Short communication: Risk of subacute ruminal acidosis affects the feed sorting behavior and milk production of early lactation cows

The objective of this study was to determine if the risk of developing subacute ruminal acidosis, as potentially affected by dietary straw particle size, influenced the feed sorting, rumination behavior, and milk production of early lactation dairy cows. Upon calving, 41 multiparous Holstein cows were fed a total mixed ration with 9% wheat straw (dry matter basis) chopped (1) using a 2.54-cm screen (short; n = 21) or (2) using a 5.08-cm screen (long; n = 20). For the first 4 wk following calving, rumination behavior (recorded using data loggers attached to neck collars) and reticulorumen pH (recorded using wireless telemetry boluses) were monitored 24 h/d. Due to technical failures, analyses were conducted on 38 cows (n = 19 per treatment). Total mixed ration and orts samples were collected every 3 d to determine feed sorting. Based on an acidosis index, created using area under the curve data (reticulorumen pH < 5.8) normalized for dry matter intake, cows were categorized as either low (LR) or high (HR) risk for developing subacute ruminal acidosis (SARA). Low risk cows had higher mean (6.3 vs. 6.1), minimum (6.0 vs. 5.7), and maximum (6.7 vs. 6.5) reticulorumen pH than HR cows. Low risk cows also had less severe area under the curve values (1.5 vs. 49.4 pH × min/d) and spent less time below a reticulorumen pH threshold of 5.8 (21.9 vs. 309.2 min/d). Although total milk yield was unaffected by SARA risk, LR cows produced more 4% fat-corrected milk (47.2 vs. 41.9 kg/d) and milk fat (2.1 vs. 1.8 kg/d) than HR cows. A SARA risk category × treatment interaction was detected for sorting all fractions of the diet; HR cows on the long treatment sorted against the longest particles in the diet, whereas LR cows on the same treatment did not sort this fraction, suggesting that SARA risk may be mitigated by a more balanced intake of physically effective fiber. High risk cows on the short treatment consumed the longest dietary particles as predicted, and sorted in favor of the physically effective medium and short particles. A SARA risk category × treatment interaction was detected for rumination behavior; within the long treatment, HR cows tended to ruminate less than LR cows (432.3 vs. 493.2 min/d). Overall, these results suggest that LR cows consumed a more balanced diet, whereas HR cows sorted their feed more, particularly when fed the diet containing long straw particles, which may have led to reduced rumination activity and yield of milk fat and fat-corrected milk.     

Network tomography from measured end-to-end delay covariance

End-to-end measurement is a common tool for network performance diagnosis, primarily because it can reflect user experience and typically requires minimal support from intervening network elements. However, pinpointing the site of performance degradation from end-to-end measurements is a challenging problem. We show how end-to-end delay measurements of multicast traffic can be used to infer the under-lying logical multicast tree and the packet delay variance on each of its links. The method does not depend on cooperation from intervening network elements; multicast probing is bandwidth efficient. We establish desirable statistical properties of the estimator, namely consistency and asymptotic normality. We evaluate the approach through simulations, and analyze its failure modes and their probabilities.     

The effect of prepartum feeding and lying space on metabolic health and immune function

