Effect of rumen degradable protein and sulfur supplementation on in vitro digestibility and ruminal fermentation

The availability of nitrogen and sulfur in the rumen should be synchronized to generate microbial protein synthesis. This study aimed to evaluate rumen degradable protein and sulfur supplementation on in vitro digestibility and ruminal fermentation. The experimental design was a 4 x 3 factorial randomized block design. Factor 1 was RDP levels (%CP) (R1= 60%; R2= 55%; R3= 50%; R4= 45%), and factor 2 was sulfur supplementation (S1= 0%; S2= 0.1%; S3= 0.2%). Data were analyzed with ANOVA followed by the Duncan test. The result showed that sulfur supplementation improved DMD and OMD without changes in rumen pH. NH3 concentration was influenced by RDP levels. Treatment R1 had the highest NH3 concentration (7.03 mM). There was an interaction of two factors on total VFA concentration. The combination of R1 and S2 resulted in the highest total VFA concentration than others. The total bacteria population increased with increasing RDP levels. Protozoa population was affected by RDP levels and sulfur supplementation. This study concluded that a combination of 60% RDP and 0.2% sulfur supplementation resulted in the best ration to improve ruminal fermentation and digestibility.

Supplementing a blend of magnesium oxide to feedlot cattle: effects on ruminal, physiological, and productive responses

This experiment evaluated ruminal, physiological, and productive responses of feedlot cattle consuming a corn-based finishing diet that included different levels of a magnesium oxide (MG) blend. Yearling cattle (58 heifers and 62 steers) were ranked by sex and initial body weight (BW; 407 ± 3.1 kg), and allocated to 4 groups of 30 animals each. Groups were housed in 1 of 4 drylot pens (30 × 12 m) equipped with GrowSafe automated feeding systems (Model 6000E, 4 bunks/pen) during the experiment (d -14 to 117). On d 0, groups were randomly assigned to receive a total-mixed ration without (CON; n = 30) or with the inclusion (as-fed basis) of MG at 0.25% (MG25; n = 30), 0.50% (MG50; n = 30), or 0.75% (MG75; n = 30) until slaughter on d 118. Individual feed intake was recorded daily, and BW were recorded every 14 d and prior to slaughter (d 117). Blood samples were collected on d 0, 28, 56, 84 and 112, and hair samples were collected on d 0, 56 and 112 from the tail-switch. On d 42, 8 rumen-cannulated steers (BW = 492 ± 8.0 kg) were housed with yearling cattle (1 pair/pen). Pairs rotated among groups every 14 d, resulting in a replicated 4 × 4 Latin square design (n = 8/treatment; d 42 to 98). Rumen pH was measured on d 7 and 14 of each period (0800, 1200, 1600 and 2000 h). Orthogonal contrasts were used to determine if inclusion of MG (0, 0.25, 0.50, or 0.75% of the diet) yielded linear or quadratic effects, and to explore overall effect of MG supplementation (CON vs. MG25 + MG50 + MG75). No treatment differences were noted (P ≥ 0.31) for BW gain, feed intake, or feed efficiency. Cattle supplemented with MG tended have less carcass marbling (P = 0.07) compared with CON. Inclusion of MG linearly increased (P < 0.01) mean plasma concentrations of magnesium, and tended to linearly decrease (P = 0.09) mean plasma concentrations of haptoglobin. Cattle supplemented with MG had greater (P < 0.01) mean plasma concentrations of cortisol compared with CON. Hair cortisol concentration did not differ between treatments on d 56 (P ≥ 0.25), and linearly decreased (P < 0.01) with MG inclusion on d 112 (treatment × day; P = 0.02). Inclusion of MG linearly increased (P = 0.03) mean rumen pH, but these outcomes were mostly noted during the last two sampling of the day (treatment × hour; P = 0.02). Collectively, supplemental MG was effective in controlling rumen pH in cattle receiving a corn-based finishing diet, but without improvements in feedlot performance and carcass merit.

Effect of the Length of Oat Hay on Growth Performance, Health Status, Behavior Parameters and Rumen Fermentation of Holstein Female Calves

The aim of this study was to evaluate the effect of the length of oat hay on the performance, health, behavior, and rumen fermentation of dairy calves. For this purpose, two hundred and ten healthy two-day-old Holstein dairy calves were randomly allocated into three groups: basic diet (calf starter) without hay (CON), or a basic diet with oat hay at either long (OL: 10–12 cm) or short (OS: 3–5 cm) length cut. The basic diet was fed from day 4, while the hay was offered from day 14. All calves were weaned at day 56 and remained in their individual hutches till the end of the trial (day 70). Calf starter intake and fecal scores were recorded daily. Bodyweight, body size, and rumen fluid samples were collected biweekly before weaning and weekly after weaning. Overall, providing oat hay (OS and OL) in the diet increased the body weight, starter intake, and average daily gain compared to the CON group. Similarly, feeding oat hay improved rumen fermentation. More specifically, hay enhanced the rumen pH and changed the rumen fermentation type. Hay fed calves spent more time on rumination but less time performing abnormal behaviors compared to control. As it can be concluded, feeding oat hay to calves enhances the growth performance, rumen fermentation, and normal calf behaviors, implying improved animal welfare irrespective of the hay length.

