Terpenes and carbohydrate source influence rumen fermentation, digestibility, intake, and preference in sheep

We hypothesized that toxins and nutrients in foods interact to influence foraging behavior by herbivores. Based on this hypothesis we predicted that 1) terpenes in big sagebrush (Artemisia tridentata) influence intake and preference in sheep for diets varying in sources of nonstructural (barley grain) and structural (sugar beet pulp) carbohydrates, and 2) these effects are due to the differential effects of terpenes on fermentation products and apparent digestibility of each class of carbohydrates. Lambs were fed 2 isoenergetic and isonitrogenous diets with varying proportions of the same ingredients (beet pulp- and barley grain-based diet) or offered a choice between the 2 diets; all feeds were fed without and with terpenes, in consecutive periods. We also compared intake and preference of the beet pulp-and barley-based diets before and after the lambs ate a meal of sagebrush. Finally, we assessed the effect of terpenes on ruminal variables and in vivo digestibility. Lambs ate less when fed beet pulp or when they were offered a choice of diets with terpenes (P < 0.001), and intake of the beet pulp-based diet was the most affected (P < 0.05). Lambs preferred the beet pulp-to the grain-based diet with terpenes, but their preference reversed when terpenes were removed from the diets (P < 0.05). When lambs were offered both diets, intake and preference did not differ (P > 0.20) before eating sagebrush, but they preferred the beet pulp-based diet after eating sagebrush (P < 0.05). Intake of sagebrush did not differ among groups consuming the test diets (P = 0.21). Addition of terpenes to both diets increased the digestibility of DM, NDF, and ADF and decreased concentrations of total VFA and acetate (P < 0.05). Terpenes also depressed butyrate concentration in the barley-based diet (P < 0.05). Propionate concentrations were not affected by terpenes in either feed (P = 0.63). In summary, the predominant type of feed ingredient (beet pulp, grain) ingested with terpenes influenced fermentation products, intake, and preference in lambs. The source of energy from supplements, or other plants in the diet, is likely to influence intake and preference for sagebrush in sheep foraging on rangelands. Moreover, ingesting terpenes from sagebrush may also influence intake and preference for other plant species or supplements.     

Challenges with nonfiber carbohydrate methods

Nonfiber carbohydrates (NFC) encompass a compositionally and nutritionally diverse group exclusive of those carbohydrates found in NDF. Their content in feeds has often been described as a single value estimated by difference as 100% of dry matter minus the percentages of CP, NDF (adjusted for CP in NDF), ether extract, and ash. A calculated value was used because of difficulties with assays for individual NFC, but it does not differentiate among nutritionally distinct NFC. Errors in NFC estimation can arise from not accounting for CP in NDF and when multipliers other than 6.25 are appropriate to estimate CP. Analyses that begin to distinguish among NFC are those for starch, soluble fiber (non-NDF, nonstarch polysaccharides), and low molecular weight carbohydrates (mono- and oligosaccharides). Many starch analyses quantify alpha-glucans through specific hydrolysis of alpha-(1 --> 4) and alpha-(1 --> 6) linkages in the glucan, and measurement of released glucose. Incomplete gelatinization and hydrolysis will lead to underestimation of starch content. Starch values are inflated by enzyme preparations that hydrolyze carbohydrates other than alpha-glucan, measurement of all released monosaccharides without specificity for glucose, and failure to exclude free glucose present in the unhydrolyzed sample. Soluble fiber analyses err in a fashion similar to NFC if estimation of CP requires multipliers other than 6.25, or if contaminants such as CP and starch have not been properly accounted. Depolymerization and incomplete precipitation can also decrease soluble fiber estimates. The low molecular weight carbohydrates have been defined as carbohydrates soluble in 78 to 80% ethanol, which separates them from polysaccharides. They can be measured in extracts using broad-spectrum colorimetric assays (phenol-sulfuric acid assay or reducing sugar analysis of acid hydrolyzed samples) or chromatographic methods. Limitations of the colorimetric assays include lack of differentiation among mono- and oligosaccharides and differences in efficacy of measuring total carbohydrate. More sensitive and precise chromatographic methods require expensive equipment and specialized expertise. Current methods for NFC can separate nutritionally relevant fractions, but questions remain as to which fractions merit analysis and what analyses to use. These issues must be resolved in order to soundly evaluate and explore the roles of carbohydrates in diets.     

