Postmortem Biochemical and Microbiological Changes in Loricariid Catfish (Pterygoplichthys disjunctivus) Muscle During Ice Storage

ABSTRACT

Postmortem biochemical and microbiological changes in loricariid catfish (Pterygoplichthys disjunctivus) muscle were evaluated during ice storage for 20 days. Values of pH remained stable for 15 days (7.4 ± 0.2), and total volatile base-nitrogen (TVB-N) remained under acceptable limits throughout storage, with a final value of 25.2 ± 3.3 mg N/100 g muscle at Day 20. Adenosine-5´-triphosphate (ATP) and derivatives followed a postmortem degradation pattern similar to other species, with the K-value being the best freshness loss indicator. Biochemical and microbiological changes indicated that the shelf life of iced loricariid catfish muscle was 15 days under optimal (0°C) storage conditions.     

Utilization of carotenoids from various sources by rainbow trout: muscle colour,carotenoid digestibility and retention

Rainbow trout (Oncorhynchus mykiss) with a mean (sd) weight of 120 (2) g were fed diets supplemented with astaxanthin extracted from the yeast Phaffia rhodozyma (OY1 = 50 mg carotenoids kg^–1 feed, OY2 = 100 mg carotenoids kg^–1 feed), astaxanthin (AX = 100 mg astaxanthin kg^–1 feed) and canthaxanthin (CX = 100 mg canthaxanthin kg^–1 feed) for 4 weeks. Muscle analyses at the end of the experiment indicated a significantly higher carotenoid concentration in the AX group, while CX and OY1 groups were similar in spite of the differences in dietary concentration. The measure of total muscle colour difference (E^* _ab) between initial samples and 4 week ones was higher for the AX fish group but showed no significant difference between OY1, OY2, and CX. The hue and the reflectance ratio (R₆₅₀:R₅₁₀) of fish muscle increased in proportion to carotenoid intake. Digestibility (ADC) of yeast astaxanthin in OY1 and OY2 groups was significantly higher than that in the AX group. Canthaxanthin ADC was about one sixth of that of astaxanthin (AX group). Carotenoid retention in the muscle, expressed as a percentage of carotenoid intake, was higher for the AX group than that recorded for OY1 and OY2. According to ADC, carotenoid retention showed a marked lower value for the CX group. Muscle retentions were similar for astaxanthins from both sources.     

Elliptical selection experiment for the estimation of genetic parameters of the growth rate and feed conversion ratio in rabbits

Two elliptical selection experiments were performed in two contemporary sire lines of rabbits (C and R) in order to optimize the experimental design for estimating the genetic parameters of the growth rate (GR) and feed conversion ratio (FCR). Twelve males and 19 females from line C, and 13 males and 23 females from line R, were selected from an ellipse defined by a quadratic index based on these traits. Data from 160 rabbits of each of the parental generations of lines C and R and their offspring (275 and 266 animals, respectively) were used for the analysis. A Bayesian framework was adopted for inference. Marginal posterior distributions of the genetic parameters were obtained by Gibbs sampling. An animal model including batch, parity order, litter size, and common environmental litter effects was assumed. Posterior means (posterior standard deviations) for heritabilities of GR and FCR were estimated to be 0.31 (0.10) and 0.31 (0.10), respectively, in line C and 0.21 (0.08) and 0.25 (0.12) in line R. Posterior means of the proportion of the variance due to common litter environmental effects were 0.14 (0.06) and 0.21 (0.06) for GR and FCR, respectively, in line C and 0.17 (0.06) and 0.22 (0.06) in line R. Posterior means of genetic correlation between both traits were -0.49 (0.25) in line C and -0.47 (0.32) in line R, indicating that selection for GR was expected to result in a similar correlated response in FCR in both lines.     

Genetic parameters of fertility in two lines of rabbits with different reproductive potential

