Dietary Nonfiber Carbohydrate Research Articles

Effect of dietary non-fiber carbohydrate source and inclusion of buffering on lactation performance, feeding behavior and milk stability of dairy cows

The present study hypothesized that partial replacement of ground corn (GC) by pelleted citrus pulp (PCP) and buffering (BF) inclusion in diets of lactating cows does not change lactation performance, but does reduce milk concentration of ionic calcium (iCa), increasing its stability at ethanol test and heating at 140 °C (heat coagulation time – HCT). We evaluated the effect of PCP and buffer inclusion on digestive metabolism, feeding behavior, milk yield, and milk stability of lactating cows. Sixteen Holstein cows (average milk yield of 28 ± 4.8 L/d and days in milk of 130 ± 81.0; mean ± SD) were distributed in a Latin square design with 4 replicated squares, 4 periods of 21 d (14 d for adaptation and 7 d for sampling) and 4 treatments in a 2 × 2 factorial arrangement. Treatment factor 1 was the partial replacement (134 g/kg) of GC by PCP and factor 2 was the inclusion of buffer (7.1 g/kg of Na bicarbonate plus 2.4 g/kg of Mg oxide; DM basis) in diets composed of 40:60 of forage: concentrate ratio. The partial replacement of GC with PCP reduced dry matter intake (DMI) by 1.35 kg/d, increased dry matter (DM) and neutral detergent fiber assayed with a heat stable amylase and expressed exclusive of residual ash (aNDFom) digestibility, and ruminal concentration of acetic and butyric acids, but no change was observed on milk yield, resulting in higher production efficiency. The partial replacement of GC with PCP also reduced the ruminal concentration of iso-butyric and iso-valeric acids, milk urea nitrogen concentration, and casein content and tended to reduce HCT. There was no isolated effect of GC replacement or buffer addition or their interaction on iCa concentration and milk stability at the ethanol test. For diets without the inclusion of PCP, cows increased drinking time by 8 min/d. When cows were fed diet with the inclusion of PCP, the rumination time decreased 57 min/kg physical effective aNDFom (peNDF) intake compared to when cows were fed diets without partial replacement of GC with PCP. The buffer inclusion increased milk fat content and urinary pH. However, milk stability at ethanol test did not change in response to treatments and HCT tended to be reduced when GC was replaced by PCP. The results of our study suggested that, although partial replacement of GC with PCP and BF inclusion altered DMI, short chain fatty acids (SCFA) concentration, and urinary pH, those factors did not change milk yield and milk stability.

Comparison of microbial fermentation data from dual-flow continuous culture system and omasal sampling technique: A meta-analytical approach

Although the omasal sampling technique (OST) has been successfully used to estimate ruminal fermentation and nutrient flow, alternatives to invasive animal trials should be pursued and evaluated. The objective of this study was to evaluate carbohydrate and N metabolisms using a meta-analytical approach to compare 2 methods: dual-flow continuous culture system (DFCCS) and OST. To be included, studies needed to report diet chemical composition and report at least 1 of the dependent variables of interest. A total of 155 articles were included, in which 97 used the DFCCS and 58 used the OST. The independent variables used were dietary nonfiber carbohydrate concentration, neutral detergent fiber (NDF) degradability, true crude protein (CP) degradability, and efficiency of microbial protein synthesis (EMPS). In addition, 12 dependent variables were used. Statistical analyses were performed using the Mixed procedure of SAS (SAS Institute Inc., Cary, NC). A random coefficients model was used considering study as a random effect and including the possibility of covariance between the slope and the intercept. The effect of method (DFCCS or OST) was included and tested in the estimates of the intercept, linear, and quadratic effects of the independent variable. There was no method effect when NDF degradability was regressed with total volatile fatty acids concentration, true CP degradability, and EMPS. Molar proportions of acetate and propionate were quadratically associated with NDF degradability. When NDF degradability was regressed with acetate and propionate there was a method effect, differing only in the intercept (β0) estimate. True organic matter digestibility, bacterial N/total N, efficiency of N utilization, total volatile fatty acid concentration, and molar proportion of butyrate linearly increased as dietary nonfiber carbohydrate concentration increased, and none of these variables were affected by method. Concentration of ammonia N had a linear and positive association with true CP degradability. This was the only variable that had a method effect when regressed with true CP degradability, differing only in the estimate of the intercept (β0). As EMPS increased, efficiency of N utilization also increased, and it was affected by method. Overall, the majority of DFCCS responses were similar to OST. When a method effect was observed, it was mainly on the estimate of the intercept, demonstrating that the magnitude of these responses was different. However, the relationships between independent and dependent variables were similar across methods.

