Dietary Neutral Detergent Fiber Research Articles

Prediction of rumen fiber pool in cattle from dietary, fecal, and animal variables

Feed intake control in ruminants is based on the integration of physical constraints and metabolic feedbacks. Physical constraints are related to the fill caused by the weight or volume of digesta in the reticulo-rumen. The amount of neutral detergent fiber (NDF) in the rumen (RNDF) may be used as an indicator of rumen fill. The objective of this study was to develop equations predicting RNDF from diet and animal characteristics using a meta-analysis technique. A treatment mean data set (n=314) was obtained from 84 studies, in which rumen pool size and diet digestibility were determined in lactating cows (n=231) or growing cattle (n=83). The data were analyzed using linear and nonlinear mixed models. Intake, rumen pool size, and fecal output of NDF were scaled to body weight (BW)1.0. Due to the heterogeneous nature of dietary NDF, predictions of RNDF based on NDF intake were not precise. Predictions were markedly improved by dividing NDF into potentially digestible and indigestible fractions, because rumen turnover time of indigestible NDF was 2.7 times longer than that of potentially digestible NDF. At equal NDF intake, RNDF was negatively associated with dietary crude protein concentration and positively with the proportion of concentrate in the diet. Models based on fecal NDF output generally performed better than those based on NDF intake, probably because the effects of intrinsic characteristics of dietary cell walls and associative effects of dietary components collectively influence fecal NDF output. The model based on fecal NDF output was improved by including dietary concentration of forage NDF in the model, reflecting slower turnover of forage NDF compared with concentrate NDF. The curvilinear relationship between fecal NDF output and RNDF could be described by a quadratic, Mitscherlich, or power function equation, which performed better than the quadratic or Mitscherlich equation. In addition to fecal NDF output and dietary concentration of forage NDF, animal and forage type had significant effects on RNDF. At the same fecal NDF output, growing cattle had a smaller RNDF than dairy cattle. Increased proportion of alfalfa or corn silages in forage decreased RNDF and increased proportion of tropical forages decreased it. It is concluded that RNDF can be predicted precisely from intake or fecal output data, and that predicted RNDF can be a useful tool in understanding the interplay between physical and metabolic factors regulating feed intake in ruminants.

Methanogenic potential of forages consumed throughout the year by cattle in a Sahelian pastoral area

Methane (CH4) emission from ruminants in African pastoral systems may be affected by intake and type of plants, which vary highly between rainy and dry seasons. In each of two sites located in the semiarid Sahelian area of Senegal, three Gobra zebus were monitored throughout 1 year. A representative sample of their diet was obtained once every month. Diet was mainly composed of grasses, herbaceous legumes, tree and shrub foliage and pods, and dried forage residues. CH4 production and volatile fatty acid (VFA) concentration, which reflects VFA production, were determined in vitro. Crude protein, neutral detergent fibre (NDF) and acid detergent fibre were measured by near-infrared spectrophotometry. CH4 production varied between 24.6 and 35.2 mL/g forage dry matter (DM), being minimal in August (rainy season) and maximal in February (dry season). Seasonal difference disappeared when CH4 was expressed in mL/g NDF. The acetate : propionate ratio varied in the same way as CH4 (3.2 and 4.6 in August and February, respectively); VFA concentration was minimum in March and maximum in September (69.2 and 77.4 mmol/L, respectively). CH4 production was closely related to dietary NDF content (r = 0.82) and to acetate : propionate ratio (r = 0.96). For six successive periods (February to July), plant categories constituting the diet were incubated separately. Reconstituting the CH4 production and VFA concentration in the diet on the basis of the proportion of plant components gave values similar to those of the global diet (33.4 and 34.2 mL CH4/g DM and 75.9 and 70.9 mmol VFA/L, respectively). This result suggests the absence of interaction among plant components on rumen fermentation.

Milk production and composition responds to dietary neutral detergent fiber and starch ratio in dairy cows.

This study was designed to investigate whether dietary neutral detergent fiber (NDF) : starch ratio could be considered as a nutritional indicator to evaluate carbohydrate composition and manipulate milk production and composition synthesis. Eight primiparous dairy cows were assigned to four total mixed rations with NDF : starch ratios of 0.86, 1.18, 1.63 and 2.34 from T1 to T4 in a replicated 4 × 4 Latin square design. Dry matter intake and milk production were decreased from T1 to T4. Digestibility of dry matter, organic matter, NDF and crude protein were linearly decreased from T1 to T4. As NDF : starch ratio increased, milk protein content and production, and milk lactose content and production were linearly reduced. However, milk fat content was linearly increased from T1 to T4. Quadratic effect was observed on milk fat production with the highest level in T3. Averaged rumen pH was linearly increased from T1 to T4, and subacute rumen acidosis occurred in T1. Ruminal propionate and butyrate concentration were linearly decreased, and microbial crude protein and metabolizable protein decreased from T1 to T4. It is concluded that NDF : starch ratio can be considered as a potential indicator to evaluate dietary carbohydrate composition and manipulate milk production and composition synthesis.

