Dietary Content Research Articles

Dietary isoleucine content defines the metabolic and molecular response to a Western diet.

The amino acid composition of the diet has recently emerged as a critical regulator of metabolic health. Consumption of the branched-chain amino acid isoleucine is positively correlated with body mass index in humans, and reducing dietary levels of isoleucine rapidly improves the metabolic health of diet-induced obese male C57BL/6J mice. However, it is unknown how sex, strain, and dietary isoleucine intake may interact to impact the response to a Western Diet (WD). Here, we find that although the magnitude of the effect varies by sex and strain, reducing dietary levels of isoleucine protects C57BL/6J and DBA/2J mice of both sexes from the deleterious metabolic effects of a WD, while increasing dietary levels of isoleucine impairs aspects of metabolic health. Despite broadly positive responses across all sexes and strains to reduced isoleucine, the molecular response of each sex and strain is highly distinctive. Using a multi-omics approach, we identify a core sex- and strain- independent molecular response to dietary isoleucine, and identify mega-clusters of differentially expressed hepatic genes, metabolites, and lipids associated with each phenotype. Intriguingly, the metabolic effects of reduced isoleucine in mice are not associated with FGF21 - and we find that in humans plasma FGF21 levels are likewise not associated with dietary levels of isoleucine. Finally, we find that foods contain a range of isoleucine levels, and that consumption of dietary isoleucine is lower in humans with healthy eating habits. Our results demonstrate that the dietary level of isoleucine is critical in the metabolic and molecular response to a WD, and suggest that lowering dietary levels of isoleucine may be an innovative and translatable strategy to protect from the negative metabolic consequences of a WD.

Effects of dietary soybean lecithin on growth, tissue fatty acid composition, and gonadal development in the hermaphroditic rice field eel (Monopterus albus)

This study investigates the effects of soybean lecithin (SL) on the growth, fatty acid composition, lipid metabolism, and gonadal development of rice field eels. Fourteen-month-old eels were fed either fish oil diets or varying levels of dietary soybean lecithin (0 %, 1.4 %, and 2.8 %) for 10 weeks. Dietary SL had no significant impact on growth, whereas 1.4 % SL led to a significant decrease in moisture content and an increase in crude protein content in eels. The content of both saturated and polyunsaturated fatty acids increased in muscles fed the higher SL diet, with a concurrent decline in saturated fatty acids and an increase in polyunsaturated fatty acids detected in the liver. The expression levels of genes related to lipid synthesis, including accα and PPARγ, and genes related to polyunsaturated fatty acid synthesis, such as pla2g4a, fad2 and scd, were significantly increased in the liver of eels fed with 1.4 % SL diet. SL supplementation enhances lipid transport and antioxidant capacity in the liver, reduces fat deposition, and protects the liver from damage. Hepatosomatic index of fish in the SL1.4 % and SL2.8 % groups decreased. Supplementation of the diet with 1.4 % SL led to a significant decrease in the content of saturated fatty acids and an increase in the content of polyunsaturated fatty acids in the gonads, with a significant increase in arachidonic acid levels. The gonadosomatic index also increased with increasing dietary SL content. Rice field eels fed diets containing SL exhibited elevated serum levels of E2, delayed ovary-to-testis transition, and a preference for retaining the female state. In conclusion, dietary supplementation with SL increased the proportion of highly unsaturated fatty acids in the tissues, enhanced lipid metabolism in the liver, and improved antioxidant capacity. Furthermore, SL supplementation has been demonstrated to promote ovarian development and delay sex reversal in rice field eels.

Fish stocks as phosphorus sources or sinks: Influenced by nutritional and metabolic variations, not solely by dietary content and stoichiometry

The study provides a descriptive understanding of when fish (Cyprinus carpio model) are the source or sink of phosphorus. Dissolved reactive phosphorus (DRP; PO4-P) losses (51.1 ± 5.9 % of intake-P) increase at excess of bioavailable P (>0.83 g 100 g−1 dry matter, DM fed) or when food (digestible) N:P mass ratio (≤4.4:1) approaches organismal storage threshold (~4:1). This is known, however, even at a sub-threshold food P content (0.57 g 100 g−1 DM) and food N:P mass ratio (7.3:1), DRP losses (57.8 ± 4.5 % of intake-P) may be extraordinary if two indispensable amino acids are biologically insufficient (lysine ≤1.43 g, methionine ≤0.39 g 100 g−1 DM fed). Given that methionine and lysine are sufficient, DRP losses cease (≈0 %) and even some P from water is absorbed, given there is support from non-protein energy (NPE). Insufficient NPE (<180 kcal 100 g−1 DM fed) may drive DRP losses (81.6 ± 4.3 % of intake-P) beyond expected levels (46–59 % of intake-P) at a given food P content (0.91 g 100 g−1 DM). Natural food seldom fulfills low P, high lysine + methionine, and high NPE contents simultaneously, thus keeping fish in a perpetual P recycling for algae (scaleless carp > scaly carp). Such P recycling ceases only during basal metabolism. During feeding state, the richness of lysine + methionine bound N and lipid + carbohydrate bound C in the food base may enhance the fishes' threshold of P storage. P storage can be diminished when they are insufficient. We show that for fish, the decision of P recycling or not recycling (for algae) may change based on the supply of specific fractions of N or C from the food web or metabolic variations (basal metabolism, presence of scales). Novelty statementThe ecological stoichiometry theory is better connected to fish nutritional bioenergetics for better understanding and biomanipulation of eutrophication processes.

Effects of Low-Lipid Diets on Growth, Haematology, Histology and Immune Responses of Parr-Stage Atlantic Salmon (Salmo salar).