Cross-sectional study of the effect of diet composition on plasma folate and vitamin B12 concentrations in Holstein cows in the United States and Canada

The objective of this cross-sectional study was to assess the variability of plasma folate and vitamin B12 concentrations in lactating Holstein cows across the United States and Canada. We also evaluated the effect of diet composition and cow characteristics on folate and vitamin B12 plasma vitamin concentrations. A total of 22 and 24 US and Canadian dairy herds were enrolled, totaling 427 and 476 cows at 10 to 197 days in milk across all US and Canadian herds, respectively. Blood samples were taken to analyze plasma folate and vitamin B12 concentrations, and ingredients of the diet were collected to determine nutrient composition. To reduce the number of interdependent variables in the analysis of the association of diet composition with plasma vitamin concentrations, we conducted a principal component analysis. Plasma folate concentrations were lower for US cows [13.4 ng/mL, 95% confidence interval (CI): 12.7-14.2] than for Canadian cows (14.5 ng/mL, 95% CI: 13.7-15.2), and the opposite was observed for plasma vitamin B12 concentrations (US 206 pg/mL, 95% CI: 192-221; Canada 170 pg/mL, 95% CI: 159-181). The highest plasma concentrations of both vitamins were observed in the Northwest region of the United States (Oregon and Washington). Cows in California had the lowest plasma folate concentrations, and cows in Québec and New York State had the lowest plasma vitamin B12 concentrations. Plasma folate concentrations were higher for multiparous than for primiparous cows and plasma vitamin B12 concentrations progressively increased from parity 1 to 3 and higher. For both studied vitamins, plasma concentrations were lower at 0 to 55 than at 56 to 200 days in milk. Of 3 principal components, the one associated with dietary carbohydrates was significantly correlated with plasma folate and vitamin B12 concentrations. Indeed, plasma folate concentrations decreased with dietary fiber concentrations (i.e., neutral and acid detergent fibers and lignin) and increased with dietary nonfiber carbohydrate concentrations. We obtained the opposite results for plasma vitamin B12 concentrations. Both multivariable models explained 41% (pseudo-R2) of the variation in plasma folate and vitamin B12 concentrations. Information gathered in this study is the first step toward determining sources of variation in plasma folate and vitamin B12 concentrations, as well as the vitamin status of cows.

Effects of the dietary nonfiber carbohydrate content on lactation performance, rumen fermentation, and nitrogen utilization in mid-lactation dairy cows receiving corn stover

BackgroundCorn stover (CS) is an abundant source of feed for livestock in China. However, it is low in nutritional value that we have been seeking technologies to improve. Previous studies show that non-fiber carbohydrate (NFC) might limit the utilization of a CS diet by lactating dairy cows. Thus, this study was conducted to investigate the lactation performance and rumen fermentation characteristics in lactating cows consuming CS with two contents of NFC compared to an alfalfa hay-containing diet. Twelve Holstein cows were used in a replicated 3 × 3 Latin square design with three dietary treatments: (1) low-NFC diet (NFC = 35.6%, L-NFC), (2) high-NFC diet (NFC = 40.1%, H-NFC), and (3) alfalfa hay diet (NFC = 38.9%, AH).ResultsIntake of DM was lower for cows fed H-NFC compared to L-NFC and AH, while the milk yield was higher in AH than in H-NFC and L-NFC (P < 0.01). The feed efficiency (milk yield/DM intake, 1.15 vs. 1.08, P < 0.01) were greater for cows fed H-NFC than L-NFC. The contents of milk protein and lactose were not different among the groups (P > 0.11), but milk fat content was higher for cows fed H-NFC and L-NFC compared to AH (P < 0.01). The rumen ammonia nitrogen concentration and the concentrations of urea nitrogen in blood and milk were lower for cows fed H-NFC and AH compared to L-NFC (P < 0.05). The concentrations of rumen propionate and total volatile fatty acids were different among groups (P < 0.05) with higher concentration for cows fed AH compared to H-NFC and L-NFC, and acetate concentration tended to be different among groups (P = 0.06).ConclusionsFrom the results obtained in this study, it was inferred that the increased NFC content in a diet containing corn stover can improve the feed efficiency and benefit the nitrogen conversion.

Associations among dietary non-fiber carbohydrate, ruminal microbiota and epithelium G-protein-coupled receptor, and histone deacetylase regulations in goats

