Effects Of Dietary Energy Levels Research Articles

Effects of dietary energy levels on microorganisms and short-chain fatty acids of rumen and tight junction proteins in Honghe Yellow cattle.

This study was conducted to investigate the effects of dietary energy levels on microorganisms and short-chain fatty acids (SCFAs) of rumen and the expression of tight junction proteins in Honghe Yellow cattle. A total of fifteen male Honghe Yellow cattle were randomly divided into three treatments (five replicates per treatment), consisting of formulated energy concentrations of 5.90 MJ/kg (high-energy diet, group H), 5.60 MJ/kg (medium-energy diet, group M) and 5.30 MJ/kg (low-energy diet, group L). The results showed that compared with group H, the expression of Claudin-1 in rumen epithelium of groups M and L was increased, but the expression of ZO-1 was decreased (p < 0.05). Moreover, compared with group H, group M down-regulated the expression of Occludin and Claudin-1 in the brain (p < 0.05). For rumen bacteria, the dominant phyla included Bacteroidetes and Firmicutes, the abundance of Actinobacteriota in groups M and L was significantly increased compared with group H (p < 0.05). At the genus level, the relative abundance of Corynebacterium, Eubacterium_nodatum_group and Neisseraceae in groups M and L was significantly decreased compared with group H (p < 0.05). For rumen fungi, the dominant phyla included Basidiomycota, Ascomycota and Neocariastigomycota, the relative abundance of Ascomycetes was significantly higher than that of groups M and L compared with group H (p < 0.05). At the genus level, the relative abundance of Neocelimastigaceae and Myceliophthora in groups M and L was significantly reduced compared with group H (p < 0.05). Furthermore, the expression of Claudin-1 in rumen epithelium was significantly positively correlated with Actinobacteriota, Corynebacterium and Neisseriaceae. The expression of ZO-1 in the spinal cord was significantly positively correlated with Myceliophthora. The expression of Occludin in brain was positively correlated with valerate content (p < 0.05). In summary, dietary energy levels affected the rumen microbiota of Honghe Yellow cattle. The expression of Claudin-1 in rumen epithelium and the total SCFAs concentration were increased with decreasing dietary energy levels, but the expression of Claudin-1 in brain and ZO-1 in the spinal cord were reduced with decreasing dietary energy levels. Meanwhile, the rumen microbiota and SCFAs were significantly correlated with the expression of TJP.

Effects of dietary energy level on antioxidant capability, immune function and rectal microbiota in late gestation donkeys.

This study investigated the effects of dietary energy level on the antioxidant capability, immune function, and rectal microbiota in donkey jennets during the last 60 days of gestation. Fifteen pregnant DeZhou donkeys with age of 6.0 ± 0.1 years, body weight of 292 ± 33 kg, parity of 2.7 ± 0.1 parities and similar expected date of confinement (74 ± 4 days) were randomly allocated to three groups and feed three diets: high energy (10.92 MJ/kg, H), medium energy (10.49 MJ/kg, M), and low energy (9.94 MJ/kg, L). The serum activity of catalase (CAT), total superoxide dismutase (T-SOD), glutathione peroxidase (GSH-Px), and total antioxidant capacity (T-AOC) in group M was significantly higher, whereas the concentrations of malondialdehyde (MDA), interleukin 1 (IL-1), IL-2, and IL-6 were lower than those recorded for groups H and L (p ≤ 0.05). The dietary energy level significantly affected rectal microbial community structure in the jennet donkeys 35 days and 7 days before the parturition (p ≤ 0.05). The abundances of norank_f_norank_o_Coriobacteriales genus was significantly higher (p ≤ 0.05) in group H, and the abundances of norank_f_norank_o_Mollicutes_RF39 and the Candidatus_Saccharimonas were higher in group L (p ≤ 0.05). The abundance of Fibrobacter in group M was significantly increased (p ≤ 0.05). The abundance of norank_f_norank_o_Coriobacteriales was positively correlated with average daily gain (ADG) and tumor necrosis factor-α (TNF-α) concentrations (p ≤ 0.05). The abundance of norank_f_norank_o_Mollicutes_RF39 was positively correlated with IL-2 and IL-6 concentrations. The abundance of Candidatus_Saccharimonas was positively correlated with CAT, T-SOD and GSH-Px activities (p ≤ 0.05). The abundance of Fibrobacter was positively correlated with CAT and T-SOD activities (p ≤ 0.05), but negatively correlated with IL-2 concentration (p ≤ 0.05). In conclusion, an appropriate dietary with an energy content of 10.49 MJ/kg for jennet donkeys during late gestation increased the prenatal antioxidant capacity, reduced inflammatory cytokines, and promoted fetal growth, and these changes were related to diet-induced changes in rectal microbiota compositions.

