The Impact of Dietary Analyzed Calcium to Phosphorus Ratios and Standardized Total Tract Digestible Phosphorus to Net Energy Ratios on Growth Performance, Bone, and Carcass Characteristics of Pigs

A total of 2,184 pigs (PIC 337 × 1050; initially 27.3 lb) were used to evaluate the effects of feeding varying analyzed calcium to phosphorus (Ca:P) ratios at two levels of standardized total tract digestible (STTD) P:NE. Pens of pigs (26 pigs per pen) were assigned to 6 dietary treatments in a randomized complete block design with 14 pens per treatment. Diets consisted of two levels of STTD P:NE, including the PIC recommendation (1.8, 1.62, 1.43, 1.25, 1.10, and 0.99 g STTD P/Mcal NE from 25 to 50, 50 to 90, 90 to 130, 130 to 180, 180 to 230, and 230 to 280 lb, respectively); or 75% of the PIC recommendation, and 3 analyzed Ca:P ratios: 0.90:1, 1.30:1, and 1.75:1. Diets were corn-soybean meal-based and contained phytase (Quantum Blue G, AB Vista, Marlborough, Wiltshire, UK); 500 to 210 FTU/kg with release values from 0.13 to 0.07% STTD P. There was a Ca:P × STTD P:NE interaction (P \u3c 0.05) observed for average daily gain (ADG), feed efficiency (F/G), and final body weight (BW). For ADG and final BW, when feeding 75% of PIC STTD P recommendation, increasing the analyzed Ca:P ratio decreased ADG and final BW (linear, P \u3c 0.001). However, when feeding the PIC STTD P recommendation, increasing the analyzed Ca:P ratio tended to improve ADG and final BW (linear, P \u3c 0.10). For F/G, when feeding 75% of the PIC STTD P recommendation, increasing the analyzed Ca:P ratio tended to worsen F/G (linear, P \u3c 0.10), whereas in pigs fed diets that met PIC STTD P recommendations, increasing the analyzed Ca:P ratio tended to improve F/G in a quadratic (P \u3c 0.10) manner. Despite the interactions, pigs fed the PIC STTD P recommendations had increased ADG, final BW, and improved F/G compared to pigs fed 75% of PIC STTD P recommendations (P \u3c 0.001). In summary, pigs fed at PIC STTD P recommendations had improved overall ADG and F/G compared to pigs fed diets at 75% of PIC STTD P recommendations. Additionally, increasing the analyzed Ca:P ratio worsened ADG and F/G when STTD P was below PIC recommendations but had marginal impacts when adequate STTD P was fed

Effects of Feeding Increasing Standardized Ileal Digestible Lysine on Growth Performance of 26- to 300-lb PIC Line 800-Sired Pigs

The objective of this study was to evaluate the growth performance and economic returns of PIC 800 × 1050 pigs fed increasing SID Lys from approximately 26 to 300 lb. Pens of pigs were blocked by BW and randomly assigned to 1 of 5 dietary treatments in a randomized complete block design with 26 pigs per pen and 16 pens per treatment. Pens were provided 1 of 5 dietary treatments with increasing SID Lys at 85, 93, 100, 107, and 115% of current PIC recommendations within 6 different phases. Two base diets containing low Lys and high Lys were blended to meet target SID Lys levels for each treatment diet within phase. For the overall experimental period (d 0 to 143), feeding increasing SID Lys improved (linear, P ≤ 0.007) ADG and F/G, but did not impact ADFI (P \u3e 0.10). For carcass characteristics, a tendency (linear, P = 0.067) for increased HCW of pigs that were provided increasing SID Lys was observed. However, there was no evidence for differences (P \u3e 0.10) across treatments in carcass yield, backfat depth, loin depth, or carcass lean percentage. Increasing SID Lys of the diets increased (linear, P \u3c 0.001) feed cost and feed cost per lb of gain. There was no evidence of difference (P \u3e 0.10) in revenue for either ingredient price scenario, thus, feeding increasing levels of SID Lys reduced (linear, P \u3c 0.001) income over feed cost (IOFC) in both scenarios. The linear model (LM) served as the best fit for both growth and economic parameters. The LM model predicted maximum ADG and minimal F/G at levels greater than 115% of PIC’s current SID Lys recommendations. For IOFC, the LM model predicted maximum profitability at or below 85% of PIC’s current Lys recommendations. In conclusion, the optimal SID Lys level for PIC 800 × 1050 pigs from 26- to 300-lb depends upon the response criteria, with growth performance maximized at levels at or above 115% of PIC’s recommendation for SID Lys; however, economic responses were maximized at or below 85% of PIC’s current SID Lys recommendations

