Effect of supplemental concentrate during the dry period or early lactation on rumen epithelium gene and protein expression in dairy cattle during the transition period

We previously reported 2 experiments with rumen-cannulated Holstein-Friesian dairy cows showing that during the transition period, rumen papillae surface area, and fractional absorption rate of volatile fatty acids (VFA) increase after calving. However, supplemental concentrate during the dry period and rate of increase of concentrate allowance during lactation affected papillae surface area, but not VFA absorption. Here we report the changes in gene and protein expression in rumen papillae related to tissue growth and VFA utilization. The lactation experiment treatment consisted of a rapid [RAP; 1.0 kg of dry matter (DM)/d; n = 6] or gradual (GRAD; 0.25 kg of DM/d; n = 6) increase of concentrate allowance (up to 10.9 kg of DM/d), starting at 4 d postpartum (pp). The dry period experiment treatment consisted of 3.0 kg of DM/d of concentrate (n = 4) or no concentrate (n = 5) during the last 28 d of the dry period. Real-time quantitative PCR analysis of rumen papillae showed that the expression of apoptosis-related genes was neither affected by day nor its interaction with treatment for both experiments. Expression of epithelial transporter genes was not affected by day or treatment in the lactation experiment, except for NBC1. In the dry period experiment, expression of MCT1, NBC1, DRA, NHE2, NHE3, and UT-B generally decreased after calving. A day and treatment interaction was observed for ATP1A1 in the dry period experiment, with greater expression at 18 and 8 d antepartum for concentrate than no concentrate. Generally, expression of VFA metabolism-related genes was not affected by day or its interaction with treatment. In the lactation experiment, immunoblotting of 5 selected genes showed that protein expression of DRA and PCCA was greater at 16 d pp compared with 3 and 44 d pp. Expression of NHE2 was greater, and that of ATP1A1 lower, at 16 and 44 d pp compared with 3 d pp, suggesting alterations in intracellular pH regulation and sodium homeostasis. Both MCT1 and PCCA protein were upregulated by RAP from 3 to 16 d pp, indicating modulations in VFA metabolism. Our data suggests that VFA absorption and metabolic capacity changed little per unit of surface area during the transition period, and suggests that a change in mitosis rate rather than apoptosis rate is associated with the increased ruminal VFA production, resulting in tissue growth. A significant but weak correlation between the examined gene and protein expression levels was observed only for PCCA, indicating that care must be taken when interpreting results obtained at either level.     

Changes in rumen microbiota composition and in situ degradation kinetics during the dry period and early lactation as affected by rate of increase of concentrate allowance

Changes in rumen microbiota and in situ degradation kinetics were studied in 12 rumen-cannulated Holstein Friesian dairy cows during the dry period and early lactation. The effect of a rapid (RAP) or gradual (GRAD) postpartum (pp) rate of increase of concentrate allowance was also investigated. Cows were fed for ad libitum intake and had free access to a mixed ration consisting of chopped wheat straw (dry period only), grass silage, corn silage, and soybean meal. Treatment consisted of either a rapid (1.0 kg of dry matter/d; n = 6) or gradual (0.25 kg of dry matter/d; n = 6) increase of concentrate allowance (up to 10.9 kg of dry matter/d), starting at 4 d pp. In whole rumen contents, bacterial community composition was assessed using samples from 50, 30, and 10 d antepartum (ap), and 3, 9, 16, 30, 44, 60, and 80 d pp, and protozoal and archaeal community composition using samples from 10 d ap, and 16 and 44 d pp. Intake of fermentable organic matter, starch, and sugar was temporarily greater in RAP than GRAD at 16 d pp. Bacterial community richness was higher during the dry period than during the lactation. A rapid increase in concentrate allowance decreased bacterial community richness at 9 and 16 d pp compared with a gradual increase in concentrate allowance, whereas from 30 d pp onward richness of RAP and GRAD was similar. In general, the relative abundances of Bacteroidales and Aeromonadales were greater, and those of Clostridiales, Fibrobacterales, and Spirochaetales were smaller, during the lactation compared with the dry period. An interaction between treatment and sampling day was observed for some bacterial community members, and most of the protozoal and archaeal community members. Transition to lactation increased the relative abundance of Epidinium and Entodinium, but reduced the relative abundance of Ostracodinium. Archaea from genus Methanobrevibacter dominated during both the dry period and lactation. However, during lactation the abundance of the methylotrophic Methanomassiliicoccaceae and Methanosphaera increased. The in situ degradation of organic matter, neutral detergent fiber, starch, and crude protein was neither affected by treatment nor by transition from the dry period to lactation. Results show that the composition of the rumen microbiota can change quickly from the dry period to the lactation period, in particular with a rapid increase in fermentable substrate supply postpartum, but this was not associated with changes in rumen degradation kinetics.     

