Risk factors for bovine respiratory disease in Australian feedlot cattle: Use of a causal diagram-informed approach to estimate effects of animal mixing and movements before feedlot entry

A nationwide longitudinal study was conducted to investigate risk factors for bovine respiratory disease (BRD) in cattle in Australian feedlots. After induction (processing), cattle were placed in feedlot pens (cohorts) and monitored for occurrence of BRD over the first 50 days on feed. Data from a national cattle movement database were used to derive variables describing mixing of animals with cattle from other farms, numbers of animals in groups before arrival at the feedlot, exposure of animals to saleyards before arrival at the feedlot, and the timing and duration of the animal's move to the vicinity of the feedlot. Total and direct effects for each risk factor were estimated using a causal diagram-informed process to determine covariates to include in four-level Bayesian logistic regression models. Mixing, group size and timing of the animal's move to the feedlot were important predictors of BRD. Animals not mixed with cattle from other farms prior to 12 days before induction and then exposed to a high level of mixing (≥4 groups of animals mixed) had the highest risk of developing BRD (OR 3.7) compared to animals mixed at least 4 weeks before induction with less than 4 groups forming the cohort. Animals in groups formed at least 13 days before induction comprising 100 or more (OR 0.5) or 50–99 (OR 0.8) were at reduced risk compared to those in groups of less than 50 cattle. Animals moved to the vicinity of the feedlot at least 27 days before induction were at reduced risk (OR 0.4) compared to cattle undergoing short-haul transportation (<6 h) to the feedlot within a day of induction, while those experiencing longer transportation durations (6 h or more) within a day of induction were at slightly increased risk (OR 1.2). Knowledge of these risk factors could potentially be used to inform management decisions to reduce the risk of BRD in feedlot cattle.     

Quarter-milking-, quarter-, udder- and lactation-level risk factors and indicators for clinical mastitis during lactation in pasture-fed dairy cows managed in an automatic milking system

Objectives To identify risk factors and indicators at quarter‐milking and other levels for clinical mastitis during lactation in pasture‐fed cows managed in an automatic milking system. Design A retrospective nested case–control study using data collected over a 31‐month period. A total of 803,948 quarter‐milkings from 249 cows were available for analysis, of which 245 were selected as clinical mastitis quarter‐milking cases and 2450 unaffected quarter‐milkings were selected as controls. Most of the diagnoses of clinical mastitis had been made after clinical assessments of quarters following automated alerts by the milking system. Potential risk factors and indicators were assessed using univariable and multivariable multilevel logistic models. Results Quarters that are milked infrequently and have low yield, fast peak milk flow rates, blood in the milk and/or elevated milk conductivity are at increased risk of clinical mastitis. Quarters were also at increased risk between days 10 and 29 of lactation, and during higher parity lactations. Milk fat and protein concentrations and the fat : protein ratio were not significantly associated with the development of clinical mastitis. Neither quarter position (fore or rear) nor side (left or right) was associated with clinical mastitis occurrence. Quarters that had been clinically affected more than 30 days previous in the current lactation were not at increased risk of redeveloping clinical mastitis. Conclusions Under the study conditions, the risk of clinical mastitis increased for quarter‐milkings in quarters that were milked less frequently in the previous 7 days, were low‐yielding, had fast peak milk flow rates and had more milkings in which blood was detected in milk and/or the milk conductivity was elevated. Risk was also increased in days 10–29 of lactation and in higher parity lactations.     

Radical reactions of c60

Photochemically generated benzyl radicals react with C(60) producing radical and nonradical adducts Rn C(60) (R = C(6)H(5)CH(2)) with n = 1 to at least 15. The radical adducts with n = 3 and 5 are stable above 50 degrees C and have been identified by electron spin resonance (ESR) spectroscopy as the allylic R(3)C(60)(.) (3) and cyclopentadienyl R(5)C(60)(.) (5) radicals. The unpaired electrons are highly localized on the C(60) surface. The extraordinary stability of these radicals can be attributed to the steric protection of the surface radical sites by the surrounding benzyl substituents. Photochemically generated methyl radicals also add readily to C(60). Mass spectrometric analyses show the formation of (CH(3))nC(60) with n = 1 to at least 34.     

