Effect of natural betaine and ractopamine HCl on whole-body and carcass growth in pigs housed under high ambient temperatures.

Betaine is an osmolyte that helps to maintain water homeostasis and cell integrity, which is essential during heat stress. We hypothesized that supplemental betaine can improve growth during heat stress and may further improve the response to ractopamine. Two studies were conducted to determine: 1) the effects of betaine in combination with ractopamine; and 2) the optimum betaine level for late finishing pigs during heat stress. Heat stress was imposed by gradually increasing temperatures over 10 d to the target high temperature of 32°C. In Exp. 1, pigs ( = 1477, BW = 91.6 ± 3 kg) were assigned within BW blocks and sex to 1 of 4 diets arranged in a 2 × 2 factorial RCB design (68 pens; 20 to 23 pigs/pen). Treatments consisted of diets without or with ractopamine (5 mg/kg for 21 d followed by 8.8 mg/kg to market) and each were supplemented with either 0 or 0.2% of betaine. Betaine reduced ( ≤ 0.05) BW (123.1 vs. 124.3 kg), ADG (0.780 vs. 0.833 kg/d), and ADFI (2.800 vs. 2.918 kg/d), but did not impact carcass characteristics. Ractopamine increased ( < 0.01) BW (125.5 vs. 121.9 kg), ADG (0.833 vs. 0.769 kg/d), G:F (0.295 vs. 0.265), HCW (94.1 vs. 90.0 kg), carcass yield (74.8 vs. 73.8%), loin depth (63.6 vs. 60.0 mm), and predicted lean percentage (53.2 vs. 51.7%) and reduced ADFI (2.822 vs. 2.896 kg/d, = 0.033) and backfat depth ( < 0.001; 20.2 vs. 22.5 mm). In Exp. 2, pigs ( = 2193, BW = 95.5 ± 3.5 kg) were allocated within BW blocks and sex to 1 of 5 treatments in a RCB design (100 pens; 20 to 24 pigs/pen). Treatments consisted of diets with 0, 0.0625, 0.125, 0.1875% of betaine, and a positive control diet with ractopamine, but not betaine. Betaine tended to decrease carcass yield quadratically ( = 0.076; 74.1, 73.5, 73.8, and 73.9 for 0, 0.0625, 0.125, 0.1875% of betaine, respectively), but did not impact other responses. Ractopamine improved ( < 0.001) BW (121.6 vs. 118.5 kg), G:F (0.334 vs. 0.295), carcass yield (74.7 vs. 73.8%), loin depth (61.7 vs. 59.0 mm), and predicted lean percentage (53.2 vs. 52.6%), and reduced backfat (18.7 vs. 20.4 mm). Collectively, data indicate that under commercial conditions, betaine did not improve performance of pigs housed under high ambient temperatures, regardless of ractopamine inclusion. Ractopamine improved whole-body growth and especially carcass growth of pigs raised under high ambient temperatures. The ability of ractopamine to stimulate growth during heat stress makes it an important production technology.

Effects of Added Zinc on Skeletal Muscle Morphometrics and Gene Expression of Finishing Pigs Fed Ractopamine-HCL.

Finishing pigs (n = 320) were used in a 35-day study to determine the effects of ractopamine-HCl (RAC) and supplemental Zinc (Zn) level on loin eye area (LEA) and gene expression. Pens were randomly allotted to the following treatments for the final 35 days on feed: a corn-soybean meal diet (CON), a diet with 10 ppm RAC (RAC+), and RAC diet plus added Zn at 75, 150, or 225 ppm. Sixteen pigs per treatment were randomly selected for collection of serial muscle biopsies and carcass data on day 0, 8, 18, and 32 of the treatment phase. Compared to CON carcasses, RAC+ carcasses had 12.6% larger (P = 0.03) LEA. Carcasses from RAC diets with added Zn had a tendency for increased (quadratic, P < 0.10) LEA compared to the RAC+ carcasses. Compared to RAC+ pigs, relative expression of IGF1 decreased with increasing levels of Zn on day 8 and 18 of treatment, but expression levels were similar on day 32 due to Zn treatments increasing in expression while the RAC+ treatment decreased (Zn quadratic × day quadratic, P = 0.04). A similar trend was detected for the expression of ß1-receptor where expression levels in the RAC+ pigs were greater than Zn supplemented pigs on day 8 and 18 of the experiment, but the magnitude of difference between the treatments was reduced on day 32 due to a decrease in expression by RAC+ pigs and an increase in expression by the Zn pigs (Zn quadratic × day quadratic, P = 0.01). The ability of Zn to prolong the expression of these two genes may be responsible for the tendency of Zn to increase LEA in RAC supplemented pigs.

