Weight Gain Response Research Articles

Dietary phosphorus requirement of juvenile milkfish,Chanos chanos(Forsskal)

Seven isocaloric and isonitrogenous diets with graded levels of monopotassium phosphate to yield total phosphorus levels of 0.28 (no P supplementation), 0.43, 0.58, 0.73, 0.88, 1.03 and 1.18% were prepared and fed to five replicate groups of 10 juvenile milkfish (initial weight = 2.5 g). After 16 weeks of feeding, significant differences in growth (300–570%), survival rates (70–100%), and bone and scale mineralization were found among treatment groups. Weight gains of milkfish increased linearly up to the 0.88% dietary phosphorus concentration and levelled off beyond this dietary level. Bone and scale ash, calcium and phosphorus concentrations showed similar patterns as weight gain in response to dietary phosphorus concentration. Broken-line regression analyses of these data indicated that the dietary phosphorus level required for optimal growth and mineralization of juvenile milkfish is ≈ 0.85% of dry diet.

Microbial Phytase Improves Performance, Apparent Metabolizable Energy, and Ileal Amino Acid Digestibility of Broilers Fed a Lysine-Deficient Diet

An experiment was conducted to examine the effects of adding microbial phytase (Natuphos®) on the performance in broilers fed a phosphorus-adequate, lysine-deficient diet. A wheat-soybean meal-sorghum-based diet, containing 1.00% lysine and 0.45% nonphytate phosphorus, was supplemented with L-lysine monochloride to provide 1.06, 1.12, or 1.18% lysine or with 125, 250, 375, 500, 750, or 1,000 phytase units (FTU)/kg diet. Each diet was fed to six pens of 10 chicks each from Day 7 to 28 posthatching. Addition of lysine to the lysine-deficient diet linearly increased (P < 0.001) weight gain and gain per feed of broilers. The response in weight gain to added phytase reached a plateau at 500 FTU/kg diet (quadratic effect, P < 0.001). Phytase had no effect on gain per feed to 250 FTU/kg diet and then increased (quadratic effect, P < 0.05) with further additions. Assuming that the observed responses in weight gain and gain per feed to added phytase were due to the release of lysine alone and by solving linear or nonlinear response equations of lysine and phytase levels, the lysine equivalency value was calculated to be 500 FTU phytase/kg diet = 0.074% lysine. Addition of increasing levels of supplemental phytase to the lysine-deficient diet improved (P < 0.001) the digestibilities of nitrogen and all amino acids. Phytase also increased the AME, and the response reached a plateau at 750 FTU/kg diet (quadratic effect, P < 0.001). These results showed that amino acid and energy responses are responsible for the performance improvements observed when phytase was added to a wheat-soybean meal-sorghum-based diet.

Effect of ruminal protein degradability on growth and N metabolism in growing beef steers.

The objective of two experiments was to correlate plasma levels of urea N (PUN) and the percentage of urine N in the form of urea (UUN) to weight gain in response to different dietary protein regimens for growing Angus steers. In Exp. 1, 60 steers (302 kg BW) were assigned to various levels of dietary N (control plus supplemental N to provide from 100 to 400 g more crude protein daily) within two sources of supplemental N (soybean meal [SBM] or a mixture of two parts corn gluten meal:one part blood meal [CGM:BM]). In Exp. 2, 27 steers (229 kg BW) were fed two levels of SBM, and half of the steers received growth-promoting implants. Steers were housed in groups of 12 and fed individually for 84 d in both experiments. Corn silage was fed at a restricted rate to minimize orts. Jugular blood and urine samples were collected during the experiments. In Exp. 1, maximal ADG of steers fed SBM (1.0 kg) was reached with 671 g/d total crude protein, or 531 g/d metabolizable protein. Maximal ADG of steers fed CGM:BM (0.91 kg) was reached with 589 g/d total crude protein, or 539 g/d metabolizable protein. The DMI was higher (P < 0.07) for steers fed SBM (6.37 kg/d) than for steers fed CGM:BM (6.14 kg/d). Increasing ruminal escape protein from 36% (SBM) to 65% (CGM:BM) of CP decreased (P < 0.05) endogenous production of urea, as evidenced by lower concentrations of urea in blood and lower UUN. In Exp. 2, increasing supplemental protein from 100 to 200 g/d increased (P < 0.05) ADG and PUN. Implants lowered (P < 0.05) UUN, particularly at the higher level of supplemental protein. Protein supplementation of growing steers can be managed to maintain acceptable ADG yet decrease excretion of urea in the urine.

