Dry Diet Research Articles

Effects of a Veterinary Gastrointestinal Low-Fat Diet on Fecal Characteristics, Metabolites, and Microbiota Concentrations of Adult Dogs Treated with Metronidazole.

Antibiotics are known to cause loose stools, disrupt the fecal microbiota, and alter fecal bile acid (BA) profiles of dogs. Recovery may be aided by diet, but little research has been conducted. The objective of this study was to determine how a veterinary low-fat diet affected the fecal characteristics, metabolites, BA, and microbiota of dogs receiving antibiotics. Twenty-four healthy adult dogs [7.38 ± 1.95 yr; 7.67 ± 0.76kg body weight (BW)] were used in an 8-wk completely randomized design study. During a 2-wk baseline, all dogs were fed a leading grocery brand dry kibble diet (GBD). Over the next 2wk, dogs were fed GBD and received metronidazole orally (20mg/kg BW twice daily). At wk 4, dogs were randomly allotted to one of two treatments [GBD or Blue Buffalo Natural Veterinary Diet GI Gastrointestinal Support Low-Fat (BB)] and fed for 4wk. Fecal scores were recorded daily and fresh fecal samples were collected at wk 2, 4, 5, 6, 7, and 8 for measurement of pH, dry matter content, and metabolite and BA concentrations. Fecal microbiota populations were analyzed by 16S rRNA gene amplicon sequencing and qPCR-based dysbiosis index (DI). All data were analyzed as repeated measures using the Mixed Models procedure of SAS 9.4, testing for effects of treatment, time, and treatment*time and significance set at P<0.05. Metronidazole increased (P<0.0001) fecal scores (looser stools), reduced fecal short-chain fatty acid, branched-chain fatty acid, phenol, and indole concentrations, increased primary BA concentrations, and decreased secondary BA concentrations. Metronidazole also reduced fecal bacterial alpha diversity, altered the abundance of 58 bacterial genera, and increased DI. During antibiotic recovery, change in fecal pH, dry matter percentage, and metabolite and immunoglobulin A concentrations were altered (P<0.05) by diet. Fecal BA concentrations recovered quickly for all dogs. Change in lithocholic acid was affected (P<0.0001) by diet, but other BA were not. Recovery of over 25 bacterial genera was impacted by diet (P<0.05). While many bacterial taxa returned to baseline levels after 4wk, others did not fully recover. DI and bacterial alpha diversity measures recovered quickly for all dogs, but were not impacted by diet. In conclusion, metronidazole drastically altered the fecal microbiota and metabolites of dogs. While most variables returned to baseline by wk 8, diet may be used to aid in recovery.

Nematodes Can Substitute Artemia in a Co-Feeding Regime for Pacific White Shrimp Post-Larvae Reared in a Biofloc Nursery System.

This study evaluated nematodes as an alternative to live Artemia when provided in a co-feeding regime to Pacific white shrimp (Penaeus vannamei) post-larvae (PL) reared in a biofloc nursery system. A 20-day experiment employing PL11 was performed for an evaluation of four dietary groups: control [C] (fed exclusively with a dry commercial feed); artificial Artemia [AA] (dry feed composed of extracted and processed Artemia cysts and dry commercial feed); live Artemia and dry commercial feed [LA]; and nematodes and dry commercial feed [N] (Panagrolaimus sp. dry nematodes). The diets were provided twice a day, with the remaining six feed provisions being a commercial dry feed for all experimental groups. A biofloc system was chosen as it offers a potentially sustainable approach to intensive shrimp farming. Alkalinity and pH in the [N] group were significantly higher in the last 5 days of the experiment (p < 0.05), likely causing the significantly lower nitrite levels observed in that same group (p < 0.05). Total and volatile suspended solids were significantly lower in the two live feed groups when compared with [C] and [AA] (p < 0.05). Although PL fed the dry diets exhibited higher growth rates (p < 0.05), the [N] and [LA] groups presented significantly higher final survivals (p < 0.05). No differences were found for survival after a salinity stress test (p ≥ 0.05). These results suggest that nematodes can successfully substitute Artemia in a co-feeding regime for P. vannamei PL reared in biofloc nursery systems.

