Citrus pulp for cattle

Orange molasses as a new energy ingredient for feedlot lambs in Brazil

The objectives of this experiment were to evaluate the effects of increasing levels of orange molasses in replacement of flint corn grain in high-concentrate diets on dry matter intake (DMI), average daily gain (ADG), and feed efficiency (FE) of feedlot lambs. Thirty male lambs without defined racial pattern (30.3 ± 5.3 kg of initial BW; mean ± SD) were used in a randomized complete block design with 10 blocks and 3 treatments. The treatments were defined by partial replacement of flint corn by orange molasses in the diet with 90% of concentrate and 10% of Cynodon spp. hay, as follows: 0OM-control diet without orange molasses; 20OM-20% of orange molasses replacing flint corn; and 40OM-40% of orange molasses replacing flint corn (DM basis). The experiment lasted 72 days divided into 3 subperiods, with 1 subperiod of 16 days and 2 subperiods of 28 days. Animals were weighed after a 16-h fast on days 1, 16, 44, and 72 of the experimental periods to determine the ADG and FE. The DMI, ADG, and FE showed an interaction between treatments and experimental periods. The DMI in the first period decreased linearly (P < 0.01); in the third period, there was no effect of treatments (P > 0.05) on DMI. The ADG decreased linearly (P < 0.01) in the first period as the orange molasses increased. Otherwise, in the third period, ADG increased linearly (P = 0.05) as flint corn was replacement by orange molasses. The FE showed an interaction between treatment and period (P = 0.09). The first period had a decreased linear effect; in the third period, there was a trend (P = 0.07) of increased linear effect. There was no difference between the diets regarding the final BW of the lambs. In conclusion, the orange molasses can replace up to 40% of flint corn in diets for feedlot lambs without affecting final BW. However, it is important to consider the adaptation time proved to be very important for better use of orange molasses as a source of energy in diets for lambs.

A comparative analysis of the proximate and mineral composition of whole Citrus limon and Citrus clementina as a prospective alternative feed resource for livestock farming in South Africa

Citrus is a well-known vital fruit grown in South Africa. The presence of important bio-nutrients and metabolites within the different Citrus fruits indicates their significant nutritional qualities. This study is aimed to evaluate the proximate and mineral components of whole Citrus limon and Citrus clementina while considering them as prospective feed material for livestock farmers in South Africa. The nutritional evaluation was done using standard analytical procedures of the Association of Official Analytical Chemists (AOAC). The mineral constituents of the whole citrus samples were analyzed using inductively coupled plasma optical emission spectroscopy (ICP-OES). From the result, the nutritional analysis showed that the whole C. limon contains significantly higher moisture content (14.13 ± 0.57) and fiber content (24.48 ± 0.61) than C. clementina (11.41 ± 1.24 and 20.66 ± 1.07). Meanwhile, C. clementina had a significantly higher protein value (8.65 ± 0.04) compared to C. limon (5.53 ± 0.10). Furthermore, the whole C. clementina had significantly higher K, Na, P, Zn, and Na+/K+ (1513.33 ± 16.99, 53.33 ± 4.71, 160.00 ± 0.00, 4.80 ± 0.00, and 1.09 ± 0.01) than the whole C. limon (1356.67 ± 20.55, 30.00 ± 0.00, 133.33±4.71, 1.67 ± 0.09, and 0.80 ± 0.02), respectively. While C. limon had significantly higher Ca, Mg, Mn, and Fe (593.33 ± 4.71, 160.00 ± 0.00, 1.00 ± 0.00, and 4.53 ± 0.25) compared to C. clementina (483.33 ± 4.71, 136.67 ± 4.71, 0.80 ± 1.11, and 3.43 ± 0.05). The study revealed variations in some nutritional and mineral components of whole C. limon and C. clementina; however, both citrus fruits have the potential to be explored for more significant livestock nutritional use in South Africa.

Non-fiber Carbohydrates in Forages and Their Influence on Beef Production Systems

Forages can provide a complete diet for ruminant animals, increasing the sustainability of beef production systems worldwide while reducing competition with humans for agricultural land or grain crops. Much of the emphasis on the nutritional characteristics of forages has been on the fiber, sugars, starch, and protein they supply to the rumen, despite the fact that other less-explored constituents, i.e., neutral detergent soluble fiber (NDSF) and other non-structural or non-fiber carbohydrates (NFC) also play a key role in the nutrition of ruminants. This paper explores the less investigated potential of temperate legumes to accumulate levels of NFC comparable to corn silage or beet pulp in cool, dry environments under irrigation, and its implications for forage-based beef production systems. We conclude that genetic or managerial interventions (i.e., breeding programs, defoliation frequency) or ecological conditions (i.e., climate, elevation) that increase concentrations of NFC in legumes can enhance beef production, meat quality, and the efficiency of nitrogen utilization by ruminants while reducing environmental impacts.

