Reproductive Performance of Triplet-Bearing Ewes on Commercial Farms and Research Priorities Identified by Sheep Producers to Improve the Survival of Triplet-Bearing Ewes and Their Lambs

Abstract

Consultation with sheep producers was used to quantify the mortality of triplet-bearing ewes and their lambs, identify management practices adopted by producers to reduce these losses and prioritise future research needs to improve the survival of triplet-bearing ewes and their lambs. Surveys were completed by 64 producers across Australia who identified and separated triplet-bearing ewes from twin-bearing ewes in 2017 and/or 2018. On average, 5.9% of all ewes mated were identified as carrying triplets (6.6% of non-Merino ewes and 2.9% of Merino ewes). The average mortality of triplet-bearing ewes was 6.4%, and ewe mortality did not differ significantly between ewe breeds. The average survival of triplet-born lambs was 59%, and survival was significantly higher for lambs from non-Merino compared to Merino ewes (60.1 vs. 52.9%, p < 0.05). The key strategies adopted to reduce the mortality of triplet-bearing ewes and their lambs included management of condition score, feed-on-offer, mob size at lambing and use of shelter. There were no differences (p > 0.05) in the average mortality of triplet-bearing ewes or their lambs between producers that prioritised the adoption of certain management practices. However, significant variation existed between producers in their targets at lambing for ewe condition score (2.8 to 3.5), mob size (10 to 150 ewes) and feed-on-offer (800 to 2500 kg dry matter/ha). Overwhelmingly, the highest priorities for further research identified by producers from surveys, workshops and a webinar were ewe condition score, mob size, feed-on-offer at lambing and mineral supplementation. This study informs benchmarks for mortality of triplet-bearing ewes and their lambs under extensive grazing conditions in Australia, and the priorities for future research to reduce these losses.

Perspective: science and the future of livestock industries

“…Responses to these challenges will always be founded on solid science, and the solutions will be diverse and multidisciplinary, as will the opportunities for research. Rather than offer an impossible list, I will confine my suggestions to research in reproduction: (i) Olfactory memory in the context of both the male effect and mother-young bonding; (ii) DoHaD and epigenetics, perhaps the ‘hottest’ current topic in reproductive biology; (iii) Embryo mortality, traditionally a very difficult research topic but now vulnerable to new tools for quantifying and investigating the problem; (iv) Postnatal survival, often dismissed as a problem confined to multiple births, but multiple births will be essential in future production systems, so it is time to take on the challenge ( 49 ). Importantly, the 100% CGE model ( 16 ) is not going to be applicable to all industries in all geographical or socio-economic environments, but individual aspects of the model can be introduced in a planned process ( 50 , 51 ) that needs to be supported by local applied research.…”

Management of Body Condition Score between Pregnancy Scanning and Lamb Marking Impacts the Survival of Triplet-Bearing Ewes and Their Lambs

“…The number of lambs weaned per ewe joined under pastoral systems, such as in Australia and New Zealand, has risen by 10 to 20% over the last twenty years [ 4 , 5 ]. However, a consequence of greater fecundity is an increase in the number of triplet-bearing ewes within a flock [ 6 , 7 ]. Triplet-born lambs are smaller at birth, can be metabolically challenged, and receive less colostrum and milk than their twin counterparts, contributing to lower survival to weaning [ 8 ].…”

“…Triplet-born lambs are smaller at birth, can be metabolically challenged, and receive less colostrum and milk than their twin counterparts, contributing to lower survival to weaning [ 8 ]. In addition, although data are somewhat sparse, triplet-bearing ewes themselves have lower survival during late-pregnancy and in lactation compared to single- and twin-bearing ewes [ 7 , 9 ], and this lower survival has a negative impact on lamb survival [ 5 , 7 ]. Australian producers who scanned their ewes for triplets were surveyed in 2018 and reported that the average mortality of triplet-bearing ewes between pregnancy scanning and marking was 6.4% and ranged from 0 to 27%, regardless of breed.…”

“…Australian producers who scanned their ewes for triplets were surveyed in 2018 and reported that the average mortality of triplet-bearing ewes between pregnancy scanning and marking was 6.4% and ranged from 0 to 27%, regardless of breed. However, the reported survival of triplet-born lambs was significantly higher for Maternals, comprising composite and crossbred breeds, than Merinos (60.1% vs. 52.9%) [ 7 ]. Therefore, developing management guidelines for triplet-bearing ewes to increase survival of the ewes and their lambs will improve productivity and animal welfare.…”

“…A recent survey of sheep producers in Australia reported that many producers ranked BCS at lambing as the management practice of highest priority for further research to understand the impacts on the survival of triplet-bearing ewes and their lambs [ 7 ]. There was no apparent difference in the survival of triplet-bearing ewes and their lambs between farms that did or did not rank BCS as a high priority.…”