Evaluating the effects of fibrolytic enzymes on rumen fermentation, omasal nutrient flow, and production performance in dairy cows during early lactation

This study was performed to evaluate the effects of pre-treating a barley-silage-based diet with an exogenous fibrolytic enzyme derived from Trichoderma reesei (FETR, a mixture of xylanase and cellulase) on lactation performance, omasal nutrient flow and digestibility, rumen fermentation characteristics, and rumen pH profile in Holstein dairy cows during early lactation. The dairy trial was conducted using nine Holstein dairy cows (averaging 46 ± 24 days in milk and 697 ± 69 kg body weight, six cows were fitted with a rumen cannula, and three were non-cannulated). Two groups of cows were randomly assigned to each of the dietary treatments in a crossover design: control (without FETR supplementation) and supplemented [with 0.75 mL of FETR·kg−1 dry matter (DM) of the diet based on our previous study]. The application of FETR tended to decrease the DM intake compared with control. There were no effects of FETR (P > 0. 10) on omasal nutrient flow and digestibility, rumen fermentation characteristics, and rumen pH profile. In conclusion, this study lacks evidence that the fibrolytic enzyme (at a level of 0.75 mL of FETR·kg−1 DM) can affect nutrient digestibility, ruminal fermentation, and the performance of early-lactation cows. Further study with larger animal trials are needed.

Changes in the Fermentation and Bacterial Community by Artificial Saliva pH in RUSITEC System

The purpose of the study was to assess the artificial saliva (AS) pH on ruminal fermentation and rumen bacteria community in the rumen simulation technique (RUSITEC) system. The experiment was performed in two treatments (low AS pH vs. high AS pH) with four replicates. The low AS pH was sustained by altering the composition of the AS (NaHCO3 from 9.8 to 1.96 g/L, Na2HPO4 from 9.3 to 1.86 g/L) according to McDougall's method. The diets were supplemented with 16 g basic diets with forage to the concentrate ratio of 50:50. The experiments were conducted over 13-day incubation periods, with 9 days adaption and 4 days sample collection. The results showed low AS pH decreased dry matter (DM) degradability (64.37 vs. 58.67%), organic matter (OM) degradability (64.38 vs. 59.32%), neutral detergent fiber (NDF) degradability (46.87 vs. 39.94%), acid detergent fiber (ADF) degradability (38.16 vs. 31.13%), and crude protein (CP) degradability (70.33 vs. 62.99%), respectively. Compared with the high AS pH, the low AS pH increased the proportion of butyrate (P = 0.008) and decreased the proportion of propionate (P < 0.001). At the bacteria community, the low AS pH increased the abundances of Spirochaetes (P = 0.001) and Synergistetes (P = 0.004) and decreased the Verrucomicrobia abundance (P = 0.004) in solid-associated bacteria. At the genus level, the low AS pH increased the abundance of Lactobacillus (P = 0.050) and decreased the abundance of Schwartzia (P = 0.002) in solid-associated bacteria. The abundances of Prevotellaceae_YAB2003_group (P = 0.040), Schwartzia (P = 0.002), and Ruminobacter (P = 0.043) were lower in the low AS pH group compared with the high AS pH group in liquid-associated bacteria. Low AS pH decreased the number of Ruminococcus albus, Ruminococcus flavefaciens, Fibrobacter succinogenes (P < 0.001) both in the solid- and liquid-associated bacteria, respectively. The results of the present study included three groups of bacteria communities according to the different sensitives to rumen pH: the abundances of Lactobacillus, Succinivibrio, and Prevotella_7 are increased with decreasing AS pH; the amounts of R. albus, R. flavefaciens, F. succinogenes as well as the abundances of Schwartzia and Ruminobacter decreased with the reducing AS pH; the abundances of Selenomonas_1, Rikenellaceae_RC9_gut_group, and Succiniclasticum were not affected by the AS pH in RUSTITEC.

