Effects Of Different Feeding Strategies Research Articles

Effects of different feeding strategies on behavior and performance in broiler breeder pullets.

Effects of different feeding strategies on behavior and performance in broiler breeder pullets.

Deciphering Metabolic Pathways in High-Seeding-Density Fed-Batch Processes for Monoclonal Antibody Production: A Computational Modeling Perspective.

Due to their high specificity, monoclonal antibodies (mAbs) have garnered significant attention in recent decades, with advancements in production processes, such as high-seeding-density (HSD) strategies, contributing to improved titers. This study provides a thorough investigation of high seeding processes for mAb production in Chinese hamster ovary (CHO) cells, focused on identifying significant metabolites and their interactions. We observed high glycolytic fluxes, the depletion of asparagine, and a shift from lactate production to consumption. Using a metabolic network and flux analysis, we compared the standard fed-batch (STD FB) with HSD cultivations, exploring supplementary lactate and cysteine, and a bolus medium enriched with amino acids. We reconstructed a metabolic network and kinetic models based on the observations and explored the effects of different feeding strategies on CHO cell metabolism. Our findings revealed that the addition of a bolus medium (BM) containing asparagine improved final titers. However, increasing the asparagine concentration in the feed further prevented the lactate shift, indicating a need to find a balance between increased asparagine to counteract limitations and lower asparagine to preserve the shift in lactate metabolism.

Effect of different feeding strategies and dietary fiber levels on energy and protein retention in gestating sows.

The aim of the study was to investigate whether increased inclusion of sugar beet pulp (SBP) alters retention of fat, protein, and energy when backfat (BF) is restored in early- and mid-gestation. In total, 46 sows were fed one of four dietary treatments with increasing inclusion of SBP providing dietary fiber (DF) levels of 119, 152, 185, and 217g/kg; sows were assigned to one of three feeding strategies (FS; high, medium, and low) depending on BF thickness at mating and again at day 30 for the following month. On days 0, 30, 60, and 108, body weight (BW) and BF thickness were measured and body pools of protein and fat were estimated using the deuterium oxidetechnique. On days 30 and 60, urine, feces, and blood samples were collected to quantify metabolites, energy, and nitrogen (N) balances. On days 15 and 45, heart rate was recorded to estimate heat energy. At farrowing, total born and weight of the litter were recorded. In early gestation, BW gain (P < 0.01) and body protein retention increased (P < 0.05) with increasing fiber inclusion, while body fat retention increased numerically by 59%. The increase in BF was greatest for sows fed the high FS, intermediate when fed the medium strategy, and negligible for sows fed the lowest FS (P < 0.001). Nitrogen intake, N loss in feces, and N balance increased linearly, whereas N loss in urine tended to decrease with increasing inclusion of fibers in early gestation. Concomitantly, fecal energy output and energy lost as methane increased linearly (P < 0.001), while energy output in urine declined linearly. Total metabolizable energy (ME) intake therefore increased from 36.5 MJ ME/d in the low fiber group to 38.5 MJ ME/d in the high fiber group (P < 0.01). Changing the ME towards more ketogenic energy was expected to favor fat retention rather than protein retention. However, due to increased intake of ME and increased N efficiency with increasing fiber inclusion, the sows gained more weight and protein with increasing fiber inclusion. In conclusion, increased feed intake improved both fat and protein retention, whereas increased DF intake increased protein retention.

The effects of different feeding strategies providing different levels of vitamin A on animal performance, carcass traits, and the conversion rate of subcutaneous fat color in cull-cows

