HP Diet Research Articles

Comparison of the fermentation and bacterial community in the colon of Hu sheep fed a low-grain, non-pelleted, or pelleted high-grain diet.

Microbial fermentation in the hindgut is likely an important contributor to energy availability in ruminants, except for the rumen. This study aimed to investigate commensal bacteria in the colon influenced by diverse dietary niches. Fifteen male sheep were randomly allotted into three feeding groups: non-pelleted low-grain (CON, n = 5), non-pelleted high-grain (HG, n = 5), and pelleted high-grain (HP, n = 5) diets. The HG and HP groups had higher fermentation parameters than the CON group, especially acetate concentration (CON = 46.91; HG = 61.66; HP = 77.99). The HG diet altered the composition of commensal bacteria in the colon in comparison to the CON group, including the increase of genera related to acetate production (e.g., Acetitomaculum spp.), butyrate production (e.g., Coprococcus spp. and Subdoligranulum spp.), and starch degradation (e.g., Prevotella spp., Roseburia spp., and Oscillibacter spp.). The colon functional compendium had co-alteration with taxonomic changes that indicated non-pelleted HG diet caused a detrimental colonic niche. The HP diet specifically promoted the abundance of Ruminococcus, Olsenella, and Alloprevotella genera to achieve the highest acetate concentration and decreased the starch-degrader Roseburia spp. and Oscillibacter spp. in contrast to the HG group. Our results provide a systematic view of the microbial fermentation, community, and functional guilds in colonic digesta and mucosa in regard to using an HP diet to maintain colonic niche homeostasis under the adverse influence of the HG diet.Key Points• Non-pelleted and pelleted high-grain diets altered sheep colonic fermentation.• Non-pelleted and pelleted high-grain diets resulted in diverse microbial composition.• The pelleted method ameliorated microbial functions compared with the high-grain diet.

Interactions of amino acids and hormones regulate the balance between growth and milk protein synthesis in lactating rats fed diets differing in protein content.

Insulin-like growth factor-I (IGF-I), growth hormone (GH), and prolactin (PRL) play important roles in milk protein synthesis, and their plasma concentrations were reported to be affected by dietary protein intake. To investigate the relationship between circulating amino acid (AA) and concentrations of these hormones, 18 Wistar rats aged 14 wk were assigned to a low (LP; 9% protein), standard (SP; 21% protein), or high-protein (HP; 35% protein) diet from parturition through day 15 of lactation. Plasma, liver, pituitary gland, skeletal muscle, and mammary gland samples were collected at the end of treatment. Circulating and hepatic IGF-I concentrations increased linearly with elevated dietary protein concentrations (P < 0.0001). Rats receiving the HP diet had higher circulating GH (P < 0.01) and pituitary PRL concentrations (P < 0.0001) but lower pituitary GH concentration (P < 0.0001) relative to those in rats receiving the LP and SP diets. Pearson correlation test performed on composed data across treatments showed that several circulating AAs were correlated with circulating and tissue concentrations of IGF-I, GH, and PRL. Multiple linear regression analyses identified Leu, Gln, Ala, Gly, and Arg as the main AAs associated with hormone responses (R2 = 0.37 ~ 0.80; P < 0.05). Rats fed the LP and HP diets had greater Igf1 and Ghr gene expression in skeletal muscle than those fed the SP diets (P < 0.01). However, LP treatment decreased Prlr mRNA abundance in mammary glands as compared with the SP and HP treatments (P < 0.05). The HP diets increased AA transporter expression (P < 0.01) but decreased mammalian target of rapamycin (P < 0.05) and 70 kDa ribosomal protein S6 kinase 1 (P < 0.01) phosphorylation in mammary glands as compared with the LP and SP diets. The results of the present study suggested that several circulating AAs mediated the effects of dietary protein supply on concentrations of IGF-I, GH, and PRL, which in turn altered the metabolism status in peripheral tissues including the lactating mammary glands.

High protein intake promotes the adaptation to chronic hypoxia in zebrafish (Danio rerio)

Chronic hypoxia is a common environmental stress factor in aquaculture. Many researchers have illustrated the physiological and metabolic changes under chronic hypoxia, but there are few studies to evaluate the relationship between dietary nutrients and hypoxic adaptation in fish. In the present study, we fed zebrafish with control diet (C), high-carbohydrate diet (HC), high-fat diet (HF) and high-protein diet (HP) at normal dissolved oxygen (DO = 7.0 ± 0.5 mg/L) or low dissolved oxygen (DO = 2.5 ± 0.5 mg/L) environment, respectively. After a 7-week feeding trial, the growth performance, body composition, tissue biochemical indexes, mRNA expressions of hifα isoforms and nutrient metabolism-related genes, intestinal digestive enzyme activities and microbiota composition were measured. The results indicated that only the HP diet could alleviate the reduction of body weight and feed efficiency induced by chronic hypoxia, but the HF diet feeding worsened the adverse effects of chronic hypoxia in zebrafish. At the C groups, hypoxia increased catabolism of lipid and protein, but at the HP groups, hypoxia enhanced utilization of glycogen and protein. Compared to the C-hypoxia group, the HP feeding could activate transcription of hif-1a and its downstream glycolysis genes in chronic hypoxia. Furthermore, at hypoxic state, the HP feeding could alleviate the reduction of intestinal digestive enzyme activities and microbiota dysbiosis induced by the chronic hypoxia, including increasing bacterial diversity and decreasing Cetobacterium genus abundance. This is the first study indicating that high protein intake could strengthen ability of fish in resisting the negative effect of chronic hypoxia.