Effects of a Sensory Stimulation on Weight Gain, Behavioral State, and Physiological Responses in Premature Infants

【Purpose: The purpose of this study was to examine the effects of sensory stimulation on premature infants. Method: Thirty three premature infants admitted to NICU of D University Hospital in C city were randomly assigned in two groups (Experimental group: 16, Control group:17). For the experimental group, tactile and kinesthetic stimulation developed by Dr. Field was applied 2 times a day for 10 days. Behavioral state was measured using the Anderson Behavioral State Scale (ABSS). Heart rate, respiration, and oxygen saturation were obtained for each infant before and after sensory stimulation. Hypothesis testing was done using the $\chi$ $^2$ - test, student t-test, and repeated measures of ANOVA. Result: Hypothesis 1: There was a significant difference in the daily body weight gain between experimental and control group (F= 40.77, p= .0001). Hypothesis 2: There was a significant difference in the frequency of 'inactive awake state' between two groups ( $\chi$ $^2$ = 39 39.778, p= .001). Hypothesis 3: There were significant differences in the mean of heart rate and $O_2$ saturation between two groups (t= -2.174, p= .037; t= 3.080, p= .005). However, there was no significant difference in the mean of respiration rate between two groups (t= -1.966, p= .581). Conclusion: The effectiveness of a sensory stimulation on weight gain and behavioral state in premature infants was supported. Further study is recommended to develop a sensory stimulation method as an independent nursing intervention for premature infant.】

Aging and the neuroendocrine regulation of reproduction and body weight.

Aging in men is associated with a decline in trophic factors such as testosterone (T), alterations in body composition and impaired energy and body weight regulation. We performed studies to investigate the mechanisms underlying age-related changes in the neuroendocrine control of testis function, body composition, food intake and body weight in the Brown Norway (BN) rat. We found that similar to aging men, male BN rats demonstrate both primary and secondary testicular failure with aging without confounding age-related tumors, hormonal changes and systemic illnesses. With aging, these animals have blunted circadian variations in luteinizing hormone (LH) and T, and decreased hypothalamic gonadotropin-releasing hormone (GnRH) synthetic capacity with preserved pituitary gonadotropin responses to GnRH. We found that aging male BN rats have increased peripheral and visceral adiposity associated with increased insulin and leptin levels, and decreased relative lean body mass and muscle mass. We found that these rats exhibit reduced food intake and body weight gain associated with decreased hypothalamic neuropeptide Y (NPY) gene expression in the arcuate nucleus (ARC), both during ad-libitum feeding and after a 72-h fast. Recently, we found that old male BN rats treated chronically with troglitazone, an insulin sensitizer, lowered high insulin and leptin levels, decreased body fat, and corrected the blunted food intake and body weight gain response to fasting without affecting basal ARC NPY gene expression. These findings suggested that hyperinsulinemia and/or hyperleptinemia associated with aging may contribute to the age-related impairment in energy and weight regulation. Our studies suggest that the aging male BN rat is an excellent model to investigate the mechanisms underlying the age-associated changes in the neuroendocrine control of body composition, energy intake and body weight.

Effects of neonatal handling on sympathoadrenal activity and body composition in adult male rats.

