Differential frontal alpha oscillations and mechanisms underlying loss of consciousness: a comparison between slow and fast propofol infusion rates.

Mechanisms underlying loss of consciousness following propofol administration remain incompletely understood. The objective of this study was to compare frontal lobe electroencephalography activity and brainstem reflexes during intravenous induction of general anaesthesia, in patients receiving a typical bolus dose (fast infusion) of propofol compared with a slower infusion rate. We sought to determine whether brainstem suppression ('bottom-up') predominates over loss of cortical function ('top-down'). Sixteen ASA physical status-1 patients were randomly assigned to either a fast or slow propofol infusion group. Loss of consciousness and brainstem reflexes were assessed every 30 s by a neurologist blinded to treatment allocation. We performed a multitaper spectral analysis of all electroencephalography data obtained from each participant. Brainstem reflexes were present in all eight patients in the slow infusion group, while being absent in all patients in the fast infusion group, at the moment of loss of consciousness (p = 0.010). An increase in alpha band power was observed before loss of consciousness only in participants allocated to the slow infusion group. Alpha band power emerged several minutes after the loss of consciousness in participants allocated to the fast infusion group. Our results show a predominance of 'bottom-up' mechanisms during fast infusion rates and 'top-down' mechanisms during slow infusion rates. The underlying mechanisms by which propofol induces loss of consciousness are potentially influenced by the speed of infusion.

Radiative Energy Budgets in a Microbial Mat Under Different Irradiance and Tidal Conditions.

Irradiance and temperature variations during tidal cycles modulate microphytobenthic primary production potentially by changing the radiative energy balance of photosynthetic mats between immersion and emersion and thus sediment daily net metabolism. To test the effect of tidal stages on the radiative energy budget, we used microsensor measurements of oxygen, temperature, and scalar irradiance to estimate the radiative energy budget in a coastal photosynthetic microbial mat during immersion (constant water column of 2 cm) and emersion under increasing irradiance. Total absorbed light energy was higher in immersion than emersion, due to a lower reflectance of the microbial mat, while most (> 97%) of the absorbed light energy was dissipated as heat irrespective of tidal conditions. During immersion, the upward heat flux was higher than the downward one, whereas the opposite occurred during emersion. At highest photon irradiance (800 µmol photon m-2 s-1), the sediment temperature increased ~ 2.5 °C after changing the conditions from immersion to emersion. The radiative energy balance showed that less than 1% of the incident light energy (PAR, 400-700 nm) was conserved by photosynthesis under both tidal conditions. At low to moderate incident irradiances, the light use efficiency was similar during the tidal stages. In contrast, we found an ~ 30% reduction in the light use efficiency during emersion as compared to immersion under the highest irradiance likely due to the rapid warming of the sediment during emersion and increased non-photochemical quenching. These changes in the photosynthetic efficiency and radiative energy budget could affect both primary producers and temperature-dependent bacterial activity and consequently daily net metabolism rates having important ecological consequences.

Intertidal microphytobenthic primary production and net metabolism of a tropical estuary.

Tidal flats are inhabited by benthic microalgae (microphytobenthos, MPB) supporting important ecosystem functions and services. Studies on MPB have been conducted mainly in temperate systems, despite that the majority of tidal flats on Earth are found in the tropical zone (∼55%). To fill this gap of knowledge and evaluate the contribution of tidal flat MPB in one of the most productive estuaries worldwide, sediment cores were collected from 14 stations along the inner Gulf of Nicoya (Costa Rica) at different tidal heights or sea levels (SL) from October 2013 to April 2014. MPB abundance, using chlorophyll a (Chla) biomass as a proxy, and net primary production (PN) and dark respiration (RD), using O2 microsensors, were measured together with other sediment biogeochemical variables in muddy and sandy sediments. Landsat-8 satellite images were used to map the extension of tidal flats and the abundance of MPB using Normalized Difference Vegetation Index (NDVI) as a proxy. Chla ranged from 0.45 to 7.45 µg cm-2, with higher concentrations observed closer to the river mouth. There was no significant correlation between Chla and SL nor with any other sediment physicochemical variable. MPB abundance estimated by remote sensing displayed considerable spatial heterogeneity, both within and among tidal flats, and clear seasonal differences with higher abundance during the rainy season. PN ranged between 0.8 and 8.6 mmol O2 m-2 h-1, being positively correlated to SL and to the accumulated rain during 30 days prior to the sampling date and inversely to the mean irradiance at noon during the previous month. Daily net community metabolism estimated from PN and RD data and converted to carbon fixation rates indicates that the unvegetated tidal flats of the gulf contribute as much as the total input of allochthonous C from the Tempisque River. However, the results presented here have to be confirmed with direct measurements of C transfer, including the contribution of the adjacent mangrove system. Such studies are crucial to assess the local, regional and global importance of production and other ecosystem services by MPB in tropical areas.

