Effects of dietary energy density and feeding strategy during the dry period on feed intake, energy balance, milk production, and blood metabolites of Holstein cows.

Our study aimed to assess the effects of dietary energy density and strategy of delivery during the dry period on production and metabolic responses of Holstein cows free of displacement of abomasum, retained placenta, metritis, or hypocalcemia. Twenty-seven multiparous cows dried-off 50 d before calving were assigned randomly to 1 of 3 dietary treatments: a controlled energy, high-fiber diet [CE; 1.39 Mcal net energy for lactation (NEL)/kg of dry matter (DM)] formulated to supply 100% of the NEL requirement at ad libitum intake; or a higher energy diet (1.58 Mcal/kg) fed either at ad libitum (HE) or restricted (RE) intake to supply ∼150 or 80% of the NEL requirements, respectively. After calving, all cows were fed the same lactation diet. Cows were individually fed and remained in the study until 28 d postpartum. Data were analyzed using 2 contrasts: CE versus HE (effect of diet composition in cows fed for ad libitum DM intake) and HE versus RE (effect of ad libitum or restricted intake of the same diet). Prepartum intakes of DM and NEL as well as energy balance (EB), were greater for HE than CE and greater for HE than RE. Body weight (BW) gain was higher in HE than in RE, but CE and HE did not differ. Change in body condition score did not differ between CE and HE or HE and RE. Postpartum intakes of DM and NEL, EB, BW, body condition score, calf birth BW, milk yield, and milk components did not differ between CE and HE or HE and RE. Concentrations of glucose, insulin, nonesterified fatty acids, ß-hydroxybutyrate, Ca, and Mg pre- and postpartum did not differ among diets. Although sample size was low, dry period plane of energy intake affected prepartum DM intake, EB, and BW gain but did not affect postpartum intakes of DM and NEL, yields of milk and milk components, or blood metabolites in healthy cows.

Effects of physical preparation of diets and inclusion rate of modified wet distillers grains with solubles on production and rumen measurements of lactating dairy cows.

Our objective was to determine if methods for preparing total mixed ration [TMR; horizontal paddle mixer with knives (PK) vs. vertical auger (VA) mixer] would alter the physical form of the TMR and affect utilization of diets with increasing amounts of modified wet distillers grains with solubles (MWDGS). Holstein cows (n = 24 with 12 ruminally cannulated; 144 d in milk ± 31 d at start) were used in a split-plot design with mixer type as the whole plot and MWDGS concentrations as subplots in a replicated 3 × 3 Latin square arrangement with 35-d periods. Inclusion rates of MWDGS were 10, 20, and 30% of dietary dry matter, primarily replacing corn, soybean meal, soyhulls, and whole cottonseed. Feed dry matter intake (DMI) was less for PK (23.8 kg/d) than for VA (25.7 kg/d), but was unaffected by MWDGS concentration. Milk production did not differ by concentration of MWDGS or by interaction of MWDGS × mixer. Milk fat percentage declined with increasing MWDGS but the interaction between mixer and MWDGS showed that decreases were larger with VA mixing. Cows fed the diet containing 30% MWDGS mixed with PK averaged 3.45% (1.24 kg/d) milk fat, whereas cows fed the same diet mixed with VA averaged 2.81% (1.10 kg/d) fat. Concentrations of trans-10,cis-12 C18:2 in milk fat likely explain the differences observed in milk fat yield; the concentration of trans-10,cis-12 C18:2 increased as MWDGS was increased and the MWDGS × mixer interaction showed that VA had greater concentrations. Greater mean particle size and increased variation in particle size with VA may partially explain differences in milk fat via increased sorting that allowed for an altered rumen environment and favored alternative biohydrogenation pathways. Feed conversion efficiency (FCE; energy-corrected milk/DMI) decreased linearly as MWDGS increased, but FCE tended to be maintained when higher MWDGS diets were mixed using PK rather than VA. Ruminal pH and ammonia concentration decreased linearly as MWDGS increased. The PK mixer resulted in greater FCE when higher amounts of MWDGS were fed, primarily because milk fat content and yield were not as depressed and DMI was lower at similar milk yields.

Effects of rumen-protected methionine on lactation performance and physiological variables during a heat stress challenge in lactating Holstein cows.