Digestibility of NDF and its effect on the level of rumen fermentation of carbohydrates

DOI: 10.15414/afz.2015.18.04.110–113 Received 14. July 2015 ǀ Accepted 12. October 2015 ǀ Available online 7. December 2015 The objective of this study, was to determinate the effects of digestibility of NDF of TMR on rumen fermentation characteristics and nutrient digestion, dairy cows were fed total mixed ration (TMR). We are measured NDF digestibility of TMR using in situ methods.Digestibility of NDF of TMR in our experiment range 26.8 to 48.2%. Digestibility of NDF of TMR did not alter VFA production but had effects on A/P ratio and production of acetate and propionate. Our results indicate that TMR with more dNDF may provide more favourable condition for nutrient digestion both in the rumen and in the total tract of dairy cows. Keywords : rumen, fermentation, NDF, volatile fatty acids, digestibility of NDF References ALLEN, M. S., BRADFORD, B. J. and OBA, M. (2009) BOARD-INVITED REVIEW: The hepatic oxidation theory of the control of feed intake and its application to ruminants. In J. Anim. Sci., vol. 87, no. 10, pp. 3317–3334. doi:http://dx.doi.org/10.2527/jas.2009-1779 BEEVER, D. E. and MOULD, F. L. (2000) Forage evaluation for efficient ruminant livestock production. In: D. I. Givens et al. (eds.) Forage Evaluation in Ruminant Nutrition. Wallington: CAB International. HOFFMAN, P.C. and SHAVER, R.D. (2009) UW-Feed Grain Evaluation System Marshfield Soil and Forage Analysis Laboratory. [Online] Available at: http://www.uwex.edu/ces/dairynutrition/documents/ WisconsinFGES.pdf. [Accessed? 2015-06-04]. HUTJENS, M. F. (2002) Is your TMR as good as it can be? In Hoard´s Dairyman, vol. 147, no. 18, pp. 698. CHUMPAWADEE, S. and PIMPA, O. (2009) Effect of fodder tree as fiber sources in total mixed ration on feed intake, nutrient digestibility, chewing behaviour and ruminal fermentation in beef cattle. In J. Anim. And Vet. Adv, vol. 8, no. 7, pp. 1279:1284. doi: http://dx.doi.org/2009.1279.1284 KOLVER, E. S. and DE VETH, M. J. (2002) Prediction of ruminal pH from pasture based diets. In J. Dairy Sci., vol. 85, no. 5, pp. 1255–1266. doi:http://dx.doi.org/10.3168/jds.S0022-0302 (02)74190-8 LINN, J.G. et al. (1989) Feeding the dairy herd. Madison: North Central Regional Extension. LOPEZ, S., J. DIJKSTRA, and FRANCE, J. (2000) Prediction of energy supply in ruminants, with emphasis on forages. In: D. I. Givens, E. Owens, R. F. E., Axford, and H. M. Omed, (eds.) Forage Evaluation in Ruminant Nutrition. Wallingford: CAB International, pp. 63-94. NRC (2001) Nutrient requirements of dairy cattle: Nutrient requirements of domestic animals. 7th revised edition. Washington: National Reserach Council. OBA, M. and ALLEN, M. S. (1999) Evaluation of the importance of the digestibility of neutral detergent fiber from forage: effects on dry matter intake and milk yield of dairy cows. In J. Dairy Sci., vol. 82, no. 3, pp. 589-596. doi:http://dx.doi.org/10.3168/jds.S0022-0302(99)75271-9 OBA, M. and ALLEN, M. S. (2000) Effects of brown midrib 3 mutation in corn silage on productivity of dairy cows fed two concentrations of dietary neutral detergent fiber: 3. Digestibility and microbial efficiency. In J. Dairy Sci., vol. 83, no. 6, pp. 1342–1349. doi: http://dx.doi.org/10.3168/jds.S0022-0302(00)75001-6 ORSKOV, E.R. and MCDONALD, I. (1979) The estimation of protein degradability in the rumen from incubation measurements weighed according to rate of passage. In J. Agric. Sci., vol. 92, no. 3, pp. 499-503. doi:http://dx.doi.org/10.1017/S0021859600063048 VARGA G.A. (2006) In vivo digestibility of forage. In: Proc. Tri-State dairy nutrition conference, Fort Wayne. Columbus: The Ohio State University, pp 95-106. VOELKER LINTON., J. A. and ALLEN, M. S. (2009) Nutrient demand interacts with forage family to affect N digestion and utilization responses in dairy cows. In J. Dairy Sci., vol. 92, no. 4, pp.1594-1602. doi:http://dx.doi.org/10.3168/jds.2008-1327

Impact of dietary fiber/starch ratio in shaping caecal microbiota in rabbits.