Evaluation of carryover effects of dietary lysine intake by Cobb 500 broiler breeder hens.

Two experiments were conducted to examine the progeny performance of broiler breeder (BB) hens fed diets differing in digestible lysine (dLys). A total of 240 Cobb 500 BB pullets and 40 cockerels, 20 wk of age, were used for each of 2 experiments. In experiment 1, treatment diets were fed from 35 to 45 wk of age. Treatment 1 and 2 diets were formulated with common feed ingredients and BB had dLys daily intakes of 1,200 (IDL-1,200) and 1,010 mg/hen per d (ID-1,010), respectively. Treatments 3 and 4 were composed of semipurified diets formulated to dLys intakes of 1,010 (SPL-1,010) and 600 mg/hen per d (SP-600), respectively. In experiment 1, chick weight at hatch was lower (P < 0.05) for those that came from the SP-600 and SPL-1,010-fed hens, but 42 and 56 d BW was similar for all treatments. Improvements (P < 0.10) in feed conversion ratio were seen at 42 and 56 d for chicks from ID-1,010-fed hens compared with IDL-1,200 hens. For experiment 2, diets were fed to BB hens from 24 to 42 wk of age. Treatment 1 was composed of corn-soybean meal and formulated to a dLys intake of 1,000 mg/hen per d (CS-1,000). Treatments 2, 3, and 4 had inclusion of 25% distillers dried grains with solubles (DDGS) with dLys intake levels of 1,000 (DDGS-1,000), 800 (DDGS-800), and 600 (DDGS-600) mg/hen per d, respectively. Progeny performance was evaluated from eggs collected at wk 26, 31, and 36. Chick hatch weight was similar for all 3 hatches. Chicks from 26-wk-old BB hens and fed DDGS-600 diets resulted in lower (P < 0.05) BW, carcass weight, and breast weight, and higher (P < 0.05) back half (drumsticks and thighs) yield, at 42 d of age. Growout studies performed on eggs laid during wk 31 and 36 revealed no effect on growth or carcass parameters. In conclusion, the results from experiments 1 and 2 may not be comparable, and therefore, the impact on progeny performance needs to be further evaluated.

Metabolic and hormonal responses of growing modern meat-type chickens to fasting.

1. The present study compared the effects of fasting on circulating concentrations of glucose, insulin and glucagon in male and female modern meat-type chickens (Ross 708) at three ages (19 d, 33 d and 47 d). 2. Plasma concentrations of glucose were reduced by fasting with reductions of 24.9% (19-d-old), 22.6% (33-d-old) and 17.9% (47-d-old) in broiler chickens fasted for 12 h. 3. Plasma concentrations of insulin decreased with fasting. For instance, circulating concentrations of insulin declined after 6 h of fasting by 45.7%, 54.7% and 50.0%, respectively, in 19-d-old, 33-d-old and 47-d-old broiler chickens. 4. Plasma concentrations of glucagon were increased by fasting. Plasma concentrations of glucagon were elevated by 3.79% (19-d-old), 3.51% (33-d-old) and 3.79% (47-d-old) with 6 h of fasting and remained elevated with 12 h, 18 h and 24 h of fasting.

Interactive effects of age, sex, and strain on apparent ileal amino acid digestibility of soybean meal and an animal by-product blend in broilers.

