Can net energy values be determined from animal performance measurements? A review of factors affecting application of the California Net Energy System1

Abstract The California Net Energy System (CNES) can reliably project performance of feedlot cattle based on three factors: expected dry matter intake (DMI), some index of degree of maturity of cattle linked to body composition (fat and protein content), and an estimate of the net energy (NE) content of the diet. The CNES allowed feedlot managers to monitor growth and efficiency of individual pens of cattle. Through assigning distinct values for net energy for maintenance (NEm) vs. net energy for gain (NEg) of the metabolizable energy (ME) present in feeds, the CNES enables valid economic comparisons among feedstuffs, an appraisal not feasible based on total digestible nutrients or digestible energy (DE) values. Because NEm and NEg are linked mathematically to ME, the CNES also allows performance-adjusted ME (paME) value of diets to be calculated from observed DMI and growth or carcass measurements. Compared with other productivity measures (e.g., average daily gain and gain-to-feed ratio) that are confounded with and affected by DMI, the CNES logically separates production responses by cattle into two factors—DMI and ME of the diet. This enables research scientists or cattle producers to appraise responses within these two factors independently. In feeding studies, means of paME values were related closely to ME values of diets calculated from the ME of diet ingredients. But unlike ME values projected from diet analyses, paME estimates are affected by environmental conditions (e.g., season, weather, animal interactions, stress, nutritional history and deficiencies, associative effects of feeds, imprecise feed management, and animal healthfulness and disorders). These factors typically overestimate ME intake or increase energy requirements, both of which decrease energetic efficiency. By comparing paME with ME values calculated from diet composition, logical reasons behind performance responses to and quantitative benefits from feed additives, grain processing, hormone implants, and animal management can be appraised. Considering the evolution in cattle types, management and marketing conditions, and changes in diet ingredients and processing that have occurred during the past 50 yr, updating by a skilled committee to correct certain anomalies within the CNES as currently being applied seems appropriate. Developing simplified spreadsheets could help users evaluate their own dietary and management conditions and assure that the CNES continues to be widely applied by the feedlot industry within the United States and worldwide.

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The Effects of Single or Combined Supplementation of Probiotics and Prebiotics on Growth Performance, Dietary Energetics, Carcass Traits, and Visceral Mass in Lambs Finished under Subtropical Climate Conditions

Biology ◽

10.3390/biology10111137 ◽

2021 ◽

Vol 10 (11) ◽

pp. 1137

Author(s):

Alfredo Estrada-Angulo ◽

Octavio Zapata-Ramírez ◽

Beatriz I. Castro-Pérez ◽

Jesús D. Urías-Estrada ◽

Soila Gaxiola-Camacho ◽

...

Keyword(s):

Growth Performance ◽

Average Daily Gain ◽

Live Weight ◽

Climatic Conditions ◽

Feed Ratio ◽

Energetic Efficiency ◽

Net Energy ◽

Subtropical Climate ◽

Visceral Mass ◽

Climate Conditions

The aim of this trial was to test the effects of the use of eubiotics (pro- and prebiotics) alone or in combination in the diet of lambs finished under subtropical climate conditions. For this purpose, 40 Pelibuey × Katahdin lambs (29.5 ± 4.8 kg initial live weight) were used in a 93 day growth-performance experiment. Dietary treatments consisted of a cracked corn-based finishing diet supplemented with (1) no eubiotics (control), (2) 3 g of probiotics (live Saccharomyces cerevisiae, SC), (3) 3 g of prebiotics (mannan oligosaccharide plus b-glucans, MOS), and (4) a combination of 1.5 g of SC and 1.5 g of MOS (SC+MOS). Throughout the study, the average temperature humidity index (THI) was 78.60. Compared to controls, supplementation with SC or MOS, alone did not affect average daily gain (ADG), but enhanced feed efficiency by 5.6% and 6.9% (gain-to-feed ratio, G:F) and dietary net energy by 4.6% and 5.9%, respectively. Compared to controls, SC+MOS enhanced ADG (10%), G:F (9.5%), and dietary net energy (7.2%). Lambs fed SC+MOS had also greater ADG, G:F, and dietary net energy compared to lambs fed SC alone. When compared to MOS, the combination enhanced ADG (10.4%, p = 0.04). This effect could be attributed to the increased dry matter intake (7.6%, p = 0.06), as neither G:F nor dietary energy was significantly affected. Compared with controls and SC, supplementation with MOS alone and SC+MOS increased kidney–pelvic–heart fat, while SC supplementation tended (p = 0.08) to reduce 4.1% the relative intestinal mass (as a proportion of empty body weight) when compared to controls. Treatment effects on the other carcass measures were not significant. In the present study, supplemental probiotics and/or prebiotics improved dietary energetic efficiency in lambs finished under subtropical climatic conditions. The combination of probiotics with prebiotics reinforced this positive effect.

