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PubMedDate not supplied

Factors contributing to preterm infant engagement during bottle-feeding.

BACKGROUND: Preterm infants have difficulty maintaining engagement throughout early oral feedings, which can lead to less efficient feeding and prolonged feeding skill development. OBJECTIVE: To examine contributions of the infant, mother, and feeding context to infant engagement during bottle-feeding. METHODS: Bottle-feedings of very-low-birthweight infants (n = 22) by their mothers were observed. Infant and maternal behaviors were coded and synchronized with physiologic measures. At completion of the feeding, the mothers were interviewed, and their working model of feeding coregulation was scored. Feedings were subdivided into feeding episodes (n = 114). Using multilevel linear regression analyses, four dyadic characteristics (working model of the caregiver's role as coregulator, birthweight, postconceptional age, baseline oxygen saturation) and five episode characteristics (readiness at episode onset, episode baseline oxygen saturation, mean oxygen saturation during the episode, maternal feeding behavior, and phase of feeding) were examined as potential predictors of feeding episode engagement. RESULTS: Conditions observed during the feeding observation explained most of the variation in engagement. Engagement was more likely to occur during the early phase of feeding (p <.05), during feeding episodes that began with infant readiness (p <.05), and during feeding episodes with higher mean oxygen saturation during the episode (p <.05). Feeding episodes with less jiggling of the nipple had a significantly greater amount of engagement (p <.05). CONCLUSIONS: The ability of the preterm infant to maintain engagement during bottle-feeding cannot be explained by characteristics of the infant or by the prefeeding condition of the infant alone. Rather, engagement is coregulated by the caregiver and the infant throughout the feeding. Strategies to assist infants in maintaining physiologic stability during bottle-feeding and further study of effective and contingent caregiver feeding behaviors are needed.

Adult↗

PubMed1987

Sexual dimorphism in broilers following periods of equal water and feed intake.

A study involving three experiments was conducted to investigate patterns of feed and water intake following an initial period in which both sexes received the same water or feed allowance. Restriction of water to an equal intake level in males and females from 0 to 10 days resulted in similar feed intake patterns and similar body weights for both sexes. Following exposure to ad libitum water, males immediately consumed 7 to 11% more water than females, while the accompanying change in feed intake was smaller in magnitude (1 to 6%). Restriction of feed to equal intake levels in both sexes from 0 to 12 days resulted in males and females consuming similar amounts of water. Body weights of males were slightly greater than female weights due to differences in feed efficiency. Following placement under ad libitum feed, males consumed more feed than females (8 to 9%). However, the divergence in feed intake following feed restriction between sexes was more gradual than the divergence in water intake following water restriction. These data indicate that feed and water intake patterns of males and females are controlled by inherent mechanisms independent of differences in body weight or maintenance requirements.

Animals↗

PubMed1989

Dietary protein level and essential amino acid content: influence upon female broiler performance during the grower period.

Three experiments were conducted to determine effects of dietary CP level and essential amino acid (EAA) content upon female broiler performance during the grower period (21 to 42 days). In each experiment, the design included a diet containing a conventional CP level (17.8 to 19.0%) and a low CP diet (15.9 to 16.7%) supplemented with several EAA. Regardless of CP content, all diets were formulated to meet National Research Council requirements in 1984 of EAA and to be isocaloric. As additional treatments, modifications of the low CP diet were made in an attempt to improve broiler performance. In Experiments 1 and 2, body weight gain (BWG) and feed efficiency (FE) were significantly impaired by feeding the low CP diet despite various combinations of increased levels of methionine, lysine, arginine, threonine, isoleucine, and tryptophan. In Experiment 3, BWG and FE were not significantly influenced by dietary CP level. Feed intake was unaffected by treatment except when a high level of glutamic acid (GLU) was added; this lowered the intake. The low CP diets increased abdominal fat deposition, which was prevented by 5% GLU supplementation. Breast yield was not affected by diet composition. Plasma free amino acids responded, in some cases, to changes in dietary EAA content.

Amino Acids, Essential↗

PubMed1996

Changes in body composition and adipocyte cellularity of male broilers subjected to varying degrees of early-life feed restriction.

