Reducing mob size increases the survival of twin-born Merino lambs when feed-on-offer from pasture is limited and ewes are supplementary fed during lambing

Lockwood, Amy; Hancock, Serina; Kearney, G. A.; Thompson, A. N.

doi:10.1016/j.smallrumres.2019.02.008

Cited by 13 publications

(13 citation statements)

References 30 publications

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“…Dystocia, stillbirths, and starvationmismothering accounted for most mortalities which is consistent with other Australian studies [3,42]. Higher rates of mortality were observed for multiple-born lambs which is consistent with previous observations for predominantly mature ewe flocks [17,[43][44][45][46]; however, there was considerable variation in lamb mortality between birth and marking between flocks in this study. This may be explained by differences in genetics, environmental factors and other management factors (e.g., mob size and supplementary feeding) on lamb survival [3,43,47,48].…”

Section: Discussionsupporting

confidence: 92%

Abortion and Lamb Mortality between Pregnancy Scanning and Lamb Marking for Maiden Ewes in Southern Australia

Clune

Lockwood

Hancock

et al. 2021

Animals

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The contribution of abortions to the overall mortality of lambs born to maiden (primiparous) ewes in Australia remains unclear. This cohort study aimed to quantify abortion and lamb mortality for ewe lambs and maiden Merino two-tooth ewes. Lamb mortality from pregnancy scanning to marking were determined for 19 ewe lamb and 11 Merino two-tooth ewe flocks across southern Australia. Average lamb mortality from scanning to marking was 35.8% (range 14.3–71.1%) for the ewe lambs and 29.4% (range 19.7–52.7%) for the two-tooth ewes. Mid-pregnancy abortion was detected in 5.7% of ewes (range 0–50%) in the ewe lamb flocks and 0.9% of ewes (range 0–4.4%) in the two-tooth ewe flocks. Mid-pregnancy abortion affecting ≥2% of ewes was observed in 6/19 ewe lamb flocks and 2/11 two-tooth ewe flocks. Lamb mortality from birth to marking represented the greatest contributor to foetal and lamb mortality after scanning, but mid-pregnancy abortion was an important contributor to lamb mortality in some ewe lamb flocks. Variability between the flocks indicates scope to improve the overall reproductive performance for maiden ewes by reducing foetal and lamb losses. Addressing mid-pregnancy abortion may improve the reproductive performance in some flocks.

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Section: Discussionsupporting

confidence: 92%

Abortion and Lamb Mortality between Pregnancy Scanning and Lamb Marking for Maiden Ewes in Southern Australia

Clune

Lockwood

Hancock

et al. 2021

Animals

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“…However, variation in the effect of mob size on lamb survival was observed in intensive experimental work conducted in two contrasting seasons. The survival of twin lambs decreased by 4% per additional 100 ewes in the mob when herbage mass was below 390 kg DM/ha and ewes were trail fed supplements during lambing (Lockwood et al 2019a), whereas the survival of single-and twin-born lambs was not observed to differ between mob sizes of 50 and 130 ewes when herbage mass at lambing exceeded 2400 kg DM/ha (Lockwood et al 2019d). This suggests that the effect of mob size on lamb survival could be influenced by herbage mass and supplementary feeding.…”

Section: Lamb Survivalmentioning

confidence: 99%

“…It would be of interested to determine if the same effect would be observed with lick feeders. Hinch and Brien (2014) stated that the limited data available suggests maximum flock sizes of 100-250 and 200-500 for twin and singleton-bearing ewes respectively, however, the optimal mob sizes are likely to be significantly smaller than this based on the recent work by Lockwood et al (2019aLockwood et al ( , 2019bLockwood et al ( , 2019cLockwood et al ( , 2019d and no such recommendations are available for triplets. Given the potential for many triplet lambs to be born in a short space of time, at a preferred lambing site, the impact of stocking rate and especially mob size on triplet survival requires investigation.…”