BackgroundDiet-derived short-chain fatty acids (SCFAs) in the rumen have broad effects on the health and growth of ruminants. The microbe-G-protein-coupled receptor (GPR) and microbe-histone deacetylase (HDAC) axes might be the major pathway mediating these effects. Here, an integrated approach of transcriptome sequencing and 16S rRNA gene sequencing was applied to investigate the synergetic responses of rumen epithelium and rumen microbiota to the increased intake of dietary non-fiber carbohydrate (NFC) from 15 to 30% in the goat model. In addition to the analysis of the microbial composition and identification of the genes and signaling pathways related to the differentially expressed GPRs and HDACs, the combined data including the expression of HDACs and GPRs, the relative abundance of the bacteria, and the molar proportions of the individual SCFAs were used to identify the significant co-variation of the SCFAs, clades, and transcripts.ResultsThe major bacterial clades promoted by the 30% NFC diet were related to lactate metabolism and cellulose degradation in the rumen. The predominant functions of the GPR and HDAC regulation network, under the 30% NFC diet, were related to the maintenance of epithelium integrity and the promotion of animal growth. In addition, the molar proportion of butyrate was inversely correlated with the expression of HDAC1, and the relative abundance of the bacteria belonging to Clostridum_IV was positively correlated with the expression of GPR1.ConclusionsThis study revealed that the effects of rumen microbiota-derived SCFA on epithelium growth and metabolism were mediated by the GPR and HDAC regulation network. An understanding of these mechanisms and their relationships to dietary components provides better insights into the modulation of ruminal fermentation and metabolism in the promotion of livestock production.

Cinética de fermentação ruminal in vitro de dietas com inclusão do resíduo de feijão (Phaseolus vulgaris L.) substituindo a torta de algodão

Objetivou-se com esta pesquisa avaliar os parâmetros fermentativos ruminal in vitro da inclusão de resíduo de feijão (Phaseolus vulgaris L.) em substituição à torta de algodão. Os tratamentos experimentais foram constituídos pela substituição da torta de algodão nos níveis de 0, 33, 66 e 100% por resíduo de feijão. O preparo das amostras foi realizado utilizando 500 mg de amostra seca ao ar, moída a 1 mm, onde imediatamente após a adição do inoculo, os frascos receberam tampa de borracha, lacre de alumínio e foram colocados em banho-maria, com agitação orbital, a 39ºC. As leituras de pressão foram realizadas por meio de um transdutor de pressão nos seguintes tempos: 1, 2, 4, 6, 8, 10, 12, 15, 18, 24, 30, 36, 48, 60, 72, 84 e 96 horas. A cinética da produção cumulativa dos gases foi analisada empregando-se o modelo logístico bicompartimental. O volume final de gases da fração de carboidratos não-fibrosos das dietas não apresentou efeito significativo (p&gt;0,05), enquanto a taxa de degradação da fração de carboidratos não-fibrosos, o volume de gases da fração de carboidratos fibrosos, a taxa de degradação da fração de carboidratos não-fibrosos e a latência apresentaram aumento linear significativo (p&lt;0,05). A adição do resíduo de feijão em substituição à torta de algodão potencializa uma maior disponibilização de nutrientes devido à melhora dos parâmetros ruminais in vitro.

Rapid Fermentable Substance Modulates Interactions between Ruminal Commensals and Toll-Like Receptors in Promotion of Immune Tolerance of Goat Rumen.

Whether dietary non-fiber carbohydrate (NFC), a rapid fermentable substance, affects immune homeostasis of rumen through the modulation of interactions of ruminal microbiota and epithelial toll-like receptors (TLRs) remains unclear. A combination of 16S rRNA amplicon sequencing and quantitative PCRs was applied to study the synergetic responses of ruminal microbiota and epithelial TLRs to the dietary NFC switch from 15 to 31% in the goat model. The results showed that the 31% NFC diet caused the radical increases on the richness and diversity of rumen microbiota. The phylum Verrucomicrobia was most significantly expanded, whereas opportunistic pathogens, namely Rikenella, Anaeroplasma, and Olsenella, were significantly decreased. In rumen epithelium, the significantly increased expressions of TLR1, 6, 10 were associated with the significantly decreased expressions of pro-inflammatory cytokines interleukin-1beta (IL-1ß), IL-6, and anti-inflammatory cytokine IL-10. Constrained correlation analysis indicated that the increased abundance of commensal bacteria in Verrucomicrobia subdivision 5 contributed to the upregulation of TLR10 expression. Finally, the significantly increased concentrations of rumen short-chain fatty acids (SCFAs), coupled with the significantly upregulated expressions of epithelial genes related to SCFA absorption were observed in goats fed with 31% NFC diet. Thus, the NFC-induced expansion of rumen microbiota promoted epithelium tolerance by enhancement of the intensity of TLR10 signaling. The newly established equilibrium benefited to the transport of ruminal energy substances into the blood.