96 Using greenhouse gas flux to estimate forage dry matter intake in ad libitum fed replacement heifers

Abstract An accurate estimate of feed intake is a critical component in determining individual animal feed efficiency. However, existing feed intake measurement systems are not designed for unprocessed, dry forage diets. Open-circuit gas flux technology measures enteric gas emissions for cattle in a pasture-based setting. If a significant relationship exists between feed intake and gas emissions, this system could be used to rank grazing cattle for forage intake and forage utilization efficiency. Our objective was to develop prediction equations to estimate forage dry matter intake using gas flux and performance data. Angus and Angus x Hereford heifers [n = 71; initial body weight (BW) 329.5 ± 31.1 kg] were used over 3 yr to measure intake, gain, and gas flux. All heifers were subject to a 21-d adaptation and 71-d intake test using individual intake technology (SmartFeed; C-Lock Rapid City, SD) with a stocking rate of 3.3 heifers per feeder. Throughout the study, heifers were fed a long-stem, unprocessed, grass hay diet (≥ 10.8% CP, 2.0 Mcal ME, and 56% TDN) with ad libitum access to a salt/mineral supplement. The GreenFeed system (C-Lock Rapid City, SD) was used to monitor oxygen (O2) consumption (means ± SD; 3364.4 ± 374.8 g/d), methane (CH4; 181.4 ± 24.3 g/d) and carbon dioxide (CO2) production (4,965.3 ± 494.5 g/d). Body weights were collected every 14 d, and average daily gain (ADG) was calculated by regressing BW on day of study. The phenotypic correlations of forage DMI with CO2, CH4, O2, and heat production (HP) were 0.72, 0.66, 0.74, and 0.74, respectively. Average daily gain and midpoint metabolic BW combined with the estimate of daily HP, O2, or CO2 accounted for 60% of the variation in forage DMI. These results suggest that forage intake can be predicted using performance data in conjunction with the GreenFeed gas quantification system.

Accuracy and precision of diets fed to close-up cows on dairy farms and its association with early lactation performance

Ensuring a consistent ration is critical for maximizing lactating cow performance, but this is not known for dry cows. The objectives of this cohort observational study were to: 1) characterize close-up dry cow diets fed on commercial farms in Ontario, Canada, 2) describe the accuracy of the nutrient composition between the formulated close-up diet and the diet offered to the cows, 3) describe the precision of the close-up diets across time, and 4) explore potential associations of that accuracy and precision with blood metabolic parameters and milk yield of cows in early lactation. Forty free-stall dairy farms were visited once every 4 wk, for a total of 6 visits to each farm, from April to October 2022. At each visit, samples of the close-up diet were collected and analyzed for dry matter (DM) content and chemical composition. Close-up diet formulations were also obtained by each farm's nutritionists. During each visit, fresh cows (0 to 14 d in milk [DIM]) had blood samples taken for blood metabolites. The same cows were also monitored for milk yield up to 120 DIM. Multivariable models were used to analyze associations between variability (in relation to the formulated diet and across time) of nutrients in the close-up diet, as measured by coefficient of variation (CV), and outcomes in fresh cows. Corn silage (67.6% of farms) and straw (24.3% of farms) were the predominant primary forage sources used in the close-up dry cow diets. Soybean meal (37.8% of farms) and canola meal (18.9% of farms) were the main ingredients used as primary concentrate sources. Overall, the diets offered did not accurately represent the formulated diets. With the exception of net energy for lactation (NEL), the CVs for the other nutrients were all greater than 5%. Diet variability, both between fed and formulated diets and from visit to visit during the close-up period, was associated with metabolic markers and dairy cow production. Lower variability in non-fiber carbohydrates (NFC) between the fed and formulated diets was associated with better liver health index scores. Visit-to-visit variability in fat% and NFC% were associated with blood β-hydroxybutyrate (BHB) concentrations, while NFC% variability was associated with blood glucose levels. Serum nonesterified fatty acids (NEFA) concentrations were associated with visit-to-visit variability in DM% and CP%. These results underscore the importance of maintaining consistency between diet formulations and feeding practices over time to optimize early-lactation dairy herd performance and health, granted that these diets are correctly formulated to meet the nutritional needs of cows in the close-up period and applied with recommended feeding practices.

Dog and owner demographics impact dietary choices in Dog Aging Project cohort.

To describe the demographic factors of owners and their dogs associated with owner feeding choices and the regularity with which those diets were fed to a US-based population of dogs. This cross-sectional analysis examined 40,367 initial survey responses from US dog owners participating in the Dog Aging Project. The surveys were collected from January 2, 2020, to December 31, 2022, and included primary and secondary diet component types and dog and owner demographic variables. Each demographic variable was compared across diet type choices with a χ2 test of independence. Most owners (82%) fed a commercially prepared extruded dry diet (kibble) as the primary diet component. Most owners (89%) reported that they fed their dogs a consistent diet over time. Owner demographic factors (income, education level) were less correlated with difference in diet choices than dog demographic factors (size, neuter status, purebred status, activity level), but owner age did correlate with choice: younger owners tended to feed kibble more compared to older owners. Home-cooked diets were most often consumed by small (< 30-lb) dogs, purebred dogs in poorer health status, and dogs with owners aged 45 years or older. Raw diets were more commonly fed to purebred, intact, and highly active dogs. Ten percent of service dogs were reportedly fed a raw diet of some sort. Demographic variables are associated with statistically significant differences in diet types selected. Nutrition studies examining health outcomes associated with the feeding of different diet types should account for these factors during design or analysis in order to avoid bias. An epidemiological tool, the directed acyclic graph, is presented. This information will help clinicians in their discussions with clients about pet nutrition.

