Feed Intake Research Articles

145 Performance, postweaning diarrhea, and apparent total tract nutrient digestibility responses of weanling pigs to nucleotide supplementation of low-protein diets

Abstract Feeding low protein (LP) diets to nursery pigs has been reported to improve intestinal health, reduce incidence of post-weaning diarrhea (PWD) and nitrogen excretion. However, these benefits are often undermined by significant reduction in growth performance. This study evaluated the effects of low protein diets supplemented with dietary nucleotides on growth performance, post weaning diarrhea and nitrogen utilization. A total of 210 piglets (Duroc × Landrace × Yorkshire) were weaned at 21 d of age and allowed a 3-d adaptation to a common solid post weaning diet. At 24 d old, pigs were reweighed (6.02 ± 0.05 kg) and allocated to 5 dietary treatments in a completely randomized block design to give 7 replicates per treatment (n = 6 piglets per replicate). The 5 dietary treatments included i) a high protein positive control diet (PC) with 24% crude protein (CP); ii) a low protein negative control (NC) with 16% CP; iii) NC with 0.1% dietary nucleotide inclusion (NC01); iv) NC with 0.3% dietary nucleotide inclusion (NC03); and v) NC with 0.9% dietary nucleotide inclusion (NC09). All diets were corn-soybean meal based, supplemented with lysine, methionine, tryptophan, and threonine, with all low protein diets (LP) additionally fortified with crystalline isoleucine, and valine to meet the ideal amino acid requirements. Diets were provided ad libitum for 35 d and weekly feed intake (FI) and body weight (BW) were measured. On d 35, blood and fecal samples were collected to determine serum metabolites and nutrient digestibility respectively. Data were analyzed by PROC GLM and orthogonal polynomial contrast of SAS. Comparison between positive and negative control diets and nucleotide levels were performed with orthogonal contrast analysis. Relative to PC, NC diet had decreased overall average daily gain (343.5 vs. 305.5 g/d), incidence of PWD (2.5 vs. 1.2 fecal consistency score), blood urea nitrogen (BUN; 11.3 vs. 3.4 mg/dL) and total tract digestibility of energy (81.3 vs. 80.1 %; P < 0.05, P < 0.05, P < 0.0001 and P < 0.1, respectively). Relative to PC, the NC01, NC03 and NC09 treatments had comparable average daily gain (P > 0.05) while maintaining reduced (P < 0.05) BUN and incidence of PWD. Total tract digestibility of dry matter (83.1 vs. 82.1%) and energy (81.3 vs. 80.1%) were similar between PC and NC09 treatments (P > 0.05). Crude protein reduction decreased serum glutathione (P < 0.05), but without an effect of nucleotide supplementation. Serum glucose and insulin concentrations were not different across treatments (P > 0.05). Results suggest that feeding LP diets supplemented with dietary nucleotide after weaning can increase protein utilization efficiency, reduce incidence of PWD while partially ameliorating the negative effects of LP diets on growth performance.

179 Effects of Saccharomyces yeast postbiotics on intestinal health of newly weaned pigs challenged with F18+ Escherichia coli.

Abstract The purpose of this study was to investigate the effects of Saccharomyces yeast postbiotics (celluTEIN, Puretein Biosecience LLC, Minneapolis, MN, USA) on the intestinal health and growth performance of newly weaned pigs challenged with F18+ Escherichia coli. Nursery pigs [n =36; initial body weight (BW) = 6.42 ± 0.33 kg BW] were allotted into three dietary treatments utilizing a randomized complete block design with sex and initial BW as blocks. The dietary treatments included a negative control (NC: basal diet, no challenge), a positive control (PC: basal diet, challenged with F18+ E. coli), and SYP (basal diet with Saccharomyces yeast postbiotics at 175 g/ton of feed, challenged with F18+ E. coli). Basal diets were formulated to meet NRC (2012) requirements with Saccharomyces yeast postbiotics replacing corn in the basal diet. Pigs were fed for 28 d in 3 phases (P1: 11 d, P2: 10 d, P3: 7 d). Pigs in PC and Saccharomyces yeast postbiotics were orally inoculated with F18+ E. coli (2.0 × 1010 CFU), whereas the NC group received sterile saline, given in 4 doses beginning on d 7 after weaning. Throughout, fecal score, BW, and feed intake were recorded to calculate average daily gain (ADG), average daily feed intake (ADFI), and gain to feed ratio (G:F). At d 28, all pigs were euthanized for sampling of the jejunal mucosa to analyze oxidative stress and immune status, as well as microbiota diversity and relative abundance. Data were analyzed using the Proc Mixed in SAS 9.4 (Cary, NC). Overall, PC reduced (P < 0.05) the BW, ADG, and ADFI of pigs. The SYP had a tendency (P = 0.098) to improve the ADFI of pigs challenged with F18+ E. coli. The fecal score of pigs fed SYP were improved (P < 0.05) on d 7 to 18 of the post-challenge period when compared with PC. Furthermore, SYP reduced protein carbonyl (P < 0.05), reduced (P < 0.05) the relative abundance of Erysipelotrichaceae, and had a tendency to increase Leuconostocaceae (P = 0.090), Streptococcaceae (P = 0.068), Corynebacteriaceae (P = 0.085), and had a tendency to reduce (P = 0.077) Ruminococcaceae when compared with PC. Additionally, SYP reduced (P < 0.05) gene expression of toll-like receptor 4 (TLR4) and increased (P < 0.05) gene expression mammalian target of rapamycin (mTOR), when compared with PC. In conclusion, challenge with F18+ E. coli increased fecal score, disrupted the microbiota composition in the jejunal mucosa, and increased gene expression associated with recognition of pathogens, without any impact on inflammation; therefore, negatively affecting growth performance. Saccharomyces yeast postbiotics could reduce the negative effects associated with F18+ E. coli infection by altering microbial diversity and reducing inflammation associated with expression of TLR4, and oxidative stress products, without changes in growth.

