Maintenance Level Of Feeding Research Articles

Intramuscular Fatty Acids in Meat Could Predict Enteric Methane Production by Fattening Lambs.

Simple SummaryThe rearing of ruminant animals is an environmental issue related to greenhouse gas emissions, mainly methane. In the current study, a regression analysis was carried out to obtain a regression equation able to successfully estimate methane production of lambs fattened under intensive feeding systems from their meat fatty acid profile and average body weight during the fattening period. The optimized model exhibited high precision, accuracy and reproducibility. It showed a clear relationship between methane emissions and the fatty acid profile of lamb meat. Our predictive model indicates that fatty acid contents in intramuscular fat could be used to establish the environmental footprint of meat from ruminants.Methane (CH4) emissions pose a serious problem for the environmental sustainability of ruminant production. The aim of the present study was to explore the usefulness of the intramuscular fatty acid (FA) profile to estimate CH4 production of lambs fattened under intensive feeding systems. A statistical regression analysis of intramuscular FA derived from ruminal metabolism was carried out to assess the best predictive model of CH4 production (g/d) in lambs fed with different diets. CH4 was calculated with three distinct equations based on organic matter digestibility (OMD) at maintenance feeding levels. The OMD of the experimental diets was determined in an in vivo digestibility trial by means of the indicator method. Regression models were obtained by stepwise regression analysis. The three optimized models showed high adjusted coefficients of determination (R2adj = 0.74–0.93) and concordance correlation coefficients (CCC = 0.89–0.98), as well as small root mean square prediction errors (RMSPE = 0.29–0.40 g/d). The best single predictor was vaccenic acid (trans-11 C18:1), a bioactive FA that is formed in the rumen to a different extent depending on dietary composition. Based on our data and further published lamb research, we propose a novel regression model for CH4 production with excellent outcomes: CH4 (g/d) = −1.98 (±1.284)–0.87 (±0.231) × trans-11 C18:1 + 0.79 (±0.045) × BW (R2adj = 0.97; RMSPE = 0.76 g/d; CCC = 0.98). In conclusion, these results indicate that specific intramuscular FA and average BW during fattening could be useful to predict CH4 production of lambs fed high concentrate diets.

Prediction of Metabolizable Energy Concentrations of Herbage in the Qinghai–Tibetan Plateau Using Tibetan Sheep Digestibility Data

Simple SummaryRobust prediction of herbage nutritive value is critical to improve grazing efficiency and to maintain a sustainable environment in the Qinghai–Tibet Plateau. A range of prediction equations were developed in the present study using sheep digestibility data which can produce an accurate estimation of herbage nutritive value. The adaptation of the present equations is expected to benefit local farmers with higher economical return and to improve the fragile ecological systems the Qinghai–Tibet Plateau.Due to its extremely harsh environment, including high altitude, hypoxia, long cold season, and strong ultraviolet radiation in the Qinghai–Tibet Plateau (QTP), herbage species and nutritional value of the pasture may differ considerably from elsewhere across the world. The aim of the present study was to develop biologically relevant equations for estimating the metabolizable energy (ME) value of fresh native herbages in the QTP using digestibility variables and chemical concentrations in the herbage offered to Tibetan sheep at the maintenance level. A total of 11 digestibility trials (6 sheep/trial) were performed in different grazing seasons from 2011 to 2016. The herbage was harvested daily in the morning and offered to sheep at the maintenance feeding level. Thirty-seven equations were developed for the prediction of herbage digestible energy (DE) and ME energy values. The mean prediction error for ME was the lowest when using herbage gross energy digestibility as a sole predictor. When using other digestibility variables (e.g., dry matter and organic matter) as primary predictors, addition of herbage nutrient concentration reduced the difference between predicted and actual values. When DE was used as the primary explanatory variable, mean prediction error was reduced with the addition of ash, nitrogen (N), diethyl ether extract (EE), neutral detergent fiber (NDF), and acid detergent fiber (ADF) concentrations. The internal validation of the present equations showed lower prediction errors when compared with those of existing equations for prediction of DE and ME concentrations in the herbage. Equations developed in the current study may thus allow for an improved and accurate prediction of metabolizable energy concentrations of herbage in practice, which is critical for the development of sustainable grazing systems in the QTP.

