Kinematic dynamos in spheroidal geometries.

The kinematic dynamo problem is solved numerically for a spheroidal conducting fluid of possibly large aspect ratio with an insulating exterior. The solution method uses solenoidal representations of the magnetic field and the velocity by spheroidal toroidal and poloidal fields in a non-orthogonal coordinate system. Scaling of coordinates and fields to a spherical geometry leads to a modified form of the kinematic dynamo problem with a geometric anisotropic diffusion and an anisotropic current-free condition in the exterior, which is solved explicitly. The scaling allows the use of well-developed spherical harmonic techniques in angle. Dynamo solutions are found for three axisymmetric flows in oblate spheroids with semi-axis ratios 1≤a/c≤25. For larger aspect ratios strong magnetic fields may occur in any region of the spheroid, depending on the flow, but the external fields for all three flows are weak and concentrated near the axis or periphery of the spheroid.

Effect of graded levels of niacin supplementation of a semipurified diet on energy and nitrogen balance, growth performance, diarrhea occurrence, and niacin metabolite excretion by growing swine.

Thirty-six crossbred barrows with an average initial age of 42 d and BW of 13.8 kg were placed in individual metabolism crates in a 35-d experiment to evaluate the supplementation of a semipurified diet with graded levels of crystalline niacin. Response criteria were energy and N balance, growth performance, occurrence of niacin deficiency diarrhea, and urinary excretion of the niacin metabolite N(1)-methyl-2-pyridone-5-carboxylamide (PYR). The basal diet met the true ileal Trp requirement of growing swine, and supplementation with 6, 10, 14, 18, 22, or 44 mg of niacin/kg made 6 treatments. Pigs were observed for scours twice daily, and pig BW and feed consumption were determined weekly. Total urine collections and fecal grab samples were made twice daily from each pig from d 28 to 35. Pigs fed the diet containing 14 mg of niacin/kg absorbed and retained more (P < 0.05) grams of N/d, had a greater N digestibility (%, P < 0.05), a greater ADFI and ADG (P < 0.10), and no diarrhea (P < 0.05) compared with pigs fed the diet containing 6 mg of niacin/kg, and pigs fed the diet containing 10 mg of niacin/kg were intermediate in ADG. There were no additional improvements in the response criteria with niacin supplementation greater than 14 mg/kg. Urinary PYR criteria (mg/L and mg/d) were greater (P < 0.001) for pigs fed the diet containing 44 mg of niacin/kg than for pigs fed the diets containing 6 to 22 mg of niacin/kg. However, urinary PYR criteria for pigs fed the diets containing 6 to 22 mg of niacin/kg did not differ from each other, indicating that PYR was not a sensitive indicator of niacin status for growing swine. Niacin treatment did not affect the percentages of N retained/N absorbed, N retained/N intake, DE, or ME. In conclusion, 14 mg of crystalline niacin/kg of semipurified diet adequate in Trp was the minimum concentration of niacin that maximized N utilization and growth performance, and prevented niacin deficiency diarrhea of growing swine in the current experiment. Because practical feed ingredients may be sources of available endogenous niacin, supplementation of practical diets with 100% of the current NRC requirement for niacin should provide adequate niacin for growing swine.

Effects of halothane sensitivity on mobility status and blood metabolites of HAL-1843-normal pigs after rigorous handling.

The objective of this study was to determine if HAL-1843-normal pigs that respond abnormally to halothane anesthesia were more likely to become nonambulatory (NA) when subjected to rigorous handling than pigs that exhibit a normal response to halothane. After a 1,100-km transport, pigs exhibiting low (HS-L; n = 33), intermediate (HS-I; n = 10), and high (HS-H; n = 47) sensitivity to halothane were moved through a 36.6-m long aisle that was 2.1 m wide at each end and 0.6 m wide in the middle 18.3 m. Ten groups of 8 pigs were briskly moved down the aisle and back 4 times, receiving a minimum of 1 electrical prod per pass (8 prods/pig). Before testing, rectal temperature was measured, open-mouth breathing and skin discoloration were visually evaluated, and a blood sample was collected from each pig. After the test, the pigs were returned to their pens, and the same measurements were taken immediately posttest and 1 h posttest (no blood at 1 h posttest). Pigs that were HS-H were more prone to becoming NA compared with HS-L pigs (P < 0.02). Regardless of halothane status, a greater number of pigs exhibited open-mouth breathing and skin discolorations immediately posttest than at the pretest or 1 h posttest times (P < 0.05). No differences were observed in blood metabolites between the different halothane sensitivity categories. However, pigs that became NA had elevated blood levels of creatine phosphokinase, lactate, glycerol, nonesterified fatty acids, ammonia, and urea nitrogen before testing (P < 0.05). Collectively, these data suggest HS-H pigs are more susceptible to becoming NA than HS-L. The elevated pretest blood metabolites of NA pigs suggest that they were in a hypermetabolic state that predisposed them to becoming NA.

