Research Note: Evaluation of phytic acid disappearance, ileal P digestibility, and total tract P retention in canola meal supplemented with increasing levels of exogenous phytase using conventional and cecectomized precision-fed roosters and growing chicks

Apparent ileal digestibility (AID) of P, apparent total tract retention (ATTR) of P, and phytic acid disappearance in canola meal were evaluated in the presence of increasing levels of exogenous phytase. In Experiment 1, a precision-fed rooster assay was used to determine phytic acid (myo-inositol 1,2,3,4,5,6-hexakis; InsP6) and inositol phosphate (InsP6-3; InsP-P) disappearance in conventional and cecectomized Leghorn roosters. Roosters were crop intubated with 25 g of canola meal mixed with 0, 500, 1,000, or 2,000 FTU/kg of exogenous phytase. In Experiment 2, InsP6 and InsP-P disappearance and AID and ATTR of P were determined using ad libitum-fed broiler chickens. Treatments consisted of semi-purified diets containing 45% canola meal as the sole source of P. Phytase was added to increase phytase activity by 0, 500, 1,000, or 2,000 FTU/kg. Experiments contained 6 replicates per treatment. Canola meal contained a high phytase activity (1,630 FTU/kg as-fed) due to contamination with a commercially available phytase at the feed mill from which the canola meal was sourced. In Experiment 1 with precision-fed roosters, there was no effect (P > 0.05) of phytase or bird type on InsP6 and InsP-P disappearance; however, phytase linearly reduced (P < 0.05) InsP3 concentrations in excreta. In Experiment 2 with ad libitum-fed chickens, phytase linearly increased (P < 0.05) ileal InsP6 and InsP-P disappearance, and phytase had a quadratic effect (P < 0.05) on excreta InsP6 and InsP-P disappearance. Increasing dietary phytase activity resulted in a linear increase (P < 0.05) in AID of P and phytase had a quadratic effect (P < 0.05) on ATTR of P. In conclusion, titration of high levels of phytase (1,600 to 3,600 FTU/kg as-fed) reduced InsP3 concentrations in precision-fed roosters but did not affect overall phytic acid hydrolysis, which was 78% or greater for all treatments; however, increasing the total phytase activity from 700 to 2,700 FTU in ad libitum-fed broiler chickens increased phytic acid disappearance and P digestibility.

Influence of different heat stress models on nutrient digestibility and markers of stress, inflammation, lipid, and protein metabolism in broilers

This experiment determined the effects of different HS models and pair-feeding (PF) on nutrient digestibility and markers of stress, inflammation, and metabolism in broilers. Birds (720 total) were allocated into 12 environmentally controlled chambers and reared under thermoneutral conditions until 20 d. Until 41 d birds were exposed to 4 treatments, including: thermoneutral at 24°C (TN-al), daily cyclic HS (12 h at 24 and 12 h at 35°C; cyHS), constant HS at 35°C (coHS), and PF birds maintained at 24°C and fed to equalize FI with coHS birds (TN-coPF). At d 41, ileal digesta were collected to determine nutrient apparent ileal digestibility (AID). Blood, liver, and breast tissues were collected from 8 birds per treatment to determine the mRNA expression of stress, inflammation, and metabolism markers. An additional 8 TN-al birds were sampled after acute HS exposure at 35°C for 4 h (aHS), and 8 cyHS birds were sampled either right before or 4 h after HS initiation. Data were analyzed by 1-way ANOVA and means were separated using Tukey's HSD test. Compared with TN-al birds, AID of nitrogen and ether extract were reduced in coHS birds, and both cyHS and coHS reduced (P < 0.05) AID of total essential amino acids. TNFα and SOD2 expression were increased (P < 0.05) under aHS, coHS, and TN-coPF conditions. IL6 and HSP70 were increased (P < 0.05) under coHS and aHS, respectively. Expression of lipogenic enzymes ACCα and FASN were reduced by coHS and TN-coPF, while coHS increased the lipolytic enzyme ATGL (P < 0.05). IGF1 was lowered in coHS birds, and p70S6K and MyoG were reduced under coHS and TN-coPF (P < 0.05). Interestingly, MuRF1 and MAFbx were increased (P < 0.05) under coHS only. Overall, these results indicate that coHS has a greater impact on nutrient digestibility and metabolism than aHS and cyHS. Interestingly, increased protein degradation during HS appears to be mostly driven by HS per se and not the reduced FI.

Economic and environmental assessment of U.S. broiler production: opportunities to improve sustainability

The United States is the largest broiler producer in the world, and Americans consume about 45 kg of chicken per capita per year, which generates substantial economic and environmental footprints. We conduct techno-economic analysis and life cycle assessment (TEA/LCA) to evaluate the sustainability performance of the U.S. broiler industry and quantify the cost, greenhouse gas (GHG) emissions, energy, water, land, fertilizer, and respiratory impacts of 7 broiler production scenarios for a contract Grower, Integrator, and Combined control volume. The assessment is a farm-gate to farm-gate analysis that includes capital cost of chicken houses, labor, chicks brought into the farm, feeds, on-site fuels, and on-site emissions. We found that economics for the Integrator are profitable and dominated by the cost of corn and soybean meal feeds, payments to the Grower, and revenue from live broilers. Additionally, we found that economics for the Grower generate modest return on investment (ROI) largely based on the cost of houses and labor when compared to contract revenue from the Integrator. Environmental impacts for GHG, energy, and respiratory effects are primarily associated with upstream feed production (roughly 65%-80% of total impacts) and on-site fuel consumption (∼20%-35% of total impacts), while those for water, land, and eutrophication are almost entirely attributable to upstream feed production (litter spreading has a low economic allocation factor). Tradeoffs among sustainability metrics are further explored with a sensitivity analysis and by evaluating cost/environmental benefit scenarios.

Assessment of meat quality attributes of four commercial broiler strains processed at various market weights

As the demand for poultry meat continues to rise, industry production is constantly challenged with obtaining consumer needs. Integrators have answered this increasing demand by improving the growth rate of broilers allowing for increased production efficiently. The resulting broiler produces higher yields and a larger quantity of fresh poultry to satisfy consumer needs. However, this increase in efficiency has cost integrators as new quality issues continue to manifest through global production. Therefore, the objective of the current experiment was to evaluate the effect of genetic strain (standard and high yielding) and target weight on meat quality attributes such as pH, water holding capacity (WHC), and tenderness, alongside meat quality defects such as breast and tender myopathies. In the current study, 1,800 broilers from 4 commercial strains (2 high breast yielding (HY) and 2 standard yielding (SY) were raised sex separate to evaluate meat quality trends over time at 6 previously defined market weights. Birds were processed at weights ranging from 2,043 to 4,313 g in 454 g increments. HY strains produced higher breast and tender yields than those of SY strains (P < 0.05). There was an increase in breast and tender yield as target weight increased (P < 0.05) for both HY and SY strains. Differences were observed between strains for all fillet dimensions (P < 0.05); however, these measurements increased as target weight increased as expected. Woody breast (WB) had a higher severity (P < 0.05) in HY strains over SY strains, for both males and females. Differences were observed in white striping (WS; P < 0.05) for females in both strains, but no differences were observed in males. A main effect of target was noticed for both WB and WS (P < 0.05), expressing increased severity as target weight increased. Shear values were influenced more by target weight (P < 0.05), but inconsistent differences were observed between HY and SY groups. Meullenet-Owens Razor Shear (MORS) energy values increased slightly as target weights increased (P < 0.05) from 2,951 to 4,313 g in both males and females, but differences were minor and inconsistent with the smaller carcass weights. The MORS peak counts generally increased as target weight increased for both sexes. While strain had minimal effects on meat quality attributes, processing weight had a greater influence on quality, specifically muscle myopathies, WHC, and shear properties.