Rumen degradability characteristics of five starch-based concentrate supplements used on Australian dairy farms

This experiment compared the rumen degradability characteristics of five starch-based concentrate supplements used by Western Australia (WA) dairy producers. Six rumen-fistulated, non-lactating, Holstein-Friesian cows were used to measure the in sacco rumen degradability of maize grain, oats, wheat, sodium hydroxide-treated wheat (NaOH wheat) and Maximize® (a commercial pellet commonly used by WA dairy producers). Cows were offered a basal diet of custom-made cubes (60 : 40 lucerne hay : wheat grain) at maintenance feeding level. Rumen disappearance of dry matter (DM), starch and crude protein was determined for each concentrate at 0, 1, 2, 4, 8, 16, 24, 36, 48 and 72 h, and fitted to an exponential model to estimate degradation kinetics. Effective degradability coefficients were then calculated at three rumen solid-outflow rates (0.02, 0.05 and 0.08/h). Degradability of DM at 0.08/h was lowest (P < 0.001) in maize grain (0.64) and oats (0.68) and greatest in wheat (0.83), with that in NaOH wheat (0.80) and Maximize (0.76) being intermediate. Starch degradability at 0.08/h was also lowest (P < 0.001) in maize grain (0.70), intermediate for NaOH wheat (0.83) and Maximize (0.87), and greatest for wheat (0.96) and oats (0.98). Degradability of crude protein was lowest (P = 0.001) in Maximize (0.66) and NaOH wheat (0.69), greatest in oats (0.85), with that in maize grain (0.72) and wheat (0.79) being intermediate. For producers where availability of maize grain for dairy cow rations is limited, such as in WA, these results indicated that NaOH wheat and Maximize may be considered as alternative starch sources to increase post-ruminal digestion of starch, although the magnitude of this increase will still not be as great as for maize grain.

Equations to predict methane emissions from cows fed at maintenance energy level in pasture-based systems

Ruminant production is a vital part of food industry but it raises environmental concerns, partly due to the associated methane outputs. Efficient methane mitigation and estimation of emissions from ruminants requires accurate prediction tools. Equations recommended by international organizations or scientific studies have been developed with animals fed conserved forages and concentrates and may be used with caution for grazing cattle. The aim of the current study was to develop prediction equations with animals fed fresh grass in order to be more suitable to pasture-based systems and for animals at lower feeding levels. A study with 25 nonpregnant nonlactating cows fed solely fresh-cut grass at maintenance energy level was performed over two consecutive grazing seasons. Grass of broad feeding quality, due to contrasting harvest dates, maturity, fertilisation and grass varieties, from eight swards was offered. Cows were offered the experimental diets for at least 2 weeks before housed in calorimetric chambers over 3 consecutive days with feed intake measurements and total urine and faeces collections performed daily. Methane emissions were measured over the last 2 days. Prediction models were developed from 100 3-day averaged records. Internal validation of these equations, and those recommended in literature, was performed. The existing in greenhouse gas inventories models under-estimated methane emissions from animals fed fresh-cut grass at maintenance while the new models, using the same predictors, improved prediction accuracy. Error in methane outputs prediction was decreased when grass nutrient, metabolisable energy and digestible organic matter concentrations were added as predictors to equations already containing dry matter or energy intakes, possibly because they explain feed digestibility and the type of energy-supplying nutrients more efficiently. Predictions based on readily available farm-level data, such as liveweight and grass nutrient concentrations were also generated and performed satisfactorily. New models may be recommended for predictions of methane emissions from grazing cattle at maintenance or low feeding levels.

The effects of season and moderate nutritional restriction on ovarian function and oocyte nuclear maturation in cycling gilts

The fertility of female pigs is impaired during summer and in response to restriction of feed intake, resulting in reduced productivity of the breeding herd. This study determined the effect of season and moderate nutritional restriction on ovarian function and oocyte developmental competence of cycling gilts. Eighty prepubescent gilts were used across two seasons—summer (S: January to March) and winter (W: June to August)—and received either a high (2.5× maintenance) or a moderately restricted (1.5× maintenance) feeding level for the first 19 days of their second estrous cycle. On Day 19, ovaries were collected post-slaughter. Diameters of all surface follicles over 1 mm were measured. All follicles ≥4 mm were aspirated and cumulus–oocyte complexes underwent in vitro maturation for ∼44 hours to assess oocyte developmental competence on the basis of metaphase II (MII) attainment. Moderate dietary nutrition reduced daily liveweight gain but did not affect the ovarian follicle population or oocyte developmental competence. The number of large follicles (≥6 mm) was lower during summer (S: 10.7 ± 1.74 vs. W: 15.5 ± 1.15, P < 0.05), as was the proportion of oocytes at the germinal vesicle stage of meiosis (S: 0.06 ± 0.02 vs. W: 0.08 ± 0.02, P < 0.05). However, the proportion of oocytes attaining MII was similar in summer and winter (S: 0.72 ± 0.04 and W: 0.69 ± 0.06, P > 0.05). Intrafollicular concentrations of luteinizing hormone were higher in summer (S: 43.05 ± 6.44 vs. W: 12.05 ± 5.12 ng/mL, P < 0.001), whereas estradiol was lower (S: 1.27 ± 0.36 vs. W: 27.52 ± 5.59 ng/mL, P < 0.001). In conclusion, our data demonstrated that in summer, follicle growth beyond 6 mm is impaired during the periovulatory period, without affecting oocyte meiotic competence. Importantly, these data also demonstrated that ovarian follicle growth and the capacity of oocytes to reach MII in vitro appear unaffected by moderate nutritional restriction during the preceding estrous cycle.

