Dietary Neutral Detergent Fiber Research Articles

Nutritional approaches to slow late finishing pig growth: implications on carcass composition and pork quality.

Although pork producers typically aim to optimize growth rates, occasionally it is necessary to slow growth, such as when harvest facility capacity is limited. In finishing pigs, numerous dietary strategies can be used to slow growth so pigs are at optimal slaughter body weights when harvest facility capacity and/or access is restored. However, the impact of these diets on pork carcass quality is largely unknown. Thus, this study aimed to evaluate the efficacy of dietary strategies to slow growth in late finishing pigs and evaluate their effects on carcass composition and pork quality. Mixed-sex pigs (n = 897; 125 ± 2 kg BW) were randomly allotted across 48 pens and assigned to 1 of 6 dietary treatments (n = 8 pens/treatment): (1) Control diet representative of a typical finisher diet (CON); (2) diet containing 3% calcium chloride (CaCl2); (3) diet containing 97% corn and no soybean meal (Corn); (4) diet deficient in isoleucine (LowIle); (5) diet containing 15% neutral detergent fiber (NDF) from soybean hulls (15% NDF); and (6) diet containing 20% NDF from soybean hulls (20% NDF). Over 42 d, pen body weights and feed disappearance were collected. Pigs were harvested in 3 groups (14, 28, and 42 d on feed) and carcass data collected. From the harvest group, 1 loin was collected from 120 randomly selected carcasses (20 loins/treatment) to evaluate pork quality traits. Overall, ADG was reduced in CaCl2, Corn, and 20% NDF pigs compared with CON pigs (P < 0.001). However, ADFI was only reduced in CaCl2 and 20% NDF pigs compared with CON (P < 0.001). Feed efficiency was reduced in CaCl2 and Corn pigs compared with CON (P < 0.001). Hot carcass weights were reduced in CaCl2 pigs at all harvest dates (P < 0.001) and were reduced in Corn and 20% NDF pigs at days 28 and 42 compared with CON pigs (P < 0.001). In general, CaCl2 and 20% NDF diets resulted in leaner carcasses, whereas the Corn diet increased backfat by 42 d on test (P < 0.05). Loin pH was reduced and star probe increased in CaCl2 pigs compared with CON pigs (P < 0.05); no treatments differed from CON pigs regarding drip loss, cook loss, color, firmness, or marbling (P ≥ 0.117). Overall, these data indicate that several dietary strategies can slow finishing pig growth without evidence of behavioral vices. However, changes to carcass composition and quality were also observed, indicating quality should be taken into consideration when choosing diets to slow growth.

79 Effects of dietary net energy and neutral detergent fiber levels on growth performance and carcass characteristics of growing finishing pigs

Abstract Our objective was to determine the effects of feeding different net energy (NE) and neutral detergent fiber (NDF) on performance of growing-finishing pigs from 30- to 135-kg. A total of 2,058 barrows and gilts (PIC 380×Camborough, initial BW 33.4±0.60 kg) were used in a 97-d growth trial with 21 pigs per pen and 14 pens per treatment in a randomized complete block design. Treatments were formulated to contain 2.11, 2.21, 2.32, 2.42, 2.53, 2.63, and 2.73 Mcal NE/kg; and 24.2, 19.7, 15.1, 10.6, 10.2, 9.8, and 9.5% NDF throughout the experiment. Wheat, wheat byproducts, barley, rye, peas, fababeans, and canola oil were used with NRC (2012) loading values to achieve the treatments. Dietary lysine levels were set to meet PIC2016 lysine requirements for finishing gilts. Experimental data were analyzed using generalized linear mixed models and linear and quadratic polynomial contrasts were built with pen as the experimental unit. Increasing NE or decreasing NDF improved (linear and quadratic, P&amp;lt; 0.05) average daily gain (ADG), gain-to-feed ratio (G:F), carcass ADG, and carcass G:F (Table 1); but reduced (linear and quadratic, P&amp;lt; 0.05) average daily feed intake (ADFI). Comparing to pigs fed 2.42 Mcal/kg diet (energy equivalent to a corn-soybean meal diet), even though those fed 2.11 Mcal/kg diet had 8.7% increment on ADFI, daily NE intake was still 5.4% less. Hot carcass weight, backfat depth, and carcass yield increased (linear and quadratic, P&amp;lt; 0.05) and lean yield decreased (linear and quadratic, P&amp;lt; 0.05) with increasing dietary NE and decreasing NDF. No evidence for differences (P &amp;gt;0.10) were observed for loin depth. Removal and mortality rate was reduced (quadratic, P&amp;lt; 0.05) with increasing dietary NE and decreasing dietary NDF. In summary, increasing dietary NE while reducing dietary NDF resulted in improvements on growth performance, carcass characteristics, and removal and mortality rate.