Abstract Cull cows represent a significant percentage of revenue received from the U.S. beef industry; however, cull cows are heavily price discounted at time of slaughter. This experiment’s objective is to evaluate different feeding strategies and their effects on body condition score, subcutaneous fat color, and carcass yield and quality traits in cull cows. The central hypothesis is feeding a high-energy diet, with low levels of vitamin A, for 56 d will improve animal performance, carcass yield, and quality traits in addition to capturing the point (rate) of the conversion of yellow to white subcutaneous fat. In the present experiment 98 Angus crossbreed cows were utilized. Cows were fed either low vitamin A (LVA) diet consisting of whole shelled corn, soybean hulls, soybean meal, and a mineral-vitamin supplement or high vitamin A (HVA) diet, formulated using whole shelled corn, fescue hay, dry distiller grains with soluble, and a mineral-vitamin supplement for 56 d. During the 56 d feeding period, body weights and condition scores, and subcutaneous adipose samples were collected every 14 d. On day 56, cattle were slaughtered; 48 h postmortem carcass characteristics and objective color scores (subcutaneous adipose tissue) were recorded and a sample of the longissimus dorsi lumborum was collected. Subcutaneous adipose tissue samples were utilized to record subjective color scores and then ground to be analyzed for β-carotene concentration. The longissimus dorsi lumborum samples (2.54 cm slices) were removed for Warner-Bratzler shear force (WBSF) and pH testing. Data were analyzed using the MIXED procedure of SAS. Feeding cull cows LVA resulted in differences in subcutaneous carcass fat color (P = 0.01) as well as b* values (P &amp;lt; 0.01) on day 56 compared with HVA. Subjective fat color scores were not different (P &amp;gt; 0.10) on day 0 or 14 but were different (P ≤ 0.05) on days 28, 42, and 56. Additionally, 9-cis-β-carotene concentration on day 56 were different (P = 0.05) between treatments. A trend was noticed for all-trans-β-carotene concentration (P = 0.10) on day 56 as well. Cull cow body weights were greater (P ≤ 0.04) when fed the LVA diet starting on days 14, 28, and 42; and a trend was noticed on day 56 (P = 0.09). Overall, cows fed the LVA treatment for 56 d exhibited decreased adipose yellowness and β-carotene concentrations as well as increased live weights.

Effect of different feeding strategies on performance of aerobic granular sludge: From perspective of extracellular polymeric substances and microorganisms

Long-term structural stability of aerobic granular sludge (AGS) is a major challenge in AGS biotechnology. This work investigated variations in the sludge performance, structural stability, and intrinsic mechanisms of AGS under three feeding strategies (R1 direct aeration after fast feeding, R2 anaerobic stirring after fast feeding and R3 anaerobic plug-flow slow feeding). The AGS sequencing batch reactor used in this study was in stable operation with biomass of 6–10 gMLSS/L and a hydraulic retention time of 4 h. The results showed that the best sludge performance was demonstrated in R3, followed by R2 and R1. These differences were caused by extracellular polymeric substances (EPS) and microbial communities. The excellent sludge performance in R3 was attributed to the high hydrophobicity in the EPS as well as the gel properties due to the high hydrogen bonding content in the exopolysaccharide (PS). Similarly, the gel properties formed by the high hydrogen bonding content maintain the sludge stability in R1. Slow-growing dominant bacteria were enriched in the AGS of R2 and R3 with alternating anaerobic/aerobic operation modes, resulting in outstanding sludge performance. In contrast, high abundance of the filamentous bacteria Neomegalonema was enriched in the AGS of R1 without an anaerobic phase, resulting in relatively poor sludge stability. Variations in EPS characteristics and microbial community under the different feeding strategies were the main mechanisms responsible for the long-term operation of AGS. This study could provide a theoretical foundation and technical assistance for the sustainable operation of AGS reactors.

The effect of different feeding strategies on honey bee gut microbiota and the presence of Nosema

Colony development in honey bees depends on both the environmental conditions and their genetic structure. Nutrition is the one of the most important factors in the honey bee’s health. This study was carried out in 48 colonies and included six groups (a control and five feeding groups). In the experiment, the effect of different feeding strategies on intestinal flora and the presence of Nosema was investigated. Pantoea agglomerans, Pseudomonas luteola, Burkholderia cepacia, Brevibacillus nitrificans, Sphingomonas paucimobilis, Aeromonas hydrophila, and P. alcalidimonas were detected in the intestinal microflora of the bee samples by morphological and phenotypic identification. The results of phenotypic identification were confirmed using 16S rRNA sequence analysis for P. agglomerans and B. nitrificans strains. The presence of Nosema was simultaneously investigated in all groups. Only Nosema cerenae was detected using DNA analysis in the positive Nosema spore samples.

Free-Choice Feeding of Whole Grains Improves Meat Quality and Intestinal Development of Pigeon Squabs Compared with Complete Pelleted Feed.