Milk yield, content, and composition are altered by heat stress. Thirty-two multiparous, lactating Holstein cows [balanced by days in milk (mean ± standard deviation; 184 ± 59); body surface area (5.84 ± 0.34 m2)] were randomly assigned to 1 of 2 dietary treatments [total mixed ration with rumen-protected Met (RPM; Smartamine M; Adisseo Inc., Antony, France; 1.05 g of RPM/kg of dry matter intake) or total mixed ration without RPM (CON)], and within each dietary treatment group cows were randomly assigned to 1 of 2 environmental treatment groups in a split-plot crossover design. The study was divided into 2 periods with 2 phases per period. In phase 1 (9 d), all cows were in thermoneutral conditions and fed ad libitum. In phase 2 (9 d), group 1 (n = 16) was exposed to a heat stress challenge (HSC) using electric heat blankets. Group 2 (n = 16) remained in thermoneutral conditions but was pair-fed (PFTN) to HSC counterparts. After a 21-d washout period, the study was repeated (period 2) and the environmental treatments were inverted relative to treatments from phase 2 of period 1, whereas dietary treatments (RPM or CON) remained the same for each cow. Cows were milked 3× per day and samples were taken on d 1, 5, and 9 of each phase. Vaginal temperature was measured every 10 min, rectal temperature and skin temperature were measured 3× per day, and respiration rate and heart rate were recorded once per day. Cow activity was measured using an accelerometer. Paired difference values were calculated for each cow for each period based on the difference between phase 1 baseline means and phase 2 values for each variable. Cows in HSC had a greater increase in vaginal temperature and respiration rate (+0.2°C and +13.7 breaths/min, respectively) compared with cows in PFTN (0.0°C and -1.6 breaths/min, respectively). Cows in PFTN had a greater decrease in dry matter intake and milk yield (-3.9 and -2.6 kg/d, respectively) compared with cows in HSC (-3.2 and -0.9 kg/d, respectively). Cows in CON had a greater decrease in milk protein concentration for PFTN (-0.10 percentage units) and HSC (-0.06 percentage units) compared with cows in RPM for PFTN (0.00 percentage units) and HSC (-0.02 percentage units). Cows in CON for HSC had greater decrease in milk fat concentration compared with cows in RPM for HSC (-0.10 and +0.12 percentage units, respectively). In conclusion, HSC altered physiological and production parameters of cows. Additionally, RPM helped maintain milk protein and fat concentration during HSC, whereas dry matter intake, milk yield, and feed efficiencies were not affected by RPM.

Technical note: Establishment of an ileal cannulation technique in preweaning calves and use of a piecewise regression approach to evaluate effects on growth and pH fluctuation of ileal digesta.

Digestibilities of nutrients, especially protein, are crucial characteristics of milk replacers in a calf-rearing program. Endogenous synthesis of proteins and microbial fermentation in the large intestine alter apparent total-tract digestibility of AA. Therefore, collection of digesta samples at the end of the ileum is the only method to estimate true small intestinal digestibility of AA. The aim of this work was to evaluate the effectiveness of inserting a T-cannula into the distal ileum of preweaning calves for use in digestibility studies. A second objective was to evaluate the use of a "broken-line" statistical model to compare treatment effects on calf growth and digesta pH. A T-cannula was surgically installed in the terminal ileum of 2 calves approximately 5 cm anterior to the ileocecal junction at 15 d of age, and 2 paired noncannulated calves were used as controls. Cannulation did not affect mean body weight (BW), average daily gain, milk and water intakes, and body frame dimensions. However, final BW (89.2 vs. 94.6 kg) was lower and starter intake (0.06 vs. 0.21 kg/d) tended to be decreased in cannulated calves compared with control calves. No effects on health scores, rectal temperature, or the odds of incurring diarrhea or being medicated were observed. Flow of digesta (46.4 ± 0.04 g/h) increased linearly after feeding, whereas there was a quadratic effect of time on digesta pH, with the nadir at approximately 8.5 h postfeeding. The broken-line model successfully fitted daily fluctuations of pH and allowed us to detect differences in growth slopes between cannulated and control calves. Despite the expected negative effect on BW, we conclude that this technique permitted sampling of representative ileal digesta while allowing satisfactory growth and health of the calves.

Technical note: Evaluating nuclear magnetic resonance spectroscopy for determining body composition in Holstein dairy calves using deuterium oxide dilution methods.

Deuterium oxide (D2O) dilution methods have been used to assess body composition in live animals. Estimated body water content can be used to predict body fat and protein, and thus, the amount of energy reserves. It is an alternative method to direct chemical analysis and considered a noninvasive technique that is economical and repeatable. Deuterium oxide use is considered easy, safe, and accurate; however, the traditional methods of analyzing D2O are expensive, tedious, and time consuming. The objective of this study was to evaluate the potential for using nuclear magnetic resonance spectroscopy (NMR) to determine body composition in Holstein dairy heifers. Nuclear magnetic resonance is less expensive and requires minutes to calculate the percentage of D2O in the blood. 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 milk replacer (MR) [CON; 20% crude protein (CP), 20% fat], (2) 669 g DM of a moderately high protein MR (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 free-choice access to starter and water. Both MR and starter were medicated with decoquinate. During weaning (d 43 to 49), the morning MR feeding ceased. On d 50, all MR feedings ended but starter and water intakes were continuously recorded until d 56. When calves were 50 d of age, a baseline blood sample was taken followed by injection of 300 mg of D2O/kg of body weight in sterile physiological saline (0.9%). The syringes containing the D2O in physiological saline were weighed before and after administration to record the actual dose of D2O injected gravimetrically. After injection, the D2O was allowed to equilibrate with body water for 1 h. Six blood samples were taken over 6 d (1/d) at 1630 h to estimate the dilution of the tracer. The plasma was aspirated and stored at -20°C until further D2O analysis. This new method was validated using 4 calf plasma samples that were sent to an outside laboratory for measurement using an independent validation method. We detected no differences in total body water, protein, fat, or mineral content in calves fed CON, MOD, or AGG; however, results demonstrated that the D2O dilution technique and analysis by NMR is an appropriate and easy method to estimate water, protein, ash, and fat in young heifers.