Effect of concentrate supplementation during the dry period on colostrum quality and effect of colostrum feeding regimen on passive transfer of immunity,calf health,and performance

The objectives were to evaluate the effect of (1) supplementing concentrates to multiparous Holstein cows during the dry period on colostral and milk immunoglobulin G (IgG) concentration; and (2) feeding calves colostrum at either 5 or 10% of their body weight (BW) on passive transfer of immunity, health, and performance. Holstein multiparous cows (n = 37) were assigned to 1 of 2 nutritional treatments during an 8-wk dry period: (1) offered ad libitum grass silage only (GS) or (2) offered ad libitum access to the same grass silage plus concentrate [total mixed ration in a 75:25 dry matter (DM) ratio], providing a mean concentrate DM intake of 3.0 kg/cow per day (GSC). Both treatment groups were offered identical levels of mineral and vitamin supplementation. Calves from these cows were weighed immediately after birth and fed either 5% (5BW) or 10% (10BW) of their BW in colostrum from their own dams within 2.5 h of birth. Calves in the 10BW group received their second feed of colostrum from first-milking colostrum. Concentrate supplementation during the dry period had no effect on colostral IgG concentration, first-milking IgG yield, or fat, protein, and lactose contents. However, cows in GSC produced a greater mean milk yield over the first 8 milkings compared with cows in the GS group. Concentrate supplementation had no effect on calf BW or BW gain, serum IgG, or apparent efficiency of absorption (AEA) at 24 h after birth. However, offspring from the GSC group had fewer cases of enteritis during the first 56 d of life compared with offspring from the GS group. Calves in the 10BW group had greater mean serum IgG concentration for the first 3 d following birth; however, at 24 h after birth, we observed no treatment effect on AEA. The rate of enteritis was greater for calves in the 5BW treatment compared with 10BW. The colostrum-feeding regimen had no effect on BW gain or on the incidence of pneumonia among calf treatment groups. In conclusion, concentrate supplementation regimens offered during the dry period had a positive effect on colostrum yield, and offspring from the GSC group had a reduced rate of enteritis. Feeding 10% of BW of colostrum versus 5% of BW resulted in a greater serum IgG concentration for the first 3 d postpartum, and 10BW calves had a reduced rate of enteritis. Overall, to achieve successful passive transfer, decrease the rate of enteritis, and increase efficiency in the dairy calf, we recommend that dairy calves be fed 10% of their BW in colostrum as soon as possible after birth.     

Effect of forage to concentrate ratio with sorghum silage as a source of forage on rumen fermentation,N balance,and purine derivative excretion in limit-fed dairy heifers

Sorghum silage has been shown to be a good alternative to corn silage for dairy cows; however, studies regarding heifers are insufficiently explored. Therefore, the objective of this study was to evaluate effects of changing forage to concentrate ratio (FOR:CON) in diets based on sorghum silage on N digestibility, rumen fermentation, N balance, C excretion, and microbial N yield in limit-fed dairy heifers. A split-plot 4 × 4 Latin square design with 19-d periods (15 d of adaptation and 4 d of sampling) was conducted with 8 rumen cannulated dairy heifers (age 13.7 ± 0.6 mo and weight 364.8 ± 17.6 kg). Heifers were fed sorghum silage–based diets with 4 FOR:CON (85:15, 75:25, 65:35, and 55:45) balanced for similar metabolizable energy intake per unit of body weight and crude protein concentration. Diets were fed to allow 900 to 1,000 g/d body weight gain and were fed once daily. Total collection of feces and urine was completed on d 15 to 19 to determine N, C, urea N, allantoin, uric acid, and creatinine excretion. Rumen contents were sampled on d 19 at 0, 1.5, 3, 4.5, 6, 9, 13, 17, 21, and 23 h after feeding to measure pH, volatile fatty acid (VFA), ammonia-N, and free AA concentrations. The pH decreased linearly while ammonia-N and free AA levels increased linearly with decreasing FOR:CON of diets. Although mean total VFA did not differ among treatment diets, molar proportions of VFA did. Acetate proportion decreased while propionate and butyrate increased with decreasing FOR:CON. Intake of N and urea N excretion decreased with decreasing forage proportion in diets while total N excretion, apparent N digestibility, and N retention were not different. Intake of C and excretion in feces (g/d) decreased linearly with decreasing FOR:CON in diets. Creatinine, allantoin, and uric acid excretion were not affected by FOR:CON; however, microbial N yield tended to increase linearly with greater concentrate in diets. Heifers limit fed diets based on sorghum silage demonstrated the effect of available ammonia-N and readily fermentable carbohydrates with subsequent effects on nutrient utilization when different FOR:CON were applied. Based on the presented results, FOR:CON 65:35 had the most suitable balance of available ammonia-N and readily fermentable carbohydrates for the most optimal results.     

