Special Issue "Hogget Production and Longevity"
Deadline for manuscript submissions: 30 October 2021.
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
Manuscript Submission Information
Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.
Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Animals is an international peer-reviewed open access monthly journal published by MDPI.
Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1800 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.
- fetal loss
- embryo loss
- lamb survival
- genetic selection
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.
- 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.
- 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.
- 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.