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A study was conducted to determine the standardized total tract digestible phosphorus (STTD P) requirement for 24- to 130-kg finishing pigs housed under commercial conditions. A total of 1,130 barrows and gilts (PIC 359 × 1050, Hendersonville, TN; initially 24.2 kg) were used, with 26 to 27 pigs per pen with 7 replicates per treatment. Pens of pigs were allotted to treatments in a randomized complete block design with body weight (BW) as the blocking factor. The dietary treatments were fed in 4 phases and were formulated to contain 80%, 90%, 100%, 115%, 130%, and 150% of the National Research Council (NRC) requirement estimate for finishing pigs within each phase. Weight ranges for each phase were: 27 to 49, 49 to 76, 76 to 90, and 90 to 130 kg. Treatments were achieved by increasing the amount of monocalcium phosphate at the expense of corn in the diet with no added phytase. All diets were formulated to contain a similar 1.14:1 to 1.16:1 total Ca:P ratio across treatments in all phases. Increasing STTD P resulted in a quadratic response (P < 0.05) in average daily gain (ADG), gain-to-feed ratio (G:F), and final BW. The greatest improvement was observed with STTD P at 130% of NRC for ADG and final BW and at 115% STTD P for G:F. Average daily feed intake increased linearly (linear, P < 0.05) with the inclusion of STTD P. Increasing STTD P resulted in an increase (quadratic, P < 0.05) in hot carcass weight (HCW) and carcass ADG with the greatest response observed with STTD P at 130% of NRC. There was a marginally significant response (quadratic, P < 0.10) in carcass G:F, with the greatest improvement with STTD P at 115% of NRC. Carcass yield decreased (linear, P < 0.05) with increasing STTD P, while there was a marginally significant (linear, P < 0.10) decrease in backfat and increase in fat-free lean. At the end of the study, a metacarpal was collected and analyzed for bone ash. Increasing STTD P resulted in an increase (linear, P < 0.05) in bone ash weight and percentage ash. For ADG and G:F, the quadratic model demonstrated the best fit. The maximum response in ADG and G:F was estimated at 122% and 116% of NRC STTD P, respectively. The broken-line linear model best fit the data for percentage bone ash, with a plateau achieved at 131% of the NRC STTD P. In conclusion, the estimated STTD P requirement of 24 to 130 kg ranged from 116% to 131% of the NRC publication (2012) requirement estimate.

One batch each of eight full-fat soybeans (FFSB) was used to determine the effect of different heat treatments including wet heating (WH) and autoclaving (AC) on chemical composition and standardized ileal digestibility (SID) of CP and AA in growing pigs. The raw FFSB (K0) were either treated by WH at 80°C for 1 min (K1), at 100°C for 6 min (K2), or at 100°C for 16 min (K3). Thereafter, these batches were expanded at 125°C for 15 s. A further heat treatment included AC at 110°C for 15 (Z1), 30 (Z2), 45 (Z3), or 60 (Z4) min of FFSB that were subjected to the same WH treatment as K3. Diets were formulated to contain the respective FFSB as the sole source of CP and AA. A N-free diet was used to measure basal endogenous losses of CP and AA in an additional period at the end of the experiment. Eight ileally cannulated pigs (28 ± 1 kg) were allocated to a row-column design with 8 diets and 6 periods of 7 d each. An increase in the duration of WH had no effect on contents of AA (% of CP) and NDF, but NDIN contents linearly increased ( < 0.05) with increasing time for WH. Autoclaving resulted in a linear decrease ( < 0.05) of trypsin inhibitor activity (TIA), contents of Arg, Leu, Ala, Asp, Cys, and Gly as well as Lys to CP ratio (Lys:CP), reactive Lys to CP ratio (rLys:CP), and in an increase ( < 0.05) in contents of NDF and NDIN. There was a quadratic response ( < 0.05) of SID of CP and AA as time for WH at 100°C increased from 0 (K0) to 6 (K2) up to 16 (K3) min. Moreover, a quadratic response ( < 0.05) to increasing time of AC was observed for SID of Arg, Phe, and Pro. The SID of CP and all indispensable AA showed a quadratic response ( < 0.05) to decreasing TIA, urease activity, protein solubility in 0.2% potassium hydroxide, protein dispersibility index, Lys:CP, (lightness), and to increasing NDIN and (redness). In addition, there was a linear increase ( < 0.05) in SID values with decreasing rLys:CP and increasing NDF contents. In conclusion, WH proved to be suitable for increasing SID values. Further improvement of SID of most AA could be achieved on additional AC treatment from Z1 to Z3, however, it needs to be considered, if the observed increase due to AC is cost effective in view of the additional production costs. Several chemical and physical parameters can be used in the feed industry for quality control purposes to predict the extent of heat damage on SID of CP and indispensable AA in FFSB.

Two experiments were conducted to determine the standardized total tract digestible phosphorus (STTD P) requirement for 11- to 23-kg nursery pigs fed diets with or without phytase. A total of 1,080 and 2,140 pigs (PIC 359 × Camborough, Hendersonville, TN; initially 11.4 ± 0.29 and 11.1 ± 0.24 kg) were used in Exp. 1 and Exp. 2, respectively. There were 23 to 27 pigs per pen with 6 and 12 replicate pens per treatment in Exp. 1 and Exp. 2, respectively. After weaning, pigs were fed a common pelleted diet with 0.45% STTD P for 7 d, and a common phase 2 meal diet with 0.40% STTD P for 14 d in Exp. 1 and 18 d in Exp. 2. Pens of pigs were then allotted to dietary treatments in a randomized complete block design with body weight (BW) as the blocking factor. In Exp. 1, dietary treatments consisted of 0.26%, 0.30%, 0.33%, 0.38%, 0.43%, 0.48%, and 0.53% STTD P. Treatments were achieved with the inclusion of monocalcium phosphate at the expense of corn. In Exp. 2, diets contained 1,000 phytase units (FYT; Ronozyme Hiphos 2500, DSM Nutritional Products, Inc., Parsippany, NJ) with assumed release value 0.132% STTD P, and treatments consisted of 0.30%, 0.33%, 0.38%, 0.43%, 0.48%, 0.53%, and 0.58% STTD P. These STTD P concentrations included the expected phytase release of 0.132% STTD P. In both experiments, a similar 1.17:1 Ca:P ratio was maintained across treatments. Statistical models included linear model (LM), quadratic polynomial (QP), broken-line linear (BLL), and broken-line quadratic (BLQ). In Exp. 1, increasing STTD P increased (linear, P < 0.001) ADG, ADFI, G:F, final BW, and grams of STTD P intake per day and per kilogram of gain. There was also a marginal quadratic response for G:F (P < 0.066). In Exp. 2, ADG and G:F increased quadratically (P < 0.05), whereas ADFI increased linearly (P = 0.060) with increasing STTD P. The BLL and QP model provided similar fit to G:F in Exp. 1, estimating the requirement for maximum G:F at 0.34% and 0.42%, respectively. The BLL was the best fitting model for ADG and G:F in Exp. 2, estimating the breakpoint at 0.40% and 0.37% STTD P, respectively. The BLL and BLQ models estimated the breakpoint for ADG as a function of STTD P intake in grams per day at 2.92 and 3.02 g/d, respectively. These data provide empirical evidence that for 11- to 23-kg pigs, the NRC (2012) accurately estimates the STTD P requirement on a g/d basis. As a percentage of the diet, the STTD P requirement for diets without or with 1,000 FYT added phytase ranged from 0.34% to 0.42%.