Quantification of secretory IgA and mucin excretion and their contributions to total endogenous amino acid losses in roosters that were fasted or precision-fed a nitrogen-free diet or various highly digestible protein sources

The objective of this study was to quantify total secretory IgA (sIgA) and mucin excretion via excreta in roosters fed diets containing highly digestible protein sources and to determine their proportional contributions to total endogenous amino acid (AA) losses. Precision-fed rooster assays with 24 h excreta collections were conducted using conventional White Leghorn roosters (4-8 roosters per treatment). In Experiment 1, roosters were fasted or precision-fed 30 g (crop intubation) of a nitrogen-free (NF) or semi-purified diet containing 10% casein. Roosters in Experiment 2 received a NF or semi-purified diet containing either 10% casein, 17% whole egg, 10% egg white, 9.8% soy protein isolate, 10.2% chicken breast meat, 11.2% spray-dried animal plasma (SDAP), or an AA mixture containing the same AA as casein. A Latin square design was used in Experiment 3, where roosters received NF or semi-purified diets containing either 10% casein, 17% whole egg, or 9.6% of a crystalline AA mixture to evaluate both diet and individual bird effects. In Experiment 1, mucin excretion did not differ (P > 0.05) among treatments; however, total sIgA excretion was lower for fasted birds, intermediate for the NF diet, and highest for casein (P < 0.05). Total endogenous AA losses (proportion of the total) from sIgA were higher for roosters fed casein, whereas mucin contributions were higher for fasted roosters (P < 0.05). In Experiment 2, sIgA excretion did not differ (P > 0.05) among treatments; however, mucin excretion was reduced for NF, whole egg, egg white, and chicken breast compared with casein and SDAP. In Experiment 3, sIgA and mucin excretion did not differ (P > 0.05) among treatments; however, sIgA excretion differed among individual roosters (7-27 mg/24 h; P < 0.05). Overall, fasting reduced sIgA excretion and sIgA and mucin excretion were affected by dietary protein source. Further, roosters excreted a substantial amount of sIgA, and sIgA and mucin were considerable contributors to total endogenous AA losses.

Dietary soy galactooligosaccharides affect the performance, intestinal function, and gut microbiota composition of growing chicks

The objective of this experiment was to investigate the effects of the dietary soy galactooligosaccharides (GOS), raffinose and stachyose, on performance, gastrointestinal health, and systemic stress in young broilers. Birds were fed a GOS-devoid diet based on soy protein isolate (SPI) or the SPI diet with 0.9, 1.8, 2.7, or 3.6% added stachyose and raffinose in a ratio of 4:1 at the expense of corn starch. These 5 treatments were administered to 10 replicate cages of 8 birds. Performance was measured weekly and excreta moisture, N retention, apparent metabolizeable energy, and complete blood cell counts were determined at 14 and 21 d. At 21 d, 2 birds per cage were orally gavaged with fluorescein isothiocyanate-dextran (FITC-d) and serum samples were analyzed for FITC-d as a marker of gut leakage. Additionally, intestinal morphology, crop presumptive lactic acid bacteria (LAB) counts, crop and cecal pH, and cecal microbiota via16S rRNA microbial sequencing were evaluated at 21 d. From 0 to 21 d, feed intake increased linearly (P < 0.01) as dietary GOS increased, whereas BWG increased (P < 0.05) quadratically. Feed conversion ratio increased (P < 0.01) linearly as GOS increased. There were linear increases (P < 0.05) in excreta moisture as dietary GOS increased at 14 and 21 d, as well as dose-dependent responses (P < 0.05) in N retention, AME, and AME_n. There was a quadratic increase (P < 0.05) in crop LAB recovery and a linear decrease (P < 0.01) in ceca pH as GOS increased. At 14 d, a linear increase (P < 0.05) in blood heterophil to lymphocyte ratio was observed as dietary GOS increased. Serum concentrations of FITC-d increased quadratically (P < 0.01) to dietary GOS. Increasing levels of GOS influenced alpha and beta diversities and composition of gut microbiota, including the abundance of Ruminococcus and Bifidobacterium. Results from this trial indicate that soy-derived GOS exert dose-dependent effects on nutrient utilization and intestinal health in young broilers.

Characterization of growth patterns and carcass characteristics of male and female broilers from four commercial strains fed high or low density diets

Over the last few decades, the poultry industry has seen the emergence of various market segments that are beneficial for rearing various flock sizes. Two concurrent experiments consisting of 1,200 broilers each were conducted to evaluate the effects of broiler size and diet on the performance of four commercially available broiler strains, including 2 standard yielding (SY) and 2 high yielding (HY) strains. Within each experiment (Experiment 1: males, Experiment 2: females), a small bird (38 and 40 d processing) and big bird (47 and 54 d processing) debone market were targeted to give variable carcass size. Two polyphasic diets were fed based on varying of amino acid densities. The low-density diet (L) consisted of 1.20, 1.10, 1.00, and 0.96% digestible Lys and the high-density diet (H) consisted of 1.32, 1.21, 1.10, and 1.06% across the 4-phases, respectively, with similar essential amino acid to digestible Lys ratios between the L and H diets in each phase. Weekly BW, BW gain, feed intake, and feed conversion ratio were assessed, as well as processing yields during both experiments. Broilers fed the H diets responded better than those fed the L diets, regardless of sex, with increased BW and decreased FCR (P < 0.05). Male HY strains provided the highest carcass yields (P < 0.05) compared to SY strains, with no differences observed in females (P > 0.05). High density diets (Diet H) also produced increases in carcass, breast, and tender yield (P < 0.05) for males, but that trend was not present in carcass yield for females (P < 0.05). Overall, strain impacted performance traits and carcass yields. Therefore, the use of specific strains and amino acid density for various market segments is beneficial for integrators to maximize return.

