Effects Of Dietary Energy Source Research Articles

Effect of dietary energy source on pregnancy rates and reproductive physiology of pastured beef heifers

Proper production of steroid hormones, such as progesterone (P4), is essential for maintenance of pregnancy. Provision of gluconeogenic substrates from the diet may alter postabsorptive energy supplies and associated hormone signaling in a manner supportive of elevating P4 concentrations. Crossbred Angus heifers (n=27) were balanced for pre-trial bodyweight (BW) and body condition score (BCS), then assigned to isoenergetic diets leveraging starch (ES) or fat (EF) as the primary source of energy (45.7% starch vs 11.5% fat). The heifers were placed on the assigned diets 8 days prior to the initiation of estrous synchronization and continued the diets through the second pregnancy diagnosis, 52 days after the initial insemination. On day 28 post-breeding, pregnancy status was diagnosed via ultrasonography. Measurements of follicle size and number were collected via rectal palpation and ultrasonography on days −10, −8, −4, and day 0 relative to breeding. Blood samples were collected on days −10, 1 through 7, 10, 14, 18, 21, 24, and 28 to analyze plasma for P4 concentrations and placental-associated glycoprotein (PAG) concentrations. Data were analyzed using a linear mixed effects model with a fixed effect for treatment and a random effect for pen. Observations collected over time were analyzed using a repeated measures approach with fixed effects for treatment, time, initial condition, and a random effect for pen. Interactions between treatment and pregnancy status were also tested for PAG and P4 concentrations. No treatment differences were observed in final BCS (P=0.12) and total dry matter intake (DMI; P=0.51), though heifers on the ES treatment tended to reach an increased BW (P=0.10). Although heifers fed ES diets had numerically higher conception rates compared to heifers fed EF diets (71.4% vs. 66.7%), there was no statistically significant difference. Furthermore, there were no significant differences observed among diets in terms of pregnancy outcomes, follicle size, or number. A treatment by pregnancy status interaction was detected for both PAG and P4 concentrations. These results suggest that short-term dietary starch supplementation provided around the time of breeding can result in shifts to reproductive hormone abundance that may be conducive for pregnancy establishment.

Effect of prepartum dietary energy sources on productive and reproductive performance in Nili Ravi buffaloes

Feeding of dietary energy sources has been extensively studied in dairy cows but not well described in dairy buffaloes. The objective of this study was to evaluate the effect of prepartum dietary energy sources on productive and reproductive performance in Nili Ravi buffaloes (n = 21). The buffaloes were offered isocaloric (1.55 Mcal/kg DM NEL (net energy for lactation)) glucogenic (GD), lipogenic (LD), and mixed diet (MD) during 63days prepartum and maintained (1.27 Mcal/kg DM NEL) at lactation diet (LCD) during 14weeks postpartum. Effects of dietary energy sources and week on animals were analyzed with the mixed model. The DMI, BCS, and body weights remained similar during the pre- and postpartum periods. The prepartum diets did not affect birth weight, blood metabolites, milk yield, and composition. The GD tended to early uterine involution, more follicle numbers, and early follicle formation. The prepartum feeding of dietary energy source had a similar effect on first estrus expression, days open, conception rate, pregnancy rate, and calving interval. So, it could be concluded that prepartum feeding of an isocaloric dietary energy source had a similar effect on the performance of buffaloes.

Effect of partial exchange of lactose with fat in milk replacer on performance and blood metabolites of Holstein calves