Effect of increasing dietary nonfiber carbohydrate with starch, sucrose, or lactose on rumen fermentation and productivity of lactating dairy cows

The objective of this study was to investigate effects of increasing dietary nonfiber carbohydrate (NFC) with starch, sucrose, or lactose on rumen fermentation, volatile fatty acid absorption, and milk production of lactating dairy cows. Twenty-eight multiparous, lactating Holstein cows (141±50 d in milk; 614±53kg of body weight) including 8 ruminally cannulated cows were used in this study. Cows were assigned to 4 dietary treatments in a 4×4 Latin square design with 21-d periods. The treatments were control [27% starch and 4% sugar on a dry matter (DM) basis], a high-NFC diet by increasing dietary starch content (STA; 32% starch and 4% sugar on a DM basis), and 2 more high-NFC diets by increasing dietary sugar content (27% starch and 9% sugar on a DM basis) in which sucrose (SUC) or lactose (LAC) was supplemented. Dry matter intake was greater for cows fed high-NFC diets compared with control diet (27.1 vs. 26.3kg/d), but rumen pH and milk production did not differ between cows fed control and high-NFC diets. However, cows fed high-disaccharide diets had lower mean rumen pH than those fed STA diet (6.19 vs. 6.32). Although molar proportion of butyrate was greater for high-disaccharide treatments than STA treatment (15.2 vs. 13.7 mol/100 mol), absorption rate of volatile fatty acid in the rumen was not affected by treatment. In addition, cows fed high-disaccharide diets had higher energy-corrected milk yield than cows fed STA diet (39.6 vs. 38.0kg/d). Dry matter intake did not differ between cows fed 2high-disaccharide diets. Although cows fed the SUC diet had lower molar proportion of butyrate in the rumen compared with those fed the LAC diet (14.4 vs. 15.9 mol/100 mol), the SUC diet did not decrease rumen pH. In addition, cows fed the SUC diet had lower nutrient digestibility of organic matter than did those fed the LAC diet (59.7 vs. 64.4%), but milk component yields did not differ between the 2 high-disaccharide diet treatments. The results of the present study suggested that partially replacing dietary starch with disaccharides increased DM intake and energy-corrected milk, although rumen pH decreased for high-disaccharide diets, and that the rumen pH responses cannot be attributed to difference in absorption rate of volatile fatty acids in the rumen. In addition, type of sugars affected nutrient digestibility and rumen fermentation, but the effects were not large enough to affect rumen pH and milk production.

Effects of Increasing Non-Fiber Carbohydrate to Neutral Detergent Fiber Ratio on Rumen Fermentation and Microbiota in Goats

Six rumen-cannulated lactating Guanzhong goats were used to investigate changes in ruminal fermentation pattern and the microbiota following a subacute ruminal acidosis (SARA) inducing procedure. Induction of SARA was performed by increasing dietary non-fiber carbohydrate (NFC) to neutral detergent fiber (NDF) ratio from 1.02 (stage 1) to 1.24 (stage 2), 1.63 (stage 3) and 2.58 (stage 4). A dynamic pH monitoring system, real-time fluorescent quantitative PCR and conventional anaerobic culture were used to assess changes in ruminal pH and microbiota. Results indicated that rumen fermentation patterns changed significantly with increased NFC: NDF ratio. The decline in ruminal pH was caused by increased ruminal total volatile fatty acids (TVFA), which was mainly attributed to a significant increase in ruminal butyrate, rather than the accumulation of ruminal lactic acid. In addition, in the course of SARA, the number of rumen microoganisms altered significantly, with increases in ruminal amylolytic bacteria, Lactobacilli, Streptococcus bovis and Megasphaera elsdenii, the latter particularly dramatically indicating that it may be the main factor responsible for the increase in butyrate, and decrease in protozoa.

Influences of dietary nitrogen and non-fiber carbohydrate levels on apparent digestibility, rumen fermentation and nitrogen utilization in growing yaks fed low quality forage based-diet

The effects of dietary N and non-fiber carbohydrate (NFC) levels on nutrient digestibility, ruminal fermentation, and nitrogen utilization were investigated in growing yaks. Four diets (N content: 1.43%, 1.97%, 2.45% and 2.90% of DM basis; ratio of dietary NFC and RDP: 5.9, 3.2, 2.2 and 1.6) were offered to four yaks in a 4×4 Latin square design. Dietary N and NFC did not affect the gastrointestinal tract digestibility of DM, organic matter (OM), NFC, NDF, or ADF (P>0.05). Ruminal pH value, molar proportion of butyrate, and ratio of acetate to propionate were not affected by the diets (P>0.05); whereas, molar proportions of acetate, propionate, iso-butyrate, iso-valerate, valerate, and total VFA concentration in rumen fluid increased linearly (P<0.01) with increase in dietary N and decrease in dietary NFC. Except for ruminal NH3-N and soluble protein N, free amino acid-N and peptide-N maintained constantly within the sampling time (from 0 to 8h of post feeding; P>0.05). The increment of N intake linearly increased the N retention (P=0.003), but no difference (P>0.05) was observed in the ratio of N retention to the gastrointestinal trace absorbed N after dietary N reached to 2.45% of DM. Microbial N supply had linear and quadric (P<0.001) responses to the dietary N, and the highest microbial N synthesis efficiency was observed when the yaks were fed with 1.97% N diet in which ratio of NFC to RDP was 3.2, and dietary NFC and RDP were 20.2% and 6.7% of DM, respectively. Total purine derivatives excretion and microbial purine N:total N had a quadric (P<0.05) response to the dietary N. Results of the current experiment suggest that maximizing N utilization and microbial efficiency were obtained when the yaks were fed a diet with an optimal dietary ratio of NFC to RDP.

