Total Tract Organic Matter Research Articles

Comparison of methane production between C3 and C4 grasses and legumes

A meta-analysis was conducted to compare effects of C4 and C3 grasses as well as warm and cold climate legumes on CH4 production of ruminants. For this purpose, a database was built using 22 in vivo studies containing 112 observations with 58 C3 grasses, 28 C4 grasses, 26 cold legumes and 12 warm legumes. Neutral detergent fibre (NDF), crude protein (CP) and total tract organic matter (OM) digestibility ranged from 415 to 753g/kgDM versus 361 to 754g/kgDM, from 24 to 254g/kgDM versus 44 to 314g/kgDM and from 0.51 to 0.71 versus 0.56 to 0.83 for C4 and C3 grasses, respectively. The NDF, CP and total tract OM digestibility ranged from 441 to 690g/kgDM versus 252 to 684g/kgDM, from 93 to 236g/kgDM versus 141 to 269g/kgDM and from 0.42 to 0.57 versus 0.38 to 0.79 for warm and cold legumes, respectively. Relationships between CH4 production and forage characteristics were analysed by analysis of covariance. For grasses, the main factors tested as fixed effects were NDF and CP content of the diet, total tract OM digestibility, intake, animal species, forage family and random trial effect. For legumes, tannin level was included in the model. Results indicate that ruminants fed C4 grass produced 17% more CH4 as L/kg OM intake (P<0.05) compared to those fed C3 grass. Animals fed warm legumes produced 20% less CH4 (P<0.05) than those fed C4 grasses. In contrast, no difference in CH4 production between C3 grasses and cold legumes. Use of some legumes in warm climates could be a strategy to reduce CH4 emissions by ruminants.This paper is part of the special issue entitled: Greenhouse Gases in Animal Agriculture – Finding a Balance between Food and Emissions, Guest Edited by T.A. McAllister, Section Guest Editors: K.A. Beauchemin, X. Hao, S. McGinn and Editor for Animal Feed Science and Technology, P.H. Robinson.

Characterization of ruminal dynamics in Holstein dairy cows during the periparturient period

We used four pregnant Holstein cows to delineate ruminal adaptations as cows transitioned from one lactation to the next. Cows were fed typical diets through far-off and close-up dry periods and lactation. We measured ruminal characteristics on day 72 (late lactation), 51 (far-off dry), 23 and 9 (close-up dry) prepartum and on days 6, 20, 34, 48, 62, 76 and 90 postpartum (early lactation). Measurements included: ruminal fill (weight of actual contents), ruminal capacity (volume of rumen when fully filled), digestibilities and ruminal passage rates. Ruminal capacity tended to increase linearly during early lactation but was stable during dry and transition periods. Both total and liquid fill decreased linearly during the dry period, increased across parturition, and increased linearly through early lactation. Dry matter fill decreased as cows were fed the close-up diet at day 23 prepartum then increased near parturition and continued to increase across early lactation. Solid passage rate was greatest when cows were fed the close-up diet, and decreased throughout the transition period. In lactation, solid passage rate responded quadratically with peak at day 48 followed by decreases through day 90 postpartum. Liquid passage increased linearly across the transition period. Total tract organic matter digestibilities increased linearly over the dry period with significant increases prior to or immediately after parturition, then they remained relatively stable over early lactation until they increased at day 90. Fibre digestibilities demonstrated quadratic responses over early lactation, being higher on day 6 and day 90 than at other times. Starch digestibilities decreased linearly across both the dry and transition periods with decreases in lactation until day 62 followed by increases until day 90. High producing lactating dairy cows go through a multitude of ruminal adaptations, in terms of digestion, passage, capacity and fill, as they transition from one lactation to the next.

Quantifying ruminal digestion of organic matter and neutral detergent fiber using the omasal sampling technique in cattle—A meta-analysis

A data set from 32 studies (122 diets) was used to evaluate the accuracy and precision of the omasal sampling technique by investigating the relationships between ruminal and total digestion of neutral detergent fiber (NDF), between intake and apparent and true ruminal digestion of organic matter (OM), and between omasal NAN flow and milk protein yield. A mixed model regression analysis with random study effect was used to evaluate the relationships. The data were obtained when feeding North American diets (n=36) based on alfalfa silage, corn silage, and corn grain and North European diets (n=86) comprising grass silage supplemented with barley-based concentrates. In all studies, digesta flow was quantified using a triple-marker approach. Standard deviations of ruminal NDF and true OM digestibility were smaller than typically reported in duodenal sampling studies using only chromic oxide as a flow marker. The relationship between total and ruminal NDF digestion was consistent, indicating little variation in the proportion of total-tract NDF digestion that occurred in the rumen. Furthermore, the slope of this regression indicated that 94.7% (±2.7%) of total NDF digestion occurred in the rumen. The slopes of mixed model regression equations between OM intake and amount digested indicated that 42% (±2.4%) and 74% (±3.1%) of OM was apparently and truly digested in the rumen, respectively. The contribution of the rumen to total-tract apparent OM digestion was 62% (±2.6%). The close relationship between omasal flow of nonammonia crude protein and milk protein yield (with adjusted residual mean squared error=31g) provided further confidence in the reliability of omasal flow measurements.