The determinants of metabolic and reproductive health disorders in the peripartum period and the degree to which feeding and lying space and management can influence health are only partially understood. The objective of this randomized controlled study was to determine whether providing noncompetitive feeding and lying access in the close-up dry period improves health and immune function. Forty-eight Holstein cows of all parities were randomly assigned to a treatment group of 6 to 10 cows in 1 pen with either 80% cows to stalls and 90 cm of feeding space per cow (understocked) or 120% stocking density and 45 cm of feeding space per cow (overstocked) for 3 wk before expected calving. All cows wore electronic data loggers to monitor daily standing and lying time. Video recordings representing d 7 to 9 after group formation were reviewed, and a competition index (C_Ind) was calculated for each cow by dividing the number of times a cow displaced another as an actor by its total number of actor and reactor displacements. Cows were categorized as high success (C_Ind ≥0.6), moderate success (0.4 ≤ C_Ind <0.6), or low success (C_Ind <0.4). Weekly blood samples measured nonesterified fatty acids, β-hydroxybutyrate, calcium, glucose, albumin, aspartate aminotransferase, bilirubin, haptoglobin, insulin, and insulin-like growth factor-1 from 3 wk before to 5 wk after calving. Measures of innate immune function (neutrophil phagocytosis and oxidative burst) were assessed at ?2, ?1, 1, 2, 3, and 5 wk relative to calving. Liver biopsies were collected at wk 1 and 3. Cows in the understocked group spent significantly more time per day lying; the back-transformed least squares means and 95% confidence interval were 14.8 h (13.9–15.6) versus 12.8 h (12.0–13.7). Controlling for parity, there was no difference between treatments in β-hydroxybutyrate, nonesterified fatty acids, glucose, insulin, insulin-like growth factor 1, aspartate aminotransferase, bilirubin, or haptoglobin concentrations. Throughout the study, cows in the understocked treatment had higher mean calcium and tended to have higher albumin and at 3 wk after calving tended to have lower mean liver triacylglycerol content. Overall, there was no treatment effect on phagocytosis, but cows with a higher C_Ind in the understocked treatment group had greater oxidative burst function. There was no effect of treatment on endometritis. Despite increased competition and lower lying time, the expected harmful effects of crowding and competition on metabolic indicators and innate immune function were mostly not observed. Although this does not refute the importance of access to feeding and lying space, these results indicate that metabolic and reproductive health is more complex than can be explained solely by exposure to what are understood to be best practices for space allowances.     

The use of end-to-end multicast measurements for characterizinginternal network behavior

We present a novel methodology for identifying internal network performance characteristics based on end-to-end multicast measurements. The methodology, solidly grounded on statistical estimation theory, can be used to characterize the internal loss and delay behavior of a network. Measurements on the MBone have been used to validate the approach in the case of losses. Extensive simulation experiments provide further validation of the approach, not only for losses, but also for delays. We also describe our strategy for deploying the methodology on the Internet. This includes the continued development of the National Internet Measurement Infrastructure to support RTP-based end-to-end multicast measurements and the development of software tools to analyze the traces. Once complete, this combined software/hardware infrastructure will provide a service for understanding and forecasting the performance of the Internet     

Randomized clinical field trial on the effects of butaphosphan-cyanocobalamin and propylene glycol on ketosis resolution and milk production

The purpose of this study was to determine the effects of a butaphosphan-cyanocobalamin combination product (B+C) and 2 durations of propylene glycol treatment (PG; 3 versus 5 d) on ketosis resolution and early lactation milk yield. Cows from 9 freestall herds (8 in Ontario and 1 in Michigan) were tested at weekly intervals between 3 and 16 d in milk. Ketosis was defined as blood β-hydroxybutyrate (BHB) ≥1.2 mmol/L. Ketotic cows were randomly assigned to treatment with 25 mL of B+C or 25 mL of saline placebo for 3 d and 3 or 5 d of 300 g of PG orally in a 2 × 2 factorial arrangement. Outcomes evaluated for all farms included ketosis cure (blood BHB <1.2 mmol/L at 1 wk after enrollment), maintenance of ketosis cure (blood BHB <1.2 mmol/L 1 and 2 wk after enrollment), and blood BHB concentrations at 1 and 2 wk after enrollment. Daily milk weights were collected in 3 herds. Poisson regression was used to evaluate cure and maintenance of cure, whereas repeated-measures ANOVA was used to evaluate blood BHB concentrations in the 2 wk after enrollment and average daily milk production in the 30 d after treatment. A total of 594 animals were enrolled in the study with 124 treated with B+C and 5 d of PG, 176 treated with B+C and 3 d of PG, 128 treated with saline and 5 d of PG, and 166 treated with saline and 3 d of PG. Animals with blood BHB >2.4 mmol/L at the time of enrollment were 1.7 times more likely [95% confidence interval (CI): 1.4 to 2.2] to cure and had a decrease of 0.25 ± 0.11 mmol/L blood BHB at 1 wk after enrollment if treated with 5 d of PG compared with 3 d, though this response was not seen in animals with BHB of 1.2 to 2.4 mmol/L at enrollment. Cows with blood glucose concentrations <2.2 mmol/L at enrollment produced 3.1 kg/d (95% CI: 1.3 to 5.0) more milk if treated with B+C and 3.4 kg/d (95% CI: 1.7 to 5.1) more milk if treated with 5 d of PG compared with their respective controls. This response was not seen in animals with blood glucose ≥2.2 mmol/L at enrollment and there was no interaction between treatments. These results indicate that extended PG treatment is beneficial in decreasing blood BHB concentrations in more severely affected animals. Additionally, both B+C treatment and extended PG treatment improved milk yield in animals with low blood glucose at the time of ketosis diagnosis.     