Inclusion of excess dietary calcium in diets for 100- to 130-kg growing pigs reduces feed intake and daily gain if dietary phosphorus is at or below the requirement.

An experiment was conducted to test the hypothesis that the requirement for standardized total tract digestible (STTD) Ca by pigs from 100 to 130 kg depends on the concentration of STTD P in the diet. Ninety pigs (average initial BW: 99.89 ± 3.34 kg) were randomly allotted to 15 experimental diets. Each diet was fed to 6 replicate pigs using a randomized complete block design. Fifteen corn and soybean meal-based diets were formulated and phytate and Na were constant among treatments. Diets were formulated using a 3 × 5 factorial design with diets containing 0.11%, 0.21%, or 0.31% STTD P and 0.12%, 0.29%, 0.46%, 0.61%, or 0.78% total Ca (0.08%, 0.18%, 0.29%, 0.38%, or 0.49% STTD Ca). The P concentrations ranged from 48 to 152% of the STTD P requirement for 100- to 125-kg pigs and the Ca concentrations ranged from 27 to 173% of the total Ca requirement. Experimental diets were fed for 28 d and pigs were individually housed. Pig and feeder weights were recorded at the beginning and at the conclusion of the experiment to calculate ADFI, ADG, and G:F. On d 28, all pigs were euthanized and the right femur was extracted. Ash, Ca, and P concentrations were determined from the de-fatted, dried femurs. Results indicated that as dietary concentrations of STTD Ca increased, ADFI decreased (main effect of Ca, < 0.05), regardless of the dietary concentration of P. The model to predict ADFI (ADFI = 3.6782 - 1.2722 × STTD Ca [%]; = 0.001) was dependent only on the concentration of dietary STTD Ca, but not on the concentration of dietary STTD P. In contrast, the model to predict ADG depended on both STTD Ca and STTD P (1.4556 - 1.4192 × STTD Ca [%] - 1.0653 × STTD P [%] + 4.2940 STTD Ca [%] × STTD P [%]; = 0.002). There were no effects of STTD Ca or STTD P on G:F. Linear increases were observed for bone ash, bone Ca, and bone P as dietary concentrations of STTD Ca increased for all concentrations of STTD P, but the increase was greater at the greatest concentration of STTD P than at lower concentrations (interaction, < 0.001). In conclusion, results indicate that the estimated requirement for dietary STTD Ca by 100- to 130-kg pigs needed to maximize ADG, bone ash, and bone Ca depends on the concentration of STTD P in the diet. Results also indicate that feeding Ca in excess of the current requirement for total Ca is detrimental to growth performance of pigs from 100 to 130 kg unless P is also included above the requirement.

Toward a theory of energetically optimal body size in growing animals.

Our objective was to formulate a general and useful model of the energy economy of the growing animal. We developed a theory that the respiratory energy per unit of size reaches a minimum at a particular point, when the marginal respiratory heat production rate is equal to the average rate. This occurs at what we defined as the energetically optimal size for the animal. The relationship between heat production rate and size was found to be well described by a cubic function in which heat production rate accelerates as the animal approaches and then exceeds its optimal size. Reanalysis of energetics data from the literature often detected cubic curvature in the relationship between heat production rate and body size of fish, rats, chickens, goats, sheep, swine, cattle, and horses. This finding was consistent with the theory for 13 of 17 data sets. The bias-corrected Akaike information criterion indicated that the cubic equation modeled the influence of the size of a growing animal on its heat production rate better than a power function for 11 of 17 data sets. Changes in the sizes and specific heat production rates of metabolically active internal organs, and body composition and tissue turnover rates were found to explain notable portions of the expected increase in heat production rate as animals approached and then exceeded their energetically optimum size. Accelerating maintenance costs in this region decrease net energy available for productive functions. Energetically and economically optimum size criteria were also compared.

Protocol for the Electroencephalography Guidance of Anesthesia to Alleviate Geriatric Syndromes (ENGAGES) study: a pragmatic, randomised clinical trial.