73 Effects of dietary neutral detergent fiber and standardized ileal digestible lysine levels on growth performance and carcass characteristics of growing-finishing pigs

Abstract Our objective was to determine the effects of feeding different neutral detergent fiber (NDF) and standardized ileal digestible (SID) lysine (Lys) levels on performance of growing-finishing pigs from 30- to 130-kg. A total of 2,016 barrows and gilts (PIC 280×Camborough, initial BW of 29.6±0.53 kg) were allotted to a randomized complete block design with a 2×2 factorial arrangement. Dietary treatments (Table 1) consisted with two NDF levels (13% or 20%) and two SID Lys curves (PIC2008 or PIC2016). There were 21 mixed-sex pigs per pen, and 24 pens per treatment. The experiment diets were fed in 3 phases. Wheat, wheat by-products, peas, and canola oil were used with NRC (2012) loading values to achieve treatments, and all diets were formulated to be iso-caloric (2,420 kcal NE/kg). Experimental data were analyzed using generalized linear mixed models with pen as the experimental unit. Increasing NDF level resulted in a reduction (P&amp;lt; 0.05) in average daily gain (ADG), average daily feed intake, hot carcass weight, carcass yield, carcass ADG, and backfat depth (Table 2), and tended to decrease percentage of removals and mortality (P=0.10). Pigs fed PIC2016 Lys curve had greater ADG and carcass ADG as compared to those fed PIC2008 Lys curve (P&amp;lt; 0.05). There were NDF×Lys interactions (P&amp;lt; 0.10) for ADG, gain to feed ratio (G:F), carcass ADG, and carcass G:F. These response criteria were improved for pigs fed PIC2016 Lys curve compared to those fed PIC2008 Lys curve when NDF level was 13%; while no evidence of differences was observed at 20% NDF. Results indicate that increasing NDF level from 13 to 20% deteriorate performance of 30- to 130- kg pigs; and the improved growth performance of pigs fed PIC2016 Lys curve as compared to those fed PIC2008 Lys curve was only observed when lower NDF level was presented.

Quantitative joint evaluation of sheep enteric methane emissions and faecal dry matter and nitrogen excretion

Specific nutrition and management interventions at farm level that aim at reducing enteric methane (CH4) production from sheep may not reduce excretion of dry matter and N, the main source of excreta CH4 production and nitrous oxide. The objectives were a) to determine the relationship of dietary variables and animal characteristics to both enteric CH4 emissions and N excretion from sheep fed ryegrass or forage brassica diets, and b) to jointly predict enteric CH4 emissions, and dry matter and N excretion from sheep based on feed intake, dietary nutrient contents and animal characteristics. A database containing 270 indirect respiration calorimetry and total excreta collection records of eight sheep studies from New Zealand was used. To explain variation in CH4 production and N excretion, all records were assigned to four categories based on CH4 emissions and N excretion being lesser or greater than the means of the entire database, viz. high CH4-high N, high CH4-low N, low CH4-high N and low CH4-low N. A redundancy analysis indicated the two low N categories were positively related to dry matter digestibility. Subsequently, dry matter digestibility was positively related to brassica forages and negatively related to ryegrass forages. Univariate modelling indicated that CH4 (g d−1) was best predicted by dry matter intake (DMI), faecal dry matter excretion (g d−1) by DMI and dietary neutral detergent fibre content, and N excretion (g d−1) by DMI and dietary crude protein content, with dry matter digestibility also contributing to the best prediction of faecal and total N. A bivariate multiple regression model for jointly predicting CH4 emission and total N excretion, and a trivariate model for also predicting faecal dry matter were developed. Key covariates included DMI, dietary neutral detergent fibre and crude protein contents, whereas DMI was replaced by body weight in the bivariate yield model (g [kg DMI]-1), and not selected for the trivariate yield model. Regression coefficients of dietary crude protein content obtained through multivariate modelling had opposite signs for CH4 emission and N excretion, indicating a trade-off. However, this trade-off was not supported by univariate modelling. Therefore, evidence for a trade-off between enteric CH4 and N excretion from sheep is limited.

Effects of addition of nutritionally improved straw in dairy cow diets at 2 starch levels

