Effects of rancidity and free fatty acids in choice white grease on growth performance and nutrient digestibility in weanling pigs.

Two experiments were conducted to determine the effects of rancidity and FFA in choice white grease (CWG) on growth performance and nutrient digestibility in nursery pigs. In Exp. 1,150 crossbred pigs (average initial BW of 6.8 kg and average initial age of 21 d) were used. Treatments (as-fed basis) were a corn-soybean meal-based control with no added fat, 6% CWG, and 6% CWG heated at 80 degrees C, with oxygen gas bubbled through it at 849 mL/min for 5, 7, 9, or 11 d. Peroxide value for the CWG increased as oxidative exposure was increased from 0 to 7 d (i.e., peroxide values of 1, 40, and 105 mEq/kg for d 0, 5, and 7, respectively), but decreased to 1 mEq/kg as the hydroperoxides decomposed after 9 and 11 d of oxidation. Pigs fed the control diet (no added fat) had the same (P = 0.91) overall ADG (d 0 to 35) but lower G:F (P < 0.04) than pigs fed diets with added fat. As for the effects of fat quality, ADG (linear effect, P < 0.01) and ADFI (linear effect, P < 0.001) decreased as the fat was made more rancid. However, there were no changes in digestibility of fatty acids as the rancidity of the fat was increased (P = 0.16), suggesting that the negative effects of rancidity were from decreased food intake and not decreased nutrient utilization. In Exp. 2, 125 crossbred pigs (average initial BW of 6.2 kg and average initial age of 21 d) were used to determine the effects of FFA in CWG on the growth performance and nutrient digestibility in nursery pigs. Treatments (as-fed basis) were a corn-soybean meal-based control with no added fat, 6% CWG, and 6% CWG that had been treated with 872, 1,752 or 2,248 lipase units/g of fat. The FFA concentrations in the CWG were increased from 2% with no lipase added to 18, 35, and 53% as lipase additions were increased. Pigs fed the control diet (no added fat) had the same (P = 0.30) overall ADG (d 0 to 33) but lower G:F (P < 0.01) than pigs fed diets with added fat. There were no effects of FFA concentration on ADG (P = 0.18), and ADFI increased (linear effect, P < 0.04) as FFA concentration in the CWG increased. Fatty acid digestibility was not affected (P = 0.17) by FFA in the diet. In conclusion, our data suggest that as fat is oxidized (especially to peroxide values greater than 40 mEq/kg), ADG and ADFI in nursery pigs will decrease; however, FFA concentrations of at least 53% do not adversely affect utilization of CWG in nursery pigs.

Effects of dietary electrolyte balance on the chemistry of blood and urine in lactating sows and sow litter performance.

One hundred fifty-three sows (average parity of 2.2) were used to determine the effects of dietary electrolyte balance (calculated as mEq/kg of diet for Na + K - Cl) on sows and their litters during lactation. The sows were fed corn-soybean meal-based diets (1.0% lysine, 1.0% valine, 0.95% Ca, and 0.80% P; as-fed basis) starting on d 109 of gestation and throughout the 21-d lactation experiment. Dietary electrolyte balance (dEB) was 0, 100, 200, 350, and 500 mEq/kg (as-fed basis), well above and below the dEB of 185 mEq/kg found in a simple corn-soybean meal-based lactation diet. To achieve the desired dEB, diets had the following: 1) 1.8% HCl (6 N) and 1.06% CaCl2, 2) 1.0% CaCl2, 3) 0.04% NaHCO3, 4) 1.29% NaHCO3, and 5) 2.54% NaHCO3 (as-fed basis). Increasing dEB increased blood pH (linear and quadratic effects, P < 0.001), partial pressure of carbon dioxide (linear effect, P < 0.001), HCO3- concentration (linear and quadratic effects, P < 0.001), and blood base excess (linear and quadratic effects, P < 0.001). However, increased dEB resulted in lower blood concentrations of K (linear and quadratic effects, P < 0.04), Cl (linear and quadratic effects, P < 0.001), and ionized Ca (linear and quadratic effects, P < 0.001). Changing dEB did not affect ADFI; water usage, litter weight gain; sow weight change; sow backfat change; percentages of CP, lactose, and fat in the milk; percentage of sows returning to estrus; days to estrus; and number of pigs born alive in the subsequent litter (P = 0.06). However, piglet survivability to d 10 and overall was greatest with the lower dEB treatments (linear effect, P < 0.05). The pH (linear and quadratic effects, P < 0.001) and colony forming units of total bacteria (linear effect, P < 0.03) in the urine increased as dEB of the diet was increased. In conclusion, dEB had pronounced effects on the physiological status of sows and decreasing dEB below that in a simple corn-soybean meal-based diet decreased bacterial counts in the urine and increased piglet survivability. However, milk composition, sow and litter weights at weaning, and subsequent rebreeding performance of the sows were not affected by dEB.