Seven ruminally cannulated Brahman steers were used in a 7 × 4 incomplete block design to determine the effects of cottonseed meal (CSM; 43.9% CP, 82.9% RDP) or dried distillers' grains (DDG; 27.5% CP, 43.6% RDP) supplementation on rice straw utilization (47 g/kg CP and 681 g/kg NDF). Treatments consisted of a negative control receiving no supplement (control) and 3 levels (60, 120, and 180 mg N/kg BW) of either CSM or DDG. Periods were 14 d with 8 d for adaptation and 6 d for data collection. Steers had ad libitum access to rice straw and were fed supplements daily. Increased supplementation resulted in a linear increase ( ≤ 0.06) in forage OM intake from 13.5 g/kg BW by controls to 15.5 and 16.1 g/kg BW for 180 mg N/kg BW of DDG and CSM, respectively. No differences between sources were observed ( = 0.84). Total digestible OM intake was increased by supplementation (linear,0.01) from 6.9 g/kg BW (control) to 10.0 and 11.2 g/kg BW for 180 mg N/kg BW of CSM and DDG, respectively. A greater response was observed for DDG ( = 0.05) due to greater provision of supplement (g DM/d) to achieve isonitrogenous treatment levels. Total tract OM digestion tended to increase with DDG supplementation (linear, = 0.08) but not CSM supplementation ( = 0.19). Both supplements did not affect NDF digestion (0.40) or calculated forage NDF digestibility (0.40). Ruminal ammonia concentrations peaked 4 h after supplementation/feeding with the greatest concentration (4.0 m) observed for 180 mg N/kg BW of CSM and the lowest concentration at 4 h observed in the control (0.8 m). Provision of CSM resulted in a linear increase (0.01) in average ruminal ammonia, in contrast to the quadratic response ( = 0.02) observed with DDG supplementation. Total VFA production linearly increased for both CSM and DDG supplementation ( = 0.09 and = 0.01, respectively). Protein supplements containing high and low levels of RDP were effective at improving intake and utilization of rice straw by Brahman steers.

Objectives were to determine the dietary inclusion level of NaOH in a dried distillers grains with solubles (DDGS)-based diet needed to improve growth performance and carcass characteristics of feedlot steers, and to determine the effects of NaOH treatment of DDGS on pattern of feed intake. Based on previous research regarding the acidity of DDGS, we hypothesized that using NaOH in cattle fed 50% DDGS-based diets to neutralize the acidity inherent in DDGS would improve growth performance of cattle but shift intake patterns. Angus-cross steers (120 total) were blocked into 2 BW blocks (light, initial BW = 211 ± 27 kg; and heavy, initial BW = 261 ± 27 kg) and allotted randomly within block to 20 pens (6 steers per pen; = 30). Pens within block were assigned randomly to 1 of 4 dietary treatments: 1) 50% DDGS, untreated; 2) 50% DDGS, treated with 0.5% NaOH (DM basis); 3) 50% DDGS, treated with 1.0% NaOH (DM basis); or 4) 50% DDGS, treated with 1.5% NaOH (DM basis). The remainder of the diets contained 20% dry-rolled corn, 20% corn silage, and 10% mineral and vitamin supplement, on a DM basis. Cattle were fed in a GrowSafe system. There were no effects ( ≥ 0.21) of increasing NaOH inclusion on final BW, ADG, or G:F. Increasing NaOH in the diet increased meal duration (linear; = 0.02) and tended to increase meal size (linear; = 0.06), but did not affect overall number of meals per day (linear; = 0.21) or overall DMI ( ≥ 0.40) for the course of the trial. Relative to cattle fed DDGS treated with 0, 0.5 or 1% NaOH (DM basis), steers fed DDGS treated with 1.5% NaOH consumed a larger proportion of their meals in the afternoon. However, regardless of treatment, all steers consumed 78% or more of their feed in the first 12 h post-feeding. There were no effects ( ≥ 0.19) of increasing NaOH inclusion on HCW, LM area, dressing percentage, KPH, back fat thickness, and marbling. There was a linear ( = 0.02) decrease in USDA Yield Grade (YG) 3 and a tendency ( = 0.09) for a quadratic response in carcasses grading USDA YG 4 as NaOH concentration increased in the diets; however, there were no other YG differences. The quality grade response followed marbling score and was not different ( ≥ 0.11) among treatments. Thus, there were no effects of feeding DDGS treated with NaOH on growing cattle performance or carcass characteristics. However, NaOH inclusion shifted the pattern of intake slightly to the afternoon hours, and increased meal duration without increasing the total number of meals per day.

Two studies evaluated effects of replacing corn with a pellet containing alkaline treated corn stover, dried distillers' grains plus solubles (DDGS), and distillers' solubles on total tract digestion and performance of finishing cattle. Experiment 1 used 4 ruminally fistulated steers in a 4 × 6 Latin rectangle to evaluate total tract digestion. Treatments consisted of a control (CON) containing 50.3% dry-rolled corn (DRC), 40% modified distillers' grains plus solubles (MDGS), and 5% untreated corn stover. The next 2 treatments replaced 25% DRC (DM basis) with either a CaO-treated stover pellet (STOVPEL) or a pellet consisting of 64% CaO-treated corn stover, 18% DDGS, and 18% corn distillers' solubles (COMBPEL). The last treatment replaced 25% DRC with a mixture of feeds: 10% treated stover pellet, 10% DDGS, and 5% distillers' solubles (COMB). Experiment 2 used 336 crossbred steer calves (301 ± 25 kg initial BW) in a 2 × 3 + 1 factorial to evaluate effects of replacing corn with a pellet containing 64% CaO-treated corn stover, 18% DDGS, and 18% corn distillers' solubles on finishing performance. Factors included level of MDGS (20 or 40%) and pellet inclusion (10, 20, or 30%). The CON diet contained a 50:50 blend of DRC and high-moisture corn and 40% MDGS. All diets contained 5% wheat straw and 4% dry meal supplement. In Exp. 1, no differences ( ≥ 0.50) were observed between the CON, STOVPEL, COMB, or COMBPEL treatments for DM (76.5, 75.4, 72.5, and 78.0%, respectively; SEM 2.5) or OM (79.1, 79.7, 75.7, and 80.5%, respectively; SEM 2.4) digestibility. In Exp. 2, a linear increase ( = 0.03) in DMI was observed as pellet inclusion increased from 0% in the CON (10.6 kg/d [SE 0.13]) to 30% (11.0 kg/d [SE 0.13]) in treatments containing 40% MDGS. A quadratic response ( = 0.03) in DMI was observed as pellet inclusion increased in diets containing 20% MDGS due to greater DMI of the 20% pellet treatment. A linear decrease ( = 0.03) in G:F was observed as the level of pellet inclusion increased from 0 (0.182 [SE 0.02]) to 30% (0.175 [SE 0.02]) in diets containing 40% MDGS. In diets containing 20% MDGS, no differences ( ≥ 0.22) in G:F were observed as pellet inclusion increased from 10 to 30%. In conclusion, replacing up to 20% of corn (DM basis) in diets containing 20% MDGS had minimal impact on performance. Conversely, up to 30% of corn could be replaced in diets containing 40% MDGS with little impact on performance.

