Changes in the rumen and colon microbiota and effects of live yeast dietary supplementation during the transition from the dry period to lactation of dairy cows.

The first objective of this study was to evaluate the dynamics and their potential association with animal performance of the microbiota in both the rumen and colon of dairy cows as they move from a nonlactation to a lactation ration. The second objective was to assess the potential effects on the microbiota of live yeast supplementation. Twenty-one Holstein cows were split in 2 treatments consisting of 1 × 1010 cfu/d of live yeast (LY; n = 10) or no supplementation (control; n = 11) starting 21 d before until 21 d after calving. At 14 d before and 7 and 21 d after calving, samples of rumen and colon digesta were obtained from each cow using an endoscope. Total DNA was extracted and submitted to high-throughput sequencing. Shannon diversity index, in both the rumen and colon, was unaffected by LY; however, in the rumen it was lowest 7 d after calving and returned to precalving values at 21 d in milk, whereas in the colon it was greatest 14 d before calving but decreased after calving. In the rumen, LY supplementation increased the relative abundance (RA) of Bacteroidales (group UCG-001), Lachnospiracea (groups UCG-002 and UCG-006), and Flexilinea 14 d before calving, and increased RA of Streptococcus 21 d after calving compared with control cows. However, changes in the ruminal microbiota were more drastic across days relative to calving than as influenced by the dietary treatment, and the effect of LY in the colon was milder than in the rumen. The ruminal RA of several genera was associated with postcalving DMI, and that of Gastranaerophilales was the only order positively associated with milk yield. Several genera were positively correlated with feed efficiency, with Clostridiales (unclassified) being the only genus negatively associated with feed efficiency. In the colon, Prevotellaceae (group Ga6A1) was the only genus positively associated with feed efficiency. The ruminal RA of Prevotella 7 and Ruminobacter 14 d precalving was negatively correlated with dry matter intake and milk yield postcalving. The RA of Parabacteroides in the colon 14 d before calving was negatively correlated with milk yield, whereas the RA of Eggerthellaceae (unclassified) and Erysipelotrichaceae (groups c and unclassified) were positively correlated with feed efficiency. Interestingly, LY supplementation doubled the RA of Eggerthellaceae (unclassified) in the colon. It is concluded that microbial diversity in the rumen experiences a transient reduction after calving, whereas in the colon, the reduction is maintained at least until 21 d in milk. Most of the effects of LY on rumen microbiota were observed before calving, whereas in the colon, LY effects were more moderate but consistent and independent of the stage of production. The microbial community of the rumen after calving is more associated with feed intake, milk yield, and feed efficiency than that of the colon. However, the colon microbiota before calving is more associated with feed efficiency after calving than that of the rumen.

Effects of oral administration of acidogenic boluses at dry-off on performance and behavior of dairy cattle.

The aim of this study was to evaluate the potential of oral acidogenic mineral boluses (196 g) containing anionic salts to facilitate the transition from lactation to the dry stage by inducing a mild and temporary metabolic acidosis at dry-off. In experiment 1, 84 lactating cows were randomly allocated to 1 of 3 treatment groups consisting of an oral administration of 0, 1, or 2 boluses 5 d before dry-off to evaluate the effects on milk production. In experiment 2, 16 lactating cows were involved in a crossover study to evaluate the effects of the administration of 2 boluses on milk production, feed intake, and urine pH. In experiment 3, 152 lactating cows were allocated to 1 of 2 treatments (control: no treatment; bolus: 2 oral boluses the day before last milking) to evaluate udder pressure, incidence of milk leakage, and lying behavior during the first days following dry-off. Also, milk yield in the subsequent lactation for all enrolled cows was recorded during the first 60 DIM. In experiment 1, cows receiving 2 boluses had the greatest reduction in milk production (-2.56 kg/d of milk) compared with those receiving 1 bolus or no treatment (-1.15 and -0.23 kg/d, respectively) the second day after bolus application. In experiment 2, the application of oral boluses decreased feed intake of cows during the first 3 d following treatment, and milk production was reduced on d 2 and 3 after bolus application. Reduced urine pH at 8 and 24 h after treatment was observed in bolus cows compared with control cows. In experiment 3, bolus cows had lower udder pressure after drying off, but incidence of milk leakage did not differ between treatments. Bolus cows had an additional 85 min of lying time in the 24 h following dry-off. Serum P and ß-OH-butyrate concentrations were lower in bolus cows than in control cows after dry-off, but no other differences in blood parameters between treatments were observed. Also, no differences in milk yield in the subsequent lactation were observed between treatments. It is concluded that oral bolus application diminishes feed intake and milk production, and, if applied at dry-off, it decreases udder pressure and increases lying time during the first 24 h after dry-off.

Changes in gene expression in the rumen and colon epithelia during the dry period through lactation of dairy cows and effects of live yeast supplementation.

