Features of inhalant allergy on nasal endoscopy: a systematic review and meta-analysis

BACKGROUND

Nasal endoscopy is increasingly accessible to ENT surgeons. The characteristics of the allergic upper airway are not well recognised.

METHODOLOGY

MEDLINE (1946-2021), EMBASE (1974-2021), and the Cochrane Library were searched on 16th November 2021 to identify articles that reported endoscopic findings of patients with documented allergy who had undergone nasal endoscopy. The review followed the Cochrane Handbook for Systematic Reviews of Diagnostic Test Accuracy. Meta-analysis was performed by pooling sensitivities and specificities using the hierarchical summary receiver operating characteristics model.

RESULTS

A total of 4108 articles were identified, of which 15 manuscripts met the inclusion criteria. The included studies involved 4660 patients who had undergone nasal endoscopy. Middle turbinate (diffuse/polypoid) oedema (sensitivity 58.0%, specificity 84.5%), watery secretions (sensitivity 65.7%, specificity 76.5%), inferior turbinate hypertrophy (sensitivity 86.2%, specificity 32.2%), and unspecified turbinate hypertrophy (sensitivity 82.0%, specificity 42.9%) were identified as the features with the highest predictive value of inhalant allergy.

CONCLUSIONS

Diffuse or polypoid oedema of the middle turbinate or watery secretions seen on nasal endoscopy can be a useful adjunct in the identification and diagnosis of inhalant allergy. These clinical features should be part of the diagnostic workup for patients that includes a clinical history and surrogate markers of allergic sensitisation from the skin and serum.

Imidazoline use in sinonasal surgery

The nasal mucosa is very vascular, receiving more blood flow per cubic centimeter of tissue than does muscle, brain or liver (Drettner and Aust, 1974; [1]). This vascularity can present a major problem during sinus surgery. Surgeons routinely use topical vasoconstrictors in endoscopic sinus surgery however, the optimal regimen is not clear. Imidazoline nasal sprays are often used up to 1hour before sinonasal surgery to aid in intraoperative vasoconstriction. After the induction of anaesthesia, epinephrine-based topical and submucosal preparations are subsequently administered to further enhance vasoconstriction. Imidazolines are non-selective, partial alpha adrenoceptor agonists with a higher affinity, yet lower potency, for alpha adrenoceptors when compared to epinephrine. It is hypothesized that imidazolines block the action of epinephrine on the alpha adrenoceptors of the nasal mucosa resulting in less vasoconstriction, and a poorer intra-operative field, when compared to the use of epinephrine alone. This paper hypothesizes that preoperative imidazoline administration may adversely affect optimal intra-operative vasoconstriction.

The response of entire male and female pigs from 20 to 100-kg liveweight to dietary available lysine

Two experiments were conducted to determine the responses of entire male and female pigs of the Australian Pig Improvement Co. genotype to dietary lysine. In Experiment 1, a total of 350 [Large White × (Landrace × Duroc)] entire male and female pigs weighing 22.3 ± 0.16 kg (mean ± s.e.m.) were used in a 2 by 5 factorial design with the main treatments being sex (entire males and females) and five levels of standardised ileal digestible (SID) lysine to digestible energy ratio (0.6, 0.7, 0.8, 0.9 and 1.0 g SID lysine/MJ DE). In Experiment 2, a total of 420 [Large White × (Landrace × Duroc)] entire male and female pigs weighing 49.6 ± 0.34 kg (mean ± s.e.m.) were used in a 2 by 5 factorial design with the main treatments being sex (entire males and females) and five levels of SID lysine to MJ DE ratio (0.4, 0.5, 0.6, 0.7 and 0.8 g). From 20 to 50 kg liveweight (LW), entire males had a similar average daily gain (ADG), lower feed intake (FI, P < 0.001) and better feed to gain ratio (F : G, P < 0.001) compared with females. From 50 to 100 kg LW, entire males had a higher ADG (P < 0.001), similar FI and improved F : G ratio (P < 0.001) compared with females. Data were subjected to the quadratic response model to determine optimum SID lysine requirement for maximum ADG and minimum F : G for the weight ranges 20–35, 35–50, 50–65, 65–80, and 80 to 95 kg LW. For male pigs, maximum ADG was achieved at SID lysine levels of 1.00, 0.87, 0.72, 0.67 and 0.63 g/MJ DE, respectively. Minimum F : G was achieved at SID lysine levels of 1.00, 0.87, 0.80, 0.69 and 0.63 g/MJ DE for the respective weight ranges. For female pigs, maximum ADG was achieved at SID lysine levels of 0.90, 0.84, 0.67, 0.63 and 0.58 g/MJ DE. Minimum F : G for females was achieved at SID lysine levels of 0.86, 0.85, 0.64, 0.66 and 0.40 g/MJ DE for the respective weight ranges. The results suggest that this Australian genotype requires greater dietary SID lysine in the growing and finishing phase than the levels currently used by the Australian industry.

Spray-dried porcine plasma and yeast derived protein meal influence the adaption to weaning of primiparous and multiparous sow progeny in different ways

Pigs from 154 litters (n = 1132, 19 ± 3 days of age, 4.9 ± 1.1 kg of bodyweight) were used in a 3 × 2 factorial design to evaluate two raw materials with nutraceutical properties being used in feeds, spray-dried porcine plasma (SDPP) and a yeast protein meal, and their effects on growth performance, immune parameters and gastrointestinal adaption of piglets to weaning. Factors included dietary treatments being (1) 5% SDPP (PLA), (2) 3.5% yeast protein meal (NUP) and (3) medicated control (TMC) and parity (primiparous versus multiparous). The treatment groups were imposed from Day 19 through to weaning at Day 27. Selected pigs (n = 720, 28 ± 3 days of age, 7.4 ± 1.0 kg of bodyweight) were weaned and remained on their respective diets from Day 28 to Day 34. From Day 35 to Day 48 all group-housed pigs were offered a commercial weaner 1 diet, and from Day 49 to Day 68 pigs were offered a commercial weaner 2 diet. Growth performance, survival, and serum immunoglobulin G were monitored throughout the nursery phase (Day 28 to Day 68). Adaptation of the gastrointestinal tract in the acute post-weaning phase (Day 28 to Day 34) was assessed in 36 individually housed male weaners, with the effects of feed on structural, digestive, microbial and immune parameters along the gastrointestinal tract determined at Day 34. Pre-weaning feed disappearance was greater (P < 0.01) in multiparous litters independent of diet. In the commercial nursery, total removals (mortality and morbidity) were highest (P < 0.01) in primiparous sow progeny, with pigs offered NUP having greater (P ≤ 0.05) total removals. Pigs offered PLA had superior average daily gain, average daily feed intake and feed conversion ratio from Day 28 to Day 34 (P < 0.05). Pigs offered NUP tended to (P = 0.07) have superior average daily gain from Day 35 to Day 49. Pigs offered NUP had higher (P < 0.05) serum immunoglobulin G concentrations at Day 68 compared with pigs offered TMC, with the effect most pronounced in primiparous sow progeny. Individually housed weaners offered PLA consumed more (P < 0.05) feed on Day 30 to Day 31, had shorter relative intestine length (P < 0.05), greater villous height in the medial jejunum (P < 0.10) and lower immuno-pathology scores along the intestine. Pigs offered PLA also tended (P < 0.10) to have increased pancreatic-specific lipase and amylase activity compared with pigs offered NUP. Pigs offered NUP had a higher ratio of E. coli : coliforms in the colon (P < 0.01) and more counts of β-haemolytic bacteria in the medial jejunum (P < 0.05) and colon (P < 0.10). Diets containing either SDPP or NUP offered pigs benefits beyond nutrition relative to the medicated control diet. The benefits of SDPP were highly effective but transient, while the yeast derived protein had a successive or accumulative effect which was more pronounced in primiparous sow progeny.

Reducing the length of time between slaughter and the secondary gonadotropin-releasing factor immunization improves growth performance and clears boar taint compounds in male finishing pigs

The objective of this study was to evaluate whether altering the timing of the secondary anti-gonadotropin-releasing factor (GnRF) immunization closer to slaughter in male finishing pigs would reduce the increase in P2 fat depth (6.5 cm from the midline over the last rib), while still limiting the incidence of boar taint. Entire male pigs are immunized against GnRF to reduce the concentration of testicular steroids that in turn limits the incidence of boar taint. Additionally, testicle measurements and color measurements were taken to examine whether they could be used to differentiate nonimmunized entire males from immunized male pigs. A total of 175 Large White × Landrace entire male pigs aged 16 wk (59 kg of BW) were used in a completely randomized design with 5 treatment groups based on the time that pigs received the secondary immunization before slaughter. Pigs were housed in groups of 7 and randomly allocated to 1 of 5 treatments with 5 replicates per treatment. The treatment groups were as follows: no secondary immunization before slaughter, and the secondary immunization given at 2, 3, 4, or 6 wk before slaughter. The P2 fat depth levels were reduced (P = 0.054) with the secondary immunization closer to slaughter (11.7, 11.3, 12.8, 12.6, and 13.7 mm for no secondary immunization, secondary immunization at 2, 3, 4, and 6 wk before slaughter, respectively). Androstenone concentration did not exceed the generally accepted industry sensory threshold of 1.0 µg/g of fat, and both androstenone concentration in the adipose tissue and testosterone concentrations in the blood were suppressed (P < 0.001) in all immunized pigs regardless of timing of the secondary immunization compared with pigs that did not receive the secondary immunization. Skatole concentration of all pigs in the experiment did not exceed the generally accepted industry sensory threshold of 0.2 µg/g. Testes weight was reduced (P < 0.001) with increased time between slaughter and the secondary immunization. Immunized pigs, regardless of time before slaughter, had greater L* (lightness) and b* (yellowness) color of the testicle surface (P < 0.001 and P = 0.020, respectively), and less a* (redness) color compared with entire males (P < 0.001). The study provides further evidence of the efficacy of the anti-GnRF immunization and indicates that the secondary immunization can be moved closer to slaughter, while still limiting the incidence of boar taint. Testicle measurements and color measurements together could provide a method of discrimination between carcasses from immunized entire males clear of boar taint and tainted carcasses.

