Evaluation of methods to reduce bacteria concentrations in spray-dried animal plasma and its effects on nursery pig performance

Four experiments with 1,040 weanling pigs (17 +/- 2 d of age at weaning) were conducted to evaluate the effects of spray-dried animal plasma source, drying technique, and methods of bacterial reduction on nursery pig performance. In Exp. 1, 180 barrows and gilts (initial BW 5.9 +/- 1.8 kg) were used to compare effects of animal plasma, animal plasma source, drying technique (spray-dried or freeze-dried), and plasma irradiation in nursery pig diets. From d 0 to 10, pigs fed diets containing irradiated spray-dried animal plasma had increased ADG and ADFI (P < 0.05) compared with pigs fed diets containing nonirradiated spray-dried animal plasma. Pigs fed irradiated animal plasma Sources 1 and 2 were similar in ADG and ADFI, but pigs fed animal plasma Source 1 had greater ADG (P < 0.05) than pigs fed animal plasma Source 2 and pigs not fed plasma. Pigs fed freeze-dried animal plasma had growth performance similar (P > 0.36) to pigs fed spray-dried animal plasma. Overall (d 0 to 24), pigs fed irradiated spray-dried animal plasma were heavier (P < 0.05) than pigs fed no animal plasma, whereas pigs fed nonirradiated spray-dried plasma were intermediate. In Exp. 2, 325 barrows and gilts (initial BW 5.8 +/- 1.7 kg) were used to compare the effects of irradiation or formaldehyde treatment of animal plasma and formaldehyde treatment of the whole diet. Pigs fed diets containing irradiated animal plasma had greater ADG (P < 0.05) than pigs fed nonirradiated plasma. Pigs fed formaldehyde-treated plasma had greater ADG and ADFI (P < 0.05) than pigs fed diets with either nonirradiated plasma or whole diet treated with formaldehyde. In Exp. 3 (360 barrows and gilts; initial BW 6.3 +/- 2.7 kg) and Exp. 4 (175 barrows and gilts; initial BW 6.1 +/- 1.7 kg), the irradiation of feed (high bacteria) and food-grade (low bacteria) animal plasma in nursery pig diets was examined. Pigs fed irradiated feed-grade plasma Product 2 had increased ADG (P < 0.05) compared with pigs fed nonirradiated plasma Product 2 and pigs fed the control diet without plasma. In Exp. 3 and 4, pigs fed irradiated food-grade plasma had growth performance similar to pigs fed nonirradiated food-grade plasma (P > 0.12). These studies indicate that bacterial reduction of feed-grade, but not food-grade animal plasma, improves nursery pig performance.     

Growth performance, diet apparent digestibility, and plasma metabolite concentrations of barrows fed corn-soybean meal diets or low-protein, amino acid-supplemented diets at different feeding level

Two experiments, each with 36 barrows with high-lean-gain potential, were conducted to evaluate apparent nutrient digestibilities and performance and plasma metabolites of pigs fed corn-soybean meal diets (CONTROL) and low-protein diets. The low-protein diets were supplemented with crystalline lysine, threonine, tryptophan, and methionine either on an ideal protein basis (IDEAL) or in a pattern similar to that of the control diet (AACON). Amino acids were added on a true ileally digestible basis. The initial and final BW were, respectively, 31.5 and 82.3 kg in Exp. 1 and 32.7 and 57.1 kg in Exp. 2. In Exp. 1, the CONTROL and IDEAL diets were offered on an ad libitum basis or by feeding 90 or 80% of ad libitum intake. Pigs were fed for 55 d. In Exp. 2, the CONTROL, IDEAL, and AACON diets were offered on an ad libitum basis or by feeding 80% of the ad libitum intake. Pigs were fed for 27 d. Pigs fed the CONTROL diet had greater (P < 0.05) ADG and feed efficiency (G/F) than pigs fed the IDEAL (Exp. 1 and 2) and AACON diets (Exp. 2). As the level of feed intake decreased, ADG decreased (P < 0.05), but G/F tended to improve (P < 0.10) for pigs fed 90% of ad libitum in Exp. 1 and for pigs fed 80% of ad libitum in Exp. 2. In Exp. 1, the apparent total tract digestibilities of DM and energy were greater (P < 0.01) for pigs fed the IDEAL diet than for pigs fed the CONTROL diet. In Exp. 2, the apparent total tract digestibility of protein was greatest in pigs fed the CONTROL diet (P < 0.05) and was greater (P < 0.05) in pigs fed the AACON diet than in pigs fed the IDEAL diet. Plasma urea concentrations were lower in pigs fed the IDEAL diet than in pigs fed the CONTROL diet, regardless of feeding level. For pigs fed the CONTROL diet, plasma urea concentrations were lower when feed intake was 80% of ad libitum (diet level, P < 0.01). In summary, pigs fed the IDEAL and the AACON diets gained less and had lower plasma urea concentrations than pigs fed the CONTROL diet. Based on these data, it seems that the growth potential of pigs fed the IDEAL and AACON diets may have been limited by a deficiency of lysine, threonine, and(or) tryptophan and that the amino acid pattern(s) used was not ideal for these pigs.     

