High concentrate-induced subacute ruminal acidosis (SARA) increases plasma acute phase proteins (APPs) and cortisol in goats

The aim of this study was to investigate changes of stress status in dairy goats induced to subacute ruminal acidosis (SARA). The level of acute phase proteins (APPs) including haptoglobin (HP) and serum amyloid A (SAA) in plasma and their mRNA expression in liver, as well as plasma cortisol and genes expression of key factors controlling cortisol synthesis in adrenal cortex were compared between SARA and control goats. SARA was induced by feeding high concentrate diet (60% concentrate of dry matter) for 3 weeks (SARA, n=6), while control goats (Con, n=6) received a low concentrate diet (40% concentrate of dry matter) during the experimental time. SARA goats showed ruminal pH below 5.8 for more than 3 h per day, which was significantly lower than control goats (pH>6.0). SARA goats demonstrated a significant increase of hepatic HP and SAA mRNA expression (P<0.05), and the level of HP but not SAA in plasma was markedly increased compared with control (P<0.05). The level of cortisol in plasma showed a trend to increase in SARA goats (0.05<P<0.1). In adrenal cortex, mRNA expression of 17α-hydroxylase cytochrome (P450_17α) (P<0.01) and 3β-hydroxysteroid dehydrogenase (3β-HSD) (P<0.05) was significantly increased in SARA goats. The contents of 3β-HSD and P450 side-chain cleavage protein were increased by 58.6% and 39.4%, respectively, but did not reach the statistical significance (P>0.05). These results suggested that SARA goats experienced a certain stress status, exhibiting an increase in HP production and cortisol secretion.     

Effects of Bacillus subtilis natto on milk production,rumen fermentation and ruminal microbiome of dairy cows

Two experiments were conducted to evaluate the effects of Bacillus subtilis natto, which was initially isolated from fermented soybeans on milk production, rumen fermentation and ruminal microbiome in dairy cows. In Experiment 1, 36 early lactation Chinese Holstein dairy cows (56 ± 23 days in milk) were randomly assigned to three groups: Control, cows were fed total mixed ration (TMR); BSNLOW, TMR plus 0.5 × 10¹¹ colony-forming units (cfu) of B. subtilis natto/cow per day; and BSNHIGH, TMR plus 1.0 × 10¹¹ cfu of B. subtilis natto/cow per day. During the 70-day treatment period, daily milk production and daily milk composition were determined in individual cows. The results showed that supplementing dairy cows with 0.5 × 10¹¹ and 1.0 × 10¹¹ cfu of B. subtilis natto linearly increased (P < 0.01) milk production (25.2 and 26.4 kg/day v. 23.0 kg/day), 4% fat-corrected milk (27.3 and 28.1 kg/day v. 24.2 kg/day), energy-corrected milk (27.3 and 28.2 kg/day v. 24.2 kg/day), as well as milk fat (1.01 and 1.03 kg/day v. 0.88 kg/day), protein (0.77 and 0.82 kg/day v. 0.69 kg/day) and lactose yield (1.16 and 1.22 kg/day v. 1.06 kg/day) but decreased milk somatic cell counts (SCC) by 3.4% to 5.5% (P < 0.01) in BSNLOW and BSNHIGH treatments compared with Control. In Experiment 2, four rumen-cannulated dairy cows were fed the basal diet from 1 to 7 days (pre-trial period) and rumen samples were collected on days 6 and 7; the same cows then were fed 1.0 × 10¹¹ cfu/day B. subtilis natto from days 8 to 21 (trial period) and rumen samples were collected on days 20 and 21. B. subtilis natto was discontinued from days 22 to 28 (post-trial period) and rumen samples were collected on days 27 and 28. Compared with the pre- and post-periods, ruminal pH decreased by 2.7% to 3.0% during the trial period (P < 0.01), whereas ammonia nitrogen (NH₃-N), total volatile fatty acids and molar proportion of propionate (P < 0.01) and valerate (P < 0.05) increased. Molar proportion of acetate decreased and the acetate to propionate ratio was lower (P < 0.01) during the trial period. However, no differences for 24-h in sacco dry matter digestibility were detected among different periods (treatments) though NDF digestibility was reduced in the trial and post-trial periods (P < 0.01). Compared with pre-trial period, total ruminal bacteria, proteolytic and amylolytic bacteria in rumen enumerated by culture methods increased by 15.0%, 16.2% and 11.7%, respectively (P < 0.01) but protozoa decreased to 5.35 log₁₀ cfu/ml (P < 0.01) during the trial period. These results demonstrate that B. subtilis natto improves milk production and milk components yield, decreases SCC and promotes the growth of total ruminal bacteria, proteolytic and amylolytic bacteria, which indicate that B. subtilis natto has potential to be applied as a probiotic for dairy cows.     

