Special Issue "Hogget Production and Longevity"

A special issue of Animals (ISSN 2076-2615). This special issue belongs to the section "Small Ruminants".

Deadline for manuscript submissions: 30 October 2021.

Special Issue Editor

Dr. Rene Anne Corner-Thomas
E-Mail Website
Guest Editor
School of Agriculture and Environment, Private Bag 11-222, Massey University, Palmerston North 4442, New Zealand
Interests: sheep production; hogget breeding; lamb survival; welfare

Special Issue Information

Ewe productivity is the principal driver of profit for dual-purpose ewe flocks. Ewe longevity further influences farm profitability by influencing the ewe replacement rate and the genetic gain and selection pressure that can be achieved. Hogget (ewe lamb) productive potential is influenced by their management in early life, with rapid growth rates from weaning at 3 months of age maximising productivity through the early attainment of puberty, increased reproductive performance, accelerated lamb growth rates and reaching target mature body size. Hogget breeding faces a number of challenges, including low and variable reproductive performance, low lamb birth weights and the need to ensure that the ewe herself continues to grow during pregnancy and lactation. For dual-purpose ewes, the assessment of productivity is based on lamb weaning, which is the culmination of events that occur prior to and during breeding, throughout pregnancy and finally during lactation. The aim of this Special Issue is to bring together contributions that provide the latest findings relating to the drivers of hogget productivity and longevity and literature reviews that summarise our current knowledge.

Dr. Rene Anne Corner-Thomas
Guest Editor

Manuscript Submission Information

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Keywords

  • conception
  • fecundity
  • growth
  • fetal loss
  • embryo loss
  • longevity
  • lamb survival
  • genetic selection
  • mortality

Published Papers (3 papers)

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Research

Article
Determining the Impact of Hogget Breeding Performance on Profitability under a Fixed Feed Supply Scenario in New Zealand
Animals 2021, 11(5), 1303; https://doi.org/10.3390/ani11051303 - 30 Apr 2021
Viewed by 478
Abstract
Hoggets (ewe lambs aged 4 to 16 months) can be bred from approximately 8 months of age for potentially increased flock production and profit, however most New Zealand hoggets are not presented for breeding and their reproductive success is highly variable. Bio-economic modelling [...] Read more.
Hoggets (ewe lambs aged 4 to 16 months) can be bred from approximately 8 months of age for potentially increased flock production and profit, however most New Zealand hoggets are not presented for breeding and their reproductive success is highly variable. Bio-economic modelling was used to analyse flock productivity and profit in four sets of scenarios for ewe flocks with varying mature ewe (FWR) and hogget (HWR) weaning rate combinations. Firstly, hogget breeding was identified to become profitable when break-even HWRs of 26% and 28% were achieved for flocks with FWRs of 135% and 150%, respectively. Secondly, relatively smaller improvements in FWR were identified to increase profit to the same level as larger improvements in HWR. Thirdly, a high performing flock with FWR and HWR both ≥ the 90th percentile currently achieved commercially, was the most profitable flock modelled. Fourthly, a FWR was identified with which a farmer not wishing to breed hoggets could have the same profit as a farmer with a flock achieving current industry average FWR and HWR. Overall, the relative profit levels achieved by the modelled flocks suggest that more farmers should consider breeding their hoggets, though improvements in FWRs should be prioritised. Full article
(This article belongs to the Special Issue Hogget Production and Longevity)
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Article
Ewe Wastage in New Zealand Commercial Flocks: Extent, Timing, Association with Hogget Reproductive Outcomes and BCS
Animals 2021, 11(3), 779; https://doi.org/10.3390/ani11030779 - 11 Mar 2021
Cited by 1 | Viewed by 625
Abstract
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 [...] Read more.
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. Full article
(This article belongs to the Special Issue Hogget Production and Longevity)
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Article
The Effect of Age of Dam and Birth Rank on the Reproductive Performance of Ewes as One- and Two-Year-Olds
Animals 2021, 11(3), 770; https://doi.org/10.3390/ani11030770 - 10 Mar 2021
Cited by 1 | Viewed by 410
Abstract
Currently, 30–43% of New Zealand sheep farmers breed their ewe lambs, but few retain the offspring as replacements for their flock. No difference in lamb production as a yearling among singletons and twins born to ewe lambs and twins born to mature ewes [...] Read more.
Currently, 30–43% of New Zealand sheep farmers breed their ewe lambs, but few retain the offspring as replacements for their flock. No difference in lamb production as a yearling among singletons and twins born to ewe lambs and twins born to mature ewes has been reported, provided the ewe lambs had reached the 60–65% of their likely mature weight prior to breeding at seven to eight months of age. The aim of this experiment was to determine the lamb production from singletons and twins born to ewe lambs and twins born to mature ewes during their first two years of lambing. The experiment included 8-month-old ewes born as twins to mature ewes (M2, n = 135), singletons born to ewe lambs (L1, n = 135), and twins born to ewe lambs (L2, n = 88), bred during the same period to the same rams, over two years. The efficiency of lamb production (total litter weight at weaning divided by the pre-breeding weight of the ewe, for all ewes presented for breeding) after two years of production was not significantly different (p > 0.05) among the groups (0.40 ± 0.02, 0.39 ± 0.02, and 0.39 ± 0.03, for M2, L1, and L2, respectively). Full article
(This article belongs to the Special Issue Hogget Production and Longevity)
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Planned Papers

The below list represents only planned manuscripts. Some of these manuscripts have not been received by the Editorial Office yet. Papers submitted to MDPI journals are subject to peer-review.