Effect of added zinc in diets with ractopamine hydrochloride on growth performance, carcass characteristics, and ileal mucosal inflammation mRNA expression of finishing pigs.

Two experiments were conducted to determine the effects of increasing the dietary Zn content on growth performance, carcass characteristics, plasma Zn, and ileal mucosal inflammation mRNA expression of finishing pigs fed diets containing ractopamine HCl (RAC; Elanco Animal Health, Greenfield, IN). In Exp. 1, 312 pigs (327 × 1050; PIC, Hendersonville, TN; 94 kg BW) were used in a 27-d study. There were 2 pigs per pen and 26 pens per treatment. Treatments included a corn-soybean meal diet (control; 0.66% standardized ileal digestible [SID] Lys); a diet (0.92% SID Lys) with 10 mg/kg RAC; and the RAC diet plus 50, 100, or 150 mg Zn/kg from ZnO or 50 mg Zn/kg from a Zn AA complex (ZnAA; Availa-Zn; Zinpro, Eden Prairie, MN). All diets also contained 83 mg Zn/kg from ZnSO4 in the trace mineral premix. Pigs fed the RAC diet without added Zn had increased (P < 0.05) ADG, G:F, HCW, carcass yield, and loin weight compared with pigs fed the control diet. Increasing Zn from ZnO in diets containing RAC tended to increase (linear, P = 0.067) G:F and loin weight (quadratic, P = 0.064). Pigs fed diets with 50 mg Zn/kg from ZnAA tended to have increased (P = 0.057) ADG compared with pigs fed the RAC diet. In Exp. 2, 320 pigs (327 × 1050; PIC; 98 kg BW) were used in a 35-d study. There were 2 pigs per pen and 20 pens per treatment. Treatments included a control diet (0.66% SID Lys); a diet (0.92% SID Lys) with 10 mg/kg RAC; or the RAC diet plus 75, 150, and 225 mg Zn/kg from ZnO or ZnAA. All diets also contained 55 mg Zn/kg from ZnSO4 from the trace mineral premix. Pigs fed the RAC diet had increased (P < 0.05) ADG, G:F, HCW, loin depth, percentage lean, and liver weight compared with pigs fed the control diet. No Zn level or source effects or level × source interactions were observed for growth performance. A Zn level × source interaction (quadratic, P = 0.007) was observed in liver Zn concentrations. This resulted from liver Zn concentrations plateauing at 150 mg Zn/kg when ZnO was supplemented, while there was a linear increase when using ZnAA. Increasing Zn in diets containing RAC increased (linear, P < 0.05) plasma Zn on d 18 and 32. The expression of IL-1ß was increased (P = 0.014) in mucosa of pigs fed the RAC diet compared with those fed the control diet. Expression of IL-1ß decreased (linear, P = 0.026) in the mucosa of pigs fed increasing added Zn. In conclusion, adding Zn to diets containing RAC resulted in a trend for improved growth performance of pigs in 1 of 2 experiments. Also, additional Zn increased plasma Zn and reduced IL-1ß.

Effect of dietary zinc and ractopamine hydrochloride on pork chop muscle fiber type distribution, tenderness, and color characteristics.

