Effect of methionine:lysine ratio on growth performance and blood metabolites of growing-finishing pigs

Eighty growing-finishing pigs (40 barrows and 40 gilts) were used in three consecutive growth assays to determine the optimum methionine:lysine ratio for pigs weighing from 48 to 107 lb, 120 to 179 lb, and 191 to 245 lb, respectively. Each growth assay was to be conducted for a 28-d period with a 14-d transition period between assays. Pigs were allotted by weight and placed in pens each containing one barrow and one gilt. Pigs were assigned to one of eight experimental treatments with five replicate pens per treatment. Pigs were fed diets containing either high lysine (1.0, .9, or .8%, respectively) or low lysine (.8, .7, or .6%, respectively) with dietary methionine at 24.5, 28, 31.5, or 35% of lysine. This would correspond to total sulfur-containing amino acids (methionine + cystine) of 49, 56, 63, and 70% relative to lysine. During the first study (48 to 107 lb), average daily gain (ADG), average daily feed intake (ADFI), and feed efficiency (F/G) improved with increasing dietary lysine. Although no differences occurred in growth performance with increasing methionine ratio, there was a numeric improvement in growth performance for those pigs receiving diets containing 28% methionine relative to lysine. A lysine × methionine interaction was observed for blood urea N with pigs having the lowest BUN values observed with methionine at 24.5 and 31.5% of lysine for pigs fed .8 and 1.0% lysine, respectively. During phase II (120 lb to 179 lb), ADG improved with increasing dietary lysine and showed a linear response to increasing methionine ratio. Feed efficiency was also improved with increasing dietary lysine. For the third phase (191 to 245 lb), ADG also improved with increasing dietary lysine. There were no significant differences in feed intake; however, feed efficiency improved with increasing dietary lysine. In summary, because of high ADFI observed in these studies, the dietary methionine levels used closely met or exceeded the pig's requirement on a grams/day basis. Therefore, these data suggest that increasing dietary methionine does not improve pig performance

Interactive effects of added L-carnitine and chromium picolinate on sow reproductive performance

A total of 599 sows were used to determine the effects of added L-carnitine and/or chromium picolinate on reproductive performance. Experimental treatments were arranged in a 2 × 2 factorial with main effects of added L-carnitine (0 or 50 ppm) and chromium picolinate (0 or 200 ppb). Starting on the first day of breeding, sows were provided a daily top dress containing the carnitine and(or) chromium along with the standard gestation diet. Dietary treatments were administered daily through the initial gestation, lactation, and through a second gestation period (2 parities). During the first parity, there was a carnitine × chromium interaction (P0.05) were observed in number of pigs born alive, still born, mummies, or total born in the first parity. Added dietary L-carnitine decreased (P<0.05) wean to estrus interval, and tended to increase (P<0.08) the number of sows in estrus by d 7. In the second parity, a tendency (P<.08) for a carnitine × chromium interaction was found for first service farrowing rate. Adding carnitine and chromium together in the diet increased first service farrowing rate compared to either product alone. Because of the change in wean-to-estrus interval and farrowing rate, feeding additional dietary carnitine and chromium increased (P<0.04) the percentage of sows that were weaned from parity 1 and farrowed in parity 2. When calculating the total number of pigs and number born alive based on all sows that were started on test, both added carnitine and chromium increased the number of pigs born and born alive. These results show that carnitine and chromium supplementation improved return-to- estrus interval and farrowing rate and, thus, total number born alive over two parities

Influence of dietary lysine on growth performance of high-lean growth gilts fed from 160 to 300 lb

