Monitoring liveweight in sheep is a valuable management strategy: a review of available technologies

Brown, D. J.; Savage, Darryl; Hinch, G. N.; Hatcher, S.

doi:10.1071/an13274

Cited by 40 publications

(17 citation statements)

References 69 publications

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“…While this does not appear to be a major loss in closely managed herds, further investigation is needed from commercial herds, particularly in the lower-rainfall and pastoral regions, where nutritional stress may be more likely. Walk-over-weighing systems may offer a low-cost method to examine variation in liveweight change (Brown et al 2015) and relationships with fetal loss.…”

Section: Embryonic and Fetal Lossesmentioning

confidence: 99%

Reproductive performance in goats and causes of perinatal mortality: a review

et al. 2020

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Goat meat production is an expanding industry in Australia. However, there is limited data quantifying the levels of reproductive performance, particularly under extensively grazed rangeland conditions, which would inform interventions to improve performance. This review aimed to quantify the levels of reproduction, time and causes of reproductive wastage in goats. It considers the levels of fertility, fecundity, embryonic loss, fetal loss and post-natal survival reported under Australian conditions, and comparisons are made with international reports. Key management factors that may contribute to reproductive performance include breed, seasonality, nutritional conditions, and weather conditions at kidding. While goats are potentially prolific breeders, in Australia, the variation in weaning rate (kids/doe joined) among properties is large (51–165%), although the causes of this variation are not well defined. Generally, conception and kidding rates are high, although fetal loss associated with undernutrition is more likely in goats than sheep. As with sheep, perinatal losses are generally the largest source of wastage, with an average 20% kid mortality, but this level is influenced by litter size and appears to be higher under extensive rangeland systems. The causes of perinatal kid loss under Australian conditions are similar to those in sheep, with starvation–mismothering–exposure and dystocia or stillbirth the key causes. Studies are needed to accurately quantify the level and causes of reproductive wastage in commercial herds, including a range of management situations, to enable effective interventions to be developed.

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Section: Embryonic and Fetal Lossesmentioning

confidence: 99%

Reproductive performance in goats and causes of perinatal mortality: a review

et al. 2020

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“…Combined BCS and BW measurements are considered to be typical and relatively easily BW = body weight; BCS = body condition score; M = mating; Pa = early pregnancy; Pb = midpregnancy; L = lambing; Sa = early suckling; Sb = midsuckling; W = weaning; Wp = postweaning. monitored parameters to describe the level of BR in sheep (Thorup et al, 2012;Brown et al, 2015;Morel et al, 2016;Puillet and Martin, 2017). Very few studies, however, are available in the literature regarding BR dynamics over complete and successive production cycles.…”

Section: Overall Br Dynamicsmentioning

confidence: 99%

Genetic analysis of robustness in meat sheep through body weight and body condition score changes over time1

Macé

García

Pradel³

et al. 2018

Journal of Animal Science

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Animal robustness may be defined as a complex trait characterizing the ability of an individual to be adapted, productive and healthy under contrasted and fluctuating environmental situations. Such a trait is now considered an essential criterion in order to meet the more ambitious goals of farming sustainability. In ruminants, one of the key mechanisms via which robustness is expressed is the capacity to mobilize or restore body reserves (BR) to cope with the challenges of negative energy balances. The objectives of this work were as follows: 1) to estimate the genetic parameters related to BR dynamics in ewes over successive production cycles and 2) to investigate BR management relationships between different physiological stages. For this, historical individual BW and BCS data from 2,920 phenotyped ewes were used for genetic analysis. The changes in BW (∆BW) and BCS (∆BCS) over time were analyzed. Eight physiological stages were considered to investigate these changes over time: mating, early pregnancy, mid-pregnancy, lambing, early suckling, mid-suckling, weaning, and postweaning. The estimated heritability were low for both ∆BW (h2 = 0.13 to 0.18) and ∆BCS (h2 = 0.04 to 0.16). Moderate to high positive genetic correlations (from 0.48 to 0.91) were obtained between BR mobilization phases and between BR accretion phases. Similarly, moderate to high negative genetic correlations (from -0.36 to -0.75) were estimated between the BR mobilization and accretion periods, suggesting that mechanisms driving BR mobilization and accretion processes were genetically correlated. This is the first study in ruminants that demonstrate that the extent and temporal changes in profiles of BR mobilization and accretion are heritable and genetically linked, indicating that such traits could be considered in genetic programs aimed at improving robustness. Nevertheless, further research is needed for a more comprehensive understanding of BR dynamics, notably by including other physiological parameters (i.e., metabolites and hormones) and additional information on the productive and reproductive life of the ewe.

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“…BCS is not a perfect proxy as the relationship between liveweight and BCS varies between flocks and also varies within flock throughout the year (SCA, 1990;McGregor, 2010;. Furthermore, liveweight and BCS comparisons between groups of sheep can be confounded with frame size (SCA, 1990;Brown et al, 2015).…”

Section: Introductionmentioning

confidence: 98%