The objective of this study was to determine the effect of dietary energy source (fat vs. carbohydrate) in calf milk replacer (MR) on growth performance parameters and feed intake in rearing calves. In a randomized complete block design, 68 Holstein calves [40 females and 28 males; (mean ± SD) body weight (BW): 43.7 ± 1.43 kg] were assigned to 17 blocks of 4 calves based on birth date and parity of the dam. Within each block, calves were randomly assigned to 1 of 2 treatments: a high-lactose MR (HL; 17% fat; 44% lactose; n = 34), or a high-fat MR (HF; 23% fat; 37% lactose; n = 34). Lactose was exchanged for fat on a weight per weight basis, resulting in a 6% difference in metabolizable energy density per kilogram of MR. The feeding plan started with 6 L/d for 7 d, then 8 L/d for 35 d, 6 L/d for 7 d, and finally, 4 L/d for 7 d. Milk replacer allowances were offered in 2 meals per day at 140 g/L. Measurements included daily MR, starter and straw intakes, weekly BW, and blood metabolites, including nonesterified fatty acids (NEFA) and glucose, on wk 4, 6, 8, and 10. Increasing fat at the expense of lactose did not affect MR intake or solid feed intake during the preweaning and weaning periods. However, HF calves tended to consume more solid feed than HL calves during the postweaning period (2.63 ± 0.08 vs. 2.52 ± 0.08 kg/d). Additionally, average daily gain (HF = 0.78 ± 0.02, HL = 0.77 ± 0.02 kg/d) and final BW (HF = 98.8 ± 1.53, HL = 97.7 ± 1.57 kg) were not affected by MR composition. Nevertheless, NEFA concentration was higher in HF calves than in HL calves (0.21 ± 0.01 vs. 0.17 ± 0.01 mmol/L), and glucose concentration was higher in HF calves (6.52 ± 0.23 vs. 5.86 ± 0.23 mmol/L). Under the conditions of this study, HF calves consumed similar amounts of solid feed and grew comparably to the HL calves; however, the isonitrogenous replacement of lactose by fat had evident metabolic effects, such as increased blood NEFA and glucose concentrations.

Effect of energy source and level, animal age, and sex on the flavor profile of sheep meat.

The effects of dietary energy source, energy level, sheep age, and sheep sex on flavor and off-flavor intensity were evaluated. Consumer panelists, with previous lamb-eating experience, assessed lamb flavor and off-flavor intensity on a 100-point, end-anchored scale (0 = very mild to 100 = very intense), with off-flavor being defined as anything different than lamb flavor. Lamb longissimus thoracis (LT) and whole, boneless ground shoulder (GS) formed into patties were evaluated. Trial 1 was a randomized complete block design with a 3 × 2 factorial arrangement of treatments. Sheep age (ewe lambs, yearling ewes, and mature ewes; n = 16/age) and ad libitum access to diets [alfalfa pellets (AP) or whole-shelled corn (WSC100)] were treatments. The LT from mature ewes had a greater (P ≤ 0.02) off-flavor intensity when compared with yearling ewes and ewe lambs. Ground shoulder from sheep raised on AP had a greater lamb flavor (P ≤ 0.04) and off-flavor (P ≤ 0.04) intensity than GS from sheep consuming WSC100. Trial 2 was a randomized complete block design with a 3 × 2 × 2 factorial arrangement of treatments. Three dietary treatments [AP, WSC100, and restricted intake of whole-shelled corn to 85% of ad libitum (WSC85)], lamb sex (ewes and wethers; n = 48/sex), and lamb age [short fed, 177 ± 16.6 d of age and 93 ± 20.5 d on feed (DOF); long fed, 294 ± 7.0 d of age and 219 ± 3.8 DOF]. Flavor intensity of the LT was greater (P ≤ 0.05) from lambs offered AP when compared with lambs offered WSC85, whereas lamb flavor of the LT from lambs fed WSC100 was intermediate and not different from the lamb flavor of the LT of lambs fed AP or WSC85. The LT of long-fed lambs had a greater (P ≤ 0.01) lamb flavor and off-flavor intensity when compared with short-fed lambs. Lambs offered AP resulted in a GS with greater lamb flavor intensity (P ≤ 0.01) when compared with lambs offered WSC85 and WSC100, with no diet influence on GS off-flavor intensity. Long-fed lambs produced GS with a greater lamb flavor (P ≤ 0.01) and off-flavor (P ≤ 0.01) intensity when compared with GS from short-fed lambs. Results from the two trials indicate lamb flavor and off-flavor intensity were greater from sheep offered a high-forage (AP) diet when compared with a high-concentrate (WSC) diet. Lamb flavor intensity increased as age of the sheep at harvest increased, suggesting dietary management and associated age-related effects at harvest will influence consumer perception of lamb flavor.

Effects of dietary energy sources on early postmortem muscle metabolism of finishing pigs.

