Effects of corn and soybean meal types on rumen fermentation, nitrogen metabolism and productivity in dairy cows

Effects of amino resin-treated and heat-treated soybean meal on ruminal fermentation, nutrient digestion, and nitrogen partitioning in continuous culture

The objective of this study was to evaluate the effects of amino resin-treated soybean meal (SBM) on ruminal fermentation, nutrient digestion, and N partitioning. Treatments were: (1) untreated solvent-extracted SBM, (2) amino resin-treated SBM (AR-SBM), and (3) heat-treated SBM (HT-SBM). The experimental design was arranged as a replicated 3 × 3 Latin square with 6 fermenters in a dual-flow continuous culture system. Treatments were randomly assigned to fermenters within a Latin square for each period. Each fermenter was fed 106 g/d of diet DM equally distributed in 2 feeding times daily at 0800 and 1800. Diets were formulated to contain 16% CP, 30% NDF, and 30% starch across treatments. The experiment consisted of 3 experimental periods, each lasting for 10 d. The first 7 d of each period were considered adaptation, and the last 3 d were used for sampling and data collection. On d 8 and 9, samples were collected for analysis of diurnal variation in concentrations of NH3-N, pH, and VFA during the first 8 h after feeding. On d 8, 9, and 10, samples were collected from the liquid and solid effluents accumulated over 24 h for analysis of daily averages of NH3-N and VFA pools, and true ruminal digestibility estimates. Data were analyzed using the MIXED procedure of SAS and significance was declared when P ≤ 0.05. The model included the fixed effect of treatment and random effects of square, period, and fermenter within square, while time and interaction treatment × time were included for analyses of diurnal variation, with time as repeated measures. Compared with SBM, the cultured ruminal contents of AR-SBM and HT-SBM had lower NH3-N concentrations, indicating lower microbial fermentation of protein. Molar proportions of isovalerate and isobutyrate were greater in SBM than AR-SBM and HT-SBM, with greater molar proportion of isobutyrate for SBM particularly during the first 2 h after feeding. Flow of NH3-N was greater for SBM compared with AR-SBM and HT-SBM, whereas NAN flow, bacterial N flow, and N efficiency were greater for AR-SBM and HT-SBM compared with SBM. Our results indicate that both the amino resin and heat treatments of SBM allow for similar decrease in microbial degradation of CP without limiting microbial protein synthesis in diets with 16% CP. Amino resin treatment may be effective in reducing microbial fermentation of protein in the rumen without adverse effects on digestibility or fermentation parameters as compared with SBM.

Bioavailability and Bioefficacy of Hemp By-Products in Ruminant Meat Production and Preservation: A Review

Plant by-products obtained from agro-industrial processes require valorisation to demonstrate their potential for enhancing animal health, meat production, and shelf life extension. One example is the fast-growing hemp industry, which produces seeds, leaves, seed oil, and cake. Studies on the nutritional value of hempseed cake have shown it can be a valuable source of protein in ruminant diets. However, there is limited documentation on the bioavailability and bioefficacy of hemp phytochemicals for improving ruminant health, production, and extending meat shelf life. The current review provides an overview of existing information on nutrient and phytochemical composition of hemp by-products, their bioavailability, and bioefficacy, and explores current limitations and prospects regarding their valorisation.

Synchrony Degree of Dietary Energy and Nitrogen Release Influences Microbial Community, Fermentation, and Protein Synthesis in a Rumen Simulation System

Synchrony of energy and nitrogen release in rumen has been proposed to maximize ruminal microbial fermentation. However, the information regarding bacterial community composition and its metabolism under a higher or lower degree of synchronization is limited. In our study, a 0 to 6 h post-feeding infusion (first half infusion, FHI), 6 to 12 h post-feeding infusion (second half infusion, SHI), and 0 to 12 h post-feeding infusion (continuous infusion, CI) of maltodextrin were used to simulate varying degrees of synchronization of energy and nitrogen release in a rumen simulation system. In addition, the bacterial community, metabolite, enzyme activity, and microbial protein synthesis (MPS) were evaluated. Compared with the FHI and CI, the relative abundance of Fibrobacter, Ruminobacter, BF311, and CF231 decreased in the SHI, but that of Klebsiella and Succinivibrio increased in the SHI. The NH₃-N and branched-chain volatile fatty acids were significantly higher, but propionate content and activities of glutamate dehydrogenase (GDH) and alanine dehydrogenase were significantly lower in the SHI than those in the FHI and CI. The SHI had lower MPS and less efficiency of MPS than the FHI and CI, which indicated that the SHI had a lower degree of synchronization. Correlation analysis showed that MPS was positively related to GDH activity and relative abundance of Fibrobacter but negatively related to NH₃-N and relative abundance of Klebsiella. Therefore, a higher degree of synchronization of energy and nitrogen release increased MPS partly via influencing the bacterial community, metabolism, and enzyme activities of ammonia assimilation in the in vitro fermenters.

