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    The influence of the number of lambs present on the suckling behaviour of triplet-rearing ewes at pasture
    (Taylor and Francis Group, 2024-01-01) Corner-Thomas RA; Shanks R; Beausoleil NJ; Sneddon N
    This study examined the suckling behaviour of triplet-rearing ewes for three days post-parturition. Twenty-six ewes were enrolled with 11 being observed for the entire 3-days post-lambing. The behaviour of the ewe, number of lambs present at the end of the event and the behaviour that terminated the event were recorded for each suckling event. The mean suckling event duration increased when additional lambs were present at the end of the suckling event. Ewes that had observations across all three days showed no change in the number of suckling events over time, but suckling events tended to be shorter on day 3 than on days 1 or 2. On day 1 more suckling events were terminated by the ewe walking away from her lambs than on days 2 and 3. The odds of a ewe walking away to terminate the suckling event were greater when three lambs were present compared with two. Ewes showed more inactive behaviours when more lambs were present at the end of the suckling event. The results partially supported the hypothesis that the ewe would be more likely to terminate a suckling event when three lambs were attempting to suck compared with one or two lambs.
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    Ewe Wastage in New Zealand Commercial Flocks: Extent, Timing, Association with Hogget Reproductive Outcomes and BCS
    (MDPI (Basel, Switzerland), 2021-03-11) Flay KJ; Ridler AL; Compton CWR; Kenyon PR
    Ewe wastage is the combination of on-farm mortality and premature culling. Internationally, there is limited research on actual wastage incidence and causes in commercial sheep flocks. To the authors' knowledge, this is the first study that reports both lifetime wastage and detailed annual wastage in a sample of commercial New Zealand flocks. This study utilized data collected from 13,142 ewes from four cohorts on three commercial New Zealand farms (Farm A 2010-born, Farm A 2011-born, Farm B, Farm C), during the period 2011-2017, as they aged from replacement hoggets to 6-year-old ewes (Farm A and Farm B) or 3-year-old ewes (Farm C). Data collection visits occurred at three or four key management times each year, namely pre-mating, pregnancy diagnosis, pre-lambing and weaning. At each visit, body condition score (BCS) was assessed and any ewes that were culled or had died on farm were recorded. As this was a lifetime study, each ewe was assigned an outcome and corresponding 'exit age'. By the end of the study, all ewes that had exited their respective flocks, were classified as either prematurely culled, or dead/missing, or if still in the flock, as censored, and either the exact date or interval in which they exited the flock was recorded. Semi-parametric competing risk (premature culling vs. dead/missing), interval-censored survival models were developed to: 1. describe the association between hogget reproductive outcomes and risk of subsequent wastage, and 2. assess pre-mating BCS as a predictor of wastage in that production year. Of the 13,142 enrolled ewes, 50.4% exited their respective flocks due to premature culling and 40.0% due to on-farm dead/missing, giving a total of 90.4% that exited due to wastage. Annual mortality incidence ranged from 3.5 to 40.2%. As a hogget, wastage incidence ranged from 7.6 to 45.4%. Pregnancy or rearing a lamb as a hogget did not increase risk of subsequent wastage. In all years, pre-mating BCS was a predictor of ewe wastage, with odds of wastage lower with increasing BCS. Therefore, farmers should focus on improving pre-mating BCS to 3.5/5.0 by assessing ewe BCS at weaning, allowing poorer-BCS ewes to be managed to gain BCS before re-breeding.
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    Factors Associated with Mortality of Lambs Born to Ewe Hoggets
    (MDPI (Basel, Switzerland), 2022-02) Ridler AL; Flay KJ; Kenyon PR; Blair HT; Corner-Thomas RA; Pettigrew EJ
    The reproductive performance of ewe hoggets is poorer than that of mature-age ewes due to production of fewer lambs with poorer survival. Scant data are available on the risk factors for, and causes of, the mortality for lambs born to ewe hoggets, the impact of ewe deaths on lamb loss, and the causes of death for lambs born to ewe hoggets vs. mature-age ewes lambing in the same circumstances. In this study, 297 lambs born to 1142 ewe hoggets were necropsied along with 273 lambs born to 1050 mature-age ewes. Low lamb birthweight, multiple litter size, and increasing ewe hogget average daily gain from breeding to late pregnancy were risk factors for lamb mortality. The most common cause of mortality for lambs born to ewe hoggets was stillbirth and the risk factors for stillbirth were similar to those for lamb mortality generally. Approximately 11% of ewe hoggets’ lamb deaths were due to the death of the dam. Causes of mortality differed between lambs born to ewe hoggets vs. those born to mature-age ewes. Management practices to increase ewe hogget lambs’ birthweights (particularly those from multiple litters) and supervision of ewe hoggets at lambing time are recommended.