PSV-16 Effect of precision feeding and functional amino acids on immune response and protein metabolism of growing pigs raised in poor sanitary conditions

Abstract The activation of the immune system reduces the nutrient availability for growth and increases the variability among pigs. Functional amino acids (AA) supplementation can reduce the negative effects of immune activation. Additionally, providing daily tailored diets using individual precision feeding (IPF) was shown to account for individual variability. Therefore, we hypothesized that the association of IPF and functional AA supplementation could reduce the negative effect of immune-challenged pigs fed with daily tailored diets. The aim of this study was to assess performance and blood parameters variation of growing pigs under poor sanitary conditions while being fed functional AA 120% above the estimated INRA AA ratios within IPF, compared with a conventional group-phase (GP) feeding system. The sanitary condition was characterized by oral inoculation of 2 × 109 cfu of Salmonella typhimurium and manure spreading on the pen floor on d 0. Sixty gilts (23 ± 2.8 kg body weight; BW) were distributed in a complete randomized block design in a 2 x 2 factorial arrangement composed of 2 diets: CN with 100% INRA AA ratio or AA+ with 120% of the ratio for Met, Thr and Trp; and 2 feeding systems: GP or IPF. GP pigs received a single diet matching the SID Lys requirement of the 80th-percentile pig at the beginning of the trial whereas IPF pigs received a diet tailored daily to each pig requirement. All pigs were group-housed and fed ad libitum for 28 d by automatic feeders. Body weight was measured at d 0 and 28 and feed intake was recorded daily. Blood samples were collected at d 0, 7 and 28. Data were analyzed with diet and feeding systems and their interactions as fixed effects and BW blocks as random effect. Blood parameters were analyzed as repeated measurements over time. The pig was considered the experimental unit. No diet effect or interactions were observed for any variable (P > 0.05), suggesting that only supplementing Met, Trp, and Thr is not enough to support growth during a sanitary challenge (Table 1). Haptoglobin and IgG increased linearly whereas IgA, urea, and creatinine had a quadratic increase over time (P < 0.05; Table 2). The IPF decreased growth performance and increased serum IgA and creatinine (P < 0.05), mostly due to the fact that IPF reduces AA provision compared with GP system. The IPF model, as most mathematical models, does not account for the AA and energy costs related to the immune challenge. Therefore, IPF might have underestimated the requirements of the pigs, and limited the amount of nutrients provided. In conclusion, the combined effect of IPF and functional AA supplementation was not able to reduce the negative effect of the sanitary challenge.

201 The effects of the supplementation of a Zinc-amino acid complex in pig nursery diets with differing pharmacological levels of zinc oxide and complexity

Abstract Diet complexity (DC), which has significance in nursery pig production, generally refers to a greater number of highly digestible ingredients. Increased DC may have even greater significance in scenarios of reduction or withdrawal of zinc oxide (ZnO) in nursery diets. The objectives were to determine 1) the impact of adding Zn-amino acid complex (Zinpro ProPath Zn) to mid- (MC) and low-complexity (LC) diets on nursery pig performance and health compared with a high complexity (HC) diet, and 2) the impact of Zinpro ProPath Zn in diets with and without pharmacologic levels of ZnO. A total of 2,400 mixed-sex weanling pigs [initial body (BW) weight = 5.79 ± 0.15 kg] were assigned to 1 of 5 dietary treatments during nursery (42 d) as follows: 1) HC; MC diet with 2) MC+ZnO) or without 3) MC-ZnO) pharmacologic ZnO; and LC diet with 4) LC+ZnO) or without 5) LC-ZnO) pharmacologic ZnO. All diets except HC were supplemented with Zinpro ProPath Zn (125 mg/kg Zn) and ZnO [3,000, 2,000, and 0 mg/kg Zn during Phases I (14 d), II (14 d) and III (14 d), respectively]. Different DC were achieved by manipulating the inclusion of spray-dried plasma, soy protein concentrate, and whey protein. Growth performance, onset of feed intake, fecal dry matter, number of injectable treatments administered, and serum acute-phase response were assessed. Pigs fed HC (20.0 kg) had greater final BW (FBW) compared with pigs fed MC-ZnO (18.8 kg), which had greater FBW compared with pigs fed LC-ZnO (17.5 kg; SEM = 0.34; P < 0.05). Average daily feed intake (ADFI) was greater in pigs fed HC (0.46 kg/d) compared with MC-ZnO (0.43 kg/d) and LC+ZnO (0.42 kg/d), which had greater ADFI compared with LC-ZnO (0.39 kg/d; SEM = 0.01; P < 0.05). Similarly, average daily gain (ADG) and gain to feed ratio (G:F) were greater in pigs fed HC (0.33 kg/d, 0.72 kg/kg, respectively) compared with pigs fed LC (0.27 kg/d, 0.67 kg/kg, respectively), regardless of ZnO (SEM = 0.01; P < 0.05). There was no effect of dietary treatments on the fecal dry matter or on the onset of feed intake of pigs (P > 0.10). The number of injectable treatments administered was greatest in LC-ZnO (62.7%), followed by LC+ZnO (50.6%), MC regardless of ZnO (44.0%), and HC (36.7%; SEM = 1.04; P < 0.05). Serum alkaline phosphatase was less in LC-ZnO than the other groups (229.8 vs. 280.9 ± 11.9 IU/L; P < 0.05). Taken together, feeding HC diets during the nursery appears to be effective in improving performance and health of pigs, particularly when compared with MC and LC diets without ZnO. Moreover, the addition of Zinpro ProPath Zn may partially attenuate the negative effects of ZnO removal in MC, but not LC, diets.

140 Response of 6 to 13 kg nursery pigs to increasing SID Arg:Lys

Abstract Newly weaned pigs (n = 480; PIC 337 × 1050; Genus, Hendersonville, TN) with an initial body weight (BW) of 6.20 ± 0.61 kg were used in a dose-response study to evaluate the effects of increasing standardized ileal digestible (SID) Arg:Lys in nursery pigs. At weaning, pigs were placed into 48 pens with five barrows and five gilts per pen and randomly assigned to one of six dietary treatments. The experimental diets were formulated with increasing levels of SID Arg by replacing corn starch, glycine, and L-alanine with L-arginine. Levels of SID Arg:Lys ranged from 45 to 145%. Diets were sub-limiting in SID Lys and exceeded all other essential amino acid requirements. Furthermore, diets were formulated to be isocaloric, isonitrogenous, and met or exceeded NRC (2012) vitamin and mineral recommendations. The experimental diets were fed in two feeding phases from d 0 to 10 and d 10 to 27, with adjustments made to account for the decreasing Lys requirement of the pigs. Pigs were subsequently fed a common diet for the remaining 14 d of the nursery period to determine carryover effects. Pigs and feeders were weighed at the beginning and end of each dietary phase for the calculation of average daily gain (ADG), average daily feed intake (ADFI), and feed efficiency (gain to feed ratio; G:F). The data were fit using linear regression with R version 4.3.1 (R Core Team, 2023). The model included linear and quadratic effects of SID Arg:Lys and initial BW. Pen was the experimental unit, and results were considered significant at P ≤ 0.05 and a tendency at 0.05 < P ≤ 0.10. There was a significant linear and quadratic effect of SID Arg:Lys on BW on d 27 (P ≤ 0.024), where BW was maximized at a SID Arg:Lys 97.09%. From d 0 to 27 there was a linear and quadratic tendency of SID Arg:Lys on ADFI (P = 0.069), where feed intake was maximized at a SID Arg:Lys of 97.00%. Furthermore, there tended to be a linear and quadratic effect of SID Arg:Lys on ADG from d0 to 27 (P ≤ 0.081), where ADG was maximized at a SID Arg:Lys of 95.65%. There was no evidence for an effect of SID Arg:Lys on G:F at any timepoint throughout the trial (P ≥ 0.298). In conclusion, SID Arg:Lys linearly and quadratically impacted ADFI and ADG in 6 to 13 kg nursery pigs, where ADG was maximized at a SID Arg:Lys of 95.65%, but ADFI was maximized at a SID Arg:Lys of 97.00%. Together, these data suggest that the SID Arg:Lys requirement of nursery pigs is greater than NRC (2012) recommendations, and excessive Arg supplementation may have negative consequences on growth performance.