Multi-omics revealed the effects of dietary energy levels on the rumen microbiota and metabolites in yaks under house-feeding conditions.

Yak (Bos grunniens) is a unique large ruminant species in the Qinghai-Tibetan Plateau (QTP). Changing the energy levels of their rations can significantly improve their growth performance. Therefore, studying the effects of dietary energy levels on the rumen microflora and metabolites of yak is crucial for enhancing the development of the yak industry. Currently, there is a lack of understanding regarding the impact of feeding energy diets on rumen fermentation parameters, microbial functions, and metabolites. This study was designed to determine the appropriate energy level for feeding yak. Three test diets with metabolizable energy levels of 7.57 MJ/kg, 9.44 MJ/kg, and 11.9 MJ/kg were used and the concentration of volatile fatty acids (VFA) in rumen fluid was measured. The microbial communities, functions, and metabolites in yaks were studied by 16S rRNA sequencing, metagenome, and LC-MS non-targeted metabolomics to investigate the relationships among rumen fermentation parameters, microbial diversity, and metabolites. Ration energy levels significantly affect total VFA, acetate, propionate, butyrate, iso-valerate, valerate, and acetate/propionate (p < 0.05). At the phylum level, the dominant phyla in all three treatment groups were Bacteroidota, Firmicutes, and Actinobacteriota. At the genus level, the abundance of the unclassified_o__Bacteroidales, norank_f_Muribaculaceae, Lachnospiraceae_NK4A136_group, and Family _XIII_AD3011_group showed significant differences (p < 0.05) and were significantly correlated with differential metabolites screened for phosphatidylcholine [PC(16:0/0:0), PC(18:3/0:0)], uridine 3'-monophosphate, and adenosine monophosphate, etc. CAZymes family analysis showed that GHs and CEs differed significantly among the three groups. In addition, differential metabolites were mainly enriched in the pathways of lipid metabolism, nucleotide metabolism, and biosynthesis of other secondary metabolites, and the concentrations of differential metabolites were correlated with microbial abundance. In summary, this study analyzed the effects of ration energy levels on rumen microorganisms and metabolites of yaks and their relationships. The results provided a scientific basis for the selection of dietary energy for yaks in the house feeding period in the future.

Effect of dietary energy levels in Hy-Line Brown laying Hens during the last production phase

Diets with 2800 and 2900 kcal of ME/kg was evaluated to determine their effect on weight gain and egg quality parameters at the end of the production cycle in hy-Line Brown hens separated into two weight groups weights: &lt;2200g and&gt; 2200 g. A group of 960 hens with 75 weeks of age was employed distributed in a Random Complete Blocks Design with a bifactorial arrangement. Data were analyzed by analysis of variance and for the comparison of treatment means, the Duncan Significant Minimum Range test was used at a &lt;0.05 and &lt;0.01 probability both for the independent factors and for the bird weight interaction and diet energy level. Data about consumption, egg production, feed conversion and abdominal fat were collected. Egg quality was determined by weight records, albumen height, color, freshness, resistance, and thickness by using the digital method with laser irradiation in the digital Egg Tester DET-600. The results showed effects on hens weight upon consumption and weekly weights, lighter hens consumed less and resulted in lower weekly weights compared to heavier hens (P &lt;0, 01), however, cumulative weight gain was not affected by the hen weight factor and energy level of diets (P&gt; 0, 005). Heavier birds accumulated more abdominal fat at the end of the laying period than the less heavy birds (P &lt;0.01). Egg production and feed conversion did not suffer variations due to the effect of both factors, although egg weight was affected only by bird weight (P &lt;0.01). On the other hand, egg color shows variations depending on the energy level of the diet; while the freshness, resistance and thickness of the egg were not affected by any study factor (P&gt; 0.05). it would be feasible to reduce the energy value of the diet without affecting the productive performance of the birds.

Physiological role of dietary energy in the sexual maturity: clues of body size, gonad development, and serum biochemical parameters of Chinese indigenous chicken