Two experiments were conducted to determine the efficiency of utilizing SID Lys and Thr for whole-body protein retention (kSIDLys and kSIDThr) in pregnant gilts. In Exp. 1, 45 gilts (158.0 ± 8.0 kg at day 39.4 ± 1 of gestation) in 2 groups were used in a 3-period nitrogen (N)-balance study. Gilts were assigned to 1 of 4 diets set to provide 60, 70, 80, and 90% of predicted daily SID Lys requirement for protein retention (NRC, 2012) in each of early (day 41 to 52, 10.44 g/d), mid- (day 68 to 79, 9.60 g/d), and late gestation (day 96 to 107, 16.04 g/d). Diets contained 3,300 kcal ME/kg and 11.6% CP; given at a rate of 2.13 kg/d in early and mid-gestation and at 2.53 kg/d during late gestation. The 12-d balance period (7-d adaptation; 5-d urine and fecal collection) was based on total urine collection using urinary catheters and determination of fecal N digestibility using indigestible marker. The SID Lys required for whole-body protein retention was estimated using the NRC (2012) model and the predicted Lys content of each gestation pool. Lysine efficiency at each diet Lys level was calculated as the ratio of daily Lys retention and SID Lys intake. The linear and quadratic response in whole-body N and Lys retention and Lys efficiency for each balance period was determined. The kSIDLys was determined from the slope generated by regressing whole-body Lys retention vs. SID Lys intake, with y-intercept set to 0. In Exp. 2, 45 gilts (165.7 ± 13.6 kg at day 39.1 ± 2 of gestation) were assigned to 1 of 4 diets set to provide 60, 70, 80, and 90% of the predicted daily SID Thr requirement for protein retention in each of early (6.46 g/d), mid- (6.05 g/d), and late gestation (9.75 g/d). Animal management, N-balance procedure, data collection and calculation, and statistical analyses were patterned from Exp. 1. In early and mid-gestation, whole-body N retention, as well as Lys and Thr retention, was not affected by the dietary SID Lys and Thr. In late gestation, there was a linear increase (P < 0.001) in whole-body N, Lys and Thr retention. The kSIDLys and kSIDThr in late gestation were determined to be 0.54. The lack of response in whole-body protein retention in early and mid-gestation may in partly reflect excess Lys and Thr intake. Lysine and Thr efficiency calculated at the lowest dietary Lys and Thr was 0.49 and 0.32 in early gestation and 0.61 and 0.52 in mid-gestation, respectively. Based on the available evidence, kSIDLys and kSIDThr do not appear to be constant throughout gestation.

Amino acid requirements of sows may change from early to late gestation due to the accelerated growth of products of conception after d 70 of pregnancy. The objective of this study was to determine the Trp requirement, Phe kinetics, and energy expenditure in early (d 35 to 53) and late (d 92 to 111) pregnancy using the indicator amino acid oxidation method and indirect calorimetry. The same 6 second parity sows were fed 6 diets in a Latin square design in both early and late pregnancy. The diets based on corn, corn starch, and sugar provided 20 to 120% of the current recommended Trp intake (2.5 g/d) in early pregnancy and 60 to 180% in late pregnancy. Feed allowance was constant for each sow at 2.41 kg/d (SE 0.029). Expired air and blood were collected every 30 min for 5 1/2 h. After three 30-min periods to determine background (13)C enrichment in expired CO2 and plasma Phe, L[1-(13)C]Phe was given orally at a rate of 2 mg/(kg BW · h) with 8 1/2 hourly meals. Expired air and plasma were analyzed for (13)CO2 and (13)C-Phe enrichment, respectively. Requirements were determined as the breakpoint of 2-phase linear models. Sows grew from 167.7 kg (SE 3.93) at breeding to 211.9 kg (SE 5.18) post-farrowing and had litters of 14.5 piglets (SE 0.43) weighing 19.0 kg (SE 1.41) at birth. The Trp requirement was 1.7 g/d (SE 0.29, P = 0.001) in early pregnancy and 2.6 g/d (SE 0.37, P = 0.013) in late pregnancy, or 0.7 g/kg and 1.1 g/kg diet of total Trp, respectively, for a feed allowance of 2.4 kg/d. The Trp requirement in late pregnancy tended (P = 0.056) to be greater than in early pregnancy. Quantitative Phe kinetics were not affected by Trp intake except for a quadratic response of Phe oxidation and retention (P < 0.1) to Trp intake in early pregnancy. In late pregnancy, sows oxidized less Phe and retained more Phe (P = 0.001) than in early pregnancy, indicating that young, growing pregnant sows increase the efficiency of utilizing AA in late pregnancy to maintain protein synthesis in both maternal and fetal tissues. Oxidation and body protein breakdown contributed less to Phe flux in late than early pregnancy while protein synthesis contributed more (P < 0.01). Heat production and energy retention were not affected by Trp level or stage of gestation. To meet both energy and AA requirements in late gestation, a phase feeding program with 2 diets is recommended. The feed allowance in late pregnancy should be greater than in early pregnancy to account for the increased energy expenditure.