Immunisation against gonadotrophin-releasing hormone (GnRH) increases growth and reduces variability in group-housed boars

It is generally accepted that entire boars are leaner and more efficient than barrows but that they have poorer meat quality with an increased risk of boar taint. An additional issue in producing boars to meet market specifications is variation in growth performance, which may be exacerbated by high levels of aggression and mounting behaviour in group-housed animals. Immunisation against gonadotrophin-releasing hormone (GnRH), leading to immunological castration, offers a means of reducing aggression and mounting behaviour while maintaining most of the production efficiencies associated with entire boars. A total of 120 control boars, 120 immunised boars and 60 barrows (physically castrated at 5 days of age) were used in a study conducted in two replicates. Each replicate consisted of two pens each of boars, immunised boars and barrows, each pen containing 15 pigs, and two blocks of 15 individually-housed boars and immunised boars. The group-housed pigs had access to two single place electronic feeders per pen. Immunised boars were given the anti-GnRH vaccine (Improvac) at 14 and 18 weeks of age. In the 2 weeks immediately after the secondary immunisation at 18 weeks, average daily gain was greater in the immunised boars than the boars or barrows, particularly in those that were group housed, as indicated by the interaction (P = 0.035). From 18 to 23 weeks of age average daily gain was greater (P = 0.005) in immunised boars than in control boars and barrows and was greater (P < 0.001) in individually- than in group-housed pigs. The average daily gain of group-housed immunised boars and individually-housed control boars were similar over the 5-week period after secondary immunisation (1090 vs 1099 g/day), being ~20 and 15% higher than the group-housed control boars and barrows, respectively. The average daily feed intake was greater (P = 0.011) in immunised boars than in control boars with barrows intermediate. The standard deviation of bodyweight increased with age but was lower (P from 0.032 to 0.09) in immunised boars than in control boars and barrows between 18 and 22 and 17 and 21 weeks of age. Carcass fighting damage and pork pH were higher (P < 0.05) for control boars than for immunised boars or barrows. In conclusion, immunisation against GnRH increased average daily gain and average daily feed intake while decreasing variation in bodyweight and improving carcass and pork quality.

Effect of liquid to feed ratio, steeping time, and enzyme supplementation on the performance of weaner pigs

Two experiments were conducted to examine the effect of liquid to feed ratio, steeping time, and enzyme supplementation on performance of weaner pigs. In Expt 1, 40 male weaner pigs (weaned at 27 days of age) were randomly allocated to 4 treatments, including a dry control and 3 liquid diets of differing liquid: feed ratios (2 : 1, 3 : 1, and 4 : 1). Pigs were fed individually. Bodyweight was measured weekly and feed intake measured daily. The results confirmed the advantage of liquid feeding but indicated that liquid: feed ratio had very little effect on performance of weaner pigs. Whereas the digestible energy (DE) content of the 2 : 1 and 3 : 1 diets was similar to the control diet, the DE content of the 4 : 1 diet was significantly lower, possibly due to the removal of the insoluble marker (long chain hydrocarbon) by the amount of water in the diet.In Expt 2, the effect of a xylanase and steeping time on pig performance was assessed in a 2 × 2 factorial design (2 steeping times, 1 h v. 15 h; enzyme addition, + v. –). Sixty male weaner pigs (weaned at 27 days of age) were randomly allocated to 4 treatments and fed individually for 3 weeks. Bodyweight was measured weekly and feed intake measured daily. The experiment revealed that both steeping and enzyme addition increased feed intake (P�<�0.01) and growth rate (P < 0.05), suggesting that both techniques influence the non-starch polysaccharide composition of the wheat-based diet. Feed conversion ratio (FCR) tended to be improved more by steeping than by enzyme addition (P = 0.06). The results would suggest that steeping improves FCR by allowing increased hydration of feed and subsequent activation of the endogenous enzymes present naturally in grains.The present study was designed to test the hypothesis that the water: solid feed ratio would affect nutrient availability to weaner pigs fed liquid diets.

Effects of particle size, processing, and dry or liquid feeding on performance of piglets

Currently, most feed grains are processed by either hammer mill or roller mill before the inclusion in pig diets. However, the effect of these two types of milling and particle size on the performance and feed utilisation has not been adequately examined. The effect of milling processing (hammer mill v. roller mill), particle size, and feeding method (liquid v. dry) was assessed in a factorial design with 120 weaner pigs over 21 days. These pigs had been weaned for 7 days when the experiment commenced. The results revealed that pigs fed on hammer-milled diets had a better performance than those on roller-milled diets. Particle size of hammer-milled diets did not affect the performance of pigs, but influenced the digestible energy content of the diets. However, the feed conversion ratio was poorer for pigs fed coarsely or medium roller-milled diets only at Day 7–14 after weaning. There was a marked advantage in terms of feed efficiency associated with liquid feeding. For pigs offered the hammer-milled diets between 0 and 14 days, simply adding the feed to water improved feed efficiency by some 22%. For the roller-milled diets the corresponding improvement in feed efficiency was 28%. Liquid feeding improved digestible energy (DE) value by 1.5 MJ/kg for medium particle size and depressed DE value by 0.8 MJ/kg for fine particle size for hammer mill. Liquid feeding improved DE values for both medium and fine particle treatments by 0.9 MJ/kg for roller-milled diets. It should be noted that the full advantages of liquid feeding could only be taken if feed wastage from this system can be minimised as much as possible.The study was conducted to investigate if processing method (roller v. hammer mill), particle size (coarse, medium, and fine), and feeding method (liquid v. dry) significantly improved the growth rate, feed intake, and feed conversion of the weaner pig.

The influence of dietary energy intake on growth performance and tissue deposition in pigs between 80 and 120 kg liveweight

Eighty crossbred pigs of a composite genotype were allocated at 80 kg liveweight to a 2 × 5 factorial experiment involving 2 sexes (boars and gilts) and 5 levels of dietary energy intake ranging from about 55% estimated ad libitum up to 100% ad libitum intake. The diet was formulated to be protein-adequate and contained 14.4 MJ DE/kg and 0.55 g available lysine/MJ DE and the pigs were slaughtered at approximately 120 kg liveweight. Growth rate and food conversion efficiency increased linearly, in response to increasing digestible energy (DE) intake, with boars consistently out-performing gilts at each level of DE intake. Protein deposition rate in the whole empty body of pigs was consistently higher in boars than in gilts and linearly related to DE intake in both sexes, with no evidence of a plateau at high energy intakes, suggesting no intrinsic limit to protein deposition in these pigs up to 120 kg liveweight. When pigs were offered the protein-adequate diet ad libitum between 80 and 120 kg liveweight, boars and gilts consumed 47.7 and 40.9 MJ DE/day, respectively, and protein deposition rates in the whole empty body of pigs reached 247 and 182 g/day, respectively. Maintenance energy requirements were estimated to be 351 kJ DE/kg0.75.day for both boars and gilts [maximal model; including nominal DE level (treated as a 5-level factor), actual DE intake (treated as a continuous variable), and sex (treated as a 2-level factor)] or 506 and 566 kJ DE/kg0.75.day for boars and gilts, respectively [reduced model; including actual DE intake (treated as a continuous variable) and sex (treated as a 2-level factor)]. Statistical analyses show that the maximal model reflects the data more closely than the minimal model, suggesting that the lower maintenance estimate of 351 kJ DE/kg0.75.day could reflect reality better. In conclusion, genetically improved boars, and to a lesser extent gilts, have a high capacity for lean growth, and their upper limit to protein retention might not be reached below about 120 kg liveweight.

Long-term, but not short-term, treatment with somatotropin during pregnancy in underfed pigs increases the body size of progeny at birth1

Treatment of pigs with porcine ST (pST) in early to mid-pregnancy increases body weight and length of their fetuses by mid-pregnancy, but this increased weight may not persist to birth. We investigated the effects of short- (25 d) and long-term (75 d) treatment with pST, and interactions between long-term pST treatment and crude protein content of diet, in restricted-fed gilts. In both experiments, Large White x Landrace gilts were bred at first estrus to Large White x Duroc boars and allowed to farrow naturally. In the first experiment, gilts were fed 1.8 kg/d of a diet containing 13.5 MJ DE/kg of DM and 15.05% CP (as-fed basis) throughout pregnancy, and were injected daily with 0, 2, or 4 mg pST from d 25 to 50 of pregnancy. Maternal treatment with pST from d 25 to 50 of pregnancy did not affect the number of piglets born per litter or progeny size at birth. In the second experiment, gilts were injected daily with 0 or 2 mg of pST and fed 2.2 kg/d of a diet containing 14.5 MJ DE/kg and either (as-fed basis) 16.6% (0.81% lysine) or 22.2% CP (1.16% lysine) from d 25 to 100 of pregnancy. All gilts were then fed 3.0 kg/d of the lower protein diet from d 100 of pregnancy to farrowing. Treatment with 2 mg pST/d from d 25 to 100 of pregnancy increased live weight of all gilts during the treatment period (P = 0.016), but the change in maternal live weight from d 25 to 100 of pregnancy was only increased (P = 0.001) by pST in gilts fed the higher protein diet. Live weight of gilts 1 d after farrowing was increased by pST treatment (P = 0.007), but was not altered by protein content of diet during pregnancy. In gilts fed the lower protein diet, but not in those fed the higher protein diet, pST treatment decreased maternal backfat depth during treatment (P < 0.020) and 1 d after farrowing (P = 0.002). Treatment with pST during pregnancy did not affect the number of piglets born per litter but independently increased body weight by 11.6% (P < 0.001) and length by 3.4% (P = 0.005) of progeny at birth and decreased (P < 0.01) the negative effect of litter size on body weight at birth. We conclude that in feed-restricted gilts, fetal weight gains in response to 25 d of pST treatment before mid-pregnancy are not maintained to term but that treatment with pST during most of pregnancy increases progeny size at birth and reduces maternal constraint of fetal growth.

