When and where do dairy cows defecate and urinate?

The accumulation of urine and feces can be responsible for many cow and environmental problems. Despite this, little is known about the factors affecting defecation and urination. In the first experiment, the occurrence of defecation and urination behaviors of 48 lactating Holstein cows was observed [days in milk (DIM) = 144.7 ± 38.0 d, body weight (BW) = 667.1 ± 72.0 kg, parity = 2.8 ± 2.3] in freestalls over 48 h. In the second experiment, defecation and urination by 29 lactating Holstein dairy cows were observed (DIM = 62 ± 22.1 d, BW = 590 ± 70.0 kg, parity = 2 ± 1.3) in another freestall barn over a period of 5 d and related to cow activity and feeding behavior. In both experiments, based on total occurrence of eliminative behaviors, cows mainly defecated (experiment 1: 33.4 ± 2.0%; experiment 2: 42.3 ± 3.1%) and urinated (experiment 1: 28.2 ± 2.5%; experiment 2: 42.7 ± 4.0%) in the feed alley and while occupying a stall (defecation: experiment 1: 28.5 ± 1.0%; experiment 2: 26.2 ± 3.0%; urination: experiment 1: 42.2 ± 1.5%; experiment 2: 39.9 ± 3.8%). Occupying a stall included lying, standing in the stall, or standing with 2 feet in the stall and 2 feet in the alley. In both experiments, differences were found between cows in frequency of defecation (experiment 1: 9.8 ± 4.2/d, range = 3 to 20; experiment 2: 15.4 ± 4.3/d, range = 6 to 36) and in frequency of urination (experiment 1: 7.0 ± 3.1/d, range = 2 to 18; experiment 2: 9.3 ± 2.8/d, range = 3 to 19). Large differences between cows were observed in the frequency of defecation and urination, but these were not correlated with parity, milk production, BW, DIM, or dry matter intake.     

Measuring liveweight changes in lactating dairy ewes with an automated walk-over-weighing system

Monitoring liveweight (LW) is an important part of sound management practices at the individual and flock level (e.g., controlling for nutritional status based on body condition, reproduction, and health-related issues), but it is time consuming and stressful. To our knowledge, no literature has reported on the evaluation of automated weighing systems in dairy sheep as an alternative to conventional static scales. The objective of this research was to evaluate the practical feasibility of using an automated walk-over-weighing (WoW) prototype to measure daily LW changes in dairy ewes without human intervention. We used adult Lacaune dairy ewes in 2 complementary trials conducted indoors. Trial 1 aimed at evaluating the repeatability, precision, and accuracy of LW measures recorded using WoW scales compared with a static scale (the gold standard). Forty-two adult ewes (LW ± standard deviation = 71.3 ± 10.4 kg) were randomly drafted from the main flock and used in a 1-day session. The trial included 3 passages. In each passage, ewes were weighed first on a static scale; once a static position was achieved and LW recorded, they continued the circuit and immediately traversed the WoW scale for an automated LW record. Trial 2 aimed to demonstrate the feasibility of using the WoW device under real-world conditions in a dairy sheep-farming system. The WoW scale was installed in the exit race of the milking parlor and evaluated over 7 wk with adult ewes in mid lactation (n = 93; LW 78.5 ± 8.1 kg). Once the ewes were acclimated to the WoW system, 1 group of ewes (n = 48) continued to receive the same feeding regimen (controls), and the other group (n = 45) underwent a nutritional challenge [challenged; 2 wk of undernutrition and then back to control regimen (refeeding) for 1 wk]. We evaluated the ability of the WoW to detect small changes in LW. We collected LW data (2 weighings per ewe per day) from the WoW after each of the 2 milking sessions (morning and evening). We also obtained LW values by weighing the ewes using a static scale once a week. The automated WoW system showed substantial agreement with the gold standard when assessed using Lin's concordance correlation coefficient and Bland and Altman's method, largely due to high repeatability. The WoW system was adequate for detecting small daily variations in LW during undernutrition and refeeding periods. Misbehaviors resulted in spurious WoW values in trial 2, requiring us to use filtration methods to exclude outlier weights and allow meaningful assessment of small LW changes. The WoW system evaluated here is an alternative to the static scales conventionally used on dairy sheep farms. If sound filtration of raw data is applied, WoW could contribute to the close (daily) monitoring of individual LW without operator intervention (i.e., voluntary weighing) and taking animal welfare into account (i.e., no stress related to the weighing session on static scales).     