The effects of dietary protein content on the rates of gain and protein deposition were studied in Iberian (IB) × Duroc (DU) 50:50 barrows at 2 stages of growth [10.6 ± 0.2 (n = 28) and 60.0 ± 0.4 (n = 24) kg initial BW]. Two feeding, digestibility, and N-balance trials were performed. At each stage of growth, they were allocated in individual pens and given restrictedly (at 0.9 × ad libitum intake) one of 4 pelleted diets of similar energy concentration (13.8 to 14.5 MJ ME/kg DM), formulated to provide 4 different (ideal) CP contents (236, 223, 208, and 184 g CP/kg DM in the first trial, and 204, 180, 143, and 114 g CP/kg DM in the second trial). Feed allowance was offered in 2 daily equal meals. The average concentration of Lys was 6.59 ± 0.13 g /100 g CP for all diets. Whatever the stage of growth, average daily BW gain and gain to feed ratio were unchanged by increases in dietary CP content (477 ± 7 and 1,088 ± 20 g, and 0.475 ± 0.027 and 0.340 ± 0.113, respectively, in the first and second trial). In pigs growing from 10 to 27 kg BW, the average rate of N retention increased linearly (P < 0.01) on increasing the protein content in the diet up to a break point, so a linear-plateau dose response was observed. Pigs fed diets providing 208 to 236 g/kg DM did not differ in rate of protein deposition (PD). A maximum value of 87 (13.93 g N retained × 6.25) g PD/d was obtained when the diet supplied at least 208 g CP/kg DM. The broken-line regression analysis estimated dietary CP requirements at 211 g ideal CP (15.2 g total Lys)/kg DM. In the fattening pigs, there was a quadratic response (P < 0.01) in the rate of N retention as dietary CP content increased. Maximum N retention (18.7 g/d) was estimated from the first derivative of the function that relates the observed N retained (g/d) and dietary CP content (g/kg DM). This maximum value would be obtained by feeding a diet containing 185 g ideal CP (13.3 g total Lys)/kg DM and represents the maximum capacity of the IB × DU 50:50 pigs for protein accretion (i.e., 117 g PD/d). Consequently, cross breeding of IB dams with Duroc sires alters the metabolic response to dietary CP supply by increasing the potential of the crossbred to accrete protein and by modifying the pattern of PD response with BW.

Distillers grains and distillers solubles are by-products of grain fermentation used to produce ethanol and contain greater concentrations of NDF and ADF, compared with other grains and concentrates they replace in feedlot diets. Typical finishing diets in the United States contain 8.3% and 9.0% roughage. Therefore, it is plausible that the dietary concentration of roughage can be altered when distillers grains are included in feedlot diets. The effects of roughage concentration in dry-rolled, corn-based diets containing wet distillers grains with solubles (WDGS) were evaluated in steers (n = 128; initial BW = 339 kg), using Calan gates. Each diet was based on dry-rolled corn and contained 25% WDGS with coarsely ground alfalfa hay (AH), replacing corn at 2% (AH-2), 6% (AH-6), 10% (AH-10), and 14% (AH-14) of DM. Feed offered was recorded daily, orts were measured weekly, and BW was measured on d 0, 1, 35, 70, 105, 140, 174, and 175. After commercial harvest and chilling, carcasses were evaluated on-line with a beef carcass grading camera to assess marbling and yield grade traits. The data were analyzed using the Mixed Procedure of SAS, in which contrast statements were used to separate linear and quadratic effects of AH inclusion. Decreasing concentrations of AH in the finishing diet resulted in a tendency for a quadratic response (P = 0.07) in final BW, where BW increased from 2 to 6% AH inclusion but then decreased from 6 to 14% inclusion. Similarly, ADG from d 0 to end responded quadratically (P < 0.01), in which ADG increased from 2 to 6% yet subsequently decreased from 6 to 14% AH inclusion. Dry matter intake from d 0 to end increased linearly (P = 0.02) as AH inclusion increased in the diet, whereas G:F increased from 2 to 6% AH inclusion and then decreased linearly (P < 0.01) from 6 to 14% AH inclusion. Concentration of AH in the finishing diet did not affect HCW, marbling score, or the proportion of cattle grading USDA choice (P ≥ 0.18). However, dressing percent and LM area did respond in a quadratic manner (P < 0.02), in which they decreased from 2 to 10% AH inclusion and increased from 10 to 14% AH in the diet. Yield grade and adjusted 12th rib fat responded quadratically (P < 0.01), in which both increased from 2 to 6% AH inclusion and decreased from 6 to 14% inclusion. Analysis of responses of G:F and ADG on AH predict the apex at 3% and 7% for G:F and ADG, respectively, when fed in diets containing 25% WDGS.

Four experiments were conducted to evaluate RUP content and digestibility for smooth bromegrass, subirrigated meadow, upland native range, and warm-season grasses. Samples were collected from esophageally cannulated cows or ruminally cannulated steers. Forages were ruminally incubated in in situ bags for durations of time based on 75% of total mean retention time, which was based on IVDMD and rate of passage calculations. One-half of the bags were duodenally incubated and excreted in the feces, and NDIN was analyzed on all bags for RUP calculations. Crude protein was numerically greater early in the growing cycle for grasses compared with later as grasses matured (P ≤ 0.32). The RUP was 13.3%, 13.3%, and 19.7% of CP for smooth bromegrass, subirrigated meadow, and upland native range, respectively. These values tended to be lower early in the growth cycle and increased (linear P ≤ 0.13) as forages matured for warm-season grasses and subirrigated meadows. Because both CP and RUP content change throughout the growing season, expressing RUP as a percentage of DM gives more consistent averages compared with RUP as a percentage of CP. Coefficient of variation values for RUP as a percentage of DM averaged 0.21 over all 4 experiments compared with 0.26 for RUP as a percentage of CP. Average RUP as a percentage of DM was 2.03%, 1.53%, and 1.94% for smooth bromegrass, subirrigated meadow, and upland native range, respectively. Total tract indigestible protein (TTIDP) linearly increased with maturity for subirrigated meadow samples (P < 0.01). A quadratic response (P ≤ 0.06) for TTIDP was observed in smooth bromegrass and warm-season grass samples. Digestibility of RUP varied considerably, ranging from 25% to 60%. Subirrigated meadow, native range, and smooth bromegrass samples tended to have linear decreases (P ≤ 0.11) in RUP digestibility throughout the growing season. The amount of digested RUP was fairly consistent across experiments and averages for smooth bromegrass, subirrigated meadow, and upland native range were 0.92%, 0.64%, and 0.49% of DM, respectively. Warm-season grasses in Exp. 2 had greater RUP (4.31% of DM) and amount of RUP digested (2.26% of DM), possibly because of cattle selecting for leadplant that contains more CP than the grasses. Forages can vary in CP, RUP, TTIDP, and RUP digestibility depending on the forage type, year, and time within year, but RUP digestibility is likely less than what previous sources have reported.