Effect of irrigation and grazing animals on soil quality measurements in the North Otago Rolling Downlands of New Zealand

The North Otago Rolling Downlands (NORD) of New Zealand is currently undergoing a large change in land use with subsequent intensification as a result of a new large community irrigation scheme. To assess the effect of this change, a 4‐year monitoring survey was established on two common Pallic soil types of the area to determine the influence of irrigation term (short, <5 years vs. long, >5 years) and grazing animal (cattle vs. sheep) on a range of physical and organic matter soil quality parameters. This 4‐year survey also included the historical land use of dryland sheep farming in the absence of irrigation water. Irrigation term had no significant (P > 0.05) effect on soil physical parameters (percentage macroporosity and bulk density) for 3 of 4 years and no significant effect (P > 0.05) on topsoil total carbon or nitrogen contents. However, irrigation term had a significant (P < 0.01) but biologically small effect on the ratio of carbon to nitrogen with narrowing of the range under longer term irrigation. A significant difference between the dryland and irrigated surveys was found for macroporosity (dryland sheep 17.3% v/v vs. irrigated sheep 13.4% v/v; P < 0.001) and for the C:N ratio (dryland sheep 10.7 vs. irrigated sheep 10.2; P < 0.05). The change in macroporosity under irrigation is likely to take effect within 1 or 2 years of land‐use change as little discernable differences in soil physical properties were evident from land under short‐ or long‐term irrigation.     

Fat mass,and not diet,has a large effect on postprandial leptin but not on adiponectin concentrations in cats

Leptin and adiponectin play important roles in carbohydrate and lipid metabolism in different species. Information is limited on the effects of diet, weight gain, and fat mass on their concentrations in cats. This study compared fasting and postprandial blood leptin and total adiponectin concentrations before and after 8 wk of ad libitum feeding to promote weight gain in adult cats (n = 32) fed either a low-carbohydrate, high-protein (23% and 47% ME) or a high-carbohydrate, low-protein (51% and 21% ME) diet. There were significant effects of total, abdominal, and nonabdominal fat mass, but not diet or body weight, on mean 24-h and peak leptin (P < 0.01); observed increases in mean and peak leptin were greatest for abdominal fat mass (50% and 56% increase for every extra 100 g, respectively). After weight gain, postprandial leptin concentration increased markedly relative to when cats were lean, and the duration of the increase was longer after a mean weight gain of 37% with the low-carbohydrate, high-protein diet group compared with 17% with the high-carbohydrate, low-protein group (P ≤ 0.01). Adiponectin was lower than fasting at some time points during the postprandial period in both groups (P ≤ 0.05). For both fasting and mean 24-h adiponectin, there was no significant diet effect (P ≥ 0.19) or changes in weight gain relative to when cats were lean (P ≥ 0.29). In conclusion, fat mass, and not diet, has a large effect on postprandial leptin but not adiponectin concentrations in cats.     

Time related factors in Heliothis control on cotton

Most factors in Heliothis control on cotton are crucially related to time but all are interrelated one with another and form two complex interactions hinging on the pest life cycle. One is the crop-pest interaction and the other the control strategy. This paper reviews most of the factors and reports work carried out in Swaziland to elucidate some of them. In the crop-pest interaction the timing of the initial attack and a cue for spraying can be indicated by development of an alternate host and, in Swaziland, by reference to the average date of maize tassellation. Later infestations are measured by scouting and a comparison is made of the two main systems, the first based on a small part of many plants and used in the USA, and the second based on the whole of a few plants in Africa. Their respective purposes are discussed and economic spray thresholds based on them are presented. The compensatory ability of the plant diminishes as the season progresses but in Swaziland manual bud/flower removal experiments over 3 years on raingrown and irrigated cotton showed that prior to 12 January (9-12 weeks from planting) removal increased the yield in half the cases whilst later removal could cause a decrease. The natural Heliothis infestation was allowed to remove fruits in an experiment by leaving spray gaps and the results confirmed those of the previous manual experiments except that damage continued for about 2 weeks after spraying restarted. This advanced the critical date to 31 December but up to three sprays could be saved without loss of yield and possibly with a yield bonus. In the control strategy the different stages of the life cycle are considered as targets but the most obvious is normally the first instar larvae. Rapid plant growth can dictate frequent spray applications regardless of deposit persistence which may need to be longer when using aircraft in spite of Heliothis oviposition occurring predominantly on exposed surfaces. Temperature-independent or fumigant insecticides or those affecting the adult may best be sprayed in the evening when cooler and calmer post-treatment conditions occur and adults are starting to fly.