Effect of taurine on growth and immune response of Pacific white shrimp (Litopenaeus vannamei) cultured at different temperatures

Low temperature is a common challenge in the culture of Pacific white shrimp (Litopenaeus vannamei), and taurine is a potential nutrient that may improve its cold-resistance. This experiment aimed to investigate effects of dietary taurine on growth and immune response of Pacific white shrimp cultured at normal and cold temperatures. Six diets were supplemented with increasing levels of taurine (0, 0.2, 0.4, 0.6, 0.8 and 1.0%) and fed to shrimp (1.59 ± 0.03 g) reared at two water temperatures (28 °C and 20 °C) for 8 weeks. The results showed that compared with 28 °C, shrimp reared at 20 °C showed lower growth performance, feed utilization, apparent digestibility and total hemocyte count (THC) (P < 0.05), but higher content of serum glucose, intracellular reactive oxygen species (ROS) and Ca2+, malonaldehyde (MDA) and apoptosis rate (P < 0.05), indicating a higher risk of oxidative damage during low temperature stress. Interestingly, shrimp could cope with cold stress by changing hemocyte composition, increasing antioxidant enzyme activity and genes expression of apoptosis and autophagy. The effect of taurine was different at different temperatures. At 28 °C, taurine supplementation improved growth rate of shrimp by increasing digestive enzyme activities, digestion absorption rate and nutrient utilization. Based on the quadratic model of weight gain rate, feed efficiency, protein retention efficiency and the broken line model of apparent digestibility coefficients of protein, the amount of taurine required for shrimp reared at 28 °C was 0.57–0.60% of dry diet. At 20 °C, taurine increased the number of THC, granulocytes, semi-granulocytes, the activities of antioxidant enzymes such as superoxide dismutase and catalase, and decreased the content of ROS in the cells, which may enhance cold resistance of shrimp. Moreover, taurine supplementation down-regulated mRNA expression of cell apoptosis genes (cyt-c, caspase-9 and caspase-3) and up-regulated mRNA expression of cell autophagy genes (atg1, atg13, atg7 and lc3) (P < 0.05), which may help to maintain cell stability at 20 °C. The optimal requirement of taurine in shrimp reared at 20 °C was 0.56–0.66% of dry diet in this experiment based on THC and MDA content. In conclusion, our study suggests that appropriate taurine promotes growth and feed utilization at optimal temperature and enhances the stability of hemocyte at low temperature in white shrimp.

Poly-β-hydroxybutyrate supplementation enhanced the growth and immune responses of juvenile Nile tilapia (Oreochromis niloticus)

Development of alternative disease treatment and prevention strategies has received considerable attention in recent years due to frequent epizootic outbreaks in modern intensive aquaculture. Poly-β-hydroxybutyrate (PHB) is a biopolymer synthesized by some bacteria with potential immunostimulatory effects. This study analyzed the potential of PHB as an immunomodulator in juvenile Nile tilapia utilizing in vitro and in vivo approaches. Head-kidney-derived macrophage production of intra- and extra-cellular superoxide anion exhibited significant linear and quadratic relationships with graded doses (0.0, 0.5, 1.0, 2.0, 4.0 and 8.0 mM) of a PHB precursor, 3-hydroxybutryate (3HB). Additionally, lyophilized PHB-synthesizing bacteria, Zobellella denitrificans (ZD1), were supplemented to a practical basal diet for Nile tilapia (36% crude protein and 6% crude lipid) to produce five isonitrogenous and isolipidic experimental diets containing PHB in five stepwise increments (0.125, 0.25, 0.5, 1.0, and 2.0% of dry-diet weight). After termination of the feeding trial, Nile tilapia exhibited dose-dependent linear and quadratic relationships in percentage weight gain, as well as feed efficiency, protein conversion efficiency, and hepatosomatic index. Finally, PHB-supplemented diets did significantly modulate intestinal microbiota composition. In conclusion, Nile tilapia exhibited enhanced growth parameters, condition factors, immunological responses, and intestinal microbiota modulation when fed PHB, with the optimal inclusion level determined to be 1% of dry diet.

Effect of supplemental milk replacer and liquid starter diet for 4 and 11 days postweaning on intestinal parameters of weaned piglets and growth to slaughter

