Relationships between dietary and cow factors with the fecal phosphorus contents of dairy cows in Manitoba

A survey was carried out on 19 dairy farms in Manitoba that varied in size, diet composition, housing, and feeding strategy to identify factors that affect the phosphorus (P) content of feces. On each farm, 10 early, 10 mid, and 10 late lactation cows were included. Multiple regression analysis showed that high dietary P concentrations and free-stall instead of tie-stall housing were mostly associated with high P contents of feces. Hence, a closer matching of the requirements and supply of P of dairy cows enhances the utilization of dietary P on these farms.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Comparisons of methods for in vitro dry matter digestibility of ruminant feeds

Apparent in vitro dry matter digestibilities of selected ruminant feeds were determined with the DAISYII incubator (ADD, ANKOM Technology Corp., Macedon, NY) and the Tilley and Terry technique (ADTT). True in vitro dry matter digestibility was also determined with the DAISYII incubator (TDD). The ADD and ADTT did not differ for grain crop silages and total mixed rations. The ADD was 9.0 percentage points higher than ADTT for grains and 3.4 percentage points lower than ADTT for grass and legume forages. The TDD was between 5.7 and 11.2 percentage points higher than ADD depending on the fee

Effects of the dietary grain content on rumen and fecal microbiota of dairy cows

Six non-lactating Holstein dairy cows received diets with forage to grain mixture ratios of 100:0 (G0), 75:25 (G25), and 50:50 (G50) that contained 0.5, 10.0, and 19.5 % DM of starch, respectively. Rumen fluid and feces were sampled and methane emissions were determined during the last week of 5 wk experimental periods. Taxonomic compositions of microbiota were determined using Illumina s16S rRNA sequencing. Increased grain feeding increased the acidity and VFA concentrations of rumen fluid and feces, and decreased methane emissions expressed as L/kg DM. Microbial diversities were highest for G25. The numbers of identified genera in rumen fluid were 185, 182, and 171 for G0, G25, and G50, respectively. In feces, these numbers were 197, 182, and 171 for these diets respectively. In rumen digesta, 7 genera were correlated positively to G0 and negatively to G50, and 6 genera were correlated negatively to G0 and positively to G50. In feces, 16 genera were correlated positively to G0 and negatively to G50, and 13 genera were correlated negatively to G0 and positively to G50. Increasing grain feeding affected a limited number of genera in rumen digesta and feces. This could not explain treatment effects on the functionalities of microbiota.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Free endotoxins in the feces of lactating dairy cows

A survey was conducted on 300 lactating dairy cows on 10 dairy farms to determine how risk factors for and symptoms of excessive grain feeding and subacute ruminal acidosis are associated with the concentrations of endotoxins in feces measured with the Limulus amoebocyte lysate test. Increases in days in milk and haptoglobin in blood plasma were associated with lower (P = 0.02) and higher (P = 0.02) fecal endotoxin, respectively. The five farms with a dietary neutral detergent fibre (NDF) content higher than 33.8% of DM had lower (P < 0.01) fecal endotoxin than those with a dietary NDF content lower than 33.8% of DM (31 790 vs. 69 276 endotoxin units (EU) g-1 of wet feces, P < 0.01). Parity, milk yield, milk fat percentage, milk protein percentage, the blood plasma concentration of serum amyloid A, and the dietary content of physically effective fibre were not associated with the fecal endotoxin concentration

Evaluation of the systemic innate immune response and metabolic alterations of nonlactating cows with diet-induced subacute ruminal acidosis