Lipids in fish diets provide energy and play important roles in immunity and metabolism. Atlantic salmon, a species that migrates from freshwater to seawater, requires high energy, especially during smoltification. Juvenile teleosts have low lipid requirements, and a high dietary lipid content is known to have negative effects on their growth and digestion. Therefore, this study evaluated the effect of two commercial rainbow trout feeds (low-lipid, 13.41% and 14.6%) on the growth and immune responses of early parr-stage Atlantic salmon compared to commercial salmon feed (high-lipid, 29.52%). Atlantic salmon parr (weight: 14.56 ± 2.1 g; length: 11.23 ± 0.44 cm) were randomly divided into three groups and fed either one of two commercial rainbow trout feeds (RTF1 and RTF2) or the commercial salmon feed (ASF) for 12 weeks. At the end of the feeding trial, growth, haematology, histology and gene expression analyses were performed. There were no significant differences in weight gain rates or feed efficiency between the groups (p > 0.05). Superoxidate dismutase, glutathione peroxidase, lysozyme and immunoglobulin M activities were not different among the experimental groups (p > 0.05). A histological examination of the liver and intestinal tissues showed no pathological symptoms of inflammatory response or lipid accumulation in any of the groups. In an intestinal transcriptome analysis using RNA-seq, the expression levels of several genes linked to lipids, immune-related proteins, cytokines and chemokines did not differ significantly between the groups (p > 0.05). Commercial rainbow trout feed with low lipid content has no clear negative impact on the development of Atlantic salmon during the early parr stage (14.5 to 39.6 g). This study provides basic information for the development of economical feed for early parr-stage Atlantic salmon.

Dietary lipid supplementation alleviated the impacts of polystyrene nanoplastic exposure in Litopenaeus vannamei

The widespread occurrence of nanoplastic (NP) pollution in the environment is a growing concern, and its presence poses a potential threat to cultured aquatic animals. Previously, we found that NPs can significantly affect the lipid metabolism of shrimp. However, relevant reports about the effects of increasing dietary lipid levels on NP toxicity are lacking. Therefore, we explored the effects of dietary supplementation with different lipid levels on the growth and lipid metabolism of Pacific white shrimp (Litopenaeus vannamei). We cultured L. vannamei at three dietary lipid levels (3 %, 6 %, and 9 %) and three NP concentrations (0, 1, and 3 mg/L) for 2 months. We evaluated the effects of lipid levels on growth indexes, hepatopancreas morphological structure, lipid metabolism-related enzyme activity, and gene expression of the shrimp. The results showed that as lipid intake increased, the survival rate, body weight growth rate, and hepatosomatic ratio of the shrimp increased while the feed conversion rate decreased. Additionally, the crude protein and crude lipid contents increased, whereas the moisture and ash contents did not change much. We found that the morphological structure of the hepatopancreas was seriously damaged in the 3 mg/L NPs and 3 % dietary lipid group. Finally, lipid metabolism-related enzyme activities and gene expression levels increased with increased dietary lipid levels. Together, these results suggest that increasing dietary lipid content can improve shrimp growth and alleviate lipid metabolism disorders caused by NPs. This study is the first to show that nutrition regulation can alleviate the toxicity of NPs, and it provides a theoretical basis for the green and healthy culture of L. vannamei.

Effects of dietary vitamin D3 and carbohydrate levels on growth performance, carbohydrate metabolism, and intestinal health of yellow catfish (Pelteobagrus fulvidraco)

The study was performed to determine effects of vitamin D3 (VD3) and carbohydrate levels in the diets on growth, carbohydrate absorption and metabolism, and intestinal health of yellow catfish (Pelteobagrus fulvidraco). Four groups of yellow catfish with an average weight of 4.12 ± 0.00 g were provided with diets containing varying proportions of VD3 and carbohydrate. These diets included two VD3 levels at 1000 IU/kg (basic VD3) and 16,100 IU/kg diet (high VD3), each containing carbohydrate levels of 25% and 35%, respectively. After analyzing dietary VD3 and carbohydrate contents, these groups were labeled as follows: the control (30.78% carbohydrates +1040 IU/kg), the VD3 group (30.67% carbohydrates +16,041 IU/kg), the high-carbohydrate group (HCD group, 39.65% carbohydrates +1017 IU/kg), and the HCD + VD3 group (39.67% carbohydrates +16,061 IU/kg). Each tank consisted of three replicates, with each replicate containing 30 fish. The experiment continued for 10 weeks. Compared with the control, HCD group reduced growth performance, the muscular layer thickness, the zonulae occludentes1 and 3 (zo1, zo3), junctional adhesion molecules 3a (jam3a), claudin1, occludin, phosphoglucomutase 1 (pgm1) mRNA expression, but increased intestinal villi height, glycogen content, glycogen synthase (gs), glycogen branching enzyme (gbe), sodium/glucose cotransporter 1 and 2 (sglt1, sglt2) and glucose transporter 2 (glut2) mRNA expression, solute carrier family 5 member 1 (SGLT1) protein expression, and dietary VD3 group alleviated HCD-induced variations of these indices mentioned above. Compared to the control, HCD group significantly suppressed pyruvate carboxylase b (pcxb), phosphoenolpyruvate carboxykinase (pepck), interleukin10 (il10), NFE2 like bZIP transcription factor 2 (nrf2), superoxide dismutase 2 (sod2) and catalase 1 (cat1) mRNA expression, and also inhibited the activities of glutathione peroxidase (GPX), catalase (CAT), total superoxide dismutase (T-SOD) and total antioxidant capacity (T-AOC), but increased hexokinase 1 (hk1), glucokinase (gk), 1-phosphofructokinase (pfkb), interleukin 1β (il1β), interleukin 6 (il6), tumor necrosis factor a and β (tnfa, tnfβ) mRNA expression, and malondialdehyde (MDA) content; dietary VD3 group further suppressed gluconeogenic genes (pcxb, pepck) expression, but significantly enhanced the expression of glycolytic genes (hk1, gk, pfkp). Dietary VD3 also alleviated HCD-induced variations of these indices involved in antioxidant and inflammatory responses in yellow catfish intestine. Based on these results, our study indicated that dietary VD3 contributed to alleviate HCD-induced adverse effects on intestinal carbohydrate utilization and health. Our study also elucidated the innovative insights into the interaction of HCD and VD3 in fish, and provided the potential strategies for improving dietary carbohydrate utilization of fish via VD3 addition in aquafeeds. These findings can potentially contribute to cost savings for businesses and serve as a reference for optimizing feed formulations.