Effects of Feeding Synthetic Zeolite A and Sodium Bicarbonate on Milk Production Nutrient Digestion,and Rate of Digesta Passage in Dairy Cows

Four rumen-cannulated Holstein cows were fed synthetic zeolite A and NaHCO₃ to evaluate their affect on milk production, nutrient digestibility, rumen fermentation, and rate of digesta passage. Treatments were allocated in a 2 × 2 factorial arrangement within a 4 × 4 Latin-square design. Treatments consisted of control; 1.0% NaHCO₃; 2.0% zeolite; and 1.0% NaHCO₃ plus 2.0% zeolite. A total mixed ration with 50:50 concentrate to forage (80% corn silage, 20% haylage) DM was fed.Intake of DM was lower for cows receiving zeolite (18.7 vs. 20.7 kg/d). Decreases were noted in daily milk (26.3 vs. 28.9 kg/d). 4% FCM (23.6 vs. 25.6 kg/d); milk fat yield (.86 vs. .93 kg/d); milk protein yield (.85 vs. .95 kg/d); and milk protein percent (3.21 vs. 3.34) with zeolite. Digestibilities of DM, organic matter, and crude protein were also decreased by zeolite but ADF digestion was unaffected. Rumen pH was increased, ruminal propionate decreased, and acetate:propionate ratio increased by zeolite. All other VFA plus rumen NH₃ were not affected by treatment. Decreases due to zeolite were observed in liquid fractional rate of passage and liquid flow rate when measured by Cr-EDTA in the feces. No treatment differences were found in fractional rate of passage of feed particles. Addition of NaHCO₃ had no significant effects.     

Sorghum forage in precision-fed dairy heifer diets

Sorghum forage is an alternative crop that is more adapted to drier conditions and more resistant than corn to drought conditions. Thus, sorghum forage maximizes water utilization. The objective of this study was to evaluate sorghum silage (SS), including digestibility and fermentation parameters, in precision-fed dairy heifers. Eight Holstein heifers (13.7 ± 0.6 mo of age and 364.8 ± 17.64 kg of body weight) fitted with rumen cannulas were used in a replicated 4 × 4 Latin Square design; treatments were 4 levels of forage to concentrate ratios (85:15, 75:25, 65:35, and 55:45). Rumen contents were sampled at various times to determine pH and volatile fatty acid concentrations. Dry matter (DM) and neutral detergent fiber (NDF) in situ degradation kinetics were compared between SS and corn silage (CS) diets. Fecal total collection was used to estimate apparent total-tract digestibility. Fecal grab samples at 0, 6, 12, and 18 h after feeding were used to estimate total-tract starch digestibility. Amount of concentrate in the diet affected the time that heifers spent eating as well as rumen pH. When the concentrate proportion of the diet increased, eating time and rumen pH decreased linearly. Total volatile fatty acid concentrations were not affected by treatment, but butyrate increased as the proportion of concentrate increased in the diet. Digestibility of DM and starch were higher in diets with lower forage to concentrate ratio, but NDF, acid detergent fiber, and hemicellulose digestibility were not affected. Corn silage had greater DM and NDF digestibility than SS. Also, fractional rate of digestion was faster for CS than SS (2.78 vs. 2.42% per hour, respectively). We conclude that fecal grab samples are suitable for predicting starch digestibility in heifers given the starch levels studied. In addition, SS was an adequate alternative forage in precision-fed dairy heifers with outcomes very similar to CS-based rations.     

Effects of the dose and viability of Saccharomyces cerevisiae. 1. Diversity of ruminal microbes as analyzed by Illumina MiSeq sequencing and quantitative PCR

This study was conducted to examine effects of the dose and viability of supplemental Saccharomyces cerevisiae on the ruminal fermentation and bacteria population and the performance of lactating dairy cows. Four ruminally cannulated lactating cows averaging 284 ± 18 d in milk were assigned to 4 treatments arranged in a 4 × 4 Latin square design with four 21-d periods. Cows were fed a total mixed ration containing 41.7% corn silage, 12.1% brewer’s grains, and 46.2% concentrate on a dry matter basis. The diet was supplemented with no yeast (control) or with a low dose of live yeast (5.7 × 10⁷ cfu/cow per day; LLY), a high dose of live yeast (6.0 × 10⁸ cfu/cow per day; HLY), or a high dose of killed yeast (6.0 × 10⁸ cfu/cow per day; HDY). Microbial diversity was examined by high-throughput Illumina MiSeq sequencing (Illumina Inc., San Diego, CA) of the V4 region of the 16S rRNA gene. The relative abundance of select ruminal bacteria was also quantified by quantitative PCR (qPCR). Adding LLY to the diet increased the relative abundance of some ruminal cellulolytic bacteria (Ruminococcus and Fibrobacter succinogenes) and amylolytic bacteria (Ruminobacter, Bifidobacterium, and Selenomonas ruminantium). Adding live instead of killed yeast increased the relative abundance of Ruminococcus and F. succinogenes; adding HDY increased the relative abundance of Ruminobacter, Bifidobacterium, Streptococcus bovis, and Selenomonas ruminantium. The most dominant (≥1% of total sequences) bacteria that responded to LLY addition whose functions are among the least understood in relation to the mode of action of yeast include Paraprevotellaceae, CF231, Treponema, and Lachnospiraceae. Future studies should aim to speciate, culture, and examine the function of these bacteria to better understand their roles in the mode of action of yeast. A relatively precise relationship was detected between the relative abundance of F. succinogenes (R² = 0.67) from qPCR and MiSeq sequencing, but weak relationships were detected for Megasphaera elsdenii, Ruminococcus flavefaciens, and S. ruminantium (R² ≤ 0.19).     