Enzyme supplementation and particle size of wheat in diets for nursery and finishing pigs.

Three experiments were conducted to determine the effects of enzyme supplementation and particle size of wheat-based diets on growth performance and nutrient digestibility in nursery and finishing pigs. In Exp. 1, 180 weaned pigs (5.7 kg and 21 d of age) were fed diets in a 35-d growth assay without or with a Trichoderma longibrachiatium enzyme product (4,000 units of xylanase activity per gram of product) and with wheat ground to mean particle sizes of 1,300, 600, or 400 microm. Enzyme supplementation had no effect on ADG or gain/feed (P > 0.32), but there was a trend (P < 0.10) for greater digestibility of DM (d 6) in enzyme-supplemented diets. A particle size of 600 microm supported the greatest overall gain/feed (quadratic effect, P < 0.01). An interaction of enzyme supplementation with particle size occurred; gain/feed was improved (P < 0.01) with enzyme supplementation at the coarse (1,300 microm) particle size but not when the wheat was ground to 600 or 400 microm. In Exp. 2, 160 finishing pigs (67 kg) were fed a diet without or with the same enzyme used in Exp. 1 and wheat ground to 1,300 or 600 microm. No interactions occurred between enzyme supplementation and particle size of the wheat (P > 0.15). However, there were trends for greater gain/feed (P < 0.10) during the 67- to 93-kg phase of the experiment and for greater digestibility of DM (P < 0.10) and N (P < 0.07) with enzyme supplementation. When particle size was reduced from 1,300 to 600 microm, gain/feed was improved (P < 0.03) for the 93- to 114-kg phase of the growth assay, and digestibilities of DM (P < 0.02) and N (P < 0.04) were greater. In Exp. 3, 160 finishing pigs (63 kg) were given diets without or with the enzyme product and wheat ground to 600 or 400 microm. Enzyme supplementation improved ADG (P < 0.04) in the 90- to 115-kg phase but otherwise did not affect growth performance, carcass measurements, or stomach lesions. A particle size of 400 microm increased overall gain/feed (P < 0.04), digestibilities of DM and N (P < 0.01), and development of stomach lesions (P < 0.01). In conclusion, pigs did not benefit consistently from enzyme supplementation. However, wheat particle sizes of 600 and 400 microm supported the best overall performance in nursery and finishing pigs, respectively.

Effects of omitting vitamin and trace mineral premixes and(or) reducing inorganic phosphorus additions on growth performance, carcass characteristics, and muscle quality in finishing pigs.

