Reproductive performance in the Sheep CRC Information Nucleus using artificial insemination across different sheep-production environments in southern Australia

Geenty, K. G.; Brien, F. D.; Hinch, G. N.; Dobos, Robin; Refshauge, Gordon; McCaskill, M. R.; Ball, Alex; Behrendt, R.; Gore, K. P.; Savage, Darryl; Harden, S.; Hocking-Edwards, J. E.; Hart, K. W.; Werf, J. H. J. van der

doi:10.1071/an11323

Cited by 60 publications

(41 citation statements)

References 21 publications

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“…The greater lamb mortality for very light or very heavy lambs in the present study agrees with previous results in the United States (Smith, 1977), Australia (Geenty et al, 2014) and the United Kingdom (Sawalha et al, 2007) sheep populations and is also consistent with the reported optimum birth weight of 3.0 to 5.5 kg to avoid the requirement for assisted lambings and mortality (Nowak and Poindron, 2006;Speijers et al, 2010). Greater lamb mortality in light lambs has been attributed to hypothermia, lack of fat reserves and mismothering (Morris et al, 2000;Nowak and Poindron, 2006); poorer ewe uterine contractions for lambs of low birth weight results in slower parturition (Dalton et al, 1980), which may also result in greater lamb mortality.…”

Section: Birth Weightsupporting

confidence: 83%

“…A combination of management and environmental factors has previously been documented to be associated with lambing difficulty and lamb mortality in the United Kingdom (Wiener et al, 1983;Dwyer et al, 1996), New Zealand (Morris et al, 2000;EverettHincks et al, 2005), Australia (Geenty et al, 2014) and the United States (Gama et al, 1991;Southey et al, 2004) sheep populations. No study has to date examined the association between lambing difficulty and mortality and risk factors in a series of simple regression models and multiple regression models across a diverse sheep population.…”

Section: Discussionmentioning

confidence: 99%

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Risk factors associated with lambing traits

McHugh

Berry

Pabiou³

2016

Animal

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The objective of this study was to establish the risk factors associated with both lambing difficulty and lamb mortality in the Irish sheep multibreed population. A total of 135 470 lambing events from 42 675 ewes in 839 Irish crossbred and purebred flocks were available. Risk factors associated with producer-scored ewe lambing difficulty score (scale of one (no difficulty) to four (severe difficulty)) were determined using linear mixed models. Risk factors associated with the logit of the probability of lamb mortality at birth (i.e. binary trait) were determined using generalised estimating equations. For each dependent variable, a series of simple regression models were developed as well as a multiple regression model. In the simple regression models, greater lambing difficulty was associated with quadruplet bearing, younger ewes, of terminal breed origin, lambing in February; for example, first parity ewes experienced greater (P < 0.001) lambing difficulty (1.56 ± 0.02) than older ewes. The association between lambing difficulty and all factors persisted in the multiple regression model, and the trend in fixed effects level solutions did not differ from the trend observed in the simple regression models. In the simple regression analyses, a greater odds of lamb mortality was associated with male lambs (1.31 times more likely of death than females), lambs of very light (2 to 3 kg) and very heavy (>7.0 kg) birth weights, quadruplet born lambs and lambs that experienced a more difficult lambing (predicted probability of death for lambs that required severe and veterinary assistance of 0.15 and 0.32, respectively); lambs from dual-purpose breeds and born to younger ewes were also at greater risk of mortality. In the multiple regression model, the association between ewe parity, age at first lambing, year of lambing and lamb mortality no longer persisted. The trend in solutions of the levels of each fixed effect that remained associated with lamb mortality in the multiple regression model, did not differ from the trends observed in the simple regression models although the differential in relative risk between the different lambing difficulty scores was greater in the multiple regression model. Results from this study show that many common flock-and animal-level factors are associated with both lambing difficulty and lamb mortality and management of different risk category groups (e.g. scanned litter sizes, ewe age groups) can be used to appropriately manage the flock at lambing to reduce their incidence.

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Section: Birth Weightsupporting

confidence: 83%

Section: Discussionmentioning

confidence: 99%

Risk factors associated with lambing traits

McHugh

Berry

Pabiou³

2016

Animal

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“…Mortality rates in this study were within the range of those previously reported for both twin-(8.1% to 26.7%) and tripletborn (12.7% to 53.4%) lambs managed under extensive pastoral systems in New Zealand [2,17]. The relationship between the sex of the lamb [18] and a curvilinear relationship of lamb birth weight [19,20] with survival to weaning were also consistent with previous work. Interestingly, data from the present study suggests that at low birthweights triplet lambs have lower survival than twins but this is not seen at heavier birth weights.…”

Section: Discussionsupporting

confidence: 90%

Behaviour of twin- and triplet-born lambs and their dam 3 to 18 hours after birth is not a useful predictor of lamb survival to weaning