181 Effects of Soy protein concentrate replacing conventional soybean meal on intestinal health and growth of newly weaned pigs challenged with F18+ Escherichia coli.

Abstract This study aims to investigate the impact of various levels of soy protein concentrate (SPC) replacing conventional soybean meal (SBM) on various parameters related to intestinal health and growth performance of nursery pigs under F18+ Escherichia coli challenge. Newly weaned pigs [n = 72; initial body weight (BW) = 6.6 ± 0.3 kg] were randomly allotted to 6 treatment groups based on randomized complete block design with initial BW and sex as blocks and fed for 25 d (P1/2 for 11/14 d, respectively). The treatment groups were 1) NC: a diet with conventional SBM, 2) PC: NC with F18+ E. coli challenge at d 7 (2.1 × 1010 CFU); 3) T1: PC with 5% SPC replacing conventional SBM; 4) T2: PC with 10% SPC replacing conventional SBM; 55) T3: NC with 10% SPC replacing conventional SBM, and 6) AGP: PC with 0.25% bacitracin methylene disalicylate. At the end of study, all pigs were euthanized to collect jejunal tissues to measure parameters related to intestinal health. Data were analyzed using MIXED procedure in SAS. The PC decreased (P < 0.05) average daily gain (ADG) and average daily feed intake (ADFI) on d 7 to d 25 (post-challenge) compared with NC. The T2 decreased (P < 0.05) ADG and ADFI on post-challenge period compared with T3. The ADG tended to linearly decrease (P = 0.067) and ADFI linearly decrease (P < 0.05) on post-challenge period with increasing SPC supplementation replacing SBM in the diets. The E. coli challenge increased (P < 0.05) fecal score in PC, and T2 treatments compared with NC, and T3, respectively. The tumor necrosis factor-alpha (TNF-α) in jejunal mucosa linearly increased (P < 0.05) with increasing SPC supplementation replacing SBM in nursery diets under E. coli challenge. The PC decreased (P < 0.05) interleukin-8 (IL-8) compared with NC. The PC (P = 0.078) and T3 (P = 0.099) tended to decrease immunoglobulin A (IgA) compared with NC. The AGP increased (P < 0.05) IgA compared with PC. The AGP increased (P < 0.05) the expression of occludin (OC) compared with PC. The expression of OC tended to linearly decrease (P = 0.099) with increasing SPC supplementation replacing SBM in nursery diets under E. coli challenge. The T2 increased (P < 0.05) villus height to crypt depth ratio (VH:CD) compared with T3. In conclusion, supplementation of SPC replacing SBM in the diet did not alleviate the deleterious effect of E. coli challenge on growth performance nursery pigs, which might be contributed by reduced feed intake. Additionally, supplementation of SPC seems to exacerbate the negative effect of E. coli challenge with increased intestinal inflammation and intestinal disintegration.

PSII-15 Effect of 25-hydroxyvitamin D3 supplementation on growth performance of nursery pigs

Abstract This study was conducted to evaluate the effects of 25-hydroxyvitamin D3 (25OHD3) supplementation on the growth performance of nursery pigs. A total of 48 newly weaned piglets (5.27 ± 1.42 kg initial body weight; weaned at 18.7 ± 0.78 d of age) were allotted to 3 treatments in 4 replicates with 4 pigs per pen based on body weight, sex, breed, and littermates. Treatments were: 1) VD-2: basal diet with 2,000 IU/kg vitamin D3, 2) 25D-1: basal diet with 1,000 IU/kg 25-OHD3 supplementation, and 3) 25D-2: basal diet with 2,000 IU/kg 25-OHD3 supplementation. All pigs were housed in nursery pens with free access to water and feed in the environmentally controlled nursery facility. Corn-soybean meal-based diets that met or exceeded the NRC (2012) nutrient requirement estimates were fed to all piglets in two phases for d 0-14 (Phase 1) and d 14-28 (Phase 2) postweaning. In each phase, a basal diet without vitamin D was mixed first, and then each vitamin D source was added to the basal diet at the assigned level. Body weight and feed disappearance were measured weekly to calculate average daily gain (ADG), average daily feed intake (ADFI), and gain to feed ratio (G:F). There was no significant difference in body weight throughout the entire nursery period, ADG, ADFI, and G:F in d 0-14 postweaning except for a slightly greater G:F in the 25D-2 treatment than the 25D-1 treatment in d 0-7 postweaning (P = 0.11; 0.368, 0.357, and 0.519 for VD-2, 25D-1, and 25D-2, respectively). In d 21-28 postweaning, the 25D-1 and 25D-2 treatments tended to have greater ADG (P < 0.08; 0.576, 0.632, and 0.634 kg/d for VD-2, 25D-1, and 25D-2, respectively) and ADFI (P < 0.05; 0.862, 0.932, and 0.932 kg/d for VD-2, 25D-1, and 25D-2, respectively) than the VD-2 treatment, resulting in slightly greater ADG (P < 0.08; 0.502, 0.536, and 0.534 kg/d for VD-2, 25D-1, and 25D-2, respectively) and ADFI (P = 0.10; 0.782,0.818, and 0.820 kg/d for VD-2, 25D-1, and 25D-2, respectively) in both 25OHD3 treatments than the VD-2 treatment in d 14-28 postweaning. In the overall period, the ADG tended to be greater in the 25D-2 treatment than the VD-2 treatment (P = 0.10; 0.353, 0.367, and 0.373 kg/d for VD-2, 25D-1, and 25D-2, respectively), and the G:F was numerically greater in both 25OHD3 treatments compared with the VD-2 treatment (0.646, 0.660, and 0.670 for VD-2, 25D-1, and 25D-2, respectively). In conclusion, supplementing 25-OHD3 to the nursery pig diets could enhance feed intake and growth rate in the late nursery period compared with vitamin D3 supplementation.

