Stage of lactation and corresponding diets affect in situ protein degradation by dairy cows.

The influence of stage of lactation and corresponding diets on rates of protein degradation (kd) is largely unstudied. Study objectives were to measure and compare in situ ruminal kd of crude protein (CP) and estimate rumen CP escape (rumen-undegradable protein; RUP) of selected feeds by cows at 3 stages of lactation fed corresponding diets, and to determine the incubation times needed in an enzymatic in vitro procedure, using 0.2 units of Streptomyces griseus protease per percent of true CP, that predicted in situ RUP. Residue CP was measured after in situ fermentation for 4, 8, 12, 24, 36, 48, and 72 h of 5 protein sources and 3 total mixed rations, which were fed to the in situ cows. Two nonlactating (dry) cows and 2 cows each at 190 (mid) and 90 (peak) days of lactation were used. Each pair of cows was offered free-choice diets that differed in composition to meet their corresponding nutrient requirements. Diets had decreasing proportions of forages and contained (dry matter basis) 11.9, 15.1 and 16.4% CP and 54.3, 40.3 and 35.3% neutral detergent fiber, for dry, mid, and peak TMR (TMR1, TMR2, and TMR3), respectively. Intakes were 10.3, 21.4, and 23.8kg of dry matter/d, respectively. Kinetic CP fractions (extractable, potentially degradable, undegradable, or slowly degradable) were unaffected by treatment. Lag time and kd varied among feeds. The kd was faster for all feeds (0.136/h) when incubated in dry-TMR1 cows compared with mid-TMR2 (0.097/h) or peak-TMR3 (0.098/h) cows, and no differences in lag time were detected. Calculated RUP, using estimated passage rates for each cow based on intake, differed between dry-TMR1 (0.382) and mid-TMR2 (0.559) or peak-TMR3 (0.626) cows, with a tendency for mid-TMR2 to be different from peak-TMR3. Using the average kd and lag time obtained from dry-TMR1 to calculate RUP for mid-TMR2 and peak-TMR3 cows using their passage rates reduced RUP values by 6.3 and 9.5 percentage units, respectively. Except for that of herring meal, in vitro residue CP at 6, 12, and 48h of enzymatic hydrolysis was correlated (r=0.90) with in situ RUP of peak-TMR3, mid-TMR2, and dry-TMR1, respectively. Although confounded within treatments, stage of lactation, diet, and intake appeared to affect CP degradation parameters and RUP. Using kd from nonlactating cows, or the RUP calculated from them, may bias diet evaluation or ration formulation for lactating cows. In addition, enzymatic in vitro predictions of RUP should be measured using incubation times that are appropriate for lactating cows.

Association of total mixed ration particle fractions retained on the Penn State Particle Separator with milk, fat, and protein yield lactation curves at the cow level.

As part of a larger project aiming to develop management evaluation tools based on results from test-day (TD) models, the objective of this study was to examine the effect of physical composition of total mixed rations (TMR) tested quarterly from March 2006 through December 2008 on milk, fat, and protein yield curves for 25 herds in Ragusa, Sicily. A random regression sire-maternal grandsire model was used to estimate variance components for milk, fat, and protein yields fitted on a full data set, including 241,153 TD records from 9,809 animals in 42 herds recorded from 1995 through 2008. The model included parity, age at calving, year at calving, and stage of pregnancy as fixed effects. Random effects were herd × test date, sire and maternal grandsire additive genetic effect, and permanent environmental effect modeled using third-order Legendre polynomials. Model fitting was carried out using ASREML. Afterward, for the 25 herds involved in the study, 9 particle size classes were defined based on the proportions of TMR particles on the top (19-mm) and middle (8-mm) screen of the Penn State Particle Separator. Subsequently, the model with estimated variance components was used to examine the influence of TMR particle size class on milk, fat, and protein yield curves. An interaction was included with the particle size class and days in milk. The effect of the TMR particle size class was modeled using a ninth-order Legendre polynomial. Lactation curves were predicted from the model while controlling for TMR chemical composition (crude protein content of 15.5%, neutral detergent fiber of 40.7%, and starch of 19.7% for all classes), to have pure estimates of particle distribution not confounded by nutrient content of TMR. We found little effect of class of particle proportions on milk yield and fat yield curves. Protein yield was greater for sieve classes with 10.4 to 17.4% of TMR particles retained on the top (19-mm) sieve. Optimal distributions different from those recommended may reflect regional differences based on climate and types and quality of forages fed.