One-hundred eight high-lean growth gilts (159.6 lb) were used to determine the dietary lysine requirement to optimize growth performance from 160 to 300 lb. The experiment was designed as a randomized complete block, with initial weight serving as the blocking factor. Six dietary treatments were used, ranging from .44 to .94% digestible lysine (.59 to 1.16% total lysine). Pigs were housed in pens of three, with six replicate pens/treatment. Pig weights and feed disappearance were collected weekly to calculate average daily gain (ADG), average daily feed intake (ADFI), and feed efficiency (F/G). Average daily gain increased from 160 to 230 lb, from 230 to 300 lb, and from 160 to 300 lb. Average daily feed intake was not influenced by dietary treatment. The gilts consumed 6.47, 6.65, and 6.56 lb/day from 160 to 230, from 230 to 300, and from 160 to 300 lb, respectively. Thus, F/G improved linearly from 160 to 230 lb and quadratically from 230 to 300 and from 160 to 300 lb as a function of increased ADG. Lysine intake was increased linearly for all three weight periods as digestible lysine increased in the diet. The data from this experiment suggest that high-lean growth gilts requires at least 26 g/d of lysine from 160 to 230 and from 230 to 300 lb. Thus, matching nutrition with genetics is essential to optimize both rate and efficiency of gain

Design of Experiments for Screening

The aim of this paper is to review methods of designing screening experiments, ranging from designs originally developed for physical experiments to those especially tailored to experiments on numerical models. The strengths and weaknesses of the various designs for screening variables in numerical models are discussed. First, classes of factorial designs for experiments to estimate main effects and interactions through a linear statistical model are described, specifically regular and nonregular fractional factorial designs, supersaturated designs and systematic fractional replicate designs. Generic issues of aliasing, bias and cancellation of factorial effects are discussed. Second, group screening experiments are considered including factorial group screening and sequential bifurcation. Third, random sampling plans are discussed including Latin hypercube sampling and sampling plans to estimate elementary effects. Fourth, a variety of modelling methods commonly employed with screening designs are briefly described. Finally, a novel study demonstrates six screening methods on two frequently-used exemplars, and their performances are compared

Interaction Testing and Polygenic Risk Scoring to Estimate the Association of Common Genetic Variants with Treatment Resistance in Schizophrenia

Importance: About 20% to 30% of people with schizophrenia have psychotic symptoms that do not respond adequately to first-line antipsychotic treatment. This clinical presentation, chronic and highly disabling, is known as treatment-resistant schizophrenia (TRS). The causes of treatment resistance and their relationships with causes underlying schizophrenia are largely unknown. Adequately powered genetic studies of TRS are scarce because of the difficulty in collecting data from well-characterized TRS cohorts. Objective: To examine the genetic architecture of TRS through the reassessment of genetic data from schizophrenia studies and its validation in carefully ascertained clinical samples. Design, Setting, and Participants: Two case-control genome-wide association studies (GWASs) of schizophrenia were performed in which the case samples were defined as individuals with TRS (n = 10501) and individuals with non-TRS (n = 20325). The differences in effect sizes for allelic associations were then determined between both studies, the reasoning being such differences reflect treatment resistance instead of schizophrenia. Genotype data were retrieved from the CLOZUK and Psychiatric Genomics Consortium (PGC) schizophrenia studies. The output was validated using polygenic risk score (PRS) profiling of 2 independent schizophrenia cohorts with TRS and non-TRS: a prevalence sample with 817 individuals (Cardiff Cognition in Schizophrenia [CardiffCOGS]) and an incidence sample with 563 individuals (Genetics Workstream of the Schizophrenia Treatment Resistance and Therapeutic Advances [STRATA-G]). Main Outcomes and Measures: GWAS of treatment resistance in schizophrenia. The results of the GWAS were compared with complex polygenic traits through a genetic correlation approach and were used for PRS analysis on the independent validation cohorts using the same TRS definition. Results: The study included a total of 85490 participants (48635 [56.9%] male) in its GWAS stage and 1380 participants (859 [62.2%] male) in its PRS validation stage. Treatment resistance in schizophrenia emerged as a polygenic trait with detectable heritability (1% to 4%), and several traits related to intelligence and cognition were found to be genetically correlated with it (genetic correlation, 0.41-0.69). PRS analysis in the CardiffCOGS prevalence sample showed a positive association between TRS and a history of taking clozapine (r2 = 2.03%; P =.001), which was replicated in the STRATA-G incidence sample (r2 = 1.09%; P =.04). Conclusions and Relevance: In this GWAS, common genetic variants were differentially associated with TRS, and these associations may have been obscured through the amalgamation of large GWAS samples in previous studies of broadly defined schizophrenia. Findings of this study suggest the validity of meta-analytic approaches for studies on patient outcomes, including treatment resistance

