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 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.

A replicated trial of 3 X 3 Latin square design was conducted with growing pigs (about 29 kg initially) to determine the effects of different levels of feed intake on nutrient digestibilities determined near the end of the small intestine and over the total digestive tract. Pigs were fiftted with simple T-cannula. Feeding levels were ad libitum (AL) and limit-fed (4.5 or 3% of body weight/d). A 16% sorghum-soybean diet was used. Limit-fed pigs were fed at 12-h intervals and water was limited to 2 liters/kg of diet; AL pigs received water ad libitum. Consumption by pigs fed ad libitum averaged 6% of body weight/d. Neither feeding method nor level greatly affected nutrient digestibility measured at the end of the small intestine, but values tended to decrease as feeding level decreased. Comparisons of nutrient digestibility between AL and limit-fed pigs ranged from 2.9 to .7 percentage units, with only N (P less than .10) and methionine (P less than .05) reaching significance. Differences between 4.5 and 3% were slightly larger, ranging from 4.3 to -.2 percentage units, with differences for dry matter, N, gross energy and several amino acids reaching significance (P less than .10 or P less than .05). Measured over the total tract, observed differences among feeding levels were again small, but the trend was reversed, with digestibilities increasing as feeding level decreased. The estimated percentage of ingested nutrients that disappeared in the large intestine increased as feeding level decreased.(ABSTRACT TRUNCATED AT 250 WORDS)

The acceptibility of bacon produced from swine fed diets containing elevated levels of oleic acid was evaluated. Slicing yields and sensory scores for overall palatability and flavor quality were lower for bacon produced from swine fed canola oil (P < 0.05). A higher percentage of panelists detected off-flavors in canola oil bacon than in bacon produced from swine fed safflower oil, sunflower oil, animal fat or a typical corn-soybean meal diet (P < 0.05).

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.

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.

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.

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.