Three experiments were conducted to determine the effects of omitting vitamin and trace mineral premixes and(or) reducing inorganic phosphorus additions to finishing diets on growth performance, carcass characteristics, and muscle quality in pigs. In Exp. 1, a corn-soybean meal-based diet (.70% lysine, .65% Ca, and .55% P) was used as the control. Pigs (n = 128; average initial BW of 85.7 kg) were fed the control diet or the control diet without 1) the vitamin premix, 2) the trace mineral premix, or 3) both premixes. Omitting the premixes had no effect on ADG (P>.39); gain/feed (P>.17); carcass backfat thickness (P>.42); and marbling, color, and firmness of the longissimus muscle (P>.11). In Exp. 2, pigs (n = 128; average initial BW of 86.2 kg) were fed the control diet (.65% Ca and .53% P) used in Exp. 1 and the control diet without 1/3 (.56% Ca and .46% P), 2/3 (.51% Ca and .40% P), or all (.47% Ca and .31% P) of the added monocalcium phosphate (MCP). Omitting up to 2/3 of the MCP increased ADG (quadratic effect, P<.02) and had no effect on meat quality (P>.12), but backfat thickness increased slightly (quadratic effect, P<.02). In Exp. 3, pigs (n = 160; average initial BW of 86.6 kg) were fed the control diet used in Exp. 1 or the control without 1) the vitamin and trace mineral premixes, 2) 2/3 of the MCP, or 3) the premixes and 2/3 of the MCP. Treatment had no effects on ADG (P>.23), gain/feed (P>.94), stomach lesions (P>.37), or serum gamma globulins (P>.08). In conclusion, vitamin and trace mineral premixes and up to 2/3 of the supplemental MCP can be omitted during late finishing (i.e., approximately the final 30 d) to reduce nutrient excesses that increase cost of feeding and nutrients excreted in waste material.

Iron complexation with oral deferoxamine in a swine model.

A controversial therapy in the management of acute iron poisoning is the oral administration of deferoxamine which purportedly complexes unabsorbed iron, exerts protection at the cellular level, and/or enhances the renal elimination of ingested iron. To study the effects of oral deferoxamine on iron absorption, fasted male pigs weighing an average of 10 kg simulated potentially toxic iron overdoses in 12 to 24-mo-old children. A control group of 13 pigs received 60 mg elemental iron/kg via oral gavage followed by 50 ml of distilled water. Serum iron (SI) levels were obtained at 0, 1 2, 4, 6 and 8 h post-iron dosing. The study group of 10 pigs received 60 mg elemental iron/kg po followed by 10 g deferoxamine (1 g/kg). SI levels were obtained at the same intervals. There was no mortality in either group. Statistical differences in SI were noted at 6 and 8 h. Characteristic urine discoloration secondary to deferoxamine was noted at 4 h in the study group. Deferoxamine reduced some peak 51 levels but did not diminish the total absorption of iron.

Effects of particle size and pelleting on growth performance, nutrient digestibility, and stomach morphology in finishing pigs.

The effects of particle size and pelleting on growth performance, carcass characteristics, nutrient digestibility, and stomach morphology were determined using 160 finishing pigs. The pigs were fed a corn-soybean meal-based diet with the corn milled to particle sizes of 1,000, 800, 600, or 400 microns. The diets were fed in meal or pellet form. Pelleting the diets resulted in 5% greater ADG (P < .01) and 7% greater grain/feed (P < .001). Also, pelleting increased digestibilities of DM, N, and GE by 5 to 8% (P < .001). Reducing particle size increased electrical energy required for milling and decreased milling production rates, especially as particle size was decreased from 600 to 400 microns. Reducing particle size of the corn from 1,000 to 400 microns increased gain/feed by 8% (linear effect, P < .001) and digestibility of GE by 7% (quadratic effect, P < .03). Improved nutrient digestibility and lower ADFI resulted in 26% less daily excretion of DM and 27% less daily excretion of N in the feces as particle size was reduced from 1,000 to 400 microns (linear effects, P < .001). Stomach lesions and keratinization increased with reduced particle size (P < .003) and keratinization increased with pelleting (P < .02), although they were unrelated to growth performance (i.e., gain/feed actually improved as lesion scores increased). Considering milling energy, growth performance, stomach morphology, nutrient digestibility, and nutrient excretion, a particle size of 600 microns, or slightly less, is an acceptable compromise for corn in both meal and pelleted diets for finishing pigs.

Reducing particle size of corn in lactation diets from 1,200 to 400 micrometers improves sow and litter performance.