Effects of different feeding strategies on meat quality and intestinal development in pigeon squabs were investigated. 120 pairs of pigeons with two squabs each were assigned to five groups (four free-choice feeding systems and one complete feeding system): T1 (corn, pea, wheat, and pelleted feed), T2 (corn, wheat, and pelleted feed), T3 (corn, pea, and pelleted feed), T4 (corn and pelleted feed), and T5 (complete pelleted feed). Compared with T5, the diet in T4 made the breast meat redder and more yellow (p < 0.05). T2 and T4 resulted in an enhanced total superoxide dismutase activity of meat. Breast muscle in T1 and T2 was determined to have higher contents of nonessential amino acids, glycine, alanine, and glutamic acid (p < 0.05). The contents of the essential amino acids, lysine, threonine, valine, histidine, and arginine were also higher in T1 (p < 0.05). Villus height, surface area, and alkaline phosphatase activity of the duodenum and jejunum in T2 were the highest among the treatments (p < 0.05). In conclusion, free-choice feeding system can improve the meat quality and intestinal development of pigeon squabs, but which combination method of whole grains to use in the production depends on the feeding purpose.

Recombinant production in Escherichia coli of a β-galactosidase fused to a cellulose-binding domain using low-cost inducers in fed-batch cultivation

This study aimed to determine the effects of different feeding strategies in fed-batch cultivations on the production of β-galactosidase fused to a cellulose-binding domain (CBD) by Escherichia coli C41(DE3) using a bench bioreactor. The highest enzyme activities (∼17,000 U/L) were obtained in fed-batch cultivations controlled by DO-stat and induced with lactose (5 g/L) at 18 h of cultivation. Under these cultivation conditions, the maximum values of β-galactosidase yields per substrate, β-galactosidase yields per biomass, and QP were approximately 950 U/gglucose, 1100 U/gcells, and 540 U/L.h, respectively, using Terrific Broth as culture medium and concentrated feed solution (2 ×). The dairy coproducts were efficient in inducing the expression of the recombinant enzyme, having reached the highest values of β-galactosidase-CBD activity after 40 h of cultivation. The maximum enzyme activities obtained when using whey permeate or ricotta whey as inducers were 22,950 or 24,640 U/L, respectively. Using the optimal temperature of E. coli growth before induction and ricotta whey as an inducer increased enzyme productivity in 50%. Plasmid construction showed high stability (>94%) throughout E. coli cultivation. This study demonstrated the feasibility of using the DO-stat feeding strategy to produce β-galactosidase-CBD employing ricotta whey as an inducer of enzyme expression.

Different feeding strategies can affect growth performance and rumen functions in Gangba sheep as revealed by integrated transcriptome and microbiome analyses.

Due to the harsh environment in the Tibetan Plateau, traditional grazing greatly limits the growth potential of local animals and causes severe ecosystem degradation. This is an urgent issue to be solved, which requires alternative strategies for grazing animals in the Tibetan alpine pastoral livestock systems. This study aimed to investigate the effects of different feeding strategies on growth performance and ruminal microbiota-host interactions in the local breed of sheep (Gangba sheep). Thirty 9-month old Gangba sheep (n = 10 per group) were assigned to natural grazing (G), semi-grazing with supplementation (T), and barn feeding (F) groups (supplementation of concentrate and oat hay) based on body weight. At the end of the experiment (75 d), all sheep were weighed, rumen fluid was obtained from six sheep per group, and ruminal epithelium was obtained from 3 sheep per group. The results showed that: (1) Compared with the G and T groups, the F group significantly increased dry matter intake, average daily gain, and feed conversion ratio of animals. Additionally, Gangba sheep in the F group had higher concentrations of ruminal short-chain volatile fatty acids (VFAs), especially propionate and butyrate (P <0.05) than sheep in the G and T groups. (2) The principal coordinates analysis indicated a significant difference in bacterial composition among different feed strategies. More specifically, the relative abundance of propionate (unidentified F082 and Succiniclasticum) and butyrate-producing (Eubacterium_coprostanoligenes_group) genera were also observed to be increased in the F group, in which unidentified F082 was identified as a differential biomarker among the three groups according to linear discriminant analysis effect size analysis. (3) The dynamics of the rumen epithelial transcriptome revealed that ECM-receptor interactions, focal adhesion, and PI3K-Akt signaling pathways, which are critical in mediating many aspects of cellular functions such as cell proliferation and motility, were upregulated in the F group. In conclusion, under harsh conditions in the Tibetan alpine meadow, barn feeding increased ruminal VFAs concentrations (especially propionate and butyrate), which stimulated gene expression related to cell proliferation in rumen epithelium, appearing to be superior to natural grazing and semi-grazing in gaining body weight of the local Gangba sheep.