Three experiments were conducted to determine growth performance, body composition changes, and adipocyte characteristics of male broilers subjected to early-life feed restriction. The purpose of Experiment 1 was to determine 42-d growth performance and body composition changes. Treatments used were full-fed control and 50% physical feed restriction during the period 6 to 12 d of age. Experiment 2 was conducted to determine the adipocyte characteristics during and after feed restriction to 42 d of age. An additional treatment involved gradual refeeding following the feed restriction period. Experiment 3 was designed to test the effect of feeding different types of dietary fat during realimentation on the abdominal fat pad (AFP) size, and lasted until 18 d of age. Three types of fats were tested, namely animal-vegetable (A-V) blend, flax oil, and animal tallow, each represented by full-fed and feed-restricted treatments. Complete compensatory growth by feed-restricted birds relative to controls was not achieved by 42 d in either Experiments 1 or 2. Early feed restriction resulted in lower body fat percentage at 12 d (P < 0.05), although by 42 d a higher rate of fat deposition mainly by hypertrophy of adipocytes resulted in no difference in fatness. Gradual reintroduction into ad libitum feeding did not alter such adipocyte hypertrophy nor improve compensatory growth response during refeeding. There was consistent improvement in feed efficiency associated with early-life feed restriction (P < 0.05). The use of different types of dietary fat did not effect the AFP when expressed as percentage body weight. Birds that were fed A-V blend during the refeeding period had bigger AFP (grams per bird), a situation that is attributable to differences in body weight. Attainment of growth compensation by the feed-restricted broilers apparently requires a more prolonged growth period or a less severe feed restriction program than that used here. Saturation of dietary fat has no effect on realimentation characteristics of the broiler.

Adipocytes↗

PubMed2004

Nutrition and feed management strategies to reduce nutrient excretions and odors from swine manure.

Manipulation of the pig's diet to reduce nutrient excretions and odors is feasible and practical. Avoiding excessive dietary protein, using high quality protein sources, and feeding low protein, amino acid supplemented diets are practices that will reduce the N in excreta. Avoiding excessive overages of dietary P, balancing diets on an available P basis, and use of phytase as a dietary supplement offers potential for further reducing the P in manure. Use of reduced or organic forms of Cu, Zn, Fe and Mg will reduce excretion of these nutrients in manure. Feeding management technologies that will enhance feed efficiencies and reduce nutrient excretion include feeding for phase, sex and genetic ability of the animal. Reducing the intact protein levels in diets and balancing with synthetic amino acids, use of low levels of specific non-starch polysaccharides (NSP; soybean hulls, sugar beet pulp), and maintaining the proper acid-base balance and buffering in the diet can significantly reduce odorous compounds. Greater nutrient reductions may be possible through the development of specialty feed ingredients that will be used for specific animal diets. Research to fine-tune the diets for production systems is needed.

Animal Feed↗

PubMed1991

Posthatching changes in the immunoglobulin A concentration in the jejunum and bile of turkeys.

An experiment was conducted to document the age-related changes in IgA concentration in the small intestine of newly hatched turkey poults reared in floor pens and to determine whether infection with stunting syndrome (SS) affects age-related changes. Day-old turkey poults were dose per os with .5 mL of saline carrier (control) or with .5 mL of one of two dilutions (250- or 2.5 x 10(6)-fold) of a "crude" SS-causing inoculum. Inoculation with the 250-fold dilution depressed body weight gain (P less than .01) throughout the experiment and impaired feed efficiency (P less than .05) at 5 and 9 days of age as compared with the control group. After 9 days of age, all inoculated poults utilized feed more efficiently than did control poults (P less than .01). Stunting syndrome did not affect IgA concentrations in either bile or jejunum at any specific age. Age-related changes in IgA concentrations, however, were observed. Bile IgA decreased from 1 to 9 days of age, and then increased until 29 days of age. The IgA concentration in jejunal tissue increased linearly from 1 to 29 days of age (P less than .01), whether expressed as IgA concentration per gram of wet tissue or as percentage of total protein in jejunum. Age-related changes in IgA concentration in both bile and jejunum suggest that the secretory immune system associated with the digestive mucosa is not fully developed at the time of hatch.

Aging↗

PubMed1986

An identified histaminergic neuron modulates feeding motor circuitry in Aplysia.