Effects of High and Low Protein Diets on Inflammatory Profiles in People with Morbid Obesity: A 3-Week Intervention Study.

Nutritional interventions in morbidly obese individuals that effectively reverse a pro-inflammatory state and prevent obesity-associated medical complications are highly warranted. Our aim was to evaluate the effect of high (HP) or low (LP) protein diets on circulating immune-inflammatory biomarkers, including C-reactive protein (CRP), interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-a), interleukin-10 (IL-10), monocyte chemoattractant protein-1 (MCP-1), chemerin, omentin, leptin, total adiponectin, high molecular weight adiponectin, and fetuin-A. With this aim, 18 people with morbid obesity were matched into two hypocaloric groups: HP (30E% protein, n = 8) and LP (10E% protein, n = 10) for three weeks. Biomarkers were measured pre and post intervention and linear mixed-effects models were used to investigate differences. Consuming HP or LP diets resulted in reduced CRP (HP: −2.2 ± 1.0 mg/L, LP: −2.3 ± 0.9 mg/L) and chemerin (HP: −17.9 ± 8.6 ng/mL, LP: −20.0 ± 7.4 ng/mL), with no statistically significant differences by diet arm. Participants following the LP diet showed a more pronounced decrease in leptin (−19.2 ± 6.0 ng/mL) and IL-6 (−0.4 ± 0.1 pg/mL) and an increase in total adiponectin (1.6 ± 0.6 µg/mL). Changes were also observed for the remaining biomarkers to a smaller degree by the HP than the LP hypocaloric diet, suggesting that a LP hypocaloric diet modulates a wider range of immune inflammatory biomarkers in morbidly obese individuals.

Lack of Endothelial Nitric Oxide Synthase Accelerates Ectopic Calcification in Uremic Mice Fed an Adenine and High Phosphorus Diet

Ectopic calcification is a risk of cardiovascular disease in chronic kidney disease (CKD) patients, and impaired endothelial nitric oxide synthase (eNOS) is involved in the CKD complications. However, whether eNOS dysfunction is a cause of ectopic calcification in CKD remains to be elucidated. To address this issue, we investigated the role of eNOS in ectopic calcification in mice with renal injury caused by an adenine and high-phosphorus (Ade+HP) diet. DBA/2J mice, a calcification-sensitive strain, were fed Ade+HP for 3 weeks. Expression levels of eNOS-related genes were reduced significantly in their calcified aorta. C57BL/6J is a calcification-resistant strain, and wild-type mice showed mild calcified lesions in the aorta and kidney when given an Ade+HP diet for 4 weeks. In contrast, a lack of eNOS led to the development of severe aortic calcification accompanied by an increase in runt-related transcription factor 2, an osteochondrogenic marker. Increased renal calcium deposition and the tubular injury score were remarkable in mice lacking eNOS-fed Ade+HP. Exacerbation of ectopic calcification by a lack of eNOS is associated with increased oxidative stress markers such as nicotinamide adenine dinucleotide phosphate oxidases. In conclusion, eNOS is critically important in preventing ectopic calcification. Therefore, the maintenance of eNOS is useful to reduce cardiovascular disease events and to improve prognosis in CKD patients.

More Bone with Less Minerals? The Effects of Dietary Phosphorus on the Post-Cranial Skeleton in Zebrafish.

Dietary phosphorus (P) is essential for bone mineralisation in vertebrates. P deficiency can cause growth retardation, osteomalacia and bone deformities, both in teleosts and in mammals. Conversely, excess P supply can trigger soft tissue calcification and bone hypermineralisation. This study uses a wide range of complementary techniques (X-rays, histology, TEM, synchrotron X-ray tomographic microscopy, nanoindentation) to describe in detail the effects of dietary P on the zebrafish skeleton, after two months of administering three different diets: 0.5% (low P, LP), 1.0% (regular P, RP), and 1.5% (high P, HP) total P content. LP zebrafish display growth retardation and hypomineralised bones, albeit without deformities. LP zebrafish increase production of non-mineralised bone matrix, and osteoblasts have enlarged endoplasmic reticulum cisternae, indicative for increased collagen synthesis. The HP diet promotes growth, high mineralisation, and stiffness but causes vertebral centra fusions. Structure and arrangement of bone matrix collagen fibres are not influenced by dietary P in all three groups. In conclusion, low dietary P content stimulates the formation of non-mineralised bone without inducing malformations. This indicates that bone formation and mineralisation are uncoupled. In contrast, high dietary P content promotes mineralisation and vertebral body fusions. This new zebrafish model is a useful tool to understand the mechanisms underlying osteomalacia and abnormal mineralisation, due to underlying variations in dietary P levels.