The objective of this experiment was to determine whether changing the dietary neutral detergent fiber (NDF)/starch ratio affected caecal microbiota when 4 different diets (diet A: 2.3 NDF/starch, diet B: 1.9, diet C: 1.4, diet D: 1.0) were formulated. A total of 200 weaned rabbits (35 days old, 50 per group) were used for the experiment, which started after an adaptation period of 7 days (i.e., day 42). Caecal contents were obtained from rabbits fed different NDF/starch diets at 52, 62, 72, and 82 days of life. The bacterial community structure was characterized by high-throughput 16S rRNA sequencing. Firmicutes, Actinobacteria, Synergistetes, and Tenericutes did not significantly change with diet or age. However, Bacteroidetes (P < 0.05), Proteobacteria (P < 0.01), and Verrucomicrobia (P < 0.05) reads were significantly affected by diet, and Proteobacteria (P < 0.01) and Verrucomicrobia (P < 0.05) reads were significantly influenced by age. At the genus level, Escherichia/Shigella (P < 0.01) was overrepresented in diet A (high fiber) relative to diet D (high starch) in 52- and 62-day-old rabbits. Venn diagrams and heat map plot analyses revealed that the number of gut species shared between animals with different diet treatments increased with age. These results suggest that dietary fiber per starch ratios and age significantly alter the composition of caecal microbiota in growing rabbits.

Effects of dietary neutral detergent fibre to protein ratio on duodenal microbial nitrogen flow and nitrogen losses in lactating cows fed high-concentrate total mixed rations with different forage combinations

SUMMARYThe objective of the present study was to investigate the effect of dietary neutral detergent fibre (NDF) : crude protein (CP) ratio on duodenal microbial crude protein (MCP) flow and nitrogen (N) losses. The study was completed in a 5 × 5 Latin square design with five lactating Holstein dairy cows and 5 high-concentrate total mixed rations (TMR) with different forage combinations, typical for Northern China. The rations with a fixed forage-to-concentrate ratio (39 : 61) resulted in different dietary NDF : CP ratios: TMR1 3·03 : 1 (428·2 g NDF/kg : 141·4 g CP/kg); TMR2 2·74 : 1 (392·7 g NDF/kg : 143·2 g CP/kg); TMR3 2·55 : 1 (368·3 g NDF/kg : 144·4 g CP/kg); TMR4 1·84 : 1 (304·8 g NDF/kg : 165·8 g CP/kg); TMR5 1·60 : 1 (285·0 g NDF/kg : 178·0 g CP/kg). Rumen content, milk, blood, urine and faeces were sampled on the last 3 days of five 18-day periods. Purine derivatives in the urine samples were determined to estimate rumen MCP flow into the small intestine. Milk yield and milk protein yield increased linearly with decreasing dietary NDF : CP ratio although slight differences in dry matter intake were observed due to feed intake restriction. Diurnal ammonia N in the rumen and duodenal MCP flow increased linearly, but blood urea N, urinary N and faecal N linearly decreased with decreasing dietary NDF : CP ratio. The enhanced N utilization in the maize-silage-based TMRs (TMR4–5) in comparison with maize-stover-based TMRs (TMR1–3) increased milk yield and the synthesis of milk protein instead of milk fat in the lactating cows, probably due to high transfer of ammonia N into rumen MCP with a considerable increase of dietary non-fibre carbohydrate content and the decrease of NDF : CP ratio. The present results indicate that not only increasing dietary non-structural carbohydrate content but also adjusting the ratio of structural carbohydrate to CP ratio are important diet formulation strategies for mitigating N losses in lactating cows.

Feeding and lying behavior of heat-stressed early lactation cows fed low fiber diets containing roughage and nonforage fiber sources

In addition to reduced nutrient intake, an environmental thermal load may directly affect milk yield in heat-stressed dairy cows. Feeding and lying behaviors of early lactation cows fed low fiber diets containing neutral detergent fiber (NDF) from roughage and nonforage fiber sources (NFFS) were investigated under summer conditions in Thailand. Immediately after calving, 30 multiparous cows (87.5% Holstein × 12.5% Sahiwal) were randomly allocated to dietary treatments for 63 d in a completely randomized design. The dietary treatments contained 25% of dry matter (DM) as dietary NDF. The control diet consisted of 13.9% roughage NDF from rice straw (RS). Two additional treatments were created by replacing 3.9% of DM with NDF from either soy hulls (SH) or cassava (Manihot esculenta Grantz) residues (CR), so that the roughage NDF content was reduced to 10%. During the experimental period, the minimum and maximum temperature-humidity indices (THI) were 86.4±2.5 and 91.5±2.7 during the day and 74.2±2.1 and 81.0±2.5 during the night, respectively, indicating conditions appropriate for induction of extreme heat stress. The duration of feeding and lying bouts decreased linearly with increasing THI. The DM intake during the day was greater for cows fed diets containing SH and CR than for those fed the diet containing NDF from RS. The number of meals during the day and night was lower, whereas meal size and meal length during the day and night were greater for cows fed diets containing SH and CR. Cows fed diets containing SH and CR lay down less frequently and longer during the day. These results suggest that under the severe heat stress during the day, early lactation cows fed the diet containing NFFS increased DM intake by increasing meal length and meal size rather than by increasing meal frequency and they spent more time lying. Cows fed diets containing NDF from SH and CR produced more 4% fat-corrected milk, lost less body weight, and had lower rectal temperatures measured at the 1530h milking. Therefore, reducing the filling effect may contribute to reducing heat load derived from the change in feeding and lying behavior. This should be considered as a factor for impairing productivity of heat-stressed early lactation cows.