An identified histaminergic neuron, C2, in the marine mollusk Aplysia is a complex mechanoafferent which appears to contribute to the maintenance of food arousal by means of its synaptic connections to the metacerebral cell (MCC). Because C2 also has extensive synaptic outputs to neurons other than the MCC, we studied its possible motor functions. We identified several synaptic followers of C2 and found that some were excitatory motor neurons for extrinsic muscles of the buccal mass, while others were modulatory motor neurons that inhibited contractions. In addition, we found that these neurons and other synaptic followers of C2 received powerful inputs during feeding motor programs. In order to determine the functional significance of the synaptic outputs of C2, we studied extrinsic buccal muscles (E4 and E5) whose motor neuron (C6) is excited by C2. Extracellular recordings from these muscles indicated that they receive input during swallowing and rejection, but not during biting movements. Lesions of these muscles, or of all extrinsic muscles, did not prevent animals from feeding, but decreased feeding efficiency, that is, the amount of seaweed an animal could ingest with each swallow. The data suggest that C2 is an integrative proprioceptive cell that functions as a premotor neuron. The non-MCC synaptic outputs of C2 may reinforce the actions of the central feeding motor program. Specifically, C2 appears to aid the functioning of muscles that produce fine adjustments of the buccal mass and contribute to the efficiency of feeding behavior, rather than in producing gross movements.

Animals↗

PubMed1981

Oocyst discharge, rumen metabolism and performance of early weaned lambs with naturally occurring coccidiosis fed monensin.

Ninety-six 9.5 kg early-weaned lambs with naturally occurring coccidiosis were fed monensin either at 0, 11, 22, or 33 mg/kg of feed for 105 days. Fecal oocyst discharge during the first three days was highest with monensin 22 mg, lowest with monensin 33 mg and averaged 149.6 x 10(3) oocysts per gram feces for all lambs. Monensin at 22 mg/kg of feed reduced Eimeria ninakohlyakimovae and E. ahsata oocyst discharge. Organic matter and crude protein digestibilities were highest (P </= 0.05) in lambs fed monensin 22 mg/kg of feed. Monensin increased (P </= 0.01) rumen ammonia and propionic acid and decreased (P </= 0.01) acetic acid. Feeding monensin 33 mg decreased (P </= 0.05) feed intake by 5% and had no effect on gain or feed efficiency. Optimal responses were observed with monensin at 11 mg, feed consumption was not affected, gains were 8% higher (P </= 0.05) and feed was utilized 9% more efficiently (P </= 0.05) than the controls. In conclusion, monensin was an effective therapeutic agent against naturally occurring coccidial infections in early weaned lambs. Performance responses were largest with monensin fed at the rate of 11 mg/kg of feed.

Animals↗

PubMed1994

The value of creep feeding during the last 84, 56, or 28 days prior to weaning on growth performance of nursing calves grazing endophyte-infected tall fescue.

To evaluate limiting the number of days that calves are creep fed, 84 crossbred cows (frame score 4) nursing steer calves were randomly assigned to three replicates over 2 yr to receive one of four lengths of creep feeding (0, 28, 56, or 84 d) for cows and calves grazing endophyte-infected tall fescue. There were no differences in cow performance due to treatments. Calf daily gain increased (P < .001) as the length of time exposed to creep increased. In yr 1, creep intake increased (P < .05) as the length to time exposed to creep increased. In yr 2, there was no difference in intake by period among 28-, 56-, and 84-d treatments. Supplemental feed efficiency was best for 56 and 84 d, and the 28-d treatment was extremely poor. During the feedlot phase, there were differences in performance between the 2 yr and there were no differences in carcass composition due to length of time receiving creep feed. Overall, creep feeding calves for 56 or 84 d improved performance, and the 56-d calves had the most efficient gain. Creep feeding calves for 28 d showed no advantage during the creep feeding period or in the feedlot. Four ruminally fistulated nursing steer calves were used in a 4 x 4 Latin square design to receive treatments of forage alone or .68 kg, 1.13 kg, or 2.27 kg/d of creep plus high-quality, freshly harvested forage available on an ad libitum basis. Forage OM intake and NDF digestibility tended (P = .11) to decrease as intake of creep feed increased. The pH decreased (P < .001), molar proportion of propionate tended to increase (P = .06), and acetate tended to decrease (P = .07) as the level of creep feed intake increased. Higher levels of creep feed tended to cause a decrease in ruminal fiber digestibility and forage intake. Creep feeding calves for 56 or 84 d improved gain; 56 d had the most efficient supplemental gain. Creep feeding calves for 28 d showed no advantage during the creep feeding period or in the feedlot.

Adipose Tissue↗

PubMed1985

Aflatoxin-antioxidant effects on growth of young chicks.