Effects of medium-chain fatty acid supplementation on performance and rumen fermentation of lactating Holstein dairy cows

Medium-chain fatty acids (MCFAs) have antimicrobial properties and cause negative or positive effects on animal performance depending on its dosage. We hypothesized that MCFA supplementation at a lower dose (i.e., 0.05–0.2% of dietary DM) would increase rumen pH and milk production without decreasing nutrient digestibility which is typically observed with the higher inclusion rates (i.e., >1% of dietary DM). The objective of this study was to evaluate the effects of MCFA supplementation at a lower dose on productivity, plasma energy metabolite concentrations, apparent total tract nutrient digestibility, rumen fermentation, and rumen microbial profile of lactating dairy cows. Thirty (n = 8 primiparous, n = 22 multiparous) Holstein cows in mid-lactation (637 ± 68.5 kg of initial BW, 98.5 ± 27.4 d in milk; mean ± standard deviation) were used in a crossover design with two 28-d periods. The MCFA supplement, consisted of 25% MCFA (containing 32% C8:0, 21% C10:0, 47% C12:0 on DM basis) and 75% carrier ingredients, was fed at 0.25% of dietary DM replacing dry ground corn in control (CON). Total inclusion of MCFA was 0.063% of dietary DM. No differences were observed in DM intake, apparent total tract nutrient digestibility and BW change between MCFA and CON. Milk and milk component yields did not differ between treatment groups. The MCFA supplementation tended to have higher minimum rumen pH (5.66 vs. 5.54), and decreased daily fluctuation range of rumen pH (1.17 vs. 1.40) compared to CON. However, the duration of acidosis (pH < 5.8, min/d) did not differ between treatment groups and ruminal total volatile fatty acid concentration and its profile did not differ between treatment groups. For rumen microbiota, the Chao1 index of bacterial community tended to be lower (10.9 vs. 11.6) whereas the Shannon index did not differ (0.91 vs. 0.93) in MCFA compared to CON, and both indices did not differ for archaeal and protozoan communities between treatment groups. The relative abundance of Methanobrevibacter gottschalkii increased when supplemented with MCFA (5.14 vs. 4.92%). These results suggest that supplementation of MCFA at 0.063% dietary DM may not affect overall animal performance or total tract nutrient digestibility, but decrease the daily range of pH and the bacterial richness in the rumen.     

Effects of sodium selenite and coated sodium selenite on lactation performance,total tract nutrient digestion and rumen fermentation in Holstein dairy cows