The objective of this experiment was to explore the effects of different dietary neutral detergent fiber sources within diets of high-producing dairy cattle with low or high starch concentrations on milk yield and composition, dry matter intake (DMI), total-tract digestibility, nitrogen (N) partitioning, and rumen function and health. Holstein-Friesian cows in early- to mid-lactation (n = 12; 666 ± 67 kg of body weight at the start of the experiment) and dry cannulated Holstein-Frisian cows (n = 4; 878 ± 67 kg of body weight at the start of the experiment) were used in multiple 4 × 4 Latin square design experiment and were offered 4 different diets. The treatments were 50:50 forage-to-concentrate diets within a total mixed ration (TMR) consisting, on a dry matter (DM) basis, of 42.4% grass silage as the main forage, 7.6% chopped untreated wheat straw, or sodium hydroxide (NaOH) wheat straw pellets, known as nutritionally improved straw (NIS), and 50.0% of 1 of 2 different concentrates with low or high starch level (TMR starch level of 16.0 vs. 24.0% of DM, respectively). Four experimental periods were used, each consisting of a 21-d adaptation period and 7 d of sampling. Dry matter intake and milk yield were both affected by the type of straw included in the diet. A 1.6 kg/d higher DMI was seen when NIS was fed compared with untreated straw, resulting in a 1.7 kg/d higher milk yield. Milk protein concentration was affected by straw type and starch level, and it was 4 and 3% higher when NIS and high-starch diets were fed, respectively. Diets with NIS were more positively effective when fed with low levels of starch. These results illustrate that feeding NIS to high-producing lactating dairy cows fed low or high starch concentrations has a positive effect on performance.

Performance of growing lambs supplemented with ground licuri (Syagrus coronata).

ObjectiveThe aim of this study was to determine the effect of dietary ground licuri on lamb performance.MethodsForty male lambs were used in a completely randomized design to test the effects of 0, 5, 10, and 15 g/kg of ground licuri added to diets. The trial lasted for 75 days. Intake, digestibility, physically effective neutral detergent fiber, and chewing activity were estimated. Blood samples were taken on day 45 to determine the concentrations of glucose, urea, non-esterified fatty acids, and triglycerides. Average daily gain (ADG) were determined on the last day of the experimental trial.ResultsLicuri inclusion markedly increased dietary neutral detergent fiber and ether extract (EE) content, but it decreased dry matter (DM) intake. However, the intake and digestibility of EE linearly increased. The ADG decreased linearly (p<0.05) with licuri inclusion. Licuri had no effect (p>0.05) on the concentrations of blood metabolites; however, blood urea increased (p<0.05), while serum glucose decreased (p<0.05).ConclusionThe physically effective fiber of ground licuri is similar to Tyfton hay and licuri inclusion decreases lamb performance due to a decreased in DM intake.

Enteric methane, lactation performances, digestibility, and metabolism of nitrogen and energy of Holsteins and Jerseys fed 2 levels of forage fiber from alfalfa silage or corn silage

Our objective was to determine the effects of replacing alfalfa silage (AS) neutral detergent fiber (NDF) with corn silage (CS) NDF at 2 levels of forage NDF (FNDF) on enteric methane (CH4), lactation performance, ruminal fluid characteristics, digestibility, and metabolism of N and energy in Holstein and Jersey cows. Twelve Holstein and 12 Jersey cows (all primiparous and mid-lactation) were used in a triplicated split-plot 4 × 4 Latin square experiment, where breed and diet formed the main and subplots, respectively. The 4 iso-nitrogenous and iso-starch dietary treatments were arranged as a 2 × 2 factorial with 2 levels of FNDF [19 (low FNDF, LF) and 24% (high FNDF, HF) of dry matter] and 2 sources of FNDF (70:30 and 30:70 ratio of AS NDF to CS NDF). Soyhull (non-forage NDF) and corn grain were respectively used to keep dietary NDF and starch content similar across diets. Total collection of feces and urine over 3 d was performed on 8 cows (1 Latin square from each breed). The difference in dry matter intake (DMI) between Holsteins and Jerseys was greater when fed AS than CS. Compared with Jerseys, Holstein cows had greater body weight (48%), DMI (34%), fat- and protein-corrected milk (FPCM; 31%) and CH4 production (22%; 471 vs. 385 g/d). However, breed did not affect CH4 intensity (g/kg of FPCM) or yield (g/kg of DMI), nutrient digestibility, and N partitioning. Compared with HF, LF-fed cows had greater DMI (10%), N intake (8%), and FPCM (5%), but they were 5% less efficient (both FPCM/DMI and milk N/intake N). Compared with HF, LF-fed cows excreted 11 and 17% less urinary N (g/d and % of N intake, respectively). In spite of lower (2.5%) acetate and higher (10%) propionate (mol/100 mol ruminal volatile fatty acids) LF-fed cows had greater (6%) CH4 production (g/d) than did HF-fed cows, most likely due to increased DMI, as affected mainly by the soyhulls. Compared with AS, CS-fed cows had greater DMI (7%) and FPCM (4%), but they were less efficient (5%), and CH4 yield (g/kg of DMI) was reduced by 8%. In addition, per unit of gross energy intake, CS-fed cows lost less urinary energy (15%) and CH energy (11%) than did AS-fed cows. We concluded that, in contrast to level and source of FNDF, breed did not affect digestive and metabolic efficiencies, and, furthermore, neither breed nor dietary treatments affected CH4 intensity. The tradeoff between CH4 and N losses may have implications in future studies assessing the environmental effects of milk production when approached from a whole-farm perspective.