PSIV-B-29 Evaluating the effect of different feeding strategies in feeding behavior through a novel behavior index integrating several components of the feeding behavior of finishing pigs

Abstract Feeding behavior is an area of study that links the nutritional and behavioral sciences. However, describing the feeding behavior of pigs is difficult given the diversity of variables available and the large day-to-day intra-animal variation. The objectives of this study were to create an index integrating information from several components of feeding behavior that accounts for intra-animal variation, and to evaluate the capability of this index to study the impact of different feeding strategies in pigs’ feeding behavior. Feed intake information from 160 pigs during the last 28 days of the finishing phase from 3 datasets was used. For each pig, the sum of the absolute values of the deviation areas between the regression line of the relative cumulative feed intake and the observed cumulative feed intake was used to calculate the weekly index measuring the irregularity of feed intake (IIFI). Spearman’s correlations of IIFI with the number of daily meals (r = -0.42; P &amp;lt; 0.001), meal duration (r = 0.38; P &amp;lt; 0.01), and feed intake per meal (r = 0.41; P &amp;lt; 0.01) indicate that pigs with high IIFI have fewer meals of longer duration and higher feed intake compared to pigs with low IIFI. Analysis of variance in datasets 1 and 2 showed that moving from conventional to feeding precision systems does not interfere with the feeding behavior of finishing pigs (P &amp;gt; 0.05). In dataset 3, pig feeding behavior was more regular in control diets than for pigs fed fibrous diets (IIFI; 164 vs. 197, respectively; P &amp;lt; 0.05). Additionally, IIFI was smaller in pigs fed canola than in pigs fed wheat by-product diets. These results indicate that IIFI integrates information from several components of the feeding behavior of pigs and demonstrates its potential to evaluate the effect of feeding strategies on feeding behavior.

Compositional and functional properties of milk and dairy products derived from cows fed pasture or concentrate-based diets.

Worldwide milk production is predominantly founded on indoor, high-concentrate feeding systems, whereas pasture-based feeding systems are most common in New Zealand and Ireland but have received greater attention recently in countries utilizing conventional systems. Consumer interest in 'pasture-fed' dairy products has also increased, arising from environmental, ethical, and nutritional concerns. A substantial body of research exists describing the effect of different feeding strategies on the composition of milk, with several recent studies focusing on the comparison of pasture- and concentrate-based feeding regimes. Significant variation is typically observed in the gross composition of milk produced from different supplemental feeds, but various changes in the discrete composition of macromolecular components in milk have also been associated with dietary influence, particularly in relation to the fatty acid profile. Changes in milk composition have also been shown to have implications for milk and dairy product processability, functionality and sensory properties. Methods to determine the traceability of dairy products or verify marketing claims such as 'pasture-fed' have also been established, based on compositional variation due to diet. This review explores the effects of feed types on milk composition and quality, along with the ultimate effect of diet-induced changes on milk and dairy product functionality, with particular emphasis placed on pasture- and concentrate-based feeding systems.

Bioeconomic evaluation of feedings strategies in the yearling beef cattle system in Mozambique

