Using caloric efficiency to estimate the net energy value of expelled, extruded soybean meal relative to dehulled, solvent-extracted soybean meal and its effects on growth performance of nursery pigs.

This study aimed to estimate the net energy (NE) value of expelled, extruded soybean meal (MSBM) relative to dehulled, solvent-extracted soybean meal (SSBM) and determine its effects on growth performance of late nursery pigs. A total of 297 pigs (DNA 241 × 600) were weaned (BW 5.10 kg) and placed into 60 pens (2 rooms of 30 pens) with 5 pigs per pen balanced by gender and weaning weight. Pigs were fed a common diet for 21 d. Then, pens of pigs (BW 9.3 kg) were randomly assigned to one of five treatments to provide 12 replications per treatment. Treatments consisted of increasing amounts of MSBM replacing SSBM in the diet (0%, 25%, 50%, 75%, and 100%). All diets were fed for 28 d and were formulated to 1.30% standardized ileal digestible lysine and met or exceeded requirements for amino acids, calcium, and phosphorus. The SSBM diet was formulated to 2,421 kcal/kg and NE was not balanced between diets. Analyzed values for CP, EE, CF, and total lysine for the SSBM were 47.28%, 0.47%, 3.80%, and 3.00%, whereas the MSBM contained 47.41%, 6.88%, 5.32%, and 2.99%, respectively. The MSBM had increased values for KOH solubility and trypsin inhibitor (83.62% and 7,026 TIU/g) compared to the SSBM (73.05% and 3,011 TIU/g), whereas urease activity was similar between the two (0.03 and 0.02 Δ pH, respectively). Data were analyzed using Proc GLIMMIX (SAS 9.4; Cary, NC) with pen as the experimental unit and room as the blocking factor. There was no evidence of differences in ADG and ADFI in pigs fed diets with increasing concentrations of MSBM. Pigs fed diets with increasing concentrations of MSBM had improved (linear, P < 0.001) G:F and caloric efficiency on an NE basis. Using caloric efficiency to estimate NE of the MSBM relative to SSBM, MSBM was estimated to have a value of 2,566 kcal/kg. In conclusion, MSBM contains approximately 123% of the energy of SSBM, which improved feed efficiency when fed to nursery pigs.

Development and Validation of Equations for Predicting the Metabolizable Energy Value of Double-Low Rapeseed Cake for Growing Pigs.

The study was conducted to develop and validate an equation to predict the metabolizable energy (ME) of double-low rapeseed cakes (DLRSC) for growing pigs based on their chemical compositions. In Experiment 1, 66 growing pigs (initial body weight 36.6 ± 4.1 kg) were allotted randomly to a completely randomized design with 11 diets. The diets included a corn-soybean meal basal diet and 10 test diets containing 19.22% DLRSC supplemented at the expense of corn, soybean meal, and lysine. Neutral detergent fiber (NDF), crude fiber (CF), and gross energy (GE) were the best predictors to determine ME. The best-fit prediction equation of ME (MJ/kg) was ME = 9.33 - 0.09 × NDF - 0.25 × CF + 0.59 × GE (R2 = 0.93). In Experiment 2, a total of 144 growing pigs (initial body weight 29.7 ± 2.7 kg), with six pigs per pen and six pens per treatment, were assigned randomly to four treatments in a completely randomized block design for a 28-day feeding trial. A corn-soybean meal basal diet was prepared, and three additional diets were formulated by adding 7%, 14%, and 21% DLRSC to the basal diet at the expense of soybean meal. All diets were formulated to provide equal standardized ileal digestibility (SID) Lys/ME ratio and SID essential amino acids/SID Lys ratio. Increasing dietary levels of DLRSC had no effect on average daily feed intake, average daily gain, and feed-to-gain ratio. The caloric efficiency of ME (31.83, 32.44, 31.95, and 32.69 MJ/kg, respectively) was not changed by increasing the dietary concentration of DLRSC. Increasing dietary levels of DLRSC linearly reduced (p < 0.05) the concentrations of triiodothyronine and tetraiodothyronine in serum, as well as apparent total tract digestibility of DM, GE, crude protein, acid detergent fiber, and organic matter of the diet. In conclusion, the ME prediction equation obtained in Experiment 1 accurately estimates the ME value of DLRSC fed to growing pigs.

