Low-starch Diet Research Articles

New Insights on Metabolic Syndrome: A “Silent” But Visible Epidemic

As surgeons, we evaluate varied problems, depending on our background and experience, but rarely make formal recommendations regarding the abnormalities observed in the metabolic syndrome (MS). The article by Ryan et al, from St. James Hospital/ Trinity College Dublin which appears in this issue of Annals of Surgery, linking proinflammatory changes with the extent of squamous intestinal metaplasia in a cohort of patients with Barrett epithelium focuses attention on a common problem that should be more widely addressed by the medical community. As a surgeon, I readily admit a focus on the “presenting problem” and not on broader questions of health maintenance; this article forced me to recognize that I should be more involved in finding ways to deal with MS, which affects 25% to 45% of the population, depending on ethnicity and sex, and has such a variety of consequences, associated risks, including cardiovascular disease, and an ever widening list of cancers. Metabolic syndrome qualifies as a public health epidemic, but its cluster of abnormalities does not command the kind of attention directed towards more visible problems such as the preventable diseases of childhood or chronic lead poisoning, with more easily defined and recognizable consequences; this is probably not the correct approach. Because many of the component physiologic abnormalities of MS are improvable (if not preventable) and directly affected by personal choices regarding lifestyle, diet, and exercise, greater emphasis should be placed on this condition. Obesity and hyperinsulinemia have been correlated with disease conditions for more than 20 years and defined more specifically of late as the metabolic syndrome. Specific details are defined by the World Health Organization, National Cholesterol Education Program, and the National Diabetes Federation (Table 1) who periodically update their definitions of these abnormalities. The weight parameter, readily apparent when viewing an American population, and lipid levels are more amenable to modification in some populations compared with others. In the rodent, a low fat, low starch diet is effective in reversing abnormalities of MS resulting from a high fat and high refined sugar diet. Eating habits in human subjects are more difficult to control, but a low fat/starch diet combined with daily exercise program can be effective, as shown most effectively in patients after bariatric surgery. As epidemiologic studies reveal additional risks of MS (increased incidence rate for cardiovascular disease, cancers, and other conditions), it becomes apparent modifiable risks deserve more attention. The present study on Barrett esophagus from Dublin shows an independent association between MS and the severity of Barrett esophagus (as defined by the extent of abnormal epithelium); the association of MS and immunoinflammatory changes with the extent of SIM is intriguing in light of our understanding of esophageal inflammation. That obesity and esophageal diseases are related is known, with published studies including an epidemiologic report from the Trinity group showing greatly increased numbers of esophageal adenocarcinoma in obese compared with nonobese individuals. Furthermore, gastroesophageal reflux disease (GERD) and erosive esophagitis are more common in the obese, and the most likely explanation for these findings is the likely effect of obesity in promoting GER, followed initially by inflammation and esophagitis, and later

Effects of dietary starch and energy levels on maximum feed intake, growth and metabolism of Nile tilapia, Oreochromis niloticus

The aim of this study was to gain insight into how Nile tilapia ( Oreochromis niloticus) regulate feed and energy intake in response to diets low and high in starch and cellulose. It was hypothesized that high-starch diets would reduce feed intake due to the effect of high blood glucose level, and that stomach volume may limit feed intake of fish fed diets low in energy. Four experimental diets, low starch–no cellulose inclusion, high starch–no cellulose inclusion, low starch–with cellulose inclusion, and high starch–with cellulose inclusion, were formulated. The high-starch diets and diets with cellulose inclusion were 17.5% more energy-diluted than the low-starch diets and diets without cellulose inclusion, respectively. Male tilapia were fed to apparent satiation for six weeks. Feed and digestible energy intake of fish fed diets with cellulose inclusion increased and decreased by 8.3% and 5.5%, respectively, compared to fish fed diets without cellulose inclusion. This suggests the role of stomach volume in restricting feed consumption. Fish fed high-starch diets achieved only 0.5% more feed intake and 13.9% less digestible energy intake than fish fed low-starch diets. The lower increase in feed intake and higher decrease in digestible energy intake of fish fed high-starch diets than of fish fed diets with cellulose inclusion suggests that high blood glucose suppresses feed intake in Nile tilapia. An alternative explanation for the differences in feed and digestible energy intake of fish fed different diets was based on the fact that heat production was not influenced by starch nor cellulose-inclusion levels. Thus, under satiation feeding, oxygen uptake capacity may determine feed and digestible energy intake in fish rather than blood glucose or stomach volume.