The application of feeding strategies (FS) to meet nutrient requirements of beef cattle grazing on native pastures during the dry season, are required to improve the productivity of production systems in tropical regions. The objective of this study was to evaluate the bioeconomic effects of different FSs applied to yearling bulls in Mozambique, using modeling and simulations as tools to support decision making. A simple deterministic simulation model was developed, assuming initial body weight (120 kg), average daily gain (ADG), feedstuffs, and production costs as inputs. FSs were simulated for a total of 120 days within four ADG systems: 0.000 kg (S000), 0.200 kg (S200), 0.400 kg (S400), and 0.600 kg/d (S600), and three diets were simulated for the positive and maintenance ADG systems, totaling 12 FS. The effects of 12 FS combinations were analyzed and a sensitivity analysis was performed. The effect of the change in the inputs of the model (feedstuffs purchase and calf purchase price) showed the sensitivity of the model to economic parameters (Gross Margin and Net Profit). The negative ADG (-0.200 kg) system (S-200) had the highest labor cost. Corn bran, considering its availability and low cost in the studied region, is a promising feedstuff for concentrates. Effective operational cost (EOC) was higher than 99% in all FSs. S-200, S000, and FS5 within the S200 system resulted in negative net profit (NP) values. Net profit proportionally increased as ADG increased. FS12 (Hyparrhenia rufa, corn bran, and Sesbania sesban) of S600 promoted the highest ratio (NP/total operation cost) (0.48), and consequently, the highest profitability (32.37%). In general, the simulation model shows that, in native and communal pasture beef production systems in regions of Africa with similar production conditions, the productivity of yearling beef cattle during the dry season may be improved by applying feeding strategies.

Evaluation of use effective microorganisms (EM) with different feeding strategies on growth performance, body chemical composition and economic efficiency of monosex Nile tilapiaOreochromis niloticusjuveniles

A factorial trial was conducted to detect the effect of different feeding strategies of supplementation of effective microorganisms (EM) liquid on the growth performance, feed utilization, body chemical composition and economic efficiency of monosex Nile tilapia (Oreochromis niloticus) juveniles. Three experimental treatments were formulated a basal diet without any addition of EM (control; A), a diet supplemented with 2% EM (B), and a diet supplemented with 4% EM (C). All treatments were offered to fish through two different strategies of feeding the meal: 2/3 in the morning and 1/3 in the afternoon or 1/3 in the morning and 2/3 in the afternoon. Each treatment was replicated three times. Juveniles Nile tilapia with an average initial body weight of 3.85 ± 0.22 g (± SE) were randomly stocked at a rate of 90 juveniles per 1.5 m3tank. Fish growth performance and feed utilization significantly (P≤ 0.05) increased with increasing EM supplementation and were positively affected by different feeding strategies. Moreover, the economic evaluation showed that there were more benefits by when using the 4% EM diet and feeding 2/3 of daily meal in the morning.

Alternative feed additive strategies to reduce antimicrobial use in finishing cattle

With the onset of the Veterinary Feed Directive, there is a need to evaluate the current strategies used for the control of liver abscesses as well as coccidia species (Eimeria bovis &amp; Eimeria zuernii) in the feedlot cattle. Additionally, removing coccidiostats and other antimicrobials from the feed will decrease costs of beef production. A study conducted in the summer of 2018 (unpublished) showed no difference in the prevalence of liver abscesses at slaughter nor Eimeria spp in feedlot cattle. The primary objectives of this study are to evaluate the effects of different feeding strategies on the prevalence of liver abscesses and coccidia in feedlot cattle. Secondary objectives of this study are to evaluate the effects of antimicrobials on average daily gain and feed conversion in feedlot cattle.

Effects of dietary protein and fat concentrations on hormonal and oxidative blood stress biomarkers in guide dogs during training

We compared the effects of different feeding strategies on hormonal and oxidative stress biomarkers in guide dogs during specialized training programs. Eight neutered adult dogs belonging to the Labrador retriever breed were divided during the training work into two homogeneous groups for sex (2 males, 2 females), age (17 months ± 1), initial body weight (26.3 kg ± 1), and BCS (4.5 of 9 ± 0.11) and fed two commercial diets with different concentration of energetic nutrients. One diet was a performance diet (HPF) characterized by low-carbohydrate/high-protein and fat content (29:39:19% as-fed) and the other a normal maintenance diet (LPF), characterized by high-carbohydrate/low-protein and fat content (50:24:12% as-fed). The trial lasted 84 days. At days 0, 28, 56, and 84, 180 min before the training work (T0) and immediately after (T1) and after 120 min (T2), blood adrenocorticotrophic hormone (ACTH), cortisol, d-ROMS (reactive oxygen metabolites–derived compounds), and BAP (biological antioxidant potential) were evaluated. Lactate was measured at T0 and T1. The statistical model included the effects of diet (HPF vs. LPF), time (from day 0 to day 84, end of the trial), and exercise (T0, T1, and T2) and their interaction. ACTH (P = 0.002) and cortisol (P = 0.013) showed higher values in the HPF than in the LPF group; there were no significant differences observed for lactate. Time showed no significant difference for any hormones or blood lactate. Exercise significantly (P < 0.001) influenced ACTH and cortisol concentrations, showing higher values at T1 than T0 and T2, and with lactate higher (P < 0.0001) at T1 than T0. Diet did not influence biomarkers of oxidative stress. Time did significantly (P < 0.05) influence BAP results but not d-ROMs. Exercise had no effect on BAP results, but d-ROMs were higher at T0 than T2 (P = 0.001). There was no interaction effect. The pituitary-adrenal (HPA) axis response and the oxidative stress indices could represent an objective method to identify optimal dietary protocols for creating a successful guide dog during the early training period.