Butylated hydroxytoluene (BHT), an antioxidant, was provided to chicks at 8 X, 30 X and 80 X the normal concentrations in their feed beginning at 1 day of age and continuing for the next 6 weeks. The ability of these birds to resist the adverse effects of dietary aflatoxin (3000 ppb, beginning Day 8) was measured by weight gain and feed efficiency over the 6-week period of study. Birds on aflatoxin-contaminated feed did not gain weight as rapidly or as efficiently as birds on uncontaminated feed. Depression of growth caused by aflatoxin was significantly less in birds given BHT than in those fed the diet not containing antioxidant.

Aflatoxins↗

PubMed1999

Effect of dietary phosphorus on finishing steer performance, bone status, and carcass maturity.

Yearling crossbred steers (n = 60; 386 kg) were individually fed in a completely randomized experimental design to determine their P requirement. Treatments were in a factorial arrangement with two levels of Ca (.35 or .70% of DM) and five concentrations of P (.14, .19, .24, .29, or .34% of DM). The finishing diet consisted of 34.5% dry-rolled corn, 22.5% brewers grits, 22.5% corn bran, 7.5% ground corncobs, 5% molasses, 3% fat, and 5% supplement. Supplemental P was provided as monosodium phosphate and Ca as limestone. Ash content was determined on the first phalanx bone from the lower front legs following slaughter, and rib bone breaking strength was determined with an Instron Universal Testing Machine. Carcass maturity and shear force were also evaluated on wholesale rib cuts. Because no interactions between Ca and P levels were detected, only main effects are presented. Daily gain, DMI, and feed efficiency were not affected by dietary P concentration or P intake. Bone ash (g or g/100 kg BW) and rib bone breaking strength were also unaffected by dietary P. Feeding .7% Ca decreased (P<.06) ADG and efficiency compared with feeding .35% Ca. Neither dietary Ca nor P had a significant effect on tenderness (shear force), skeletal maturity, or overall maturity. These results indicate that the P requirement for finishing yearlings is .14% of diet DM or less and that supplementing P above levels supplied by basal ingredients in many grain-based finishing diets is not necessary.

Animals↗

PubMed1997

Maintenance threonine requirement and efficiency of its use for accretion of whole-body threonine and protein in young chicks.

Broiler chicks were fed on chemically-defined crystalline amino acid diets containing graded levels of L-threonine (Thr) during the period 10-20 d post-hatching. Doses of Thr represented 5, 10, 15, 40, 55, 70 and 95% of its ideal level for maximal weight gain and feed efficiency. Other amino acids were maintained at minimized excess levels that were 15% (of ideal) above the various doses of Thr. Following 10 d of feeding and a 24 h fast, chicks were killed for whole-body protein and amino acid analysis. Using pen accretion means, weight gain (r2 0.98), protein accretion (r2 0.99), and Thr accretion (r2 0.99) were linear (P < 0.01) functions of Thr intake. Slope of the Thr accretion regression line indicated that 82% of the Thr intake was recovered in whole-body protein. At zero Thr intake, chicks lost 11.9 mg Thr/d. The Thr maintenance requirement was 45.7 mg/d per kg body weight 0.75. Increasing doses of Thr resulted in increased (P < 0.05) concentrations of methionine, isoleucine, histidine and lysine in whole-body protein. Other indispensable amino acids, including Thr, also tended to increase. Whole-body glycine, proline, serine and cystine concentrations decreased (P < 0.05) as Thr was increased in the diet. The maintenance need for Thr represented 5.5% of the total need for Thr. The data suggest that efficiency of Thr utilization is constant at all levels of Thr intake between 5 and 95% of the level required for maximal weight gain and feed efficiency.

Analysis of Variance↗

PubMed1987

Stimulation of supranormal growth in prepubertal, adult plateaued, and hypophysectomized female rats by large doses of rat growth hormone: physiological effects and adverse consequences.