Effect of group size and feeder type on growth performance and feeding patterns in growing pigs

The effects of four group sizes (2, 4, 8, and 12 pigs per pen) and two single-space feeder types (conventional and electronic feed intake recording equipment [FIRE]) on feed intake, growth performance, and feeding patterns were determined in growing pigs over a 4-wk period. A total of 416 hybrid pigs (barrows and gilts) were grown from 26.5 (SD = 1.6) to 47.8 (SD = 2.7) kg BW and given ad libitum access to a corn-soybean meal-based diet (17.4% CP; 0.9% lysine; 3,298 kcal ME/kg). The floor space allowance was 0.9 m2/pig for all treatments. Pigs using the electronic feeders had similar growth rates but lower feed intakes (P < 0.01) and higher gain:feed ratios (P < 0.01) compared to those using the conventional feeders. Barrows compared to gilts had higher growth rates (P < 0.05), numerically higher (P > 0.05) ADFI, and similar feed efficiency and feeding pattern. Feed intakes and growth rates were lowest (P < 0.05) for groups of 12 pigs but gain:feed ratio was not affected by group size. Daily feeder occupation time per pig was lower (P < 0.01) for groups of 12 than for groups of 2 or 4 pigs, and feed consumption rate was higher (P < 0.01) for groups of 12 than for groups of 4 pigs. The proportion of time spent eating was lower (P < 0.01) and the proportion of time spent standing was higher (P < 0.01) for pigs in groups of 12 compared to groups of 2. Correlations between ADG and ADFI and feed intake per visit were 0.29 and 0.30, respectively (P < 0.01), between ADG and ADFI and feed consumption rate were 0.27 and 0.31, respectively (P < 0.01), and between ADFI and feeder occupation time per day were 0.33 (P < 0.01). This study suggests that, in growing pigs given access to a single feeder, changes in feeding behavior with increasing group size were not sufficient to maintain feed intake and growth rate.     

Effects of dietary fat on growth performance and carcass characteristics of growing-finishing pigs reared in a commercial environment.

We conducted two experiments to evaluate the effects of added choice white grease on performance and carcass merit of barrows and gilts reared under commercial conditions. Pigs were housed either 20 (Exp. 1) or 25 (Exp. 2) per pen and were provided 0.67 m2 of pen space per pig. Diets were based on corn and soybean meal and fed in a meal form. The proportion of soybean meal was increased in diets with added fat to maintain the same calorie:lysine ratio in all diets within a weight phase. In Exp. 1, 480 pigs were fed diets with 0, 2, 4, or 6% fat. Total lysine contents of the control diets were 1.21, 0.88, and 0.66% during the weight phases 36 to 59, 59 to 93, and 93 to 120 kg, respectively. Gain:feed was increased linearly (P < 0.01) due to fat addition in all weight intervals and over the total experiment. The effect of added fat on ADG was not consistent among the weight phases; a linear (P < 0.01) improvement was found from 36 to 59 kg, but no effect was found during the heavier weight phases. Over the total experiment, however, ADG was improved (P < 0.01) linearly. Carcass traits were not affected by treatment. Experiment 2 used 900 pigs to evaluate possible carryover effects on performance and carcass merit from feeding 6% fat. The experiment was divided into four phases: 25 to 45, 45 to 70, 70 to 90, and 90 to 115 kg; lysine contents of the control diets fed in each phase were 1.23, 1.05, 0.81, and 0.63%, respectively. The six treatments consisted of no added fat throughout the experiment or 6% added fat fed from 25 to 45 kg, 25 to 70 kg, 25 to 90 kg, 25 to 115 kg, or 45 to 70 and 90 to 115 kg. Carryover effects for ADG and G:F (P < 0.07) were found for the 90- to 115-kg interval and for ADFI and ME intake (P < 0.05) for the 45- to 70- and 70-to 90-kg intervals. When fat was added in the previous weight interval, ADG and G:F were improved and ADFI and ME intake were decreased in the subsequent weight interval. Pigs fed fat from 25 to 115 kg had more (P < 0.05) backfat and lower (P < 0.05) carcass leanness than pigs on the other treatments. These data suggest that fat can be added or removed from diets of growing-finishing pigs without any detrimental carryover effects. In fact, the positive carryover effect on ADG and G:F from 95 to 115 kg suggests that feeding fat from 25 to 95 kg will maximize performance over the total growing-finishing period but minimize any detrimental effects of added fat on carcass leanness.     

Effects of feeding schedule on body condition, aggressiveness, and reproductive failure in group-housed sows

A total of 208 sows and 288 gilts (PIC line C29) were used to determine the influence of feeding frequency (2 vs. 6 times/d, floor fed) on performance and welfare measurements on a commercial sow farm. Treatments consisted of feeding similar amounts of feed to each sow (2.5 kg) or gilt (2.05 kg) over 2 (0700 and 1530) or 6 times daily (0700, 0730, 0800, 1530, 1600, and 1630). There were 8 sows or 12 gilts in each pen. Gilts and sows were moved to pens 1 to 4 d after breeding. In sows, there were no differences (P > 0.10) in ADG, backfat change, or variation in BW. There was a trend (P < 0.08) for sows fed twice daily to farrow more total pigs born, but number born alive or other reproductive performance traits were not different (P > 0.10) among treatments. Sows fed 6 times per day had increased vocalization during the morning (P < 0.07) and afternoon (P < 0.01) feeding periods compared with sows fed twice daily. Sows fed twice daily had more skin (P < 0.01) and vulva (P < 0.04) lesions as well as a small increase in feet and leg (P < 0.01) and hoof (P < 0.02) problems. In this commercial facility, the standard management protocol required moving gilts to a different gestation facility on d 42. On d 42, two pens of gilts with similar breeding dates and treatment were combined and moved to another facility with larger pens until farrowing. Gilts fed 6 times daily had a tendency for greater ADG (P < 0.07) from d 0 to 42 and a tendency for greater (P < 0.09) backfat on d 42. After movement to the larger groups from d 42 to farrowing, ADG was similar (P > 0.10) for gilts fed 2 or 6 times daily. Gilts fed twice daily had lower BW variation at d 42 (P < 0.04) and tended to at farrowing (P < 0.10). In gilts, there were no differences (P > 0.10) for reproductive performance, skin and vulva lesions, and feet and leg scores. In conclusion, there were few growth, farrowing, or aggression differences among gilts fed 2 or 6 times daily. This suggests that either feeding method is suitable for group-housed gilts. Among sows, feeding frequency resulted in few growth or farrowing performance differences. Feeding 6 times daily resulted in a small but significant reduction in skin and vulva lesions and structural problem scores while increasing vocalization. Increasing the feeding frequency from 2 to 6 times daily does not appear to have a negative or positive impact on performance or welfare of group-housed gilts and sows.     