Orange Bagasse Pellets as a Carbon Source for Biobutanol Production

Due to the environmental concerns, the conversion of lignocellulosic waste can be the key to produce bioproducts and biofuels such as butanol. This study aimed to present and evaluate orange bagasse pellets (OBP) as a carbon source to produce butan-1-ol production via ABE fermentation using Clostridium beijerinckii. These bagasse pellets were characterized, holocellulose (18.99%), alfacellulose (5.37%), hemicellulose (13.62%), lignin (6.16%), pectin (7.21%), protein (3.14%), and was tested under three different pretreatments, which were the following: (a) ultrasound, (b) autohydrolysis, and (c) acid-diluted hydrolysis followed by enzymatic hydrolysis to verify an amount of fermentable total reducing sugars. ANOVA was used and pretreatments followed by enzymatic hydrolysis do not enhance a significant amount of available sugars compared to raw bagasse. The ABE fermentation was carried out in batch reactors at 37 °C under agitation of 160 rpm and anaerobic conditions, using OBP without treatment followed by enzymatic hydrolysis. Using a non-mutant microorganism, the fermentation achieved butyric acid yields of 3762.68 mg L^-1 for control and 2488.82 mg L^-1 for OBP and the butanol production was 63.86 mg L^-1 and 196.80 mg L^-1 for OBP and the control (glucose) assay, respectively. The results of this solvent's production have shown that OBP has the potential for ABE fermentation and a promising feedstock.

Effects of Replacing Extruded Maize by Dried Citrus Pulp in a Mixed Diet on Ruminal Fermentation, Methane Production, and Microbial Populations in Rusitec Fermenters

Citrus pulp is a highly abundant by-product of the citrus industry. The aim of this study was to assess the effects of replacing extruded maize (EM; 20% of total diet) by dried citrus pulp (DCP; 20%) in a mixed diet on rumen fermentation and microbial populations in Rusitec fermenters. The two diets contained 50% alfalfa hay and 50% concentrate, and the same protein level. Four Rusitec fermenters were used in a cross-over design with two 13-d incubation runs. After 7-d of diet adaptation, diet disappearance, fermentation parameters, microbial growth, and microbial populations were assessed. Fermenters receiving the DCP showed greater pH values and fiber disappearance (p < 0.001) and lower methane production (p = 0.03) than those fed EM. Replacing EM by DCP caused an increase in the proportions of propionate and butyrate (p < 0.001) and a decrease in acetate (p = 0.04). Microbial growth, bacterial diversity, and the quantity of bacteria and protozoa DNA were not affected by the diet, but the relative abundances of fungi and archaea were greater (p < 0.03) in solid and liquid phases of DCP fermenters, respectively. Results indicate that DCP can substitute EM, promoting a more efficient ruminal fermentation.

Replacing corn with ground or pelleted citrus pulp in diets of Nellore heifers

SUMMARY Citrus pulp can replace corn in feedlot diets in order to decrease metabolic problems by reducing formation of lactate ruminal. However, while eating, animals can easily select against pelleted citrus pulp due to the greater particle size of the pellet. Therefore, grinding citrus pulp pellet can be an alternative to decrease particle selectivity. This study was realized to evaluate the replacement of ground corn by pelleted citrus pulp and ground citrus pulp on animal performance, sorting index, and feeding behavior of Nellore heifers. Thirty-six Nellore heifers were randomly assigned to three treatments: control diet based on ground corn (GC), partial replacement of GC by ground citrus pulp (GCP), and partial replacement of GC by pelleted citrus pulp (PCP). . Heifers fed with the GC diet had higher final body weight (BW), average daily gain (ADG), and dry matter intake (DMI) compared with heifers fed with citrus pulp (P < 0.05). Ground citrus pulp increased DMI and fiber intake compared with the PCP group (P < 0.05). Heifers fed with PCP and GCP sorted for diet particles from 8 to 19 mm and selected particles with less than 1.18 mm (P < 0.05). Thus, the ground citrus pulp is better than pelleted citrus pulp due to higher feed intake and ADG, in consequence of lower selection index.