The objectives of this study were to determine if age, sex, and strain of broilers affect the apparent ileal amino acid digestibility (AID) of soybean meal and an animal by-product blend. Chicks from 2 broiler strains, 1 commercially available and the other in the test phase, were obtained from a common hatchery, feather-sexed, and placed into floor pens. The birds received common diets while on floor pens. Birds were transferred to metabolism crates for 2 ileal digestibility trials conducted at 3 and 6 wk of age. Two semipurified diets were formulated with each of the feed ingredients providing all of the amino acids (AA) in the diets. Diets were formulated to contain 20% CP, with chromic oxide added to the diet at 0.30% as the indigestible marker. The experimental diets were fed for a 72-h period after an overnight fast to 8 replicate cages of 5 birds per cage. Upon completion of the experimental periods (i.e., d 22 and 43), birds were euthanized and ileal digesta samples were collected and pooled by pen, frozen, lyophilized, and analyzed for AA and chromium concentrations. For soybean meal, no main effects were observed for age, sex, or strain; however, significant (P ≤ 0.05) 3-way interactions were observed for several dispensable and indispensable AA. Statistical analyses of these interactions indicate the AID of soybean meal may be different for 42-d males of the test strain. For the animal by-product blend, only main effects were significant for each AA, with the exception of Ile and Tyr. Main effect of strain was observed for most of the AA, showing that the commercially available strain had higher AID than the test strain. Also, significant main effect of age indicated that the AID for animal by-product blend was higher at 42 d than at 21 d. Evaluation of these 2 ingredients showed that age, sex, and strain may affect digestibility of feedstuffs and should be considered independently or interactively, for some cases, in future investigations as sources of variation in AA digestibility.

Dietary influence of digestible lysine concentration on Cobb 500 hen broiler breeder reproductive performance.

A study was conducted to examine the reproductive parameters of Cobb 500 broiler breeder hens fed 2 different types of diets varying in digestible lysine concentration. In total, 240 Cobb 500 broiler breeder pullets were placed in individual cages and given experimental diets from 35 to 45 wk of age. Treatments 1 and 2 were diets formulated using only commercially available feed ingredients and consisted of digestible lysine intakes of 1,200 (IDL) and 1,010 mg/hen per day (ID). Treatments 3 and 4 consisted of semipurified diets with the inclusion of l-glutamic acid to maintain isonitrogenous conditions with digestible lysine intakes of 1,010 (SPL) and 600 mg/hen per day (SP). Hens fed the SPL and SP diets had lower hen-day egg production than hens fed the ID diet, with hens receiving the IDL diet yielding intermediate values. Hens fed the SP diet had the lowest (P < 0.05) egg weight, but no differences were observed among dietary treatments for egg specific gravity. Fertility and hatchability of eggs set were lowest (P < 0.05) for hens fed the SPL dietary treatment. No differences were observed for early and middle embryonic mortality, contaminated, or pipped eggs. Late embryonic mortality was observed to be higher (P < 0.05) in hens fed the SP diet. A decrease in the daily intake of digestible lysine appeared to improve broiler breeder reproductive performance when hens were fed a semipurified diet. In contrast, the same effect was not observed when hens were fed a standard industry-type diet that contained less lysine.

Sodium chloride concentration affects yield, quality, and sensory acceptability of vacuum-tumbled marinated broiler breast fillets.

The objective of this experiment was to determine the effect of sodium chloride concentration on yield, instrumental quality, and sensory acceptability of broiler breast meat that was vacuum tumbled with a 15% solution (over green weight) for 30 min. Different concentrations (0, 0.25, 0.50, 0.75, 1.00, 1.25, and 1.50%) of NaCl (salt) and 0.35% sodium tripolyphosphate were included in the marinade solution. After marinating, breast fillets were evaluated for marination yields, pH, surface color, cooking loss, tenderness, expressible moisture, proximate composition, purge loss, sodium content, and sensory acceptability. As salt concentration increased, CIE L* decreased linearly, with a concentration of 0.75% having lower (P < 0.05) CIE L* values when compared with the control, 0, and 0.25% NaCl treatments. In addition, there was a linear and quadratic decrease (P < 0.05) in shear force as salt concentration increased, with no further decrease (P < 0.05) when greater than 0.75% NaCl was used. Cooking yield increased (P < 0.05) as the salt concentration increased to 1.0%. All marinated treatments were preferred (P < 0.05) over the control treatment, and all treatments marinated with at least 0.50% sodium chloride had an average rating of like moderately. Cluster analysis indicated that consumer groups varied in their preference of broiler breast meat treatments and that samples that were marinated with between 0.5 to 1.0% NaCl were acceptable to the majority of consumers. Marination with 0.75% NaCl was sufficient to maximize yields and decrease lightness (L*) in vacuum-tumbled, marinated broiler breast that is sold raw, but 1.0% NaCl could be used in a precooked product because it minimizes cook loss. In addition, use of 0.50% NaCl had minimal effects on yields, color, and sensory acceptability when compared with products that were marinated with greater concentrations of NaCl.