Barley and oat cultivars with diverse carbohydrate composition alter ileal and total tract nutrient digestibility and fermentation metabolites in weaned piglets

An experiment was conducted to evaluate the effects of cereal carbohydrate form (isolated v. cereal matrix) and level, especially mixed-linked β-glucan (hereafter referred to as β-glucan) and starch amylase/amylopectin ratio on nutrient digestibility and fermentation parameters in the intestines of weaned pigs. Four hulless barley cultivars containing varying β-glucan levels (41 to 84 g/kg) were compared with hulled barley, supplemented or not with a β-glucan concentrate (BBG; 270 g/kg β-glucan) and two oat cultivars for digestibility and fermentation metabolites. Seventy-two weaned piglets (BW = 12.8 ± 1.9 kg) were assigned to one of nine diets composed of 815 g/kg cereal, 60 g/kg whey, 90 g/kg soy protein isolate and 35 g/kg minerals. After 15 days, the pigs were killed, and digesta collected from ileum and colon were analyzed for proximate nutrients, short-chain fatty acids (SCFAs), lactic acid (LA) and ammonia. Ileal and total tract digestibility of proximate nutrients and non-starch polysaccharides (NSPs) were determined using HCl-insoluble ash as a marker. Organic matter (OM) ileal digestibility was greater (P < 0.05) for diets based on hulless barley (77% ± 1.1% on average), as compared with hulled barley (64% ± 1.4%) and oat (58% ± 1.5%). Similar trends were found for total tract OM digestibility, varying from 90% ± 0.3% for hulless barley to 67% ± 0.4% for oat, on average. NSP digestibility differed (P < 0.05) within and between cereal types, ranging from 20% (hulled barley plus 163 g/kg BBG or ∼40 g/kg β-glucan) to 51% (SB94893 hulless barley cultivar with high β-glucan and high amylose ratio) at the ileum and from 44% (hulled barley) to 84% (SB94893 cultivar) at the total tract level. No dietary effect (P > 0.05) was found for SCFA concentration in ileal contents, whereas in colonic contents, SCFA was lower in pigs fed oat (P < 0.001). LA concentration was greater (P < 0.001) in the colon of pigs fed hulless barley than in pigs fed hulled barley and oat. Expressed per kg carbohydrate (NSP + starch) fermented, the ammonia concentration at the colon was lowest for hulled barley diets (supplemented with β-glucan) and the highest for oat diets. In conclusion, the interaction of both form and level of β-glucan impacted nutrient digestibility and fermentation. Hulless barleys with high soluble NSP such as β-glucan and resistant starch yielded, in general higher SCFA and LA and lower ammonia. Hulless barleys may, therefore, have potential for use in feeding strategies designed to improve gut health in pigs.

Effect of lauric acid and coconut oil on ruminal fermentation, digestion, ammonia losses from manure, and milk fatty acid composition in lactating cows

This experiment (replicated 3×3 Latin square design) was conducted to investigate the effects of lauric acid (LA) or coconut oil (CO) on ruminal fermentation, nutrient digestibility, ammonia losses from manure, and milk fatty acid (FA) composition in lactating cows. Treatments consisted of intraruminal doses of 240g of stearic acid/d (SA; control), 240g of LA/d, or 530g of CO/d administered once daily, before feeding. Between periods, cows were inoculated with ruminal contents from donor cows and allowed a 7-d recovery period. Treatment did not affect dry matter intake, milk yield, or milk composition. Ruminal pH was slightly increased by CO compared with the other treatments, whereas LA and CO decreased ruminal ammonia concentration compared with SA. Both LA and CO decreased protozoal counts by 80% or more compared with SA. Methane production rate in the rumen was reduced by CO compared with LA and SA, with no differences between LA and SA. Treatments had no effect on total tract apparent dry matter, organic matter, N, and neutral detergent fiber digestibility coefficients or on cumulative (15d) in vitro ammonia losses from manure. Compared with SA, LA and CO increased milk fat 12:0, cis-9 12:1, and trans-9 12:1 content and decreased 6:0, 8:0, 10:0, cis-9 10:1, 16:0, 18:0, cis 18:1, total 18:2, 18:3 n-3 and total polyunsaturated FA concentrations. Administration of LA and 14:0 (as CO) in the rumen were apparently transferred into milk fat with a mean efficiency of 18 and 15%, respectively. In conclusion, current data confirmed that LA and CO exhibit strong antiprotozoal activity when dosed intraruminally, an effect that is accompanied by decreases in ammonia concentration and, for CO, lowered methane production. Administration of LA and CO in the rumen also altered milk FA composition.