How do dairy cows chew?--particle size analysis of selected feeds with different particle length distributions and of respective ingested bolus particles.

Not only feed but also respective bolus particle size could alter diet efficiency and cow performance. The objective of this project was to characterize particle size of selected feeds and respective swallowed boli. Feed samples included 6 different particle length rye grass hay samples, 1 grass silage, 1 corn silage, and 1 total mixed ration (TMR). Rye grass hay samples consisted of long hay and chopped hay particles retained on the 19- (19_PSPS hay), 8- (8_PSPS hay), and 1.18-mm (1.18_PSPS hay) Penn State Particle Separator (PSPS) screens and those collected on the pan (PSPS_pan hay). A sixth hay treatment was rye grass forage cut at 50-mm lengths and dried to hay (50-mm hay). Treatments were offered to 4 nonlactating and 4 lactating cows following rumen evacuation. Swallowed boli were collected and the number of chews per gram of ingested feed dry matter was determined. Feed and bolus particles of lengths ≥5mm were collected on a 1.6-mm screen using a horizontal wet sieving technique. This cut point was chosen, as the literature suggests that most fecal particles are shorter than 5mm. Dry matter proportions on this screen (PROP_1.6) were determined and particle lengths of retained particles were measured by image analysis. Mean particle lengths (ML) were calculated considering particles ≥5mm in length. Boli of long hay, of 19_PSPS hay, of 8_PSPS hay, and of 50-mm hay had similar ML of 10 to 11mm. Bolus PROP_1.6 were also similar between these treatments, ranging from 0.54 to 0.69. Bolus particle lengths and distributions of these treatments were not related to respective hay particles. Bolus of 1.18_PSPS hay had PROP_1.6 of 0.51 and a smaller ML of 8mm. The PSPS_pan hay had PROP_1.6 of only 0.33, but was still chewed intensely. Apparently, little particle size reduction occurred when cows ate the TMR or the silages. Feed and respective bolus PROP_1.6 were as follows: 0.66 and 0.59 in grass silage, 0.52 and 0.55 in corn silage, and 0.44 and 0.38 in the TMR. Feed and respective bolus ML were as follows: 13.8 and 11.6mm in grass silage, 12.0 and 11.2mm in corn silage, and 13.1 and 12.5mm in the TMR. Rye grass hay particles retained on PSPS screens ≥8mm, with ML of at least 25mm were longer compared with TMR particles, but respective bolus particles were shorter. Bolus particle size is not associated with the size of large feed particles chewed to a constant size that is appropriate for deglutition. This size may be related to feed chemical composition.

Objective estimation of body condition score by modeling cow body shape from digital images.

Body condition score (BCS) is considered an important tool for management of dairy cattle. The feasibility of estimating the BCS from digital images has been demonstrated in recent work. Regression machines have been successfully employed for automatic BCS estimation, taking into account information of the overall shape or information extracted on anatomical points of the shape. Despite the progress in this research area, such studies have not addressed the problem of modeling the shape of cows to build a robust descriptor for automatic BCS estimation. Moreover, a benchmark data set of images meant as a point of reference for quantitative evaluation and comparison of different automatic estimation methods for BCS is lacking. The main objective of this study was to develop a technique that was able to describe the body shape of cows in a reconstructive way. Images, used to build a benchmark data set for developing an automatic system for BCS, were taken using a camera placed above an exit gate from the milking robot. The camera was positioned at 3 m from the ground and in such a position to capture images of the rear, dorsal pelvic, and loin area of cows. The BCS of each cow was estimated on site by 2 technicians and associated to the cow images. The benchmark data set contained 286 images with associated BCS, anatomical points, and shapes. It was used for quantitative evaluation. A set of example cow body shapes was created. Linear and polynomial kernel principal component analysis was used to reconstruct shapes of cows using a linear combination of basic shapes constructed from the example database. In this manner, a cow's body shape was described by considering her variability from the average shape. The method produced a compact description of the shape to be used for automatic estimation of BCS. Model validation showed that the polynomial model proposed in this study performs better (error=0.31) than other state-of-the-art methods in estimating BCS even at the extreme values of BCS scale.