A total of 320 finishing pigs (PIC 327 × 1050; initially 98 kg) were used to determine the effects of adding Zn to diets containing ractopamine HCl (RAC) on muscle fiber type distribution, fresh chop color, and cooked meat characteristics. Dietary treatments were fed for approximately 35 d and consisted of a corn-soybean meal-based negative control (CON), a positive control diet with 10 mg/kg of RAC (RAC+), and the RAC+ diet plus 75, 150, or 225 mg/kg added Zn from either ZnO or Availa-Zn. Loins randomly selected from each treatment (n = 20) were evaluated using contrasts: CON vs. RAC+, interaction of Zn level × source, Zn level linear and quadratic polynomials, and Zn source. There were no Zn source effects or Zn source × level interactions throughout the study (P > 0.10). Pigs fed RAC+ had increased (P < 0.02) percentage type IIX and a tendency for increased (P = 0.10) percent type IIB muscle fibers. Increasing added Zn decreased (linear, P = 0.01) percentage type IIA and tended to increase (P = 0.09) IIX muscle fibers. On d 1, 2, 3, 4, and 5 of display, pork chops from pigs fed the RAC+ treatment had greater (P < 0.03) L* values compared to the CON. On d 0 and 3 of display, increasing added Zn tended to decrease (quadratic, P = 0.10) L* values and decreased (quadratic, P < 0.03) L* values on d 1, 2, 4, and 5. Pigs fed RAC+ had decreased (P < 0.05) a* values on d 1 and 4 of display and tended to have decreased (P < 0.10) a* values on d 0 and 2 compared to CON pork chops. Pork chops from the RAC+ treatment had a tendency for increased (P < 0.08) oxymyoglobin percentage compared to CON pork chops on d 1, 2, 4, and 5. On d 0, as dietary Zn increased in RAC+ diets, there was a decrease (linear, P < 0.01) in the formation of pork chop surface oxymyoglobin percentage. Metmyoglobin reducing ability (MRA) of pork chops on d 5 was decreased in the RAC+ group. Chops from pigs fed added Zn had increased (quadratic, P < 0.03) MRA on d 3 and 5 of the display period. There was a trend for increased (linear, P = 0.07) cooking loss with increasing Zn in RAC diets and treatments did not affect tenderness as measured by Warner-Bratzler shear force (P > 0.07). In conclusion, RAC+ diets produced chops that were lighter and less red but maintained a greater percentage of surface oxymyoglobin throughout a 5-d simulated retail display. Ractopamine reduced MRA at the end of the display period, but supplementing Zn to RAC diets restored MRA to near CON treatment levels at the end of the display period.

Effects of dietary supplementation of an enzyme blend on the ileal and fecal digestibility of nutrients in growing pigs.

The objective of this experiment was to determine the effect of a beta-glucanase-protease enzyme blend product (EBP) on fecal digestibility (FD), apparent ileal digestibility (AID), standardized ileal digestibility, and digestibility in the hindgut of growing pigs. Twelve ileal-cannulated, growing barrows (38.2 +/- 0.5 kg) were housed in individual metabolism crates, blocked by previous feed intake into 3 groups with 4 pigs each, and randomly assigned to 1 of 4 treatments within a square (group) of 3 replications of 4 x 4 Latin square design. Treatments were basal diet (Basal), Basal + 0.05% of EBP (0.05% EBP), Basal + 0.10% of EBP (0.10% EBP), and hydrolyzed casein for measurement of endogenous amino acids. The Basal diet consisted of corn and soybean meal and was calculated to have 3.36 Mcal of ME/kg and 1.1% of total lysine, as-fed basis. Feed intake of each replicate of the Latin square during the first period was 85% of the minimum feed intake of the 4 pigs during the preliminary period and was equalized within each square. The feeding level was increased by 100 g/d in each subsequent period. Each of the experimental periods was 14 d, including 4 d of dietary adaptation, 5 d of fecal collection, 3 d of transition period, and 2 d of ileal collection. Ileal effluents were collected continuously for the same 12-h interval each day. Pigs fed the EBP demonstrated increased (P < 0.05) FD of DM, OM, energy, CP, nonfiber carbohydrate, total dietary fiber, insoluble dietary fiber, acid-hydrolyzed fat, ash, Ca, and P compared with pigs fed Basal. The AID of NDF and hemicellulose was increased (P < 0.05) by supplying the EBP either at 0.05 or 0.10% in the diets, but AID of DM and energy was not increased. The AID of acid-hydrolyzed fat tended to be greater (P = 0.051) for the pigs fed the EBP than for those fed Basal. Ileal digestibility of most amino acids was not affected by treatment, but the EBP reduced the apparent and standardized digestibility of methionine, alanine, and serine (P < 0.05). The difference between FD and AID of hemicellulose was lower (P < 0.05) for the pigs fed the EBP than for those fed Basal. These results demonstrated that the EBP fed to growing pigs improved the FD of DM, OM, energy, CP, nonfiber carbohydrate, total dietary fiber, acid-hydrolyzed fat, Ca, and P, and the AID of NDF and hemi-cellulose, but the standardized ileal digestibility of amino acids was not improved by supplying the EBP in corn-soybean meal-based diets of growing pigs.