Neonatal handling permanently alters the hypothalamic-pituitary-adrenal (HPA) response to stress. Because the sympathetic nervous system (SNS) and adrenal medulla also participate in stress responses, the impact of daily handling between birth and weaning on SNS and adrenal medullary function was examined in adult rats using techniques of [(3)H]norepinephrine ([(3)H]NE) turnover and urinary catecholamine excretion. Handled animals exhibited a 23% reduction in [(3)H]NE turnover in heart and a 53% decrease in spleen. [(3)H]NE turnover in brown adipose tissue, stomach, and kidney did not differ between handled and nonhandled animals. In contrast, urinary epinephrine (Epi) excretion was significantly greater in handled rats in response to a 3-day fast than in nonhandled animals. Although body weight, weight gain in response to dietary enrichment with sucrose or lard, or body fat content did not differ in handled and nonhandled animals, handled rats displayed heavier abdominal fat depots than nonhandled animals, implying a difference in body fat distribution. Neonatal handling thus leads to decreased sympathetic activity within specific subdivisions of the SNS and, by contrast, to increased adrenal medullary responsiveness.

Absence of a weight gain response to Vitamin B12 supplementation in weaned dairy heifers grazing pastures of marginal cobalt content

extract Unfortunately there is an error in the paper by Clark et al. in the August 1999 issue of the Journal (Vol 47, 125-127, 1999) entitled: “Absence of a weight-gain response to Vitamin B12 supplementation in weaned dairy heifers grazing pasture of marginal cobalt content”. In the Materials and Methods section, the dose of hydroxycobalamin administered to the treated group reads “2000 mg”; the correct dose is “2000 𝛍g”.

Effect of complex catalytic supplementation with non-protein nitrogen on the ruminal ecosystem of growing goats pasturing on shrub land in Mexico

Thirty-eight young Alpine goats, 16.1 (±0.370) kg body weight (BW), were reared at Querétaro, Mexico, grazing on a semi-arid woody brush ( Caducifolio espinoso) range land. The experimental goats ( n = 20) were pastured daily and supplemented with 200 g/day of a complex catalytic feed (CCF). It consisted of molasses (14–18%), urea (8–10%), salt (3–4%), limestone (3–4%), cottonseed meal (13–18%), rice polishing (10–13%), corn (11–12%), poultry litter (9–10%), commercial mineral salt (1.3%), ammonium sulfate (0.3–0.5%), cement kiln dust (1.5%), and animal lard (10–15%). The control goats ( n = 18) were supplemented daily with 300 g of a balanced concentrate (BC), containing 1.5% commercial mineral salt, 60% corn, 32.5% wheat bran, and 4% soybean oil meal. Stocking rates varied from 1.45 to 1.85 AU/ha and daily stocking rate from 36.4 to 58.6 AU/ha. At all times, fibrous forages were available exceeding the voluntary dry matter intake. One fistulated goat was kept in each group. Growth of the experimental goats averaged 95 g/day (±3) compared to 76 g/day (±5) of the controls ( P < 0.005) in 150 days from June to November. Supplementation per kg BW was from 17.5 to 10.4 g BC/day for the control goats; the experimental goats received 12.2–6.5 g CCF/day. Weight gain in response to fermentable carbohydrates (FC) averaged 8.95 g BW gain/g FC/day for the control BC goats, compared to 28.2 g BW gain/g FC/day for the experimental CCF goats. Daily supplies of FC to goats on CCF supplementation were always below the limits for celullolysis at 6 g/day, while FC supplies of BC rations to the control goats always exceeded them. After 2 h of shrub land pasture, the ruminal pH rose when CCF was offered and stayed above 6.6 during 12 h, while the ruminal acidity in BC goats went down to pH 5.57 at 6 h and rose to 6.5 by 12 h. Ammonia (NH 3 mg/l) in ruminal liquid of CCF goats was higher ( P < 0.01) in average and all but one sample. Total cost per animal per day including shrub land pasture, management, medicine and salaries was US $0.06 for experimental goats and US $0.09 for controls (market price for goat meat was US $1.15/kg; US $1.00 = 10 Mexican Pesos, November 1998). Daily gain varied during the study period from 77 to 85 g/day in BC control goats compared to 92–97 g/day in experimental CCF goats. CCF supplementation to shrub land pasturing resulted in significantly greater weight gains apparently due to elevated ruminal pH, higher availability of fermentable carbohydrates and ruminal ammonia, augmenting ruminal ecosystem, digestibility and voluntary feed intake. The use of local shrub land resources and complex catalytic supplementation with non-protein nitrogen provided greater profitability from this feeding system for growing goats than the traditional balanced concentrate feed supplementation.