Effects of Starter Diet Energy Concentration on Nutrient Digestibility and Subsequent Growth Performance and Meat Yields of Broilers under Two Coccidiosis Control Programs.

An experiment was conducted to evaluate the live performance, processing characteristics, and apparent ileal digestibility (AID) of nutrients and energy (IDE) in broilers under two coccidiosis control programs (CCP) and fed three starter diet energy levels. Treatments were a factorial arrangement of CCP [in-feed diclazuril (ACD) or vaccinated after hatch (VAC)] and three starter diet energy levels [3008 (standard), 3058 (moderate), and 3108 (high) kcal/kg apparent MEn] achieved with different soybean oil concentrations. Birds were reared in floor pens (12 per pen) and received experimental starter diets from 0 to 18 d and common grower and finisher diets to 43 d. At d 11, VAC birds had higher (p < 0.05) excreta oocyst counts and lower (p < 0.05) plasma carotenoids, nutrient AID, and IDE than ACD birds. From 0 to 18 and 0 to 31 d, VAC decreased (p < 0.05) body weight gain and increased (energy × CCP, p < 0.05) feed conversion ratio of birds fed the moderate and high-energy diets but not for those fed the standard energy diet. From 0 to 43 d, VAC only increased the feed conversion ratio of birds fed the moderate-energy starter diet (energy × CCP, p < 0.05). Carcass yields were lower (p < 0.05) for VAC birds than for ACD birds, and interactive effects (p < 0.05) were observed for wing yield. In summary, increasing dietary lipid concentration to account for Eimeria-induced reductions in lipid digestibility during the starter period of coccidiosis-vaccinated broilers may exacerbate, rather than ameliorate, these impacts on bird performance.

Effects of dietary lipid levels on growth, lipid metabolism, fatty acid composition and antioxidant capacity of juvenile greasyback shrimp (Metapenaeus ensis)

The optimal dietary lipid requirement and underlying lipid metabolic mechanisms remain elusive in greasyback shrimp (Metapenaeus ensis), presenting significant obstacles to the advancement of their culture development. Five isonitrogenous diets (38.39% crude protein) containing lipid levels of 2.25%, 4.72%, 7.50%, 10.18%, and 12.71% were formulated to evaluate the effects of dietary lipid levels on growth, lipid metabolism, fatty acid composition and antioxidant capacity of juvenile greasyback shrimp. The results indicated that shrimps fed a diet with 7.50% lipid exhibited significantly higher percent weight gain (161.36%) and specific growth rate (1.72%/d) than those fed other diets (P < 0.05). As the dietary fat content increased, the lipid levels of the whole shrimp, muscle, hepatopancreas, and serum exhibited similar elevations. Concurrently, H&E staining clearly revealed the occurrence of hepatocyte swelling and hepatocyte vacuolization in the 10.18% and 12.71% groups, and hepatic lipid accumulation was further observed in these groups by Oil red O staining. In addition, with the increase in dietary fat levels, saturated fatty acids (SFA) decreased and polyunsaturated fatty acids (PUFA) increased in both hepatopancreas and muscle. The expression of genes involved in lipogenesis (fas, acc and dgat) was initially up-regulated and subsequently down-regulated with increasing dietary lipid levels, whereas the expression trends of lipolysis genes (hsl, atgl) remained similar. The mRNA levels of genes associated with long-chain PUFA biosynthesis (elovl5, lxrβ, srebp1) and fatty acid oxidation (cpt1, acox1) in the hepatopancreas of shrimp fed a diet with 7.50% lipid were significantly elevated compared to those in other dietary groups (P < 0.05). With the increase in dietary fat levels, the expression of fatty acid transport genes fatp4 and fabp1 was up-regulated. Antioxidant enzyme activities in the hepatopancreas initially increased with dietary lipid levels, peaking in shrimp fed the 7.50% lipid diet, but subsequently declined. In conclusion, optimal dietary fat levels enhance growth performance, while high lipid levels impede growth, decrease antioxidant enzyme activities, and regulate lipid deposition in greasyback shrimp by modulating lipid metabolic pathways.