Feed intake, nutrient digestibility, and selected rumen parameters in feedlot bulls fed diets with different feed additives

An experiment was conducted to evaluate the feed intake, nutrient digestibility and selected rumen parameters in feedlot bulls fed diets containing different feed additives. Six rumen-cannulated Nellore bulls (age = 8 ± 1.0 months; initial BW = 225 ± 13.2 kg) were distributed in a 6 × 6 Latin square design. Six experimental diets based on 30% corn silage and 70% concentrate on a dry matter (DM) basis were evaluated. Diets differed in feed additive on a DM basis, as follows: 1.4% bicarbonate and magnesium oxide in 3:1 ratio (BOX); 36 ppm lasalocid sodium (LAS); 30 ppm monensin sodium (MON); 25 ppm virginiamycin (VIR); 30 ppm monensin sodium plus 25 ppm virginiamycin (MV); and 3.15% commercial mineral supplement containing D-limonene and exogenous α-amylase (EOA). The experiment lasted 144 d, with six periods of 24 d. Each period consisted of 14 d for dietary adaptation, 3 d for feces and urine collection, and 7 d for omasal and ruminal digesta collection. Bulls fed the BOX diet showed greater (P < 0.05) intake of DM, organic matter (OM), neutral detergent fiber (apNDF), crude protein (CP), and starch compared to the other diets. Diets with LAS, MON, VIR, MV, or EOA did not influence (P > 0.05) the DM, OM, apNDF, CP, or starch intake of feedlot bulls. Bulls fed the EOA diet showed greater (trend; P = 0.09) ruminal digestibility of starch compared to the other diets. The feed additives did not affect (P > 0.05) the intestinal or total tract digestibility of starch, rumen pH, microbial efficiency, total rumen fluid, dilution rate, rate of intake, rate of degradation, or passage rate of the DM, OM, apNDF, and starch. In conclusion, LAS, MON, VIR, MV, and EOA diets reduced nutrient intake compared to BOX. Although all feed additives presented similar effects on rumen pH, temperature, and kinetics the presence of exogenous α-amylase in the EOA diet may increase ruminal starch digestibility and apparent total tract digestibility of DM and OM.

300 Effects of Associating Feed Additives on Rumen Ph Dynamics by Feedlot Cattle Fed a High-concentrate Diet

Our objective was to evaluate the effects of feed additives on ruminal pH of finishing cattle fed a 90%-concentrate diet. Twenty four 18-mo Angus-Nellore crossbred bulls (IBW, 456 ± 6,5 kg) were allocated in a completely randomized design to three treatments with eight replicates each, as follows: 1) Control (MON) - Sodium Monensin (26 mg/kg DM, Rumensin, Elanco Animal Health); 2) Crina® RumistarTM (CR) - a blend of essential oils, 90 mg/kg DM + exogenous α-amylase, 560 mg/kg DM) and 3) CR + HyD® (25-hydroxy-vitamin-D3 at 1 mg/animal/d, CRD, DSM Nutritional Products). The ruminal pH and temperature was monitored individually for 98 days, using a wireless bolus, (SmaXtec Animal Care, Austria). Data were analyzed using the Mixed procedure of SAS and means comparison evaluated by Tukey test at P&lt; 0.05. During adaptation period (i.e. first 14 days), bulls fed CR and CRD had increased rumen mean pH (6.40 and 6.36 vs. 6.16; P &lt; 0.01) and minimum pH (5.89 and 5.87 vs. 5.57; P &lt; 0.01) than bulls fed MON. In addition, rumen pH from bulls fed CR spent less time below 6.0 than bulls fed MON (256.07 vs. 452.62 min/d; P = 0.05). Regarding the total period, bulls fed MON had lower mean (6.22 vs. 6.51 and 6.42, P &lt; 0.01) and minimum rumen pH (5.60 vs. 5.92 and 5.85, P &lt; 0.01) than bulls fed CR and CRD. Additionally, feeding MON increased time duration of rumen pH (390.79 min/day, P &lt; 0.01) and had a larger area below 6.0 (81.52 min x pH units/day; P &lt; 0.01). Moreover, the addition of monensin increased pH time duration below 5.8 (161.10 vs. 121.13 and 122.56 min/day; P = 0.02) compared with CR and CRD, and increased ruminal temperature (39.60 vs. 39.51 and 39.5 °C; P &lt; 0.01). We conclude that feeding Crina® RumistarTM and Crina® RumistarTM HyD® increased the rumen pH of bulls.