Diet and the evolution of human amylase gene copy number variation.

Starch consumption is a prominent characteristic of agricultural societies and hunter-gatherers in arid environments. In contrast, rainforest and circum-arctic hunter-gatherers and some pastoralists consume much less starch. This behavioral variation raises the possibility that different selective pressures have acted on amylase, the enzyme responsible for starch hydrolysis. We found that copy number of the salivary amylase gene (AMY1) is correlated positively with salivary amylase protein level and that individuals from populations with high-starch diets have, on average, more AMY1 copies than those with traditionally low-starch diets. Comparisons with other loci in a subset of these populations suggest that the extent of AMY1 copy number differentiation is highly unusual. This example of positive selection on a copy number-variable gene is, to our knowledge, one of the first discovered in the human genome. Higher AMY1 copy numbers and protein levels probably improve the digestion of starchy foods and may buffer against the fitness-reducing effects of intestinal disease.

“B27 Disease” Is a New Autoimmune Disease That Affects Millions of People

"B27 disease" is a new autoimmune disease that afflicts millions of people throughout the world. "B27 disease" occurs in individuals who have ankylosing spondylitis (AS) or preankylosing spondylitis and/or uveitis and are also positive for HLA-B27. Molecular mimicry between the bowel microbe Klebsiella and the HLA-B27 molecule, as well as the spinal collagens types I, III, and IV, indicates a pathological mechanism involving autoimmunity. Antibodies to Klebsiella microbes have been reported in AS patients from 18 different countries. Sera from patients with AS show complement-dependent cytopathic activity against sheep red cells coated with HLA-B27 peptide antigens. Diagnosis of B27 disease can lead to early treatment, involving low-starch diet, sulfasalazine, and immunosuppressive and biological agents so as to prevent the irreversible bony changes of established classical AS. The concept of B27 disease provides a new approach to the study and treatment of these disorders and needs to be evaluated in prospective studies by the world rheumatological community.

Application of Mathematical Models to Individually Allocate Feed of Group-fed Cattle

ABSTRACT A data set of group-fed growing and finishing steers with individual feed access was used to evaluate predictions of required individual DM by 2 mathematical models (Cornell Value Discovery System, CVDS; and beef NRC) to allocate feed of group-fed, commingled cattle. Forty-eight crossbred steers (BW = 296 kg) were assigned to 1 of 6 pens and fed 1 of 4 growing diets formulated to have different energy concentrations for restricted or ad libitum intake regimen for 56 d. The diets were a low-starch diet fed ad libitum, a high-starch diet fed ad libitum, a high-starch with restricted intake, and an intermediate diet fed ad libitum with an average energy intake between ad libitum low-starch and ad libitum high starch diets. On d 57, all steers (BW = 401 kg) were placed on the ad libitum high-starch diet for finishing until d 140. The CVDS was able to account for 61% of the variation in the observed DMI (oDMI) of steers during the growing period, and for 71% of the variation in oDMI during finishing, with an average overprediction of 3.76%. In the same fashion, the NRC model was able to explain 59% of the variation in oDMI after adjustment for known performance during the growing period with no bias (P > 0.10), and 57% of the variation in oDMI during the finishing period, with an average underprediction of 4.40%. Our overall evaluation suggested that the CVDS was more precise and accurate than the NRC model when predicting DMI for individual animals. Both models were sensitive to the previous level of nutrition of the cattle, suggesting that more variables are necessary to increase the prediction precision for cattle growing systems. The results from a risk analysis suggested that an amount of approximately $17.00/animal may be either over- or under-charged in the billing process of a commercial feedlot growing and finishing periods. Therefore, mathematical models could assist commercial feed-lots to improve the accuracy of the billing process while maintaining the same income per pen.