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Supplementation with calcium salts of cottonseed oil improves performance of Bos indicus animals consuming finishing diets1

Translational Animal Science ◽

10.1093/tas/txaa080 ◽

2020 ◽

Vol 4 (2) ◽

pp. 967-973

Author(s):

Marcos A A Carvalho ◽

Bruno I Cappellozza ◽

Bruna Silva ◽

Thais S Castro ◽

Marcos Renato Burim ◽

...

Keyword(s):

Beef Cattle ◽

Average Daily Gain ◽

Bos Indicus ◽

Experimental Period ◽

Cottonseed Oil ◽

Feedlot Cattle ◽

Metabolizable Energy ◽

Neutral Detergent Fiber ◽

Net Energy ◽

Calcium Salts

Abstract Lipid ingredients are often used into feedlot cattle diets, primarily to increase energy density and improve efficiency parameters of the herd. Therefore, this study was designed to evaluate the effects of including calcium salts of fatty acids (CSFA) and increasing levels of cottonseed byproducts into feedlot diets. On day 0 of the study, 96 Bos indicus bullocks were individually weighed twice and initial body weight (BW) was considered the average of both measurements (initial BW = 287 ± 22.4 kg). Bulls were ranked by initial BW, allocated into 1 of 12 feedlot pens (eight bulls per pen), and pens randomly assigned to one of three treatments: 1) inclusion of 15.0% [dry matter (DM) basis] of cottonseed byproducts into the finishing diet (CTS-15; n = 4), 2) inclusion of 22.0% (DM basis) of cottonseed byproducts into the finishing diet (CTS-22; n = 4), and 3) inclusion of 2.7% (DM basis) of CSFA of cottonseed oil into the finishing diet (CSFA; n = 4). The experimental period lasted 135 d and consisted of 5 d of preadaptation, 15 d of adaptation (ADP), 31 d of growing (GRO), and 84 d of finishing (FIN). Performance and carcass characteristics data were evaluated at the end of the experimental period. A treatment × period interaction was observed on total DM intake (DMI; P < 0.0001), given that no treatment differences were observed during ADP (P > 0.33), whereas CSFA-supplemented animals had a reduced DMI during GRO and FIN phases (P < 0.05). When individual mean nutrient intake was evaluated, CSFA supplementation caused a reduction in crude protein and physically effective neutral detergent fiber intake (P ≤ 0.05), and tended to reduce metabolizable energy, net energy for maintenance and gain intake (P = 0.06). Additionally, CSFA inclusion or CTS increase into the diet did not affect final BW, BW change, average daily gain (ADG), hot carcass weight, carcass ADG, and yield gain (P ≥ 0.11). On the other hand, CSFA reduced DMI as percentage of BW and improved feed efficiency (FE; P < 0.02) and also tended to improve biological conversion (BC; P = 0.07) versus CTS. Similarly, increasing CTS byproducts in the diet improved FE and BC (P = 0.02) but also tended to increase dressing percentage (DP; P = 0.08). In summary, including CSFA into feedlot diets reduced DMI but improved FE and BC of beef cattle, demonstrating the efficacy of this technology on feedlot beef cattle diets. Moreover, increasing cottonseed byproducts into the diets also benefited FE, BC, and DP of finishinw B. indicus cattle.

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170 Meta-analysis to Determine the Standardized Ileal Digestible Lysine Requirements of Growing-finishing Pigs from 11- to 150-kg

Journal of Animal Science ◽

10.1093/jas/skab054.104 ◽

2021 ◽

Vol 99 (Supplement_1) ◽

pp. 62-63

Author(s):

Uislei A Orlando ◽

Carine M Vier ◽

Wayne R Cast ◽

Ning Lu ◽

Ron A Navales ◽

...