A supranormal rate of growth in intact, prepubertal, 26-day-old female rats was evoked by administration of large doses of highly purified rat GH (rGH). In response to daily doses of 1 and 5 mg/rat (13.6 mg/kg BW and 68 mg/kg BW), sc, for 20 days, body weight (BW) gain increased 51% and 73%, and skeletal growth increased 27% and 40%, respectively. Serum rGH in treated rats rose as much as 69-fold greater than that of controls. Feed efficiency, the ratio of weight gained to feed consumed, increased from 19.8% to 32.0%. This rGH treatment depleted pituitary GH content as much as 58% and caused hepatomegaly. These effects, as well as the accelerated growth rate, reverted to normal after cessation of rGH treatment. Onset of puberty in rGH-treated rats was delayed an average of 2.7 days. A similar stimulatory effect on BW gain, but not skeletal growth, as well as depletion of pituitary GH content, and hepatomegaly, was elicited by rGH treatment in adult, plateaued female rats. These effects in plateaued rats reverted to normal after cessation of GH treatment, and 50% of the body weight gain was rapidly lost. The largest dose of rGH used, 5 mg/day, was apparently toxic, resulting in a 20% higher mortality rate in treated prepubertal and plateaued female rats. Antibody formation was not the cause of the toxicity, since antibodies against rGH were undetectable at the lowest dilutions of serum tested. Serum rat insulin-like growth factor I (RIA), 3.5 U/ml in untreated intact prepubertal rats, increased to 4.7 and 5.0 U/ml, respectively, after 20 days of rGH treatment. In hypophysectomized rats, serum rat insulin-like growth factor I (RIA), undetectable in controls, was increased to 1.63 U/ml after 14 days treatment with 1 mg rGH/day. This study demonstrates that greater than normal growth can be stimulated in normal female rats by administration of large doses of homologous GH, but at the risk of serious adverse effects. Possible implications for the administration of GH to non-GH-deficient children, to promote taller stature, are clear.

Animals↗

PubMed1990

Effect of environmental stress on the ascorbic acid requirement of laying hens.

An experiment with a factorial arrangement of treatment (3 by 2 by 2 by 2) was conducted to determine the effect of ascorbic-acid supplementation (0, 100, and 200 ppm) on the performance of two commercial layer strains housed at a density of either 3 or 4 birds per cage and relative humidities (RH) of 40% or 60%. The hens were subjected to a continuous heat stress of 31.1 degrees C for the 3-mo experimental period. As a comparison with an unstressed control group, an additional group of hens was housed at 23.9 degrees C and 40% RH and was fed the diet without ascorbic-acid supplementation. Mortality was reduced by ascorbic-acid supplementation. Shell weight per unit surface area showed a small increase with the added ascorbic acid. Values (in Haugh units) were increased by ascorbic-acid supplementation at the 200 ppm level and by the lower relative humidity. The higher RH reduced egg production by 4.16% and changed feed efficiency from 2.29 to 2.45 g of feed intake per gram of egg mass. There were differences in blood pH, blood CO2, blood HCO3-, and blood and adrenal ascorbic-acid levels due to the housing temperature. The higher RH produced blood-chemistry changes that were typical of respiratory alkalosis, which has been shown to occur in layers at high temperatures. Higher cage density, on the other hand, showed no change in the HCO3 level; but blood pCO2 was increased while blood pH was decreased. These results demonstrate that ascorbic-acid supplementation can be effective in reducing laying-hen mortality due to environmental stress and has small influences on egg quality.

Adrenal Glands↗

PubMed1992

Effects of forage and protein source on feedlot performance and carcass traits of Holstein and crossbred beef steers.

Fifty-eight Holstein and 58 crossbred beef steers were individually fed one of four isonitrogenous diets to evaluate the effects of forage source (corn silage and alfalfa haylage) and protein source (soybean meal and fish meal) on feedlot performance. Phase 1 diets (up to 354 kg of BW) were 40% forage and 60% concentrates and were fed for 70 to 136 d (depending on diet and breed group). Phase 2 diets (354 kg of BW until slaughter) were 20% forage and 80% concentrates and were fed for 127 to 150 d (depending on diet and breed group). Slaughter end points were .6 cm of 12th rib fat for Holsteins and 1.0 cm of rib fat for crossbreds using real-time ultrasonic estimates. The steers were fed for a maximum of 330 d each year. Forage source was a significant component of variation for most growth, efficiency, and carcass traits. Holstein and crossbred steers fed alfalfa haylage had significantly lower average daily gain, feed efficiency, dressing percentage, and empty body fat and required more days on feed to reach slaughter end points, but had higher total feed energy intake available for production. Steers fed corn silage diets had significantly greater energetic efficiency (P less than .05) than those fed alfalfa haylage, due to increased use of ME to produce fat in the carcass. Protein type did not influence gain, feed or energetic efficiency, energy intake, or most carcass traits. A significant protein system x forage source interaction among the four diets was detected for crossbred steers fed corn silage and fish meal, for which there was significantly greater feed conversion with lower energy intake above maintenance, possibly due to better fiber digestion and(or) amino acid flow to the lower tract. Alfalfa haylage plus soybean meal diets decreased (P less than .05) the percentage of Holsteins grading USDA Choice or higher. These results indicate that corn silage, because of greater energy concentration, was a more desirable forage in feedlot diets composed of less than or equal to 40% forage and that protein type (soybean meal and fish meal) in growing diets is not an important factor in feedlot performance or carcass traits of Holstein or crossbred steers that are fed these diets.