Effects of ruminal doses of sucrose, lactose, and corn starch on ruminal fermentation and expression of genes in ruminal epithelial cells

The objective was to evaluate effects of a ruminal dose of sucrose, lactose, and corn starch on ruminal fermentation and expression of genes in ruminal epithelial cells. Six ruminally cannulated nonlactating nonpregnant Holstein cows (body weight=725±69.6kg) were assigned to treatments in a 3×3 Latin square design with 7-d periods; 1d for data and sample collection followed by a 6-d washout period. Cows were fed a diet containing whole-crop barley silage and dry ground corn, and dietary neutral detergent fiber and crude protein contents were 41.8 and 13.2% [dry matter (DM) basis], respectively. Treatment was a pulse-dose of sucrose, lactose, and corn starch (3.0, 3.0, and 2.85kg of DM, respectively; providing similar amounts of hexose across the treatments) through the ruminal cannulas. All treatments were given with alfalfa silage (1.75kg DM) to prevent acute rumen acidosis. Rumen pH was continuously monitored, and rumen fluid was sampled at 0, 30, 60, 90, 120, 150, and 180min after the dose. In addition, ruminal papillae were sampled from the ventral sac at 180min after the dose. Ruminal dosing with sucrose and lactose, compared with corn starch, increased ruminal total volatile fatty acid concentration and molar proportion of butyrate from 60 to 180min after the dose, and expression of genes for sodium hydrogen exchanger isoforms 1 and 2, and ATPase isoform 1 in ruminal epithelial cells. Ruminal dosing with sucrose, compared with lactose and corn starch, decreased rumen pH from 120 to 180min after the dose and molar proportion of acetate in ruminal fluid from 60 to 150min after the dose, and increased molar proportion of propionate in ruminal fluid from 60 to 150min, and expression of genes involved in butyrate metabolism (3-hydroxy-3-methylglutaryl-coenzyme A synthase isoform 1) and anion exchange across ruminal apical cell membrane (putative anion transporter isoform 1). These results suggest that replacing dietary starch with sugars may affect ruminal fermentation and metabolism regulating intracellular pH and fermentation acid absorption in ruminal epithelial cells, and that these effects can be greater for sucrose than lactose.

Factors affecting feed efficiency in dairy goats

The objective of this study was to present some factors affecting feed efficiency in dairy goats. To develop our work, individual and average data from performance experiments with lactating goats were used. The following variables were evaluated: gross feed efficiency, adjusted feed efficiency, dry matter intake, milk-yield, 3.5% fat-corrected milk yield, dry matter digestibility, dietary neutral detergent fiber content, different roughage-to-concentrate ratios and body weight. The statistical analyses involved the application of descriptive and dispersion measures besides Pearson's correlation coefficient and linear regression analysis. The analyzed variables were highly correlated with feed efficiency. The feed efficiency of lactating goats was affected by the milk fat correction, dry matter digestibility, dietary fiber content, proportion of roughage in the diet and body weight. Among these factors, standardization of the milk fat appeared to be the most efficient in correcting the feed efficiency in lactating goats. Correction of some of these factors implies greater precision in the measurement of feed efficiency.

Comparison of enriched palmitic acid and calcium salts of palm fatty acids distillate fat supplements on milk production and metabolic profiles of high-producing dairy cows