Meta-analysis of the influence of Saccharomyces cerevisiae supplementation on ruminal parameters and milk production of ruminants

The effects of yeast supplementation on intake, production, and rumen fermentation characteristics have been widely studied, but results are inconsistent between different studies. A quantitative meta-analysis was applied to 110 papers, 157 experiments, and 376 treatments dealing with yeast supplementation in ruminants. The objective was first to highlight the major quantitative effects of live yeast supplementation on intake, rumen fermentation, and milk production, and second, to identify major differences in experimental conditions between studies that can affect the response to treatment. Some of these experimental conditions are referred to as interfering factors. Yeast supplementation increased rumen pH (+0.03 on average) and rumen volatile fatty acid concentration (+2.17mM on average), tended to decrease rumen lactic acid concentration (−0.9mM on average), and had no influence on acetate-to-propionate ratio. Total-tract organic matter digestibility was also increased by yeast supplementation (+0.8% on average). Yeast supplementation increased dry matter intake (DMI;+0.44g/kg of body weight; BW), milk yield (+1.2g/kg of BW), and tended to increase milk fat content (+0.05%), but had no influence on milk protein content. Dose effects of yeast supplementation, expressed as log10 [1+(cfu per 100kg of BW)], globally confirmed the qualitative effects observed in the first analysis. The positive effect of yeast supplementation on rumen pH increased with the percentage of concentrate in the diet and with the DMI level. It was negatively correlated with the level of dietary neutral detergent fiber (NDF). The positive effect of yeast supplementation on rumen volatile fatty acid concentration increased with DMI and crude protein levels. The positive effect of yeast supplementation on organic matter digestibility increased with the percentage of concentrate and NDF in the diet. The negative effect of yeast supplementation on lactic acid concentration tended to decrease when the DMI level and the percentage of concentrate in the diet increased. The effects of interfering factors were globally similar when either dose effect or qualitative effect of yeast was taken into account. Although rumen fermentation efficiency per se was not measured, these results suggest an improvement in rumen fermentation by yeast supplementation. This effect could, however, be modulated by several different factors such as DMI, percentage of concentrate or NDF in the diet, or species.

Interaction of molasses and monensin in alfalfa hay- or corn silage-based diets on rumen fermentation, total tract digestibility, and milk production by Holstein cows

Sugar supplementation can stimulate rumen microbial growth and possibly fiber digestibility; however, excess ruminal carbohydrate availability relative to rumen-degradable protein (RDP) can promote energy spilling by microbes, decrease rumen pH, or depress fiber digestibility. Both RDP supply and rumen pH might be altered by forage source and monensin. Therefore, the objective of this study was to evaluate interactions of a sugar source (molasses) with monensin and 2 forage sources on rumen fermentation, total tract digestibility, and production and fatty acid composition of milk. Seven ruminally cannulated lactating Holstein cows were used in a 5×7 incomplete Latin square design with five 28-d periods. Four corn silage diets consisted of 1) control (C), 2) 2.6% molasses (M), 3) 2.6% molasses plus 0.45% urea (MU), or 4) 2.6% molasses plus 0.45% urea plus monensin sodium (Rumensin, at the intermediate dosage from the label, 16g/909kg of dry matter; MUR). Three chopped alfalfa hay diets consisted of 1) control (C), 2) 2.6% molasses (M), or 3) 2.6% molasses plus Rumensin (MR). Urea was added to corn silage diets to provide RDP comparable to alfalfa hay diets with no urea. Corn silage C and M diets were balanced to have 16.2% crude protein; and the remaining diets, 17.2% crude protein. Dry matter intake was not affected by treatment, but there was a trend for lower milk production in alfalfa hay diets compared with corn silage diets. Despite increased total volatile fatty acid and acetate concentrations in the rumen, total tract organic matter digestibility was lower for alfalfa hay-fed cows. Rumensin did not affect volatile fatty acid concentrations but decreased milk fat from 3.22 to 2.72% in corn silage diets but less in alfalfa hay diets. Medium-chain milk fatty acids (% of total fat) were lower for alfalfa hay compared with corn silage diets, and short-chain milk fatty acids tended to decrease when Rumensin was added. In whole rumen contents, concentrations of trans-10, cis-12C18:2 were increased when cows were fed corn silage diets. Rumensin had no effect on conjugated linoleic acid isomers in either milk or rumen contents but tended to increase the concentration of trans-10C18:1 in rumen samples. Molasses with urea increased ruminal NH3-N and milk urea N when cows were fed corn silage diets (6.8 vs. 11.3 and 7.6 vs. 12.0mg/dL for M vs. MU, respectively). Based on ruminal fermentation characteristics and fatty acid isomers in milk, molasses did not appear to promote ruminal acidosis or milk fat depression. However, combinations of Rumensin with corn silage-based diets already containing molasses and with a relatively high nonfiber carbohydrate:forage neutral detergent fiber ratio influenced biohydrogenation characteristics that are indicators of increased risk for milk fat depression.