The evaluation of liquefied de-oiled herring silage in diets for growing pigs: Feeding trials

Pens of pigs grown from 30 to 60 kg liveweight (LW) and 30 to 90 kg LW in separate experiments were fed diets containing either 75 or 150 kg t^?1 dietary dry matter of de-oiled herring offal silage stored for up to 8 weeks, and their performance compared with pens of pigs fed control diets based on soya bean meal formulated to contain equivalent levels of total lysine. All pens of pigs were rationed on the same time-based scale of feeding. Pigs in both weight ranges fed herring silage diets grew significantly faster than the control pigs; in the 30–60 kg LW range growth rates were 687 and 529 g day^?1 (P<0.01) and in the 30–90 kg LW range, 670 and 588 g day^?1 (P= 0.05), respectively. The mean feed: gain ratio was also better with pigs fed the herring silage diets. No significant differences were found between treatment and control pigs slaughtered at either 60 or 90 kg LW for back fat probe measurements or killingout percentage. No pigs were down graded by the Meat and Livestock Commission carcass quality classification.     

Body composition and feed intake of young pigs postweaning

Thirty-five female Large White pigs were weaned at 14 days of age, penned individually, given a single diet and slaughtered serially at 25, 40, 55 and 70 days of age. A control group was fed to appetite throughout while three groups were subjected to feed restriction at various ages postweaning. For the periods 25 to 40, 40 to 55, 55 to 70 days of age pigs fed to appetite gained 321 (±19.9), 532 (±35.4) and 601 (±35.5) g liveweight day^?1. Pigs restricted between 25 and 55 days, followed by refeeding from 55 to 70 days, gained 192 (±14.0), 169 (±44.8) and 508 (±81.0) g liveweight day^?1; pigs restricted between 40 and 55 days, followed by refeeding from 55 to 70 days, gained 425 (±42.8), 409 (±49.6) and 480 (±70.1) g liveweight day^?1. A group given 200 g feed day^?1 gained 42 (±4.2) g liveweight daily between 25 and 70 days. Refed groups did not differ significantly from controls in their feed intakes for the period 55 to 70 days, either in absolute intakes or in feed intake kg^?1 mean liveweight. Refed pigs grew no faster, and made no greater protein gains than controls of equivalent weight; however, lipid gains were elevated.     

Polyethylene glycol as an indigestible marker to estimate fecal output in dairy cows

The objective of this study was to evaluate the accuracy of fecal output measurements using polyethylene glycol (PEG) as an external marker determined by near-infrared reflectance spectroscopy. In addition, the accuracy of dry matter intake predictions based on fecal output and digestibility estimated using an internal marker [indigestible neutral detergent fiber (iNDF)] was assessed. The experiment was conducted using 6 lactating dairy cows fed 2 different diets. Polyethylene glycol was administered twice daily into the rumen and the diurnal pattern of fecal concentrations and recovery in feces were determined. To evaluate the effects of alternative marker administration and sampling schemes on fecal output estimates, the passage kinetics of PEG in the digestive tract of dairy cows was determined and used for simulation models. The results indicate that PEG was completely recovered in feces and, thus, fecal output was accurately estimated using PEG. Good agreement between measured and predicted dry matter intake (standard error of prediction = 0.86 kg/d, R² = 0.81) indicates good potential to determine feed intake using PEG in combination with iNDF. The precision of cow-specific digestibility estimates based on iNDF was unsatisfactory, but for a group of cows iNDF provided an accurate estimate of dry matter digestibility. The current study indicated that, to overcome inherent day-to-day variation in feed intake and fecal output, the minimum of 4 fecal spot samples should be collected over 4 d. Preferably, these samples should be distributed evenly over the 12-h marker administration interval to compensate for the circadian variation in fecal PEG concentrations.     