Research Note: Evaluation of a precision-fed rooster assay for determination of phytic acid disappearance in feedstuffs

The objective of this study was to evaluate a precision-fed rooster assay that is suitable for determination of phytic acid (myo-inositol 1,2,3,4,5,6-hexakis; InsP₆) disappearance in plant-based feed ingredients. A 48-h precision-fed rooster assay was used to measure InsP₆ disappearance using conventional White Leghorn roosters. A minimum of 4 individually-caged roosters per treatment were fasted for 26 h prior to crop intubation with 15 to 30 g of sample, and excreta were quantitatively collected for 48 h. Soybean meal, soybean hulls, canola meal, conventional distillers dried grains with solubles (DDGS), palm kernel meal (PKM), and wheat bran were evaluated in Experiment 1, whereas wheat middlings (WM) and rice bran (RB) were evaluated without and with 1,000 and 1,800 U/kg phytase in Experiment 2. Data from Experiment 1 were subjected to a one-way ANOVA for a completely randomized design, while data from Experiment 2 were subjected to two-way ANOVA for a 2 × 3 factorial arrangement of treatments. In Experiment 1, InsP₆ disappearance ranged from 3 to 95% among all ingredients. The InsP₆ disappearance for conventional DDGS (95%) was the highest (P < 0.05), wheat bran and soybean hulls were intermediate (47-48%), PKM was low (24%), and soybean meal and canola meal were very low (3-5%). In Experiment 2, there was a significant ingredient × phytase interaction (P < 0.05). Phytase inclusion at both 1,000 and 1,800 U/kg resulted in a significant improvement (P < 0.05) in InsP₆ disappearance for RB; however, only the addition of 1,800 U/kg resulted in an increase in InsP₆ disappearance for WM. The addition of 1,800 U/kg phytase increased the InsP₆ disappearance from 58 to 74% for WM and from 26 to 53% for RB. These results suggest the precision-fed rooster assay can be used to evaluate phytic acid disappearance in plant-based feed ingredients and the assay was able to detect a significant effect of 1,800 U/kg of exogenous phytase on phytic acid disappearance for WM and RB.

A review of heat stress in chickens. Part II: Insights into protein and energy utilization and feeding

With the growing global demand for animal protein and rising temperatures caused by climate change, heat stress (HS) is one of the main emerging environmental challenges for the poultry industry. Commercially-reared birds are particularly sensitive to hot temperatures, so adopting production systems that mitigate the adverse effects of HS on bird performance is essential and requires a holistic approach. Feeding and nutrition can play important roles in limiting the heat load on birds; therefore, this review aims to describe the effects of HS on feed intake (FI) and nutrient digestibility and to highlight feeding strategies and nutritional solutions to potentially mitigate some of the deleterious effects of HS on broiler chickens. The reduction of FI is one of the main behavioral changes induced by hot temperatures as birds attempt to limit heat production associated with the digestion, absorption, and metabolism of nutrients. Although the intensity and length of the heat period influences the type and magnitude of responses, reduced FI explains most of the performance degradation observed in HS broilers, while reduced nutrient digestibility appears to only explain a small proportion of impaired feed efficiency following HS. Targeted feeding strategies, including feed restriction and withdrawal, dual feeding, and wet feeding, have showed some promising results under hot temperatures, but these can be difficult to implement in intensive rearing systems. Concerning diet composition, feeding increased nutrient and energy diets can potentially compensate for decreased FI during HS. Indeed, high energy and high crude protein diets have both been shown to improve bird performance under HS conditions. Specifically, positive results may be obtained with increased added fat concentrations since lipids have a lower thermogenic effect compared to proteins and carbohydrates. Moreover, increased supplementation of some essential amino acids can help support increased amino acid requirements for maintenance functions caused by HS. Further research to better characterize and advance these nutritional strategies will help establish economically viable solutions to enhance productivity, health, welfare, and meat quality of broilers facing HS.

A review of heat stress in chickens. Part I: Insights into physiology and gut health

Heat stress (HS) compromises the yield and quality of poultry products and endangers the sustainability of the poultry industry. Despite being homeothermic, chickens, especially fast-growing broiler lines, are particularly sensitive to HS due to the phylogenetic absence of sweat glands, along with the artificial selection-caused increase in metabolic rates and limited development of cardiovascular and respiratory systems. Clinical signs and consequences of HS are multifaceted and include alterations in behavior (e.g., lethargy, decreased feed intake, and panting), metabolism (e.g., catabolic state, fat accumulation, and reduced skeletal muscle accretion), general homeostasis (e.g., alkalosis, hormonal imbalance, immunodeficiency, inflammation, and oxidative stress), and gastrointestinal tract function (e.g., digestive and absorptive disorders, enteritis, paracellular barrier failure, and dysbiosis). Poultry scientists and companies have made great efforts to develop effective solutions to counteract the detrimental effects of HS on health and performance of chickens. Feeding and nutrition have been shown to play a key role in combating HS in chicken husbandry. Nutritional strategies that enhance protein and energy utilization as well as dietary interventions intended to restore intestinal eubiosis are of increasing interest because of the marked effects of HS on feed intake, nutrient metabolism, and gut health. Hence, the present review series, divided into Part I and Part II, seeks to synthesize information on the effects of HS on physiology, gut health, and performance of chickens, with emphasis on potential solutions adopted in broiler chicken nutrition to alleviate these effects. Part I provides introductory knowledge on HS physiology to make good use of the nutritional themes covered by Part II.

Feed Composition and Isolate of Histomonas meleagridis Alter Horizontal Transmission of Histomonosis in Turkeys. Proof of Concept

Outbreaks of histomonosis in turkeys are typically initiated by the ingestion of contaminated embryonated eggs of Heterakis gallinarum, potentially present in earthworms and mechanical vectors. Once an outbreak is started, infected turkeys can transmit the disease by horizontal transmission. Factors influencing horizontal transmission of histomonosis are poorly understood. Replication of horizontal transmission in experimental conditions has not been consistent, presenting an obstacle in searching for alternatives to prevent or treat the disease. Two pilot experiments and three validation experiments were conducted in the present study. In pilot experiment 1, one isolate of Histomonas meleagridis (named Buford) was used. Turkeys were fed a low-nutrient density diet corn-soy based (LOW-CS) and raised in floor pens. In pilot experiment 2, another isolate of H. meleagridis was used (named PHL). Turkeys were fed a low-nutrient density diet with the addition of wheat middlings (LOW-WM) and raised in floor pens. In experiment 3, conducted on floor pens, both isolates and diets were used in different groups. In experiment 4, turkeys were raised on battery cages and only the PHL isolate was used. Both diets (LOW-WM and LOW-CS) were used, in addition to a diet surpassing the nutritional needs of young poults (turkey starter, TS). In experiment 5, conducted in battery cages, only the PHL isolate was used, and the LOW-WM and TS diets were in different groups. The horizontal transmission was achieved only with the PHL isolate from all experiments. The transmission rate varied among experimental diets, with the TS diet having the lowest transmission rate in experiments 4 and 5. Variation was observed between experiments and within experimental groups.