The objectives of this study were (1) to use endoscopy to collect biopsies from the rumen and colon epithelia to describe changes in gene expression in these 2 tissues as cows move from a dry to a lactation ration and (2) to evaluate the potential influence that supplementation of live yeast could exert on these 2 epithelia. Twenty-one Holstein cows were split into 2 treatments and received either 300 g/d of corn containing 1 × 1010 cfu/d of live yeast (LY; n = 10) or 300 g/d of corn with no supplementation (control; n = 11) starting 21 ± 2.6 d (average ± SD) before until 21 d after calving. At 14 ± 2.6 d before the expected calving date, and exactly at 7 and 21 d after calving, rumen and colon biopsies were obtained from each cow using an endoscope. Total RNA was extracted from rumen and colon tissues, and the expression of IL10, TNFA, TLR4, IL1B, PCNA, MKI67, SGLT1, BAX, CASP3, OCLN, CLDN4, HSPA1A, HSPB1, DEFB1, and MCT1 (the latter only in rumen samples) was quantified by quantitative PCR. Overall, fluctuations in expression of the selected genes in the colon between the 2 stages of production and the 2 treatments were smaller than those found in the rumen. In the rumen epithelium, expression of TLR4 and DEFB1 was greatest before calving, with LY cows having a greater expression of TLR4 than control cows. Similarly, expression of IL10 was greatest in LY cows before calving. Expression of TNFA in the rumen epithelium of control cows was lowest at 21 DIM but in LY cows was kept steady among production stages. The expression of PCNA and MKI67 in the rumen epithelium was greatest at 7 DIM, indicating a high proliferation rate of this epithelium after calving. In the colon mucosa, expression of TLR4 and DEFB1 was greater than in the rumen, and DEFB1 expression was greater in LY cows than in control cows. The use of an endoscope allowed us to study the dynamics of rumen epithelium adaptation to increased supply of concentrate after calving, consisting of increased epithelia remodeling, reduction of the TLR4, and increased IL10 expression. Furthermore, the rumen epithelium of dry cows responded rapidly to live yeast, with changes in the expression of genes involved in the immune response becoming evident after 7 d of exposure to yeast. The expression of genes related to the immune response (mainly TLR4 and DEFB1) in the colon mucosa was greater than in the rumen, and the expression of DEFB1 was further stimulated by live yeast. It is concluded that the use of an endoscope allows the study of gene expression patterns in the rumen and hindgut epithelia. We report marked changes in the rumen wall and more modest changes in the colon when transitioning from a dry to a lactation ration. Furthermore, supplementation of live yeast fostered and increased expression of genes regulating inflammation and epithelial barrier in the rumen, and in the colon it increased the expression of DFEB1 coding for an antimicrobial peptide.

Milk performance and rumen microbiome of dairy cows as affected by the inclusion of corn silage or corn shredlage in a total mixed ration.

Corn silage (CS) is the most common forage used to feed dairy cows with inclusion rates typically around 20-40% of the diet DM. In recent years, the use of corn shredlage (SDL) has been proposed as a substitute for CS. Corn SDL is produced by a method which involves shredding the corn plant into unusually long sections and crushing the corn kernels. The objective of this study was to provide additional data on the effect of feeding SDL vs CS on milking performance and rumen microbial ecosystem. A total of 212 000 kg of whole plant were harvested on the same day and ensiled in two adjacent bunker silos of ~100,000 kg each. One silo was processed using a theoretical length of cut (LOC) of 26 mm (SDL) and other was harvested using a 16-mm LOC (CS). Both corn plants were treated at the rate of 100 ml/ton with a commercial inoculant (Magniva Platinum 1, Lallemand, France) to supply 150 000 CFU of Lactobacillus hilgardii CNCM I-4785 and 150 000 CFU of L. buchneri NCIMB 40 788 per gram of fresh material. Sixty lactating Holstein cows (648 ±â€¯66.6 kg of BW; 44.4 ±â€¯9.9 kg/d of milk yield; 155 ±â€¯75 DIM) were split into two groups and fed the same total mixed ration (15.2% CP, 30.8% NDF on a DM basis) containing either 32.7% CS or 32.7% SDL, on a DM basis, for 7 weeks. Individual feed intake and milk production and composition were monitored daily. Also, at 50 d of study (completion), a rumen sample was obtained from every cow, and DNA extracted and submitted to high-throughput sequencing to evaluate potential changes in rumen microbiota. Data were analyzed using a mixed-effects model which accounted for the fixed effects of treatment, week of study, and their two-way interaction, plus the random effect of cow. Cows on SDL had a greater DMI toward the end of the study, but milk yield and composition were not affected by dietary treatments. As result, feed efficiency was greater in cows fed CS than in those fed SDL toward the end study. There were no major changes in the relative abundances of the different microbial populations in the rumen between both groups of cows. It is concluded that SDL increases DMI of cows, but this increase is not followed by improvements in production.