배합사료 공급율 및 공급횟수가 겨울철에 사육된 육성기 넙치의 성장 및 체조성에 미치는 영향

Two 15-week feeding trials were conducted to investigate how the rate and frequency of feeding affected the winter growth of olive flounder (<TEX>$13^{\circ}C$</TEX>). In the first experiment, triplicate groups of fish (initial mean weight <TEX>$117{\pm}6.0$</TEX> g) were fed extruded pellets twice a day at feeding rates of 0.1, 0.25, 0.4, 0.55, and 0.57% (satiation) body weight per day (BW/d). The weight gain, specific growth rate, and feed efficiency increased significantly (P<0.05) with the feeding rates from 0.1 to 0.55% BW/d, but no significant differences in these parameters were found for fish fed diets of 0.55% BW/d and satiation. The moisture and ash contents of whole body of fish tended to decrease as the feeding rate increased, but the opposite trend was found for crude lipid content. In the second experiment, triplicate groups of fish (initial mean weight <TEX>$117{\pm}6.3$</TEX> g) were fed extruded pellets to apparent satiation at the three different feeding frequencies: one meal 2 days, one meal a day and two meals a day. The weight gain and specific growth rate of fish fed one meal 2 days were significantly (P<0.05) lower than those of fish fed one or two meals a day, whereas no significant differences in the weight gain and specific growth rate were found between fish fed one and those fed two meals a day. Feed efficiency and condition factor were not significantly affected by feeding frequency. Based on these results, a feeding rate of 0.3% BW/d is recommended as maintenance feeding level, and the optimum feeding frequency is one meal a day with satiation feeding for the growth of olive flounder (117-147 g) during winter (<TEX>$13^{\circ}C$</TEX>).

Effects of feeding levels on growth performance, feed utilization, body composition and apparent digestibility coefficients of nutrients for juvenile Chinese sucker,Myxocyprinus asiaticus

An experiment was conducted to determine effects of feeding levels on growth performance, feed utilization, nutrient deposition, body composition and apparent digestibility coefficients (ADCs) of nutrients for juvenile Chinese sucker (initial weight, 11.77±0.22 g). Chinese sucker were fed a practical diet from 0% (starvation) to 4.0% (at 0.5% increments) body weight (bw) day−1 for 8 weeks. The results showed that growth performance, feed utilization, nutrient deposition, body composition and ADCs of dry matter, protein and energy were significantly (P<0.05) affected by feeding levels. Survival was the lowest for the starvation group. Final mean body weight, growth rate, thermal-unit growth coefficient (TGC) increased with feeding rate from 0% to 3.0% bw day−1 (P<0.05) and showed no significant differences above the level (P>0.05). Feed conversion rate was significantly lower at a feeding level of 2.5% bw day−1 than above and below the level (P<0.05). Protein efficiency ratio was markedly highest at the 2.5% bw day−1 ration level (P<0.05). Fish fed at the feeding level (1.0% bw day−1), which represented a maintenance ration (energy gain was less than 2.27 kJ fish−1 day−1), showed positive protein deposition but negative lipid deposition. This indicates that fish fed a maintenance ration mobilize body lipid reserve to support protein deposition. Lipid contents of whole body, muscle and liver increased with increasing feeding rates from 0.5% to 3.0% bw day−1 and showed no significant differences above the level (P>0.05). Protein contents of whole-body composition increased with feeding rate from 0.5 to 3.0% bw day−1 (P<0.05) and showed no significant differences above the level (P>0.05), whereas muscle and liver remained relatively stable with the different ration amount with the exception of fish fed a ration of 0.5% bw day−1, at which Chinese sucker possessed significantly lower body protein concentration (P<0.05). The ADCs of dry matter, protein and energy decreased with increasing feeding levels from 0.5% to 3.0% bw day−1 and then remained relatively constant over the level. Based on the broken-line regression analysis using WG data, the optimum and maintenance feeding levels for Chinese sucker were 3.10% bw day−1 and 0.45% bw day−1 respectively.