Comparison of feed-grade antibiotics in starter diets containing spray-dried blood products

A total of 240 pigs (initially 11.6 lb and 19 d of age) was used to compare four different feed-grade antibiotics or antibiotic combinations in phase I (d 0 to 14 postweaning) and phase II (d 14 to 28 postweaning) starter pig diets. Apramycin and carbadox were compared in the phase I diet. Combinations of tylosin/sulfamethazine and neomycin sulfate/oxytetracycline were compared in the phase II diet. No differences occurred in pig performance for the phase I and phase II periods between the feed-grade antibiotics compared in this growth assay. Therefore, determination of appropriate feed-grade antibiotic inclusion will depend on 1) economics, 2) disease profile of the herd, and 3) growth response within a particular producer's herd

Optimum level of spray-dried porcine plasma for early-weaned (10.5 d of age) starter pigs

A total of 290 early-weaned pigs (initially 7.6 lb and 10.5 d of age) was used to evaluate various levels of spray-dried porcine plasma. Pigs were assigned to one of five experimental diets with either 5, 7.5, 10, 12.5, or 15% spray-dried porcine plasma replacing dried skim milk. Pigs were fed this diet for the first 14 days postweaning. Common diets were fed from d 14 to 42 postweaning in order to monitor subsequent performance. During the first phase (d 0 to 14 postweaning), linear improvements in average daily gain (ADG) and average daily feed intake (ADFI) occurred as the level of spray-dried porcine plasma increased from 5% to 15%. This resulted in a linear improvement in weight at d 14 postweaning. For the first phase and subsequent phases, no differences occurred in feed efficiency (F/G). From d 14 to 21 postweaning, a linear decrease occurred in ADG and ADFI as well as a linear deterioration of F/G as the level of spray-dried porcine plasma increased from 5% to 15%. This reversal of performance resulted in no difference of pig weights at d 21 and 25 postweaning. From d 25 to 42 postweaning, no difference was seen in ADG. In summary, spray-dried porcine plasma can be used as an effective replacement for dried skim milk as a protein source in diets for pigs weaned at 10 d of age

The effect of increasing dietary methionine on performance of the early-weaned pig

A total of 216 pigs (initially 10.8 lb and 21 d of age) was used in a 35 d growth trial to determine the effect of increased dietary methionine on growth performance for the early-weaned pig when offered a porcine plasma-based diet. During d 0 to 21 postweaning, increasing methionine levels were obtained by adding DL-methionine to a common basal diet. The control diet was corn-soybean meal-based; contained 10% spray-dried porcine plasma (SDPP), 20% dried whey, 3% lactose, and 1.75% spray-dried blood meal (SDBM); and was formulated to contain 1.6% lysine and .28% methionine. DL-methionine replaced sucrose in the control diet to achieve the experimental dietary methionine levels of .28, .32, .36, .40, .44, and .48%. Six pigs were housed per pen with six pens per treatment. From d 21 to 35 postweaning, all pigs were switched to a common diet containing 10% dried whey and 2.5% SDBM and formulated to contain 1.25% lysine. During d 0 to 21, average daily gain (ADG), average daily feed intake (ADFI), and feed efficiency (F/G) were improved quadratically as dietary methionine increased, with maximum growth performance being obtained between .40 and .44% dietary methionine. Average daily gain was not affected during the second half (d 21 to 35) of the trial. However, both ADFI and feed efficiency were improved with increasing methionine level fed during phase I. On d 7 and 14 postweaning, blood urea N was reduced as dietary methionine increased. Pigs fed .40% dietary methionine had the lowest blood urea N concentration on d 14 compared to pigs fed the other methionine levels. Cumulative (d 0 to 35) ADG and ADFI were maximized between .40 and .44% dietary methionine. These data suggest that the early-weaned pig requires approximately .40 to .44% dietary methionine to optimize growth performance. This corresponds to .345 to .385% digestible methionine and 1.27 and 1.55 g/d of methionine intake from d 0 to 14 postweaning. These requirements are substantially higher than those previously recommended