Effects of ensiling time on corn silage neutral detergent fiber degradability and relationship between laboratory fiber analyses and in vivo digestibility

Accurate analysis of degradability of silage neutral detergent fiber (NDF) is important for diet formulation and to predict lactational performance of dairy cows. In this study, 5 corn silage hybrids ensiled for 0 (unfermented), 30, 60, 120, and 150 d were used to determine the effects of ensiling time on silage neutral detergent fiber degradability (NDFD) and to assess the relationships between near-infrared reflectance spectroscopy (NIR) NDF-related analyses and in situ NDFD variables. In addition, the relationships between dietary concentration of indigestible NDF, 288-h incubation (iNDF288), or undegraded NDF, 240-h incubation (uNDF240), and in vivo total-tract apparent organic matter and NDF digestibility were studied in total mixed ration samples from 16 experiments with lactating dairy cows. Ensiling time had no effect on silage NDF concentration; however, the ratio of acid detergent fiber ÷ NDF increased, and estimated hemicellulose concentration decreased quadratically with ensiling time. Also, concentration of NDF-bound protein decreased, and that of lignin increased linearly with ensiling time. These changes in silage fiber composition resulted in a linear decrease in in situ effective degradability of silage NDF with increasing ensiling time. The indigestible fraction of NDF and concentration of structural carbohydrates were not affected by ensiling time. Correlations of in situ NDFD variables with laboratory NIR NDFD analyses were weak to moderate. The relationship of corn silage uNDF240 with lignin concentration or 30-h NDFD (all NIR analyses) was remarkably good (R2 = 0.73 and 0.88, respectively). The relationship between in situ iNDF288 concentration (but not uNDF240) and in vivo total-tract apparent digestibility of dietary organic matter and NDF was good (R2 = 0.72 and 0.80, respectively). In conclusion, in situ degradability of silage NDF linearly decreased from 0 to 150 d ensiling time, primarily caused by a decrease in concentrations of hemicellulose and NDF-bound protein. In situ NDF degradability measurements and common laboratory NIR NDF-related analyses were generally poorly correlated. We found a good relationship between in vivo NDF digestibility and dietary concentration of iNDF288 determined in situ, but the relationship with uNDF240 was poor.

411 Relationships between dietary composition and reproductive outcomes in cattle

Abstract Individual experiments and recent literature summaries suggest links between reproductive outcomes in cattle and dietary composition. The objective of this meta-analysis was to evaluate the effects of dietary composition on reproductive efficiency of cows and heifers. A literature search returned 42 previously published papers containing 164 treatment means that were eligible for use in the meta-analysis. Diet composition information of interest included neutral detergent fiber (NDF), acid detergent fiber (ADF), organic matter (OM), crude protein (CP), lignin, ether extract (EE), non-structural carbohydrate (NSC) and starch percentages. For papers to be included, they needed to report reproductive outcomes, dry matter intake (DMI), experimental design details (treatments, design, number of experimental units, measurement SE or SD values, and P-values), and diets with all ingredients and inclusion percentages. Details on diet composition, intake, and reproductive outcomes were extracted from these papers and analyzed using linear mixed effects models with a random intercept for each study. When diet composition information was not reported, it was estimated from commercial feed library data and reported dietary feed inclusion rates. Days to service, days to ovulation, pregnancy at first artificial insemination, and overall pregnancy rate were the primary reproductive outcomes of interest. Significant variables were identified through a backward elimination approach. Overall pregnancy rate tended to be affected by the percentage of lignin in the diet (P = 0.078). Days to service was affected by dietary NDF (P = 0.013), ADF (P = 0.022), and starch (P = 0.027) percentages, and tended to be affected by lignin (P = 0.0768) percentage. Days to ovulation and pregnancy at first artificial insemination were not affected by the nutritional factors tested here. Additional assessment is needed to assess how dietary factors interact with other experimental and environmental variables to influence reproductive outcomes.

Partial corn replacement by soybean hull, or hay supplementation: Effects of increased NDF in diet on performance, metabolism and behavior of pre-weaned calves