Sexual maturity is a crucial factor in the formation and development of poultry reproductive capacity. The nutritional status has been confirmed to play an important role in the regulation of sexual maturity. To investigate the effect of dietary energy levels on sexual maturity in chicken, diets with 3 energy levels (group L: 2,573 kcal/kg, group C: 2,836 kcal/kg, group H: 3,122 kcal/kg) were implemented to feed Guangyuan Gray chickens. During this trial, body weight, body size, organ development, sexual maturity, reproductive performance and blood biochemical parameters were monitored. The earlier sexual maturity was observed in group H, as well as a heavier first egg weight, larger interpubic distance and higher total cholesterol (T-CHO) content at sexual maturity. The dietary energy levels had no significant effect on body weight at first egg and egg production at 300 d of age. Although dietary energy levels had a significant effect on body weight, comb length, tibia length and girth, abdominal fat weight, oviduct weight and length, T-CHO, triglyceride (TG) content and estradiol (E2) level during the rearing period. No significant difference of gonadotropin releasing hormone (GnRH) and luteinizing hormone (LH) level among 3 groups was observed during the trial. The dietary energy levels had effects on mRNA expression of GnRH, estrogen receptor 1 (ESR1), estrogen receptor 2 (ESR2) in hypothalamus, gonadotropin inhibitory hormone receptor (GnIHR) in pituitary and luteinizing hormone receptor (LHR), ESR2 in ovary. The GnIHR/GnRHR ratio in pituitary was higher before sexual maturity and decreased at sexual maturity. The results of correlations analysis found that all the body size, carcass traits, serum biochemical parameters negatively correlated with age at first egg except for interpubic distance and serum blood glucose content. Collectively, dietary energy levels had effects on sexual maturity of chicken, which may be achieved by affecting body weight, gonad development, endocrine and the mRNA expression of genes related to hypothalamus-pituitary-gonad axis. These results further set our understanding of how dietary energy regulates sexual maturity.

Effects of Different Dietary Energy Levels on Development, Quality of Carcass and Meat, and Fatty Acid Profile in Male Lambs.

This experiment was conducted to study the effects of dietary energy level on the growth performance and meat quality of weaned Alpine Merino lambs. The study ran for a total of 104 days (20-day pretrial, 84-day trial). From three groups of test lambs, we randomly selected ten lambs per group to determine slaughter performance, meat quality characteristics, and organ indexes. The slaughter performances of the lambs improved as the dietary energy level increased. The live weight before the slaughter of the lambs was significantly higher in the high group than in the low and medium groups. The carcass weight was significantly higher in the high group than in the low group. Dietary energy level had little effect on the organ weight of lambs. Meat quality differed among the three dietary energy levels. The muscle yellowness and redness scores decreased significantly as the energy levels increased. The C18:0, C21:0, C20:1, C18:2n6c, and C20:2 contents in the muscle were significantly higher in the high group than in the medium and low groups. The C18:3n6 content in the muscle was significantly higher in the low group than in the medium group. The C20:5n3 content in the longissimus dorsi was significantly higher in the high group than in the medium and low groups. The monounsaturated and unsaturated fatty acid contents in the muscle were significantly higher in the high group than in the low group. A dietary energy level of 10.5 MJ/kg is suitable for fattening weaned male Alpine Merino lambs.

Effects of different energy levels and two levels of temperature–humidity indices on growth, blood metabolites, and stress biomarkers in Korean native calves

This study investigated the effects of dietary energy levels on growth, blood metabolites, and stress biomarkers in Korean native calves subjected to heat stress (HS). Twenty-four calves (BW: 221.5 ± 24.9 kg; age: 162 ± 4.8 d) were randomly housed in climate-controlled chambers using 3 × 2 factorial design. There were three treatment groups including low energy (LE = 2.53), medium energy (ME = 2.63), and high energy levels (HE = 2.72 Mcal/kg of DM) and two stress levels (threshold: THI = 70–73; severe: THI = 89–91). The calves were adapted to 22 °C for 7 days, then to the target THI level for 14 days. Energy intake, average daily gain, and gain to feed ratio were determined to decline (p < 0.05) under severe HS compared with threshold. Under severe HS, rectal temperature was increased 0.67 °C compared with threshold. Severe HS increased glycine, ammonia, and 3-methylhistidine concentrations compared with threshold (p < 0.05). Gluconeogenic AAs in the blood were increased among the various energy levels regardless of HS. In PBMCs the expression of HSP70 gene was increased in the LE group (p < 0.05), and the HSP90 gene expression was increased in LE and ME groups (p < 0.05) under severe HS. However, the expression of genes HSP70 and HSP90 in HE group did not differ under severe HS (p > 0.05). It has been suggested that HE intake may have a beneficial effect on PBMCs by mitigating ATP depletion. No differences in growth performance were found when increasing energy intake with high protein (CP 17.5%) under HS. However, the increase in energy levels resulted in increased gluconeogenic AAs but decreased urea and 3-methylhistidine in blood. In conclusion, increased energy levels are thought to improve HS adaptability by inhibiting muscle degradation and glucose production using gluconeogenic AAs in Korea native calves under HS condition.

High energy diet of beef cows during gestation promoted growth performance of calves by improving placental nutrients transport.