Keyword(s):

Meta Analysis ◽

Energy Levels ◽

Average Daily Gain ◽

Random Effect ◽

Growth Curves ◽

Metabolizable Energy ◽

Experimental Unit ◽

Net Energy ◽

Finishing Pigs ◽

Ingredient Composition

Abstract A meta-analysis was conducted to determine the standardized ileal digestible (SID) lysine (Lys) recommendations for 11–150 kg PIC pigs housed under commercial conditions. Data from 29 trials dating from 2013 to 2020 utilizing 48,338 pigs were recorded in a database. Number of pens/treatment and pigs/trial ranged from 9 to 16 and 12 to 25, respectively. Sire lines were PIC 337 in 25 trials, PIC 327 in 3 trials, and PIC TR4 and 327 in 1 trial. Dam lines were PIC Camborough in 18 trials and PIC Camborough 29 in 9 trials. The SID Lys to calorie ratio curves were built for both metabolizable energy (ME) and net energy (NE) systems using the feed ingredient composition in NRC (2012) for energy levels. The response variables average daily gain (ADG) and feed efficiency (G:F) were analyzed using generalized linear and non-linear mixed models with heterogeneous variance (Gonçalves et al., 2016). Each treatment mean within a trial (n = 288) was considered the experimental unit and each trial was used as a random effect. The models were developed for mixed gender pigs and the PIC 337 growth curves were used to estimate the recommendations for barrows and gilts. There was no evidence for an interaction between sire lines or dam lines and treatment (P > 0.10). The SID Lys to calorie recommendations are based on the average for ADG and G:F (Table 1). At these levels, approximately 100% of maximum ADG and 99.4% of maximum G:F are achieved. The NE to ME ratio that results in a similar SID Lys recommendation as a percentage of the diet ranged from approximately 0.72 to 0.74. The updated biological requirements for PIC pigs remained similar compared to previous PIC recommendations (Gonçalves et al., 2017). However, the requirement estimates have been adjusted for late nursery and late finishing phases.

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Relationships of retained energy and retained protein that influence the determination of cattle requirements of energy and protein using the California Net Energy System

Translational Animal Science ◽

10.1093/tas/txy120 ◽

2018 ◽

Vol 3 (3) ◽

pp. 1029-1039 ◽

Cited By ~ 4

Author(s):

Luis O Tedeschi

Keyword(s):

Body Fat ◽

Energy System ◽

The Body ◽

Metabolizable Energy ◽

Net Energy ◽

Body Protein ◽

Protein Requirements ◽

Growing Cattle ◽

Lower Correlation

Abstract Interrelationships between retained energy (RE) and retained protein (RP) that are essential in determining the efficiency of use of feeds and the assessment of energy and protein requirements of growing cattle were analyzed. Two concerns were identified. The first concern was the conundrum of a satisfactory correlation between observed and predicted RE (r = 0.93) or between observed and predicted RP when using predicted RE to estimate RP (r = 0.939), but a much lower correlation between observed and predicted RP when using observed RE to estimate RP (r = 0.679). The higher correlation when using predicted vs. observed RE is a concern because it indicates an interdependency between predicted RP and predicted RE that is needed to predict RP with a higher precision. These internal offsetting errors create an apparent overall adequacy of nutrition modeling that is elusive, thus potentially destabilizing the predictability of nutrition models when submodels are changed independently. In part, the unsatisfactory prediction of RP from observed RE might be related to the fact that body fat has a caloric value that is 1.65 times greater than body protein and the body deposition of fat increases exponentially as an animal matures, whereas body deposition of protein tends to plateau. Thus, body fat is more influential than body protein in determining RE, and inaccuracies in measuring body protein will be reflected in the RP comparison but suppressed in the RE calculation. The second concern is related to the disconnection when predicting partial efficiency of use of metabolizable energy for growth (kG) using the proportion of RE deposited as protein—carcass approach—vs. using the concentration of metabolizable energy of the diet—diet approach. The culprit of this disconnection might be related to how energy losses that are associated with supporting energy-expending processes (HiEv) are allocated between these approaches. When computing kG, the diet approach likely assigns the HiEv to the RE pool, whereas the carcass approach ignores the HiEV, assigning it to the overall heat production that is used to support the tissue metabolism. Opportunities exist for improving the California Net Energy System regarding the relationships of RE and RP in computing the requirements for energy and protein by growing cattle, but procedural changes might be needed such as increased accuracy in the determination of body composition and better partitioning of energy.