Use of low carbohydrate, high protein diets in cats with diabetes mellitus

The goal of this randomized, double‐blind study was to compare the effects of feeding a low carbohydrate, high protein diet versus a maintenance diet in a group of cats with diabetes mellitus treated with insulin glargine twice daily. All cats with naturally occurring diabetes mellitus not currently treated with insulin glargine or diabetogenic drugs or being fed a low carbohydrate, high protein diet were eligible for inclusion. Baseline testing included a physical examination, complete blood count, serum biochemistry profile, urinalysis and urine culture, serum thyroxine concentration, and serum fructosamine concentration. All cats were treated with insulin glargine (starting dose of 0.25 U/kg) twice daily. Insulin was adjusted as needed for glucose regulation. Cats were randomized to receive either a low carbohydrate, high protein diet or a feline maintenance diet. Re‐evaluations were performed on all cats at weeks 1, 2, 4, 6 and 10, and included an assessment of clinical signs, physical examination, 12‐h blood glucose curve, and serum fructosamine concentrations. Changes in continuous variables over the course of the study were analyzed using analysis of variance with repeated measures. p < 0.05 was considered statistically significant. Ten cats have completed the study. There were no significant differences between diet groups at baseline for age, gender, weight, body condition score, serum glucose or fructosamine concentrations. Although there was not a significant difference over time in clinical signs, insulin doses, or peak or nadir glucose concentrations between diet groups, diet did have a significant effect on serum fructosamine concentrations (p = 0.01). Six of the 10 cats that have completed the study achieved complete remission by the end of the study period, with no statistical difference between diets. The study's results indicate that diet can have significant effects on glucose regulation in cats receiving insulin glargine for treatment of feline diabetes mellitus.     

Effect of carbohydrate source on growth performance, carcass traits, and meat quality of growing-finishing pigs

Two experiments were conducted to determine the effect of substituting a more available dietary carbohydrate (CHO) for portions of corn or fat in the diet on growth performance, carcass traits, meat quality, and serum or plasma metabolites in growing-finishing pigs. A three-phase feeding program was used with corn-soybean meal diets formulated to provide 105% of the Lys requirement for barrows or gilts gaining 325 g of lean daily in Exp. 1 or gilts gaining 350 g of lean daily in Exp. 2. Diets were isoenergetic within experiments. All other nutrients met or exceeded suggested requirements. In Exp. 1, pigs were allotted to three dietary treatments (0, 7.5, or 15.0% sucrose), with three replications of barrows and three replications of gilts, and with three or four pigs per replicate pen; average initial and final BW were 25.2 and 106.7 kg. In Exp. 2, gilts were allotted to two dietary treatments (waxy [high amylopectin] or nonwaxy [75% amylopectin and 25% amylose] corn as the grain source), with five replications of four gilts per replicate pen; average initial and final BW were 37.7 and 100.0 kg. In Exp. 1, ADG and gain:feed ratio increased linearly (P < 0.02) as dietary sucrose increased. Minolta color scores, a* and b*, and drip loss (P < 0.06) also increased linearly with added sucrose. In Exp. 2, ADG, carcass weight and length, and the Minolta a* value were greater for pigs fed waxy corn (P < 0.08) than for those fed nonwaxy corn. Feed intake, longissimus muscle area, 10th-rib and average backfat thickness, dressing percentage, fat-free lean, percentage of lean and muscling, lean gain per day, total fat, percentage fat, lean:fat ratio, serum or plasma metabolites (Exp. 1: serum urea N; Exp. 2: serum urea N, and plasma nonesterified fatty acids, triacylglycerols, total and high-density lipoprotein cholesterol, insulin, and total protein), pH of the longissimus muscle, and subjective muscle scores (color, firmness-wetness, and marbling) were not affected by diet in either experiment. In summary, increasing availability of dietary CHO in growing-finishing pig diets improved growth performance, but it did not affect carcass traits.     