The aim of this study was to explore the effects of dietary energy level during gestation on growth performance and serum parameters in offspring using beef cattle as research objects. Additionally, the gene expressions associated with nutrients transport in the placenta were evaluated. Eighteen Simmental crossbred cows (body weight = 338.44 ± 16.03 kg and 760 ± 6 days of age) were randomly assigned to 3 dietary treatment groups: low energy (LE, metabolic energy = 8.76 MJ/kg), medium (ME, 9.47 MJ/kg) and high (HE, 10.18 MJ/kg). The dietary treatments were introduced from day 45 before expected date of parturition. The pre-experiment lasted for 15 days and formal experiment lasted for 30 days. Growth performance data and blood samples of calves were collected at birth and day 30 post-birth. The placental tissue was collected at parturition. The results indicated that the birth weight and average daily gain of calves in HE group were higher (P < 0.05) than those in LE group. After parturition, the serum contents of glucose, total protein, cortisol and leptin in neonatal calves were significantly increased (P < 0.05) with the elevation of dietary energy levels. At 30 days postpartum, the glucose, glutathione peroxidase, growth hormone, insulin-like growth factor 1 and leptin concentrations of HE group were significantly increased (P < 0.05) as compared with LE group, while the serum amyloid protein A displayed an opposite trend between two groups. With the increase of dietary energy concentration, placental mRNA expressions of vascular endothelial growth factor A, glucose transporter 1 and 3 were significantly up-regulated (P < 0.05). Furthermore, the amino acid transporter solute carrier family 38 member 1, hydroxysteroid 11-beta dehydrogenase 2, insulin-like growth factor 1 and 2 mRNA expressions of HE group were higher (P < 0.05) than those of LE and ME groups. In conclusion, the improved growth performance of calves from the high energy ration supplemented beef cows may be attributed to the increased placental nutrients transport, which may lead to the increased nutrient supply to the fetus.

The effect of dietary energy levels on the sexual puberty of ram lambs

Aim of study: To evaluate the effect of different feeding levels on body weight changes, sexual behavior activities, and spermatogenesis characteristics of testis tissue in immature Iranian breed lambs.&#x0D; Area of study: University of Tabriz, Iran.&#x0D; Material and methods: A total of 40 (start of experiment, 4; after 6 months, 12; 9 months, 12; sexual behavior, 12) two-month-old immature ram lambs were divided into three equal groups and were fed for eight months with three different concentrate mixtures formulated using conventional ingredients based on barley grain. Lambs received the same amount of crude protein with three levels of energy. The diet of the low-energy (LE) group had an energy of 10% lower than the control group, which received a diet with optimum energy of 100% according to the NRC. Lambs in the high-energy (HE) group were fed diets with an energy of 10% higher than the optimum energy group. In each group, four lambs were castrated in three steps, including the ages of 2 (start of treatment), 6, and 9 months. Body weight and scrotal circumference were recorded monthly. Sexual behaviors toward estrus ewes were evaluated for 30 min, and the testes were analyzed histologically.&#x0D; Main results: The lambs in the LE group had lower body weight and smaller scrotal circumference than HE group (p&lt;0.05). Sexual behaviors in the HE group occurred at an earlier age, such as mount and mounts with ejaculation, as the external presentations of puberty (p&lt;0.05). &#x0D; Research highlights: Underfeeding of pre-pubertal animals delayed puberty, while high-plane feeding advanced puberty.

Effect of Prepartum Dietary Energy Level on Production and Reproduction in Nili Ravi Buffaloes.

Simple SummaryThe objective was to evaluate the effect of prepartum dietary energy level on performance of Nili Ravi buffaloes. Buffaloes were fed low, medium or high energy diet during 63 days prepartum and same lactation diet during 14 weeks postpartum. Buffaloes fed the high energy diet had better performance compared with buffaloes fed the medium or low energy diet. While, prepartum feeding of low energy diet adversely affected buffalo performance.The objective of this study was to evaluate the effect of prepartum dietary energy level on postpartum production and reproduction in Nili Ravi buffaloes (n = 21). The buffaloes were offered low energy (LE: 1.31 Mcal/kg DM NEL (net energy for lactation)), medium energy (ME: 1.42 Mcal/kg DM NEL) or high energy (HE: 1.54 Mcal/kg DM NEL) diet for 63 days prepartum, and received the same lactation diet (LD: 1.22 Mcal/kg DM NEL) during 14 weeks postpartum. The effects of dietary energy level and week were analyzed with Proc GLIMMIX model. Dry matter intake (DMI) was lower in buffaloes fed the LE diet compared with buffaloes fed the ME or HE diet. Calf birth weight (CBW) was higher in buffaloes fed the HE diet compared with buffaloes fed the ME or LE diet. Milk production was similar in buffaloes fed the HE, ME or LE diet within 14 weeks postpartum and throughout the lactation. Milk fat was higher in buffaloes fed the LE diet compared with buffaloes fed the ME or HE diet. Milk protein and lactose yields was high in buffaloes fed the HE diet compared with buffaloes fed the ME or LE diet. Body condition score was high in HE and was affected by diet × week interactions during pre and postpartum period. The concentrations of β-hydroxybutyrate (BHBA) and triglycerides in serum was lowest in buffaloes fed the HE diet compared with the buffaloes fed the ME or LE diet. The buffaloes fed the HE diet had early uterine involution (UI), first estrus, short dry days, and calving interval (CI) compared with buffaloes fed the ME or LE diet. None of buffaloes fed the LE diet exhibited estrus during the first 14 weeks postpartum compared with buffaloes fed the ME or HE diet. In conclusion, prepartum feeding of high energy diet can be helpful in improving the postpartum productive and reproductive performance in Nili Ravi buffaloes.