ObjectiveThis study investigated the effects of different dietary energy sources on early postmortem muscle metabolism of finishing pigs.MethodsSeventy-two barrow (Duroc×Landrace×Yorkshire, DLY) pigs (65.0±2.0 kg) were allotted to three iso-energetic and iso-nitrogenous diets: A (44.1% starch, 5.9% crude fat, and 12.6% neutral detergent fibre [NDF]), B (37.6% starch, 9.5% crude fat, and 15.4% NDF) or C (30.9% starch, 14.3% crude fat, and 17.8% NDF). After the duration of 28-day feeding experiment, 24 pigs (eight per treatment) were slaughtered and the M. longissimus lumborum (LL) samples at 45 min postmortem were collected.ResultsCompared with diet A, diet C resulted in greater adenosine triphosphate and decreased phosphocreatine (PCr) concentrations, greater activity of creatine kinase and reduced percentage bound activities of hexokinase (HK), and pyruvate kinase (PK) in LL muscles (p<0.05). Moreover, diet C decreased the phosphor-AKT level and increased the hydroxy-hypoxia-inducible factor-1α (HIF-1α) level, as well as decreased the bound protein expressions of HK II, PKM2, and lactate dehydrogenase A (p<0.05).ConclusionDiet C with the lowest level of starch and the highest levels of fat and NDF could enhance the PCr utilization and attenuate glycolysis early postmortem in LL muscle of finishing pigs.

1617 Effect of dietary energy source and level on rumen bacteria community in lactating dairy cows

1617 Effect of dietary energy source and level on rumen bacteria community in lactating dairy cows

Effect of dietary energy source on the plasma parameters of equine athletes trained in a deep water aqua treadmill

The aim of the study was to test the effect of different dietary energy sources on several blood biochemical parameters on aqua treadmill trained show jumpers. Four horses in latin square arrangements consumed identical amounts of meadow hay, and four concentrates differing mainly in their energy source (control, starch from oat, oil from sunflower and sugar from sugar beet molasses) but providing the same amount of energy. One experimental period consisted of a 10 day adaptation and 4 day test period involving deep water aqua treadmill training. Blood samples were taken during and after the last aqua treadmill training and lactate, lactate dehydrogenase, creatine kinase, aspartate aminotransferase, glucose and triglycerides levels were determined from the plasma. The different dietary energy sources resulted in similar plasma lactate levels. The increased starch content of the feed resulted in significantly lower (p < 0.05) creatine kinase level at the end of the first walking section of aqua training. This result appeared later as a tendency (p ≤ 0.1). Horses fed sunflower oil as a main energy source had higher aspartate aminotransferase level after two hours of the aqua training. The plasma triglyceride concentration in the sunflower oil group tended (p < 0.1) to be lower at the end of aqua training; while one hour after the training it was significantly lower. The elevated level of creatine kinase and aspartate aminotransferase indicates that lactate does not correctly reflect the strenuousness of the aqua training. The dietary energy source modifies the metabolic response to aqua training, even if it is not considerable.

Effect of dietary energy source and level on nutrient digestibility, rumen microbial protein synthesis, and milk performance in lactating dairy cows

This study was conducted to examine the effects of dietary energy source and level on intake, digestion, rumen microbial protein synthesis, and milk production in lactating dairy cows, using corn stover as a forage source. Eight multiparous Holstein cows, 4 of which were fitted with rumen cannulas, were evaluated in a replicated 4×4 Latin square design, with each period lasting 21 d. The cows were randomly assigned into 4 treatment groups: low-energy (LE) ground corn (GC), LE steam-flaked corn (SFC), high-energy (HE) GC, and HE SFC. Changes to ruminal energy degradation rates were induced by feeding the cows diets of either finely ground corn or SFC as components of diets with the same total energy level. Milk yield, milk protein content and yield, and milk lactose yield all increased in response to higher levels of dietary energy, whereas contents of milk fat and lactose were unaffected. Cows fed HE diets had a higher crude microbial protein yield and total-tract apparent digestibility than those receiving LE diets. Milk yield, milk protein yield, and microbial protein yield were also higher when SFC replaced GC as the main energy source for lactating cows fed LE diets. These results suggest that an increased dietary energy level and ruminal degradation rate are beneficial to milk protein production, which we suggest is due to increased yields of microbial proteins, when cows are fed corn stover as a dietary forage source.

Effects of Dietary Energy Sources on Post Mortem Glycolysis, Meat Quality and Muscle Fibre Type Transformation of Finishing Pigs.