Precision intestinal nutrition: knowledge and gaps regarding the role of amino acids during an enteric challenge

Poultry nutritionists continually strive for more “precision” nutritional programs that provide the exact balance of nutrients that maximize broiler growth performance without economically and environmentally costly excesses. Many factors affect the precise amount and balance of nutrients needed by the broiler, including genetics, age, sex, and environment. Furthermore, broilers in intensive rearing environments will almost always be subjected to some degree of enteric stress that can alter nutrient needs. Exposure to enteric pathogens such as Eimeria spp., the intestinal parasites that cause avian coccidiosis, induces physical damage to the intestinal epithelium and activates immune responses, ultimately resulting in the repartitioning of amino acids (AA) in response to these prioritized demands. Even without any pathogenic challenge, the intestine has an already high demand for many AA, with 30 to 100% of dietary AA extracted during first pass intestinal metabolism. In many cases, increasing dietary protein from intact proteins has been shown to be a viable option to ameliorate impaired AA digestion and absorption and heightened need for certain AA of birds under an enteric stress. However, increasing dietary protein often results in concomitant increases in indigestible protein and carbohydrates that can stimulate the overgrowth of pathogenic bacteria (i.e., Clostridium perfringens). Alternative options to increase dietary AA levels are to increase all feed-grade, free AA (e.g., Met, Lys, Thr, Val), or specific individual feed-grade AA. Therefore, the objectives of this paper are to discuss precision nutrition, the dietary AA demands of the intestine, consequences of coccidiosis on AA needs of the intestine, and formulation approaches to meet these altered needs. In summary, increased dietary protein met by intact proteins has consistently demonstrated its benefits during an Eimeria spp. infection; however, to further the goal of precision nutritional programs, feeding higher levels of a specific AA to support desired functions such as intestinal recovery or immune function for birds experiencing an enteric stress still require further evaluation.

Effects of hatch window and nutrient access in the hatcher on performance and processing yield of broiler chicks reared according to time of hatch

The effects of hatch window and hatching basket nutrient availability on organ weights, performance, and processing yield of broilers were investigated. Eggs were hatched in illuminated hatchers. At the end of each hatch window period (HWP), hatched chicks were placed into control (CTL) hatching baskets with no nutrients or baskets providing access to feed and water (FAW). This resulted in 6 treatments in a factorial arrangement of 3 HWP (early, middle, or late) and 2 basket types (CTL or FAW). Chicks remained in experimental baskets until 504 h and were then subjected to a 4 h holding period at the hatchery without nutrient access. Subsequently, 1,500 hatched chicks were reared in floor pens for 42 d with 5 replicate pens per treatment. Common diets and water were provided ad libitum. Bird weights and feed consumption were recorded weekly. Individual bird weights were taken at 21 and 42 d. At 43 d, 14 males from each pen were processed. There was an interaction between HWP and basket type on placement BW (P = 0.028) and BW change in the hatcher (P < 0.001). The HWP influenced BW at hatch (P = 0.007), 7 d (P < 0.001), and 14 d (P < 0.001) and FI at 7 d (P < 0.001) and 14 d (P = 0.002). Chicks from FAW baskets were heavier (P < 0.001) than those from CTL baskets at 7 d; afterward, they were similar (P > 0.05) in BW. Yolk and liver weights were similar (P > 0.05) between basket treatments at 3 d posthatch. No differences (P > 0.05) in FCR, mortality, or processing were observed between basket treatments. Interestingly, early hatching chicks were lightest at hatch but subsequently had higher FI and BWG. These findings indicate that hatcher nutrient access may reduce weight loss in the hatcher, especially for early hatching chicks, but had no influence on subsequent performance or processing yields beyond 7 d.

Effects of Hatch Window and Nutrient Access in the Hatcher on Performance and Processing Yields of Broilers Reared with Equal Hatch Window Representation

Simple Summary

In commercial hatcheries, hatched broiler chicks remain in the hatcher without feed or water until all chicks are pulled from the hatching cabinet. Subsequent hatchery holding and transport periods can further delay nutrient access, potentially causing dehydration and limiting the bird’s growth potential. This can possibly be mitigated by providing feed and water in the hatching cabinet to promote immediate nutrient access to chicks after hatching. In the current experiment, chicks hatched in baskets modified to supply feed and water were compared with those hatched in standard baskets in regards to their organ weights, growth performance to 42 d, and processing yields. Additionally, chicks were identified according to moment of hatch within the hatch window to evaluate this factor and its potential interaction with nutrient access. Chicks from hatching baskets with nutrient and water access had heavier body weights during the first 4 wk of growth, but were otherwise similar to chicks from standard baskets in growth performance and meat yield, regardless of the timing of their hatch. This indicates that broilers may be able to compensate for some degree of delayed feed and water access associated with their timing of hatch and subsequent holding and transport.

Abstract

The objective of this experiment was to investigate the effects of feed and water availability in hatching baskets on broiler performance, processing yield, and organ weights while considering the influence of hatch window. Cobb 500 eggs were transferred into illuminated hatchers with two hatching basket types [control (CTL) hatching baskets with no nutrients provided or baskets containing feed and water (FAW)]. Chicks were pulled sequentially to establish four hatch window periods (HWP): early, pre-peak, post-peak, or late. Chicks were then held for 4 h at the hatchery without nutrient access and subsequently reared in 26 floor pens designated as CTL (n = 13) or FAW (n = 13), with 13 chicks from each of the 4 HWP per pen (52 chicks per pen). At 43 d, 16 males from each pen were processed. Chicks from FAW baskets were 1 g heavier (p < 0.001) than those from CTL baskets at placement and were heavier through 28 d (p = 0.003) but similar (p > 0.05) in body weight (BW) for the remainder of the 42 d. No differences (p > 0.05) in feed conversion ratio, mortality, or processing data were observed between CTL and FAW groups. Early-hatching chicks were lighter (p < 0.001) than those from all other HWP at placement, but were only lighter (p < 0.001) than the post-peak group by 42 d. In summary, it was found that hatching basket nutrient access increased the BW of broilers during the first 4 wk of growth, with no other effects on performance or yield. Also, earlier-hatching chicks were generally able to compensate for a lighter placement BW.

Determining the 4th limiting amino acid in low crude protein diets for male and female Cobb MV × 500 broilers

1. Four experiments were conducted to determine the 4th limiting amino acid (AA) in maize-soybean meal-based diets. 2. Deletion assay methodology was used to quantify performance and carcase trait responses to potential deficiencies in essential and conditionally essential AA caused by reductions in dietary crude protein of maize-soybean meal-based diets from 202.9 to 186.5 g/kg. 3. The deletion of Val, Phe and Gly + Pro resulted in negative effects on live performance and carcase traits for male broilers, whereas AA deletion only affected wing weights for females with no response on live performance. 4. Further experimentation could not duplicate a response to Phe or Pro in male broilers. 5. Valine was identified as the potential 4th limiting AA in maize-soybean meal-based diets and was not found to be co-limiting with Ile.