INTRODUCTION: Postoperative delirium, arbitrarily defined as occurring within 5 days of surgery, affects up to 50% of patients older than 60 after a major operation. This geriatric syndrome is associated with longer intensive care unit and hospital stay, readmission, persistent cognitive deterioration and mortality. No effective preventive methods have been identified, but preliminary evidence suggests that EEG monitoring during general anaesthesia, by facilitating reduced anaesthetic exposure and EEG suppression, might decrease incident postoperative delirium. This study hypothesises that EEG-guidance of anaesthetic administration prevents postoperative delirium and downstream sequelae, including falls and decreased quality of life. METHODS AND ANALYSIS: This is a 1232 patient, block-randomised, double-blinded, comparative effectiveness trial. Patients older than 60, undergoing volatile agent-based general anaesthesia for major surgery, are eligible. Patients are randomised to 1 of 2 anaesthetic approaches. One group receives general anaesthesia with clinicians blinded to EEG monitoring. The other group receives EEG-guidance of anaesthetic agent administration. The outcomes of postoperative delirium (≤5 days), falls at 1 and 12 months and health-related quality of life at 1 and 12 months will be compared between groups. Postoperative delirium is assessed with the confusion assessment method, falls with ProFaNE consensus questions and quality of life with the Veteran's RAND 12-item Health Survey. The intention-to-treat principle will be followed for all analyses. Differences between groups will be presented with 95% CIs and will be considered statistically significant at a two-sided p<0.05. ETHICS AND DISSEMINATION: Electroencephalography Guidance of Anesthesia to Alleviate Geriatric Syndromes (ENGAGES) is approved by the ethics board at Washington University. Recruitment began in January 2015. Dissemination plans include presentations at scientific conferences, scientific publications, internet-based educational materials and mass media. TRIAL REGISTRATION NUMBER: NCT02241655; Pre-results.

Effect of a grain challenge on ruminal, urine, and fecal pH, apparent total-tract starch digestibility, and milk composition of Holstein and Jersey cows.

The effects of a grain challenge on ruminal, urine, and fecal pH, apparent total-tract starch digestibility, and milk composition were determined. Six Holstein cows, 6 rumen-cannulated Holstein cows, and 6 Jersey cows were used in a replicated 3 × 3 Latin square design balanced to measure carryover effects. Periods (10 d) were divided into 4 stages (S): S1, d 1 to 3, served as baseline with regular total mixed ration ad libitum; S2, d 4, served as restricted feeding, with cows offered 50% of the total mixed ration fed on S1 (dry matter basis); S3, d 5, a grain challenge was performed, in which cows were fed total mixed ration ad libitum and not fed (CON) or fed an addition of 10% (MG) or 20% (HG) pellet wheat-barley (1:1) top-dressed onto the total mixed ration, based on dry matter intake obtained in S1; S4, d 6 to 10, served as recovery stage with regular total mixed ration fed ad libitum. Overall, cows had a quadratic treatment effect for milk yield where CON (22.6 kg/d) and HG (23.5 kg/d) had lower milk yield than cows in MG (23.7 kg/d). Jersey cows had a quadratic treatment effect for dry matter intake where cows in CON (13.2 kg/d) and HG (12.4 kg/d) had lower dry matter intake than cows in MG (14 kg/d). Holstein cows had a linear treatment effect for dry matter intake (17.7, 18.4, and 18.6 kg/d for CON, MG, and HG, respectively). Rumen pH for the rumen-cannulated cows had a linear treatment effect (6.45, 6.35, and 6.24 for CON, MG, and HG, respectively). Cows in HG spent more time with rumen pH below 5.8 (4.33 h) than MG (2 h) or CON (2.17 h) as shown by the quadratic treatment effect. Holstein cows in HG (8.46) had lower urine pH than MG (8.51) or CON (8.54) as showed by the linear treatment effect for urine pH. Apparent total-tract starch digestibility had a tendency for a linear treatment effect on S3 (97.62 ± 1.5, 97.47 ± 1.5, and 91.84 ± 1.6%, for CON, MG, and HG, respectively). Fecal pH was associated with rumen pH depression as early as 15 h after feeding for Holstein cows. In conclusion, a grain challenge reduced urine pH in Holstein cows but not in Jersey cows. Holstein cows' health were not affected when rumen pH was depressed. A potentially useful link between rumen pH and systemic (urine) pH within 2 h after feeding was quantified in Holstein cows.

Requirement for digestible calcium by 25 to 50 kg pigs at different dietary concentrations of phosphorus as indicated by growth performance, bone ash concentration, and calcium and phosphorus balances.

