Variable Fitness Response of Two Rotifer Species Exposed to Microplastics Particles: The Role of Food Quantity and Quality

Plastic pollution is an increasing environmental problem, but a comprehensive understanding of its effect in the environment is still missing. The wide variety of size, shape, and polymer composition of plastics impedes an adequate risk assessment. We investigated the effect of differently sized polystyrene beads (1-, 3-, 6-µm; PS) and polyamide fragments (5–25 µm, PA) and non-plastics items such as silica beads (3-µm, SiO2) on the population growth, reproduction (egg ratio), and survival of two common aquatic micro invertebrates: the rotifer species Brachionus calyciflorus and Brachionus fernandoi. The MPs were combined with food quantity, limiting and saturating food concentration, and with food of different quality. We found variable fitness responses with a significant effect of 3-µm PS on the population growth rate in both rotifer species with respect to food quantity. An interaction between the food quality and the MPs treatments was found in the reproduction of B. calyciflorus. PA and SiO2 beads had no effect on fitness response. This study provides further evidence of the indirect effect of MPs in planktonic rotifers and the importance of testing different environmental conditions that could influence the effect of MPs.

Standardization of sperm management for laboratory assessment of sperm quality and in vitro fertilization in Eurasian perch (Perca fluviatilis)

Sperm handling procedures and its usage for in vitro fertilization are crucial for standardized experimental operations on evaluation of reproductive performance, gamete quality, and optimization of fertilization protocols. In our study, the changes in perch sperm motility parameters within 6-h chilled storage and using 4 different activating solutions were compared. Eight different sperm-to-egg ratio was also compared during fertilization. Sperm activated with modified activating solution for cyprinids (78±11%), common perch activating solution (68±16%), modified Lahnsteiner activating solution (75±16%), and Woynárovich solution (76±13%) showed similar progressive motility at 10 s after activation. At 30 s after activation, progressive motility decreased below 5%, regardless the activating solution used. Progressive motility decreased significantly already after 2 h of storage (51±19%) in comparison with 0 h (78±5%). The highest average fertilization rate (using common perch activating solution) was observed with a sperm-to-egg ratio 2.5×105:1 (80±9%), where the smallest variability in the values was also recorded (coefficient of variation: 11%). However, no significant difference was detected among the 8 sperm-to-egg ratio groups. According to our findings, undiluted fresh perch sperm is recommended to use in 1 h post-stripping. Modified Lahnsteiner’s activating solution can be applied efficiently for quality assessment where common perch activating solution is applicable for fertilization in Eurasian perch. A sperm-to-egg ratio 2.5×105:1 already allows to achieve a high fertilization rate; however, the finding is needed to be tested also at hatchery level (higher number of eggs).

Reproductive biology of Kalanchoe laetivirens (Crassulaceae) in the edaphoclimatic conditions of Santa Catarina, Brazil

Crassulaceae of the Kalanchoe laetivirens species have ornamental potential, but are poorly studied, especially their reproductive biology and trophic resources made available to visitors. The aim of this study, therefore, was to characterize the reproductive system of K. laetivirens through analyses of floral morphology, trophic resources and floral visitors. Floral structures, pollen / egg ratio, in vitro pollen germination, pollen grain structure in scanning microscopy and the availability of trophic resources by the evaluation of potential and instant nectar were described. The survey of floral visitors was carried out, and the pollen and nectar collection frequencies were recorded. The results show that the species has tubular flowers, complete with tetramer calyx and corolla, eight epipetalous stamens and four pistils with pluriovulated ovaries. Based on pollen / ovule ratio, this species is optionally autogamous. Morphologically, the pollen grain is small, tricolporate and has radial symmetrywith in vitro germination facilitated in the presence of sucrose (20%). Visitors mostly collected pollen with the highest frequency of visits at 9:30 am. The production of instant nectar had little variation between the evaluated times. The results are relevant to the understanding of the reproductive biology of Kalanchoe laetivirens and its relationship with floral visitors.

Effects of Dietary Inclusion of Seaweed, Heat Stress and Genetic Strain on Performance, Plasma Biochemical and Hematological Parameters in Laying Hens

This study was planned to investigate the effects of seaweed supplementation, genetic strain, heat stress and their interactions on laying hen performances, blood chemistry and hematology. In a short-term trial, laying hens of the two genetic lines Lohman LSL-Lite (White) and Lohman Brown-Lite (Brown) were supplemented with Chondrus crispus (CC) at 3% for 21 days, while a control group was not. In a long-term trial, the same two strains were assigned to control (0%), 3% red seaweed Chondrus crispus (CC) or 0.5% brown seaweed Ascophyllum nodosum (AN)-supplemented diets for 41 weeks, concluding with a four-week control or heat-stress period. The White hens displayed higher egg production and a lower feed/egg ratio. The short-term inclusion of CC significantly reduced the feed intake, weight gain and feed/egg ratio. The long-term seaweed intake affected the plasma albumin and gamma-glutamyl transferase (GGT) (p < 0.05), and there were significant strain-heat stress interactions; heat stress in the Brown birds was associated with reduced protein, globulin and glucose and increased cholesterol and GGT levels and higher heterophil-to-lymphocyte (H/L) ratios (p < 0.05) in response to heat stress (p < 0.05). In conclusion, a long-term seaweed supplementation affected the plasma protein and enzyme profiles, yet had little effect on hen leukocyte counts and the overall performance.

Effects of Different Dietary Calcium Levels on the Performance, Egg Quality, and Albumen Transparency of Laying Pigeons

In order to confirm the dietary calcium (Ca) requirement to keep a balance of the production performance and the albumen transparency, the study examined the effects of different dietary Ca levels on the production performance, egg quality, and albumen transparency of laying pigeons. 1080 pigeon pairs were randomly allocated into six treatment groups, each consisting of six replicates of 30 pigeon pairs per treatment. Ca levels of 0.60, 0.90, 1.20, 1.80, 2.40, and 3.00% were fed. The results showed that the laying rate, average egg weight, and feed to egg ratio were significantly influenced by Ca levels (p < 0.05). Albumen percentage, albumen height, Haugh unit, and eggshell thickness at 8 w and 16 w were significantly influenced by Ca levels (p < 0.05). The L*, a*, b*, and c* values of cooked albumen at 8 w and 16 w were all significantly influenced by Ca levels (p < 0.05). After 16 w of feeding different Ca levels, the percentage of transparent eggs had an early increasing and later decreasing trend. In conclusion, taking the transparency of pigeon eggs as an assessment index and considering production performance secondly, the optimal level of dietary Ca for laying White King pigeons is 0.90%.