The effect of various diet nutrient densities and electrolyte balances on sow and litter performance during two seasons of the year.

An experiment involving 289 farrowings during a 2-yr period was conducted to determine the effect of increasing dietary nutrient concentration, electrolyte balance, and season of the year on the lactational performance of sows. Experimental diets were corn-soybean meal-based. The basal diet was formulated to meet or exceed the NRC requirements and the high-nutrient diet was formulated to contain approximately 20% higher levels of the nutrients than the basal diet, with or without adjustment of the electrolyte balance (Na+K-Cl) to 250 mEq/kg. Experimental diets were fed in both the warm (May through October) and cool (November through April) seasons of the year, resulting in a 2 x 2 x 2 factorial arrangement of treatments. There were no season x treatment interactions for any of the indices measured. During the first 21 d of lactation, sows farrowing in the cool season consumed more feed (P < .001) and produced heavier (P < .001) pig weights and litter weight gains than sows farrowing in the warm season. Increasing nutrient density from 100 to 120% of the NRC requirements resulted in decreased (P < .05) daily feed consumption, but it increased (P < .001) daily CP and GE intake, 21-d pig weights, and litter weight gains. Adjusting the dietary electrolyte balance from normal (130 mEq/kg) to 250 mEq/kg tended to increase (P < .07) 21-d pig weights, but it had no effect on other indices measured. These data indicate that under the environmental and management conditions of this experiment, the nutrient requirements of the lactating sow are higher than the current NRC standards.

Effects of feeding diets containing different fat supplements to swine on the visual properties and storage stability of low-fat sausage.

Sixty barrows and gilts were assigned to one of five dietary treatments consisting of a control diet of corn and soybean meal and four similar test diets that contained a 10% replacement of either animal fat, safflower oil, sunflower oil or canola oil, to determine the effects of high levels of oleic acid in the diet of swine on the storage stability of fresh pork sausage. Pork trim from each treatment was used to formulate sausage that contained two fat levels (25% and 35%), and two levels of added water (3% and 11%). Thiobarbituric acid values did not differ between the control, safflower oil or sunflower oil treatments and all treatments were acceptable after 10 weeks of storage. Microbial numbers increased with the level of added water and during time in storage (up to 3 weeks). Visual evaluation showed that the control was the most red and least discolored, while the canola oil treatment was the least red and the most discolored. Results from the present study suggest that a 105 replacement of a typical corn/soybean meal diet to swine with safflower or sunflower oil did not alter the storage-stability of fresh pork sausage.

Dietary cation-anion balance and cation source effects on production and acid-base status of heat-stressed cows.