Composition, digestibility and nutritive value of cereals for dogs

Most dry dog foods are based on cereals, but very little published information and few comparative studies are available on the nutritive value of various cereals in dogs. To determine the apparent nutrient digestibilities and feed values of five different autoclave-processed and ground cereals: oat groats, barley, wheat, corn and rice, a digestibility trial was carried out on twelve adult huskies according to a 6 x 4 cyclic changeover design. Total tract organic matter (OM), crude carbohydrate and gross energy (GE) digestibilities were higher in rice than in all the other cereals. Apparent crude protein (CP) and acid hydrolyzed fat digestibilities of rice (80% and 94%, respectively) were as good as for oat groats (81% and 93%). However, oat groats had higher OM, CP and GE digestibilities than barley, wheat and corn. The amount of digestible crude protein (118 g kg-1 DM) was higher in oat groats than in the other cereals. Digestible energy contents (MJ kg-1 DM) of oat groats, rice, corn, wheat and barley were 17.1, 16.0, 15.7, 15.6 and 15.5, respectively. The quantity of excreted wet faeces increased and the percentage of dry matter (DM) in faeces decreased when oat groats, barley, wheat or corn were supplemented to the basal diet, in contrast to rice, which had the opposite effect on wet faeces excretion. Oat groats are good substitutes for rice or other cereals in dry dog foods.;

How Does Live Yeast Differ from Sodium Bicarbonate to Stabilize Ruminal pH in High-Yielding Dairy Cows?

The objectives of this study were to evaluate the capacity of 2 dietary feed additives, sodium bicarbonate and live yeast Saccharomyces cerevisiae (strain Sc 47), in optimizing ruminal pH in dairy cows and to determine their modes of action. Three early lactating Holstein cows, fitted with ruminal cannulas, were allocated in a 3×3 Latin square design. They were given a total mixed ration as control diet (CD) at a daily feeding rate of 28.0kg of dry matter (DM)/cow supplemented with 150 g/d of sodium bicarbonate (SBD) or 5 g/d of live yeast (YD) during a 21-d experimental period (14 d of diet adaptation, 4 consecutive days of measurement and sampling and 3 d of transition). The pH and redox potential (Eh) were measured from 1h before feeding to 8h after feeding at 1-h intervals, and samples of ruminal fluid were taken at 0, 2, 4, 6, and 8h after feeding for the determination of volatile fatty acids and lactate concentrations. Total tract apparent digestibility of the diet was also determined. Ruminal pH fluctuated between 6.53 at feeding and 5.57 at 5h postfeeding. Mean pH was greater with SBD (6.21) and YD (6.14) compared with CD (5.94), showing that both additives had a pH stabilization effect. The Eh varied from -88mV at 1h before feeding to -165mV at 1h after feeding. Mean Eh and Clark's Exponent (rH) were lower with YD (–149mV and 7.31, respectively) than with SBD (–137mV and 7.85, respectively) and CD (–115mV and 8.05, respectively), indicating that the yeast strengthened the reducing power of the milieu. Total volatile fatty acids were greater in SBD (95.3mM) and YD (99.4mM) compared with CD (85.3mM). Acetate concentration was greater in SBD (60.8mM) and YD (59.1mM) compared with CD (53.2mM). Propionate concentration was greater in YD (25.8mM) than in SBD (20.0mM) and CD (18.0mM). Butyrate remained constant between diets. Mean total lactate concentrations were 16.5, 12.2, and 5.4mM for CD, SBD, and YD, respectively, with a 67% decrease with YD. Total tract organic matter digestibility was greater for YD (66.6%) compared with SBD (61.7%) and CD (62.2%). The neutral detergent fiber digestibility was greater with YD (41.6%) compared with SBD (34.3%) and CD (29.6%), whereas acid detergent fiber digestibility was greatest in YD (32.3%), intermediate in SBD (24.4%), and lowest in CD (18.1%). By inducing a lower ruminal Eh and rH, live yeast prevented accumulation of lactate and allowed better fiber digestion, whereas sodium bicarbonate seemed to act only as an exogenous buffer.

Intake, rumen fermentation and nutrient flow to the omasum in beef cattle fed grass silage fortified with sucrose and/or supplemented with concentrate