Effect of feeding strategy on the protein and fatty acid contents of black soldier fly prepupae (Hermetia illucens) for the potential applications as animal feed and promising alternative protein-rich food

There is considerable interest in the exploring of an alternative protein source due to ever-growing population in the world. Black soldier fly (BSF), Hermetia illucens, can be a promising alternative protein-rich food due to its high protein content as compared to livestock. This study investigated the effect of different feeding strategies on the crude protein of BSF prepupae (BSFP) to further enhance the protein contents. The feeding strategy was done at BSFP stage using two different diets which were a mixture of food waste as a control, and bacterial dried cells. Protein and fatty acid content analyses were done on the freeze-dried BSFP samples harvested on day 4 after feeding in order to determine the crude protein and fatty acid. BSFP fed with lyophilized cells showed enhancement in the nutritional contents, compared to the conventional feeding strategy using food waste, with increased crude protein content by 17%. This study demonstrated that the bacterial dried cells can be utilized as a single cell protein to further increase the protein content in the BSFP body which can be applied for the animal feed and potential human consumption.

PSXI-6 Effects of different feeding strategies during gestation on the reproductive performance of crossbred Landrace-Yorkshire sows

Abstract This study was conducted to investigate the effects of different feeding strategies during gestation on the reproductive performance of sows. A total of 1121 American Landrace-Yorkshire (YL) crossbred sows and parity from 1 to 4 were assigned randomly to “North American System” feeding pattern or “Danish System” feeding pattern during gestation basing on the backfat thickness and body weight. Sows received the same diet and fed ad libitum during lactation. Results showed that over the entire gestation period, there was also no difference in average daily feed intake and total feed intake between two groups (P &amp;gt; 0.05). “Danish System” group has significantly improved the backfat thickness at gestation 30 d (P &amp;lt; 0.01). At 110 d of gestation, there was no difference of the backfat thickness between two groups (P &amp;gt; 0.05). “Danish System” group had significantly increased the total number of born (P = 0.02) and born alive (P = 0.04). The number of total born (P = 0.04), stillborn (P = 0.05) and mummies (P = 0.02), had significantly different in between parities of sows. Mummies had significantly interaction effect (P = 0.01). No different was observed for the number of weaned pigs, litter weight at weaning, piglet weight, and weaning to oestrus interval between two groups. However, a significant increase of litter weight at weaning, piglet weight, was associated with increased parity of sow (P &amp;lt; 0.01). The results of the present investigation showed that “Danish System” group could significantly increase the litter size and number born alive. Our findings point to the importance that the Danish system can be applied to North American genotypes.

Effect of feeding time and frequency on gut transit and feed digestibility in two fish species with different feeding behaviours, gilthead seabream and Senegalese sole

A comparative approach was adopted to assess the effect of different feeding strategies on feed transit and daily oscillations of apparent digestibility coefficients (ADCs) of dry matter, protein, and energy, in two species with different feeding habits, gilthead seabream and Senegalese sole. For this purpose, fish juveniles were consecutively fed with a standard and a marked diet (yttrium oxide) and were sampled at difference post-prandial times. Mathematical models were constructed to predict filling and evacuation of the stomach and intestine in gilthead seabream, and the whole digestive tract in Senegalese sole. Results demonstrated that changes in daily feeding time and frequency, modified the feed transit rate and residence time in the gut as well as the apparent digestibility, with obvious consequences for the utilization of nutrients. Variations in apparent digestibility were also observed along the daily cycle. Besides, the obtained response varied significantly depending on the studied fish species, due to the interspecific differences in the anatomy, digestive physiology, and feeding habits. Allocating the whole daily meal in one ration resulted in fast gut filling rate and low apparent digestibility in both species. In gilthead seabream, feeding protocol did not influence the stomach and intestine evacuation rates. However, in Senegalese sole, frequent meals during the whole daily cycle resulted in a faster gut evacuation. Very frequent diurnal feeding led to highest ADCs in both species; although, such higher digestibility values were not necessarily related to longer feed residence times within the gut in gilthead seabream. The results obtained from this study can be useful to establish optimized feeding protocols that help to reduce the production costs and undigested debris in the effluents.