Models to predict dry feed intake in Holstein calves to 4 months of age

Voluntary daily dry feed intake (DFI) in Holstein calves was predicted using 60,761 individual daily observations collected from 1,235 Holstein calves in 30 experiments from 4 research stations in the United States and Europe. Consumption of dry feed (calf starter and hay, kg/d or percent of body weight) was measured from 3 to 114 d of age. Linear models and 2- and 3-parameter nonlinear models were evaluated to predict DFI using age of calf, intake of milk replacer, ambient temperature, percent forage, and neutral detergent fiber concentration in ration dry matter (DM) as independent variables. The initial data set was randomly divided within study location into development (80% of all observations) and validation data sets, and initial screening was conducted using the development data set. Five nonlinear models and 3 linear models (candidate models) were identified and used in further model evaluation. Cross-validation studies (n = 20) with the validation data set were conducted by linear regression of DFI with predicted DFI as independent variable. Candidate models were subsequently evaluated with data from 12 published studies in 2 analyses. The exponential model that best predicted daily DFI in Holstein calves in original and external data sets was DFI (kg/d) = 1.3207 × e^{[(?5.3892 + 0.6376 × MEgap) × EXP(?0.0392 × Age)]} – 0.0013 × Temp + 0.0032 × NDFDM + 0.0026 × Age × MEgap – 0.3646 × PctForage [coefficient of determination (R²) = 0.92, concordance correlation coefficient (CCC) = 0.96, and mean square error of prediction (MSEP) = 0.10 kg]; where MEgap (Mcal/d) = difference of daily metabolizable energy (ME) requirement and ME intake from milk replacer; Age = age of calf (d) from 3 to 114, Temp = mean daily ambient temperature (°C), NDFDM = ration neutral detergent fiber (% DM); PctForage = percent forage in ration DM. The linear model that best predicted DFI was DFI (kg/d = ?0.1349 + 0.0106 × Age + 0.1808 × MEgap + 0.0013 × Age × MEgap + 0.0001 × Temp + 0.00002 × Age × Temp (R² = 0.93, CCC = 0.96, and MSEP = 0.10 kg). When Temp and ration characteristics were not included, optimal models were 1.4362 × e^{[(?4.6646 + 0.5234 × MEgap) × EXP(?0.0361 × Age)]} + 0.0025 × Age × MEgap (R² = 0.92, CCC = 0.96, and MSEP = 0.11 kg) and ?0.1344 + 0.0102 × Age + 0.1810 × MEgap + 0.0013 × Age × MEgap [R² = 0.93, CCC = 0.96, and MSEP = 0.10 kg]. Models of daily DFI may improve prediction of nutrient supply to young Holstein calves to approximately 4 mo of age, thereby increasing prediction of growth performance.     

Genetic parameters across lactation for feed intake,fat- and protein-corrected milk,and liveweight in first-parity Holstein cattle

Breeding values for dry matter intake (DMI) are important to optimize dairy cattle breeding goals for feed efficiency. However, generally, only small data sets are available for feed intake, due to the cost and difficulty of measuring DMI, which makes understanding the genetic associations between traits across lactation difficult, let alone the possibility for selection of breeding animals. However, estimating national breeding values through cheaper and more easily measured correlated traits, such as milk yield and liveweight (LW), could be a first step to predict DMI. Combining DMI data across historical nutritional experiments might help to expand the data sets. Therefore, the objective was to estimate genetic parameters for DMI, fat- and protein-corrected milk (FPCM) yield, and LW across the entire first lactation using a relatively large data set combining experimental data across the Netherlands. A total of 30,483 weekly records for DMI, 49,977 for FPCM yield, and 31,956 for LW were available from 2,283 Dutch Holstein-Friesian first-parity cows between 1990 and 2011. Heritabilities, covariance components, and genetic correlations were estimated using a multivariate random regression model. The model included an effect for year-season of calving, and polynomials for age of cow at calving and days in milk (DIM). The random effects were experimental treatment, year-month of measurement, and the additive genetic, permanent environmental, and residual term. Additive genetic and permanent environmental effects were modeled using a third-order orthogonal polynomial. Estimated heritabilities ranged from 0.21 to 0.40 for DMI, from 0.20 to 0.43 for FPCM yield, and from 0.25 to 0.48 for LW across DIM. Genetic correlations between DMI at different DIM were relatively low during early and late lactation, compared with mid lactation. The genetic correlations between DMI and FPCM yield varied across DIM. This correlation was negative (up to −0.5) between FPCM yield in early lactation and DMI across the entire lactation, but highly positive (above 0.8) when both traits were in mid lactation. The correlation between DMI and LW was 0.6 during early lactation, but decreased to 0.4 during mid lactation. The highest correlations between FPCM yield and LW (0.3–0.5) were estimated during mid lactation. However, the genetic correlations between DMI and either FPCM yield or LW were not symmetric across DIM, and differed depending on which trait was measured first. The results of our study are useful to understand the genetic relationship of DMI, FPCM yield, and LW on specific days across lactation.     