Response of broiler chickens fed diets supplemented with a bioactive olive pomace extract from Olea europaea to an experimental coccidial vaccine challenge

This study aimed to investigate an experimental procedure of coccidial challenge in battery cages and the anticoccidial effect of a bioactive olive pomace extract from Olea europaea (OE) in broiler chickens. To this end, four hundred 1-day-old male chicks were randomly assigned to 5 experimental treatments (10 cages/treatment; 8 birds/cage). One group was fed the control diet without any additives and not challenged (NCU). The other 4 groups were challenged and fed the control diet with no additives (NCC) or supplemented with 500 ppm of coccidiostat or with 500 or 1,500 ppm of OE. At 0, 7, and 14 d, all challenged birds, except the NCC group, were orally gavaged with a live Eimeria spp. oocyst vaccine at 1x, 4x, and 16x of the manufacturer's recommended dose, respectively. Feed intake (FI), body weight gain (BWG), and feed conversion ratio (FCR) were determined at 7, 14, 20, and 28 d. At 20 d of age, 1 bird per cage was euthanized to analyze duodenum and jejunum morphology, ileal mucosa gene expression, and plasma cytokine, alpha-1-acid glycoprotein, and carotenoid (CAR) concentrations. Coccidial vaccine challenge lowered BW (P < 0.05) throughout the trial, and reduced FI and BWG, except from 20 to 28d, and increased FCR from 0 to 7, 0 to 14, and 0 to 20 d. Birds in the NCC group had higher (P < 0.05) oocyst counts and lower (P < 0.05) CAR and villus height to crypt depth ratios compared with NCU birds. Overall, coccidia challenge caused the expected reductions in growth performance and gut integrity. While the coccidiostat reduced oocysts excretion, dietary OE or coccidiostat had no effects on performance or gut integrity. The attenuated inflammatory response observed for all the treatments following the third infection can be attributed to the adaptation or immunization to the repetitive exposure to Eimeria spp.

Local and systemic inflammatory responses to lipopolysaccharide in broilers: new insights using a two-window approach

The inflammatory response involves a complex interplay of local tissue activities designed to recruit leukocytes and proteins from the blood to the infected tissue. For egg-type chickens, we established the growing feather (GF) as an accessible tissue test site to monitor tissue responses to injected test-material. For commercial broilers, whose health depends to a large extent on innate immune system functions, the GF test system offers an important novel window to directly assess their natural defenses. This study was conducted to adapt the GF test system for use in broilers, and use it to simultaneously examine local (GF) and systemic (blood) inflammatory responses initiated by GF pulp injection of lipopolysaccharide (LPS). Specifically, GF of 12 male and 12 female, 5-week-old broilers were injected with LPS (16 GF/chicken; 1 μg LPS/GF). Blood and GF were collected at 0 (before), 6, and 24 h after GF injection. GF pulp was used to determine leukocyte-infiltration and gene-expression profiles, reactive-oxygen-species generation, and superoxide dismutase (SOD) activity. Blood was used to determine blood cell profiles and SOD activity. A time effect (P ≤ 0.05) was observed for most aspects examined. In GF, LPS injection resulted in heterophil and monocyte infiltration reaching maximal levels at 6 and 24 h, respectively. Reactive-oxygen-species generation, SOD activity, and mRNA levels of IL-1β, IL-8, IL-6, IL-10, and cathelicidin B1 were elevated, whereas those of TNF-α, LITAF, SOD1, and SOD2 decreased after LPS injection. In blood, levels of heterophils and monocytes were elevated at 6 h, lymphocytes and RBC decreased at 6 h, and thrombocytes and SOD activity increased at 24 h. Assessment of LPS-induced activities at the site of inflammation (GF) provided novel and more relevant insights into temporal, qualitative, and quantitative aspects of inflammatory responses than blood. Knowledge generated from this dual-window approach may find direct application in identification of individuals with robust, balanced innate defenses and provide a platform for studying the effects of exogenous treatments (e.g., nutrients, probiotics, immunomodulators, etc.) on inflammatory responses taking place in a complex tissue.

Effect of pullet body weight and hen dietary amino acid treatments on their progeny fed high and low amino acid diets

Four studies were conducted on Cobb 700 broilers to evaluate the dietary protein and any maternal effects on live production and processing parameters. Day-old Cobb 700 broiler breeder pullets were reared to conform to 2 different BW curves (control BW and increased BW) with 8 replicate pens per treatment. Birds were fed common diets from 1 d of age until first egg (24 wk). At 24 wk, 12 pens of each pullet treatment were given different amino acid (AA) diets (low = 14% CP, high = 15% CP). The performance of female and male progeny from 32 and 45 wk hens were evaluated on low AA and high AA density diets. The 4 progeny trial designs were identical factorial 2 × 2 × 2 designs, with 2 pullet BW curves (control BW and increased BW), 2 dam CP diet levels (low and high), and 2 progeny CP diets (low and high), with 6 replicates each containing 18 birds, for a total of 108 broiler progeny per treatment. Broiler chickens on the higher AA density feed exhibited consistent improvement in mid-growth BW and FCR and white meat yield percentage. Some maternal effects were noted, including increased carcass yield in female broilers from 32 wk old hens. There were 3-way interactions of pullet BW × hen dietary AA × progeny dietary AA treatments for female progeny carcass yield (from 32-week-old hens) and male tender yield (from 45-week-old hens). There were 2-way interactions of pullet BW x hen dietary AA treatments effect on female and male progeny drumstick yield from 32-week-old hens, pullet BW × progeny dietary AA treatments effect on male 27 d BW from 32-week-old hens, and hen dietary AA × progeny dietary AA treatments effect on male thigh yield from 45-week-old hen. The epigenetic effects of maternal pullet BW and dietary AA treatments were seen in processing yields suggesting, the need of dietary CP changes of the progeny.

Research Note: Evaluation of deoxycholic acid for antihistomonal activity

Deoxycholic acid (DCA) is a naturally occurring secondary bile acid that originates from intestinal bacterial metabolic conversion of cholate, a primary bile acid. Deoxycholic acid was shown to have antihistomonal properties in vitro, leading to our hypothesis that DCA inclusion within the feed might prevent histomoniasis. Selected dietary concentrations of DCA were evaluated for effects on body weight gain (BWG), lesions, and mortality of turkeys challenged with wild-type Histomonas meleagridis (WTH). Treatments consisted of non-challenged control (NC; basal diet), 0.25% DCA diet + challenge, 0.5% DCA diet + challenge, 1% DCA diet + challenge, and a positive-challenged control (PC; basal diet). All groups were fed a basal starter diet until day 7, at which time DCA diets were administered to the respective groups. On day 14, 2 × 10⁵ WTH cells/turkey were intracloacally administered. H. meleagridis-related lesions were evaluated on day 13 post-challenge. Pre-challenge day 0 to 14 BWG was higher (P ≤ 0.05) in the 0.25% DCA group than in the 1% DCA group. There were no significant differences in pre-challenge day 0 to 14 BWG between any of the other groups. No significant differences in mortalities from histomoniasis occurred in the DCA groups as compared to the PC group. No H. meleagridis lesions or mortalities were observed at any time in the NC group. Presence of H. meleagridis-related liver lesions was higher (P ≤ 0.05) in the 0.5% DCA group as compared to the PC group. Using the same controls and experimental timeline, an additional group was included to evaluate a biliogenic diet formulated with 20% whole egg powder to encourage endogenous bile acid production. The biliogenic diet had no statistical impact on pre-challenge day 0 to 14 BWG, but did not reduce H. meleagridis-related mortalities or lesions after the challenge. Taken together, these data suggest that DCA inclusion within the feed at these concentrations and under these experimental conditions does not prevent histomoniasis.

