Factors associated with fetal losses in ewe lambs on a New Zealand sheep farm.

CASE HISTORY: As part of a production study of ewe lambs on a large farm in the Waikato region of New Zealand in 2011, pregnancy diagnosis was undertaken twice by trans-abdominal ultrasonography at 68-103 and 97-132 days of gestation. At the second pregnancy diagnosis 257/3,790 (6.8%) ewe lambs had evidence of non-viable fetuses or absence of a pregnancy that was present at the previous pregnancy diagnosis (fetal loss). LABORATORY FINDINGS: Serum antibody titres for Leptospira interrogans serovar Pomona appeared generally higher in 10 ewe lambs with fetal loss compared with 10 that were still pregnant. Histopathological investigation was not able to confirm that fetal loss was associated with leptospial infection. EPIDEMIOLOGICAL INVESTIGATION: In the 2012-born cohort of ewe lambs 443 were vaccinated with a bivalent leptospirosis vaccine and 882 unvaccinated. Serum was collected from 124 non-vaccinated ewe lambs between January and December 2013 for measurement of antibodies to Leptospira serovar Pomona and L. borgpetersenii serovar Hardjo-bovis using a microscopic agglutination test (MAT). Less than 5% of these ewe lambs were seropositive until May, but by August 85% and 48% of animals were seropositive to Leptospira serovars Hardjo-bovis and Pomona, respectively. Fetal loss in non-vaccinated ewe lambs was 78/882 (9%) compared with 23/443 (5%) in vaccinated ewe lambs. Combined data from the 2011- and 2012-born ewe lambs (n=5,115) were analysed using a logistic regression model and fetal loss as the dependent variable. In the final model fetal loss was associated with pre-mating bodyweight (p=0.003), weight change from pre-mating to initial pregnancy diagnosis (p<0.001), year born and leptospirosis vaccination status (p=0.013). Amongst the serologically monitored ewe lambs, there were associations between fetal loss and being seropositive to Leptospira serovar Pomona using titre cut-points of 1:48 and 1:768 (p<0.001). CLINICAL RELEVANCE: Low pre-mating weight and/or low weight gain from mating to pregnancy diagnosis was associated with increased fetal loss, emphasising the importance of ewe lambs achieving target pre-mating weights and liveweight gains during pregnancy. Infection with Leptospira serovar Pomona was associated with fetal loss in the 2012-born cohort and the possibility of infection with this serovar should be considered when investigating cases of fetal loss.

The effects of pasture availability for twin- and triplet-bearing ewes in mid and late pregnancy on ewe and lamb behaviour 12 to 24 h after birth.

This experiment was conducted to evaluate the effect of offering ewes two different feeding levels, during mid and late pregnancy, on ewe and lamb behaviour 12 to 24 h after birth. Romney ewes, bearing twin (n = 80) or triplet foetuses (n = 56), were allocated to a pasture sward height of 2 or 4 cm between 70 and 107 days of pregnancy. In late pregnancy (day 107 to 147), half of the ewes were reallocated the alternate sward height, which produced four treatments: 2-2, 2-4, 4-2 and 4-4. Ewes were weighed on days 65, 92, 107 and 130 of pregnancy and lamb live weights were recorded 12 to 24 h after birth. Twelve to 24 h after birth the maternal behaviour score (MBS) of the ewes were determined, whilst their lambs were tagged. After the lambs were released, the behaviour of each ewe and her lambs was observed for 5 min. Ewe treatment and litter size had no effect on ewe MBS. However, as MBS increased (ewes stayed closer to lambs during tagging), ewes bleated less in a high-pitch and were quicker to make contact with their lamb. During the observation period, ewes in the 4-4 treatment had a greater percentage of their bleats in a low pitch (P < 0.05) than ewes in the 2-2 and 4-2 treatment (61.3% v. 41.3% and 38.8% low bleats, respectively) and more lambs born to 4-4 ewes (95%) bleated than lambs born to 2-2 ewes (84%; P < 0.05). However, lambs born to ewes in the 2-2 treatment bleated earlier than lambs in all other treatments (P < 0.05). Lambs born to 4-4 ewes were less likely (P < 0.05) to move towards their dam in order to make contact than lambs born to 2-2 or 4-2 ewes (3.1% v. 16.9% and 16.7%, respectively). These findings suggest that under the conditions of the present study, ewe nutrition had little effect on maternal behaviour. However, lambs born to ewes offered 2 cm pasture sward heights during mid and/or late pregnancy (2-2, 2-4 and 4-2 treatments) displayed behaviour that demonstrated greater 'need' whereas lambs born to ewes offered 4 cm during mid and late pregnancy sought less attention from their dam.