Carbohydrate source and protein degradability alter lactation, ruminal, and blood measures

Thirty-eight lactating dairy cows including 6 ruminally cannulated cows were used in a feeding study to assess effects of feed sources that differed in dietary nonfiber carbohydrate (NFC) composition and ruminal degradability of dietary protein (RDP) on production, ruminal, and plasma measures. The design was a partially balanced, incomplete Latin square with three 21-d periods and a 3 × 2 factorial arrangement of treatments. Samples and data were collected in the last 7 d of each period. Feed sources that differed in NFC profile were dry ground corn (GC; starch), dried citrus pulp (DCP; sugar and pectins), and sucrose+molasses (SM; sugar). Dietary RDP was altered by providing CP with soybean meal (+RDP) or substituting a heat-treated expeller soybean product for a portion of the soybean meal (−RDP). Diets were formulated to be isonitrogenous and similar in NFC concentration. Cows consuming GC had the greatest milk urea nitrogen and milk protein percentage and yield, tended to have the greatest dry matter intake, but had a lesser milk fat percentage compared with cows consuming DCP and SM. Sucrose+molasses diets supported greater dry matter intake, milk protein yield, and 3.5% fat- and protein-corrected milk yield than did DCP diets. On −RDP diets, milk protein percentage was less and milk urea nitrogen and protein yield tended to be less than for +RDP diets. Dry ground corn diverged from DCP and SM in the effect of NFC × RDP, with cows consuming GC having lesser milk yield, 3.5% fat- and protein-corrected milk yield, and efficiency with −RDP as compared with +RDP, whereas these production measures were greater with −RDP than +RDP for cows consuming DCP and SM. In contrast, in situ NDF digestibility at 30h for GC and SM was greater for −RDP as compared with +RDP, but the reverse was true for DCP. The lowest ruminal pH detected by 6h postfeeding was also influenced by the interaction of NFC × RDP, with cows consuming SM having a lower pH with +RDP than with −RDP and cows consuming DCP having a similar pH on either RDP treatment. Total rumen volatile fatty acid concentrations did not differ among diets, but acetate molar percent was greater for DCP than for SM, and GC had the lowest molar percent for butyrate and valerate and greatest branched-chain volatile fatty acid concentration. Valerate molar percent and NH3 concentration tended to be greater with +RDP than with −RDP. Plasma glucose and insulin were both greater in cows receiving SM than in those receiving DCP. Protein degradability, NFC source, and their interactions affected lactation, ruminal, and blood measures, suggesting that these dietary factors warrant further consideration in diet formulation.

Metabolism of Dairy Cows as Affected by Prepartum Dietary Carbohydrate Source and Supplementation with Chromium Throughout the Periparturient Period

Holstein cows (n=72) entering second or later lactation were used to determine whether metabolic indices and hepatic capacities for oxidation and gluconeogenesis from propionate are affected by source of carbohydrate in the prepartum diet and chromium-l-methionine (Cr-Met) supplementation throughout the periparturient period. Cows were fed prepartum diets as total mixed rations with the concentrate portion based either on starch-based cereals [high nonfiber carbohydrate (NFC); 1.59 Mcal/kg of net energy for lactation (NEL), 14.4% crude protein (CP), 40.3% NFC] or nonforage fiber sources (low NFC; 1.54 Mcal/kg of NEL, 14.5% CP, 33.6% NFC) from 21 d before expected parturition until parturition. After parturition all cows were fed a common lactation total mixed ration (1.74 Mcal/kg of NEL, 16.5% CP, 40.0% NFC). The Cr-Met was supplemented once daily via gelatin capsule at dosages of 0, 0.03, or 0.06mg of Cr/kg of BW0.75. Thus, treatments were in a 2 (carbohydrate source)×3 (Cr-Met) factorial arrangement. There was no effect of prepartum carbohydrate source on pre- and postpartum plasma concentrations of glucose, nonesterified fatty acids (NEFA), β-hydroxybutyrate (BHBA), insulin, glucagon, or insulin to glucagon ratio. However, cows fed the low NFC diet during the prepartum period tended to have greater plasma NEFA and lower BHBA concentrations postpartum. Liver glycogen concentrations tended to be greater on d 1 postpartum for cows fed low NFC prepartum. Supplementing 0.03 mg/kg of BW0.75 of Cr as Cr-Met increased prepartum plasma glucose and glucagon concentrations and tended to decrease prepartum plasma NEFA concentrations compared with either 0 or 0.06mg of Cr/kg of BW0.75. Postpartum plasma glucose concentrations decreased linearly and glucagon concentrations were increased quadratically by administering increasing amounts of Cr-Met. Supplementing Cr-Met did not affect prepartum plasma concentrations of insulin or BHBA, postpartum NEFA or BHBA, or liver composition. There was an interaction of prepartum carbohydrate source and Cr-Met supplementation such that in vitro hepatic conversion of [1-14C]propionate to both CO2 and glucose was similar or increased when Cr-Met was supplemented to cows fed the low NFC diet but decreased when Cr-Met was supplemented to cows fed the high NFC diet. Insulin addition in vitro did not affect hepatic metabolism of propionate on d 1 postpartum. Overall, both the NFC content of the prepartum diet and Cr-Met had only modest effects on metabolic indices in this experiment.