Two experiments were conducted to determine the requirement for standardized total tract digestible (STTD) Ca by 25 to 50 kg pigs at different concentrations of STTD P. Twenty corn-soybean meal based diets were formulated with diets containing 4 concentrations of STTD P (0.15, 0.31, 0.39, or 0.47%) and 5 concentrations of STTD Ca (0.13, 0.27, 0.42, 0.57, or 0.72%). Diets were mixed in 1 batch and were used in both experiments. In Exp. 1, 240 pigs (initial average BW: 24.70 ± 1.27 kg) were randomly allotted to the 20 diets in 6 blocks with 1 pen per diet in each block using a 4 × 5 factorial design. There was 1 gilt and 1 barrow in each pen. At the conclusion of the 28 d experiment, all barrows were euthanized and the right femur was collected. Results indicated that there were interactions ( < 0.001) between concentration of STTD Ca and concentration of STTD P in diets for ADG, G:F, and bone ash. The predicted maximum ADG at STTD P concentrations of 0.15, 0.31, 0.39, and 0.47% were 0.76, 0.87, 0.90, and 0.92 kg at STTD Ca concentrations of 0.12, 0.36, 0.47, and 0.59%, respectively, which correspond to STTD Ca:STTD P ratios of 0.80:1, 1.16:1, 1.21:1, and 1.26:1. The predicted maximum G:F ratio at the 4 STTD P concentrations were 0.43, 0.46, 0.48, and 0.50 kg/kg at STTD Ca concentrations of 0.09, 0.38, 0.52, and 0.67%, respectively, and these values correspond to STTD Ca:STTD P ratios of 0.60:1, 1.23:1, 1.33:1, and 1.43:1. The predicted maximum bone ash at the 4 STTD P concentrations were 14.5, 21.0, 23.1, and 24.5 g at STTD Ca concentrations of 0.41, 0.56, 0.64, and 0.72%, respectively, which correspond to STTD Ca:STTD P ratios of 2.73:1, 1.81:1, 1.64:1, and 1.53:1. In Exp. 2, 120 pigs (initial average BW: 29.45 ± 2.15 kg) were placed in metabolism crates and randomly allotted to the 20 diets in 6 blocks with 1 pig per diet in each block. Fecal and urine samples were collected. Results indicated that the predicted maximum retention of Ca in the body at STTD P concentrations of 0.15, 0.31, 0.39, and 0.47% were 4.7, 7.1, 8.6, and 10.2 g/d at STTD Ca concentrations of 0.77, 0.96, 1.06, and 1.15%, respectively, which correspond to STTD Ca:STTD P ratios of 5.13:1, 3.10:1, 2.72:1, and 2.45:1. These observations indicate that if STTD P meets or exceeds the requirement, the STTD Ca:STTD P ratio needed to maximize ADG and G:F by 25 to 50 kg pigs is between 1.16:1 and 1.43:1. However, a greater ratio may be needed to maximize bone ash or Ca retention.

Prepartum nutritional strategy affects reproductive performance in dairy cows.

Negative energy balance during early postpartum is associated with reduced reproductive performance in dairy cows. A pooled statistical analysis of 7 studies completed in our group from 1993 to 2010 was conducted to investigate the association between prepartum energy feeding regimen and reproductive performance. The interval from calving to pregnancy (days to pregnancy, DTP) was the dependent variable to assess reproductive performance. Individual data for 408 cows (354 multiparous and 54 primiparous) were included in the analysis. The net energy for lactation (NEL) intake was determined from each cow's average dry matter intake and calculated dietary NEL density. Treatments applied prepartum were classified as either controlled-energy (CE; limited NEL intake to ≤100% of requirement) or high-energy (HE; cows were allowed to consume >100%) diets fed during the far-off (FO) or close-up (CU) dry periods. Cow was the experimental unit. The Cox proportional hazard model revealed that days to pregnancy was shorter for CE (median=157 d) than HE (median=167 d) diets during the CU period [hazard ratio (HR)=0.70]. Cows fed HE diets during the last 4 wk prepartum lost more body condition score in the first 6 wk postpartum than those fed CE diets (-0.43 and -0.30, respectively). Cows fed CE diets during the FO period had lower nonesterified fatty acids concentrations in wk 1, 2, and 3 of lactation than cows fed HE diets. Higher nonesterified fatty acids concentration in wk 1 postpartum was associated with a greater probability of disease (n=251; odds ratio=1.18). Cows on the CE regimen during the FO period had greater plasma glucose concentrations during wk 1 and 3 after calving than cows fed the HE regimen. Higher plasma glucose (HG) concentration compared with lower glucose (LG) in wk 3 (HG: n=154; LG: n=206) and wk 4 (HG: n=71; LG: n=254) after calving was associated with shorter days to pregnancy (wk 3: median=151 and 171 d for HG and LG, respectively, and HR=1.3; wk 4: median=148 and 167 d, respectively, and HR=1.4). In the first 2 wk after calving, cows that received HE diets in the FO period had higher concentrations of total lipids and triglyceride and greater ratio of triglyceride to glycogen in liver than cows fed CE diets. In conclusion, cows fed CE diets during the CU period had a shorter interval between parturition and conception, which may be explained by increased NEL intake during the first 4 wk postpartum and lower incidence of peripartal diseases. Lower body condition score loss during the first 6 wk postpartum and slightly higher glucose concentration at wk 3 likely contributed to improved reproductive performance.

Short communication: Kelp taste preferences by dairy calves.

Kelp is a common feed additive used on many dairy farms in the United States. However, few data are available supporting the efficacy of its addition to cattle feed. The purpose of this study was to evaluate the taste preferences of calves provided with 0, 30, or 60 g of kelp daily in a sequential elimination experiment. Calves in this study always ranked the control treatment first when given a choice and consumed 34.5% more dry matter from the control treatment in the first 3-d segment of the experiment. During the second feeding segment (d 4 and 5), when the control treatment was removed, daily dry matter consumption was reduced in 4 out of 6 calves compared with control calves when this treatment was available (first feeding segment). However, calves did not differentiate between the 2 amounts of kelp. Results indicated that calves preferred calf starter grains without kelp.

