Prevalence of hock,knee, and neck skin lesions and associated risk factors in dairy herds in the Maritime Provinces of Canada

Skin lesions are commonly seen in dairy herds and have been associated with animal-, environmental-, and management factors. These lesions are not only a welfare concern, but they also affect profitability. Three areas on the cattle were examined for skin lesions: the hock, knee, and neck. Previous Canadian studies estimating the prevalence of lesions and the risk factors associated with them have not included the Maritime Provinces. In this study, 73 herds in the Maritime Provinces were chosen voluntarily to participate, with both tiestalls (n = 33) and freestalls (n = 40) represented. Within each herd, 67 to 90% of the lactating cows were selected and assessed for potential animal-, environmental-, and management-based risk factors. If producers were aware of the potential risk factors, this could help them reduce the prevalence in their herd. Leg lesions were scored on a 4-point scale (0–3) based on hair loss, swelling, and scabs, with a lesion defined as a score of 2 or 3 on at least 1 hock or knee. Necks were scored on a 3-point scale (0–2), with a lesion defined as score 2. For freestalls, the prevalence (95% confidence interval) of hock lesions was 39% (29–49%), knee lesions was 14% (11–18%), and neck lesions was 1% (<1–2%). Similarly, for tiestalls the prevalence (95% confidence interval) of hock lesions was 39% (33–46%), knee lesions was 17% (13–22%), and neck lesions was 5% (3–8%). Due to differences in management and methods of assessment between facility types, tiestalls and freestalls were analyzed separately. Due to dichotomization of cows as having a skin lesion or not, random-effects multivariable logistic regression was used to determine the risk factors for each lesion and facility type. Several environmental-based measurements, such as the stall base, type and dryness of bedding, and type of milking parlor, were associated with leg lesions. An environmental-based measurement that was associated with neck lesions was the design of the feed rail barrier in freestalls and the dimensions of the tie rail in tiestalls. Animal-based risk factors, such as stage of lactation, parity, and body condition, were also associated with all 3 types of lesions. This study showed that lesions to the hock, knee, and neck were common in the Maritime Provinces of Canada. Although differences were seen between facility types, in general, the results suggest that improving stall design and management and feed bunk design would help producers reduce the number of skin lesions seen in dairy cattle.     

Prevalence of lameness and associated risk factors on dairy farms in the Maritime Provinces of Canada

Lameness in dairy cattle is a major issue for the industry due to the effects on the welfare of the animal, the economic impact, and consumer perception. The aim of this study was to determine the prevalence of lameness and explore potential risk factors in the Maritime Provinces of Canada. Cows were scored for lameness and potential risk factors and were assessed in 46 freestall herds and 33 tiestall herds in Nova Scotia, New Brunswick, and Prince Edward Island. In freestall herds, lameness was assessed using the most common method, locomotion scoring. A cow with a gait score of ≥3 out of 5 was considered to be lame. In tiestall herds, lameness was assessed using an alternative method known as stall lameness scoring. This assessment consisted of observation of the cow for 4 behavioral changes: standing on the edge of the stall, shifting weight, resting a limb, and uneven weight bearing when moved side to side. A cow displaying 2 or more of these behaviors was considered to be lame. At the time of the assessment, other animal-, environmental-, and management-based measurements were collected. These measurements were used in multivariable logistic regression analysis to determine risk factors that were associated with lameness for both freestalls and tiestalls independently. The prevalence of lameness was 21% for freestall-housed cattle and 15% for tiestall-housed cattle. Of the 1,488 tiestall-housed cows that were assessed, 68% showed no behavioral changes, whereas 15, 15, 2, and <1% showed 1, 2, 3, or 4 changes, respectively. In freestalls, higher odds of lameness were seen when cows spent ≥3 h/d in the holding area for milking compared with those that spent <3 h/d. In tiestall herds, higher odds of lameness were seen when bedding material was wet compared with when it was dry. For both lactating cow facility types, housing the dry cows and heifers on a deep bedded pack compared with tiestalls or freestalls was associated with a decreased odds of lameness. There were also many cow-level variables associated with lameness, including parity, daily milk production, stage of production, body condition, and width at the tuber coxae (hook bones). If producers become aware of the risk factors associated with lameness, they can make informed decisions on where to implement changes to help reduce the level of lameness in their herd.     

The effects of growth temperature and growth phase on the inactivation of Listeria monocytogenes in whole milk subject to high pressure processing

