Effects of temperature and lipid droplet adherence on mortality of hatchery-reared southern hake Merluccius australis larvae

Effects of exogenous (water temperature) and endogenous (lipid droplet adherence) factors were experimentally tested on early survival of southern hake Merluccius australis reared under controlled conditions. Experiments to determine the effect of temperature (10, 12 and 14 °C) on larval growth rates and yolk-sac absorption rates of unfed southern hake were carried out under laboratory conditions. There was no significant differences in growth rates at the temperature range tested (ANCOVA, F = 0.164, p > 0.25), but yolk-sac absorption rates and mortality increased with temperature (ANCOVA, F = 53.84, p < 0.001). A high percentage (between 31 and 81%) of hake eggs showed a lipid droplet not adhered (i.e., freely moving in the yolk, and not located in the posteriormost portion of the yolk-sac). In a second experiment, fed southern hake larvae with the lipid droplet not adhered during embryonic development did not survive after yolk-sac absorption. This study provides the first data on the influence of the lipid droplet absorption on larval survival of cultured hake, and can be used as an early indication of the quality of the batch.     

Adherence of Actinobacillus pleuropneumoniae serotype 1 to swine buccal epithelial cells involves fibronectin

The swine pathogen Actinobacillus pleuropneumoniae serotype 1 was investigated for its ability to adhere to swine, rat, and human buccal epithelial cells (BEC). The highest number of bacteria adhered was to swine BEC. This binding ability was affected by heating, extreme pH, treatment with sodium dodecyl sulfate, ethylenediamine tetraacetate, or periodate, and proteolysis, suggesting that cell-surface glycoproteins participate in adherence and that adherence is based mostly on ionic interactions. Mannose and swine fibronectin may play a direct role in this interaction. Convalescent-phase serum from naturally infected pigs inhibited the adhesion. There was a correlation between bacterial pathogenicity as well as host specificity and the capacity for adherence to swine BEC. Adhesion to swine BEC provides a convenient method to study in vitro the adherence of A. pleuropneumoniae and other pathogens of the pig respiratory tract.     

Analysis of world strains of Anaplasma marginale using major surface protein 1a repeat sequences

Anaplasma marginale is a tick-borne pathogen of cattle that causes the disease bovine anaplasmosis worldwide. Major surface proteins (MSPs) are involved in host-pathogen and tick-pathogen interactions and have been used as markers for the genetic characterization of A. marginale strains and phylogenetic studies. MSP1a is involved in the adhesion and transmission of A. marginale by ticks and varies among geographic strains in the number and sequence of amino-terminal tandem repeats. The aim of this study was to characterize the genetic diversity of A. marginale strains collected from countries in North and South America, Europe, Asia, Africa and Australia, inclusive of all continents. In this study, we characterized 131 strains of A. marginale using 79 MSP1a repeat sequences. These results corroborated the genetic heterogeneity of A. marginale strains in endemic regions worldwide. The phylogenetic analyses of MSP1a repeat sequences did not result in clusters according to the geographic origin of A. marginale strains but provided phylogeographic information. Seventy-eight percent of the MSP1a repeat sequences were present in strains from a single geographic region. Strong (> or =80%) support was found for clusters containing sequences from Italian, Spanish, Chinese, Argentinean and South American strains. The phylogenetic analyses of MSP1a repeat sequences suggested tick-pathogen co-evolution and provided evidence of multiple introductions of A. marginale strains from various geographic locations worldwide. These results contribute to the understanding of the genetic diversity and evolution of A. marginale and tick-pathogen interactions.     

Dietary inclusion of dehydrated bocaiuva pulp increases the antioxidant potential of quail eggs

The aim of this study was to evaluate dietary supplementation of different levels of dehydrated bocaiuva pulp (DBP) on the productive performance of laying quails, and on lipid oxidation, and quality in their eggs. A total of 120 quails were distributed in a completely randomized design with six treatments (0%, 0.1%, 0.2%, 0.3%, 0.4% and 0.5% of DBP), five replicates and four birds per experimental unit. To evaluate lipid oxidation, the eggs were collected on five consecutive days at the end of the trial and distributed in a completely randomized experimental design in a 6 × 5 factorial scheme (eggs from quails fed different levels of DBP × evaluated fresh and after 7, 14, 21 and 28 days). The antioxidant potential of diets was improved (p < 0.05) when the DBP was added estimated as 2,2'‐azinobis‐3‐ethylbenzothiazolin‐6‐sulfonic acid (ABTS) free radical scavenging capacity. No effect (p > 0.05) was observed on feed intake, hen‐day egg production and feed conversion (kg/kg and kg/dz). There were no changes (p > 0.05) in the egg weight, Haugh unit, yolk index or eggshell percentage. Although no difference was observed (p > 0.05), when comparing each level with the control, a negative linear effect (p < 0.05) on specific gravity was observed. In addition, only the treatment with 0.5% pulp exhibited lower (p < 0.05) eggshell thickness compared with the control (0%). Thiobarbituric acid reactive substances (TBARS) analysis showed that as the dietary pulp level was increased, malondialdehyde content decreased linearly (p < 0.05) in the egg yolks, regardless of the storage period. Inclusion of DBP in the diets had no effect (p > 0.05) on the concentration of conjugated dienes in the eggs. The diets containing DBP showed a potential antioxidant effect, reducing the degree of lipid oxidation in egg yolk. However, no beneficial effects were observed on performance and egg quality.     