Seasonal Variation and Dietary Effects in the Fatty Acid Composition of Bulk Tank Milk in Taiwan

Background: Information about seasonal variation in the fatty acid (FA) composition of bulk tak milk and its relationship with dietary factors in Taiwan remains to be completed. This study aimed to determine the average FA composition of milk in different seasons and collect dietary information to investigate the relationship between dietary characteristics and lactation performance, including FA concentration in bulk tank milk. Methods: Bulk tank milk samples were collected monthly from 90 dairy farms across Taiwan for two years to capture seasonal variations. Additionally, 36 bulk tank milk samples from three farms were collected monthly from August 2022 to July 2023. Result: Milk production (kg/day), fat (%), crude protein (%), true protein (%), lactose (%) and solids-not-fat (%) were significantly higher in the cold season than in the hot and warm seasons (P less than 0.05) over the studied period. In contrast, somatic cell counts were significantly lower in the cold season than in the hot and warm seasons (P less than 0.05). Total saturated FA and C14:0 concentrations were significantly higher in the cold season than in the hot and warm seasons (P less than 0.05). In contrast, the C18:1 concentration was significantly higher in the hot and warm seasons than in the cold season (P less than 0.05). However, the C18:0 concentration did not differ significantly by season. Fat and FA concentrations varied significantly among three selected dairy farms (P less than 0.05). Milk fat only differed significantly between the three farms in the hot season, with Farm B having the lowest milk fat concentration (P less than 0.05). FA concentrations showed significant seasonal effects at all three farms. These results provide an overview of milk FA variation and identify the critical factors influencing variation in bulk tank milk fat and individual farm FA concentrations: dietary ether extract content and forage choice.

Integrated multiple-omics reveals the regulatory mechanism underlying the effects of homologous Bacillus tequilensis (GCB-3) on growth performance of grass carp (Ctenopharyngodon idellus)

The purpose of this study was to investigate the regulatory mechanism of Bacillus tequilensis (GCB-3) in improving the growth performance of grass carp by microbiome and targeted metabolomics analysis. Fish were fed with different amounts of GCB-3 including B0 (0 CFU/g), B6 (1×106 CFU/g), B7 (1×107 CFU/g), B8 (1×108 CFU/g), and B9 (1×109 CFU/g) for 8 weeks. The results indicate that with the increase of dietary GCB-3 concentration, grass carp showed a significant linear trend in growth performance, and appetite factors showed a significant linear and quadratic trend, the growth performance and appetite-promoting factors in the B8 group reach their maximum value in the B8 group. Microbiome analysis found that Proteobacteria and Actinobacteria were the most abundant phylum in the gut microbiota of grass carp. The functional potential predicted that GCB-3 affected the synthesis and degradation of carbohydrates, amino acids, fatty acids and lipids. It found that GCB-3 also affected the tricarboxylic acid (TCA) cycle VII (acetate-producers) pathway. The results of targeted metabolomics showed a significant linear and quadratic increase in intestinal acetate with GCB-3 concentration and a maximum in the B8 group. The results of the correlation analysis showed a significant positive correlation between Actinobacteria abundance and acetic acid content, and also between TCA cycle VII (acetate-producers) pathway abundance and Actinobacteria abundance and acetic acid content. In B8 group, grass carp showed a faster regulation speed of blood glucose levels after glucose injection, and the GLP-1 content remained stable. The activities of glycolytic enzymes, lipolytic enzymes, protein metabolism enzymes, and their related mRNA expression levels in grass carp showed a linear or quadratic increasing trend. However, the expression levels of gluconeogenic enzymes and fatty acid synthesis enzyme related mRNA showed an opposite trend. In summary, the addition of 1×108 CFU/g GCB-3 in grass carp feed can improve the abundance of dominant bacterial phyla in the intestine, especially Actinobacteria, increase the concentration of intestinal acetate, provide substrate for the TCA cycle VII (acetate-producers) pathway, thereby regulating the nutrient metabolism of grass carp and ultimately promoting growth.

Dietary CP and digestion kinetics influence BW loss, litter weight gain, and reproduction by affecting postprandial amino acid metabolism in lactating sows

To avoid a high body protein mobilization in modern lean sows during lactation, an adequate dietary amino acid (AA) supply and an efficient AA utilization are crucial. This study evaluated the effects of dietary CP and in vitro protein digestion kinetics on changes in sow body condition, litter weight gain, milk composition, blood metabolites, protein utilization efficiency and subsequent reproductive performance. We hypothesized that a slower digestion of dietary protein would improve AA availability and utilization. In total, 110 multiparous sows were fed one of four lactation diets in a 2 × 2 factorial design, with two CP concentrations: 140 g/kg vs 180 g/kg, and two protein digestion kinetics, expressed as a percentage of slow protein (in vitro degradation between 30 and 240 min): 8 vs 16% of total protein. Feeding sows the high CP diets reduced sow weight loss (Δ = 7.6 kg, P < 0.01), estimated body fat loss (Δ = 2.6 kg, P = 0.02), and estimated body protein loss (Δ = 1.0 kg, P = 0.08), but only at a high percentage of slow protein. A higher percentage of slow protein increased litter weight gain throughout lactation (Δ = 2.6 kg, P = 0.04) regardless of CP concentrations, whereas a higher CP only increased litter weight gain during week 3 of lactation (Δ = 1.2 kg, P = 0.01). On Day 15 postfarrowing, serial blood samples were taken from a subsample of sows fed with the high CP diets. In these sows, a high percentage of slow protein resulted in higher plasma AA concentrations at 150 and 180 min after feeding (Δ = 0.89, P = 0.02, Δ = 0.78, P = 0.03, mmol/L, respectively) and lower increases in urea at 90 and 120 min after feeding (Δ = 0.67, P = 0.04, Δ = 0.70, P = 0.03, mmol/L, respectively). The higher dietary CP concentration increased total nitrogen loss to the environment (Δ = 604 g, P < 0.01) with a reduction of protein efficiency (Δ = 14.8%, P < 0.01). In the next farrowing, a higher percentage of slow protein increased subsequent liveborn litter size (Δ = 0.7, P < 0.05). In conclusion, feeding sows with a high dietary CP concentration alleviated maternal weight loss during lactation when the dietary protein digestion rate was slower, but lowered protein efficiency. A slower protein digestion improved litter weight gain, possibly by reducing AA oxidation and improving plasma AA availability, thus, improving protein efficiency.