Luminal Substrate “Brake” on Mucosal Maltase‐glucoamylase Activity Regulates Total Rate of Starch Digestion to Glucose

Starches are the major source of dietary glucose in weaned children and adults. However, small intestine alpha-glucogenesis by starch digestion is poorly understood due to substrate structural and chemical complexity, as well as the multiplicity of participating enzymes. Our objective was dissection of luminal and mucosal alpha-glucosidase activities participating in digestion of the soluble starch product maltodextrin (MDx). Immunoprecipitated assays were performed on biopsy specimens and isolated enterocytes with MDx substrate. Mucosal sucrase-isomaltase (SI) and maltase-glucoamylase (MGAM) contributed 85% of total in vitro alpha-glucogenesis. Recombinant human pancreatic alpha-amylase alone contributed <15% of in vitro alpha-glucogenesis; however, alpha-amylase strongly amplified the mucosal alpha-glucogenic activities by preprocessing of starch to short glucose oligomer substrates. At low glucose oligomer concentrations, MGAM was 10 times more active than SI, but at higher concentrations it experienced substrate inhibition whereas SI was not affected. The in vitro results indicated that MGAM activity is inhibited by alpha-amylase digested starch product "brake" and contributes only 20% of mucosal alpha-glucogenic activity. SI contributes most of the alpha-glucogenic activity at higher oligomer substrate concentrations. MGAM primes and SI activity sustains and constrains prandial alpha-glucogenesis from starch oligomers at approximately 5% of the uninhibited rate. This coupled mucosal mechanism may contribute to highly efficient glucogenesis from low-starch diets and play a role in meeting the high requirement for glucose during children's brain maturation. The brake could play a constraining role on rates of glucose production from higher-starch diets consumed by an older population at risk for degenerative metabolic disorders.

Selection of Barley Grain Affects Ruminal Fermentation, Starch Digestibility, and Productivity of Lactating Dairy Cows

The objective of this study was to evaluate the effects of 2 lots of barley grain cultivars differing in expected ruminal starch degradation on dry matter (DM) intake, ruminal fermentation, ruminal and total tract digestibility, and milk production of dairy cows when provided at 2 concentrations in the diet. Four primiparous ruminally cannulated (123±69 d in milk; mean±SD) and 4 multiparous ruminally and duodenally cannulated (46±14 d in milk) cows were used in a 4×4 Latin Square design with a 2×2 factorial arrangement of treatments with 16-d periods. Primiparous and multiparous cows were assigned to different squares. Treatments were 2 dietary starch concentrations (30 vs. 23% of dietary DM) and 2 lots of barley grain cultivars (Xena vs. Dillon) differing in expected ruminal starch degradation. Xena had higher starch concentration (58.7 vs. 50.0%) and greater in vitro 6-h starch digestibility (78.0 vs. 73.5%) compared with Dillon. All experimental diets were formulated to supply 18.3% crude protein and 20.0% forage neutral detergent fiber. Dry matter intake and milk yield were not affected by treatment. Milk fat concentration (3.55 vs. 3.29%) was greater for cows fed Dillon compared with Xena, but was not affected by dietary starch concentration. Ruminal starch digestion was greater for cows fed high-starch diets compared with those fed low-starch diets (4.55 vs. 2.49kg/d), and tended to be greater for cows fed Xena compared with those fed Dillon (3.85 vs. 3.19kg/d). Ruminal acetate concentration was lower, and propionate concentration was greater, for cows fed Xena or high-starch diets compared with cows fed Dillon or low-starch diets, respectively. Furthermore, cows fed Xena or high-starch diets had longer duration that ruminal pH was below 5.8 (6.6 vs. 4.0 and 6.4 vs. 4.2 h/d) and greater total tract starch digestibility (94.3 vs. 93.0 and 94.3 vs. 93.0%) compared with cows fed Dillon or low-starch diets, respectively. These results demonstrate that selection of barley grain can affect milk fat production and rumen fermentation to an extent at least as great as changes in dietary starch concentration.

Dietary starch enhances the acetylation of histone and binding of Cdx‐2 and HNF‐1 on SI gene in the small intestine

Sucrase-isomaltase (SI) is expressed in the brush-border membranes in the small intestine and it participates in the final digestion of starch hydrolysates and sucrose. Many previous studies showed that the expression of SI gene was regulated by dietary starch. Cell studies indicated that gene expression of SI is regulated by HNF-1 and Cdx-2, which are homeodomain proteins working as transcription factors. However, it is unknown whether SI gene expression is regulated by HNF-1 and Cdx-2 in vivo. To examine physiological relevance of SI gene regulation by HNF-1 and Cdx-2, we performed chromatin immunoprecipitation (ChIP) assay using antibodies of HNF-1 and Cdx-2 in mice which were fed a high starch diet (carbohydrate 70 energy %) or a low starch diet (carbohydrate 5 energy %) for 7 days. The ChIP signals of HNF-1 and Cdx-2 were detected using the promoter region but not the cording region in the rats fed a low starch diet. Moreover, the ChIP signals of Cdx-2 and HNF-1 on SI promoter region of SI were enhanced in the rats fed a high starch diet compared with those fed a low starch diet. Furthermore, the acetylation of histone H3 interacting with the SI promoter and cording regions were also enhanced in the rats fed a high starch diet. Our study suggests that the induction of SI gene in the rats fed a high starch diet are regulated not only by the binding of HNF-1 and Cdx-2 but also by acetylation of histone H3 interacting with the SI gene.