Protein expression in pectoral skeletal muscle of chickens as influenced by dietary methionine.

Effects of dietary methionine (Met) on pectoralis muscle development and the effect that Met as a nutritional substrate has on protein expression of skeletal muscle cells of pectoralis muscle of chickens were evaluated in this study. Broiler chickens received a common pretest diet up to 21 d of age and were subsequently fed either a low (LM) or high Met (HM) diet (0.41 vs. 0.51% of diet) from 21 to 42 d of age. Dietary deficiency was shown in vivo judging by the depression in breast meat weight and yield when broilers were fed the LM diet. Global protein expression was analyzed by quantitative high-performance liquid chromatography nanospray ionization tandem mass spectrometry. Up- and downregulated proteins were analyzed via Ingenuity Pathways Analysis to identify the metabolic pathways affected. Four canonical pathways related to muscle development were identified as being differentially regulated between LM- and HM-fed chickens. These pathways included the citrate cycle and calcium, actin cytoskeleton, and clathrin-mediated endocytosis signaling. The HM diet may have allowed for increased muscle growth by an increased availability of nutrients to muscle cells. Although the Met supplementation was associated with enhanced breast muscle growth, contraction fiber concentrations in muscles decreased and were associated with a lower calcium transportation rate and sensitivity and with a lower energy supply. It is further suggested that increased muscle protein deposition, that was induced by Met supplementation, may have been largely due to sarcoplasmic rather myofibrillar hypertrophy.

Understanding the interactive effects of dietary leucine with isoleucine and valine in the modern commercial broiler.

A study was conducted to understand the relationship among dietary branched-chain amino acids (BCAA) on the performance of Ross 344 × 708 male broilers. A total of 2,592 d-old male chicks were randomly placed into 144-floor pens according to a 23 full factorial central composite design (CCD) with 20 treatments (14 treatments and 6 center points). Each treatment consisted of varying digestible Ile:Lys (52 to 75), Val:Lys (64 to 87), and Leu:Lys (110 to 185) ratios. Birds and feed were weighed at 20 and 34 d of age to determine body weight gain (BWG), feed intake, and feed conversion ratio (FCR). At 35 d of age, feather amino acid composition and carcass characteristics were evaluated. Data were analyzed as CCD using the surface response option of JMP v. 15. Body weight gain (1,332 g; P < 0.001; R2 = 0.93) and FCR (1.54; P = 0.002; R2 = 0.88) were optimized at the lowest Leu:Lys ratio (110) with moderate Val:Lys (78 to 79) and Ile:Lys (65 to 66) ratios. Poorer BWG and FCR were observed as Leu:Lys ratio increased while increasing Val:Lys and Ile:Lys ratios alleviated the poor performance. Carcass (71.5%; P = 0.031; R2 = 0.76) and breast yield (26.7%; P < 0.001; R2 = 0.96) were maximized at the highest Leu:Lys ratio. This effect was complemented by increasing Ile:Lys ratio beyond 68. Lower Ile:Lys and Val:Lys ratios were required to maximize carcass and breast yield at the lowest Leu:Lys ratio. However, this strategy yielded less meat than providing a high Leu:Lys ratio diet. Dietary BCAA had little effect on altering the composition of feather protein and amino acid (P > 0.10). These results suggest that optimum BCAA ratios to Lys may vary depending on response criteria and demonstrate the importance of maintaining proper Val and Ile ratios centered on dietary Leu. Live performance can be optimized in diets with low Leu:Lys ratios; however, meat yield can be enhanced by increasing dietary Leu:Lys along with Ile:Lys ratios.