Essentiality of dietary cholesterol and its interactions with phospholipid in juvenile slipper lobster (Thenus australiensis)

This study was conducted to verify the essentiality of dietary cholesterol for early juvenile slipper lobster, Thenus australiensis (initial weight 4.50 ± 0.72 g, mean ± SD, CV = 0.16), and to explore the potential for interactions between dietary cholesterol and phospholipid. An 8-week experiment was conducted using six experimental feeds containing three supplemental cholesterol concentrations (0, 0.2 and 0.4% dry matter) at two supplemental phospholipid concentrations (0% and 1.0% dry matter). Dietary cholesterol concentrations of ≥ 0.2% resulted in up to threefold greater weight gain compared to 0% dietary cholesterol, but without any significant main or interactive dietary phospholipid effect. An interaction was observed for lobster survival with lowest survival (46%) recorded for combined 0% cholesterol and 0% phospholipid compared to every other treatment (71–100%). However, all surviving lobsters at 0% dietary cholesterol, regardless of dietary phospholipid level, were in poor nutritional condition. Apparent feed intake (AFI) was significantly higher at dietary cholesterol ≥ 0.2% but was lower for each corresponding dietary cholesterol level at 1% dietary phospholipid. This implied that the feed conversion ratio was improved with supplemental phospholipid. In conclusion, this study confirms the essential nature of dietary cholesterol and that dietary phospholipid can provide additional benefits.

157 Effects of increasing dietary protein concentration on digestibility of amino acids by growing pigs

Abstract Two experiments were conducted to test the hypothesis that the standardized ileal digestibility (SID) of amino acids (AA) by growing pigs is not influenced by dietary protein concentration if all AA are supplied by soybean protein isolate (SPI) or casein. In Exp. 1, cannulated pigs [n = 12; average body weight (BW) = 39.22 kg; SD = 3.96] were allotted to a replicated 6 × 3 Youden square design with the 6 diets and 3 periods. Five diets were formulated to contain 7 to 35% SPI. An N-free diet was also used. In Exp. 2, cannulated pigs (n = 24 average BW = 23.12 kg; SD = 2.89) were allotted a quadruplicated 6 × 2 Youden square design with the 6 diets and 2 periods. Five diets were formulated to contain 6.75 to 33.75% casein. An N-free diet was also used. Ileal digesta were collected and analyzed for dry matter (DM), Cr, and AA. The statistical models included diet as a fixed variable and square, animal, and period as random effects. Polynomial contrasts were used to test linear and quadratic effects of increasing dietary protein. Results from Exp. 1 indicated that the apparent ileal digestibility (AID) of DM linearly (P = 0.001) decreased and the AID of all AA quadratically (P &amp;lt; 0.05) increased as the inclusion of SPI increased in the diets (Table 1). The SID of His and Trp was not affected by the inclusion of SPI in the diets. However, the SID of Arg, Leu, Lys, Phe, Thr, and Val linearly (P &amp;lt; 0.05) decreased, and the SID of Ile and Met tended to linearly (P &amp;lt; 0.10) decrease as the inclusion of SPI in the diets increased. Results from Exp. 2 indicated that the AID of DM tended to linearly decrease (P = 0.089) as the inclusion of casein increased in the diets (Table 2). The AID of most AA increased quadratically (P &amp;lt; 0.01) and the AID of Trp tended to increase (quadratic, P = 0.068) with increasing inclusion rate of casein. The SID of most AA was independent of casein levels. In conclusion, the anti-nutritional factors may have been increased in the diets as the inclusion of SPI increased and thus resulted in reduced SID values. However, the SID values were not influenced by increasing dietary protein if all AA were supplied by casein that does not contain anti-nutritional factors. Therefore, it is concluded that pigs have the capacity to absorb peptides and AA with the same efficiency if the protein concentration is 30% as if it is 6%. Dietary protein concentration itself, therefore, is not likely to limit AA absorption. However, even small amounts of anti-nutritional factors appear to negatively impact the SID of AA.

PSII-20 Feeding behavior of pigs fed dietary amino acid levels adjusted according to the circadian rhythm

Abstract Pigs are diurnal animals that present feed intake during daylight hours, with feeding peaks in the early morning and late afternoon. However, it is possible that the concentration of amino acids (AA) in the diet throughout the day changes the meal pattern of the pigs. Therefore, the objective of this study was to evaluate the feeding behavior of growing-finishing pigs subjected to adjustment of the concentration of AA in the diet according to the circadian rhythm. Sixty-eight (body weight = 25 kg ± 2.67) barrows were assigned to four treatments, being a daily feeding program (DP) and three sequential feeding programs (SEQ). In DP, dietary AA concentration was adjusted daily, providing 100% of the standardized ileal digestibility (SID) recommendation for the 24-h period. In SEQ, the daily dietary AA concentration was adjusted every 12 h, providing a low AA concentration from 0000 to 1159 h and a high AA concentration from 1200 to 2359 h. The low and high AA concentrations of the SEQ corresponded to ±20%, ±30% and ±40% of daily AA requirements. The experiment lasted 82 d and was divided into three phases. Meal pattern variables were recorded in real time by precision feeders. The information obtained was grouped into four periods: PE1, from 0000-0600 h; PE2, 0601-12:00 h; PE3, 1201-1800 h; and PE4, 1801-2359 h. From this database, the visits to the feeder (n), meals (n), amount of time feeding (min), feed intake (g), and feed intake rate (g/min) were calculated for each period, within each experimental phase. The analysis of variance was performed considering the effects of feeding programs (FP), periods (PE), and their interaction (FP×PE), considered significant when P &amp;lt; 0.05. There was no interaction between FP and PE (P &amp;gt; 0.05; Table1). The visits to the feeder were greater (P &amp;lt; 0.01) in PE2 and PE3 compared with PE1 in phase one and compared with PE1 and PE4 in phases two and three. The meals, amount of time feeding, and feed intake was greater (P &amp;lt; 0.01) in PE2 and PE3 in all phases. Regarding feed intake rate, an PE effect (P ≤ 0.01) was observed in all phases and there was an effect of FP (P &amp;lt; 0.01) in phases one and three. In phase one, pigs ingested feed faster in PE3 than PE1, and in phase three feed intake rate in PE1 was less than in the other (P &amp;lt; 0.01). During phase one, SEQ40 feed intake rate was lower than SEQ30, while in phase three SEQ40 showed lower feed intake rate compared with SEQ30 and DP. Pigs showed greater feeding activity from 0600 to 1800 h. The AA concentration in the diet adjusted according to the circadian rhythm did not change the meal pattern of the pigs throughout the day. However, a decreased feed intake rate was observed in SEQ40 group in phases one and three.