Reduced piglet feed intake immediately postweaning (pw) leads to disruption of small intestine structure and function and reduced growth. Our objective was to evaluate the effect of providing supplemental milk or liquid starter diet for either 4 or 11 days pw, on intestinal parameters of newly weaned piglets and growth to slaughter. At weaning (28 ± 0.6 days old), five hundred and eighty−seven piglets ((Large White × Landrace) × Duroc) were divided into 59 pen groups, each containing 9–10 same sex (entire male or female) piglets. The pen groups were blocked by sex and weaning weight and provided with ad-libitum access to one of five dietary treatments: (1) Dry pelleted starter diet (control; CON); (2) CON+liquid milk replacer for 4 days pw (M4); (3) CON+liquid milk replacer for 11 days pw (M11); (4) CON+liquid starter diet for 4 days pw (S4) and (5) CON+liquid starter diet for 11 days pw (S11). Pen groups were weighed at weaning, days 11, 20, 28, and 47 pw and at target sale weight. Feed disappearance (on a DM basis) was recorded on each weighing day. On day 7 pw, 10 piglets per treatment were euthanised to collect small intestine tissue samples for determination of villus height (VH), crypt depth and brush-border membrane enzyme activity. Data were analysed using SAS-version 9.4. Between days 0 and 11 pw, M11 increased average daily feed intake by 48% and average daily gain (ADG) by 57% compared to CON (P < 0.05), and increased ADG by 54% (P < 0.05) compared to S4. Piglets on M11 also had improved feed conversion efficiency compared with CON piglets between days 0 and 11 pw. Treatment did not affect growth performance after day 28 pw, or carcass parameters at slaughter. At day 7 pw, M11 piglets had 37% higher jejunal VH than CON piglets (P < 0.05) and S11 piglets had 28% higher ileal VH than S4 piglets (P < 0.05). M11 piglets had up to 150% higher ileal sucrase activity than M4, S4 and S11 piglets (P < 0.05) and 180% higher ileal maltase activity than S4 piglets (P < 0.05). In conclusion, M11 reduced the immediate negative effects of weaning, as it was associated with increased feed intake, growth, brush-border membrane enzyme activity and improved intestinal structure early pw. However, there were no carryover effects of any of the liquid supplements on growth or feed efficiency or carcass weight at slaughter.

Feeding nanoparticles of copper oxide coated with lysine with or without added antagonists affects the copper status but not performance of Holstein dairy cows

The apparent absorption of copper (Cu) in ruminants is low, with between 0.01 and 0.07 g/g absorbed from sources such as copper oxide (CuO) under typical feeding conditions, resulting in high levels of excretion. Improving the bioavailability of Cu could reduce the supplemental amount required to maintain Cu status and reduce excretion, particularly in the presence of dietary antagonists such as sulfur (S) and molybdenum (Mo). The objective of our study was to determine the Cu status of cows when fed nanoparticle CuO coated with Lys compared with conventional CuO when fed without or in combination with antagonists to Cu absorption (S and Mo) in the diet of dairy cows. Fifty-six multiparous Holstein-Friesian cows that were 48 d ± 17.4 (mean ± SD) post calving and yielding 40.6 ± 6.9 kg milk/d were used in a 2 × 2 factorial design. The 4 treatment groups were; CuO (O-), CuO with added antagonists (O+), nano CuO with a lysine coating (N-), and nano CuO with a Lys coating with added antagonists (N+), fed for 16 wks. We formulated the diets to contain approximately 17 mg Cu/kg dry matter (DM) and diets with antagonists contained an additional 1 g S/kg DM and 6 mg Mo/kg DM, with Lys added to O- and O+ to provide the same daily supply as N- and N+. Blood samples were collected at wk 0, 2, 4, 6, 10 and 16, and liver biopsy samples at wk 0 and 16. We found no effect of dietary treatment on DM intake, milk yield, live weight or body condition score, with mean values of 23.3 kg/d, 40.1 kg/d, 646 kg and 2.68, but milk SCC was higher in cows fed conventional compared with non CuO, or with added antagonist. We also found no effect of treatment on blood activity of gamma glutamyl transferase, superoxide dismutase or ceruloplasmin, hematology profile, or plasma Cu and iron concentration. We found that plasma Mo concentration was increased from 0.36 µmol/L in cows fed O- or N- to 0.80 µmol/L in those receiving O+ or N+. Additional dietary antagonists also decreased the concentration of Cu in the liver of cows fed conventional CuO (C+) over the study period by 1.3 mg/kg DM/d, but in cows fed dietary antagonists and nano CuO coated with Lys (N+), liver Cu concentration was increased by 1.1 mg/kg DM/d. Our study is the first to demonstrate that reducing the particle size of CuO into the nano scale with a lysine coating improves the bioavailability of CuO in the presence of dietary antagonists in dairy cattle, and we did not observe any negative effects on performance or health.