Protein quality chicken meat after feeding with active substances of citrus fruits and diclazuril and salinomycin sodium

The purpose of this study was an experimental investigation of the influence of active substances obtained mainly from citrus fruits in the experimental feed mixtures, and diclazuril and salinomycin sodium in the control feed mixtures of broiler chickens on productive efficiency and protein quality of the breast and thigh muscles. In vivo experiment was carried out with hybrid chickens Cobb 500. Basic feed mixtures were equal a soy cereal type for experimental and control group. Indicators of productive efficiency were measured and calculated, and protein, lysine and methionine contents in the breast and thigh muscles were measured by the method of FT IR, Nicolet 6700. Active substances obtained mainly from citrus fruits confirmed a statistically significant (p ˂0.05) positive effect on the body weight gain; tended to slightly increase feed intake per bird, protein, energy, lysine and methionine intake per bird; slightly decrease feed intake per 1 kg of body weight gain, protein, energy, lysine and methionine intake per 1 kg of body weight gain; slightly increase protein efficiency ratio and energy efficiency ratio. Additive substances used in the feed mixtures did not have a statistically significant effect on protein, lysine and methionine contents in the breast and thigh muscles but displayed a strong positive, statistically significant relation between lysine and methionine in them.

Flint corn grain processing and citrus pulp level in finishing diets for feedlot cattle

Four trials were conducted to evaluate the effects of flint corn processing and the replacement of corn with citrus pulp (CiP) in diets for Nellore feedlot cattle. In a 103-d finishing trial, 216 Nellore bulls (350 ± 24 kg initial BW) were used in a randomized complete block design with a 2 × 4 factorial arrangement of treatments. Factors included 2 processing methods, either ground corn (GC) or steam-flaked corn (FC), with CiP replacing each corn type at 4 levels (0, 25, 50, and 75% of DM). All diets contained 12% sugarcane bagasse and 88% concentrate (DM basis). Treatments were also evaluated in metabolism trials, in which 10 ruminally cannulated Nellore steers (389 ± 37 kg) were assigned to 2 independent but simultaneous 5 × 5 Latin squares, each using 1 method of corn processing (GC and FC). Interactions ( < 0.05) between corn processing and CiP inclusion level were observed for final BW, DMI, ADG, G:F, and HCW. With FC-based diets, added CiP linearly decreased final BW ( = 0.04), whereas with GC-based diets, added CiP quadratically increased final BW ( = 0.002). With FC-based diets, the inclusion of CiP linearly increased DMI ( = 0.03) and linearly decreased ADG ( = 0.03) and G:F ( = 0.001). Increasing CiP in GC-based diets quadratically increased DMI ( = 0.001), ADG ( = 0.005), and HCW ( = 0.003). In FC-based diets, CiP inclusion had no effect on HCW ( = 0.21). Dressing percent, LM area, and 12th-rib fat were not affected by diet ( ≥ 0.05). For steers fed GC diets, CiP inclusion in the diet quadratically decreased the molar proportion of isovalerate ( = 0.001) but linearly increased ruminal butyrate ( = 0.006). No differences ( ≥ 0.16) were observed for total VFA concentrations, acetate:propionate ratio, and ruminal NH-N as CiP replaced GC. For steers fed FC diets, the molar proportion of acetate linearly increased ( = 0.002) whereas the proportion of propionate was linearly decreased ( < 0.001), resulting in a linear increase ( = 0.001) in the acetate:propionate ratio. Replacing corn with CiP linearly reduced NEm ( = 0.001) and NEg ( < 0.001) of FC-based diets but did not affect ( = 0.15) NE values of CG-based diets. Steam flaking flint corn improved cattle performance in this trial more than has been reported for dent corn in the published literature.

Investigation on the effect of different levels of dried sweet orange (Citrus sinensis) pulp on performance, carcass characteristics and physiological and biochemical parameters in broiler chicken

