Supplemental phytases of microbial and cereal sources improve dietary phytate phosphorus utilization by pigs from weaning through finishing.

This experiment was conducted to measure the nutritional and metabolic responses of pigs fed diets with continuous supplementation of microbial and cereal phytase from weaning to finishing, and to determine the feasibility of complete replacement of inorganic P addition by supplemental phytase in swine diets. Forty-eight Landrace x Hampshire x Meishan pigs were divided into four groups. In phase 1 (10 to 50 kg BW), pigs in Groups 1, 2, 3, and 4 were fed a low-P, corn-soybean meal basal diet (BD), the BD plus microbial phytase (A. ficuum) at 1,200 units/kg, the BD plus 10% wheat bran (230 units of cereal phytase/kg), and the BD + .24% inorganic P (calcium phosphate), respectively. In phase 2 (51 to 90 kg BW), these pigs were fed a similar BD or the BD plus 1,000 microbial phytase units/kg, 20% wheat bran, or .20% inorganic P, respectively. Repeated measures included growth performance, P, Ca, and N balance, metatarsal and metacarpal bone strength, serum concentration of inorganic P, Ca, and 1,25-dihydroxycholecalciferol, and serum alkaline phosphatase activity. Pigs fed the BD supplemented with microbial phytase and pigs fed the BD supplemented with inorganic P showed almost identical responses for all variables. Pigs fed the BD supplemented with cereal phytase also had responses for various measures that were similar to those of pigs fed microbial phytase or inorganic P, except for some differences in serum inorganic P concentrations and bone strength in phase 1. Because of improvements in apparent digestibility of dietary P and N, fecal excretion of these two nutrients was reduced by 31 to 62% (P < .05) in pigs fed the BD supplemented with phytase compared with pigs fed inorganic P. It is physiologically feasible and environmentally advantageous to replace inorganic P with microbial or cereal phytase in corn-soybean meal diets for this type of pig through the entire growing-finishing period.

Gastric cannulation of pregnant sows.

The purpose of this project was to study the effect of superalimentation in lactating sows through permanent, surgically placed, gastric cannulas. A surgical technique was developed to install gastric cannulas into pregnant sows to allow superalimentation by introducing feed through the cannula. After induction of general anesthesia, a flexible, T-shaped cannula (22 mm outside diameter) was surgically placed in the dorsal portion of the greater curvature of the stomach and exteriorized through the tenth intercostal space approximately 30 cm left of the dorsal midline. Cannulas were installed on day 85 +/- 5 days of gestation. Anesthesia, surgical procedures, and the subsequent presence of the cannula did not affect the size or number of live pigs at birth. In addition, the prevalence of stillbirths and mummified fetuses was not significantly different than that of noncannulated sows. The gastric cannulas did not affect lactation performance, as litter size and weight were unaffected when compared with that in noncannulated controls. Postmortem examination of euthanatized sows revealed adhesions of the gastric wall to the abdominal wall, thus eliminating the possibility of leakage of the gastric contents into the peritoneum. Detrimental effects of the cannulas on gastric function or capacity were not detected, and cannulas could be maintained through multiple parities.

Effects of adding fat to the sow lactation diet on lactation and rebreeding performance.

One-hundred-three multiparous sows were randomly assigned to one of two lactation diets containing either no supplemental animal fat (C) or 10% added fat (F) during two seasons, summer (S) and winter (W), in a 2 X 2 factorial arrangement of treatments. Sows were placed on their respective dietary treatments 1 wk prior to farrowing and were fed these diets ad libitum throughout the 28-d lactation period. Weekly feed intake and total feed intake were not affected by diet or season, while weekly metabolizable energy (ME) intake tended to be higher during week 1 and 3, and was higher (P less than .04) during wk 2 for sows fed diet F. Sow weight loss from farrowing to 21 d of lactation and to weaning (28 d) were unaffected by diet or season. Average pig birth weight was .15 kg higher (P less than .01) for pigs born during S compared with those born in W. Sows receiving diet F had heavier litters at 21 d (P less than .01) and heavier average pig 21-d weights (P less than .01). This was primarily due to the 13.1% increase (P less than .04) in estimated milk yield and the higher fat concentration (P less than .001) of milk consumed by the pigs nursing sows fed diet F. Interval between weaning and rebreeding was shortened by 5.9 d (P less than .01) for sows during W than during S, and tended to be lower for sows fed diet F (7.3 d) compared with that of sows fed diet C (9.7 d).(ABSTRACT TRUNCATED AT 250 WORDS)

Developmental comparisons of boars and barrows: I. Growth rate, carcass and muscle characteristics.