One hundred primiparous sows were used to determine the effects of particle size of corn in lactation diets on sow and litter performance. The sows were fed a corn-soybean meal-based diet with the corn ground to 1,200, 900, 600, or 400 microns. Particle size of corn had no influence on sow BW or backfat loss (P > .30), subsequent weaning-to-estrus interval (P > .40), or percentage of sows returning to estrus (P > .09). However, ADFI was increased (linear effect, P < .04) as particle size was reduced from 1,200 to 400 microns. Pig survivability was not affected (P > .30) but litter BW gain was increased by 11% when sows were fed diets with 400 vs 1,200 microns corn (linear effect, P < .05). Apparent digestibilities of DM, N, and GE were increased by 5, 7, and 7%, respectively, as particle size was reduced from 1,200 to 400 microns (linear effects, P < .001). Intake of DE was increased 14% (13.7 to 15.6 Mcal/d) as corn particle size was reduced from 1,200 to 400 microns. Intakes of digestible DM and N also were increased (11 and 14%, respectively), whereas fecal excretions of DM and N were decreased by 21 and 31%, respectively (linear effects, P < .001). Reducing particle size increased severity of ulceration and keratinization (nonzero correlations of P < .04 and P < .004, respectively) in the esophageal region of the stomach, although the changes were not associated with reduced sow performance.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of dietary buffers on growth performance, nutrient digestibility, and stomach morphology in finishing pigs.

The effects of supplemental alkaline salts on growth performance, blood chemistry, and stomach morphology were determined in two experiments using 248 finishing pigs fed finely ground diets. In Exp. 1, 128 pigs (56 kg average initial BW) were fed a corn-soybean meal-based diet (488-microns mean particle size) for 66 d. Treatments were control and 1, 2, or 3% added NaHCO3 in a randomized complete block design. Average daily gain (linear effect, P < .005), dressing percentage (linear effect, P < .04), and plasma urea N concentration (linear effect, P < .004) decreased as the concentration of NaHCO3 in the diet was increased, but primarily at the 2 and 3% additions. Feed intake, gain/feed, backfat thickness, stomach ulceration score, blood gases (pCO2 and HCO3), and plasma Na and K were not affected by treatment (P > .11). In Exp. 2, 120 pigs (55 kg average initial BW) were fed a pelleted wheat-soybean meal-based diet (355-microns mean particle size) during a 64-d growth assay. Treatments were 1) control, 2) 1% NaHCO3, and 3) 1% KHCO3. Average daily gain, ADFI, gain/feed, backfat thickness, stomach keratinization score, blood pCO2, plasma urea N, and digestibilities of DM and N were not affected by treatment (P < .15). However, addition of NaHCO3 and KHCO3 tended to decrease (P < .10) the incidence of ulcers and increased (P < .05) the concentration of blood HCO3- and digestibility of GE. These data indicate that 1% addition of either NaHCO3 or KHCO3 may help to reduce the severity of gastric ulcers in finishing pigs without adversely affecting growth performance or nutrient digestibility.

Optimum particle size of corn and hard and soft sorghum for nursery pigs.

A total of 240 weanling pigs (22 d of age and 5.3 kg average BW) were used to determine the effects of particle size of corn and two sorghum hybrids on diet processing, growth performance, apparent digestibility of nutrients, and morphology of the stomach and intestines in weanling pigs. Treatments were corn, hard endosperm sorghum, and soft endosperm sorghum milled to particle sizes (geometric mean) of 900, 700, 500, and 300 microns, in a 3 x 4 factorial arrangement. All diets were pelleted and the pigs were allowed to consume feed and water on an ad libitum basis. As particle size was reduced, production rate (tons/hour) decreased and energy required to mill (kilowatt hours/ton) increased. Corn required more energy to mill and had a lower production rate than the sorghums. For d 0 to 14, ADG and gain/feed increased linearly (P < .009 and P < .002, respectively) as particle size was decreased to 300 microns. However, there was a grain source x particle size interaction; pigs fed corn responded to particle size reduction more than pigs fed the sorghums (P < .04). For d 0 to 35, pigs fed diets with corn grew 23% faster and were 6% more efficient (P < .001) than pigs fed diets with sorghum. Gain/feed responded quadratically to reduction of particle size (P < .01), with maximum gain/feed at 500 microns for all grains. Lowest cost of gain (including milling and ingredient costs) was achieved at 500 to 700 microns for corn and 500 microns for the hard and soft sorghums. These data suggest that response to reducing particle size is greatest during the first 2 wk postweaning and that optimal particle size for corn and sorghums increases with age of nursery pigs.