Impact of betaine on pig finishing performance and carcass composition

Two experiments were conducted to evaluate the effect of betaine supplementation of finishing diets on growth performance and carcass characteristics of swine. Experiment 1 included 288 pigs in a 2 x 2 x 3 factorial arrangement of treatments consisting of barrows and gilts of two genetic populations fed diets with 1.25 g/kg supplemental betaine from either 83 or 104 kg to 116 kg and control pigs fed betaine-devoid diets. Pigs were housed three pigs per pen with eight replicate pens per treatment. Diets were corn-soybean meal-based with 300 ppm added choline. Genetic populations differed (P < 0.05) in fat depth (2.24 vs 2.93 cm) and longissimus muscle depth (53.8 vs 49.1 mm) at 116 kg. Betaine reduced feed intake (P < 0.05); however, real-time ultrasound measurements were not affected. In Exp. 2, 400 pigs were used in a 2 x 2 x 2 factorial arrangement of treatments to evaluate the effect of sex (barrow or gilts), betaine (0 or 1 g/kg of diet), and crude protein (CP) (0.70% lysine = 12.7% CP or 0.85% lysine = 15.0% CP) when fed from 60 to 110 kg live weight. Pigs had been assigned to either a high- or low-protein feeding regimen at an average initial weight of 11.3 kg and were maintained on their respective protein levels throughout the experiment. For a 56-d period from 61.7 kg to 113.6 kg, pigs were fed diets with 300 ppm added choline. Within each protein level, pigs were randomly assigned to diets containing 0 or 1 g/kg betaine. Pigs were group-housed (four to five pigs per pen). Pig weight and feed intake were recorded every 28 d. Real-time ultrasound measurements were recorded initially and at d 28 on 64 pigs, and on all pigs prior to slaughter. Growth rate was fastest and feed intake greatest for barrows (P < 0.05) and for pigs receiving 12.7% crude protein. A crude protein x betaine interaction (P < 0.05) was observed from d 28 to 56 with pigs fed the 15% CP diet growing fastest when supplemented with 1 g/kg betaine, and pigs receiving the 12.7% CP diet growing fastest when the diets contained 0 g/kg betaine. Gilts more efficiently (P < 0.05) converted feed into body weight gain, as did pigs receiving the 12.7% CP diet (P < 0.05). Longissimus muscle area and fat measurements were unaffected by betaine or dietary protein on d 28. However, by d 56 betaine reduced average fat depth in barrows (P < 0.05; 3.21 vs 3.40 cm), but not in gilts. Betaine may be more effective at altering body composition in barrows than in gilts.     

Effect of carbohydrate source on growth performance, carcass traits, and meat quality of growing-finishing pigs

Two experiments were conducted to determine the effect of substituting a more available dietary carbohydrate (CHO) for portions of corn or fat in the diet on growth performance, carcass traits, meat quality, and serum or plasma metabolites in growing-finishing pigs. A three-phase feeding program was used with corn-soybean meal diets formulated to provide 105% of the Lys requirement for barrows or gilts gaining 325 g of lean daily in Exp. 1 or gilts gaining 350 g of lean daily in Exp. 2. Diets were isoenergetic within experiments. All other nutrients met or exceeded suggested requirements. In Exp. 1, pigs were allotted to three dietary treatments (0, 7.5, or 15.0% sucrose), with three replications of barrows and three replications of gilts, and with three or four pigs per replicate pen; average initial and final BW were 25.2 and 106.7 kg. In Exp. 2, gilts were allotted to two dietary treatments (waxy [high amylopectin] or nonwaxy [75% amylopectin and 25% amylose] corn as the grain source), with five replications of four gilts per replicate pen; average initial and final BW were 37.7 and 100.0 kg. In Exp. 1, ADG and gain:feed ratio increased linearly (P < 0.02) as dietary sucrose increased. Minolta color scores, a* and b*, and drip loss (P < 0.06) also increased linearly with added sucrose. In Exp. 2, ADG, carcass weight and length, and the Minolta a* value were greater for pigs fed waxy corn (P < 0.08) than for those fed nonwaxy corn. Feed intake, longissimus muscle area, 10th-rib and average backfat thickness, dressing percentage, fat-free lean, percentage of lean and muscling, lean gain per day, total fat, percentage fat, lean:fat ratio, serum or plasma metabolites (Exp. 1: serum urea N; Exp. 2: serum urea N, and plasma nonesterified fatty acids, triacylglycerols, total and high-density lipoprotein cholesterol, insulin, and total protein), pH of the longissimus muscle, and subjective muscle scores (color, firmness-wetness, and marbling) were not affected by diet in either experiment. In summary, increasing availability of dietary CHO in growing-finishing pig diets improved growth performance, but it did not affect carcass traits.     