Effects of dietary tryptophan levels on growth performance, serotonin metabolism, brain 5-HT and cannibalism activities in tiger puffer, Takifugu rubripes fingerlings

Essential amino acid (EAA) requirements of aquaculture fish species can be used as a guideline for commercial feed formulation. Several EAA requirements have been quantified in tiger puffer (Takifugu rubripes). However, as the third limiting amino acid (AA) of many plant protein sources, tryptophan requirement of this species has yet to be quantified. This study was conducted to determine dietary tryptophan requirement of tiger puffer, and investigate the effect of dietary tryptophan supplementation on the cannibalism, brain serotonin (5-hydroxytryptpamine, 5-HT) metabolism and serum cortisol levels. Six experimental diets were prepared using fish meal, gelatin and corn protein concentrate as intact protein, and then supplemented with crystalline AA premix. The analyzed tryptophan levels in the experimental diets were 3.5, 4.1, 4.5, 5.5, 7.0 and 11.8 g/kg of dry diet. Experimental diets were randomly fed in triplicate to tiger puffer (initial average weight of 17.5 g) for 58 days. The weight gain (WG), feed conversion ratio (FCR) and protein efficiency ratio (PER) were significantly affected by dietary tryptophan, and the break points were observed at 5.07, 4.82 and 4.99 g/kg of dry diet, respectively. Compared to the basal diet, the cannibalism (the rate of bite mark appearance) was significantly lower and survival rate was significantly higher when fish were given diets containing 7.0 and 11.8 g/kg tryptophan. The concentrations of free tryptophan and phenylalanine in the brain exhibited a nonlinear increase in response to the incremental levels of dietary tryptophan. Brain 5-HT concentration was significantly affected by dietary tryptophan levels, but did not show a significant dose-dependent response. The expression of genes related to 5-HT metabolism (tph1a, ddc and aldh) and serotonin reuptake (sert) in the brain varied significantly and exhibited a nonlinear relationship with the graded levels of dietary tryptophan. In addition, serum cortisol levels showed a decreasing trend till the 5.5 g/kg tryptophan inclusion level, at which point there appeared to be the lowest level. In conclusion, based on nonlinear regression analysis of the WG, FCR and PER, dietary tryptophan requirement of tiger puffer was determined to be range between 4.82 and 5.07 g/kg of dry diet (10.48–11.03 g/kg of dietary protein). Dietary tryptophan supplementation above requirement could mitigate cannibalism and improve the survival of tiger puffer, which may be attributed to regulating the synthesis and catabolism of 5-HT and its availability in the synaptic cleft, and subsequently the reduction of serum cortisol content.

Quantifying methane emissions during dry season and estimating emission factors in alpacas grazing Andean grasslands

This study aimed to (1) measure methane emissions from alpacas grazing in Andean grasslands during the dry season and compare them with those of sheep under similar conditions, and (2) estimate the methane conversion and emission factor for alpacas grazing in Andean grasslands, considering methodology, animal class, and season. The comparison involved nine alpacas and nine sheep, with measurements taken for dry matter intake, diet composition, and enteric methane emissions measured with the sulfur hexafluoride technique. Alpacas selected a more digestible diet than sheep (0.62 vs. 0.50 g/g of dry matter), even with limited feed availability. Methane emissions were similar between the two species. For the second objective, the study used observations from the first objective and mean treatments from a literature review. The developed model predicted methane conversion factors, considering animal class and measurement methodology, with no significant influence observed for season. The predicted methane conversion factors (% gross energy in feed converted to methane) for alpacas grazing in Andean grasslands were 7.71 for juveniles (i.e., tuis) alpacas and 8.71 for adults, corresponding to emission factors of 6.49 and 9.77 g per alpaca and day, respectively. These results emphasize the importance of considering animal class, measurement methods, and regional variations when estimating methane emission factors for alpacas.

Farm-level risk factors associated with increased milk β-hydroxybutyrate and hyperketolactia prevalence on farms with automated milking systems

The objectives of this study were to determine the farm-level hyperketolactia (HKL) prevalence, as diagnosed from milk β-hydroxybutyrate (BHB) concentration, on dairy farms milking with an automatic milking system (AMS) and to describe the farm-level housing, management, and nutritional risk factors associated with increased farm-average milk BHB and the within-herd HKL prevalence in the first 45 DIM. Canadian AMS farms (n = 162; eastern Canada n = 8, Quebec n = 23, Ontario n = 75, western Canada n = 55) were visited once between April to September 2019 to record housing and herd management practices. The first test milk data for each cow under 45 DIM were collected, along with the final test of the previous lactations for all multiparous cows, from April 1, 2019 to September 30, 2020. The first test milk BHB was then used to classify each individual cow as having HKL (milk BHB ≥ 0.15 mmol/L) at the time of testing. Milk fat and protein content, milk BHB, and HKL prevalence were summarized by farm and lactation group (all, primiparous, and multiparous). During this same time period, formulated diets for dry and lactating cows, including ingredients and nutrient composition, and AMS milking data were collected. Data from the AMS were used to determine milking behaviors and milk production of each herd during the first 45 DIM. Multivariable regression models were used to associate herd-level housing, feeding management practices, and formulated nutrient composition with first test milk BHB concentrations and within-herd HKL levels separately for primiparous and multiparous cows. The within-herd HKL prevalence for all cows was 21.8%, with primiparous cows having a lower mean prevalence (12.2 ± 9.2%) than multiparous cows (26.6 ± 11.3%). Milk BHB concentration (0.095 ± 0.018 mmol/L) and HKL prevalence for primiparous cows were positively associated with formulated prepartum DMI and forage content of the dry cow diet while being negatively associated with formulated postpartum DMI, the major ingredient in the concentrate supplemented through the AMS, and the PMR-to-AMS concentrate ratio. However, multiparous cows' milk BHB concentration (0.12 ± 0.023 mmol/L) and HKL prevalence were positively associated with the length of the previous lactation, milk BHB at dry off, prepartum diet nonfiber carbohydrate content, and the major forage fed on farm, while tending to be negatively associated with feed bunk space during lactation. This is the first study to determine the farm-level risk factors associated with herd-level prevalence of HKL in AMS dairy herds, thus helping optimize management and guide diet formulation to promote the reduction of HKL prevalence.