Energy utilisation of carbohydrate, fat and protein sources in newly hatched broiler chicks

1. TME, TMEn and metabolisability (TME/gross energy) of energy-yielding foodstuffs were determined in 1, 3 and 10 d old broiler chicks, using the assay method developed by Murakami et al. (1994), in order to characterise energy utilisation during the 10 d after hatching. 2. TME, TMEn and metabolisability of dextrin and starch were low in chicks aged 1 d, and increased with age up to 10 d. Energy values of glucose and maltose at days 1 and 3 could not be determined because of the sudden death of birds soon after the feeding. TMEn and metabolisability of cereal sources were lower in d-old chicks than in those aged 3 and 10 d. At all ages, maize was better utilised than wheat and sorghum. 3. In the fat sources (coconut oil, beef tallow and safflower oil) no age dependency was observed in TME, TMEn and metabolisability. 4. Bioavailability of soyabean meal and fish meal was lower at 1 d than at 3 d and 10 d. Energy utilisation from casein was the highest among the protein sources tested and it was not age dependent. 5. It is concluded that energy utilisation of carbohydrate and protein sources during 10 d post-hatch tended to increase with age. Among the energy yielding foodstuffs fat sources seem to be better utilised, with no age dependency.     

Recovery of duodenal villi and cells in chickens refed protein, carbohydrate and fat

1. To clarify how histological recovery of villi and cells would be affected after refeeding single nutrients such as protein, carbohydrate and fat, male chickens were divided as follows: (1) intact control fed ad libitum a commercial finisher mash diet (CP, 140 g; ME, 11.71 MJ/kg, ALM), (2) 3 d feed withdrawal (FW), (3) FW followed by one day ad libitum free access to the mash diet (FW-ALM), and FW followed by one day force-feeding of (4) a commercial finisher pellet diet (FW-FFM) and an isocaloric diet of (5) a protein (FW-FFP), (6) a carbohydrate (FW-FFC) or (7) a fat (FW-FFF). 2. After refeeding, the formula diet groups increased in villus height and villus area and tended to increase in cell area and cell mitosis. Furthermore, flat cells on the villus tip in the F group developed to dome-shaped cells. This suggests that nutritionally well-balanced diets can induce histological recovery at villus and cellular levels. 3. Not all of the single nutrient groups recovered to the extent of the formula diet groups in all light microscopic variables after refeeding, suggesting that a single nutrient cannot induce histological recovery of the villus. 4. However, the dome-shaped cells were more distributed on the villus tip in these single nutrient groups than in the well-balanced formula diet groups, although cell diameter of the former groups was smaller than that of the latter. This suggests that the single nutrients would be effectively absorbed from cells and can induce histological recovery at the cellular level.     

Biotyping of Haemophilus paragallinarum isolates using hemagglutinin serotyping, carbohydrate fermentation patterns, and antimicrobial drug resistance patterns

Three techniques, a hemagglutinin (HA) serotyping scheme, carbohydrate fermentation patterns, and antimicrobial drug resistance patterns, were used to examine 92 isolates of Haemophilus paragallinarum. The results were used to create biotyping schemes. The carbohydrate fermentation and antimicrobial drug resistance patterns each resulted in the identification of five biovars. With both of these techniques, a large majority of the isolates fell into one biovar: 81% were biochemical biovar I and 73% were antimicrobial biovar I. However, by combining the results of these techniques with those of the HA serotyping, a much greater discrimination could be achieved. The combined use of hemagglutinin serotyping, biochemical biotyping and antimicrobial biotyping appears to provide a suitable approach for epizootiological studies on infectious coryza.     

鱼类对饲料中糖的利用研究进展

糖类是鱼类饲料中廉价的能量源,然而,与陆生动物相比,鱼类对饲料中糖的利用能力较低。本文综述了这方面的最新研究进展,包括鱼类对饲料糖的利用能力与鱼饲料中糖的适宜含量、影响因素及鱼类的糖代谢机制。     