The rate of gain, carcass measurements and three muscles were evaluated in 65 crossbred boars representing 13 litters that were allotted at 4 wk of age to slaughter weight and treatment groups as follows: 1) 105 kg, castrated; 2) 105 kg, intact; 3) 118 kg, intact; 4) 132 kg, intact and 5) 145 kg, intact. One barrow and four boars within a litter constituted a replicate and each replicate was penned separately. The growth rate of all boars to 105 kg constituted one group and was compared with the growth rate of barrows to 105 kg live body weight. Average daily gain from 4 wk until 105 kg did not differ significantly between boars and barrows. Growth rate of the boars continued at an increasing rate until they reached 87.3 kg live weight, while maximum daily gain of barrows occurred at 76.3 kg live weight or 11 kg less than that of boars. At 105 kg, boars had 31.3% less 10th rib backfat thickness and 2.9% greater carcass length than barrows, but longissimus muscle area did not differ. Barrows had greater backfat thickness at 105 kg than 145-kg boars. As live weight increased from 105 to 145 kg, carcass length, 10th rib backfat thickness and longissimus area of boars increased (P less than .01) linearly. Fat-free muscle weights of the brachialis (BR), semitendinosus (ST) and longissimus (L) did not differ between boars and barrows at 105 kg. Boars at 105 kg had 1.3 and 1.7% more moisture in the BR and ST, respectively, than barrows. Percentage protein, total intramuscular fat and fiber diameter in the BR, ST and L muscles did not differ between boars and barrows at 105 kg or with increasing live weight in boars. Total RNA increased linearly (P less than .05) in the BR and ST as boars increased in live weight from 105 to 145 kg.

Developmental comparisons of boars and barrows: II. Body composition and bone development.

Differences in total carcass bone, muscle and fat, and linear measurements of the tibia and radius were evaluated in barrows at 105 kg and boars at 105, 118, 132 and 145 kg live body weight. The carcasses of five replicates were physically separated into skin, bone and soft tissues, and the linear measurements of the tibia and radius were obtained on seven replicates. At live weight of 105 kg, boars did not differ significantly in fat-free muscle, but they had 33.2% less fat, 11% greater bone weight and 14% greater skin weight than barrows. At 145 kg, boars had total carcass fat weight comparable with 105-kg barrows. Fat-free muscle, bone and skin weight of boars increased at linear rates of .41, .083 and .104 kg/kg of body weight increase from 105 to 145 kg, respectively. At 105 kg, density and length of the tibia and radius did not differ between boars and barrows. The tibia of boars were heavier than those of barrows at 105 kg, resulting in a greater ratio of tibia weight to length (indirect measure of bone thickness). As boars increased in live weight from 105 to 145 kg, total weight and length of the tibia and radius increased linearly. The ratio of weight to length of the tibia and radius increased during this 40-kg weight gain, indicating that weight of both bones increased at a greater rate than length. These results indicate that boars and barrows have the same weight of total carcass fat when boars are 40 kg heavier than the barrows. The greater bone weight of boar carcasses compared with barrows is due to greater bone thickness.

Immunization of Swine for Production of Antibody Against Zearalenone.

Production of antisera specific for zearalenone was investigated in swine for potential use in prophylaxis against zearalenone hyperestrogenism. Swine were immunized with zearalenone-6'-carboxymethyloxime bovine serum albumin conjugate by four different protocols. For detection of antizearalenone antibody, a simple indirect enzyme-linked immunosorbent assay (ELISA) was devised whereby porcine antiserum was incubated over a zearalenone-6'-carboxymethyloxime poly-L-lysine solid phase and total bound antibodies were detected with peroxidase-labeled anti-swine serum. The optimal immunization protocol consisted of an initial injection of 5 mg of conjugate followed by a 2-mg boost at 4 wk and was sufficient to obtain anti-zearalenone titers of 1:5120 in 8 wk. Competitive indirect ELISA for zearalenone using this antiserum had an assay detection limit of 10 ng/ml for the toxin. Cross-reactivity of the antiserum with α-zearalenol, ß-zearalenol, α-zearalanol, and ß-zearalanol were 33, 25, 6, and 10%, respectively.