The objective was to determine the relative effects of a specific increase in grass silage sucrose concentration, or a specific supplement of a starch-based concentrate, on rumen fermentation and nutrient supply to the omasum in beef cattle. Four ruminally cannulated Holstein–Friesian steers were fed grass silage only (G), G plus 3 kg concentrates/day (GC), G plus 90 g sucrose/kg dry matter (DM) (GS) and G plus 90 g sucrose/kg DM plus 3 kg concentrates/day (GCS) in a 4 × 4 Latin Square design experiment. Omasal flow was estimated using Co-EDTA, Yb-acetate and indigestible neutral detergent fibre (INDF) as digesta flow markers and purine bases as microbial markers. Concentrate supplementation reduced ( P < 0.01) silage and increased ( P < 0.001) total DM intake whereas sucrose had no effect. There was a sucrose × concentrate interaction ( P < 0.05) for rumen pH whereby addition of sucrose to grass silage alone decreased pH and to grass silage plus concentrate had no effect. Rumen ammonia N ( P < 0.01), total volatile fatty acid (VFA) concentration ( P < 0.05) and the molar proportions of valerate ( P < 0.05) and butyrate ( P < 0.001) increased with concentrate supplementation whereas, sucrose supplementation had no effect on rumen fermentation parameters. Organic matter (OM) intake, omasal OM flow, the quantities of OM apparently (OMAD) and truly digested (OMTD) in the rumen ( P < 0.001) and total tract OM digestibility ( P < 0.01) increased, and apparent and true ruminal OM digestibility decreased ( P < 0.05) with concentrate supplementation. Supplementation with concentrate decreased ( P < 0.05) ruminal neutral detergent fibre (aNDFom) digestibility and increased ( P < 0.05) aNDFom omasal flow. There was a tendency for addition of sucrose to increase ( P < 0.1) ruminal OMAD and OMTD, while there was no effect of sucrose addition on intake or digestion of aNDFom. Concentrate supplementation increased ( P < 0.001) N intake, flows of N, non-ammonia N (NAN), microbial N (MN) ( P < 0.05) and non-ammonia non-microbial N (NANMN) ( P < 0.01) and apparent total tract digestibility of N ( P < 0.01), whereas sucrose reduced ( P < 0.05) N intake and apparent ruminal N digestibility. There was no effect of concentrate or sucrose on N use efficiency or efficiency of microbial protein synthesis. Concentrate supplementation increased ( P < 0.001) plasma β-hydroxybutyrate levels. In comparison to supplementing unwilted, well preserved grass silage of moderate digestibility with 3 kg starch-based concentrate per day, the limited response to the rate of sucrose supplementation employed suggests that increasing the water-soluble carbohydrate (WSC) concentration of grass silage through agronomic and/or ensiling practices will have relatively little effect on intake, rumen digestion or efficiency of microbial N synthesis.

Effect of dietaryEnterolobium cyclocarpumon microbial protein flow and nutrient digestibility in sheep maintained fauna-free, with total mixed fauna or withEntodinium caudatummonofauna

Three groups of five wethers with ruminal and duodenal cannulas and maintained as either fauna-free (FF) or inoculated with total mixed fauna (TF) or Entodinium caudatum as a single-species monofauna (EN) were used in an experiment with two 28 d periods. In the first period, the sheep were fed a control barley-based diet (40:60 concentrate to silage DM) and in the second period the diet was supplemented with 187 g DM of Enterolobium cyclocarpum for the last 12 d of the period. The diets of period 1 and 2 were isonitrogenous. There was no effect of fauna on apparent ruminal and total tract organic matter and fibre digestion, but bacterial and microbial N flow and efficiency were improved in FF sheep compared to TF sheep. In period 2, protozoal numbers were reduced between 31 and 88 % 2 h after feeding E. cyclocarpum for the third to twelfth day of supplementation and by an average of 25 % in samples collected over the 24 h feeding cycle. Supplementation of the diet with E. cyclocarpum and the consequent protozoal reduction in TF and EN sheep improved the flow of non-ammonia N and bacterial N to the small intestine and the efficiency of microbial synthesis. However, E. cyclocarpum reduced ruminal organic matter digestion, especially in faunated sheep, and total tract organic matter, N and fibre digestion. Thus, a reduction in the protozoal cell numbers of 25 % was sufficient to achieve the beneficial effects of reduced fauna on the bacterial protein supply, but diet digestibility was reduced.

Effect of dietary inclusion of hazelnut and soybean meals on microbial protein synthesis

The aim of this study was to compare effects of dietary inclusion of hazelnut meal (HZM) with soybean meal (SBM) on site of digestion and microbial protein synthesis in sheep. Four ruminally and duodenally cannulated female Redkaraman × kıvırcık sheep (initial BW of 44.0 ± 1.02 kg) were utilized in a crossover experiment. Sheep were fed a diet of 60% corn silage (DM basis) and 40% concentrate consisting of barley and SBM or HZM. Feed was fed at 115% of ad libitum intake. Intakes of dry matter (DM), organic matter (OM), crude protein (CP), neutral detergent fiber (NDF) and acid detergent fiber (ADF) were similar between sheep fed SBM or HZM based diets ( P > 0.05). Organic matter intake averaged 1089 (2.37% BW) and 1143 g/day (2.42% BW) for SBM and HZM, respectively. Apparent and true ruminal and total tract DM and OM digestibilities did not differ between diets ( P > 0.05). True ruminal OM digestibility was 74.3 and 74.6% for SBM and HZM based diets, respectively. Total CP entering the duodenum was similar between diets ( P > 0.05). Dietary plus endogenous CP entering the duodenum in grams and as a percentage of total CP was greater ( P < 0.05) for SBM versus HZM. Quantities of microbial protein ( P < 0.15) and NH 3 N ( P < 0.08) flowing to the duodenum tended to be less for SBM versus HZM; percentages of total CP were lower ( P < 0.05) for SBM. Apparent ruminal and total tract CP digestibilities did not differ between diets, but true ruminal CP digestibility and efficiency of microbial protein synthesis tended to be higher in animals fed the HZM based diet compared with the diet based on SBM ( P < 0.13). In conclusion, because total CP entering duodenum did not differ between diets, HZM can be substituted for SBM in sheep fed corn silage and barley based diets with a moderate CP level.