Effects of high-protein distillers dried grains on growth performance of nursery pigs.

A total of 300 pigs (DNA 400 × 200, Columbus, NE), initially 11.1 kg, were used in a study to evaluate the effects of increasing amounts of high-protein distillers dried grains (HP DDG) on growth performance and to estimate its energy value relative to corn. Pigs were weaned, placed in pens with five pigs each, and fed a common diet for 21 d after weaning. Then, pens were assigned to treatments in a randomized complete block design. There were 5 treatments with 12 replicates per treatment. Treatments consisted of 0, 10, 20, 30, or 40% HP DDG, formulated by changing only the amounts of corn and feed-grade amino acids. Pigs were weighed weekly for 21 d to evaluate average daily gain (ADG), average daily feed intake (ADFI), and gain-to-feed ratio (G:F). Caloric efficiency was obtained by multiplying ADFI by kcal of net energy (NE) per kg of diet and dividing by ADG. The NE values for corn and soybean meal were obtained from NRC (2012), and initial estimates for HP DDG NE were derived from the Noblet et al. (1994) equation. The energy of HP DDG was estimated based on caloric efficiency relative to the diet without HP DDG. Pigs fed diets with increasing HP DDG had a linear decrease (P < 0.01) in ADG, ADFI, and final body weight. There was a tendency for a quadratic response (P = 0.051) in G:F, with the greatest G:F observed for pigs fed diets with 40% HP DDG. There was a linear reduction (P < 0.05) in caloric efficiency with increasing amounts of HP DDG, indicating the initial NE estimate of HP DDG was underestimated. The use of caloric efficiency to estimate the energy value of HP DDG presents several limitations. This approach assumes that the NE values of corn and soybean meal are accurate and does not take into account possible changes in body composition, which can influence the G:F response as leaner pigs are more efficient. In conclusion, increasing HP DDG in the diet linearly decreased ADG and ADFI. Using caloric efficiency to estimate energy content relative to corn, the HP DDG used in this study was estimated to be 97.3% of the energy value of corn. Direct or indirect calorimetry is needed to confirm this value.

Concerns about the misleading conclusions regarding estimation of the net energy value of soybean meal relative to corn using the caloric efficiency approach in pigs.

Apart from energy balance trials such as calorimetry, growth trials could also be used to estimate the energy values of feed ingredients with caloric efficiency as an indicator. Recent work used such methods reported greater net energy (NE) value of soybean meal (SBM) relative to corn in nursery pigs. We theoretically compared the NE values of SBM and corn according to the definition of NE and properties of the major chemical compositions in each ingredient. Meanwhile, we thoroughly examined the diet formulations and related analysis used in this work and compared this study with some peer works. We found that this study may suffer from problems with experimental design, reference citation, and data interpretation. In summary, the conclusion from the recent work that the SBM NE value may be greater than the corn NE value is likely to be erroneous.

Estimate of the energy value of soybean meal relative to corn based on growth performance of nursery pigs.