Effect of grower dietary energy level on feed intake and performance of modern broiler chickens

An experiment was carriedout to investigate the effect of dietary energy level levels on feed intake of modern broiler chickens during the growth period. A total of 160 Ross broiler chicks (mixed-sex) in a completely randomized design with 4 treatments and 4 replicates (10 birds) were used. The chicks were fed from 11 to 24 days of age with dietary treatments, including 4 grower diets with 2800, 2900, 3000, and 3100 kcal/kg ME and constant nutrient to ME ratios. All chicks were fed the recommended Ross diet during starter (1- 10 days) and finisher (25- 42 days) periods. At the end of experimentperiod (42 days), growth performance and carcass characteristics were measured.The results showed that the energy level had no significant effect on the average daily feed intake for the grower period, but the grower's dietary energy level had a significant effect on daily body weight gain and feed conversion ratio.Also, there was no significant difference in final live weight and relative carcass yield at the end of theexperimentalperiod. In conclusion, during the growing period, modern broiler chicks consume feed regardless of the energy level of the diet and continue up to physical satiety.

Comparison of the meat quality and fatty acid profile of muscles in finishing Xiangcun Black pigs fed varied dietary energy levels.

To study the effects of dietary energy level on the meat quality of different muscles in finishing pigs, 400 Xiangcun Black pigs (BW = 79.55 ± 4.77 kg) were randomly assigned to 5 treatments with varied calculated digestive energy (DE) at 3,050, 3,100, 3,150, 3,200 and 3,250 kcal/kg, respectively. Each treatment had 8 replicates with 10 pigs per replicate. Meat quality, amino acid and fatty acid composition were tested in this study. No differences in average daily gain, average daily feed intake or feed-to-gain ratio (P > 0.05) were observed among dietary treatments. Glycogen concentrations of longissimus dorsi (LD) muscle in DE3150 was higher than those in other groups (P < 0.05). The crude fat concentration of biceps femoris (BF) muscle in DE3250 tended to be higher than that in DE3150 and DE3100 groups (P < 0.05). Pigs in DE3250 and DE3200 had higher fiber density and smaller cross-sectional area of BF muscle than those in DE3150 (P < 0.05). Pigs in DE3150 had the highest Cu concentration in LD muscle compared with those in DE3200, DE3250 (P < 0.05). The C16:1 proportion of LD muscle was lower (P < 0.01) and C20:1 was higher (P < 0.05) in DE3050 than that in the other dietary treatments. The C18:3n6 and C20:3n6 proportions of BF muscle in DE3150 were higher than those in DE 3050, DE3200 and DE3250 (P < 0.05). For LD muscle, mRNA expressions of type I and IIa MyHC in group DE3150 were higher than other treatments (P < 0.01). The LD muscle in DE3150 expressed higher PPARd than in other groups (P < 0.01). Pigs in DE3100 expressed higher FOX1 than in DE3200 and DE3250 (P < 0.05). Sterol-regulatory element binding proteins (SREBPa) mRNA expression decreased linearly when dietary energy level increased in BF muscle (P < 0.01). In conclusion, a 200 kcal/kg decrease in digestible energy for 4 consecutive weeks did not affect growth performance of Xiangcun Black pigs. Furthermore, LD and BF muscle respond differently to dietary energy level, and meat quality was improved by the medium energy level during the finishing phase.

Dietary energy influences ovarian morphology and in vitro maturation of oocytes in goats

ABSTRACT The present study aimed to determine the effects of dietary energy levels on follicular development and in vitro maturation of oocytes in pre-pubertal goats. Thirty-six female six-month-old stall-fed Black Bengal goats were divided into three equal groups that were randomly assigned to receive three iso-nitrogenous diets containing different levels of metabolizable energy (8.67, 10.20, and 11.73 MJ/kg DM). After 150 days of rearing, the weight, length and width of the ovaries increased significantly in medium and high levels of dietary energy groups than in the low-energy group. Medium and high-energy levels in the diet significantly increased the number of visible antral follicles and large antral follicles than the low level of dietary energy. The number of antral follicles per ovary was higher in high-energy fed goats than medium- and low-energy groups. The low-energy group showed more non-growing primordial follicles and degenerated follicles than the other groups. The medium- and high-dietary energy levels significantly increased the maturation rate of oocytes to metaphase II than the low-energy group. These results reveal that the level of dietary energy positively influences follicular development and meiotic competence of goat oocytes.