Unconnected Body Accrual of Dietary Lipid and Protein in Rats Fed Diets with Different Lipid and Protein Content.

Eating large amounts of fat is usually associated with fat accumulation. However, different types of diets (not only lipids) elicit different metabolic responses. Male and female rats (10 week-old) are distributed in four groups and fed for 1 month a standard diet (SD), or this diet enriched with either lipid (high-fat diet, HF) or protein (high-protein diet, HP), or a cafeteria diet (CAF). Both HF and CAF diets share the percentage of energy from lipids (40%) but these are different. Protein-derived energy in the HP diet is also 40%. Feeding SD, HF, and HP diets does not result in differences in energy intake, energy expenditure, total body weight, or lipid content. However, the CAF-fed groups show increases in these parameters, which are more marked in the male rats. The CAF diet increases the mass of adipose tissue while the HF diet does not. Different diets produce substantial changes in the fate of ingested nutrient energy. Dietary lipids are not essential for sustaining an increase in body lipid (or adipose tissue) content. Body protein accrual is unrelated to dietary lipids and overall energy intake. Both protein and lipid accrual are more efficient in male rats.

A Humanized Diet Profile May Facilitate Colonization and Immune Stimulation in Human Microbiota-Colonized Mice.

BackgroundIn spite of the importance of the use of gnotobiotic mice for human fecal transfer, colonization efficiency and immune stimulation after human microbiota inoculation in mice are poorly studied compared to mouse microbiota inoculation. We tested the colonization efficiency and immune responses in mice bred for one additional generation after inoculating the parent generation with either a human (HM) or a mouse microbiota (MM). Furthermore, we tested if colonization efficiency and immune stimulation could be improved in HM-colonized mice by dietary approaches: if these were fed a diet closer to the human diet either in its sources of animal fat and protein [the “animal source” (AS) diet] or in its proportions of macronutrients from the normal sources of a mouse diet [the “human profile” (HP) diet].ResultsAlthough significantly lower in mice with a human microbiota (30–40% vs. 61–70%) the colonization efficiency was significantly higher in HM mice fed the HP diet (40%), and in MM mice fed AS (70%). The microbiota of mice fed HP was comparable to the microbiota of mice fed a standard rodent chow, while the microbiota of mice fed the animal source diet (AS) clustered separately. Mice inoculated with mouse fecal matter had significantly more CD4+ T cells and Cd4 expression and significantly fewer regulatory T cells (Tregs) and FoxP3 expression than human microbiota inoculated mice, but cell proportions differences were mostly apparent between mice fed the AS diet. Mice fed the HP diet had significantly higher expression of Cd8a.ConclusionIt is concluded that a diet with a humanized profile could support the establishment of a human microbiota in mice, which will, however, still elicit a lower colonization efficiency compared to mice inoculated with a mouse microbiota.

Effects of Prolonged Energy Restriction and Dietary Protein on Muscle Protein Synthesis and Proteome Dynamics in Obese Zucker Rats

Abstract Objectives High protein (HP) diets during short-term energy restriction (ER) attenuate energy-mediated reductions in muscle protein synthesis (MPS). MPS-adaptive responses to HP diets during prolonged ER are not well described. This study examined the effects of prolonged ER and HP on MPS and the synthesis rates of numerous individual muscle proteins. Methods Female 6-wk-old obese Zucker (leprfa+/fa+, n = 48) rats were randomized to one of four diet groups for 10 weeks: ad libitum-standard protein (AL-SP; 14% protein), AL-HP (35% protein), ER-SP, and ER-HP (both fed 60% of intake of AL-SP). At the start of week 10, D2O was administered by intraperitoneal injection and isotopic equilibrium was maintained daily by providing D2O in drinking water. Rats were euthanized after 1 week of labeling, and mixed-MPS (gastrocnemius), absolute mixed-MPS (mixed-MPS x muscle protein content), proteome dynamics, and protein half-lives [rate/d (k) = –ln(1-f)/d, where f is mixed-MPS and t is time in days; t1/2 (days) = ln(2)/k] were quantified. Results Mixed-MPS was not altered by energy status and protein intake. Gastrocnemius mass was lower (P &amp;lt; 0.001) in ER-fed rats than AL-fed rats and higher (P = 0.034) for AL-HP than AL-SP. As a result, absolute mixed-MPS was lower (P &amp;lt; 0.005) in ER than AL, regardless of dietary protein. Absolute synthesis in 24 of 26 myofibrillar, 32 of 61 mitochondrial, and 55 of 60 cytoplasmic measured proteins were lower in ER than AL (P &amp;lt; 0.05), regardless of dietary protein. The difference in absolute synthesis of myofibrillar, mitochondrial, and cytoplasmic proteins due to ER compared to AL was 28%, 16%, and 27%, respectively. Comparison of HP and SP within each energy state revealed lower turnover rates and prolonged half-lives for a majority of measured muscle proteins in HP than in SP in both ER and AL conditions (P &amp;lt; 0.001). Conclusions Prolonged ER in obese Zucker rats exerted a strong suppressive effect on myofibrillar, mitochondrial, and cytoplasmic MPS, suggesting reduced protein accretion contributed to lower gastrocnemius mass in ER-fed rats. Lower turnover rates of most muscle proteins in HP-fed rats without reductions in protein pool size (i.e., tissue mass) suggests prolonged HP intake, independent of energy, may prolong muscle protein lifespan of in obese Zucker rats. Funding Sources Supported by USAMRDC; authors’ views not official U.S. Army or DoD policy.