Influence of coccidiosis vaccination on nutrient utilization of corn, soybean meal, and distillers dried grains with solubles in broilers

Two experiments were conducted to determine the impact of coccidiosis vaccination on the apparent ileal digestibility (AID) of nutrients and ileal digestible energy (IDE) in commonly used feed ingredients in broilers. Eight experimental treatments based on a factorial arrangement of coccidiosis vaccination (control with in-feed diclazuril [CTL] or vaccinated [VAC]) and 4 different diets were administered to male Cobb 500 broilers in floor pens containing 12 birds per pen. For the vaccinated group, a 3× dose of a live coccidiosis vaccine was given via oral gavage on the day of hatch. Experimental diets consisted of a basal diet and 3 test diets in which 30% of the basal diet was replaced with either corn, soybean meal (SBM), or distillers dried grains with solubles (DDGS) to allow for calculation of nutrient digestibility of individual ingredients by difference. Broilers were fed a common diet from 0 to 7 D and experimental diets from 7 to 12 D. On day 12, blood and ileal digesta were collected to measure plasma carotenoids and determine AID of nitrogen, ether extract, IDE (experiments 1 and 2), and amino acids (AA) (experiment 2). Vaccination increased (P < 0.05) excreta oocyst counts and decreased (P < 0.05) plasma carotenoids when compared with CTL birds. Interactive effects (P < 0.05) were observed for AID of nitrogen (experiment 1) which was reduced by vaccination in birds fed the corn diet and increased for birds fed DDGS. No differences (P > 0.05) in IDE were observed between VAC and CTL birds in either experiment, whereas vaccination decreased (P < 0.05) AID of ether extract independently of diet. Interactive effects (P < 0.05) were observed for AA digestibility, whereby digestibility of all AA was reduced by VAC in corn diets but generally increased AA digestibility of DDGS diets, with minimal impact on SBM diets. In conclusion, the impact of coccidiosis vaccination on nutrient and energy digestibility varied among ingredients; however, digestibility was minimally impacted or improved with DDGS.

Longitudinal Characterization of Coccidiosis Control Methods on Live Performance and Nutrient Utilization in Broilers

An experiment was conducted to quantify the timing and magnitude of the effects of coccidiosis vaccination on the growth performance, apparent ileal digestibility (AID) of nutrients and energy, intestinal morphology, and plasma carotenoids and nitric oxide in broilers. Treatment groups consisted of 3 coccidiosis control methods [unvaccinated, unmedicated (NC), in-feed chemical coccidiostat (PC), and live oocyst vaccination (VAC) at day of hatch] administered to male Cobb broilers reared in floor pens. Body weight gain (BWG), feed intake (FI), and feed conversion ratio (FCR) were determined at 12, 16, 20, 28, and 36 d. Blood and ileal digesta were collected from birds in 10 replicate pens of each treatment at 12, 16, 20, and 36 d to evaluate plasma carotenoid and nitric oxide concentrations and determine nutrient AID and IDE. Jejunal samples were taken at 12, 20, and 36 d for morphological measurements. Oocyst shedding in VAC birds was confirmed by increased oocyst counts and decreased carotenoid concentrations (P < 0.05) when compared with PC birds, with no differences (P > 0.05) in nitric oxide concentrations. At 20 d, BWG and FI were lowest (P < 0.05) in VAC birds, intermediate in NC birds, and highest in PC birds, with no differences in FCR (P > 0.05). By 28 and 36 d, FCR was higher (P < 0.05) for VAC and NC birds but BWG and FI of VAC birds were similar (P > 0.05) to PC birds. At d 12, IDE and AID of nitrogen and ether extract were lower (P < 0.05) in VAC birds than PC birds. At d 16, AID of nitrogen was similar (P > 0.05) between PC and VAC birds, whereas AID of ether extract remained lower in VAC birds than PC birds. No differences in AID of nutrients or IDE were observed (P > 0.05) between VAC and PC birds at 20 or 36 d. No differences (P > 0.05) in jejunal morphology were observed at any time point. Overall, VAC elicited a transient reduction in AID and IDE, particularly for lipids, that diminished by d 20.

Effects of pre-starter and starter diets varying in amino acid density given to broiler chickens that received coccidiosis vaccination at hatch1

An experiment was conducted to evaluate broilers vaccinated against coccidiosis fed combinations of pre-starter and starter diets varying in digestible amino acid (dAA) density from 1 to 19 d of age on subsequent growth performance and meat yield. A total of 1,800 Yield Plus Ross × Ross 708 male broilers were allocated to 60 floor pens and assigned to 1 of the 6 treatments. Four pre-starter diets varying in dAA density [1.15% dLys, 1.25% dLys, 1.35% dLys, and Positive Control (1.15% dLys + Diclazuril)] were fed until 9 d of age. Then, 3 starter diets varying in dAA density [1.15% dLys, 1.25% dLys, and PC (1.15% dLys + Diclazuril)] were given from 10 to 19 d of age. All diets were formulated to similar dAA ratios to dLys; hence, resulting in increasing amino acid (AA) density among the dietary treatments. Birds were given common grower and finisher diets for the remainder of the experiment. At 19, 27, and 40 d of age, broilers that received the 1.35% and 1.25% dLys density pre-starter and 1.25% dLys density starter diets had increased BW gain (P ≤ 0.006) compared with broilers fed the 1.15% dLys density diets. Broilers that received the 1.15% dLys density pre-starter diet had a lower cumulative BW gain (P = 0.007) than those fed the 1.35% and 1.25% dLys density pre-starter diets. Broilers that received the 1.35% and 1.25% dLys density pre-starter and 1.25% dLys density starter diets had the heaviest (P ≤ 0.008) total breast weights. Increasing the pre-starter dAA density enhanced (P ≤ 0.03) total breast weight by 28 g (1.25% dLys density) and 51 g (1.35% dLys density). Results from this study indicated that increasing dAA density from 1 to 19 d of age enabled a 1 to 19 d dAA intake increase of 4.8 g, which enhanced cumulative growth and meat yield of broilers vaccinated against coccidiosis.