Utilization of agricultural by-products in animal nutrition is a matter of great concern. Dried sweet orange (Citrus sinensis) pulp (DCSP) is a potential source of valuable nutrients and natural antioxidants for poultry feed. In the experiment, a feeding trial was conducted in order to investigate the effect of different levels of dried orange residues in diet on broiler growth performance, carcass characteristics, blood metabolites, humoral immunity, and cecum microbial population. A total of 200 one day experimental broiler chicks were distributed into a completely randomized design (CRD) which included 5 dietary treatments with 4 replicates per each treatment and 10 birds fed in each replicate. The experimental treatments consist of a control group (without additive), 0.5%, 1.0%, 1.5%, and 2% of DCSP (residue) in diet. Weight gain, feed intake and feed conversion ratio (FCR) were measured. Blood parameters and carcass traits were measured in the postnatal 35th day. The highest level of dried orange residues in treatment 5 (T5) had significantly increased the feed intake and body weight of broilers in groups and overall during the rearing period (P > 0.05). Different levels of dried orange residues had no significant effect on chicken FCR. Using of dried orange residues significantly decreased the liver and abdominal fat of broilers (P < 0.05). T5 has also significantly lower level of triglyceride than the control (T1) and treatment 2 (T2) (P < 0.05). In conclusion, the use of dried orange residues improved some performance (e.g. feed intake and body weight gain), decreased liver and abdominal fat and also serum triglyceride level in broiler chicken.

Citrus pulp as a dietary source of antioxidants for lactating holstein cows fed highly polyunsaturated Fatty Acid diets

The effects of feeding pelleted citrus pulp (PCP) as a natural antioxidant source on the performance and milk quality of dairy cows fed highly polyunsaturated fatty acid (FA) diets were evaluated. Four lactating Holstein cows were assigned to a 4×4 Latin-square. Treatments, on a dry matter (DM) basis, were i) control diet; ii) 3% soybean oil; iii) 3% soybean oil and 9% PCP and; iv) 3% soybean oil and 18% PCP. When cows fed on citrus pulp, the DM intake tended to decrease. The total tract apparent digestibility of DM and ether extract decreased when cows fed on the control diet compared to other diets. Cows fed PCP had higher polyphenols and flavonoids content and higher total ferric reducing antioxidant power (FRAP) in milk compared to those fed no pelleted citrus pulp. Cows fed 18% PCP showed higher monounsaturated FA and lower saturated FA in milk fat compared with cows fed the other diets. The lowest n-6 FA proportion was in milk fat from cows fed control. The present study suggests that pelleted citrus pulp added to 9% to 18% DM increases total polyphenols and flavonoids concentration, and the FRAP in milk.

Determination of physical characteristics, chemical composition and digestion coefficients of treated lemon pulp with Saccharomyces cerevisiae in goat diet

The aim of this study was to evaluate the effects of processing of lemon pulp with Saccharomyces cerevisiae on physical properties, chemical composition, digestion coefficients and blood parameters. Eight adult male Raeini goats were used in a 28-day period. The experimental design was a completely randomised design with two treatments and four replicates. The first 21 days were for adaptation, and the last 7 days were for collecting samples. The animals were housed in individual metabolic cages equipped with a urine-faeces separator and were fed with diet containing alfalfa hay (60%) and lemon pulp (40%) at the maintenance level. Collected data were subjected to analysis of completely randomised design. With diet containing processed lemon pulp, functional specific gravity, bulk density, soluble dry matter, percentage of crude protein, neutral detergent fibre (NDF), acid detergent fibre and crude ash were significantly increased and water-holding capacity, insoluble dry matter, insoluble ash percentage of dry matter, organic matter, crude fat, non-fibrous carbohydrates and nitrogen-free extract were significantly decreased (p < 0.05). Digestion coefficient of organic matter in dry matter and metabolisable energy were also decreased in treated lemon pulp (p < 0.05). Compared with untreated lemon pulp, digestibility of crude protein and NDF was higher (p < 0.05), but digestibility of crude fat was lower (p < 0.05). In general, processing of lemon pulp with S. cerevisiae improved the physical characteristics and increased the percentage of crude protein and the digestion coefficients of protein and NDF.

Pectin-rich biomass as feedstock for fuel ethanol production

The USA has proposed that 30 % of liquid transportation fuel be produced from renewable resources by 2030 (Perlack and Stokes 2011). It will be impossible to reach this goal using corn kernel-based ethanol alone. Pectin-rich biomass, an under-utilized waste product of the sugar and juice industry, can augment US ethanol supplies by capitalizing on this already established feedstock. Currently, pectin-rich biomass is sold (at low value) as animal feed. This review focuses on the three most studied types of pectin-rich biomass: sugar beet pulp, citrus waste and apple pomace. Fermentations of these materials have been conducted with a variety of ethanologens, including yeasts and bacteria. Escherichia coli can ferment a wide range of sugars including galacturonic acid, the primary component of pectin. However, the mixed acid metabolism of E. coli can produce unwanted side products. Saccharomyces cerevisiae cannot naturally ferment galacturonic acid nor pentose sugars but has a homoethanol pathway. Erwinia chrysanthemi is capable of degrading many of the cell wall components of pectin-rich materials, including pectin. Klebsiella oxytoca can metabolize a diverse array of sugars including cellobiose, one degradation product of cellulose. However, both E. chrysanthemi and K. oxytoca produce side products during fermentation, similar to E. coli. Using pectin-rich residues from industrial processes is beneficial because the material is already collected and partially pretreated to facilitate enzymatic deconstruction of the plant cell walls. Using biomass already produced for other purposes is an attractive practice because fewer greenhouse gases (GHG) will be anticipated from land-use changes.