Effects of storage time and exogenous xylanase supplementation of new season wheats on the performance of young male pigs

A series of experiments was conducted to investigate the influence of new season wheats on pig growth performance. Experiments were carried out on 10 different wheats at the time of harvest and 10 mo post-harvest. At harvest wheat, at a 65% level in the steam-pelleted diets, influenced (P < 0.01) feed intake and daily gain over a 21-d trial. Thus, feed intake and daily gain of pigs offered the lowest and highest quality wheats varied by 47 and 48%, respectively. There was, however, no effect on feed conversion ratio (FCR), even though dry matter (DM) digestibility and digestible energy (DE) values of different wheats differed significantly (P < 0.01 and P < 0.01, respectively). The non-starch carbohydrate (NSC) level of the wheats was measured as the sum of non-starch polysaccharides (NSP) and free sugars. The NSC level of the wheats negatively affected feed intake (r2 = -0.556: P < 0.01) and daily gain (r2 = -0.574: P < 0.01). After 10 mo of storage, the feed intake and daily gain of the pigs fed the same wheats were significantly (P < 0.01) higher, but not all the wheats responded to storage. A xylanase product was added to three of the 10 mo-old wheats, which were pre-characterized as low, medium and high intake wheats. The enzyme increased (P < 0.01) daily gain and feed intake of the pigs fed the low-quality wheat by 50.6 and 42.8%, respectively. It may be concluded that the nutritive value of wheat for weaner pigs varies widely and appears to be related to the level of NSC and the cell wall structure of the grain. Key words: Wheat, non-starch polysaccharides, non-starch carbohydrate, xylanase, pigs

Lifetime and post-weaning determinants of performance indices of pigs

The present study was designed to determine the interrelationships between sex, weaning age, and weaning weight on subsequent growth performance. Ninety-six Large White × Landrace pigs were used in a 2 × 2 × 2 factorial experiment with the respective factors being: age at weaning (14 or 28 days), weight at weaning (heavy or light), and sex (boar or gilt). Eighty pigs were offered a high quality pelleted weaner diet ad libitum while the remaining 16 pigs (2 pigs from each treatment group) were removed from the sow and fasted for 24 h before being euthanased for determination of gut histology and enzymology. The remaining pigs were weaned into individual pens and given an ad libitum diet containing 15.5 MJ DE/kg and 0.95 g available lysine/MJ DE. On Day 6 and 13 after weaning, 2 pigs from each group at each time had their feed removed and, 24 h later, were euthanased. From 3 weeks post-weaning, the remaining pigs were group-penned with contemporary pigs and fed commercial rations until slaughter at 23 weeks of age. In the first week after weaning, the heavy pigs and those weaned at 28 days ate more feed and grew faster, and gilts ate more and grew faster than boars over the same time. Pigs that were heavier at weaning were also heavier at every subsequent age. At slaughter, heavy boars weighed more than heavy gilts (110.5 v. 103.7 kg, P = 0.027), whereas this was not the case for light boars and gilts (94.1 v. 94.4 kg, P = 0.96). Whereas there were no effects of sex or weight at weaning on P2 backfat depth, pigs weaned at 14 days had more backfat at 23 weeks than pigs weaned at 28 days (13.1 v. 10.9 mm, P = 0.009). In conclusion, these data clearly indicate that the greatest determinants of immediate post-weaning performance under the present conditions were the age and weight of the pigs at weaning. However, the key determinant of lifetime growth rate appeared to be weight of pigs at weaning or, by inference, birth. Although age at weaning had no effect on lifetime growth rate, early-weaned pigs were fatter at slaughter.

Age, sex, and weight at weaning influence organ weight and gastrointestinal development of weanling pigs

The present study was designed to determine the interrelationships between sex, weaning age, and weaning weight on aspects of physiological and gastrointestinal development in pigs. Forty-eight Large White × Landrace pigs were used in a factorial arrangement with the respective factors being: age at weaning (14 or 28 days), weight at weaning (heavy or light), sex (boar or gilt), and time after weaning (1, 7, and 14 days). At weaning, 48 pigs were removed from the sow: 16 pigs were then fasted for 24 h before euthanasia for determination of organ weights, gut histology, and enzymology, and 32 pigs were offered a high quality pelleted weaner diet ad libitum for subsequent assessment of organ weights, histology, and enzymology at 7 and 14 d after weaning. On Day 6 and 13 after weaning, 2 pigs from each group had their feed removed, and 24 h later were euthanased and similar measurements were taken. In general, the data highlighted the overall gastrointestinal underdevelopment of pigs weaned at 2 weeks of age and of pigs weaned light-for-age at either 2 or 4 weeks. Heavier body organs, gastrointestinal organs, and accessory digestive organs observed after weaning, except for the spleen, presumably reflected the increase in substrates available for cellular growth as feed intake increased after weaning, and the development of organs required to process this feed. Interestingly, the relative weights (% of liveweight) of the stomach and small intestine and, to a lesser extent, the caecum and colon, were greater in the light, 14-day-old weaned pigs, but these differences diminished with increasing time after weaning. Consistent effects due to age, weight, and sex were not observed for villous height and crypt depth, or for the specific activities of the brush-border and pancreatic enzymes measured. However, increases (P < 0.001) in the activities of maltase (P�<�0.001), glucoamylase (P < 0.001), and sucrase (P = 0.020) (all expressed per gram of mucosa), and that of trypsin (per gram of pancreas), occurred by 14 days after weaning. This most likely reflected the inducible nature of these enzymes in response to the increasing intake of substrates provided in the diet. In contrast, the specific activity of lactase declined (P = 0.012) in the first 14 days after weaning. These data suggest that pigs weaned at 2 weeks of age and pigs weaned light-for-age at either 2 or 4 weeks have a less developed gastrointestinal tract, and that its development after weaning might proceed differently to that of pigs weaned older and heavier.

Manipulation of growth in pigs through treatment of the neonate with clenbuterol and somatotropin

Neonatal pigs were treated with lipolytic agents to determine whether this would cause a long-term decrease in their ability to deposit fat, with a consequent increase in muscle growth and feed efficiency. Groups of 25 female piglets were given clenbuterol (100 microg/kg BW), porcine somatotropin (pST; 100 microg/kg BW), pST plus clenbuterol, or saline injections from 3 d to 40 d of age. Five piglets from each group were then slaughtered to determine body composition. Clenbuterol and pST both increased ADG up to weaning when given separately (24%, P < 0.05; 20%, P < 0.1 respectively) but did not reduce fat deposition. In contrast, pigs given clenbuterol plus pST showed no increase in ADG and a 41% reduction in carcass fat (P < 0.05). Clenbuterol caused a marked decrease in beta2-adrenoceptor density in porcine adipose tissue (P < 0.001) and skeletal muscle (P < 0.01). This effect was attenuated by concurrent pST treatment, which helps to explain the synergistic effect of these drugs on fat deposition. Once the drugs were withdrawn at 40 d, the anabolic effect of pST gradually disappeared, so that the live weight of pST-treated and control pigs was identical at 168 d. Clenbuterol withdrawal caused the rapid loss of extra weight gained, plus an additional 4 to 5 kg live weight that was never recovered. During the 4-wk finishing period there was an increase in feed intake in pigs that had previously undergone treatment with pST (23%, P < 0.1), with no increase in ADG, and so feed efficiency was impaired (P < 0.05). Pigs that were treated with pST plus clenbuterol showed no marked increase in feed intake during this period. Carcasses from clenbuterol-treated pigs tended to be leaner at 168 d, but there was no long-term effect of pST or the combined treatment on carcass composition. Overall, the treatment of neonatal pigs with repartitioning agents was counter-productive, due to the withdrawal effects of the beta-adrenefgic agonist and the delayed long-term effect of pST on feed intake.

Effect of dietary betaine on nutrient utilization and partitioning in the young growing feed-restricted pig

The purpose of this study was to examine the effects of dietary betaine over a range of concentrations (between 0 and 0.5%) on growth and body composition in young feed-restricted pigs. Betaine is associated with decreased lipid deposition and altered protein utilization in finishing pigs, and it has been suggested that the positive effects of betaine on growth and carcass composition may be greater in energy-restricted pigs. Thirty-two barrows (36 kg, n = 8 pigs per group) were restrictively fed one of four corn-soybean meal-skim milk based diets (18.6% crude protein, 3.23 Mcal ME/kg) and supplemented with 0, 0.125, 0.25, or 0.5% betaine. Feed allotment was adjusted weekly according to BW, such that average feed intake was approximately 1.7 kg for all groups. At 64 kg, pigs were slaughtered and visceral tissue was removed and weighed. Carcasses were chilled for 24 h to obtain carcass measurements. Subsequently, one-half of each carcass and whole visceral tissue were ground for chemical analysis. Linear regression analysis indicated that, as betaine content of the diet was elevated from 0 to 0.5%, carcass fat concentration (P = 0.06), P3 fat depth (P = 0.14) and viscera weight (P = 0.129) were decreased, whereas total carcass protein (P = 0.124), protein deposition rate (P = 0.98), and lean gain efficiency (P = 0.115) were increased. The greatest differences over control pigs were observed in pigs consuming 0.5% betaine, where carcass fat concentration and P3 fat depth were decreased by 10 and 26%, respectively. Other fat depth measurements were not different (P > 0.15) from those of control pigs. In addition, pigs consuming the highest betaine level had a 19% increase in the carcass protein:fat ratio, 23% higher carcass protein deposition rate, and a 24% increase in lean gain efficiency compared with controls. Dietary betaine had no effects (P > 0.15) on growth performance, visceral tissue chemical composition, carcass fat deposition rate, visceral fat and protein deposition rates, or serum urea and ammonia concentrations. These data suggest that betaine alters nutrient partitioning such that carcass protein deposition is enhanced at the expense of carcass fat and in part, visceral tissue.