Two 4 x 4 replicated Latin square studies, each containing 8 lactating Holstein cows, were conducted simultaneously in south Georgia during the summer. The effects of dietary cation source (Na or K) and increasing dietary cation-anion balance (milliequivalents of Na + K - Cl per kilogram of feed DM) within cation source (control = 120.4 meq/kg of feed DM; Na source = 219.7, 347.8, 464.1 meq/kg of feed DM; K source = 231.2, 352.6, 456.0 meq/kg of feed DM) were determined on performance and acid-base chemistry during hot, humid weather. Cow body temperatures were elevated by environmental conditions but were not affected by dietary cation-anion balance. Differences in body temperature from dietary cation source probably were related to differences in cow BW. Intake of DM increased linearly, but yields of milk and FCM did not change with increasing dietary cation-anion balance, and cation source had no effect. Milk fat and protein percentages were not altered by dietary cation-anion balance, and greater milk fat and protein percentages from cows offered the Na versus K source diets probably were due to differences between cows in the two Latin squares. Alterations in blood acid-base chemistry with increasing dietary cation-anion balance were as expected. Greater blood buffering capacity, indicated by blood base excess and bicarbonate content, may be responsible for the improved feed intake.

The effect of copper and fat addition to the diets of weanling swine on growth performance and serum fatty acids.

A 2 x 3 factorial experiment, encompassing three 28-d trials involving a total of 420 weanling pigs, was conducted to determine the effect of dietary Cu (5 or 250 ppm) and animal fat (0, 2.5, or 5%) on the performance and serum fatty acid profiles of weanling pigs. Pigs had ad libitum access to corn-soybean meal-based diets containing 10% whey and 5% fish meal and similar lysine:calorie ratios. Pigs were weighed and pen feed intakes were recorded weekly. Weekly blood samples were collected during the first two trials (n = 270) for serum fatty acid analysis. There was a Cu x fat interaction for ADG from d 1 to 14 (P less than .07) and over the 28-d experiment (P less than .05). The ADG of pigs fed 250 ppm of Cu increased, whereas the ADG of pigs fed 5 ppm of Cu was not affected as dietary fat increased. The addition of 250 ppm of CU increased (P less than .01) ADFI throughout the 28-d experiment. The addition of fat quadratically increased ADG (P less than .05) during d 14 to 28 and gain:feed ratios (P less than .01) during d 14 to 28 and over the 28-d experiment. The addition of fat decreased (P less than .05) the weight percentage of serum saturated fatty acids and increased (P less than .01) the weight percentage of serum monounsaturated fatty acids on d 28. The addition of 250 ppm of Cu decreased (P less than .01) the weight percentage of monounsaturated fatty acids on d 14 and 28.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of copper addition to diets with various iron levels on the performance and hematology of weanling swine.

A 2 x 6 factorial experiment with Cu added at 5 or 250 ppm and Fe added at 50, 100, 150, 200, 250, or 300 ppm was conducted using 480 crossbred weanling pigs with an average initial weight of 7.0 kg. The basal corn-soybean meal-whey diet contained 4 ppm Cu, 169 ppm Fe, and 199 ppm Zn. Pigs were allotted by weight, sex, and litter outcome group and had ad libitum access to feed and water during the 28-d trials. Animals were weighed and pen feed intake was recorded weekly. Blood samples were collected on d 1, 14, and 28 of the experiment. The addition of 250 ppm Cu increased ADG (P less than .001) and average daily feed intake (ADFI, P less than .01) during the 28-d trials. The addition of Fe had no effect on ADG and ADFI (P greater than .10). A Cu x Fe interaction (P less than .01) was observed for feed/gain. Increasing Fe levels linearly improved hematocrit status (P less than .05) on d 28 of the trial. A Cu x Fe interaction (P less than .08) was observed for hemoglobin at the end of the trial; hemoglobin levels were increased by the addition of Fe to the diet containing 250 ppm of Cu. Plasma Cu was increased (P less than .001) by the addition of 250 ppm of Cu. Plasma Fe was low when either 50 or 100 ppm of Fe was added in the presence of 250 ppm of Cu, but it was not affected at other levels, resulting in a Cu x Fe interaction (P less than .05). These data indicate that levels of added Fe up to 300 ppm may help to improve the hematological status of weanling pigs fed growth-promoting levels of Cu but that it has little effect on performance.