Effects of cyclical short-term fasting and refeeding on juvenile Lophiosilurus alexandri, a carnivorous Neotropical catfish

The effects of different feeding strategies on the growth rate and hematology of Lophiosilurus alexandri were investigated. An experiment was carried out at the Laboratório de Aquacultura, Universidade Federal Minas Gerais, with nine hundred juvenile L. alexandri (length 4.3 ± 0.3, weight cm 0.9 ± 0.2 g) fed exclusively extruded dry diet and kept in fifteen 30-L cultivation tanks in a recirculating aquaculture system. The design was completely randomized with five replicates of each of three feeding treatments: every day of the week (control), six days of the week (F6:1) and five days of the week (F5:2). The following were calculated at the end of the experiment: survival, daily weight gain (DWG), total length (TL), daily feed intake (DFI), feed conversion rate (FCR), specific growth rate (SGR), final body weight (FBW), condition factor (K), protein efficiency ratio (PER), nitrogen retention (NR) and the hepatosomatic index (HSI). Blood samples were taken after 42 days (prior to feed restriction) and at 45 days (after feed restriction of one or two days), and levels of hematocrit, total plasma, hemoglobin, erythrocytes, leukocytes glucose, cholesterol and triglycerides determined. Data were submitted to ANOVA and means compared by the Tukey test (5%). No significant differences were found for survival, FCR, DWG, TL, FBW, K, and SGR. The highest DFI and HSI values were recorded in the control treatment, while PER and NR were highest in the F5.2 treatment. The highest hematocrit values were observed for the control and F6:1 treatments. In all treatments, the values for hematocrit, total protein, leukocytes and glucose were lower after fasting. The highest values for leukocytes were for the control and F6.1 treatments prior to fasting, while after fasting the control treatment was highest. For the F5:2 treatment, the highest value for erythrocytes was after fasting. The highest values for cholesterol were after fasting for all treatments. In conclusion, L. alexandri exhibits compensatory growth in relation to the two short-term food restriction treatments tested. The species adapted to dietary strategies and maintained hematological and biochemical parameters close to those of the control groups when returned to feeding.

Discontinuous Administration of β-glucan is Effective for Preventing Immune Fatigue in Litopenaeus vannamei

β-glucan is an effective, available immunostimulant that has been successfully used to improve the immune defense of shrimp against pathogenic infection. However, the long-term continuous use of β-glucan can lead to immune fatigue, and intermittent feeding may be an effective way of avoiding this phenomenon. A 60-day growth trial was conducted to compare the effects of different feeding strategies of diets containing 200 mg/kg β-glucan on the growth and immune system of the Pacific white shrimp Litopenaeus vannamei. The results showed that either continuous feeding or intermittent feeding of diets containing 200 mg/kg β-glucan did not promote the growth of L. vannamei. However, the levels of superoxide dismutase, alkaline phosphatase, and acid phosphatase in the hepatopancreas of L. vannamei in the intermittent feeding group were significantly higher than those in the control and continuous feeding groups. Expression levels of the genes encoding LPS/β-glucan binding protein, superoxide dismutase, lysozyme, penaeid in-3a, and catalase were also significantly upregulated in the intermittent feeding group, whereas most of the immune parameters in the continuous feeding group were not significantly different from those of the control group. After artificial infection with Vibrio parahaemolyticus, the average mortality rates in the control group, the continuous feeding group, and the intermittent feeding group were 76.67%, 78.89%, and 45.56%, respectively. The results indicated that the addition of 200 mg/kg β-glucan to the diet did not promote the growth of L. vannamei, but the strategy of intermittent feeding effectively prevented immune fatigue and enhanced disease resistance, perhaps by increasing nonspecific immunity in L. vannamei.