The aim of this research was to assess the effect of temperature intensity and variation both throughout the day and between days within different periods of the reproductive cycle and the lactation of the rabbit. This information would help in establishing optimal patterns of environmental temperature control in rabbitries. The traits analyzed were total number of kits born (TB), number of kits alive at weaning (NW), and average individual weight at weaning (AvgWW). For each trait, several mixed models were fi tted to the data, differing only in the number and type of tem- perature descriptors included in the vector of fi xed effects. Those descriptors were the average daily mean, maximum, and range of temperatures (AvgTmean, AvgTmax, and AvgRg, respectively) and the CV of dai- ly mean temperature (CVTmean). All were calculated for periods in which important physiological processes related to the studied traits occur. High environmental temperature was found to have a detrimental effect on prolifi cacy and preweaning growth of the kits. When the average daily mean reached 20°C, it produced a linear decay of TB of around 0.1 kit/°C. The most sen- sitive period for TB could cover from spermatogenesis to embryo implantation. However, the high correlation between descriptors calculated for different periods makes it diffi cult to assign an effect to each specifi c period and therefore to the specifi c physiological pro- cess occurring in that period. The effect on NW was smaller and quadratic, with an optimum value between 18°C and 21°C. Weaning weight was the most strongly affected trait similar to NW. It also showed a quadratic response to AvgTmean, with an optimum value in the same temperature interval as NW and a strong decline in weaning weight with temperatures higher than 21°C (-14 g/°C). There were no differences on the effect of heat at different stages of lactation on NW and AvgWW. The impact of high environmental temperatures on prolifi cacy is alleviated if a drop in temperature is pro- duced during the day. Thus, the effect of AvgRg was relevant and positive for TB and NW. However, it had a quadratic negative effect for AvgWW at late lactation. The temperature variation between days within a period has a positive effect on TB and AvgWW but a negative effect on NW when it is produced at middle lactation, whereas there is no effect at other stages of lactation.

A summer study and a winter study were conducted using an incomplete factorial structure in a complete randomized design. Within season, the factors studied were 1) type of diet, which included 2 levels of ME, classified as either concentrate (3.04 Mcal of ME/kg) or roughage (2.63 Mcal of ME/kg) diets, and 2) daily ME intakes (MEI) of 11, 18, and 25 Mcal of ME/d for the roughage diets and 18, 25, and 32 Mcal of ME/d for the concentrate diets. In Exp. 1 (sum- mer study), 30 steers (5 steers/treatment combination) were used to collect tympanic temperatures (TT). In Exp. 2 (winter study), 24 steers (4 steers/treatment combination) were used to collect TT. Mean TT was 0.3°C greater for summer than winter (38.9 vs. 38.6°C, respectively; P < 0.05). Steers fed diets based on con- centrate tended to display greater TT than steers fed diets based on roughage. Season × diet × hour inter- actions were found for TT (P = 0.01). In the winter, greater TT (P < 0.05) were found from 0900 to 1400 h when an equal amount of MEI was derived from a concentrate-based vs. roughage-based diet. In cattle fed roughage-based diets during the summer, TT = 38.63 + 0.0114·MEI, whereas for cattle fed concen trate-based diets, TT = 38.69 + 0.0114·MEI. During the win ter, for cattle fed a roughage-based diet, TT = 37.65 + 0.0856·MEI − 0.0018·MEI 2 , whereas for cattle fed a concentrate-based diet, TT = 35.37 + 0.2635·MEI − 0.0051·MEI 2 . In summary, results demonstrate that in- creases in the energy of the diet resulted in increases in TT. However, the response was dependent on season of the year, with a linear response in TT for summer and a quadratic response during winter.

Whole field peas were fed at 0, 10, 20, and 30% of DM to 139 yearling steers (British cross; 409 ± 31 kg of initial BW) for a 119-d finishing period. Carcass data and Choice grade strip loins (n = 98) were collected from a commercial abattoir in Lexington, Nebraska. Consumer sensory and Warner-Bratzler shear force analyses were performed on 2.5-cm strip steaks. No differences (P ≥ 0.17) were observed in final BW, ADG, DMI, and G:F of steers. Likewise, no differences (P ≥ 0.23) were observed for HCW, LM area, fat thickness at the 12th rib, yield grade, and marbling scores. However, KPH responded quadratically to increasing dietary amount of field peas (P = 0.02). Regarding the sensorial analysis, feeding peas linearly increased subjective tenderness (P < 0.01) and led to a quadratic response of overall like ratings (P = 0.01) and flavor like ratings (P = 0.12). Feeding peas did not alter (P ≥ 0.64) juiciness, but decreased shear force values linearly when quantities were increased (P = 0.02). These data suggest that feeding peas does not affect steer performance or carcass characteristics differently from dry-rolled corn, but does improve objective and subjective tenderness, overall desirability, and flavor of beef. Field peas could be fed to cattle and give positive attributes to the quality of the meat up to 30% inclusion in the diet.

British and British x Continental steers (n = 560; initial BW = 339.4 ±1.76 kg) were used in a serial slaughter study with a completely random design to evaluate effects of zilpaterol hydrochloride (ZH; 8.33 mg/kg of dietary DM basis) on performance and carcass characteristics. Treatments were arranged in a 4 x 4 factorial (112 pens; 7 pens/treatment; 5 steers/ pen) and included duration of ZH feeding (0, 20, 30, or 40 d before slaughter plus a 3-d ZH withdrawal period) and days on feed (DOF) before slaughter (136, 157, 177, and 198 d). No duration of ZH feeding x slaughter group interactions were detected for the performance measurements (P > 0.10). Final BW did not differ (P = 0.15) between the 0-d group and the average of the 3 ZH groups, but ADG was greater for the average of the 3 ZH groups during the period in which ZH diets were fed (P 0.10) were detected for carcass characteristics. Regardless of the duration of ZH feeding, cattle fed ZH had greater HCW (P < 0.01), greater dressing percent (P < 0.01), less 12th-rib fat (P < 0.01), larger LM area (P < 0.01), less KPH (P = 0.03), and lower yield grade (P < 0.01) than the 0-d cattle. The 0-d group had greater marbling scores (P < 0.01) than cattle fed ZH diets, with a tendency for a linear decrease in marbling score (P = 0.10) as duration of ZH feeding was extended. A greater percentage of carcasses in the 0-d group graded USDA Choice or greater (P < 0.01) than in the 3 ZH groups, whereas the percentage of Select carcasses was greater (P = 0.01) for the 3 ZH groups. From d 0 to end (P = 0.04) and during the last 43 d on feed (P < 0.01), ADG responded quadratically to DOF before slaughter. No differences were detected among slaughter groups for DMI for the entire trial period; however, a quadratic response (P = 0.02) was observed for the final 43 d before slaughter. A quadratic response was also detected for the final 43 d before slaughter (P < 0.01) and from d 0 to end (P = 0.02) for G:F. Final BW, HCW, dressing percent, and 12th-rib fat increased linearly (P < 0.01) as DOF before slaughter increased. Our results indicate that no substantial effects on performance and carcass measurements were observed when ZH was fed for 30 or 40 d as opposed to 20 d, and that effects of ZH generally did not interact with DOF before slaughter.