BACKGROUND: Two experiments were conducted to determine the effects of increasing amounts of soybean meal (SBM) in swine diets and estimate the energy value of SBM. METHODS: A total of 2233 pigs (PIC 337 × 1050, Hendersonville, TN) and 3796 pigs (PIC 359 × C40), initially 11.0 kg and 17.6 kg body weight (BW), were used in Exp. 1 and 2, respectively. In Exp. 1, pigs were placed in 92 pens each containing 20 to 27 pigs. In Exp. 2, pigs were placed in 84 pens each containing 37 to 43 pigs. Treatments were assigned in a randomized complete block design with BW as the blocking factor. Dietary treatments consisted of 21%, 27%, 33%, or 39% SBM in Exp. 1 and 17.5%, 22%, 26.5%, 31%, 35.5%, or 40% SBM in Exp. 2, obtained by changing the inclusion rate of feed-grade amino acids and corn grain. For Exp. 1, representative samples of corn grain, SBM, and distillers dried grains with solubles were analyzed for total AA content prior to diet formulation. For Exp. 2, diets were formulated using NRC (2012) nutrient loadings. Treatment diets were fed for 21 and 22 d (Exp. 1 and 2) and there were 23 replicates in Exp. 1 and 14 replicates in Exp. 2. Pigs were weighed and feed disappearance measured weekly to calculate average daily gain (ADG), average daily feed intake (ADFI), gain-to-feed ratio (G:F), and caloric efficiency (CE). Data were analyzed with block as a random effect and treatment as a fixed effect, and contrasts were constructed to test the linear and quadratic effects of increasing SBM. RESULTS: In Exp. 1, there was a tendency (linear, P = 0.092) for a decrease in ADFI as SBM increased. There was a tendency (P = 0.090) for a quadratic response for ADG, with a decrease in ADG observed with 39% SBM inclusion. Pigs fed diets with increasing SBM had a tendency (quadratic, P = 0.069) for an increase in G:F up to 33% SBM and an improvement (linear, P = 0.001; quadratic, P = 0.063) in CE with increasing SBM. Using CE to estimate the energy of SBM relative to corn, a value of 105.4% of corn energy or 2816 kcal/kg NE was determined using all data points. When removing the CE value of the 39% SBM treatment due to the quadratic tendency, SBM was estimated to have 121.1% of corn energy or 3236 kcal/kg NE. In Exp. 2, there was a decrease (linear, P = 0.001) in ADFI. Pigs fed increasing SBM had a tendency (linear, P = 0.065) for reduced ADG but an improvement (linear, P = 0.001) in G:F and CE as SBM increased. The energy value of SBM was estimated as 124.7% of corn energy or 3332 kcal/kg NE. CONCLUSIONS: The results suggest that feeding increasing levels of SBM improves G:F and CE. The energy value of SBM was estimated to be between 105% and 125% of corn, which is much greater than the NRC (2012) would indicate.

Effects of soybean meal level on growth performance of 11- to 25-kg nursery pigs.

Four experiments were conducted to determine the effects of increasing soybean meal (SBM) level in diets with or without 25% distillers dried grains with solubles (DDGS) on growth performance of nursery pigs raised in university or commercial facilities. Treatments were arranged in a 2 × 3 factorial with main effects of SBM (27.5%, 32.5%, or 37.5% of the diet) and DDGS (0% or 25% of the diet). A total of 296, 2,502, 4,118, and 711 pigs with initial body weight (BW) of 10.6, 11.7, 12.5, and 12.3 kg were used in Exp. 1, 2, 3, and 4, respectively. There were 10, 16, 13, and 12 replicates per treatment in Exp. 1, 2, 3, and 4, respectively. After weaning, pigs were fed common diets for approximately 21 d. Then, pens of pigs were assigned to treatments in a randomized complete block design with BW as the blocking factor and experimental diets were fed for 21 d. Pigs were weighed and feed disappearance measured to calculate average daily gain (ADG), average daily feed intake (ADFI), gain-to-feed ratio (G:F), and caloric efficiency (CE). Data were analyzed using the GLIMMIX procedure of SAS with block as a random effect and treatment as a fixed effect. Single degree-of-freedom contrasts were constructed to test the linear and quadratic effects of increasing SBM and their interactions with DDGS. Pigs used in all experiments did not undergo major health challenges during the experimental period and due to the low number of mortality and cull events, statistical analysis was not performed on these variables. The average cull rate was 0.7%, 0.5%, 0.2%, and 0%, and the mortality rate was 0.7%, 0.3%, 0.4%, and 0% in Exp. 1-4, respectively. There were interactions (P ≤ 0.039) between SBM and DDGS for G:F and CE in Exp. 2 and for ADG and ADFI in Exp. 3. These were mostly driven by increasing SBM negatively affecting performance in a greater magnitude when diets contained DDGS compared to diets without DDGS. The main effects of DDGS and SBM were more consistently observed across experiments. Pigs fed diets with 25% DDGS had decreased (P ≤ 0.001) ADG and ADFI in all experiments, as well as poorer (P ≤ 0.028) G:F and CE except for Exp. 3. Feeding increasing amounts of SBM generally did not result in any major impact in ADG but consistently improved (linear, P ≤ 0.078) G:F and CE across experiments.