A COMPARATIVE RESPIRATORY SENSITIZATION STUDY OF 2,4- AND 2,6-TOLUENE DIISOCYANATE USING GUINEA PIGS

The potential exposure of workers to both 2,4-toluene diisocyanate (2,4-TDI) and 2,6-TDI led to an investigation of the comparative respiratory sensitization potential of these two isomers. Separate groups of guinea pigs were either sham exposed or exposed to one of the isomers 3 h/day for 5 consecutive days (sensitization phase). The mean concentration during the sensitization phase ranged from 1.29 to 1.40 ppm. The animals were then conventionally housed for 2 wk and challenged for 1 h on 3 subsequent weeks with either the same isomer or the alternate isomer. The first 2 wk of the challenge phase involved exposure to TDI vapor (18 to 46 ppb), whereas the third challenge was to an aerosol of TDI? guinea pig serum albumin (GPSA) conjugate (18 to 32 mg/ m3). The endpoint used to detect both immediate-onset and delayedonset hypersensitivity responses was respiratory rate. Body weights and clinical signs were also recorded. There were clear decrements in weight gain in response to the wk 1 exposure to either isomer of TDI, but no isomer-specific differences were observed. Clinical signs revealed irritation to the respiratory tract only during the sensitization phase. A single animal challenged with TDI? GPSA may have experienced a severe anaphylactic response during the challenge phase. The incidence of immediate-onset hypersensitivity responses resulting from challenge with TDI vapor was less robust and less consistent than that resulting from challenge with the TDI-GPSA conjugate. All groups sensitized with either isomer showed an increased incidence of responders. There was no apparent difference between the two isomers. The delayed-onset phase produced more spontaneous variability in spontaneous respiratory rates and was not amenable to analysis for response to TDI challenge. Thus, no isomer-dependent differences were observed.

Body weight and tail length divergence in mice selected for rate of development.

A series of mouse lines has been produced by 19 generations of restricted index selection for rate of development during early and late ontogeny. The selection program was based on an index with the following four replicated selection treatments: E(+) and E(-) were selected to alter birth to 10-day body weight gain while holding late gain for both selection lines constant; correspondingly, L(+) and L(-) were selected to alter 28- to 56-day body weight gain holding early gain for both lines constant. Herein, we characterize response to selection for growth rate by analyzing age-specific mouse body weight and tail lengths and for growth curves using a logistics model. Selection on developmental rate has resulted in divergence in both age-specific and growth curve traits. E(+) and L(+) lines reached identical weights during the late selection interval, then diverged to unique mature weights. E(-) and L(-) lines similarly achieved identical weights during late selection and diverged to unique mature weights. However, the shapes of early and late growth curves were significantly divergent, and at least two distinct growth patterns are shown to result from selection. Response in body weight gain was accompanied by similar, though less pronounced, change in tail length traits. Significant response during intervals of restricted growth was also found, especially in lines selected for late gain. The evolution of the growth trajectory under restricted index selection is discussed in terms of drift and available additive genetic variation and covariation.

The effects of citric acid on phytate-phosphorus utilization in young chicks and pigs.