The effects of porcine somatotropin and dietary lysine on growth performance and carcass characteristics of finishing swine fed to 105 or 127 kilograms.

One hundred twenty barrows (initially 59 kg) were used to determine the effects of dietary lysine and porcine somatotropin (pST) on growth performance and carcass characteristics of finishing pigs fed to heavy market weights (127 kg). Pigs were injected daily with either 4 mg of pST or a placebo and fed diets containing either .8, 1.0, 1.2, or 1.4% lysine in a 2 x 4 factorial arrangement. Performance data were collected and evaluated for the weight ranges: 59 to 105, 105 to 127, and 59 to 127 kg. In addition, daily accretion rates of protein (DPA), lipid (DLA), moisture, and ash were determined by slaughtering six randomly selected pigs at the start of the experiment, then one pig per pen when pigs reached mean weights of 105 and 127 kg. Pigs injected with pST had greater (P < .05) ADG than control pigs at all weight ranges. Increased dietary lysine had no effect (P > .20) on ADG during the entire trial (59 to 127 kg). Although control pigs showed no increase in ADG with increasing lysine, ADG of pST-treated pigs tended to increase. This resulted in a pST x lysine interaction (P < .07) for ADG from 59 to 127 kg. Feed consumption decreased (P < .05) in pigs from 59 to 105 kg and 59 to 127 kg with pST treatment and with increasing dietary lysine. Feed conversion (G/F) was improved (P < .01) by pST administration and a tendency for a pST x lysine interaction (P < .12) was observed. At 105 kg, average backfat thickness, kidney fat, longissimus muscle area, and DPA were unaffected by dietary lysine but were improved by pST treatment (P < .01). At a slaughter weight of 127 kg, average backfat thickness decreased and DPA increased (linear, P < .05) with increasing dietary lysine and pST treatment (P < .01). Longissimus muscle area was increased and DLA was decreased (P < .01) by injections of pST but both were unchanged by dietary lysine. These data indicate that growth performance and carcass characteristics at 105 and 127 kg were improved by daily administration of 4 mg of pST. At both slaughter weights, increasing dietary lysine resulted in increased carcass leanness (increased carcass protein and decreased carcass lipid). Although increasing lysine did not improve overall (59 to 127 kg) ADG and feed efficiency, pST-treated pigs showed a greater response to increasing dietary lysine. The data indicate that pST-treated pigs (4 mg/d) require approximately 28 g/d of lysine.

Interrelationships between porcine somatotropin and dietary lysine on growth performance and carcass characteristics of finishing swine.

Seventy-two barrows (initial weight = 57.1 kg) were used to determine the interrelationship between porcine somatotropin (pST) and dietary lysine and their effects on growth performance and carcass characteristics. Pigs were injected daily in the extensor muscle of the neck with either 4 or 8 mg of pST and fed a pelleted corn-soybean meal-sesame meal diet (.8% lysine; 17.8% CP) or diets containing 1.0, 1.2, or 1.4% lysine provided by additions of L-lysine.HCl (2 x 4 factorial arrangement). Control pigs (placebo injection) received the .8% lysine diet. All diets were formulated to contain > or = 200% of current recommendations for other amino acids, vitamins, and minerals. A tendency for a pST x lysine interaction was observed for cumulative ADG (P < .15) and feed conversion (G/F; P < .05). Average daily gain and G/F were improved by increasing dietary lysine level in pigs injected with 4 mg/d of pST; however, pigs injected with 8 mg/d of pST had greater improvements in cumulative ADG and G/F with added lysine. Feed intake was reduced (quadratic, P < .10) as dietary lysine level and pST dosage increased. Increasing pST dosage and dietary lysine increased (linear, P < .05) longissimus muscle area and decreased backfat thickness. Trimmed ham and loin weights were increased (linear, P < .10) by pST dosage. Chemical composition of samples taken from the loin, ham, and belly indicated increased moisture and CP and decreased lipid content as pST dosage and dietary lysine level increased (quadratic, P < .05). Shear force values from loin and semimembranosus increased with increasing lysine level (quadratic, P < .01) and pST dosage (linear, P < .05); however, these differences were not detected by sensory analysis (P > .20). Plasma urea concentrations on d 28 decreased with increasing lysine level (quadratic, P < .05), and plasma lysine concentrations increased (linear, P < .01). Based on the pST x lysine interaction for ADG and G/F, these data suggest that the lysine level needed to maximize growth performance and carcass characteristics may be proportional to the pST dosage provided. Growth and carcass characteristics were maximized by dietary lysine intakes of 27 to 32 and > or = 36 g/d for pigs injected with 4 and 8 of mg/d of pST, respectively.