Animal Feed↗

PubMed1988

Effects of recombinant chicken growth hormone in randombred meat-type chickens.

Recombinant chicken growth hormone (rcGH) was administered subcutaneously twice daily to male and female Athens-Canadian randombred meat-type chickens between 2 and 14 days posthatch. Treatment groups consisted of non-injected controls, saline-injected controls, and those injected with either 50 or 250 micrograms/kg rcGH per injection. Body weight, body weight gain, feed consumption, and feed efficiency were determined. Body weight or body weight gain was not significantly affected by rcGH through 28 d. Feed consumption and efficiency were not significantly affected by treatment through 21 d. It was concluded that rcGH failed to demonstrate any significant growth-promoting effects in young, slow-growing randombred chickens.

Animals↗

PubMed1993

A 91-day feeding study in rats with caprenin.

Caprenin, a randomized triglyceride primarily comprising caprylic (C8:0), capric (C10:0), and behenic (C22:0) acids, was administered in a semi-purified diet to weanling Sprague-Dawley rats (25/sex/group) at dose levels of 5.23, 10.23 or 15.00% (w/w) for 91 days. Corn oil was added at 8.96, 5.91 and 3.00%, respectively, to provide essential fatty acids and digestible fat calories. Corn oil alone (12.14%) and a blend of medium-chain triglyceride (MCT) oil plus corn oil (11.21 and 3.13%, respectively) served as controls. All diets were formulated to provide about 4000 kcal/kg of diet and 26.8% of digestible calories from fat by assuming that corn oil, MCT oil, and caprenin provided 9, 7 and 5 kcal/g, respectively. Survival, clinical signs, body weight, feed consumption, feed efficiency, organ weights, organ-to-body-weight ratios, organ-to-brain-weight ratios, haematological values and clinical chemistry parameters were evaluated in all groups. Histopathology of a full complement of tissues was evaluated in the corn oil and MCT oil control groups as well as the high-dose caprenin group. Additional rats (n = 5/sex/group) were included in the study to determine whether there was marked storage of C22:0 in heart, liver or perirenal fat at the end of the 91-day feeding period. No significant differences in body weight gain were measured with the balanced caloric diets, although feed conversion efficiency was reduced in the high-dose caprenin group. No adverse effects from the ingestion of caprenin were detected, nor were significant amounts of C22:0 present in the fat extracted from the selected fat depot sites. These results establish a no-observable-adverse-effect level (NOAEL) of more than 15% (w/w) caprenin in the diet (or more than 83% of total dietary fat), which is equal to a mean exposure level of more than 13.2 g/kg/day for male rats and more than 14.6 g/kg/day for female rats.

Adipose Tissue↗

PubMed1984

Effects of graded levels of lysine and excess arginine and threonine on young pigs fed practical diets.

Three experiments were conducted to estimate the lysine requirement of the weanling pig and the effects of excess arginine and threonine on that estimate. Feeding 1.15% dietary lysine in Exp. 1 and 1.20% in Exp. 2 maximized feed efficiency and resulted in the lowest plasma urea N values. Adding .15% threonine to the diets in Exp. 2 did not affect (P greater than .10) performance of the pigs, but increased (P less than .01) plasma urea N and decreased (P less than .01) plasma lysine concentrations. Supplemental arginine (.22%) did not affect performance of the growing pigs in Exp. 3, but it increased (P less than .01) plasma urea N. Pigs fed a corn-soybean meal diet utilized feed more efficiently (P less than .05) than those fed a corn-fish meal-dried whey diet. The most likely cause for this response was that the corn-soybean diet contained more lysine (.82%) than expected, whereas the corn-fish meal-dried whey diet had close to the expected content of lysine (.72%). From these results, it was concluded that the lysine requirement of the weanling pig fed practical diets is at least 1.15 or 1.20% of the diet. Also, added arginine or threonine did not adversely affect the performance of pigs.

Amino Acids, Essential↗