Overstocking dairy cows during the dry period affects dehydroepiandrosterone and cortisol secretion

Stressful situations trigger several changes such as the secretion of cortisol and dehydroepiandrosterone (DHEA) from the adrenal cortex, in response to ACTH. The aim of this study was to verify whether overstocking during the dry period (from 21 ± 3 d to the expected calving until calving) affects DHEA and cortisol secretion and behavior in Holstein Friesian cows. Twenty-eight cows were randomly divided into 2 groups (14 animals each), balanced for the number of lactations, body condition score, and expected date of calving. Cows in the far-off phase of the dry period (from 60 to 21 d before the expected calving date) were housed together in a bedded pack. Then, animals from 21 ± 3 d before the expected calving until calving were housed in pens with the same size but under different crowding conditions due to the introduction of heifers (interference animals) into the pen. The control condition (CTR) had 2 animals per pen with 12.0 m² each, whereas the overstocked condition (OS) had 3 interference animals in the same pen with 4.8 m² for each animal. On d ?30 ± 3, ?21 ± 3, ?15 ± 3, ?10 ± 3, and ?5 ± 3 before and 10, 20, and 30 after calving, blood samples were collected from each cow for the determination of plasma DHEA and cortisol concentrations by RIA. Rumination time (min/d), activity (steps/h), lying time (min/d), and lying bouts (bouts/d) were individually recorded daily. In both groups, DHEA increased before calving and the concentration declined rapidly after parturition. Overstocking significantly increased DHEA concentration compared with the CTR group at d ?10 (1.79 ± 0.09 vs. 1.24 ± 0.14 pmol/mL), whereas an increase of cortisol was observed at d ?15 (3.64 ± 0.52 vs. 1.64 ± 0.46 ng/mL). The OS group showed significantly higher activity (steps/h) compared with the CTR group. Daily lying bouts tended to be higher for the OS group compared with CTR group in the first week of treatment. The overall results of this study documented that overstocking during the dry period was associated with a short-term changes in DHEA and cortisol but these hormonal modifications did not influence cow behavior.     

No Associative Effects Between Corn and Haycrop Silages Fed to Lactating Dairy Cows

Four first-lactation Holstein cows were used 65 to 177 days postpartum in a 4 × 4 Latin square trial to evaluate possible associative feeding effects between corn and haycrop silages. Nutrient digestibility and nitrogen and energy balances were studied. Diets were concentrate mixture, urea-treated corn silage, and early-cut, wilted haycrop silage in dry matter ratios of 55:45:0, 55:30:15, 55:15:30, and 55:0:45. Rations were offered just below energy balance in each 28-day period. Ration components were fed separately, concurrently, and twice daily. Crude protein in concentrate, corn silage, and hay crop silage dry matter was 16.9, 11.1, and 12.5%. Milk yield (18 to 19 kg) and ration dry matter intake (2.61% body weight) were not significantly different among diets. Apparent digestibility of gross energy, dry matter, protein, and fiber was not different among diets, but fat was more digestible in corn silage. Partition of ingested energy and nitrogen was not affected by treatments except that urine nitrogen was higher in corn silage. No associative feeding effects were significant. The two silages were equivalent in supporting milk production when fed in equal dry matter amounts.     

Response of High Producing Dairy Cows in Early Lactation to the Feeding of Heat-Treated Whole Soybeans

Fifty-eight multiparous cows were assigned randomly to one of two rations. Control cows received a concentrate mixture that contained 20% soybean meal as the protein supplement, and the experimental cows were fed a concentrate that contained 25% heat-treated whole soybeans. The experimental period started 10 d after calving and continued for 15 wk.Experimental cows peaked later in milk production (5 vs. 3 wk) but at a higher level (39.8 vs. 39.4 kg/d) than control cows. Although milk production was less during the first 4 wk, experimental cows surpassed the controls in wk 5 and increased the advantage to 2.0 kg/cow/d by wk 15. For the total 15-wk period, average milk production was 37.0 kg/d for the experimental cows compared with 36.2 kg/d for the controls.Total dry matter intake, lactation efficiency, body weight, and reproductive performance were similar for both treatments. Cows fed heated soybeans consumed more metabolizable energy, 61.6 vs. 60.4 Mcal/d for controls. Cows on experimental diet also had higher free fatty acids in plasma (5.6 vs. 4.8 mg/100 ml) and triglycerides (25.0 vs. 20.9 mg/100 ml). The acetate-to-propionate ratio of rumen acids was significantly lower in the experimental group (3.36 vs. 3.61).     