215 The effect of a Lactobacillus fermentation postbiotic on nursery pig growth performance after experimental inoculation with F18 Escherichia coli.

Abstract This study evaluated a Lactobacillus fermentation postbiotic (LFP) in nursery pigs challenged with F18 ETEC. A total of 119 three-week-old barrows and gilts were used in this study. Pigs were acclimated for a period of 7 d upon arrival at the facility before inoculation. Pigs were stocked in mixed-sex pens of 6 pigs in each pen. Four rooms were used and each room had 5 pens. One room of pigs was not challenged with F18 ETEC (NCH). Ninety pigs in the other 3 rooms were intraorally challenged for three consecutive days with F18 ETEC isolate at a concentration of ~1x109 cfu/ml (CH) Pigs in the non-challenge groups were housed in separate airspaces than those receiving ETEC inoculum to avoid contamination. All pigs, regardless of health challenge, were fed a standard two-phase dietary nursery program. Five dietary treatments were evaluated: T1) negative dietary control without feed additives (Carabox, zinc oxide, and added copper), T2) 750 ppm LFP, T3) 1,500 ppm LFP, T4) 2,250 ppm LFP, and T5) positive control (PC) with feed additives. Feces were collected at 0 and 4 d post inoculation (dpi) to evaluate fecal shedding by real time polymerase chain reaction (rtPCR). Pig body weights were collected at -7, 0, 7, 14, 21, and 42 dpi to calculate performance. Feed intake was measured at the completion of the two dietary phases at 7 and 42 dpi for calculation of average daily feed intake (ADFI) and gain to feed ratio (G:F). All pigs were negative for F18 ETEC on 0 dpi and the non-challenge pigs remained negative by 4 dpi. At 4 dpi, the pigs fed 1,500 and 2,500 ppm LFP had significantly less Cts than pigs fed the positive control (rtPCR < 0.819, P = 0.03). Pigs fed the negative control had significantly greater fecal bacterial load than those fed the positive control averaged across challenge treatments and dpi (Ct ratio = 0.84, P = 0.03). Total E. coli and overall bacterial load were increased at 0 dpi compared with 4 dpi (Ct ratio= 0.90, P < 0.02). Pigs fed the positive control grew significantly faster than those fed the other diets during the acclimation phase (P < 0.01). Pigs in T5 were heavier than those on T1 at 14 and 21 dpi P < 0.02; table 1). End weights, average daily gain (ADG), and ADFI were similar between T1 and T2-4 across dietary phases (P = 0.13) with a tendency for the pigs feed 1,500 ppm to be heavier at d 21 (linear effect, P = 0.15) Pigs fed the positive control were heavier and grew faster at the end of each phase compared with pigs fed the other diets. The F18 challenge was effective in decreasing pig performance. Preliminary evidence suggests lactobacillus fermentation postbiotic may improve nursery performance in the face of an F18 challenge, but further investigation is necessary.

281 Effects of dietary Aspergillus oryzae postbiotic during gestation and lactation on sow and progeny performance

Abstract This study aimed to evaluate effects of Aspergillus oryzae postbiotic (AOP) supplementation in gestation and lactation diets on sow performance, litter performance, and offspring performance through the nursery period. Sows [n = 118; Landrace × Yorkshire; body weight (BW) = 238 ± 2.2 kg; parit y= 3.8 ± 0.32] were blocked by parity and assigned randomly to one of two treatments. Treatments were a control diet and a control diet supplemented with AOP (Biozyme Inc.) at 1.5 g/sow/d in gestation from 5 days before breeding until farrowing, and adjusted to 1.55 g•sow-1•d-1 during lactation. Sow BW and P2 backfat thickness were measured on d 0, 30, and 109 of gestation and 24 h postpartum and at weaning on d 20 ± 2. Litters were standardized to 13 piglets within 24 h of farrowing. Piglets were weighed individually at birth, after 24 h, and at weaning. At weaning, 369 pigs were allotted to pens within maternal dietary treatment (48 pens, with 7 or 8 pigs/pen) for a 42-d nursery trial. All pigs received a common nursery diet in 3 dietary phases. Sows fed AOP had a lighter (P < 0.01) BW than those in the control group on d 109 of gestation (234.1 vs 244.1 kg) and post-farrowing (227.4 vs 236.7 kg), respectively, but not at other time points. Moreover, sows fed AOP showed less (P < 0.01) BW loss from d 109 of gestation to weaning (-0.9 vs -7.8 kg) and from post-farrowing to weaning (4.1 vs -1.9 kg) compared with control sows. Total feed intake and average daily feed intake (Control: 6.0 vs AOP: 6.2 kg/d) during lactation were not impacted (P > 0.10) by dietary treatments. Supplementation of AOP did not influence (P > 0.10) litter size (14.8 vs 16.0), litter birth weight (17.4 vs 18.2 kg), percentage of low birth weight piglets (13 vs 12.5 %) or normal birth weight piglets (87.0 vs 87.5 %), stillbirths (1.2 vs 1.2/litter), or mummies (0.9 vs 0.5/litter) for Control and AOP sows, respectively. Across treatments, no differences (P > 0.10) were observed for litter weight gain (43.2 vs 40.4 kg), average piglet BW at weaning (5.1 vs 4.9 kg), or piglet mortality rate (12.4 vs 13.1 %) for Control and AOP sows, respectively. Piglets weaned from AOP sows tended (P = 0.07) to have an increased average daily feed intake (ADFI) during the first week after weaning compared with pigs weaned from Control sows (0.28 vs 0.26 kg), but AOP did not influence other performance parameters for the entire nursery period. There were no interactions between maternal dietary treatment and nursery phase (P > 0.10), suggesting consistent responses to maternal dietary treatments over time. In summary, feeding sows AOP reduced sow BW loss but had no impact on litter or nursery performance.