Several bioassays were conducted with young chicks and pigs fed phosphorus (P)-deficient corn-soybean meal diets. With diets for chicks containing .62% Ca and .42% P (.10% available P), graded doses of a citric acid + sodium citrate (1:1, wt:wt) mixture (0, 1, 2, 4, or 6% of diet) resulted in linear (P < .01) increases in both weight gain and tibia ash. Relative to chicks fed no citric acid, tibia ash (%) and weight gain (g/d) were increased by 43 and 22%, respectively, in chicks fed 6% citric acid. Additional chick trials showed that 6% citric acid alone or sodium citrate alone was as efficacious as the citric acid + sodium citrate mixture and that 1,450 U/kg of phytase produced a positive response in bone ash and weight gain in chicks fed a diet containing 6% citrate. Varying the Ca:available P ratio with and without citrate supplementation indicated that citric acid primarily affected phytate-P utilization, not Ca, in chicks. Moreover, chicks did not respond to citrate supplementation when fed a P-deficient (.13% available P), phytate-free casein-dextrose diet. Young pigs averaging 10 to 11 kg also were used to evaluate citric acid efficacy in two experiments. A P-deficient corn-soybean meal basal diet was used to construct five treatment diets that contained 1) no additive, 2) 3% citric acid, 3) 6% citric acid, 4) 1,450 U/kg phytase, and 5) 6% citric acid + 1,450 U/kg phytase. Phytase supplementation increased (P < .01) weight gain, gain:feed, and metatarsal ash, whereas citric acid addition increased only gain:feed (P < .05) and metatarsal ash (P < .08). A subsequent 22-d pig experiment was conducted to evaluate the effect of lower levels of citric acid (0, 1, 2, or 3%) or 1,450 U/kg phytase addition to a P-deficient corn-soybean meal diet. Phytase supplementation improved (P < .01) all criteria measured. Weight gain and gain:feed data suggested a response to citric acid addition, but this was not supported by fibula ash results (P > .10). The positive responses to phytase were much greater than those to citric acid in both pig experiments. Thus, dietary citric acid effectively improved phytate P utilization in chicks but had a much smaller effect in pigs.

Sporidesmin-induced mortality and histological lesions in mouse lines divergently selected for response to toxins in endophyte-infected fescue.

For eight generations, mouse lines were selected for smaller or larger reduction in postweaning gain from endophyte-infected fescue seed in the diet. After five generations in which there was no further selection for divergence in response to fescue toxicosis, the current experiment was conducted to determine whether resistant (R) and susceptible (S) lines differed in response to the mycotoxin sporidesmin (SPD). At approximately 8 wk of age, R and S mice that had never consumed endophyte-infected fescue seed were randomly assigned (five to seven per line x sex x SPD dose subclass) to receive dimethyl sulfoxide (DMSO) carrier or 10, 20, 30, or 40 mg/kg SPD by oral gavage. At death or euthanasia 14 d after treatment, livers and kidneys were collected for histological examination. Mice receiving 40 mg/kg SPD died sooner than mice receiving 30 mg/kg (63 vs 134 h; P = .02), but there was no line or line x dose interaction effect for time to death. Within those mice, neither line, dose, nor their interaction influenced liver weight or liver weight as a proportion of body weight. The R mice were more resistant to SPD than S mice; LD50 values were 23.6 and 31.8 mg/kg for the S and R lines, respectively (P < .05). Sporidesmin caused dose-related liver and kidney lesions in both lines. Selection lines did not differ significantly in the incidence of infarcts of hepatic lobules. However, at 30 and 40 mg/kg SPD doses, severity of this lesion was higher in affected S than in affected R mice. At the higher SPD doses, there also was a greater incidence of hepatic subacute cholangitis in S mice than in R mice. Foci of acute tubular necrosis were found in kidneys of mice receiving 20, 30, or 40 mg/kg SPD, with no protection against these lesions in the R line. Foci of tubular basophilia (indicative of tubular regeneration) were present in all line x dose subgroups, but incidence was not SPD dose-dependent in either line. In summary, divergent selection for weight gain response to ingestion of endophyte-infected fescue seed resulted in a favorable correlated response in survival following exposure to a chemically distinct toxin. It may be possible therefore, to select livestock populations for simultaneous resistance to a variety of toxins.