The effect of different types of stressors during mid- and late pregnancy on lamb weight and body size at birth.

Mid-pregnancy shearing has consistently been shown to increase lamb birth weight, which can lead to an increase in lamb survival rates. However, shearing ewes during the winter months and under outdoor pastoral farming conditions can expose the recently shorn ewe to a greater risk of hypothermia. The aim of this study was to determine if exposure of ewes to repeated stressors, in mid- and late pregnancy, would result in an increase in lamb birth weight. This information may assist in the elucidation of the mechanism for the birth weight response to mid-pregnancy shearing, which in turn could assist in the design of management options to increase lamb birth weight without placing the ewe at risk. One hundred and forty-four twin-bearing Romney ewes were allocated to one of six mid-pregnancy treatments: control, isolation on 2 or 10 occasions, sham-shearing on 10 occasions, intramuscular cortisol injection on 10 occasions or shearing. Isolation, sham-shearing and cortisol treatments were conducted twice a week beginning, on average, day 74 of pregnancy and shearing occurred on day 76. During pregnancy, ewe treatment had no effect on ewe live weight. However, average ewe body condition scores were higher in the shorn group than in the sham-shorn or cortisol groups (P < 0.05). Intramuscular injections of cortisol had a greater effect on ewe plasma cortisol concentrations than all other treatments (P < 0.05). Shearing produced a greater plasma cortisol response than isolation × 10 and sham-shearing (P < 0.05). Ewe plasma cortisol responses decreased during the 5 weeks of isolation and sham-shearing but cortisol injections produced a greater response during the fifth treatment than the first or ninth treatments (P < 0.05). Lambs born to shorn ewes were heavier and had a longer crown rump, forelimb and hind limb lengths than all other lambs (P < 0.05). In addition, lambs born to ewes in the cortisol treatment were lighter than lambs born to control, isolation × 2, isolation × 10 and shorn ewes (P < 0.05). The plasma cortisol concentrations observed for ewes injected with cortisol were far greater than those observed in all other groups, which is likely to explain the low birth weights of lambs born to ewes in that group. These results indicate that the mechanism by which mid-pregnancy shearing increases lamb birth weight is unlikely to be repeated stressors.

How do land-based salmonid farms affect stream ecology?

Increasing research is highlighting the fact that streams provide crucial ecosystem services through the biogeochemical and ecological processes they sustain. Freshwater land-based salmonid farms commonly discharge their effluents into low order, headwater streams, partly due to the fact that adequate freshwater resources for production are commonly found in undisturbed areas. We review the effects of salmonid farm effluents on different biological components of stream ecosystems. Relevant considerations related to the temporal and spatial scales of effluent discharge and ecological effects are discussed. These highlight the need to characterize the patterns of stressor discharge when assessing environmental impacts and designing ecological effects studies. The potential role of multiple stressors in disrupting ecosystem structure and function is discussed with an emphasis on aquaculture veterinary medicines. Further research on the effects of veterinary medicines using relevant exposure scenarios would significantly contribute to our understanding of their impact in relation to other effluent stressors.

Construct validity of a work environment impact scale.

This study examined the construct validity and the internal consistency of a newly developed assessment, the Work Environment Impact Scale (WEIS). After administration to 20 individuals with psychiatric disabilities, Rasch analysis was utilized to scrutinize the data. For this study, criteria for determining unexpected person/item responses were based on the following criteria: MNSQ > 1.3 and $\underline{t}>2.0$. Persons/items with MNSQ < 0.7 and $\underline{t}<-2.0$ were examined to enhance instrument precision but were not considered misfit. Results suggest that the WEIS is an appropriate and valid instrument to utilize with workers who have psychiatric disabilities. Overall, the items appeared to match the worker's need for performance, satisfaction, and well-being as the mean of persons measure is 0.30 ± 0.49 logits more than the mean of items measured. In addition the hierarchical order of items is consistent with literature identifying environmental press and affordance for workers with psychiatric disabilities. WEIS items constitute a uni-dimensional construct given that the summary statistics for both item and person had a MNSQ of 1.00 and 1.02 respectively and both $\underline{t}$ values were -0.2. However, three items exceeded the established criterion for being too informative given the MNSQ < 0.7 and a $\underline{t}<-2.0$., suggesting these needed to be revised to enhance the quality measurement of the instrument. One hundred percent of the workers fit the expected response pattern of the Rasch model suggesting that workers with greater satisfaction, performance and health had a higher degree of match with his/her occupational environment. In summary, anecdotal data suggested that the WEIS provided clinically relevant information useful for planning of work-related interventions or reasonable accommodations.