The effects of ractopamine hydrochloride on lean carcass yields and pork quality characteristics.

One hundred eighty barrows were evaluated to determine the effects of ractopamine hydrochloride (RAC) on lean carcass yields and pork quality. The pens were blocked by weight (six pens per block) with starting block weights of 69.0, 70.7, 73.8, 76.6, 78.4, and 84.3 kg. Pens within a block were assigned randomly to one of three RAC treatments so each treatment in a block was replicated twice. Treatments (as-fed basis) included control diet, 10 ppm of RAC added (R10), and 20 ppm of RAC added (R20) and ranged from 25 to 41 d depending on block. Pigs were slaughtered by blocks when block average live weights were 109 kg. Gain and feed efficiency were improved (P < 0.05) with increasing dietary concentrations of RAC, but feed intake did not differ (P > 0.05). Dressing percentage was higher (P < 0.05) for RAC-treated pigs. Subjective color, firmness, marbling scores, and Minolta L* reflection of the LM were not different (P > 0.05) among treatments. Carcass weights were heavier (P < 0.05) for pigs treated with RAC compared with control pigs and were higher for R20 than for R10. The RAC-fed pigs had greater (P < 0.05) yields (actual and percentage of HCW) of the following Institutional Meat Purchase Specification (IMPS) cuts than control pigs: trimmed, boneless ham (IMPS-402C and IMPS-402G), loin (IMPS-414), sirloin, and Boston butt (IMPS-406A). Pigs treated with RAC had a greater (P < 0.05) percentage of fat-free lean trimmings (IMPS-418) than did control pigs. Pigs treated with the R20 concentration had increased (P < 0.05) water-holding capacity compared with control pigs. Purge loss decreased linearly (P < 0.05) with increasing RAC compared with control for 14-d aged, non-enhanced loins. Warner-Bratzler shear (WBS) force values measured for nonenhanced chops were greater for RAC-treated pigs than for control pigs with a low dose response (P = 0.001). Enhanced chop (salt and phosphate injection) WBS values did not differ (P > 0.05) among dietary treatments. Trained sensory evaluation panel results for tenderness decreased in a low-dose plateau response fashion for nonenhanced chops (P = 0.004). Tenderness of enhanced chops decreased linearly (P = 0.04) with increasing RAC concentrations. No differences (P > 0.05) were found in juiciness or flavor of enhanced or nonenhanced chops. Feeding RAC to late-finishing swine resulted in faster growing, more efficient animals with increased boneless subprimal yields, and it had little effect on pork juiciness and flavor.

The effect of dietary ractopamine concentration and duration of feeding on growth performance, carcass characteristics, and meat quality of finishing pigs.

A total of 400 barrows from Dekalb EB and 83 terminal sires mated to 43 and 45 maternal lines were used to evaluate the effects of dietary ractopamine (RAC; Paylean, Elanco Animal Health, Greenfield, IN) concentrations (0, 5, 10, or 20 ppm; as-fed basis) and feeding durations (6 to 34 d) on growth, efficiency, carcass, and meat quality characteristics of finishing pigs. Barrows were weighed and sorted into five weight blocks, each block consisting of 16 pens (five pigs per pen). Weight blocks were allocated to feeding duration treatments and assigned consecutively by weight from lightest to heaviest to represent 34, 27, 20, 13, and 6 d on test, respectively. The lightest and heaviest blocks averaged 79.8 and 103.8 kg, respectively, at the start of the test. Within a weight block, pens (four per treatment) were randomly assigned to one of four dietary concentrations of RAC in a basal diet containing 18.5% CP and 1.13% lysine. The experiment-wide target slaughter weight was 109 kg, and pigs and feeders were weighed weekly. Weight blocks (80 barrows per block) were slaughtered at a commercial packing plant after 6, 13, 20, 27, or 34 d on test. Overall, RAC supplementation improved (P < 0.05) ADG; however, ADG was not different (P > 0.08) from controls for pigs fed 5, 10, and 20 ppm RAC for 27, 34, and 6 d, respectively. During each feeding period, RAC-fed pigs had improved (P < 0.05) G:F, and, after 20, 27, and 34 d on test, pigs fed 20 ppm RAC had greater (P < 0.05) G:F compared with those fed 0 or 5 ppm RAC. Hot carcass weight was increased (P < 0.05) by RAC feeding after 13 and 27 d of feeding, and by feeding 10 and 20 ppm RAC after 20 d of feeding. After 34 d, pigs fed 20 ppm RAC had heavier (P < 0.05) hot carcass weight than pigs fed 10 ppm RAC. Fat-free lean estimates and the 10th-rib LM area were increased (P < 0.05) by feeding 10 and 20 ppm RAC after 27 d, and by feeding 20 ppm RAC after 34 d compared with controls. Japanese and American color scores, as well as L*, a*, and b* values of the LM, were not affected (P > 0.11) by 5 and 10 ppm RAC compared with controls during each feeding period. Visual marbling score for the LM was decreased (P < 0.05) when RAC was fed at 10 and 20 ppm compared with 0 ppm RAC when fed for 34 d. Dietary RAC improved growth performance at all feeding durations, whereas carcass composition was improved at longer feeding durations. In addition, 5 and 10 ppm RAC did not affect objective and subjective measures of pork quality.