258 Nutritional strategies allowing inorganic phosphates reduction in maintaining maximum growth performance and bone mineralization in piglets

Abstract Phosphorus (P) is an essential component for optimal maintenance of growth and bone mineralization but its inclusion in animal feed is a core concern for economic and environmental concerns in ensuring sustainability of this resource. This study aimed to test impacts of different nutritional strategies such as dietary calcium (Ca) reduction and phytase superdosing for piglets fed without inorganic phosphate. A total of 147 piglets Piétrain*(Large White*Landrace) were divided among 5 experimental diets. Three levels of digestible P were tested (0.21%, 0.27%, 0.33%) by adding monocalcium phosphate (MCP) from 1) a negative control diet (NC) without MCP, 2) a diet with 0.3 % MCP (NC+0.3 % MCP), or 3) a diet with 0.6 % MCP (NC+0.6 % MCP). Those three diets contained 250 FTU/kg of phytase and a minimum amount of phytate set at 0.27%. All dietary treatments were formulated following a constant Ca:digestible P ratio at 2.1. The other two diets were formulated with two phytase’ doses added on top of the NC diet 4) 2,000 FTU/kg (NC+2000 phy) or 5) 3,000 FTU/kg (NC+3000 phy). Piglets were weighed individually at 42, 55 and 69 d of age, and feed intake per phase was recorded per pen. Average daily gain (ADG), daily feed intake (ADFI) and feed conversion ratio (FCR) were calculated. At the end of the experiment, right metacarpal was removed from 12 animals per treatment to analyze bone mineralization. Data were submitted to an ANOVA including effects of dietary treatments and body weight at start of the trial using JMP 16.2.0. Differences among means were separated by a Student’s test and significance accepted at P < 0.05. Liveability % was not different between treatments. The reduction of Ca and digestible P in NC did not affect growth performance (P > 0.05) but reduced bone ash % compared with PC (P < 0.05, 30.4 % vs 34.6 %, respectively). Phytase supplementation at 2,000 and 3,000 FTU/kg improved body weight gain (28.8 kg for animals fed NC vs 30.0 kg for NC+2000 phy vs 30.2k g for NC+3000 phy, P < 0.05), feed efficiency (1.60 vs 1.50 for NC and NC + 3000 phy, respectively; P < 0.05) and bone mineralization (P < 0.05). This experiment confirms the benefit of reducing the Ca and concomitantly P levels in piglet feed without impairing growth performance by optimal use of phytase that also provides the ability to overcome dependence on inorganic phosphates.

54 Effects of a new biosynthetic 6-phytase supplementation on nutrient digestibility, phytate disappearance and growth efficiency in weaning piglets fed low in calcium and digestible phosphorus diets

Abstract The objective of this study was to investigate the influence of adding graded levels of a new biosynthetic bacterial 6-phytase on nutrient digestibility, phytate disappearance and growth performance in weaned piglets. A total of 192 male weaned piglets with initial body weight of 8.70 ± kg, distributed in a randomized block design with four treatments and 24 replicate pens with 2 animals each for 42 d. The experimental diets included a phosphorus and Ca deficient diet (STTD of P/Ca = 0.21%/0.58% and 0.19%/0.54%, respectively, in post-weaning 1 and 2 diets) containing 0 (a control diet), 500, 1,000 or 1,500 FTU/kg diet. The diets were fed into 2 phases: post-weaning 1 and 2 from 1 to 14 and 15 to 42 d, respectively. Body weight and feed intake were measured at the end of each phase, and average daily gain (ADG), average daily feed intake (ADFI) and feed conversion ratio (FCR) were calculated for the overall experimental period. On d 42, ileal digesta samples were collected from 1 piglet/pen (n = 12 samples/treatment) for apparent ileal digestibility (AID) of Ca, P, and amino acids and phytate disappearance determination. Supplementation of diet with phytase from 0 to 1500 FTU/kg diet linearly improved (P < 0.01) AID of Ca. Both linear and quadratic effects (P < 0.001) was observed for AID of P and phytate-P. Increasing level of phytase supplementation resulted in linear and quadratic increases of Arg, His, Ile, Leu, Lys, Phe, Thr, Trp, Val, Ala, Asp, Cys, Glu, Ser, Tyr and total amino acids. Phytase supplementation increased (P < 0.0001) linearly Met and Pro, with an AID of Met showing a tendency (P = 0.09) for a quadratic increase. In addition, increasing phytase dose linearly increased (P = 0.006) the overall ADFI and ADG and decreased (P < 0.001) F:G ratio. Also, a tendency (P = 0.07) for quadratic effect of phytase was also observed on F:G ratio. These findings highlight that the supplementation of diets with the new bacterial 6-phytase significantly enhanced the utilization of nutrients, disappearance of phytate and performances of weaned piglets in a dose dependent manner.

PSIII-14 Effect of a combined supplementation of Bacillus spp. and lactic acid bacteria probiotics on growth performance and fecal score in nursery pigs

Abstract This experiment was conducted to evaluate the effect of a combined supplementation of Bacillus spp. and lactic acid bacteria probiotics on growth performance and fecal score in nursery pigs. Bacillus spp. probiotics have been shown to improve the proliferation of lactic acid bacteria in the gut of piglets. A total of 45 newly weaned piglets (initial body weight = 8.37 ± 1.38 kg; weaning age = 27.2 ± 1.05 d) were allotted to 3 treatments in 3 replicates with 5 pigs per pen based on body weight, gender, and breed for a 28-d feeding trial. Treatments were: 1) Control: no probiotic supplementation, 2) PB: Bacillus spp. probiotic supplementation, and 3) PBL: Bacillus spp. and lactic acid bacteria probiotic supplementation. The Bacillus spp. probiotic consisted of Bacillus subtilis and Bacillus licheniformis and was supplemented to the PB and PBL diets at the recommended level (3.2 × 109 CFU/kg diet). The lactic acid bacteria probiotic consisted of Lactobacillus acidophilus, plantarum, casei, and Enterococcus faecium strains and was supplemented to the diets at the recommended level (4 and 2 × 107 CFU/kg diet for Phase 1 and 2, respectively). Corn-soybean meal-based diets were used for d 0-15 (Phase 1) and d 15-28 (Phase 2) postweaning. Growth performance and fecal score (1 = normal, 4 = severe diarrhea) were measured in each phase. In the Phase 1 (d 0-15 postweaning), average daily gain tended to be greater in the PBL treatment compared with the Control treatment (P = 0.13; 0.268 and 0.210 kg/d, respectively), and average daily feed intake tended to be greater in the PBL treatment compared with the Control and PB treatments (P = 0.12; 0.385, 0.375, and 0.424 kg/d for the Control, PB, and PBL treatments, respectively). In the overall period (d 0-28 postweaning), average daily feed intake tended to be greater in the PBL treatment compared with the PB treatment (P = 0.07; 0.651 and 0.596 kg/d, respectively), and gain to feed ratio in the PB treatment tended to be greater compared with the Control and PBL treatments (P = 0.10; 0.618, 0.649, and 0.620 kg/d for the Control, PB, and PBL treatments, respectively). Fecal score was significantly improved in both PB and PBL treatments compared with the Control treatment from d 7 postweaning (P = 0.08) to the end of experiment (P < 0.05; 1.75, 1.41, and 1.42 for the Control, PB, and PBL treatments, respectively). In conclusion, both lactic acid bacteria and Bacillus spp. probiotic supplementation to nursery diets may have potential to improve growth rate and feed intake in early nursery period and probiotic supplementation could improve fecal consistency of weaning pigs in the nursery period.