Porcine somatotropin and dietary lysine influence bone mineralization and mechanical properties of bones in finishing swine.

The femur, a rib, and a third metacarpal were collected from 108 barrows (initial weight = 57 kg) and analyzed to determine the effects of porcine somatotropin (pST) and dietary lysine on bone mineralization and mechanical properties. In Exp. 1, pigs were injected daily with 4 mg of pST and fed diets containing 1.0% Ca and .9% P and either .6, .8, 1.0, 1.2, or 1.4% lysine. Control pigs (placebo injection) received the .6% lysine diet. Bone wall thickness (BWT) of the femur increased (linear, P < .05) but ash content decreased (linear, P < .10) as dietary lysine level increased. Stress and ash content of the rib also decreased (linear, P < .05) with increasing dietary lysine level. In Exp. 2, pigs were injected with either 4 or 8 mg/d of pST and fed diets containing 1.1% Ca and 1.0% P and either .8, 1.0, 1.2, or 1.4% lysine. Control pigs received the .8% lysine diet. Increasing pST dosage increased BWT of the femur (linear, P < .10) but decreased ash content (linear, P < .10). In the rib, increasing pST dosage reduced stress, modulus of elasticity (linear, P < .10), and ash content (linear, P < .01). Increasing lysine level resulted in increased BWT of the femur and decreased ash content of rib, femur, and metacarpal (linear, P < .10). These data indicate that pST administration in conjunction with increasing lysine levels decreases bone ash content but increases BWT of finishing pigs.

The effects of porcine somatotropin and dietary lysine on growth performance and carcass characteristics of finishing swine.

Seventy-two finishing pigs (initial weight = 57.6 kg) were utilized to determine the effects of porcine somatotropin (pST) and dietary lysine level on growth performance and carcass characteristics. Pigs were injected daily with 4 mg pST in the extensor muscle of the neck and fed either a pelleted corn-sesame meal diet (.6% lysine, 17.8% CP) or diets containing .8, 1.0, 1.2 or 1.4% lysine provided by additions of L-lysine.HCl. All diets were formulated to contain at least twice the required amounts of other amino acids. Control pigs received a placebo injection and the .6%-lysine diet. Increasing levels of dietary lysine resulted in increased ADG and improved feed conversion (quadratic, P less than .01) for pST-treated pigs. The calculated daily lysine intake was 16.6, 13.6, 19.6, 25.1, 29.6 and 33.6 g for the control and pST-treated pigs fed .6, .8, 1.0, 1.2 and 1.4% lysine, respectively, over the entire experiment. Breakpoint analysis indicated that cumulative ADG and feed conversion were optimized at 1.19 and 1.22% lysine, respectively. Longissimus muscle area and trimmed ham and loin weights increased as dietary lysine was increased among pST-treated pigs (quadratic, P less than .01). Breakpoint analysis indicated that 1.11% lysine maximized longissimus muscle area, whereas trimmed ham and loin weights were maximized at .91 and .98% lysine, respectively. Adjusted backfat thickness was not affected by dietary lysine, but pST-treated pigs had less backfat (P less than .05) than control pigs did. Percentage moisture of the longissimus muscle increased (linear, P less than .05), as did percentage CP (quadratic, P less than .05), whereas fat content decreased (linear, P less than .05) as lysine level increased. Similar trends in composition were observed for muscles of the ham (semimembranosus, semitendinosus, and biceps femoris). Shear-force values from the longissimus and semimembranosus were lowest for control pigs, but they increased as dietary lysine level increased among pST-treated pigs. Sensory panel evaluations indicated that juiciness and tenderness decreased (linear, P less than .05) as dietary lysine level increased. Plasma urea concentrations decreased linearly (P less than .01) on d 28 as lysine level increased, whereas plasma lysine and insulin were increased (quadratic, P less than .01). Plasma glucose and free fatty acid concentrations on d 28 tended to increase (quadratic, P less than .10) with increasing dietary lysine level.(ABSTRACT TRUNCATED AT 400 WORDS)

