Impact of supplement withdrawal and wheat middling inclusion on bone metabolism, bone strength, and the incidence of bone fractures occurring at slaughter in pigs.

The objective of this study was to determine if supplement withdrawal (omission of dietary vitamin and trace mineral premixes and 2/3 of inorganic P) 28-d preslaughter and the feeding of wheat middlings (dietary concentrations of 5, 15, or 30% from weaning to 16 kg, 16 to 28 kg, and 28 kg to slaughter, respectively) affect bone metabolism, bone strength, bone density, and the incidence of bone fractures at slaughter in pigs. Crossbred barrows (n = 64) were assigned to a 2 x 2 factorial arrangement of treatments (with or without supplement withdrawal, and with or without wheat middlings). Serum was collected on d 0, 14, and 27 of the preslaughter withdrawal period to determine changes in the concentrations of osteocalcin, an indicator of bone formation, and pyridinoline, an indicator of bone resorption. The serum osteocalcin and pyridinoline concentrations on d 14 and 27 were analyzed as change from the d-0 concentration. At slaughter, radiographs of the lumbar vertebrae and of the right and left femurs were taken to determine the incidence of bone fractures. Third metacarpal bones were analyzed for bone mineral density, peak load, ultimate shear stress, and percent ash. Supplement withdrawal increased (P < 0.05) serum osteocalcin and pyridinoline concentrations, indicating an increase in osteoblast activity and bone resorption. Supplement withdrawal decreased (P < 0.01) bone mineral density, peak load, ultimate shear stress, and percent ash of the metacarpal bones. Dietary wheat middling inclusion did not alter bone quality. Neither supplement withdrawal nor wheat middling inclusion affected the incidence of bone fractures at slaughter. The results of this study indicate that removing inorganic P, vitamin premix, and trace mineral premix for 28 d preslaughter increases bone turnover and decreases bone quality.

Effects of mannan oligosaccharide and an antimicrobial product in nursery diets on performance of pigs reared on three different farms.

The objective of this experiment was to compare the effects of dietary mannan oligosaccharide (MOS) and a feed-grade antimicrobial (AM) on growth performance of nursery pigs reared on three different farms (A and B were large-scale commercial farms, and C was located at Michigan State University). On all farms, production was continuous flow by building, but all-in/all-out by room. Within each nursery facility, all pigs on the experiment were in one room. Pigs (Farm A, n = 771, weaning age = 18.4 d; Farm B, n = 576, weaning age = 19.0 d; Farm C, n = 96, weaning age = 20.6 d) were blocked (within farm) by BW and sex and allotted randomly to dietary treatments arranged in a 2 x 2 factorial. The two factors were 1) with and without MOS (0.3% in Phase I, 0.2% in Phases II, III, and IV; as-fed basis) and 2) with and without AM (110 mg of tylosin and 110 mg of sulfamethazine/kg of diet in all phases; as-fed basis). The four nursery phases were 4, 7, 14, and 17 d, respectively. With 35, 20, and 4 pigs per pen on Farms A, B, and C, respectively, space allowances per pig were 0.29, 0.26, and 0.56 m2. Across all farms, the addition of AM and MOS plus AM increased (P < 0.05) ADG (368, 406, and 410 g/d for control, AM, and MOS plus AM, respectively and increased ADFI (661, 703, and 710 g/d for control, AM, and MOS plus AM, respectively) for the entire 42-d experiment. The addition of MOS also increased ADG (P < 0.05) from d 0 to 42 of the experiment (394 g/d). Performance differed depending on farm (P < 0.01). Antimicrobial did not affect growth performance on Farm B, but it increased (P < 0.05) ADG on Farms A and C, ADFI on Farm A, and G:F on Farm C. Growth improvements with MOS on Farms A and B were not significant; however, pigs on Farm C fed MOS had greater (P < 0.05) ADG, ADFI, and G:F than controls. The results of this study suggest that MOS may be an alternative to tylosin and sulfa-methazine as a growth promotant in nursery diets.

Impact of vitamin and mineral supplement withdrawal and wheat middling inclusion on finishing pig growth performance, fecal mineral concentration, carcass characteristics, and the nutrient content and oxidative stability of pork.

A study was conducted to determine if supplement withdrawal (omission of dietary vitamin and trace mineral premixes and a two-thirds reduction in dietary inorganic phosphorus) for 28 d preslaughter and the feeding of wheat middlings (dietary concentrations of 5, 15, and 30% from weaning to 16, 16 to 28, and 28 kg to slaughter, respectively) affect growth performance, carcass characteristics, and fecal mineral concentrations ofthe pig, as well as the nutrient content and oxidative stability of the longissimus dorsi muscle. Crossbred pigs (n = 64) were blocked by weight and assigned to one of four dietary treatments in a 2 x 2 factorial design (with or without supplement withdrawal, and with or without wheat middlings). Supplement withdrawal and wheat middling inclusion did not influence average daily gain (ADG), average daily feed intake, gain/feed, or carcass traits, except for a decrease (P < 0.01) in the ADG of pigs from 28 to 65 kg when fed wheat middlings. Supplement withdrawal decreased (P < 0.01) fecal Ca, P, Cu, Fe, Mn, and Zn concentrations. In diets containing full vitamin and mineral supplementation, wheat middling inclusion decreased (P < 0.01) fecal Ca, Cu, Fe, and Zn concentrations and increased (P < 0.01) fecal Mn. Supplement withdrawal decreased (P < 0.05) concentrations of riboflavin, niacin, and P in the longissimus dorsi muscle, but did not affect longissimus dorsi thiamin, vitamin E, Fe, Cu, Zn, and Ca concentrations. Inclusion of wheat middlings increased (P < 0.04) longissimus dorsi thiamin, niacin, riboflavin, and vitamin E concentrations and decreased (P < 0.04) Cu concentrations. However, wheat middling inclusion did not affect (P > 0.05) longissimus dorsi Ca, P, Fe, and Zn concentrations. Dietary treatment did not affect either Cu/Zn superoxide dismutase or glutathione peroxidase activity in the longissimus dorsi. The results from this study indicate that supplement withdrawal and dietary wheat middling inclusion alter pork nutrient content and fecal mineral concentration, but not the oxidative stability of pork.