Concentrations of progesterone and insulin in serum of nonlactating dairy cows in response to carbohydrate source and processing

Two experiments were conducted to investigate the effects of carbohydrate source and processing on serum progesterone (P4) and insulin concentrations of nonlactating dairy cows. In experiment 1, 12 ovariectomized grazing Gir x Holstein cows were stratified by body weight and body condition score, and randomly assigned to receive a supplement containing either finely ground corn or citrus pulp in a Latin square crossover design. Diets were fed individually, twice daily at a rate of 10.9 kg of dry matter per cow. Cows received a controlled intravaginal P4-releasing insert before the beginning of the study, and inserts were replaced every 7 d. During the first experimental period, cows were adapted to treatments from d 0 to 13 and blood was collected on d 14, whereas during the second experimental period cows were adapted to treatments from d 0 to 6 and blood samples were collected on d 7. In both periods, blood samples were collected immediately before and at 1, 2, 3, 4, 5, and 6 h after the first supplement feeding of the collection day. In experiment 2, the cows utilized in experiment 1 were randomly assigned to receive a supplement based on finely ground corn, coarsely ground corn, or high-moisture corn in a Latin square crossover design. Cows were fed and received the controlled intravaginal P4-releasing insert as in experiment 1. Within each of the 3 experimental periods, cows were adapted to diets from d 0 to 6, and blood samples were collected on d 7 as in experiment 1. Time effects were detected in experiments 1 and 2 because insulin concentrations increased by 1 h (4.6 +/- 0.90 vs. 7.4 +/- 0.91 microIU/mL for 0 and 1 h, respectively) and P4 concentrations decreased by 3 h (1.8 +/- 0.12 vs. 1.2 +/- 0.11 ng/mL for 0 and 3 h, respectively) after supplements were offered. In experiment 2, insulin concentrations were greater in cows fed high-moisture corn compared with those fed coarsely or finely ground corn (8.8 +/- 1.05, 5.7 +/- 1.05, and 6.1 +/- 1.05 microIU/mL, respectively). Data combined from both experiments indicated that cows with median insulin >or=4.5 microIU/mL before supplement feeding had greater P4 concentrations at 1 h, but lesser P4 concentrations at 5 h compared with cows with insulin <4.5 microIU/mL. Carbohydrate processing, but not carbohydrate source, affected serum insulin of nonlactating dairy cows.

Optimizing nitrogen utilization in growing steers fed forage diets supplemented with dried citrus pulp

Our objectives were to compare the effects of sources of supplemental N on ruminal fermentation of dried citrus pulp (DCP) and performance of growing steers fed DCP and bahiagrass (Paspalum notatum) hay. In Exp. 1, fermentation of DCP alone was compared with that of isonitrogenous mixtures of DCP and solvent soybean meal (SBM), expeller soybean meal (SoyPLUS; SP), or urea (UR). Ground (1 mm) substrates were incubated in buffered rumen fluid for 24 h, and IVDMD and fermentation gas production kinetics and products were measured. Nitrogen supplementation increased (P < 0.10) ruminally fermentable fractions, IVDMD, pH, and concentrations of NH3 and total VFA, but reduced the rate of gas production (P < 0.10) and the lag phase (P < 0.01). Supplementation with UR vs. the soy-based supplements increased ruminally fermentable fractions (P < 0.05) and concentrations of total VFA (P < 0.10) and NH3 (P < 0.01), but these measures were similar (P > 0.10) between SBM and SP. In Exp. 2, 4 steers (254 kg) were fed bahiagrass hay plus DCP, or hay plus DCP supplemented with CP predominantly from UR, SBM, or SP in a 4 x 4 Latin square design, with four 21-d periods, each with 7 d for DMI and fecal output measurement. Nitrogen-supplemented diets were formulated to be isonitrogenous (11.9% CP), and all diets were formulated to be isocaloric (66% TDN). Intake and digestibility of DM, N, and ADF were improved (P < 0.05) by N supplementation. Compared with UR, the soy-based supplements led to greater (P < 0.05) DM and N intakes and apparent N and ADF digestibilities. Plasma glucose and urea concentrations increased (P < 0.10) with N supplementation and were greater (P < 0.01) for the soy-based supplements than for UR. Intake, digestibility, and plasma metabolite concentrations were similar (P > 0.1) for SBM and SP. In Exp. 3, 24 steers (261 kg) were individually fed bahiagrass hay plus DCP (control), or hay plus DCP supplemented with CP predominantly from UR or SBM. Over 56 d, DMI and ADG were greatest (P < 0.05) in steers fed SBM. Nitrogen supplementation increased (P < 0.05) DMI, ADG, and G:F. However, SBM supplementation produced greater (P < 0.05) DMI and ADG and similar (P > 0.05) G:F compared with UR supplementation. We conclude that supplemental N is important to optimize ruminal function and performance of growing steers fed forage diets supplemented with DCP. Diets with supplemental N mainly from SBM improved diet digestibility and animal performance beyond that achieved by UR.