A meta-analysis of feed digestion in dairy cows. 1. The effects of forage and concentrate factors on total diet digestibility

A meta-analysis based on published experiments with lactating dairy cows was conducted to study the effects of dietary forage and concentrate factors on apparent total diet digestibility. A data set was collected that included a total of 497 dietary treatment means from 92 studies. The diets were based on grass silage or on legume or whole-crop cereal silages partly or completely substituted for grass silage. The silages were supplemented with concentrates given at a flat rate within a dietary comparison. For the statistical evaluation, the data were divided into 5 subsets to quantify silage (digestibility, 42 diets in 17 studies; fermentation characteristics, 108 diets in 39 studies) and concentrate (amount of supplementation, 142 diets in 59 studies; concentration of crude protein, 215 diets in 82 studies; carbohydrate composition, 66 diets in 23 studies) factors on total diet digestibility. The diet digestibility of dairy cows was determined by total fecal collection or by using acid-insoluble ash as an internal marker. Diet organic matter digestibility (OMD) at a maintenance level of feeding (OMDm) was estimated using sheep in vivo or corresponding in vitro digestibility values for the forage and reported ingredient and chemical composition values, with tabulated digestibility coefficients for the concentrate components of the diet. A mixed model regression analysis was used to detect the responses of different dietary factors on apparent total diet digestibility. Improved silage OMDm resulting from earlier harvest was translated into improved production-level OMD in cows (OMDp). The effects of silage fermentation characteristics on OMDp were quantitatively small, although sometimes significant. Concentrate supplementation improved total diet OMDm, but this was not realized in lactating dairy cows because of linearly decreased neutral detergent fiber (NDF) digestibility as concentrate intake increased. Increasing the concentrate crude protein amount quadratically improved OMDp in cows, with the response being mostly due to improved NDF digestibility. Replacement of starchy concentrates with fibrous by-products slightly decreased OMDp but tended to improve NDF digestibility. The true digestibility of cell solubles (OM – NDF) estimated by the Lucas test both from all data and from the data subsets was not significantly different from 1.00, suggesting that responses in OMDp of dairy cows are mediated through changes in the concentration and digestibility of NDF.

A meta-analysis of feed digestion in dairy cows. 2. The effects of feeding level and diet composition on digestibility

A meta-analysis based on published experiments with lactating dairy cows fed mainly grass silage-based diets was conducted to study the effects of intake, diet composition, and digestibility at a maintenance level of feeding on the apparent total diet digestibility. A data set that included a total of 497 dietary treatment means from 92 studies was collected and analyzed using mixed model regression analysis with a random study effect. Diet organic matter digestibility (OMD) in dairy cows at a production level (OMDp) was positively associated with OMD at maintenance (OMDm), but the slope was less than 1 (0.69). Diet OMDp decreased as feed intake increased, and diets with high OMDm exhibited greater depressions in digestibility with increased intake than did diets with low OMDm. Digestibility of organic matter and neutral detergent fiber (NDF) increased as dietary crude protein concentration increased, whereas increased concentrate fat decreased digestibility. Replacement of grass silage with whole-crop cereal silage was associated with a quadratic decrease in diet digestibility. Metabolic fecal output, defined as fecal organic matter minus NDF, averaged 95.8 (SE=0.65) g/kg of dry matter intake, and it was not influenced by intake or diet composition. Variation in OMDp in cows fed grass silage-based diets was therefore attributable to variation in dietary NDF concentration and NDF digestibility. Depression in digestibility of organic matter with increased intake was less than predicted by the National Research Council and Cornell Net Carbohydrate and Protein systems. The following 2-parameter model indicates that the difference between OMD estimated in sheep fed at maintenance compared with dairy cows at production level is related both to dry matter intake and digestibility at maintenance level: OMDp=257 (±43) + 0.685 (±0.054) × OMDm (g/kg of dry matter) – 2.6 (±0.44) × dry matter intake (kg/d); adjusted residual mean square error=8.4g/kg. It was concluded that diet digestibility in dairy cows can be predicted accurately and precisely from digestibility estimated at maintenance intake in sheep by using regression models including animal and dietary factors.

Effect of feeding allowance level on embryonic survival, IGF‐1, insulin, GH, leptin and progesterone secretion in early pregnancy gilts