Interactions between weaning age, weaning weight, sex, and enzyme supplementation on growth performance of pigs

Digestive capacity of early-weaned pigs may be insufficient to fully digest many ingredients currently used in weaner diets. The aim of this experiment was to determine whether an exogenous enzyme preparation with broad carbohydrase activity could benefit pigs that developmentally might be immature at weaning, especially with regard to gastrointestinal development. Eighty Large White × Landrace pigs were used in a 2 × 2 × 2 × 2 factorial experiment with the factors being: weaning age (14 or 24 days), weaning weight (heavy or light), sex (boar or gilt), and dietary Biofeed Plus CT (0 or 500 μg/g) which contained fungal xylanases, pentosanases and β-glucanases. Pigs were housed individually and given a wheat-based (550 g/kg) diet containing 15.0 MJ DE and 15.9 g lysine/kg on an ad libitum basis for 21 days. The diet also contained 50 g/kg of soybean meal and 50 g/kg of lupin (Lupinus�angustifolius) kernels. The liveweights of heavy (H) pigs weaned at 24 or 14 days and light pigs (L) weaned at 24 or 14 days were 7.9 and 5.3 and 5.2 and 3.9 kg, respectively. Pigs weaned at 14 days grew slower (157 v. 345 g/day) than those weaned at 24 days, although there was a suggestion of an interaction between age and weight at weaning (P = 0.081). Thus, H and L pigs weaned at 14 days grew at 148 and 166 g/day, whereas H and L pigs weaned at 24 days grew at 374 and 315 g/day, respectively. Although there was no main effect of enzymes on daily gain (248 v. 254 g/day, P = 0.80), feed intake (278 v. 284 g/day, P = 0.79), or feed conversion ratio (1.19 v. 1.25, P�=�0.35), there were interactions with weaning age on daily gain (P = 0.050) and feed intake (P = 0.060). Pigs weaned at 14 days grew slower (176 v. 138 g/day) and ate less (206 v. 174 g/day), whereas pigs weaned at 24 days grew faster (321 v. 369 g/day) and ate more (351 v. 394 g/day), when supplemented with enzymes. During the third week after weaning there were interactions between dietary enzymes and sex (P = 0.060) and dietary enzymes and age (P = 0.023) on daily gain. Thus, pigs weaned at 24 days and supplemented with Biofeed Plus CT grew more quickly during the third week (559 v. 460 g/day), whereas the converse was true for pigs weaned at 14 days (286 v. 334 g/day). Also, enzyme-supplemented boars grew better over this period (457 v. 371 g/day), whereas the converse was true for gilts (388 v. 423 g/day). In conclusion, these data clearly indicate that the greatest determinant of post-weaning performance under the present conditions was the age of the pigs at weaning. Dietary enzyme supplementation appeared most efficacious in boars weaned at an older age, although benefits did not become apparent until 2 weeks after weaning.

Fluid balance during and after an ironman triathlon

OBJECTIVE

To record weight changes, fluid intake and changes in serum sodium concentration in ultradistance triathletes.

DESIGN

Descriptive research.

SETTING

Ironman triathlon (3.8 km swim, 180 km cycle, 42.2 km run). Air temperature at 1200 h was 21 degrees C, (relative humidity 91%). Water temperature was 20.7 degrees C.

PARTICIPANTS

18 triathletes.

INTERVENTIONS

None.

MAIN OUTCOME MEASURES

Subjects were weighed and had blood drawn for serum sodium concentration [Na], hemoglobin, and hematocrit, pre-race, post-race, and at 0800 h on the morning following the race ("recovery"); subjects were also weighed at transitions. Fluid intake during the race was estimated by athlete recall.

RESULTS

Median weight change during the race = -2.5 kg (p < 0.0006). Subjects lost weight during recovery (median = -1.0 kg) (p < 0.03). Median hourly fluid intake = 716 ml/h (range 421-970). Fluid intakes were higher on the bike than on the run (median 889 versus 632 ml/h, p = 0.03). Median calculated fluid losses cycling were 808 ml/h and running were 1,021 ml/h. No significant difference existed between pre-race and post-race [Na] (median 140 versus 138 mmol/L) or between post-race and recovery [Na] (median 138 versus 137 mmol/L). Plasma volume increased during the race, median + 10.8% (p = 0.0005). There was an inverse relationship between change in [Na] pre-race to post-race and relative weight change (r = -0.68, p = 0.0029). Five subjects developed hyponatremia ([Na] 128-133 mmol/L).

CONCLUSIONS

Athletes lose 2.5 kg of weight during an ultradistance triathlon. most likely from sources other than fluid loss. Fluid intakes during this event are more modest than that recommended for shorter duration exercise. Plasma volume increases during the ultradistance triathlon. Subjects who developed hyponatremia had evidence of fluid overload despite modest fluid intakes.

Dietary lupins (Lupinus angustifolius and Lupinus albus) can increase digesta retention in the gastrointestinal tract of pigs

Lupins are high in crude protein, cell wall materials, and gross energy but uncertainty about the bioavailability of nutrients and adverse effects on feed intake limit their use in the pig industry. Three experiments were conducted to determine the effect of lupins on retention time in the digestive tract by determining the average time it took for ingested polyethylene beads to pass through the digestive tract of pigs fed wheat-based diets containing various lupin species and fractions. In Expt 1, pigs were restrictively fed (1.8 kg/day) diets containing either predominantly wheat or predominantly wheat plus 400 g/kg peas or L. angustifolius seeds or kernels. The retention times of diets containing 400 g/kg of L. angustifolius seeds or kernels were significantly greater than those containing wheat alone (66.4 and 64.3 v. 48.8 h, P < 0.05, s.e.d. = 7.7 h), while that for the diet containing 400 g/kg peas was intermediate (55.8 h). In Expt 2 and 3, pigs were fed 1 of 6 wheat-based diets balanced for digestible energy (DE) and amino acid composition and containing either animal protein or 350 g/kg of peas, and L. angustifolius seeds or kernels, or L. albus seeds and kernels. Pigs were restrictively fed (1.5 kg/day) for Expt 2 or fed ad libitum for Expt 3. The mean retention time of the L. albus diets was greater than the other diets in both experiments. Feed intake and daily gain were reduced in pigs fed diets containing L. albus. Despite having lower feed intakes, pigs fed diets containing L. albus had more digesta in the stomach and small intestine at slaughter than the pigs consuming the diets not containing lupins. Appropriate physical treatment or enzymatic supplementation of L. albus diets may alleviate some of the feed intake problems.

Interrelationships between dietary lysine, sex, and porcine somatotropin administration on growth performance and protein deposition in pigs between 80 and 120 kg live weight

Sixty male and 60 female crossbred pigs were allocated to an experiment to investigate the effects of porcine somatotropin (pST) administration (0 or 6 mg/d) and dietary lysine content on growth performance, tissue deposition, and carcass characteristics over the live weight range of 80 to 120 kg. Pigs receiving pST were given diets containing 6.9, 7.8, 8.8, 9.7, 10.6, or 11.5 g lysine/kg, whereas control pigs received diets containing 4.8, 5.8, 6.9, 7.8, 8.8 or 9.7 g lysine/kg. These dietary levels ranged from 0.40 to 0.70 g available lysine/MJ of DE for pST-treated pigs and from 0.28 to 0.58 g available lysine/MJ of DE for control pigs. Pigs were individually housed in pens, and there were five replicates of each treatment. All diets contained 14.5 MJ of DE/kg and were offered for ad libitum consumption to pigs between 80 and 120 kg live weight. Growth rate increased exponentially and food conversion ratio (FCR) decreased exponentially with increasing levels of lysine. In addition, there was a significant sex x pST interaction such that pST reduced the sex difference in FCR. Growth rate was faster in boars than in gilts and was increased by pST at the higher levels of dietary lysine. Similarly, FCR was lower for boars than for gilts and was decreased by pST at the higher dietary lysine levels. The optimum growth rate and FCR were defined as the lysine level at which growth rate and FCR were 95% and 105%, respectively, of the lysine plateau. The optimum growth rate and FCR were achieved at similar dietary lysine contents and were approximately 0.35 and 0.52 g available lysine/MJ of DE for control and pST-treated pigs, respectively. Protein deposition in the carcass increased exponentially with increasing dietary lysine level, was higher in boars than in gilts, and was increased by pST at the higher dietary lysine contents. Sex had no effect on dietary lysine required to maximize protein deposition. The dietary lysine contents required to ensure 95% of plateau protein deposition of 104 and 153 g/d were 0.39 and 0.55 g available lysine/MJ of DE for control and pST-treated pigs, respectively. The increase in lysine requirement with pST seems to be commensurate with the increase in protein deposition.

Treatment of underfed pigs with GH throughout the second quarter of pregnancy increases fetal growth

Circulating growth hormone (GH) concentrations increase in pregnancy and administration of GH during early-mid pregnancy increases fetal growth in well-fed pigs. To determine whether increased maternal GH could promote fetal growth when feed availability is restricted, fifteen cross-bred primiparous sows (gilts) were fed at approximately 30% of ad libitum intake, from mating onwards and were injected daily i.m. with recombinant porcine GH (pGH) at doses of 0, 13.4+/-0.3 and 25.6+/-0.5 microg/kg live weight from day 25 to day 51 of pregnancy (term approximately 115 days). Treatment with pGH increased maternal backfat loss between day 25 and day 51 of pregnancy, and increased maternal plasma IGF-I concentrations measured at day 51 of pregnancy. Fetal body weight, length and skull width at day 51 of pregnancy were increased by maternal treatment with pGH. Fetal plasma glucose concentrations were increased and maternal/fetal plasma glucose concentration gradients were decreased by maternal pGH treatment at 13.4, but not 25.6 microg/kg.day. Fetal plasma concentrations of urea were decreased by both levels of pGH treatment. Overall, fetal weight was negatively correlated with fetal plasma concentrations of urea, positively correlated with maternal plasma alpha-amino nitrogen concentrations and unrelated to glucose concentrations in either maternal or fetal plasma. This suggests that the availability of amino acids, not glucose, limits fetal growth in the first half of pregnancy in underfed gilts, and that maternal GH treatment may improve amino acid delivery to the fetus.