Prevalence of mastitis pathogens in Ragusa, Sicily, from 2000 to 2006.

The objective of this study was to report the prevalence of intramammary infections (IMI) in Ragusa, Sicily, from milk samples (n = 18,711) collected between October 2000 and June 2006 from 101 dairy herds. Milk samples were collected at 9,747 cow sampling events from 5,285 individual cows. Samples were individual quarter (92.8%) or composite samples (7.2%) from an individual cow. Logistic regression was used to examine the prevalence of IMI at the level of milk sample and at the level of cow, controlling for year and season of collection, type of sample (individual quarter or composite), and type of housing and bedding of the cow at the time of collection. Bedding and housing types were as follows, respectively (number of herd groups): bedding: none (61), organic [51 (straw, 50; sawdust, 1)], and sand (3); housing: bedded pack (37), free stalls (57), tie stalls (4), and paddock (17). Raw prevalence of cow IMI for a sample event was as follows (percentage of cow samples): no growth, 47.4%; coagulase-negative staphylococci, 22.6%; Staphylococcus aureus, 20.6%; other Streptococcus spp., 11.1%; Streptococcus agalactiae, 2.3%; coliform bacteria, 2.9%; and other organisms, 5.8%. Prevalence of IMI differed by bedding type for Staph. aureus (none, 24.5%; organic, 12.7%; sand, 12.3%) and coagulase-negative staphylococci (none, 13.1%; organic, 27.4%; sand, 26.9%) but not for Streptococcus spp. or coliform bacteria. Prevalence of Streptococcus spp. IMI differed by housing type (tie stalls, 22.2%; bedded pack, 12.8%; free stalls, 8.4%; paddock, 7.1%). Housing was not associated with the prevalence of IMI for other bacteria. Herd monthly prevalence of Staph. aureus and Streptococcus spp. IMI was associated with decreased mean milk production (Staph. aureus, -1.42 kg/d per cow, SEM 0.51; Streptococcus spp., -1.31 kg/d per cow, SEM 0.64) and increased mean linear score (Staph. aureus, 1.01 units/d per cow, SEM 0.16; Streptococcus spp., 0.59 units/d per cow, SEM 0.22). Herds (n = 11) with a mean linear score (MLS) less than 3.3 units had the lowest prevalence of Staph. aureus IMI and monthly MLS and the greatest monthly mean milk production compared with other herds grouped by MLS [MLS 3.31 to 3.99 (n = 20), MLS 4.00 to 4.46 (n = 20), MLS >4.46 (n = 17), and MLS not available (n = 33)]. Implementation of a milk quality program to control gram-positive organisms is important for Ragusa.

Body condition assessment using digital images.