Predicting CO2 production of lactating dairy cows from animal, dietary, and production traits using an international dataset

Automated measurements of the ratio of concentrations of methane and carbon dioxide, [CH4]:[CO2], in breath from individual animals (the so-called "sniffer technique") and estimated CO2 production can be used to estimate CH4 production, provided that CO2 production can be reliably calculated. This would allow CH4 production from individual cows to be estimated in large cohorts of cows, whereby ranking of cows according to their CH4 production might become possible and their values could be used for breeding of low CH4-emitting animals. Estimates of CO2 production are typically based on predictions of heat production, which can be calculated from body weight (BW), energy-corrected milk yield, and days of pregnancy. The objectives of the present study were to develop predictions of CO2 production directly from milk production, dietary, and animal variables, and furthermore to develop different models to be used for different scenarios, depending on available data. An international dataset with 2,244 records from individual lactating cows including CO2 production and associated traits, as dry matter intake (DMI), diet composition, BW, milk production and composition, days in milk, and days pregnant, was compiled to constitute the training dataset. Research location and experiment nested within research location were included as random intercepts. The method of CO2 production measurement (respiration chamber [RC] or GreenFeed [GF]) was confounded with research location, and therefore excluded from the model. In total, 3 models were developed based on the current training dataset: model 1 ("best model"), where all significant traits were included; model 2 ("on-farm model"), where DMI was excluded; and model 3 ("reduced on-farm model"), where both DMI and BW were excluded. Evaluation on test dat sets with either RC data (n = 103), GF data without additives (n = 478), or GF data only including observations where nitrate, 3-nitrooxypropanol (3-NOP), or a combination of nitrate and 3-NOP were fed to the cows (GF+: n = 295), showed good precision of the 3 models, illustrated by low slope bias both in absolute values (-0.22 to 0.097) and in percentage (0.049 to 4.89) of mean square error (MSE). However, the mean bias (MB) indicated systematic overprediction and underprediction of CO2 production when the models were evaluated on the GF and the RC test datasets, respectively. To address this bias, the 3 models were evaluated on a modified test dataset, where the CO2 production (g/d) was adjusted by subtracting (where measurements were obtained by RC) or adding absolute MB (where measurements were obtained by GF) from evaluation of the specific model on RC, GF, and GF+ test datasets. With this modification, the absolute values of MB and MB as percentage of MSE became negligible. In conclusion, the 3 models were precise in predicting CO2 production from lactating dairy cows.

Effect of Fermented Feeds on Weaned Piglets Experimentally Infected with Escherichia coli

Sixty large white breed piglets aged between 28 and 35 days were randomly assigned to five replicate groups (Bu1, Bu2, Bd1, Bd2, Bs1, Bs2, Lc1, Lc2, C1, and C2) with six pigs per group. The Bu1 and Bu2 groups were fed with wet and dry basal diets, respectively, supplemented with 0.8 mL (6 x 106 colony-forming units (CFU)) of Lactobacillus isolated from burukutu (beverage made from sorghum grains). The Pg1 and Pg2 groups were fed with wet and dry basal diets, respectively, supplemented with 0.8 mL (6 x 106 CFU/mL) of Lactobacillus isolated from pig hindguts. The Bs1 and Bs2 groups were fed with wet and dry basal diets supplemented with 0.8 mL (6 x 106 CFU/mL) of Bacillus subtilis and Bacillus pumilus, respectively. The Lc1 and Lc2 groups were fed with wet and dry basal diets supplemented with 0.8 mL (6 x 106 CFU/mL) of Lactobacillus acidophilus, respectively. Meanwhile, the C1 and C2 groups as the control groups were fed with wet and dry basal diets, respectively. The treatment and control animals were infected with Escherichia coli at 6 mL (1 x 1010 CFU/mL) orally. Aseptically collected fecal samples from the piglets in each group showed significant bacteriological and pathological differences. This study suggested that Lactobacillus species isolated from burukutu, pig hindguts, and industrial probiotics could inhibit colibacillosis.

Growth, survival, digestive activity and respiratory metabolism of Octopus maya juveniles fed with prepared diets.