Influence of dietary protein level, amino acid supplementation, and dietary energy levels on growing-finishing pig performance and carcass composition

Two experiments were conducted to determine the effects of feeding reduced-CP, AA-supplemented diets at two ambient temperatures (Exp. 1) or three levels of dietary NE (Exp. 2) on pig performance and carcass composition. In Exp. 1, 240 mixed-sex pigs were used to test whether projected differences in heat increment associated with diet composition affect pig performance. There were 10 replications of each treatment with four pigs per pen. For the 28-d trial, average initial and final BW were 28.7 kg and 47.5 kg, respectively. Pigs were maintained in a thermoneutral (23 degrees C) or heat-stressed (33 degrees C) environment and fed a 16% CP diet, a 12% CP diet, or a 12% CP diet supplemented with crystalline Lys, Trp, and Thr (on an as-fed basis). Pigs gained at similar rates when fed the 16% CP diet or the 12% CP diet supplemented with Lys, Trp, and Thr (P > 0.10). Pigs fed the 12% CP, AA-supplemented diet had a gain:feed similar to pigs fed the 16% CP diet when housed in the 23 degrees C environment but had a lower gain:feed in the 33 degrees C environment (diet x temperature, P < 0.01). In Exp. 2, 702 gilts were allotted to six treatments with nine replicates per treatment. Average initial and final BW were 25.3 and 109.7 kg, respectively. Gilts were fed two levels of CP (high CP with minimal crystalline AA supplementation or low CP with supplementation of Lys, Trp, Thr, and Met) and three levels of NE (high, medium, or low) in a 2 x 3 factorial arrangement. A four-phase feeding program was used, with diets containing apparent digestible Lys levels of 0.96, 0.75, 0.60, and 0.48% switched at a pig BW of 41.0, 58.8, and 82.3 kg, respectively. Pigs fed the low-CP, AA-supplemented diets had rates of growth and feed intake similar to pigs fed the high-CP diets. Dietary NE interacted with CP level for gain:feed (P < 0.06). A decrease in dietary NE from the highest NE level decreased gain:feed in pigs fed the high-CP diet; however, gain:feed declined in pigs fed the low-CP, AA-supplemented diet only when dietary NE was decreased to the lowest level. There was a slight reduction in longissimus area in pigs fed the low-CP diets (P < 0.08), but other estimates of carcass muscle did not differ (P > 0.10). These data suggest that pigs fed low-CP, AA-supplemented diets have performance and carcass characteristics similar to pigs fed higher levels of CP and that alterations in dietary NE do not have a discernible effect on pig performance or carcass composition.     

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.     

Effects of dietary spray-dried egg on growth performance and health of weaned pigs

Four experiments were conducted to evaluate the nutrient contributions and physiological health benefits of spray-dried egg (SDE) containing only unfertilized eggs as a protein source in nursery pig diets. In all experiments, all diets were formulated to the same ME and Lys content, and each pen within a block (by BW) housed the same number of barrows and gilts. In Exp. 1 and 2 (168 and 140 pigs, respectively; 5 kg BW; 16 d old; 14 replicates/experiment), conducted at a university farm, treatments were with or without 5% SDE in a nursery control diet, which included antibiotics and zinc oxide. Pigs were fed for 10 d after weaning to measure ADG, ADFI, and G:F. The SDE increased (P < 0.05) ADG (Exp. 1: 243 vs. 204 g/d; Exp. 2: 204 vs. 181 g/d) and ADFI (Exp. 1: 236 vs. 204 g/d; Exp. 2: 263 vs. 253 g/d) compared with the control diet but did not affect G:F. In Exp. 3 (1,008 pigs; 5.2 kg BW; 20 d old; 12 replicates/treatment), conducted at a commercial farm, treatments were in a factorial arrangement of with or without SDE and high or low spray-dried plasma (SDP) in nursery diets, which included antibiotics and zinc oxide. Pigs were fed for 6 wk using a 4-phase feeding program (phases of 1, 1, 2, and 2 wk, respectively) with declining diet complexity to measure ADG, ADFI, G:F, removal rate (mortality plus morbidity), and frequency of medical treatments per pen and day (MED). The diets with the SDE increased (P < 0.05) ADFI during phase 1 only (180 vs. 164 g/d) compared with the diets without the SDE but did not affect growth performance during any other phases. The diets with SDE reduced MED during phase 1 (0.75% vs. 1.35%; P < 0.05) and the overall period (0.84% vs. 1.01%; P = 0.062) compared with the diets without the SDE but did not affect removal rate. In Exp. 4 (160 pigs; 6.7 kg BW; 21 d old; 10 replicates/treatment), conducted at a university farm to determine whether SDE can replace SDP, treatments were in a factorial arrangement of with or without SDP or SDE in nursery diets, which excluded antibiotics and zinc oxide. Pigs were fed for 6 wk using the same schedule used in Exp. 3 to measure ADG, ADFI, and G:F. The diets with SDE increased (P < 0.05) ADFI during phase 1 only (195 vs. 161 g/d) compared with the diets without SDE but did not affect growth performance during any other periods. In conclusion, SDE can be an efficacious protein and energy source in nursery pig diets and improves health and, in some instances, increases growth rate.     

Estimation of the total sulfur amino acid requirement and the effect of betaine in diets deficient in total sulfur amino acids for the weanling pig.