Genetic Background Heavily Impacts Effects of Diet on Obesity in a Collaborative Cross Population

Abstract Objectives Obesity is a complex disease long established to be strongly influenced by diet, yet it is still unclear why no specific diet can effectively control obesity development across all human populations. Because genetics also strongly impacts the development of obesity, we tested the hypothesis that individual genetic background determines how strongly diet affects adiposity accumulation by quantifying the impact of genetics and diet on adiposity in a panel of genetically diverse recombinant inbred mice. Methods Female mice from 22 Collaborative Cross (CC) strains (total n = 204) were first placed on a synthetic control (AIN-76A) diet for 2 weeks, and then randomly assigned to either a high protein (HP, n = 102) or high fat high sucrose (HS, n = 102) diet for 8 weeks. MRI body composition analysis was performed on the mice to assess baseline body composition and weight after 2 weeks on AIN-76A, and again 8 weeks post-diet. Changes in adiposity accumulation (ΔBF%) were calculated by subtracting baseline % body fat (BF%) from post-diet BF%. Results At baseline there was a wide range of adiposity in the CC ranging from 1.1–29.8% body fat, with line CC019 least susceptible to obesity (mean BF% = 4.4 ± 0.56%) and line CC028 most susceptible (mean BF% = 23.1 ± 1.5%); genetic background (CC strain) had a significant effect on BF% (ANOVA, F = 12.4, P = 7.7 × 10−25). After 8 weeks of the diet challenge, CC019 was the strain least susceptible to obesity regardless of diet (mean HP BF% = 4.7 ± 0.4%, mean HS BF% = 4.6 ± 0.5%), while strains most prone to obesity on HP and HS diets were CC040 (mean BF% = 29.7 ± 1.3%) and CC028 (mean BF% = 35.7 ± 2.0%), respectively. Diet induced a wide range of effects on changes in adiposity depending on strain, including fat loss on both diets (CC036, ΔBF% HP = −5.1 ± 2.5% and HS = −4.1 ± 2.3%), similar fat gain on both diets (CC040, ΔBF% HP = 4.2 ± 0.8% and HS = 5.1 ± 2.1%), dramatic fat gain on one diet compared to the other (CC028, ΔBF% HP = 2.0 ± 1.1% and HS = 11.1 ± 1.1%), or fat loss/gain depending on the diet (CC027, ΔBF% HP = −1.4 ± 1.0% and HS = 6.8 ± 1.7%). Linear mixed model analysis revealed significant effects of strain x diet interactions on ΔBF% (Satterthwaite approx., P = 1.5 × 10−5). Conclusions Genetic background plays a significant role in the predisposition of obesity development and determining the degree of diet effects on adiposity accumulation in the CC. Funding Sources USDA.

Effects of Dietary Protein Levels on Growth Performance, Carcass Traits, Serum Metabolites, and Meat Composition of Tibetan Sheep during the Cold Season on the Qinghai-Tibetan Plateau.