Sex-specific effects of prepubertal stress and high-fat diet on leptin signaling in rats.

OBJECTIVE: Both stress exposure and high-fat diet (HFD) are contributors to the alarming prevalence of obesity. Leptin is secreted from adipose tissue and regulates appetite and body weight via the JAK-STAT3 pathway in the hypothalamus; it also regulates the hypothalamic-pituitary-thyroid axis, modulating energy homeostasis. Leptin signaling may be impaired by HFD intake, and here we investigate whether social isolation during the prepubertal period, associated with chronic HFD, can exert long-term effects on metabolic parameters in a sex-specific manner. METHODS: Wistar male and female rats were divided into two groups (receiving standard chow or standard chow and HFD), which were subdivided into (1) exposed to social isolation during the prepubertal period or (2) not exposed. RESULTS: HFD induced sex-specific effects on leptin signaling and on the hypothalamic-pituitary-thyroid axis; males receiving HFD presented increased T4 but a reduced T3:T4 ratio and higher caloric efficiency during development. A stress × diet interaction was noted for leptin signaling in males, where pSTAT3 was higher when these factors were applied together. On the other hand, females were more susceptible to early stress, which reduced pSTAT3 in the hypothalamus. CONCLUSION: Both stress during the prepubertal period and chronic consumption of HFD had long-term sex-specific effects on hormonal signaling related to energy balance. However, the effects of HFD were more pronounced in males, whereas prepubertal stress had greater effects on leptin signaling in females.

Net energy of corn, soybean meal and rapeseed meal in growing pigs.

BACKGROUND: Two experiments were conducted to estimate the net energy (NE) of corn, soybean meal, expeller-pressed rapeseed meal (EP-RSM) and solvent-extracted rapeseed meal (SE-RSM) using indirect calorimetry and to validate the NE of these four ingredients using pig growth performance. METHODS: In Exp.1, 24 barrows (initial BW = 36.4 ± 1.6 kg) were allotted to 1 of 4 diets which included a corn basal diet, a corn-soybean meal basal diet and two rapeseed meal diets containing 20% EP-RSM (9.5% ether extract) or SE-RSM (1.1% ether extract) substituted for corn and soybean meal. The design allowed the calculation of NE values of corn, soybean meal and rapeseed meals according to the difference method. In Exp.2, 175 growing pigs (initial BW = 36.0 ± 5.2 kg) were fed 1 of 5 diets for 28 d, with five pigs per pen and seven replications (pens) per treatment in order to validate the measured energy values. Diets were a corn-soybean meal diet and four diets including 10% or 20% EP-RSM and 10% or 20% SE-RSM. RESULTS: The NE of corn, soybean meal, EP-RSM and SE-RSM were 12.46, 11.34, 11.71 and 8.83 MJ/kg DM, respectively. The NE to ME ratio of corn (78%) was similar to tabular values, however, the NE to ME ratios of soybean meal (70%) and rapeseed meal (76%) were greater than tabular values. The greater NE value in EP-RSM than in SE-RSM is consistent with its higher EE content. Increasing EP-RSM or SE-RSM did not affect the growth performance of pigs and the caloric efficiency of NE was comparable for all diets. CONCLUSIONS: The NE of EP-RSM was similar to soybean meal, and both were greater than SE-RSM. The DE, ME and NE values measured in Exp.1 are confirmed by results of Exp. 2 with comparable caloric efficiencies of DE, ME or NE for all diets.

A review of feed efficiency in swine: biology and application.