Four experiments were conducted to determine whether betaine (BET) could replace dietary methionine (MET) in diets for weanling pigs. Pigs in each experiment were allotted to treatments on the basis of weight in a randomized complete block design. Each treatment was replicated four (Exp. 4), five (Exp. 1 and 2), or six (Exp. 3) times with five or six pigs per replicate. In Exp. 1, pigs were fed a diet formulated to be deficient in total sulfur amino acids (TSAA) (negative control; NC) or the NC + 0.05 or 0.10% MET or BET during Phase 1 and 0.035 or 0.07% MET or BET during Phase 2. Growth performance was not affected (P > 0.10) by dietary treatments, indicating that the diets were not deficient in TSAA. In Exp. 2, graded levels of TSAA (0.74, 0.79, 0.84, 0.89, or 0.94%) were fed. Overall ADG was increased (0 vs added MET, P < 0.07) in pigs fed TSAA levels of 0.79% or greater, but gain:feed was not affected (P > 0.10) by diet. Overall ADFI was increased (linear, P < 0.08) and plasma urea N (PUN) was decreased (quadratic, P < 0.01) as the level of TSAA was increased. Most of the change in ADG, PUN, and ADFI occurred between 0.74 and 0.84% TSAA. Thus, the 0.74% TSAA diet was used in Exp. 3 as the NC. In Exp. 3, the diets included the following: 1) NC, 2) NC + 0.05% MET, 3) NC + 0.10% MET, 4) NC + 0.039% BET, or 5) NC + 0.078% BET. The addition of MET resulted in increased (linear, P < 0.10) ADG, ADFI, and gain:feed, but MET decreased PUN (linear, P < 0.05). Daily gain, ADFI, and TSAA intake were not different (P > 0.10) between pigs fed 0.05% MET or 0.039% BET, but gain:feed was decreased (P < 0.01) in pigs fed 0.039% BET compared with pigs fed 0.05% MET. In Exp. 4, a 2 x 2 x 2 factorial arrangement of treatments was used (MET, 0 or 0.072%; cystine, 0 or 0.059%; or BET, 0 or 0.057%). Overall ADG and gain:feed were increased (P < 0.10) in pigs fed MET. The intake of TSAA was increased (P < 0.05), and PUN was decreased (P < 0.10) in pigs fed MET or cystine. Overall ADFI was increased in pigs fed BET or MET independently but not affected when BET and MET were fed together (BET x MET, P < 0.10). The addition of BET to TSAA-deficient diets resulted in increased ADG, which was due to an increase in ADFI (TSAA intake). Thus, BET did not spare MET in this experiment.     

Individually measured feed intake characteristics and growth performance of group-housed weanling pigs: effects of sex, initial body weight, and body weight distribution within groups

Feed intake characteristics of 192, 27-d-old weanling pigs housed in groups and given ad libitum access to feed and water were measured individually with the use of computerized feeding stations. The groups were either homogeneous or heterogeneous as to BW distribution; pigs of three defined initial BW classes were used (mean BW of 6.7, 7.9, or 9.3 kg). The effects of BW distribution, BW class, and sex were studied with regard to average performance traits, latency time (interval between weaning and first feed intake), initial feed intake (intake during the first 24 h following first feed intake), and daily increase in feed intake during the interval between first feed intake and the day on which energy intake met or exceeded 1.5 times the maintenance requirement. Homogeneous and heterogeneous groups had similar latency times, initial feed intakes, and daily increases in feed intake. For the period 0 to 34 d after weaning, ADFI and ADG were also similar for homogeneous and heterogeneous groups, but gain:feed ratio was greater (P < 0.05) in the homogeneous groups. Gilts had higher (P < 0.05) initial feed intakes than barrows and also had greater (P < 0.05) ADFI and ADG during the period 0 to 13 d after weaning. Pigs with average BW of 6.7 kg had higher (P < 0.05) initial feed intakes than their counterparts with average BW of 7.9 kg and 9.3 kg, but the daily increase in feed intake was similar for the three groups. The lighter pigs had more daily visits and a lower feed intake per visit and tended to have a shorter postweaning latency to the onset of feeding than the heavier pigs. This study indicates that the high variability in early feeding behavior among group-housed weanling pigs may be related to BW and sex.     

Utilization of spray-dried blood cells and crystalline isoleucine in nursery pig diets

Three experiments were conducted to evaluate spray-dried blood cells (SDBC) and crystalline isoleucine in nursery pigs. In Exp. 1, 120 pigs were used to evaluate 0, 2, 4, and 6% SDBC (as-fed basis) in a sorghum-based diet. There were six replicates of each treatment and five pigs per pen, with treatments imposed at an initial BW of 9.3 kg and continued for 16 d. Increasing SDBC from 0 to 4% had no effect on ADG, ADFI, and G:F. Pigs fed the 6% SDBC diet had decreased ADG (P < 0.01) and G:F (P = 0.06) compared with pigs fed diets containing 0, 2, or 4% SDBC. In Exp. 2, 936 pigs were used to test diets containing 2.5 or 5% SDBC (as-fed basis) vs. two control diets. There were six replicates of each treatment at industry (20 pigs per pen) and university (six pigs per pen) locations. Treatments were imposed at an initial BW of 5.9 and 8.1 kg at the industry and the university locations, respectively, and continued for 16 d. Little effect on pig performance was noted by supplementing 2.5% SDBC, with or without crystalline Ile, in nursery diets. Pigs fed the 5% SDBC diet without crystalline Ile had decreased ADG (P < 0.01), ADFI (P < or = 0.10), and G:F (P < 0.05) compared with pigs fed the control diets. Supplementation of Ile restored ADG, ADFI, and G:F to levels that were not different from that of pigs fed the control diets. In Exp. 3, 1,050 pigs were used to test diets containing 5, 7.5, or 9% SDBC (as-fed basis) vs. a control diet. There were six replicates of each treatment at the industry (20 pigs per pen) location and five replicates at the university (six pigs per pen) locations. Treatments were imposed at an initial BW of 6.3 and 7.0 kg at the industry and university locations, respectively, and continued for 16 d. Supplementation of 5% SDBC without crystalline Ile decreased ADG and G:F (P < 0.01) compared with pigs fed the control diet, but addition of Ile increased ADG (P < 0.01) to a level not different from that of pigs fed the control diet. The decreased ADG, ADFI, and G:F noted in pigs fed the 7.5% SDBC diet was improved by addition of Ile (P < 0.01), such that ADG and ADFI did not differ from those of pigs fed the control diet. Pigs fed diets containing 9.5% SDBC exhibited decreased ADG, ADFI, and G:F (P < 0.01), all of which were improved by Ile addition (P < 0.01); however, ADG (P < 0.05) and G:F (P = 0.09) remained lower than for pigs fed the control diet. These data indicate that SDBC can be supplemented at relatively high levels to nursery diets, provided that Ile requirements are met.     