Influence of Rumen Escape Starch on ??Amylase Activity in Pancreatic Tissue and Small Intestinal Digesta of Lambs

Two slaughter experiments were conducted to determine the effects of rumen escape starch, by altering dietary starch concentration and corn particle size, on ??amylase activity in the pancreas and the small intestinal digesta of lambs. In experiment 1, 18 wether lambs (28.5??.6 kg) were fed low, medium or high starch diets for 35 d and slaughtered. Dietary starch concentrations linearly increased rumen escape starch (p<0.05). Pancreatic ??amylase activity was lower (p<0.05) in lambs fed the low starch diet. When expressed per gram of digesta, ??amylase activity was lower in lambs fed the low starch diet. However, expressed as total activity, ??amylase in the digesta was greater in lambs fed the medium starch diet. In experiment 2, 12 wether lambs (23.5??.3 kg) were fed diets with finely cracked corn, coarsely cracked corn and whole corn. These dietary treatments continued for 35 d before tissue collection. Rumen escape starch increased with increasing corn particle size (p<0.05). ??Amylase activity in the pancreas and the small intestinal digesta was significantly greater (p<0.05) in lambs fed the coarsely cracked corn. These data suggest that increasing rumen escape starch results in a quadratic increase in total ??amylase activity in the pancreas and the small intestinal digesta. Maximum ??amylase activity is reached when rumen escape starch is about 100-120 g/d in 25-30 kg lambs.

A possible link between Crohn’s disease and ankylosing spondylitis via Klebsiella infections

Crohn's disease (CD) is an immune-mediated gastrointestinal inflammatory disease, which could arise from an interplay between genetic and environmental factors. Klebsiella microbes were suggested to have a vital role in the initiation and perpetuation of the disease through the mechanism of molecular mimicry. This proposition is based on the results of various studies where significantly elevated levels of antibodies against the whole bacteria or preparations from Klebsiella microbes and antibodies to collagen types I, III, IV, and V were detected in patients with CD and patients with ankylosing spondylitis (AS). Molecular similarities were found between Klebsiella nitrogenase and HLA-B27 genetic markers and between Klebsiella pullulanase and collagen fibers types I, III, and IV. Furthermore, significantly positive correlations and cross-reactivity binding activities were observed between anti-Klebsiella and anticollagen antibodies among patients with CD and AS. Early treatment of CD patients with anti-Klebsiella measures is proposed, which may involve the use of antibiotics and low starch diet together with other traditionally used immunomodulatory, immunosuppressive, or biologic agents.

Ankylosing Spondylitis, HLA-B27 and Klebsiella - An Overview: Proposal for Early Diagnosis and Treatment

Ankylosing spondylitis (AS) is a potentially disabling rheumatic disease for which no curative treatment has yet been discovered. An extensive computer-based and manual search was undertaken to evaluate the role of microbes in the pathogenesis of AS. All together 147 papers were scrutinised. A total of 24 studies carried out on 1330 AS patients and 1191 healthy controls involving 15 different countries showed significantly elevated Klebsiella antibodies in AS patients when compared to controls. Molecular analysis has shown that Klebsiella microbes possess antigens, which cross-react with self-antigens, such as HLA-B27 and spinal collagens. Diagnostic criteria have been developed in which a person who is HLA-B27 positive and has clinical and laboratory evidence of an inflammatory backache for at least three months is proposed to have pre-AS. A specific elevation of anti- Klebsiella antibodies would confirm the diagnosis. A proposal for an early treatment using anti-Klebsiella measures is suggested. So far, apart from Klebsiella no other microbes have been shown to have a link with the development of AS. It is suggested that identifying and treating patients with Klebsiella reactive arthritis/pre-AS could involve the use of anti- Klebsiella measures, such as antibiotics and low starch diet together with immunosuppressive drugs in an endeavour to prevent the irreversible sequelae of established AS. Keywords: Ankylosing spondylitis, HLA-B27, Klebsiella, new diagnostic marker