PSVI-15 Assessing the implications of a silymarin-enriched diet on the performance and blood absorption rate of broiler and laying hen

Abstract This experiment was executed to assess the impacts of silymarin on different aspects of broiler and laying hen, including growth, digestibility, excreta score, footpad lesion score, tibia ash, meat quality, and blood absorption rate. In Experiment 1: 1-d-old Ross 308 broilers (mixed sex; n = 576) were arbitrarily assigned with an average body weight of 42 ± 0.3 g for a 32-d trial. The broilers were sorted into eight repetition pens with 18 birds per pen and four research treatments (basal diet as the control and basal diet included 0.02, 0.04, and 0.06% micelle silymarin). Experiment 2: 61-wk-old Hy-line brown laying hens (n = 16) were divided into 2 treatment groups (TRT1, basal diet + powdered silymarin 4%; TRT2, basal diet + micelle silymarin 4%), with 8 numbers per repetition. Feeding broilers with a graded dose of micelle silymarin (MS) increased body weight gain linearly during d 1–9, 9–21, 21–32, and overall (P = 0.021, 0.011, 0.019, and 0.002, respectively). Furthermore, there was a linear increase in feed intake (P = 0.017) during d 1–9, and the enhancement of dry matter utilization (linear, P = 0.011) was exhibited as the amount of MS inclusion in the diet increased. Tibia ash content enhanced linearly (P = 0.038), and meat quality traits also revealed a linear improvement in breast muscle color (yellowness) (P = 0.045) and linear decrease (P = 0.004) in pH level with the increasing levels of MS in the broiler diet. Nonetheless, both the excreta score and the footpad lesion score showed no significant alteration (P > 0.05). Moreover, a greater absorption rate of silymarin was observed in the blood of laying hens 2 h (P < 0.0001) and 4 h (P < 0.0001) after feeding with micelle-type silymarin as compared with powdered-type silymarin. Briefly, MS can be a favorable supplement for poultry production as it can increase the growth, digestibility, toe ash, and meat quality of broilers and the blood absorption rate of laying hens.

127 Utilizing predictive models for bone mineral content and bone mineral density as a tool to assess dietary phosphorous

Abstract Dietary phosphorous is a necessary nutrient for bone development in pigs at all stages of its growing. Deficiencies in phosphorous decrease bone mineral content (BMC) and bone mineral density (BMD) and may be a causative of lameness. However, the normal range expected in whole body (WB) and individual bones for BMC and BMD in commercial pigs has been poorly defined. Therefore, our objectives were to 1) model normal WB bone density at multiple timepoints in wean to finish pigs, and 2) determine the extent to which individual bone (femur and 3rd metatarsal) BMC and BMD could predict WB BMC and BMD. Mixed sex pigs [Camborough (1050) x 337, PIC] were utilized and included freshly weaned ~21 d (n = 8), ~44 d of age (n = 24), ~84 d of age (n = 24) and ~154 d of age (n = 24). Pigs were individually penned. Excluding weaning age, at each age group pigs were randomly assigned to diets adequate, marginally deficient, or deficient in available phosphorus (avP) and fed for 3, 4, and 6 wk (age group 44, 84, 154, respectively). Within each age group, diets were formulated to meet nutrient and energy requirements except for avP and pigs fed ad libitum. On-test and off-test body weight (BW) and feed intake and gain to feed ratio were assessed for each age group. At the end of each feeding period, all pigs were euthanized and WB, femur (F) and 3rd metatarsal (M) BMC and BMD determined by dual X-ray absorptiometry (DXA). Data were analyzed using linear and generalized additive models that predicted response variables (BMC or BMD) as a function of BW or age. Only pigs fed adequate avP diets were used in the model fit. Pigs fed adequate avP diets increased BMD with age (0.22, 0.42, 0.84 and 1.10 g/cm2, days of age 21, 44, 84 and 154 respectively, P < 0.001). Within day of age 84, marginally and deficient avP diets reduced BMC and BMD by 21 to 41% (P = 0.002) and 12 to 25% (P = 0.006), respectively. Within day of age 154, marginally and deficient avP diets reduced BMC and BMD by 9% (P = 0.05) and 6 to 8% (P = 0.06), respectively. Body weight record and individual bone (F and M) BMC and BMD from pigs fed deficient avP diets were used to predict WB BMC and BMD and the mean square error of prediction was selected as a criterion to evaluate the ability of the models to detect these inadequately fed pigs. Using the selected models, pigs fed nutritionally deficient diets were detected due to 2- to 7-fold increase in MSE of predicted WBMD or WBMC compared with pigs fed adequate diets. These models can be used to assess bone development and strength in growing pigs and to infer the adequacy of avP level supplied in their diets.

126 A nutritional solution based on calcidiol (25-OH-D3, HyD) and triterpenoid affects muscle protein synthesis pathways in grower-finisher pigs

Abstract To boost profitability in pig production, it is important to achieve increased lean growth rates and maximize efficiency, especially in grower-finisher pigs where feed intakes are high. Molecular research, especially the study of gene expression, is a proven tool for understanding the precise mechanisms behind muscle tissue growth, including a recent focus on pathways such as the mammalian target of rapamycin (mTOR). In the current work, gene expression analyses were used to study the mode of action of the combination of calcidiol (25-OH-D3, HyD) and triterpenoid, which has shown significant growth and efficiency improvements in grower-finisher pigs (McCormack et al., 2024). Three experimental diets were evaluated for 7 wk; Positive control: 0.7% total Ca, 0.36% total P, vit D3 at 1500IU/kg feed (PC), negative control: PC diet + 30% reduced Ca and 10% reduced P (NC), and NC diet with 1,500IU D3 in calcidiol form (25-OH-D3, HyD) and triterpenoid (NC+). At 19 wk of age, 16 animals per treatment were sacrificed and tissue samples were taken from the longissimus muscle and preserved in RNA later solution. The RNA was extracted, quality control checked, and mRNA sequenced using the Illumina platform with 150 base pair paired-end sequencing and 30M read depth. The sequenced data were aligned to the Sus scrofa reference genome (Sscrofa11.1) using Kallisto. Data were normalized and analyzed for differentially expressed genes (DEGs) between treatments using DeSeq2. Genes were assigned to biological pathways using Biofractal’s customisation of the Reactome pathway database. For statistical analysis, RNA integrity number and treatment were included in the model. In the PC compared with the NC, there were 71 DEGs using a false discovery rate (FDR) of < 0.10. Altered pathways included the inhibition of cellular stress pathways and increased cell turnover in the muscle of PC compared with NC pigs. In the NC+ compared with the NC, there were 155 DEGs (FDR < 0.10). The most significantly upregulated gene in the NC+ treatment was adenylate cyclase (FDR < 0.001), an upstream regulator of several pathways related to energy metabolism and muscle protein synthesis. This mechanism was confirmed in the pathway analysis, which found that the NC+ treatment activated PKA-mediated phosphorylation of CREB, a pathway that inhibits muscle atrophy. Furthermore, the NC+ treatment activated several pathways related to muscle growth, including the mammalian target of rapamycin complex 1 (mTORC1). In this study the addition of calcidiol (25-OH-D3, HyD) and triterpenoid to the diet was found to specifically affect molecular pathways in the muscle of grower-finisher pigs involved in both the inhibition of muscle breakdown as well as activating muscle growth.