Automatic recording of daily walkover liveweight of dairy cattle at pasture in the first 100 days in milk

Daily walkover liveweight (WoLW) records (n = 79,697) from 463 pasture-fed dairy cows from a single dairy herd in the lower North Island of New Zealand were recorded over the first 100 d of lactation. The aims of this study were to (1) describe LW records retrieved by a standalone automatic Wo daily weighing system; (2) describe the frequency and nature of outlier LW records measured by the system and develop an approach for excluding identified outlier LW records; (3) quantify the agreement between cow LW measured using the Wo system and those measured statically; and (4) describe the autocorrelation between daily LW measurements to provide an indication of how frequently management decisions need to be reviewed to effectively monitor cow LW change in the early-lactation period. The standard deviation of daily LW measurements across parities was 17 kg, on average. A near perfect association between LW measured statically and WoLW (concordance correlation coefficient 0.99, 95% CI 0.99-1.0) was observed. After controlling for the effect of LW at calving and long-term LW change using a mixed-effects linear regression model, the autocorrelation between WoLW recorded on successive days was 0.21, decaying to zero by 8 d. This study shows that by using a standalone automatic Wo weighing system positioned in the exit race of a rotary milking parlor, it was possible to record LW of individual cows on a daily basis and, with controlled cow flow over the weighing platform (allowing for sufficient succession distance to prevent congestion), results were similar to those recorded using conventional, static weighing techniques using the same scales. Based on the autocorrelation analyses, we recommend that LW are recorded on a daily basis to allow changes in physiological status such as the onset of acute illness or estrus to be detected. For managerial purposes, such as using LW change as a guide for adjusting the herd feeding program, we recommend a 7-d decision interval to effectively monitor significant changes in cows’ recorded daily LW measurements.     

“Global” and “local” predictions of dairy diet nutritional quality using near infrared reflectance spectroscopy

The objective of the study was to evaluate performance of classic (global) and innovative (local) calibration techniques to monitor cattle diet, based on fecal near infrared reflectance spectroscopy (NIRS). A 3-yr on-farm survey (2005-2008) was carried out in Vietnam and La Reunion Island to collect animal, feed intake, and feces excretion data. Feed and feces were scanned by a Foss NIRsystem 5000 monochromator (Foss, Hillerød, Denmark) to estimate diet characteristics and nutrient digestibility. A data set including 1,322 diet-fecal pairs was built and used to perform global and local calibrations. Global equations gave satisfactory accuracy [coefficient of determination (R²) >0.8, 10% ≤ relative standard error of prediction (RSEP) ≤20%], whereas local equations gave good accuracy (R² >0.8, RSEP <10%) or excellent accuracy (R² >0.9, RSEP <10%) for the prediction of diet intake, quality, and digestibility. When validating the equations using the external individual data, both techniques were robust, with similar RSEP (8%) and R² (0.82) values. The predictive performance of global and local equations was improved (RSEP = 5% and R² = 0.90) when averaged animal data from farm, visit, and similar milk production were used. In particular, local equations reduced RSEP by 43% and increased R² by 15%, on average, compared with those obtained from individual data. The low RSEP (4%), high R² (0.96), and good ratio performance deviation (RPD = 5) illustrated the excellent accuracy and robustness of the local equations. Findings suggest the ability of fecal NIRS to successfully and more accurately predict diet properties (intake, quality, and digestibility) with local calibration techniques compared with classic global techniques, especially on an averaged data set. Local calibration techniques represent an alternative promising method and potentially a decision support tool to decide whether diets meet dairy cattle requirements or need to be modified.     