Effect of incremental amounts of camelina oil on milk fatty acid composition in lactating cows fed diets based on a mixture of grass and red clover silage and concentrates containing camelina expeller

Camelina is an ancient oilseed crop that produces an oil rich in cis-9,cis-12 18:2 (linoleic acid, LA) and cis-9,cis-12,cis-15 18:3 (α-linolenic acid, ALA); however, reports on the use of camelina oil (CO) for ruminants are limited. The present study investigated the effects of incremental CO supplementation on animal performance, milk fatty acid (FA) composition, and milk sensory quality. Eight Finnish Ayrshire cows (91 d in milk) were used in replicated 4 × 4 Latin squares with 21-d periods. Treatments comprised 4 concentrates (12 kg/d on an air-dry basis) based on cereals and camelina expeller containing 0 (control), 2, 4, or 6% CO on an air-dry basis. Cows were offered a mixture of grass and red clover silage (RCS; 1:1 on a dry matter basis) ad libitum. Incremental CO supplementation linearly decreased silage and total dry matter intake, and linearly increased LA, ALA, and total FA intake. Treatments had no effect on whole-tract apparent organic matter or fiber digestibility and did not have a major influence on rumen fermentation. Supplements of CO quadratically decreased daily milk and lactose yields and linearly decreased milk protein yield and milk taste panel score from 4.2 to 3.6 [on a scale of 1 (poor) to 5 (excellent)], without altering milk fat yield. Inclusion of CO linearly decreased the proportions of saturated FA synthesized de novo (4:0 to 16:0), without altering milk fat 18:0, cis-9 18:1, LA, and ALA concentrations. Milk fat 18:0 was low (<5 g/100 g of FA) across all treatments. Increases in CO linearly decreased the proportions of total saturates from 58 to 45 g/100 g of FA and linearly enriched trans-11 18:1, cis-9,trans-11 18:2, and trans-11,cis-15 18:2 from 5.2, 2.6, and 1.7 to 11, 4.3, and 5.8 g/100 g of FA, respectively. Furthermore, CO quadratically decreased milk fat trans-10 18:1 and linearly decreased trans-10,cis-12 18:2 concentration. Overall, milk FA composition on all treatments suggested that one or more components in camelina seeds may inhibit the complete reduction of 18-carbon unsaturates in the rumen. In conclusion, CO decreased the secretion of saturated FA in milk and increased those of the trans-11 biohydrogenation pathway or their desaturation products. Despite increasing the intake of 18-carbon unsaturated FA, CO had no effect on the secretions of 18:0, cis-9 18:1, LA, or ALA in milk. Concentrates containing camelina expeller and 2% CO could be used for the commercial production of low-saturated milk from grass- and RCS-based diets without major adverse effects on animal performance.     

Effect of a dual-purpose inoculant on the quality and nutrient losses from corn silage produced in farm-scale silos

This project aimed to determine effects of applying an inoculant containing homofermentative and heterofermentative bacteria on the fermentation, nutritive value, aerobic stability, and nutrient losses from corn silage produced in farm-scale silos. Corn forage was harvested at 34% dry matter (DM) and treated without (control) or with 5 × 10⁵ cfu/g of Lactobacillus buchneri and Pediococcus pentosaceus. The inoculant was sprayed on alternate 8-row-wide swaths of forage, and the untreated and inoculated forages were alternately packed into 3.6-m-wide bag silos. Forty-five tonnes of corn forage were packed into each of 4 replicate bags per treatment and ensiled for 166 d. Silage removed from the bags (500 kg/d) was separated into good and spoiled (visibly moldy or darker) silage portions, and weighed for 35 d. Weekly composites were analyzed for chemical composition, aerobic stability, and fungal counts. Aerobic stability was measured using data loggers that recorded sample and ambient temperature every 30 min for 7 d. Inoculation did not affect the chemical composition of the spoiled or good silage but decreased the quantity (5.7 vs. 12.9 kg/d) and percentage (3.4 vs. 7.8) of spoiled silage in the bags by over 50%. Losses of crude protein (0.28 vs. 0.92 kg/d), gross energy (6.0 × 10⁴ vs. 1.8 × 10⁵ kJ/d), and neutral detergent fiber (1.34 vs. 4.12 kg/d) in spoiled silage were less in inoculated versus control silages. Inoculated silages had lower pH (3.91 vs. 3.99), lactate concentration (7.63 vs. 7.86%), lactate:acetate ratio (1.58 vs. 2.53%), and a greater acetate (5.11 vs. 3.56%) concentration than the control silage. Inoculated silages tended to have fewer yeasts (2.59 vs. 4.62 log cfu/g) than control silages, but aerobic stability was not different across treatments (14.7 vs. 9.5 h). Applying the inoculant made the fermentation more heterolactic, inhibited the growth of yeasts, and substantially reduced the amount of spoilage and the associated energy and nutrient losses.     