Starter Period Digestible Valine Requirement of Female Nicholas Poults

Two experiments were conducted to determine the digestible Valine requirement in female Nicholas poults. A low-protein corn-soybean meal diet with added amino acids was used for the valine titration. Body weight gain and feed conversion responses to increasing dietary valine were measured. In Experiment 1, a wide range of valine levels were fed, with poults that received 0.79% or more digestible valine achieving maximal growth rate and feed efficiency. A narrower titration was used in Experiment 2, in which poults receiving 0.82% digestible valine were significantly heavier than those fed 0.75% or lower levels. The average growth data subjected to broken-line analysis indicated that the digestible valine requirement for maximum body weight gain was 0.82%. These studies indicate that in a corn-soybean meal diet containing 3218 kcal ME/kg, the dietary valine requirement of starting female Nicholas poults, expressed on a digestible basis, is 0.82%.

Absence of a weight gain response to Vitamin B12 supplementation in weaned dairy heifers grazing pastures of marginal cobalt content

Aim. To obtain information on serum and liver vitamin B12 and urinary methylmalonic acid concentrations as diagnostic tests to predict a weight gain response to supplementation with vitamin B12 in young dairy cattle when grazing pasture of low cobalt content. Methodology. Forty dairy cattle (12 Friesian, 14 Friesian × Jersey and 14 Jersey) were allocated to two equal sized groups, treated and untreated, based on liveweight. At monthly intervals for 14 months, all animals were weighed, their serum and urine sampled, their liver biopsied and the pasture sampled from the paddocks they were grazing and going to graze. Serum and liver were assayed for Vitamin B12 concentrations. For the first 5 months of the trial, urine was assayed for methylmalonic acid concentrations. Both washed and unwashed pasture samples were assayed for cobalt concentrations. Results. No weight gain response occurred to Vitamin B12 supplementation in young growing cattle grazing pasture with a cobalt concentration of 0.04-0.06 mg/kg DM. For 5 months of the trial, liver Vitamin B12 concentrations from untreated calves were in the range 75-220 nmol/kg and serum vitamin B12 concentrations were as low as 72 pmol/1. There was no associated growth response to supplementation. Conclusion. Further trials involving young cattle grazing pastures with cobalt concentrations less than 0.04 mg/kg DM are required to reliably determine liver and serum Vitamin B12 concentrations at which growth responses to Vitamin B12 or cobalt supplementation are likely under New Zealand pastoral grazing conditions.

Quantitative dietary requirements of postlarval tiger shrimp, Penaeus monodon, for histidine, isoleucine, leucine, phenylalanine and tryptophan

The quantitative requirements of postlarvae Penaeus monodon for essential amino acids were determined through a series of feeding experiments. Test diets contained casein–gelatin as natural proteins supplemented with crystalline l-amino acids (CAAs) at levels based upon the tissue amino acid profile of postlarvae tiger shrimp. Each set of experimental diets contained graded levels of the test amino acid in a range below and above those found in shrimp muscle protein. The dietary CAA mixture was pre-coated with carboxymethylcellulose (CMC), and the diets were additionally bound with CMC, corn starch, and K-carrageenan to prevent leaching of amino acids and other nutrients. P. monodon postlarvae, PL 20, mean body weight of 20 mg, were randomly distributed to 30-l fiberglass tanks at a density of 10/tank and each group was fed a particular diet for 56 days. A one-way analysis of variance was used to determine if there were any significant differences in weight gain, survival, and feed conversion among the dietary treatments for each experiments. Regression analysis of the weight gain responses against dietary amino acid levels was used to estimate the amino acid requirements. The optimum dietary requirements for essential amino acids, in percent of the diet, were: 0.8% histidine, 1.01% isoleucine, 1.7% leucine, 1.4% phenylalanine, and 0.2% tryptophan. Expressed as percent of the dietary protein, the requirement values were: 2.2% histidine, 2.7% isoleucine, 4.3% leucine, 3.7% phenylalanine, and 0.5% tryptophan. This information is crucial in optimizing growth and feed efficiency and in developing cost-effective diets for P. monodon.