Effects of Standardized Ileal Digestible Threonine to Lysine Ratio on Growth Performance of PIC Line 337 × 1050 Pigs

The objective of this research was to evaluate the impact of varying SID Thr:Lys ratios on growth performance, removals, and mortality rates of late-nursery, grower, and finishing PIC 337 × 1050 pigs. In each experiment, pens of pigs were blocked by BW and randomly assigned to 1 of 5 dietary treatments in a randomized complete block design with 19 to 27 pigs per pen and 8, 7, and 7 replications per treatment in Exp. 1, 2, and 3, respectively. In Exp. 1, 987 pigs (initially 26.0 ± 0.70 lb) were used from 26 to 54 lb. In Exp. 2, 875 pigs (initially 95.5 ± 1.17 lb) were used from 95 to 155 lb. In Exp. 3, 824 pigs (initially 224.4 ± 1.85 lb) were used from 224 to 297 lb. Pens were randomly assigned to 1 of 5 dietary treatments with increasing SID Thr:Lys ratios at 53, 58, 62, 65, and 68% in Exp. 1 and 2, and 56.5, 60, 64, 68, and 72.5% in Exp. 3. Diets were corn-soybean meal-based. Diets with the lowest and highest Thr:Lys ratios were blended to achieve the target SID Thr:Lys treatments in each experiment. Between experiments, all pens of pigs were placed on a common diet for 23 (Exp. 1 and 2) and 32 d (Exp. 2 and 3) to provide opportunity for compensatory growth prior to initiation of the next experiment. In Exp. 1 (26 to 54 lb), ADG and final BW increased linearly (P ≤ 0.006) while ADFI, Thr intake/d, and Thr intake/kg of gain increased quadratically (P ≤ 0.001). Overall, F/G improved (quadratic, P ≤ 0.001) as Thr:Lys ratio increased. Additionally, Lys intake/d increased (quadratic, P \u3c 0.001) while Lys intake/ kg of gain decreased (quadratic, P\u3c 0.001) with increasing Thr:Lys ratio. The quadratic polynomial (QP) model predicted greater than 68% SID Thr:Lys was required for ADG from 26 to 54 lb, while a QP model suggested that minimum F/G was achieved at 62.1% SID Thr:Lys. In Exp. 2 (95 to 155 lb), ADG, final BW, Thr intake/d, and Thr intake/kg of gain increased (linear, P ≤ 0.05) and F/G improved (linear, P = 0.030) as dietary Thr:Lys increased. Moreover, Lys intake/kg of gain decreased (linear, P = 0.023) with increasing Thr:Lys ratio. For model analysis, QP models suggested optimum ADG and F/G were achieved at levels greater than 68% SID Thr:Lys. However, similar fitting broken-line quadratic (BLQ) and broken-line linear (BLL) models predicted no further improvement to F/G and ADG beyond 61 and 67% SID Thr:Lys, respectively. In Exp. 3 (224 to 297 lb), increasing SID Thr:Lys increased (linear, P ≤ 0.001) Thr intake/d and Thr intake/kg of gain. In addition, increasing SID Thr:Lys ratios tended (P ≤ 0.086) to quadratically increase (P≤ 0.086) ADFI and BW of pigs at the second marketing event. However, no other response criteria were impacted (P ≥ 0.10) by dietary Thr:Lys. Due to a lack of ADG and F/G responses, prediction models were not developed. In summary, these results suggest the optimal SID Thr:Lys level for 26- to 54-lb pigs is 62.1% for feed efficiency and greater than 68% for ADG. From 95 to 155 lb, the requirement was predicted at or above 61 and 67% SID Thr:Lys for F/G and ADG, respectively. However, with the variation in response criteria in Exp. 3 (224 to 297 lb), we were unable to statistically define a requirement estimate

Effects of Standardized Ileal Digestible Tryptophan to Lysine Ratio on Growth Performance of PIC Line 337 × 1050 Pigs

