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These experiments were conducted to determine if ractopamine hydrochloride (RAC) could improve nutrient utilization and decrease water use in hog operations. The growth experiment utilized a comparative slaughter technique that consisted of 120 barrows (95 ± 3 kg BW) including 12 assigned to an initial slaughter group; the remaining pigs were slaughtered at 108- or 120-kg. Growth performance and nutrient retention were determined. The 15 d metabolism experiment consisted of 54 pigs (95 ± 3 kg BW). Growth performance, feed, and water intake and urine and fecal output were measured. The metabolism experiment used 9 dietary treatments arranged as a 3 x 3 factorial: 3 levels of RAC (0, 5 and 10 ppm) and 3 standardized ileal digestible lysine: digestible energy (DE) ratios (1.75, 2.25 and 2.75 g/Mcal DE). The growth study was designed as a 3 x 3 x 2 factorial to include slaughter weight as an additional factor.<p> In the growth experiment, RAC had no effect ADG, ADFI, or G:F (P > 0.10). With increased Lys levels G:F improved (P < 0.05), but not ADG or ADFI (P > 0.10). Protein deposition rates numerically increased (P = 0.11), water deposition rates tended to increase (P < 0.10), whereas lipid deposition tended to decrease with RAC inclusion (P < 0.10). In the metabolism experiment, with greater levels of RAC and Lys the pigs had improved ADG (P < 0.05) and G:F (P < 0.001). Water intake (P < 0.05.) and urine output (P < 0.05) decreased with greater RAC inclusions. Lys inclusion did not alter water balance (P > 0.10). Urinary N excretion (P < 0.05), total N excretion (P < 0.05), and the urine N:fecal N ratio (P < 0.001) decreased with addition of dietary RAC; however fecal N (P < 0.05) increased with dietary RAC inclusion. Retention of N improved with addition of RAC to the diet (P < 0.05). With greater dietary Lys inclusion fecal N was reduced (P < 0.001). The pigs fed the 2.25 g/Mcal Lys tended to have the lowest urinary N and total N excretion and highest N retention (P < 0.10) and greatest urinary N:fecal N ratio (P < 0.05). A RAC x Lys interaction was observed for N digestibility, excretion, and retention and fecal and urinary N (P < 0.05). By improving N and water utilization in finishing pigs, RAC containing diets supplemented with sufficient Lys can reduce the environmental footprint of pork production.

These experiments were conducted to determine if ractopamine hydrochloride (RAC) could improve nutrient utilization and decrease water use in hog operations. The growth experiment utilized a comparative slaughter technique that consisted of 120 barrows (95 ± 3 kg BW) including 12 assigned to an initial slaughter group; the remaining pigs were slaughtered at 108- or 120-kg. Growth performance and nutrient retention were determined. The 15 d metabolism experiment consisted of 54 pigs (95 ± 3 kg BW). Growth performance, feed, and water intake and urine and fecal output were measured. The metabolism experiment used 9 dietary treatments arranged as a 3 x 3 factorial: 3 levels of RAC (0, 5 and 10 ppm) and 3 standardized ileal digestible lysine: digestible energy (DE) ratios (1.75, 2.25 and 2.75 g/Mcal DE). The growth study was designed as a 3 x 3 x 2 factorial to include slaughter weight as an additional factor.<p> In the growth experiment, RAC had no effect ADG, ADFI, or G:F (P > 0.10). With increased Lys levels G:F improved (P < 0.05), but not ADG or ADFI (P > 0.10). Protein deposition rates numerically increased (P = 0.11), water deposition rates tended to increase (P < 0.10), whereas lipid deposition tended to decrease with RAC inclusion (P < 0.10). In the metabolism experiment, with greater levels of RAC and Lys the pigs had improved ADG (P < 0.05) and G:F (P < 0.001). Water intake (P < 0.05.) and urine output (P < 0.05) decreased with greater RAC inclusions. Lys inclusion did not alter water balance (P > 0.10). Urinary N excretion (P < 0.05), total N excretion (P < 0.05), and the urine N:fecal N ratio (P < 0.001) decreased with addition of dietary RAC; however fecal N (P < 0.05) increased with dietary RAC inclusion. Retention of N improved with addition of RAC to the diet (P < 0.05). With greater dietary Lys inclusion fecal N was reduced (P < 0.001). The pigs fed the 2.25 g/Mcal Lys tended to have the lowest urinary N and total N excretion and highest N retention (P < 0.10) and greatest urinary N:fecal N ratio (P < 0.05). A RAC x Lys interaction was observed for N digestibility, excretion, and retention and fecal and urinary N (P < 0.05). By improving N and water utilization in finishing pigs, RAC containing diets supplemented with sufficient Lys can reduce the environmental footprint of pork production.

