Paper mulberry (Broussonetia papyrifera; PM) is an excellent and extensive type of roughage in Asia. This study aimed to evaluate the effects of PM silage on the milk production, apparent digestibility, antioxidant capacity, and fecal bacteria composition in Holstein dairy cows. Forty-five lactating Holstein dairy cows with a similar milk yield and parity were selected and randomly assigned to three groups. The control group was fed a non-PM silage diet, and the PM-treated groups were fed 4.5 and 9.0% PM silage supplementary diets for 28 days. Then, treatment groups were fed diets containing 13.5 and 18.0% PM silage for the next 28 days, respectively. PM silage increased the milk urea nitrogen and decreased the somatic cell count (p < 0.05), but did not affect the dry matter intake, milk yield, apparent digestibility, and energy balance of dairy cows. PM silage can enhance the blood total antioxidant capacity, superoxide dismutase, and immune globulin content (p < 0.05). The PM silage significantly decreased the relative abundance of the genera Ruminococcaceae UCG-013 and Tyzzerella-4 (p < 0.05). In conclusion, PM silage enhanced the antioxidant capacity and immunity of dairy cows, but did not influence the milk yield, dry matter digestibility, and fecal bacteria composition.

To better understand the transition of rumen function during the weaning period in dairy calves, sixteen Holstein dairy calves were selected and divided into two groups: pre-weaning (age = 56 ± 7 day, n = 8) and post-weaning (age = 80 ± 6 day, n = 8). The rumen fluid was obtained by an oral gastric tube. The rumen fermentation profile, enzyme activity, bacteria composition, and their inter-relationship were investigated. The results indicated that the post-weaning calves had a higher rumen acetate, propionate, butyrate, and microbial crude protein (MCP) than the pre-weaning calves (p < 0.05). The rumen pH in the post-weaning calves was lower than the pre-weaning calves (p < 0.05). The protease, carboxymethyl cellulase, cellobiohydrolase, and glucosidase in the post-weaning calves had a lower trend than the pre-weaning calves (0.05 < p < 0.1). There was no difference in α and β diversity between the two groups. Linear discriminant analysis showed that the phylum of Fibrobacteres in the post-weaning group was higher than the pre-weaning group. At the genus level, Shuttleworthia, Rikenellaceae, Fibrobacter, and Syntrophococcus could be worked as the unique bacteria in the post-weaning group. The rumen bacteria network node degree in the post-weaning group was higher than the pre-weaning group (16.54 vs. 9.5). The Shuttleworthia genus was highly positively correlated with MCP, propionate, total volatile fatty acid, glucosidase, acetate, and butyrate (r > 0.65, and p < 0.01). Our study provided new information about the rumen enzyme activity and its relationship with bacteria, which help us to better understand the effects of weaning on the rumen function.

High-yield dairy cows with high-concentrate diets are more prone to experiencing health problems associated with rumen microbial imbalance. This study assessed the effects of Saccharomyces cerevisiae culture (SC), a food supplement, on ruminal pH, volatile fatty acid (VFA), inflammatory cytokines, and performance of high-yield dairy cows. Forty Holstein cows with similar characteristics (e.g., milk yield, days of milk, and parity) were randomly divided into two groups: an experimental group fed the basal ration supplemented with the SC of 100 g of SC per cow per day (hour, SC group), and a control group fed the same basal ration diet without SC (i.e., CON group). On average, the supplementation of SC started at 73 days of lactation. The experimental period lasted approximately 70 days (from 18 January to 27 March 2020), including 10 days for dietary adaptation. Milk yield was recorded daily. Rumen fluid and milk samples were collected after 2 h of feeding in the morning of day 0, 15, 30, and 60. The data showed that rumen pH increased (p < 0.05) when cows were provided with SC. On average, the cows in the SC group produced 1.36 kg (p < 0.05) more milk per day than those in the CON group. Milk fat content of cows in the SC group was also higher (4.11% vs. 3.96%) (p < 0.05). Compared with the CON group, the concentration of acetic acid in the rumen fluid of dairy cows in the SC group was significantly higher (p < 0.05). There were no differences (p > 0.05) found in milk protein content and propionic acid between groups. The SC group had a tendency increase in butyric acid (p = 0.062) and total VFA (p = 0.058). The result showed that SC supplementation also enhanced the ratio between acetic and propionic. Most of the mean inflammatory cytokine (IL-2, IL-6, γ-IFN, and TNF-α) concentrations (p < 0.05) of the SC group were lower than CON group. This study demonstrated that high-yield cows receiving supplemental SC could produce more milk with higher fat content, have higher rumen acetate, and potentially less inflammatory cytokines.

