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To determine the level and timing of lamb loss that occurs during the first year of life on a typical hill country sheep and beef farm in the central North Island of New Zealand and to determine how much of this loss can be prevented through vaccination against the five main clostridial diseases using a commercially available multivalent clostridial vaccine.The study was conducted on a single commercial hill country sheep and beef farm in the central North Island of New Zealand, with a history of never vaccinating their stock against clostridial disease. Lambs were blocked on sex and randomly selected at docking into treatment (n = 1,705 lambs) and control (n = 1,709 lambs) groups. Treated lambs were vaccinated at docking and 4 weeks later with 1 mL of multivalent clostridial vaccine. Control lambs were not vaccinated. Different coloured ear tags were used to identify the lambs in the treatment and control groups. All lambs were counted at docking (October 2019) and at six other management event times between docking and when the replacement hoggets were set stocked for lambing (August 2020). The number of lambs sold between each management event, from each group was also counted. The difference in the number of lambs from one management event to another, minus the lambs sold between these events was regarded as the lamb losses for that period.The total percentage of lamb losses from docking to pre-lamb was 4.8% (81/1,705) and 6.2% (106/1,709) in the vaccinated and unvaccinated lambs respectively OR = 0.75 (95% CI = 0.56-1.02; p = 0.06). Most lamb loss occurred in the period after docking, followed by the period between weaning and the first post-weaning drench. Less lamb loss occurred in the vaccinated lambs (27/1,705; 1.6%) after docking than in the unvaccinated lambs (66/1,709; 3.9%). This was mainly due to lower female lamb losses in the vaccinated (5/868; 0.6%) compared to the unvaccinated (38/868; 4.4%) group (p 0.001).Vaccination of lambs at docking and 4 weeks later, with a multivalent 5-in-1 clostridial vaccine was associated with a 23.6% (25/106) reduction in total lamb loss from docking to pre-lambing. In female lambs, vaccination was associated with an 87% (33/38) reduction in lamb loss after docking and a 37% (22/59) reduction over the total trial period.

Using climatic data from 1991 to 2016 recorded at Avikanagar, wind chill index (WCI) was calculated for each day during winter (December–February) coinciding with major lambing season. The WCI (kca...

To compare the vascular and neuronal changes in the central nervous system (CNS) of lambs that died in the first 3 days after birth, from various causes, with control lambs subject to euthanasia.Dead lambs (n=65) were collected daily during the period 07 September 2010 to 26 September 2010 from a flock of 200 twin-lamb-bearing ewes. Age-matched lambs from the same flock were subject to euthanasia as a control group (n=39). Necropsies were conducted on all study lambs. The cause of death in lambs found dead was categorised as starvation-mismothering-exposure complex (SME), dystocia, or other, based on gross necropsy findings. Deaths were categorised as SME in lambs with necropsy lesions of pericardial, perirenal and mesenteric fat catabolism, an empty gastrointestinal tract and completely inflated lungs. Dystocia was diagnosed by the presence of a swollen tongue, injected sclera and subcutaneous oedema and haemorrhage around the head and neck or hind limbs. Deaths were categorised as other if an obvious cause of death could not be ascertained and if evidence of infection was identified. The CNS of each lamb necropsied was assessed grossly for haemorrhage, and using histopathology to determine vascular and neuronal changes. Immunohistochemistry was performed on selected cases (n=36) to confirm neuronal death.Of the 65 lambs found dead, 16 (25%) had evidence of cerebral and spinal meningeal haemorrhage, whereas of the 39 clinically normal control lambs, all displayed gross evidence of cerebral and spinal meningeal haemorrhage. There was no evidence of parenchymal vacuolation, neuronal vacuolation or ischaemic neurons in any of the lamb brain sections including those that died with evidence of dystocia. There was no difference, within the regions examined, in mean vascular score between lambs categorised by cause of death (p0.05). The overall mean vascular score for the brain stem was greater than the mid brain (p=0.02) and the cortex (p=0.005) but did not differ from either the spinal cord or cerebellum (p0.3). The vascular score for the spinal cord was greater than the mid brain (p=0.01) and cortex (p=0.003). Lambs that died of dystocia had less immunoreactivity for microtubule associated protein 2 (MAP2) in the hilus/CA4 region of the hippocampus (p=0.02) and dentate gyrus of the hippocampus (p=0.006) than those that were subject to euthanasia.Neither gross nor histological vascular changes in the CNS could be used to distinguish newborn lambs that had been subject to euthanasia from those that died with evidence of SME or dystocia, so meningeal haemorrhages in or on the brain and spinal cord of lambs that die in the neonatal period cannot be used to support a diagnosis of birth injury or dystocia. The CA4 region and the dentate gyrus of the hippocampus are useful regions for detecting hypoxic/ischaemic injury in lambs with evidence of dystocia. There was no evidence that hypoxia/ischaemia contributed to lambs dying of SME.The results of this study suggest that vascular changes in the CNS of newborn lambs may be produced artefactually. Caution is warranted with respect to interpretation of these vascular changes.