Prepartum monensin for the reduction of energy associated disease in postpartum dairy cows

A total of 1317 Holstein cows from 45 farms in the Canadian provinces of Quebec, Prince Edward Island (PEI) and Ontario were enrolled in a randomized trial during 1998 and 1999 to further confirm the efficacy of a monensin controlled release capsule in preventing periparturient disease in lactating dairy cows. Cows were randomized on the farms to receive either a monensin controlled release capsule (CRC) 2 to 4 wk before expected calving or to serve as negative controls. Health data were collected for 90 d postcalving and were analyzed with logistic regression accounting for the intraherd correlation with generalized estimating equations. Monensin CRC significantly reduced the incidence of both clinical ketosis and abomasal displacement post-calving. There was a numerical but nonsignificant decrease in the incidence of retained placenta in cows receiving a monensin CRC. A pooled analysis of two separate but similar studies (conducted in 1995 and 1998) demonstrated a strengthened association between monensin CRC administration precalving and reduced periparturient disease. A 40% reduction in both abomasal displacement and clinical ketosis was observed with precalving administration of a monensin CRC. In addition, the larger dataset highlighted a trend for a 25% reduction in the incidence of retained placenta in monensin-treated cows. Improved energy metabolism as a result of monensin treatment is likely the mechanism for the reduction in incidence of all three of these diseases. Thus the term "energy associated disease" was created to assess the combined impact of the precalving monensin treatment on the incidence of retained placenta, displaced abomasum, and clinical ketosis. The monensin controlled release capsule reduced the incidence of energy associated disease by 30%.     

Entrainment of the circadian system of mammals by nonphotic cues

Although light is the principal zeitgeber to the mammalian circadian system, other cues can be shown to have a potent resetting effect on the clock of both adult and perinatal mammals. Nonphotic entrainment may have both biological and therapeutic significance. This review focuses on the effect of behavioral arousal as a nonphotic cue and the neurochemical circuitry that mediates arousal-induced entrainment in the adult rodent. In addition, it considers the role of nonphotic entrainment of the developing circadian system in perinatal life prior to the establishment of retinal input to the clock.     

The relationship between Internet identification,Internet anxiety and Internet use

This paper reports a study investigating the relationship between Internet identification, Internet anxiety and Internet use. The participants were 446 students (319 females and 127 males) from two universities in the UK and one university in Australia. Measures of Internet identification and Internet anxiety were developed. The majority of participants were NOT anxious about using the Internet, although there were approximately 8% who showed evidence of Internet anxiety. There was a significant and negative relationship between Internet anxiety and Internet use. Those who were more anxious about using the Internet used the Internet less, although the magnitude of effect was small. There was a positive and significant relationship between Internet use and Internet identification. Those who scored high on the measure of Internet identification used the Internet more than those who did not. There was also a significant and negative relationship between Internet anxiety and Internet identification. Finally, males had a significantly higher Internet identification score than females. Implications of these findings are discussed.     

Short communication: Effects of a monensin premix on milk fatty acid content during subacute ruminal acidosis in dairy cows

The effects of a monensin premix on milk fatty acid content during grain-induced subacute ruminal acidosis (SARA) in Holstein cows receiving a total mixed ration was investigated. Six multiparous, rumen-fistulated Holstein cows were used in a two-treatment, two-period crossover design with 6-wk periods. Experimental treatments were either a monensin premix or a placebo premix. At the beginning of wk 4, SARA was induced in experimental cows for a 10-d period using a grain challenge model. The administration of a monensin premix elevated milk fat proportion of total short-chain saturated fatty acids (sum of C4 to C15). Milk fat proportions of conjugated linoleic acid isomers were unaffected. Linolenic acid (C18:3n3) proportion in milk fat of monensin-treated cows were lower when compared with placebo-treated cows during the SARA period. Results from this study indicate that dietary supplementation with monensin during SARA had little effect on milk fatty acid content.