Effect of irradiation of individual feed ingredients and the complete diet on nursery pig performance

A total of 1,210 nursery pigs was used in two experiments to evaluate the effects of irradiation of typical nursery diet ingredients, specialty protein products, and the whole diet on nursery pig performance. In Exp. 1, 880 barrows and gilts (15 +/- 2 d of age at weaning) were used in two growth trials (14 d and 12 d for Trials 1 and 2, respectively) to determine the effects of individual ingredient and whole-diet irradiation on nursery pig performance. Overall (d 0 to 14 of Trial 1 and d 0 to 12 of Trial 2), ADG was greater (P < 0.05) for pigs fed irradiated animal plasma compared with pigs fed the control, the diet containing irradiated microingredients, and the diet that was manufactured and irradiated. Also, pigs fed irradiated soybean meal had greater (P < 0.05) ADFI compared with pigs fed the manufactured diet that was irradiated. Pigs fed the diet containing irradiated animal plasma had improved feed efficiency (G:F; P < 0.05) compared with those fed the diet with irradiated microingredients and when all ingredients were irradiated before manufacturing of complete feed. Finally, pigs fed irradiated corn, whey, fishmeal, soybean oil, microingredients, or if all ingredients or the whole diet were irradiated, had similar ADG, ADFI, and G:F (P > 0.12) to control pigs. In Exp. 2, 330 nursery pigs (20 +/- 2 d of age at weaning) were used to determine the effects of irradiation of commercially available specialty protein products in diets for nursery pigs. Overall, ADG was greater (P < 0.05) when pigs were fed diets containing nonirradiated spray-dried animal plasma and egg combination (SDAPE) and dried porcine digest (DPD) compared with pigs fed the control diet containing no specialty protein products. In addition, G:F was improved (P < 0.05) when pigs were fed diets containing nonirradiated SDAPE, DPD, spray-dried beef muscle (SDBM), and spray-dried whole egg (SDWE) compared with pigs fed the control diet. Pigs fed irradiated SDAPE and SDBM had greater (P < 0.05) ADG than pigs fed the nonirradiated forms. Pigs fed irradiated SDBM had improved (P < 0.05) G:F compared with pigs fed the nonirradiated form. In Exp. 1 and 2, an irradiation treatment level of 8.5 kGy was effective in reducing the total bacterial concentration of all ingredients evaluated, as well as the whole diet in Exp.1. Irradiation of certain ingredients, but not the complete diet, increased growth performance of nursery pigs.     

Effects of dietary organic and inorganic trace mineral levels on sow reproductive performances and daily mineral intakes over six parities

Dietary trace mineral sources and levels were fed to developing gilts to evaluate their performance responses during the growth phase, but treatments were continued into the reproductive phase in which subsequent reproductive responses were evaluated. In Exp. 1, three groups of gilts (n = 216) were used in a 2 x 2 factorial in a randomized complete block design (6 replicates) with treatment diets initially fed at 30 kg of BW. The first factor was trace mineral source (organic or inorganic), whereas the second factor evaluated dietary levels. The NRC requirement was the first level evaluated, whereas the second level was formulated to average industry standards (IND). Organic trace minerals were mineral proteinates, whereas the inorganic minerals were provided in salt form. The results of Exp. 1 indicated that trace mineral source or level did not affect gilt growth or feed performance responses to 110 kg of BW. Experiment 2 continued with the same females but was a 2 x 3 factorial in a split-plot design using 3 groups of females over a 6-parity period and had a total of 375 farrowings. Factors in Exp. 2 were the same as in Exp. 1, except that 2 additional pens of gilts during their development had been fed the IND level trace mineral levels of both trace mineral sources. At breeding, the gilts from these 2 additional pens were continued on the same trace mineral source and level but fed greater dietary Ca and P levels (IND + Ca:P). Litters were standardized by 3 d postpartum within each farrowing. Sows fed organic trace minerals farrowed more (P < 0.05) total (12.2 vs. 11.3) and live pigs (11.3 vs. 10.6) compared with sows fed inorganic trace minerals. Sows fed the IND + Ca:P level tended to have fewer (P < 0.10) total pigs born for both trace mineral sources. Litter birth weights were heavier (P < 0.05) when sows were fed organic trace minerals, but individual piglet weights were similar. Nursing pig ADG tended to be greater (P < 0.10) when sows were fed organic trace minerals. Other sow reproductive traits (BW, feed intake, and rebreeding interval) were not affected by trace mineral source or level. Daily mineral intake increased by parity but declined when trace mineral intakes were expressed on an amount per kilogram of BW and declined during later lactations. These results suggest that feeding sows organic trace minerals may improve sow reproductive performance, but there were minimal effects on other reproductive measurements.     