Subacute ruminal acidosis (SARA) increases lipopolysaccharide endotoxin in the rumen, which might translocate into the systemic circulation, triggering a cascade of clinical and immunological alterations. The objective of this study was to characterize the clinical immune and metabolic responses to ruminal-derived lipopolysaccharide in nonlactating cows induced with SARA using 2 challenges, a grain-based SARA challenge (GBSC) or an alfalfa-pellet SARA challenge (APSC). Six dry, nonlactating Holstein cows were used in a 3 × 3 Latin square arrangement of treatments with 4-wk experimental cycles. All cows received the control diet containing 70% forage and 30% mixed concentrates (dry matter basis) for 3 wk. In wk 4, cows received a control diet, GBSC (38% wheat-barley pellets, 32% other mixed concentrate, and 30% forages), or APSC (45% mixed concentrate, 32% alfalfa pellets, and 23% other forages). Total plasma proteins and immunology-related proteins, acute phase proteins, blood cells, serum chemistry, mRNA gene expression of peripheral blood cell surface markers, and selected proinflammatory cytokines were evaluated. Ruminal pH was lower in both groups with induced SARA compared with a control group. Ruminal endotoxins were higher in GBSC; however, plasma endotoxin was not detected in any study group. No significant differences in feed intake, rectal temperature, white blood cell counts, or differentials were found between control and SARA challenge groups; changes in glucose, urea, Ca, and Mg were observed in SARA groups. Total plasma proteins were lower in both SARA groups, and acute phase proteins were higher in GBSC. The expression of CD14, MD2, and TLR4 mRNA in peripheral blood leukocytes was not affected by SARA induction. The induction of SARA as a result of GBSC or APSC challenge was successful; however, LPS was not detected in plasma. Changes in clinical, metabolic, and inflammatory responses were not observed in the SARA-challenged cows, suggesting that, in this study, SARA was not associated with a systemic response to inflammation

Effects of Saccharomyces cerevisiae fermentation products and subacute ruminal acidosis on feed intake, fermentation, and nutrient digestibilities in lactating dairy cows

Effects of Saccharomyces cerevisiae fermentation products (SCFP) and subacute ruminal acidosis (SARA) on rumen and hindgut fermentation, feed intake, and total tract nutrient digestibilities were determined in 32 lactating Holstein cows between weeks 4 and 9 of lactation. Treatments included control, 14 g·d−1 Diamond V Original XPC™ (SCFPa; Diamond V, Cedar Rapids, IA, USA), 19 g·d−1 NutriTek® (SCFPb-1X; Diamond V), and 38 g·d−1 NutriTek® (SCFPb-2X; Diamond V). During weeks 5 and 8, SARA challenges were conducted by switching from a 18.6% to a 27.9% dry matter (DM) starch diet. This reduced the rumen and feces pH. The durations of the rumen pH below 5.6 during these challenges averaged 175.0, 233.8, 246.9, and 79.3 min·d−1 for the control, SCFPa, SCFPb-1X, and SCFPb-2X treatments, respectively. Hence, SARA was not induced under the SCFPb-2X treatment. The feces pH during the SARA challenges was lowest during SCFPb-2X, suggesting this treatment shifted fermentation from the rumen to the hindgut. The SARA challenges reduced the total tract digestibility of DM, neutral detergent fiber digestibility (NDFd), and phosphorus, but tended to increase that of starch. The SCFPb-2X treatment increased the NDFd from 52.7% to 61.8% (P < 0.05). The SCFPb-2X treatment attenuated impacts of SARA.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

The effects of supplementing Napier grass (Pennisetum purpureum) with rock phosphate and steamed bone meal compared with a commercial mineral mix on phosphorus absorption in cattle

Twelve Boran steers with a mean live weight of 215.8 ± 13.9 kg were used in an incomplete Latin Square experiment to compare the apparent phosphorus (P) absorption in cattle when Napier grass (Pennisetum purpureum) was supplemented with Busumbu rock phosphate (BRP), Minjingu rock phosphate (MRP), steamed bone meal (SBM) or a commercial mineral mix (CMM). The steers were housed individually and supplemented with P at 0, 4.5 or 17.5 g P/day. Dry matter intake (DMI) and dry matter digestibility (DMD) were not affected (p > 0.05) by the source of Live weight gains (LWG) were different (p 0.05) across periods. The level of P supplementation had no significant effect (p>0.05) on DMI or LWG. However, increasing the level of P supplementation significantly increased (p 0.05) different from each other. These results suggest that BRP has potential as a source of P for ruminants