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Greenhouse gases and performance of growing pigs fed wheat-based diets containing wheat millrun and a multi-carbohydrase enzyme

Journal of Animal Science ◽

10.1093/jas/skab213 ◽

2021 ◽

Vol 99 (10) ◽

Author(s):

Agbee L Kpogo ◽

Jismol Jose ◽

Josiane C Panisson ◽

Atta K Agyekum ◽

Bernardo Z Predicala ◽

...

Keyword(s):

Energy Content ◽

Average Daily Gain ◽

Ghg Emissions ◽

Nutrient Digestibility ◽

Growing Pigs ◽

Feed Ratio ◽

Net Energy ◽

Enzyme Supplementation ◽

Carbon Dioxide Co2 ◽

The Impact

Abstract The objective of this project was to determine the impact of feeding growing pigs with high wheat millrun diets supplemented with a multi-carbohydrase enzyme (amylase, cellulase, glucanase, xylanase, and invertase activities) on nutrient digestibility, growth performance, and greenhouse gas (GHG) output (carbon dioxide, CO2; nitrous oxide, N2O; methane, CH4). Three experiments were conducted utilizing six treatments arranged as a 3 × 2 factorial (0%, 15%, or 30% wheat millrun; with or without enzyme) for the digestibility experiment or as a 2 × 2 factorial (0% or 30% wheat millrun; with or without enzyme) for the performance and GHG experiments. The digestibility, performance, and GHG experiments utilized 48 individually housed pigs, 180 pigs housed 5 per pen, or 96 pigs housed 6 per chamber, respectively. Increasing wheat millrun up to 30% in the diet of growing pigs resulted in decreased energy, nitrogen (N) and phosphorus (P) apparent total tract digestibility and net energy content (P < 0.01). Overall, average daily gain (ADG) and gain to feed ratio were reduced in pigs fed wheat millrun (P < 0.05). Enzyme supplementation had minimal effects on the digestibility or performance parameters measured. Feeding diets with 30% millrun did not affect GHG output (CH4: 4.7 and 4.9; N2O: 0.45 and 0.42; CO2: 1,610 and 1,711 mg/s without or with millrun inclusion, respectively; P > 0.78). Enzyme supplementation had no effect on GHG emissions (CH4: 4.5 and 5.1; N2O: 0.46 and 0.42; CO2: 1,808 and 1,513 mg/s without or with enzymes, respectively; P > 0.51). Overall, the carbohydrase enzyme had minimal effects on parameters measured, regardless of wheat millrun inclusion (P > 0.10). Although energy, N and P digestibility, and ADG were reduced, the inclusion of up to 30% wheat millrun in the diet has no effect on GHG emissions from growing pigs (P > 0.10).

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Diet formulation method influences the response to increasing net energy in finishing pigs1

Translational Animal Science ◽

10.1093/tas/txz147 ◽

2019 ◽

Vol 3 (4) ◽

pp. 1349-1358 ◽

Cited By ~ 1

Author(s):

Danilo A Marçal ◽

Charles Kiefer ◽

Mike D Tokach ◽

Steve S Dritz ◽

Jason C Woodworth ◽

...

Keyword(s):