Breeding objectives of Brangus cattle in Brazil

Our goal was to define a breeding objective for Brangus beef cattle in Brazil. Bioeconomic models were produced and used to estimate economic values (EVs). The scenarios simulated were typical full-cycle beef production systems that are used in tropical and subtropical regions. The breeding objective contained pregnancy rate (PR), warm carcass weight (WCW), mature cow weight (MCW), number of nematode eggs per gram of faeces (EPG) and tick count (TICK). Two models were used in series to estimate the EV. A deterministic model was used to simulate effects of PR, WCW and MCW on profitability with a constant parasite load. Subsequently, stochastic models were used to estimate economic values for TICK and EPG as consequences of their environmental effects on weight gains, mortality and health costs. The EV of PR, WCW, MCW, EPG and TICK, was US$1.59, US$2.11, −US$0.24, −US$5.35 and −US$20.88, respectively. Results indicate positive emphasis should be placed on PR (12.49%) and WCW (65.07%) with negative emphasis on MCW (13.92%), EPG (2.77%) and TICK (5.75%). In comparison with the indexes usually used, these results suggest a reformulation in the selection indexes of the beef production system in tropical and subtropical regions in order to obtain greater profitability.     

A logistic analysis of the factors determining the decision of smallholder farmers to intercrop: A case study involving rubber–tea intercropping in Sri Lanka

The factors influencing the decision of smallholder farmers to adopt new farming technologies were studied with reference to rubber–tea intercropping in Sri Lanka. Rubber–tea intercropping has been recommended previously to rubber farmers as a means to improve productivity and income during the early pre-tapping phase of rubber growth. Although crop trials have shown that the two crops are agronomically compatible and potentially produce a combined economic yield superior to the yield of a sole crop grown on the same area of land, there is little evidence of widespread adoption of this practice among smallholder farmers in Sri Lanka. The aim of the study was to determine the major factors that influence the decision to undertake rubber–tea intercropping and to construct a predictive model that describes the likelihood of adoption of intercropping by traditional smallholder rubber growers. A rapid rural appraisal (RRA) was undertaken based on semi-structured interviews of 90 smallholder farmers in the main rubber growing low wet zone of Sri Lanka. Among a number of factors shown to significantly influence the decision to intercrop tea with rubber, three were shown to operate independently, namely level of income, source of income (i.e. solely from own farm or from farm plus additional off-farm enterprises), and availability of land considered suitable for tea cultivation. A statistical model developed through correlation and logistic analysis, which predicts the likelihood of a smallholder adopting intercropping based on these factors, is presented and discussed. The most likely combination of circumstances (82% probability) under which rubber–tea intercropping is practiced is shown to be where the farmer’s income is greater than Rs. 10,000 per month, where the farmer’s income is based solely on own farm enterprises, and where more than 80% of the farmer’s land area was judged to be suitable for tea cultivation. Conversely, 30% of smallholder farmers that chose not to intercrop did possess land suitable for tea cultivation. Qualitative responses to the RRA indicated that limitation of technical knowledge was the main problem subsequently faced by rubber farmers who had adopted rubber–tea intercropping. Results indicate that there is need for both income support through farm subsidies and further agricultural extension services, if rubber–tea intercropping is to be adopted more widely in Sri Lanka. The wider usefulness of the developed logistic model in determining the likelihood of adoption of intercropping by smallholder farmers is discussed.     

Estimation of Milk Production in Lactating Sows by Determination of Deuterated Water Turnover in Three Piglets per Litter

The milk intake in piglets from four lactating sows was measured in three 48 h periods, starting on days 3, 10 and 17 of lactation, using the deuterium oxide (D 2 O) dilution technique. The milk intake was estimated from the water turnover in the piglets corrected for the production of metabolic water. The water turnover was estimated from the water dilution space and the fractional turnover of body water, determined by the rate of D 2 O dilution. To determine the magnitude of isotopic recycling, a randomly selected piglet in each litter was not enriched with D 2 O. Milk production of the four lactating sows was also measured by the weigh-suckle-weigh (WSW) method on days 4, 11 and 18 of lactation. The average daily milk production determined by the D 2 O dilution technique (9.91 - 0.69 kg) was higher ( P <0.05) than that determined by the uncorrected WSW method (8.65 - 0.81 kg). Different procedures for selecting piglets were evaluated to obtain the best possible estimation of total milk production from three piglets in each litter. The total milk production of a sow based on three piglets in the litter was obtained from a quadratic model of the relationship between milk intake and daily gain. When the daily gain of all piglets were known the Pearson correlation between milk production determined for the whole litter ( n -1) and only three median piglets was 0.98.