Dietary Forage and Nonfiber Carbohydrate Contents Influence B-Vitamin Intake, Duodenal Flow, and Apparent Ruminal Synthesis in Lactating Dairy Cows

The objective of this experiment was to quantify intakes, duodenal flows, and ruminal apparent synthesis (AS) of B-vitamins in lactating dairy cows fed diets varying in forage and nonfiber carbohydrate (NFC) contents. Eight (4 primiparous and 4 multiparous) ruminally and duodenally cannulated Holstein cows were assigned to 4 dietary treatments in a replicated 21-d period, 4×4 Latin square design with a 2×2 factorial treatment arrangement. Diets, fed as TMR, contained (DM basis) 2 levels of forage (35 and 60%) and 2 levels of NFC (30 and 40%). The forage portion of the diets contained 50% corn silage, 33% alfalfa hay, and 17% grass hay. Soybean hulls and beet pulp (2:1) and corn meal and ground barley (2:1) were included to achieve desired NFC concentrations. No supplemental B-vitamins were fed. B-vitamin AS was calculated as the amount of a specific B-vitamin flowing to the duodenum minus its daily orts-corrected intake. Dry matter and organic matter intakes were higher for cows fed the 35% forage diets and the 40% NFC diets. Increasing dietary forage content decreased ruminal AS of pyridoxine, folic acid, and B12. Increasing dietary NFC content increased ruminal AS of nicotinic acid, nicotinamide, niacin, pyridoxal, B6, and folic acid but decreased AS of B12. Across diets, amounts of B-vitamins synthesized were highest for niacin, followed by riboflavin, B12, thiamin, B6, and folic acid. Biotin AS values were negative for all diets, suggesting either no ruminal synthesis or that destruction by ruminal microflora was greater than synthesis. B-vitamin intake, duodenal flow, and ruminal synthesis are influenced by dietary forage and NFC contents.

Performance of Dairy Cows as Affected by Prepartum Dietary Carbohydrate Source and Supplementation with Chromium Throughout the Transition Period

Holstein cows (n=72) entering second or later lactation were used to determine whether productive performance and dry matter intake (DMI) are affected by carbohydrate source in the prepartum diet and chromium-l-methionine (Cr-Met) supplementation throughout the periparturient period. Cows were fed either a TMR with the concentrate portion based on starch-based cereals [high nonfiber carbohydrate (NFC); 1.59 Mcal/kg of net energy for lactation (NEL), 14.4% crude protein (CP), 40.3% NFC] or a TMR with the concentrate portion based on nonforage fiber sources (low NFC; 1.54 Mcal/kg NEL, 14.5% CP, 33.6% NFC) from 21 d before expected parturition until parturition. After parturition all cows were fed a lactation TMR (1.74 Mcal/kg NEL, 16.5% CP, 40.0% NFC). The Cr-Met was supplemented once daily via gelatin capsule at dosages of 0, 0.03, or 0.06mg of Cr/kg of metabolic body weight. Thus, treatments were in a 2 (carbohydrate source)×3 (Cr-Met) factorial arrangement. Neither prepartum nor postpartum DMI was affected by prepartum dietary carbohydrate source. Administering increasing amounts of Cr-Met linearly increased milk yield and, subsequently, postpartum DMI. Prepartum carbohydrate source did not affect postpartum milk yield; however, cows fed the low NFC diet tended to yield milk with a lower content of total solids. These data indicate that prepartum carbohydrate source has little influence on performance during the immediate peripartal period, and that increases in milk yield for cows supplemented with Cr-Met are independent of prepartum dietary carbohydrate source.

Influence of dietary nonfiber carbohydrate concentration and supplementation of sucrose on lactation performance of cows fed fescue silage.