Control Diet ◽

Average Daily Gain ◽

High Energy ◽

Feed Ratio ◽

Net Energy ◽

White Grease ◽

Diet Formulation ◽

Finishing Pig ◽

Commercial Processing ◽

Dietary Energy Density

Abstract An experiment was conducted to compare the effects of increasing dietary net energy (NE) in finishing pig diets while either maintaining a standardized ileal digestible lysine:NE ratio (SID Lys:NE) or maintaining SID Lys as a constant percentage of the diet across increasing energy densities. A total of 150 pigs (Line 600 × 241; DNA, Columbus, NE; initially 35.7 kg) were used in a 91-d study. Pigs were blocked by sex and weight and randomly assigned to 1 of 5 treatments with 2 pigs per pen and 15 pens per treatment. Treatments included a low-energy control diet that was corn-soybean meal-based with added soybean hulls, and a 2 × 2 factorial arrangement of treatments with main effects of increasing dietary NE (medium or high by adding choice white grease) and formulation method (with a SID Lys:NE ratio or maintaining the same percentage SID Lys). Linear and quadratic contrasts were made using the control diet and the medium- and high-energy diets within each formulation method. Pigs and feeders were weighed approximately every 30 d to calculate average daily gain (ADG), average daily feed intake (ADFI), and gain-to-feed ratio (G:F). At the end of the experiment, pigs were sent to a commercial processing facility for carcass data collection. From days 0 to 34 and 34 to 61, ADG and SID Lys intake increased as NE increased (linear, P < 0.05) in pigs fed diets with a Lys:NE ratio, but not for those fed the same percentage Lys. As NE increased, NE intake and G:F increased (P < 0.01) in pigs fed diets with either formulation method. From days 61 to 91, increasing NE had no effect (P > 0.10) on ADG. There was no change in G:F in pigs fed diets with the same percentage Lys (P > 0.10), but G:F decreased then increased (quadratic, P < 0.01) in response to increasing NE in pigs fed diets with a SID Lys:NE ratio. Overall, increasing dietary NE increased (linear, P < 0.001) daily NE intake and G:F (linear, P < 0.018) with either formulation method. However, SID Lys intake, ADG, and hot carcass weight only increased (linear, P < 0.01) when a SID Lys:NE ratio was maintained. Increasing NE without maintaining a constant SID Lys:NE ratio increased backfat depth (quadratic, P = 0.01), whereas it did not in pigs fed diets with a SID Lys:NE ratio. In conclusion, increasing dietary energy density increased NE intake and G:F regardless of formulation method. However, a SID Lys:NE ratio must be maintained to achieve increased ADG and minimize fat deposition.

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Evaluation of an active live yeast (Levucell Saccharomyces cerevisiae, CNCM l-1077) on receiving and backgrounding period growth performance and efficiency of dietary net energy utilization in low health risk beef steers1

Translational Animal Science ◽

10.1093/tas/txaa127 ◽

2020 ◽

Vol 4 (3) ◽

Author(s):

Zachary K Smith ◽

Kip Karges ◽

Angel Aguilar

Keyword(s):

Health Risk ◽

Growth Performance ◽

Block Design ◽

Average Daily Gain ◽

Energy Utilization ◽

Feed Ratio ◽

Experimental Unit ◽

Net Energy ◽

Respiratory Pathogens ◽

Live Yeast

Abstract The objective of this experiment was to evaluate the influence of an active live yeast direct-fed microbial (DFM) product on receiving and backgrounding period growth performance and efficiency of dietary net energy (NE) utilization in low health risk beef steers. Maine-Anjou × Angus steers (n = 199; body weight [BW] = 252 ± 32.1 kg) were received from two sources at the Ruminant Nutrition Center in Brookings, SD, in November 2019 and used in a 77-d feedlot receiving and backgrounding experiment. Steers were provided access to long-stem hay and ad libitum water upon arrival. Steers were weighed, vaccinated for respiratory pathogens (source 2 only): infectious bovine rhinotracheitis, bovine viral diarrhea types 1 and 2, parainfluenza-3 virus, and bovine respiratory syncytial virus (Bovi-Shield Gold 5, Zoetis, Parsippany, NJ) vaccinated for clostridial species (Ultrabac 7/Somubac, Zoetis) and pour-on moxidectin (Cydectin, Bayer, Shawnee Mission, KS). Steers (n = 176 steers; initial unshrunk BW = 235 ± 27.6 kg) were allotted to pens (n = 20 pens; 10 pens per treatment; eight or nine steers per pen). Diets were based upon corn silage, dry-rolled corn, and dried distillers grains; dietary treatments were 1) no DFM (CON) and 2) DFM (Levucell SC, Advantage Titan, CNCM l-1077), fed at 10 g/steer/d providing 8 × 109 CFU of active live yeast to each steer daily (DFM). Initial BW was the average of day −1 and day 1 BW (n = 176 steers; initial BW = 253 ± 27.6 kg). On day 21, steers received a 200-mg progesterone and 20-mg estradiol benzoate implant. Data were analyzed from day 1 to 47 (receiving period), day 48 to 77, and from day 1 to 77 as a randomized complete block design; pen served as the experimental unit for all analyses. On day 47 of the experiment, DFM had greater BW (P = 0.01) by 0.9% and average daily gain (ADG; P = 0.01) by 4.2% and gain-to-feed ratio (G:F) tended (P = 0.13) to be 2.8% greater. Day 77 BW did not differ (P = 0.60), cumulative (days 1–77): ADG (P = 0.47), dry matter intake (P = 0.66), and G:F (P = 0.56) were similar. Yeast inclusion had no appreciable influence on performance-based dietary NE utilization or the ratio of observed/expected dietary NE (P ≥ 0.59). In low health risk steers, DFM improved performance during the feedlot receiving period. However, no improvements for DFM were detected for cumulative performance from day 1 to 77. The confirmation of yeast counts indicated the CFU to be above the expected level at the start of the trial but was found below expected level at the end of the trial. This may explain differences during the initial 47 d compared to cumulative growth performance results.