A Bayesian analysis with a threshold model was performed for fertility defined as a binary trait (1 = successful mating, 0 = unsuccessful mating) in two populations of rabbits of different reproductive potential and different genetic origin: Line P selected for litter size and Line C selected for growth rate. There were 20,793 records of natural mating (86.2% successful) in Line C between 1983 and 2003, and 17,548 records (80.5% successful) in Line P, between 1992 and 2003. Data related to 5,388 and 3,848 females and 1,021 and 685 males in Lines C and P, respectively. The pedigree included 6,409 and 4,533 individuals in Lines C and P, respectively. The binary response was modeled under a probit approach. The model for the latent variable included male and female additive genetic effects, male and female permanent environmental effects, and the year-season and physiological status of the female (nulliparous, multiparous lactating, or multiparous nonlactating) as systematic effects. Means (standard deviation in parentheses) of the estimated marginal posterior distribution (EMPD) of male heritability were 0.013 (0.006) and 0.010 (0.008) in Lines C and P, respectively, and those of EMPD of female heritability were 0.056 (0.013) and 0.062 (0.018) in Lines C and P, respectively. Means of the EMPD of the proportion of the phenotypic variance due to environmental male and female effects were, respectively, 0.031 (0.007) and 0.128 (0.018) in Line C and 0.053 (0.010) and 0.231 (0.024) in Line P. Means (standard deviations in parentheses) of the EMPD of genetic correlation between male and female fertility were 0.733 (0.197) in Line C and 0.434 (0.381) in Line P. The posterior distribution of genetic correlations presents a huge dispersion, and the estimates should be taken with caution because of the almost negligible estimate of the male genetic component. Results indicate that little genetic variation exists for female fertility, and practically none for male fertility. It would, therefore, be possible to improve reproductive performance by including female fertility in a breeding program, but response to selection would be very small.     

Xenotransplantation of goat ovary as an alternative to analyse follicles after vitrification

The aim of this study was to evaluate the caprine preantral follicles enclosed on vitrified/warmed ovarian cortex grafted to nude BALB/mice during 1 month. The ovarian cortex from goats was fragmented (3 × 3 × 0.5 mm) and divided into four groups: fresh control, vitrified control, fresh transplant and vitrified transplant. Follicular morphology, development and density, fibrosis as well as apoptosis, and tissue revascularization were evaluated. It was also observed a significant decrease in morphologically normal preantral (primordial, transition, primary and secondary) follicles in both vitrified control and vitrified transplant treatments when compared with both fresh control and fresh transplant. However, fresh control and fresh transplant exhibited a similar percentage of developing follicles. Additionally, Vitrified control showed a significant increase in developing follicles in comparison with both fresh control and fresh transplant. Follicular density significantly decreased in all treatments in comparison with fresh control. We observed high fibrosis in both fresh transplant and vitrified transplant. The mRNA expression of caspase 3 was lower in both fresh transplant and vitrified transplant in comparison with vitrified control. In conclusion, xenotransplantation is an excellent strategy to maintain normal preantral follicle morphology after vitrification/warming of goat ovarian tissue. Yet, in order to ensure the survival and development of these follicles, it is essential to improve the revascularization of the graft.     

A new integrated CFD modelling approach towards air-assisted orchard spraying. Part I. Model development and effect of wind speed and direction on sprayer airflow

The current trend in modelling flow phenomena within trees such as in orchards follows the assumption of the space occupied by the trees as a porous and horizontally homogeneous medium to avoid the flow details associated with the individual plants. This being sufficient at a larger field or regional scale much has to be done at a plant scale to analyse the flow details within the plant and its elements especially for sensitive agricultural operations such as spraying. This article presents an integrated 3D computational fluid dynamics (CFD) model of airflow from a two-fan air-assisted cross-flow orchard sprayer through non-leafed orchard pear trees of 3 m average height. In this model the effect of the solid part of the canopy on airflow was modelled by directly introducing the actual 3D architecture of the canopy into the CFD model. The effect of small canopy parts, such as very short and thin branches and flowers that were not incorporated in the geometrical model, on airflow was simulated by introducing source-sink terms in the Reynolds averaged Navier-Stokes (RANS) momentum and k-? turbulence equations in a sub-domain created around the branches. This model was implemented in a CFD code of ANSYS-CFX-11.0 (ANSYS, Inc., Canonsburg, PA, USA). In this work it was possible to link the real 3D architecture of pear canopy into a CFD code of CFX. The model was able to capture the local effects of the canopy and its parts on wind and sprayer airflow directly by inserting the tree structure into the model which gave realistic results. The model showed that within the injection region of the sprayer there was an average reduction of the jet velocity by 1 m s⁻¹ for a distance of 2.3 m from the sprayer outlet due to the presence of leafless pear canopy. This reduction was variable at different vertical positions due to the difference in the canopy density. Maximal effect of the canopy was observed in the middle height of the trees between 0.25 m and 2.5 m which is the denser region with a bunch of several branches. The maximum velocity difference observed between these two positions was 1.35 m s⁻¹ at 1.75 m height. Thus, regions of high and low air velocity zones of the sprayer due to the variable branch density of the pear tree were predicted. The effects of wind speed and direction on the air jet from the sprayer were investigated using the model. For a cross- (direction of 90°) wind speed of 5 m s⁻¹ there was about 2 m s⁻¹ reduction in the sprayer jet velocity at the jet centre and 0.5 m horizontal shift of the jet centre towards the wind direction. Generally there was a decrease in the jet velocity with increasing cross-wind and decreasing wind direction with respect to the jet direction.     