There is interest in knowing if the source of nonfibrous carbohydrates (NFC) influences milk production and composition. Our objective was to determine the effects of source (starch or sugar) and level of NFC in the diet on these parameters. A 4 x 4 Latin square replicated five times using early-lactation (56 +/- 9 DIM) Holstein cows was used; cows were offered one of two levels of NFC and either no added sucrose or sucrose substituting for 10% of the corn. Diets were balanced to meet National Research Council requirements for total protein, energy, and minerals. Tall fescue silage was included at one of two levels (0.95 or 1.25% of BW as forage NDF), resulting in diets with 40 and 30% NFC. The remaining ingredients consisted of high-moisture corn, soybean meal, SoyPlus, minerals, and vitamins. Megalac (0.45 kg) was used in the low NFC diets. High NFC diets were lower (P < 0.01) in neutral detergent fiber (NDF; 31.5%) and crude protein (CP; 19.6%) than the low NFC diet (35.8% NDF and 21.0% CP). Sucrose containing diets were somewhat lower (P < 0.01) in NDF (33.1%) than the no sucrose added diets (34.3%), but diets did not differ in CP%. Cows offered the high NFC level produced more milk (39.6 kg/d; P < 0.05) than those offered the low level (38.3 kg/d), primarily due to higher dry matter intake (P < 0.05). Cows consuming the high NFC diet also had lower (P < 0.05) milk fat (3.25%) and milk urea nitrogen (MUN; 13.7 mg/dl), and higher (P < 0.05) milk protein (2.58%) and milk lactose (4.81%) concentrations than cows offered the low NFC level (3.46% milk fat, 17.5 mg/dl MUN, 2.51% milk protein, and 4.74% milk lactose). Fat yield was higher (P < 0.05) for cows fed low NFC diets than cows fed high NFC diets, whereas protein and fat yield were lower (P < 0.05) for cows fed low NFC diets than those fed high NFC diets. The NFC source did not influence dry matter intake or milk production or milk component yield (P > 0.05). Milk lactose (4.79%) and MUN (16.0 mg/dl) concentrations were higher (P < 0.05) for cows offered sucrose as a portion of the NFC compared with those not offered sucrose (4.76% milk lactose and 15.2 mg/dl MUN). Results suggest that cows fed sucrose may utilize diet nitrogen less efficiently than those not fed sucrose, when sucrose is replacing a portion of the high-moisture corn in the diet.

Influence of nonfiber carbohydrate concentration on forage fiber digestion in vitro

We quantified the effect of dietary nonfiber carbohydrate (NFC) concentration (30, 35, 40, or 45% of DM) on in vitro digestion kinetics of neutral detergent fiber (NDF) from alfalfa and corn silages at pH 5.8 or 6.8. The objective was to simulate the effect of diets differing in effective fiber content on the optimal NFC-to-NDF ratio that resulted in maximal fiber digestion. Ash-free NDF was determined at 0, 3, 6, 9, 12, 24, 30, 36, 48, 72, and 96h of fermentation. Kinetic parameters were estimated using logarithmic transformation and linear regression. The optimal NFC-to-NDF ratio for maximal NDF digestion differed between the two forages. For alfalfa fermented at pH 6.8, apparent extent of ruminal NDF digestion was greatest between 30 and 40% NFC, but at pH 5.8 NDF digestion was greatest at 35% NFC. For corn silage fermented at either pH 6.8 or 5.8, apparent extent of NDF digestion was greatest at 30% NFC. An NFC-to-NDF ratio of 0.70–1.20 maximized NDF digestion for alfalfa only when fermentation pH was maintained at 6.8. These in vitro results demonstrate that the optimal dietary NFC content for maximum NDF digestion in the rumen for a particular forage will be a function of fermentation pH that reflects the physically effective NDF content of the diet.

Effects of Nonfiber Carbohydrate and Niacin on Periparturient Metabolic Status and Lactation of Dairy Cows

Fifty Holstein cows and 25 Holstein heifers were used in a randomized complete block design. Treatments were a standard nonfiber carbohydrate diet beginning at 19 d prepartum, a high nonfiber carbohydrate diet beginning at 19 d prepartum, a standard nonfiber carbohydrate diet plus niacin (12 g/d) beginning at 19 d prepartum, a high nonfiber carbohydrate diet plus niacin beginning at 19 d prepartum, and a standard nonfiber carbohydrate diet beginning at 19 d prepartum plus niacin beginning at 14 d postpartum. Treatments were applied through 40 wk postpartum. Niacin did not significantly affect production parameters or blood and liver metabolites. Prepartum intakes of dry matter and energy and energy balance were greater for cows and heifers fed the high nonfiber carbohydrate diets. Plasma glucose concentrations tended to be significantly higher, and nonesterified fatty acids and β-hydroxybutyrate concentrations were significantly lower, when animals were fed diets that were high in nonfiber carbohydrates. Diets containing high nonfiber carbohydrates increased concentrations of liver glycogen and tended to reduce concentrations of liver triglyceride. Milk production tended to be higher, milk fat percentage tended to be lower, and milk protein percentage and production were significantly greater when diets that were high in nonfiber carbohydrates were fed. An increase in dietary nonfiber carbohydrates improved the metabolic parameters during the transition period and improved lactation performance.