Maximizing profit on New England organic dairy farms: an economic comparison of 4 total mixed rations for organic Holsteins and Jerseys.

The objective of these experiments was to compare 4 total mixed rations fed to USDA-certified organic dairy cows in New England. Forty-eight Jersey cows from the University of New Hampshire (UNH) and 64 Holstein cows from the University of Maine (UMaine) were assigned to a 2 × 2 factorial arrangement of treatments testing the main effects of corn silage versus grass silage as the forage base and commodity concentrates versus a complete pelleted concentrate mixture. Treatment diets were fed as a total mixed ration for 8 wk during the winter and spring months of 2007, 2008, and 2009. Milk yield, component, and quality data were recorded and used to calculate the value of the milk produced for each cow. The dry matter intake (DMI) was recorded and used to calculate the average cost per cow per day of each diet. Income over feed costs were calculated for each diet using milk value and feed cost data. Feed cost and income over feed cost data were resampled using bootstrap methodology to examine potential patterns. Milk yield, milk fat and true protein concentrations, and SCC were similar among treatments. Cows at UNH fed corn silage tended to have higher DMI and lower milk urea nitrogen than did cows fed grass silage, whereas cows fed pellets had higher DMI than cows fed commodities. Cows at UNH fed commodities tended to have higher body condition scores than those fed pellets. Cows at UMaine fed commodities tended to have higher DMI than did cows fed pellets, and cows fed corn silage had lower milk urea nitrogen than did cows fed grass silage. Body weights and body condition scores were not different for cows at UMaine. Feed costs were significantly higher for corn silage diets and diets at UNH containing pellets, but not at UMaine. The calculated value of the milk and income over feed costs did not differ among treatments at either university. Bootstrap replications indicated that the corn silage with commodities diet generally had the highest feed cost at both UNH and UMaine, whereas grass silage diets containing commodities generally had the lowest cost. In contrast, the grass silage with commodities diets had the highest income over feed cost in the majority of the replications at both UNH and UMaine replications, whereas the corn silage with commodities diets had the lowest rank. Similar results were observed when forage prices were increased or decreased by 5, 10, and 25% above or below the actual feed price. Feeding a grass silage-based diet supplemented with commodity concentrates may have an economic advantage for dairy producers in New England operating under an organic system of production.

Particle size distribution and chemical composition of total mixed rations for dairy cattle: water addition and feed sampling effects.

Four dairy farms were used to determine the effects of water addition to diets and sample collection location on the particle size distribution and chemical composition of total mixed rations (TMR). Samples were collected weekly from the mixing wagon and from 3 locations in the feed bunk (top, middle, and bottom) for 5 mo (April, May, July, August, and October). Samples were partially dried to determine the effect of moisture on particle size distribution. Particle size distribution was measured using the Penn State Particle Size Separator. Crude protein, neutral detergent fiber, and acid detergent fiber contents were also analyzed. Particle fractions 19 to 8, 8 to 1.18, and <1.18 mm were judged adequate in all TMR for rumen function and milk yield; however, the percentage of material>19 mm was greater than recommended for TMR, according to the guidelines of Cooperative Extension of Pennsylvania State University. The particle size distribution in April differed from that in October, but intermediate months (May, July, and August) had similar particle size distributions. Samples from the bottom of the feed bunk had the highest percentage of particles retained on the 19-mm sieve. Samples from the top and middle of the feed bunk were similar to that from the mixing wagon. Higher percentages of particles were retained on >19, 19 to 8, and 8 to 1.18 mm sieves for wet than dried samples. The reverse was found for particles passing the 1.18-mm sieve. Mean particle size was higher for wet than dried samples. The crude protein, neutral detergent fiber, and acid detergent fiber contents of TMR varied with month of sampling (18-21, 40-57, and 21-34%, respectively) but were within recommended ranges for high-yielding dairy cows. Analyses of TMR particle size distributions are useful for proper feed bunk management and formulation of diets that maintain rumen function and maximize milk production and quality. Water addition may help reduce dust associated with feeding TMR.

Inclusion of psyllium in milk replacer for neonatal calves. 1. Effects on growth, digesta viscosity, rate of passage, nutrient digestibilities, and metabolites in blood.