The present experiment was conducted to evaluate the effects of feeding allowance level on embryonic survival, uterine development and reproductive hormone secretion in early gestation gilts. A total of 54 F1 crosses of Landrace x Large white gilts were randomly allocated to three treatment groups of high (H, 2 x maintenance), medium (M, 1.2 x maintenance) and low (L, 0.6 x maintenance) feeding level after mating. Blood samples and uterine flushings were collected on day 12, 25 and 35 of pregnancy, and embryonic survival rate was estimated. Concentrations of insulin-like growth factor I (IGF)-1, insulin, growth harmone (GH), leptin and progesterone in serum and uterine flushings were determined by enzyme-linked immunosorbent assay. Embryonic survival was affected by dietary treatment; total number of viable embryos and embryo survival of group M were higher than other groups in the early pregnancy (p < 0.05). Greater foetal weight in M gilts was achieved when gestation advanced to day 35 (p < 0.05), though there was no difference on day 25 of pregnancy among treatments. No appreciable differences were observed in the crown-rump length on day 25 and 35 of pregnancy among groups. Greater weight of uterus and products of conception were identified in M gilts compared with group H and L (p = 0.024 and p = 0.005, respectively) on day 25 of pregnancy. The hormone level was greatly affected by feeding allowance level. In serum, concentrations of IGF-1, leptin and insulin tended to be greater in H than in M and L during the early gestation, while concentrations of GH were greater in M and progesterone were the lowest in H. At the same time, feed allowance level affected the concentration of IGF-1, insulin, GH, leptin and progesterone in uterine flushings. These data demonstrated that feed allowance level after mating has important consequence on embryo survival, embryo development and uterine development, possibly mediated by nutrition level inducing changes in concentrations of reproductive hormones and/or intermediary metabolites in early pregnancy.

Prediction of in vivo neutral detergent fiber digestibility and digestion rate of potentially digestible neutral detergent fiber: Comparison of models

Eleven 1-pool, seven 2-pool, and three 3-pool models were compared in fitting gas production data and predicting in vivo NDF digestibility and effective first-order digestion rate of potentially digestible NDF (pdNDF). Isolated NDF from 15 grass silages harvested at different stages of maturity was incubated in triplicate in rumen fluid-buffer solution for 72 h to estimate the digestion kinetics from cumulative gas production profiles. In vivo digestibility was estimated by the total fecal collection method in sheep fed at a maintenance level of feeding. The concentration of pdNDF was estimated by a 12-d in situ incubation. The parameter values from gas production profiles and pdNDF were used in a 2-compartment rumen model to predict pdNDF digestibility using 50 h of rumen residence time distributed in a ratio of 0.4:0.6 between the non-escapable and escapable pools. The effective first-order digestion rate was computed both from observed in vivo and model-predicted pdNDF digestibility assuming the passage kinetic model described above. There were marked differences between the models in fitting the gas production data. The fit improved with increasing number of pools, suggesting that silage pdNDF is not a homogenous substrate. Generally, the models predicted in vivo NDF digestibility and digestion rate accurately. However, a good fit of gas production data was not necessarily translated into improved predictions of the in vivo data. The models overestimating the asymptotic gas volumes tended to underestimate the in vivo digestibility. Investigating the time-related residuals during the later phases of fermentation is important when the data are used to estimate the first-order digestion rate of pdNDF. Relatively simple models such as the France model or even a single exponential model with discrete lag period satisfied the minimum criteria for a good model. Further, the comparison of feedstuffs on the basis of parameter values is more unequivocal than in the case of multiple-pool models.

Prediction of the energy content of tallgrass prairie hay1

Two experiments were conducted to describe the DE content of tallgrass prairie hay (TPH). In trial 1, steers (n = 13; 277 +/- 15 kg of BW) were used in a 13 x 4 Latin square experiment to measure the DE of 13 samples of TPH fed at 1.5% of BW daily (average feeding level = 0.7 x the maintenance energy requirement). Hays were harvested from a variety of locations in east-central Kansas and represented an array of harvest dates and storage methods. In trial 2, steers (n = 16; 261 + 17 kg of BW) were used in a randomized complete block experiment to assess the effects of TPH intake level on DE. Hay was fed at 1.3, 1.7, 2.1, or 2.5% of BW daily, which corresponded to 0.9, 1.4, 1.6, and 1.9 x the maintenance energy requirement. Steers in both trials were fed soybean meal in amounts calculated to provide ruminally degradable protein (RDP) equal to 11% of digestible OM intake. Hay samples were analyzed for ash, N, NDF, ADF, ADIN, NDIN, acid detergent-insoluble ash, lignin, monosaccharides, and alkali-labile phenolic acids. Chemical components related to DE (P < 0.2) were subjected to iterative regression analysis to predict the DE concentration of the diet. Iterations were ceased when the error mean square of the regression was optimized. At 0.7 x maintenance, the dietary DE concentration (Mcal/kg) was described by: DE = 0.13(CP) - 0.16(ADL) + 2.11 (R(2) = 0.73; S(y*x) = 0.13). Forage OM digestion decreased linearly (P < 0.01) as forage intake increased. Apparent dietary DE concentration decreased by 7.4% when intake was increased from 1 to 2 x maintenance. When RDP was adequate, chemical composition values were useful indicators of forage DE content in our study. Moreover, increased forage intake depressed GE digestion by steers, but ultimately increased total DE intake. Energy digestion varied with forage intake in a predictable manner between 1 and 2 x the maintenance feeding level.