Effects of dietary amino acid density and feed allocation during the starter period on 41 days of age growth performance and processing characteristics of broiler chickens given coccidiosis vaccination at hatch1

A study was conducted to determine if increasing digestible (dig) amino acid (AA) density or feed allocation of starter diets fed to broilers receiving coccidiosis vaccination can ameliorate poor cumulative growth performance and reduce meat yield. A total of 1,600 Yield Plus Ross × Ross 708 male broilers were assigned to a 2 × 3 factorial arrangement of dig AA density [moderate (1.15% dig Lys) and high (1.25% dig Lys)] and feed allotment (0.45, 0.73, and 1.00 kg/bird) with 2 positive control treatments during the starter period. Diets were formulated to essential AA ratios relative to dig Lys. Vaccinated birds received a 1x dosage of Coccivac- B52 prior to placement, whereas non-vaccinated birds in the positive control groups were fed diets containing diclazuril. Following consumption of the starter diets, birds were provided common grower and finisher diets. Broilers fed the high AA density diet during the starter period had higher cumulative BW gain and lower cumulative feed conversion ratios (P < 0.05) than those fed the moderate AA density diet. Broilers fed the high AA density diet had heavier (P ≤ 0.005) carcass and total breast weights than birds fed the moderate AA density diet. Broilers fed a starter allotment of 1.00 kg/bird produced heavier carcass weights (P ≤ 0.006) than did birds provided lower allotments. Additionally, broilers fed the high AA density diet had a greater percentage of 0 scores (P = 0.005) for the upper intestinal region during scoring. Results from this study indicated that feeding the high AA density diet at higher feed allotments during the starter period resulted in increased AA intake, which supported the bird through the vaccine challenge and enhanced the cumulative growth and meat yield.

Effects of dietary copper and amino acid density on growth performance, apparent metabolizable energy, and nutrient digestibility in Eimeria acervulina-challenged broilers

The objective of this experiment was to evaluate the influence of copper supplementation in diets varying in amino acid (AA) density on growth performance, apparent metabolizable energy (AMEn), apparent ileal nutrient digestibility (AID), and plasma carotenoids in broilers infected with Eimeria acervulina. Ross 308 male broilers (480 total) were housed in battery cages and allotted to 8 experimental treatments in a factorial arrangement of 2 dietary AA densities [1.00% (LAA) or 1.20% (HAA) digestible Lys], 2 supplemental copper concentrations (zero or 116 mg/kg), and 2 E. acervulina infection states (uninfected or infected). Essential AA ratios relative to digestible Lys were similar in both the LAA and HAA diets, and copper was provided by 200 mg/kg of tribasic copper chloride (58% copper). Chicks received experimental diets from 2 to 21 d post hatch and 6 replicate cages of 10 birds per cage were assigned to each treatment. Broilers were inoculated with zero or 6.3 × 105 sporulated E. acervulina oocysts at 15 d and blood and ileal digesta were collected at 21 days. From 2 to 15 d, body weight gain and G:F of broilers were improved (P < 0.05) with increasing AA density, and an AA density × copper interaction was observed (P < 0.05) for feed intake. Eimeria infection reduced (P < 0.05) plasma carotenoids, growth performance, dietary AMEn, and AID of organic matter, nitrogen, and total AA. There were no interactive effects of dietary treatments with E. acervulina infection on broiler growth performance or dietary AMEn. An AA density × copper supplementation interaction was observed (P < 0.05) for AID of total AA, whereby copper supplementation increased AID of total AA for birds fed the LAA diet and decreased AID of total AA for birds fed the HAA diet. In summary, E. acervulina-induced reductions in nutrient digestibility were dependent on dietary copper and AA status, but changes in digestibility had minimal impact on growth performance of broilers during the E. acervulina infection period.

Interactive effects of dietary arginine and Eimeria acervulina infection on broiler growth performance and metabolism

The influence of dietary Arg concentration and Eimeria acervulina infection on broiler growth performance and plasma carotenoid, nitric oxide (NO), amino acid, and urea concentrations was evaluated. Male Ross × Ross 308 broilers (384 total) were fed a common diet for 10 d post-hatch and provided experimental diets formulated to contain 1.23 (HA) or 0.74% (LA) standardized ileal digestible Arg from 10 to 28 d. At 21 d, one-half of the broilers were switched to the opposite diet to create 4 dietary regimens where birds were fed the LA diet throughout, the LA diet replaced by the HA diet at 21 d, the HA diet throughout, or the HA diet replaced by the LA diet at 21 d. Broilers were orally inoculated 0 (uninfected) or 3.5 × 105 sporulated E. acervulina oocysts at 15 d, resulting in a factorial arrangement of 4 dietary regimens × 2 infection states (8 replicates/treatment). Overall (10 to 28 d) BW gain and G:F were greatest (P < 0.01) for birds fed the HA diet throughout, regardless of infection status. Eimeria acervulina infection decreased (P < 0.01) BW gain of birds from 15 to 21 d, and G:F was lowest (P < 0.05) for infected birds fed the LA diet during this period. There was no influence (P > 0.05) of E. acervulina on BW gain or G:F of broilers from 21 to 28 d. Plasma Arg, Lys, and Orn levels at 21 d indicated that the LA diet caused an imbalance in the Lys and Arg status of broilers, and E. acervulina infection increased (P < 0.01) the plasma concentration of these 3 amino acids. Diet × infection interactions (P < 0.05) were observed on 21 d for plasma carotenoids and NO, whereby infection decreased plasma carotenoids and increased plasma NO, but dietary Arg concentration only influenced these measures for uninfected birds. Thus, production of NO during E. acervulina infection was not impaired by dietary Arg limitation.

Influence of dietary amino acid reductions and Eimeria acervulina infection on growth performance and intestinal cytokine responses of broilers fed low crude protein diets

Two experiments were conducted to evaluate the influence of Eimeria acervulina infection on growth performance, plasma carotenoids, and intestinal cytokine responses of broilers fed low crude protein (LCP) diets with reduced concentrations of selected amino acids (AA). Experiment 1 was conducted to validate a dietary formulation approach in which broilers were fed 1 of 5 diets including a 19.0% CP corn-soybean meal based (CSBM) diet, a LCP control diet (16.7% CP) that matched the AA profile of the CSBM diet, and 3 LCP diets with 30% reductions in standardized ileal digestible concentrations of TSAA, Lys, or Thr from 14 to 23 d post-hatch. Body weight gain and G:F were greatest (P < 0.05) and similar for broilers fed the CSBM and LCP control diets, whereas reductions in Thr, TSAA, and Lys each decreased (P < 0.05) G:F of broilers. In Experiment 2, birds were allotted to 18 treatment groups in a factorial arrangement of 9 dietary treatments × 2 infection states. Dietary treatments included a LCP control diet similar to that fed in Experiment 1 and 8 LCP diets with 40% individual reductions in TSAA, Lys, Thr, Val, Ile, Arg, Phe + Tyr, or Gly + Ser. Broilers received experimental diets from 10 d to 28 d post-hatch and were inoculated with 0 or 4.0 × 10⁵ sporulated E. acervulina oocysts at 15 d. Decreased (P < 0.05) growth performance (10 to 28 d) of broilers was observed with each AA reduction, except Phe + Tyr, compared with birds fed the LCP control diet. Body weight gain and G:F were lowest (P < 0.05) for birds fed diets reduced in Lys or Val. Eimeria acervulina decreased growth performance and plasma carotenoids of broilers, but effects varied among dietary treatment groups as indicated by diet × infection interactions (P < 0.05). Dietary AA reductions did not alter (P > 0.05) the increase in intestinal gene expression of interferon-γ, interleukin-1β, or interleukin-10 observed in E. acervulina-infected birds.