A variable response to fat supplementation has been reported in dairy cows, which may be due to cow production level, environmental conditions, or diet characteristics. In the present experiment, the effect of a high palmitic acid supplement was investigated relative to a conventional Ca salts of palm fatty acids (Ca-FA) supplement in 16 high-producing Holstein cows (46.6±12.4kg of milk/d) arranged in a crossover design with 14-d periods. The experiment was conducted in a non-heat-stress season with 29.5% neutral detergent fiber diets. Treatments were (1) high palmitic acid (PA) supplement fed as free FA [1.9% of dry matter (DM); 84.8% C16:0] and (2) Ca-FA supplement (2.3% of DM; 47.7% C16:0, 35.9% C18:1, and 8.4% C18:2). The PA supplement tended to increase DM intake, and increased the yields of milk and energy-corrected milk. Additionally, PA increased the yields of milk fat, protein, and lactose, whereas milk concentrations of these components were not affected. The yields of milk de novo and 16-C FA were increased by PA compared with Ca-FA (7 and 20%, respectively), whereas the yield of preformed FA was higher in Ca-FA. A reduction in milk fat concentration of de novo and 16-C FA and a marginal elevation in trans-10 C18:1 in Ca-FA is indicative of altered ruminal biohydrogenation and increased risk of milk fat depression. No effect of treatment on plasma insulin was observed. A treatment by time interaction was detected for plasma nonesterified fatty acids (NEFA), which tended to be higher in Ca-FA than in PA before feeding. Overall, the palmitic acid supplement improved production performance in high-producing cows while posing a lower risk for milk fat depression compared with a supplement higher in unsaturated FA.

Increasing dietary neutral detergent fiber concentration decreases ruminal hydrogen sulfide concentrations in steers fed high-sulfur diets based on ethanol coproducts.

Cattle feedlot diets commonly contain ethanol coproducts that are high in S. This dietary S is reduced in the rumen by sulfate reducing bacteria, resulting in an accumulation of hydrogen sulfide (H2S), increasing the risk for S toxicity. A negative correlation between H2S and ruminal pH has been observed previously. The objective of this study was to determine the effect of varying dietary NDF from chopped bromegrass hay (66% NDF) on performance, ruminal pH, and ruminal H2S gas concentration of steers fed a high-S finishing diet. One hundred fifty crossbred steers (359 ± 51 kg BW) were blocked by BW into pens of 5 steers and randomly assigned within block to 1 of 5 treatments (n = 6 pens per treatment) and fed for 84 d. Dietary treatments included 3.5, 5.7, 7.9, 10.1, or 11.4% roughage NDF (rNDF) from bromegrass hay and contained 0.46% dietary S from a combination of dried distillers grains with solubles and condensed corn distillers solubles. In all diets, hay was added at the expense of dry-rolled corn. Effective NDF increased linearly (P < 0.01) with increased inclusion of rNDF. Final BW was not affected by rNDF (P ≥ 0.12). The addition of roughage did not affect ADG (P ≥ 0.13) or gain efficiency (P ≥ 0.12). Dry matter intake increased linearly (P < 0.01) as rNDF concentration increased. There was a treatment × month interaction for S intake (P < 0.01), explained by steers fed 3.5 or 11.4% rNDF increasing S intake each month whereas the middle rNDF inclusions had similar S intake between months 1 and 2 and increased in month 3. Ruminal H2S concentrations and ruminal fluid pH were measured at 6 h postfeeding on d 7, 14, 21, 29, and 84. Ruminal pH increased linearly (P < 0.01; 5.48, 5.61, 5.71, 5.74, and 5.80 ± 0.041 for 3.5, 5.7, 7.9, 10.1, and 11.4% rNDF, respectively) and ruminal H2S concentrations decreased linearly (P < 0.01; 1.00, 0.86, 0.76, 0.70, and 0.62 ± 0.037 g/m(3) for 3.5, 5.7, 7.9, 10.1, and 11.4% rNDF, respectively) as rNDF inclusion increased. Using mixed model regression analysis, ruminal pH had a strong negative relationship with ruminal H2S concentrations (β = -0.63; P < 0.01). Under conditions of this study, increasing roughage did not affect cattle gains but helped maintain greater ruminal pH and decreased H2S concentration, suggesting that this dietary strategy may lessen the risk of S toxicity in feedlot cattle.

Effect of monensin on recovery from diet-induced milk fat depression

The objective of the present experiment was to investigate the effect of monensin (MN) on the time course of recovery from diet-induced milk fat depression. Milk fat depression was induced in all cows (n = 16) during the first phase of each period by feeding a low-fiber, high-unsaturated fat diet [25.3% neutral detergent fiber (NDF), 6.9% fatty acids (FA), and 3.24% C18:2] with MN (450mg/cow per day) for 10 to 14d. A recovery phase of 18d followed, where cows were switched to a higher-fiber and lower unsaturated fat diet (31.2% NDF, 4.3% FA, and 1.7% C18:2). According to a crossover design, treatments during recovery were (1) control (no MN supplementation) or (2) continued MN supplementation. Milk yield, milk composition, and milk FA profile were measured every 3d during recovery. No effect was observed of MN on dry matter intake or yield of milk, milk protein, and lactose. Milk fat concentration and yield increased progressively during recovery in both treatments. Monensin decreased milk fat yield from d 6 to 15, but it was the same as the control on d 18. A treatment by time interaction on milk fat concentration was detected, which was decreased by MN only on d 3 and 6. The yield of milk de novo synthesized FA increased progressively in both treatments and was not affected by treatment. Similarly, yield of 16-C FA increased progressively, but was decreased by MN on d 6 and 9. Preformed FA yield was lower in the MN group from d 6 to 15, but was not different from the control on d 18. Importantly, milk FA concentration of trans-10 C18:1 and trans-10,cis-12 conjugated linoleic acid rapidly decreased in both groups; however, MN slightly increased trans-10 C18:1 concentration above baseline on d 15 and 18. In conclusion, MN supplementation had minimal effect on recovery of normal rumen biohydrogenation and de novo FA synthesis during recovery from milk fat depression by correction of dietary starch, NDF, and polyunsaturated FA concentration, but moderately decreased recovery of preformed FA in milk.