Effect of dietary energy level in finishing phase on performance, carcass and meat quality in immunocastrates and barrows in comparison with gilts and entire male pigs

Immunocastration, a technique consisting of two vaccinations against gonadotropin-releasing hormone (GnRH), can be used as alternative to surgical castration of piglets. It reduces boar taint and allows higher economic and ecological efficiency compared to barrows. The feeding strategy of immunocastrates, however, can still be improved. After second vaccination, when immunisation becomes fully effective, feed intake of immunocastrates increases sharply. This study aimed to investigate whether energy intake of immunocastrates after second vaccination could be reduced by lowering the dietary energy level of the finishing phase, without negatively affecting animal performance and quality of pork production. We hypothesised that immunocastrates already reach their limits in voluntary feed intake after second vaccination, and therefore would not be able to compensate the lower dietary energy level, in contrast to barrows. Therefore, this study aimed to assess the effect of high-energy diet (HE, net energy (NE) = 10.2 MJ/kg) compared to low-energy diet (LE, NE = 8.8 MJ/kg) in barrows and immunocastrates and as a reference, gilts and entire male pigs on a standard high-energy diet were included. CP and standardised ileal digestible amino acid levels were similar in both diets. For each treatment, eight pen replicates of six pigs per pen were evaluated on performance, carcass quality, meat and fat quality, digestibility, economic and ecological sustainability, behaviour and effectiveness of immune response. No difference in feed intake of immunocastrates between LE and HE could be demonstrated. As a result, daily energy intake of immunocastrates was higher on HE compared to LE, which resulted in a higher daily gain on HE. Feed conversion ratio (FCR) of immunocastrates on HE did not differ significantly with FCR of entire males. Barrows did not show higher average daily gain on HE compared to LE. Nitrogen efficiency was better in HE compared to LE, without negative effects on digestibility, carcass quality, economic parameters, behaviour or immune response. Small positive effects on the palatability of the meat of immunocastrates on HE were observed, although consumers did not prefer one of both feeds. Immunocastration was successful in reducing sexual and aggressive behaviour as well as in lowering the prevalence of boar taint from 15% in EM to 0% in immunocastrates. However, in two out of 96 immunocastrates (one on HE and one on LE), the immunocastration was not fully effective. In conclusion, this study did not show advantages of feeding immunocastrates or barrows a low-energy diet.

Effects of Dietary Energy Levels on Rumen Fermentation, Gastrointestinal Tract Histology, and Bacterial Community Diversity in Fattening Male Hu Lambs.

This study investigated rumen fermentation and histological and microbial diversity in male Hu lamb fed diets with different metabolizable energy (ME) levels (MEA, 9.17 MJ/kg, MEB, 10.00 MJ/kg, and MEC, 10.82 MJ/kg). Thirty-six male Hu lambs were randomly allotted to three treatments, and the feeding trial lasted for 67 days. Rumen fermentation results suggest that the iso-valerate had a significant effect on dietary energy level. The papillary height (PH) of rumen was the highest in the MEB group, the crypt depth (CD) was significantly increased in the duodenum and jejunum, and the villus height (VH)-to-CD ratio (VH/CD) was significantly decreased in the duodenum by increasing dietary energy levels; the VH, villus width (VW), and VH/CD also had significant differences in the ileum. 16S rRNA sequencing results showed that the operational taxonomic units (OTUs) number, the ACE, and Chao1 indices were linearly decreased by increasing dietary energy level; 24 phyla including 124 genera were identified, and the relative abundance of Papillibacter and Quinella linearly decreased by increasing the dietary energy level. Compared to MEA and MEB groups, the relative abundance of unidentified_Veillonellaceae and Anaerovibrio was significantly increased in the MEC group at the genus level. The relative abundance of the carbohydrate metabolism pathway predicted by Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt) was linearly increased by increasing the dietary energy levels. Three metabolic pathways identified in Kyoto Encyclopedia of Genes and Genomes (KEGG) level 3 were significantly influenced as the dietary energy level increased. In summary, these results demonstrated that the dietary energy levels affected the rumen fermentation parameters, morphological structures of the gastrointestinal tract (GIT), and the composition and function of rumen microflora in male Hu sheep.