Simple SummaryThe Tibetan sheep (Ovis aries) is an ovine breed well adapted to the harsh plateau environment. For a long period of time, Tibetan sheep farming has been an important pillar industry for native herders on the Qinghai-Tibetan Plateau. With the increasing demand for sheep meat and products, nutrition research has gained increasing importance. In this study, the effects of three different dietary protein levels (10.1%, 12.1%, and 14.1%) on growth performance, carcass traits, serum metabolites, and meat composition were investigated in Tibetan sheep during the cold season. The results showed that the diets containing 12.1% and 14.1% protein were better than a diet containing 10.1% protein for enhancing the growth performance, carcass performance, and meat products of the Tibetan sheep.Dietary protein is a critical nutrient that directly influences the health and production of livestock. Recent studies showed that protein supplements could enhance the growth performance of Tibetan sheep. However, there is a lack of information regarding the influence of dietary protein levels on carcass traits and meat composition. This study investigated the effects of dietary protein levels on growth performance, carcass traits, serum metabolites, and meat composition in Tibetan sheep during the cold season on the Qinghai-Tibetan Plateau. A total of eighteen 1-year-old, healthy, castrated Tibetan sheep with similar initial body weights (31.7 ± 0.72 kg) were randomly divided into three treatment groups with different dietary protein level (low protein (LP, 10.1%); medium protein (MP, 12.1%); high protein (HP, 14.1%)) diets. The results indicated that the Tibetan sheep fed with the MP and HP diets had greater final body weights (BWs), average daily gains (ADGs), and average daily feed intakes (ADFIs) (p < 0.05). The MP and HP diets also improved the hot carcass weight, net meat (including the fat) weight, and bone weight of the sheep significantly (p < 0.05). Besides, the dietary protein levels could significantly affect the serum concentrations of growth hormone (p < 0.05). The diameter of muscle fibers in the MP group was significantly greater than that in the LP group (p < 0.05), while the density of muscle fibers showed the opposite trend. The dietary protein levels only significantly (p < 0.05) influenced the ether extract content and profile content of the longissimus dorsi muscle but had no effect on other parameters of meat composition. In summary, our results indicate that dietary protein levels affect growth performance, carcass traits, and meat composition and that diets containing 12.1% and 14.1% protein are recommended to obtain better production performance and meat products in Tibetan sheep, rather than a diet containing 10.1% protein, during the cold season on the Qinghai-Tibetan Plateau.

Ileal Transposition in Rats Reduces Energy Intake, Body Weight, and Body Fat Most Efficaciously When Ingesting a High-Protein Diet

PurposeIleal transposition (IT) allows exploration of hindgut effects of bariatric procedures in inducing weight loss and reducing adiposity. Here we investigated the role of dietary macronutrient content on IT effects in rats.MethodsMale Lewis rats consuming one of three isocaloric liquid diets enriched with fat (HF), carbohydrates (HC), or protein (HP) underwent IT or sham surgery. Body weight, energy intake, energy efficiency, body composition, and (meal-induced) changes in plasma GIP, GLP-1, PYY, neurotensin, and insulin levels were measured.ResultsFollowing IT, HC intake remained highest leading to smallest weight loss among dietary groups. IT in HF rats caused high initial weight loss and profound hypophagia, but the rats caught up later, and finally had the highest body fat content among IT rats. HP diet most efficaciously supported IT-induced reduction in body weight and adiposity, but (as opposed to other diet groups) lean mass was also reduced. Energy efficiency decreased immediately after IT irrespective of diet, but normalized later. Energy intake alone explained variation in post-operative weight change by 80%. GLP-1, neurotensin, and PYY were upregulated by IT, particularly during (0–60 min) and following 17-h post-ingestive intake, with marginal diet effects. Thirty-day post-operative cumulative energy intake was negatively correlated to 17-h post-ingestive PYY levels, explaining 47% of its variation.ConclusionReduction in energy intake underlies IT-induced weight loss, with highest efficacy of the HP diet. PYY, GLP-1, and neurotensin levels are upregulated by IT, of which PYY may be most specifically related to reduced intake and weight loss after IT.

High protein diet increases kidney macrophages and accelerates polycystic kidney disease

BackgroundAutosomal dominant polycystic kidney disease (ADPKD) is the most common genetic kidney disease that leads to end stage renal disease. Interestingly, the disease severity is highly variable even among families with the same gene mutation, suggesting factors other than genetics may affect cystogenesis. One factor that accelerates cystogenesis in PKD rodent is a high protein diet that results in renal hypertrophy. However, the mechanism of how a high protein diet promotes cystogenesis is unknown. We have shown that renal hypertrophy triggered by unilateral nephrectomy increases kidney macrophages and accelerates cystogenesis in ADPKD mouse. Therefore, we hypothesize that a high protein diet fed in ADPKD mice leads to increased kidney macrophages and accelerates cyst growth similar to a unilateral nephrectomy model.MethodsWe used adult tamoxifen inducible Pkd1flox/flox mice with or without Cagg cre‐ER. These adult conditional Pkd1 knockout mice typically requires months to develop major kidney cysts. Three weeks after cre induction, mice were fed with either a high protein (HP: 60%), a normal protein (NP: 18%) or a low protein (LP: 6%) diet for a total of 1 and 6 weeks. Some mice were given a HP diet and treated either with liposomal clodronate (to deplete macrophage) or with PBS (IP twice a week) for a total of 6 weeks. All mice were sacrificed at the end of the experiment and kidneys were harvested for histology, cytokines and flow cytometry for kidney immune cell sorting.ResultsPkd1 mice fed a HP diet for 6 weeks resulted in increased number of kidney resident macrophage (CD11blo, F4/80 hi) and infiltrating macrophages (CD11bhi, F4/80lo) compared to kidneys from a NP or LP diet fed mice. A HP diet resulted in increased kidney pro‐inflammatory cytokines, chemokine and developed severe kidney cysts compared to a NP or LP diet group. Pkd1 mice treated with liposomal clodronate had fewer resident and infiltrating macrophages and smaller kidneys compared to control PBS treated group. Interestingly, mice fed a HP diet for 1 week already had larger kidneys compared to those fed a LP diet, but there were no differences in kidney chemokines or tubular injury marker.ConclusionsRenal hypertrophy triggered by a HP diet increases kidney macrophages, inflammatory cytokine production and promotes cyst growth in adult Pkd1 mice. The mechanism of how dietary protein initiates and accelerates cyst growth remains to be determined.Support or Funding InformationNIH/NIDDK K08 DK106465, R03 DK119717 PKD Foundation 232G19a