Microphytobenthos spatio-temporal dynamics across an intertidal gradient using Random Forest classification and Sentinel-2 imagery.

Microphytobenthos (MPB) provides important ecosystem functions and services, contributing significantly to the total primary production in shallow coastal ecosystems. However, determining the factors that regulate the seasonal changes of MPB and its distribution patterns at larger scales is hindered by the considerable spatial and temporal variability in these environments. Here, we studied the dynamics of intertidal MPB biomass, cover, and net growth rates in a south European tidal flat (Cadiz Bay, Spain) over a four-year period using the Normalized Difference Vegetation Index (NDVI) calculated from Sentinel-2 satellite images. Pixels dominated by different benthic communities (MPB, Zostera sp., Caulerpa sp. and green macroalgae) were identified at a 10-m resolution using a Random Forest (RF) machine learning classification algorithm. MPB dominated the intertidal zone. MPB cover did not show a clear seasonal pattern and was clearly higher in the middle of the intertidal range of sea level. Despite interannual variability, MPB biomass was always higher during winter, coinciding with observations from other low latitude intertidal flats with temperate climate, and in the upper-middle intertidal. Net rates of MPB biomass change, calculated from the differences in MPB NDVI over time, showed maximal net growth rates from autumn to winter and maximum loss rates during spring and summer, although with high variability. Our study demonstrates that RF algorithms allow mapping MPB and other intertidal communities from Sentinel-2 multispectral satellite imagery accurately obtaining invaluable information from large areas at very high spatio-temporal resolution. The dissimilarities observed in the patterns of MPB variables over time or sea level, indicate differences in their ecological regulation, still largely unknown both here and in other temperate climate intertidal flats. High resolution remote sensing can aid in their detailed and systematic study producing a more integrated view of these systems and contributing to their science-based management and conservation.

Microbial community fingerprinting by differential display-denaturing gradient gel electrophoresis.

Complex microbial communities exhibit a large diversity, hampering differentiation by DNA fingerprinting. Herein, differential display-denaturing gradient gel electrophoresis is proposed. By adding a nucleotide to the 3' ends of PCR primers, 16 primer pairs and fingerprints were generated per community. Complexity reduction in each partial fingerprint facilitates sample comparison.

Broiler genetic strain and sex effects on meat characteristics.

A randomized complete block design within a factorial arrangement of treatments was used to evaluate the effect of strain and sex on carcass characteristics, meat quality, and sensory acceptability. Two broiler strains were reared: a commercially available strain (strain A) and a strain currently in the test phase (strain B) that has been genetically selected to maximize breast yield. Broilers were harvested in a pilot scale processing plant using commercial prototype equipment at 42 d of age. Carcasses were deboned at 4 h postmortem. The left half of each breast was evaluated for pH, color, cooking loss, shear force, and proximate analysis. The right side of each breast was used for consumer acceptability testing. Thigh meat was evaluated for proximate composition. No interactions were observed throughout the study. Male broilers had a higher (P < 0.05) live BW, carcass weight, and breast weight and lower (P < 0.05) dressing percentage and breast meat yield when compared with females. Broilers from strain B presented a higher (P < 0.05) breast yield and dressing percentage than those broilers corresponding to the commercially available broiler strain. At 24 h postmortem, female broilers presented a lower ultimate pH and higher Commission internationale de l'éclairage yellowness values (ventral side of the pectoralis major) when compared with male broilers. On average, no differences existed (P > 0.05) among treatments with respect to pH decline, cooking loss, shear values, and proximate composition. In addition, no differences (P > 0.05) existed among breast meat from the different strains with respect to consumer acceptability of appearance, texture, flavor, and overall acceptability, but breast meat from strain B was slightly preferred (P < 0.05) over that of strain A with respect to aroma. However, breast meat from both strains received scores in the range of "like slightly to like moderately." Overall data suggest that all treatments yielded high quality breast and thigh meat and strain cross did not present variability in terms of consumer acceptability.