Methane-suppressing effect of myristic acid in sheep as affected by dietary calcium and forage proportion

The efficiency of myristic acid (14 : 0) as a feed additive to suppress CH4 emissions of ruminants was evaluated under different dietary conditions. Six sheep were subjected to a 6 x 6 Latin square arrangement. A supplement of non-esterified 14 : 0 (50 g/kg DM) was added to two basal diets differing in their forage:concentrate values (1 : 1.5 and 1 : 0.5), which were adjusted to dietary Ca contents of 4.2 and 9.0 g/kg DM, respectively. Comparisons were made with the unsupplemented basal diets (4.2 g Ca/kg DM). The 14 : 0 supplementation decreased (P<0.001) total tract CH4 release depending on basal diet type (interaction, P<0.001) and dietary Ca level (P<0.05, post hoc test). In the concentrate-based diet, 14 : 0 suppressed CH4 emission by 58 and 47 % with 4.2 and 9.0 g Ca/kg DM, respectively. The 14 : 0 effect was lower (22 %) in the forage-based diet and became insignificant with additional Ca. Myristic acid inhibited (P<0.05) rumen archaea without significantly altering proportions of individual methanogen orders. Ciliate protozoa concentration was decreased (P<0.05, post hoc test) by 14 : 0 only in combination with 9.0 g Ca/kg DM. Rumen fluid NH3 concentration and acetate:propionate were decreased (P<0.05) and water consumption was lower (P<0.01) with 14 : 0. The use of 14 : 0 had no clear effects on total tract organic matter and fibre digestion; this further illustrates that the suppressed methanogenesis resulted from direct effects against methanogens. The present study demonstrated that 14 : 0 is a potent CH4 inhibitor but, to be effective in CH4 mitigation feeding strategies, interactions with other diet ingredients have to be considered.

Corn Silage Management: Effects of Hybrid, Chop Length, and Mechanical Processing on Digestion and Energy Content

Two experiments were conducted to evaluate the effects of chop length and mechanical processing of two hybrids of whole plant corn on digestion and energy content of the total mixed ration (TMR). The experimental designs in experiments 1 and 2 were 6×6 and 4×4 Latin squares, respectively. In the first experiment, Pioneer hybrid 3845 was harvested at three theoretical lengths of cut: 11.1, 27.8, and 39.7mm. At each chop length, corn was harvested with and without mechanical processing using a John Deere 5830 harvester with an onboard kernel processor. In the second experiment, Pioneer hybrid Quanta was harvested at two theoretical lengths of cut: 27.8 and 39.7mm, with and without mechanical processing. In both experiments, the increase in the theoretical length of cut of corn silage increased the average length of cut and tended to increase the percentage of particles greater than 19mm and lower the percentage of particles between 8 and 19mm. In experiment 1, apparent total tract dry matter, organic matter, and neutral detergent fiber (NDF) digestibilities were lower for cows fed diets containing corn silage harvested at a short chop length (11.1mm) than for corn silage harvested at a long chop length (39.7mm). The lower total tract digestibility of nutrients may have contributed to the lower TDN, metabolizable energy (percentage of digestible energy), and NEL concentration of diets containing the short chop length corn silage (experiment 1). In experiment 2, total tract starch digestibility was greater for cows fed medium chop (27.8mm) corn silage diets, and total tract NDF digestibility was greater for cows fed long chop (39.7mm) corn silage diets. The opposing effect of total tract starch and fiber digestibilities between chop lengths may have contributed to the lack of difference in energy content of the diets in experiment 2. The TDN and NEL concentrations of the processed corn silage diets were greater than the unprocessed corn silage diets in experiment 1. The increase in energy concentration for the processed corn silage diet was due to greater total tract digestibility of organic matter and ether extract. Total tract starch digestibility was greater, and total tract NDF digestibility was lower for cows fed processed corn silage diets than unprocessed corn silage diets in experiment 2. The opposing effect of total tract starch and fiber digestibilities between processed and unprocessed corn silage may have contributed to the lack of difference in energy content of the diets.

Effect of Protein Source on Amino Acid Supply, Milk Production, and Metabolism of Plasma Nutrients in Dairy Cows Fed Grass Silage