Impact of no-tillage agricultural systems on sediment yield in two large catchments in Southern Brazil

Purpose

The impact of agriculture on water resources has long been a problem associated with the formation of runoff, the siltation of lakes and reservoirs, and overall depletion of water quality. In Brazil, these problems are mainly related to soil degradation by water erosion. However, studies of catchment-scale erosion are still rare particularly in grain-producing regions which have adopted conservative tillage systems for soil protection. In order to contribute to a better understanding of the impact of conservation agriculture on water resources, this study determined the runoff coefficient and sediment yield for two agricultural catchments.

Materials and methods

Hydrological and sedimentological monitoring was conducted in two catchments: the Conceicao catchment is characterized by grain production in weathered soils and a gently sloping landscape, while the Guapore catchment is characterized by heterogeneous soils and topography. Both catchments have problems associated with water erosion.

Results and discussion

The magnitudes of annual runoff coefficients and sediment yield were high, even if compared to similar agricultural regions, including a catchment with widespread adoption of no-tillage. The sediment yield was 140 t km^?2 year^?1, and the runoff coefficient was 14 % for the Conceicao catchment, while the sediment yield was 270 t km^?2 year^?1, and the runoff coefficient was 31 % for the Guapore catchment. The results indicate that problems such as gullies, soil compaction, runoff, floods, siltation, and water quality depletion associated with the misuse of agricultural areas in terms of soil conservation and water use are still evident and important even in regions with widespread adoption of no-tillage systems.

Conclusions

The magnitudes of both runoff and sediment yield clearly indicate the need to adopt complementary practices of soil conservation measures, such as mechanical runoff control.     

Suspended sediment dynamics during flushing flows in a large impounded river (the lower River Ebro)

Purpose

The aim of this work was to improve the understanding of the spatial and temporal dynamics of suspended sediment transport during flushing flows in a large regulated river, the lower River Ebro (NE Spain).

Materials and methods

Relationships between sediment and discharge (i.e. discharge (Q)–suspended sediment concentrations (SSC)) were examined during six flushing flows using continuous discharge and turbidity records obtained at six monitoring sections distributed along the lower Ebro River for the 2008–2011 period.

Results and discussion

Analyses revealed marked spatial and temporal patterns. At the spatial scale, the Q–SSC relationships were mostly influenced by the different routing velocity of discharge and sediment waves. At the upstream sections, the sediment peak usually preceded peak discharge (i.e. clockwise loop); however, flow routing through the 85-km channel length tends to increase the lag between them, modifying the hysteresis towards counter-clockwise patterns in the downstream direction. At the temporal scale, the season when the artificial releases were performed strongly influenced the sediment availability, with similar-magnitude flushing flows generating higher sediment peaks in autumn than in spring.

Conclusions

These results are of great interest in order to reinforce the flushing flows programme in the lower Ebro River, so as to help achieve the sustainability of the riverine and deltaic ecosystems.     

Effect of administration of a controlled-release monensin capsule on incidence of calving-related disorders, fertility, and milk yield in dairy cows

OBJECTIVE: To determine the effect of a controlled-release monensin capsule administered at cessation of lactation on incidence of calving-related disorders, fertility, and milk yield in dairy cows. ANIMALS: 290 dairy cows treated with monensin and 290 untreated control cows. PROCEDURE: Treated cows received a capsule that released monensin at 335 mg/d for 95 days. Incidence of calving-related disorders; daily milk yield up to 20 days postpartum; test-day milk yield, fat, protein, and mature-equivalent 305-day milk production; and body condition score at calving were determined. Reproductive variables were conception rate at first service, pregnancy rate, and calving-to-conception interval. RESULTS: Cows treated with monensin were 2.1 times as likely to develop dystocia and 0.8 times as likely to develop metritis as control cows. For milk yield, there was an interaction of treatment X time X parity. In multiparous cows, monensin significantly improved milk yield at test days 4 and 7. In addition, monensin increased body condition score at calving. CONCLUSIONS AND CLINICAL RELEVANCE: Despite increasing the likelihood of developing dystocia and metritis, administration of monensin improved the lactational performance of multiparous cows and may be a promising additive for use at the time of cessation of lactation.