An evaluation of barley in starter diets for swine.

Four growth trials and one digestibility trial were conducted to determine the effects of substituting barley for grain sorghum in weanling pig diets on pig performance and nutrient digestibility. Experiments 1 and 2 were 35-d growth trials in which barley was substituted for gain sorghum at levels of 0, 10, 20, 30 and 40% of the diet. Average daily gain (ADG), average daily feed intake (ADFI) and feed conversion (F/G) were not affected by dietary barley level (P greater than .50). Experiment 3 was a digestibility trial conducted to determine the apparent digestibility of dry matter (DMD), gross energy (GED), and N (ND) and percentage of N retained (%NRT) of pigs fed the 0, 20 and 40% barley diets. As dietary barley level increased, DMD and GED decreased linearly (P less than .05), whereas %NRT increased linearly (P less than .10). Apparent N digestibility was not affected by dietary treatment (P greater than .12). Experiments 4 and 5 were 35-d growth trials with treatments arranged in a 2 x 3 factorial design to determine the effects of barley particle size (fine, 635 microns or medium, 768 microns) and dried whey level (0, 10 or 20%) on pig performance. Average daily gain and ADFI increased linearly (P less than .01) as whey level increased. Pigs fed diets containing fine-ground barley grew faster and were more efficient (P less than .05) than those fed medium-ground barley diets.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of feeding systems on social and feeding behavior and performance of finishing pigs.

Two experiments were conducted to study the effects of feeding systems on feeding behavior, aggression, social ranks and average daily gain (ADG) of pigs. In Exp. 1, feed was delivered during the day from 1100 to 1400 and at night from 2300 to 0200. One pen containing 10 barrows and 10 gilts was used. Correlation coefficients were calculated between pairs of traits. In Exp. 2, four feeding systems were tested using similar group composition as in Exp. 1. Two feeding systems were ad libitum, offering either dry or wet feed; the other two used time-restricted feeding from 0900 to 1100 and from 1600 to 1800, but with water supplied either ad libitum or time-restricted. Analyses of variance were used to test feeding system effects; correlation coefficients were calculated for pairs of traits. Results of Exp. 1 indicated that pigs displayed predominantly daytime activities. Frequency of aggressive acts were correlated significantly with feeding frequency (r = .48), time to first feeding (r = -.50) and ADG (r = .56). In Exp. 2, pigs on time-restricted feeding with ad libitum water had significantly depressed ADG and reduced feed intake. A possible association between time-restricted feeding and water intake is postulated. Feeding behavior, aggression and social rank were associated with ADG in time-restricted systems but not in ad libitum systems. There was a tendency in time-restricted-fed pigs for the more aggressive pigs to perform more feeding activities, to rank higher in the social order, and to gain faster.

Efficacy of furazolidone in grower diets on subsequent performance of swine--a cooperative study.