This study conducted according to a 4×4 Latin square with 28 d periods and four ruminally cannulated Finnish Ayrshire cows investigated the effect of protein supplements differing in amino acid (AA) profile and rumen undegradable protein content on postruminal AA supply and milk production. Mammary metabolism of plasma AA and other nutrients were also studied. The basal diet (Control; 13.4% crude protein) consisted of grass silage and barley in a ratio of 55:45 on a dry matter basis. The other three isonitrogenous diets (17.0% crude protein) were control+fishmeal (FM), control+soybean meal (SBM), and control+corn gluten meal (CGM). The protein supplements replaced portions of dry matter of the control diet maintaining the silage to barley ratio constant for all diets. Dry matter intake was limited to 95% of the preexperimental ad libitum intake and was similar (mean 19.8 kg/d dry matter) across the diets. Protein supplements increased milk, lactose, and protein yields but did not affect yields of energy-corrected milk or milk fat. Milk protein yield response was numerically lowest for diet SBM. Protein supplements increased milk protein concentration but decreased milk fat and lactose concentrations. Microbial protein synthesis and rumen fermentation parameters were similar across the diets, except for an increased rumen ammonia concentration for diets supplemented with protein feeds. Protein supplements increased N intake, ruminal organic matter and N, and total tract organic matter, N, and neutral detergent fiber digestibilities. Protein supplements also increased N and AA flows into the omasum, with SBM giving the lowest and CGM the highest flows. This was associated with an unchanged microbial N flow and a higher undegraded dietary N flow. The omasal flows of individual AA reflected differences in total N flow and AA profile of the experimental diets. Differences in AA flows did not always reflect plasma AA concentrations. The results indicated that AA supply of dairy cows fed a grass silage-cereal diet can be manipulated using protein supplements differing in ruminal protein degradability and AA profile. Lower milk production response to SBM than that to FM and CGM appeared to be related mainly to lower N and AA supplies arising from a high ruminal protein degradability of SBM. Histidine appeared to be the first limiting AA for milk protein synthesis on the control diet. Mammary gland may regulate AA uptake according to requirements.

Oral Administration of Arabinogalactan Affects Immune Status and Fecal Microbial Populations in Dogs

Seven ileally cannulated dogs were randomly assigned to a control or arabinogalactan (AG) treatments in a 7 x 7 Latin square design to evaluate effects of oral AG administration on nutritional and immunological characteristics. Arabinogalactan treatments included a high (1.65 g/d) and low (0.55 g/d) dose of AG100, AG1000 or AG3000 provided via gelatin capsules. Arabinogalactan forms differed in purification procedures. Each period consisted of a 6-d adaptation followed by a 4-d collection. Blood and fresh fecal samples were collected on d 10 of each period. Fecal score increased (P < 0.02) in dogs supplemented with the low dose of AG1000. Ileal and total tract dry matter (DM) and organic matter (OM) digestibilities were not affected by treatment. Dogs supplemented with the high dose of AG1000 tended (P = 0.15) to have a higher concentration of total aerobic fecal bacteria than control dogs. Dogs supplemented with the low dose of AG1000 and the high dose of AG3000 had higher concentrations of fecal lactobacilli (P = 0.04) and tended to have higher concentrations of fecal bifidobacteria (P < or =0.16) compared with control dogs. Dogs fed the low dose of AG3000 tended (P = 0.10) to have a lower concentration of fecal Clostridium perfringens compared with control dogs. Arabinogalactan treatments did not affect (P > 0.05) serum immunoglobulin G, M or A concentrations. Specific forms and doses of AG increased white blood cell, neutropil and eosinophil concentrations. Arabinogalactan is a unique dietary fiber that affects the digestive physiology and immunological characteristics of dogs.

Steam-flaked corn diets containing combinations of wet corn gluten feed and alfalfa hay: effects on diet digestibility and ruminal characteristics (2002)

Twelve ruminally cannulated Jersey steers were used to measure digestibility and ruminal characteristics of steam-flaked corn based diets containing combinations of wet corn gluten feed (WCGF) and alfalfa hay (AH). Starch intake was lower (P<0.05), but neutral detergent fiber intake was higher (P<0.05) as AH and WCGF increased in the diet. Ruminal pH was increased by AH (linear, P<0.05) and tended (P<0.07) to increase with WCGF. Feeding higher levels of WCGF tended to increase passage rate (P=0.17) and decreased (P<0.05) total tract organic matter digestibility. Flaked corn diets containing at least 25% WCGF may contribute enough roughage to allow reduction of alfalfa hay levels.

Effects of energy and protein supplementation on microbial-N synthesis and allantoin excretion in sheep fed guinea grass