Effect of Ration Protein Content and Solubility on Milk Production of Primiparous Holstein Heifers

Twenty-eight primiparous heifers were blocked at calving and assigned to four dietary treatments in a 2 × 2 factorial arrangement of two crude protein concentrations (15.4 and 20.7%) and two protein solubilities (22.8 and 53% of protein). Heat-treated soybeans replaced raw soybeans in low solubility rations. Rations were offered for the first 10 wk of lactation divided into two 5-wk periods. Feed was offered ad libitum in period 1 and restricted in period 2. Digestibility and N balance were measured at completion of the lactation study. Body weight change, DM intake, milk yield, milk protein percentage, rumen pH, and total VFA were not affected by treatments. Milk fat percentage was increased by higher CP content during period 1, resulting in a 16.2% increase in 4% FCM. Plasma urea N and rumen NH₃ were elevated by higher CP content. Reducing protein solubility depressed rumen NH₃. A protein × solubility interaction for the acetate to propionate ratio suggests that protein and solubility combinations that optimized plasma urea N and rumen NH₃ provided a more favorable rumen environment and supported highest milk production. Nitrogen digestibility was influenced most by ration CP; however, lower solubility improved DM and N digestibilities. Both dietary CP content and solubility must be considered to maintain optimum rumen environment.     

Effect of dietary inclusion of winter brassica crops on milk production,feeding behavior,rumen fermentation,and plasma fatty acid profile in dairy cows

This study determined feeding behavior, dry matter (DM) intake (DMI), rumen fermentation, and milk production responses of lactating dairy cows fed with kale (Brassica oleracea) or swede (Brassica napus ssp. napobrassica). Twelve multiparous lactating dairy cows (560 ± 22 kg of body weight, 30 ± 4 kg of milk/d, and 60 ± 11 d in milk at the beginning of the experiment; mean ± standard deviation) were randomly allocated to 3 dietary treatments in a replicated 3 × 3 Latin square design. The control diet comprised 10 kg of grass silage DM/d, 4 kg of ryegrass herbage DM/d, and 8.8 kg of concentrate DM/d. Then, 25% of herbage, silage, and concentrate (DM basis) was replaced with either kale or swede. Cows offered kale had decreased total DMI compared with cows fed the control and swede diets, whereas inclusion of swede increased eating time. Milk production, composition, and energy-corrected milk:DMI ratio were not affected. Cows fed with kale had a greater rumen acetate:propionate ratio, whereas swede inclusion increased the relative percentage of butyrate. Estimated microbial N was not affected by dietary treatments, but N excretion was reduced with inclusion of kale, improving N utilization. Cows fed kale tended to have increased nonesterified fatty acids and showed presence of Heinz-Ehrlich bodies, whereas hepatic enzymes such as aspartate aminotransferase, γ-glutamyl transferase, and glutamate dehydrogenase were not affected by dietary treatments. In plasma, compared with the control, swede and kale reduced total saturated fatty acids and increased total polyunsaturated fatty acids and total n-3 fatty acids. Overall, feeding cows with winter brassicas had no negative effect on production responses. However, mechanisms to maintain milk production were different. Inclusion of swede increased the time spent eating and maintained DMI with a greater relative rumen percentage of butyrate and propionate, whereas kale reduced DMI but increased triacylglycerides mobilization, which can negatively affect reproductive performance. Thus, the inclusion of swede may be more suitable for feeding early-lactating dairy cows during winter.     

Nitrogen utilization,preweaning nutrient digestibility,and growth effects of Holstein dairy calves fed 2 amounts of a moderately high protein or conventional milk replacer

Studies have shown that calves fed milk replacers (MR) with crude protein (CP) concentrations greater than 20%, as typically found in conventional MR, have higher dry matter intakes (DMI) and greater average daily gains (ADG) but consume less starter, which can lead to stress during weaning and reduced rumen development. The greater amount of CP being fed to preweaned calves may alter their nitrogen (N) balance, and excess N may be excreted in the urine. The objective of this study was to determine N utilization in preweaned calves fed diets varying in the amount of CP and MR fed. This study used 24 newborn dairy heifer calves blocked by birth and randomly assigned to 1 of 3 treatments: (1) 446 g dry matter (DM) of a conventional MR (CON; 20% CP, 20% fat), (2) 669 g DM of a moderately high protein MR (moderate; MOD; 26% CP, 18% fat), or (3) 892 g DM of a moderately high protein MR (aggressive; AGG; 26% CP, 18% fat). All calves had ad libitum access to starter and water. Both MR and starter were medicated with decoquinate. During weaning (d 43–49), the morning MR feeding ceased. On d 50, all MR feedings ended; however, starter and water intakes were continuously recorded until d 56. At 5 wk of age, urine was collected using urinary catheters for 3 d and chromium oxide was administered by bolus at 2 g/d for 7 d to estimate N efficiency. Calves fed MOD and AGG had similar starter intakes, feed efficiencies, and ADG, with the combined treatments having reduced starter intakes (258 vs. 537 g/d), greater ADG (674 vs. 422 g/d), and improved feed efficiency (0.57 vs. 0.45 gain:feed) compared with CON calves preweaning. However, DMI and water intake were similar across all treatments. Results from the N utilization phase showed that MOD and AGG treatments had similar but lower N efficiency compared with CON calves (45.5 vs. 52.7%). This could be due to MOD- and AGG-fed calves having greater urine volume and thereby, greater combined urine N output compared with CON calves (17.6 vs. 12.1 g/d). In summary, feeding >0.66 kg (DM) from a 26% CP MR increased ADG and improved feed efficiency during the preweaning period but reduced starter intake and lowered N efficiency.     