Dietary energy source can influence muscle glycogen storage at slaughter. However, few studies have demonstrated whether the diet-induced change of muscle glycogen is achieved by the transformation of muscle fibre type. This study investigated the effects of dietary energy sources on meat quality, post mortem glycolysis and muscle fibre type transformation of finishing pigs. Seventy-two barrows with an average body weight of 65.0 ± 2.0 kg were selected and were allotted to three iso-energetic and iso-nitrogenous diets A, B or C, and each treatment consisted of three replicates (pens) of eight pigs each. Diet A contained 44.1% starch, 5.9% crude fat and 12.6% neutral detergent fiber (NDF); diet B contained 37.6% starch, 9.5% crude fat and 15.4% NDF; and diet C contained 30.9% starch, 14.3% crude fat and 17.8% NDF. The duration of the experiment was 28 days. After feed withdrawal 12 h, 24 pigs (eight per treatment) were slaughtered, samples from M. longissimus lumborum (LL) were collected for subsequent analysis. The results showed that pigs fed diet C had lesser average daily gain, average daily feed intake and back fat depth than those fed diet A (P<0.05). Diet C increased pH45min (P<0.05) and decreased drip loss (P<0.05) in LL muscles compared with diet A. Meat from pigs fed diet A showed increased contents of lactate and greater glycolytic potential (GP) compared with those fed diet C (P<0.05). Greater mRNA expression of myosin heavy-chain (MyHC)-I and IIa and lesser expression of MyHC-IIx and IIb (P<0.05) in LL muscles were found in pigs fed diet C, than in pigs fed diet A. In addition, pigs fed diet C resulted in downregulation of miR23a and upregulation of miR409 and miR208b (P<0.05), associated with conserved changes of their corresponding targets. These findings indicated that diets containing low starch and high fibre were beneficial in reducing muscle glycolysis, improving meat quality of finishing pigs. This reduction of GP may be partially associated with the improvement of oxidative fibre composition in LL muscle, and the change in myofibre type may be correlated with the change in the miRNA expression.

Effect of Dietary Energy Source on Ruminal Fermentation, Venous Blood Gases and Various Blood Metabolites of Baluchi Sheep

Aims: Present study was to determine the effects of dietary energy source diets such as glucogenic and lipogenic nutrients on ruminal fermentation characteristics, venous blood gases and concentration plasma metabolites in Baluchi sheep. Study Design: Latin square design with 3 periods (28 days). Place and Duration of Study: Department of animal science, Faculty of agriculture, Ferdowsi University of Mashhad, between March 2012 and May 2012. Methodology: Experimental diets were a glucogenic, a lipogenic or a mixture of glucogenic and lipogenic diets (50:50). The animals were fed diets consisted of 50% chopped alfalfa hay and 50% concentrate. Ruminal fluid samples were collected before the feeding until 8 hour post feeding at day 24 of the each experimental period. Blood samples were taken from jugular vein before the feeding, 2, 4 and 6 h post feeding at day 26 of each period. In order to determine venous blood gases and pH, jugular blood samples were collected using heparinized syringes before and 4 h after feeding on day 27. Results: Results indicated that glucose and insulin concentration was decreased in sheep consume lipogenic diet (P 0.05). Conclusion: Feeding the mixture of glucogenic and lipogenic diets (50:50) improved Original Research Article Annual Research & Review in Biology, 4(2): 451-459, 2014 452 plasma glucose and insulin concentration, while ruminal and blood pH were not altered. This phenomenon indicates the potent synergistic beneficial effect of mixed diet to supply energy source.

Effect of dietary energy source on deposition and fatty acid synthesis in the liver of the laying hen