Nutrient digestibilities of soft winter wheat, improved triticale cultivars, and pearl millet for finishing pigs.

A replicated 4 x 4 Latin square digestion trial was conducted to determine apparent nutrient digestibilities and N and energy balances for soft red winter wheat, Beagle 82 triticale, Florico triticale, and pearl millet using finishing pigs fitted with ileal T-cannulas. Fortified experimental diets contained 97.5% of each respective grain. Nitrogen and amino acid digestibilities of soft winter wheat and triticale were similar (P greater than .13) when measured near the end of the small intestine and over the total digestive tract. Ileal digestibilities of alanine, isoleucine, leucine, threonine, tryptophan, and valine were higher (P less than .05) for pearl millet than for the other grains. Total tract N and amino acid digestibilities were all higher than ileal digestibilities. Gross energy and DM digestibilities determined at the small intestine were higher (P less than .05) for wheat and pearl millet than for Beagle 82 triticale, with the Florico variety being intermediate in energy digestibility. Total tract digestible and ME concentrations followed essentially the same pattern as ileal GE digestibility and were 2 to 3% higher (P less than .05) for wheat and pearl millet than Beagle 82 triticale. Florico triticale had similar (P greater than .05) DE but was 1.3% lower (P less than .05) in ME content than wheat.

Acceptability of low-fat frankfurters as influenced by the feeding of elevated levels of monounsaturated fats to growing-finishing swine.

The effects of high levels of oleic acid in the diet on the physical, chemical and sensory traits of frankfurters were examined. Frankfurters were formulated at three fat levels (10, 20 and 25%) from pork trimmings from each dietary treatment. The control frankfurters were the most springy, firm, flavorful and palatable and had the most intense flavor (P < 0·05). However, low-fat frankfurters produced from the high-oleate treatments were comparable to the control in all sensory characteristics (P > 0·05). The 10 and 25% fat frankfurters were rated highest and lowest, respectively, for juiciness, springiness, firmness, flavor, flavor intensity and overall palatability (P < 0·05). Sensory panelists detected off-flavors in the 25% fat frankfurters more frequently than in the 10% fat frankfurters (P < 0·05). 2-Thiobarbituric acid values were not affected by treatment and were acceptable after storage at 2°C for 24 weeks (P < 0·05).

The prediction of percentage of protein in pork carcasses.

Determination of percentage of protein in a pork carcass is a very costly and lengthy process. Therefore, we attempted to identify an easy and economical means to predict protein content of pork carcasses. Forty-seven market-weight pigs were slaughtered. The right side of each carcass was skinned, deboned and ground for composition analysis. Carcass data were collected on the left side and specific gravity analysis was performed on the side, ham and 8-9-10 rib loin section of each carcass. The hams and loin sections were dissected into skin, bone, subcutaneous fat, seam fat and individual muscles. After these components were weighted, they were analyzed for chemical composition. Percentage of chemical protein of each animal was determined and correlated with each of the weights and measurements taken on the carcass, ham and loin sections. Stepwise regression was used to predict decimal fraction of protein using either the carcass data, specific gravity ham measurements, loin section measurements or various combinations of these. In prediction equation, specific gravity of the carcass accounted for 73.4% of the variation found in percentage of protein. Prediction equations using indicators from the ham and loin section resulted in equations with R-square values as high as .783. These results suggest that specific gravity or indicators from the carcass, ham or loin section can be employed to predict percentage of protein in pork carcasses.

The prediction of percentage of fat in pork carcasses.