This study describes how birth weight, gender, litter size, and age of dam affect lamb mortality during the summer period, using data on lambs of the breeds Spaelsau (N ≈ 110 000) and Norwegian White Sheep (N ≈ 450 000) during 1994 to 2005. A general mixed linear model was used for the analysis. Birth weight affected summer mortality non-proportionally: an increase in weight from very small towards the breed mean strongly deflated mortality risk; weigh increase above breed means had little effect. Male lambs had a higher mortality than females, and lambs born by 12-months-old dams were in greater risk than those having older dams. Increasing litter size resulted in increased mortality. The results are discussed and recommendations for future research, with focus on breeding and genotype by environment interaction effects are made.

Wind and wet coats create dangerous conditions for lambs, even at moderate temperatures. Lambs compromised by factors such as birth injury and small size are particularly at risk. Wet, cold, windy weather added 38–76% to mortality rates in Australian Merino and Corriedale lambs, and in New Zealand lamb breeds added 10–20% (more in snow conditions). Wind shelter removed 3–13% from single lamb mortality rates and 14–37% from twin lamb mortality rates in Australian Merino and Corriedale sheep, but was not effective in reducing losses of twins in cold or wet weather. In New Zealand, wind shelter (such as Pinus radiata tree shelter belts) has generally removed less than 10% from mortality rates. Effective shelter would protect lambs from wind, rain, radiative and conductive heat loss, as well as allowing lambs exposure to the sun. Shelter should be familiar and well dispersed to encourage ewes to isolate from other sheep at lambing. Scattered dense shelter within paddocks such as tussocks or forage gr...

A controlled supplementation trial was performed in an assumed iodine-deficient Romney ewe flock in the Manawatu. Significantly more twin litters were born to iodine-supplemented ewes than to control ewes. Furthermore, the perinatal mortality rate in lambs born to iodine-supplemented dams was significantly lower than in lambs born to control dams. Ewe age and the use of different lambing paddocks for iodine-supplemented and control ewes may have been confounding factors. In both iodine-supplemented and control ewes, serum T3, and T4, concentration values remained above the currently used normal range throughout the trial period.

In each of three years (1979, 1980, 1981) 260 – 280 mixed age Marshall Romney (MR) and 300 - 400 mixed age control Romney (CR) ewes were allocated to eight groups with ewes of each strain present in each group. Four groups were single-sire-mated with four MR rams and the other four groups with four CR rams. A new selection of rams was used each year. The haemoglobin type of all ewes and rams was determined. Ewes were weighed 3 – 4 weeks before the beginning of lambing and their respective weights adjusted to conceptus-free weights. At lambing, the lambs born to each ewe were identified and birth weight, pelvic width, and head and chest circumferences were measured. Each day dead lambs were picked up and autopsied. In the last 2 years this included looking for cranial and spinal haemorrhages. Lambs present at weaning were weighed and recorded. The conjugate and transverse diameters and area of the pelvic opening were measured on the pelvises of 47 MR and 37 CR ewes after slaughter in 1980 and 1981...