Nutritional supplements in support of equine welfare

In the wild, the horse would spend most of the day roaming and foraging in an externally variable environment as part of a herd. As non-ruminant herbivores they are well suited to a high fibre, low starch diet. They rarely fast voluntarily for more than 2 –4 hrs at a time and would naturally forage for 16-18hrs a day. Modern horse management often brings the horse into a small enclosed, isolated environment and limits the feeding occasions. What and when they are able to eat, is now predominantly determined by ourselves and we therefore have to take responsibility for the effects of our choice of management practices on their health and welfare. It is becoming increasingly apparent that some of these practices may not be optimal for the welfare of horses (Davidson and Harris 2003).Animal welfare has been defined ecologically as the good fit of an animal to its environment (Kronfeld et al 1998).

Dietary Sucrose Enhances Intestinal Lactase Gene Expression in Euthyroid Rats

It is postulated that dietary carbohydrates and thyroid hormones are major regulators for expression of the lactase/phlorizin hydrolase (LPH) gene in rat jejunum. In this study, we investigated the effects of thyroid hormones and dietary sucrose on LPH gene expression and lactase activity in starved rats. Firstly, animals at 8 wk of age were fed a low-starch diet (5.5% energy as cornstarch) or high-starch diet (71% energy as cornstarch) for 7 d (experiment 1). The mRNA level of LPH as well as lactase activity significantly decreased in rats fed the low-starch diet as compared to those fed the high-starch diet. To investigate the effects of thyroid hormone status, the animals previously fed the low-starch diet were starved for 3 d, and half of the animals were given intraperitoneal (i.p.) injections of 20 microg/ 100 g body weight triiodothyronine (T3) twice daily (experiment 2). The LPH mRNA level and lactase activity were elevated by starvation for 3 d, but they were repressed by the injection of T3 during starvation. To investigate the effects of dietary sucrose in starved rats, they were force-fed a sucrose diet for 6 h (experiment 3). The LPH gene expression and lactase activity were up-regulated by force-feeding a sucrose diet, only when the animals were kept in euthyroid status by daily T3 administrations. In contrast, the sucrase-isomaltase mRNA levels and sucrase activity were unaffected by force-feeding the sucrose diet for both T3-treated and untreated starved rats. Our work suggests that dietary sucrose is capable of enhancing lactase gene expression in starved rats when they have a sustainable thyroid hormone level.

P2-14 Impact d’une hospitalisation de courte durée (< 30 jours) sur le fardeau ressenti par les aidants de patients souffrant de syndrome démentiel

Rehydrated and ensiled mature ground corn has high ruminal starch digestibility, but particle size (PS) and dietary starch proportion (ST) can affect starch digestion and lactating cow performance. We evaluated the effect of rehydrated and ensiled corn (REC), PS, and ST on intake, lactation performance, nutrient digestibility, ruminal fermentation profile, and chewing behavior of dairy cows. Kernels from an 84% vitreousness hybrid were finely (FN) or coarsely (CS) ground, yielding geometric mean particle sizes of 1,591 and 2,185 µm, respectively. Ground kernels were rehydrated [60% dry matter (DM)] and ensiled in 200-L buckets for ≥205 d. The grinding rate (t/h) was 3.9 for FN and 11.7 for CS. The PS did not affect DM loss (11.3% of ensiled) or silage pH (3.8). Samples of each bucket (n = 15/PS) before and after silage fermentation were incubated in situ for 0, 3, 6, 18, and 48 h in 4 rumen-cannulated lactating cows. Ensiling increased the effective ruminal in situ DM degradation (63.7 vs. 34.1%), regardless of PS. Sixteen Holstein cows (152 ± 96 d in milk) in 4 × 4 Latin squares (21-d periods) were individually fed a 2 × 2 factorial combination of low (LO) or high (HI) starch diets with FN or CS. Cows were fed the same REC incubated in situ. Varied concentration of starch in the diet (29.2 vs. 23.5% of DM) was achieved by partial replacement of REC (22.0 vs. 14.2% of DM) with citrus pulp (0 vs. 8.2% of DM). Milk, protein, fat, and lactose yields did not differ. Milk fat percentage was reduced and protein percentage was increased by HI. Treatment FN increased feed efficiency (energy-corrected milk/digestible organic matter intake) when fed with HI. Total-tract starch digestibility tended to be reduced by CS (96.4 vs. 97.2% of starch intake). Serum β-hydroxybutyrate was increased by LO. High-starch diet reduced the molar proportions of acetate and butyrate in ruminal fluid and increased propionate and isoacids. Particle size did not affect ruminal fermentation profile. Coarse grinding reduced plasma d-lactate concentration with HI. Diet HI reduced the proportion of daily intake from 1900 to 0700 h and induced preferential intake of feed particles <8 mm and greater refusal of particles >19 mm in the morning. Fine REC reduced rumination time per day and increased eating time per DM intake. Milk and plasma urea-N did not differ. Ensiling of mature flint corn for >200 d largely eliminated the effect of the PS of REC on the studied outcomes. The proportion of REC in the diet affected ruminal fermentation profile and milk solids concentration, but did not affect short-term performance and digestibility. Coarse grinding of REC may allow increasing the grinding rate and thus save labor and energy during ensiling.