Effects of dietary energy density and lysine:calorie ratio on growth performance and carcass characteristics of growing-finishing pigs

We conducted two experiments to evaluate the effects of dietary energy density and lysine:calorie ratio on the growth performance and carcass characteristics of growing and finishing pigs. In Exp. 1, 80 crossbred barrows (initially 44.5 kg) were fed a control diet or diets containing 1.5, 3.0, 4.5, or 6.0% choice white grease (CWG). All diets contained 3.2 and 2.47 g of lysine/Mcal ME during growing (44.5 to 73 kg) and finishing (73 to 104 kg), respectively. Increasing energy density did not affect overall ADG; however, ADFI decreased and feed efficiency (Gain:feed ratio; G:F) increased (linear, P < .01). Increasing energy density decreased and then increased (quadratic, P < .06) skinned fat depth and lean percentage. In Exp. 2, 120 crossbred gilts (initially 29.2 kg) were used to determine the effects of increasing levels of CWG and lysine:calorie ratio fed during the growing phase on growth performance and subsequent finishing growth. Pigs were fed increasing energy density (3.31, 3.44, or 3.57 Mcal ME/kg) and lysine:calorie ratio (2.75, 3.10, 3.45, or 3.80 g lysine/Mcal ME). No energy density x lysine:calorie ratio interactions were observed (P > .10). Increasing energy density increased ADG and G:F and decreased ADFI of pigs from 29.5 to 72.6 kg (linear, P < .05). Increasing lysine:calorie ratio increased ADG and ADFI (linear, P < .01 and .07, respectively) but had no effect on G:F. From 72.6 to 90.7 kg, all pigs were fed the same diet containing .90% lysine and 2.72 g lysine/Mcal ME. Pigs previously fed with increasing lysine:calorie ratio had decreased (linear, P < .02) ADG and G:F. Also, pigs previously fed increasing CWG had decreased (linear, P < .03) ADG and ADFI. From 90.7 to 107 kg when all pigs were fed a diet containing .70% lysine and 2.1 g lysine/Mcal ME, growth performance was not affected by previous dietary treatment. Carcass characteristics were not affected by CWG or lysine:calorie ratio fed from 29.5 to 72.6 kg. Increasing the dietary energy density and lysine:calorie ratio improved ADG and G:F of growing pigs; however, pigs fed a low-energy diet or a low lysine:calorie ratio from 29 to 72 kg had compensatory growth from 72 to 90 kg.     

The relationship of feeding behavior to residual feed intake in crossbred Angus steers fed traditional and no-roughage diets

Two studies were conducted to determine the relationship of feeding behavior to a phenotypic expression of residual feed intake (RFI), a measure of efficiency. In Exp. 1, a feedlot diet containing roughage was fed (traditional). In Exp. 2, a no-roughage diet was fed. Residual feed intake, a measure of feed efficiency, was calculated for both studies. In Exp. 1, six feed-efficient (low RFI) steers and six feed-inefficient steers (high RFI) were selected from a contemporary group of 80 steers, and feeding behaviors were analyzed. In Exp. 2, nine feed-efficient and eight feed-inefficient steers were selected from a contemporary group of 40 steers. There were no differences (P > 0.13) in initial or final BW or ADG between efficient and inefficient groups in either Exp. 1 or 2. In Exp. 1, DMI and average eating bouts daily differed (P < 0.001), with efficient steers consuming less feed and eating fewer times per day. In Exp. 2, efficient steers consumed less (P < 0.001) feed, and average eating bouts daily tended (P = 0.07) to be fewer in efficient animals. Limited differences were noted in feeding behavior between groups, with inefficient steers from both studies having a more variable eating pattern throughout the day. The average daily eating rate did not differ (P > 0.20) between groups in either experiment. The average number of days comprising a feeding pattern for both efficiency groups in Exp. 1 and 2 was found to be 2 to 3 d and multiples of 2 to 3 d. In Exp. 1, the feed intake pattern of efficient and inefficient steers changed once they reached a BW of approximately 391 and 381 kg, respectively. This occurred near d 47 for the efficient steers and near d 32 for inefficient steers. In Exp. 2, the feed intake pattern of both efficient and inefficient steers changed once they reached a BW of approximately 399 kg, which occurred on d 31 for the efficient steers and on d 33 for the inefficient steers. From the measured variables, there were no differences in growth and limited differences noted in feeding behavior between efficient and inefficient groups. The results of the trials suggest increased variability of feed intake throughout the day for inefficient animals.     

Growth performance of 20- to 50-kilogram pigs fed low-crude-protein diets supplemented with histidine, cystine, glycine, glutamic acid, or arginine