Effect of niacin additions to corn-soybean meal diets on performance of pigs from weaning to finishing.

An experiment was conducted to study the effect of adding crystalline niacin to low-protein diets on pig performance from weaning to market weight. Niacin was added at 0, 3, 9, 27, or 81 ppm to a low-protein test (LPT) diet fortified with crystalline amino acids and at 0 or 81 ppm to a positive control (PC) diet. Pens (four pigs/pen) were the experimental units with 12 and 8 pens per treatment during the 35-d nursery and 98-d growing-finishing phases, respectively. Niacin supplementation did not affect (P > .10) ADFI, ADG, gain:feed ratio, hair and skin condition, or the incidence of toe cracks and lameness during the nursery or the growing-finishing phases. There were no linear, quadratic, or cubic responses (P > .20) with increasing concentrations of added niacin in the LPT diets for the production criteria measured. Also, there were no interactions (P > .20) between niacin (0 or 81 ppm) and protein level (LPT or PC diets) for any of the criteria studied. Pigs fed the PC diets had greater (P < .05) ADFI, ADG, and gain:feed ratios over the entire experiment than pigs fed the LPT diets that contained 0 or 81 ppm of added niacin. In conclusion, the addition of niacin to low-protein or positive control corn-soybean meal diets did not improve pig performance criteria from weaning to market weight.

Effect of supplemental niacin on sow reproduction and sow and litter performance.

In this study the effects of supplemental crystalline niacin on sow reproduction and sow and litter performance were evaluated using 240 litters produced by 67 sows. A basal 12.80% CP corn-soybean meal-oat diet was supplemented with 0 or 33 mg of crystalline niacin/kg during gestation and lactation. The sows were grouped to equalize initial BW and parity among the two treatment groups. Each sow was fed 2.0 kg/d during gestation and 1.8 kg plus .45 kg per nursing pig during lactation. Sows not culled due to reproductive or structural problems remained on the experiment for five parities (average 3.6). Supplemental niacin did not improve (P > .20) any of the sow reproductive or sow and litter performance variables evaluated, including the subjective scores for sow lameness, toe cracks, and hair and skin condition. In conclusion, these results suggest that a 12.80% CP corn-soybean meal-oat diet provides adequate niacin during gestation and lactation without supplementation with crystalline niacin.

The effect of L-carnitine and soybean oil on performance and nitrogen and energy utilization by neonatal and young pigs.

A total of 64 neonatal pigs was used in an experiment to study the effect of L-carnitine and soybean oil on pig performance and N and energy utilization. Pigs were weaned at an average of 3 d of age and individually fed diets that contained dextrose, corn syrup solids, and isolated soy protein for 21 d. Two levels of soybean oil (1.18 or 12.31%) and L-carnitine (0 or 800 ppm) were used in a factorial arrangement of treatments. Diets were formulated to contain the same nutrient content per megacalorie of ME. Total fecal and urine collections were made from d 17 to 21 of the experiment. Pigs were paired within treatments on d 21 and housed in pens until d 63. L-carnitine was lowered to 750 ppm and the soybean oil additions were 1.15 or 13.22% from d 21 to 42 and 2.17 or 14.74% from d 42 to 63. Soybean meal replaced isolated soy protein from d 42 to 63. Analysis of covariance was used with calculated ME intake per day as the covariate. There were no carnitine x soybean oil interactions (P > .05) for any criteria measured. L-carnitine or soybean oil did not (P > .05) affect ADG, grams of gain per megacalorie of ME, ME as a percentage of GE or N retained as a percentage of N consumed. In conclusion, L-carnitine did not improve the utilization of ME in diets that contained high additions of soybean oil, and calories from soybean oil were utilized as effectively as calories from carbohydrate by neonatal and young pigs.