The solid diet is a determining factor for ruminal development in calves. However, it is still unclear what is the optimal content and the best way to include fiber in the diet of pre-weaned calves. Thirty-five Holstein calves were used in a randomized block design, considering the sex, weight and birth date of the calves as blocking factor. Animals were housed in individual suspended cages without bedding and assigned to one of three treatments: (1) 22NDF: conventional ground starter concentrate with 220 g neutral detergent fiber (NDF)/kg dry matter (DM); (2) 31NDF: ground starter with 310 g NDF/kg DM, with partial replacement of corn by soybean hull; and (3) 22NDFhay: conventional starter with 220 g NDF/kg DM plus coast-cross hay fed separately ad libitum. The calves received 4 L of milk replacer with 12.5% solids, divided into two meals daily. Feed intake was measured daily. Weight gain and metabolic indicators of intermediate metabolism were evaluated weekly. Ruminal fluid was collected on week 4, 6 and 8 of age. The experiment lasted for 56 days. The increase of the NDF content in the concentrate starter up to 310 g/kg DM with replacement of corn by soybean hull or hay supplementation did not change the starter intake and performance of calves at weaning. The 31NDF diet resulted in higher concentration of short chain fatty acid (SCFA) at week 4, but 22NDF diet increased total SCFA concentration at week 8. Hay supplementation increased rumination time, and decreased non-nutritive oral behaviors during last week preweaning. Dietary NDF levels used in the ground starter concentrate may be higher than current recommendations without reducing intake and performance, as long as the NDF source has low ADF and lignin.

Predicting nutrient digestibility and energy value for broilers.

Digestibility coefficients of nutrients, metabolizable energy (ME), net energy (NE) and the ratio of NE to ME (NE/ME) of 20 diets were measured in broiler chickens (1 to 21 d). Dietary nutrients were formulated to keep similar ME/nutrient ratios, except for dietary protein, fat, and fiber using corn, soybean meal, animal protein blend, barley, poultry oil and an enzyme mixture of xylanase, glucanase, and phytase. Digestibility coefficients of nutrients and ME were measured in battery cages under free-access of feed, while NE was measured in floor pens feeding 75% of recommended ME intake each day. NE for maintenance was calculated on basis of mean metabolic weight using a coefficient from a previous study and NE for gain was calculated by body protein and fat gains using dual-energy x-ray absorptiometry. Digestibility coefficients of protein and neutral detergent fiber (NDF) were curvilinearly related to dietary protein and NDF, respectively, while digestibility coefficients of fat and starch were linearly correlated to dietary fat and starch, respectively. The inclusion of enzymes increased the digestion coefficient of NDF to predict the digestibility of protein, NDF, fat, and starch. MEn/gross energy ratio averaged 72.5% and was correlated to protein, fat, NDF, and starch. ME values were accurately predicted from chemical characteristics, where best equations were obtained from digestible nutrients. Energetic efficiencies of ME were 72% (NE/MEn) and 68% (NE/ME) and varied by about 20 and 18%, respectively. Ratios of energetic efficiency were 68% for digestible carbohydrates; 86% for digestible fat; and 76% (NE/MEn) and 59% (NE/ME) for digestible protein. According to the lowest residual standard deviation the best nutrient components to predict energy were digestible nutrients for predicting ME values (41kcal/kg); digestible protein intake, fecal organic matter, and body fat and protein for predicting heat increment values (111kcal/kg); and combination of ME and crude nutrient for predicting NE values (140kcal/kg).

Effects of the supplementation of distillers’ grape residues on ruminal degradability, whole tract digestibility and nitrogen metabolism in sheep

ABSTRACTFive ruminally and duodenally cannulated Kazakh male lambs (30 ± 2.75 kg) maintained singly in a metabolic cage were used in a 5 × 5 Latin square experiment to investigate the effect of supplementing a ration with five different levels of distillers’ grape residue (DGR) on ruminal degradability, whole tract digestibility and nitrogen (N) metabolism of growing lambs. The rations were isoenergetic and isonitrogenous and contained 0, 3.85, 7.70, 11.55 and 15.41% DGR (DM basis). Each experimental period lasted for 18 d: 10 d for adaptation to the dietary treatment and 8 d for faecal, urinary, ruminal and duodenal digesta sample collections. The outflow rate of ruminal digesta increased (p = 0.032) linearly with the increased level of dietary neutral detergent fibre content, caused by the supplementation of DGR. As a result, the effective degradability of dry matter and crude protein decreased significantly with the treatments. Although the dietary intake of N, duodenal flow of total N, and the endogenous N at the duodenum were not affected by experimental treatments, N fractions in the digesta were altered. Ruminal microbial N decreased (p < 0.01) linearly; in contrast, ruminal un-degradable protein increased linearly (p < 0.01) in response to the increased addition of DGR. Although there was no significant difference in faecal N among treatments, N retention was increased linearly (p = 0.014), owing to the remarkable reduction (p = 0.016) of urinary N excretion with an increasing level of DGR. The results indicate that the DGR has some potential benefits of increasing the supply of bypass protein and of improving the utilisation efficiency of N for sheep. Therefore, the supplementation of DGR in ruminant feeding is recommended at levels not exceeding 10% of the diet.

Regression analysis to predict the impact of dietary neutral detergent fiber on carcass yield in swine.