The Effects of Dietary Neutral Detergent Fiber Ratio from Forage and Concentrate on The Dietary Rumen Degradability and Growth Performance of Philippine Native Goats (Capra hircus Linn.)

This research’s objective was to determine the dietary rumen degradability and growth performances of goats fed dietary treatments. 18 native female goats (live weight of 7.96 ± 2.21 kg) were grouped into 6 classes for the feeding trial and 3 male mature goats with rumen cannula were used for the in situ digestibility. The three dietary treatments were: T1 - 72:28 Forage-Concentrate NDF ratio; T2 - 64:36; and T3 - 57:43. The rate of rumen degradability of DM and CP at 0 hours, potentially degradable fraction (b) and the rate of degradation of b were not affected by dietary treatments. The different ratios of NDF in the diets significantly affected the intake of DM, CP and NDF from forage and concentrates. Treatment diets affected the total intake of DM, CP and NDF of the animals. However, growth performance was not affected by the treatments showing the same production efficiency. This means that diets given to native goats with ratio of forage NDF of 72.07% can be applied since the value of the output and efficiency of feed utilization had the same value compared to diets ratio of forage NDF of 57.21%.

Development of a mechanistic model of intake, chewing and digestion in cattle in connection with updated feed units

Recent proposals have updated systems of feed units of energy, protein, structure and rumen fill. However, consistency between the largely independently built units has not been checked, even though energy, structure and fill values of feedstuffs are linked throughout feeding in ruminants. The target of this work was to build a mechanistic model to ensure consistency across equations related to intake, mastication, fill value of feeds and diets, digestion of organic matter and transit times. The first step was to build a large database of published results on digestion, intake and chewing in cattle. This database was studied by meta-analyses to calculate more than 100 empirical regressions; about half of these equations were used to build the new French systems of net energy and metabolisable protein. The other equations were mainly related to mastication (per day or kg dry matter intake, DMI), as well as the sizes and adjacent flows of 12 compartments inside the rumen: neutral detergent fibre (NDF), degradable (D) or not (U), in large or small particles; protein, soluble (S) or D and U; starch, S or D; water; volatile fatty acids; and microbes. The rumen digesta load (RL) was closely linked with the forage NDF intake, but in this dataset, there was no maximum RL, so it does not seem to limit DMI. Close relationships were observed between long-forage intake (NDFI, % of liveweight) and dietary forage NDF (%DM) and between mastication (min/day) and dietary index of mastication (min/kg DMI). Unlike RL, each of these two relationships exhibited obvious asymptotic maximum values for the duration of mastication per day (~1000 min/day) and for the level intake of NDF from long forages (1.35% of liveweight). In these two equations, the slope represented the level of DMI. The two equations were added to the other structural equations. It is therefore possible to use a mechanistic model with 12 compartments to consistently integrate aspects dealing with fill, chewing, DMI and energy value of rations in cattle.

The effects of dietary neutral detergent fiber ratio on the rumen degradability and growth performance of Philippine native goats (Capra hircus Linn.)

This research’s objective was to determine the dietary rumen degradability and growth performances of goats fed dietary treatments. Eighteen (18) female goats were grouped into 6 weight classes for the feeding trial experiment, the average BW of the animals that were used was about 7.96 ± 2.21 kg (CV - 27.76%) and were approximately 1 year of age. For the in situ digestibility, three (3) male mature goats surgically fitted with cannulated rumen were used. Three (3) dietary treatments were used for all studies as follows: T1 - 72 : 28 NDF Forage-Concentrate Ratio; T2 - 64 : 36; T3 - 57 : 43. A RCBD was applied for Feeding Trial and a 3 x 3 LSD was used for In Situ Study. Treatments 1, 2 and 3 did not affect the rate of rumen degradability of DM, NDF and CP at 0 hours, potentially degradable fraction (b) and the rate of degradation of b. The treatments affected the intake rate of forage and concentrates on the DM, CP and NDF. However, the total intake of DM, CP and NDF were not affected by the treatments. Growth performance of goats used in this experiment was not affected by the treatments as indicated by the similar production and efficiency. This means that diets given to native goats with ratio of NDF forage of 72.07% can be applied since the value of the output and efficiency of feed utilization had the same value compared to diets ratio of NDF forage of 57.21%. Key Words: NDF Forage, Ration, Goat