137 Impact of dietary soybean-mediated trypsin inhibitor concentrations on nursery pig performance

Abstract Antinutritional factors associated with soybeans and soy products, such as trypsin inhibitor proteins, have been shown to hinder amino acid bioavailability and, consequently, affect the growth performance of pigs. Thus, our objective was to assess the impact of dietary trypsin inhibitor units (TIU; expressed as TIU/mg of feed) on nursery pig performance and health. Sixty barrows [5.56 ± 0.65 kg body weight (BW), Camborough (1050) x 337, (PIC, Hendersonville, TN)], freshly weaned and 19 to 21 d of age were randomly selected and allotted across six dietary treatments (10 pigs/treatment) in a randomized complete block design. All pigs were individually penned with ad libitum access to water and feed. Diets were administered in two phases directly post-weaning, spanning 14 and 28 d, respectively, and the entire test period extended for 42 d. Within each phase, diets were formulated to be isocaloric, with uniform NDF and SID lysine concentrations. In both phases, TIU were incrementally adjusted by the inclusion of soybean meal, raw ground soybeans, soybean oil, and soyhulls to attain a target TIU/mg feed of 0.5, 1, 2, 3, 4, and 6. All diets were analyzed for active TIU/mg. Pig BW and feed disappearance were measured at the start and end of each phase to compute average daily gain (ADG), average daily feed intake (ADFI), and gain to feed ratio (G:F). Fecal consistency was assessed daily in phase 1. Pig was the experimental unit and data were analyzed with the effect of diet, including the linear and quadratic contrasts, evaluating dietary TIU levels. The average analyzed TIU/mg over both diet phases were 0.38, 0.54, 1.85, 3.16, 3.90, and 5.79 TIU/mg diet, respectively. Fecal consistency scores did not differ across diets. At the end of phase 1, BW decreased from 8.7 to 6.9 kg as TIU/mg diet increased from 0.38 to 5.79 (linear P < 0.05). Similarly, by d 42, BW decreased from 25.3 to 15.5 kg with the increase in dietary TIU/mg from 0.38 to 5.79 (linear P < 0.0001). Both phase 1 and 2 showed a decrease in average daily gain (ADG) and G:F as TIU increased (linear P < 0.05). ADFI exhibited a decreasing trend in phase 1 (linear P = 0.079) and a decrease in phase 2 (linear P < 0.05) as dietary TIU increased. No quadratic responses were reported for ADG and G:F. Overall, as TIU increased, ADG, ADFI, and G:F were reduced, with 5.79 TIU/mg feed resulting in a decrease of these parameters by 8 to 22% (linear P < 0.01). In conclusion, increasing TIU levels in the diet had detrimental effects on nursery pig performance. The most significant negative impacts on growth, feed intake, and feed efficiency were observed in diets containing 3.16 to 5.79 TIU/mg feed.

PSV-9 Effects of increasing amounts of high-oleic or conventional soybeans in diets fed to mid-lactation dairy cows on measures of dry matter intake and lactation

Abstract The objective of the study was to determine effects of increasing amounts of conventional (CONV) or high-oleic (HO) soybean in diets fed to mid-lactation dairy cows on dry matter intake (DMI) and performance. Rumen and duodenally cannulated cows (n = 8) were split into two groups and placed in a split-plot design. The whole plot factor was type of soybean (CONV vs. HO) and was provided to cows in a crossover arrangement so that each cow was provided both types of soybeans throughout the experiment. The subplot factor was amount of soybeans (0, 4, 8, 12%). Each group of cows receiving the same type of soybean were placed in a 4 x 4 Latin square with treatment sequences balanced for carryover effects. Diets were formulated to contain 18.5% crude protein and to slightly exceed requirements for ruminally degradable protein. Additions of soybeans replaced soybean meal and soybean hulls so that diets provided similar amounts of soy-based protein and fiber. During the last 4 d of each 14-d period, spot samples of feed, orts, and milk were collected together with measures of milk production and feed intake. Data were analyzed using the MIXED procedure of SAS. There were no interactions of soybean type and amount on lactation or DMI except for measures of milkfat, milk energy concentration and milkfat yield. Increasing amounts of HO resulted in a quadratic response in milkfat and energy concentration together with measures of milkfat yield. Specifically, these measures were greater (P ≤ 0.02) when cows were fed diets containing 4 and 8% HO compared with diets containing 0 or 12% HO; increasing amounts of CONV had no impact (P ≥ 0.32) on milkfat and energy concentration or milkfat yield. Measures of milk yield were not affected by type or amount of soybean (P ≥ 0.54), but measures of energy corrected milk yield (ECM) tended to respond differently to increasing amounts of soybean from either CONV or HO (P = 0.07). Interestingly, ECM responded quadratically (P = 0.02) to increasing amounts of HO but not to increasing amounts of CONV (P ≥ 0.58). Overall, however, ECM tended (P = 0.06) to be slightly greater with HO compared with CONV (42.5 vs. 41.1 kg/d). Yet, DMI was also greater (P ≤ 0.01) with HO compared with CONV (26.6 vs. 24.4 kg/d). Differences in DMI, therefore, resulted in a tendency (P = 0.07) for greater efficiency of ECM production when cows were fed CONV vs. HO. Overall, treatments had no effect on measures of milk protein, urea-nitrogen, solids-not-fat or lactose concentrations or yields. These data seem to indicate that performance responses among lactating cows to increasing amounts of HO are dynamic but that responses to CONV are not.