Leptin expression in offspring is programmed by nutrition in pregnancy

Birth weight is a determinant of blood leptin concentrations in adults. Since nutrition during pregnancy can affect birth weight, the hypothesis that feed intake during pregnancy alters leptin expression in progeny was examined. Leptin mRNA was measured in subcutaneous adipose tissue and leptin protein was measuredin blood plasma from 59 day old female pigs whose mothers were fed at the same restricted rate except that half were permitted to consume 35% more feed during the second quarter of pregnancy. Leptin mRNA abundance in adipose tissue (P=0.015) and plasma leptin concentration (P=0.01) were higher in progeny from mothers provided with more feed. Body weight at birth was negatively correlated with the abundance of leptin mRNA in subcutaneous fat at 59 days of age (P=0.01). This study shows for the first time that maternal nutrition during pregnancy programs postnatal leptin expression in offspring.

Effects of L-carnitine fed during lactation on sow and litter performance

Sows of differing parities and genetics were used at different locations to determine the effects of feeding added L-carnitine during lactation on sow and litter performance. In Exp. 1, sows (n = 50 PIC C15) were fed a lactation diet (1.0% total lysine, .9% Ca, and .8% P) with or without 50 ppm of added L-carnitine from d 108 of gestation until weaning (d 21). No differences in litter weaning weight, survivability, sow ADFI, or sow weight and last rib fat depth change were observed. Number of pigs born alive in the subsequent farrowing were not different (P>.10). In Exp. 2, parity-three and -four sows (n = 115 Large White cross) were used to determine the effect of feeding 0, 50, 100, or 200 ppm of added L-carnitine during lactation (diet containing .9% total lysine, 1.0% Ca, and .8% P) on sow and litter performance. No improvements in the number of pigs or litter weights at weaning were observed (P>.10). Sows fed added L-carnitine had increased weight loss (linear; P<.04), but no differences (P>.10) were observed in last rib fat depth change or subsequent reproductive performance. In Exp. 3, first-parity sows (n = 107 PIC C15) were fed a diet with or without 50 ppm of added L-carnitine during lactation (diet containing 1.0% total lysine). Sows fed added L-carnitine tended (P<.10) to have fewer stillborn and mummified pigs than controls (.42 vs .81 pigs). No differences were observed for litter weaning weight, survivability, or subsequent farrowing performance. Feeding 50 to 200 ppm of added L-carnitine during lactation had little effect on sow and litter performance.

Epinephrine transiently increases amino acid disappearance to lower amino acid levels in humans

BACKGROUND

Infusion of epinephrine decreases plasma amino acid concentrations. However, the mechanism by which this decrement occurs is not well characterized.

METHODS

Epinephrine was infused (40 ng/kg/min) for 2 hours into eight normal healthy adults. The essential amino acid tracers L-[1-(13)C]leucine and L-[phenyl-2H5]phenylalanine were infused before and during the epinephrine infusion and blood samples obtained to determine amino acid rates of appearance and disappearance from the time course of change in amino acid concentration and tracer enrichments.

RESULTS

Epinephrine infusion decreased plasma leucine and phenylalanine concentrations over a period of 30 to 90 minutes after the start of the epinephrine infusion. Epinephrine infusion induced an immediate decrement in tracer enrichments. These changes defined sharp increases in both rate of appearance and rate of disappearance. By 30 minutes of epinephrine infusion, the rate of amino acid appearance from proteolysis had returned to baseline, but the rate of amino acid disappearance remained elevated for 90 minutes before returning to baseline. It was the protracted increase in amino acid disappearance that was responsible for the lowering of plasma amino acid concentrations. After this acute response, rates of amino acid appearance and disappearance returned to normal whereas plasma amino acid levels remained suppressed.

CONCLUSIONS

Epinephrine transiently affects both rates of amino acid appearance and disappearance, with the net effect being increased in amino acid disappearance. However, epinephrine lowers amino acid concentrations beyond the period that it affects kinetics. These results suggest that the effect of epinephrine on amino acid metabolism is not detrimental and that epinephrine allows amino acid metabolism to proceed normally but at lower concentrations of amino acids.

The relationship between endogenous insulin-like growth factors and growth in pigs

Previous studies have reported conflicting data on gender differences in plasma IGF-I in postnatal pigs. There is also debate over the role of IGF-II in regulation of postnatal growth. We have, therefore, determined the concentrations of plasma IGF-I, IGF-II, and IGF-binding protein-3 (IGFBP-3) in boars, barrows, and gilts and related these to postnatal growth characteristics. Plasma concentrations of IGF-I were higher in boars than in gilts or barrows from 13 wk. of age, and plasma IGF-II levels were generally higher in barrows than in boars or gilts. Plasma IGFBP-3 levels were higher in boars than in gilts or barrows at most ages. Between 15 and 23 wk. of age, IGF-I and IGFBP-3, but not IGF-II, were positively associated with growth rate, voluntary feed intake, and gain:feed ratio. Plasma IGF-II, but not IGF-I or IGFBP-3, was positively associated with backfat depth during this period. These results support the hypothesis that circulating IGF-I and IGF-II are regulators of lean and adipose tissue growth, respectively.

Hyponatremia in ultradistance triathletes

PURPOSE

Hyponatremia ([plasma sodium] <135 mmol x L(-1)) is a potentially serious complication of ultraendurance sports. However, the etiology of this condition is still uncertain. This observational cohort study aimed to determine prospectively the incidence and etiology of hyponatremia in an ultradistance triathlon.

METHODS

The subjects consisted of 605 of the 660 athletes entered in the New Zealand Ironman triathlon (3.8-km swim, 180-km cycle, and 42.2-km run). Subjects were weighed before and after the race. A blood sample was drawn for measurement of plasma sodium concentration after the race.

RESULTS

Complete data on pre- and postrace weights and plasma sodium concentrations were available in 330 race finishers. Postrace plasma sodium concentrations were inversely related to changes in body weight (P = 0.0001). Women (N = 38) had significantly lower plasma sodium concentrations (133.7 vs 137.4 mmol x L(-1); P = 0.0001) than men (N = 292) and lost significantly less relative weight (-2.7 vs -4.3%; P = 0.0002). Fifty-eight of 330 race finishers (18%) were hyponatremic; of these only 18 (31%) sought medical care for the symptoms of hyponatremia (symptomatic). Eleven of the 58 hyponatremic athletes had severe hyponatremia ([plasma sodium] < 130 mmol x L(-1)); seven of these 11 severely hyponatremic athletes were symptomatic. The relative body weight change of the 11 severely hyponatremic athletes ranged from 2.4% to +5%; eight (73%) of these athletes either maintained or gained weight during the race. In contrast, relative body weight changes in the 47 athletes with mild hyponatremia ([plasma sodium] 130-134 mmol x L(1)) were more variable, ranging from -9.25% to +2.2%.

CONCLUSIONS

Hyponatremia is a common biochemical finding in ultradistance triathletes but is usually asymptomatic. Although mild hyponatremia was associated with variable body weight changes, fluid overload was the cause of most (73%) cases of severe, symptomatic hyponatremia.

Epinephrine produces a prolonged elevation in metabolic rate in humans

BACKGROUND

Epinephrine increases the metabolic rate and contributes to the hypermetabolic state in severe illness.

OBJECTIVE

We sought to determine the effect of prolonged elevation of epinephrine on resting energy expenditure (REE).

DESIGN

Thirteen healthy men were placed on a well-defined diet for 5 d. Beginning on the morning of the second diet day, the subjects were infused for 24 h with saline, then for 23 h with epinephrine (0.18 nmol x kg(-1) x min(-1)) to increase plasma epinephrine concentrations into the high physiologic range (4720 +/- 340 pmol/L). REE and the respiratory quotient (RQ) were measured by indirect calorimetry in the postabsorptive state at the same time every morning.

RESULTS

Infusion of epinephrine significantly increased heart rate and systolic blood pressure, but the response was transient (values after 23 h of epinephrine infusion were not significantly different from those on the day saline was infused). Infusion of epinephrine significantly increased REE by 12% and increased the RQ. These changes were apparent at the end of the 23-h infusion (REE: 97.5 +/- 2.3 kJ x kg(-1) x d(-1) with saline infusion and 108.9 +/- 2.3 kJ x kg(-1) x d(-1) with epinephrine infusion; RQ: 0.832 +/- 0.012 with saline infusion and 0.879 +/- 0.013 with epinephrine infusion). REE returned to baseline by 24 h after the epinephrine infusion ended, but the postabsorptive RQ remained modestly elevated. Infusion of epinephrine also produced a transient increase in urine flow and in urinary nitrogen excretion. This diuresis was compensated for by a drop in urine volume and nitrogen excretion after the epinephrine infusion was stopped.

CONCLUSIONS

Epinephrine produced a prolonged increase in REE in healthy subjects. The fuel for this increase in REE, determined by the RQ, was from increased carbohydrate oxidation, not from that of fat or protein.