Comparison of metabolic rates and feed nutrient digestibility in conventional, genetically improved (GIFT) and genetically male (GMNT) Nile tilapia, Oreochromis niloticus (L.)

Various aspects of energy metabolism and feed digestibility were evaluated in two reportedly improved strains of Nile tilapia (Oreochromis niloticus) namely GIFT (genetically improved farmed tilapia) and GMNT (genetically male Nile tilapia) and compared with those of CNT (conventional Nile tilapia). Fish were stocked individually in a computer-controlled respirometer system at 27+/-0.1 degrees C for 10 weeks. Metabolic rates were measured at three different feeding levels: starved, maintenance (3.0 g kg(-0.8) day(-1)) and growth (7.5 g kg(-0.8) day(-1)) using a fishmeal based feed containing TiO2 marker (41% crude protein, 9% crude lipid and 19 kJ (g DM)(-1) gross energy). The standard metabolic rate (SMR), measured at the beginning of the experiment (45.4+/-4.6, 52.4+/-7.7 and 46.8+/-4.6 mg O2 kg(-0.8) h(-1) respectively for GIFT, GMNT and CNT), did not differ significantly between the groups (p<0.05). Similarly, non-significant differences were also observed in the routine metabolic rates under starved, maintenance and growth conditions but the variability was higher in the case of GMNT and CNT than in GIFT. The latter group showed a significantly lower active metabolic rate (145 mg O2 kg(-0.8) h(-1)) compared to GMNT and CNT (232 and 253 mg O2 kg(-0.8) h(-1), respectively) at maintenance feeding level. The specific dynamic action (% offered feed energy) showed no significant differences among the groups. Digestibility coefficients of feed dry matter, protein, lipid and energy for the three tilapia groups also did not differ significantly. Therefore, we concluded that the genetic improvement or modification in the GIFT or GMNT might not upgrade the inherent physiological potential compared to CNT as far as energy metabolism and digestion efficiencies are concerned.

Effects of Feeding Levels on Growth Performance, Feed Utilization, Body Composition, and Apparent Digestibility Coefficients of Nutrients for Grouper Epinephelus coioides Juveniles

Abstract An experiment was conducted to determine effects of feeding levels on growth performance, feed utilization, body composition, and apparent digestibility coefficients (ADCs) of nutrients for juvenile grouper Epinephelus coioides (initial weight, 10.31 ± 0.36 g). Grouper were fed a practical diet from 0 (starvation) to 3.5% (at 0.5% increments) body weight per day (bw/d) for 8 wk. ANOVA indicated that growth performance, feed utilization, body composition, and ADCs of dry matter, protein, and energy were significantly (P &lt; 0.05) affected by feeding levels. Survival was the lowest for the starvation group and for fish fed a ration of 0.5% bw/d. Final mean body weight, weight gain (WG), specific growth rate, and metabolic growth rate increased with feeding rate from 0 to 2.5% bw/d (P &lt; 0.05) and showed no significant differences above the level (P &gt; 0.05). Feed conversion rate was significantly lower at a feeding level of 2.0% bw/d than above and below the level (P &lt; 0.05). Protein efficiency ratio was markedly highest at the 2.0% bw/d ration level (P &lt; 0.05). Lipid contents of whole body, muscle, and liver increased with increasing feeding rates from 0 to 3% bw/d and showed a slight decline at the feeding level of 3.5% bw/d. Protein contents of whole‐body composition, muscle, and liver remained relatively stable with the different ration amount with the exception of fish fed a ration of 0.5% bw/d, at which grouper possessed significantly lower body protein concentration (P &lt; 0.05). Condition factor, viscerosomatic index, and hepatosomatic index were the lowest for fish fed 0.5% bw/d and tended to increase with the increasing feeding levels. ADCs of dry matter, protein, and energy decreased with increasing feeding levels from 0 to 2.5% bw/d and then remained relatively constant over the level. Based on the broken‐line regression analysis using WG data, the optimum and maintenance feeding levels for grouper were 2.5% bw/d and 0.25% bw/d, respectively.

Measurements of heat production for estimation of maintenance energy requirements of Hereford steers1,2