Se can enhance lactation performance by improving nutrient utilization and antioxidant status. However, sodium selenite (SS) can be reduced to non-absorbable elemental Se in the rumen, thereby reducing the intestinal availability of Se. The study investigated the impacts of SS and coated SS (CSS) supplementation on lactation performance, nutrient digestibility, ruminal fermentation and microbiota in dairy cows. Sixty multiparous Holstein dairy cows were blocked by parity, daily milk yield and days in milk and randomly assigned to five treatments: control, SS addition (0.3 mg Se/kg DM as SS addition) or CSS addition (0.1, 0.2 and 0.3 mg Se/kg DM as CSS addition for low CSS (LCSS), medium CSS (MCSS) and high CSS (HCSS), respectively). Experiment period was 110 days with 20 days of adaptation and 90 days of sample collection. Dry matter intake was higher for MCSS and HCSS compared with control. Yields of milk, milk fat and milk protein and feed efficiency were higher for MCSS and HCSS than for control, SS and LCSS. Digestibility of DM and organic matter was highest for CSS addition, followed by SS addition and then control. Digestibility of CP was higher for MCSS and HCSS than for control, SS and LCSS. Higher digestibility of ether extract, NDF and ADF was observed for SS or CSS addition. Ruminal pH decreased with dietary Se addition. Acetate to propionate ratio and ammonia N were lower, and total volatile fatty acids (VFAs) concentration was greater for SS, MCSS and HCSS than control. Ruminal H ion concentration was highest for MCSS and HCSS and lowest for control. Activities of cellobiase, carboxymethyl-cellulase, xylanase and protease and copies of total bacteria, fungi, Ruminococcus flavefaciens, Fibrobacter succinogenes and Ruminococcus amylophilus increased with SS or CSS addition. Activity of α-amylase, copies of protozoa, Ruminococcus albus and Butyrivibrio fibrisolvens and serum glucose, total protein, albumin and glutathione peroxidase were higher for SS, MCSS and HCSS than for control and LCSS. Dietary SS or CSS supplementation elevated blood Se concentration and total antioxidant capacity activity. The data implied that milk yield was elevated due to the increase in total tract nutrient digestibility, total VFA concentration and microorganism population with 0.2 or 0.3 mg Se/kg DM from CSS supplementation in dairy cows. Compared with SS, HCSS addition was more efficient in promoting lactation performance of dairy cows.     

Effects of the processing methods of corn grain and soybean meal on milk protein expression profiles in dairy cows

A proteomic approach was used to investigate the effects of the processing method of corn grain and soybean meal on the milk protein expression profile in lactating dairy cows. A total of 12 multiparous Holstein dairy cows were used in a 4×4 Latin square design with a 2×2 factorial arrangement. The primary factors examined were corn (finely ground (FGC) v. steam-flaked (SFC)) and soybean meal (solvent-extracted (SSBM) v. heat-treated (HSBM)), which were used to formulate four diets with the same basal ingredient: 27% FGC and 9% SSBM; 27% SFC and 9% SSBM; 27% FGC and 9% HSBM; and 27% SFC and 9% HSBM. Each period lasted for 21 days. Milk samples were collected on days 18, 19 and 20 of each period. Changes in the milk proteins were assessed by two-dimensional (2D) electrophoresis and ImageMaster 2D Platinum 6.0 software. A total of 13 spots displayed variations in protein spot abundance according to the statistical analysis. These spots were identified by a matrix-assisted laser desorption/ionization-time of flight/time of flight MS. According to the gels, the relative abundance of α_s2-casein (CN) fragments was higher in the cows fed the SFC-HSBM than that for SFC-SSBM, whereas β-CN, α-lactalbumin and zinc-alpha-2-glycoprotein fragments were down-regulated in HSBM-fed cows. The relative decrease of β-CN expression was validated by western blot and agreed with the MS data. These results suggested that the method used to process soybean meal modified the synthesis and secretion of milk proteins in lactating dairy cows’ mammary glands.     

Treatment of corn with lactic acid or hydrochloric acid modulates the rumen and plasma metabolic profiles as well as inflammatory responses in beef steers

Background

High-grain diets that meet the energy requirements of high-producing ruminants are associated with a high risk of rumen disorders. Mild acid treatment with lactic acid (LA) has been used to modify the degradable characteristics of grains to improve the negative effects of high-grain diets. However, the related studies mainly focused on dairy cows and explored the effects on rumen fermentation, production performance, ruminal pH and so forth. And up to date, no studies have reported the hydrochloric acid (HA) treatment of grains for ruminant animals. Therefore, based on metabolomics analysis, the aim of this study was to evaluate the effects of treatment of corn by steeping in 1% LA or 1% HA for 48?h on the rumen and plasma metabolic profiles in beef steers fed a high corn (48.76%) diet with a 60:40 ratio of concentrate to roughage. The inflammatory responses of beef cattle fed LA- and HA-treated corn were also investigated.