Apparent metabolizable energy needs of male and female broilers from 36 to 47 days of age.

Two experiments were conducted to examine AME(n) responses of Ross × Ross 708 male and female broilers from 36 to 47 d of age. In each experiment, 1,440 male and female broilers were randomly distributed into 96 floor pens (15 birds/pen; 8 replicate pens/treatment) sexed separately and were fed 6 levels of AME(n) ranging from 3,140 to 3,240 kcal/kg in increments of 20 kcal of AME(n)/kg, resulting in a 6 × 2 factorial arrangement of treatments. Body weight gain, feed intake, feed conversion, AME(n) intake, AME(n) intake per BW gain, plasma 5-triiodothyronine and thyroxine concentrations, mortality, and meat yields were evaluated during experimentation. Average temperature and RH were 20.3°C and 49.0% for experiment 1 and 26.1°C and 66.6% for experiment 2. In experiment 1, broilers fed progressive additions of AME(n) had lower (P ≤ 0.02) feed intake, feed conversion, and caloric conversion. Progressive increments of AME(n) did not influence plasma 5-triiodothyronine and thyroxine concentrations, carcass yield, or breast meat yield. No AME(n) × sex interactions were observed in experiment 1. In experiment 2, AME(n) × sex linear interactions (P ≤ 0.04) were observed for BW gain, caloric conversion, carcass weight, and total breast weight. Male broilers responded more to higher AME(n) levels than did female broilers. These data indicate that AME(n) needed for growth performance of broilers from 36 to 47 d of age differed between experiments.

Determination of the fourth and fifth limiting amino acids in broilers fed on diets containing maize, soybean meal and poultry by-product meal from 28 to 42 d of age.

1. Valine (Val) is considered the 4th limiting amino acid for broilers fed on diets containing ingredients from vegetable origin. However, Val and Isoleucine (Ile) may be co-limiting for broilers fed on diets containing animal protein meals. An experiment was conducted to examine growth responses and meat yield of broilers provided diets varying in digestible Val (dVal) and digestible Ile (dIle) concentrations from 28 to 42 d of age. 2. Eight experimental diets varying in dVal (dVal to dLys ratios from 0·66 to 0·76) and dIle (dIle to dLys ratios from 0·57 to 0·67) were studied; digestible Lysine (Lys) was formulated to 9·9 g/kg in all diets. 3. Broilers fed on a negative control (NC) diet supplemented with crystalline Val (L-Val) and crystalline Ile (L-Ile), dVal to dLys = 0·76 and dIle to dLys = 0·67, grew faster and had higher breast meat yield than birds fed on NC + L-Ile (dVal to dLys = 0·66 and dIle to dLys = 0·67), NC + L-Val (dVal to dLys = 0·76 and dIle to dLys = 0·57), and NC + reduced L-Val and L-Ile (dVal to dLys = 0·71 and dIle to dLys = 0·62). 4. Feeding broilers on the NC + L-Val and L-Ile (dVal to dLys = 0·76 and dIle to dLys = 0·67) diets gave similar BW gain, carcase weight and yield and total breast meat weight and yield to birds fed on the positive control-fed broilers with no added L-Val and L-Ile (dVal to dLys = 0·76 and dIle to dLys = 0·67). 5. These results indicate that Val and Ile are co-limiting in diets containing poultry by-product meal.

Effects of feeding distillers dried grains with solubles to broilers from 0 to 28 days posthatch on broiler performance, feed manufacturing efficiency, and selected intestinal characteristics.