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For economical and ecological reasons, efficiency and profitability ofswine production relies heavily on the way pigs utilize key nutrients such as P,which is considered a potential pollutant of water ecosystems. Although cerealgrains and oilseed meals contain enough P to fulfill the biological needs of pigs,most of this P is tightly bound as phytate. As pigs do not have enough phytase(PHY) to cleave P from phytate, it is excreted in the feces. To prevent adeficiency, diets have traditionally been supplemented with highly availableinorganic sources of P. Today, an environmentally-friendly alternative is tosupplement diets with PHY.Growth promoting antibiotics are also used to enhance the utilization ofdietary components such as energy and N. It has been suggested that theantibiotic virginiamycin (VIR) could also improve phytate-P utilization by pigs.Eight experiments evaluated the effects of VIR and/or PHY amendmentson digestibility, retention, excretion, growth, bone characteristics, meat traits, andileal microflora populations of growing pigs fed corn–soybean meal (SBM) diets(seven experiments) or corn-SBM-rice bran diets (one experiment). Additionally,a comparison between two digestibility procedures was conducted for two of theexperiments.On average, VIR improved P digestibility and total P excretion by 5.0%,and P retention as a percent of absorption by 1.0%. Phytase amendmentsimproved P digestibility between 14 and 27%, and P retention (as a % ofabsorption) between 0.7 and 2.5%. In the growth trial, VIR supplementation wasassociated with numerical differences favoring bone mineralization and ilealphytate-utilizing bacteria populations. These observations demonstrate additionalresearch is warranted with this antibiotic under conditions of higher stress andbacterial load in the environment.According to the comparisons between digestibility methods, a single grabfecal collection was not reliable. Further, a cumulative grab collection for fivedays was not as good an option as the total collection method.It is concluded that VIR does improve P utilization in pigs fed corn-SBMdiets not supplemented with inorganic P. Similar effects, but of greatermagnitude, were confirmed for PHY-amended diets with either normal or highlevels of phytate P.

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In adults, serum and salivary cortisol increase during aerobic exercise. There is little data on serum and no data on salivary cortisol responses during aerobic exercise in children. The purpose of this study was to examine serum and salivary cortisol during and after aerobic exercise. Ten male children with a mean age of 10.6 ± 0.6 years were subjects in this study. Each child came to the laboratory on three occasions. The first visit was to familiarize the child with the procedures. On the second visit, each child performed a maximal exercise test on a cycle ergometer (mean VO2. 49.5 ± 3.6 ml•kg''-min-') . On the third visit, an indwelling catheter was placed in a forearm vein. Thirty minutes later baseline blood and saliva samples were obtained followed by 30 minutes of exercise on a cycle ergometer at 69.5 ± 3.0% of VOA. Blood and saliva samples we e obtained at mid-exercise, end exercise and 15 minutes post-exercise. Serum and salivary cortisol were analyzed using RIA skit. Serum samples were corrected for changes in plasma volume. A repeated measures ANOVA revealed that exercise significantly increased serum, but not salivary cortisol. Mean salivary cortisol (ug.dl'') at baseline was 0.079 ± 0.042, at mid-exercise 0.099 ± 0.070, at end-exercise 0.133 ± 0.112, and at 15 minutes post-exercise was 0.143 ± 0.140. Post-hoc analyses indicated that mean serum cortisol at midexercise (7.94 ± 4.53 ug•dl-'), end-exercise (8.72 ± 5.61) and 15 minute post-exercise (8.21 ± 5.03 ug•dl'') were significantly greater than baseline (5.54 ± 2.73 ug•dl-'). The ratio of mean salivary to mean serum cortisol ranged from 1.3% to 1.7%. Serum and salivary cortisol were significantly correlated at mid-exercise (r=0.77), post-exercise (r=0.90) and 15 minutes post-exercise (r=0.84), but not at baseline. It is concluded that: (1) as a result -of exercise, children show adrenocortical activation as measured by serum cortisol; and, (2) salivary and serum cortisol are strongly correlated during and after exercise in children. / School of Physical Education