An experiment was conducted to determine the effects of two types of protein, soybean meal (SBM) and fish meal (FM); and two types of energy supplements, corn flour (CF) and paper pulp (PP) on in vivo digestibility of organic matter (OM), rumen fermentation pattern and dilution rate, rumen microbial-N synthesis and flow of organic matter and nitrogenous compounds through the duodenum in four Merino rams with an average weight of 54.4±4.5 kg. The relationships between duodenal purine flow and urinary allantoin and duodenal protein/energy (MJ rumen VFA per day) ratio were also investigated. The experiment was conducted in a 4×4 Latin square design with a 2×2 factorial arrangement of dietary treatments. The animals, fitted with both rumen and duodenal cannulae were housed in individual crates and fed chopped fresh guinea grass ad libitum twice daily, 100 g molasses and one of the four dietary supplements: (i) 170 g FM+268 g PP (FM+PP); (ii) 170 g FM+268 g CF (FM+CF); (iii) 200 g SBM+200 g PP (SBM+PP); and (iv) 200 g SBM+200 g CF (SBM+CF). Each supplement, at varying rates of rumen degradability, was formulated to provide similar amount of N and gross energy. The results showed that rumen pHs were similar, ranging from pH 5.8 to 6.0, for all animals fed the different dietary supplements. Rumen ammonia concentration was significantly ( p<0.05) higher in animals fed SBM (170.2–190.7 mg N l −1) than in animals fed FM supplement (166.8–170.2 mg N l −1). Rumen VFA concentrations were similar (94–103 mM) but molar proportions of acetate and propionate were respectively lower and higher in treatment SBM+CF, leading to a significantly decreased acetate:propionate ratio in this treatment (3.6) compared to SBM+PP (4.3). There were no significant differences between treatments in rumen fluid dilution rate and rumen volume. Duodenal OM flow was similar in PP supplemented diets, but differed significantly ( p<0.05) between protein supplements in the CF diets. Organic matter digestibility in the rumen was significantly ( p<0.05) higher in the CF+FM diet. Moreover, animals fed SBM supplement showed higher total tract OM digestibility than animals fed FM supplement. The flow of nitrogenous compounds to the duodenum, i.e., total-N, non-ammonia-N and rumen-undegradable-N were not significantly affected by either protein or energy supplements. Microbial-N flow tended ( p<0.08) to be higher in sheep fed CF supplement (average of 10.2 g per day) than in those fed PP supplement (average of 8.1 g per day). Urinary allantoin excretion was low (0.30–0.42 mmol per day/kg BW 0.75). A positive linear correlation ( r=0.73, p<0.005) between urinary allantoin (μmol per day/kg BW 0.75) and duodenal purines (μmol per day/kg BW 0.75) was observed. The efficiency of rumen microbial-N synthesis based on OM truly digested in the rumen was significantly ( p<0.02) higher in sheep fed CF supplement (15.2–16.6 g N kg −1 OMTDR) than in those fed PP supplement (12.2–12.8 g N kg −1 OMTDR). Differences in microbial protein:energy ratio or total duodenal protein:energy ratio among dietary treatments were not significant.

Intake and digestion by Holstein steers consuming different particle size fractions of broiler litter

Eight Holstein steers (153±13.6 kg body weight) were used in two simultaneous 4×4 Latin squares with 21-day periods to determine effects of separating deep-stacked broiler litter into small and large particle size fractions on feed intake and digestibility. Steers were fed diets with or without two sources of deep-stacked broiler litter (source A: 24% crude protein and 35% neutral detergent fiber; source B: 23% crude protein and 44% neutral detergent fiber). All steers were fed ground corn at approximately 0.5% body weight (dry matter basis). Bermudagrass hay was consumed ad libitum by Control steers (without broiler litter) or at 0.5% body weight (dry matter basis) for treatments with dietary broiler litter. Broiler litter was consumed ad libitum without separation (whole; W) or after separation (1-mm screen aperture) into small (S; 27 and 33% crude protein for A and B, respectively) and large (L; 22 and 18% crude protein for A and B, respectively) particle size fractions. Organic matter intake was increased ( P=0.06) by dietary inclusion of broiler litter (4.55, 4.56, 4.63, 4.73, 4.24, 5.18, 4.74 and 4.59 kg day −1 for Control-A, W-A, S-A, L-A, Control-B, W-B, S-B and L-B, respectively; SE 0.229). Total tract organic matter digestibility was greater ( P=0.08) for broiler litter source A than for B (57.4, 57.8, 54.9, 57.6, 56.5, 48.4, 46.9 and 54.8%; SE 3.83), and digestible organic matter intake tended ( P=0.11) to be greater for source A (2.56, 2.64, 2.54, 2.72, 2.36, 2.51, 2.16 and 2.58 kg day −1 for Control-A, W-A, S-A, L-A, Control-B, W-B, S-B and L-B, respectively; SE 0.166). In conclusion, separating deep-stacked broiler litter into two particle size fractions did not alter feeding value as assessed by digestible organic matter intake by growing steers.

Effects of base ingredient in cooked molasses blocks on intake and digestion of prairie hay by beef steers (1998)

Blocks based on cooked beet molasses, cane molasses, or concentrated separator by-product, CSB) were tested to compare their effects on intake and digestion of prairie hay by beef steers. All blocks contained at least 30% crude protein. Steers fed the cooked molasses blocks consumed and 22% more forage than control steers, but forage intakes were not different among the three different blocks. Intakes of digestible organic matter and neutral detergent fiber, indicators of energy available to the steers, were increased 38 and 29% respectively, by block supple-mentation but were not different among the three blocks. However, total tract organic matter and neutral detergent fiber digestibilities, expressed as a percent of intake, were slightly higher for steers fed the beet molasses block than those fed the cane molasses block or the CSB block. In summary, supplementation with cooked molasses blocks that contained adequate degradable protein increased forage intake and digestion. Generally, blocks made from the different by-products elicited similar responses, though steers fed the beet molasses product tended to have greater digestibilities than those fed blocks made from cane molasses or concentrated separator by-product.