Effects of dietary soybean meal concentration on growth and immune response of pigs infected with porcine reproductive and respiratory syndrome virus

An experiment was conducted to determine the effects of dietary soybean meal (SBM) concentration on the growth performance and immune response of pigs infected with porcine reproductive and respiratory syndrome virus (PRRSV). Four experimental treatments included a 2 × 2 factorial arrangement of 2 dietary SBM concentrations, 17.5% (LSBM) or 29% (HSBM), and 2 levels of PRRSV infection, uninfected sham or PRRSV infected. Sixty-four weanling pigs of split sex (21 d of age, 7.14 ± 0.54 kg) were individually housed in disease containment chambers. Pigs were provided a common diet for 1 wk postweaning before being equalized for BW and sex and allotted to 4 treatment groups with 16 replicate pigs per group. Pigs were fed experimental diets for 1 wk before receiving either a sham inoculation (sterile PBS) or a 1 × 10 50% tissue culture infective dose of PRRSV at 35 d of age (0 d postinoculation, DPI). Pig BW and feed intake were recorded weekly, and rectal temperatures were measured daily beginning on 0 DPI. Blood was collected on 0, 3, 7, and 14 DPI for determination of serum PRRSV load, differential complete blood cell counts, and haptoglobin and cytokine concentrations. Infection with PRRSV increased (P < 0.01) rectal temperatures of pigs throughout the infection period, with no influence of dietary SBM concentration. Pigs in the PRRSV-infected group had lower (P < 0.01) ADFI and G:F from 0 to 14 DPI compared with uninfected pigs. In the PRRSV-infected group, pigs fed HSBM tended to have improved ADG (P = 0.06) compared with pigs fed LSBM, whereas there was no influence of SBM concentration on growth of pigs in the uninfected group. At 14 DPI, PRRSV-infected pigs fed HSBM had a lower serum PRRSV load (P < 0.05), a higher (P = 0.02) hematocrit value, and a tendency for greater hemoglobin concentration (P = 0.09) compared with pigs fed LSBM. Serum haptoglobin and tumor necrosis factor-α concentrations of PRRSV-infected pigs were lower (P < 0.05) in pigs fed HSBM at 3 and 14 DPI, respectively, than in pigs fed LSBM. Overall, increasing the dietary SBM concentration modulated the immune response and tended to improve the growth of nursery pigs during a PRRSV infection.

Effects of feeding diets varying in energy and nutrient density to Hy-Line W-36 laying hens on production performance and economics

The objectives of this study were to evaluate the effects of feeding 5 different energy and nutrient dense diets to Hy-Line W-36 hens on long-term performance and economics. A total of 480 19 wk old Hy-Line W-36 Single Comb White Leghorn hens were weighed and randomly allocated to 6 replicate groups of 16 hens each (2 adjacent cages containing 8 hens per cage, 60.9×58.4 cm) per dietary treatment in a randomized complete block design. The hens were fed 5 treatment diets formulated to contain 85, 90, 95, 100, and 105% of the energy and nutrient recommendations stated in the 2009 Hy-Line Variety W-36 Commercial Management Guide. Production performance was measured for 52 wk from 19 to 70 wk age. Over the course of the trial, a significant increasing linear response to increasing energy and nutrient density was seen for hen-day egg production, egg weight, egg mass, feed efficiency, energy intake, and body weight (BW). Feed intake showed no significant linear level response to increasing energy and nutrient density except during the early production cycle. No consistent responses were noted for egg quality, percent yolk, and percent egg solids throughout the study. Significant linear responses due to energy and nutrient density were seen for egg income, feed cost, and income minus feed cost. In general, as energy and nutrient density increased, egg income and feed cost per hen increased, but income minus feed cost decreased. Overall, these results indicate that feeding Hy-Line W-36 hens increasing energy and nutrient-dense diets will increase egg production, egg weight, egg mass, feed efficiency, energy intake, BW, egg income, and feed cost, but decrease egg income minus feed cost. However, these benefits do not take effect in early production and seem to be most effective in later stages of the production cycle, perhaps "priming" the birds for better egg-production persistency with age.

Effects of diet type and ingredient composition on rate of passage and apparent ileal amino acid digestibility in broiler chicks

This experiment evaluated rate of passage (ROP) and apparent ileal amino acid digestibility (AIAAD) of 4 diets varying in ingredient composition fed to broilers from 14 to 22 d of age. Two hundred and 88 Ross × Ross 708 chicks (12 birds per cage; 0.45 m(2) per bird) were randomly assigned to 24 cages (6 replicate cages per treatment) at 1 d of age. Experimental diets were 1) corn-soybean meal-based (CSM) diet containing porcine meat and bone meal (MBM; 5% inclusion), 2) CSM diet containing distillers dried grains with solubles (DDGS; 5% inclusion), 3) semipurified (SP) diet containing MBM (38% inclusion), and 4) SP diet containing DDGS (76% inclusion). Diets were formulated to contain 20% CP and were adequate for vitamins and minerals. Experimental diets were provided from d 14 to 22. On d 18, a total excreta collection was conducted every hour for 12 h from 0800 to 1900 h to determine ROP, and AIAAD was determined on d 22. Time of 1% TiO(2) excretion (T1), 50% TiO(2) excretion (T50), and mean retention time (MRT) were used to express ROP. The SP-MBM diet reached T1 (P < 0.05) faster than the SP-DDGS or 2 CSM diets. However, T50 indicated a faster (P < 0.05) ROP for SP-DDGS than the 2 CSM diets, and no significant difference was observed between the 2 SP diets. The MRT of the SP-DDGS diet (5.13 h) was less (P < 0.05) than the MRT of the SP-MBM, CSM-MBM, and CSM-DDGS diets, which resulted in values of 5.48, 5.62, and 5.58 h, respectively. In general, the AIAAD values were higher (P < 0.05) for the 2 CSM diets than for SP diets. Except for His, no statistical differences were observed between the AIAAD of the 2 CSM diets. Comparing the 2 SP diets, AIAAD was usually similar or higher (P < 0.05) for SP-DDGS, except for His, Lys, and Gly, which were higher (P < 0.05) for SP-MBM. Based on T50 and MRT, SP diets containing DDGS had a faster ROP in broilers than CSM diets or SP diets containing MBM.