Forty-seven market-weight pigs were slaughtered in order to determine percentage of chemical fat and in an attempt to determine an easily obtainable and inexpensive method to predict this value. The hams and 8-9-10 rib loin sections were removed from the left side of each carcass and dissected into subcutaneous and seam fat, individual muscles, skin and bone. Weights and chemical analysis were determined for each component. Numerous weights, measurements and specific gravity were determined on the carcass, ham and loin section of each pig. Percentage of chemical fat of each ham, loin section and carcasses was determined and correlated with the various weights and measurements taken. Stepwise regression was used to develop prediction equations using carcass data, specific gravity, ham or loin measurements or various combinations of these as dependent variables. The single best indicator of the decimal fraction of chemical fat in the pork carcass was determined to be specific gravity of the carcass half, the prediction equation using this variable had an R-square of .64. By adding 10th rib fat thickness to this equation, the R-square increased to .72. The best equation using carcass variables included 10th rib fat and marbling (R-square = .67). The loin section proved to be an accurate indicator of composition; ham measures were not as accurate as specific gravity and carcass measurements for predicting percentage of carcass fat. This research suggests that the percentage of chemical fat in the pork carcass can be predicted by an easy and inexpensive means.

Effect of dietary electrolyte balance on nutrient digestibility determined at the end of the small intestine and over the total digestive tract in growing pigs.

A replicated 4 x 4 Latin square digestion trial was conducted to determine the effect of electrolyte balance (EB = Na + K - Cl meq/kg of the diet) on apparent nutrient digestibilities in pigs fitted with ileal T-cannulas. Experimental diets were composed of corn and soybean meal with dietary EB altered by the substitution of CaCl2 for CaCO3, or NaHCO3 for corn and soybean meal. Electrolyte balance levels examined were -50, 100, 250 or 400 meq/kg of the diet. Increasing dietary EB concentration linearly increased (P less than .05 to P less than .02) apparent ileal digestibility of N, energy, DM and all amino acids, except alanine and methionine. However, nutrient and amino acid digestibilities measured over the total digestive tract were similar (P greater than .16) among EB levels. Increasing dietary EB resulted in a linear and quadratic (P less than .03) effect on daily urinary N excretion, resulting in a linear (P less than .05) improvement in N retention expressed both as a percentage of N intake and of absorbed N. Blood pH, total CO2, HCO3 and base excess concentrations increased linearly (P less than .02 to P less than .001) with increasing dietary EB. Dietary EB concentrations influenced nutrient and amino acid absorption measured near the end of the small intestine. Additionally, the N balance data per unit of N intake or N absorbed are indicative of an improved N utilization in pigs fed increasing dietary EB concentrations from -50 to 400 meq/kg.

Effect of roasted or raw peanut kernels on lactation performance and milk composition of swine.

A lactation trial involving 105 sows was conducted to determine the effect of 12% roasted or raw, ground, whole, shelled peanuts on sow weight change during lactation, feed intake, piglet and litter weight gain, milk composition, and days to return to postweaning estrus. The trial was conducted using three sow groups during two farrowing seasons, summer (July to September) and winter (December to February). Diets were based on corn plus soybean meal. Diets contained either 5% animal fat or equivalent added fat from 12% roasted or raw, ground, shelled peanuts. The replacement of animal fat by roasted or raw peanuts had no effect (P greater than .20) on sow weight change, average daily feed intake during lactation or days to estrus postweaning, or on piglet weight gain or survival. Milk composition (percentage fat and protein) was not altered (P greater than .20) by source of fat in the summer; however, in the winter, sows fed roasted peanuts had higher (P less than .05) milk fat and protein percentage at 3 d postfarrowing than other treatment groups. At d 7, sows fed 12% roasted or raw peanuts had higher (P less than .05) milk protein than sows fed 5% animal fat. Sows farrowing in the summer had greater (P less than .01) weight loss and consumed less (P less than .05) feed during lactation than sows farrowing in the winter. Sows farrowed in the summer had larger (P less than .05) litters at birth and 14 d postfarrowing and greater (P less than .10) piglet and litter weight gain postfarrowing than those farrowed in the winter.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of dietary electrolyte balance on performance and blood parameters of growing-finishing swine fed in high ambient temperatures.