Effects of dietary crude protein level and N-carbamylglutamate supplementation on nutrient digestibility and digestive enzyme activity of jejunum in growing pigs.

Three experiments were conducted to investigate the effects of dietary crude protein (CP) level and N-carbamylglutamate (NCG) supplementation on apparent total tract digestibility (ATTD) and ileal digestibility of nutrients and digestive enzyme activity of jejunum in growing pigs. In experiment 1, 10 Duroc × Landrace × Yorkshire barrows (initial BW: 48.7 kg) were allotted to a three-period switchback design with five experimental diets and two replicate pigs per diet in each period. Diets were categorized as high CP (HP, 18% CP), moderate low CP (MLP, 15% CP), very low CP (VLP, 12% CP), and MLP and VLP with 0.1% NCG supplementation. Feces and urine were collected from day 6 to day 11 after a 5-d adaptation period. The DE, ME, and ATTD of GE, OM, CP, NDF, ADF, and P decreased (P < 0.01) with a reduction of dietary CP, but no effect of dietary treatments on pig daily N retention was detected. The NCG supplementation increased (P < 0.01) DE and ATTD of ADF of the VLP diet. In experiment 2, 10 jejunal-cannulated Duroc × Landrace × Yorkshire barrows (initial BW: 44.5 kg) were fed five diets for three periods as experiment 1. Jejunal fluid was collected on days 6 and 8 after a 5-d adaptation period. The digestive enzymes activity was not affected by dietary CP level, except for α-amylase, for which there was a decrease (P < 0.01) in pigs fed VLP diets compared to HP and MLP diets. In experiment 3, 12 ileal-cannulated Duroc × Landrace × Yorkshire barrows (initial BW: 46.7 kg) were allotted to a three-period switchback design with six diets and two replicate pigs per diet in each period. The six experimental diets consisted of five experimental diets as experiment 1 and one N-free diet. Ileal digesta was collected from day 6 to day 8 after a 5-d adaptation period. Results indicated that apparent ileal digestibility (AID) of CP and P and ileal digestibility of Arg, His, Ile, Leu, Phe, and all dispensable AA, except Pro, decreased (P < 0.01) in pigs fed VLP diet compared to HP and MLP diets, but AID of GE, OM, EE, NDF, and ADF were not affected. The supplementation of NCG in the VLP diet increased (P < 0.01) the AID of CP and ileal digestibility of Arg, His, Leu, Phe, Val, Ser, and Tyr. In conclusion, reducing dietary CP level decreased nutrient digestibility, but improved the efficiency of dietary N utilization and reduced N emission. Moderate reduction of dietary CP level had a minimal effect on nutrient digestibility and digestive enzyme activity. Additionally, NCG supplementation plays a beneficial effect on nutrient digestion only if the dietary CP level is extremely lowered.

The Effects of Substituting Dietary Soybean Meal with Maize Grain on Milk Production in Dairy Goats.