Research has shown that carcass yield in swine is reduced when ingredients with high neutral detergent fiber (NDF) content. Carcass yield reduction from feeding high-fiber ingredients results from an increase in the weight of intestinal contents. NDF has been shown to result in the digestive contents to swell in the large intestine by absorbing water thus increasing the fecal volume in the large intestine. Considering the financial implications of changing carcass yield, the objective of this project was to develop a regression equation to estimate carcass yield from dietary NDF and strategies where high-NDF ingredients are taken out of the diet in the last dietary phases before slaughter (withdrawal period; WP). Data from 8 experiments (43 observations) originated from 6 journal articles and 1 technical memo were used to develop the regression equation. The WP of high NDF ingredients was either none or ranged from 5 to 63 d in the experiments. Treatment diets of each trial were reformulated to obtain dietary nutrient content using the NRC ingredient library (NRC, Nutrient requirements of swine. 11th ed, 2012). Composition of experimental diets was used to calculate dietary net energy, crude protein, crude fiber, NDF, and acid detergent fiber in the last two dietary phases. These dietary compositions along with the number of days of WP were used to develop regression equations. The model was determined using a step-wise selection procedure starting with guided forward selection through individual predictor variables, with a statistical significance at P < 0.05 used to determine inclusion of terms in the final model. The regression analysis showed that WP, NDF level in the dietary phase prior to the final phase (NDF1), NDF level in the last dietary phase before marketing (NDF2), and the interaction between NDF2 and WP were the most important variables in the dataset to predict carcass yield. The resulting regression equation was as follows: carcass yield, % = 0.03492 ± 0.02633 × WP (d) - 0.05092 ± 0.02862 × NDF1 (%) - 0.06897 ± 0.02931 × NDF2 (%) - 0.00289 ± 0.00216 × (NDF2 [%] × WP [d]) + 76.0769 ± 1.33730. In conclusion, high levels of NDF up to slaughter had a negative impact on carcass yield. Increasing the length of the WP improved carcass yield; however, the effect of WP was dependent on the level of NDF2. The equation herein provides a tool to estimate of the impact of dietary NDF on carcass yield.

Effect of exogenous fibrolytic enzymes and ammonia fiber expansion on the fermentation of wheat straw in an artificial rumen system (RUSITEC)1.

This study investigated the effect of treatment of wheat straw using ammonia fiber expansion (AFEX) and exogenous fibrolytic enzymes (Viscozyme) on fiber digestibility, rumen fermentation, microbial protein synthesis, and microbial populations in an artificial rumen system [Rumen Simulation Technique (RUSITEC)]. Four treatments were assigned to 16 vessels (4 per treatment) in 2 RUSITEC apparatuses in a randomized block design. Treatments were arranged as a 2 × 2 factorial using untreated or AFEX-treated wheat straw with or without exogenous fibrolytic enzymes [0 or 500 μg of protein/g straw dry matter (DM)]. Fibrolytic enzymes were applied to straw, prior to sealing in nylon bags. The concentrate mixture was provided in a separate bag within each fermentation vessel. The RUSITECs were adapted for 8 d and disappearance of DM, neutral detergent fiber (NDF), acid detergent fiber (ADF), and crude protein (CP) was measured after 48 h of incubation. Ammonia fiber expansion increased (P < 0.01) the disappearance of wheat straw DM (69.6 vs. 38.3%), NDF (65.6 vs. 36.8%), ADF (61.4 vs. 36.0%), and CP (68.3 vs. 24.0%). Total dietary DM, organic matter (OM), and NDF disappearance was also increased (P ≤ 0.05) by enzymes. Total microbial protein production was greater (P < 0.01) for AFEX-treated (72.9 mg/d) than untreated straw (63.1 mg/d). Total gas and methane (CH4) production (P < 0.01) were also greater for AFEX-treated wheat straw than untreated straw, with a tendency for total gas to increase (P = 0.06) with enzymes. Ammonia fiber expansion increased (P < 0.01) total volatile fatty acid (VFA) production and the molar proportion of propionate, while it decreased (P < 0.01) acetate and the acetate-to-propionate ratio. The AFEX-treated straw had lower relative quantities of fungi, methanogens, and Fibrobacter succinogenes (P < 0.01) and fewer protozoa (P < 0.01) compared to untreated straw. The pH of fermenters fed AFEX-treated straw was lower (P < 0.01) than those fed untreated straw. Both AFEX (P < 0.01) and enzymes (P = 0.02) decreased xylanase activity. There was an enzyme × straw interaction (P = 0.02) for endoglucanase activity. Enzymes increased endoglucanase activity of AFEX-treated wheat straw, but had no effect on untreated straw. The addition of enzymes lowered the relative abundance of Ruminococcus flavefaciens, but increased F. succinogenes. These results indicate that AFEX increased the ruminal disappearance of wheat straw and improved fermentation and microbial protein synthesis in the RUSITEC.