Growth and body composition of young entire male pigs fed diets of differing ingredient composition and nutrient quality

Twenty-eight pairs of entire male Large White pigs of 5.59 kg liveweight were grown to 25 kg. They were offered two diets of different nutrient density and ingredient content: the diets (S and C) contained 16 and 15 MJ DE (digestible energy) and 235 and 214 g CP (crude protein) kg^?1 dry matter, respectively. A liveweight of 25 kg was reached in 43.4 days by pigs given diet S and in 57.5 days by pigs given diet C (P < 0.001). Total feed intakes were 33.6 and 42.5 kg( P < 0.001), respectively, but differences in daily feed intake (0.81 and 0.76 kg) were not significant. Chemical composition of the empty body was not affected by nutritional regime (12.4% lipid, 15.8% protein). The mean daily rates of protein deposition over the 5.59 to 25 kg growth phase were 64 g (S) and 55 g (C).     

Technical note: validation of a system for monitoring individual feeding and drinking behavior and intake in group-housed cattle

The objective of this study was to validate a system for monitoring individual feeding and drinking behavior and intake in group-housed cattle. A total of 42 Holstein cows were tested with access to 24 feed bins and 4 water bins. For the purposes of this validation experiment, we focused our observations on 4 water bins and 13 feed bins. When the cow approached the feed or water bin, an antenna detected the cow's unique passive transponder and lowered the barrier, allowing the cow access to the feed or water. For each visit to the bin, the system recorded the cow number, bin number, initial and final times and weight and calculated the visit duration and intake. Bins were also monitored by direct observation and time-lapse video recording for 2 d per bin, with observations for 4 and 6 h/d for the feed and water bins, respectively. Data from direct observations were compared with the electronic data recorded by the system. Feed disappearance over 24 h was assessed by using an external scale over 3 consecutive 24-h periods, and these values were compared with the sum of intakes across all visits to that bin for the same time periods. The system showed a high specificity (100%) and sensitivity (100 and 99.76% for the feed and water bins, respectively) for cow identification. The duration of the feeding and drinking visits and the feed and water intake per visit, as estimated by the monitoring system, were highly correlated with those obtained by direct observation (R² ≥ 0.99 in all the cases). The comparison of the total feed that disappeared from each bin in 24 h with the sum of the feed cows consumed from that bin during the same period differed by less than 1 kg (29.92 ± 0.90 kg and 29.24 ± 0.90 kg as estimated by manual weighing and by the electronic system, respectively). This difference could be attributed to changes in feed moisture during the 24-h period. In conclusion, this electronic system is a useful tool for monitoring intakes and feeding and drinking behavior of loose-housed cows.     

Determination of copper in fish feed by graphite furnace atomic absorption spectrometry using slurry sampling

The present work develops and optimizes a method to determine copper in samples of feces and fish feed by graphite furnace atomic absorption spectrometry (GFAAS) through the direct introduction of slurries of the samples into the spectrometer’s graphite tube coated internally with metallic rhodium and tungsten carbide that acts as chemical modifiers. The limits of detection (LOD) and quantification (LOQ) calculated for 20 readings of the blank of the standard slurries (0.50% m/v of feces or feed devoid of copper) were 0.24 and 0.79 μg L⁻¹ for the standard feces slurries and 0.26 and 0.87 μg L⁻¹ for the standard feed slurries. The proposed method was applied in studies of absorption of copper in different fish feeds and their results proved compatible with that obtained from samples mineralized by acid digestion using microwave oven.     