The objective of the present study was to examine the effects of increasing the number of heifers per concentrate feeding place on performance, behavior, welfare indicators, and ruminal fermentation of feedlot heifers. Seventy-two Friesian heifers were used in a factorial arrangement, with 3 treatments and 3 blocks of similar BW. Treatments consisted of 2 (T2), 4 (T4), or 8 (T8) heifers per each place in the concentrate feeder (8 heifers/pen). Concentrate and straw were fed at 0830 h in individual feeders that allowed ad libitum consumption. During 6 periods of 28 d each, DMI and ADG were measured, and blood and rumen samples were taken. Fecal glucocorticoid metabolites and behavior were measured at periods 1, 3, and 6. Final BW, ADG, and G:F were not affected by treatments. Variability in final BW among heifers sharing the same pen tended to increase (P = 0.06) and concentrate intake decreased linearly as competition increased. The proportion of abscessed livers responded quadratically, being 8, 4, and 20% for T2, T4, and T8, respectively. Concentrate eating time decreased (P = 0.001) and eating rate increased (P = 0.05) linearly, whereas the variability between pen mates in concentrate eating time was greatest in T4 and T8. Increasing competition resulted in a quadratic response (P = 0.02) in daily lying time (greatest in T2), whereas standing time increased linearly (P = 0.02). The number of displacements among pen mates from the concentrate feeders, as well as the total sum of displacements, increased linearly (P < 0.05) with increasing competition. The pen average of fecal glucocorticoid metabolites was not affected by treatments (P ≥0.16) but the pen's maximum concentration responded quadratically (P < 0.001), being greatest in T8, with dominant heifers being the most affected. Serum haptoglobin concentration increased linearly (P = 0.05) with competition, particularly within the most subordinate heifers. Increased competition reduced (P < 0.05) ruminal pH only in periods 1 and 2 and increased ruminal lactate (P = 0.02). Increasing competition at the concentrate feeders increased the variability in final BW but performance was not affected. Detrimental effects on animal welfare might be deduced from the altered feeding behavior, reduced resting time, and increased aggression. Ruminal lactate and blood haptoglobin indicate that the risk of rumen acidosis might increase with competition, whereas liver abscesses increased at 8 heifers per feeder.

Seventy-two Friesian calves (BW = 102.0 +/- 1.8 kg) were bought from a commercial calf farm and distributed to a factorial arrangement of treatments in a complete block design with 3 treatments and 3 blocks of similar fasted BW to study the effect of increasing the number of feeding places per pen on performance, behavior, and welfare indicators during the 4 wk after arrival. Treatments consisted of 1 (T1), 2 (T2), or 4 (T4) concentrate feeding places/pen (8 calves/pen). Concentrate and straw were fed at 0830 in individual feeders, and animals were allowed to consume on an ad libitum basis. Dry matter intake and ADG were recorded weekly, and blood samples were taken on d 0 (before transport), 7, 14, 21, and 28. Time spent in maintenance activities, number of displacements between calves, and the angular dominance value (ADV) were registered at wk 1 and 3 after arrival. Increasing the number of feeding places per pen resulted in a quadratic response of concentrate and total DMI, ADG, and BW during the 28-d period, with T1 showing the lowest values. Straw intake and the within-pen SD of ADG tended to decrease linearly (P = 0.10) as the number of feeding places per pen increased. During the 4-wk receiving period, and particularly on d 7 after arrival, serum NEFA responded quadratically, with T1 and T2 calves showing the greatest values. With increasing number of concentrate feeders, the average time spent lying increased (P = 0.001), standing time decreased linearly (P = 0.001), and the diurnal feeding pattern changed (concentrate eating time increased but straw eating time decreased during peak feeding times, P 0.20). Increasing social pressure at the concentrate feeders beyond the threshold of 4 heifers per feeder had a negative effect on performance. Within-pen variability in performance increased linearly as a consequence of greater effects of social dominance. Physiological indicators of welfare were not consistently affected by treatments.

Two experiments were conducted to refine the Ile needs in 7- to 11-kg pigs. In Exp. 1, 1,680 pigs were fed a 1.25% digestible Lys diet containing 7.5% spray-dried blood cells (as-fed basis) with supplemental crystalline Ile (0.06% increments) to generate seven levels of apparent digestible Ile (0.47 to 0.83%). There were 12 replicates of each treatment with 20 pigs per pen, and treatments were imposed at an initial BW of 7 kg and continued for 16 d. Responses in ADG, ADFI, G:F, and plasma urea nitrogen (PUN) were quadratic (P < 0.01) over the 16-d period. Data were fitted to both a single-slope broken line and a quadratic fit, and when the quadratic response curve was superimposed on the broken line, the points at which the quadratic curve first intersected the plateau of the broken line occurred at 0.70, 0.73, 0.66, and 0.65% digestible Ile for ADG, ADFI, G:F, and PUN, respectively. Using the ADG and ADFI obtained at this intersection point resulted in an estimate of 9.1 mg of digestible Ile per gram of weight gain. In Exp. 2, 1,840 pigs were fed similarly composed diets, except that digestible Lys was lowered in six diets to 1.10% by decreasing soybean meal. Crystalline Ile was supplemented at 0.09% increments to generate six levels of digestible Ile (0.37 to 0.83%). A seventh diet contained 1.25% digestible Lys by supplementing the 0.83% digestible Ile diet with 0.19% L-Lys HCl to verify that 1.10% digestible Lys was deficient for these pigs. There were 12 replicates of each treatment with 22 pigs per pen, and treatments imposed at an initial BW of 7 kg and continued for 16 d. Supplementation of Lys to the 0.83% digestible Ile diet (1.10 vs. 1.25% digestible Lys) did not affect ADG (260 vs. 264 g/d, P = 0.60) and ADFI (359 vs. 343 g/d, P = 0.20), whereas G:F (725 vs. 774 g/kg, P < 0.01) was improved by increasing dietary Lys. Responses in ADG, ADFI, and G:F to the first six diets were quadratic (P < 0.01) over the 16-d period. The points at which the quadratic curve first intersected the plateau of the broken line occurred at 0.686, 0.638, and 0.684% digestible Ile for ADG, ADFI, and G:F, respectively. Using the ADG and ADFI obtained at this intersection point results in an estimate of 9.9 mg of digestible Ile per gram of weight gain. These results suggest that although the percent digestible Ile requirement and digestible Ile:Lys ratio for starter (7 to 11 kg) pigs may be higher than 1998 NRC recommendations, the requirement may be lower than current recommendations when taking gain and feed intake into account.