Ideal amino acid profile and dietary lysine specification for broiler chickens of 20 to 40 days of age

1. The aim of the study was to determine the ideal ratio of the essential amino acids lysine (Lys), methionine (Met), threonine (Thr), tryptophan (Trp), arginine (Arg), valine (Val) and isoleucine (Ile) and to assess the required dietary lysine concentration for optimum performance in broiler chickens of 2 commercial strains from 20 to 40 d of age. 2. An identical basal diet was used throughout all experiments. It consisted mainly of maize and soyabean meal and contained 172 g crude protein and 13.2 MJ AME was adequately supplemented with all essential amino acids except the one to be tested, which was supplemented in 6 graded concentrations in exchange for maize starch. One (Met, Trp, Arg, Val, Ile) or 2 (Lys, Thr) growth trials were conducted per amino acid tested and the response in weight gain, food: gain ratio, breast meat yield and abdominal fat were examined. 3. The ideal amino acid ratio relative to Lys (expressed as a percentage) was calculated to be 75% Met+Cys, 63% Thr, 19% Trp, 112% Arg, 71% Ile and 81% Val on a true faecal digestible basis when the data were subjected to broken-line regression analysis. From both lysine studies the concentration for optimum food: gain ratio was calculated, by exponential regression analysis, to be 11.5 g true faecal digestible lys per kg diet. per kg. For each experiment, the basal diet N

Microbial phytase in finisher diets of White Pekin ducks: effects on growth performance, plasma phosphorus concentration, and leg bone characteristics

Two experiments (Exp.) were conducted to determine the growth response of White Pekin ducks to inclusion of microbial phytase in finisher diet. In Exp. 1, 1-d-old male ducks (240 total) were reared in litter-floor pens and fed regular starter diet until 3 wk of age. At 3 wk of age, ducks were randomly divided into six groups of 10 ducks each and each group was fed one of four diets. Three finisher diets containing 16% CP and 0.18% available phosphorus (AP) without supplemental P were formulated with microbial phytase (Natuphos) added at 0, 750, or 1,500 phytase units/kg of diet. The fourth diet was a control finisher diet that was supplemented with dicalcium phosphate (DCP) to supply dietary AP of 0.41%. Group BW and feed intake were measured weekly to assess growth response. At 6 wk of age, leg bones (tibia, femur, metatarsus) from five randomly selected ducks were removed and analyzed for bone characteristics. In Exp. 2, a total of 120 ducks reared as in Exp. 1 were randomly divided into six groups of five ducks each and fed one of four diets. A basal finisher diet was formulated to contain 16% CP and 0.18% AP. Monosodium phosphate was added to the basal diet to give dietary AP levels of 0.18, 0.27, and 0.36%. The fourth diet was the basal diet supplemented with microbial phytase (750 phytase units/kg of diet). Ducks were fed these diets from 3 to 6 wk of age. At the end of the study, ducks were bled by cardiac puncture and blood plasma was analyzed for P concentration. Leg bones from all ducks were removed and analyzed for bone characteristics as in Exp. 1. Feed intake increased linearly with increased level of dietary phytase, whereas the weight gain response was quadratic only during the last week of Exp. 1. In Exp. 2, there was a quadratic response for weight gain due to dietary AP. Weight gain due to phytase (750 units) was not different from ducks fed diets at 0 or 0.18% AP. Plasma P concentration increased linearly as dietary AP increased. Plasma P levels of ducks fed phytase were similar to those of ducks fed 0.18% AP but lower than in ducks fed 0.27% AP. Estimates of AP resulting from the addition of 750 units of phytase to basal diet were 0.05 and 0.07% based on plasma P concentration and weight gain, respectively. Using regression analysis, the AP due to phytase effect in the diet was estimated to range from 0.06 to 0.08%. Results suggest that phytase can be used in finisher diets similar to the one used in this study for ducks from 3 to 6 wk of age to improve growth performance and leg bone development similar to ducks fed diets supplemented with P from inorganic sources.