PSI-6 Growth performance of weaned pigs fed an activated zinc oxide to replace pharmacological content of dietary zinc oxide

Abstract The objective of this study was to determine the effect of replacing feed-grade zinc oxide (ZnO) with decreased contents of an activated zinc oxide (aZnO) on growth performance of weaned pigs. A total of 720 pigs (Landrace × Yorkshire × Duroc; TOPICS, Richfield, MN) with an initial body weight (BW) of 5.88 ± 0.97 kg were distributed into 60 pens with 12 pigs per pen following a randomized complete block design. After weaning at 18 d of age, pigs were fed one of five diets differing in ZnO source and Zn content during a 3-phase feeding program for 42 d (Table 1). Experimental diets were formulated to meet minimum nutrient requirements. Mortality was monitored daily and analyzed using survival analysis. Performance data were analyzed by multiple linear regression, with BW gain as dependent variable and Zn source (ZnO, aZnO) and Zn content as the independent variables for each phase. Linear regression analysis used diet A as baseline (150 ppm ZnO). In addition, groups receiving diet E and B, both supplemented with the same ZnO level during phase-1, were compared using a t-test. A linear relationship was observed between BW gain and dietary Zn content (P &amp;lt; 0.001) and Zn source (P = 0.026). A slope ratio between the two Zn sources indicated that pigs provided with aZnO had a 72% greater growth rate compared with ZnO. In addition, during Phase 1, when both diets B and E offered similar Zn concentrations (1,200 ppm) as ZnO and aZnO, pigs fed aZnO outperformed ZnO-fed pigs by 490 g (P &amp;lt; 0.001). The mortality was 7.6% less (P = 0.009) for diet C than diet A. No differences were detected among pigs fed the test diets in Phases 1, 2 and 3 for other variables. In conclusion, results show the potential of aZnO as a suitable replacement for ZnO, but also underscore the effect of dietary Zn content on pig performance and mortality. The aZnO source is a suitable replacement for ZnO, enhancing growth performance in weaned pigs and demonstrating potential for reducing overall Zn usage, thereby mitigating the environmental impact of swine production.

143 Effect of increasing dietary net energy content at a constant lysine on feed intake and performance of 7 to 11 kg and 11 to 20 kg pigs

Abstract Information about NE requirements for nursery pigs is still limited. Therefore, 2 experiments were conducted to evaluate the effect of dietary NE contents on growth performance of 7 to 11 kg pigs (Exp. 1) and 11 to 20 kg pigs (Exp. 2). In Exp. 1, mixed-sex pigs (n = 192; PIC; initial body weight (BW) of 7.8 ± 1.07 kg] were assigned to 4 diets for 14 d. Diets 1 to 4 were formulated to contain 4 levels of NE (9.8, 10.1, 10.4 and 10.7 MJ/kg) and adequate in all AA with standardized ileal digestible (SID) Lys being constant at 1.42%. In Exp. 2, mixed-sex pigs (n = 192; PIC; initial BW of 11.2 ± 1.54 kg) were assigned to 4 diets for 21 d. Diets 1 to 4 contained 4 levels of NE (9.6, 9.9, 10.2 and 10.5 MJ/kg) and adequate in all AA (1.32% SID Lys). For both studies, there were 6 pen replicates (4 entire males and 4 gilts/pen) per treatment, and diets were based on corn, soybean meal, whey powder, wheat bran and soy oil. Pigs had ad libitum access to feed (mash) and water. Individual pigs and pen feed disappearance were weighed weekly to calculate average daily gain (ADG), average daily feed intake (ADFI), and feed efficiency gain to feed ratio (G:F). Data were analyzed by ANOVA using the GLM procedure of SAS with pen as the experimental unit. In Exp. 1, ADFI tended to decrease (quadratic; P ≤ 0.08) with increasing NE levels during d 0 to 7 and d 8 to 14. The ADG during d 0 to 7 tended to be greater (158, 192, 187 and 152 g for diets 1 to 4; quadratic; P = 0.08) at 10.1 MJ/kg NE; however, the overall ADG (d 0 to 14) was not affected by the NE levels. Although not significant, G:F, Lys utilization efficiency were greatest at 10.1 MJ/kg NE for the overall period. In Exp. 2, ADFI decreased (827, 783, 768 and 749 g for diets 1 to 4; linear; P = 0.05) with increasing NE levels during d 15 to 21 but was not affected (P &amp;gt; 0.05) for other periods. The ADG (d 8 to 14) tended to be greater at 9.6 MJ/kg NE (quadratic; P = 0.06) and G:F (d 15 to 21) tended to be greater at a dietary NE of 10.2 MJ/kg (linear; P = 0.10). However, the overall (d 0 to 21) ADG and G:F were not affected (P &amp;gt; 0.05) by NE levels. Although not significant, G:F and Lys utilization efficiency were greatest at a dietary NE of 10.2 MJ/kg for the overall period. These results indicate that G:F of 7 to 11 kg pigs and 11 to 20 kg pigs maximized at a dietary NE content of 10.1 MJ/kg and 10.2 MJ/kg, which correspond to 1.41 and 1.29 g SID Lys/MJ NE, respectively.