This study evaluated the effect of 2 levels (0 vs. 8%) of distillers dried grains with solubles (DDGS) in a starter broiler diet (0 to 14 d; 45 replicates/treatment) after these same birds were subsequently fed a grower diet (14 to 28 d) with either 0, 7.5, 15, 22.5, or 30% DDGS (9 replicates/treatment). Ross×Ross 308 male broilers were used in this experiment, and evaluation criteria consisted of feed mill parameters, broiler growth, relative liver weight, ileal viscosity, and cecal content count of Clostridium perfringens and Escherichia coli analyzed by both selective media and real-time PCR. Increased inclusion of DDGS resulted in a nonlinear response for production rate (P<0.05), conditioner energy usage (P<0.01), and pellet mill energy usage (P<0.05). Increasing DDGS resulted in a linear decrease in pellet quality (P<0.001) and an increase (P<0.001) in total fines. Inclusion of DDGS decreased (P<0.001) energy usage at the pellet mill and decreased (P<0.05) bulk density of the diets. The DDGS levels fed during the starter phase (0 vs. 8%) had no effect on the broilers at 14 or at 28 d of age. Increasing DDGS inclusion levels during the grower phase resulted in a linear decrease (P<0.001) in BW gain and liver relative weight (P<0.001). A DDGS starter×grower interaction (P<0.05) was observed for feed consumption, in which birds that consumed no DDGS during the starter phase exhibited a decrease in feed consumption with the higher inclusion levels of DDGS during the grower phase, whereas birds that received 8% DDGS during the starter phase were unaffected by DDGS inclusion level in the grower phase. Feed conversion, mortality, ileal viscosity, and cecal C. perfringens and E. coli concentrations were unaffected by DDGS level in the grower diet. The feed intake response suggests a beneficial effect of exposing broiler chicks to DDGS if inclusion levels of 22.5% or higher are to be fed after 14 d of age. However, the data suggest that the young broiler can be negatively affected with inclusion levels of 15% DDGS or higher up to 28 d of age.

Effects of in ovo injection of L-carnitine on hatchability and subsequent broiler performance and slaughter yield.

Effects of in ovo injection of L-carnitine on the hatchability, grow-out performance, and slaughter yield of Ross x Ross 308 broilers from a young breeder flock were determined through 48 d of age. Fertilized eggs were injected in the amnion with L-carnitine (0.5, 2.0, or 8.0 mg dissolved in 100 microL of a commercial diluent) on d 18 of incubation using an automated egg injector. Three control groups (noninjected and injected with or without diluent) were also included. Hatchability and hatch rate of fertilized eggs were assessed. Furthermore, subsequent mortality, BW gain, feed intake per bird, and feed conversion were determined through 46 d posthatch. On d 47, live body, carcass, and abdominal fat pad weights, along with the weights of all major commercial cuts including the thigh, drumstick, wings, and breast muscles, were determined. Individual doses of supplemental L-carnitine had no significant effect on the hatchability or rate of hatch of fertilized eggs; however, significant trends were noted for increased hatchability and length of egg incubation in conjunction with increases in L-carnitine dose. Nevertheless, there were no significant treatment effects on any of the grow-out performance or slaughter yield parameters investigated. In conclusion, although increasing the levels of L-carnitine added to commercial vaccine diluent between 0.5 and 8.0 mg/100 microL for commercial in ovo injection did not significantly influence subsequent broiler grow-out performance or slaughter yield, L-carnitine dosages above those used in this study have the potential for significantly increasing incubation length and hatchability of broiler hatching eggs.

Dietary inclusion level effects of distillers dried grains with solubles on broiler meat quality.

A completely randomized design with 7 replications (n = 7, treatments = 5 with 8 subsamples per treatment) was used to evaluate the effects of feeding various levels of distillers dried grains with solubles (DDGS; 0, 6, 12, 18, and 24%) on broiler breast and thigh meat quality. Broilers were harvested in a pilot scale processing plant with commercial prototype equipment at 42 d of age. The right half of each breast was evaluated for pH, instrumental color, cooking loss, proximate analysis, and tenderness. The left half of each breast was used for consumer acceptability testing. Thigh meat was evaluated for proximate composition, fatty acid composition, and TBA reactive substances. Breast meat from broilers that were fed DDGS had a higher (P < 0.05) pH than those from the control diet. In addition, the 18 and 24% DDGS treatments yielded breast meat with higher (P < 0.05) pH values than the 6% DDGS treatment. No differences existed (P > 0.05) among breast meat from the different treatments with respect to cooking loss, instrumental color, and consumer acceptability, but breast meat from the control (0% DDGS) treatment had slightly lower (P < 0.05) shear force than breast meat from the 18 and 24% DDGS treatments. In addition, no differences (P > 0.05) existed among proximate composition of breast and thigh meat from the control and DDGS treatments. As DDGS concentration increased, there was a linear increase (P < 0.05) in linoleic and polyunsaturated fatty acids, which indicates a greater potential for lipid oxidation. The TBA reactive substances values were greater (P < 0.05) for the 18 and 24% DDGS treatments at d 5 when compared with the control and 6% DDGS treatments, which indicates increased oxidation. Overall, data suggest that all treatments yielded high-quality breast meat and that thigh meat quality was similar among treatments containing 0 to 12% DDGS, but higher inclusion levels led to thigh meat that was more susceptible to oxidation.