The aim of this study was to explore the effect of a wide range of growth temperatures, growth phases and plating media on the inactivation of Listeria monocytogenes by high pressure processing (HPP). In part one, L. monocytogenes was grown to mid-stationary phase at 4, 15, 25, 35 or 43 degrees C, inoculated into whole UHT milk at approximately 10(7) CFU/ml and high pressure processed at 400 MPa at room temperature (20-25 degrees C). Afterward, the HPP milk was plated on Tryptic Soy Yeast Extract Agar (TSYEA) and Modified Oxford Agar (MOX) to determine the degree of injury. For part two, cells were grown to mid-exponential, late-exponential or mid-stationary phase at 15 or 43 degrees C and processed in the same way. Time to reach a 5-log reduction was determined and data were analysed by ANOVA. The results from part one showed that both growth temperature and plating medium had a significant effect (P < 0.001) on the inactivation of stationary phase L. monocytogenes by HPP. Tukey's pairwise comparisons revealed that the effects of all temperatures, except 35 and 43 degrees C, were significantly different (P < 0.05). Cells grown at 15 degrees C were most sensitive to HPP, followed by cells grown at 4, 25 or 35 degrees C, with cells grown at 43 degrees C appearing to be the most resistant. Inactivation of cells grown at 4, 15 or 25 degrees C followed first order kinetics, whereas cells grown at 35 or 43 degrees C displayed non-linear inactivation kinetics due to tailing. In part two, both growth phase and plating medium had significant effects on the inactivation (P < or = 0.001) of L. monocytogenes by HPP. Cells grown at 15 degrees C to mid-stationary phase were the most pressure-resistant when tested on both media, and were significantly more resistant (P < 0.05) than cells grown at the same temperature to the other two phases of growth. There was no significant difference between mid- and late-exponential phase cells grown at 15 degrees C. When cells were grown at 43 degrees C, mid-exponential phase cells were significantly more sensitive (P < 0.05) than either late-exponential or mid-stationary phase cells, with no difference between late-exponential or mid-stationary phase cells. It was postulated that membrane composition, stationary phase proteins and/or stress proteins may affect pressure resistance.     

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%.     

Effect of prior growth temperature, type of enrichment medium, and temperature and time of storage on recovery of Listeria monocytogenes following high pressure processing of milk

A five-isolate cocktail of Listeria monocytogenes (10(3) cfu/ml in skim or whole raw milk) was subjected to 450 MPa for 900 s or 600 MPa for 90 s. The effects of prior growth temperature, type of milk (skim vs. whole), type of recovery-enrichment media (optimized Penn State University [oPSU] broth, Listeria Enrichment Broth [LEB], Buffered LEB [BLEB], Modified BLEB [MBLEB], and milk), storage temperature and storage time on the recovery of L. monocytogenes were examined. Optimized PSU broth significantly increased the recovery of L. monocytogenes following high pressure processing (HPP), and was 63 times more likely to recover L. monocytogenes following HPP, compared to LEB, BLEB and MBLEB broths (p<0.05; Odds Ratio=63.09, C.I. 23.70-167.96). There was a significant main effect for prior growth temperature (p<0.05). However, this relationship could not be interpreted given the significant interaction effects between temperature and both pressure and milk type. HPP-injured L. monocytogenes could be recovered using both LEB and oPSU broths after storage of milk at 4, 15 and 30 degrees C, with recovery being maximal after 24 to 72 h of storage; however, recovery yield dropped to 0% after prolonged storage of milk at 4 and 30 degrees C. In contrast, storage of milk at 15 degrees C yielded the most rapid rate of recovery and the highest recovery yield (100%), which remained high throughout the 14 days of storage at 15 degrees C. The above factors need to be taken into consideration when designing challenge studies to insure complete inactivation of L. monocytogenes and possibly other foodborne pathogens during high pressure processing of foods.     

Contrasts between organic participation in apatite biomineralization in brachiopod shell and vertebrate bone identified by nuclear magnetic resonance spectroscopy

Unusually for invertebrates, linguliform brachiopods employ calcium phosphate mineral in hard tissue formation, in common with the evolutionarily distant vertebrates. Using solid-state nuclear magnetic resonance spectroscopy (SSNMR) and X-ray powder diffraction, we compare the organic constitution, crystallinity and organic matrix–mineral interface of phosphatic brachiopod shells with those of vertebrate bone. In particular, the organic–mineral interfaces crucial for the stability and properties of biomineral were probed with SSNMR rotational echo double resonance (REDOR). Lingula anatina and Discinisca tenuis shell materials yield strikingly dissimilar SSNMR spectra, arguing for quite different organic constitutions. However, their fluoroapatite-like mineral is highly crystalline, unlike the poorly ordered hydroxyapatite of bone. Neither shell material shows ¹³C{³¹P} REDOR effects, excluding strong physico-chemical interactions between mineral and organic matrix, unlike bone in which glycosaminoglycans and proteins are composited with mineral at sub-nanometre length scales. Differences between organic matrix of shell material from L. anatina and D. tenuis, and bone reflect evolutionary pressures from contrasting habitats and structural purposes. The absence of organic–mineral intermolecular associations in brachiopod shell argues that biomineralization follows different mechanistic pathways to bone; their details hold clues to the molecular structural evolution of phosphatic biominerals, and may provide insights into novel composite design.     

Magnetron sputter deposition of A-15 and bcc crystal structure tungsten thin films

The effect of processing parameters on the crystal structure and electrical resistivity of magnetron sputter deposited tungsten thin films was investigated. Formation of body centered cubic (bcc) W was favored when the concentration of impurity oxygen atoms in the films was <5 at.% while the formation of A-15 W was favored between 6 and 10 at.% oxygen. A transition from A-15 W films to bcc W films occurred as the oxygen was removed from the deposition chamber by presputtering the target for extended periods of time. The binding energies of the W atoms in A-15 and bcc W films are similar, as is the binding energy of the O atoms in the two different crystal structures, indicating that the oxygen is not present as a tungsten oxide compound. The resistivity of A-15 W films is always higher than the resistivity of bcc W films due to the increased oxygen concentration and small grain size of the A-15 films. However, the sputter deposition pressure is found to have a greater effect on resistivity. This is attributed to the formation of cracks in the film.