Porcine somatotropin, dietary protein and energy effects on arginase and transaminase activities in pigs

Two experiments were conducted with cross-bred barrows to determine the effect of somatotropin administration on liver enzyme activities. In the first experiment, pigs growing from 26 to 55 kg body weight were given two doses of pituitary porcine somatotropin (pST; 0 and 100 micrograms per kg body weight) and three levels of dietary energy (60, 80 and 100% of free choice intake). In the second experiment, pigs growing from 30 to 60 kg body weight were given two doses of recombinant porcine somatotropin (rpST; 0 and 100 micrograms per kg body weight) and five levels of dietary crude protein (110, 150, 190, 230 and 270 g crude protein/kg diet). Liver arginase (ARG, EC 3.5.3.1) and aspartate aminotransferase (AAT, EC 2.6.1.1) activities were then determined in organ samples taken at slaughter time. Dietary energy did not change liver ARG. Activities of both ARG and AAT increased as dietary crude protein increased. Both pST and rpST decreased ARG, AAT and serum utrea nitrogen. There was a lack of interaction between rpST therapy and dietary protein on either ARG or AAT activities, suggesting that set nutritional states are not required for expression of pST effects.

Interrelationships between dietary ractopamine,energy intake, and sex in pigs

A major constraint to protein deposition in the pig is energy intake. Ractopamine (RAC) isa b-agonist which has been shown to increase protein deposition under both ad libitum and restrictive feeding regimes. To assess the interactions between energy intake, sex, and dietary RAC, 104 crossbred pigs (52 boars and 52 gilts) were used in a slaughter-balance experiment conducted over the growth phase of 60-90 kg liveweight. To obtain initial body composition, 4 pigs of each sex were slaughtered at 60 kg. The remaining 96 pigs were allocated to a 2 6 2 factorial experiment. The respective factors were sex (boar or gilt), dietary digestible energy (DE) intake (21·2, 24·7, 28·2, 32·7, 36·7MJ DE/day and ad libitum), and dietary RAC (0 and 20 mg/kg of ractopamine.HCl). Average daily gain increased with DE intake and was faster for boars than gilts. Dietary RAC increased averagedaily gain in both boars and gilts independent of DE intake. Neither dietary RAC nor sex had any effect on ad libitum feed intakes while effects on feed : gain ratio reciprocated growth rates. Protein deposition increased with DE intake and was higher in boars than in gilts. Although protein deposition was increased by dietary RAC in both boars and gilts across the range of DE intakes investigated,ad libitum feed intakes were necessary to maximise protein deposition. Fat deposition increased with DE intake and was greater in gilts than in boars. Whereas dietary RAC had no effect on the rateof fat deposition or backfat depths, the fat content of the empty body was lower due to increased protein deposition and lower fat : protein ratio. Dietary RAC improves growth performance and carcass composition in both boars and gilts independent of DE intake. However, ad libitum feed intakes maybe necessary if responses are to be maximised.

The effect of dietary lysine and valine fed during lactation on sow and litter performance

Sows (98 first parity and 104 second parity) were used to determine the effects of dietary lysine and valine on lactation performance. Treatments were arranged in a 2 x 3 factorial with two levels of lysine (.80 or 1.20%) and three valine:lysine ratios (80, 100, or 120% of lysine). For all sows, increasing dietary lysine increased litter weaning weight (P < .001) and litter weight gain (P < .002) and reduced sow weight loss (P < .001). Litter weight gain tended (P = .22) to increase with increasing dietary valine, but the increase was not significant. Data were separated into two groups: sows that weaned 10 or more pigs and sows that weaned fewer than 10 pigs. For sows that weaned 10 or more pigs, litter weaning weight (P < .001) and litter weight gain (P < .001) increased and sow BW loss decreased (P < .001) when dietary lysine increased from .80 to 1.20%. For sows that weaned fewer than 10 pigs, increasing lysine had no effect (P < .77) on litter growth rate. For sows weaning 10 or more pigs, litter weaning weights (linear, P < .04; quadratic, P < .06) and litter weight gain increased (linear, P < .04; quadratic, P < .02) as dietary valine increased. For sows that weaned fewer than 10 pigs, maximum litter weight gain was observed at a valine:lysine ratio of 100% (quadratic, P < .13). These results demonstrate the need to increase dietary lysine and valine as litter weaning weights increase. High-producing sows that wean 10 or more pigs require increased dietary lysine and valine to maximize litter growth rate and minimize sow weight loss compared with sows weaning fewer than 10 pigs. The independent increases in litter weaning weights from adding lysine and valine suggest separate modes of action for these amino acids in high-producing sows.

Hyponatremia and weight changes in an ultradistance triathlon

OBJECTIVE

To describe the weight changes and the incidence of hyponatremia during an ultradistance triathlon in the athletes who attend medical care after the race.

DESIGN

Descriptive research.

SETTING

The 1996 New Zealand Ironman Triathlon in which each athlete swam 3.8 km, cycled 180 km, and ran 42 km.

PARTICIPANTS

Ninety-five athletes attending for medical care after the race were studied. One hundred sixty-nine athletes who did not attend for medical care were also weighed before and after the race.

MAIN OUTCOME MEASURES

Weights were measured at race registration and on finishing the race. Whole-blood sodium concentration was measured in those athletes with clinical evidence of fluid or electrolyte disturbances.

RESULTS

Weights were significantly decreased at the end of the race in the athletes seeking medical care (n = 48, mean % delta wt = -2.5%, p < 0.001) and also in the athletes who did not seek medical care (n = 169, mean % delta wt = -2.9%, p < 0.001). Seventeen percent of race starters sought medical attention. Dehydration accounted for 26% of primary diagnoses and hyponatremia for 9%. One athlete with hyponatremia (Na 130 mEq/L) is described who drank 16 L over the course of the race, with a weight gain of 2.5 kg. This is consistent with the hypothesis of fluid overload as the cause of his hyponatremia. Hyponatremia accounted for four of five admissions to the hospital after the race. An inverse relationship between postrace sodium concentrations and percentage change in body weight was observed (r = -0.63).

CONCLUSIONS

Hyponatremia is an important risk to the health of athletes competing in an ultradistance triathlon, with fluid overload the likely aetiology.

Performance and body composition of finishing gilts (45 to 85 kilograms) as affected by energy intake and nutrition in earlier life: II. Protein and lipid accretion in body components

Forty-eight commercial hybrid gilts were used to investigate the response relationships between energy intake and deposition of protein and lipid in body components of finishing pigs (45 to 85 kg) as affected by previous nutrition. Two groups of 24 gilts received a single diet either at 2.2 (restricted pigs) or 3.7 (control pigs) times maintenance (M) from 20 to 45 kg. From 45 to 85 kg, pigs from each of these two groups were fed the same diet at one of six intake levels (1.7, 2.2, 2.7, 3.2, or 3.7 x M, or adlibitum). At 85 kg, the gilts were dissected and analyzed. Protein content in the whole body decreased curvilinearly from 190 to 166 g/kg (P < .001) and lipid content increased from 116 to 210 g/kg (P < .001) with increasing energy intake. The mean content of protein was 6 g/kg higher and of lipid 29 g/kg lower (both P < .001) in previously restricted gilts. Protein (PD) and lipid deposition (LD) in the whole body, organs, lean, and fat tissue increased linearly (P < .001) with increasing energy intake. In the whole body, PD increased from 83 to 187 g/d and LD from 46 to 392 g/d. The respective response relationships in grams/day were PD = 21.8 + 3.78 x DEI and LD = -193 + 13.7 x DEI(DEI is digestible energy intake, MJ/d). The LD:PD ratio increased curvilinearly from .6 to 2.2. Previous nutrition had only small effects on PD and LD. Only PD in the organs was on average 7 g/d higher (P < .001) in previously restricted gilts. Thus, the higher protein content and the lower lipid content in previously restricted gilts was not primarily the results of compensation but was almost entirely present at the end of the restriction phase at 45 kg.

Somatotropin enhances the rate of amino acid deposition but has minimal impact on amino acid balance in growing pigs

This experiment was conducted to establish the influence of porcine somatotropin on tissue distribution and deposition rates of amino acids in growing pigs. Barrows were treated daily with buffer or porcine somatotropin (100 micrograms/kg body wt) when they weighed between 30 and 64 kg (eight pigs/group). Pigs were restrictively fed so that the average food intake was 1.86 kg/d. The corn-soybean meal-skim milk-based diet contained 18% crude protein and 1.2% lysine, and was designed to meet muscle amino acid ratio profile with respect to lysine as the first limiting amino acid for growth. Tissue levels of eighteen amino acids were determined on lyophilized samples that were appropriately hydrolyzed and analyzed by HPLC. The concentrations (mg/g dry wt) of all amino acids were greater in carcass, skin, head and empty body of porcine somatotropin-treated pigs; amino acid concentration in viscera was not influenced by porcine somatotropin. However, when the concentration of each amino acid was expressed on a per unit protein basis, the amino acid profiles of control and porcine somatotropin-treated pigs were quite similar. The average deposition rate of each amino acid was increased approximately 67% by porcine somatotropin. When the deposition of each amino acid was calculated in relation to lysine, however, the pattern of amino acid utilization for growth was similar for control and porcine somatotropin-treated pigs; exceptions were arginine, glycine and tryptophan. The ratio of indispensable to dispensable amino acids that were deposited was also similar for control and porcine somatotropin-treated pigs. These data indicate that the synthesis rate of individual proteins can be influenced by porcine somatotropin, but the balance of amino acids remains largely unaffected, suggesting that the changes in protein and amino acid metabolism elicited by porcine somatotropin are consistent with normal growth processes.