1. This experiment was conducted to determine the effect of different dietary energy sources on hepatic lipid deposition and fatty acid synthesis in the layer's liver. 2. A total of 120 Lohmann Pink commercial layers were divided into three groups of 40 birds each and restricted-fed so that they had similar metabolisable energy intakes. Experimental diets were prepared as follows: (1) maize-soybean meal basal diet (CS) fed at 108 g/d, (2) soybean isolated protein plus lard diet (SL) fed at 63 g/d, (3) soybean isolated protein plus maize starch diet (SC) fed at 94·4 g/d. All feed intakes were limited so that the birds consumed similar quantities of the major nutrient daily; all the birds were fed 4 times/d. 3. Compared with chicks fed on the CS and SC, hepatic EE (ether extraction) and triglyceride of the SL group were increased significantly and the total of cholesterol and phospholipids was increased. However, there were no significant reductions in plasma VLDL and ApoB100 concentrations. 4. The birds fed on the maize starch diets up-regulated srebp-1c and chrebp mRNA transcription levels significantly. The maize starch diet also increased the activity of acetyl CoA carboxylase (ACC) and fatty acid synthase (FAS) significantly. However, the lard diet led to a decrease of ACC activity, but had no significant effect on FAS. 5. These results showed that dietary carbohydrates can induce hepatic lipid deposition by increasing the ACC and FAS activities and up-regulating the srebp-1c and chrebp mRNA transcription levels in the layer's liver much more readily than dietary fat, and layers fed on high carbohydrate diets tend to have more fatty livers.

Effect of feed withdrawal and dietary energy source on muscle glycolytic potential and blood acid-base responses to handling in slaughter-weight pigs1

The effects of dietary energy source and feed withdrawal on muscle glycolytic potential (GP) and blood acid-base responses to handling were investigated in slaughter-weight pigs (initial BW 94.7 ± 1.01 kg). Crossbred pigs (n = 96; 48 barrows, 48 gilts) were used in a randomized complete block design with a 4 × 2 × 2 factorial arrangement of treatments: l) diet [control, high fat (10% supplemental fat), low-digestible carbohydrate (20% total starch), and high-fat/low-digestible carbohydrate (10% supplemental fat and 20% total starch)]; 2) feed withdrawal (0 and 36 h); and 3) sex (barrow and gilt). Diets were fed for 28 d before the feed withdrawal treatment was applied, at the end of which all pigs were individually moved through a 12.20-m-long × 0.91-m-wide passageway for 16 laps (195 m total distance), with the assistance of an electric goad (2 times per lap). Longissimus muscle biopsies were collected at the beginning of the feeding and feed withdrawal periods and immediately after and 4 h after the handling procedure. Venous blood was collected 2 h before and immediately after the handling procedure to measure acid-base responses. At the end of the feeding period, pigs fed the control and high-fat diets were heavier (P < 0.001) than those on the low-digestible carbohydrate and the high-fat/low-digestible carbohydrate diets (129.8, 130.9, 114.0, and 122.1 kg, respectively; SEM 1.91). Diet, feed withdrawal, and sex did not affect (P > 0.05) blood acid-base responses to handling. Muscle GP at the end of the feeding period and 4 h posthandling was least (P < 0.05) for pigs fed the high-fat diet and similar for the other 3 diet treatments. Pigs subjected to 36 h compared with 0 h of feed withdrawal had less GP (P < 0.05) immediately after and 4 h after the handling procedure. There was an interaction between diet and feed withdrawal treatments for changes in GP from the start of feed withdrawal to 4 h posthandling. The reduction in GP was greater (P < 0.05) for fasted than for fed pigs receiving the control and high-fat diets, but was similar (P > 0.05) for fasted and fed pigs receiving the 2 low-digestible carbohydrate diets. In conclusion, neither dietary energy source nor fasting affected blood acid-base responses to handling; however, fasting-induced changes in LM GP were diet dependent.

Dietary energy source and physical conditioning affect insulin sensitivity and skeletal muscle glucose metabolism in horses

Starch rich (S) feeds reduce insulin sensitivity in untrained horses when compared to high fat (F) feeds, but insulin sensitivity is not affected when S or F are fed during exercise training. The effects of S vs. F on training-associated alterations in skeletal muscle glucose metabolism are unknown. To determine the effects of dietary energy source on training-associated changes in insulin sensitivity, skeletal muscle GLUT4 protein and hexokinase (HK) and glycogen synthase (GS) activities in horses. After a baseline period on an all forage diet (Phase 1), horses were adapted to high starch (S) or high fat (F) diets (n = 7/group) for 6 weeks (Phase 2) and then completed 7 weeks of exercise training (Phase 3) on the same diets. To measure insulin sensitivity (SI), minimal model analysis of a frequently-sampled i.v. glucose tolerance test was performed at the end of each phase. Middle gluteal muscle biopsies to measure GLUT-4 protein content, muscle glycogen and HK and GS activities were taken before and after euglycaemic-hyperinsulinaemic clamps administered after each phase. Data were analysed by repeated measures ANOVA. In S, SI was 36% lower (P < 0.05) after Phase 2 when compared to Phase 1 but was unchanged in F. After Phase 3, SI was increased (P < 0.01) in S and F compared to Phase 2 and did not differ (P > 0.05) between diets. Middle gluteal muscle GLUT-4 protein and post clamp HK activity were increased (P < 0.05) in S after Phase 3, with higher (P < 0.01) GLUT4 in S than in F. GS activities were unchanged in both diets. Adaptation to S resulted in decreased SI mitigated by moderate physical conditioning. Increased GLUT-4 protein content and HK activity in S may have contributed to higher SI after training.