Effects of supplement type on performance, reproductive, and physiological responses of Brahman-crossbred females

Two experiments were conducted to compare the performance and physiological responses of forage-fed beef females supplemented with either a molasses-based (ML) or a citrus pulp-based (CT) supplement. In Exp. 1, BW gain, reproductive performance, and concentrations of blood urea N (BUN), plasma glucose, insulin, IGF-I, and progesterone (P4) were assessed in 60 Brahman x Angus heifers supplemented 3 times weekly with either ML or CT. Supplement intakes were formulated to be isocaloric and isonitrogenous. Reproductive performance was not affected by treatments, but mean BW gain was greater (P < 0.01) for heifers fed CT than for those fed ML (0.40 vs. 0.30 kg/d). Mean plasma concentrations of glucose, insulin, and IGF-I were greater (P < 0.05) for heifers fed CT, whereas BUN was greater (P < 0.05) for heifers fed ML. Mean plasma P4 concentration did not differ between treatments, but both groups had lower plasma P4 concentrations during days that supplements were offered (P < 0.01). In Exp. 2, forage DMI and concentrations of BUN, plasma glucose, insulin, IGF-I, and P4 were assessed in 24 Brahman x British mature cows supplemented with the same treatments described in Exp. 1. Overall forage DMI did not differ between treatments, but a day effect and a treatment x day interaction were detected (P < 0.05). Both groups consumed less forage during the days on which the supplements were offered (P < 0.01), and forage DMI for cows fed CT was less (P < 0.05) than for cows fed ML during those days. No differences were detected in any blood or plasma measurement. In addition, no differences in concentrations of P4 were detected between CT- and ML-fed cows. We concluded that CT-supplemented heifers had greater BW gain compared with ML-supplemented heifers, but no differences in reproductive performance were observed. We also observed that CT-supplemented cows had a greater variability in forage DMI compared with ML-supplemented cows.

Effect of a monensin controlled-release capsule on rumen and blood metabolites in Florida Holstein transition cows

The objective of this study was to determine the effect of a monensin controlled-release capsule administered intraruminally at dry-off on rumen volatile fatty acids, NH3, lactate, pH, and energy blood metabolites in transition dairy cows fed Florida typical diets. In March 2003, 24 cows (10 primiparous and 14 multiparous) dried-off 50 to 70 d before expected parturition were randomly assigned to a treatment (n=12, oral capsule of monensin) or a control group (n=12, no capsule). Both groups received the same diet and were exposed to the same environment and management conditions. At assignment, at 21 d before expected parturition, at calving, and at 7, 14, and 21 d postpartum, blood samples were taken and body condition scores were determined. At 10 d postpartum, rumen and blood samples were obtained in the morning before the first feeding and at 2, 4, and 6 h after feeding. Serum nonesterified fatty acids (NEFA), beta-hydroxybutyrate (BHBA), and glucose were measured. Rumen samples were analyzed for concentrations of acetic, propionic, butyric, L- and D-lactic acids, and NH3. Data for rumen and blood metabolites were analyzed by ANOVA, mixed models for repeated measures. Volatile fatty acids were not different between groups. Multiparous treated cows had a significant reduction in rumen NH3 at 6 h after feeding. Treatment with monensin significantly increased body condition score at calving in multiparous cows. During the postpartum period, NEFA and BHBA were noticeably lower in treated than in control primiparous cows. This difference was not observed in multiparous cows.