Protein and lipid accretion in body components of growing gilts (20 to 45 kilograms) as affected by energy intake

Twenty-eight commercial hybrid gilts with a high genetic capacity for lean gain were used to determine the relationships between energy intake and tissue deposition and body composition between 20 and 45 kg BW. Four pigs were killed at 20 kg to determine body composition at the beginning of the experiment. The other 24 gilts received one of six intake levels (1.7, 2.2, 2.7, 3.2, and 3.7 times maintenance [M], and ad libitum) ranging from 11.3 to 27.2 MJ of DE/d. At 45 kg BW, the gilts were killed and dissected into carcass and organ fractions. Carcasses of pigs at 2.2 and 3.7 x M were dissected into lean and other carcass parts. Daily gain increased linearly (P < .001) from 371 to 1,075 g/d. Gain/feed increased (P < .01) from 500 to 600 g/kg. Deposition rates of protein and lipid increased linearly (P < .001) from 75 to 172 g/d and from 28 to 193 g/d, respectively. The ratio between lipid and protein deposition increased (P < .001) from .3 to 1.1. The relative organ mass increased (P < .001) with increasing energy intake, whereas the body lean percentage decreased (P < .01) from 53.9% at 2.2 x M to 47.4% at 3.7 x M. In the carcass and organs, protein content decreased (P < .01) and lipid content increased (P < .001) with increasing energy intake. Protein deposition increased with 5.77 g/MJ increase in DE intake, of which only approximately 40% was deposited in the lean tissue.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of dietary energy intake and exogenous porcine growth hormone administration on circulating porcine growth hormone concentration and response to human growth hormone-releasing factor administration in growing swine

In a 2 x 2 treatment array (n = 4 pigs/treatment), the effects of feed intake (ad libitum vs. restricted to 60% ad libitum) and the daily administration of excipient buffer or porcine pituitary-derived growth hormone (GH) at a dose of 100 micrograms/kg body weight per day on serum GH profile and human growth hormone-releasing factor (hGRF) response were examined in barrows weighing 55 kg. Feed intake treatment was implemented from 25 to 55 kg live weight. Buffer or GH treatment was implemented for 10 d before sampling. After GH treatment, the integrated serum GH concentration area was 25% greater in barrows fed restrictively. Data are consistent with the suggestion that GH dose to improve the efficiency of lean tissue deposition be adjusted according to feeding regimen. The serum GH response to hGRF was also altered by level of feed intake. The ad libitum feeding of buffer-treated animals resulted in a monophasic serum GH response to hGRF, whereas barrows fed restrictively had a biphasic response to hGRF. Together, these data suggest that feed intake pattern alters GH secretion and as such could influence the practical implementation of somatotropin as a metabolism modifier in swine.

Effect of cortisol on energy expenditure and amino acid metabolism in humans

Hydrocortisone was infused overnight into nine normal healthy adults on three occasions at 0, 80, and 200 micrograms.kg-1.h-1, producing plasma cortisol concentrations of 10.6 +/- 1.2, 34.0 +/- 2.0, and 64.9 +/- 4.3 micrograms/dl, respectively. L-[1-13C]leucine, L-[phenyl-2H5]phenylalanine, and L-[2-15N]glutamine were infused during the last 7 h of hypercortisolemia to measure amino acid kinetics. During the last 3.5 h, somatostatin, glucagon, and insulin were infused to reduce the cortisol-induced elevation in plasma insulin to basal. Hypercortisolemia increased plasma glucose, free fatty acid (FFA), and insulin concentrations. Institution of the somatostatin clamp returned insulin to basal but increased glucose and FFA. Acute hypercortisolemia increased protein breakdown 5-20%, as measured by increases in leucine and phenylalanine appearance rates. Normalizing insulin during hypercortisolemia did not alter phenylalanine flux but enhanced leucine appearance rate, the latter result indicating that insulin was affecting leucine metabolism during hypercortisolemia. The fraction of the leucine flux that was oxidized was not significantly increased with hypercortisolemia, but disposal by the nonoxidative route of leucine uptake for protein synthesis was increased. Hypercortisolemia increased cycling of amino acids by increasing protein breakdown and synthesis, but the increase in this process could have increased resting energy expenditure (REE) only 1-2%. Hypercortisolemia increased glutamine flux in a dose-dependent fashion through an increase in de novo synthesis, which presumably reflects increased release from skeletal muscle. Hypercortisolemia increased REE 9-15% at the 80 and 200 micrograms.kg-1.h-1 infusion rates. Respiratory quotient did not rise with cortisol infusion but tended to decrease, suggesting that the increase in REE was fueled by increased oxidation of fat. These data demonstrate that hypercortisolemia increases metabolic rate and may be in part responsible for the hypermetabolic state in injury.

Digestible lysine requirement of gilts with high genetic potential for lean gain, in relation to the level of energy intake

One hundred gilts were used to determine the optimal ratio between ileal digestible lysine and digestible energy in the diet, and the effect of energy intake level on this optimal ratio for gilts with high genetic potential for lean gain, between 20 and 45 kg BW. In a 2 x 15 factorial arrangement the pigs were fed either 2.5 or 3.0 times the energy requirements for maintenance. Average daily lysine intake in the treatment period ranged from 6.4 to 18.2 g/d in 15 graduated steps. The first 12 increments were .74 g/d, and the last two increments were 1.48 g/d. Average daily gain (ADG), gain/feed, and protein deposition increased curvilinearly (P < .01) with increasing lysine intake. The ADG was maximized at 606 and 768 g/d, gain/feed was maximized at .564 and .604 kg/kg, and protein deposition was maximized at 108 and 128 g/d at the low- and high-energy levels, respectively. The ratio between lipid and protein deposition decreased curvilinearly with increasing lysine intake (P < .01) and reached a minimum of .53 and .75 at the low- and high-energy levels, respectively. The lysine requirements (ileal digestible lysine/DE, grams/megaJoule), determined with a linear-plateau model, were .57 for ADG and gain/feed, and .62 for protein deposition. These estimated requirements were similar for the two energy levels. Consequently, approximately .60 g of ileal digestible lysine/MJ of DE was required to optimize performance in gilts with high genetic potential for lean gain, irrespective of the feed intake level. In addition, a factorial model to estimate the lysine/energy requirements is proposed.

Interrelationships between sex and ractopamine on protein and lipid deposition in rapidly growing pigs

Sixty pigs were used to investigate the effects of two levels of dietary ractopamine (RAC; 0 and 20 mg/kg) and three sex types (SEX; boars, gilts, and barrows) on performance over the live weight range 60 to 90 kg. Pigs were housed in individual pens and allowed ad libitum access to a diet containing 3.466 Mcal of DE and 10.7 g of lysine/kg. Control boars exhibited faster and more efficient growth and deposited more protein and less fat than gilts or barrows. The RAC increased ADG by 17 and 21% in gilts and barrows but not in boars. Feed intake was not altered by dietary RAC. Dietary RAC increased the rate of protein deposition by 15, 42, and 41% in boars, gilts, and barrows, respectively. Nevertheless, the daily rate of protein deposition was greatest in RAC-treated boars. The RAC tended to reduce the daily rate of fat deposition by 21% in boars but not in gilts or barrows. Carcass protein content increased by 5% and fat content decreased by 8% in response to RAC. These improvements in carcass composition occurred without compromising meat quality. Results show that RAC is a potent stimulator of protein deposition in finishing pigs. However, increased protein deposition is not necessarily at the expense of fat deposition.

Interrelationships between dietary protein and ractopamine on protein and lipid deposition in finishing gilts

Fifty-two gilts were used to investigate the effects of two levels of dietary ractopamine (RAC; 0 and 20 mg/kg) and six levels of dietary protein content (DPC; 8.5, 11.2, 14.0, 16.7, 19.5, and 22.2%) on performance over the live weight range from 60 to 90 kg. Pigs were housed in individual pens and restrictively fed their treatment diets according to a sliding scale related to live weight (average intake approximately 7.0 Mcal of DE/d). The ADG increased with increasing DPC for both control and RAC-treated gilts. The RAC further increased ADG at DPC > 14%; improvements were most apparent during the first 3 to 4 wk. There was a significant linear interaction between DPC and RAC for average daily carcass gain. Although carcass gain was not affected by RAC at the three lowest DPC, it was significantly increased for the three highest DPC. Feed to gain decreased with increasing DPC in a similar manner for both control and RAC-treated gilts. The relationship between empty body protein deposition and DPC could be described by a quadratic and rectilinear model. Regardless of the model employed, protein deposition increased with DPC at the same rate for both the control and RAC-treated gilts over at least the two lowest levels of DPC (< 11.2%). At higher DPC maximal rates of protein deposition were at least 21% greater in RAC-treated gilts; these rates were achieved at 3% higher DPC for RAC-treated gilts. Fat deposition decreased with increasing DPC but was unchanged by dietary RAC. Because the biological efficiency of protein use was unchanged, RAC-treated gilts have greater dietary protein requirements than controls do.

Splanchnic bed utilization of glutamine and glutamic acid in humans

To study the fate of enterally delivered nonessential amino acids, glutamine and glutamate, 14 healthy adults were infused in the postabsorptive state with [2-15N]glutamine and [15N]glutamate for 7 h by intravenous (iv) and nasogastric (ng) tube routes. The amount of enterally delivered tracer that was sequestered by the splanchnic bed on the first pass was 54 +/- 4 and 88 +/- 2% for the [2-15N]glutamine and [15N]glutamate tracers, respectively. Only 46 and 12% of the ng glutamine and glutamate tracers entered systemic blood, respectively. The relative amount of 15N transferred from glutamate to glutamine, the transaminating amino acids leucine, isoleucine, valine, and alanine, and to proline was significantly higher when the [15N]glutamate was infused by the ng vs. iv route. The same was also true for [2-15N]glutamine, which presumably transferred 15N after it was converted to glutamate. Thus we conclude that the splanchnic bed sequesters over one-half of the glutamine and almost all of the glutamate delivered to it in the postabsorptive state. There is production of transaminating amino acids in the splanchnic bed, and the splanchnic bed produces simultaneously both glutamine from glutamate and glutamate from glutamine.