Effects of dietary energy level and guanidino acetic acid supplementation on growth performance, carcass quality and intestinal architecture of broilers

Energy, known as the most expensive nutrient in broiler feed, is what strongly adjusts and affects the growth of broilers. Creatine has a key role in cellular energy metabolism and could be synthesised from guanidinoacetic acid (GAA) in the liver; however, its de novo synthesis is not able to adequately fulfil the demand of energy metabolism, especially in fast-growing modern broilers. So the aim of the study was to evaluate the efficiency of commercial GAA in energy-reduced broiler diets on performance and intestinal development. Overall, 11 400 day-old Ross 308 chicks were randomly allocated to six dietary treatments with ten replicates in each. Dietary treatments were designed as a 3 × 2 factorial arrangement with three levels of dietary metabolisable energy (AME&lt;sub&gt;n&lt;/sub&gt;) recommended by Aviagen for Ross 308 broilers (12.55 MJ/kg, 12.97 MJ/kg and 13.38 MJ/kg for starter, grower and finisher, respectively), 0.209 MJ/kg and 0.418 MJ/kg reduced and two levels of GAA (0.00% and 0.06%). There was no significant GAA × AME&lt;sub&gt;n&lt;/sub&gt; interaction for all performance parameters, carcass traits and jejunal morphological parameters (except for the villus width). Reduction of dietary AME&lt;sub&gt;n&lt;/sub&gt; (0.209 MJ/kg and/or 0.418 MJ/kg) caused a significant depression in body weight (BW) gain (P &amp;lt; 0.001) and feed conversion ratio (FCR) (P &amp;lt; 0.001). However, a decreasing AME&lt;sub&gt;n&lt;/sub&gt; level increased villus height (P &amp;lt; 0.003) and villus surface area (P &amp;lt; 0.03), while crypt depth and villus width were similar. The GAA improved final BW and FCR by 1.77% and 1.66%, respectively (P &amp;lt; 0.001). Birds fed low energy diets supplemented with GAA showed a significant improvement in the performance so that BW and FCR were the same as in the control birds; however, no such positive effects were obtained in jejunal villus development. Hence, it might be concluded that 0.06% GAA supplementation improves BW and FCR and can save at least 0.209 MJ/kg dietary AME&lt;sub&gt;n&lt;/sub&gt; in broiler diets.

Effect of Dietary Energy Levels on The Performances of Testicular Development, Live Body Weight and Testosterone Concentration in Ouled Djellal Ram Lambs

The aim of our study was to determine the effect of the dietary energy levels on the live body weight, testis volume and blood testosterone concentration in Ouled Djellal ram lambs throughout growth. The study lasted six months from post-weaning until the pubertal period at the Technical Institute Farms (I.T.E.L.V) Lamtar of Sidi-bel-Abbes (Western Algeria). After weaning, Twenty single-born Ouled Djellal ram lambs from 90 to 240 days old were weighed and allotted into two equal groups of Low energy (n = 10) or High energy (n = 10) nutrition plane. Each group received; in addition to a basal diet (good quality pasture) 200 g and 400 g of concentrate feed mixture containing barley (60%), corn (5%), wheat bran (37.5 %) and vitamin-mineral compound (2.5 %) by head-1day-1 respectively. Hay and water were provided ad libitum. Monthly measurements of live body weight, testicular volume and blood testosterone concentration of lambs were recorded. The results showed that the High energy group of lambs recorded a significantly higher live body weight compared to the lambs of low energy group (p <0.001). Whereas, the testicular growth indicated a gradual and linear increase for both groups (low energy and high energy) with significant differences (p <0.001). However, all measurements of the testis, live body weight, serum testosterone levels and age were positively correlated with one another of both low and high groups throughout the experiment. In conclusion, High-level energy supplementation can improve to enhanced development in Ouled Djellal ram lambs this may be due to its beneficial effect on the productive and reproductive performance of growing male lambs. Furthermore, using younger lambs may reduce production costs, accelerate the benefits of genetic selection, and allow earlier progeny and libido testing.

Effects of Dietary Energy Level on Performance, Plasma Parameters, and Central AMPK Levels in Stressed Broilers.

This study aimed to characterize the effects of diets with different energy levels on the growth performance, plasma parameters, and central AMPK signaling pathway in broilers under dexamethasone (DEX)-induced stress. A total of 216 1-day-old male broiler chickens were allocated to groups fed with high (HED), National Research Council-recommended (control), or low (LED) energy diets. At 10 days old, chickens were treated with or without dexamethasone (DEX, 2 mg/kg body weight) for 3 consecutive days. HED increased broiler average daily gain (ADG) at 10 days old, compared with the LED (P < 0.05), while average daily feed intake (ADFI) and feed conversion rate (FCR) decreased as the dietary energy level increased (P < 0.05). Chickens fed a HED had higher total protein (TP) content, albumin (ALB), glucose (GLU), total cholesterol (TCHO), high-density lipoprotein (HDL) cholesterol, and low-density lipoprotein (LDL) cholesterol, compared with the control group (P < 0.05). At 13 days old, DEX decreased ADG and increased FCR in broilers fed with different energy diets (P < 0.05). The DEX-HED group had a higher ADFI than non-DEX treated HED group chickens. In addition, TP, ALB, triglycerides (TG), TCHO, HDL, and LDL content levels in the DEX group were higher than those in the control group (P < 0.05). The uric acid (UA) content of the LED group was higher than that of the HED group (P < 0.05). Further, gene expression levels of liver kinase B1, AMP-activated protein kinase α1, neuropeptide Y, and GC receptor in the hypothalamus were increased in chickens treated with DEX (P < 0.05). There was a trend toward interaction between plasma TCHO and hypothalamic LKB1 expression (0.05 < P < 0.1). In conclusion, this study suggests that HED improves growth performance, plasma glucose and total cholesterol at 10 days old broilers, but had no significant effect on performance, plasma parameters, and central AMPK in stressed broilers.