The objective of these experiments was to evaluate the impact of varying SID Trp:Lys ratios on growth performance, removals, and mortality rates of PIC 337 × 1050 finishing pigs. In each experiment, pens of pigs were blocked by BW and randomly assigned to 1 of 5 dietary treatments in a randomized complete block design with 22 to 27 pigs per pen and 6 or 7 replications per treatment. In Exp. 1, 840 pigs (initially 101.2 ± 2.08 lb) were used from 101 to 161 lb. In Exp. 2, 801 pigs (initially 219.8 ± 3.44 lb) were used from 220 to 281 lb. Dietary treatments were corn-soybean meal-based with 30 or 20% DDGS (Exp. 1 and 2, respectively) and contained increasing SID Trp:Lys ratios at 15, 17.5, 19, 21, and 23%. Diets containing low and high Trp:Lys ratios were blended to achieve the target SID Trp:Lys treatment levels in Exp. 1, while diets containing low, medium, and high Trp:Lys ratios were blended to achieve the target SID Trp:Lys treatment levels in Exp. 2. Between experiments, all pens of pigs were placed on a common diet for 27 d and pens were reallotted to dietary treatment at the start of Exp. 2. In Exp. 1, increasing the SID Trp:Lys ratio increased (quadratic, P ≤ 0.008) ADG, ADFI, and final BW and improved (quadratic, P = 0.007) F/G. As expected, increasing SID Trp:Lys increased (linear, P \u3c 0.001) Trp intake, g/d. In addition, Trp intake per kg of gain and Lys intake/d increased (quadratic, P ≤ 0.009), while Lys intake per kg of gain decreased (quadratic, P = 0.008) with increasing SID Trp:Lys ratio. There was no difference between Trp:Lys ratios on the percentage of removals, mortalities, or total removals (P \u3e 0.10). For model analysis in 101- to 161-lb pigs, the developed broken-line linear models suggested no further improvement to ADG and F/G beyond 19.0 and 19.3% SID Trp:Lys, respectively. Meanwhile, a similar fitting quadratic polynomial (QP) model suggested minimum F/G was achieved at 21.5% SID Trp:Lys. In Exp. 2, increasing the SID Trp:Lys ratio increased (linear, P ≤ 0.001) Trp intake and Trp intake per kg of gain (quadratic, P = 0.050). However, no other observed response criteria were significantly impacted (P≥ 0.10). Models to predict optimal Trp:Lys ratios were not analyzed for 220- to 281-lb pigs due to the lack of observed differences for ADG and F/G. In summary, these results suggest the optimal SID Trp:Lys level for 101- to 161-lb pigs was predicted at or above 19.0 and 19.3% SID Trp:Lys for ADG and F/G, respectively. With the variation in response criteria observed in Exp. 2 (220 to 281 lb), we were unable to statistically define a requirement estimate

Structural analysis of cytochrome P450 105N1 involved in the biosynthesis of the zincophore, coelibactin

Coelibactin is a putative non-ribosomally synthesized peptide with predicted zincophore activity and which has been implicated in antibiotic regulation in Streptomyces coelicolor A3(2). The coelibactin biosynthetic pathway contains a stereo- and regio-specific monooxygenation step catalyzed by a cytochrome P450 enzyme (CYP105N1). We have determined the X-ray crystal structure of CYP105N1 at 2.9 Å and analyzed it in the context of the bacterial CYP105 family as a whole. The crystal structure reveals a channel between the α-helical domain and the β-sheet domain exposing the heme pocket and the long helix I to the solvent. This wide-open conformation of CYP105N1 may be related to the bulky substrate coelibactin. The ligand-free CYP105N1 structure has enough room in the substrate access channel to allow the coelibactin to enter into the active site. Analysis of typical siderophore ligands suggests that CYP105N1 may produce derivatives of coelibactin, which would then be able to chelate the zinc divalent cation

Diurnally Entrained Anticipatory Behavior in Archaea

By sensing changes in one or few environmental factors biological systems can anticipate future changes in multiple factors over a wide range of time scales (daily to seasonal). This anticipatory behavior is important to the fitness of diverse species, and in context of the diurnal cycle it is overall typical of eukaryotes and some photoautotrophic bacteria but is yet to be observed in archaea. Here, we report the first observation of light-dark (LD)-entrained diurnal oscillatory transcription in up to 12% of all genes of a halophilic archaeon Halobacterium salinarum NRC-1. Significantly, the diurnally entrained transcription was observed under constant darkness after removal of the LD stimulus (free-running rhythms). The memory of diurnal entrainment was also associated with the synchronization of oxic and anoxic physiologies to the LD cycle. Our results suggest that under nutrient limited conditions halophilic archaea take advantage of the causal influence of sunlight (via temperature) on O2 diffusivity in a closed hypersaline environment to streamline their physiology and operate oxically during nighttime and anoxically during daytime