GFAAS Determination of Zinc in Fish Feed and Feces Using Slurry Sampling

This paper presents a simple, fast, and sensitive method to determine zinc in samples of feces and fish feed by electrothermal atomic absorption spectrometry through the direct introduction of slurries of the samples into the spectrometer’s graphite tube. The procedure is based on the injection of 10 μL of an acidified aqueous solution containing 0.50% w/v of feces or feed and 0.50% v/v HNO₃ into graphite tube. The limits of detection and quantification calculated for 20 readings of the blank of the standard slurries (0.50% w/v of feces or feed devoid of zinc) were 0.04 and 0.13 μg L⁻¹ for the standard feces slurries and 0.05 and 0.17 μg L⁻¹ for the standard feed slurries. The proposed method was applied in studies of digestibility of zinc in different fish feeds, and their results proved compatible with that obtained from samples mineralized by acid digestion using microwave oven.     

The use of mid-infrared spectrometry to estimate the ration composition of lactating dairy cows

The composition of cow milk is strongly affected by the feeding regimen. Because milk components are routinely determined using mid-infrared (MIR) spectrometry, MIR spectra could also be used to estimate an animal's ration composition. The objective of this study was to determine whether and how well amounts of dry matter intake and the proportions of concentrates, hay, grass silage, maize silage, and pasture in the total ration can be estimated using MIR spectra at an individual animal level. A total of 10,200 milk samples and sets of feed intake data were collected from 90 dairy cows at 2 experimental farms of the Agricultural Research and Education Centre in Raumberg-Gumpenstein, Austria. For each run of analysis, the data set was split into a calibration and a validation data set in a 40:60 ratio. Estimated ration compositions were calculated using a partial least squares regression and then compared with the respective observed ration compositions. In separate analyses, the factors milk yield and concentrate intake were included as additional predictors. To evaluate accuracy, the coefficient of determination (R²) and ratio to performance deviation were used. The highest R² values (for kg of dry matter intake/for % of ration) for the individual feedstuffs were as follows: pasture, 0.63/0.66; grass silage, 0.32/0.43; concentrate intake, 0.39/0.34; maize silage, 0.32/0.33; and hay, 0.15/0.16. Estimation of groups of feedstuffs (forages, energy-dense feedstuffs) mostly resulted in R² values >0.50. Including the parameters milk yield or concentrate intake improved R² values by up to 0.21, with an average improvement of 0.04. The results of this study indicate that not all ration components may be estimated equally accurately. Even if some estimates are good on average, there may be strong deviations between estimated and observed values in individual data sets, and therefore individual estimates should not be overemphasized. Further research including pooled samples (e.g., bulk milk, farm samples) or variations in ration composition is called for.     

Prediction and validation of residual feed intake and dry matter intake in Danish lactating dairy cows using mid-infrared spectroscopy of milk

The present study explored the effectiveness of Fourier transform mid-infrared (FT-IR) spectral profiles as a predictor for dry matter intake (DMI) and residual feed intake (RFI). The partial least squares regression method was used to develop the prediction models. The models were validated using different external test sets, one randomly leaving out 20% of the records (validation A), the second randomly leaving out 20% of cows (validation B), and a third (for DMI prediction models) randomly leaving out one cow (validation C). The data included 1,044 records from 140 cows; 97 were Danish Holstein and 43 Danish Jersey. Results showed better accuracies for validation A compared with other validation methods. Milk yield (MY) contributed largely to DMI prediction; MY explained 59% of the variation and the validated model error root mean square error of prediction (RMSEP) was 2.24 kg. The model was improved by adding live weight (LW) as an additional predictor trait, where the accuracy R² increased from 0.59 to 0.72 and error RMSEP decreased from 2.24 to 1.83 kg. When only the milk FT-IR spectral profile was used in DMI prediction, a lower prediction ability was obtained, with R² = 0.30 and RMSEP = 2.91 kg. However, once the spectral information was added, along with MY and LW as predictors, model accuracy improved and R² increased to 0.81 and RMSEP decreased to 1.49 kg. Prediction accuracies of RFI changed throughout lactation. The RFI prediction model for the early-lactation stage was better compared with across lactation or mid- and late-lactation stages, with R² = 0.46 and RMSEP = 1.70. The most important spectral wavenumbers that contributed to DMI and RFI prediction models included fat, protein, and lactose peaks. Comparable prediction results were obtained when using infrared-predicted fat, protein, and lactose instead of full spectra, indicating that FT-IR spectral data do not add significant new information to improve DMI and RFI prediction models. Therefore, in practice, if full FT-IR spectral data are not stored, it is possible to achieve similar DMI or RFI prediction results based on standard milk control data. For DMI, the milk fat region was responsible for the major variation in milk spectra; for RFI, the major variation in milk spectra was within the milk protein region.     