Nine experiments were conducted at three stations to evaluate the efficacy of furazolidone as a growth promoter in diets for young swine and to determine if an early growth response is maintained after the additive is withdrawn from the diet. A total of 528 pigs (24 replications, 132 pigs/treatment) initially averaging 12 kg body weight were fed a nonmedicated basal diet or a diet with 110 ppm furazolidone for 5 wk, 165 ppm furazolidone for 3 wk or 220 ppm furazolidone for 2 wk. After withdrawal of furazolidone, the basal diet was fed to the end of the test, at which time the pigs averaged 93 kg. During the initial 2-wk period, pigs fed furazolidone gained 15.4% faster (P less than .001) and required 8% less (P less than .001) feed per unit of gain than control pigs fed the nonmedicated diet. At 5 wk, pigs previously fed furazolidone gained 8.4% faster (P less than .001) and 4.5% more efficiently (P less than .001) than controls. By 10 wk, pigs previously fed furazolidone maintained a slight advantage in growth rate over controls (2.6%, P less than .10), but feed/gain responses were similar for the two groups. By the end of the experiment, the early growth response from furazolidone was completely lost. Although there were differences in growth responses among stations, the treatment response patterns were similar for each station, with no evidence of a treatment X station interaction.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of gleptoferron with iron dextran for anemia prevention in young pigs.

Gleptoferron, a sterile aqueous colloidal solution of beta-ferric oxyhydroxide and dextran glucoheptonic acid, was compared with iron dextran for the prevention of Fe deficiency anemia in young pigs. Using 26 litters, pigs (within each litter) were randomly allotted to one of three treatments: 1) control (no Fe), 2) iron dextran (200 mg) and 3) gleptoferron (200 mg). Blood was collected at 0, 10, 21 and 50 d post-treatment for red blood cell count (RBC), hematocrit (HCT), hemoglobin (HGB) concentration, serum Fe concentration (Fe) and serum Fe-binding capacity (IBC). At 21 d, 30 pigs (one pig/treatment from each of 10 litters) were killed to determine milligrams nonheme Fe (NHFe) in liver and spleen, bile IBC and concentrations of bile and fecal Fe. There were no differences (P greater than .05) between Fe sources in 3- or 8-wk body weight or in any of the blood or tissue characteristics. In contrast, control pigs gained less (P less than .05) weight and had lower (P less than .05) RBC, HGB, HCT, serum Fe and liver and spleen NHFe than those that received iron dextran or gleptoferron. Serum IBC was greater (P less than .05) for the control than for Fe-treated pigs. These results demonstrate that the iron from iron dextran and gleptoferron is used with similar efficiency for anemia prevention in young pigs.

Reproductive development in young boars exposed to sexually mature, nonpregnant sows and gilts.

Thirty Yorkshire boars were allotted by litter to one of two treatment groups. Fifteen boars were reared, from 14 to 22 wk of age, in fenceline contact with mature sows and gilts that were randomly exhibiting estrus. Fifteen littermates of these boars, reared without exposure to females, served as controls. Boar-to-boar sexual behaviors were observed 1 hour daily from 16 to 22 wk of age. At ages 14 to 30 wk, boars were weighed at 4-wk intervals. Five boars per treatment were slaughtered when 22 wk old and twelve others (six per treatment) when 30 wk old. Vesicular gland, bulb of the prostate gland, bulbourethral gland, and each testis, cauda epididymis, and combined caput and corpus epididymis were closely trimmed and weighed. Left cauda epididymal sperm and left testis elongated spermatids were determined by homogenization and hemacytometer counting. At 26, 30, and 38 wk of age, boars were tested for mating efficiency by exposure to an estrous gilt. Boars exposed to females tended to be lighter at 22 wk and were lighter at 30 wk (P<.05). Total male-to-male sexual acts from 16 to 22 wk were correlated with mating-efficiency score at 26 and 30 wk (r = .69 and .68, respectively; (P<.05)). Correlation between testicle size and total testicle elongated spermatids was high at 30 wk of age (r = .92; P<.001). Results indicated that exposing young boars to mature females had limited effects on the boars' reproductive development; however, there were strong indications of a relationship between boar behavior during rearing and postpuberal mating performance.