泥鳅幼鱼配合饲料中蛋白质、脂肪、糖类及纤维素的适宜含量研究

采用四因素三水平L_9(3~4)正交试验设计,制成蛋白质含量为25%、30%、35%,脂肪含量为4%、8%、12%,糖含量20%、25%、30%,纤维素含量1.6%~2.0%、2.0%~2.4%、2.4%~2.8%的9种泥鳅幼鱼配合饲料,进行为期38 d的饲养试验,以探讨初始体重为(1.23±0.09)g的泥鳅幼鱼配合饲料中蛋白质、脂肪、糖、纤维素的适宜含量。结果表明,各营养素对泥鳅幼鱼增重率、特定生长率、蛋白质效率的影响顺序为:蛋白质脂肪纤维素糖;当配合饲料中粗蛋白质为35%,脂肪为8%,糖为25%~30%,粗纤维为1.6%~2.0%时,泥鳅幼鱼的WGR、SGR最大,PER最高,FCR最小,CF各组间无显著差异(P0.05)。通过综合分析,在本试验条件下,蛋白质为主要营养素(P0.05),脂肪、纤维素、糖的作用并不明显(P0.05),泥鳅幼鱼配合饲料中蛋白质、脂肪、糖和纤维素的适宜含量分别为35%、8%、25%~30%、1.6%~2.0%。     

不同SC/NSC日粮对徐淮白山羊瘤胃发酵的影响

选取4只体况良好、体重(30±2.5)kg的徐淮白山羊,并安装永久性瘤胃瘘管,按4×4拉丁方设计,饲喂4种结构性碳水化合物(SC)与非结构性碳水化合物(NSC)比例不同的日粮(SC/NSC3.52、2.06、1.28、0.84),分别为A、B、C、D组,研究徐淮白山羊瘤胃发酵规律.结果表明D组瘤胃液pH值极显著低于其他3组(P＜0.01);D组瘤胃液氨氮浓度(NH3-N)极显著高于A、B组(P＜0.01);A组微生物蛋白(MCP)浓度极显著低于其他3组(P＜0.01);瘤胃液总挥发性脂肪酸(VFA)、乙酸及丙酸浓度,C组最高,但差异不显著(P＞0.05);D组丁酸浓度极显著高于A、B、C三组(P＜0.01);乙酸与丙酸之比差异不显著(P＞0.05).结果表明,SC/Nsc为1.28时徐淮白山羊瘤胃发酵最佳.     

Influence of dietary protein and carbohydrate sources on nitrogen metabolism and carbohydrate fermentation by ruminal microbes in continuous culture

Four diets containing 15% CP were formulated to study the effects of dietary carbohydrate and protein sources on N metabolism and carbohydrate fermentation by ruminal bacteria. Diets were supplied to eight dual-flow continuous culture fermenters during three experimental periods in a randomized complete block design. Six replications were obtained for each diet. Treatments were arranged as a 2 X 2 factorial with two carbohydrate and two protein sources. Carbohydrate sources were corn and barley and protein sources were soybean meal (SBM) and fish meal (FM). Approximately 40% of the dietary CP was derived from SBM or FM and corn or barley provided 39% of dietary DM. All diets contained 15% grass hay, 20% wheat straw, and 10.1 to 15.3% solka floc (DM basis). Interactions (P less than .05) were observed between dietary carbohydrate and protein sources, resulting in a depression of VFA production (moles/day) and digestion (percentage) of ADF and cellulose when the corn-FM diet was fed. True OM digestion (percentage) was higher (P less than .05) for SBM than for FM diets and for corn than for barley diets. Although dietary CP degradation (percentage) was higher (P less than .05) for SBM than for FM diets, non-NH3 N in the effluent (grams/day) was not different among diets due to a greater (P less than .05) bacterial N flow for SBM than for FM diets. Despite the lower amino acid (AA) intake (P less than .05) for corn than for barley diets and also for FM than for SBM diets, flows (grams/day) of total AA, essential AA (EAA), and nonessential AA (NEAA) were similar (P greater than .05) among diets. However, greater (P less than .05) total AA, EAA, and NEAA flows (percentage of AA intake) were found for corn than for barley diets and for FM than for SBM diets. It is concluded, therefore, that ruminal escape protein derived from corn or FM has a significant effect on manipulating AA leaving the ruminal fermentation.     