Incidence of puberty in beef heifers fed high- or low-starch diets for different periods before breeding1

Spring-born Hereford x Angus heifers (n = 206) were used to determine effects of energy supplementation programs and amount of starch in the diet on incidence of puberty. In Exp. 1, heifers (205 +/- 5 kg; n = 68) grazing dormant native pasture were fed 0.9 kg/d (as-fed basis) of a 42% CP supplement from November until February 14. Heifers were stratified by weaning weight and allotted randomly to treatment before breeding (May to July). Treatments were 1) 0.9 kg (as-fed basis) of a 42% CP supplement/d and pasture (control); 2) a high-starch (HS) diet (73% corn; 53% starch) fed in a drylot for 60 d (HS-60); 3) a HS diet fed in drylot for 30 d (HS-30); or 4) a low-starch (LS) diet (49% corn; 37% starch) self-fed on pasture for 30 d (LS-30). The HS-60 and HS-30 heifers were limited-fed to gain 0.9 kg/d, and the LS-30 heifers had ad libitum access to the diet. High-starch-60 and LS-30 heifers were heavier (P < 0.05) than control and HS-30 heifers at the beginning of the breeding season. Thirty-one, 25, and 26% more HS-60 heifers were pubertal (P < 0.05) on May 1 compared with LS-30, HS-30, and control heifers, respectively. At puberty, HS-60 heifers were 24 and 22 d younger (P < 0.05) than LS-30 and control heifers, and 31 kg lighter (P < 0.01) than LS-30 heifers. In Exp. 2, heifers grazed dormant pasture and were fed 0.9 kg (as-fed basis) of a 42% CP supplement/d from weaning in October to late February; then heifers were assigned randomly to treatments for 60 d before the breeding season. In two years, control heifers (n = 46) grazed pasture and received 0.9 kg of SBM supplement/d; LS (n = 46) heifers were self-fed a distiller's grain and soybean hull-based diet in drylot; and HS heifers (n = 46) were limited-fed a corn-based diet in drylot. During treatment, HS and LS heifers had greater weight gains than control heifers. Pubertal BW (313 +/- 6 kg) was not influenced by treatment, but HS and LS heifers were younger (P < 0.03) than control heifers at puberty. During a 60-d breeding period, the incidence of puberty was greater (P < 0.05) for HS and LS heifers than for control heifers and was greater (P < 0.05) in HS than in LS heifers in Year 1. Feeding a LS or a HS diet for 30 d before breeding may be inadequate to stimulate puberty in beef heifers, but feeding a diet with a greater amount of starch for 60 d before breeding may increase the incidence of puberty during breeding of heifers that have inadequate yearling weight.

Options for reducing the negative effects of nitrogen in agriculture

After addition to farms by fertilizer, crop residues, biological fixation and animal excreta, nitrogen can be lost through gaseous emission, runoff and leaching to contaminate the atmosphere and water bodies, and cause adverse health effects. The efficiency of fertilizer nitrogen can be increased and losses reduced, by matching supply with crop demand, optimizing split application schemes, changing the form to suit the conditions, and use of slow-release fertilizers and inhibitors. In addition, agronomic practices such as higher plant densities, weed and pest control and balanced fertilization with other nutrients can also increase efficiency of nitrogen use. Efficiency of use by animals can be increased by diet manipulation. Feeding dairy cattle low degradable protein and high starch diets, and grazing sheep and cattle on grasses high in water soluble carbohydrate result in less nitrogen excretion in urine and reduced ammonia volatilization.

