Four chick trials and one pig trial were conducted to investigate the phosphorus-releasing efficacy oftwo commercial phytase enzymes (Natuphos and Ronozyme) and an experimental E. coli phytase enzyme (ECP) when added to corn-soybean meal diets containing no supplemental inorganic P (iP). In the 13- or 14-d chick trials, three or four graded levels of iP (0, 0.05,0.10,0.15%) from KH2PO4 were added to the basal diet to construct standard curves from which bioavailable P release could be calculated for the phytase treatments. In all cases, phytase supplementation levels were based on an assessment of phytase premix activity (i.e., P release from Na phytate at pH 5.5). Linear (P < 0.01) responses in tibia ash and weight gain resulted from iP supplementation in all assays. In the first chick trial, supplementation of 500 phytase units (FTU)/kg of ECP resulted in superior (P < 0.01) weight gain and tibia ash values compared with 500 FTU/kg of Natuphos. Results of the second chick trial revealed P-release values of 0.032 and 0.028% for 500 FTU/kg Natuphos and Ronozyme, respectively, and these were lower (P < 0.01) than the 0.125% P-release value for 500 FTU/kg of ECP. Tibia ash responded quadratically (P < 0.05) in response to graded levels of ECP up to 1,500 FTU/kg in the third chick trial. Combining Natuphos with either Ronozyme or ECP in Chick Trial 4 revealed no synergism between phytases with different initiation sites of P removal. The pig trial involved 10 individually fed weanling pigs per diet, and and phytase enzymes were supplemented to provide 400 FTU/kg in diets containing 0.60% Ca. Based on the linear regression of fibula ash on supplemental iP intake (r2 = 0.87), P-release values were 0.081% for Natuphos, 0.043% for Ronozyme, and 0.108% for ECP. These trials revealed an advantage of the E. coli phytase over the commercial phytases in young chicks.

The aim of this research was to determine whether feeding gestating and lactating sows (n-3) PUFA [eicosapentaenoic acid (EPA) and/or docosahexenoic acid (DHA)] or coconut fat (saturated fat) influences ex vivo glucose absorption in the proximal jejunum and glucose and glycogen concentration of liver and muscle of their offspring at weaning. Sows were fed 1 of 4 diets for 150 d, which included the entire gestation and lactation periods. The diets consisted of basal corn/soybean meal (CONT), CONT + protected EPA and DHA-rich fish oil (PFO), CONT + DHA Gold fat (DHAGF), and CONT + coconut fat (COCO). All tissues were collected from piglets (n = 4 per treatment) following a 24-h period of food deprivation, which was initiated at weaning. Proximal jejunum samples were mounted in modified Ussing chambers for transport determinations. Relative to the CONT (7 muA/cm(2)), active glucose transport was greater (P = 0.013) in piglets from sows fed the PFO (30 microA/cm(2)) and DHAGF (40 microA/cm(2)) diets, but not the COCO diet (19 microA/cm(2); pooled SEM = 5). Likewise, jejunum expression of glucose transporter 2 and sodium glucose transporter 1 protein tended (P < 0.10) to be greater in piglets from dams fed the PFO and DHAGF diets, as did AMP-activated protein kinase activity. Piglets' muscle glycogen was greater than in CONT (34 +/- 5.2 mg/g wet tissue) only in piglets from dams fed the DHAGF (46 +/- 5.2 mg/g wet tissue; P < 0.05). These results indicate that (n-3) PUFA, particularly DHA, improves intestinal glucose absorption and muscle glycogen concentrations in newly weaned pigs. These findings may also have important implications for human mothers and infants.

The effects of dietary vitamin E (VE, alpha-tocopherol acetate) and fat supplementation on growth and carcass quality characteristics, oxidative stability of fresh and cooked pork patty in storage, fatty acid profiles of muscle and adipose tissue, and VE concentrations of plasma, muscle, and adipose tissue were studied. Six hundred pigs were allocated to 1 of 6 diets and fed for 63 d in a 3 x 2 factorial design. The dietary treatments included 3 fat levels (normal corn, high oil corn, high oil corn plus added beef tallow) and 2 levels of VE supplementation (40 IU/kg, normal VE supplementation; and 200 IU/kg, high VE supplementation). At 113 kg of BW, 54 pigs were slaughtered as a subsample to evaluate dietary effects on pork quality. Growth performance and meat quality characteristics did not differ (P > 0.05) among treatment groups. The high level of VE supplementation had a beneficial effect on the oxidative stability of pork as indicated by thiobarbituric acid reactive substance (TBARS) values. Lean tissue had lower (P < 0.05) TBARS in the group fed the high VE than in those fed the normal VE level. The TBARS values differed among storage periods (0 to 6 d) and also between fresh and cooked ground ham. Fat type did not significantly affect total saturated and unsaturated fatty acids proportions in the neutral and polar fraction of muscle. Adding VE acetate led to greater (P < 0.05) monounsaturated and total unsaturated fatty acid proportions in neutral lipids of muscle and adipose tissues. Increasing dietary levels of VE acetate increased the concentration of VE in plasma and muscle. These results indicate that dietary VE acetate supplementation increased (P < 0.05) lipid stability and the VE concentration of muscle.

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The effects of the proportion of pigs removed from an established group and subsequent floor space on growth performance during the final 19 d of the finishing period were evaluated using 28 pens of mixed-sex crossbred pigs (mean initial BW = 113.4 +/- 0.57 kg; n = 1,456; approximately 52 pigs per pen). A randomized block design was used with four pig-removal treatments: 1) 0% of pigs removed [Control], 2) approximately 25% of pigs removed, 3) approximately 50% of pigs removed, and 4) approximately 50% of pigs removed and floor and feeder spaces/pig decreased to equal those of Control. A block consisted of four pens with the same number of pigs and sex ratio per pen and with similar initial BW. Pens within blocks were randomly allocated to treatment, and the heaviest animals were removed from Treatments 2, 3, and 4 at the start of the study. Group size and floor space/pig for Treatments 1, 2, 3, and 4 were 52 and 0.65 m(2), 39 and 0.87 m(2), 26 and 1.30 m(2), and 26 and 0.65 m(2), respectively. Each pen contained a six-place feeder that provided 212 cm of total trough space; however, only three-places were accessible to pigs on Treatment 4. Compared with Controls, removing 25 or 50% of pigs resulted in increased (P < 0.001) ADG by 20.6 and 21.0%, ADFI by 10.8 and 7.9%, and G:F by 7.7 and 14.3%, respectively. Average daily gain by pigs on Treatment 4 (50% removal rate and decreased floor and feeder spaces) was greater (P < 0.05) than that of the Controls, but lower (P < 0.05) than that of Treatment 3 pigs (50% removal rate, no adjustment in floor or feeder spaces). No differences were observed among treatments for either morbidity or mortality. These results indicate that removing 25 or 50% of the heaviest pigs from groups of finishing pigs increased growth rate of the remaining pigs, and that the improved performance was only partly due to increased floor and feeder spaces.