Nitrogen partitioning and isotopic fractionation in dairy cows consuming diets based on a range of contrasting forages

Nine multiparous Holstein-Friesian cows (initially 97 d in milk), were used in a 3 × 3 lattice square design experiment with 4-wk periods. All cows received 4 kg/d concentrates and dietary treatments were based on silages offered ad libitum: perennial ryegrass (PRG); timothy (TIM); tall fescue (TF); red clover (RC); red clover/corn silage mixture [40/60 on a dry matter (DM) basis; RCC]; red clover/whole-crop oat silage mixture (40/60 on a DM basis; RCO); or red clover/whole-crop oat silage mixture (25/75 on a DM basis; ORC). The remaining treatments were based on RCO with feed intake restricted to the level of PRG (RCOr) or with a low protein concentrate (50/50 mixture of barley and molassed sugar beet pulp; RCOlp). Experiment objectives were to evaluate diet effects on N partitioning and N isotopic fractionation. Yields of milk and milk protein were consistently high for diets RC, RCC, and RCO and low for the diets based on poorly ensiled grass silages. Restriction of intake (RCOr) and inclusion of a higher proportion of whole-crop oat silage (ORC) and the low-protein concentrate (RCOlp) led to some loss of production. Diet had little effect on milk fat, protein, and lactose concentrations: low concentrations of milk protein and lactose reflect the restricted energy intakes for all treatments. The highest diet digestibilities were measured for RC and PRG, whereas increasing inclusion of the whole-crop oat silage (0, 60, and 75% of forage DM) led to a marked decrease in diet digestibility (0.717, 0.624, and 0.574 g/g, respectively). Urinary excretion of purine derivatives, an indicator for rumen microbial protein synthesis, was significantly higher for RCC than for TIM and TF. Nitrogen intake ranged between 359 and 626 g/d (treatment means). Partitioning of N intake to feces and urine was closely related to N intake, although urinary N losses were less than predicted from N intake for the 60/40 mixtures of cereal silage and red clover silage. The ¹⁵N content of milk, urine, and feces were all influenced by diet ¹⁵N content. Isotopic fractionation meant that feces and milk were enriched and urine was depleted in ¹⁵N relative to the diet. Significant relationships were observed between the extent of enrichment of urine, feces, and milk, suggesting some commonality in fractionation pathways. The trend for the lowest ¹⁵N enrichment in milk protein occurring in diets with low N-use efficiency (milk N/feed N) was contrary to expectations, possibly because of endogenous contributions to milk protein or fractionation when dietary ammonia was incorporated into microbial protein.     

Relationships among manure nitrogen output and dietary and animal factors in lactating dairy cows

A large data set derived from total diet digestibility assessments on lactating dairy cows (535 Holstein-Friesian and 29 Norwegian) was used to examine effects of dietary and animal factors on manure (feces and urine) nitrogen (N) output and to develop mitigation strategies and prediction equations for manure N output in lactating dairy cows. Manure N output was positively and significantly related to live weight, milk yield, dietary crude protein (CP) concentration, dry matter intake, and N intake. Reducing the dietary CP concentration or increasing the milk yield decreased manure N output per kilogram of milk yield. Prediction equations for manure N output using live weight and milk yield, either alone or combined, had relatively low R² (0.227 to 0.474) and large standard error (70.6 to 85.6) values. Addition of dietary CP concentration to these relationships considerably increased R² to 0.754 and reduced the standard error to 48.2. Relating manure N output to N intake produced a very high r² (0.901) and a very low standard error (30.6). The addition of live weight and milk yield to this relationship as supporting predictors only marginally increased R² to 0.910 and reduced the standard error to 29.3. The internal validation of these equations revealed that use of N intake as the primary predictor produced a very accurate prediction of manure N output. In situations in which data on N intake are not available, prediction equations based on dietary CP concentration, live weight, and milk yield together can produce a relatively accurate assessment of manure N output.     