318 Effect of Initial Providing Time of Oat Hay on Performance, Health, Behavior and Rumen Fermentation in Calves

To determine the appropriate time to feed hay to calves, 210 healthy Holstein calves at d 2 were randomly divided into 3 groups: feeding basic diet (starter) without hay (CON), inclusion of oat hay from the second week (H2) or fourth week (H4) in addition to the basic diet. All calves were weaned on d 56 and raised in the same hutches until the end of the experiment (d 70). Calf starter intake and fecal score were recorded daily throughout the experimental period. Body weight, body size, blood and rumen fluid samples were collected every 2 weeks before weaning and once a week after weaning. Inclusion of oat hay in the basic diet (H2 and H4) resulted in increased body weight (P &lt; 0.01) and average daily gain (P &lt; 0.01) throughout the experiment when compared to the basic diet (CON) only. Calves fed oat hay from 2 weeks of life had the highest starter intake (P &lt; 0.01), average daily gain (P &lt; 0.01) in the pre- and post-weaning periods. Body length and heart girth was similar between treatments. The H2 calves had lower diarrhea frequency (P &lt; 0.05) and diarrhea days (P &lt; 0.05) during the post-weaning period. Compared to the CON calves, inclusion of hay increased the rumen pH (P &lt; 0.01), while decreasing the NH3-N (P &lt; 0.01) and tend to decrease the total VFA (P &lt; 0.06) during the entire trial. Calves in H2 treatment spent more time ruminating (P &lt; 0.01), but less time standing (P &lt; 0.05), eating starter (P &lt; 0.01) and engaging in abnormal behaviors (P &lt; 0.01). In conclusion, calves supplemented with oat hay improved growth rate and rumen fermentation when compared with calves fed only starter, and adding hay from 2 weeks of calves life may be the best choice for the farm to have the greatest growth and health performance.

505 Late-Breaking: Ruminal Microbiota, Inflammation Cytokines, and Performance of High-yield Dairy Cows Supplemented with Saccharomyces Cerevisiae Culture

Dramatic increases in milk yields in recent decades have created challenges in terms of rumen pH and microbial health which ultimately impact dairy cow health. The objective of this study was to assess the effects on ruminal pH, Volatile Fatty Acid (VFA), microbiota, inflammation, and performance of high-yield dairy cows by supplementing Saccharomyces cerevisiae culture (SC). Forty Holstein cows were divided into two groups based on their milk yield, days of milk, and parity fed the same basal ration diet that did or did not contain 100 g of SC /cow per day. Individual dry matter intake (DMI) and milk yield were recorded each day. Rumen fluid and milk samples were collected after 2 hours of morning feeding at intervals of 15 days during the experiment period. The data showed that rumen pH was increased by 0.19 (P = 0.09) when SC was supplemented than no SC was provided. SC-supplemented cow consumed 0.28 kg (P &lt; 0.05) extra DM/d. Those supplemented with SC produced 1.36 kg (P &lt; 0.05) more milk/cow per day than did non-supplemented cows. Milk fat percentage was higher (4.11 vs. 3.96%) for cows receiving SC. There were no differences in milk protein percentage. Rumen fluid VFA concentration was not statistically affected by SC but was numerically higher acetic and lower propionic for supplemented cows. The blood of the SC group with lower inflammation cytokines and somatic cell count (SCC). SC-supplemented cows had a greater relative abundance of Prevotellaceae, Succinivibrionaceae, Fibrobacteraceae, Lactobacillaceae, and lower relative abundance of Spirochaetaceae, Methanobacteriaceae, Enterobacteriaceae than the unsupplemented cows. It had greater functions on xylanolysis, fermentation, cellulolysis in the rumen in terms of the KEGG function prediction analysis. This study demonstrated that high-yield lactation cows receiving supplemental SC produced more milk and potentially reduced the inflammation and enhanced rumen cellulolysis bacteria growth.

321 Extrusion of Grass Silage Increase Intake and Milk Yield in Dairy Cows

This research evaluated effects of grass silage extrusion on dairy cow performance. A grass dominated (70% timothy, 26% meadow fescue, 3% red clover and 1% undefined) first cut ley was harvested on June 13, 2019, and 10 days later near Uppsala, Sweden (58°83′ N, 17°82′ E). Crops were wilted (45% DM for early cut, 50% DM for late cut), round baled and wrapped into plastic film for ensiling. At feeding out, bales were chopped in a TMR feeder, and a portion was processed in an extruder, where screws shear the material under pressure, for further particle size reduction and cell wall break up. Eight Swedish Red cows in two blocks (4 ruminally fistulated, 143 ± 38 DIM and 4 intact, 68 ± 10 DIM) were used in a Latin square design experiment with 4 periods of three weeks each and 4 treatments. The 2x2 factorial arrangement of treatments included silage from early or late harvest that was chopped or extruded. Silage was fed separately ad libitum and supplemented (daily amounts on an as fed basis) with 2 kg of soybean meal, a compound feed (6 kg for fistulated and 8 kg for intact cows), and 120 g of a mineral mix. Extrusion increased silage DMI (1.8 kg/d, P &lt; 0.001) with greater effect at late harvest (P = 0.021 for interaction between processing and harvest) and milk yield (1.8 kg ECM/d, P = 0.004) with a tendency to greater effect at late harvest (P = 0.055). Extrusion depressed total tract OM digestibility (2.3 percentage points, P &lt; 0.001), eating time (0.5 h/d, P = 0.014), rumination time (2.0 h/d, P &lt; 0.001) and rumen pH (0.1 units, P = 0.008). Extrusion improves intake and milk production in dairy cows, despite depressed digestibility.