The effects of two prepared feeds were tested on growth, survival, enzymatic activity, nutritive reserves in the digestive gland and oxygen consumption of Octopus maya juveniles. For the first time, a semihumid paste (HD, control) and a dry diet, in pelleted form (PD, experimental) with the same formulation were used for this species. The experiment lasted for 42 days. Results indicate that growth rates were similar for both diets (p > 0.05); however, survival (70%) was higher with the PD compared to the HD (48%) (p < 0.05). The performance index was higher for octopuses fed the PD (p < 0.05). No differences in acid proteases activity were observed. However, a higher activity of alkaline proteases in the octopuses fed the PD was observed (p < 0.05). Ingestion rate was higher for octopuses fed the PD. Routine energy inversion was similar in both treatments (p > 0.05). A greater energy inversion was observed in octopuses fed the PD, whose active metabolism was double compared to the octopuses fed the HD. Results showed that the PD promoted similar growth compared to the HD diet but favored survival, and a greater investment in the active metabolism, reflected in the apparent heat increase.

Survival and growth of larval Pallid Sturgeon are improved by a live diet

AbstractObjectiveConservation propagation facilities in the upper basin of the Missouri River are currently experiencing inconsistent survival of first‐feeding larval Pallid Sturgeon Scaphirhynchus albus among genetic families (i.e., distinct male–female pairings). The inconsistent survival can have unintended negative consequences for genetic representation of Pallid Sturgeon that are returned to the Missouri and Yellowstone rivers. We conducted a laboratory study designed to determine whether a live diet improves survival and growth of first‐feeding larval Pallid Sturgeon.MethodsFirst‐feeding larval Pallid Sturgeon from three distinct genetic families were assigned to one of the following diets: live first instar brine shrimp (Artemia franciscana) nauplii, an Otohime dry diet, a 50–50% combination of Otohime and live first instar brine shrimp nauplii, or food restricted (no food). Mortality was evaluated at the end of each day and at the end of the trial (21 days after the onset of exogenous feeding), and individual weight (g) was measured at the end of the trial.ResultPallid Sturgeon larvae that received a live diet (either solely live first instar brine shrimp nauplii or the combined diet) experienced higher survival than larvae that were fed solely Otohime. Furthermore, there was statistical evidence that larvae receiving solely live first instar brine shrimp nauplii were heavier at 21 days postexogenous feeding than larvae that were fed either solely Otohime or the combined diet.ConclusionOur results suggest that a live diet can improve survival and growth of first‐feeding larval Pallid Sturgeon at conservation propagation facilities.

Effect of dietary β‐carotene supplementation on growth and antioxidant capability of female swimming crab Portunus trituberculatus

AbstractDietary supplementation with synthetic β‐carotene was investigated in this study to assess its impact on gonad development, antioxidant status, color parameters, and carotenoid composition in adult female swimming crab (Portunus trituberculatus). Four diets, designated as Diet 1 to 4, were formulated to contain 3.07, 53.78, 103.23, and 205.22 mg/kg dry diets of synthetic β‐carotene. The findings revealed the following: (1) No significant differences in body weights or feed utilization were observed, indicating that β‐carotene did not significantly enhance the growth of adult P. trituberculatus. (2) The inclusion of 50–100 mg/kg β‐carotene in the diets led to improvements in antioxidant capacity indicators (T‐AOC, MDA) and immune‐related parameters (AKP, ACP) in both hepatopancreas and hemolymph. (3) Notably, the redness of ovaries and hepatopancreas increased significantly with higher dietary β‐carotene supplementation for color enhancement. In conclusion, incorporating β‐carotene into the diet enhanced the antioxidative capability, nonspecific immunity, and tissue carotenoid contents in adult female P. trituberculatus, and the optimal level of dietary synthetic β‐carotene supplementation for adult female P. trituberculatus was suggested to be around 100 mg/kg.

Effects of weaning time, light regime, and stocking density on growth, condition, survival, and cannibalism rates in northern pike (Esox lucius L.) larvae and early juveniles under intensive culture