Effects of dietary fiber content and different fiber-rich ingredients on endogenous loss of fat and fatty acids in growing pigs

Effects of dietary fiber content and different fiber-rich ingredients on endogenous loss of fat and fatty acids in growing pigs

Adjusting for 30-hour undigested neutral detergent fiber in substitution of wheat straw and beet pulp for alfalfa hay and corn silage in the diet of high-producing cows

This study examined the feeding effects of wheat straw (WS) and beet pulp (BP) substituted for corn silage (CS) and alfalfa hay (AH) based on forage 30-h undigested neutral detergent fiber (uNDF30) on lactation performance in high-producing dairy cows. Twelve multiparous (body weight = 611 ± 31 kg, days in milk = 97 ± 13; 51 ± 3 kg/d of milk; mean ± standard error) Holstein cows were used in a replicated 3 × 3 Latin square design with 28-d periods. Three treatments were established by substituting WS for CS and AH such that the concentration of forage uNDF30 in all diets was the same. The treatments were (1) 0% forage uNDF30 from WS (WS0; control), (2) 50% forage uNDF30 from WS (WS50), and (3) 100% forage uNDF30 from WS (WS100). Beet pulp was added in the straw diets to achieve similar dietary neutral detergent fiber digestibility after 30-h incubation (NDFD30). The 3 diets were similar in forage uNDF30 (14% of dry matter), total uNDF30 (∼18.5% of dry matter), and NDFD30 (approximately 42% of neutral detergent fiber). The substitution of WS and BP for AH and CS decreased the proportion of forage (40, 31, and 22.3% of dry matter) and forage neutral detergent fiber (21.2, 19.7, and 18.3% of dry matter) for WS0, WS50, and WS100, respectively, in the diet. However, the substitution linearly increased mean rumen pH (5.90, 6.09, and 6.28 for WS0, WS50, and WS100, respectively), digestibility of nutrients, and selection for long particles of diets without affecting dry matter intake. The substitution also linearly increased cholesterol and blood urea nitrogen concentration in the blood. Milk fat percentage, fat production, fat:protein ratio, and milk urea nitrogen increased linearly when treatments changed from WS0 to WS100, whereas the production of energy-corrected milk (ECM) was not affected by the treatments. Milk yield and milk protein yield were affected in a curvilinear manner and were lower in WS100 than other treatments. The efficiency of ECM production linearly increased in the diet with higher inclusion of WS and BP substitution in the diet (1.66, 1.70, and 1.72 for WS0, WS50, and WS100, respectively), but body weight, body weight change, and backfat thickness of cows were not different among treatments. In conclusion, the substitution of WS and BP for CS and AH with fixed uNDF30 improved feed efficiency and rumen pH, decreased milk and protein yield, and did not affect ECM yield.

Dietary Nutritive Value, Dung Quality, Decomposition, and Nutrient Movement into Soil in Smooth Bromegrass Pastures

Legumes increase forage nutritive value in pastures; however, literature addressing the impacts on dietary nutritive value, dung quality, decomposition, and nutrient movement into soil remains scarce. Cattle grazing legume‐interseeded smooth bromegrass (Bromus inermis Leyss.) pastures may select diets with greater nutritive value and consequently produce dung that decomposes faster and increases nutrient movement into soil relative to cattle grazing N‐fertilized and unfertilized smooth bromegrass pastures. In 2014 and 2015, we collected rumen and dung samples from replicated experiments to evaluate effects of season (June and August), pasture type (legume‐interseeded, N‐fertilized, and unfertilized pastures), and harvest time (3, 7, and 30 d after deposition) on dietary nutritive value, dung quality, dung decomposition, and nutrient movement into soil. Cattle grazing legume‐interseeded pastures had similar dietary crude protein concentrations but 11% less dietary neutral detergent fiber concentrations than cattle grazing N‐fertilized pastures. Dung from cattle grazing legume‐interseeded pastures, meanwhile, had 5 to 12% greater N concentrations than dung from cattle grazing N‐fertilized and unfertilized pastures. From 3 to 30 d after deposition, dung C/N ratio decreased from 20.0 to 16.5; whereas, dry matter remaining diminished to 77.5%. Dung C/N ratio and dry matter remaining did not vary with season or pasture type. At Day 7, soil below dung from cattle grazing legume‐interseeded pastures had 20 and 42% greater inorganic N than soil below dung from N‐fertilized and unfertilized pastures. This research showed that pastures with legumes increases dietary nutritive value, resulting in greater dung quality and increased N movement into soil.

PSXI-14 Effects of dietary neutral detergent fiber and starch ratio on performance and milk composition in lactating dairy cows: a meta-analysis.

PSXI-14 Effects of dietary neutral detergent fiber and starch ratio on performance and milk composition in lactating dairy cows: a meta-analysis.