164 Impact of varying dietary inclusion of modified distiller’s grains plus solubles weekly compared with constant inclusion on feedlot cattle performance and carcass characteristics

Abstract The use of distiller’s grains in feedlot diets was abundant due to supply and price, but the availability to feedlots and greater prices of distiller’s grains has led to reduced inclusion and more variation in supply, and thus, inclusion within the feeding period for cattle. The hypothesis was that varying inclusion of modified wet distiller’s grains plus solubles (MDGS) in the diet would negatively impact cattle performance due to changing dietary starch concentration and risk of acidosis. One solution to help with ruminal acidosis concerns with variable MDGS inclusion would be increasing roughage inclusion. Therefore, our objective was to evaluate if varying the inclusion of MDGS at normal and 2X normal roughage inclusion influences performance of finishing cattle. In this study, crossbred steers (n = 576) with an initial body weight (BW) = 379 kg (SD= 11 kg) were evaluated for performance and carcass traits over the 143 d on study. Two inclusions of grass hay (6% and 12%) and three treatments related to MDGS (no inclusion, constant inclusion at 25% MDGS, and varying inclusion between 15 and 35% MDGS) were tested in a 2 × 3 factorial. Variable inclusion was accomplished by randomly selecting inclusions of 15, 20, 25, 30, or 35% each week with inclusion averaging 25% over the entire feeding period. There was no interaction between grass hay inclusion and MDGS inclusion (P ≥ 0.67) for performance data except a tendency (P = 0.09) for a gain to feed (G:F) interaction. In treatments fed 12% hay, G:F increased for cattle fed either MDGS inclusion (25% constant or varying inclusion) compared with 0% MDGS. In cattle fed 6% hay, G:F was similar between 0, 25 constant or variable 25% MDGS treatments. There was not an interaction due to a different response of variable versus constant inclusion of MDGS when more hay was included, as hypothesized. The 25% constant MDGS and 25% variable MDGS treatments did not differ (P ≥ 0.22) in average daily gain (ADG), hot carcass weight, or G:F. There was a tendency for cattle fed varying inclusion of MDGS to eat less (P = 0.10), but this difference was small (0.1 kg/d). In general, cattle fed MDGS (constant or varying) had greater dry matter intake and ADG, with greater fatness and marbling compared with cattle fed without MDGS (P ≤ 0.01). As for the degree of liver abscess severity, there was no interaction between treatments. Our results show that although varying supply of MDGS in diets is not recommended or desired, if it occurs and inclusions vary from 15 to 35%, these weekly adjustments did not negatively affect gain or feed efficiency in this study.

246 The effect of trypsin inhibitor unit concentrations from raw soybeans in grower pig performance and protein digestibility

Abstract Soybeans contain two major protease inhibitors, Kunitz trypsin and Bowman-Birk protease inhibitors, both of which are anti-nutritional components that can be directly linked to a reduction in amino acid bioavailability and growth performance in swine. Therefore, the objective of this study was to determine the level at which trypsin inhibitor units (TIU, expressed as TIU/mg of complete feed), coming from raw soybeans, in pig diets result in reduction in growth performance and digestibility. This study used 45 grower gilts initial body weight (BW) = 39.7 ± 2.1 kg] that were individually penned and fed one of five dietary TIU treatments (n = 9 pigs/trt) in a complete randomized design. Diets were representative of a commercial corn-soybean meal diet and formulated to have ranging TIU/mg of complete feed of 0.89, 1.77, 3.55, 6.99, and 11.54 TIU/mg utilizing raw ground soybeans and soybean meal at incremental levels. Analyzed diets contained 0.99, 2.23, 3.07, 6.49, and 9.38 active TIU/mg. Diets were balanced to the same grams of SID Lys:ME of 2.85 and NDF concentration of 7.4% utilizing soybean oil and soybean hulls, respectively. Individual feed intake was recorded throughout, and pig BW were collected on d 0, 21, and 27 to calculate average daily gain (ADG), average daily feed intake (ADFI), and feed efficiency gain to feed ratio (G:F). All pigs were placed into metabolism crates on d 21 for 6 d to determine apparent total tract digestibility (ATTD) of nitrogen (N), N excretion and N balance. Growth performance and ATTD data were analyzed with pig as the experimental unit and diet TIU level as a fixed effect using ANOVA, linear, and quadratic contrast models. Overall, ADG decreased as diet TIU increased (1.07, 1.03, 1.02, 0.91, and 0.83 kg/d, respectively, linear P &amp;lt; 0.001). However, no differences in ADFI (P &amp;gt; 0.10) were reported and this resulted in a decrease in G:F (0.48, 0.45, 0.43, 0.41, 0.36, respectively, linear P &amp;lt; 0.001) as dietary TIU concentrations increased from 0.99 to 9.38 TIU/mg. Compared with 0.99 TIU/mg, pigs fed 9.38 TIU/mg had a 9.32% reduction in final BW (68.7 vs. 62.3 kg, linear P &amp;lt; 0.001). Apparent total tract digestibility of N decreased when pigs were fed 9.38 TIU/mg compared with 0.99 and 2.23 TIU/mg (83.26% vs. 90.29% and 89.57%, respectively, P &amp;lt; 0.001). In conclusion, as total trypsin inhibitor units increase in complete feed of grower pigs, digestibility of protein, growth rates and feed efficiency are reduced in a linear manner.