Simple SummaryToday the environmental sustainability of livestock has become increasingly important. Nitrogen excretion from livestock can lead to air and groundwater pollution, causing acid rain, fine air particulates, and greenhouse gas emissions that lead to climate change, groundwater nitrate poisoning, and surface water eutrophication. Often, livestock are fed diets with a protein content that is much higher than what they require. In this experiment, a herd of dairy goats of the Alpine breed, reared on a farm in the hills near Genoa, Italy, was used to study the impacts of being fed a low- or a high-protein diet. The high-protein diet did not improve milk yield and quality; on the contrary, it lowered the efficiency of dietary-nitrogen utilization, increased feeding cost, and, above all, increased nitrogen excretion and the associated environmental risks. In conclusion, a high-protein diet is not advisable, both economically and environmentally, and a precision feeding approach (i.e., supplying the nutrients required for a given body mass and level of production, and no more) is highly recommended.In view of better environmental sustainability, livestock diets must not exceed protein requirements, as often happens with lactating goats reared in semi-intensive systems. The aim of this experiment was to verify in real-breeding conditions the influence of two diets with different protein contents (% crude protein (CP) on dry matter (DM)): 16.0 (high-protein diet; HP) vs 12.2 (low-protein diet; LP) on milk production in dairy goats. The diets differed only in the replacement—in the LP diet—of 250 g soybean meal with 250 g maize grain meal. Twenty-three Alpine goats were divided into two groups and used in a cross-over feeding trial for 2 months. Animals were weighed at the beginning of each month of the trial, and feed intake and milk yield and composition were recorded weekly. HP and LP did not differ statistically for milk yield and composition (3.32 vs 3.42 kg milk/d, 3.21% vs 3.27% fat, 3.31% vs 3.27% protein for HP and LP, respectively), but the HP diet determined a higher milk urea content (51.2 vs 36.6 mg/dL, p < 0.001) and a worse efficiency of nitrogen utilization (28.0% vs 37.2%). In conclusion, the LP diet resulted in a reduction of urinary nitrogen excretion by 28% and of the feed cost by about 10%.

Productive performance response of growing rabbits to dietary protein reduction and supplementation of pyridoxine, protease, and zinc.

An 8-week experiment was carried out to assess the impact of supplemental dietary pyridoxine (PY), protease (PR), zinc (Zn) and their mixture (MIX) with low protein diet (LP; 14.76% CP) or high protein diet (HP; 18.53% CP) on rabbit growth, feed utilization, and nutrients digestibility. Rabbits were divided into ten similar groups in a 2 (protein level) ×5 (treatments) factorial design. Treatments included a control group (without any additives), 5 mg PY/kg of diet, 100 mg Zn/kg of diet, 500 mg PR/kg of diet or a mixture of all tested feed additive with the same doses. Results indicated that growth performance, feed utilization, and nutrients digestibility indicators were retarded significantly with reduction of dietary crude protein. Growth performance and feed conversion were significantly enhanced as a result of PY, PR, Zn, and MIX supplementation. All feed supplements had significantly improved the digestibility of crude protein and digestible crude protein. No change in carcass traits was recorded in response to protein level and tested feed supplements. It is concluded that the growing rabbit responded positively to PY, Zn, PR, and MIX (particularly PY) supplemental of LP or HP diets, in terms of growth performance, feed conversion, and nutrient digestibility.

Phytase and phytate interactions on broilers' diet at 21 days of age

The objective was to evaluate the effects of different levels of phytase in diets with varying amounts of phytate on live performance and bone characteristics of broiler chickens at 21 D. The treatments consisted of a 3 × 5 factorial arrangement, with 3 levels of phytate, high ( HP ), medium ( MP ), and low ( LP ), and 5 diets consisting of a positive control ( PC ); negative control ( NC , with a reduction of 0.15% of calcium [ Ca ] and 0.15% of phosphorus [ P ]), and NC diet plus 0, 500, 1,000, or 1,500 FTU kg −1 of phytase. Feed intake peaked with supplementation of 1,051 FTU kg −1 phytase to the LP diets. Bone ash of broilers receiving LP showed a maximum response at 1,101 FTU kg −1 . Birds receiving the NC diet had a larger hypertrophic cartilage zone ( P < 0.05) than those receiving the PC diet. Serum Ca and P of birds receiving the NC treatment and LP diet were lower than those in broilers fed with the MP and HP diets. Broilers in the NC plus 500 FYT kg −1 treatments had lower tibia P levels than those in the PC treatment; also, broilers receiving HP diets had a higher tibia Ca content than those receiving LP diets ( P < 0.05). In general, bone P of birds fed with diets containing HP was higher than that of birds on a LP or MP diet ( P < 0.05). The use of 1,101 FTU kg −1 resulted in better bone characteristics when fed with the lowest phytate level, and this level does not negatively affect the other parameters evaluated.

Modelling effects of carcass weight, dietary concentrate and protein levels on the CH4 emission, N and P excretion of dairy bulls