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.     

Chewing activities and particle size of rumen digesta and feces of precision-fed dairy heifers fed different forage levels with increasing levels of distillers grains

The objective of this study was to determine the effects of 2 differing forage to concentrate ratios (F:C) and various levels of corn dry distillers grain with solubles (DDGS) replacing canola meal in precision-fed dairy heifer rations on chewing behavior, rumen pH and fill, and particle size of rumen contents and feces. A split plot design with F:C as whole plot and DDGS inclusion level as subplot was administered in a 4-period 4 × 4 Latin square. Eight rumen-cannulated Holstein heifers (12.5 ± 0.5 mo of age and 344 ± 15 kg of body weight, respectively) housed in individual stalls were allocated to F:C 50:50 (low forage) or 75:25 [high forage (HF); dry matter basis] and to a sequence of DDGS level (0, 7, 14, and 21%; dry matter basis). Forage was a mix of 50% corn silage and 50% grass hay (dry matter basis). Diets were fed once daily and formulated to provide equal amounts of nutrients and body weight gain. No differences were found for rumen pH between dietary treatments. Time spent eating tended to be longer for HF and was not affected by DDGS inclusion rate. Ruminating time did not differ by F:C, but linearly increased as DDGS increased (422 to 450 ± 21 min/d). Total chewing time tended to be longer for HF and to increase linearly as DDGS increased (553 to 579 ± 33 min/d). Wet rumen digesta weight and volume were greater for HF. Geometric mean particle length of rumen contents was greater for HF 2 h prefeeding when analyzed with solubles (particles <0.15 mm). Proportion of rumen solubles decreased as DDGS increased 5 h postfeeding. Fecal geometric mean particle length and proportion of particles >1.18 mm increased with increasing levels of DDGS and did not change with F:C. Total chewing time increased by the addition of DDGS and higher F:C. Heifers can compensate for lower physically effective neutral detergent fiber by modifying their chewing behavior. Rumen pH was never at a level that could induce acidosis, and lower eating time at lower F:C was somewhat compensated by time spent ruminating per unit of physically effective neutral detergent fiber intake. Dry distillers grains with solubles, when used in dairy heifer rations as a replacement for canola meal, yielded similar rumen digestion traits.     

Changes in rumen fermentation and bacterial community in lactating dairy cows with subacute rumen acidosis following rumen content transplantation

Rumen microbiota intervention has long been used to cure ruminal indigestion in production and has recently become a research hotspot. However, how it controls the remodeling of rumen bacterial homeostasis and the restoration of rumen fermentation in cows of subacute ruminal acidosis (SARA) remains poorly understood. This study explored changes in rumen fermentation and bacterial communities in SARA cows following rumen content transplantation (RCT). The entire experiment comprised 2 periods: the SARA induction period and the RCT period. During the SARA induction period, 12 ruminally cannulated lactating Holstein cows were selected and allocated into 2 groups at random, fed either a conventional diet [CON; n = 4; 40% concentrate, dry matter (DM) basis] or a high-grain diet (HG; n = 8; 60% concentrate, DM basis). After the SARA induction period, the RCT period began. The HG cows were randomly divided into 2 groups: the donor-recipient (DR) group and the self-recipient (SR) group, and their rumen contents were removed completely before RCT. For the DR group, cows received 70% rumen content from the CON cows, paired based on comparable body weight; for the SR group, each cow received 70% rumen content, self-derived. The results showed that nearly all rumen fermentation parameters returned to the normal levels that the cows had before SARA induction after 6 d of transplantation, regardless of RCT. The concentrations of acetate, valerate, and total volatile fatty acids (VFA) were not recovered in the SR cows, whereas all of them were recovered in the DR cows. The amplicon sequencing results indicated that both the SR and DR cows rebuild their rumen bacterial homeostasis quickly within 4 d after RCT, and the DR group showed a higher level of bacterial community diversity. At the genus level, the DR cows displayed an improved proportion of unclassified Ruminococcaceae and Saccharofermentans compared with the SR cows. Correlation analysis between the rumen bacteria and rumen fermentation suggested some potential relationships between the predominant transplantation-sensitive operational taxonomic units and VFA. Co-occurrence network analysis revealed that RCT affected only those rumen bacterial taxa that showed weak interactions with other taxa and did not affect the pivotal rumen bacteria with high levels of co-occurrence. Our findings indicate that RCT contributes to the restoration of rumen bacterial homeostasis and rumen fermentation in cows suffering from SARA without affecting the core microbiome.     