Based on research in other species, inclusion of psyllium in milk replacer might improve nutrient utilization and gastrointestinal function in neonatal calves. Male Holstein calves were fed a milk replacer (22% crude protein, 20% fat) either without or with psyllium (1.1% of dry matter) from 2 d through 28 d of age. Milk replacer was reconstituted to 12.5% dry matter (DM) and fed at 12% of calf body weight (BW), adjusted weekly. Water was offered ad libitum but no starter was fed. Three calves per treatment were harvested weekly to sample digesta from the rumen, abomasum, jejunum, proximal colon, and distal colon. Mean daily intakes of water, DM, crude protein, and metabolizable energy did not differ between treatments. Average daily gain of BW did not differ between treatments. Digesta from the abomasum and colon of calves fed psyllium was more viscous than digesta from control calves. Mean retention time of digesta in the total digestive tract tended to be greater for calves supplemented with psyllium (9.7 vs. 8.4h). Feces and digesta from the proximal and distal colon of calves fed psyllium had lower DM content than feces and digesta from control calves. Total-tract apparent digestibility of DM (92.8 vs. 94.1%) was lower for psyllium-fed calves, likely as an effect of the addition of the more poorly digestible psyllium; digestibilities of energy and ash also tended to be lower. The prefeeding plasma glucose concentration (10h after previous feeding) tended to be greater for psyllium-fed calves but concentrations of nonesterified fatty acids, beta-hydroxybutyrate, cholesterol, urea N, and total protein did not differ between treatments. Blood components did not differ between treatments at 2h postfeeding. Inclusion of psyllium in the milk replacer of neonatal calves increased digesta viscosity and slowed passage of digesta through the gastrointestinal tract.

Nitrogen transactions along the gastrointestinal tract of cattle: A meta-analytical approach.

In ruminant animals, endogenous N (EN) secretions contribute to meeting the N requirement of the ruminal microflora. The EN also constitutes a sizable portion of the duodenal N flow, which might be available to the host animal. Most measures of EN have been accomplished with highly invasive techniques or unusual semisynthetic diets. By utilizing a statistical approach and data obtained from studies reporting duodenal, ileal, and fecal N flows in cattle, the EN losses and true digestibility of N were estimated for different segments of the gastrointestinal tract of cattle. A simulation for a reference diet (24.2 g of N/kg of OM, 32% NDF and carbohydrates of medium fermentation rate) consumed at 2% of BW daily estimated that the minimal contribution of EN to the N available in the rumen was 39%. The free EN represented 13% of the duodenal N flow, and when bacterial N of EN origin was considered, EN contributed 35% of the total N flow. The minimal entry of EN into various segments of the gastrointestinal tract was also estimated as: foregut, 10.54; small intestine, 3.10; and hindgut, 5.0 g/kg of OMI. Rumen dietary N degradability was 0.68, and true N digestibilities in the small intestine and hindgut were 0.75 and 0.49, respectively. A better understanding of the factors involved in EN losses will allow for a more accurate estimation of both N supply and N requirements. This will translate into improved accuracy of diet formulation and less N excreted into the environment.

Dietary cation-anion difference and dietary protein effects on performance and acid-base status of dairy cows in early lactation.

Our objective was to examine the effects of dietary cation-anion difference (DCAD) with different concentrations of dietary crude protein (CP) on performance and acid-base status in early lactation cows. Six lactating Holstein cows averaging 44 d in milk were used in a 6 x 6 Latin square design with a 2 x 3 factorial arrangement of treatments: DCAD of -3, 22, or 47 milliequivalents (Na + K - Cl - S)/100 g of dry matter (DM), and 16 or 19% CP on a DM basis. Linear increases with DCAD occurred in DM intake, milk fat percentage, 4% fat-corrected milk production, milk true protein, milk lactose, and milk solids-not-fat. Milk production itself was unaffected by DCAD. Jugular venous blood pH, base excess and HCO3(-) concentration, and urine pH increased, but jugular venous blood Cl- concentration, urine titratable acidity, and net acid excretion decreased linearly with increasing DCAD. An elevated ratio of coccygeal venous plasma essential AA to nonessential AA with increasing DCAD indicated that N metabolism in the rumen was affected, probably resulting in more microbial protein flowing to the small intestine. Cows fed 16% CP had lower urea N in milk than cows fed 19% CP; the same was true for urea N in coccygeal venous plasma and urine. Dry matter intake, milk production, milk composition, and acid-base status did not differ between the 16 and 19% CP treatments. It was concluded that DCAD affected DM intake and performance of dairy cows in early lactation. Feeding 16% dietary CP to cows in early lactation, compared with 19% CP, maintained lactation performance while reducing urea N excretion in milk and urine.

Dietary cation-anion difference effects on performance and acid-base status of dairy cows postpartum.