The effect of dietary energy source on performance and nutrient digestibility in growing pigs

The effect of dietary energy source on performance and nutrient digestibility in growing pigs

Dietary energy source and feeding levels during the rearing period affect ovarian follicular development and oocyte maturation in gilts

Fifty-four Landrace × Yorkshire gilts (59.0 ± 4.2 kg and 147 ± 3 d old) were used to examine the effects of dietary energy source (starch or mixed fat) at high [112.5% of energy requirements recommended by NRC (1998)], normal (100%), and low (87.5%) energy feeding levels on ovarian follicular development and oocyte maturation. Forty-seven estrus gilts were slaughtered at Day 19 after the second estrus; oocytes were recovered from follicles >4 mm in diameter, and matured in vitro for 44 h. Gilts fed high-energy diets had more follicles >4 mm (mean, 25.8 vs. 19.1, P < 0.05) and more oocytes that reached metaphase II (80.3 vs. 64.0%, P < 0.05) than those fed the low-energy diet. Furthermore, gilts fed starch-rich diets had enhanced oocyte nuclear maturation relative to those fed fat-rich diets (75.4 vs. 68.0%, P < 0.05). Compared to the lower-energy feeding groups, high-energy feeding groups had higher ( P < 0.05) blood concentrations of postprandial insulin (1562.4 vs. 990.0 ng/4 h), IGF-I (321.2 vs. 256.9 ng/mL), and LH pulses (2.7 vs. 1.4 pulses/6 h). Follicular fluid concentrations of IGF-I (198.5 vs. 143.1 ng/mL) and estradiol (152.6 vs. 124.8 ng/mL) were higher ( P < 0.05) in the high-energy group than in the normal group. Compared with gilts fed the high-energy diet supplemented with fat, gilts fed the high-energy diet supplemented with starch had a tendency ( P < 0.10) towards increased IGF-I concentration in both blood and follicular fluid, and improved oocyte nuclear maturation during culture in vitro. We inferred that starch-rich, high-energy diets during rearing may improve ovarian follicular development and oocyte maturation in replacement gilts.

Insulin Sensitivity in Thoroughbred Geldings: Effect of Weight Gain, Diet, and Exercise on Insulin Sensitivity in Thoroughbred Geldings

The effects of dietary energy source, controlled weight gain, and exercise restriction on insulin sensitivity (SI) were studied in mature Thoroughbred geldings with body condition scores (BCS) of 4.3 ± 0.1. Two dietary energy sources were used, one high in starch and sugar (HS; n = 9) and one high in fat and fiber (HF; n = 7), and horses were fed 20 Mcal digestible energy (DE)/day above maintenance requirements to encourage weight gain. Using the minimal model of glucose and insulin dynamics, no differences in SI between groups were noted before initiation of treatment concentrate feeding. After dietary acclimation, SI was decreased in HS ( P < 0.01) as compared with HF. After 32 weeks of controlled weight gain (90.8 kg; final BCS, 7.0 ± 0.1), SI remained lower in HS ( P = 0.07) but did not change from the preweight gain value. SI in HF did not change between the start and end of weight gain. After completion of weight gain, exercise was restricted for 2 weeks, resulting in a reduction in SI in HF ( P = 0.03) but no change in HS. It was concluded that dietary energy source may be more influential than weight gain on SI in the mature Thoroughbred gelding between BCS 4 and 7. The higher SI found in horses consuming the HF diet appeared to be partially dependent on some level of physical activity.