The effects of antibiotics in the weanling pig diet on growth and the excretion of volatile phenolic and aromatic bacterial metabolites.

The purpose of this study was to investigate the effects of dietary antibiotic supplementation on the fecal urinary excretion of volatile phenolic and aromatic bacterial metabolites by the weanling pig, and to determine if a relationship exists between an exposure to these metabolites and growth performance. Wealing pigs were fed a basal diet, supplemented with either 110 ppm chlortetracycline, 110 ppm sulfamethazine and 55 ppm penicillin, 40 ppm lincomycin sulfate, or no antibiotics, for 30 days. Pigs on the chlortetracycline-sulfamethazine-penicillin diet on the average tended to grow at a faster rate, attained a higher percentage weight gain, and weighed slightly more than pigs on either the lincomycin sulfate or no antibiotic diets. Under all treatments, p-cresol was the predominant metabolite of the volatile phenolic and aromatic metabolites detected in feces and urine, with the urine accounting for 88% of its total daily excretion. Pigs on the chlortetracycline-sulfamethazine-penicillin diet excreted less urinary p-cresol than pigs on either the lincomycin sulfate or no antibiotic diets. Total p-cresol excretion expressed on the metabolic body size, resulted in significant treatment differences. Regression analysis of percentage body weight gain on urinary p-cresol excretion gave a negative correlation coefficient (r = -0.73). The results suggest that intestinal p-cresol production may be responsible for depressing the growth of the weanling pig.

Polybrominated biphenyl (PBB) in the growing pig diet.

Twelve pigs which averaged 13.7 kg were randomly allotted from litters to a corn-soybean meal grower diet containing 0, 20, or 200 ppm of polybrominated biphenyls (PPB). During a 16-week growth trial, average daily gain (kg), average daily feed (kg) and feed/gain for pigs on diets containing 0, 20, or 200 ppm of PBB, respectively, were 0.82, 2.45, 2.99; 0.67, 1.88, 2.79; 0.45, 1.23, 2.70. Mean daily gain differences between all lots were highly significant (p < 0.01). Blood from each pig was withdrawn biweekly through the first 8 weeks of the trial and at 4 week intervals thereafter. Hemoglobin and hematocrit differed significantly only at the 6 weeks bleeding, being reduced in pigs receiving 200 ppm of PBB. Erythrocyte reduced glutathione concentration and glutathione peroxidase activity were not significantly influenced by level of dietary PBB. Serum lactic dehydrogenase activity was significantly higher in control pigs than in either PBB supplemented lots at 16 weeks. There was no significant influence of PBB upon serum glutamic oxaloacetic transaminase, serum alkaline phosphatase or serum creatine phosphokinase. Based on these enzyme assays, PBB produced no evidence of significant necrosis of liver, myocardium, or skeletal muscle. There was no consistent effect of dietary PBB upon total serum protein concentration or electrophoretic profile. Pigs on either level of PBB did not have overt clinical signs of toxicity during the 16-week test period with the exception of a dermatosis on the ventral surface of two of the pigs receiving 200 ppm of PBB. There was a marked increase in liver weight of pigs receiving either level of dietary PBB. Heart, kidney, and adrenals of pigs receiving either level of dietary PBB were heavier as a percent of body weight than that of control pigs. Fat retention of PBB and urinary and fecal PBB excretion were significantly affected by dietary PBB level. Grossly, the glandular portion of the stomach appeared somewhat hyperplastic in pigs on 200 ppm of PBB. Two pigs which had received 200 ppm of PBB were placed on the control diet and over the next 14 weeks normal growth rate occurred. One of these pigs was killed and organ weights were normal. The other pig, a gilt, came into estrus. She was bred and conceived. At the end of gestation, four pigs were born. Three survived and grew normally; the one death at birth examined at gross necropsy did not reveal changes in organ size or other tissue alterations.