Influence of starch intake on growth and skeletal development of weanling horses1,2

Forty-four weanling horses were used in two experiments to evaluate the effect of starch intake on growth and skeletal development. In Exp. 1, the weanlings were fed either a grain-based, high-starch (31.1%, DM basis) concentrate or a by-product-based, low-starch (0.0%) concentrate with coastal bermudagrass (Cynodon dactylon) hay. Corn oil was used to equalize the energy concentration of the concentrates. The concentrate:hay ratio was 64:36 (as-fed basis), and intake was the same for both diets. Body weight gains were greater by the weanlings consuming the high-starch concentrate (0.81 vs. 0.67 kg/d; P = 0.01). Total body length gain also was greater for the weanlings consuming the high-starch concentrate (15.5 vs. 13.2 cm; P = 0.045). Other body measurements and bone mineral deposition were not influenced by diet or gender. At the end of the experiment, postprandial blood glucose concentrations suggested that the horses on the low-starch diet were less efficient in metabolizing blood glucose than were those that had been consuming the high-starch diets. In Exp. 2, the weanlings were fed either a high-starch (34.7%) or medium-starch (17.0%) concentrate plus coastal bermudagrass hay. Corn oil again was used to equalize the energy content of the medium-starch concentrate to that of the high-starch concentrate. The concentrate:hay ratio was 64:36 (as-fed basis), and the intake was the same for both diets. The diets did not influence rate of gain (0.75 kg/d; P = 0.98), body measurements (P = 0.11 to 0.93), or bone mineral deposition (P = 0.66). Animals on the medium-starch diet tended to have blood glucose concentrations that peaked earlier and were lower at later times than those consuming the high-starch concentrate. Bone osteochondrotic lesions were not related to the diet and were found to decrease during the course of the experiment for both the high-starch and the medium-starch diets (P = 0.006 and 0.016, respectively).

Influence of dietary starch contents on milk composition of Friesian cows in early lactation

The aim of this research was to evaluate the effect of the modification of diet starch content on milk composition and on its nitrogen and mineral fractions. Ten Italian Friesian primiparous cows were randomly assigned to two groups and fed a basal total mixed ration, (BSD, basal starch diet, 24.9% starch/DM) until 42 days in milking (DIM). At 43 DIM, 5 animals (control group, CTR) continued to receive the same ration and the remaining 5 cows (experimental group, EXP) were fed a low starch diet (LSD, 21.0% starch/DM) until 65 DIM, followed by a high starch diet (HSD, 28.3% starch/DM) 66 to 85 DIM. From 86 DIM until 94 DIM, cows of the EXP group returned to the BSD. Milk samples were collected at 37, 50, 60, 70, 80, 94 DIM. Starch intake was lower for EXP at DIM 50, 60 and higher at 70 and 80 DIM (P < 0.01). Milk yield and fat corrected milk (FCM) did not vary between groups and times of sampling, but HSD caused a significant (P < 0.05) reduction of milk fat in the EXP animals. NPN and MUN contents were affected by dietary treatments at 80 DIM (P < 0.05), being higher in CTR and lower in EXP group in comparison to their basal values (37 DIM). The αs1-casein percentages at 80 and 94 DIM increased in the EXP but not in the CTR group, and a marked decrease of αs2-casein percentage for the EXP group at 94 DIM was observed (P < 0.05). Milk sodium content decreased at 80 and 94 DIM and the sodium to potassium ratio was reduced after the return to the basal diet in the EXP group (94 DIM), indicating that dietary starch variations can be involved in the control of epithelium integrity of mammary gland in early lactation.

Oxidative stress in primiparous cows in relation to dietary starch and the progress of lactation