  1. Title: Reproductive rate of Merino and Maternal ewe lambs at multiple sites across Australia and selecting ewes for breeding based on pre-mating live weight and condition score

Authors: A.N. Thompson, M.B. Ferguson, G. A. Kearney, L. Kuibel, C.A. Macleay, B.L. Paganoni J. Trompf, C.A. Rosales Nieto

Abstract: Ewe lambs that are heavier due to improved nutrition pre- and post-weaning consistently achieve puberty at a younger age, are more fertile and have a higher reproductive rate. Fatness in intimately linked to reproduction in a variety of species, and in this paper we hypothesized that pre-mating condition score would explain additional variance in reproductive rate of ewe lambs over and above liveweight. We also expected that if only a proportion of ewe lambs were presented for breeding then it would be more effective to select these on both pre-mating liveweight and condition score. To test these hypotheses, we analysed data from over 17,000 records from Merino and Maternal composite ewe lambs from 22 different flocks from across Australia. Maternal composite ewe lambs achieved a higher reproductive rate (96.9% vs 60.7%) than Merino ewe lambs. There were significant curvilinear relationships between pre-mating liveweight (P<0.001) or body condition score (P<0.001) and reproductive rate for both Merino and Maternal composite ewe lambs. If ewe lambs achieved 50 kg or condition score 3.5 at joining, the reproductive rates achieved were within 10% of the predicted maximum for Merino ewe lambs and 4% of the maximum for Maternal composite ewe lambs. There was a significant (P<0.001) quadratic effect of pre-mating body condition score on reproductive rate independent of the correlated changes in liveweight, and even at the same liveweight an extra 0.5 of a condition score up to 3.3 improved the reproductive rate for both Merino and Maternal composite ewe lambs by about 20%. Nevertheless, the results indicated that if only 50% of ewe lambs are selecting for breeding, then selection based on both liveweight and condition score only improved reproductive rate by 1 to 3% compared to selection on liveweight alone.

  1. Title: Interaction between age and live weight at mating of ewe lambs on their reproductive success

Authors: A.N. Thompson,, E. Bowen, J. Keiller, D. Pegler, G.A. Kearney and C.A. Rosales Nieto

Abstract: The younger ewe lambs can be mated successfully the easier they can be integrated with the mating of the adult ewe flock the following year. In this paper we tested the hypothesis that both liveweight and age of ewe lambs at mating would influence their reproductive rate and the survival of their progeny. To test this hypothesis, we analysed data from more than 10,000 maternal ewe lambs collected from 2010 to 2017 by ram breeders. The ewe lambs had full pedigree records including birth type, age and liveweight at mating plus records of the birthweight and survival of their progeny. The average liveweight and age at mating was 40.1 kg and 228 days. The reproductive rate and weaning rate responses to liveweight at mating were curvilinear (P<0.001) and if ewe lambs achieved 45 kg by mating their reproductive rate and weaning rate were within 5% of their maximum. There was also a quadratic (P<0.01) effect of age at mating on reproductive rate which increased only marginally when ewe lambs were older than 8 months at mating and there was no effect on reproductive rate beyond 8.5 months. By contract, the effects of age at mating on weaning rate were linear up to 10 months of age. Liveweight (P<0.001) and age (P<0.001) at mating both had significant positive effects on progeny birth weight when included in the same statistical model. The model predicted that an extra 10 kg of liveweight or one-month of age at mating independently increased the birth weight of their progeny by 0.16 kg. Surprisingly, liveweight at mating had no significant effect (P<0.1) on progeny survival whereas age at mating had a significant positive effect (P<0.001) that remained (P=0.05) even when birth weight was included. This data has contributed to whole farm modelling to determine the optimal age and liveweight for mating maternal ewe lambs.

  1. Title: The effects of age at first joining (7 or 19 months) and ewe genotype (Belclare, Suffolk x Belclare, >75% Suff) on ewe performance when lambing as 2-tooths and of their progeny until drafting for slaughter

Authors: Tim Keady, Prof J.P. Hanrahan

4. Title: Effect of breeding heavier ewe lambs at seven months of age on lamb production and efficiency over their first breeding seasons and their mature weight 

Authors: Emmanuelle Haslin, Rene A. Corner-Thomas, Paul R. Kenyon, Emma J. Pettigrew, Rebecca E. Hickson, Steve T. Morris and Hugh T. Blair

 Affiliation: School of Agriculture and Environment, Massey University, Palmerston North 4474, New Zealand.
Abstract: This experiment examined the effect of breeding heavier ewe lambs on lamb production and their efficiency over their first three breeding seasons. Two groups of ewe lambs were bred at seven months of age at an average pre-breeding live weight of either 47.9 ± 0.36 kg (Heavy; n = 135) or 44.9 ± 0.49 kg (Control; n = 135). Ewe live weight, number of lambs born and weaned, and lamb live weight were recorded until 39 months of age, and efficiency was calculated for each ewe. Although the total lamb production did not differ between treatments, when data were pooled, heavier ewe lambs at breeding had a greater number and weight of lambs at weaning over the three-year period. Breeding heavier ewe lambs had no effect on efficiency over the three-year period. There was, however, a positive relationship between ewe lamb breeding live weight and their mature weight. These results suggest that although breeding heavier ewe lambs had a positive effect on total lamb production, it had no effect on efficiency over the first three breeding seasons. Before final recommendations can be made, lifetime performance and longevity to five years of age of heavier ewe lambs at breeding is required.

 

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