Milk production and composition of mid-lactation cows consuming perennial ryegrass-and chicory-based diets

Dry matter intakes (DMI), nutrient selection, and milk production responses of dairy cows grazing 3 herbage-based diets offered at 2 allowances were measured. The 2 allowances were 20 (low) and 30 (high) kg of dry matter (DM)/cow per day and these were applied to 3 herbage types: perennial ryegrass (PRG) and chicory (CHIC+) monocultures and a mixed sward of chicory and perennial ryegrass (MIX). The CHIC+ diet was supplemented with alfalfa hay (approximately 2kg of DM/cow per day) to maintain dietary neutral detergent fiber (NDF) concentration and all diets were supplemented with energy-based pellets (6kg of DM/cow per day). Holstein-Friesian dairy cows averaging 136±30 d in milk were allocated to 4 replicates of the 6 treatments using stratified randomization procedures. Cows were adapted to their experimental diets over a 14-d period, with measurements of DMI, milk yield, and composition conducted over the following 10 d. Herbage DMI was lowest (12.8 vs. 14.0kg of DM/d) for CHIC+ compared with the MIX and PRG, although total forage intake (grazed herbage plus hay) was similar (14.0 to 15.0kg of DM/d) across the 3 treatments. Milk production, milk protein, and milk fat concentrations were not different between herbage types. Grazed herbage DMI increased with increasing herbage allowance and this was associated with increased milk protein concentration (3.23 to 3.34%) and total casein production (41.7 to 43.6mg/g). Concentrations of polyunsaturated fatty acids in milk fat, particularly linoleic acid, were increased in milk from cows offered the CHIC+ or the MIX diets, indicating potential benefits of chicory herbage on milk fatty acid concentrations. Although feeding CHIC+ or MIX did not increase milk yield, these herbage types could be used as an alternative to perennial ryegrass pasture in spring.

The development of a model to predict feed intake by growing cattle

The objective of this work was to develop total dry matter intake (TDMI) prediction models for growing cattle. The Finnish dataset of 1006 experimental period treatment means from 17 feeding trials in growing bulls was collected for developing TDMI prediction models. The diets were mainly based on grass silage or grass silage partly or completely replaced by whole-crop silages or straw. The concentrate feeds consisted mainly of cereal grains, fibrous by-products and various protein supplements. The following non-linear equation for the relationship between TDMI and body weight (BW) (kg) was defined: TDMI (kg/d)=0.191×BW0.627 (Adj. RMSE=0.451). The model was improved when both the constant and exponent were adjusted for dietary variables. Dietary neutral detergent fibre (NDF) concentration (kg/kg DM) generated a greater improvement in the model than other variables investigated (dietary concentrations of forage NDF and ME, and the proportion of concentrate). The constant decreased and the exponent increased with increasing dietary NDF concentration. The following equation was defined: TDMI (kg/d)=(0.209–0.489×NDF)×BW (0.614+0.397×NDF) (Adj. RMSE=0.438). In the model NDF concentration was centred to the mean concentration of 0.40kg/kg DM. The model was marginally improved when the constant was adjusted for silage DMI (SDMI)-index that was centred to 100 units and dietary concentration of volatile fatty acids (VFA). The effects of SDMI-index and VFA were highly significant (P<0.01): TDMI (kg/d)=(0.199–0.380×NDF+0.000348×SDMI-index−0.00044×VFA)×BW(0.624+0.348×NDF) (Adj. RMSE=0.433). A complete dataset was used for the evaluation of models developed from the Finnish dataset. The complete dataset was collected from growing cattle feeding experiments, in which total mixed rations or forages were fed ad libitum. Overall, the complete dataset comprised 135 feeding experiments and 687 treatment means. The following relationship between observed and predicted TDMI was derived with a non-linear model including SDMI-index and dietary VFA concentration as adjustment factors for the constant: Observed TDMI=–0.35(±0.40)+1.01(±0.051)×Predicted TDMI (n=421; Adj. RMSE=0.243). The developed models can be used to estimate the intake responses to BW and diet changes. They provide an improved basis for practical ration formulation systems and economic evaluation.