In this study, three separate experiments were conducted to optimize the intensive larviculture of pike (Esox lucius L.) under different weaning times, light regimes, and stocking densities. In the first experiment, larvae were fed sequential combinations of live feed (LF), co-feeding with dry starter (DS), and only DS feed for 18 days as follows: 9 days LF followed by 3 days co-feeding and 5 days DS (group A); 6 days LF followed by 3 days co-feeding and 9 days DS (group B); 3 days LF followed by 3 days co-feeding and 12 days DS (group C); and DS alone for 18 days (group D). Fish fed LF had significantly higher growth rates than those fed a dry diet (p&amp;lt; 0.05). Extending the feeding period on LF resulted in a significantly higher growth rate (24.6% d−1), variability (13.5%), and heterogeneity (299.5% d−1) than fish fed a DS. In the second experiment, the effect of the light regime was assessed at eight different levels (L0:D24; L24:D0; L16:D8; L4:D4:L4:D4:L4:D4; L8:D4:L8:D4; L12:D12; L8:D16; and L4:D8:L4:D8). The growth and survival of the larvae increased with increasing light period. Groups exposed to complete light (L24:D0) and 16 h of light (L16:D8) exhibited significantly higher weight gain and specific growth rate (SGR, %) than the other groups. The highest survival was observed in fish reared with complete light (68.5 ± 4.5%) and an L8:D4:L8:D4 light regime (61.4 ± 5.2%). All larvae maintained under L0:D24 died during the experiment. The third experiment tested the effect of the fish density within four experimental groups: 10 ind L−1, 20 ind L−1, 40 ind L−1, and 80 ind L−1. Fish at densities of 20 and 40 ind L−1 had significantly higher weight gain and SGR (%) than those in the other groups. The highest survival was in fish reared with 20 ind L−1 density (72.5 ± 8.5%). Fish at densities of 10 and 80 ind L−1 showed significantly higher cannibalism rates than those in the other groups. These results indicated that weaning time, photoperiod, and stocking density play significant roles in early pike larval performance.

Glycine supplementation can partially restore oxidative stress-associated glutathione deficiency in ageing cats.

Intracellular levels of glutathione, the major mammalian antioxidant, are reported to decline with age in several species. To understand whether ageing affects circulating glutathione levels in cats, blood was sampled from two age groups, < 3 years and > 9 years. Further, to determine whether dietary supplementation with glutathione precursor glycine (GLY) affects glutathione concentrations in senior cats (> 8 years), a series of free GLY inclusion level dry diets were fed. Subsequently, a 16-week GLY feeding study was conducted in senior cats (> 7 years), measuring glutathione, and markers of oxidative stress. Whole blood and erythrocyte total, oxidised and reduced glutathione levels were significantly decreased in senior cats, compared with their younger counterparts (P ≤ 0·02). The inclusion level study identified 1·5 % free GLY for the subsequent dry diet feeding study. Significant increases in erythrocyte total and reduced glutathione were observed between senior cats fed supplemented and control diets at 4 weeks (P ≤ 0·03; maximum difference of 1·23 µM). Oxidative stress markers were also significantly different between groups at 8 (P = 0·004; difference of 0·68 nG/ml in 8-hydroxy-2'-deoxyguanosine) and 12 weeks (P ≤ 0·049; maximum difference of 0·62 nG/mG Cr in F2-isoprostane PGF2α). Senior cats have lower circulating glutathione levels compared with younger cats. Feeding senior cats a complete and balanced dry diet supplemented with 1·5 % free GLY for 12 weeks elevated initial erythrocyte glutathione and altered markers of oxidative stress. Dietary supplementation with free GLY provides a potential opportunity to restore age-associated reduction in glutathione in cats.

Effects of dietary tryptophan levels on growth performance, plasma profile, intestinal antioxidant capacity and growth related genes in rainbow trout (Oncorhynchus mykiss) fingerlings

A 56-day feeding trial was carried out to evaluate the dietary tryptophan requirements for rainbow trout, Oncorhynchus mykiss using 360 fingerlings (1.75 ± 0.02 g/fish; 5.3 ± 0.27 cm/fish) randomly distributed into 6 tanks with six treatments and three replicates. Six isoenergetic (20.9 kj g−1 energy) and isonitrogenous (450 g kg−1 protein) diets with increasing level of tryptophan amino acids (0.40, 1.60, 2.80, 4.0, 5.20 and 6.40 g kg−1) were prepared. Fish were hand-fed twice daily at 09:00 and 17:00 h at a rate of 5% body weight per day. The results revealed that growth parameters were significantly improved with each incremental level up to 4.0 g kg−1 tryptophan containing diet. Similarly high body protein, intermediate body fat and low moisture were observed in fish offered 4.0 g kg−1 dietary tryptophan, whereas body ash content did not produce any significant (p˃0.05) difference, except at lowest fed groups. Significant (p < 0.05) improvement in hemoglobin (Hb) level, hematocrit (Hct) content, red blood cell (RBC) count, total protein, alkaline phosphatase (ALP), albumin and globulin were also noted at 4.0 g kg−1 tryptophan fed diet. Declining pattern in alanine aminotransaminase (ALT) and aspartate aminotransaminase (AST) enzymes were observed up to the optimum level. Intestinal enzymes and antioxidant variables showed a significant upward trend (p < 0.05) in fish fed diets up to 4.0 g kg−1, except amylase and malondialdehyde (MDA) which showed a declined pattern across the treatments. Relative gene expression level of TOR and 4E-BP1 in the muscle were significantly (p < 0.05) high with increasing of dietary tryptophan up to a certain level. Based on the quadratic regression analysis of growth parameters and activity of hemato-biochemical enzymes, the optimum tryptophan requirement of the fish was estimated to be 4.0 g kg−1 of dry diet, corresponding to 8.89 g kg−1 of dietary protein.