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How did Lofgreen and Garrett do the math?

Translational Animal Science ◽

10.1093/tas/txz072 ◽

2019 ◽

Vol 3 (3) ◽

pp. 1011-1017

Author(s):

James W Oltjen

Keyword(s):

Body Weight ◽

Energy Content ◽

Energy System ◽

Metabolizable Energy ◽

Net Energy ◽

Significant Difference ◽

Linear Fit ◽

Metabolizable Energy Intake ◽

Logarithmic Equation ◽

Finishing Beef Cattle

Abstract Lofgreen and Garrett introduced a new system for predicting growing and finishing beef cattle energy requirements and feed values using net energy concepts. Based on data from comparative slaughter experiments they mathematically derived the California Net Energy System. Scaling values to body weight to the ¾ power, they summarized metabolizable energy intake (ME), energy retained (energy balance [EB]), and heat production (HP) data. They regressed the logarithm of HP on ME and extended the line to zero intake, and estimated fasting HP at 0.077 Mcal/kg0.75, similar to previous estimates. They found no significant difference in fasting HP between steers and heifers. Above maintenance, however, a logarithmic fit of EB on ME does not allow for increased EB once ME is greater than 340 kcal/kg0.75, or about three times maintenance intake. So based on their previous work, they used a linear fit so that partial efficiency of gain above maintenance was constant for a given feed. They show that with increasing roughage level efficiency of gain (slope) decreases, consistent with increasing efficiency of gain and maintenance with greater metabolizable energy of the feed. Making the system useful required that gain in body weight be related to EB. They settled on a parabolic equation, with significant differences between steers and heifers. Lofgreen and Garrett also used data from a number of experiments to relate ME and EB to estimate the ME required for maintenance (ME = HP) and then related the amount of feed that provided that amount of ME to the metabolizable energy content of the feed (MEc), resulting in a logarithmic equation. Then they related that amount of feed to the net energy for gain calculated as the slope of the EB line when regressed against feed intake. Combining the two equations, they estimate the net energy for maintenance and gain per unit feed (Mcal/kg dry matter) as a function of MEc: 0.4258 × 1.663MEc and 2.544–5.670 × 0.6012MEc, respectively. Finally, they show how to calculate net energy for maintenance and gain from experiments where two levels of a ration are fed and EB measured, where one level is fed and a metabolism trial is conducted, or when just a metabolism trial is conducted—but results are not consistent between designs.

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Evaluation of the National Research Council (NRC) nutrient requirements for beef cattle: Predicting feedlot performance

Canadian Journal of Animal Science ◽

10.4141/a03-009 ◽

2003 ◽

Vol 83 (4) ◽

pp. 787-792

Author(s):

E. K. Okine ◽

D. H. McCartney ◽

J. B. Basarab

Keyword(s):