Short communication: Meta-analysis of dairy cows fed conventional sorghum or corn silages compared with brown midrib sorghum silage

A meta-analysis was conducted to compare the effects of feeding dairy cows conventional sorghum silage (CSS) or conventional corn silage (CCS) compared with brown midrib sorghum silage (BMRSS) diets on dry matter intake (DMI), milk production, and milk composition. Data from 9 published articles (1984 to 2015) were used to contrast diets with CSS (7 means comparisons; 104 cows) or CCS (13 means comparisons; 204 cows) versus BMRSS diets. Statistical analysis was performed using fixed or random effects models with the Metafor package of R (https://www.R-project.org). The degree of heterogeneity was measured with the I2 statistic, and publication bias was determined with funnel plots and Egger's regression test. Other sources of heterogeneity of response were analyzed through meta-regression. Estimated effect size was calculated for DMI, milk production, and milk composition. No evidence of publication bias was observed for any variable tested. The highest degree of heterogeneity (I2 = 41.5 and 72.6%) was observed for DMI among dependent variables tested in both comparisons, indicating that intake responses to silage type are rather inconsistent; in contrast, milk production had the lowest degree of heterogeneity (I2 = 0%), supporting the idea that the responses of this variable to silage type were very consistent across studies. Compared with BMRSS diets, cows fed CSS diets exhibited decreased milk production (1.64 kg/d), milk fat concentration (0.09%), milk fat yield (0.08 kg/d), milk protein yield (0.04 kg/d), and milk lactose yield (0.16 kg/d) and tended to decrease DMI (0.83 kg/d). Compared with CCS diets, cows fed BMRSS diets increased milk fat concentration (0.10%), but decreased milk protein concentration (0.06%) and tended to increase lactose yield (0.08 kg/d). Meta-regression indicated that days in milk affected DMI and milk production when CSS diets were compared with BMRSS diets, and DMI when CCS diets were compared with BMRSS diets. Additionally, the inclusion rate of silage in the diet and dietary neutral detergent fiber affected yields of milk fat and lactose, respectively, when CCS and BMRSS diets were compared. Overall, lactation performance improved when cows were fed diets formulated with BMRSS compared with CSS, but performance was not different for cows fed BMRSS and CCS diets. However, the small sample size may have influenced these results by increasing the margin of the error and, concurrently, the power of the meta-analysis. Results of this analysis suggest that additional research is needed to explore the effects of days in milk and the inclusion rates of silages in the diets when comparing BMRSS with CSS or CCS.

The effects of source and concentration of dietary fiber, starch, and fatty acids on the daily patterns of feed intake, rumination, and rumen pH in dairy cows

The daily patterns of feed intake and rumination influence rumen fermentation, rumen pH, and timing of absorbed nutrients in the dairy cow, but the effects of diet composition on these patterns are not well characterized. Data from 3 previously published experiments were examined to determine the influence of dietary starch, fiber, and fatty acids (FA) on daily patterns of intake, rumination, and rumen pH. Dietary neutral detergent fiber (NDF) and starch were investigated in 2 experiments, each with duplicated 4 × 4 Latin square designs with a 2 × 2 factorial arrangement of treatments in cows fed cows 1×/d at 1200 and 1400 h, respectively. To investigate fiber content and digestibility in the first experiment, brown midrib or isogenic conventional corn silage were fed in low- and high-NDF diets (29 and 38%, respectively). To investigate starch source and concentration in the second experiment, ground high-moisture corn or dry ground corn were fed in low- and high-starch diets (21 and 32%, respectively). Effect of fat concentration and saturation was investigated in the third experiment using a replicated 4 × 4 Latin square design that fed cows 1×/d at 0900 h; treatments included a control diet with no added fat and 2.5% added saturated FA, unsaturated FA, or a mixture of the saturated and unsaturated FA. In the first 2 experiments, intake followed a similar daily pattern regardless of starch and NDF concentration or digestibility. Rumination displayed a treatment by time interaction for both NDF and starch concentration, with high-fiber, low-starch diets causing greater rumination overnight but not midday. High-starch diets decreased total daily rumen pH equally across the day, but did not change the daily pattern. Type of corn silage did not affect the daily patterns of rumination or rumen pH, but pH was reduced throughout the day in brown midrib diets. In the third experiment, no interactions between fatty acid supplement and time of day were observed for intake, rumination, or rumen pH. Within all experiments, rumination fit or tended to fit a 24-h rhythm regardless of diet, with the amplitude of the rumination being reduced in low-starch diets and diets containing saturated FA or a mixture of saturated and unsaturated FA. Overall, intake, rumination, and rumen pH follow a daily pattern that was minimally modified by dietary fiber and starch type and level or fat level and fatty acid profile.