Mortality data on 5163 Romney × Suffolk lambs were collected at Winchmore Irrigation Research Station from 1976 to 1981. Mortality from birth to tailing (25 days) for single, twin, and triplet births was 14.1, 14.7, and 33.0% with mean birth weights of 5.2, 4.1, and 3.3 kg respectively. Ninety-four percent of all deaths occurred within 72 h of birth. Dystocia accounted for 50.4% of all single deaths and starvation/exposure for 45.0% of all multiple deaths. The proportion of ewes assisted at lambing increased with birthweight above 4.5 kg to reach almost 19 and 8% for single and twin births respectively. If lambs that were assisted at birth, but survived to weaning, are regarded as potential deaths, the overall potential mortality of single and twin lambs was 27.9 and 20.2% respectively. Ewe liveweight gain during the last 6 weeks of pregnancy was associated with increased birthweights of single and twin lambs (P < 0.05). A liveweight change of approximately 10 kg in ewes was required to alter bir...

370000 litter records from the Swedish sheep recording scheme during 1974–80 were analysed according to the mortality rate for lambs at different ages from birth to 4––5 months of age. The four breeds included were Swedish Peltsheep (P), Swedish Finewool (Lf), Rya (Lr) and the Crossbred group (X), together comprising over 90% of all ewes in the national sheep recording scheme. The overall mortality rates were 6.13 in P, 12.71 in Lf, 9.78 in Lr and 8.14% in X. Corresponding figures for stillbirths were 1.74 (P), 5.20 (Lf), 3.73 (Lr) and 2.89 (X). Stillbirths and deaths during the first 4 days after birth constituted between one–half and three–fourths of all losses. Effects of year, region, flock size and birth season as well as interactions between these were significant, especially for stillbirths and deaths shortly after birth. Factors connected with season of birth seemed to be more important than factors associated with years, regions and flock size. Environmental factors of major importance i...

Two experiments were carried out to determine the effect of slope on lamb mortality. In Experiment 1, 166 Marshall Romney (MR), 170 conventional Romney (CR), and 59 MR X CR ewes were allocated to one of 17 lambing areas of 0.2-0.4 ha and uniform slope. Mean slopes ranged from 3 to 440 and each area was surrounded by electric netting fences. Ewes entered their respective lambing areas 2 days before the expected lambing date and remained there for 4-5 days. In Experiment 2, two 1 ha plots selected on the basis of conformity of slope (36-44°) and 100-120 m long were each divided into three equal lambing areas by fences down the slope. Barriers either 15 or 30 m apart were constructed of 33-cm-high woven polyethylene mesh across the slope on two of the three lam bing areas in both plots. Lamb mortality in Experiment 1 was not affected by slopes up to 300 but there was a large increase in lamb mortality with slopes of 36-44° (19.4% lamb mortality for less than 300 versus 50.1% lamb mortality for more ...

Factors associated with mortality in 7,727 lambs born to 7,091 twoto five-year-old ewes over the 9 years 1959–67 were studied. The lambs were from two Romney flocks and first-, second-, third-, and fourthcross Border Leicester × Romney flocks. Lamb survival rate (lambs weaned as a percentage of all lambs born) increased with increasing age of dam for both single- and multipleborn lambs. Variation in survival rate between flocks and between female and male lambs was large. In 60% of the dead lambs, 44.6% of single-born lambs died of dystokia and 15.1 % from physiological starvation. Of the multiple-born lambs autopsied, 16% died from dystokia and 41.7% from starvation. Infections accounted for 11.6% and pre-natal deaths for 10.3% of the remaining deaths. Most of the deaths occurred within 3 days of birth, and relatively more single- than multiple-born lambs died at birth Analysis of variance of birth weight showed that first-cross lambs were the heaviest and that birth weights decreased with inter...

An analysis of the breeding performance of sorne 11,258 sheep, mostly Corriedale, over aperiod of 15 years in relation to liveweight at mating has been made, yielding the following observations:- (i) Ewe and lamb mortality, 3.8 per cent and 12.0 per cent respectively, are independent of liveweight of the ewe, except at liveweights below 90–100 lb. (ii) Barrenness (mean 6 per cent) is relatively independent of liveweight above approximately 90–100 lb but below this critical weight barren (iii) Twinning increases approximately linearly with increasing liveweight at a rate of the order of 6 per cent per 10 lb. (iv) The lower breeding performance of 2-tooth ewes in comparisonwith older ewes can be explained almost entirely in terms of liveweight at mating. The relative significance of liveweight and flushing as factors influencing lambing percentage are discussed.