Responses in the growth of body components of finishing lambs to additional metabolizable energy supplied from either grass silage or concentrates

AbstractTwo experiments involving 213 finishing lambs were carried out to examine the responses in growth rate and carcass composition to the addition ofmetabolizable energy (ME) to a mixed diet in theform ofeither grass silage concentrate. In the second experiment the performance of lambs offered silage only was also compared at equal intake with the performance of lambs given mixed diets. On average the silages contained 224 g dry matter (DM) per kg; 148 g crude protein (CP) per kg DM; 86 g ammonia-nitrogen per kg total nitrogen and 723 g digestible organic matter per kg DM. Concentrates were based on barley and soya-bean meal and contained 181 g CP per DM. Responses in carcass weight gain when additional ME was added to mixed silagelconcentrate diets in theform ofgrass silage and concentrates were 9·2 and 10·2 (s.e. 0·90) gIM] respectively in experiment 1 and 9·8 and 10-(s.e. 0·33) g/MJ respectively in experiment 2, and responses in energy retention in experiment 2 were 0·34 and 0-(s.e. 0·012) MJ/M] respectively. However carcass gain and energy retention sustained by a silage only diet were only 0·67 and 0·70 respectively of those sustained by a high-concentrate diet at the same ME intake. The diet did not significantly affect body or carcass composition.

D-allothreonine has no growth promoting efficacy for chicks

One hundred and sixteen crossbred male chicks were used in two battery trials to establish the biological efficacy and toxicity of D-allothreonine (D-allo-Thr) relative to L-Thr. In the efficacy trial, graded doses of D-allo-Thr or L-Thr were added to a Thr-deficient (0.24% L-Thr) chemically defined diet and fed to chicks during the period 10 to 21 d posthatching. Addition of 0, 0.09, and 0.18% L-Thr produced marked linear (P < 0.01) growth and feed efficiency responses, but addition of 0.18 or 0.36% D-allo-Thr did not elicit a response in either weight gain or feed efficiency. In the toxicity trial, 2% D-allo-Thr or 2% L-Thr were added to a conventional 23% CP corn-soybean meal starter diet. During an 11-d feeding period, neither weight gain nor voluntary feed intake were affected (P > 0.10) by 2% additions of either compound. This experiment demonstrates that chicks cannot metabolize D-allo-Thr to L-Thr and that neither L-Thr nor D-allo-Thr are growth depressing when provided in a large surfeit.

Pulmonary function correlates in the prediction of long-term weight gain in cystic fibrosis patients with gastrostomy tube feedings.

Gastrostomy tube feedings have a positive effect on nutritional status and are currently recommended for cystic fibrosis patients who fall below 85% ideal weight for height. However, the impact of pulmonary function at the time of gastrostomy tube placement on long-term nutritional status has not been ascertained. We retrospectively evaluated whether nutrition status and/or pulmonary function at gastrostomy tube placement surgery were predictive of subsequent long-term (> or =2 yrs) weight velocity. We identified 21 cystic fibrosis patients (12 male), ages 5-18 years at gastrostomy tube insertion. Patients were divided into two groups according to their weight gain response after 2 years on gastrostomy tube feeding. Responders were defined as having a positive change in weight/age z-score (deltaWAZpost) at 2 years follow-up compared to the 2 year period preceding gastrostomy tube insertion (deltaWAZpre). Nonresponders were defined as having a negative WAZpost. Responders had significantly better FEV1 at surgery (61 +/- 26 [SE] vs. 24 +/- 3 %pred.; p < 0.05). In responders, epsilonWAZpre was -0.37 +/- 0.08 and was -0.46 +/- 0.07 in nonresponders (p-NS). In contrast, AWAZpost was 0.92 +/- 0.11 in responders and -0.40 +/- 0.07 in nonresponders (p < 0.001). Furthermore, a significant correlation between weight/age z-score change and pulmonary function was found when FEV1 <40% predicted (r = 0.88; p < 0.004) whereas no significant correlation was present when FEV1 > or =40% predicted. We conclude that the long-term nutritional benefit of gastrostomy tube placement is critically dependent on pre-surgical pulmonary function. Our findings suggest that gastrostomy tube insertion in malnourished cystic fibrosis patients should be considered an early intervention rather than one of last resort.