Effects of dietary energy levels on Pectoralis major mixed muscle protein turnover and body composition in two broiler lines housed in different grow-out environments.

This study determined the Pectoralis (P) major mixed muscle protein turnover (PT) in two meat broiler lines, Line A and Line B, during the finishing grow-out feeding period (21-42days) as affected by the dietary metabolizable energy (ME) levels and ambient temperatures. Experimental finishing diets consisted of 80, 90, 100, 110 and 120% ME of recommended nutrient guidelines for energy level. Fractional synthesis rates (FSR) or fractional degradation rates (FDR) were measured in P.major at day 36 and 42. Protein and fat mass gain were measured, and respective energy retention efficiencies as protein and fat (EREp and EREf) were determined. Metabolic heat production (HP) was also reported. Experimental feeding studies were conducted in cool season (24hr mean: 69.91˚F and 63.98% RH) and in hot season (24hr mean: 77.55˚F and 86.04% RH). Results showed that FSR or FDR values were not affected by dietary ME levels at day 36, whereas reduced FSR (p<.05) were observed at day 42 fed diets with reduced ME levels (≤100% ME) which could have resulted from greater maintenance energy requirement of maturing broilers at that age. Broilers fed reduced ME diets (≤100% ME) maintained protein mass (equivalent to broilers fed ≥100%-120% ME) by reduced FDR and increased feed intake. Grow-out ambient temperature did not affect FSR or FDR values across ME levels. Line B retained higher protein mass, lower fat mass and greater HP compared to Line A. This was followed by higher feed intake in Line B. Further, Line B exhibited higher EREp and lower EREf across dietary ME levels. In summary, PT homeostasis and body composition changes in broiler lines studied seemed to be regulated by the birds' intent to normalize energy intake as per physiological need by controlling feed intake.

Effects of dietary energy levels on performance and carcass yield of 2 meat-type broiler lines housed in hot and cool ambient temperatures

Two meat-type broiler lines, line A and line B were fed experimental diets from 22–42 d with objectives to determine the effects of dietary metabolizable energy (ME) levels on feed intake (FI), performance, body composition, and processing yield as affected by environmental grow-out temperatures. Two thousand fifty male chicks from line A and 2,050 male chicks from line B were reared in 90-floor pens, 45 chicks per pen utilizing primary breeder nutrition and husbandry guidelines for starter (1–10 d) and grower (11–21 d) phases. Experimental finisher diets consisted of 5 increasing levels of apparent nitrogen corrected ME (2,800, 2,925, 3,050, 3,175, and 3,300 kcal/kg set at 19.5% crude protein and 1.0% dLys at each level) to represent 80, 90, 100, 110, and 120% ME of Evonik AminoChick energy level giving 2 × 5 factorial design and were fed from 22–42 d. All other amino acid levels in diets were formulated to a fixed ratio of dLys level. There were nine replicate pens for each diet and each line. The experiment was conducted twice—once in hot season (barn averages: 77.55 ˚F and 86.04% RH) and another in cool season (barn averages: 69.91 ˚F and 63.98% RH) of the year. Results showed that FI and feed conversion ratios (FCR) decreased (P < 0.05) linearly (R2 = 0.9) by 61.25 g and 0.073 units for every 10% increase in dietary ME for combined analysis of lines and seasons. The % fat mass of total body mass increased by 0.57%, whereas % protein mass decreased by 0.21% across ME levels (R2 > 0.9). However, there was no difference (P > 0.05) in % weights (of live weight) for wings, breast filet, tenders, or leg quarters across ME levels for both lines except % fat pad that increased (P < 0.05) by 0.20% for each 10% increment in dietary ME level. Line B had higher cumulative FI, BW gain, % lean, and protein mass of body mass than line A in hot season (P < 0.05). Feed intake was not different between lines in cool season (P > 0.05), whereas higher BW and improved FCR were observed for line A. Line A had higher % fat mass in both seasons. In summary, performance and yield results as affected by dietary ME levels were line specific and were affected by grow-out seasons. The optimal dietary ME level for the ME range studied (2,800–3,000 kcal/kg) at a constant recommended amino acid level lies in determining the best performance and profitability indices by taking into account the grow-out production inputs and processing yield outputs.