This project assessed the ability to assign a body condition score (BCS) to a dairy cow from digital photographs or videos. Images were taken from the rear of the cow at a 0 to 20 degrees angle relative to the tail head. Four observers assigned a BCS to each of 57 cows at a farm visit (live, farm 1) and later from a photograph (photo). Means +/- standard deviations of BCS by method and observer were as follows: live = 3.25 +/- 0.51, 3.42 +/- 0.49, 3.32 +/- 0.58, 3.13 +/- 0.62; photo = 3.36 +/- 0.52, 3.32 +/- 0.43, 3.44 +/- 0.62, 3.14 +/- 0.6 for observers 1 to 4, respectively. Body condition score means differed across observers for live (observer 2 higher and observer 4 lower, compared with observers 1 and 3) and photo methods (observer 3 lower, compared with observers 1, 2, and 3); however, within observer, the mean live BCS did not differ from the mean photo BCS. Correlation coefficients between BCS assigned live and from photos were 0.84, 0.82, 0.82, and 0.90 for observers 1 to 4, respectively. Subsequently, observer 1 visited 2 farms, assigned a live BCS, and digitally photographed 187 cows (56 and 131 cows from farms 2 and 3, respectively). Observers 2, 3, and 4 assigned a BCS from the photographs. Means +/- standard deviations of BCS by observer (method) were 1 (live) 3.35 +/- 0.55; 2 (photo) 3.33 +/- 0.49; 3 (photo) 3.60 +/- 0.54; and 4 (photo) 3.26 +/- 0.62. The mean BCS for observer 3 was higher and that for observer 4 was lower than for observers 1 and 2. Correlation coefficients between observer 1 and observers 2 through 4 were 0.78, 0.76, and 0.79, respectively. Observer 1 assigned a BCS to 41 cows at a farm visit and 3 wk later assessed the BCS of cows from a video taken at a farm visit by a different individual. Cows were restrained in headlocks at a feed bunk when assessing BCS and for video production. No difference was detected for the mean BCS, for the standard deviation of the mean BCS, or in the distribution of BCS between the live and video assessments. Mean and SD for 17 groups of Holstein cows from 20 farms were used to generate 10,000 random samples of BCS. Groups of 25, 50, 100, and 150 cows were created from the random samples, and estimates of mean BCS were determined by sampling 3 to 80% of the group. Estimates of mean BCS with a sample size of 30% or more from a group of cows fell within the 95% confidence limit of the true mean more than 98% of the time. Digital photographs provide adequate imaging for assessment of BCS. Sampling 30% of a group should be adequate to assess the mean BCS. Video imaging allowed a rapid assessment of BCS but did not permit identification of individual cows.

[Sterilization with ethylene oxide]. / La sterilizzazione con ossido di etilene.

In the above brief note, the authors discuss the validity of sterilization with ethylene oxide in hospital. The use of this agent requires most accurate attention by the operator and precise specific indication in view of the many negative factors which limit its widespread use, above all its marked toxicity and the fact that it is not easy to handle.

[The tasks and aims of prevention]. / Compiti e finalità della prevenzione.

The purpose of the above note was to offer an overall view of preventive medicine the fundamental object of which is the safeguard of the state of health before the manifestation of disease. Prevention is therefore closely related to epidemiology which looks for causes and identifies risk factors. These tasks must be performed with constant effort and tenacity on the one hand by the state via the necessary public health organizations (personnel, facilities, programming), and on the other by the community as well as by the individual citizen who, being the user and driving force, must take advantage of the benefits and at the same time work for better results through changes in his own behavior and lifestyle.

[Work at video display terminals]. / Il lavoro ai video-terminali.

The different problems connected with work at video-terminals are thoroughly discussed, and above all the preventive aspects both as to repercussions on the operator's health and as to a better relationship between operator and machine are set out. These aspects require the participation of a variety of specialists concerned with techniques, methods, and ergonomics, as well as norms, also with a view of the future given the ever wider use of computerized systems.

[Medical prevention of ocular risks caused by laser radiation]. / La prevenzione medica dei rischi oculari da radiazioni laser.

The authors examine prophylactic aspects of laser-induced injury in personnel dealing with these radiations, especially as far as ocular pathology and criteria of aptitude to work with these radiations from the point of view of function of the visual apparatus are concerned. The importance is stressed of a multidisciplinary approach as well as the need for close cooperation between specialists in ophthalmology and occupational medicine.

[The problem of radon pollution in closed environments]. / Il problema dell'inquinamento da radon negli ambienti confinati.

Radon is the most serious cause of human irradiation and can accumulate indoors in large quantities. The authors examine some aspects of human exposition to natural radioactivity, survey the Italian and international literature on indoor radon concentrations, and finally, set out some guidelines for prevention and control of radon pollution.