Unlike most bivalve shellfishes, giant clams (tridacnines) harbor symbiotic microalgae (zooxanthellae) in their fleshy bodies. Zooxanthellae are not maternally inherited by tridacnine offspring, hence, the larvae must acquire zooxanthellae from external sources, although such algal populations or sources in the environment are currently unknown. It is well known that giant clams expel fecal pellets that contain viable zooxanthellae cells, but whether these cells are infectious or just an expelled overpopulation from the giant clams has not been investigated. In this study, we observed the ultrastructural and photosynthetic competencies of zooxanthellae in the fecal pellets of Tridacna crocea and further tested the ability of these cells to infect T . squamosa juveniles. The ultrastructure of the zooxanthellae cells showed that the cells were intact and had not undergone digestion. Additionally, these zooxanthellae cells showed a maximum quantum yield of photosystem II ( Fv/Fm ) as high as those retained in the mantle of the giant clam. Under the assumption that feces might provide symbionts to the larvae of other giant clams, fecal pellets from Tridacna squamosa and T . crocea were given to artificially hatched 1-day-old T . squamosa larvae. On the 9 th day, 15–34% of the larvae provided with the fecal pellets took up zooxanthellae in their stomach, and on the 14 th day, zooxanthellae cells reached the larval margin, indicating the establishment of symbiosis. The rate reaching this stage was highest, ca. 5.3%, in the larvae given whole (nonhomogenized) pellets from T . crocea . The composition of zooxanthellae genera contained in the larvae were similar to those in the fecal pellets, although the abundance ratios were significantly different. This study is the first to demonstrate the potential of giant clam fecal pellets as symbiont vectors to giant clam larvae. These results also demonstrate the possibility that fecal pellets are a source of zooxanthellae in coral reefs.
In vitro fermentation experiment and in vivo metabolic experiment were conducted to investigate the effects of sake lees made from steamed rice on digestion, ruminal fermentation, nitrogen balance and blood metabolites in wethers fed high concentrate diets. Rolled barley was replaced with soybean meal (SBM), dried sake lees (SLd) and wet sake lees (SLw) as substrates in in vitro study. The SLw treatment had lowest in vitro DM digestibility and acetate concentration (P < 0.01), followed by the SLd and SBM treatments. While, the propionate concentration in the SLw treatment was highest (P < 0.01), followed by the SLd and SBM treatments. The SLd treatment was lowest in in vitro CP digestibility (P < 0.01), followed by the SLw and SBM treatments. Four wethers were used in a 4×4 Latin square design experiment and fed concentrate and roughage at the ratio of 7 : 3 in in vivo study. Soybean meal accounted for 10% of the concentrate diet was replaced with wet sake lees at 0 (C, Control), 34 (L, Low), 69 (M, Middle), 100 (H, High)%. Each concentrate diet had the equal contents of CP and TDN. Ruminal protozoa counts were lower in wethers of M and H treatments than those of C and L treatments (P < 0.05) after feeding. No significant effects of treatment on DM intake, apparent digestibility, nitrogen balance, ruminal pH and VFA concentration. This study suggested that sake lees made by steamed rice can be replaced with soybean meal as concentrate diets.
We investigated the effects of supplementary calcium salt of fatty acid (CSFA) from linseed oil with different oil adsorbents on in vitro gas production and rumen fermentation characteristics in barley substrate condition. A non-supplementation treatment (CONT) and treatments of six products, CSFA without oil adsorbent (2.1 fatty acid/ Ca molar ratio) and CSFAs with silica gel, zeolite, bentonite, diatomite, and vermiculite (2.8 fatty acid/Ca molar ratio), were prepared. The supplementary 2% and 4% CSFA with silica gel (+S) in the substrate reduced CH 4 production 56% and 79%, respectively, compared with that in CONT (p < 0.01). The products, except for +S, did not decrease CH 4 production. The dry matter (DM) disappearance in CSFAs with oil adsorbents was lower than that in the CSFA without oil adsorbent (74.8%-77.3% vs. 79.3%, p < 0.01), and crude protein (CP) disappearance in +S supplementation was lower than that of the other products (53.5% vs. 57.2%-59.1%, p < 0.01). The +S supplementation decreased acetate proportion and increased propionate proportion (p < 0.01). Our study indicated that although the disappearance of DM and CP might decrease, using silica gel as an oil adsorbent of linseed oil calcium salt with high fatty acid/Ca molar ratio has the potential to mitigate CH 4 emissions from ruminants. K E Y W O R D S calcium salt of fatty acid, in vitro fermentation, methane mitigation, oil adsorbent, silica gel 1 | INTRODUCTION Strategies to decrease global greenhouse gas (GHG) emissions have been developed to address environmental issues. Methane (CH 4 ) is an important source of GHG and has 28 times the global warming potential of CO 2 calculated on a 100-year time frame (Intergovernmental Panel on Climate Change [IPCC], 2013). Methane emissions from ruminants account for 24.0% of the total CH 4 emissions source (United Nations Framework Convention on Climate Change[UNFCCC], 2015), and 2%-12% of gross energy intake is also lost by CH 4 emissions in ruminants (Johnson & Johnson, 1995). Therefore, inhibition of CH 4 emission from enteric fermentation of ruminants can contribute not only to preventing global warming but also to improving feed efficiency.The effectiveness of feeding lipids on CH 4 reduction differs from that of lipid sources or the amount of lipid supply (Martin et al., 2008;Martin et al., 2016). For example, canola and linseed oils, which are rich in monounsaturated fatty acids (MUFAs) and polyunsaturated fatty acids (PUFAs), respectively, reduce CH 4 emissions in lactating dairy cows (Martin et al., 2010) and beef cattle (Beauchemin &
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.