Three main crop straws including corn straw (Zea mays, CS), rice straw (Oryza sativa, RS), and wheat straw (Triticum aestivum, WS), and two forages including alfalfa hay (Medicago sativa, AH) and corn silage (Zea mays, CSil) were analyzed in order to compare their ruminal degradability, indigestible neutral detergent fiber (iNDF), intestinal digestibility (ID), and their total-tract digestibility (TTD) of crude protein (CP), neutral detergent fiber (NDF), and acid detergent fiber (ADF) using both an in situ nylon bag technique and a mobile nylon bag technique. The forage samples were incubated in the rumen for 6, 12, 16, 24, 36, 48, 72, and 288 h, respectively, to determine their ruminal degradability. Prior to intestinal incubation, forage samples were incubated in the rumen for 12 h and 24 h to determine the ruminal degradable content of CP, NDF, and ADF, respectively, and for 288 h to determine their iNDF₂₈₈ content. Residues from the ruminal undegradable fractions (12 h for CP, 24 h for NDF and ADF) were subsequently inserted into the duodenum through a cannula to determine their intestinal digestible content. Here, the TTD of CP, NDF, and ADF were determined as the ruminal degradable content + intestinal digestible content. The results showed that AH had the highest iNDF_2.4 (calculated as acid detergent lignin content × 2.4) and iNDF₂₈₈ values (379.42 and 473.40 g/kg of NDF), while CS and CSil had the lowest iNDF_2.4 values (177.44 and 179.43 g/kg of NDF). The ruminal degradability of CP, NDF, and ADF for CS, RS, and WS were lower than those of AH and Csil during the first 48 h of incubation. The potential degradation fraction of CP, NDF, and ADF for CSil was the highest; CS, RS, and WS were intermediate; and AH was the lowest (p < 0.05). CS, RS, and WS had a lower intestinal digestibility with respect to their rumen undegradable content of NDF (p < 0.05), and lower TTD of CP, NDF, and ADF (p < 0.05) compared to AH and CSil. General regression equations with satisfactory accuracy (R² ≥ 0.828) were derived to predict iNDF₂₈₈ and TTD based on their chemical compositions and the ruminal degradation kinetics of different forages. Incorporating this information into rations could improve our ability to optimize main crop straws utilization and milk production.