Effects of ractopamine in pig muscles: histology, calpains and β-adrenergic receptors

Ractopamine is a G-adrenergic agonist which stimulates growth in pigs, but this effect appears to decline during prolonged treatment. This study was conducted to examine possible mechanisms for the growth-enhancing activity of ractopamine, and its attenuation. Finishing gilts (47.0 kg body weight) were allocated to one of five experimental groups: CON, control diet for 6 weeks; RAC, ractopamine (20 mg/kg feed) for 6 weeks; C/R, CON for 3 weeks and RAC for 3 weeks; R/C, RAC for 3 weeks and CON for 3 weeks; and ALT, CON for weeks 1, 3 and 5, and RAC in weeks 2, 4 and 6. All pigs were fed 2.25 kg/day of a commercial grower ration (13 MJ DE/kg, 16% crude protein, 0.6 g available lysine/MJ DE). Samples of the m. longissirnus dorsi were taken at slaughter and analysed for fibre histology, calpain activities and G -adrenergic receptor populations. Ractopamine had no effect on muscle fibre proportions, but Type II fibres were smaller in pigs treated for the first 3 weeks only (R/C; 2477 8m2, P < 0.05), and tended to be larger in pigs treated for the second 3 weeks only (C/R; 3670 8m2, P < 0.10), as compared to controls (3086 8m2). Giant fibres were also larger in C/R pigs as compared to controls (9027 v. 6917 8m2, P < 0.05). Type I fibres were unaffected by any of the treatments. Calpain II and calpastatin activities were unaffected by any treatment, but calpain I activities were reduced in C/R pigs as compared to controls (0.331 v. 0.504 U/g, P < 0.05), indicating that reduced capacity for protein degradation might partially account for the hypertrophic effect of ractopamine. Pigs treated with ractopamine for 3 weeks before slaughter had reduced numbers of G-adrenoceptors in muscle than controls (2.34 v. 3.17 fmol/mg protein, P < 0.05), which may be responsible for the observed attenuation in growth enhancement over time.

Temporal changes in growth enhancement by ractopamine in pigs: performance aspects

Ractopamine is a phenethanolamine with G-adrenergic agonist activity which stimulates growth in pigs. In order to test whether the growth-enhancing properties of ractopamine change over time, 40 Large White crossbred gilts (47.0 kg liveweight) were assigned to five treatment groups: CON, control diet for 6 weeks; RAC, ractopamine(20 mg/kg feed) for 6 weeks; C/R, CON for 3 weeks, then RAC for 3 weeks; R/C, RAC for 3 weeks, then CON for 3 weeks; ALT, CON for weeks 1, 3, and 5, and RAC in weeks 2, 4 and 6. The control diet was a commercial wheat and soy-based grower ration (13 MJ DE/kg, 16% crude protein, 0.9% lysine, 0.6 g available lysine/MJ DE); all pigs were fed 2.25 kg/day. Weekly measurements included body weight and P2 backfat (by ultrasound). Due to uncertainty about the data from the final week, results for weeks 1 to 3 and 3 to 5 are presented. Average daily gain (ADG) was increased by RAC (+16%) during the first 3 weeks, with no further improvement thereafter. C/R produced higher ADG (+21%) during weeks 3 to 5 compared with controls, and ALT tended to do the same (+12%, P < 0.10). Over the 5 week period, total weight gain was increased (P > 0.05) by RAC (+18%) and ALT (+15%), and tended to increase with C/R (+12%, P < 0.10) with no significant effect of R/C (+l0%, P > 0.05). There were no differences among groups in P2 backfat during the feeding period ( P > 0.05). With the exception of dressing percentage, which was increased by RAC, C/R and ALT ( P < 0.05), carcass and meat quality characteristics (carcass weight, P2 backfat, loin eye area, pH, colour, drip loss and protein solubilities) were unaffected by any of the treatments (P > 0.05). In conclusion, ractopamine stimulated growth in finishing pigs on restricted intakes; this effect diminished over time, and was more pronounced in older and heavier pigs. In addition, meat quality characteristics were unaffected.

Splanchnic bed utilization of leucine and phenylalanine in humans

To study the fate of enterally delivered essential amino acids, leucine and phenylalanine, 14 healthy adults were infused in the postabsorptive state with [1-13C]leucine, [5,5,5-2H3]leucine, and [phenyl-2H5]phenylalanine for 7 h in a crossover design by intravenous and nasogastric tube routes. The amount of enterally delivered tracer that was sequestered by the splanchnic bed on the first pass was 21 +/- 1, 17 +/- 3, and 29 +/- 2 for the [13C]leucine, [2H]leucine, and [2H]phenylalanine tracers, respectively. Less than 2% of the nasogastric [1-13C]leucine tracer was oxidized on the first pass. We estimate that 40% of the nasogastric leucine tracer that was sequestered on the first pass was converted to alpha-ketoisocaproate and released, and 50% was incorporated into newly synthesized proteins. Assuming that less phenylalanine is incorporated into protein than leucine because of the lower abundance of phenylalanine in protein compared with leucine, we estimate that 80% of the extracted nasogastric phenylalanine tracer was converted to tyrosine. The study design also indicated a significant effect of duration of tracer infusion on the results, presumably due to recycling of tracer from rapidly turning over protein.

Growth hormone increases whole-body protein turnover in growing pigs

Ten pigs with an average initial live weight of 65 kg were used to investigate the effects of daily exogenous porcine pituitary growth hormone (pGH; .1 mg.kg-1.d-1) for a 13-d period on N retention and whole-body protein turnover. Feed intake was restricted to both the control (treated with excipient) and pGH-treated groups to ensure that animals in each group consumed equal amounts. Whole-body protein turnover was estimated from the excretion of 15N in urinary urea and ammonia after a single oral dose of [15N]glycine. Nitrogen balance and whole-body N flux were increased by 35 to 40% with pGH treatment (P less than .001). Protein synthesis and breakdown were increased by 56 and 59% (P less than .001), respectively, in pGH-treated pigs relative to controls. These higher rates of protein turnover seemed to lower slightly the efficiency of the metabolic process for protein deposition. However, the absolute increment in protein synthesis rate was greater than that for breakdown, leading to the increased net N retention. Thus, pGH treatment improved the utilization of dietary amino acids for protein deposition.

The effect of dietary protein intake on glutamine and glutamate nitrogen metabolism in humans

The response of glutamine and glutamate kinetics were studied in five healthy young adult men on diets containing deficient (0.1), adequate (0.8), or surfeit (2.2 g.kg-1.d-1) amounts of protein. Glutamate, glutamine, and phenylalanine kinetics were measured in the postabsorptive state at the end of each diet period. Urinary urea and ammonia excretion correlated with protein intake (the sum of the two was 2.1 +/- 0.2, 5.7 +/- 0.3, and 11.9 +/- 1.2 g N g.kg-1.d-1 for the respective 0.1, 0.8, and 2.2 g.kg-1.d-1 protein intakes). Glutamate and glutamine concentrations varied inversely with protein intake. Phenylalanine concentrations and phenylalanine flux did not change significantly with the changing protein intake. Both glutamate and glutamine fluxes varied inversely with protein intake (glutamate flux was 177 +/- 15, 120 +/- 10, and 125 +/- 11 mumol.kg-1.h-1 and glutamine flux was 373 +/- 29, 343 +/- 26, and 318 +/- 15 mumol.kg-1.h-1 at the respective 0.1, 0.8, and 2.2 g.kg-1.d-1 protein intakes). These changes in glutamine or glutamate flux in response to alterations in dietary protein intake were attributable to changes in de novo production.

Interrelationships between exogenous porcine somatotropin (PST) administration and dietary protein and energy intake on protein deposition capacity and energy metabolism of pigs

Exogenous porcine somatotropin (PST) administration stimulates protein deposition and inhibits lipogenesis, resulting in dose-related improvements in growth performance and reduction of carcass fat content. However, the associated impacts of this technology on dietary nutrient requirements and energy partitioning between maintenance, protein, and fat remain unclear. Studies with pigs between 25 and 60 kg body weight indicate that, because of unknown improvements in amino acid utilization and(or) in the energy available for protein synthesis, only marginal increases in dietary protein percentage are required to support 20 to 25% improvements in protein deposition induced by PST administration. In contrast, an increased dietary protein concentration is required to support maximal protein deposition in pigs 60 to 100 kg. Exogenous PST administration increased the maintenance energy requirement and altered the relationship between energy intake and protein deposition, although the magnitude of these changes and the consequent effects on expression of dietary protein (amino acid) requirements was influenced by gender. Albeit limited, information suggests that PST alters nutrient demand at the tissue level. Information of this type will form the basis for rational decisions concerning the method for expression of dietary nutrient requirements (% vs g/d) for PST-treated pigs. Further quantitative information is required on the effects of PST dosage on the relationship of protein deposition to energy intake and on any underlying changes in amino acid utilization and metabolism.

Developmental changes in growth hormone, insulin-like growth factors (IGF-I and IGF-II) and IGF-binding proteins in plasma of young growing pigs

The relationship between plasma concentrations of normally secreted GH and insulin-like growth factor-I (IGF-I) was investigated in pigs after weaning. Frequent blood sampling for between 12 and 24 h showed that plasma GH was pulsatile in pigs of 10, 20 and 35 kg liveweight. Pulses were brief in duration, low in amplitude and variable in frequency. Basal and average daily plasma concentrations of GH changed significantly with development, increasing by about 50% between 10 and 20 kg liveweight. Concentrations of IGF-I in plasma showed little or no evidence of diurnal periodicity and were not increased by GH pulses. Average daily concentrations of both IGF-I and IGF-II in plasma progressively increased between 10 and 35 kg liveweight, as did the total desaturated IGF-binding protein (IGFBP) activity of plasma. A strong positive correlation was observed between the total concentration of IGFs (IGF-I plus IGF-II) in the circulation and plasma IGFBP activity. The developmental rise in IGFBP activity of plasma was associated with increased labelling with 125I-labelled human IGF-II in ligand blots of binding proteins of apparent molecular masses greater than 200, 50, 43 and 29 kDa. One class of binding proteins of 34.5 kDa decreased with development. This study of young growing pigs shows that normally secreted endogenous GH exerts no significant immediate control over plasma IGF-I concentrations, and that plasma levels of IGF-I and IGF-II increase with maturation in this species.(ABSTRACT TRUNCATED AT 250 WORDS)