Effects of high and moderate non-structural carbohydrate hay on insulin, glucose, triglyceride, and leptin concentrations in overweight Arabian geldings

The objective of this study was to determine the effects of high and moderate non-structural carbohydrates (NSC) hay on insulin, glucose, triglyceride, and leptin concentrations in overweight Arabian geldings. Eight adult overweight (average BCS 7 [9-point scale]) Arabian geldings were fed each of two orchardgrass hays, high NSC (18% DM) and moderate NSC (12% DM), in a cross over design during two 28-day periods. Body weight and body condition score assessment along with blood sampling to measure insulin, glucose, leptin, and triglyceride concentrations were performed on days 0, 7, 14, 21 and 28 of each period. Effects of hay, period, day, and day*hay on plasma glucose and serum leptin were not detected. Serum insulin was influenced by hay (p = 0.001), day (p = 0.03), and day*hay (p = 0.04). Insulin concentrations were higher on day 7 in the high NSC group (15.6 μIU/ml) than the moderate NSC group (9.5 μIU/ml), but not by day 14 (p = 0.0007). Plasma triglyceride was influenced by period (p = 0.0003), day*period (p < 0.0001), and day*hay (p = 0.02). Hyperinsulinaemia was not observed in the overweight Arabian geldings fed either a moderate or high NSC hay.     

Estimation of quantitative oxidation and fat retention from carbohydrate,protein and fat in growing pigs

Die Oxidation von Nährstoffen und Retention von Kohlenhydraten, Protein und Fett hei wachsenden Schweinen Die Oxidation von Nährstoffen sowie deren Beitrag zur Fettretention wurde an Hand von 185 individuellen Bilanzstudien mit wachsenden Schweinen (40–100 kg Lebendgewicht) beurteilt. Der Respirationskoeffizient ohne Berücksichtigung des Proteins (RQnp) lag entweder unter oder über 1. Die beschriebene Methode basierend auf Gasaustausch sowie Kohlenstoff-Stickstoffbilanz zur Berechnung der Oxidation von Nährstoffen und Lipogenese ist in beiden Fällen gültig (RQnp > 1 und RQnp < 1). Bei einer den Wachstumsbedarf deckenden Energiezufuhr (ME ≥ 1,2 MJ/kg^0.75) ist die Oxidation von Nährstoffen im Bezug auf die Proteinretention abhängig von der Menge und Qualität des verdauten Proteins. Weiterhin besteht eine Abhängigkeit von der Menge an verdaulichen Kohlenhydraten. Die Versorgung mit Fett spielt dagegen keine Rolle. Die Oxidation von Kohlenhydraten trägt mit 85%, die von Protein mit 15% zur anfallenden Wärmeenergie bei. Eine Fettoxidation findet auch bei hohem Fettgehalt der Nahrung nicht statt. Die Lipogenese aus Kohlenhydraten stellt die Hauptquelle für die Körperfettretention dar. Da keine Fettoxidation stattfindet, wird das gesamte Nahrungsfett im Körper reteniert. Bei einer für das Wachstum zu geringen Energiezufuhr werden Nahrungsfett und Körperfett oxidiert. Um Protein für die Retention zu erhalten, ist die Oxidation von Protein vermindert. Selbst bei Mobilisierung von Körperfett und Oxidation von Nahrungsfett wird ein Teil der Kohlenhydrate und des Proteins für die Lipogenese vermutlich zum Aufbau von Strukturfett verwendet.     

Effects of dietary carbohydrate sources on plasma glucose, insulin and IGF-I levels in multiparous sows

Effects of different carbohydrate sources on plasma glucose, insulin and insulin-like growth factor-I (IGF-I) levels were compared to subsequently be able to study effects of insulin-stimulating diets on follicle development in sows. The following feed components were tested in 12 sows during six consecutive test periods of 9.5 days: dextrose (DEX), sucrose (SUC), lactose (LAC), dextrose plus lactose (DL), sucrose plus lactose (SL), dextrose plus sugarbeet pulp (DSBP) and control (CON). On day 2, 5 and 9 of each test period, plasma glucose (only at day 9), insulin and IGF-I profiles were determined. Despite similar glucose profiles for all diets, the postprandial insulin response was higher for DL and SL compared with CON and LAC; the other diets were intermediate. Plasma IGF-I levels were higher in CON, LAC and SL compared with DSBP, but differences were only marginal. It was concluded that dextrose and sucrose have the potential to stimulate fast and high insulin peaks, especially when combined with additional lactose. Despite the high dextrose in the DSBP diet, the insulin response was flattened, probably due to the viscosity of sugarbeet pulp. The results show that modulation of plasma insulin levels by dietary carbohydrates seems possible in anabolic sows, but IGF-I levels are less easily modified.