This study was conducted to examine whether Cu could exert its growth-promoting effect when injected, rather than being fed, and thus bypass the gastrointestinal tract. In two 18-d experiments, pigs were injected every 2 d with a Cu histidinate or histidine solution. Amounts of Cu injected were calculated to simulate varying absorption rates in pigs fed 250 ppm of dietary Cu. In Exp. 1, 44 pigs were randomly assigned to four groups of 11 pigs each. Pigs were injected with four levels of Cu histidinate (0, 5, 10, and 15% estimated apparent absorption coefficients based on calculated feed intake). Average daily gain responded quadratically (P < .05) to levels of Cu histidinate; maximum growth was seen in the 5% group. At d 6, serum mitogenic activity also exhibited a similar quadratic response (P < .05). In Exp. 2, estimated Cu absorptions of 0, 2, 4, 6, and 8% were tested. Forty-five pigs were randomly assigned to five groups of nine pigs each and injected as in Exp. 1. Both ADG and serum mitogenic activity displayed a quadratic response (P < .05); the maximum response was seen in the 4% group. Liver Cu content, superoxide dismutase activity, and serum Cu concentrations were linearly increased (P < .05) with increasing dosage of Cu in both Exp. 1 and 2. Also, brain Cu content linearly increased (P < .05) with increasing dosage of Cu in both Exp. 1 and 2. Also, brain Cu hormone mRNA concentrations in Exp. 2 were not significantly influenced by treatments.(ABSTRACT TRUNCATED AT 250 WORDS)

The effects of dietary electrolyte balance (DEB; mEq of Na + K - Cl/100 g of DM) on performance and acid-base status of growing cattle consuming a corn silage-based diet were established using 120 Angus (n = 60) and Angus crossbred (n = 60) steers (247 +/- 2.4 kg). Treatments consisting of 0, 15, 30, or 45 mEq of DEB/100 g of DM were obtained by varying NH4Cl and NaHCO3. Average daily gain showed a linear increase (P < .05) with increased DEB for the first 28 d and a quadratic response (P < .05) for the remainder of the 84-d study. Average daily feed intake was not affected by DEB the first 28 d. However, feed intake over the entire feeding period showed a linear increase with increasing DEB (P < .01). On d 28, plasma Na, K, and Mg were not affected by DEB, whereas Ca followed a quadratic pattern (P < .10). On d 84, plasma Na and Mg decreased linearly with increasing DEB. Plasma Cl concentrations decreased linearly (P < .01) with increased DEB on d 28 and 84. On d 28 arterial blood pH and HCO3 increased linearly (P < .05) with increased DEB, whereas ionized Ca, pCO2, and pO2 were unchanged. On d 84, arterial blood pH (P < .10), HCO3 (P < .05), and ionized Ca (P < .10) increased quadratically, whereas pO2 and pCO2 were not affected by treatment. Ruminal pH increased linearly (P < .05) with increased DEB on d 28 but showed no differences on d 84. These data indicate that DEB affects performance and systemic values in growing feedlot cattle. A DEB in the range of 15 to 30 mEq seemed to provide normal homeostasis of growing steers fed a corn silage-based diet.

Three experiments were conducted to determine the value of pearl millet grain, grown at either Purdue University or the University of Nebraska, as a substitute for corn in the diets of young pigs. In Exp. 1, 24 crossbred barrows, average initial weight of 20.7 kg, were used to evaluate nutrient digestibility of both sources of pearl millet compared with corn. Nitrogen digestibility was similar (P.05) for corn and both sources of pearl millet. Energy and DM digestibilities were highest (P.01) for corn, resulting in corn having a higher (P.01) DE and ME value. Two 28-d feeding studies were conducted to evaluate the growth response of pigs when 0, 25, 50, 75, or 100% of corn was replaced with pearl millet (Exp. 2, Nebraska millet; Exp. 3, Purdue millet) and an equal-weight basis in nursery (Exp. 2) and growing (Exp. 3) diets. Experiments were designed as 2 x 5 factorials of sex and dietary treatment. In Exp. 2, 60, 10-kg crossbred pigs (barrows:gilts, 1:1) were used. During the 14-d period after weaning, and over the entire 28-d experimental period, no effect (P.05) of dietary treatment on growth rate or feed intake was observed. However, from d 14 to 28, a quadratic response (P.05) in growth rate and feed intake were observed from incremental substitution of pearl millet for corn. In Exp. 3, 50 crossbred pigs (barrows:gilts, 1:1) with an average initial weight of 24.3 kg were used. Rate of BW gain, feed intake, and gain:feed ratio were not affected (P.05) by dietary treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Four experiments were conducted to characterize the interactions between fumaric (FA), malic (MA), or citric acid (CA) and NaHCO3. In two experiments, seven diets were formulated containing 2.5% FA, MA, and CA, with or without 2.3, 1.9, or 1.4% NaHCO3, respectively, as well as a control diet (no addition of organic acids or NaHCO3) for 28-d-old pigs (Exp. 1, corn-soy protein concentrate-based diet) and 1-wk-old chicks (Exp. 4, corn-soy-based diet). In Exp. 1, at 2 and 4 wk, the FA+NaHCO3 treatment resulted in greater average daily gain (ADG) and feed intake (ADFI) compared with the control (P < .05). In Exp. 2, 28-d-old pigs were fed corn-soy diets with .9, 1.6, and 2.3% NaHCO3 in addition to 2.5% FA. After wk 2, there was a quadratic response in ADG (P < .08) and ADFI (P < .05) when increasing levels of NaHCO3 were added to the diet. This was true at wk 4 for both ADG and ADFI (P < .05). In Exp. 3, finishing pigs were fed corn-soy diets containing 2.5% FA or 2.5% FA + 2.3% NaHCO3 added to a control diet. No effect (P < .05) of FA or NaHCO3 was observed. In Exp. 4, the combination of CA+NaHCO3 or MA+NaHCO3 was superior to FA+NaHCO3 for ADG (P < .08) and ADFI (P < .05) when fed to young chicks.