Effects of alfalfa hay particle size in high-concentrate diets supplemented with unsaturated fat: Chewing behavior, total-tract digestibility, and milk production of dairy cows

This study evaluated the effects of increasing the physically effective neutral detergent fiber (peNDF) intake of lactating dairy cows fed high-concentrate diets supplemented with unsaturated fat on intake, eating behavior, diet sorting, chewing activity, total-tract digestibility, and milk production and composition. Diets contained 24% alfalfa hay (AH), 16% corn silage, 58% concentrate, and 2% yellow grease [dry matter (DM) basis], and dietary peNDF content was increased by varying the particle size (PS) of the AH. Nine multiparous cows averaging 87.8±14.8d in milk and weighing 653±53kg were randomly assigned to a triplicate 3×3 Latin square. During each 21-d period, cows were offered 1 of 3 total mixed rations that varied in PS of AH: fine, medium, and long, with a geometric mean particle length of 3.00, 3.57 and 3.87mm, respectively. Increasing PS quadratically affected DM intake (DMI; 24.7, 25.4, and 23.7kg/d, for fine, medium, and long, respectively), but cumulative DMI at 2, 4, and 6h after feeding was similar across treatments, averaging 23.4, 35.6 and 46.4% of total DMI for the 3 time points, respectively. Increased peNDF intake did not affect feed sorting, but increased daily eating time, and eating and total chewing time per kilogram of DMI. Daily rumination time exhibited a quadratic response, with highest rumination time for the medium diet. Dietary PS had no effects on digestibility in the total tract, but we observed, for fine, medium, and long diets, quadratic responses in milk production (41.5, 43.3, and 40.4kg/d), 4% fat-corrected milk production, and milk protein yield. Milk fat content decreased linearly with increasing PS, but milk fat content and fat:protein ratio were low for all treatments, likely due to adding unsaturated fat to a diet containing a high level of nonfiber carbohydrates (42.2% of DM). The composition, degree of saturation, and total conjugated linoleic acid content of fatty acids in milk fat were not affected by the change in peNDF content of the diet. The study indicates that a moderate increase in the PS of AH in diets containing unsaturated fat elevates peNDF intake and increases chewing activity, DMI, milk yield and milk fat production. However, the effects of dietary PS were quadratic, with maximum DMI and milk production observed with diets supplying 24% dietary peNDF (measured as the proportion of the ration retained on sieves >1.18mm multiplied by dietary neutral detergent fiber content; DM basis).

Characterization of cecal microbiota of the emu (Dromaius novaehollandiae)

Emus (Dromaius novaehollandiae), large flightless ratites native to Australia, are farmed for their fat and meat. They are omnivorous and feed on a wide variety of plants and insects. Despite having a relatively simple gastrointestinal tract and a short digesta retention time, emus are able to digest a significant portion of the ingested dietary neutral detergent fibre. However, nothing is known about the microbial diversity in their gastrointestinal tract. In this study, we evaluated the phylogenetic diversity of the cecal microbiota of four emus (2 males, 2 females) that were fed a barley-alfalfa-canola based diet, using 454 pyrosequencing after amplification for V3-V5 region of bacterial 16S rRNA gene. Emus were slaughtered in early November, just prior to the onset of their breeding season, but after the seasonal decline in their feed intake had begun. A total of 822 operational taxonomic units (OTUs) (335.3 ± 70.5 OTUs/sample) belonging to 9 bacterial phyla were identified. The most predominant bacterial phyla were Bacteroidetes (≈ 57% of total classified diversity), Proteobacteria (≈ 24%), Fusobacteria (≈ 11.3%), and Firmicutes (≈ 7%). Our results indicate that the emus' ceca may have a higher microbial richness (Chao1: 624 ± 170 OTUs, and ACE: 586 ± 161 OTUs) than other species of birds, but they have a lower microbial diversity (Shannon diversity index: 3.4 ± 0.2, Simpson index: 0.79 ± 0.02), possibly reflecting their decrease feed intake. This is the first study to characterize the microbial community of the gastrointestinal tract of a ratite using pyrosequencing, providing a baseline for further study.

Diet factors and subclinical laminitis score in lactating cows of smallholder dairy farms in Thailand

The objective of this study was to evaluate the importance of dietary crude protein (CP) content, dietary neutral detergent fiber (NDF) content and feeding regime as well as other factors related to management and demographics on the occurrence of (subclinical) laminitis under practical Thai feeding conditions. Hemorrhage of the white line and the sole, sole ulcer and white-line fissure of all four claws of milking cows (n=119) on 25 farms (selected based on the occurrence of lameness) were macroscopically assessed to calculate the prevalence of subclinical laminitis (SCL) on each farm. Data were collected on farm characteristics, feed and feeding management, floor type and hoof care. Dry matter intake was assessed on each farm and feed ingredients collected and analyzed for dry matter (DM), CP and NDF. No significant differences were found for farm characteristics such as herd size, number of milking cows, parity and body condition scoring between farms with a low (<25%) or a high prevalence (>25%) of SCL. Percentages of DM and CP content of the rations did not differ, whereas mean NDF content in the ration was significantly higher in the low compared to the high prevalence farms. Multiple regression analysis of the data showed that a ration low in NDF content and/or in combination with the separate feeding of roughage and concentrate was associated with a high SCL prevalence. The results suggest that mixing concentrate with a substantial part of the roughage is an important strategy to prevent SCL in smallholder dairy farms under Thai feeding conditions. In addition, the dietary NDF content but not the dietary CP level is associated with SCL prevalence in dairy cows under Thai feeding conditions.