Specific enrichment of microbes and increased ruminal propionate production: the potential mechanism underlying the high energy efficiency of Holstein heifers fed steam-flaked corn

Corn grain has a high starch content and is used as main energy source in ruminant diets. Compared with finely ground corn (FGC), steam-flaked corn (SFC) could improve the milk yield of lactating dairy cows and the growth performance of feedlot cattle, but the detailed mechanisms underlying those finding are unknown. The rumen microbiome breaks down feedstuffs into energy substrates for the host animals, and contributes to feed efficiency. Therefore, the current study was conducted to investigate the ruminal bacterial community changes of heifers fed differently processed corn (SFC or FGC) using 16S rRNA sequencing technologies, and to uncover the detailed mechanisms underlying the high performance of ruminants fed the SFC diet. The results revealed that different processing methods changed the rumen characteristics and impacted the composition of the rumen bacteria. The SFC diet resulted in an increased average daily gain in heifers, an increased rumen propionate concentration and a decreased rumen ammonia nitrogen concentration. The relative abundance of the phylum Firmicutes and Proteobacteria were tended to increase or significantly increased in the heifers fed SFC diet compared with FGC diet. In addition, the relative abundance of amylolytic bacteria of the genera Succinivibrio, Roseburia and Blautia were elevated, and the cellulolytic bacteria (Ruminococcaceae_UCG-014 and Ruminococcaceae_UCG-013) were decreased by the steam flaking method. Spearman correlation analysis between the ruminal bacteria and the microbial metabolites showed that the rumen propionate concentration was positively correlated with genera Succinivibrio and Blautia abundance, but negatively correlated with genera Ruminococcaceae_UCG-014 abundance. Evident patterns of efficient improvement in rumen propionate and changes in rumen microbes to further improve feed conversion were identified. This observation uncovers the potential mechanisms underlying the increased efficiency of the SFC processing method for enhancing ruminant performance.

A study on comparative feeding value of corn flakes according to temperature and retention time in the pressurized steam chamber

This study aimed to investigate the effects of temperature and retention time of the pressurized steam chamber on the ruminal fermentation characteristics and nutrient degradability of corn flakes in three Korean native Hanwoo cows and three Holstein cows implanted with a ruminal fistula. Corn kernels were categorized into 13 groups based on the chamber temperature (range, 100°C–116°C) and retention time (range, 700–950 s). The pH value was lowest in T1 regardless of breed. Propionate concentration was the highest in T2 (p < 0.05). Total-volatile fatty acid (VFA) concentration was slightly but not significantly greater in T2 than in other conditions. Dry matter (p < 0.05), starch, and crude protein (p < 0.05) degradability were the highest in T1. At different incubation times and with different breeds, dry matter, starch, and crude protein degradability of corn flakes were the highest in T1. Thus, the present results indicate that the optimal temperature and retention time of the pressurized steam chamber should be 100°C–105°C and 700–720 s.