Effects of dietary energy source and level and injection of tilmicosin phosphate on immune function in lipopolysaccharide-challenged beef steers1,2

Twenty-four Angus x Hereford crossbred steers (247 kg BW; SE = 2.4 kg) were used in a completely random design to evaluate the effect of energy source and level with or without antibiotic administration on measures of immune function. Steers were fed 1 of 3 dietary treatments: a 70% concentrate diet ad libitum (70AL), a 30% concentrate diet ad libitum (30AL), and a 70% concentrate diet offered in an amount calculated to provide NE(g) intake equal to the 30AL treatment (70RES). Half the steers in each dietary treatment received a s.c. injection of tilmicosin phosphate (ANTI; 1 mL/30 kg of BW); the other half received an equal volume of saline s.c. (SAL). Steers were offered the treatment diets for 28 d before and were administered the ANTI or SAL injections 2 d before indwelling catheters were placed in the jugular vein and 2.0 microg/kg of BW of Escherichia coli lipopolysaccharide (LPS) was administered i.v. Blood serum was collected at 30-min intervals from -2 to 6 h and at 8, 12, 24, 48, and 72 h relative to the LPS challenge. Increased energy intake (70AL) increased (P < or = 0.04) DMI, ADG, and rectal temperature (RT) after the challenge compared with the 70RES treatment. The 30AL treatment increased the maximum concentrations and area under the response curve of the proinflammatory cytokines (PIC) interferon-gamma, tumor necrosis factor-alpha, and IL-6 (P < or = 0.05) compared with the average of the 70AL and 70RES treatments. Decreased energy intake (70RES vs. 70AL) increased IL-6 (P < or = 0.003) but did not significantly increase interferon-gamma and tumor necrosis factor-alpha (P > or = 0.14) after LPS administration. Tilmicosin administration decreased the time to attain maximal RT (P = 0.01) by 1 h without altering the peak RT (P = 0.85), and tilmicosin interacted with energy intake to increase prechallenge PIC in 70RES vs. 70AL (P < or = 0.05). Results indicate that increased PIC response, presumably resulting from a combination of decreased energy intake and from direct effects of roughage, may be a mode of action for the slight decrease in morbidity that often occurs when newly received, stressed calves are fed roughage-based receiving diets. Tilmicosin phosphate might have immunomodulatory capacity beyond its direct effects on pathogenic bacteria, and these effects could interact with dietary energy intake in cattle.

Effect of dietary energy sources on growth performance, nutrient digestibility and carcass characteristics of rabbits

Effect of dietary energy sources on growth performance, nutrient digestibility and carcass characteristics of rabbits

Effects of dietary energy source on energy balance, metabolites and reproduction variables in dairy cows in early lactation

This paper summarizes three recent studies by the same authors with the objective to study the effect of dietary energy source on the energy balance (EB) and risk for metabolic and reproductive disorders in dairy cows in early lactation. The first study, a literature survey, illustrated that feeding extra glucogenic nutrients relative to lipogenic nutrients, decreased milk fat and seems to decrease plasma non-esterified fatty acid (NEFA) and β-hydroxybutyrate (BHBA) concentration. However studies are scarce and mostly confound the effect of energy source with level of energy intake, compromising eventual effects on EB and fertility. Therefore, in the second study, 16 dairy cows were either fed a glucogenic or a lipogenic diet (isocaloric) and EB was determined in climate-controlled respiration chambers from week 2 until 9 of lactation. Glucogenic diet decreased milk fat yield and milk energy and tended to decrease body fat mobilization compared with lipogenic diet. The objective of the third study was to study the effect of dietary energy source on EB, metabolites and reproduction variables. Dairy cows ( n = 111) were fed glucogenic, lipogenic or mixed diet from week 3 until week 9 relative to calving. Multiparous cows fed glucogenic diet had lower milk fat yield, higher calculated EB, and lower plasma NEFA, BHBA and liver triacylglyceride concentration and tended to have fewer days to first postpartum ovulation. In conclusion, increasing the glucogenic nutrient availability improved the EB and had potential to reduce the risk for metabolic disorders and to improve reproductive performance in dairy cows.

Glucose kinetics in trained Arabian geldings: effects of dietary energy source and endurance exercise

Glucose kinetics in trained Arabian geldings: effects of dietary energy source and endurance exercise