants versus butterflies: the ecological role of large herbivores in the evolutionary history of two tropical worlds

Aim Large herbivores have important effects upon Paleotropical ecosystems, but attain much lower biomass densities in the Neotropics. We assess how this difference in herbivore activity has generated different ecological and evolutionary trajectories in the New and Old World tropics. We also propose an explanation for how the greater biomass density in the Old World came about. Location Data were compiled primarily from moist tropical forests, although more of the relevant information to address most of our hypotheses was available from the mainland areas of Africa, Asia, and South America than elsewhere. Methods We gleaned data from published information and personal communication. We compared body masses and a variety of other types of information for the New‐ and Old‐World tropics. We proposed that interhemispheric differences exist in a variety of processes, including herbivory, frugivory, and flower visitation. We erected hypotheses and evaluated them qualitatively, and, when information was available, tested them using simple ratios of species in various taxonomic and trophic categories. To make the comparisons more meaningful, we specified appropriate data selection criteria. Results A general pattern of differences emerges from this review. Compared with Neotropical forests, the much greater biomass densities of large herbivores in Paleotropical forests are associated with a lesser diversity of small herbivores, different hunting methods used by indigenous humans, larger arboreal vertebrates, larger fruits, different patterns of fruit and flower dispersion in space and time, a lesser abundance of most types of reproductive plant parts, and other features. The existence of a species‐rich fauna of large herbivores in the pre‐Holocene Neotropical rain forest was not supported. Main conclusions The potential for large herbivores to cause functional differences between the New and Old World tropical forests has been virtually unexplored, despite the well‐known importance of large herbivores in the Old World tropics. The evaluations of our hypotheses suggest that the abundance of large herbivores in the Old World tropics has launched it onto a different evolutionary trajectory than that of the NewWorld tropics. The relevant evidence, although scanty, suggests that the interhemispheric ecological differences are not an artefact of recent megafaunal extinctions in the New World. Recent human activities have, however, reduced population sizes of large wild herbivores in the Old World, and increased population sizes of livestock. This has likely created a rather homogeneous, anthropogenic selection pressure that tends to erase the evolutionary differences between the two tropical worlds.