Sean M. Tibbetts

Dietary protein requirement of juvenile American eel (Anguilla rostrata) fed practical diets

Abstract Triplicate groups of juvenile American eel were fed to satiation herring meal-based diets containing 35, 39, 43, 47 and 51% crude protein (as fed basis) for 84 days. Data were collected to determine the relationship between dietary protein level and the following response variables: mean weight gain (MWG), specific growth rate (SGR), feed conversion ratio (FCR), nutrient digestibility and nutrient retention. Highest MWG and SGR ( P P P P P

Nutrition, Feeding, and Behavior of Fish

Nutrition and feeding influence growth, reproduction, and health of fish and their response to physiologic and environmental stressors and pathogens. The basics of fish metabolism are similar to those of warm-blooded animals in that they involve food intake, digestion, absorption, and transport of nutrients to the various tissues. Fish, however, being the most primitive form of vertebrates, possess some distinguishing features which will be discussed. Unlike warm-blooded animals, which are homoeothermic, fish are poikilothermic, so their body temperature and metabolic rate depends on the water temperature and this has practical implications for the nutrition, feeding and health of fish. Several behavioral responses have been linked to methods of feeding, feeding habits, frequency of feeding, mechanisms of food detection, and food preferences. Fish are also unique among vertebrates in their ability to absorb minerals not only from their diets but also from water through their gills and skin.

Ruminal in vitro gas production, dry matter digestibility, methane abatement potential, and fatty acid biohydrogenation of six species of microalgae

Abstract: This study evaluated the composition, digestibility [dry matter digestibility (DMD)], CH4 abatement potential, and fatty acid biohydrogenation of six species of microalgae. Lipid content ranged from 115 g kg-1 dry matter (DM) (Scenedesmus sp. AMDD) to 361 g kg-1 DM (Tetracystis sp.), while Scenedesmus sp. AMDD had the highest carbohydrate (364 g kg-1 DM) and fibre content (277 g kg-1 DM). Gas production was highest (P < 0.001) for Micractinium reisseri and Chlorella vulgaris. In vitro DMD ranged from 654 g kg-1 for Scenedesmus sp. AMDD to 797 g kg-1 for Nannochloris bacillaris. Total CH4 differed (P < 0.001) among microalgae, ranging from 1.76 mL g-1 DM for Tetracystis sp. to 4.07 mL g-1 DM for M. reisseri. Nannochloropsis granulata (marine) had higher myristic, palmitoleic, and eicosapentaenoic acid levels than freshwater microalgae. Levels of a-linolenic acid were higher in Scenedesmus sp. AMDD than all other microalgae. CH4 production negatively correlated (P < 0.05) with levels of total carbohydrate, oleic, and a-linolenic acid. Despite having a lower lipid content, CH4 reductions with Scenedesmus sp. AMDD were comparable to Tetracystis sp. and N. bacillaris. Reductions in CH4 with Tetracystis sp. and N. bacillaris occurred without a decline in DMD, suggesting that overall microbial activity was not inhibited.

Nutritional Evaluation of Whole and Lipid-Extracted Biomass of the Microalga Scenedesmus sp. AMDD for Animal Feeds: Simulated Ruminal Fermentation and In Vitro Monogastric Digestibility

Background: Scenedesmus sp. AMDD (S-AMDD) has been the focus of several studies to assess its potential as a feedstock for biofuels and bioremediation, while the evaluation of its potential suitability as a novel animal feed ingredient has only just begun. In an initial study; S-AMDD demonstrated rapid growth rate and biomass productivity during exponential growth phase and the resulting biomass appeared to have good potential for animal nutrition based on its attractive proximate composition, favorable essential amino acid, fatty acid and elemental profiles and lack of contaminating heavy metals. However, the total carbohydrate and fibre fractions of whole-cell and lipid-extracted SAMDD were relatively high which could limit their digestion, particularly when fed to monogastric animals. The difference in the capacity to digest and metabolically utilize diets rich in cellulosic material (e.g., fibre) is vast between various farmed animal species. As such, knowledge on the nutritional value of novel ingredients for ruminant animals can rarely be immediately extrapolated to monogastrics and vice versa. Simulated fermentation using rumen-derived digestive fluids or in vitro digestibility using purified monogastric-derived enzymes can provide valuable information. Although not fully conclusive, results from these types of rapid assays are generally inexpensive, require smaller amounts of sample; utilize fewer (or zero) experimental animals, avoid feed refusal issues associated with ingredient off-flavours or odours and can be effective tools for research and for routine industrial use. Objective: The present study is the second in a series of projects designed to evaluate the nutritional value of S-AMDD for animal feed applications. The main objective was to generate novel digestibility data of whole-cell and lipid-extracted S-AMDD for both ruminant and monogastric animals including ruminal organic matter digestibility (OMD), apparent metabolizable energy (aME) content, methane (CH4) production, dilute pepsin digestibility (DPD) and two-phase gastric/pancreatic digestibility of protein (GPDProtein) and energy (GPDEnergy). Methods: Simulated ruminal OMD, aME contents and CH4 production of experimental test diets containing graded levels of whole-cell and lipid-extracted S-AMDD were estimated using a modified batch-culture in vitro fermentation system with total gas capture using lactating dairy cattle as rumen fluid donors. In vitro monogastric DPD and two-phase GPD were measured by incubation of whole-cell and lipid-extracted S-AMDD samples in porcine pepsin and porcine pancreatin, containing amylase, lipase and protease enzyme solutions. Results: Simulated ruminal fermentations using lactating dairy cattle as rumen fluid donors indicate that both whole-cell and lipid-extracted S-AMDD have excellent potential for use in ruminant animal feeds. Dietary inclusion of whole-cell SAMDD at 50% forage protein replacement (equivalent to 20% of the total diet) or lipid-extracted S-AMDD at 100% forage protein replacement (equivalent to 32% of the total diet) did not significantly affect OMD or aME content of the control diet. However, OMD was marginally comprised with 100% forage protein replacement with whole-cell S-AMDD (equivalent to 40% of the total diet) relative to the 25 and 50% replacement levels, although not significantly different from the control diet. Diets containing lipid-extracted S-AMDD significantly reduced CH4 production by approximately 50% compared to the control diet (47% reduction) and those containing whole-cell S-AMDD (51% reduction). Since OMD and aME content of diets containing lipid-extracted S-AMDD were unaffected relative to the control diet and whole-cell S-AMDD-containing diets, it seems clear that lipid-extracted S-AMDD contains anti-methanogenic ‘non-fatty acid’ substances that have the ability to suppress rumen methanogenic bacteria without disturbing ruminal digestion. This area warrants further exploration in vivo, especially considering the large volume of algal feed that could be produced 2 Journal Name, 2015, Vol. X, No. X Principal Author Last Name et al. without occupying significant land resources. In vitro monogastric digestibility using porcine enzymes indicates that lipid-extracted S-AMDD has potential for use in monogastric animal feeds. Protein and energy digestibility of this product were moderately high (75-84% and 70%, respectively); which resulted in relatively high contents of DP (30%) and DE (14 MJ kg-1). On the other hand, the digestibility of whole-cell S-AMDD was low at 52-61% and 50%, respectively resulting in lower levels of DP (15%) and DE (12 MJ kg-1). Despite the encouraging results for lipidextracted S-AMDD, the digestibility (particularly of energy) remains marginal for monogastric animals and requires improvement through additional cost-effective cell rupture technologies or the production algal protein concentrates.