Three experiments were conducted to evaluate influences of supplemental alfalfa quality on intake and use of low-quality meadow grass roughages (MG) by beef cattle. In Exp. 1, 15 steers (250 kg) were assigned to three treatments: 1) MG (5.2% CP), no supplement; 2) MG plus high-quality alfalfa (18.8% CP); and 3) MG plus low-quality alfalfa (15.2% CP). High- and low-quality alfalfa supplements were fed at .45 and .55% BW, respectively. Total DMI was greater (P.01) for alfalfa-supplemented steers than for MG. Likewise, intake of digestible DM, DM digestibility (DMD), and ruminal ammonia level were greater (P.01) for supplemented steers. In Exp. 2, 96 pregnant Hereford x Simmental cows (537 kg; body condition [BC] score 4.86) were assigned to the same treatments as in Exp. 1. For d 0 to 42, cows grazed on 19.1 ha of stockpiled MG (4,539 kg/ha; 6.8% CP), whereas, on d 43 to 84, cows received MG hay (5.2% CP). Supplemented cows gained more BW (P.01), BC score (P.01), and had heavier calf birth weight (P.01) than nonsupplemented cows. However, there were no treatment effects (P.10) on cow cyclicity, pregnancy rate, or calving interval. In Exp. 3, 90 pregnant Angus x Hereford cows (475 kg; BC score 4.59) were assigned to three treatments: 16.1%, 17.8% or 20.0% CP alfalfa supplement, with levels of .63, .55, and .50% of BW, respectively. Weight gain and BC score for the 84-d study displayed a quadratic response (P.10), yet represented only 7 kg BW and .2 units of BC score. In conclusion, alfalfa hay supplementation was effective in increasing DMI and digestibility. However, alfalfa hay quality did not dramatically affect BW, BC score, and(or) calf birth weight, when fed on an isonitrogenous basis.

We examined the effects of six volatile compounds on alfalfa pellet consumption by lambs. In each experiment, 45 lambs were individually fed alfalfa pellets sprayed with a selected compound (camphor, limonene, cis-jasmone, beta-caryophyllene, borneol, or alpha-pinene) at one of five concentrations. Treatment concentrations were multiples (0, .5, 1, 2, and 10) of the concentration of a specific compound (X) that was related to differential herbivory of tarbush by livestock in previous studies. Treatments were applied to alfalfa pellets (.64 kg x lamb(-1) x d(-1), DM basis), and consumption was measured during a 20-min interval each morning for 5 d. Lambs were adapted to handling procedures and the pelleted diet (without treatments) for 10 d. Lambs were maintained and fed (approximately 4.5 to 5% of BW) as one group except during 20-min tests. A negative linear effect of treatment concentration on intake was observed for camphor (P < .02) and alpha-pinene (P < .01), and a quadratic response was detected for borneol (P < .02). The other three compounds had no discernible effect on consumption. Although volatile compounds generally had only minor influences on consumption, the negative influences of alpha-pinene and camphor concentrations on pellet consumption suggest that these monoterpenes may partially explain differential herbivory of individual tarbush plants by livestock.

Three experiments were conducted with 288 weanling pigs to determine the effects of sorbic acid (SA) added to dry (DSG), high moisture (HMSG) or reconstituted (RSG) sorghum grain diets on gains and feed conversion. Dietary treatments for Exp. 1 were: DSG with and without .1% SA; HMSG with .1% SA and RSG with .1% SA. The DSG diets were fed ad libitum. The HMSG and RSG diets were mixed fresh from oxygen-limiting storage every 3 and 7 d and were also fed ad libitum. Pigs fed RSG diets consumed more feed than those fed HMSG diets (P

Crossbred growing-finishing pigs (112 barrows, 48 gilts) were used to determine the effect of reducing excess dietary arginine, through feedstuff variation, on performance, carcass composition and plasma amino acid concentrations. Diets contained five, four, three or two times the NRC requirement for arginine. Lysine in all diets was formulated to be equal to NRC requirements, and all diets contained at least 100% of the NRC recommendations for all other essential amino acids. Initial weight, final weight and days on test for the grower phase were 26.7 kg, 44.2 kg and 28 d, respectively. Weight gain and gain/feed were not different among treatments but feed intake showed a quadratic response during the grower phase, being highest at four times the NRC requirement for arginine. Initial weight, final weight and days on test for the finisher phase were 44.2 kg, 96.9 kg and 67 d, respectively. Weight gain during the finisher phase and for the total experiment exhibited a quadratic response, being highest for the pigs fed the intermediate arginine levels. Gain/feed for the finisher phase followed the same trend as weight gain. Feed intakes for the finisher phase and total experiment were not different among treatments. Carcass data were collected on all barrows. There were no differences in hot carcass weight or adjusted average backfat among treatments. Loin eye area and percentage of lean decreased linearly as arginine level decreased in the diet. Plasma urea, arginine and orthinine concentrations decreased linearly with decreasing dietary arginine. Plasma lysine exhibited both a quadratic and a cubic response. The data indicate that reducing excess dietary arginine had little effect on performance or carcass composition and no consistent effect on plasma lysine of growing-finishing swine.

Five trials with steers new to the feedlot environment were conducted to determine the effects of one or two i.m. injections of selenium (Se) and(or) vitamin E (Vit E) on performance, health status and serum antibody response to Pasteurella haemolytica vaccination. In all trials, performance and average number of days sick per steer were not affected (P greater than .05) by single injection of Se and(or) Vit E. In Trial 1, 26 steers (avg initial wt 267 kg) were treated with 1) no Se or Vit E or 2) 25 mg Se (as Na2SeO3) plus 340 IU Vit E (as [d]-alpha-tocopheryl acetate). P. haemolytica serum immunoglobulin G (IgG) titers on d 7 and 14 were greater (P less than .05) for steers receiving 25 mg Se plus 340 IU Vit E. In Trial 2, 141 steers (avg initial wt 204 kg) were treated with 1) no Se or Vit E, 2) 25 mg Se, 3) 340 IU Vit E or 4) 25 mg Se plus 340 IU Vit E. Serum IgG titers were greater (P less than .05) only for Treatment 4 on d 6. Trial 3 was conducted using 107 steers and the same treatments as in Trial 2. By d 14, titers for treatment 4 were greater (P less than .05) than those for Treatments 1 or 3, but not greater than those for Treatment 2. In Trial 4, serum IgG titers were unaffected (P greater than .05) when 48 steers (avg initial wt 248 kg) were treated with 1) no Se or Vit E, 2) 25 mg Se plus 340 IU Vit E 14 d prior to shipping or 3) 25 mg Se plus 340 IU Vit E 14 d prior to shipping, plus repeat injection on day of arrival at the feedlot. In Trial 5, 107 steers were treated with 1) no Se or Vit E, 2) 25 mg Se plus 340 IU Vit E or 3) 50 mg Se plus 680 IU Vit E. Serum IgG titers increased linearly (P less than .01) due to treatment on d 7, 13 and 20 and a quadratic response (P less than .05) was observed on d 27. In these trials, serum antibody response to P. haemolytica vaccination was enhanced with the combination of Se and Vit E; however, performance and health status were not affected.