A growing-finishing trial using 96 crossbred pigs (21.8 kg initially) was conducted to determine the effect of dietary electrolyte balance (EB = Na + K - Cl, meq/kg of feed) on rate and efficiency of weight gain, blood gases and whole blood Na and K concentration during high ambient temperatures. Dietary EB (25, 100, 175, 250, 325 or 400 meq/kg) was altered by the substitution of CaCl2 for CaCO3 or NaHCO3 for corn and soybean meal. Increasing EB during the grower phase (21 to 50 kg) increased feed intake and average daily gain linearly (P less than .03). Efficiency of feed utilization was unaffected (P greater than .70). During the finisher phase (50 to 105 kg), live weight gain was 7% higher for pigs receiving the 250 meq EB diet compared with the average of all other EB levels. Feed intake during the finisher period increased linearly (P less than .03) as dietary EB increased from 25 to 400 meq/kg of diet. Live weight gain and daily feed intake measured over the entire growing-finishing period (21 to 105 kg) improved linearly (P less than .03) with increasing dietary EB. Blood pH, HCO3, total CO2, Na concentration, and base excess increased linearly (P less than .05) as dietary EB increased. We interpret the data to indicate that feed intake and weight gain of growing-finishing swine may be enhanced by dietary electrolyte modification during periods of high ambient temperature. This improvement probably is due to increased blood buffering capacity.

Distribution of aflatoxins in tissues of growing pigs fed an aflatoxin-contaminated diet amended with a high affinity aluminosilicate sorbent.

The effect of hydrated sodium calcium aluminosilicate (HSCAS) added to the diet of swine fed an aflatoxin-contaminated diet on tissue aflatoxin levels was investigated. Pigs were fed control (less than 10 ng/g B1 + B2), contaminated (500-600 ng/g B1 + B2), and contaminated +0.5% HSCAS diets. Tissues analyzed for the presence of aflatoxin B1, B2, and M1 residues included liver, muscle, kidney, and adipose. Addition of HSCAS to the contaminated diet significantly reduced the amount of M1 in liver, kidney, and muscle tissue. Aflatoxin B1 was not reduced in liver or kidney, but was decreased in muscle.

Effect of a high affinity aluminosilicate sorbent on prevention of aflatoxicosis in growing pigs.

Adding 0.5% hydrated sodium calcium aluminosilicate to diets formulated with aflatoxin-contaminated corn significantly reduced the detrimental effects of the mycotoxin on live weight gains and feed intake. Hepatocellular changes normally associated with aflatoxin consumption could not be detected histopathologically in liver sections from pigs fed contaminated diets plus the aluminosilicate sorbent.

Effect of lasalocid on reproductive performance and subsequent lactation in the sow.

The effect of lasalocid (140 mg . head-1 . d-1) on sow reproductive performance and subsequent piglet performance during lactation were examined in a trial that involved 114 sows. Treatments consisted of 1) control diet with no lasalocid during gestation and lactation; 2) lasalocid diet during gestation, control diet during lactation; 3) control diet during gestation and lasalocid diet during lactation; and 4) lasalocid diet during gestation and lactation. The addition of lasalocid either to gestation or lactation diets had no effect (P greater than .10) on sow weight gains or days to return to estrus postweaning. Milk protein percentages were similar (P greater than .10) for sows in all treatment groups for samples taken at 3, 7 and 14 d postfarrowing. Milk fat percentages were higher (P less than .05) in fall-bred sows at d 3 for Treatments 1, 3 and 4 than for Treatment 2 No significant differences (P less than .10) were observed for litter size at birth, 21 d postfarrowing or at weaning. Piglet weights at birth, 21 d and weaning were similar (P less than .10) among treatment groups. However, litter size and litter weight gains tended to be heavier at 21 d postfarrowing and at weaning for fall-bred sows fed lasalocid in either gestation and (or) lactation compared with those fed the control diet.