Gronqvist

Kenyon

Morris

et al. 2020

Asian-Australas J Anim Sci

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Objective: An experiment was designed to determine if behaviour traits expressed by twinand triplet-bearing lambs and their dams at 3 to 18 hours of age (after the immediate ewelamb bonding had occurred) were associated with lamb survival to weaning. Methods: The behaviour of twin and triplet lambs and their dams was assessed in the paddock at 3 to 18 hours after birth. Observations were made of the number of high-and low-pitched bleats, time to stand, make contact with dam, suck from dam and follow dam were recorded for each lamb. The maternal behaviour score of each dam was assessed. A random sub-sample of lambs were assessed during a maternal-recognition test at 12 or 24 hours of age. Traits included time spent standing, sitting, walking, time taken to reach the ewes and time spent with the ewes as well as the number of high-and low-pitched bleats emitted by the lamb. Results: In the paddock, for each additional second required for twin-born lambs to follow their dam, lambs were 1.004 (95% confidence interval [CI] 1.000 to 1.008) times more likely to survive to weaning (p<0.05). The opposite relationship, however, was seen in triplet lambs. For each additional second required for triplet-born lambs to follow their dam, lambs were 0.996 (95% CI 0.993 to 0.999) times as likely to survive to weaning (p<0.05). During the maternal recognition test, twin-born lambs were 0.989 (95% CI 0.979 to 1.000) times as likely to survive to weaning for every additional second they took to reach the contact zone (p<0.05). Similarly, triplet-born lambs were 0.994 (95% CI 0.989 to 0.999) as likely to survive for every additional second they took to reach their dam (p<0.05). Conclusion: All ewe behaviours and the majority of lamb paddock and test behaviours were not associated with the survival of twin-or triplet-born lambs and, therefore, are of little use as indicators of lamb survival to weaning.

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“…The IN consisted of 8 genetically linked flocks located in each of the major sheep growing areas of Australia (Armidale, NSW; Trangie, NSW; Cowra, NSW; Rutherglen, VIC; Hamilton, VIC; Struan, SA; Turretfield, SA; and Katanning, WA) and managed by Sheep CRC partner organizations. The design of the IN, including procedures used to select the sires to artificially inseminate the founding dams and the management procedures, have been described Geenty et al, 2014). All sires were used at 2 sites (Armidale and Katanning) and at least 50% of the sires were used at all the sites.…”

Section: Animalsmentioning

confidence: 99%

Genetic parameters for wool traits, live weight, and ultrasound carcass traits in Merino sheep1

Mortimer

Hatcher

Fogarty

et al. 2017

Journal of Animal Science

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ABSTRACT:Genetic correlations between 29 wool production and quality traits and live weight and ultrasound fat depth (FAT) and eye muscle depth (EMD) traits were estimated from the Information Nucleus (IN). The IN comprised 8 genetically linked flocks managed across a range of Australian sheep production environments. The data were from a maximum of 9,135 progeny born over 5 yr from 184 Merino sires and 4,614 Merino dams. The wool traits included records for yearling and adult fleece weight, fiber diameter (FD), staple length (SL), fiber diameter CV (FDCV), scoured color, and visual scores for breech and body wrinkle. We found high heritability for the major yearling wool production traits and some wool quality traits, whereas other wool quality traits, wool color, and visual traits were moderately heritable. The estimates of heritability for live weight generally increased with age as maternal effects declined. Estimates of heritability for the ultrasound traits were also higher when measured at yearling age rather than at postweaning age. The genetic correlations for fleece weight with live weights were positive (favorable) and moderate (approximately 0.5 ± 0.1), whereas those with FD were approximately 0.3 (unfavorable).The other wool traits had lower genetic correlations with the live weights. The genetic correlations for FAT and EMD with FD and SL were positive and low, with FDCV low to moderate negative, but variable with wool weight and negligible for the other wool traits. The genetic correlations for FAT and EMD with postweaning weight were positive and high (0.61 ± 0.18 to 0.75 ± 0.14) but were generally moderate with weights at other ages. Selection for increased live weight will result in a moderate correlated increase in wool weight as well as favorable reductions in breech cover and wrinkle, along with some unfavorable increases in FD and wool yellowness but little impact on other wool traits. The ultrasound meat traits, FAT and EMD, were highly positively genetically correlated (0.8), and selection to increase them would result in a small unfavorable correlated increase in FD, moderately favorable reductions in breech cover and wrinkle, but equivocal or negligible changes in other wool traits. The estimated parameters provide the basis for calculation of more accurate Australian Sheep Breeding Values and selection indexes that combine wool and meat objectives in Merino breeding programs.

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Reproductive performance in the Sheep CRC Information Nucleus using artificial insemination across different sheep-production environments in southern Australia

Cited by 60 publications

References 21 publications

Risk factors associated with lambing traits

Risk factors associated with lambing traits

Behaviour of twin- and triplet-born lambs and their dam 3 to 18 hours after birth is not a useful predictor of lamb survival to weaning

Genetic parameters for wool traits, live weight, and ultrasound carcass traits in Merino sheep1

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