Impact of Nonfiber Carbohydrate on Intake, Digestion, and Milk Production by Dairy Cows

Four concentrations of dietary nonfiber carbohydrate (42,36, 30, and 24%) were evaluated using eight multiparous Holstein cows (662kg of BW; 63 DIM) in replicated 4 × 4 Latin squares with 28-d periods. Shelled corn and soybean meal were partially replaced with wheat middlings, dried brewers grains, and soy hulls to formulate 36, 30, and 24% nonfiber carbohydrate diets. Decreasing dietary nonfiber carbohydrate decreased DMI, did not affect actual or fat-corrected milk production, increased milk fat percentage, and decreased milk protein percentage and production. Apparent total tract DM and OM digestibilities were highest for 36% and lowest for 24% nonfiber carbohydrate diets. Digestibility of NDF was lowest for the 42% nonfiber carbohydrate diet. Ruminal pH and acetate:propionate increased, and total VFA concentrations decreased, as dietary nonfiber carbohydrate decreased. Ruminal degradation of alfalfa hay DM and NDF were higher for low nonfiber carbohydrate diets. Significant depression of DMI (.9 to 1.8 kg/d) coincided with dietary nonfiber carbohydrate concentration at or below 30%. Results indicate that diets for cows producing 40 kg/ d should contain more than 30% nonfiber carbohydrate and suggest little benefit of 42 over 36% nonfiber carbohydrate diets.

Effect of nonfiber carbohydrate level and Aspergillus oryzae fermentation extract on intake, digestion, and milk production in lactating dairy cows.

Eight multiparous, ruminally cannulated Holstein cows averaging 40 d in milk and 575 kg BW at the start of trial were in a replicated 4 x 4 Latin square arrangement (28-d periods) to determine the effects of dietary nonfiber carbohydrate (NFC) level and Aspergillus oryzae fermentation extract (AO) on intake, milk production, and nutrient digestibility. Treatments were 42 or 35% NFC and 0 or 3 g of AO per day arranged as a 2 x 2 factorial. Diets formulated to contain 21% NDF from alfalfa silage (48.4% of ration DM) and 18.5% CP were fed as total mixed rations twice daily. Alteration of dietary NFC level was by partial replacement of shelled corn and soybean meal with wheat middlings and brewers dried grains. Intake of NDF was higher (1.49 vs 1.22% of BW) for 35 than for 42% NFC diets, but DMI was lower (24.1 vs 24.9 kg/d). Milkfat percentage, ruminal pH, ammonia, acetate (moles/100 moles), and total tract digestibility of fiber were higher for 35% NFC diets; however, ruminal disappearance of DM, CP, and NDF from Dacron bags containing alfalfa hay was not affected (P > .10) by NFC level. Supplementation with AO did not affect (P > .10) DMI, milk yield, or nutrient digestion. Partial replacement of corn with high-fiber byproducts to lower dietary NFC level and correspondingly increase NDF level increased NDF intake but effected only a small change in DMI. Reducing dietary NFC level improved ruminal fermentation and milkfat percentage without significantly affecting milk yield.

Carbohydrate and Aspergillus oryzae Effects on Intake, Digestion, and Milk Production by Dairy Cows

Six multiparous, ruminally cannulated Holstein cows (46 DIM, 584kg of BW) and 6 primiparous Holstein cows (35 DIM, 506kg of BW) were used in two 6 × 6 Latin squares with 21-d periods to examine the effects of level of nonfiber carbohydrate, source of fibrous carbohydrate, and Aspergillus oryzae fermentation extract on intake, digestion, and milk production. Treatments were 42 and 36% nonfiber carbohydrate; shelled corn and soybean meal were replaced partially by beet pulp and dried brewers grains or soy hulls and dried brewers grains in 36% nonfiber carbohydrate diets. These three diets then were supplemented with 0 or 3 g/d of A. oryzae. Milk production and composition and DMI were not significantly affected by level or source of carbohydrate, although intake of NDF was significantly higher for 36% nonfiber carbohydrate diets. Total tract apparent digestibilities of ADF and NDF were higher for 36% nonfiber carbohydrate diets. Supplementation with A. oryzae did not significantly affect DMI, milk production, or total tract apparent digestibilities; however, milk fat content was decreased. Partial replacement of corn with fibrous carbohydrate sources, beet pulp and soy hulls, did not adversely affect intake or milk production in early lactation cows fed alfalfa silage-based diets.