This study aimed to test the hypothesis that maintenance energy requirement (MEm) can be estimated from continuous heat production measurements during a change from a near maintenance feeding level to far below maintenance for two consecutive days. The MEm of eight Hereford steers weighing 286 +/- 5 kg (mean +/- SE) was determined in a balance trial. In addition, during the 10-d collection period, the animals were kept in open-circuit respiration chambers to measure 24-h gas exchange continuously at 10-min intervals. During the balance trial, the animals were fed dried chopped grass twice daily at an estimated level of 1.2 x MEm. After termination of the collection period on the 11th d of the balance trial, the steers were offered 2 kg/d of wheat straw while only gas exchange was measured. Estimates of MEm were derived from heat production (HP) data. The analyses included values of 24-h HP, HP of the nocturnal period (0000 to 0630), HP of the nocturnal period (excluding HP caused by standing) during the grass-feeding period and 24-h HP, nocturnal HP, and nocturnal HP (excluding HP caused by standing) during the straw feeding period. The MEm predicted from estimates of HP measurements were 536 +/- 9, 470 +/- 8, 441 +/- 8, 435 +/- 8, 393 +/- 9, and 373 +/- 9 kJ.kg of BW(-0.75).d(-1), respectively, whereas MEm calculated from data of the balance trial were 416 +/- 9 kJ.kg of BW(-0.75).d(-1). Values predicted for nocturnal HP (excluding HP caused by standing) of grass fed animals, 24-h HP, and nocturnal HP during straw feeding did not differ significantly from MEm. The differences in MEm among animals were reflected by all estimates of HP, whereas the correlation with the 24-h HP during straw feeding reached 0.9 (P = 0.002). We conclude that the method described is adequate to determine MEm with a sufficient degree of accuracy.

Effect of Protein Sources with Different Rumen Degradability in a Diet on the Efficiency of Utilization of Metabolizable Energy by Calves

Abstract. To evaluate the effect of dietary protein of diverse rumen degradability on the efficiency of metabolizable energy (ME) utilization by calves at the growth and maintenance levels of feeding. A total of 54 energy balance trials were conducted using 18 Holstein castrated male calves given four diets containing soybean meal (SBM), cottonseed meal (CSM), heated soybean meal (HSBM) and corn gluten meal (CGM) as a main source of protein. The trials were carried out at the ages of 13 weeks for the growth (G) level of feeding and 15 weeks for maintenance (M) followed by the 24-h measurement of fasting (F) heat production after 3-day fasting. The dg values were 0.657, 0.543, 0.463 and 0.413 for SBM, CSM, HSBM and CGM, respectively. The regression analyses of energy retention (ER, kJ/W0.75) on the intake of ME (IME, kJ/W0.75) above the maintenance level revealed no significant differences among diets and gave a following pooled equation: ER = 0.56(±0.04)IME – 311, r = 0.897 (P&lt;0.01). The below M level resulted in the following two distinct equations for the diet with a higher dg of protein source and that of a lower dg: ER = 0.77(±0.02)IME – 403, r = 0.994 (P&lt;0.01) for SBM + CSM. ER = 0.60(±0.03)IME – 350, r = 0.982 (P&lt;0.01) for HSBM + CGM. We concluded that ME utilization for maintenance may be influenced by the protein sources of different dg, but not for growth.

Prediction of nutritive values in grass silages: I. Nutrient digestibility and energy concentrations using nutrient compositions and fermentation characteristics.

Grass silages (n = 136) were selected from commercial farms across Northern Ireland according to their pH, ammonia nitrogen, DM, and predicted ME concentration. Each silage was offered to four sheep as a sole feed at maintenance feeding level to determine nutrient digestibility and urinary energy output. Dry matter concentration was determined as alcohol-corrected toluene DM and was subsequently used as the basis for all nutrient concentrations. The objectives were to use these data to examine relationships between nutritive value and nutrient concentration or fermentation characteristics in silages and then develop prediction equations for silage nutritive values using stepwise multiple regression techniques. The silages had a large range in quality (DM = 15.5 to 41.3%, ME = 7.7 to 12.9 MJ/kg of DM, pH = 3.5 to 5.5) and a relatively even distribution over the range. There was a positive relationship (P < 0.001) between silage GE and DE or ME concentration. Digestible OM in total DM (DOMD); ME/GE; and digestibility of DM, OM, and GE were positively related (P < 0.05) to CP, soluble CP, ether extract, lactic acid concentration, and lactic acid/ total VFA, whereas they were negatively related (P < 0.05) to ADF, NDF, lignin, individual VFA concentration, pH, and ammonia N/total N. Concentrations of DE and ME and digestibility of CP and NDF had similar relationships with those variables, although some relationships were not significant. Three sets of multiple prediction equations for DE and ME concentration; ME/ GE; DOMD; and digestibility of DM, OM, GE, CP, and NDF were therefore developed using three sets of predictors. The first set included GE, CP, soluble N/total N, DM, ash, NDF, lignin, lactic acid/total VFA, and ammonia N/total N; the second set excluded soluble N/ total N and lignin because they are not typically measured; the third set further excluded the fermentation data. The R2 values generally decreased with exclusion of predictors. The second and third sets of equations, except for NDF digestibility, were validated using the mean-square-prediction-error model and an independent grass silage data set published since 1977 (n = 17 [DM digestibility] to 28 [DOMD and OM digestibility]). The validation indicated that the equations developed in the present experiment could accurately predict DE and ME concentrations and DE/GE and ME/GE in grass silages.