Our objective was to examine the effect of dietary cation-anion difference (DCAD) on performance and acid-base status of cows postpartum. Sixteen Holstein and 8 Jersey multiparous cows were used immediately after calving to compare 2 DCAD [22 or 47 milliequivalents (Na + K - Cl - S)/100 g of dry matter (DM)] in a completely randomized design. The corn silage-based diets were formulated to contain 19.0% crude protein, 25.4% neutral detergent fiber, 15.0% acid detergent fiber, and 1.69 Mcal of net energy for lactation per kilogram (on a DM basis). An additional 2.3 kg of alfalfa hay was fed during the first 5 d postpartum, and then milk, blood, and urine samples were collected weekly for 6 wk. Repeated-measures (with an extra between-cow effect) mixed model analysis indicated that DCAD did not affect DM intake (18.2 and 18.3 kg/d), milk production (33.5 and 33.3 kg/d), milk composition (3.96 and 4.11% fat, 3.11 and 3.00% protein, and 8.95 and 8.83% solids-not-fat), jugular venous blood pH (7.395 and 7.400), HCO3(-) concentration (27.3 and 27.6 mEq/L), or partial pressure of CO2 (46.7 and 46.5 mmHg). Elevated coccygeal venous plasma branched-chain AA (431 and 558 microM) and ratio of essential AA to total AA (0.390 and 0.434) in cows with DCAD of 22 vs. 47 mEq/100 g of DM indicated that N metabolism in the rumen was affected, probably resulting in more microbial protein flowing to the small intestine. Urinary pH tended to increase with DCAD (8.12 vs. 8.20). Higher net acid excretion in cows with DCAD of 22 vs. 47 mEq/100 g of DM (-24 and -41 mM:mM) suggested that net acid excretion was much more indicative of acid load than blood acid-base parameters in cows postpartum. Intake of DM and performance of cows postpartum were not improved when DCAD increased from 22 to 47 mEq/100 g of DM, likely because cows immediately after calving respond more variably to dietary treatments and that makes treatment effects difficult to detect.

Housekeeping gene expression in bovine liver is affected by physiological state, feed intake, and dietary treatment.

Selection of appropriate housekeeping genes (HKG) for normalization of quantitative PCR data for genes of interest is critical for interpretation of results. Ideally, copy number of the chosen HKG mRNA will not vary with experimental treatments or physiological state in the tissue studied, which improves accuracy in detecting changes in genes of interest. Because of the liver's dynamic role in metabolism, physiological state or dietary treatments could alter mRNA expression of commonly used HKG. Therefore, the objective of this study was to evaluate stability of mRNA expression for a number of candidate HKG in bovine liver across different physiological and dietary experimental conditions during the periparturient period. A publicly available program (geNorm) was used to evaluate expression stability of 8 HKG (beta-actin, glyceraldehyde 3-phosphate dehydrogenase, beta-glucuronidase, peptidylprolyl isomerase A, polyubiquitin, ribosomal protein S9, ribosomal protein L32, and 18S ribosomal RNA) in 91 liver RNA samples. Screened samples included liver from cows in 3 groups: 1) cows receiving a dietary supplement pre- and postpartum (n = 10); 2) cows with clinical or subclinical ketosis (n = 7); and 3) cows consuming different amounts of energy prepartum (n = 74). In group 3, samples from d -65, -30, -14, 1, 14, 28, and 49 relative to parturition were included to enable characterization of HKG mRNA expression across different physiological states. Initial analyses indicated that mRNA for ribosomal protein S9 (RPS9) was one of the most stably expressed across different experiment types. To determine the best gene, 200 bootstrap replications of the original data set were performed to determine if the ranking of RPS9 was superior to the other 7 genes evaluated. Average ranks and estimated standard errors for the top 3 genes were 1.64 +/- 0.06, 3.27 +/- 0.10, and 3.71 +/- 0.12 for RPS9, GAPDH, and beta-actin, respectively. Ribosomal protein S9 was ranked first 59% of the time and was never ranked lower than fifth. The lowest-ranked gene was polyubiquitin, ranked last 46.5% of the time (average rank = 6.85 +/- 0.10). In this study, physiological state, amount of intake, or dietary treatment influenced the mRNA expression of commonly used HKG in bovine liver. Ideally, expression stability should be tested before collection of data in all experiments; however, we have shown that RPS9 mRNA is stable across several physiological and diet-related experimental conditions for dairy cows, making it a good HKG in liver quantitative PCR experiments.

Food intake and ingredient profile affect viscosity of ileal digesta of dogs.

Two experiments were conducted to determine dietary factors affecting digesta viscosity. In experiment 1, six ileal-cannulated dogs were either full (607.1 kJ/BW0.67) or restricted (303.5 kJ/BW0.67) fed. In experiment 2, four dog foods were surveyed for effects on digesta viscosity based on protein source [animal protein (AP) or plant protein (PP)] or dietary fibre source [soluble dietary fibre (SDF) or insoluble dietary fibre (IDF)]. Dry matter (DM) intake was higher (p<0.05) when dogs were full (11.4 g/kg) compared with restricted fed (5.98 g/kg). Ileal digesta viscosity tended to be higher (p=0.07) for full fed [10,251 centipoise (cP)] compared with restricted-fed dogs (6677 cP). Ileal digesta viscosities were 6561, 11,074, 13,830 and 15,967 cP for dogs consuming IDF, SDF, AP and PP treatments respectively. Ileal DM concentrations were 11.4%, 13.6%, 14.8% and 14.8% for SDF, IDF, AP and PP treatments respectively. DM digestibility coefficients were lowest (71.2%) for the PP treatment and highest (88.7%) for the IDF treatment. Organic matter digestibilities followed a similar pattern. Ileal digesta viscosity of dogs appears to increase with increased diet intake, and increased ileal DM concentration. More digestible diets result in less ileal DM and lower viscosity constants.