A query for effective mean particle size in dry and high-moisture corns

The objective of this study was to investigate whether prediction of fermentation potential (FP) of dry and high-moisture (HM) corns could be improved by using a concept of effective (e) mean particle size (MPS). A set of FP standards was created by processing a single lot of Reid Yellow Dent (RYD) corn to achieve MPS of 3,778, 2,786, 2,282, 1,808, 1,410, 806, 586, 378, 308, 226, and 105 μm. In vitro gas production of RYD standards was measured, and peak absolute rate (PAR) of gas production (mL/0.2 g of DM/h) was used to establish a standard relationship between PAR and MPS. To identify factors other than MPS affecting FP, the MPS and nutrient composition of 36 diverse samples of dry (n = 18) and HM (n = 18) corns were determined. Composition included dry matter (DM), crude protein, soluble crude protein, neutral detergent fiber, starch, NH₃-N, prolamin protein, and fat. In vitro gas production of undried, unground dry and HM corns was measured, and PAR, time of peak absolute rate (h), maximum cumulative gas production (mL/0.2 g of DM), gas production fractional rate (h^?1), and lag (h) were determined. Nonlinear relationships between MPS, defined as the dependent variable, and PAR, as an independent variable, were used to identify FP deviations unexplained by MPS. When no variation in nutritional composition was present (RYD standards), the relationship between PAR and MPS was described by an exponential decay model [RYD_MPS = 9,006 × e^{(?0.452×PAR)}; R² = 0.96]. For diverse dry and HM corn populations, the variation in MPS explained by PAR was diminished (R² = 0.50). To investigate factors that diminish the relationship between MPS and PAR in diverse corns, relative residual (rr) MPS was determined [rrMPS = (MPS – RYD_MPS)/MPS], where RYD_MPS was predicted from the PAR of diverse dry and HM corn. The rrMPS was most highly related to prolamin protein [rrMPS_dry = 0.58 ? 0.15 × (prolamin protein, % of DM); R² = 0.43] and NH₃-N [rrMPS_HM = 0.21 + 0.08 × (NH₃-N, % of total N); R² = 0.46] for dry and HM corns, respectively. An eMPS was calculated as eMPS = MPS – MPS × rrMPS, where rrMPS was predicted from prolamin protein or NH₃-N concentration in dry and HM corn, respectively. The natural logarithm of eMPS accounted for 84% of the variability in PAR and 53% of the variability in the fractional rate of gas production. Calculating eMPS by adjusting the MPS of dry corn for prolamin and HM corn for NH₃-N concentration improved the assessment of industry corn FP.     

Short communication: Comparison of pH,volatile fatty acids,and microbiome of rumen samples from preweaned calves obtained via cannula or stomach tube

The objective of this study was to compare rumen samples from young dairy calves obtained via a stomach tube (ST) or a ruminal cannula (RC). Five male Holstein calves (46 ± 4.0 kg of body weight and 11 ± 4.9 d of age) were ruminally cannulated at 15 d of age. Calves received 4 L/d of a commercial milk replacer (25% crude protein and 19.2% fat) at 12.5% dry matter, and were provided concentrate and chopped oats hay ad libitum throughout the study (56 d). In total, 29 paired rumen samples were obtained weekly throughout the study in most of the calves by each extraction method. These samples were used to determine pH and volatile fatty acids (VFA) concentration, and to quantify Prevotella ruminicola and Streptococcus bovis by quantitative PCR. Furthermore, a denaturing gradient gel electrophoresis was performed on rumen samples harvested during wk 8 of the study to determine the degree of similarity between rumen bacteria communities. Rumen pH was 0.30 units greater in ST compared with RC samples. Furthermore, total VFA concentrations were greater in RC than in ST samples. However, when analyzing the proportion of each VFA by ANOVA, no differences were found between the sampling methods. The quantification of S. bovis and P. ruminicola was similar in both extraction methods, and values obtained using different methods were highly correlated (R² = 0.89 and 0.98 for S. bovis and P. ruminicola, respectively). Fingerprinting analysis showed similar bacteria band profiles between samples obtained from the same calves using different extraction methods. In conclusion, when comparing rumen parameters obtained using different sampling techniques, it is recommended that VFA profiles be used rather than total VFA concentrations, as total VFA concentrations are more affected by the method of collection. Furthermore, although comparisons of pH across studies should be avoided when samples are not obtained using the same sampling method, the comparison of fingerprinting of a bacteria community or a specific rumen bacterium is valid.