贻贝、牡蛎复合物对肠道菌群紊乱型小鼠便秘的干预作用

本研究探讨了贻贝、牡蛎复合物对抗生素诱导小鼠便秘的干预作用,采用混合抗生素溶液灌胃C57BL/6雌性小鼠,构建肠道菌群紊乱型小鼠便秘模型（ME）,以0.02 mL/g?bw贻贝、牡蛎复合物灌胃ME组小鼠为干预组（IC）。结合16s RNA基因测序技术,7 d后,测定小肠推进率、排便量、饲料消耗量、肠道菌群结构等指标,评估小鼠便秘模型及其贻贝、牡蛎复合物的干预作用。对比空白组,ME组小肠推进率下降22.89%（p<0.05）,排便量降低41.00%（p<0.05）,日平均饲料消耗量显著下降2.68 g/d（p<0.05）,粪便含水率显著下降19.40%（p<0.05）,同时,ME组肠道菌群有益菌多样性减少,表现为Prevotella-9、Lachnospiraceae、Enterobacter、Verrucomicrobia等有益菌菌群丰度降低;经贻贝、牡蛎复合物干预后,对比ME组,IC组小鼠小肠推进率提升70.00%（p<0.05）,排便量提升52.00%（p<0.05）,粪便含水率显著增加18.10%（p<0.05）,IC组肠道菌群多样性增加,表现为Proteobacteria、Fusobacteria、Akkermansia、Bacteroidetes、Verrucomicrobia丰度增加,同时IC组肠道菌群结构恢复至与空白组小鼠相似。综上,贻贝、牡蛎复合物可显著改善由抗生素导致的便秘小鼠的小肠推进率等小肠蠕动功能,增加小鼠排便,并提高粪便含水率,同时调节便秘小鼠的肠道菌群结构及组成,增加Akkermansia等肠道有益菌。     

Technical note: Estimation of feed intake while grazing using a wireless system requiring no halter

A simple, compact bite counter was used to record dairy cow jaw movements. This information was used to estimate feed intake. The device is composed of a pendulum, a microcontroller, and a transmitter attached to a collar. The microcontroller memory can store the number of bites over 10-min intervals for up to 3 mo and has a battery life of more than 1 yr. The number of bites measured by personal observation, and the values reported by the counter were compared for 5 multiparous, nonlactating Holstein cows. The correlation was linear with an R² value of 0.9, unaffected by rumination, and little affected by walking. The collar system avoided the problems often experienced with counters attached to halters. The utility of the bite counter recordings in estimating intake was tested using 8 multiparous lactating cows. The slopes of the regression lines relating the number of bites to feed intake were dependent on the level of available pasture mass (120 or 190 g standing dry matter/m²). The feed intake could be estimated by applying linear regression to the number of bite counts versus pasture disappearance. In both cases the R² values of the regression lines were >0.7. Although the counter recorded jaw movements during grazing when the head was down, it did not record rumination or mastication when the head was raised because the counter/collar did not contact the jaw in this position. The bite counters were easy to attach to the cows using the collar and could be used effectively by farmers and researchers.     

复合苦荞粉通便作用的研究

通过对小鼠做通便药效试验,研究复合苦荞粉的通便作用。以小鼠为试验对象,随机分为5组,即空白对照组、模型对照组和复合苦荞粉低、中、高3个剂量组。采用复方地芬诺酯灌胃建立小鼠便秘模型,通过测定小肠推进率、首次排黑便时间、排黑便粒数以及排黑便质量,判断复合苦荞粉对小鼠肠道蠕动和排便功能的影响。在连续灌胃14 d后,高剂量组小鼠的墨汁推进显著高于模型对照组(p0.05);高剂量组的小鼠排黑便粒数高于模型对照组,呈极显著差异(p0.01),低、中剂量组的排黑便粒显著高于模型对照组(p0.05);各剂量组的排黑便质量均极显著高于模型对照组(p0.01);而首次排黑便时间各剂量组与模型组之间无显著差异。复合苦荞粉能有效增强肠道蠕动并促进排便,改善便秘。