Cattle farming is an important agricultural contributor to methane (CH4) emissions and has also a significant environmental impact through nutrient surpluses onto arable land. Therefore, the purpose of the present study was to model the effects of carcass weight (CW) and dietary concentrate and protein levels on the CH4 production and nitrogen (N) and phosphorus (P) excretion of dairy bulls fed grass silage-based diets. The modelling was based on treatment mean data from a growing cattle feeding experiment in which the concentrate and protein supply was manipulated. The three concentrate proportions were 300 (LC), 500 (MC) and 700 (HC) g/kg dry matter (DM) fed without (LP) or with (HP) rapeseed meal (RSM) supplementation. In the LP and HP diets the crude protein content of the concentrate was 128 and 160 g/kg DM, respectively. Methane emissions and faecal N output were predicted by the dynamic and mechanistic Karoline model. Manure P was calculated as P intake – Retained P. Predicted differences between the diets in CH4 emissions were small; the greatest difference was approximately 4% lower CH4 intensity expressed per kg carcass weight gain (CWG) in cattle fed HC diet compared with those fed LC or MC diets. Total N intake decreased with increasing diet concentrate proportion, which resulted in reduced urinary and faecal N output and reduced excretions per kg body weight (BW) and CWG. Increased N intake with RSM supplementation resulted in a greater total manure N output per day and per kg BW and CWG. Most of the increase in manure N output with RSM supplementation was urinary N. Manure P output per day and per kg BW and CWG increased with greater concentrate or protein supplementation. Within the practical range of grass silage-based beef cattle diets fed to dairy bulls the effects of diet composition on methane yield or intensity were small. However, taking into account carbon footprint of feed production, increasing proportion of grain in the diet can increase total carbon footprint. Emissions per unit of CWG markedly increase with increased CW. Manure N and P output and methane emission per unit of CWG increased more rapidly in BW above 570 kg, mainly because of reduced BW gain. Manure N and P output per kg CWG were mainly related to dietary concentrations of these nutrients and CW. Decreasing dietary N and P inputs is the best nutritional strategy to reduce manure N and P outputs.

385 Feed efficiency of beef cattle in low-protein diets is driven by nitrogen use efficiency

Abstract Performance of cattle in rangeland systems is driven by the ability to efficiently use nutrients during periods of restricted availability. Thirty Bos indicus steers (398 ± 24 kg BW) were used to evaluate the relationship between feed efficiency (FE) and nitrogen use efficiency (NUE). The hypothesis was that FE would be related to NUE in protein restricted diets, but not in high-protein diets. Steers used in a completely randomized block design were classified by residual gain in low (LFE), medium (MFE) and highly feed efficient (HFE), after being fed for periods of 70 days with diets supplying either 70% (LP) or 100% (HP) of their rumen degradable protein requirements. After each 70-day period, animals were adapted to metabolism crates for two days, and NUE was measured for five days. About 10% of daily faecal and urine output of each animal was collected for N analysis. Results of N intake from LFE, MFE and HFE in the LP diet were 21.6, 21.2 and 22.2 g N/100 kg BW (P = 0.63), while the total N excretion was 20.3, 18.0 and 19.0 g N/100 kg BW (P = 0.45) for LFE, MFE and HFE, respectively. NUE values were 11.1, 26.9 and 28.0 g retained N/100 g of digested N (P = 0.04). In the HP diet, N intake was 31.6, 30.8 and 26.8 g/100 kg BW (P = 0.12) for LFE, MFE, and HFE, respectively. Total N excretion was 26.9, 28.8 and 27.5 g N/100 kg BW (P = 0.83), respectively. NUE in the HP diet was 21.0, 5.2 and -6.3 g retained N/100 g of digested N (P = 0.04). These results support the hypothesis that FE is dependent on NUE in protein restricted diets; whereas when evaluated in protein abundant diets, FE is not related to NUE.

Higher glycolytic capacities in muscle of carnivorous rainbow trout juveniles after high dietary carbohydrate stimulus at first feeding

BackgroundRainbow trout is a “glucose-intolerant” carnivorous species. Using the metabolic programming strategy, we used early nutritional stimuli in order to modify carbohydrate utilization in trout juveniles.MethodFish were fed two diets during the first feeding, namely HP (no carbohydrate / high protein) diet and LP (high carbohydrate / low protein) diet. HP diet was used as the control diet and LP diet as an early stimulus diet. We also used another early stimulus with fish fed HP diet every other day during the first feeding (HP restriction feeding - HPR). After the first-feeding stage (4 weeks), all fish were subsequently subjected to a growth trial with a commercial diet followed by a challenge test with the LP diet (11 weeks). At the end of the first feeding stimulus and of the challenge test, we investigated growth performance, glucose metabolism-related parameters and global DNA CmCGG methylation in trout.ResultsLP and HPR dietary stimuli have been a success as shown by the direct modifications of growth performance and mRNA levels for glucose metabolism-related genes at the end of first feeding compared to alevins fed the HP diet. At the end of the challenge trial, no variation in growth performance and hepatic metabolism of LP-history and HPR-history in trout juveniles were observed. However, in muscle of trout juvenile subjected to LP diet at the first feeding, we found an up-regulation of mRNA levels of some glucose metabolism (glucose transport and glycolysis)-related genes and an increase of activities of important glycolysis-related enzymes (hexokinase, phosphofructokinase and pyruvate kinase). These observations are associated with a decrease in the content of glycogen compared to fish fed the HP diet. Moreover, global CmCGG DNA methylation in the muscle of fish with LP history was significantly lower than those fed the HP diet.ConclusionDietary LP stimulus at first feeding could permanently modify glucose metabolism and global CmCGG DNA methylation level in muscle of trout juveniles, showing that the first feeding stage is efficient for programming the glucose metabolism in fish.