Effects of in ovo injection of L-carnitine on subsequent broiler chick tissue nutrient profiles.

Effects of in ovo injection of L-carnitine on BW and the moisture and nutrient biochemical concentrations of various organs and muscles of Ross x Ross 308 broiler chicks, hatched from eggs laid by a 28-wk-old breeder flock, were determined through 48 d posthatch. Eggs containing live embryos were injected in the amnion with L-carnitine (0.5, 2.0, or 8.0 mg dissolved in 100 microL of a commercial diluent) on d 18 of incubation using an automated egg injector. Three control groups (noninjected and injected with or without diluent) were also included. On d 0, 3, 10, 28, and 48 posthatch, bird BW and the proportional weights and moisture concentrations of various organs and muscles were determined. Glycogen, glucose, protein, and fat concentrations were also determined in certain tissue samples. Bird BW; proportional liver weight; breast, thigh, and gastrocnemius muscle moisture; liver glycogen, glucose, and protein concentrations; and breast and thigh muscle fat and protein concentrations changed with posthatch bird age. Liver glucose on d 0 and pipping muscle moisture on d 3 posthatch were significantly affected by treatment. In comparison to eggs injected with commercial diluent with no added L-carnitine, liver glucose was reduced by the injection of diluent containing either 0.5 or 8.0 mg of L-carnitine, and pipping muscle moisture was increased by the injection of commercial diluent containing either 0.5 or 2.0 mg of L-carnitine. The modified concentrations of the 2 parameters in response to these treatments were not different from those in noninjected control eggs. In conclusion, L-carnitine added to commercial vaccine diluent at levels between 0.5 and 8.0 mg/100 microL for the commercial injection of broiler hatching eggs may decrease liver glucose and increase pipping muscle moisture concentrations of chicks on d 0 and 3 posthatch, respectively, so that their levels are commensurate with noninjected controls.

Digestible lysine requirements of male broilers from 28 to 42 days of age.

Research addressing digestible Lys requirement data of modern broilers from 4 to 6 wk of age is limited. Male broilers (1,632 Ross×Ross TP16 and 3,000 Cobb×Cobb 700) were used in separate experiments to determine the digestible Lys requirements from 28 to 42 d. In each experiment, 2 diets (dilution and summit) consisting of corn, soybean meal, animal protein meal, and peanut meal were formulated to be adequate in all other amino acids. The dilution and summit diets were blended to create 9 titration diets. A control diet formulated to contain corn, soybean meal, and animal protein meal as the primary ingredients was used for comparison with the titration diets. Body weight gain, feed intake, digestible Lys intake, digestible Lys intake:BW gain, feed conversion, mortality, carcass yields, and physiological measurements were assessed during experimentation. Digestible Lys requirements were estimated using a quadratic broken-line model. In experiment 1, the digestible Lys requirement for male Ross×Ross TP16 broilers was determined at 0.988, 1.053, 0.939, and 0.962%, respectively, for BW gain, feed conversion, carcass weight, and total breast meat weight. In experiment 2, the digestible Lys requirement for male Cobb×Cobb 700 broilers ranged from 0.965, 1.012, 1.029, 0.987, and 0.981%, respectively, for 28- to 42-d BW gain, feed conversion, carcass weight, total breast meat weight, and total breast meat yield. Digestible Lys requirements for male Ross×Ross TP16 and Cobb×Cobb 700 broilers were estimated at 1.001 and 0.995%, respectively, based upon averages of live performance and meat yield responses. Both strains required the highest requirement estimate of digestible Lys to optimize feed conversion.