Optimum feeding rates for European sea bass Dicentrarchus labrax L. reared in seawater and freshwater

Growth, feed conversion efficiency, fillet composition and morphological indices of European sea bass (initial weight of 2.6±0.3 g) were investigated in a 6×2 factorial designed experiment employing two salinities [seawater (SW, 40 ppt) and freshwater (FW, 0.4 ppt)] and six different feeding rates (2.0%, 2.5%, 3.0%, 3.5%, 4.0% of their body weight (bw) day −1 and to satiation) for 60 days. Twenty fish were stocked into 155-l round tanks and each treatment had three replicate tanks. Throughout the experiment, weight gain and specific growth rate (SGR) were highest at ration 4.0 bw day −1 and to satiation in SW group. Regardless of feeding rate, sea bass fingerlings grew about 20–30% more in SW than those reared in FW. There was a significant ( P<0.05) interactive effect of feeding rates and culture media (SW and FW) on weight gain and feed conversion efficiency (FCE). FCE was found to be lower in fish fed to satiation (65–66%) compared to the feeding rate of 3.5% bw day −1, which was best in both SW (89.1%) and FW (86.5%). There were no significant differences in either protein or ash contents of the fish cultured in SW or FW although lipid and moisture contents changed with increasing feeding rate. Condition factor, fillet yield and carcass/body weight were significantly increased, whereas hepatosomatic index, viscera somatic index decreased when the feeding rate was increased above 2.0% bw day −1. Feeding rate proved to be the main differentiating factor in all growth, FCE and fillet composition parameters. Values of SGR plotted against feeding rates allowed the maintenance, optimum and maximum feeding levels to be determined. Based on the calculations, the optimum feeding rate for sea bass fingerlings (3 g) reared in SW and FW is 3.0% and 3.5% bw day −1, respectively. In addition, the optimum feeding rate for FCE was calculated as 2.7% bw day −1 in SW and 3.8% bw day −1 in FW. It is concluded that growth and FCE of European sea bass can be improved by feeding them at about 3.0–3.5% bw day −1 in SW or FW.

Effect of specific weight on the metabolizable energy content of four cultivars of wheat grain in ewes

To determine the effect of specific weight on the metabolizable energy value of wheat grain for ruminants, 16 samples of winter wheat grain, comprising four cultivars (Riband, Buster, Consort and Haven) each at four specific weights ranging from 60 to 78 kg/hl were fed in a pelleted concentrate (wheat=0.7 of total fresh weight) to housed mature sheep at the maintenance level of feeding. The concentrate comprised 0.6 of total daily dry matter (DM) intake, and chopped winter wheat straw comprised 0.4 of total daily DM intake. There was no effect of specific weight on apparent digestibility of whole-diet DM or on whole-diet estimated metabolizable energy (ME) concentration. There were no interactions between specific weight and cultivar in terms of apparent digestibility of whole-diet DM. Apparent digestibility of DM was lower ( P<0.05) for Buster and Consort than for Riband and Haven. Estimated concentration of ME was lower ( P<0.05) for Buster than for Riband and Haven. There is energetic flexibility in the use of winter wheat of different specific weights in diets for ruminants, since there is no relationship between specific weight and metabolizable energy content.

Optimum daily ration for Eurasian perch Perca fluviatilis L. reared at its optimum growing temperature

Four feeding experiments were conducted to estimate the optimal daily food ration of Eurasian perch at different stages of its development under optimum rearing temperature (23 °C). Mean initial weights of 0.22-, 0.73-, 1.56- and 18.9-g fish, previously habituated to a dry diet, were used in experiments lasting between 14 and 30 days, depending on initial body weight. Daily feeding levels ranged from 2% to 20% of biomass in 0.22-g fish, from 1% to 8% in 0.73-g fish, from 1% to 10% of biomass in 1.56-g fish and from 0.3% to 3% of biomass for 18.9-g fish. Feeding levels significantly affected survival of perch, except in experiment 4 with large juveniles (18.9). In experiments 2 and 3 (with 0.73- and 1.56-g fish, respectively), cannibalism was significantly higher at the lowest feeding level (1% biomass day −1), while starvation seemed to be the major cause of death in experiment 1 with 0.22-g fish. Values of specific growth rate (SGR) plotted against daily food ration allowed the maintenance, optimum and maximum feeding levels to be determined, according to the Brett and Grove's model. Optimum feeding level for Eurasian perch decreased from 7.4% to 5.1%, 4.5% and 2.2% biomass day −1 for fish of 0.22, 0.73, 1.56 and 18.9 g initial body weight, respectively.