35 Role and mechanism of supplemental methionine in metabolic stress of broilers raised at high ambient temperature or stock density

Abstract Current poultry production practices may render fast-growing broilers prone to metabolic stresses induced by high ambient temperatures and(or) high stocking densities. As the first limiting amino acid of broilers fed corn-soy diets, methionine also serves as a free radical scavenger. Our laboratory has explored metabolic effects and biochemical mechanisms of supplemental methionine in grower and finisher diets for broilers raised at high temperature or high stock density. In Experiment 1, a total of 360 male, 1 d-old Cornish cockerel chicks were fed four diets (10 pens/treatment, 9 chicks/pen): 100 or 130% required methionine in the diets as DL-methionine (DL-MET) or 2-hydroxy-4-(methylthio)butanoate (HMTBA). The room was maintained at 4 to 13oC above the suggested thermoneutral temperature. The 130% DL-MET and HMTBA diets enhanced (P &amp;lt; 0.05) hepatic GSH concentrations of growers and plasma ferric reducing ability of finishers than the 100% diets. The DL-MET-fed growers had greater (P &amp;lt; 0.05%) muscle GSH and hepatic unsaturated fatty acid concentrations than those fed HMTBA. The methionine form and concentration exerted an interaction effect (P &amp;lt; 0.05) on the expression of inflammation-related genes in the liver of finishers. In Experiment 2, we determined if 30% extra DL-MET alleviated adverse effects of a greater stocking density on broilers. A total of 560 male, 1 d-old Cornish cockerels were housed at two stocking densities (9 and 12 birds/m2) and fed two concentrations of DL-MET (grower: 2.90 or 3.77 g/kg and finisher: 2.60 or 3.38 g/kg). The high stocking density decreased (P &amp;lt; 0.05) body weight and growth performance of growers and(or) finishers. Those differences were largely removed or attenuated by the 130% DL-MET diet. There were interaction effects (P &amp;lt; 0.05) between dietary DL-MET concentrations and stocking densities on activities of glutathione S-transferase in the liver of growers and the breast, thigh, and adipose tissue of finishers as well as on activities of glutathione peroxidase and superoxide dismutase in the thigh of growers. The 130% DL-MET diet decreased (P &amp;lt; 0.05) hepatic gene expression of heat shock protein 90 (18%) and malondialdehyde concentrations in the thigh and breast of finishers (35%). In summary, the high ambient temperature-induced metabolic responses of broilers were mediated by the extra methionine supplementation. That function varied with the chicken age and(or) tissue and the methionine form. Meanwhile, the 30% extra DL-MET addition partially reversed adverse effects caused by the greater stocking density, partially via improving tissue redox status. (This research was supported in part by Evonik Nutrition &amp; Care GmbH, and was published: J. Anim. Sci. 97:4883-4894; J. Anim. Sci. 98:skaa092. doi: 10.1093/jas/skaa092).

198 Evaluation of zinc source and concentration on growth performance of nursery swine

Abstract Trace minerals (TM) supplementation in swine diets can negatively interact with other nutrients. Zinc (Zn) and copper (Cu) mutually inhibit their intestinal absorption; thus, limiting their bioavailability. Recent peer-reviewed work has suggested that nursery pigs fed a diet supplemented with increased Zn experienced impaired Cu metabolism, negatively impacting growth performance. However, it has been demonstrated that mitigation of antagonisms might be possible with the use of organic TM supplemented at decreased concentrations. To validate these findings, a total of 2,629 pigs [initial body weight (BW) = 6.2 kg] were used in a 37-d experiment. Pens of 36 pigs were randomly allotted to 1 of 8 dietary treatments with 9 replications per treatment. Dietary treatments were formulated to contain 1 of 4 Zn sources: Zn Sulfate, Zn Hydroxychloride A (Intellibond Zn [Micronutrients Inc., Indianapolis, IN), Zn Hydroxychloride B [Zn Hydroxychloride (Alltech, Inc., Nicholasville, KY)] or Organic Zn [Bioplex Zn (Alltech, Inc)] at 1 of 2 concentrations: 125 or 250 ppm. The concentrations utilized for Organic Zn treatment were 62.5 or 125 ppm per published recommendations. Experimental diets were fed in two phases: phase 1 from d 0 to 21 and phase 2 from d 22 to 37. Added Cu in both dietary phases was 10 ppm. At d 37, serum and liver samples (data not showed) were collected from 1 barrow per pen and submitted to Michigan State University Veterinary Diagnostic Laboratory to determine Zn and Cu concentration. No significant source × concentration interactions were observed for growth performance in this study. From d 0 to 37, pigs fed the greatest Zn concentration had less (P = 0.040) average daily feed intake (ADFI) and marginally decreased (P = 0.060) average daily gain (ADG), despite Zn source (Table 1). In addition, a marginal improvement (P = 0.070) in gain to feed ratio (G:F) was observed in pigs fed diets containing Organic Zn, regardless of concentration. For mineral concentrations in serum, there was a marginally significant source × concentration interaction (P = 0.078), where pigs fed diets with 125 ppm of Zn Hydroxychloride B had one of the greatest Zn concentrations, yet it was drastically reduced when pigs were fed diets with 250 ppm. Furthermore, Cu concentration in serum was decreased (P = 0.045) in pigs fed the greatest concentration of Zn, despite source. In conclusion, these results suggest that greater dietary Zn concentration impaired Cu absorption, reduced feed intake, and marginally decreased growth. Organic Zn, included at 50% reduced concentrations, marginally improved feed efficiency.