The purpose of this investigation was to compare the growth performance of grower pigs fed low-CP, corn-soybean meal (C-SBM) AA-supplemented diets with that of pigs fed a positive control (PC) C-SBM diet with no supplemental Lys. Five experiments were conducted with Yorkshire crossbred pigs, blocked by BW (average initial and final BW were 21 and 41 kg, respectively) and assigned within block to treatment. Each treatment was replicated 4 to 6 times with 4 or 5 pigs per replicate pen. Each experiment lasted 28 d and plasma urea N was determined at the start and end of each experiment. All diets were formulated to contain 0.83% standardized ileal digestible Lys. All the experiments contained PC and negative control (NC) diets. The PC diet contained 18% CP and was supplemented with only DL-Met. The NC diet contained 13% CP and was supplemented with L-Lys, DL-Met, L-Thr, and L-Trp. The NC + Ile + Val diet was supplemented with 0.10% Val + 0.06% Ile. The NC + Ile + Val diet was supplemented with either His (Exp. 1), Cys (Exp. 2), Gly (Exp. 2, 3, and 4), Glu (Exp. 3), Arg (Exp. 4), or combinations of Gly + Arg (Exp. 4 and 5) or Gly + Glu (Exp. 5). Treatment differences were considered significant at P < 0.10. In 3 of the 4 experiments that had PC and NC diets, pigs fed the NC diet had decreased ADG and G:F compared with pigs fed the PC diet. The supplementation of Ile + Val to the NC diet restored ADG in 4 out of 5 experiments. However, G:F was less than in pigs fed the PC diet in 1 experiment and was intermediate between the NC and PC diets in 3 experiments. Pigs fed supplemental Ile + Val + His had decreased G:F compared with pigs fed the PC. Pigs fed supplemental Cys to achieve 50:50 Met:Cys had decreased G:F compared with pigs fed the PC. Pigs fed Ile + Val + 0.224% supplemental Gly had similar ADG, greater ADFI, and decreased G:F compared with pigs fed the PC. Pigs fed Ile + Val + 0.52% supplemental Gly had ADG and G:F similar to that of pigs fed the PC. Pigs fed supplemental Glu had decreased G:F compared with pigs fed the PC. Pigs fed Ile + Val + 0.48% supplemental Arg had decreased G:F compared with pigs fed the PC. Pigs fed the diet supplemented with Gly + Arg had ADG and G:F similar to pigs fed the PC. Pigs fed the low-CP diets had reduced plasma urea N compared with pigs fed PC. The results of these experiments indicate that supplementing Gly or Gly + Arg to a low-CP C-SBM diet with 0.34% Lys, Met, Thr, Trp, Ile, and Val restores growth performance to be similar to that of pigs fed a PC diet with no Lys supplementation.     

Effect of microbial phytase on energy availability,and lipid and protein deposition in growing swine

Two experiments were conducted to determine the effect of phytase on energy availability in pigs. In Exp. 1, barrows (initial and final BW of 26 and 52 kg) were allotted to four treatments in a 2 x 2 factorial arrangement. Corn-soybean meal (C-SBM) diets were fed at two energy levels (2.9 and 3.2 x maintenance [M]) with and without the addition of 500 phytase units/kg of diet. The diets contained 115% of the requirement for Ca, available P (aP), and total lysine, and Ca and aP were decreased by 0.10% in diets with added phytase. Pigs were penned individually and fed daily at 0600 and 1700, and water was available constantly. Eight pigs were killed and ground to determine initial body composition. At the end of Exp. 1, all 48 pigs were killed for determination of carcass traits and protein and fat content by total-body electrical conductivity (TOBEC) analysis. Six pigs per treatment were ground for chemical composition. In Exp. 2, 64 barrows and gilts (initial and final BW of 23 and 47 kg) were allotted to two treatments (C-SBM with 10% defatted rice bran or that diet with reduced Ca and aP and 500 phytase units/kg of diet), with five replicate pens of barrows and three replicate pens of gilts (four pigs per pen). In Exp. 1, ADG was increased (P < 0.01) in pigs fed at 3.2 x M. Based on chemical analyses, fat deposition, kilograms of fat, retained energy (RE) in the carcass and in the carcass + viscera, fat deposition in the organs, and kilograms of protein in the carcass were increased (P < 0.10) in pigs fed the diets at 3.2 vs. 2.9 x M. Based on TOBEC analysis, fat deposition, percentage of fat increase, and RE were increased (P < 0.09) in pigs fed at 3.2 x M. Plasma urea N concentrations were increased in pigs fed at 3.2 x M with no added phytase but were not affected when phytase was added to the diet (phytase x energy, P < 0.06). Fasting plasma glucose measured on d 28, ultrasound longissimus muscle area (LMA), and 10th-rib fat depth were increased (P < 0.08) in pigs fed phytase, but many other response variables were numerically affected by phytase addition. In Exp. 2, phytase had no effect (P > 0.10) on ADG, ADFI, gain:feed, LMA, or 10th-rib fat depth. These results suggest that phytase had small, mostly nonsignificant effects on energy availability in diets for growing pigs; however, given that phytase increased most of the response variables measured, further research on its possible effects on energy availability seems warranted.     

Escherichia coli phytase improves growth performance of starter, grower, and finisher pigs fed phosphorus-deficient diets

Corn-soybean meal-based diets, consisting of a high-P control (HPC) containing supplemental dicalcium phosphate (DCP), a basal diet containing no DCP, and the basal diet plus Escherichia coli phytase at 500 or 1,000 phytase units per kilogram (FTU/kg; as-fed basis) were fed to evaluate growth performance in starter, grower, and finisher pigs. Pigs were blocked by weight and gender, such that average weight across treatments was similar, with equal numbers of barrows and gilts receiving each treatment in each block. In Exp. 1, 48 pigs with an average initial BW of 11 kg, housed individually, with 12 pens per diet, were used to evaluate growth performance over 3 wk. Overall ADG and G:F were increased linearly (P < 0.05) by dietary phytase addition. Final BW and plasma P concentrations at 3 wk also increased linearly (P < 0.05). In Exp. 2, 128 pigs with an average initial BW of 23 kg, housed four pigs per pen, with eight pens per diet, were used to evaluate growth performance over 6 wk. A linear increase in response to phytase was noted for ADG and G:F in all three 2-wk periods, as well as overall (P < 0.05). Percentage of bone ash also showed a linear increase (P < 0.01). In Exp. 3, 160 pigs (53 kg), housed five pigs per pen, with eight pens per diet, were used to evaluate growth performance over 6 wk. A linear increase was detected for final BW, as well as ADG and G:F in the first and second 2-wk periods, and overall (P < 0.01). Twenty-four 15-kg individually housed pigs were used to evaluate total-tract nutrient digestibility in Exp. 4. Daily absorption of P linearly increased (P < 0.05) with phytase supplementation. Results of this research indicate that E. coli phytase is effective in liberating phytate P for uptake and utilization by starter, grower, and finisher pigs.