91 The effect of increasing oat groat levels on nursery pig performance, digesta pH, and fecal consistency and physicochemical properties in young pig diets

Abstract Post-weaning growth delay in pigs is a well-documented challenge associated with the stressors inherent in the weaning process. Oat-based dietary interventions have shown potential in improving fecal consistency, increasing feed intake, and improving feed efficiency. However, the direct effect of oat groats on the fecal physicochemical properties and dry matter (DM) is largely unknown. The experimental objective was to evaluate increasing inclusions of oat groats in young pig diets on pig performance, digesta pH, and fecal consistency and physicochemical properties. Newly weaned pigs (n = 128) with an initial body weight (BW) of 5.4 ± 0.27 kg were randomly assigned to one of four treatments (n = 8 split sex pens) for a 35-d study. Dietary treatments consisted of 0%, 5%, 10% or 15% inclusion of oat groats at the expense of corn. Treatments were applied across 2 dietary phases and a common diet fed during phase 3: d 0-7 (phase 1), d 7-21 (phase 2), d 21-35 (phase 3). On d 7, 14, 21, 28, and 35, pigs and feeders were weighed, pen fecal samples were collected, and fecal scores were evaluated using a 4-point scale (1 = solid, 2 = semi-solid, 3 = semi-liquid, 4 = liquid). Fresh fecal samples were analyzed for water binding capacity (WBC), and fecal DM. On d 14, one pig per pen closest to the mean BW was necropsied, and ileal, cecal, and colonic digesta pH were measured. Continuous data were analyzed as a linear mixed model (PROC MIXED) with treatment and period as fixed effects, and initial BW as a covariate where appropriate. Orthogonal polynomial contrasts were used to determine the linear and quadratic effects of increased inclusion. Fecal scores were analyzed using odd logistic regression. There was a linear increase in average daily gain (ADG) and average daily feed intake (ADFI) as oat groat inclusion increased from d 0-7 and d 7-14 (Linear P < 0.05). However, from d 14 to 21, and d 21 to 35 there was no longer an impact of oat inclusion on ADG (P > 0.782) or ADFI (P > 0.405). Feed efficiency did not differ among treatments (P > 0.71). Oat groat inclusion had no effect on fecal scores throughout the study (P = 0.743). However, fecal DM% increased as oat groat inclusion did on d 7 and 14 (Linear P < 0.01), and fecal WBC tended to be increased in 5% and 10% oat groat diets (Diet; P = 0.063). Ileal and colonic pH did not differ among treatments, but cecal pH tended to be less in pigs fed 10 and 15% oat groats (P = 0.089). In conclusion, increasing oat groats in nursery diets increased ADFI, ADG, and altered fecal DM, but did not impact feed efficiency.

236 The effects of replacing dried distiller’s grains with solubles with heat-treated soybean meal on nutrient intake and digestibility in forage-based diets

Abstract Cattle growth is calculated through dry matter intake, average daily gain and gain:feed measures that assume performance and digestibility are correlated. Hence, evaluating nutrient digestibility and flow provides additional explanations for subsequent growth performance. Therefore, five fistulated Jersey steers [Initial body weight (BW) = 288 ± 22 kg) fitted with ruminal, duodenal, and ileal cannulas were utilized in a 4 × 5 row-column design to determine intake and total tract nutrient digestibility when replacing dried distiller’s grains plus solubles (DDGS) with heat-treated soybean meal (TSBM) in forage-based growing diets. The 56-d study contained 4 periods, each period lasting 14 d [9 d of adaptation and 5 d of collection (d 0 to 4)]. Dietary treatments partially replaced DDGS, included at 16% diet dry matter (DM), with TSBM at increasing inclusion levels of 0 (TSBM0), 4 (TSBM4), 8 (TSBM8), and 12% (TSBM12) DM. Basal diets contained 43.5% corn silage, 36.5% oat hay, and 4% meal supplement (DM). Chromic oxide was incorporated into the diet daily at 0.25% DM as a digesta marker. Steers were housed in individual tie stalls during the 5-d collection period. Treatment diets were fed daily at 0800 h with orts being weighed at 0730 h and subsampled on d 0 to d 4 each period. Fecal collection bags were harnessed to each steer from d 0 to d 4 to collect fecal weight and subsampled twice daily (0700 and 1900 h). Digestibility and feed intake were analyzed utilizing the MIXED procedure of SAS with treatment and period as fixed effects and animal as a random effect. There were no differences (P ≥ 0.14) in DM, organic matter (OM), neutral detergent fiber (NDF), starch and nitrogen (N) intakes among treatments. Fecal DM, OM, NDF, starch, and N output resulted in no treatment effects (P ≥ 0.24). Subsequently, total tract apparent digestibility differences (P ≥ 0.32) were not detected for DM, OM, NDF, and starch content. However, N total tract apparent digestibility was significantly different (P < 0.03) with TSBM0 resulting in less N digestibility than TSBM12 (65.54% and 71.59%, respectively). Replacing a portion of DDGS with TSBM does not result in deleterious digestive effects in forage-based growing diets. As a result, the utilization of DDGS or TSBM as the primary protein source will depend on growth performance, feedstuff availability and economics.

PSV-6 The additive effect of hormonal implant and inclusion of beta-agonists in carcass quality in beef cattle

Abstract The objective of this study was to determine what additive effect hormonal implants and inclusion of beta-agonists in the diet have on carcass quality in yearling beef steers. Twenty-one Hereford-cross steers (450 ± 15 kg) were assigned to one of three drylot pens based on initial body weight (BW) and sire so that each pen had an equal starting BW and sires were equally represented in each pen. Each drylot pen was assigned to one of three treatments: receiving a hormonal implant (IMP), consuming a beta-agonist (BAG), or receiving both of the previous treatments (AND). All steers were fed a mixed ration consisting of 30.0% rye silage, 28.0% DDGS, 30.0% rolled corn, 10.5% soybean meal, and 1.5% mineral supplement (22.0% CP, 2.90 Mcal ME/kg DM). Animals were fed daily at 0700 and 1700 and weighed weekly at 0630. For the duration of the trial, animals were housed in drylot pens with ad libitum access to feed and water and had shade structures in each pen. Following a 15-d adaptation period, feed intake was recorded for 45 d. Weight gain for each treatment group were 1.26, 1.28, and 1.48 kg/d for IMP, BAG, and AND, respectively. After the intake portion of the study was completed, an animal from each pen was slaughtered and evaluated for carcass quality. Hot carcass weights for diets IMP, BAG, and AND were 347.4, 352.9, and 394.8 kg, respectively. Following 14 d aging, samples from the ribeye area were collected from each animal and subjected to sensory analysis and other assessments of quality. Data were analyzed as a completely random design in SAS v9.4. There was not a significant difference between the IMP treatment and the AND treatment based on assessment from Warner-Bratzler shear force, carcass yield, marbling score, and sensory assessment (P < 0.05); however, the BAG treatment had significantly less marbling than the other two treatments. It was concluded that the additive effect of using both a hormonal implant and a beta-agonist can produce carcass of good quality without detrimental effects on meat quality when compared with a beta-agonist only inclusion.