0.05) during the 35-d period decreased linearly as CSB supplementation levels increased in the diets. In conclusion, CSB supplementation tended to increase colostral IgG and IgA concentrations in sows and improved growth performance of nursery pigs under an immune challenge when supplemented in the nursery diet.

Piglets are born with purportedly low plasma vitamin D levels. The objective of this study was to investigate the effect of fat-soluble vitamin administration, primarily vitamin D, by different administration routes on plasma vitamin concentrations in suckling pigs. A total of 45 pigs from 5 litters were allotted at birth to 3 treatments within each litter. Pigs were administered 400 IU of α-tocopherol, 40,000 IU of retinyl palmitate, and 40,000 IU of vitamin D at d 1 of age either orally or by i.m. injection and compared with control pigs with no supplemental vitamin administration. Blood samples were collected at d 0 (initial), 1, 2, 3, 4, 6, 9, 14, and 20 after administration. Plasma 25-hydroxycholecalciferol (25OHD), α-tocopherol, retinyl palmitate, and retinol concentrations were analyzed. Except for retinol, the effects of treatment, day, and day × treatment interaction ( < 0.01) were observed on plasma vitamin concentrations. Plasma concentrations of 25OHD and α-tocopherol increased immediately regardless of administration routes to peak at d 2 and 1 after administration, respectively. Plasma retinyl palmitate concentrations increased only with the injection treatment, with the peak at d 1 after administration. Plasma concentrations of 25OHD in both administration treatments and α-tocopherol in the injection treatment were maintained at greater levels than those in the control treatment until d 20 after administration. With regard to the pharmacokinetic parameters for plasma 25OHD concentrations, the injection treatment had greater elimination half-life ( < 0.01), maximum plasma concentrations ( < 0.05), and all area under the curve parameters ( < 0.01) but a lower elimination rate constant ( < 0.01) than the oral treatment. Relative bioavailability of oral administration compared with injection administration was 55.26%. These results indicate that plasma status of 25OHD,α-tocopherol, and retinyl palmitate are differentially changed between types of vitamins administered and between administration routes and that the injection route had a greater increase and slower disappearance of plasma vitamin levels than the oral route during the suckling period.

Inorganic boron (B), in the form of various borates, is readily absorbed across gastrointestinal epithelia. Although there is no stated B requirement, dietary B supplementation is thought to positively affect animal growth and metabolism, including promotion of bone strength and cell proliferation. Because of effective homeostatic control of plasma B levels, primarly by renal excretion, B toxicity in animals and humans is rare. The mechanisms responsible for improved animal performance and borate homeostasis are incompletely understood. Although a Na+-coupled borate transporter (NaBC1) has been identified, the effect of dietary B supplementation on expression of NaBCl has not been evaluated. An experiment was conducted with growing pigs to determine if NaBC1 mRNA was expressed by small intestinal epithelia and kidney of growing barrows and whether dietary B (as borate) supplementation would affect expression of NaBC1 mRNA. A concomitant objective was to test the hypothesis that B supplementation of a phosphorus (P)-deficient diet would improve calcium, phosphorus, or nitrogen retention. Twenty-four crossbred growing barrows (body weight=74.0±9.8 kg) were selected and used in a randomized complete block design experiment with a total of eight blocks and three B supplementation treatments (n=8/treatment). A typical corn-soybean meal basal diet (calculated to contain 41 mg intrinsic B/kg) was formulated to meet or exceed nutrient requirements, except for P, and fed to all pigs for 12 days. The basal diet plus 0, 50, or 100 mg/kg of B (prilled sodium borate pentahydrate, Na₂B₄O₇·5H₂O) was then fed for 18 more days. Feces and urine were collected during days 6 to 16 of the B supplementation, and pigs were killed for collection of jejunal and ileal epithelia and kidney tissue. Real-time reverse transcription-PCR analysis revealed that NaBC1 mRNA was expressed by these tissues, a novel finding for jejunal and ileal epithelia. Boron supplementation increased jejunal, but decreased, renal NaBC1 mRNA expression, relative to the 0 mg/kg treatment. The finding that NaBC1 mRNA is regulatable by dietary B is novel. That B supplementation evoked opposite effects on jejunal and kidney NaBC1 mRNA expression indicates that transcriptional regulation of NaBC1 expression may constitute a part of the homeostatic control of B metabolism. In contrast to its effect on NaBC1 mRNA expression, B supplementation did not affect total tract digestibility or retention of phosphorus, calcium, or nitrogen.

Evaluations of the nutritional impact of antibiotics have largely centered on effects related to the digestibility and utilization of protein and energy. Recent research has demonstrated that virginiamycin increases P digestibility. Because of the importance of P in diet cost and in waste management plans, the present study evaluated the potential impact of 2 additional antibiotics, bacitracin methylene disalicylate (bacitracin) and tylosin, on P digestibility in swine. A total of 48 barrows (mean initial BW, 63.0 to 82.9 kg) were used in 2 nutrient balance experiments. A basal corn-soybean meal diet that was not supplemented with any inorganic source of P was used in each experiment. In Exp. 1, two diets were tested: basal vs. basal plus 33.1 mg of bacitracin/kg of diet. In Exp. 2, two diets were also tested: basal vs. basal plus 44.1 mg of tylosin/kg of diet. In both experiments, the pigs were fed their diets for a minimum of 12 d before fecal and urine collection, and pigs were fed the diet at 2.7% of BW during the adaptation and collection period. In Exp. 1, the apparent DM, Ca, and P digestibility values for the basal and bacitracin diets were 91.69, 65.96, and 43.03 vs. 91.47, 65.46, and 41.79%, respectively, and did not differ by diet. In Exp. 2, the DM, Ca, and P digestibility values for the basal and tylosin diets were 91.03, 62.17, and 38.80 vs. 91.11, 63.20, and 40.10%, respectively, and did not differ by diet. The effect of the antibiotics on gut microflora was also appraised but the evaluations failed to demonstrate an effect on the microflora measured, with the exception that tylosin decreased the number of phytate-utilizing bacteria (P = 0.05). Therefore, because these 2 antibiotics did not demonstrate an improvement in P digestibility, improvements in P digestibility seem to be an antibiotic-specific response rather than a generalized antibiotic response.