Beef Cattle ◽

Dry Matter ◽

Research Council ◽

Average Daily Gain ◽

National Research Council ◽

Metabolizable Energy ◽

Dry Matter Intake ◽

Net Energy ◽

Feeder Cattle

The accuracy of predicted CowBytes® versus actual dry matter intake (DMI) and average daily gain (ADG) of 407 Hereford × Angus and Charolais × Maine Anjou (445.6 ± 36 kg) feeder cattle using digestable enery acid detergent fiber (DE) estimated from the (ADF) content [Laboratory analysis method (LAB)] and from values determined in vivo (INVIVO method) was examined. The diet consisted of a 73.3% concentrate diet, 22.0% barley silage, 1.6% molasses, and 3.1% feedlot supplement fed ad libitum (as-fed basis). The calculated DE values of the feed were used to predict the metabolizable energy (ME), net energy of maintenance (NEm), and net energy of gain (NEg) of the diet. These energy values were then used in CowBytes® to predict dry matter intake (DMI), ADG, and days on feed (DOF) necessary to meet targeted quality grade of AA and weights of 522 and 568 kg for the heifers and steers, respectively. There was no effect of gender and prediction method interaction (P > 0.10) on any of the variables measured. There were no (P > 0.05) differences in predicted DMI by either the INVIVO or LAB method but both methods underestimated DMI actually consumed by the cattle by 6.8 and 4.9% (P = 0.007), respectively. Indeed, regression values from these predictive methods and actual DMI were (P < 0.05) different from the one-to-one relationship expected by definition. In spite of the higher actual DMI, the actual ADG of the cattle was 14 and 11% (P = 0.0004) lower than was predicted by either the INVIVO or LAB methods. A possible reason for the lower ADG could be an overestimation of DE of the diet. Thus, if available, users of CowBytes® should use actual DMI from their experience in ration formulation. In addition, the effects of environmental temperature on digestibility of diets should be taken into consideration when using the DE of the diet as determined from in vivo digestibility trials or calculated from chemical analyses in determining the DMI of feedlot cattle. Key words: Beef cattle, performance, CowBytes®, National Research Council

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128 Determining the effects of high phytase levels and feeding duration on growth performance and carcass characteristics of growing-finishing pigs

Journal of Animal Science ◽

10.1093/jas/skaa054.093 ◽

2020 ◽

Vol 98 (Supplement_3) ◽

pp. 50-51

Author(s):

Carine Vier ◽

Steve S Dritz ◽

Mike D Tokach ◽

Jon Bergstrom ◽

Jason C Woodworth ◽

...

Keyword(s):

Block Design ◽

Average Daily Gain ◽

Carcass Characteristics ◽

Metabolizable Energy ◽

Net Energy ◽

Finishing Pigs ◽

Distillers Grains With Solubles ◽

Dried Distillers Grains ◽

Feeding Duration ◽

Heat Stable

Abstract Our objective was to determine the effects of high phytase levels and feeding duration on performance of growing finishing pigs. A total of 1,215 barrows and gilts (PIC 359×Camborough, initially 28.0±0.47 kg) were used in a 126-d growth trial with 27 pigs per pen and 15 pens per treatment in a randomized complete block design. Diets were corn-soybean meal-dried distillers grains with solubles-based.Treatments were: 1) Control (no added phytase); 2) Grower phytase (1,500 FYT/kg added phytase fed from d 0 to 57, then no phytase from d 57 to market); and 3) Grow-finish phytase (1,500 FYT/kg added phytase fed throughout the study). Phytase (Ronozyme Hiphos GT 2500, heat-stable; DSM Nutritional Products, Inc., Parsippany, NJ) was assumed to release 0.146% digestible phosphorus (P), 0.166% available P, 0.102% STTD calcium, 53 kcal/kg of metabolizable energy, 42 kcal/kg of net energy (NE), and 0.0217, 0.0003, 0.00886, 0.0224, 0.0056, 0.0122, and 0.0163% standardized ileal digestible lysine, methionine, methionine+cysteine, threonine, tryptophan, isoleucine, and valine, respectively. Beef tallow and feed grade amino acids (AA) were added to the diets without phytase to balance NE and AA across treatments. Data were analyzed using generalized linear mixed models with pen as the experimental unit.Overall, pigs fed diets with no phytase and pigs that were only fed phytase in the grower period had greater (P< 0.05) average daily gain (ADG) and feed efficiency (G:F) than pigs fed the phytase-containing diets until market. Pigs fed the control and grower phytase treatments had greater (P< 0.10) hot carcass weight (HCW) than the phytase throughout treatment. No evidence of differences (P >0.10) were observed for other carcass characteristics. In summary, adding 1,500 FYT/kg of phytase and using full matrix values for minerals, AA, and energy had detrimental effects on ADG, G:F, and HCW in this study when applied to the entire grow-finish period.

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