Results

Based on ultra-high-performance liquid tandem chromatography-quadrupole time-of-flight mass spectrometry (UHPLC-QTOF/MS) metabolomics and multivariate analyses, this study showed that steeping corn in 1% LA or 1% HA modulated the metabolic profiles of the rumen. Feeding beef steers corn steeped in 1% LA or 1% HA was associated with lower relative abundance of carbohydrate metabolites, amino acid metabolites, xanthine, uracil and DL-lactate in the rumen; with higher ruminal pH; with lower concentrations of acetate, iso-butyrate and iso-valerate; and with a tendency for lower ruminal lipopolysaccharide (LPS) concentrations. Moreover, the data showed lower concentrations of plasma C-reactive protein, serum amyloid A, haptoglobin, interleukin (IL)-1β and IL-8 in beef steers fed 1% LA- or HA-treated corn. The 1% LA treatment decreased the concentrations of plasma LPS, LPS-binding protein and tumour necrosis factor-alpha and the relative abundance of L-phenylalanine, DL-3-phenyllactic acid and tyramine in plasma. The 1% HA treatment decreased the relative abundance of urea in plasma and increased the relative abundance of all amino acids in the plasma.

Conclusions

These findings indicated that LA or HA treatment of corn modulated the degradation characteristics of starch, which contributed to improving the rumen and plasma metabolic profiles and to decreasing inflammatory responses in beef steers fed a high-concentrate diet.

     

Influence of barley grain particle size and treatment with citric acid on digestibility,ruminal fermentation and microbial protein synthesis in Holstein calves

Chemical and physical treatments of barley grain increase ruminally resistant starch and can improve the rumen fermentation pattern. The objective of the present study was to evaluate the effects of chemical (addition of citric acid, CA) and physical (grinding to two different particle sizes, PS) treatment of barley grain on performance, rumen fermentation, microbial protein yield in the rumen and selected blood metabolites in growing calves. In all, 28 male Holstein calves (172±5.1 kg initial BW) were used in a complete randomised design with a factorial arrangement of 2 barley grain particle sizes×2 levels of citric acid. The diets were as follows: (i) small PS (average 1200 µm) barley grain soaked in water (no CA addition); (ii) small PS barley grain soaked in a CA solution (adding 20 g CA/kg barley); (iii) large PS (average 2400 µm) barley grain soaked in water (no citric acid addition) and (iv) large PS barley grain soaked in a citric acid solution (adding 20 g CA/kg barley). Barley grain was then incorporated at 35% in a total mixed ration and fed to the calves for 11 weeks. Feeding small PS barley decreased feed intake (P=0.02) and average daily weight gain (P=0.01). The addition of CA to barley grain did not affect intake but increased weight gain (P<0.01) and improved feed to gain ratio (P=0.03). Digestibility of organic matter and NDF tended (P<0.10) to increase, whereas faecal scoring was improved (P=0.03) and the presence of undigested grain particles in faeces was reduced (P<0.01) with CA-treated barley grain. Glucose and urea concentrations were increased (P<0.01) in the blood of calves fed the CA-treated barley grain. Ruminal pH tended (P=0.08) to be decreased with more finely ground barley and was increased when barley grain was treated with CA. Total volatile fatty acid concentrations in the rumen did not differ among treatments (P>0.05). However, the molar proportion of propionate was increased (P=0.03) when barley was more finely ground, and that of acetate was increased (P=0.04) when CA was added to barley grain. The ruminal concentration of ammonia nitrogen was increased (P<0.01) and microbial nitrogen synthesis in the rumen tended to decrease by adding CA to barley. Treating barley grain with citric acid increased fibre digestibility of total mixed rations, attenuated the decrease in ruminal pH, and improved weight gain and feed efficiency in male Holstein growing calves fed a high-cereal diet (550 g cereal grain/kg diet).