AbstractOxidative stress may be important in early lactation cows due to high metabolic demands. Modifying dietary starch may alter glucose utilization, modify oxidative metabolism and, consequently, increase oxidative stress. To test this hypothesis, early lactation primiparous cows underwent a short-term dietary starch restriction followed by realimentation. At calving, 10 Friesian primiparous cows were randomly assigned to two groups and given a basal starch diet (BSD, 249 g/kg of starch dry matter (DM)) in the form of a total mixed ration until 42 days in milk (DIM). Afterwards, five cows (CTR) continued to receive the same diet and five cows (EXP) were allotted to experimental diets: low starch diet (LSD, 210 g/kg starch DM) from 43 to 65 DIM followed by high starch diet (HSD, 283 g/kg starch DM) from 66 to 85 DIM and BSD from 86 to 94 DIM. Blood samples were collected at 37, 50, 60, 70, 80, and 94 DIM to measure total plasma glutathione (GSH), thiobarbituric acid reactive substances (TBARS), and erythrocyte glutathione peroxidase (GPx) activity as indicators of oxidative stress, N-acetyl-ß-D glucosaminidase (NAGase), lysosyme, and white blood cell counts as indicators of immune response. Metabolic adaptations were evaluated by glucose, non-esterified fatty acids (NEFA), beta-hydroxy-butyrate (BOHB), insulin, and GH concentrations, and the acid/base balance. Milk yield was not significantly different between groups throughout the experiment and was correlated with TBARS (r 0·284; P 0·05) and GSH (r = 0·294; P 0·05). Estimated energy intake was significantly higher in the EXP group at 70 DIM only (P 0·05). Plasma glucose was significantly lower in the EXP group at 50, 60 (P 0·001) and 80 DIM (P 0·05), and was correlated with GSH (r = 0·348; P 0·01) and TBARS (r = 0·367; P 0·01). Plasma NEFA decreased overall in both groups (P 0·01). EXP was lower than CTR in concentrations of plasma BOHB at 70 DIM (P 0·05) and plasma insulin at 60 (P 0·001), 80 and 94 (P 0·05) DIM. Plasma TBARS, GSH and GPx increased throughout (P 0·01) in both groups. This was delayed in the EXP group following introduction of LSD; significant differences between groups at 60 (P 0·01), 80 and 95 (P 0·05) DIM for TBARS, and at 70 (P 0·01) and 80 (P 0·05) DIM for GPx. Indicators of immune response and plasma bicarbonates did not differ between groups. Blood pH was significantly lower in the EXP group at 80 and 94 DIM (P 0·001). Blood pCO2 was significantly lower at 80 and 94 DIM (P 0·05) in the CTR group. While recovering from the negative energy balance, cellular metabolism probably shifted towards oxidative phosphorylation, with a consequent oxidative stress increase. LSD delayed this recovery in the EXP group and thus reduced GSH synthesis. In conclusion, the diet starch content may alter the control of oxidative stress and expose animals to oxidative injuries.

Effects of dietary energy and starch concentrations for newly received feedlot calves: I. Growth performance and health.

Crossbred calves (n = 572; initial BW = 186 +/- 27 kg) purchased from northern Texas, Arkansas, and southeast Oklahoma auction markets were delivered to the Willard Sparks Beef Research Center, Stillwater, OK, and used to study the effects of dietary energy and starch concentrations on performance and health of newly received feedlot calves during a 42-d receiving period. On arrival, calves were assigned randomly to one of two dietary energy levels (0.85 or 1.07 Mcal NEg/kg DM) and one of two dietary starch levels (34 or 48% of ME from starch) in a 2 x 2 factorial arrangement of treatments. Cattle were weighed and serum samples were collected on d 0, 7, 14, 28, and 42. Individual animal records of morbidity were kept for all cases of respiratory and other disease. Nasal swabs were collected from each morbid animal and cultured for upper-respiratory pathogens. There were no energy x starch level interactions for performance or health response variables. Daily gain (1.14 kg/d) and gain efficiency (ADG:DMI = 0.179) were not affected by increasing dietary energy or starch concentrations. Calves fed low-energy diets consumed (P < 0.05) more DM. No difference (P = 0.54) was detected in morbidity for calves fed high-energy (62.4% calves treated) compared with low-energy (65.8% calves treated) diets; however, calves fed the high-starch diets had numerically (P = 0.11) greater morbidity than calves fed low-starch diets (68.8 vs. 59.4% calves treated, respectively). There were no energy or starch effects on Mannheimia haemolytica or Pasteurella multocida antibody titers; however, day effects (P < 0.02) occurred. On d 7, 14, and 28, calves had antibody titers for P. multocida that were greater (P < 0.05) than titers on d 0. In addition, calves had greater antibody titers to M. haemolytica on d 7 and 14 than on d 0. Nasal swabs revealed that calves fed the high-energy diets tended (P = 0.06) to have a lower percentage of morbid calves with P. multocida during the first antimicrobial treatment and a lower percentage of Haemophilus somnus isolates during the first (P = 0.01) and second (P = 0.06) antimicrobial treatments than calves fed the low-energy diets. Although animal performance was not influenced, the present data suggest that feeding the high-energy diet decreased the percentage of P. multocida and H. somnus pathogens in calves that received one or more antimicrobial treatments.