Effect of dietary crude protein degradability and corn processing on lactation performance and milk protein composition and stability

The present study aimed to evaluate the effect of crude protein degradability and corn processing on lactation performance, milk protein composition, milk ethanol stability (MES), heat coagulation time (HCT) at 140°C, and the efficiency of N utilization for dairy cows. Twenty Holstein cows with an average of 162 ± 70 d in milk, 666 ± 7 kg of body weight, and 36 ± 7.8 kg/d of milk yield (MY) were distributed in a Latin square design with 5 contemporaneous balanced squares, 4 periods of 21 d, and 4 treatments (factorial arrangement 2 × 2). Treatment factor 1 was corn processing [ground (GC) or steam-flaked corn (SFC)] and factor 2 was crude protein (CP) degradability (high = 10.7% rumen-degradable protein and 5.1% rumen-undegradable protein; low = 9.5% rumen-degradable protein and 6.3% rumen-undegradable protein; dry matter basis). A significant interaction was observed between CP degradability and corn processing on dry matter intake (DMI). When cows were fed GC with low CP degradability, DMI increased by 1.24 kg/d compared with cows fed GC with high CP degradability; however, CP degradability did not change DMI when cows were fed SFC. Similar interactions were observed for MY, HCT, and lactose content. When cows were fed GC diets, high CP degradability reduced MY by 2.3 kg/d, as well as HCT and lactose content, compared with low CP degradability. However, no effect of CP degradability was observed on those variables when cows were fed SFC diets. The SFC diets increased dry matter and starch total-tract digestibility and reduced β-casein (CN) content (% total milk protein) compared with GC diets. Cows fed low-CP degradability diets had higher glycosylated κ-CN content (% total κ-CN) and MES, as well as milk protein content, 3.5% fat-corrected milk, and efficiency of N for milk production, than cows fed high-CP degradability diets. Therefore, GC and high-CP degradability diets reduced milk production and protein stability. Overall, low CP degradability increased the efficiency of dietary N utilization and MES, probably due to changes in casein micelle composition, as CP degradability or corn processing did not change the milk concentration of ionic calcium. The GC diets increased β-CN content, which could contribute to reducing HTC when cows were fed GC and high-CP degradability diets.

Lactation-related metabolic mechanism investigated based on mammary gland metabolomics and 4 biofluids' metabolomics relationships in dairy cows

Background

Lactation is extremely important for dairy cows; however, the understanding of the underlying metabolic mechanisms is very limited. This study was conducted to investigate the inherent metabolic patterns during lactation using the overall biofluid metabolomics and the metabolic differences from non-lactation periods, as determined using partial tissue-metabolomics. We analyzed the metabolomic profiles of four biofluids (rumen fluid, serum, milk and urine) and their relationships in six mid-lactation Holstein cows and compared their mammary gland (MG) metabolomic profiles with those of six non-lactating cows by using gas chromatography-time of flight/mass spectrometry.

Results

In total, 33 metabolites were shared among the four biofluids, and 274 metabolites were identified in the MG tissues. The sub-clusters of the hierarchical clustering analysis revealed that the rumen fluid and serum metabolomics profiles were grouped together and highly correlated but were separate from those for milk. Urine had the most different profile compared to the other three biofluids. Creatine was identified as the most different metabolite among the four biofluids (VIP = 1.537). Five metabolic pathways, including gluconeogenesis, pyruvate metabolism, the tricarboxylic acid cycle (TCA cycle), glycerolipid metabolism, and aspartate metabolism, showed the most functional enrichment among the four biofluids (false discovery rate < 0.05, fold enrichment >2). Clear discriminations were observed in the MG metabolomics profiles between the lactating and non-lactating cows, with 54 metabolites having a significantly higher abundance (P < 0.05, VIP > 1) in the lactation group. Lactobionic acid, citric acid, orotic acid and oxamide were extracted by the S-plot as potential biomarkers of the metabolic difference between lactation and non-lactation. The TCA cycle, glyoxylate and dicarboxylate metabolism, glutamate metabolism and glycine metabolism were determined to be pathways that were significantly impacted (P < 0.01, impact value >0.1) in the lactation group. Among them, the TCA cycle was the most up-regulated pathway (P < 0.0001), with 7 of the 10 related metabolites increased in the MG tissues of the lactating cows.

Conclusions

The overall biofluid and MG tissue metabolic mechanisms in the lactating cows were interpreted in this study. Our findings are the first to provide an integrated insight and a better understanding of the metabolic mechanism of lactation, which is beneficial for developing regulated strategies to improve the metabolic status of lactating dairy cows.

Electronic supplementary material

The online version of this article (10.1186/s12864-017-4314-1) contains supplementary material, which is available to authorized users.