Section: Lamb Survivalmentioning

confidence: 99%

Triplet lambs and their dams – a review of current knowledge and management systems

Kenyon

Fraga

Blumer

et al. 2019

New Zealand Journal of Agricultural Research

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Triplet-bearing ewes and their lambs have the potential to improve flock productivity however, the lack of robust information on optimal nutrition and management is limiting their performance. In comparison to twins, the triplet lamb is; lighter, more metabolically challenged, has lower body temperature, and receives less colostrum and milk which combined results in lower survival rates and weaning weights. While scientifically based management guidelines are available for singletons and twins, guidelines are generally lacking for triplets. Although there is some knowledge on the impacts of nutrition, further studies are required to examine the impacts of varying feeding regimens in pregnancy and lactation, across the body condition range. Characterising the impacts of shelter and other paddock factors, stocking rate, mob size and human intervention would also be of benefit. Future studies must be large enough to allow for evaluation of lamb survival and litter birth weight variation.

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“…Primiparous ewes may be more susceptible to infectious diseases, as younger ewes are less likely to have developed immunocompetency to infection prior to pregnancy [ 21 , 22 ]. Most recent Australian studies that included lamb necropsies were conducted with multiparous ewes, and cause of death was assigned based on gross post-mortem findings without adjunct laboratory investigation [ 2 , 23 – 27 ]. In general, relatively few investigations for abortion and perinatal lamb death are submitted to veterinary diagnostic laboratories for exclusion of infectious diseases [ 12 ].…”

Section: Introductionmentioning

confidence: 99%

Chlamydia pecorum detection in aborted and stillborn lambs from Western Australia

Clune

Besier

Hair

et al. 2021

Vet Res

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Lamb survival is an important welfare and productivity issue for sheep industries worldwide. Lower lamb survival has been reported for primiparous ewes, but the causes of this are not well studied. The aim of this study was to determine causes of perinatal deaths for lambs born to primiparous ewes in Western Australia, and identify if infectious diseases are implicated. Lamb mortality from birth to marking were determined for 11 primiparous ewe flocks on 10 farms in Western Australia. Lamb mortality from birth to marking averaged 14% for single-born and 26% for multiple-born lambs. Lamb necropsies (n = 298) identified starvation–mismosthering–exposure (34%), dystocia (24%) and stillbirth (15%) as the most common causes of perinatal lamb death. There was no evidence of exotic abortigenic pathogens in aborted and stillborn lambs (n = 35). Chlamydia pecorum was detected by qPCR in 15/35 aborted and stillborn lambs on 5/6 farms. Preliminary molecular characterisation of C. pecorum detected in samples from aborted and stillborn lambs (n = 8) using both Multilocus Sequence Typing and ompA genotyping indicated all strains were genetically identical to previously described pathogenic livestock strains, denoted ST23, and dissimilar to gastrointestinal strains. High frequency of detection of a pathogenic C. pecorum strains ST23 associated with ovine abortion and stillbirth on multiple farms located across a wide geographic area has not been previously reported. Chlamydia pecorum may contribute to reproductive wastage for primiparous sheep in Western Australia. Further investigation to understand C. pecorum epidemiology and impact on sheep reproduction is warranted.

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Reducing mob size increases the survival of twin-born Merino lambs when feed-on-offer from pasture is limited and ewes are supplementary fed during lambing

Abstract: Reducing mob size increases the survival of twin-born Merino lambs when feed-on-offer from pasture is limited and ewes are supplementary fed during lambing

Cited by 13 publications

References 30 publications

Abortion and Lamb Mortality between Pregnancy Scanning and Lamb Marking for Maiden Ewes in Southern Australia

Abortion and Lamb Mortality between Pregnancy Scanning and Lamb Marking for Maiden Ewes in Southern Australia

Triplet lambs and their dams – a review of current knowledge and management systems

Chlamydia pecorum detection in aborted and stillborn lambs from Western Australia

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