The objective of this study was to evaluate the GreenFeed (GF) and respiration chambers (RC) for daily and intraday measurements of the enteric gaseous exchange, as well as the metabolic heat production, lying behavior, and feed intake (FI) rate of dairy cows at these 2 respective housing conditions [tie-stall barn (TS) vs. RC] during the summer periods. Sixteen multiparous lactating dairy cows were recruited and arranged in a randomized complete block design with a baseline period established for each cow. Cows were given a basal diet (CON) for a baseline period of 7 d and were then fed a 3-nitrooxypropanol (3-NOP)-containing feed for the subsequent 26 d as experimental period. During both the baseline and the last 7 d of treatment period, gaseous exchanges of each animal were measured in the TS using GF for 8 6-hourly staggered measurements over 3 d, immediately followed by the measurement in RC for 2 d. Corresponding DMI, milk yield, and behavior parameters (e.g., lying behavior and FI rate) in TS and RC were recorded. The correlation coefficients of CH₄ and H₂ using raw data were 0.84 and 0.85, respectively. For all gases, correlation coefficients between GF and RC on individual cow level decreased when the marginal fixed effects (e.g., inhibitor and breed) were corrected by a mixed model. There were no differences in daily CH₄ production or intensity between GF and RC (442 vs. 443 g CH₄/d or 16.6 vs. 16.2 g CH₄ /kg MY). However, greater CH₄ yield was measured by GF than RC (19.0 vs. 17.8 g CH₄/kg DMI), driven by a lower DMI (23.3 vs. 24.6 kg/d) when cows were housed in TS sampled by GF compared with cows being housed and sampled in RC. The correlations for CO₂ production and O₂ consumption were moderate and expected due to the variation associated with the mild heat stress condition during GF measurements in the TS (Thermal humidity index (THI) 56 vs. 68), as indicated by the reduced lying time (-2.1 h/d). At the intraday level, there was an interaction between techniques and hour-of-day for CH₄ production, as indicated by the discrepancies in post-prandial CH₄ emissions between techniques. In summary, this set of results showed that there were strong positive correlations for CH₄ and H₂ emissions between GF and RC based on individual cow data. However, such relationship should be interpreted with caution, given the data clustering resulting from the use of inhibitor 3-NOP. On treatment level, these 2 techniques detected similar inhibitor effect on the estimated daily CH₄ emissions. The intraday patterns of CH₄ and H₂ production captured by GF provided a close approximation for those measured by RC. Nevertheless, potential underestimation may occur, especially following fresh feed delivery. For measuring CO₂ production and O₂ consumption, the GF captured similar intraday variations to those in the RC. However, the estimated daily production and consumption were not directly comparable, which was expected due to the variable thermal conditions during the summer. Further evaluations under the same weather conditions are warranted.

The objective of this study was to determine the effect of dietary supplementation of n-3 polyunsaturated fatty acids (PUFA) and n-6 PUFA on dry matter intake (DMI), energy balance, oxidative stress, and performance of transition cows. Forty-five multiparous Holstein dairy cows with similar parity, body weight (BW), body condition score (BCS), and milk yield were used in a completely randomized design during a 56-d experimental period including 28 d prepartum and 28 d postpartum. At 240 d of pregnancy, cows were randomly assigned to one of the 3 isoenergetic and isoprotein dietary treatments, including a control ration containing 1% hydrogenated fatty acid (CON), a ration with 8% extruded soybean (HN6, high n-6 PUFA source), and a ration with 3.5% extruded flaxseed (HN3; high n-3 PUFA source). The HN6 and HN3 diets had an n-6/n-3 ratio of 3.05:1 and 0.64:1 in prepartum cows and 8.16:1 and 1.59:1 in postpartum cows, respectively. During the prepartum period (3, 2, and 1 wk before calving), DMI, DMI per unit of BW, total net energy intake, and net energy balance were higher in the HN3 than in the CON and NH6 groups. During the postpartum period (2, 3, and 4 wk after calving), cows fed HN3 and HN6 diets both showed increasing DMI, DMI as a percentage of BW, and total net energy intake compared with those fed the CON diet. The BW of calves in the HN3 group was 12.91% higher than those in the CON group. Yield and nutrient composition of colostrum (first milking after calving) were not affected by HN6 or HN3 but milk yield from 1 to 4 wk of milking was significantly improved compared with CON. During the transition period, BW, BCS, and BCS changes were not affected. Cows fed the HN6 diet had a higher plasma NEFA concentration compared with the CON cows during the prepartum period. Feeding HN3 reduced the proportion of de novo fatty acids and increased the proportion of preformed long-chain fatty acids in regular milk. In addition, the n-3 PUFA-enriched diet reduced the n-6/n-3 PUFA ratio in milk. In conclusion, increasing the n-3 fatty acids concentration in the diet increased both DMI during the transition period and milk production after calving, and supplementing n-3 fatty acids was more effective in mitigating the net energy balance after calving.