Feed efficiency represents the cumulative efficiency with which the pig utilizes dietary nutrients for maintenance, lean gain and lipid accretion. It is closely linked with energy metabolism, as the oxidation of carbon-containing components in the feed drive all metabolic processes. While much is known about nutrient utilization and tissue metabolism, blending these subjects into a discussion on feed efficiency has proven to be difficult. For example, while increasing dietary energy concentration will almost certainly increase feed efficiency, the correlation between dietary energy concentration and feed efficiency is surprisingly low. This is likely due to the plethora of non-dietary factors that impact feed efficiency, such as the environment and health as well as individual variation in maintenance requirements, body composition and body weight. Nonetheless, a deeper understanding of feed efficiency is critical at many levels. To individual farms, it impacts profitability. To the pork industry, it represents its competitive position against other protein sources. To food economists, it means less demand on global feed resources. There are environmental and other societal implications as well. Interestingly, feed efficiency is not always reported simply as a ratio of body weight gain to feed consumed. This review will explain why this arithmetic calculation, as simple as it initially seems, and as universally applied as it is in science and commerce, can often be misleading due to errors inherent in recording of both weight gain and feed intake. This review discusses the importance of feed efficiency, the manner in which it can be measured and reported, its basis in biology and approaches to its improvement. It concludes with a summary of findings and recommendations for future efforts.

Effects of dietary wheat middlings, corn dried distillers grains with solubles, and net energy formulation on nursery pig performance.

Four experiments were conducted to examine effects of dietary wheat middlings (midds), corn dried distillers grains with solubles (DDGS), and NE formulation on nursery pig performance and caloric efficiency. In Exp. 1, 180 nursery pigs (11.86 ± 0.02 kg BW and 39 d of age) were fed 1 of 5 diets for 21 d, with 6 pigs per pen and 6 replications per treatment. Diets were corn-soybean meal based and included 0, 5, 10, 15, or 20% wheat midds. Increasing wheat midds decreased (linear; P < 0.05) ADG and ADFI. Caloric efficiency improved (linear; P < 0.05) on both an ME (NRC, 1998) and NE (Sauvant et al., 2004) basis as dietary wheat midds increased. In Exp. 2, 210 pigs (6.85 ± 0.01 kg BW and 26 d of age) were fed 1 of 5 diets for 35 d, with 7 pigs per pen and 6 replications per treatment. Diets were corn-soybean meal based and contained 0, 5, 10, 15, or 20% wheat midds. Increasing wheat midds did not affect overall ADG or ADFI but decreased (quadratic; P < 0.013) G:F at 20%. Caloric efficiency for both ME and NE improved (quadratic; P < 0.05) as dietary wheat midds increased. In Exp. 3, 180 pigs (12.18 ± 0.4 kg BW and 39 d of age) were fed 1 of 6 experimental diets arranged in a 2 × 3 factorial with main effects of DDGS (0 or 20%) and wheat midds (0, 10, or 20%) for 21 d, with 6 pigs per pen and 5 replications per treatment. No DDGS × wheat midds interactions were observed, and DDGS did not influence ADG, ADFI, or G:F, but increasing dietary wheat midds decreased (linear; P < 0.05) ADG, G:F, and final BW. In Exp. 4, 210 pigs (6.87 kg BW and 26 d of age) were allotted to 1 of 5 dietary treatments, with 7 pigs per pen and 6 replications per treatment. Wheat middlings (0, 10, or 20%) were added to the first 3 diets without balancing for energy. In diets 4 and 5, soybean oil was added (1.4 and 2.8%) to 10 and 20% wheat midds diets to balance to the same NE as the positive control (0% wheat midds). Overall, no wheat midds × fat interactions occurred. Regardless of formulated energy value, caloric efficiency and G:F were poorer (P < 0.05) on an ME basis as wheat midds increased from 10 to 20% of the diet but did not change when calculated on an NE basis. Results of these experiments indicate that wheat midds may be fed up to 10 to 15% of the diet without negatively affecting nursery pig performance and with no interactive effects when fed in combination with DDGS. Also, formulating on an NE basis provided for similar performance with increasing dietary wheat midds compared with a corn-soybean meal control diet.